BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: gut bacteria

Gut Microbes Help to Advance Flu Vaccines

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On January 21, 2020

In Student Post

Beneficial Gut Bacteria

This September, a potentially monumental study was published in the scientific journal, Cell, reporting that researchers have confirmed that microbes present in the gut can change, lower, or jumpstart our immune response.  Previously research has only been done with other mammals such as mice, and this was the first study that linked the results to human subjects. Since most previous trials were conducted on other animals, researchers such as Dan Littman who studies microbiota at NYU School Of Medicine, emphasized there are likely to be large differences in the results for humans versus other animals.   

Specifically, researchers found that people who have not received a flu shot or had the flu within the past 3 years and then were administered broad spectrum antibiotics, produced lower levels of antibodies to the influenza virus. Those subjects who did not receive the antibiotics produced more antibodies to the flu virus. This publication is so noteworthy because previously so little actual human clinical trials were performed to understand the role of the human gut microbiome and its relationship to the strength of our immune response.  

Previous research on how the flu vaccine works and its varying efficiency among many people has been done.  In 2011, Bali Pulendran, an immunologist at Stanford University, found that increased activity in the gene receptor that recognizes the bacterial protein flagellin, the core part flagella, seemed to stand out as the one major change among how well the flu shot was working in varying groups of people.  This underscores the connection between the immune system’s recognition of bacteria (especially gut microbes) and  how well people may respond to the flu vaccine.  

In 2014, this research was followed by gene knockouts being given to mice for the receptor for bacterial flagellin in the flu shot.  The results showed that the mice who received the knockouts made were antibodies than the control mice in the trial.  The researchers suspected this reduction was controlled by the absence or presence of gut microbes and their ability to sense flagellin.  To confirm this, researchers followed up with separate trial in which mice’s microbiota were reduced by the administration of antibiotics before receiving the flu vaccine and control mice who did not receive the antibiotics so their microbiomes remained present.  The results again showed a link that gut microbiota play a role in levels of antibodies produced against their flu shot.  Because of these results, it seemed obvious to test the same situation with humans. 

The current study did just that and was designed as a Phase 1 clinical trial to determine if gut microbes are connected to the efficiency of flu vaccine immunity.   11 adults received broad spectrum antibiotics for 5 days and 11 served as the control and did not receive antibodies.  All subjects receive the influenza vaccine on day 4. The people who received the antibiotics had reduced levels of gut microbes.  However, no major difference was observed in response to the vaccine. These results prompted researchers to dig deeper and they next investigated people who had not had the flu shot or suffered from the flu virus within the last 3 years.  They wanted subjects that would be relatively clear of flu antibodies to begin with. They repeat a very similar study with 11 people, 5 receiving the antibiotics and 6 serving as controls. Everyone got the flu vaccine, but this time the results showed a marked difference in vaccine induced immunity.  Subjects who received antibiotics and had fewer microbes presents, made far fewer flu-specific antibodies.   

This research is very promising not only in the field of flu vaccination, but could reveal that changes to microbiota can have profound impacts on future vaccine development for a variety of pathogens.  Because the results were so tiring, Pulendran is continuing to research deeper into the relationship between gut bacteria and vaccines, for viruses that may affect us in the future. This holds promise for development of vaccines for a wide range of pathogens that attack the human race.  

 

Your Gut Microbiota Could be Influencing Mental Health Disorders: Could Psychiatric Medications Change This?

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On November 17, 2019

In Student Post

Mental Health and Gut Bacteria 

Newly published research in rodents and continuing research in humans explores the effects of psychiatric drugs, including antidepressants, on the composition of gut bacteria. They have examined how the effects on gut microbiota, typically caused by naturally occurring metabolic changes in the gut, may influence connection with the nervous system rendering some negative effects on mental health. The most common mental health conditions connected to changing composition of the gut microbiome are anxiety and depression. 

This comes from a recent study that Medical News Today has released, reporting on different bacteria that play a part in synthesizing neuroactive compounds in the gut. These neuroactive substances interact with the nervous system, influencing the likelihood of developing depression or anxiety. This research has been proved more extensively and directly in rodents, but the research in humans provides similar conclusions, allowing scientists to partially conclude the effects in humans–research on this topic in humans is likely to expand greatly in the near future. 

