As one of the key effector functions, C5a-induced C5aR1 activation, is involved in numerous kidney diseases, but also cardiac remodeling in hypertension (46, 47), psoriasis (48), rheumatoid arthritis (49), complications in sepsis (50), neuropathic pain (51), or hidradenitis suppurativa (52). Here, C5AR1 is linked to hidradenitis suppurativa.