Bone Marrow Transplants

In an informational video produced by Be The Match, bone marrow is defined as a factory that normally, if functioning properly, makes all the blood cells we see in the blood. Bone marrow also contains stem cells that are the “mother cells” that form all the cells in the blood. If these stem cells are damaged, this could affect our blood cell production. For someone who has dysfunctional bone marrow cells, a bone marrow transplant completely eliminates the bad cells in the marrow and replaces them with healthy stem cells. Essentially, a bone marrow transplant is just like a blood transfusion. You just hang the bag of blood and allow it to run in. However, the curative part of the transplant is actually the pre-treatment. When old bone marrow isn’t working, doctors will usually give patients high doses of chemotherapy, and sometimes radiation, to kill it off. Once the old bone marrow is out, this gives space for new cells to come in. The transplant itself can be more accurately referred to as the recovery. The donor cells rebuild your immune system after it had been completely wiped out by the chemo. As the donor cells engraft, red blood cells, white blood cells, and platelets recover to normal levels.

In a different video by Be The Match, it describes the process of HLA matching. HLA stands for human leukocyte antigens, which are proteins found on most of your cells in your body. There are many HLA markers unique to your body, and your immune system uses these markers to determine which cells belong in your body and which cells don’t. A close HLA match makes it more likely that your transplant will work and successfully treat your disease. HLA matching begins with a blood test, which is compared to other potential donors. Usually, doctors want to match between 8 and 10 HLA markers. Occasionally, patients can get healthy red blood cells from something called cord blood. Cord blood is one of three sources of blood-forming cells used in transplants. The blood is collected from the umbilical cord immediately after birth. For cord blood units, doctors may only need to match 4 to 6 HLA markers. HLA markers are inherited from your parents. You get half from your mom and half from your dad. Your siblings have a 1 and 4 chance of being a match. However, it was found that 7 out of 10 people won’t have a close match in their family.

From the Be The Match website, they talk about how ethnicity plays an important factor in matching. People who share ethnic background will be more likely to be an HLA match. Some ethnic groups have more complex tissue types than others, so a person’s best chance of finding a donor may be someone with the same ethnic background. In an article by Time magazine, according to the World Donor Marrow Association, 2 out of 3 white people find a bone marrow match, while the chances of a patient from a different ethnic background can be as low as 1 and 4. There have been notable improvements in bone marrow registries around the world, however, the global registry is still disproportionately represented by the US, UK, and Germany, which are all predominantly white countries. For a multiracial person, the chances of finding a match are very low.

From Be The Match.

New COVID Developments

With new variants being discovered and infection still spreading, COVID has been impacting our world for almost two years now. There is hope, however. Nobel Prize winner Jennifer Doudna and her team have developed new insight into the Delta variant, and how it has come to be much more infectious than regular SARS-CoV-2 strands. According to an article by Science Insider, she developed a new tool by experimenting with virus like particles (VLP). They built VLPs from various SARS-CoV-2 variants to get a better understanding on how changes to those proteins affect the virus’ properties. VLPs contain all of the virus’ structural protein, but lack its genome. This allows the VLP to bind with cells in a laboratory setting and invade them. However, without its genome it cannot invade other cell’s machinery to replicate and perform apoptosis in order to infect surrounding cells. Doudna describes this as a “one-way ticket,” because this means the VLP won’t spread!

What Doudna and her team did was insert a tiny bit of mRNA, which caused the cells that contained the VLP to light up and glow. The brighter the glow after infection with the VLP, the more mRNA the VLP has delivered. Doudna then tampered with the VLP’s proteins by inducing various mutations. She found that a single amino acid change in the Delta variant’s nucleocapsid, amplified the particles with more than 10 times the mRNA than the original virus. Therefore, this mutation allows the Delta variant to be better at making infectious particles and, in turn, spreading more quickly.

