User login
You Are When You Eat: Microbiome Rhythm and Metabolic Health
Similar to circadian rhythms that help regulate when we naturally fall asleep and wake up, microbial rhythms in our gut are naturally active at certain times of the day to help regulate our digestion.
Investigators from the University of California, San Diego sought out to track these microbial rhythms to determine whether aligning the times we eat to when our gut microbes are most active – time-restricted feeding (TRF) – can bolster our metabolic health. Their research was published recently in Cell Host & Microbe.
“Microbial rhythms are daily fluctuations in the composition and function of microbes living in our gut. Much like how our bodies follow an internal clock (circadian rhythm), gut microbes also have their own rhythms, adjusting their activities based on the time of day and when we eat,” said Amir Zarrinpar, MD, PhD, a gastroenterologist at UC San Diego School of Medicine, and senior author of the study.
Zarrinpar and his team were particularly interested in observing whether adopting the TRF approach counteracted the harmful metabolic effects often associated with consuming a high-fat diet.
The study is also notable for the team’s use of technology able to observe real-time microbial changes in the gut — something not previously attainable with existing metagenomics.
How the Study Evolved With New Tech
Researchers separated three groups of mice to analyze their microbiome activity: one on a high-fat diet with unrestricted access, another on the same high-fat diet within a TRF window of 8 hours per day, and a control group on a normal chow diet with unrestricted access.
“In mice, [their] microbial rhythms are well-aligned with their nocturnal lifestyle. For example, during their active (nighttime) period, certain beneficial microbial activities increase, helping digest food, absorb nutrients, and regulate metabolism,” said Zarrinpar. As a result, the team made sure the mice’s TRF window was at night or when they would normally be awake.
“We chose an 8-hour feeding window based on earlier research showing this time period allows mice to consume the same total calories as those with unlimited food access,” said Zarrinpar. “By controlling [the] calories in this way, we ensure any metabolic or microbial benefits we observe are specifically due to the timing of eating, rather than differences in total food intake.”
But before any observations could be made, the team first needed a way to see real-time changes in the animals’ gut microbiomes.
Zarrinpar and his team were able to uncover this, thanks to metatranscriptomics, a technique used to capture real-time microbial activity by profiling RNA transcripts. Compared with the more traditional technique of metagenomics, which could only be used to identify which genes were present, metatranscriptomics provided more in-depth temporal and activity-related context, allowing the team to observe dynamic microbial changes.
“[Metatranscriptomics] helps us understand not just which microbes are present, but specifically what they are doing at any given moment,” said Zarrinpar. “In contrast, metagenomics looks only at microbial DNA, which provides information about what microbes are potentially capable of doing, but doesn’t tell us if those genes are actively expressed. By comparing microbial gene expression (using metatranscriptomics) and microbial gene abundance (using metagenomics) across different diet and feeding conditions in [light and dark] phases, we aimed to identify how feeding timing might influence microbial activity.”
Because metagenomics focuses on stable genetic material, this technique cannot capture the real-time microbial responses to dietary timing presented in rapidly changing, short-lived RNA. At the same time, the instability of the RNA makes it difficult to test hypotheses experimentally and explains why researchers haven’t more widely relied on metatranscriptomics.
To overcome this difficulty, Zarrinpar and his team had to wait to take advantage of improved bioinformatics tools to simplify their analysis of complex datasets. “It took several years for us to analyze this dataset because robust computational tools for metatranscriptomic analysis were not widely available when we initially collected our samples. Additionally, sequencing costs were very high. To clearly identify microbial activity, we needed deep sequencing coverage to distinguish species-level differences in gene expression, especially for genes that are common across multiple types of microbes,” said Zarrinpar.
What They Found
After monitoring these groups of mice for 8 weeks, the results were revealed.
As predicted, “When mice have free access to a high-fat diet, their normal eating behavior changes significantly. Instead of limiting their activity and feeding to their active nighttime period, these mice begin to stay awake and eat during the day, which is their typical rest phase,” Zarrinpar explained.
“This unusual daytime activity interferes with important physiological processes. Consequently, the animals experience circadian misalignment, a condition similar to what human shift workers experience when their sleep-wake and eating cycles don’t match their internal biological clocks,” he continued. “This misalignment can negatively affect metabolism, immunity, and overall health, potentially leading to metabolic diseases.”
For the mice that consumed a high-fat diet within a TRF window, metabolic phenotyping demonstrated that their specific diet regimen had protected them from harmful high-fat induced effects including adiposity, inflammation, and insulin resistance.
Even more promising, the mice not only were protected from metabolic disruption but also experienced physiological improvements including glucose homeostasis and the partial restoration of the daily microbial rhythms absent in the mice with unrestricted access to a high-fat diet.
While the TRF approach did not fully restore the normal, healthy rhythmicity seen in the control mice, the researchers noted distinct shifts in microbial patterns that indicated time-dependent enrichment in genes attributed to lipid and carbohydrate metabolism.
Better Metabolic Health — and Better Tools for Researching It
Thankfully, the latest advancements in sequencing technology, including long-read sequencing methods, are making metatranscriptomics easier for research. “These newer platforms offer greater resolution at a lower cost, making metatranscriptomics increasingly accessible,” said Zarrinpar. With these emerging technologies, he believes metatranscriptomics will become a more standard, widely used method for researchers to better understand the influence of microbial activity on our health.
These tools, for example, enabled Zarrinpar and the team to delve deeper and focus on the transcription of a particular enzyme they identified as a pivotal influence in observable metabolic improvements: bile salt hydrolase (BSH), known to regulate lipid and glucose metabolism. The TRF approach notably enhanced the expression of the BSH gene during the daytime in the gut microbe Dubosiella newyorkensis, which has a functional human equivalent.
To determine why this happened, the team leveraged genetic engineering to insert several active BSH gene variants into a benign strain of gut bacteria to administer to the mice. The only variant to produce metabolic improvements was the one derived from Dubosiella newyorkensis; the mice who were given this BSH-expressing engineered native bacteria (ENB) had increased lean muscle mass, less body fat, lower insulin levels, enhanced insulin sensitivity, and better blood glucose regulation.
“It is still early to know the full clinical potential of this new BSH-expressing engineered native bacterium,” said Zarrinpar. “However, our long-term goal is to develop a therapeutic that can be administered as a single dose, stably colonize the gut, and provide long-lasting metabolic benefits.” Testing the engineered bacteria in obese and diabetic mice on a high-fat diet would be a next step to determine whether its potential indeed holds up. If proven successful, it could then be used to develop future targeted therapies and interventions to treat common metabolic disorders.