How can gut microbiota be affected by different psychotropics? 

The Study and Results:  

Provided this link between changing gut bacteria and mental health, researchers from University College Cork, in Ireland, set out to investigate this in rodents. First, the team “investigated the antimicrobial activity of psychotropics against two bacterial strain residents in the human gut, Lactobacillus rhamnosus and Escherichia coli.“The psychotropics that the researchers conducted this study with included fluoxetine, escitalopram, venlafaxine, lithium, valproate, and aripiprazole.

Then, the scientists studied “the impact of chronic treatment with these drugs” on the rats’ microbiota. The scientists gave the rodents psychiatric drugs for a period of 4 weeks, ending the study by inspecting the effects of the drugs on the rodents gut bacteria. They found that lithium and valproate, mood stabilizers that can treat conditions including bipolar disorder, raised the numbers of certain types of bacteria. These included Clostridium, Peptoclostridium. On the other hand, selective serotonin reuptake inhibitors (SSRIs), fluoxetine and escitalopram (both antidepressants), ceased the growth of bacterial strains such as Escherichia coli.

“We found that certain drugs, including the mood stabilizer lithium and the antidepressant fluoxetine, influenced the composition and richness of the gut microbiota,” says head researcher Sofia Cussotto. 

Conclusions from the Study, and what the Future Holds 

Dr. Serguei Fetissov, a professor of physiology at Rouen University, in France commented on the study, saying: “At the moment, it would be premature to ascribe a direct role of gut bacteria in the action of antidepressant drugs until this work can be reproduced in humans, which is what the authors now hope to do.”

However, the implications and further goals and hopes of this research is to directly prove that “psychotropic drugs might work on intestinal microbes as part of their mechanisms of action,” says Cussotto

Do you think it is too early to assume a direct connection between gut bacteria and mental health in humans? Comment about this below.

Further Research

https://www.medicalnewstoday.com/articles/amp/326299 

https://www.medicalnewstoday.com/articles/319117.php#1 

 

 

 

Can your bacteria reveal your age?

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On January 15, 2019

In Student Post

There are billions of bacteria all in, around, and all over you. They prevent diseases, regulate digestion, and everything in between. Researcher Alex Zhavoronkov and his colleagues at InSilico Medicine in Maryland c study and examine whether their predictions that “microbiomes are aging clocks” were true.

To start their study, Alex and his team gathered 3600 samples of gut bacteria from 1165 healthy individuals from around the world, ranging from three age samples. A third of the participants were aged 20 to 39, another third were aged 40 to 59, and the last third were from people aged 60 to 90. They then used machine learning. This means they trained a computer program on “95 different species of bacteria from 90% of the samples, along with the ages of the people they had come from. Then, they asked the algorithm to predict the ages of the people who provided the remaining 10%”. Their program ended up being successful in that 39 bacteria of the 95 were successful in predicting someone’s age within four years.

When researching the certain biomes, Eubacterium hallii-which is important for intestines and metabolisms-became more abundant with age. They also noticed bacteria like Bacteroides vulgatus decreased with age. Alex and his team predict that the different bacteria found may help in detecting peoples’ age.

If validated, the “microbiome aging clock” they created can have many positive effects. It could be used to compare healthy people with those who have diseases. It can test how fast someone is aging and test if any antibiotics, probiotics, diet, or alcohol affect aging. It could help test new treatments or medicine and see if it would have any effect on the aging process. However, challenges may arise. One may include distinguishing whether the different microbes come from age or come from “markedly different populations”. Researcher Robin Knight states, “ it’s also not known whether changes in the microbiome cause people to age more rapidly, or whether the changes are simply a side effect of aging”. It is not yet guaranteed how the aging-clock machine will turn out but if it ends up being successful, many would consider for it to be life-changing.  

Bacteria Not So “Bad”, After All?

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On January 18, 2018

In Student Post

Photo Link: Wild Garden of Gut Bacteria, By: Nicola Fawcett

Most of us are used to the common notion that bacteria may not be the most beneficial factor in maintaining your health.  Thats why the results of a recent research study conducted by scientists at Babraham Institute in collaboration with colleagues in Brazil and Italy, yielding evidence that in fact good bacteria in the gut can control gene expression in our cells, is game-changing!