I think that this discovery is a big deal. With more and more experimentation occurring, we are able to crack down on the causes and pathogenesis of COVID. This allows us to get a better grasp on what we are dealing with here. The article explains that with this new finding on VLPs, researchers that do not have access to high-level biosafety are able to see how all four of the coronavirus proteins work together to create the virus, and examine how it invades other cells. This new technology with also give us a leg up on future variants that may arise. The reason why so many variants are arising is because not everyone is getting the vaccine. If more of our population were to receive the vaccine, it would allow us to reach herd immunity and the spread would severely decline.

COVID-19 virus.

Tuberculosis

In an article by the Center for Disease Control and Prevention (CDC), tuberculosis is known to be caused by a bacterium named Mycobacterium tuberculosis. This bacterium takes a strong liking to the lungs, but in general, it can attack any part of the human body. Humans is the only reservoir for this disease. Not everyone who is infected with the tuberculosis bacterium becomes infected. This gives rise to the two type of tuberculosis seen: latent TB infection (LTBI) and TB disease. Some symptoms of tuberculosis are a bad cough that lasts 3 weeks or longer, pain in the chest, coughing up blood or sputum, weakness, etc. Tuberculosis has an incubation period of about two to ten weeks.

Also stated in the article by the CDC, tuberculosis is spread in most people who breathe in the tuberculosis-causing bacterium and become infected. The tuberculosis is put into the air by people coughing, speaking, or singing. Usually, the body is able to fight against this bacterium and stop it from growing. This is the LTBI form of tuberculosis. Many people who have LTBI never actually develop the disease. The bacterium remains inactive for a lifetime, not causing any damage. In others, specifically immunocompromised individuals, the bacterium becomes active. Once active, it multiples and causes disease. For LTBI, there are several medication treatment regimens that are recommended. Some of the medications are: isoniazid, rifapentine, rifampin. For TB disease, it is treated by taking several different medications for six to nine months. The first-line anti-TB agents that are included in the medication regimen are: isoniazid, rifampin, ethambutol, and pyrazinamide. There is a tuberculosis vaccine called Bacille Calmette-Guérin (BCG), but it is not used heavily in the US. It is mostly used in countries where tuberculosis is most common, and it is given to young children and infants. This vaccine does not always protect people from getting tuberculosis.

In an article written by the World Health Organization (WHO), it was concluded that in 2020, 1.5 million people died from tuberculosis (this number is including 214,000 people with HIV). Also, in 2020 ten million people were diagnosed with tuberculosis. Of that, 5.6 million were men, 3.3 million were women, and 1.1 million were children. You see a disproportionate number of men contract this disease. This could be due to a lack of access to care or because of close contact conversations between someone who is infected with this disease. Tuberculosis is the 13^th leading cause of death in the world. There are eight countries that account for 86% of new tuberculosis tests in 2020. From most to least, they include: India, China, Indonesia, the Philippines, Pakistan, Nigeria, Bangladesh, and South Africa. Multidrug-resistant tuberculosis is becoming an increasing problem in the US, and threatens health security. Every one in three people in 2020 who was diagnosed with multidrug-resistant tuberculosis, were provided quality treatment.

Tuberculosis transmission.

CRISPR-Cas9 and the Human Genome

CRISPR (Clusters of Regularly Interspersed Short Palindromic Repeats) systems were discovered when scientists found bacterial genomes inside pieces of phage DNA. In an article written in Science in the News by Harvard University, they explain that CRISPR sequences are crucial to the body’s immune system. If a viral infection threatens a bacterial cell, the CRISPR immune system can stop that threat and destroy the genome of the incoming virus. By destroying the viral genome, the CRISPR immune system protects bacteria from ongoing viral infection. How it works is that a virus first needs to invade a bacterial cell. Then, a new spacer is made from the virus and is further integrated into a CRISPR sequence. Denise Anderson’s textbook “Nester’s Microbiology: A Human Perspective,” describes a spacer as an integrated segment of captured DNA. The spacer DNA gives a historical record of all the past infections your body has had. This is what allows surviving cells to recognize viruses you may have already encountered. The CRISPR sequence is transcribed and CRISPR RNA is formed. This RNA guides molecular machinery to target and destroy the invading viral genome.

