Pulmonary Epithelial Cell Apoptosis Research Articles

Pasteurella multocida activates Rassf1-Hippo-Yap pathway to induce pulmonary epithelial apoptosis

Pasteurella multocida is an opportunistic zoonotic pathogen that primarily causes fatal respiratory diseases, such as pneumonia and respiratory syndromes. However, the precise mechanistic understanding of how P. multocida disrupts the epithelial barrier in mammalian lung remains largely unknown. In this study, using unbiased RNA-seq analysis, we found that the evolutionarily conserved Hippo-Yap pathway was dysregulated after P. multocida infection. Given the complexity of P. multocida infection associated with lung injury and systemic inflammatory processes, we employed a combination of cell culture models, mouse models, and rabbit models to investigate the dynamics of the Hippo-Yap pathway during P. multocida infection. Our findings reveal that P. multocida infection activates the Hippo-Yap pathway both in vitro and in vivo, by upregulating the upstream factors p-Mst1/2, p-Lats1, and p-Yap, and downregulating the downstream effectors Birc5, Cyr61, and Slug. Conversely, pharmacological inhibition of the Hippo pathway by XMU-MP-1 significantly rescued pulmonary epithelial cell apoptosis in vitro and reduced lung injury, systemic inflammation, and mouse mortality in vivo. Mechanistic studies revealed that P. multocida induced up-regulation of Rassf1 expression, and Rassf1 enhanced Hippo-Yap pathway through phosphorylation. Accordingly, in vitro knockdown of Rassf1 significantly enhanced Yap activity and expression of Yap downstream factors and reduced apoptosis during P. multocida infection. P. multocida-infected rabbit samples also showed overexpression of Rassf1, p-Lats1, and p-Yap, suggesting that P. multocida activates the Rassf1-Hippo-Yap pathway. These results elucidate the pathogenic role of the Rassf1-Hippo-Yap pathway in P. multocida infection and suggest that this pathway has the potential to be a drug target for the treatment of pasteurellosis.

Stellate ganglion block relieves acute lung injury induced by severe acute pancreatitis via the miR-155-5p/SOCS5/JAK2/STAT3 axis

Acute lung injury (ALI), a prevalent complication of severe acute pancreatitis (SAP), is also a leading contributor to respiratory failure and even death of SAP patients. Here, we intended to investigate the function and mechanism of stellate ganglion block (SGB) in ameliorating SAP-induced ALI (SAP-ALI). We engineered an SAP-ALI model in rats and treated them with SGB. HE staining and the dry and wet method were implemented to evaluate pathological alterations in the tissues and pulmonary edema. The rats serum changes of the profiles of TNF-α, IL-6, IL-1β, and IL-10 were examined. The profiles of miR-155-5p and SOCS5/JAK2/STAT3 were detected. Functional assays were performed for confirming the role of miR-155-5p in modulating the SOCS5/JAK2/STAT3 pathway in pulmonary epithelial cells. Our findings revealed that SGB vigorously alleviated SAP rat lung tissue damage and lung edema and lessened the generation of pro-inflammatory cytokines TNF-α, IL-6, and IL-1β. SGB enhanced SOCS5 expression, hampered miR-155-5p, and suppressed JAK2/STAT3 pathway activation. As evidenced by mechanism studies, miR-155-5p targeted the 3′UTR of SOCS5 and repressed its expression, hence resulting in JAK2/STAT3 pathway activation. During animal trials, we discovered that SGB ameliorated SAP-ALI, boosted SOCS5 expression, and mitigated the levels of pro-inflammatory factors and miR-155-5p in the plasma. In vitro, miR-155-5p overexpression substantially facilitated pulmonary epithelial cell apoptosis, inflammation, and JAK2/STAT3 pathway activation and restrained SOCS5 expression. All in all, our work hinted that SGB could modulate the miR-155-5p/SOCS5/JAK2/STAT3 axis to alleviate SAP-ALI.

Compounds in cigarette smoke induce EGR1 expression via the AHR, resulting in apoptosis and COPD.

