Saturday, January 27, 2007

Leaky gut and altered bacteria in gut linked to AIDS. More support for probiotic use?

Leaky gut and bacteria in the gut are important in the progression of AIDS after HIV infection. Benchley et al report elevated levels of lipopolysaccharides (LPS), a component of the cell wall of gram negative bacteria in the gut, in people with AIDS versus those HIV infection without AIDS. Lower levels of LPS therefore less bacterial translocation and leaky gut were observed in people with HIV infection treated with combination anti-viral medications and in monkeys with AIDS like virus who were treated with antibiotics to reduce gut bacteria. Signs of chronic systemic immune activation including severely depleted T-helper type CD4+ white blood cells are associated with HIV progressing to AIDS.

Immune activation in AIDS is then believed the result of the breakdown of the gut mucosal barrier or a leaky gut by HIV infection. Elevated LPS in the blood is a marker of bacterial translocation that is associated with increased gut permeability. Translocation is movement of bacteria or bacteria products through the gut wall without bacteremia or full-blown bacterial blood stream infection. Such increased gut permeability and elevated LPS levels in the blood are linked to inflammatory bowel diseases (IBD) and persistent systemic immune activation probably in part due to bacteria and yeast proteins in Crohn’s disease. The latter is reflected by elevated blood antibodies to Saccharomyces cervesiae yeast (ASCA) and bacteria products (anti-cBir1, OmpC) detected in the blood in many people with Crohn’s disease.

Uncontrolled immune activation in the gut is believed to be central to the abnormal response to food antigens like gluten in celiac disease. The leaky gut from gluten results in development elevated gliadin antibodies and eventually endomysial and tissue transglutaminase antibodies in most people with untreated celiac disease. Since the gut is the primary entrance of most foreign proteins, altered gut barrier followed by chronic persistent immune activation results in more foreign microbes and food protein exposure that promotes further gut injury, i.e. more leaky gut. It becomes a vicious cycle. We cannot change our genes that may predispose us to certain diseases resulting from leaky gut associated foreign protein immune activation but we can control some of our risk for leaky gut.

If you have celiac disease, lactose intolerance, IBD, irritable bowel syndrome or autoimmune diseases you should definitely consider taking a daily probiotic. Avoid medications that injure the gut like NSAIDs (ibuprofen etc.) and antibiotics and acid blockers that may alter gut bacteria levels. Controlling stress as much as possible is important as stress has been shown to increase gut permeability at least in in a rat model. Avoid or limit problem food antigens like gluten and casein or problem food lectins like wheat germ agglutinin, casein, soybean agglutinin, and peanut agglutinin as much as possible. Avoid foods derived from animals or plant sources treated with antibiotics and antifungals. Since avoiding all these factors may be impossible, taking a daily probiotic to restore your gut to healthy levels of microbes makes sense.

Microbial translocation is a cause of systemic immune activation in chronic HIV infection. Benchley JM et al. Nature Medicine 2006; 12:1365-1371.

Gut microbes out of control in HIV infection. Haynes, BF. Nature Medicine 2006; 12: 1351-1352.

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