CD44 is it all about the Gut?

There is a real move to suggest that the influence of the immune system is because of bacteria in the gut. Every science meeting has a session on it.

The following is one example, but as I get airbrushed out of history I am not so sure it is all so simple

Chitrala KN, Guan H, Singh NP, Busbee B, Gandy A, Mehrpouya-Bahrami P, Ganewatta MS, Tang C, Chatterjee S, Nagarkatti P, Nagarkatti M.CD44 deletion leading to attenuation of experimental autoimmune encephalomyelitis results from alterations in gut microbiome in mice. Eur J Immunol. 2017 May 23. doi: 10.1002/eji.201646792. [Epub ahead of print
Dysbiosis in gut microbiome has been shown to be associated with inflammatory and autoimmune diseases. Previous studies from our laboratory demonstrated the pivotal role played by CD44 in the regulation of experimental autoimmune encephalomyelitis (EAE), a murine (They mean mouse) model of multiple sclerosis (I bet the people doing marmoset studies would like to think they do EAE studies). In the current study, we determined whether these effects resulted from an alteration in gut microbiota in CD44KO mice (CD44 is a molecule on white blood cells that gets upregulated in memory T cells. This binds to hylauronic acid which gets deposited in lesions).


Feacal transfer from naïve CD44KO but not CD44WT mice, into EAE-induced CD44WT mice, led to significant amelioration of EAE. 

High-throughput bacterial 16S rRNA gene sequencing and biochemical analysis, revealed that EAE-induced CD44KO mice showed significant diversity, richness, and evenness when compared to EAE-induced CD44WT mice at the phylum level, with dominant Bacteroidetes (68.5%) and low Firmicutes (26.8%). 

In conclusion, our results demonstrate that the attenuation of EAE seen following CD44 gene deletion in mice may result from alterations in the gut microbiota. Furthermore, our studies also demonstrate that the phenotype of gene knock-out animals may be shaped by gut microbiota

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