Chronic obstructive pulmonary disease (COPD) is a major cause of mortality worldwide, and pulmonary epithelial cell apoptosis is regarded as one of the most important factors in its pathogenesis. Here, we examined the molecular mechanisms of apoptosis caused by cigarette smoke (CS). In the normal bronchial epithelium cell line BEAS-2B, a CS extract markedly induced apoptosis together with transient early growth response 1 (EGR1) protein expression, which is activated over time via the aryl hydrocarbon receptor (AHR). The CS extract-induced apoptosis decreased cell count of BEAS-2B cells and was significantly reversed by knockdown of either EGR1 or AHR. In vivo, the CS extract caused alveolar wall destruction, mimicking COPD, 1week after intrathoracic injection. Bronchoalveolar lavage fluid (BALF) from the CS extract-treated mice contained massive numbers of apoptotic epithelial cells. Furthermore, it was found that aminoanthracene induced EGR1 expression and cell apoptosis. By contrast, the AHR antagonist stemregenin 1 (SR1) restored apoptosis upon CS treatment. These results suggest that aryl hydrocarbons, such as aminoanthracene, induce EGR1 expression via the AHR, resulting in cell apoptosis and that this can be prevented by administration of an antagonist of AHR.

Phillygenin inhibits the inflammation and apoptosis of pulmonary epithelial cells by activating PPARγ signaling via downregulation of MMP8.

Acute lung injury (ALI) is often responsible for the high morbidity of critically ill patients. The present study aimed to investigate whether phillygenin (PHI) can inhibit inflammation and apoptosis of pulmonary epithelial cells by activating peroxisome proliferator-activated receptor γ (PPARγ) signaling. The in vitro model of ALI was established using lipopolysaccharide (LPS) and PHI was used to treat the LPS-induced cells. Cell viability was assessed using the MTT assay and the concentration levels of the inflammatory factors were detected by ELISA. Western blotting and reverse transcription-quantitative PCR were conducted to measure the expression levels of the inflammation- and apoptosis-associated proteins. The MMP8-overexpression plasmid was transfected into LPS-induced cells, which were treated with PHI treatment and the expression levels of PPARγ were detected via western blotting. PHI treatment suppressed the induction of inflammation and apoptosis of LPS-induced BEAS-2B cells. Furthermore, the expression levels of MMP8 in BEAS-2B cells induced by LPS were decreased following PHI treatment. Following transfection of the MMP8 overexpression plasmid into the LPS-induced BEAS-2B cells and subsequent treatment of these cells with PHI, the expression levels of PPARγ were decreased. In conclusion, it was shown that PHI inhibited the inflammation and apoptosis of pulmonary epithelial cells by activating PPARγ signaling via downregulating MMP8. These data may provide valuable information for future studies exploring the therapeutic effects of PHI for ALI.

MUTYH Deficiency Is Associated with Attenuated Pulmonary Fibrosis in a Bleomycin-Induced Model

Idiopathic pulmonary fibrosis (IPF) is a progressive, irreversible lung disease of unknown etiology with limited survival. IPF incidence and prevalence increase significantly with aging, which is associated with an age-related accumulation of oxidative DNA damage. The Mutyh gene is involved in the base excision repair (BER) system, which is critical for repairing the misincorporated adenine that is opposite to the oxidized guanine base, 8-oxoguanine, and maintaining the fidelity of DNA replication. We used Mutyh knockout mice and a bleomycin-induced pulmonary fibrosis model to test the effect of MUTYH deficiency on lesion progression. Unexpectedly, a much less severe lesion of pulmonary fibrosis was observed in Mutyh−/− than in Mutyh+/+mice, which was supported by assay on protein levels of TGF-β1 and both fibrotic markers, α-SMA and Vimentin, in pulmonary tissues of the model animals. Mechanically, MUTYH deficiency prevented the genomic DNA of pulmonary tissue cells from the buildup of single-strand breaks (SSBs) of DNA and maintained the integrity of mtDNA. Furthermore, increased mitochondrial dynamic regulation and mitophagy were detected in pulmonary tissues of the bleomycin-induced Mutyh−/− model mice, which could reduce the pulmonary epithelial cell apoptosis. Our results suggested that MUTYH deficiency could even induce protective responses of pulmonary tissue under severe oxidative stress.

Regulatory mechanism of NOV/CCN3 in the inflammation and apoptosis of lung epithelial alveolar cells upon lipopolysaccharide stimulation.

