LEP and idiopathic pulmonary arterial hypertension: Moreover, ObR expression on the regulatory T-cell (Treg) membrane was markedly upregulated in IPAH and CTD-PAH, and leptin can inhibit the function of Treg of IPAH and CTD-PAH patients and hypoxia-induced PH rats, and ObR deficient rats were protected against Treg dysfunction in hypoxia-induced PH [34,40].