With this engineered bacteria, Zarrinpar and his team are hopeful that it alone can replicate the microbial benefits associated with following a TRF dietary schedule. “In our study, the engineered bacterium continuously expressed the enzyme DnBSH1, independently of dietary or environmental factors. As a result, the bacterium provided metabolic benefits similar to those seen with TRF, even without requiring the mice to strictly adhere to a TRF schedule,” said Zarrinpar.
“This suggests the exciting possibility that this engineered microbe might serve either as a replacement for TRF or as a way to enhance its beneficial effects,” he continued. “Further studies will help determine whether combining this ENB with TRF could provide additional or synergistic improvements in metabolic health.”
Looking Ahead
“As the pioneer of the single anastomosis duodenal switch which separates bile from food until halfway down the GI tract, I agree that bile is very important in controlling metabolism and glucose,” said Mitchell Roslin, MD, chief director of bariatric and metabolic surgery at Lenox Hill Hospital, and the Donald and Barbara Zucker School of Medicine, Hempstead, New York, who was not involved in the study. “Using enzymes or medications that work in the GI tract without absorption into the body is very interesting and has great potential. It is an early but exciting prospect.”
However, Roslin expressed some reservations. “I think we are still trying to understand whether the difference in microbiomes is the cause or effect/association. Is the microbiome the difference or is a different microbiome representative of a diet that has more fiber and less processed foods? Thus, while I find this academically fascinating, I think that there are very basic questions that need better answers, before we look at the transcription of bacteria.”
Furthermore, translating the metabolic results observed in mice to humans might not be as straightforward. “Small animal research is mandatory, but how the findings convert to humans is highly speculative,” said Roslin. “Mice that are studied are usually bred for medical research, with reduced genetic variation. Many animal models are more sensitive to time-restricted eating and caloric restriction than humans.”
While it requires further research and validation, this UC San Diego study nevertheless contributes to our overall understanding of host-microbe interactions. “We demonstrate that host circadian rhythms significantly influence microbial function, and conversely, these microbial functions can directly impact host metabolism,” said Zarrinpar. “Importantly, we now have a method to test how specific microbial activities affect host physiology by engineering native gut bacteria.”
Roslin similarly emphasized the importance of continued investment in exploring the microbial ecosystem inside us all. “There is wider evidence that bacteria and microbes are not just passengers using us for a ride but perhaps manipulating every action we take.”
A version of this article appeared on Medscape.com.
Similar to circadian rhythms that help regulate when we naturally fall asleep and wake up, microbial rhythms in our gut are naturally active at certain times of the day to help regulate our digestion.
Investigators from the University of California, San Diego sought out to track these microbial rhythms to determine whether aligning the times we eat to when our gut microbes are most active – time-restricted feeding (TRF) – can bolster our metabolic health. Their research was published recently in Cell Host & Microbe.
“Microbial rhythms are daily fluctuations in the composition and function of microbes living in our gut. Much like how our bodies follow an internal clock (circadian rhythm), gut microbes also have their own rhythms, adjusting their activities based on the time of day and when we eat,” said Amir Zarrinpar, MD, PhD, a gastroenterologist at UC San Diego School of Medicine, and senior author of the study.
Zarrinpar and his team were particularly interested in observing whether adopting the TRF approach counteracted the harmful metabolic effects often associated with consuming a high-fat diet.
The study is also notable for the team’s use of technology able to observe real-time microbial changes in the gut — something not previously attainable with existing metagenomics.
How the Study Evolved With New Tech
Researchers separated three groups of mice to analyze their microbiome activity: one on a high-fat diet with unrestricted access, another on the same high-fat diet within a TRF window of 8 hours per day, and a control group on a normal chow diet with unrestricted access.
“In mice, [their] microbial rhythms are well-aligned with their nocturnal lifestyle. For example, during their active (nighttime) period, certain beneficial microbial activities increase, helping digest food, absorb nutrients, and regulate metabolism,” said Zarrinpar. As a result, the team made sure the mice’s TRF window was at night or when they would normally be awake.
“We chose an 8-hour feeding window based on earlier research showing this time period allows mice to consume the same total calories as those with unlimited food access,” said Zarrinpar. “By controlling [the] calories in this way, we ensure any metabolic or microbial benefits we observe are specifically due to the timing of eating, rather than differences in total food intake.”
But before any observations could be made, the team first needed a way to see real-time changes in the animals’ gut microbiomes.
Zarrinpar and his team were able to uncover this, thanks to metatranscriptomics, a technique used to capture real-time microbial activity by profiling RNA transcripts. Compared with the more traditional technique of metagenomics, which could only be used to identify which genes were present, metatranscriptomics provided more in-depth temporal and activity-related context, allowing the team to observe dynamic microbial changes.
“[Metatranscriptomics] helps us understand not just which microbes are present, but specifically what they are doing at any given moment,” said Zarrinpar. “In contrast, metagenomics looks only at microbial DNA, which provides information about what microbes are potentially capable of doing, but doesn’t tell us if those genes are actively expressed. By comparing microbial gene expression (using metatranscriptomics) and microbial gene abundance (using metagenomics) across different diet and feeding conditions in [light and dark] phases, we aimed to identify how feeding timing might influence microbial activity.”
Because metagenomics focuses on stable genetic material, this technique cannot capture the real-time microbial responses to dietary timing presented in rapidly changing, short-lived RNA. At the same time, the instability of the RNA makes it difficult to test hypotheses experimentally and explains why researchers haven’t more widely relied on metatranscriptomics.
To overcome this difficulty, Zarrinpar and his team had to wait to take advantage of improved bioinformatics tools to simplify their analysis of complex datasets. “It took several years for us to analyze this dataset because robust computational tools for metatranscriptomic analysis were not widely available when we initially collected our samples. Additionally, sequencing costs were very high. To clearly identify microbial activity, we needed deep sequencing coverage to distinguish species-level differences in gene expression, especially for genes that are common across multiple types of microbes,” said Zarrinpar.
What They Found
After monitoring these groups of mice for 8 weeks, the results were revealed.
As predicted, “When mice have free access to a high-fat diet, their normal eating behavior changes significantly. Instead of limiting their activity and feeding to their active nighttime period, these mice begin to stay awake and eat during the day, which is their typical rest phase,” Zarrinpar explained.