How CRISPR editing works; Harvard University.

In an article about CRISPR-Cas9 use for cancer therapy by Chen, et al., they explain that CRISPR-Cas9 genome editing technology has been used in various cell types and organisms, both in vitro and in vivo, for efficient gene disruption and modification. This being said, it has shown hope for a treatment of cancer. This technology allows one to precisely manipulate almost any given genome sequence, further enabling one to eradicate genes involved in carcinogenesis and the correction of cancer-causing mutations. However, how these tools are delivered to target cells in vivo and how to reduce unintentional off-target effects is proving to be a large challenge. In addition, the constantly changing mutations resulting from cancer make it hard to pinpoint and kill mutations. This is the case for both CRISPR sequences and other genome editing tools used previously. CRISPR editing is more flexible and efficient due to its simpler and more accurate Watson-Crick basing pairing between RNA and target DNA, as opposed to previously used zinc-finger nucleases (ZFNs) and transcription activator like effector nucleases (TALENs).

In the US, there are limitations to how/where the CRISPR sequences and other germline genome editing can be used. In an article written in 2018 assessing the risks and benefits of human germline editing by Rubeis, Giovanni and Steger, Florian, supporters of germline editing claim that the procedure can be useful from a disease prevention standpoint. However, opponents claim that the medical and societal risks outweigh the benefits. With this editing technique, germ cells are altered, which allow the modified genes to be passed down from generation to generation. These modified genes could spread throughout the human genome pool and create unforeseeable consequences. An example this article gives is that of sickle cell anemia. This disease is a carrier against malaria, meaning if we fixed this gene, we would see in an increase in cases of malaria due to the eradication of sickle cell anemia and therefore, the malaria resistance gene. Opponents of gene therapy also state that this is a new level of interfering with nature and moving forward with it would be considered “irresponsible.” The societal risk identified is the idea that there could be the creation of two classes of human: the enhanced and non-enhanced. I believe that genome editing could be useful in helping eradicate life-threatening disease, but extensive research must be done and the topic must be addressed from multiple angles.  

Diet and the Microbiome

There is no question that a person’s diet has direct effects on their intestinal microbiota. Dieting can create a shift in the gut microbiota, but according to an article by Leeming, et.al talking about the effect of diet on the gut microbiota, these changes are temporary. They also talk about how it is unknown the effects of prolonged dietary changes on the gut microbiota because of a lack of long-term dietary interventions seen in humans, and because of a lack of long-term follow-ups of short-term dietary interventions. There is a possibility that habitual diets have a greater influence on the gut microbiota than acute dieting strategies. Through habitual dietary practices, we are able to select substrates that provide a competitive environment for gut microbiota. In an article written by Harvard Public Health, they talk about how high-fiber diets in particular affect the type and amount of microbiota in the intestines. Dietary fiber can only be broken down and then fermented by enzymes that live in the microbiota of the colon. Short fatty acid chains are released as result of this fermentation, in turn lowering the pH of the colon and becoming a determining factor of what microbiota are present. Only microbiota that can live in this acidic environment can survive, which limits the growth of harmful bacteria such as C. diff.

One food that I learned has a surprisingly large amount of sugar in it is pasta sauce. Pasta is one of my go to comfort foods because it is easy to make and fills me up. Pasta sauce can have 6-12 grams of sugar per half cup. The serving size for pasta sauce per person is about 2 to 4 ounces (1/4 to ½ a cup). In Rao’s homemade marinara sauce (which is the sauce I usually use), the serving size is ½ cup. There are 6 grams of carbohydrates, which includes 4 grams of total sugars and 1 gram of dietary fiber. Another food that has a surprising amount of sugar in it is barbecue sauce. Just two tablespoons can contain up to 15 grams of sugar. All those trips to the McDonalds on Franklin street at 1am where I get fries and barbecue sauce are catching up to me. On the Sweet Baby Ray’s nutrition label, the first ingredient on the list is high fructose corn syrup, which is a form of sugar.

