Figure 3.

Overview of regulation of dipeptidyl peptidase (DPP)IV enzymatic activity and its substrates in rheumatoid arthritis-related inflammation. Gray arrows indicate modification of mediator receptor preference by proteolytic modification; black arrows indicate stimulation of indicated mediator or enzymatic activity; dashed lines indicate termination of indicated mediator function by proteolytic degradation; dotted lines indicate down-regulation of indicated receptor. Biologically active peptides are shown in regular font and receptors are shown in italics. See the text for references. CCR, CC receptor; CGRP, calcitonin gene-related peptide; CXCR, CXC receptor; IL, interleukin; MIP, macrophage inflammatory protein; NK, natural killer; NPY, neuropeptide Y; NPYR, neuropeptide Y receptor; SDF, stromal cell-derived factor; SP, substance P; TNF, tumor necrosis factor; VIP, vasoactive intestinal peptide.