“This unusual daytime activity interferes with important physiological processes. Consequently, the animals experience circadian misalignment, a condition similar to what human shift workers experience when their sleep-wake and eating cycles don’t match their internal biological clocks,” he continued. “This misalignment can negatively affect metabolism, immunity, and overall health, potentially leading to metabolic diseases.”
For the mice that consumed a high-fat diet within a TRF window, metabolic phenotyping demonstrated that their specific diet regimen had protected them from harmful high-fat induced effects including adiposity, inflammation, and insulin resistance.
Even more promising, the mice not only were protected from metabolic disruption but also experienced physiological improvements including glucose homeostasis and the partial restoration of the daily microbial rhythms absent in the mice with unrestricted access to a high-fat diet.
While the TRF approach did not fully restore the normal, healthy rhythmicity seen in the control mice, the researchers noted distinct shifts in microbial patterns that indicated time-dependent enrichment in genes attributed to lipid and carbohydrate metabolism.
Better Metabolic Health — and Better Tools for Researching It
Thankfully, the latest advancements in sequencing technology, including long-read sequencing methods, are making metatranscriptomics easier for research. “These newer platforms offer greater resolution at a lower cost, making metatranscriptomics increasingly accessible,” said Zarrinpar. With these emerging technologies, he believes metatranscriptomics will become a more standard, widely used method for researchers to better understand the influence of microbial activity on our health.
These tools, for example, enabled Zarrinpar and the team to delve deeper and focus on the transcription of a particular enzyme they identified as a pivotal influence in observable metabolic improvements: bile salt hydrolase (BSH), known to regulate lipid and glucose metabolism. The TRF approach notably enhanced the expression of the BSH gene during the daytime in the gut microbe Dubosiella newyorkensis, which has a functional human equivalent.
To determine why this happened, the team leveraged genetic engineering to insert several active BSH gene variants into a benign strain of gut bacteria to administer to the mice. The only variant to produce metabolic improvements was the one derived from Dubosiella newyorkensis; the mice who were given this BSH-expressing engineered native bacteria (ENB) had increased lean muscle mass, less body fat, lower insulin levels, enhanced insulin sensitivity, and better blood glucose regulation.
“It is still early to know the full clinical potential of this new BSH-expressing engineered native bacterium,” said Zarrinpar. “However, our long-term goal is to develop a therapeutic that can be administered as a single dose, stably colonize the gut, and provide long-lasting metabolic benefits.” Testing the engineered bacteria in obese and diabetic mice on a high-fat diet would be a next step to determine whether its potential indeed holds up. If proven successful, it could then be used to develop future targeted therapies and interventions to treat common metabolic disorders.
With this engineered bacteria, Zarrinpar and his team are hopeful that it alone can replicate the microbial benefits associated with following a TRF dietary schedule. “In our study, the engineered bacterium continuously expressed the enzyme DnBSH1, independently of dietary or environmental factors. As a result, the bacterium provided metabolic benefits similar to those seen with TRF, even without requiring the mice to strictly adhere to a TRF schedule,” said Zarrinpar.
“This suggests the exciting possibility that this engineered microbe might serve either as a replacement for TRF or as a way to enhance its beneficial effects,” he continued. “Further studies will help determine whether combining this ENB with TRF could provide additional or synergistic improvements in metabolic health.”
Looking Ahead
“As the pioneer of the single anastomosis duodenal switch which separates bile from food until halfway down the GI tract, I agree that bile is very important in controlling metabolism and glucose,” said Mitchell Roslin, MD, chief director of bariatric and metabolic surgery at Lenox Hill Hospital, and the Donald and Barbara Zucker School of Medicine, Hempstead, New York, who was not involved in the study. “Using enzymes or medications that work in the GI tract without absorption into the body is very interesting and has great potential. It is an early but exciting prospect.”
However, Roslin expressed some reservations. “I think we are still trying to understand whether the difference in microbiomes is the cause or effect/association. Is the microbiome the difference or is a different microbiome representative of a diet that has more fiber and less processed foods? Thus, while I find this academically fascinating, I think that there are very basic questions that need better answers, before we look at the transcription of bacteria.”
Furthermore, translating the metabolic results observed in mice to humans might not be as straightforward. “Small animal research is mandatory, but how the findings convert to humans is highly speculative,” said Roslin. “Mice that are studied are usually bred for medical research, with reduced genetic variation. Many animal models are more sensitive to time-restricted eating and caloric restriction than humans.”
While it requires further research and validation, this UC San Diego study nevertheless contributes to our overall understanding of host-microbe interactions. “We demonstrate that host circadian rhythms significantly influence microbial function, and conversely, these microbial functions can directly impact host metabolism,” said Zarrinpar. “Importantly, we now have a method to test how specific microbial activities affect host physiology by engineering native gut bacteria.”
Roslin similarly emphasized the importance of continued investment in exploring the microbial ecosystem inside us all. “There is wider evidence that bacteria and microbes are not just passengers using us for a ride but perhaps manipulating every action we take.”
A version of this article appeared on Medscape.com.
Similar to circadian rhythms that help regulate when we naturally fall asleep and wake up, microbial rhythms in our gut are naturally active at certain times of the day to help regulate our digestion.
Investigators from the University of California, San Diego sought out to track these microbial rhythms to determine whether aligning the times we eat to when our gut microbes are most active – time-restricted feeding (TRF) – can bolster our metabolic health. Their research was published recently in Cell Host & Microbe.
“Microbial rhythms are daily fluctuations in the composition and function of microbes living in our gut. Much like how our bodies follow an internal clock (circadian rhythm), gut microbes also have their own rhythms, adjusting their activities based on the time of day and when we eat,” said Amir Zarrinpar, MD, PhD, a gastroenterologist at UC San Diego School of Medicine, and senior author of the study.
Zarrinpar and his team were particularly interested in observing whether adopting the TRF approach counteracted the harmful metabolic effects often associated with consuming a high-fat diet.
The study is also notable for the team’s use of technology able to observe real-time microbial changes in the gut — something not previously attainable with existing metagenomics.
How the Study Evolved With New Tech
Researchers separated three groups of mice to analyze their microbiome activity: one on a high-fat diet with unrestricted access, another on the same high-fat diet within a TRF window of 8 hours per day, and a control group on a normal chow diet with unrestricted access.