Lipopolysaccharide (LPS) induces inflammatory stress and apoptosis. Pulmonary epithelial cell apoptosis has been shown to accelerate the progression of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), and is the leading cause of mortality in patients with ALI/ARDS. Nephroblastoma overexpressed (NOV; also known as CCN3), an inflammatory modulator, is reported to be a biomarker in ALI. Using an LPS-induced ALI model, we investigated the expression of CCN3 and its possible molecular mechanism involved in lung alveolar epithelial cell inflammation and apoptosis. Our data revealed that LPS treatment greatly increased the level of CCN3 in human lung alveolar type II epithelial cells (A549 cell line). The A549 cells were also transfected with a specific CCN3 small interfering RNA (siRNA). CCN3 knockdown not only largely attenuated the expression of inflammatory cytokines, interleukin (IL)-1β and transforming growth factor (TGF)-β1, but also reduced the apoptotic rate of the A549 cells and altered the expression of apoptosis-associated proteins (Bcl-2 and caspase-3). Furthermore, CCN3 knockdown greatly inhibited the activation of nuclear factor (NF)-κB p65 in the A549 cells, and TGF-β/p-Smad and NF-κB inhibitors significantly decreased the expression level of CCN3 in A549 cells. In conclusion, our data indicate that CCN3 knockdown affects the expression of downstream genes through the TGF-β/p-Smad or NF-κB pathways, leading to the inhibition of cell inflammation and apoptosis in human alveolar epithelial cells.

Silencing of lncRNA MALAT1 Prevents Inflammatory Injury after Lung Transplant Ischemia-Reperfusion by Downregulation of IL-8 via p300

Ischemia-reperfusion injury is a common early complication after lung transplantation. It was reported that long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is involved in ischemia-reperfusion injury and regulates inflammation. This study aimed to explore the role of MALAT1 in inflammatory injury following lung transplant ischemia-reperfusion (LTIR). A LTIR rat model was successfully established, with the expression of MALAT1 and interleukin-8 (IL-8) in lung tissues detected. Then, in vitro loss- and gain-of-function investigations were conducted to evaluate the effect of MALAT1 on pulmonary epithelial cell apoptosis and IL-8 expression. The relationship among MALAT1, p300, and IL-8 was tested. Moreover, a sh-MALAT1-mediated model of LTIR was established in vivo to examine inflammatory injury and chemotaxis infiltration. Both IL-8 and MALAT1 were highly expressed in LTIR. MALAT1 interacted with p300 to regulate the IL-8 expression by recruiting p300. Importantly, silencing of MALAT1 inhibited the chemotaxis of neutrophils by downregulating IL-8 expression via binding to p300. Besides, MALAT1 silencing alleviated the inflammatory injury after LTIR by downregulating IL-8 and inhibiting infiltration and activation of neutrophils. Collectively, these results demonstrated that silencing of MALAT1 ameliorated the inflammatory injury after LTIR by inhibiting chemotaxis of neutrophils through p300-mediated downregulation of IL-8, providing clinical insight for LTIR injury.

Matrilin-2 regulates proliferation, apoptosis and cell cycle during radiation-induced injury in HPAEpiC cell

Radiation pulmonary injury is related to the accumulation of extracellular matrix proteins in the alveolar interstitial space. Matrilin-2 as a component of extracellular filamentous networks, present higher level in the lung tissue from irradiated mice and irradiated pulmonary epithelial cell line, HPAEpiC cells. Knockdown of endogenous matrilin-2 prevents the apoptosis of HPAEpiC cell induced by the irradiation injury. Consistently, over-expression of matrilin-2 reduced the proliferation and induced apoptosis of HPAEpiC cells. Matrilin-2 promotes the expression of p21 via increasing the transcriptional activity of p53, by which induces the G1 phase arresting in HPAEpiC cells. In summary, matrilin-2, increased by irradiation, reduced the proliferation and induces apoptosis of pulmonary epithelial cells via p53/p21 pathway.

