Genes essential to the immune system that are “entrusted” to microbial “Old Friends”

In 2005 Sarkis Mazmanian and colleagues showed that a single polysaccharide from an intestinal commensal, Bacteroides fragilis, could largely correct the subnormal and functionally distorted development of the immune system that occurs in germ-free mice (Mazmanian et al. 2005). More recently they have shown, using three different models of intestinal inflammation, that the same polysaccharide, given by mouth, can turn on crucial immunoregulatory pathways (Mazmanian et al. 2008). In the discussion of the latter paper they state:- (more…)

Pig worms and multiple sclerosis: the unintended consequences of hygiene

Do worms protect us against autoimmune diseases? The epidemiological evidence is strongly suggestive. Ethiopian, Brazilian, Venezuelan, and Gambian adults have less asthma when infected with nematodes; Gabonese schoolchildren with schistosomiasis have fewer allergic reactions to dust mites than do those who are not so infected, and children living on farms in Germany have fewer allergies than children living in cities (Wilson & Maizels 2004). One of the most debilitating autoimmune diseases, multiple sclerosis, is virtually absent in Roma, Inuit, and Bantu, is rare in the indigenous peoples of the Americas and Asia, and is rare in the tropics generally. And in the developed world, (more…)

What good is fever?

It is pretty obvious that fever is useful. Work by Kluger and others has shown that increased temperatures decrease mortality during infection. Even for lizards! (When infected they crawl to warmer places.)

The mystery has been how fever works. Can higher body temperature alone inhibit pathogen growth? It seems unlikely that changing temperature by just a degree or so would have a major effect. Pathogens are too adaptable.

In a seminar discussion this week, Karl Sperling, from the Institute of Human Genetics, Charité – Universitätsmedizin Berlin, brought up the protective role of heat shock proteins, and how highly conserved they are. This quickly suggested that their original function might have been co-opted to cope with infection.

Sure enough, a quick search revealed (more…)