Daya Upadhyay

Asbestos-Induced Pulmonary Toxicity: Role of DNA Damage and Apoptosis

Asbestos causes asbestosis and various malignancies by mechanisms that are not clearly defined. Here, we review the accumulating evidence showing that asbestos is directly genotoxic by inducing DNA strand breaks (DNA-SB) and apoptosis in relevant lung target cells. Although the exact mechanisms by which asbestos causes DNA damage and apoptosis are not firmly established, some of the implicated mechanisms include the generation of iron-derived reactive oxygen species (ROS) as well as reactive nitrogen species (RNS), alteration in the mitochondrial function, and activation of the death receptor pathway. We focus on the accumulating evidence implicating ROS. DNA repair mechanisms have a key role in limiting the extent of DNA damage. Recent studies show that asbestos activates DNA repair enzymes such as apurinic/apyrimidinic endonuclease (APE) and poly (ADP-ribose) polymerase (PARP). Asbestos-induced neoplastic transformation may result in the setting where DNA damage overwhelms DNA repair in the face of a persistent proliferative signal. Strategies aimed at limiting asbestos-induced oxidative stress may reduce DNA damage and, as such, prevent malignant transformation.

SPARC Suppresses Apoptosis of Idiopathic Pulmonary Fibrosis Fibroblasts through Constitutive Activation of β-Catenin

Idiopathic pulmonary fibrosis (IPF) is a poorly understood progressive disease characterized by the accumulation of scar tissue in the lung interstitium. A hallmark of the disease is areas of injury to type II alveolar epithelial cells with attendant accumulation of fibroblasts in areas called fibroblastic foci. In an effort to better characterize the lung fibroblast phenotype in IPF patients, we isolated fibroblasts from patients with IPF and looked for activation of signaling proteins, which could help explain the exaggerated fibrogenic response in IPF. We found that IPF fibroblasts constitutively expressed increased basal levels of SPARC, plasminogen activator inhibitor-1 (PAI-1), and active β-catenin compared with control cells. Control of basal PAI-1 expression in IPF fibroblasts was regulated by SPARC-mediated activation of Akt, leading to inhibition of glycogen synthase kinase-3β and activation of β-catenin. Additionally, IPF fibroblasts (but not control fibroblasts) were resistant to plasminogen-induced apoptosis and were sensitized to plasminogen-mediated apoptosis by inhibition of SPARC or β-catenin. These findings uncover a newly discovered regulatory pathway in IPF fibroblasts that is characterized by elevated SPARC, giving rise to activated β-catenin, which regulates expression of downstream genes, such as PAI-1, and confers an apoptosis-resistant phenotype. Disruption of this pathway may represent a novel therapeutic target in IPF.

Rhabdomyolysis associated with 2009 influenza A(H1N1).

dations for the management of patients with herpes zoster recommend using antiviral therapy to decrease the incidence of PHN,” citing an article for which I am a coauthor. This article stated that antiviral therapy should be used to treat patients with herpes zoster and that it had an impact on acute neuritis. Although the guidelines concluded that the use of antiviral therapy may have an effect on “chronic pain,” this therapy was not sufficient to uniformly prevent PHN. As noted here, the FDA reached a similar conclusion. The goal of management of herpes zoster is to accelerate healing, prevent complications, and decrease pain—both acute pain and PHN. With the evidence available from existing antiviral studies, these end points have been achieved with the exception of prevention of PHN. The management of PHN is of critical importance for individuals who have herpes zoster. Consideration of combination therapy at the onset of disease, particularly in patients with severe acute pain, needs to be further evaluated. Future treatment strategies may prevent or provide more significant relief for this potentially devastating complication.

