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Biomedical subjects

Irina Petrache

Publications and source records attributed to Irina Petrache.

12 recordsLinked to original sources
PubMed2006

A novel antiapoptotic role for alpha1-antitrypsin in the prevention of pulmonary emphysema.

RATIONALE: There is growing evidence that alveolar cell apoptosis plays an important role in emphysema pathogenesis, a chronic inflammatory lung disease characterized by alveolar destruction. The association of alpha1-antitrypsin deficiency with the development of emphysema has supported the concept that protease/antiprotease imbalance mediates cigarette smoke-induced emphysema. OBJECTIVES: We propose that, in addition to its antielastolytic effects, alpha1-antitrypsin may have broader biological effects in the lung, preventing emphysema through inhibition of alveolar cells apoptosis. METHODS, MEASUREMENTS, AND MAIN RESULTS: Transduction of human alpha1-antitrypsin via replication-deficient adeno-associated virus attenuated airspace enlargement and emphysema caused by inhibition of vascular endothelial growth factor (VEGF) receptors with SU5416 in mice, a model of apoptosis-dependent emphysema lacking neutrophilic inflammation. The overexpressed human serine protease inhibitor accumulated in lung cells and suppressed caspase-3 activation and oxidative stress in lungs treated with the VEGF blocker or with VEGF receptor-1 and -2 antibodies. Similar results were obtained in SU5416-treated rats given human alpha1-antitrypsin intravenously. CONCLUSIONS: Our findings suggest that inhibition of structural alveolar cell apoptosis by alpha1-antitrypsin represents a novel protective mechanism of the serpin against emphysema. Further elucidation of this mechanism may extend the therapeutic options for emphysema caused by reduced level or loss of function of alpha1-antitrypsin.

Adenoviridae↗
PubMed2006

State of the art. Cellular and molecular mechanisms of alveolar destruction in emphysema: an evolutionary perspective.

Emphysema consists of a unique pattern of alveolar destruction, resulting in marked airspace enlargement with reduction of alveolar capillary exchange area. Classical concepts of the pathogenesis of emphysema have relied on the paradigm set by the inflammation and protease/antiprotease imbalance. We propose herein that cigarette smoke constitutes an environmental hazard that causes alveolar destruction by the interaction of apoptosis, oxidative stress, and protease/antiprotease imbalance. We draw a parallel between organismal aging, organ structural maintenance, and the damage resulting from chronic cigarette smoke inhalation. The stochastic interaction between environmental hazards and the effort of an organism or a particular organ to fend off these hazards results in the accumulation of cellular damage and features characteristic of aging. Inflammation follows as the result of the multiplication of injuries. We highlight the importance of understanding the biology of the interaction of alveolar cells in homeostasis and in alveolar destruction, and the potential role of novel processes related to senescence and stress response. An evolutionary perspective of emphysema that incorporates mechanisms related to aging may lead to important advances in the understanding and therapeutic targeting of chronic obstructive pulmonary disease.

Aging↗
PubMed2006

Role of lung maintenance program in the heterogeneity of lung destruction in emphysema.

Centrilobular emphysema caused by chronic cigarette smoking is a heterogeneous disease with a predominance of upper lobe involvement. It is presumed that this heterogeneity indicates a particular susceptibility to cigarette smoke or the fact that the inhaled smoke distributes preferentially to upper lung zones. The less involved areas might therefore retain the capacity for lung regeneration and gain of pulmonary function in terminally ill patients. We propose that the interplay between molecular and cellular switches involved in the lung response to environmental injuries determines the heterogeneous pattern of emphysema due to cigarette smoke. Regional activation of alveolar destruction by apoptosis and oxidative stress coupled with regional failure of defense mechanisms may account for the irregular pattern of lung destruction in cigarette smoke-induced emphysema. Protection afforded by the key antioxidant transcription factor Nrf-2 and the antiproteolytic and antiapoptotic actions of alpha(1)-antitrypsin is central to maintain lung homeostasis and lung structure. As the lung is injured by environmental pollutants, including cigarette smoke, molecular sensors of cellular stress, such as the mTOR/protein translation regulator RTP-801, may engage both inflammation and alveolar cell apoptosis. As injury prevails during the course of this chronic disease, it leads to a more homogeneous pattern of lung disease.

