IL13 and pulmonary arterial hypertension: HIV infection induces high secretion of some cytokines by monocytes, macrophages and lymphocytes including interleukin (IL)-1, IL-6, IL8, IL-13, tumor necrosis factor (TNF) α and platelet-derived growth factors which can exacerbates a patent PAH or induces inflammation of vascular endothelium leading to PAH [16–23].