RESUMO
Respiratory tract infections represent a significant global public health concern, disproportionately affecting vulnerable populations such as children, the elderly, and immunocompromised individuals. RNA viruses, particularly influenza viruses and coronaviruses, significantly contribute to respiratory illnesses, especially in immunosuppressed and elderly individuals. Influenza A viruses (IAVs) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to pose global health threats due to their capacity to cause annual epidemics, with profound implications for public health. In addition, the increase in global life expectancy is influencing the dynamics and outcomes of respiratory viral infections. Understanding the molecular mechanisms by which IAVs and SARS-CoV-2 contribute to lung disease progression is therefore crucial. The aim of this review was to comprehensively explore the impact of IAVs and SARS-CoV-2 on chronic lung diseases, with a specific focus on pulmonary fibrosis in the elderly. It also outlines potential preventive and therapeutic strategies and suggests directions for future research.
RESUMO
Influenza A virus (IAV) infection while primarily affects the lungs, it is often associated with cardiovascular complications. However, the mechanisms underlying this association are not fully understood. Here, we investigated the potential role of FBXL19, a member of the Skp1-Cullin-F-box family of E3 ubiquitin ligase, in IAV-induced cardiac inflammation. We demonstrated that FBXL19 overexpression in endothelial cells (ECs) reduced viral titers and IAV matrix protein 1 (M1) levels, while increasing antiviral genes expression, including interferon (IFN)-α, ß, γ and RANTES in the cardiac tissue of IAV-infected mice. Moreover, EC-specific overexpression of FBXL19 attenuated the IAV infection-reduced interferon regulatory factor 3 (IRF3) level without altering its mRNA level, and suppressed cardiac inflammation. Furthermore, IAV infection triggered cellular senescence programs in the heart as indicated by the upregulation of p16 and p21 mRNA levels, and the downregulation of lamin B1 levels, which were partially reversed by FBXL19 overexpression in ECs. Our findings indicate that EC-specific overexpression of FBXL19 protects against IAV-induced cardiac damage by enhancing interferon-mediated antiviral signaling, reducing cardiac inflammation, and suppressing cellular senescence programs.
RESUMO
The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has led to a global health emergency. There are many similarities between SARS-CoV-2 and influenza A virus (IAV); both are single-stranded RNA viruses infecting airway epithelial cells and have similar modes of replication and transmission. Like IAVs, SARS-CoV-2 infections poses serious challenges due to the lack of effective therapeutic interventions, frequent appearances of new strains of the virus, and development of drug resistance. New approaches to control these infectious agents may stem from cellular factors or pathways that directly or indirectly interact with viral proteins to enhance or inhibit virus replication. One of the emerging concepts is that host cellular factors and pathways are required for maintaining viral genome integrity, which is essential for viral replication. Although IAVs have been studied for several years and many cellular proteins involved in their replication and pathogenesis have been identified, very little is known about how SARS-CoV-2 hijacks host cellular proteins to promote their replication. IAV induces apoptotic cell death, mediated by the B-cell lymphoma-2 (Bcl-2) family proteins in infected epithelia, and the pro-apoptotic members of this family promotes viral replication by activating host cell proteases. This review compares the life cycle and mode of replication of IAV and SARS-CoV-2 and examines the potential roles of host cellular proteins, belonging to the Bcl-2 family, in SARS-CoV-2 replication to provide future research directions.
Assuntos
COVID-19 , Vírus da Influenza A , Humanos , SARS-CoV-2 , Peptídeo Hidrolases , Pandemias , Replicação Viral , Proteínas Proto-Oncogênicas c-bcl-2RESUMO
Idiopathic pulmonary fibrosis (IPF) is an irreversible and fatal lung disease that is primarily found in the elderly population, and several studies have demonstrated that aging is the major risk factor for IPF. IPF is characterized by the presence of apoptosis-resistant, senescent fibroblasts that generate an excessively stiff extracellular matrix (ECM). The ECM profoundly affects cellular functions and tissue homeostasis, and an aberrant ECM is closely associated with the development of lung fibrosis. Aging progressively alters ECM components and is associated with the accumulation of senescent cells that promote age-related tissue dysfunction through the expression of factors linked to a senescence-associated secretary phenotype (SASP). There is growing evidence that SASP factors affect various cell behaviors and influence ECM turnover in lung tissue through autocrine and/or paracrine signaling mechanisms. Since life expectancy is increasing worldwide, it is important to elucidate how aging affects ECM dynamics and turnover via SASP and thereby promotes lung fibrosis. In this review, we will focus on the molecular properties of SASP and its regulatory mechanisms. Furthermore, the pathophysiological process of ECM remodeling by SASP factors and the influence of an altered ECM from aged lungs on the development of lung fibrosis will be highlighted. Finally, recent attempts to target ECM alteration and senescent cells to modulate fibrosis will be introduced.NEW & NOTEWORTHY Aging is the most prominent nonmodifiable risk factor for various human diseases including Idiopathic pulmonary fibrosis. Aging progressively alters extracellular matrix components and is associated with the accumulation of senescent cells that promote age-related tissue dysfunction. In this review, we will discuss the pathological impact of aging and senescence on lung fibrosis via senescence-associated secretary phenotype factors and potential therapeutic approaches to limit the progression of lung fibrosis.
