eye microbiome

Our gut microbiome may be contributing to some forms of blindness

Our eyes are considered ‘immune privileged’, which means that they are generally protected from our own immune system.  The major mechanism for eye immune privilege comes from a tight physical barrier that separates our lymphocytes, such as T cells, from the actual eye.  T cells do have the ability to cross this barrier, but they first must come in contact with, and be activated by eye antigens.  These antigens are sequestered on the opposite side of the barrier, in the eye, so that they are not exposed to the T cells.  There are diseases in which these retinal T cells do mysteriously become activated though, and they cause an inflammatory disease known as uveitis.  Uveitis is responsible for causing blindness and other eye issues in many people, but again the cause for the T cell activation is largely unknown.  Researchers at the NIH recently created a mouse model for uveitis, and were able to test a variety of factors that may be activating the T cells.  To their surprise, the gut microbiota seemed to be activating the T cells.  They published the results of their study last week in the journal Immunity.

The researchers first created a mouse model of uveitis where the retinal T cells spontaneously become activated.  They then noticed that the highest concentration of these T cells were near the gut, suggesting the gut bacteria were playing a role.  The scientists then treated the mice with antibiotics to decrease the gut bacterial concentration.  Although the mice still developed some symptoms of uveitis, the disease was ameliorated greatly in these mice.  As previously discussed, the normal T cell activator antigen is in the and physically separated.  In order to ensure that this antigen wasn’t somehow leaking out of the eye to activate the T cells in their model they created mice that lacked these antigens in their eye.  Still though, the mice presented symptoms of uveitis, meaning that the antigen that is activating the T cells is not from the eye, but rather is being produced somewhere else, such as the gut.  In order to firmly prove the gut bacteria’s role, the scientists showed that T cells could be activated by specific proteins from gut bacteria.  In fact, germ free mice, which otherwise would not have an ocular inflammatory response in their model, showed strong uveitis when they were given just the protein extract from other wild type mice. 

This research is the first to connect the gut microbiome with ocular autoimmune inflammation.  It presents many questions as to how to therapeutically combat this disease, perhaps through monitoring the gut microbiota for presentation of antigens that could activate these retinal T cells.  It also begs to be connected with other sites immune privilege breakdown in the body.  The fetus and placenta in pregnant women, for example, is an immune privileged space.  Immune activation of this site can sometimes lead to miscarriage.  Are gut or vaginal bacteria involved with this response, as we have discussed a few times in this blog?  In time, scientists will know enough to accurately answer this question.

Please email blog@MicrobiomeInstitute.org for any comments, news, or ideas for new blog posts.

The views expressed in the blog are solely those of the author of the blog and not necessarily the American Microbiome Institute or any of our scientists, sponsors, donors, or affiliates.

Episode 9 of The Microbiome Podcast: The skin microbiome and AOBiome with Dr. Larry Weiss

On the ninth episode of The Microbiome Podcast, we talked with Dr. Larry Weiss, Chief Medical Officer of AOBiome.  AOBiome is a leading company based in Cambridge, MA that is developing treatments for inflammatory skin conditions. They also have a cosmetic product on the market that consists of Ammonia Oxidizing Bacteria that the user applies to the skin twice a day. We discuss both the cosmetic product as well as AOBiome’s approach to treating skin conditions with Dr. Weiss. 

AOBiome is offering listeners of The Microbiome Podcast a 25% discount if you order their product before June 29th. The discount code is ami25. Click here to learn more about the product.

Also, as we discussed on last week’s podcast, the AMI is sponsoring a citizen science project where individuals can sequence their vaginal or penile microbiome. To be entered to win a free sampling, enter your information here. 

Remember to call in to ask any questions about the microbiome that you would like answered on future podcasts. The number is 518-945-8583. 

Listen to the podcast on our website, on iTunes, or on Stitcher

For more detailed shownotes, read below:

On this week’s podcast we discussed:

  • (2:00) Ritter Pharmaceuticals, a microbiome pharmaceutical company that is working on an oral therapy for reducing lactose intolerance symptoms, filed for a $17 million IPO and is becoming a public company. Read more
  • (2:30) Seres Health, a microbiome company working on a therapeutic for treating Clostridium difficile infection, also filed for an IPO for $100 million and received Breakthrough status from the FDA. Read more.
  • (4:55) A study out of NYU found that wearing contact lenses altered the eye microbiome compared to non-contact wearers. Read the abstract
  • (9:31) We talked a bit about AOBiome. Learn more about AOBiome. www.aobiome.com
  • (11:17) Dr. Larry Weiss gave an overview of the skin microbiome and ammonia oxidizing bacteria.
  • (13:22) An article out of NYU (led the same scientist who led the contact lens study) that studied a group of aboriginal Amerindians and found that they had perfect skin and still contained ammonia oxidizing bacteria on the skin. Read our blog post about the study
  • (16:34) Dr. Weiss discussed the goals of AOBiome and how they are approaching the skin microbiome.
  • (18:55) AOBiome’s cosmetic product that applies ammonia oxidizing bacteria to the skin. Learn more about the product. There is a discount code for our listeners for 25% off - ami25. 
  • (26:00) Larry mentioned a Ted Talk about combatting smelly armpits. Watch the TED Talk
  • (29:18) AOBiome’s therapeutic research areas and specifically acne.
  • (32:25) Eczema and how the microbiome could be used to treat the condition.
  • (39:15) Bacterial vaginosis and AOBiome’s approach to this infection.
  • (42:51) Larry’s career going from a company called CleanWell, an antimicrobial company, to AOBiome, a company that administers bacteria to the body.
  • (45:25) Hang hygiene and hand washing and Larry mentioned a study from the US Navy that found washing hands lowered the risk for getting a respiratory illness. Read the study.
  • (50:16) On the aftershow, we discussed hand washing, whether we wear glasses or contacts, and Lebron James and the NBA finals.

Please email blog@MicrobiomeInstitute.org for any comments, news, or ideas for new blog posts.

The views expressed in the blog are solely those of the author of the blog and not necessarily the American Microbiome Institute or any of our scientists, sponsors, donors, or affiliates.