Vitamin B5 Regulates Th17 Cell Differentiation And Development Of Autoimmune Diseases

Th17 cell is an important subset of T helper cells,which plays an important role in protecting host from extracellular bacterial and fungal infections.In steady state,Th17 cells mainly reside at the mucosal barrier to maintain barrier integrity and protect host from pathogens infections.For example,intestinal mucosal Th17 cells,on one hand,promote the secretion of antimicrobial peptides by epithelial cells to preserve the balance between host and commensal bacteria.On the other hand,Th17 cells can recruit macrophages and neutrophils to clear pathogens in intestine.However,dysregulated Th17 cells response can also lead to the development of inflammatory or autoimmune diseases.Accumulating evidence revealed that Th17 cells are closely related to the development of inflammatory bowel disease(IBD)and multiple sclerosis(MS).When dysbiosis,pro-inflammatory cytokine milieus directed pathogenic Th17 cell differentiation and autoimmune diseases development.It is of great importance to understand the detailed mechanism(s)mediating pathogenic Th17 cell differentiation to aid autoimmune diseases treatment.Cellular metabolic reprogramming is essential for Th17 cells differentiation and function.A shift from oxidative phosphorylation adopted by na?ve CD4 T cells to aerobic glycolysis has been documented during Th17 cell differentiation.Indeed,increased glucose uptake and glycolysis promote Th17 cell differentiation.Whereas disruption of glycolysis associated genes restrains Th17 cell differentiation and function.In addition to increased glucose utilization,glutamine uptake and glutaminolysis are also upregulated to fuel energetic and biosynthetic demands during Th17 cell differentiation.Furthermore,mitochondrial oxidative phosphorylation also plays an important role for Th17 cell differentiation.Inhibition of cellular oxidative phosphorylation resulted in diminished glycolytic genes expression,thereby inhibiting the differentiation of Th17 cells and related autoimmune diseases development.These observations highlight that targeting of cellular metabolism manifests therapeutic potential of pathogenic Th17-associated autoimmune diseases.Environmental and genetic factors are important for the development of autoimmune diseases.Likewise,environmental cues are also the risk factor for pathogenic Th17 cell differentiation in auto inflammation.Diet as an important environmental cue associated with autoimmune diseases development has been extensively reported.A shift in diet pattern to high salt,high glucose and high fat foods has been linked to increased incidence of autoimmune diseases in western countries.Pathogenic Th17 cell response in high salt,high glucose and high fat diet have been validated to promote autoimmune diseases development,manifesting that diet is important for Th17 cell specification.But,on the other hand,diet-derived microelement and fiber are essential for host homeostasis,which are utilized directly by host cells or by commensal bacteria to produce microbial metabolites,such as short chain fatty acid.The aim of this study is to screen intestinal compounds,including diet-or bacterialderived compounds,on the effect of Th17 cell differentiation and Th17 cell-related autoimmune diseases.We used IL-17A-GFP fluorescent reporter mice for the intestinal compounds screening and animal models validation,and we obtained the following results:1.Vitamin B5 and downstream metabolite coenzyme A inhibit Th17 cells differentiation in vitro.Using IL-17A-GFP fluorescent reporter mice to screen more than one hundred intestinal compounds,we found that vitamin B5 significantly inhibited Th17 cell differentiation.At the same time,we also examined the effect of vitamin B5 on T cell survival,activation and proliferation.We found that vitamin B5 inhibited the differentiation of Th17 cells without affecting cell survival,activation and proliferation.Next,we explored the effect of coenzyme A,the downstream metabolite of vitamin B5,on Th17 cell differentiation.In consistent with vitamin B5,coenzyme A significantly inhibited Th17 cells differentiation in vitro.2.Vitamin B5 alleviates the development of EAE in mice.To investigate the function of vitamin B5 in experimental autoimmune encephalomyelitis(EAE)model,we fed mice with vitamin B5 in the drinking water two weeks prior to EAE induction.The results showed that vitamin B5 supplementation significantly alleviated the development of EAE as compared to normal diet fed mice,exhibited by reduced demyelination and immune cell infiltration in the spinal cord and reduced the frequency and cell number of Th17 cells.By contrast,vitamin B5-deficient diet rendered mice prone to EAE development,exhibited by increased demyelination,immune cell infiltration and pro-inflammatory Th17 cells accumulation in the inflammatory sites.3.Vitamin B5 alleviates CD45RBhi CD4 T cell transfer induced colitis in mice.To explore the function of vitamin B5 in other autoimmune disease,CD45RBhi CD4 T cell transfer induced colitis model was adopted.We found that vitamin B5 supplementation significantly alleviated intestinal inflammation and reduced inflammatory Th17 cells infiltration,while vitamin B5 deficiency exacerbated colitis development as compared to normal diet fed mice,exhibited by increased immune cell infiltration and inflammatory Th17 cells accumulation in the colon.4.Vitamin B5 and downstream metabolite coenzyme A inhibit Th17 cell glucose metabolism.Through RNA sequencing technology,we found that vitamin B5 treatment significantly inhibited the expression of glucose metabolism related genes in Th17 cells as compared to PBS treatment.Further,we found that vitamin B5 and coenzyme A significantly inhibited the glycolysis and oxidative phosphorylation of Th17 cells by seahorse measurement and metabolomics profiling.5.Coenzyme A binds to PKM2 and impedes its nuclear translocation.Through co-immunoprecipitation experiments,we found that coenzyme A specifically binds to pyruvate kinase isoform 2(PKM2).Further research showed that vitamin B5 and coenzyme A inhibited the phosphorylation of PKM2,thereby promoting the formation of tetrameric PKM2 and inhibiting PKM2 nuclear translocation.As the consequence,STAT3 phosphorylation and glycolytic genes expression were inhibited.6.Vitamin B5 inhibits human Th17 cell differentiation and is significantly reduced in the serum of IBD and MS patients.We next to explore the function of vitamin B5 in human Th17 cell differentiation and autoimmune diseases.We found that vitamin B5 is significantly reduced in the serum of IBD and MS patients as compared to healthy controls.And we also found that vitamin B5 and coenzyme A significantly inhibited the differentiation of human Th17 cells in vitro by inhibiting PKM2 nuclear translocation and glycolysis.In summary,our study first found that vitamin B5 significantly inhibits the differentiation of Th17 cells and plays an important protective role in autoimmune diseases development.Mechanistically,we found that coenzyme A,the downstream metabolite of vitamin B5,can bind to PKM2,thereby inhibiting PKM2 phosphorylation and nuclear translocation,and,as the consequence,inhibits the downstream glycolysis and the phosphorylation of STAT3.At the same time,we found that vitamin B5 is significantly reduced in the serum of IBD and MS patients,suggesting vitamin B5 supplementation represents a potential therapeutic avenue for Th17-associated autoimmune diseases treatment.