Targeting ZIP12-mediated Zn²⁺ signaling as a treatment for pulmonary hypertension

ZIP12, a membrane-bound zinc importer, is up-regulated in the remodeled pulmonary arterioles of patients with pulmonary arterial hypertension (PAH). Genetic deletion of its encoding gene, Slc39a12, ameliorates the disease in rodent models. Here, we show that ZIP12 overexpression in human pulmonary artery smooth muscle cells (PASMCs) increased intracellular labile Zn²⁺ and promoted proliferation. ZIP12 siRNA knockdown attenuated pulmonary hypertension in rodent models. We developed a humanized anti-ZIP12 monoclonal antibody, APL-9796, that normalized intracellular Zn²⁺ concentration, suppressed proliferation in fibroblasts derived from patients with PAH and PDGF-stimulated PASMCs, and reduced PDGF-induced cytoskeletal remodeling in PASMCs and contractility in PASMCs and engineered pulmonary artery tissues. APL-9796 showed dose-dependent efficacy in humanized Slc39a12 rats, improving cardiopulmonary parameters after induction of pulmonary hypertension and was well tolerated in phase 1 clinical studies. Transcriptomic profiling revealed modulation of several molecular pathways, including those involving AMPK, PPAR, and PI3K-Akt. ZIP12-driven labile Zn²⁺ signaling underpins the pathogenesis of PAH. Targeting ZIP12 with APL-9796 offers a promising therapeutic strategy.