Sweet Baby Ray’s nutrition label.

Rao’s Homemade Pasta Sauce nutrition label.

One lifestyle marker that I would like to strongly advocate for that was mentioned in the Nature article is physical exercise. Not only does physical exercise promote microbiome diversity, but it also is a great stress reliever that leaves you feeling accomplished and good about yourself. In high school, I used to be a very competitive athlete. I would work out and play soccer sometimes twice a day, and I would travel every weekend for games. Once getting into college, I lost that aspect of myself and found myself drowning in school work. Overall, I was just not happy with how things were going. Taking the time to work out, or even just go for a walk has greatly helped me release stress and feel like I have done something productive with my day, as opposed to just sitting at my desk and procrastinating all my work. It helped give me a set schedule for my week and gave me the chance to do something I truly enjoy.

The Growing Problem of Antibiotic Resistance

Antibiotic drug resistance is an ever-growing problem that poses a severe threat to healthcare systems globally. A superbug is defined by Mayo clinic as “strains of bacteria, viruses, parasites and fungi that are resistant to most of the antibiotics and other medications commonly used to treat the infections they cause.” I think of it as natural selection in a way. Over time, bacteria, viruses, parasites, and fungi adapt to drugs that are designed to kill them and change in order to survive. Some common practices that have proven to increase the appearance of antimicrobial-resistant germs are: using or misusing antibiotics, having poor infection prevention and control practices, living or working in unclean conditions, and mishandling food. In order to tackle this problem, people should use antibiotics as directed and only when needed, complete the full treatment of course, even if you feel better, not share antibiotics with others, and not use leftover prescriptions.

In an article by Bhawna Malik and Samit Bhattacharyya published in the Scientific Reports journal talking about antibiotic drug resistance, they explain how resistant bacteria is described now as a primary threat to public health in the 21^st century, and global agencies are now in a race to provide urgent action. They go on to say that antibiotic resistance has the potential to occur naturally, but one of the primary driving forces is the irrational use of antibiotics. Misuse of antibiotics accelerates the resistance process by leading to the eradication of the sensitive strain and creation of the resistant bacteria. The use of antibiotics is increasing worldwide, specifically in developing countries. Self-medication is a primary factor in this increase. Over-the-counter sales, which is a common practice in countries like Bangladesh, Addis Ababa, and Ethiopia, is one of the sources of self-medication. In a recent report regarding global antibiotic consumption, it shows an increase by 65% (previous 39%) between the years 2000 and 2015. It also showed an increase from 21.1 to 34.8 billion Daily Defined Doses, and this increase was sparked by overconsumption in lower middle income class countries. Some of the struggles driving self-medication are the avoidance of expensive treatment, poor access to medical facilities, inadequate education, and a lack of awareness. Factors for irrational antibiotic prescription by physicians include satisfying patient expectation, lack of knowledge and diagnostics, incentives and advertising from industry, and financial benefits.

So, what can we do about this? As stated before, if prescribed an antibiotic, the patient must use as directed for the allotted time in order to ensure that all of the bacteria are killed. If a person starts feeling better half way through their prescribed treatment and does not take the rest, the bacteria could reemerge from a latent stage and the individual could become infected again. People also need to become more educated on the purpose and use of antibiotics in order to understand that increasing resistance within the population is a dire problem. Physicians should only prescribe antibiotics if absolutely necessary and should explain clearly to the patient how to use them in a safe and correct way. In an infographic made by the CDC, they state that half of antibiotic use in humans and much of antibiotic use in animals is unnecessary and makes everyone less safe. Stopping these inappropriate uses would help greatly in slowing down the spread of resistant bacteria. They also state that practicing antibiotic stewardship (only using antibiotics when needed, and to choose the right antibiotics and to administer them in the right way) is a primary way to stop antibiotic resistance.

How to stop antibiotic resistance; CDC.

Is Your Hand Sanitizer Safe?

