IL-6, a centralinflammatory cytokine produced by vascular and non-vascular cells, isquantitatively associated with PAH outcomes [295], and forced overexpression ofits receptor IL6R causes vascular remodeling in animal models of PH [150].Tocilizumab, a humanized monoclonal antibody targeting IL6R and approved for usein certain diseases such as cytokine release syndrome, has shown efficacy atreversing disease pathology in preclinical models. Here, IL6R is linked to pulmonary arterial hypertension.