“In mice, [their] microbial rhythms are well-aligned with their nocturnal lifestyle. For example, during their active (nighttime) period, certain beneficial microbial activities increase, helping digest food, absorb nutrients, and regulate metabolism,” said Zarrinpar. As a result, the team made sure the mice’s TRF window was at night or when they would normally be awake.
“We chose an 8-hour feeding window based on earlier research showing this time period allows mice to consume the same total calories as those with unlimited food access,” said Zarrinpar. “By controlling [the] calories in this way, we ensure any metabolic or microbial benefits we observe are specifically due to the timing of eating, rather than differences in total food intake.”
But before any observations could be made, the team first needed a way to see real-time changes in the animals’ gut microbiomes.
Zarrinpar and his team were able to uncover this, thanks to metatranscriptomics, a technique used to capture real-time microbial activity by profiling RNA transcripts. Compared with the more traditional technique of metagenomics, which could only be used to identify which genes were present, metatranscriptomics provided more in-depth temporal and activity-related context, allowing the team to observe dynamic microbial changes.
“[Metatranscriptomics] helps us understand not just which microbes are present, but specifically what they are doing at any given moment,” said Zarrinpar. “In contrast, metagenomics looks only at microbial DNA, which provides information about what microbes are potentially capable of doing, but doesn’t tell us if those genes are actively expressed. By comparing microbial gene expression (using metatranscriptomics) and microbial gene abundance (using metagenomics) across different diet and feeding conditions in [light and dark] phases, we aimed to identify how feeding timing might influence microbial activity.”
Because metagenomics focuses on stable genetic material, this technique cannot capture the real-time microbial responses to dietary timing presented in rapidly changing, short-lived RNA. At the same time, the instability of the RNA makes it difficult to test hypotheses experimentally and explains why researchers haven’t more widely relied on metatranscriptomics.
To overcome this difficulty, Zarrinpar and his team had to wait to take advantage of improved bioinformatics tools to simplify their analysis of complex datasets. “It took several years for us to analyze this dataset because robust computational tools for metatranscriptomic analysis were not widely available when we initially collected our samples. Additionally, sequencing costs were very high. To clearly identify microbial activity, we needed deep sequencing coverage to distinguish species-level differences in gene expression, especially for genes that are common across multiple types of microbes,” said Zarrinpar.
What They Found
After monitoring these groups of mice for 8 weeks, the results were revealed.
As predicted, “When mice have free access to a high-fat diet, their normal eating behavior changes significantly. Instead of limiting their activity and feeding to their active nighttime period, these mice begin to stay awake and eat during the day, which is their typical rest phase,” Zarrinpar explained.
“This unusual daytime activity interferes with important physiological processes. Consequently, the animals experience circadian misalignment, a condition similar to what human shift workers experience when their sleep-wake and eating cycles don’t match their internal biological clocks,” he continued. “This misalignment can negatively affect metabolism, immunity, and overall health, potentially leading to metabolic diseases.”
For the mice that consumed a high-fat diet within a TRF window, metabolic phenotyping demonstrated that their specific diet regimen had protected them from harmful high-fat induced effects including adiposity, inflammation, and insulin resistance.
Even more promising, the mice not only were protected from metabolic disruption but also experienced physiological improvements including glucose homeostasis and the partial restoration of the daily microbial rhythms absent in the mice with unrestricted access to a high-fat diet.
While the TRF approach did not fully restore the normal, healthy rhythmicity seen in the control mice, the researchers noted distinct shifts in microbial patterns that indicated time-dependent enrichment in genes attributed to lipid and carbohydrate metabolism.
Better Metabolic Health — and Better Tools for Researching It
Thankfully, the latest advancements in sequencing technology, including long-read sequencing methods, are making metatranscriptomics easier for research. “These newer platforms offer greater resolution at a lower cost, making metatranscriptomics increasingly accessible,” said Zarrinpar. With these emerging technologies, he believes metatranscriptomics will become a more standard, widely used method for researchers to better understand the influence of microbial activity on our health.
These tools, for example, enabled Zarrinpar and the team to delve deeper and focus on the transcription of a particular enzyme they identified as a pivotal influence in observable metabolic improvements: bile salt hydrolase (BSH), known to regulate lipid and glucose metabolism. The TRF approach notably enhanced the expression of the BSH gene during the daytime in the gut microbe Dubosiella newyorkensis, which has a functional human equivalent.
To determine why this happened, the team leveraged genetic engineering to insert several active BSH gene variants into a benign strain of gut bacteria to administer to the mice. The only variant to produce metabolic improvements was the one derived from Dubosiella newyorkensis; the mice who were given this BSH-expressing engineered native bacteria (ENB) had increased lean muscle mass, less body fat, lower insulin levels, enhanced insulin sensitivity, and better blood glucose regulation.
“It is still early to know the full clinical potential of this new BSH-expressing engineered native bacterium,” said Zarrinpar. “However, our long-term goal is to develop a therapeutic that can be administered as a single dose, stably colonize the gut, and provide long-lasting metabolic benefits.” Testing the engineered bacteria in obese and diabetic mice on a high-fat diet would be a next step to determine whether its potential indeed holds up. If proven successful, it could then be used to develop future targeted therapies and interventions to treat common metabolic disorders.
With this engineered bacteria, Zarrinpar and his team are hopeful that it alone can replicate the microbial benefits associated with following a TRF dietary schedule. “In our study, the engineered bacterium continuously expressed the enzyme DnBSH1, independently of dietary or environmental factors. As a result, the bacterium provided metabolic benefits similar to those seen with TRF, even without requiring the mice to strictly adhere to a TRF schedule,” said Zarrinpar.
“This suggests the exciting possibility that this engineered microbe might serve either as a replacement for TRF or as a way to enhance its beneficial effects,” he continued. “Further studies will help determine whether combining this ENB with TRF could provide additional or synergistic improvements in metabolic health.”
Looking Ahead
“As the pioneer of the single anastomosis duodenal switch which separates bile from food until halfway down the GI tract, I agree that bile is very important in controlling metabolism and glucose,” said Mitchell Roslin, MD, chief director of bariatric and metabolic surgery at Lenox Hill Hospital, and the Donald and Barbara Zucker School of Medicine, Hempstead, New York, who was not involved in the study. “Using enzymes or medications that work in the GI tract without absorption into the body is very interesting and has great potential. It is an early but exciting prospect.”
