Reactive oxygen species may contribute to airway injury in patients with cystic fibrosis (CF) and iron catalyzes oxidant injury by promoting generation of highly reactive hydroxyl radicals. Iron in the lower respiratory tract may be free, ferritin bound (from which iron can be reductively mobilized), or transferrin bound (which generally prevents iron mobilization). Ferritin is composed of subunits that are heavy (H) or light (L), and H-rich ferritins have additional biologic effects including inhibition of lymphocyte proliferation and cell growth. To assess concentrations of iron and iron-binding proteins in the lower respiratory tract of patients with CF, we measured iron (ferrozine), L-ferritin, H-ferritin, and transferrin (enzyme-linked immunosorbent assay [ELISA]) in bronchoalveolar lavage (BAL) fluid recovered from stable patients with CF (n = 8), healthy nonsmokers (NS; n = 8), or heavy cigarette smokers (HS; n = 8). Iron was detected in BAL fluid from patients with CF and HS, but not NS, with higher iron concentrations in patients with CF (42.0 +/- 11.6 microgram/dl) than in HS (9.9 +/- 2.6 microgram/dl, p < 0.05). Ferritin was present in all BAL fluids, with higher total ferritin (L + H) in patients with CF (647 +/- 84 ng/ml) than in HS (181 +/- 25 ng/ml, p < 0.005) or NS (9 +/- 3 ng/ml, p < 0.0005). Ferritin recovered from HS and NS lungs was < 2% H type, whereas ferritin in CF lungs was > 40% H-type ferritin. Transferrin concentrations in BAL fluid were not different in any group. Tumor necrosis factor (TNF)-alpha was present only in BAL samples from patients with CF. To assess whether TNF-alpha contributed to H-ferritin accumulation in CF lungs, we treated lung epithelial cells (A549) with iron alone (FeSO(4), 10-40 microM) or with iron and TNF-alpha (5-20 ng/ml). Iron-treated A549 cells synthesized almost entirely L-ferritin whereas exposure to TNF-alpha with iron caused a dose-dependent increase in accumulation of H-type ferritin. These findings suggest that oxidant injury could be promoted in lungs of patients with cystic fibrosis by iron mobilized from extracellular ferritin and, in addition, that TNF-alpha-promoted accumulation of H-type ferritin may impair local immune function and cell growth.

No abstract

Objective Our previous findings support an additive effect of cocaine to HIV-infection in the development of pulmonary arteriopathy through enhanced proliferation of human pulmonary smooth muscle cells. We now examined the role of anti-proliferative bone morphogenetic protein receptor (BMPR) axis in HIV-protein and cocaine mediated pulmonary smooth muscle hyperplasia. Approach and Results Stimulation of BMPR axis resulted in attenuation of synergistic increase in the proliferation of human pulmonary arterial smooth muscle cells in response to cocaine and HIV protein, Trans-Activator of Transcription (Tat). Interestingly, an increase in mRNA but decrease in protein levels of BMPR with correlated decrease in the activation of SMAD1/5/8 and Id1 gene expression was observed on combined treatment with cocaine and Tat compared to untreated cells at all-time points tested. Although longer exposure to either cocaine or Tat alone also resulted in a significant decrease in the BMPR protein expression, the abrogation on combined treatment was still significantly more compared to mono-treatments. Significant increase in mRNA but down-modulation of BMPR protein expression was also observed in the lung extracts from HIV-infected intravenous drug users (HIV+IVDU) when compared with HIV-infected non-IVDUs (HIV) or un-infected IVDUs (IVDU). Furthermore, significant decrease in BMPR protein expression was also observed in HIV or IVDUs compared to normal controls that correlated with in-vitro findings on chronic exposure to cocaine or HIV protein alone. Conclusion Simultaneous exposure of pulmonary smooth muscle cells to viral protein(s) and cocaine exacerbates down-regulation of BMPR axis that may results in enhanced pulmonary vasculature aberrations in HIV+IVDUs.

No abstract

BackgroundHuman immunodeficiency virus (HIV) infected patients are at increased risk for the development of pulmonary arterial hypertension (PAH). Recent reports have demonstrated that HIV associated viral proteins induce reactive oxygen species (ROS) with resultant endothelial cell dysfunction and related vascular injury. In this study, we explored the impact of HIV protein induced oxidative stress on production of hypoxia inducible factor (HIF)-1α and platelet-derived growth factor (PDGF), critical mediators implicated in the pathogenesis of HIV-PAH.MethodsThe lungs from 4-5 months old HIV-1 transgenic (Tg) rats were assessed for the presence of pulmonary vascular remodeling and HIF-1α/PDGF-BB expression in comparison with wild type controls. Human primary pulmonary arterial endothelial cells (HPAEC) were treated with HIV-associated proteins in the presence or absence of pretreatment with antioxidants, for 24 hrs followed by estimation of ROS levels and western blot analysis of HIF-1α or PDGF-BB.ResultsHIV-Tg rats, a model with marked viral protein induced vascular oxidative stress in the absence of active HIV-1 replication demonstrated significant medial thickening of pulmonary vessels and increased right ventricular mass compared to wild-type controls, with increased expression of HIF-1α and PDGF-BB in HIV-Tg rats. The up-regulation of both HIF-1α and PDGF-B chain mRNA in each HIV-Tg rat was directly correlated with an increase in right ventricular/left ventricular+septum ratio. Supporting our in-vivo findings, HPAECs treated with HIV-proteins: Tat and gp120, demonstrated increased ROS and parallel increase of PDGF-BB expression with the maximum induction observed on treatment with R5 type gp-120CM. Pre-treatment of endothelial cells with antioxidants or transfection of cells with HIF-1α small interfering RNA resulted in abrogation of gp-120CM mediated induction of PDGF-BB, therefore, confirming that ROS generation and activation of HIF-1α plays critical role in gp120 mediated up-regulation of PDGF-BB.ConclusionIn summary, these findings indicate that viral protein induced oxidative stress results in HIF-1α dependent up-regulation of PDGF-BB and suggests the possible involvement of this pathway in the development of HIV-PAH.