Abstract 2277: TNF transactivation of EGFR protects EGFR-TKI, gefitinib induced pulmonary epithelial cell apoptosis and injury in TNF transgenic mice

Abstract Background: TNF is a cytokine with many biological properties including both anti- and pro-apoptotic signaling pathways. However, the molecular switch, which determines TNF regulation of these two different functions, is not well characterized. EGFR and other ErbB family members could be activated by direct interaction with EGF-like ligands initiating formation of homo- and/or hetero-dimers and increased kinase activity. In addition to direct EGFR ligands, EGFR can be transactivated by various extracellular stimuli, such as agonists for GPCR and cytokine receptors. Previously, we have reported that EGFR and ErbB2 were transactivated via Src kinase family activation with TNF exposure and blockade of EGFR enhanced intestinal epithelial cells apoptosis. Furthermore, TNF administration enhanced apoptotic cells in colonic grand of EGFRwa2 mice. Hypothesis: The induction of pulmonary epithelial cell apoptosis is a persistent finding in lung tissue from patients with emphysema and pulmonary fibrosis. We hypothesized that EGFR tyrosine kinase activity is required for protection from pulmonary cell apoptosis in TNF-rich condition. Methods: We employed C57BL/6 mice as a control and surfactant protein-C (SP-C)/TNF transgenic (TG) mice (6-8 weeks old), which showed over-expression of TNF in lung tissue by induction of SP-C production. The lung tissue sections were stained by H&E and trichrome stain. Apoptosis and signal transduction was determined by TUNEL assay and Western-blot analysis, respectively. The accumulation of collagen was measured by Sircol assay. Results: Control mice and TG mice was administrated gefitinib 100mg/kg for 14days. Gefitinib increased lymphocyte infiltration into interstitial spaces of the TG mice lung, significantly. Although TG mice lung was severely injured by gefitinib, fibroblast proliferation was not observed and the accumulation of collagen was not detected. In TG mice, gefitinib increased apoptotic response 10-fold compared to 1% tween80 treated TG mice in interstitial spaces. To test the role of EGFR in apoptosis induction in TG mice, the protein was isolated from whole lung tissue. The tyrosine kinase activity of EGFR was increased and the downstream of AKT and ERK were activated in TG mice. Conversely, treating with gefitinib on TG mice, EGFR phosphorylation was inhibited and, AKT and ERK were inactivated. One of the pro-apoptotic signals, p38 MAPK was activated via MKK3/6 by gefitinib treatment in TG mice, suggesting activation of ASK1/p38 MAPK signals leading to pulmonary epithelial cell apoptosis. Conclusions: The dysregulated production of TNF is a mediator of inflammation and tumor growth. Therefore, the mechanisms of TNF-regulated anti-/pro- apoptotic responses are important in understanding the role of TNF in the pathogenesis of pulmonary disorders, such as inflammation and cancer. Citation Format: Toshimitsu Yamaoka, Yasunari Oki, Yasunori Murata, Sojiro Kusumoto, Hiroo Ishida, Takao Shirai, Etsuko Toya, Motoi Ohba, Ken-ichi Fujita, Satoru Arata, Tohru Ohmori, Tsukasa Ohnishi, Hironori Sagara, Yasutsuna Sasaki. TNF transactivation of EGFR protects EGFR-TKI, gefitinib induced pulmonary epithelial cell apoptosis and injury in TNF transgenic mice. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2277. doi:10.1158/1538-7445.AM2014-2277

The effects of erdosteine and N-acetylcysteine on apoptotic and antiapoptotic markers in pulmonary epithelial cells in sepsis.

This study investigated the frequency of apoptosis in rat pulmonary epithelial cells after the injection of an intraperitoneal endotoxin lipopolysaccharide (LPS), the effects of LPS on apoptotic (bax, caspase-3) and antiapoptotic (bcl-2) markers during lung damage, and the protective effects of two known antioxidant agents, erdosteine and N-acetylcysteine (NAC). Male Wistar rats were divided into the following six groups, which included nine rats each: two control groups, two LPS-treated groups, one erdosteine-treated group (150 mg/kg), and one NAC-treated group (150 mg/kg). LPS was injected intraperitoneally at a dosage of 20 mg/kg. Following LPS injection, the antioxidants were orally administered. The rats were sacrificed at 24 h after LPS administration. The levels of apoptosis in bronchiolar and alveolar cells were determined using the TUNEL-staining method. Immunohistochemical staining of cytoplasmic bax, caspase-3, and bcl-2 in the epithelial cells was performed. Erdosteine and NAC significantly reduced the rate of LPS-induced pulmonary epithelial cell apoptosis. The effect of NAC on regulating apoptosis was weaker than that of erdosteine. Erdosteine and NAC significantly reduced the local induction of bax and caspase 3 and significantly increased the reduced local production of bcl-2. These findings suggest that erdosteine and NΑC can effectively protect the lungs from the damaging effects of LPS.