However, Roslin expressed some reservations. “I think we are still trying to understand whether the difference in microbiomes is the cause or effect/association. Is the microbiome the difference or is a different microbiome representative of a diet that has more fiber and less processed foods? Thus, while I find this academically fascinating, I think that there are very basic questions that need better answers, before we look at the transcription of bacteria.”
Furthermore, translating the metabolic results observed in mice to humans might not be as straightforward. “Small animal research is mandatory, but how the findings convert to humans is highly speculative,” said Roslin. “Mice that are studied are usually bred for medical research, with reduced genetic variation. Many animal models are more sensitive to time-restricted eating and caloric restriction than humans.”
While it requires further research and validation, this UC San Diego study nevertheless contributes to our overall understanding of host-microbe interactions. “We demonstrate that host circadian rhythms significantly influence microbial function, and conversely, these microbial functions can directly impact host metabolism,” said Zarrinpar. “Importantly, we now have a method to test how specific microbial activities affect host physiology by engineering native gut bacteria.”
Roslin similarly emphasized the importance of continued investment in exploring the microbial ecosystem inside us all. “There is wider evidence that bacteria and microbes are not just passengers using us for a ride but perhaps manipulating every action we take.”
A version of this article appeared on Medscape.com.
Why scratching is so contagious
If you’ve ever felt an urge to scratch after witnessing someone else relieve their own itch, you’re certainly not alone. Itching can be contagious and the phenomenon is so common it doesn’t just affect humans. Now researchers may understand why.
Some background: In a 2007 study led by Zhou-Feng Chen, PhD, professor of anesthesiology, psychiatry, and developmental biology at the Washington University in St. Louis, researchers discovered a specific gene, the GRPR (gastrin-releasing peptide receptor), in the spinal cord and a corresponding neuropeptide, GRP (gastrin-releasing peptide). Together, the GRP system was found to transmit the “itch information” from one’s skin to the spinal cord.
This discovery was further backed by 2017 findings when Dr. Chen and his colleagues closely observed the molecular and neural basis of contagious itch behavior in mice. “We played a video that showed a mouse scratching at a very high frequency to other mice,” said Dr. Chen. “We found that, indeed, the mice who watched the video also scratched.”
To determine the inner workings at play, the researchers used molecular mapping to reveal increased neuronal activity in the suprachiasmatic nucleus (SCN), a bilateral structure found in the hypothalamus of the mouse’s brain. In other words, this part of the mouse’s brain “lit up” when a mouse displayed contagious scratching behavior.
The researchers then decided to take this one step further by manipulating the amount of GRP in the hypothalamus. “When we deleted the GRP in the SCN, the mice stopped imitating the scratch,” Dr. Chen said. “When we injected more GRP into the SCN, the mice started scratching like crazy.”
Now, after more investigating and research published in 2022 in Cell Reports, Dr. Chen and his team suspect contagious itching may have just as much to do with our eyeballs as our skin and spinal cord. Why? The phenomenon begins with a visual component: Someone seeing another person scratching.
The researchers targeted mice’s retinal ganglion cells, a type of light-capturing neuron found near the inner surface of the retina. When those cells were disabled, all scratching stopped.
This recent study argues that a previously undiscovered visual pathway may exist between the retina and the brain – bypassing the visual cortex – to provide more immediate physical reactions to potential adverse situations.
There’s more (and it could be quite relatable to some people): After the mice watched a video of another mouse scratching for half an hour, the researchers measured the mice’s stress hormone levels, finding a significant increase. This suggested that exposure to impulsive, contagious scratching behavior may have caused heightened anxiety in the mice.
said Dr. Chen. “We humans also scratch a lot, sometimes as a way to unconsciously express our internal anxiety.”
The mice may have interpreted the scratching video as a sudden negative change to their environment that they had to prepare for. “Contagious behavior is actually a very efficient way to inform other animals of what’s coming,” Dr. Chen said. “When we see other people running in a panic, there is no time to think. You just run as fast as you can. This is another example of contagious behavior that is in your own interest to survive.”
As a result, Dr. Chen believes it’s fair to infer that contagious behavior, including yawning and emotional contagion, is merely an expression of a fundamental survival mechanism that has evolved over time. “The human being is just an imitation machine. It’s often very difficult for people to act independently or as a minority because you would be working against evolution,” said Dr. Chen.
Scott Ira Krakower, DO, a child and adolescent psychiatrist at Northwell Health in Glen Oaks, N.Y., (and not party to this research), seconds this sentiment. “In regard to the physical benefits of contagion, it acts as a permanent defense and helps build collective immunity,” he said. “The social benefits when it comes to empathy or social media contagion are also important to our development. It helps us understand, adapt, and connect with others.”
Observing how empathy operates as a socially contagious behavior is something Dr. Chen and his colleagues are interested in looking into in the future.
“The definition of empathy is the sharing of emotions,” Dr. Chen said. “Shared feelings are crucial for social bonding and mental health, and for other animals, like mice, this is also the case.” Previous studies have shown that mice do, in fact, experience empathy and share feelings of pain and fear with one another.
There is still much to be explored in the study of contagious behaviors and the components of the brain that are activated during such behavior. Dr. Chen and his team intend to, ahem, scratch that particular itch.
A version of this article first appeared on Medscape.com.
If you’ve ever felt an urge to scratch after witnessing someone else relieve their own itch, you’re certainly not alone. Itching can be contagious and the phenomenon is so common it doesn’t just affect humans. Now researchers may understand why.
Some background: In a 2007 study led by Zhou-Feng Chen, PhD, professor of anesthesiology, psychiatry, and developmental biology at the Washington University in St. Louis, researchers discovered a specific gene, the GRPR (gastrin-releasing peptide receptor), in the spinal cord and a corresponding neuropeptide, GRP (gastrin-releasing peptide). Together, the GRP system was found to transmit the “itch information” from one’s skin to the spinal cord.
This discovery was further backed by 2017 findings when Dr. Chen and his colleagues closely observed the molecular and neural basis of contagious itch behavior in mice. “We played a video that showed a mouse scratching at a very high frequency to other mice,” said Dr. Chen. “We found that, indeed, the mice who watched the video also scratched.”
To determine the inner workings at play, the researchers used molecular mapping to reveal increased neuronal activity in the suprachiasmatic nucleus (SCN), a bilateral structure found in the hypothalamus of the mouse’s brain. In other words, this part of the mouse’s brain “lit up” when a mouse displayed contagious scratching behavior.
