CD44 deletion leading to attenuation of experimental autoimmune encephalomyelitis results from alterations in gut microbiome in mice

Abstract

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 model of multiple sclerosis (MS). Specifically, we showed that CD44 knockout (KO) mice were resistant to induction of EAE when compared to CD44wildtype (WT) mice and this was due to inhibition in the pro-inflammatory Th1/Th17 cells and increased induction of anti-inflammatory Th2/Treg cells. In the current study, we determined whether these effects resulted from an alteration in gut microbiota and the short-chain fatty acid (SCFA) production in CD44KO mice. Fecal 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, followed by clustering sequences into operational taxonomic units (OTUs) 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%). Further, data showed a significant change in the abundance of SCFAs, propionic acid and i-butyric acid in EAE-CD44KO compared to EAE-CD44WT mice. 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 and SCFAs. Furthermore, our studies also demonstrate that the phenotype of gene knock-out animals may be shaped by gut microbiota.

Indole-3-carbinol prevents colitis and associated microbial dysbiosis in an IL-22–dependent manner

“…Microbial 16S rRNA gene analysis and PiCRUSt functional analysis. To perform bacterial phylogenetic and functional analysis, genomic DNA was isolated from colonic flushes on day 4 of TNBS model and sequenced as previously described (96). For all downstream analysis after sequencing, this study used the Nephele platform from the National Institute of Allergy and Infectious Diseases (NIAID) Office Colon length shortening C BALB/cJ, C57BL/6 ≥8.5 cm, ≥6.5 cm 0 ≥7.5 but <8.5 cm, ≥ 5.5 but <6.5 cm 1 ≥6.5 but <7.5 cm, ≥4.5 but <5.5 cm 2 <6.5 cm, <4.5 cm 3…”

“…SCFA analysis from colonic flushes. Quantification of SCFA from colonic flushes collected from experimental groups was performed as previously described (96,97). Briefly, colon contents (100 mg) were extracted using 25% metaphosphoric acid, centrifuged (12,000 g for 15 minutes at 4°C), and filtered with Ultra-free MC columns from Thermo Fisher Scientific.…”

Resveratrol modulates the gut microbiota to prevent murine colitis development through induction of Tregs and suppression of Th17 cells

“…Samples collected were immediately frozen at −80°C for future analysis. Samples were analyzed for short‐chain fatty acid (SCFA) concentrations using 2‐ethylbutyric acid as internal standard as previously described . Briefly, the cecal samples (100 mg) were suspended and homogenized in water.…”

“…Samples were analyzed for short-chain fatty acid (SCFA) concentrations using 2-ethylbutyric acid as internal standard as previously described. 22 Briefly, the cecal samples (100 mg) were suspended and homogenized in water. After centrifugation for 10 min at 12,000 rpm, the supernatant was acidified by adding 25% metaphosphoric acid.…”

The role of gut microbiome and associated metabolome in the regulation of neuroinflammation in multiple sclerosis and its implications in attenuating chronic inflammation in other inflammatory and autoimmune disorders

“…A large portion of the intestinal flora has been linked to the production of propionic acid, including the Gram‐negative phylum Bacteroidetes and the Gram‐positive phylum Firmicutes, which contains the genus Clostridium . Studies have shown that faecal transplants high in propionic acid in combination with propionic‐acid‐producing bacterial species have been beneficial in ameliorating the clinical symptoms of EAE in mice …”