Assuntos
Matriz Extracelular , Fibrose Pulmonar Idiopática , Pulmão , Fenótipo Secretor Associado à Senescência , Fibrose Pulmonar Idiopática/metabolismo , Fibrose Pulmonar Idiopática/patologia , Matriz Extracelular/patologia , Pulmão/patologia , Humanos , Animais , Proteínas da Matriz Extracelular/metabolismoRESUMO
Caspases and poly (ADP-ribose) polymerase 1 (PARP1) have been shown to promote influenza A virus (IAV) replication. However, the relative importance and molecular mechanisms of specific caspases and their downstream substrate PARP1 in regulating viral replication in airway epithelial cells (AECs) remains incompletely elucidated. Here, we targeted caspase 2, 3, 6, and PARP1 using specific inhibitors to compare their role in promoting IAV replication. Inhibition of each of these proteins caused significant decline in viral titer, although PARP1 inhibitor led to the most robust reduction of viral replication. We previously showed that the pro-apoptotic protein Bcl-2 interacting killer (Bik) promotes IAV replication in the AECs by activating caspase 3. In this study, we found that as compared with AECs from wild-type mice, bik-deficiency alone resulted in ~ 3 logs reduction in virus titer in the absence of treatment with the pan-caspase inhibitor (Q-VD-Oph). Inhibiting overall caspase activity using Q-VD-Oph caused additional decline in viral titer by ~ 1 log in bik-/- AECs. Similarly, mice treated with Q-VD-Oph were protected from IAV-induced lung inflammation and lethality. Inhibiting caspase activity diminished nucleo-cytoplasmic transport of viral nucleoprotein (NP) and cleavage of viral hemagglutinin and NP in human AECs. These findings suggest that caspases and PARP1 play major roles to independently promote IAV replication and that additional mechanism(s) independent of caspases and PARP1 may be involved in Bik-mediated IAV replication. Further, peptides or inhibitors that target and block multiple caspases or PARP1 may be effective treatment targets for influenza infection.
Assuntos
Vírus da Influenza A , Influenza Humana , Animais , Camundongos , Humanos , Vírus da Influenza A/fisiologia , Caspases/metabolismo , Células Epiteliais , Proteínas Reguladoras de Apoptose , Nucleoproteínas/metabolismo , Replicação Viral/fisiologia , Proteínas MitocondriaisRESUMO
Extensive inflammation causes epithelial cell hyperplasia in the airways and Bcl-2-interacting killer (Bik) reduces epithelial cell and mucous cell hyperplasia without affecting resting cells to restore homeostasis. These observations suggest that Bik induces apoptosis in a cell cycle-specific manner, but the mechanisms are not understood. Mice were exposed to an allergen for 3, 14, or 30 days and Bik expression was induced in airway epithelia of transgenic mice. Bik reduced epithelial and mucous cell hyperplasia when mice were exposed to an allergen for 3 or 14 days, but not when exposure lasted for 30 days, and Ki67-positivity was reduced. In culture, Bik expression killed proliferating cells but not quiescent cells. To capture the stage of the cell cycle when Bik induces cell death, airway cells that express fluorescent ubiquitin cell cycle indicators were generated that fluoresce red or green during the G0/G1 and S/G2/M phases of the cells cycle, respectively. Regardless of the cell cycle stage, Bik expression eliminated green-fluorescent cells. Also, Bik, when tagged with a blue-fluorescent protein, was only detected in green cells. Bik phosphorylation mutants at threonine 33 or serine 35 demonstrated that phosphorylation activated Bik to induce death even in quiescent cells. Immunoprecipitation and proteomic approaches identified casein kinase IIα to be responsible for phosphorylating and activating Bik to kill cells in S/G2/M. As casein kinase 2 alpha (CKIIα) is expressed only during the G2/M phase, we conclude that Bik activation in airway epithelial cells selectively targets hyperplastic epithelial cells, while leaving resting airway cells unaffected.