Apoptosis↗
PubMed2006

alpha-1 antitrypsin inhibits caspase-3 activity, preventing lung endothelial cell apoptosis.

alpha-1 Antitrypsin (A1AT) is an abundant circulating serpin with a postulated function in the lung of potently inhibiting neutrophil-derived proteases. Emphysema attributable to A1AT deficiency led to the concept that a protease/anti-protease imbalance mediates cigarette smoke-induced emphysema. We hypothesized that A1AT has other pathobiological relevant functions in addition to elastase inhibition. We demonstrate a direct prosurvival effect of A1AT through inhibition of lung alveolar endothelial cell apoptosis. Primary pulmonary endothelial cells internalized human A1AT, which co-localized with and inhibited staurosporine-induced caspase-3 activation. In cell-free studies, native A1AT, but not conformers lacking an intact reactive center loop, inhibited the interaction of recombinant active caspase-3 with its specific substrate. Furthermore, overexpression of human A1AT via replication-deficient adeno-associated virus markedly attenuated alveolar wall destruction and oxidative stress caused by caspase-3 instillation in a mouse model of apoptosis-dependent emphysema. Our findings suggest that direct inhibition of active caspase-3 by A1AT may represent a novel anti-apoptotic mechanism relevant to disease processes characterized by excessive structural cell apoptosis, oxidative stress, and inflammation, such as pulmonary emphysema.

Animals↗
PubMed2005

Pulmonary ischemia induces lung remodeling and angiogenesis.

Cellular remodeling during angiogenesis in the lung is poorly described. Furthermore, it is the systemic vasculature of the lung and surrounding the lung that is proangiogenic when the pulmonary circulation becomes impaired. In a mouse model of chronic pulmonary thromboembolism, after left pulmonary artery ligation (LPAL), the intercostal vasculature, in proximity to the ischemic lung, proliferates and invades the lung (12). In the present study, we performed a detailed investigation of the kinetics of remodeling using histological sections of the left lung of C57Bl/6J mice after LPAL (4 h to 20 days) or after sham surgery. New vessels were seen within the thickened visceral pleura 4 days after LPAL predominantly in the upper portion of the left lung. Connections between new vessels within the pleura and pulmonary capillaries were clearly discerned by 7 days after LPAL. The visceral pleura and the lung parenchyma showed intense tissue remodeling, as evidenced by markedly elevated levels of both proliferating cell nuclear antigen and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling positive cells. Rapidly dividing cells were predominantly macrophages and type II pneumocytes. The increased apoptotic activity was further quantified by caspase-3 activity, which showed a sixfold increase relative to naive lungs, by 24 h after LPAL. Because sham surgeries had little effect on measured parameters, we conclude that both thoracic wound healing and pulmonary ischemia are required for systemic neovascularization.

Animals↗
PubMed2005

Ceramide upregulation causes pulmonary cell apoptosis and emphysema-like disease in mice.

Alveolar cell apoptosis is involved in the pathogenesis of emphysema, a prevalent disease primarily caused by cigarette smoking. We report that ceramide, a second messenger lipid, is a crucial mediator of alveolar destruction in emphysema. Inhibition of enzymes controlling de novo ceramide synthesis prevented alveolar cell apoptosis, oxidative stress and emphysema caused by blockade of the vascular endothelial growth factor (VEGF) receptors in both rats and mice. Emphysema was reproduced with intratracheal instillation of ceramide in naive mice. Excessive ceramide triggers a feed-forward mechanism mediated by activation of secretory acid sphingomyelinase, as suggested by experiments with neutralizing ceramide antibody in mice and with acid sphingomyelinase-deficient fibroblasts. Concomitant augmentation of signaling initiated by a prosurvival metabolite, sphingosine-1-phosphate, prevented lung apoptosis, implying that a balance between ceramide and sphingosine-1-phosphate is required for maintenance of alveolar septal integrity. Finally, increased lung ceramides in individuals with smoking-induced emphysema suggests that ceramide upregulation may be a crucial pathogenic element and a promising target in this disease that currently lacks effective therapies.

Acyltransferases↗
PubMed2004

Genetic ablation of Nrf2 enhances susceptibility to cigarette smoke-induced emphysema in mice.

Although inflammation and protease/antiprotease imbalance have been postulated to be critical in cigarette smoke-induced (CS-induced) emphysema, oxidative stress has been suspected to play an important role in chronic obstructive pulmonary diseases. Susceptibility of the lung to oxidative injury, such as that originating from inhalation of CS, depends largely on its upregulation of antioxidant systems. Nuclear factor, erythroid-derived 2, like 2 (Nrf2) is a redox-sensitive basic leucine zipper protein transcription factor that is involved in the regulation of many detoxification and antioxidant genes. Disruption of the Nrf2 gene in mice led to earlier-onset and more extensive CS-induced emphysema than was found in wild-type littermates. Emphysema in Nrf2-deficient mice exposed to CS for 6 months was associated with more pronounced bronchoalveolar inflammation; with enhanced alveolar expression of 8-oxo-7,8-dihydro-2'-deoxyguanosine, a marker of oxidative stress; and with an increased number of apoptotic alveolar septal cells--predominantly endothelial and type II epithelial cells--as compared with wild-type mice. Microarray analysis identified the expression of nearly 50 Nrf2-dependent antioxidant and cytoprotective genes in the lung that may work in concert to counteract CS-induced oxidative stress and inflammation. The responsiveness of the Nrf2 pathway may act as a major determinant of susceptibility to tobacco smoke-induced emphysema by upregulating antioxidant defenses and decreasing lung inflammation and alveolar cell apoptosis.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2003

Central involvement of Rho family GTPases in TNF-alpha-mediated bovine pulmonary endothelial cell apoptosis.