Due to the COVID-19 pandemic, we have seen a significant increase in the buying and manufacturing of hand sanitizers. This, as we know, led to a shortage, causing non-traditional manufacturers to start making more. From an economics standpoint, the demand of hand-sanitizer was high and the supply was low, this leads to desperate people willing to pay extremely high prices for an essential product. Companies monopolize on this and start producing this product, but some companies may not have the health of individuals in mind when making it. On August 12, 2020, the FDA released a statement urging individuals to stop buying hand sanitizer that contains 1-propanol, specifically hand sanitizer manufactured by Harmonic S de RL de MI in Mexico. These hand sanitizers have been labeled to contain ethanol or isopropyl alcohol, but have been tested positive for 1-propanol contamination.

In the statement from the FDA, it says that young children who accidentally ingest these products, and adolescents/adults who drink these products, are most at risk. Ingesting 1-propanol can cause depression to the central nervous system, potentially leading to death. Some symptoms of 1-propanol infection are: confusion, decreased consciousness, and slowed pulse/breathing. Studies performed on animals have shown that the depressant effects from 1-propanol are two to four times as potent as alcohol (ethanol). Skin or eye exposure can cause irritation, and in some cases allergic reactions.

In a study published in February, 2021 by Phillips, et al. discussing the impact of alcohol-based hand sanitizers during the COVID-19 pandemic, it was stated that exposure to 1-propanol can cause severe acidosis and death. Their methods included using generic codes for alcohol-based hand sanitizers to characterize exposures reported to the Texas Poison Control Network in 2019 and 2020. For the cases in 2020, they identified cases considered COVID-19 -related cases where the individual reported exposure to an unknown alcohol-based hand sanitizer with safety concerns. What they found was that reported exposures to alcohol-based hand sanitizers increased 72.5% between 2019 and 2020, and in 2020, 10% were COVID-19 -related. The effects of dangerous chemicals, such as 1-propanol, were disproportionately seen in older individuals who claimed to be using a chronic amount of hand sanitizer because of COVID-19.

The best way to prevent the spread of COVID-19 is by washing your hands with soap and water. However, if this is not available when needed, the CDC recommends using an alcohol-based hand sanitizer with at least 60% ethanol. The FDA continuously tested different hand-sanitizers in order to determine their safety and effectiveness. They have a DO-NOT-USE list that I recommend everybody look at to ensure that the hand-sanitizer they are using is safe. The only alcohol that should be in your hand sanitizer is ethyl alcohol (commonly known as ethanol or alcohol) and isopropyl (also known as isopropanol or 2-propanol).

Step-by-step hand sanitizer search guide provided by the FDA.

MMR Vaccine Linked to Autism?

In 1998, Andrew Wakefield published an article in the journal The Lancet, talking about “linkages” between the MMR vaccine and autism. Since the publishing of this article, the term vaccine hesitancy was created and people have been more and more reluctant to receiving multiple different vaccinations since. The Lacet retracted the article in 2010, noting that elements of the manuscript were proven to be false. In an article by Dr. Thomas Zane, he disputes Wakefield’s study and explains thoroughly how the study done was not “good science.” In Wakefield’s study, it said that nine of the subjects that were studied demonstrated signs of regressive autism after the vaccine. Dr. Zane disputes this by saying that three of the nine subjects clearly had no such symptoms, and these three subjects did not even have a clinical diagnosis of autism. A further recalculation of the results was done and it showed that of the 12 subjects, six were reported to having symptoms after the vaccine, but the other six did not. This was proven to be a random result with no correlation to the vaccine. Dr. Zane also explained that the subjects chosen to participate in this study were not randomly selected, further altering the integrity of the study. Many of the participants were selected from an organization called Justice Awareness and Basic Support (JABS). The opening line on their website states “Welcome to the support group for vaccine-damaged children.” This poses two problems: the children selected for the study could have had previous medical problems or the parents could have had predisposed biases against the MMR vaccine. The control of Wakefield’s study was children who were not vaccinated with the MMR vaccine. The Wakefield study triggered the vaccine-autism myth worldwide and resulted in a distrust for many childhood vaccines. This study shows multiple examples of how the scientific method was neglected, and how he conducted an experiment that supported a previously held belief of his.