Assuntos
Caseína Quinase II , Proteômica , Alérgenos , Animais , Apoptose , Proteínas Reguladoras de Apoptose/metabolismo , Divisão Celular , Hiperplasia , Camundongos , Proteínas Mitocondriais/metabolismoRESUMO
Respiratory syncytial virus (RSV) is associated with enhanced progression of chronic obstructive pulmonary disease (COPD) and COPD exacerbations. However, little is known about the role of IL-17 in RSV-induced lung injury. We first investigated the role of RSV infection in enhancing mucous cell hyperplasia (MCH) and airspace enlargement in the lungs of mice injured with elastase and LPS (E/LPS). Mice injured with E/LPS had an enhanced and prolonged neutrophilic response to RSV that was associated with decreased levels of type I IFN and increased levels of IL-17, IL-23, CXCL-1, granulocyte colony stimulating factor (GCSF), CXCL-5, and matrix metalloproteinase (MMP)-9. In addition, extent of MCH and mean weighted alveolar space were increased significantly in the lungs of E/LPS-injured mice infected with RSV compared with E/LPS-only or RSV-only controls. Interestingly, immunodepletion of IL-17 before viral infection diminished the RSV-driven MCH and airspace enlargement in the E/LPS-injured animals, suggesting that IL-17 may be a therapeutic target for MCH and airspace enlargement when enhanced by RSV infection.
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Interleucina-17/metabolismo , Pneumonia Viral/fisiopatologia , Enfisema Pulmonar/virologia , Infecções por Vírus Respiratório Sincicial/fisiopatologia , Animais , Citocinas/genética , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Regulação da Expressão Gênica , Hiperplasia/metabolismo , Hiperplasia/patologia , Interleucina-17/genética , Lipopolissacarídeos/toxicidade , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Pulmão/patologia , Camundongos Endogâmicos C57BL , Elastase Pancreática/toxicidade , Pneumonia Viral/metabolismo , Doença Pulmonar Obstrutiva Crônica/metabolismo , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Enfisema Pulmonar/metabolismo , Enfisema Pulmonar/fisiopatologia , Infecções por Vírus Respiratório Sincicial/metabolismoRESUMO
OBJECTIVE: House dust mite (HDM) exposure is used to model experimental asthma in mice. However, a direct comparison of inflammatory responses following continuous versus intermittent HDM exposure has not been reported. Therefore, we investigated whether the HDM dose at sensitization or challenge affects extent of inflammation in mice that were either continuously or intermittently sensitized with HDM. MATERIALS AND METHODS: C57BL/6 mice received either 10 continuous exposures with 10 µg HDM per exposure or two intermittent HDM exposures over a period of two weeks and were subsequently challenged by three instillations with HDM during the third week. For the intermittent model, mice were sensitized with 1 or 10 µg HDM and challenged on three consecutive days with 1 or 10 µg HDM. Inflammatory cells in the bronchoalveolar lavage fluid and epithelial cell hyperplasia and mucous cell metaplasia were quantified. RESULTS: Significantly higher levels of inflammation and mucous cell metaplasia were observed when mice were sensitized intermittently compared with continuously. Intermittent sensitization and challenge with 10 µg HDM caused maximum inflammation, mucous cell metaplasia, and epithelial cell hyperplasia. However, sensitization with 1 µg HDM only also showed increased inflammation when challenged with 10 µg HDM. DISCUSSION: These findings suggest major differences in adaptive immunity, depending on the sensitization protocol. CONCLUSIONS: Because of significant differences, the HDM sensitization protocol should be carefully considered when designing studies to investigate the underlying mechanisms of immunity in mouse models of asthma.