The researchers then decided to take this one step further by manipulating the amount of GRP in the hypothalamus. “When we deleted the GRP in the SCN, the mice stopped imitating the scratch,” Dr. Chen said. “When we injected more GRP into the SCN, the mice started scratching like crazy.”
Now, after more investigating and research published in 2022 in Cell Reports, Dr. Chen and his team suspect contagious itching may have just as much to do with our eyeballs as our skin and spinal cord. Why? The phenomenon begins with a visual component: Someone seeing another person scratching.
The researchers targeted mice’s retinal ganglion cells, a type of light-capturing neuron found near the inner surface of the retina. When those cells were disabled, all scratching stopped.
This recent study argues that a previously undiscovered visual pathway may exist between the retina and the brain – bypassing the visual cortex – to provide more immediate physical reactions to potential adverse situations.
There’s more (and it could be quite relatable to some people): After the mice watched a video of another mouse scratching for half an hour, the researchers measured the mice’s stress hormone levels, finding a significant increase. This suggested that exposure to impulsive, contagious scratching behavior may have caused heightened anxiety in the mice.
said Dr. Chen. “We humans also scratch a lot, sometimes as a way to unconsciously express our internal anxiety.”
The mice may have interpreted the scratching video as a sudden negative change to their environment that they had to prepare for. “Contagious behavior is actually a very efficient way to inform other animals of what’s coming,” Dr. Chen said. “When we see other people running in a panic, there is no time to think. You just run as fast as you can. This is another example of contagious behavior that is in your own interest to survive.”
As a result, Dr. Chen believes it’s fair to infer that contagious behavior, including yawning and emotional contagion, is merely an expression of a fundamental survival mechanism that has evolved over time. “The human being is just an imitation machine. It’s often very difficult for people to act independently or as a minority because you would be working against evolution,” said Dr. Chen.
Scott Ira Krakower, DO, a child and adolescent psychiatrist at Northwell Health in Glen Oaks, N.Y., (and not party to this research), seconds this sentiment. “In regard to the physical benefits of contagion, it acts as a permanent defense and helps build collective immunity,” he said. “The social benefits when it comes to empathy or social media contagion are also important to our development. It helps us understand, adapt, and connect with others.”
Observing how empathy operates as a socially contagious behavior is something Dr. Chen and his colleagues are interested in looking into in the future.
“The definition of empathy is the sharing of emotions,” Dr. Chen said. “Shared feelings are crucial for social bonding and mental health, and for other animals, like mice, this is also the case.” Previous studies have shown that mice do, in fact, experience empathy and share feelings of pain and fear with one another.
There is still much to be explored in the study of contagious behaviors and the components of the brain that are activated during such behavior. Dr. Chen and his team intend to, ahem, scratch that particular itch.
A version of this article first appeared on Medscape.com.
If you’ve ever felt an urge to scratch after witnessing someone else relieve their own itch, you’re certainly not alone. Itching can be contagious and the phenomenon is so common it doesn’t just affect humans. Now researchers may understand why.
Some background: In a 2007 study led by Zhou-Feng Chen, PhD, professor of anesthesiology, psychiatry, and developmental biology at the Washington University in St. Louis, researchers discovered a specific gene, the GRPR (gastrin-releasing peptide receptor), in the spinal cord and a corresponding neuropeptide, GRP (gastrin-releasing peptide). Together, the GRP system was found to transmit the “itch information” from one’s skin to the spinal cord.
This discovery was further backed by 2017 findings when Dr. Chen and his colleagues closely observed the molecular and neural basis of contagious itch behavior in mice. “We played a video that showed a mouse scratching at a very high frequency to other mice,” said Dr. Chen. “We found that, indeed, the mice who watched the video also scratched.”
To determine the inner workings at play, the researchers used molecular mapping to reveal increased neuronal activity in the suprachiasmatic nucleus (SCN), a bilateral structure found in the hypothalamus of the mouse’s brain. In other words, this part of the mouse’s brain “lit up” when a mouse displayed contagious scratching behavior.
The researchers then decided to take this one step further by manipulating the amount of GRP in the hypothalamus. “When we deleted the GRP in the SCN, the mice stopped imitating the scratch,” Dr. Chen said. “When we injected more GRP into the SCN, the mice started scratching like crazy.”
Now, after more investigating and research published in 2022 in Cell Reports, Dr. Chen and his team suspect contagious itching may have just as much to do with our eyeballs as our skin and spinal cord. Why? The phenomenon begins with a visual component: Someone seeing another person scratching.
The researchers targeted mice’s retinal ganglion cells, a type of light-capturing neuron found near the inner surface of the retina. When those cells were disabled, all scratching stopped.
This recent study argues that a previously undiscovered visual pathway may exist between the retina and the brain – bypassing the visual cortex – to provide more immediate physical reactions to potential adverse situations.
There’s more (and it could be quite relatable to some people): After the mice watched a video of another mouse scratching for half an hour, the researchers measured the mice’s stress hormone levels, finding a significant increase. This suggested that exposure to impulsive, contagious scratching behavior may have caused heightened anxiety in the mice.
said Dr. Chen. “We humans also scratch a lot, sometimes as a way to unconsciously express our internal anxiety.”
The mice may have interpreted the scratching video as a sudden negative change to their environment that they had to prepare for. “Contagious behavior is actually a very efficient way to inform other animals of what’s coming,” Dr. Chen said. “When we see other people running in a panic, there is no time to think. You just run as fast as you can. This is another example of contagious behavior that is in your own interest to survive.”
As a result, Dr. Chen believes it’s fair to infer that contagious behavior, including yawning and emotional contagion, is merely an expression of a fundamental survival mechanism that has evolved over time. “The human being is just an imitation machine. It’s often very difficult for people to act independently or as a minority because you would be working against evolution,” said Dr. Chen.
Scott Ira Krakower, DO, a child and adolescent psychiatrist at Northwell Health in Glen Oaks, N.Y., (and not party to this research), seconds this sentiment. “In regard to the physical benefits of contagion, it acts as a permanent defense and helps build collective immunity,” he said. “The social benefits when it comes to empathy or social media contagion are also important to our development. It helps us understand, adapt, and connect with others.”
Observing how empathy operates as a socially contagious behavior is something Dr. Chen and his colleagues are interested in looking into in the future.
“The definition of empathy is the sharing of emotions,” Dr. Chen said. “Shared feelings are crucial for social bonding and mental health, and for other animals, like mice, this is also the case.” Previous studies have shown that mice do, in fact, experience empathy and share feelings of pain and fear with one another.