Air pollution induces enhanced mitochondrial oxidative stress in cystic fibrosis airway epithelium

We studied the effects of airborne particulate matters (PM) on cystic fibrosis (CF) epithelium. We noted that PM enhanced human CF bronchial epithelial apoptosis, activated caspase‐9 and PARP‐1; and reduced mitochondrial membrane potential. Mitochondrial inhibitors (4,4‐diisothiocyanatostilbene‐2,2′disulfonic acid, rotenone and thenoyltrifluoroacetone) blocked PM‐induced generation of reactive oxygen species and apoptosis. PM upregulated pro‐apoptotic Bad, Bax, p53 and p21; and enhanced mitochondrial localization of Bax. The anti‐apoptotic Bcl‐2, Bcl‐xl, Mcl‐1 and Xiap remained unchanged; however, overexpression of Bcl‐xl blocked PM‐induced apoptosis. Accordingly, we provide the evidence that PM enhances oxidative stress and mitochondrial signaling mediated apoptosis via the modulation of Bcl family proteins in CF.

Variability in interventions with pulmonary artery catheter data

ObjectivesTo determine if intensivists given PAC data from critically ill patients make uniform management choices.DesignCross-sectional survey of board-certified intensivists.SettingMedical intensive care unit.ParticipantsBoard-certified intensivists who are members of the American College of Chest Physicians and Society of Critical Care Medicine.InterventionsA survey questionnaire containing three medical intensive care clinical vignettes was mailed to critical care physicians. Each vignette contained PAC data and one-half of the surveys contained echocardiographic (Echo) information. Every respondent was asked to select one of six interventions for each vignette.MeasurementsThere were 126 evaluable surveys returned. In vignette 1 an intervention (none of the above) was selected by more than 50% of respondents. In vignettes 2 and 3, the most frequent selection was chosen only 44 and 37% of the times, respectively. There was a significant difference in the distribution of management choices between the Echo and the non-Echo subgroups.ConclusionsThere is significant heterogeneity in selecting an intervention based on PAC data among intensivists. The presence of Echo information may change the intervention selected but does not reduce heterogeneity. Any randomized trial evaluating efficacy of PACs will have to have strict treatment protocols.

Ambient particulate matter induces alveolar epithelial cell cycle arrest: role of G1 cyclins.

We hypothesized that the ambient air pollution particles (particulate matter; PM) induce cell cycle arrest in alveolar epithelial cells (AEC). Exposure of PM (25 μg/cm2) to AEC induced cells cycle arrest in G1 phase, inhibited DNA synthesis, blocked cell proliferation and caused decrease in cyclin E, A, D1 and Cyclin E‐ cyclin‐dependent kinase (CDK)‐2 kinase activity after 4 h. PM induced upregulation of CDK inhibitor, p21 protein and p21 activity in AEC. SiRNAp21 blocked PM‐induced downregulation of cyclins and AEC G1 arrest. Accordingly, we provide the evidence that PM induces AEC G1 arrest by altered regulation of G1 cyclins and CDKs.

The role and regulation of microRNAs in asthma.

Purpose of reviewAsthma is a common chronic inflammatory airway disorder that is characterized by variable and recurring airflow obstruction, chronic airway inflammation and bronchial hyper-responsiveness. The etiopathogenesis of asthma remains a complex issue. The intricacy in developing a more effective therapeutic strategy may be due to a large diversity in causative agents and a lack of understanding of the precise molecular mechanism involved in asthma. However, recent identification of microRNAs (miRs) has enhanced technological abilities to understand the disease process. Recent findingsmiRs regulate gene expression by controlling the translation of a specific type of messenger RNA. miRs have been recently identified as key regulatory RNAs with immense significance in numerous biological processes including asthma. miRs have been implicated to have a fundamental role in acute and chronic asthma and in airway remodeling by the regulation of multiple signal transduction pathways that are involved in the pathogenesis of asthma. It is possible that miRs may bring a fundamental change to our understanding of the pathophysiology of asthma. This may then lead to the development of novel efficacious therapeutic strategies in asthma. SummaryIn this review, we highlight the current understanding of the role and regulation of miRs in asthma.

