Girdhari Lal, India
National Centre for Cell Science Laboratory of Inflammation and AutoimmunityPresenter of 2 Presentations
CHEMOKINE RECEPTOR CCR6 INTRINSIC SIGNALING ALTERS METABOLIC REPROGRAMMING OF TH17 CELL DURING GUT INFLAMMATION AND AUTOIMMUNITY
Abstract
Background and Aims
CCR6 is a G protein-coupled receptor, and ulcerative colitis patients show strong positive with the severity of the disease. How does CCR6 intrinsic signaling in CD4 T cells affect the pathogenicity of Th17 cells during gut inflammation and autoimmunity is not known.
Methods
Immune cells were phenotypically characterized using flow cytometry. FACS purified naïve CD4 T cells were in vitro differentiated into Th17 in the presence or absence of CCL20, and proteomic analysis was performed using mass spectroscopy. Gut inflammation in wild-type C57BL/6 or CCR6-/- mice was induced by giving dextran sodium sulfate in the drinking water.
Results
Our results showed that ulcerative colitis patients have a significantly high frequency of RORgt+T-bet+CD4+ T cells in PBMCs as compared to healthy individuals. In the presence of CCL20, in vitro differentiation of purified naïve human CD4+ T cells into Th17 cells significantly increased the frequency of pathogenic IL-23R+Th17 cells (IL-17+IFNγ+GMCSF+ Th17 cells) in the AKT/mTOR/STAT3 signaling dependent manner. Furthermore, CCR6-/- mice showed reduced inflammatory colitis and lower frequency of pathogenic Th17 in the gut-associated lymphoid tissues as compared to wild-type mice. Deficiency of CCR6-/- abrogated the CCL20 driven differentiation of pathogenic Th17 cells. Proteomics analysis of Th17 cells differentiated in the presence of CCL20 showed significant alteration in several proteins belonging to various cellular metabolic pathways.
Conclusions
Signaling through the CCL20-CCR6 axis drive the differentiation of pathogenic Th17 cells by altering the cellular metabolism, and a strategy to block the non-chemotactic function of CCR6 may help in controlling the gut inflammation and autoimmunity.
CCR9 INTRINSIC SIGNALING IN DENDRITIC CELLS PROMOTE THE DIFFERENTIATION OF FOXP3+ REGULATORY CD4 T CELLS IN THE GUT
Abstract
Background and Aims
The chemokine receptor CCR9 play important role in the migration of immune cells in the gut and shows a strong clinical association in inflammatory bowel disease (IBD). Several clinical trials were conducted by targeting CCR9 or its ligand CCL25 in IBD but failed. The detailed cellular and mechanism of CCR9 and CCL25 interactions and its effect various immune cells are not clearly understood.
Methods
Gut inflammation in C57BL/6 mice was induced by giving dextrans sodium sulfate (DSS; 2% w/v) in the drinking water. Dendritic cells (DC) subsets and CD4 T cells were characterized using flow cytometry. Naive CD4+CD25-CD44- T cells were in vitro differentiated into Th17 and Treg cells in the presence of CCR9+ or CCR9- DCs and recombinant CCL25.
Results
DSS treatment significantly increased the infiltration of CCR9+DCs in the gut-associated lymphoid tissues (GALT) compared to control mice. Among the CCR9+CD11c+DCs, the frequency of CD11b-CD103+ DCs was significantly higher in the GALT. CCR9+ DCs showed lower expression of MHC II and CD86 molecules, and higher FasL and latency associated peptides in the GALT. CCR9+DCs in the presence of purified recombinant CCL25 promoted the differentiation of Foxp3+ regulatory CD4 T cells in the culture. The differentiation of Foxp3+Tregs was due to thymic stromal lymphopoietin (TSLP) produced by DCs in the culture. Furthermore, the adoptive transfer of CCR9+DCs in C57BL6 mice suppresses the ova-specific gut allergic response.
Conclusions
Our data showed that CCR9+DCs have a regulatory function and may be exploited as a cellular therapy to control gut inflammation and autoimmunity.