Andrew Wakefield; adapted from slate.com.

In another article published in 2002 in The New England Journal of Medicine, Madsen, et al. performed a study further refuting Wakefield’s position. The study was based on individual reports of vaccination and diagnosis of autism in a well-defined geographic area.  The participants in this study were children born in Denmark during the period of January 1, 1991 through December 31, 1998. However, not all the children that were born during this time frame were included in the results. Follow-up of 5,811 children was stopped before December 31, 1999, because of a diagnosis of an autistic disorder, other autistic-spectrum disorders, tuberous sclerosis, congenital rubella, Angelman’s syndrome, or because of death or emigration. The study found that there was no increase in the risk of autism among vaccinated children compared with unvaccinated children (the control group). The adjusted relative risk of autistic disorder was 0.92, indicating close to identical risk among the two groups (vaccinated and unvaccinated). I do not believe this paper was biased because it used the scientific method and valid data to accurately refute Wakefield’s previous stance.

I believe that vaccines only help the public rather than harm. I do not believe that there is a direct correlation between autism and the MMR vaccine, which is now the MMRV vaccine. Vaccine hesitancy is real and is something we see now in regards to the COVID-19 vaccines, which have been unfortunately politicized and portrayed as dangerous to an individual’s health. In an article by Jarret, et al. discussing strategies for addressing vaccine hesitancy, it was found that the greatest methods of mitigating hesitancy were as follows: directly targeting unvaccinated or under-vaccinated populations, increasing vaccination knowledge and awareness, improving convenience and access to vaccination, targeting specific populations, mandating vaccines or sanction against non-vaccination, and engage religious or other influential leaders to promote vaccination. If individuals are knowledgeable about the mechanics of vaccines, I believe we would see a greater number of childhood vaccinations, as well as an increase in COVID, and even influenza, vaccination rates.

Moderna vs Johnson & Johnson

The COVID-19 Moderna vaccine is a mRNA vaccine, which gives instructions to our cells to make a harmless piece of what is called the “spike protein.” In an article about mRNA vaccines written by the CDC, they explain that this spike protein is found on the surface of the COVID-19 virus. First, the COVID-19 vaccine is administered to the upper arm muscle. Once the mRNA is inside the muscle cells, the cells then use these instructions to make a protein piece. After it is made, the cell breaks down the mRNA and eradicates it. The mRNA never enters the nucleus of the cell, meaning it does not affect or interact with our DNA in any way. Next, the protein piece is shown on the cell’s surface. Our immune system recognizes that this protein does not belong there and we begin building an immune response and making antibodies. Lastly, our bodies have then produced enough antibodies and is educated on how to protect us from future infection. One positive of this vaccine is that you get protection without having to worry about getting sick with COVID-19. In an article written by NPR, Margaret Liu, a vaccine researcher, explains that vaccine can me made much faster than older vaccines could. She also explains that one of the problems with mRNA vaccines is that they are very easily destroyed, due to there being enzymes in it that will just break it apart. For this reason, we need to store the Moderna vaccine at a very low temperature, because everything happens more slowly as you lower the temperature. This means the chemical reactions that break down the RNA are going to happen more slowly.

How mRNA vaccines work.

The Johnson & Johnson vaccine is a bit different. In an article written by VCU Health concerning the Johnson & Johnson vaccine, it is explained that the vaccine uses a disabled adenovirus, which is a common virus that causes cold or flu like symptoms, to deliver the instructions needed to protect you against COVID-19. The adenovirus has no relation to COVID-19 and is actually a completely different virus. It can give your body the instructions necessary to protect you from future infection, but it cannot replicate in your body and cause infection. One of the biggest advantages of the Johnson & Johnson vaccine is that it only requires one shot, whereas the Moderna and Pfizer mRNA vaccines require two. Another advantage is that the vaccine does not need to be kept in freezing cold temperatures, making it easier to distribute and maintain. In another article by MU Health, they explain that the scientists behind the Johnson & Johnson vaccine added the gene for the coronavirus’ spike protein to an adenovirus. The adenovirus was modified so it can enter cells but can’t replicate. Once the vaccine is administered, the adenovirus brings the instructions that teaches the cells how to make said spike protein. This causes an immune reaction and you begin making antibodies to attack the spike protein.

