Free fatty acid receptor 2 Free fatty acid receptor 2 Free fatty acid receptor 2 (FFAR2) is a G-protein coupled receptor encoded by the FFAR2 gene. FFAR2 mRNA is expressed in adipose tissue, pancreas, spleen, lymph nodes, bone marrow, and peripheral blood mononuclear cells. FFAR2 transcription is regulated by the XBP1 transcription factor which binds to the core promoter. Mouse studies utilizing Ffar2 gene deletions have implicated the receptor in the regulation of energy metabolism and immune responses. Short Chain Fatty Acids (SCFA's) generated in the processing of fiber by intestinal microbiota act as ligands for the receptor and can affect neutrophil chemotaxis. However, discrepancies
Follicular dendritic cells Noncognate B cells play a significant role as an antigen transporter to FDCs. They capture immune complexes in CR1/2-dependent way either directly from the blood or from macrophages, and putate to the lymphoid tissue, where they upload FDCs with opsonized antigen. FDCs, in turn, attract B cells with chemoattractant CXCL13. B cells lacking CXCR5, the receptor for CXCL13, still enter the white pulp, but are mislocalized and disorganized. To generate follicular structures, FDCs need to be stimulated by lymphotoxin (LT), a mediator produced by B cells. The stimulation of CXCR5 on B cells upregulates LT production, which leads to FDCs