S1PR1 and autoimmune disease: More than half of the compounds are distributed across four known targets, which are type 5 phosphodiesterase (PDE5A), the primary target of sildenafil [18], a chemokine receptor (CCR2) involved in disease processes in various neurological disorders or autoimmune diseases [19], a Na+/H+ exchanger in mitochondrial membranes (NHE1) associated with cardiac dysfunction [20], and sphingosine 1 phosphate receptor-1, which is mainly involved in autoimmune diseases [21].