Gut Inflammation in Chronic Fatigue Syndrome

Shaheen E Lakhan; Annette Kirchgessner

Disclosures

Nutr Metab. 2010;7(1) 

In This Article

Hydrogen Sulfide

Alterations of the gut microbiota may have serious consequences for the host health. Overgrown pathogenic bacteria found in the oral cavity and GI tract produce the "toxic gas" hydrogen sulfide (H2S) when they come in contact with heavy metals. H2S, a colorless, flammable and water-soluble gas with the characteristic odor of rotten eggs, has been known for decades because of its toxicity and as an environmental hazard.[77] Inhibition of mitochondrial respiration, more potent than that of cyanide, resulting from blockade of cytochrome c oxidase is the main mechanism of H2S toxicity.[78]

H2S is normally found in the body, which suggests that this molecule could have physiologic relevance. The mucosa of the gut is continuously exposed to H2S generated by sulfate-reducing bacteria.[79] However, too much H2S, produced by the overgrowth of harmful, pathogenic bacteria as occurs during inflammation causes the intestinal epithelial barrier to break down. Increased levels of bacterial H2S stimulate the production of destructive compounds called ROS, which inhibit mitochondrial function directly. An increase in ROS caused by an imbalance between antioxidant defenses and ROS production results in tissue damage and, eventually, cell death. This is a key mechanism for the development of gut infections. Thus, there is evidence that H2S is involved in chronic (long-term) inflammation of the gut.[80]

People with CFS were shown to have higher concentrations of intestinal bacteria than normal, which probably leads to higher levels of H2S. Professor Kenny De Meirleir of the Brussels Free University and his team say high levels of H2S caused by an intestinal overgrowth of Gram positive D/L lactate-producing bacteria play a major role in CFS and lead to a series of reactions in your body that leave cells devoid of oxygen and energy.

Understanding the role of the intestinal barrier and its breakdown is an area of research that is currently receiving a great deal of attention as is considered by many scientists as the real basis for CFS.[12] Interestingly, it has recently been shown that H2S is also present in gut nerves in humans and guinea pigs. Schemann and colleagues found that more than 90% of neurons in the ENS contain enzymes that produce H2S.[81] In addition, H2S increased neuronal electrical activity and significantly increased mucosal secretion. These finding suggest H2S is a novel gut-signaling molecule and may be the third gaseous transmitter in addition to nitric oxide and carbon monoxide.

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