Hypoxia‐induced deoxycytidine kinase expression contributes to apoptosis in chronic lung disease

Chronic obstructive pulmonary disease (COPD) is characterized by persistent inflammation and tissue remodeling and is a leading cause of death in the United States. Increased apoptosis of pulmonary epithelial cells is thought to play a role in COPD development and progression. Identification of signaling pathways resulting in increased apoptosis in COPD can be used in the development of novel therapeutic interventions. Deoxyadenosine (dAdo) is a DNA breakdown product that amplifies lymphocyte apoptosis by being phosphorylated to deoxyadenosine triphosphate (dATP). dAdo is maintained at low levels by adenosine deaminase (ADA). This study demonstrated that mice lacking ADA developed COPD manifestations in association with elevated dAdo and dATP levels and increased apoptosis in the lung. Deoxycitidine kinase (DCK), a major enzyme for dAdo phosphorylation, was up-regulated in mouse and human airway epithelial cells in association with air-space enlargement. Hypoxia was identified as a novel regulator of DCK, and inhibition of DCK resulted in diminished dAdo-mediated apoptosis in the lungs. Our results suggest that activating the dAdo-DCK-dATP pathway directly results in increased apoptosis in the lungs of mice with air-space enlargement and suggests a novel therapeutic target for the treatment of COPD.

A Role for Forkhead Box A1 in Acute Lung Injury

Forkhead box protein A1 (FoxA1) is an evolutionarily conserved winged helix transcription factor with diverse regulatory functions. However, little is known about the role of FoxA1 in acute lung injury (ALI) and pulmonary cell injury. In this study, an in vivo model was employed whereby rats were administered an intravenous injection of oleic acid (OA, 0.1 ml/kg), and alveolar type II epithelial cells (AT-2 cells) injury was induced by hydrogen peroxide (H(2)O(2)) in vitro. OA injection resulted in lung injury and AT-2 cells apoptosis in vivo. OA injection and H(2)O(2) upregulated FoxA1 mRNA and protein in lung tissue of the in vivo ALI model and in H(2)O(2) challenged AT-2 cells. Overexpression of FoxA1 promoted apoptosis, whereas FoxA1 deficiency, induced by antisense oligonucleotides, decreased AT-2 cells apoptosis induced by H(2)O(2), as shown by flow cytometry. These results suggest that FoxA1 may play an important role in ALI by promoting apoptosis of pulmonary epithelial cells.

Epithelial Cell Apoptosis Causes Acute Lung Injury Masquerading as Emphysema

Theories of emphysema traditionally revolved around proteolytic destruction of extracellular matrix. Models have recently been developed that show airspace enlargement with the induction of pulmonary cell apoptosis. The purpose of this study was to determine the mechanism by which a model of epithelial cell apoptosis caused airspace enlargement. Mice were treated with either intratracheal microcystin (MC) to induce apoptosis, intratracheal porcine pancreatic elastase (PPE), or their respective vehicles. Mice from all groups were inflated and morphometry was measured at various time points. Physiology measurements were performed for airway resistance, tissue elastance, and lung volumes. The groups were further analyzed by air-saline quasistatic measurements, surfactant staining, and surfactant functional studies. Mice treated with MC showed evidence of reversible airspace enlargement. In contrast, PPE-treated mice showed irreversible airspace enlargement. The airspace enlargement in MC-treated mice was associated with an increase in elastic recoil due to an increase in alveolar surface tension. PPE-treated mice showed a loss of lung elastic recoil and normal alveolar surface tension, a pattern more consistent with human emphysema. Airspace enlargement that occurs with the MC model of pulmonary epithelial cell apoptosis displays physiology distinct from human emphysema. Reversibility, restrictive physiology due to changes in surface tension, and alveolar enlargement associated with heterogeneous alveolar collapse are most consistent with a mild acute lung injury. Inflation near total lung capacity gives the appearance of enlarged alveoli as neighboring collapsed alveoli exert tethering forces.

