TLR4 and pulmonary arterial hypertension: For example, male SHR showed a higher serum mitochondrial DNA (TLR9 DAMP) when compared to females (Echem et al., 2019); likewise, in an animal model of pulmonary arterial hypertension, males showed a higher circulating HMGB1 (TLR4 DAMP) when compared to females.