Hydroxychloroquine withdrawal triggers pregnancy-associated pulmonary arterial hypertension in systemic lupus erythematosus: a case report and exploration of the Complement-EndMT axis

This case provides compelling <i>in vivo</i> evidence that non-adherence to HCQ constitutes a pivotal, modifiable risk factor for the onset of SLE-associated PAH in the gravid state, and that pharmacological reintroduction can arrest and partially reverse this pathogenic trajectory. We attribute the vascular protective effects of HCQ to the inhibition of complement activation along the C5a-MAPK/ERK signaling axis. Targeting this pathway disrupts pathological endothelial-mesenchymal transition (EndMT) and mitigates subsequent pulmonary vascular remodeling. Stringent HCQ adherence should be standard of care. Furthermore, complement monitoring guides precision pharmacotherapy to prevent PAH in susceptible SLE pregnancies.