Inhibition of Inflammatory Mediators Role of Statins in Airway Inflammation

Objective. To determine if statins induce anti-inflammatory effects in upper airway inflammation. Mediators of innate and adaptive immunity regulate airway inflammation. Release of these mediators involves enzymatic conversion of polyunsaturated fatty acids into biologically active mediators, which can be blocked by statins. Although upper airway inflammation and chronic sinusitis occur in millions of patients with asthma worldwide, the anti-inflammatory effects of statins in upper airway inflammation have not been previously studied. Study Design. Laboratory research. Setting. Tertiary referral center. Subjects and Methods. Analysis of sinus tissues collected from patients with chronic rhinosinusitis revealed suppression of highly expressed inflammatory mediators in patients who were found to be on statins, suggesting that statins may induce anti-inflammatory effects. Therefore, the authors performed an in vitro study to determine if these anti-inflammatory effects were induced by statins. Cultured primary human airway epithelial cells were exposed to ambient air pollution particulates (PM) to trigger the inflammation, with and without statins, and the expression of inflammatory mediators was analyzed. Results. The authors found that expression of CCL5, CCL11, and IL13RA was suppressed in patients on statins. In vitro exposure to PM enhanced the expression of these mediators, while pretreatment with statins completely blocked these effects. Furthermore, the effects of statins were blocked by inhibition of the statin pathway using isopentenyl-5-pyrophosphate. Statins did not have any significant effect on the viability of normal cells. Conclusion. Statins induce anti-inflammatory effects in human airway epithelial inflammation. Statins may play a role in the treatment and prevention of chronic rhinosinusitis and pulmonary exacerbation of obstructive airway diseases.

Fibroblast growth factor-10 upregulates Na,K-ATPase via the MAPK pathway

We studied the effects of fibroblast growth factor (FGF‐10) on alveolar epithelial cell (AEC) Na,K‐ATPase regulation. Within 30 min FGF‐10 increased Na,K‐ATPase activity and α1 protein abundance by 2.5‐fold at the AEC plasma membrane. Pretreatment of AEC with the mitogen‐activated protein kinase (MAPK) inhibitor U0126, a Grb2‐SOS inhibitor (SH3‐b‐p peptide), or a Ras inhibitor (farnesyl transferase inhibitor (FTI 277)), as well as N17‐AEC that express a Ras dominant negative protein each prevented FGF‐10‐mediated Na,K‐ATPase recruitment to the AEC plasma membrane. Accordingly, we provide first evidence that FGF‐10 upregulates (short‐term) the Na,K‐ATPase activity in AEC via the Grb2‐SOS/Ras/MAPK pathway.

Nicotine induces resistance to chemotherapy in nasal epithelial cancer.

Background Epidemiological and clinical data implicate that in patients with cancer, continued smoking causes progression of cancer growth and resistance to therapy. The carcinogens possess the ability to block apoptosis, an important mechanism in the development of tumors and resistance to chemotherapy. We previously showed that nicotine enhances growth and proliferation in lung cancer. However, the effects of nicotine, a tobacco carcinogen that inhibits apoptosis, have not been studied before in nasal epithelial carcinoma (NC). In this study, we sought to determine the effects of nicotine on chemotherapy-induced apoptosis in human NC. Methods Primary human NC cells were grown per protocol, treated with combination chemotherapy, and the apoptosis was assessed by TUNEL (terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling) and DNA fragmentation assays. The regulation of mitogen-activated protein kinase (MAPK) and protein kinase B (AKT) signal transduction pathway was examined by real time quantitative polymerized chain reaction, and immunofluorescent staining assays. Results Combination chemotherapy with cisplatin (35 μM) plus etoposide (20 μM) caused a significant increase in NC apoptosis compared with single agent alone, and nicotine, in part, inhibited chemotherapy-induced apoptosis in NC. Furthermore, nicotine induced activation of AKT and MAPK pathways, while inhibition of MAPK using U0126 and AKT by phosphatidylinositol 3-kinase inhibitor, LY294002, in part, blocked the antiapoptotic effects of nicotine against cisplatin and etoposide-induced apoptosis in NC. Conclusion Nicotine inhibits chemotherapy-induced apoptosis in NC via the AKT and MAPK-mediated signaling pathways. We speculate that nicotine may play a role in oncogenesis and resistance to cancer therapy in NC.