Heterogeneity of CD4+CD25+Foxp3+Treg TCR β CDR3 Repertoire Based on the Differences of Symbiotic Microorganisms in the Gut of Mice

Abstract

Gut microbes play a crucial role in the occurrence and development of autoimmune diseases. The diversity of intestinal microorganisms affected by the living environment, regulate the immune function of peripheral immune organs and local tissues. In the study, the diversity of intestinal microorganisms of Germ-free (GF), Specific Pathogen-free (SPF), and Clean (CL) BALB/c mice were conducted by 16S rDNA sequencing. High-throughput sequencing technology was used to analysis the composition and characterization of TCR β chain CDR3 repertoires in Regulatory T cells (Treg) in intestine and spleen of GF, SPF, and CL mice, so as to investigate the effects of differential composition of intestinal microorganisms on the CD4 + CD25 + Foxp3 + Treg TCR β CDR3 repertoire of intestine and spleen. We observed that GF, SPF, and CL mice have different gut microorganism composition, and the abundance and quantity of microorganisms are positively correlated with the level of feeding environment. Interestingly, incomplete structure of spleen and small intestine in GF mice was found. Moreover, a significant difference in the usage of high frequency unique CDR3 amino acid sequences was detected in the intestinal Treg TCRβ CDR3 repertoire among GF, SPF and CL mice, and there were a greater heterogeneity in the usage frequency of TRBV, TRBJ , and TRBV-TRBJ combinations gene segments. However, the effect of different feeding environment on the mice Treg TCRβ CDR3 repertoire of spleen was weak, implying that the different composition of intestinal microbiota may primarily affect the diversity of the local Treg TCRβ CDR3 repertoire and does not alter the overall properties of the circulating immune system. These results provide basic data to further analyze the mechanism of gut microbes regulating the intestinal mucosal immune system.

Two Step Selection for Bias in β Chain V-J Pairing

“…The simplest molecular explanation for such a preferential pairing would be that V β - J β pairs affect the biochemical properties of the receptor, and that receptors on the extremities of the distribution are selected against, as we have shown here for multiple biochemical properties, such as the length in nucleotides, the molecular weight, the charge and the polarity of the receptor. This is consistent with the relation between the V-J combination used and the CDR3 length distribution, especially for pathogen-specific TCRs ( 34 ) and the effect of the mouse compartment on the usage frequency of V β , J β , and V β - J β heterogeneity ( 35 ). This is further consistent with the bias in MHC-constrained systems for CDR3 length and amino acid composition.…”

The Effect of the Gut Microbiota on Systemic and Anti-Tumor Immunity and Response to Systemic Therapy against Cancer

“…The absence of the gut microbiota in germ-free mice is highly associated with immune dysfunction, including lymphoid tissue defects, smaller Peyer’s patches, reduced number of IELs, and an inadequate humoral mucosal immunity and IgA secretion, as well as a decreased number of immune cells, including Th1 and Th17 cells [ 20 , 21 , 22 , 23 , 24 , 25 ]. Moreover, Foxp3 + Tregs are significantly reduced in antibiotic-treated and germ-free mice, indicating the crucial role of the gut microbiota in Tregs development [ 26 , 27 ]. Instead, immune maturation occurs following microbiota transplantation to germ-free animals.…”