Recently researchers have identified platelet Toll-like receptor 4 (TLR4) as a key factor mediating immune and inflammatory responses in PAH, and in a hypoxia-induced model, specific deletion of TLR4 demonstrated protective effects against PAH, and inhibition of TLR4-specific ligands or stimulation of ligand etiology may be a viable treatment for PAH (31). Here, TLR4 is linked to pulmonary arterial hypertension.