IL17A and psoriasis: The pathogenesis of psoriasis and organ-based comorbidities may be mediated by certain representative cytokines, e.g., Interleukin-17 (IL-17),50, 51, 52, 53 Interleukin-23 (IL-23),54 and Tumour Necrosis Factor-ɑ (TNF-ɑ).55, 56 They can reach the body anywhere through the blood circulation and may mediate systemic inflammatory responses in psoriasis.57, 58, 59, 60, 61 Whether the inflammatory cytokines act on each system together or singly?