Subcellular Expression Pattern and role of IL-15 in Pneumococci induced Lung Epithelial Apoptosis

Streptococcus pneumoniae is the leading causative agent of community-acquired pneumonia. Induction of apoptosis in pulmonary epithelial cells by bacteria during pneumonia might be harmful to the host. Interleukin-15 (IL-15) has been demonstrated as an effective inhibitor of apoptosis and is expressed in lung epithelium on the mRNA and protein level. Therefore, we characterized the sub-cellular expression pattern of the short and long IL-15 isoforms in lung epithelial cells in vitro as well as its role in pneumococci-related lung epithelial cell apoptosis.

Subcellular expression pattern and role of IL-15 in pneumococci induced lung epithelial apoptosis

Streptococcus pneumoniae is the leading causative agent of community-acquired pneumonia. Induction of apoptosis in pulmonary epithelial cells by bacteria during pneumonia might be harmful to the host. Interleukin-15 (IL-15) has been demonstrated as an effective inhibitor of apoptosis and is expressed in lung epithelium on the mRNA and protein level. Therefore, we characterized the sub-cellular expression pattern of the short and long IL-15 isoforms in lung epithelial cells in vitro as well as its role in pneumococci-related lung epithelial cell apoptosis. We found an expression pattern for both IL-15 signal peptides in the pulmonary epithelial cell lines A549 and Beas-2B. Moreover, a strong co-localization of IL-15 and IL-15Ralpha was detected on cell surfaces. Compared to pro-inflammatory cytokine stimulation, neither IL-15 nor its trimeric receptor complex was up-regulated after pneumococcal infection. However, overexpression of IL-15 isoforms revealed IL-15LSP and IL-15Vkl as inhibitors of pneumococci induced apoptosis in pulmonary epithelial cells. Thus, IL-15 may act as an anti-apoptotic molecule in pneumococci infection, thereby suggesting IL-15 as a benefical cytokine in pulmonary host defense against infection.

The UspA1 Protein ofMoraxella catarrhalisInduces CEACAM‐1–Dependent Apoptosis in Alveolar Epithelial Cells

Moraxella catarrhalis is a major cause of exacerbations of chronic obstructive pulmonary disease (COPD) and emphysema. M. catarrhalis-specific UspA1 and the epithelial carcinoembryonic antigen-related cell adhesion molecule (CEACAM1) were required to induce apoptosis. M. catarrhalis-induced apoptosis was significantly enhanced in HeLa cells stably transfected with CEACAM1, compared with HeLa cells not expressing CEACAM1. Infected cells showed increased activity of caspases 3, 6, and 9 but not of caspase 8. Reduced expression of Bcl-2, translocation of Bax into the mitochondria, and cytosolic increase of apoptosis-inducing factor in M. catarrhalis-infected cells implicated the involvement of mitochondrial death pathways. In conclusion, M. catarrhalis induced apoptosis in pulmonary epithelial cells--a process that was triggered by interaction between CEACAM1 and UspA1. Thus, M. catarrhalis-induced apoptosis of pulmonary epithelial cells may contribute to the development of COPD and emphysema.

Fungal Invasion of Normally Non-Phagocytic Host Cells

Many fungi that cause invasive disease invade host epithelial cells during mucosal and respiratory infection, and subsequently invade endothelial cells during hematogenous infection. Most fungi invade these normally non-phagocytic host cells by inducing their own uptake. Candida albicans hyphae interact with endothelial cells in vitro by binding to N-cadherin on the endothelial cell surface. This binding induces rearrangement of endothelial cell microfilaments, which results in the endocytosis of the organism. The capsule of Cryptococcus neoformans is composed of glucuronoxylomannan, which binds specifically to brain endothelial cells, and appears to mediate both adherence and induction of endocytosis. The mechanisms by which other fungal pathogens induce their own uptake are largely unknown. Some angioinvasive fungi, such as Aspergillus species and the Zygomycetes, invade endothelial cells from the abluminal surface during the initiation of invasive disease, and subsequently invade the luminal surface of endothelial cells during hematogenous dissemination. Invasion of normally non-phagocytic host cells has different consequences, depending on the type of invading fungus. Aspergillus fumigatus blocks apoptosis of pulmonary epithelial cells, whereas Paracoccidioides brasiliensis induces apoptosis of epithelial cells. This review summarizes the mechanisms by which diverse fungal pathogens invade normally non-phagocytic host cells and discusses gaps in our knowledge that provide opportunities for future research.