There is still much to be explored in the study of contagious behaviors and the components of the brain that are activated during such behavior. Dr. Chen and his team intend to, ahem, scratch that particular itch.
A version of this article first appeared on Medscape.com.
FROM CELL REPORTS
'Zombie viruses': Fascinating and a little frightening
Of all the consequences of climate change, here’s one nobody counted on.
A team of European researchers digging into Siberian permafrost discovered and revived 13 types of prehistoric viruses.
The researchers coined the isn’t-that-just-great term “zombie viruses” to describe previously dormant viruses that had been frozen in ice for tens of thousands of years – 27,000 to 48,500 years, in fact.
The first question is obvious: This is fascinating, but is it a good idea? We’re still dealing with a certain mutating virus our immune systems have never encountered before.
The second question: What does it mean?
No humans were harmed in this study
The quick answer: The viruses observed here were only able to infect amoebae. But viruses that can infect humans do indeed exist in environments like permafrost.
The possibility that an unearthed, unknown virus will one day appear from seemingly nowhere and result in another pandemic is not necessarily zero.
“There is an objective risk, and it is increasing,” says Jean-Michel Claverie, PhD, the lead researcher and an emeritus professor of genomics and bioinformatics at Aix-Marseille University in France. “However, we cannot put a number on this probability, specifically because we refuse to work with and revive human- and animal-infecting viruses. It would be much too dangerous.”
Based on Dr. Claverie and his team’s results, human- and animal-infecting viruses can indeed survive deep within the permafrost for extended periods of time.
“From our research, we can deduce that other viruses present in the permafrost are likely still infectious,” says Dr. Claverie. “By sequencing the total DNA, we can detect the presence of viruses similar to those infecting animals or humans today.”
That said, the chances of something catastrophic happening from, say, humans exposed to thawed permafrost are slim. “[The microbes] would be quick to decay once they’re exposed to heat, UV light, and oxygen,” he says.
Also, in places like Siberia where permafrost exists, people generally do not. So, some science fiction-inspired fears (we see you, fans of John Carpenter’s “The Thing”) are pretty unfounded. But if more people or companies begin to migrate toward the areas where these microbes are being released, the chances of a virus successfully infecting a host could be greater.
But what if ...
So, what would happen – hypothetically – if the next deadly virus to overtake our planet came from the Arctic permafrost? Would we even be remotely prepared?
“There is a small risk that a frozen virus that gets unearthed is able to start an infection chain that ends up in humans,” says Adrian Liston, PhD, an immunologist and senior group leader at the Babraham Institute, a life sciences research institute at the University of Cambridge in England. Dr. Liston was not involved in the research discussed here. “On the one hand, we would not have preexisting immunity against it, so the initial ability to combat the infection is low. On the other hand, the virus would not be adapted to infect (modern-day) humans, so the chance of an initial infection being successful for the virus is extremely low.”
That’s something a lot of folks don’t understand: Today’s viruses and other infectious microbes are infectious only because they exist today. They have evolved to work within our modern immune systems – for either good or ill.
“ ‘Entry events’ do happen, very rarely, and they can shape human evolution,” says Dr. Liston. “Major examples would be smallpox (a virus) and tuberculosis (a bacteria), which strongly influenced human evolution when they entered our species, selecting for the type of immune system that was able to fight them and killing off individuals with the ‘wrong’ type of immune system.”
And not all organisms are harmful.
“There are many, many microbes that are beneficial to humans,” Dr. Liston says. “But generally speaking, these are microbes that have evolved for millions of years to work in harmony with our body, such as our microbiome, or have been selected for thousands of years to do beneficial chores for us, like yeast in making bread or brewing beer.”
Some random frozen microbe is unlikely to affect us directly, but if it does, it is far more likely to be bad, Dr. Liston says.
For now, at least, we can rest easy knowing that Dr. Claverie and his team have no plans to revive dangerous viruses or retrieve more samples. “Because of the Russian-Ukrainian war, all of our collaborations have stopped. We are now focused on studying the viruses already in our lab and understanding how they replicate and interact with their cellular hosts,” he says.
If anything, zombie viruses can at least remind us about the constant increasing effects that climate change will have on our lives and planet in the near future.
“The most important take-home message is that climate change is going to create unexpected problems,” says Dr. Liston. “It isn’t simply changes to weather, climate events, and sea levels rising. A whole cascade of secondary problems will be generated. New infections, some of which could go pandemic, are almost certainly going to happen because of climate change.”
A version of this article first appeared on WebMD.com.
Of all the consequences of climate change, here’s one nobody counted on.
A team of European researchers digging into Siberian permafrost discovered and revived 13 types of prehistoric viruses.
The researchers coined the isn’t-that-just-great term “zombie viruses” to describe previously dormant viruses that had been frozen in ice for tens of thousands of years – 27,000 to 48,500 years, in fact.
The first question is obvious: This is fascinating, but is it a good idea? We’re still dealing with a certain mutating virus our immune systems have never encountered before.
The second question: What does it mean?
No humans were harmed in this study
The quick answer: The viruses observed here were only able to infect amoebae. But viruses that can infect humans do indeed exist in environments like permafrost.
The possibility that an unearthed, unknown virus will one day appear from seemingly nowhere and result in another pandemic is not necessarily zero.
“There is an objective risk, and it is increasing,” says Jean-Michel Claverie, PhD, the lead researcher and an emeritus professor of genomics and bioinformatics at Aix-Marseille University in France. “However, we cannot put a number on this probability, specifically because we refuse to work with and revive human- and animal-infecting viruses. It would be much too dangerous.”
Based on Dr. Claverie and his team’s results, human- and animal-infecting viruses can indeed survive deep within the permafrost for extended periods of time.
“From our research, we can deduce that other viruses present in the permafrost are likely still infectious,” says Dr. Claverie. “By sequencing the total DNA, we can detect the presence of viruses similar to those infecting animals or humans today.”
That said, the chances of something catastrophic happening from, say, humans exposed to thawed permafrost are slim. “[The microbes] would be quick to decay once they’re exposed to heat, UV light, and oxygen,” he says.
Also, in places like Siberia where permafrost exists, people generally do not. So, some science fiction-inspired fears (we see you, fans of John Carpenter’s “The Thing”) are pretty unfounded. But if more people or companies begin to migrate toward the areas where these microbes are being released, the chances of a virus successfully infecting a host could be greater.
But what if ...