The research team, led by Patrick Varga-Weisz, made this discovery by studying the gut bacterias found within various mice. Their attention was quickly drawn to the mice that had lost most of their gut bacteria. It became apparent that in the mice with a very low amount of the bacteria within their gut, contained increased amounts of the “HDAC2 protein”.  When investigating deeper into HDAC2, it was found that increased amounts of this particular protein are associated with increased risk of colorectal cancer.

This new research also resulted in the finding that the amount of chemical markers on our genes, are increased by short fatty acids. These specific chemical gene markers, known as “crotonylations”, were only recently discovered and are newly classified as genome “epigenetic markers”. The researchers then found that by shutting down the HDAC2 protein, short chain fatty acids increase the number of crotonylations.

Ingestion of fruits and vegetables into ones healthy diet are vital – ultimately determining how chemicals produced by gut bacteria, affect genes in the cells of the gut lining. In other words, the short fatty acids, which come from those dietary elements, have the ability to move from bacteria into our own cells, and from there cause changes in gene activity and cell behavior.

In the end, the scientists were strongly convinced that the ability to turn off and on genes, is determined by changes in crotonylation. This inferred that the existence of crotonylation in the genome of cells is vital to protect the body from cancer. Therefore, the pretense of good bacteria is very important for the prevention of disease and illness in the body!

As someone with a strong passion for the science, and also very influenced and intrigued by medicine, I very much enjoyed this study. As the boundary to curing cancer is still a hurtle doctors and scientists try to transcend everyday, studies like these, are both hopeful and fascinating, to me. Also, as someone curious about how the human diet ultimately affects the functions and inner workings of the body, this research again was very engaging and interesting!

Primary Source Article: How good bacteria controls your genes

Secondary Source: Wikipedia – Gut Flora (Gut Bacterias)

 

Possible Links Between Gut Microbes and Obesity, Cancer & Autism

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On January 17, 2017

In Student Post

While the bacteria in our gut play a vital role in the digestion process, recent findings have suggested that it could effect much more in our bodies. New studies have found possible links between the bacteria in our gut and obesity, cancer and autism.

Creative Commons image link

A study done by Cornell University and King’s College London revealed that Christensenellaceae minuta, a strain of gut bacteria, was found more often and in larger quantities in people with lower body masses. To investigate whether the bacteria is actually linked with obesity, researchers added the same bacteria into the guts of mice and compared their weight gain to mice lacking the bacteria. The research showed that the mice with Christensenellaceae minuta gained noticeably less weight than the mice lacking the bacteria. While research is still in its early stages, these results have made an exciting connection between bacteria in our gut and weight gain, which could dramatically impact the future of our health.

In addition to obesity, the bacteria in our gut has also been linked to cancer- in both beneficial and detrimental aspects. Researchers from the National Cancer Institute tested the effect of gut bacteria on chemotherapy in mice and found that the chemotherapy was significantly less effective in the mice lacking the bacteria. Similarly, another study found that cyclophosphamide, an antitumor drug, was less effective in mice with insufficient gut bacteria compared to those with normal levels. While these studies showed positive links between gut bacteria and cancer, other studies have found adverse effects of gut bacteria.

Unfortunately, a study published in The Journal of Cancer Research in 2012 has made a possible connection between Lactobacillus johnsonii, a strain of gut bacteria, and lymphoma, cancer of the white blood cells. The study claims that the presence of this specific strain of bacteria could lead to the development of lymphoma. Another study done in the UK in 2013 found that a specific gut bacterium, Helicobacter pylori, has the ability to deactivate the part of our immune system responsible for regulating inflammation. In effect, this could cause stomach cancer and ulcers.

While it may seem like a stretch, numerous studies have found a possible link to autism and the bacteria in our gut. A study done in 2013 by Arizona State University found that compared to children without autism, children suffering from autism had lower levels of Prevotella, Coprococcus and Veillonellaceae, three strains of gut bacteria. Even more surprisingly, another study revealed that the presence of Bacteroides fragilis in the gut reduced autism-like symptoms in mice. Research in this field is still in its primary stages, as researchers are trying to figure out if these connection are in fact related, and if so, how the bacteria directly effects these conditions.

 

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