C5AR1 and hidradenitis suppurativa: Although C5aR1 is highly regarded as pro-inflammatory and pathogenic in a multitude of inflammatory diseases and C5AR2 is also involved in those inflammatory diseases, including gout, sepsis, hidradenitis suppurativa, and type 2 diabetes, the nature of C5AR2 appears to be much more nuanced and multifaceted (24–27).