In our recent studies, we defined a critical role for increased levels of myosin light chain (MLC) phosphorylation, a regulatory event in the interaction between actin and myosin in TNF-alpha-induced pulmonary endothelial cell actomyosin rearrangement and apoptosis. The Rho GTPase effector, Rho kinase is an important signaling effector governing levels of MLC phosphorylation which contributes to plasma membrane blebbing in several models of apoptosis. In this study, we directly assessed the role of Rho kinase in TNF-alpha-induced endothelial cell microfilament rearrangement and apoptosis. Inhibition of RhoA GTPase activity by the overexpression of dominant negative RhoA attenuates TNF-alpha-triggered stress fiber formation, consistent with Rho activation as a key event in TNF-alpha-induced cytoskeletal rearrangement. Furthermore, pharmacologic inhibition of Rho kinase as well as dominant negative RhoA overexpression dramatically reduced TNF-alpha-induced bovine endothelial apoptosis reflected by nucleosomal fragmentation as well as caspase 7, 3, and 8 activation. These results indicate that Rho kinase-dependent cytoskeletal rearrangement is critical for early apoptotic events, possibly in the assembly of the death-inducing signaling complex leading to initiator and effector caspase activation, and suggest a novel role for Rho GTPases in endothelial cell apoptosis.

Actins↗
PubMed2003

Caspase-dependent cleavage of myosin light chain kinase (MLCK) is involved in TNF-alpha-mediated bovine pulmonary endothelial cell apoptosis.

Cytoskeletal proteins are key participants in the cellular progression to apoptosis. Our previous work demonstrated the critical dependence of actomyosin rearrangement and MLC phosphorylation in TNF-alpha-induced endothelial cell apoptosis. As these events reflect the activation of the multifunctional endothelial cell (EC) MLCK isoform, we assessed the direct role of EC MLCK in the regulation of TNF-alpha-induced apoptosis. Bovine pulmonary artery endothelial cells expressing either an adenovirus encoding antisense MLCK cDNA (Ad.GFP-AS MLCK) or a dominant/negative EC MLCK construct (EC MLCK-ATPdel) resulted in marked reductions in MLCK activity and TNF-alpha-mediated apoptosis. In contrast, a constitutively active EC MLCK lacking the carboxyl-terminal autoinhibitory domains (EC MLCK-1745) markedly enhanced the apoptotic response to TNF-alpha. Immunostaining in GFP-EC MLCK-expressing cells revealed colocalization of caspase 8 and EC MLCK along actin stress fibers after TNF-alpha. TNF-alpha induced the caspase-dependent cleavage of EC MLCK-1745 in transfected endothelial cells, which was confirmed by mass spectroscopy with in vitro cleavage by caspase 3 at LKKD (D1703). The resulting MLCK fragments displayed significant calmodulin-independent kinase activity. These studies convincingly demonstrate that novel interactions between the apoptotic machinery and EC MLCK exist that regulate the endothelial contractile apparatus in TNF-alpha-induced apoptosis.

Animals↗
PubMed2003

The role of the microtubules in tumor necrosis factor-alpha-induced endothelial cell permeability.

Tumor necrosis factor (TNF)-alpha, a major proinflammatory cytokine, triggers endothelial cell activation and barrier dysfunction which are implicated in the pathogenesis of pulmonary edema associated with acute lung injury syndromes. The mechanisms of TNF-alpha-induced vascular permeability are not completely understood. Our initial experiments demonstrated that TNF-alpha-induced decreases in transendothelial electrical resistance across human pulmonary artery endothelial cells are independent of myosin light chain phosphorylation catalyzed by either myosin light chain kinase or Rho kinase. We next assessed the involvement of another cytoskeletal component, the tubulin-based microtubule network, and found TNF-alpha to induce a decrease in stable tubulin content and partial dissolution of peripheral microtubule network as evidenced by anti-acetylated tubulin and anti-beta-tubulin immunofluorescent staining, respectively. Microtubule-stabilizing agents, paclitaxel and epothilone B, significantly attenuated TNF-alpha-induced decreases in transendothelial electrical resistance, inhibited the cytokine-induced increases in actin stress fibers, formation of intercellular gap, and restored the TNF-alpha-compromised vascular endothelial (VE)-cadherin-based cell-cell junctions. Importantly, neither TNF-alpha nor paclitaxel treatment was associated with endothelial cell apoptosis. Inhibition of p38 mitogen-activated protein kinase by SB203580 significantly attenuated TNF-alpha-induced microtubule destabilization, actin rearrangement, and endothelial barrier dysfunction. These results strongly suggest the involvement of microtubule rearrangement in TNF-alpha-induced endothelial cell permeability via p38 mitogen-activated protein kinase activation.

Actins↗