Within pooled microdissected pulmonary arteries, we observed significant (***P < 0.001) increases postbleomycin challenge, in mRNA expression levels, for the mediators associated with pulmonary hypertension in clinical disease and rodent disease models; PDGF‐β (Fig. 7A), Nox‐4 (Fig. 7B), PAI‐1 (Fig. 7C), VEGF (Fig. 7D), Tryptophan hydroxylase‐1 (TPH‐1) (Fig. 7E), and IL‐6 (Fig. 7F). Here, TPH1 is linked to pulmonary arterial hypertension.