Heme oxygenase-1-mediated autophagy protects against pulmonary endothelial cell death and development of emphysema in cadmium-treated mice

Abstract

Pulmonary exposure to cadmium, a major component of cigarette smoke, has a dramatic impact on lung function and the development of emphysema. Cigarette smoke exposure induces heme oxygenase-1 (HO-1), a cytoprotective enzyme. In this study, we employed a truncated mouse model of emphysema by intratracheal instillation of cadmium (CdCl2) solution (0.025% per 1 mg/kg body wt) in HO-1(+/+), HO-1(-/-), and overexpressing humanized HO-1 bacterial artificial chromosome (hHO-1BAC) mice. We evaluated the role of HO-1 in cadmium-induced emphysema in mice by analyzing histopathology, micro-computed tomography scans, and lung function tests. CdCl2-exposed HO-1(-/-) mice exhibited more severe emphysema compared with HO-1(+/+) or hHO-1BAC mice. Loss of pulmonary endothelial cells (PECs) from the alveolar capillary membrane is recognized to be a target in emphysema. PECs from HO-1(+/+), HO-1(-/-), and hHO-1BAC were employed to define the underlying molecular mechanism for the protection from emphysema by HO-1. Electron microscopy, expression of autophagic markers (microtubule-associated protein 1B-light chain 3 II, autophagy protein 5, and Beclin1) and apoptotic marker (cleaved caspase 3) suggested induction of autophagy and apoptosis in PECs after CdCl2 treatment. CdCl2-treated HO-1(-/-) PECs exhibited downregulation of autophagic markers and significantly increased cleaved caspase 3 expression and activity (∼4-fold higher). Moreover, hHO-1BAC PECs demonstrated upregulated autophagy and absence of cleaved caspase 3 expression or activity. Pretreatment of HO-1(+/+) PECs with rapamycin induced autophagy and resulted in reduced cell death upon cadmium treatment. Induction of autophagy following CdCl2 treatment was found to be protective from apoptotic cell death. HO-1 induced protective autophagy in PECs and mitigated cadmium-induced emphysema.

Resveratrol Potently Counteracts Quercetin Starvation‐Induced Autophagy and Sensitizes HepG2 Cancer Cells to Apoptosis

“…In this sense, our results (Figures B) clearly show that RSV strongly downregulated HO‐1 protein content, and this correlates with the anti‐autophagic effect of RSV. Consistent with our results, it has been shown that the HO‐1 inhibitor zinc protoporphyrin strongly inhibits autophagy and induces apoptosis and that HO‐1 induces protective autophagy …”

“…Interestingly, HO‐1 is also highly induced by a variety of agents causing oxidative stress, and increasing HO‐1 expression seems to be protective in animal and in vitro models . Additionally, recent studies have highlighted the critical role of HO‐1 in regulating autophagy . Consequently, we focused on the influence of QCT and/or RSV treatments on HO‐1 expression.…”

3D pulmospheres serve as a personalized and predictive multicellular model for assessment of antifibrotic drugs

“…For paraffin sections, immunofluorescent staining was performed as described previously (42). The primary antibodies used for staining were Fibronectin-EDA antibody (catalog sc-59826, Santa Cruz Inc.), SPC (catalog ab40879, Abcam), CD11b (catalog ab8878, Abcam), CD31 (catalog MA 3105, Thermo Scientific), α-SMA (catalog ab32575, Abcam), Collagen type IV (catalog ab6586, Abcam), and Collagen type I (catalog 600-401-103-0.5, Rockland Inc.).…”

Cadmium in tobacco smokers: a neglected link to lung disease?

“…In this setting, the oral co-administration of the anti-oxidant N-acetylcysteine partially reversed the induced pathology. Moreover, autophagy mediated by haemoxygenase may protect against cell death in pulmonary endothelial cells and the development of emphysema that is caused by intratracheal administration of cadmium chloride in a mouse model [55]. Furthermore, lysyl oxidase (LOX) is a copper-dependent enzyme essential for the cross-linking of the extracellular matrix.…”