TLR3 and pulmonary arterial hypertension: TLR3 transcription within ECs is regulated by p53 and downstream TLR3 signaling via IRF3 regulates transcription of bone morphogenic protein receptor 2 (BMPR2) via direct binding of IRF3 on the BMPR2 promoter, hence linking cell cycle regulation via p53, regulation of innate immunity and BMPR2 signaling as a novel axis driving pulmonary artery remodeling and PAH (30).