So, what would happen – hypothetically – if the next deadly virus to overtake our planet came from the Arctic permafrost? Would we even be remotely prepared?
“There is a small risk that a frozen virus that gets unearthed is able to start an infection chain that ends up in humans,” says Adrian Liston, PhD, an immunologist and senior group leader at the Babraham Institute, a life sciences research institute at the University of Cambridge in England. Dr. Liston was not involved in the research discussed here. “On the one hand, we would not have preexisting immunity against it, so the initial ability to combat the infection is low. On the other hand, the virus would not be adapted to infect (modern-day) humans, so the chance of an initial infection being successful for the virus is extremely low.”
That’s something a lot of folks don’t understand: Today’s viruses and other infectious microbes are infectious only because they exist today. They have evolved to work within our modern immune systems – for either good or ill.
“ ‘Entry events’ do happen, very rarely, and they can shape human evolution,” says Dr. Liston. “Major examples would be smallpox (a virus) and tuberculosis (a bacteria), which strongly influenced human evolution when they entered our species, selecting for the type of immune system that was able to fight them and killing off individuals with the ‘wrong’ type of immune system.”
And not all organisms are harmful.
“There are many, many microbes that are beneficial to humans,” Dr. Liston says. “But generally speaking, these are microbes that have evolved for millions of years to work in harmony with our body, such as our microbiome, or have been selected for thousands of years to do beneficial chores for us, like yeast in making bread or brewing beer.”
Some random frozen microbe is unlikely to affect us directly, but if it does, it is far more likely to be bad, Dr. Liston says.
For now, at least, we can rest easy knowing that Dr. Claverie and his team have no plans to revive dangerous viruses or retrieve more samples. “Because of the Russian-Ukrainian war, all of our collaborations have stopped. We are now focused on studying the viruses already in our lab and understanding how they replicate and interact with their cellular hosts,” he says.
If anything, zombie viruses can at least remind us about the constant increasing effects that climate change will have on our lives and planet in the near future.
“The most important take-home message is that climate change is going to create unexpected problems,” says Dr. Liston. “It isn’t simply changes to weather, climate events, and sea levels rising. A whole cascade of secondary problems will be generated. New infections, some of which could go pandemic, are almost certainly going to happen because of climate change.”
A version of this article first appeared on WebMD.com.
Of all the consequences of climate change, here’s one nobody counted on.
A team of European researchers digging into Siberian permafrost discovered and revived 13 types of prehistoric viruses.
The researchers coined the isn’t-that-just-great term “zombie viruses” to describe previously dormant viruses that had been frozen in ice for tens of thousands of years – 27,000 to 48,500 years, in fact.
The first question is obvious: This is fascinating, but is it a good idea? We’re still dealing with a certain mutating virus our immune systems have never encountered before.
The second question: What does it mean?
No humans were harmed in this study
The quick answer: The viruses observed here were only able to infect amoebae. But viruses that can infect humans do indeed exist in environments like permafrost.
The possibility that an unearthed, unknown virus will one day appear from seemingly nowhere and result in another pandemic is not necessarily zero.
“There is an objective risk, and it is increasing,” says Jean-Michel Claverie, PhD, the lead researcher and an emeritus professor of genomics and bioinformatics at Aix-Marseille University in France. “However, we cannot put a number on this probability, specifically because we refuse to work with and revive human- and animal-infecting viruses. It would be much too dangerous.”
Based on Dr. Claverie and his team’s results, human- and animal-infecting viruses can indeed survive deep within the permafrost for extended periods of time.
“From our research, we can deduce that other viruses present in the permafrost are likely still infectious,” says Dr. Claverie. “By sequencing the total DNA, we can detect the presence of viruses similar to those infecting animals or humans today.”
That said, the chances of something catastrophic happening from, say, humans exposed to thawed permafrost are slim. “[The microbes] would be quick to decay once they’re exposed to heat, UV light, and oxygen,” he says.
Also, in places like Siberia where permafrost exists, people generally do not. So, some science fiction-inspired fears (we see you, fans of John Carpenter’s “The Thing”) are pretty unfounded. But if more people or companies begin to migrate toward the areas where these microbes are being released, the chances of a virus successfully infecting a host could be greater.
But what if ...
So, what would happen – hypothetically – if the next deadly virus to overtake our planet came from the Arctic permafrost? Would we even be remotely prepared?
“There is a small risk that a frozen virus that gets unearthed is able to start an infection chain that ends up in humans,” says Adrian Liston, PhD, an immunologist and senior group leader at the Babraham Institute, a life sciences research institute at the University of Cambridge in England. Dr. Liston was not involved in the research discussed here. “On the one hand, we would not have preexisting immunity against it, so the initial ability to combat the infection is low. On the other hand, the virus would not be adapted to infect (modern-day) humans, so the chance of an initial infection being successful for the virus is extremely low.”
That’s something a lot of folks don’t understand: Today’s viruses and other infectious microbes are infectious only because they exist today. They have evolved to work within our modern immune systems – for either good or ill.
“ ‘Entry events’ do happen, very rarely, and they can shape human evolution,” says Dr. Liston. “Major examples would be smallpox (a virus) and tuberculosis (a bacteria), which strongly influenced human evolution when they entered our species, selecting for the type of immune system that was able to fight them and killing off individuals with the ‘wrong’ type of immune system.”
And not all organisms are harmful.
“There are many, many microbes that are beneficial to humans,” Dr. Liston says. “But generally speaking, these are microbes that have evolved for millions of years to work in harmony with our body, such as our microbiome, or have been selected for thousands of years to do beneficial chores for us, like yeast in making bread or brewing beer.”
Some random frozen microbe is unlikely to affect us directly, but if it does, it is far more likely to be bad, Dr. Liston says.
For now, at least, we can rest easy knowing that Dr. Claverie and his team have no plans to revive dangerous viruses or retrieve more samples. “Because of the Russian-Ukrainian war, all of our collaborations have stopped. We are now focused on studying the viruses already in our lab and understanding how they replicate and interact with their cellular hosts,” he says.
If anything, zombie viruses can at least remind us about the constant increasing effects that climate change will have on our lives and planet in the near future.
“The most important take-home message is that climate change is going to create unexpected problems,” says Dr. Liston. “It isn’t simply changes to weather, climate events, and sea levels rising. A whole cascade of secondary problems will be generated. New infections, some of which could go pandemic, are almost certainly going to happen because of climate change.”
A version of this article first appeared on WebMD.com.