The effects of erdosteine, N-acetylcysteine, and vitamin E on nicotine-induced apoptosis of pulmonary cells

This study was conducted to investigate the frequency of apoptosis in the pulmonary epithelial cells of rats after intratraperitoneal nicotine injection, in order to examine the role of inflammatory markers [myeloperoxidase (MPO) and tumor necrosis factor-alpha (TNF-α)] in nicotine-induced lung damage, and to determine the protective effects of three known antioxidant agents [ N-acetylcysteine (NAC), erdosteine, and vitamin E] on the lung toxicity of nicotine in the lungs. Female Wistar rats were divided into seven groups, each composed of nine rats: two negative control groups, two positive control groups, one erdosteine-treated group (500 mg/kg), one NAC-treated group (500 mg/kg), and one vitamin E-treated group (500 mg/kg). Nicotine was injected intraperitoneally at a dosage of 0.6 mg/kg for 21 days. Following nicotine injection, the antioxidants were administered orally, treatment was continued until the rats were killed. Lung tissue samples were stained with hematoxylin–eosin (H&E) for histopathological assessments. The apoptosis level in the lung bronchiolar and alveolar epithelium was determined by using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) method. Cytoplasmic TNF-α in the bronchiolar and alveolar epithelial cells and the lung MPO activity were evaluated immunohistochemically. The protective effect of vitamin E on lung histology was stronger than that of erdosteine or NAC. Treatment with erdosteine, NAC, and vitamin E significantly reduced the rate of nicotine-induced pulmonary epithelial cell apoptosis, and there were no significant differences in apoptosis among the three antioxidants groups. Erdosteine, NAC, and vitamin E significantly reduced the increases in TNF-α staining and lung MPO activity. The effects of erdosteine on the increases in the local TNF-α level and lung MPO activity were weaker than that of NAC or vitamin E. This findings suggest that erdosteine and NAC can be as effective as vitamin E in protecting against nicotine-induced pulmonary cell apoptosis.

P21Waf1/Cip1 and the prevention of oxidative stress.

pulmonary dysfunction resulting from acute oxygen toxicity is due at least in part to the death of lung epithelial cells. Pulmonary epithelial cells are essential to the maintenance of the alveolar-capillary barrier, and compromise may lead to leakage of fluid and proteins in the airways and alveoli

Deficiency in the c-Jun NH2-terminal kinase signaling pathway confers susceptibility to hyperoxic lung injury in mice.

Hyperoxia generates an oxidative stress in the mouse lung, which activates the major stress-inducible kinase pathways, including c-Jun NH2-terminal kinase (JNK). We examined the effect of Jnk1 gene deletion on in vivo responses to hyperoxia in mice. The survival of Jnk1-/- mice was reduced relative to wild-type mice after exposure to continuous hyperoxia. Jnk1-/- mice displayed higher protein concentration in bronchoalveolar lavage (BAL) fluid and increased expression of heme oxygenase-1, a stress-inducible gene, after 65 h of hyperoxia. Contrary to other markers of injury, the leukocyte count in BAL fluid of Jnk1-/- mice was markedly diminished relative to that of wild-type mice. The decrease in BAL leukocyte count was not associated with any decrease in lung myeloperoxidase activity at baseline or after hyperoxia treatment. Pretreatment with inhaled lipopolysaccharide increased BAL neutrophil content and extended hyperoxia survival time to a similar extent in Jnk1-/- and wild-type mice. Associated with increased mortality, Jnk1-/- mice had increased pulmonary epithelial cell apoptosis after exposure to hyperoxia compared with wild-type mice. These results indicate that JNK pathways participate in adaptive responses to hyperoxia in mice.