I believe that it is absolutely imperative that everybody gets vaccinated. Getting vaccinated, wearing your mask, and keeping your distance are the only true ways we will eradicate this virus, but the vaccines can’t reach their full potential unless we reach herd immunity. I think that any of the three vaccines made (Moderna, Pfizer, and Johnson & Johnson) are effective against COVID-19. One of the biggest discrepancies I have heard against the Johnson & Johnson vaccine is that it has a lower efficacy rate. However, at the beginning of the pandemic, if we had a vaccine with an efficacy rate of 72%, we would all be ecstatic. With new variants arising, the efficacy rate is falling, but this is due to not everyone getting vaccinated. If everyone had received the vaccine when they were allotted to, we would have reached herd immunity and it would have been harder for the virus to mutate and create new strains. There are many credible sources available that accurately explain how these vaccines work and why they are not bad for you. People begin depending on non-reliable sources that spread false information regarding the vaccine, further deterring them from receiving it. The sources I have listed are very helpful and go into great detail about how the vaccine is safe and how we should all get it.

Microbiome and Disease

According to the National Human Genome Research Institute, the microbiome is an umbrella term that refers to a specific collection of microorganisms that exist in an environment. In the context of this class, we are studying the microbiome that is found in the human body, for example, in the skin or stomach. The microbiomes in our body help maintain our health, but inflammation, diet, and other factors can severely harm our microbiome, leading to disease. One disease where you see the microbiome playing a part is depression. In an article written by Lach, G., Schellekens, H., Dinan, T.G. et al. about the role of the microbiome in anxiety and depression, it was expressed that many of the peptides and their receptors released in the gut are also found widely in the brain/expressed in the brain, where they play roles in the neurobiology of anxiety and depression. The expression of these peptides in the brain is likely to be controlled by changes in the gut microbiota, suggesting that they may have an integral role in gut-brain communication. Depression is also linked with changes in colonic motility, which directly affects the composition and stability of gut microbiota. Stress-related disorders also have effects on the intestinal barrier, which triggers a “leaky gut”, in turn, allowing a microbiota-driven proinflammatory response.

The microbiome – brain information pathways.

In an article talking about the gut microbiome and the brain, they went into detail about the role of SCFAs and how they could have potential antidepressant effects. SCFAs are produced by the gut microbiota through the fermentation of partially digestible and indigestible polysaccharides. The most known SCFAs that are produced by the gut are aceitic acid, proprionic acid, and butyric acid. These act as signaling molecules and are able to influence a wide range of physiological functions. One example given was the beneficial effects that proprionic acid has over body weight control and glucose metabolism through activation of free fatty acid receptor 3, receptors on nerve fibers of the portal vein, and its subsequent signaling to the brain. Also, chronic butyrate treatment produced an antidepressant effect in rats that was associated with an increase in brain derived neutrophic factor, which promotes the survival of nerve cells.

Today, many people have fallen into a Western diet, which Zumin Shi defines as a high intake of energy-dense and processed food. Consuming this diet is a risk factor for many chronic diseases including diabetes, obesity, and cardiovascular diseases. In Shi’s article about the link between the gut microbiota and the Western diet, he states that the underlying cause of chronic diseases from the Western diet is inflammation. A high consumption of ultra-processed foods – defined as being highly palatable, having a long shelf-life, and being cheap – can change the gut microbiota and lead to said inflammation. Having a healthy diet not only provides us with the nutrients that we need, but also the materials we need in order to facilitate the growth of microbiota in our gut.