CX3CR1 and granulomatosis with polyangiitis: Fractalkine/CX3CL1-CX3CR1 interaction contributes to the development of various inflammatory diseases such as rheumatoid arthritis, asthma, Wegener’s granulomatosis, Crohn’s disease, psoriasis, glomerulonephritis, experimental autoimmune anterior uveitis, and atherosclerosis [52-57].