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Alérgenos/administração & dosagem , Hipersensibilidade/imunologia , Inflamação/imunologia , Pyroglyphidae/imunologia , Imunidade Adaptativa , Alérgenos/imunologia , Animais , Líquido da Lavagem Broncoalveolar/imunologia , Células Epiteliais/patologia , Hiperplasia/patologia , Hipersensibilidade/patologia , Inflamação/patologia , Pulmão/imunologia , Masculino , Camundongos Endogâmicos C57BLRESUMO
Influenza virus induces apoptosis in infected cells to promote viral replication by manipulating the host cell death signaling pathway. Although some Bcl-2 family proteins play a role in the replication of influenza A virus (IAV), the role of cell death pathways in the viral replication cycle is unclear. We investigated whether deficiency of the proapoptotic Bcl-2 family protein, Bik, plays a role in IAV replication. IAV replication was attenuated in mouse airway epithelial cells (MAECs) from bik(-/-) compared with bik(+/+) mice, as indicated by reduced viral titers. Bik(-/-) MAECs showed more stable transepithelial resistance after infection than did bik(+/+) MAECs, were less sensitive to infection-induced cell death, and released fewer copies of viral RNA. Similar results were obtained when Bik expression was suppressed in human airway epithelial cells (HAECs). Bik(+/+) mice lost weight drastically and died within 8 days of infection, whereas 75% of bik(-/-) mice survived infection for 14 days and were 10-fold less likely to die from infection compared with bik(+/+) mice. IAV infection activated caspase 3 in bik(+/+) but not in bik(-/-) MAECs. Cleavage of viral nucleoprotein and M2 proteins were inhibited in bik(-/-) MAECs and when caspase activation was inhibited in HAECs. Furthermore, Bik deficiency impaired cytoplasmic export of viral ribonucleoprotein. These studies suggest a link between Bik-mediated caspase activation and cleavage of viral proteins. Thus, inhibition of proapoptotic host factors such as Bik and downstream mediators of cell death may represent a novel approach to influenza treatment.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Caspase 3/metabolismo , Vírus da Influenza A/fisiologia , Influenza Humana/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Mitocondriais/metabolismo , Infecções por Orthomyxoviridae/metabolismo , Proteínas Virais/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/deficiência , Células Epiteliais Alveolares/metabolismo , Células Epiteliais Alveolares/patologia , Células Epiteliais Alveolares/virologia , Animais , Morte Celular , Embrião de Galinha , Citoplasma/metabolismo , Cães , Ativação Enzimática , Humanos , Influenza Humana/virologia , Células Madin Darby de Rim Canino , Camundongos Endogâmicos C57BL , Proteínas Mitocondriais/deficiência , Infecções por Orthomyxoviridae/virologia , Ribonucleoproteínas/metabolismo , Replicação ViralRESUMO
BACKGROUND: Airway epithelial cells (AECs) are crucial for mucosal and adaptive immunity but whether these cells respond in a memory-dependent manner is poorly studied. Previously, we have reported that LPS intratracheal instillation in rodents causes extensive neutrophilic inflammation and airway epithelial cell hyperplasia accompanied by mucous cell metaplasia (MCM). And the resolution process required a period of 40 d for the inflammation to subside and the lung epithelia to resemble the non-exposed condition. Therefore, the present study investigated the memory-dependent response of airway epithelial cells to a secondary LPS challenge after the initial inflammation was resolved. METHODS: Airway epithelial and mucous cells were assessed in response to a secondary LPS challenge in F344/N rats, and in C57BL/6 wild-type (Foxn1WT) and T cell-deficient athymic (Foxn1nu) mice that were instilled with LPS or saline 40 d earlier. Epithelial expression of TLR4, EGFR, and phosphorylated-ERK1/2 (pERK) were also analyzed. RESULTS: LPS-pretreated F344/N rats responded with elevated numbers of AECs after saline challenge and with 3-4-fold increased MCM following the LPS challenge in LPS- compared with saline-pretreated rats. LPS-pretreated rats showed 5-fold higher number of AECs expressing TLR4 apically than saline-pretreated rats. Also, the expression of EGFR was increased in LPS-pretreated rats along with the number of AECs with active or nuclear pERK, and the levels were further increased upon LPS challenge. LPS-pretreated Foxn1nu compared with Foxn1WT mice showed increased MCM and elevated levels of TLR4, EGFR, and nuclear pERK at 40 d after LPS instillation. LPS challenge further augmented MCM rapidly in Foxn1nu compared with Foxn1WT mice. CONCLUSION: Together, these data suggest that AECs preserve an 'innate memory' that drives a rapid mucous phenotype via spatiotemporal regulation of TLR4 and EGFR. Further, T cells may suppress the sustained elevated expression of TLR4 and EGFR and thereby the hyperactive epithelial response.
Assuntos
Células Epiteliais/imunologia , Imunidade nas Mucosas , Memória Imunológica , Pneumonia/imunologia , Mucosa Respiratória/imunologia , Linfócitos T/imunologia , Animais , Modelos Animais de Doenças , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Receptores ErbB/imunologia , Receptores ErbB/metabolismo , Fatores de Transcrição Forkhead/deficiência , Fatores de Transcrição Forkhead/genética , Lipopolissacarídeos , Masculino , Metaplasia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Nus , Proteína Quinase 1 Ativada por Mitógeno/imunologia , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/imunologia , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Fosforilação , Pneumonia/induzido quimicamente , Pneumonia/metabolismo , Pneumonia/patologia , Ratos Endogâmicos F344 , Mucosa Respiratória/metabolismo , Mucosa Respiratória/patologia , Transdução de Sinais , Linfócitos T/metabolismo , Linfócitos T/patologia , Fatores de Tempo , Receptor 4 Toll-Like/imunologia , Receptor 4 Toll-Like/metabolismoRESUMO
BACKGROUND: The length of time for cigarette smoke (CS) exposure to cause emphysema in mice is drastically reduced when CS exposure is combined with viral infection. However, the extent of inflammatory responses and lung pathologies of mice exposed to CS and infected with influenza A virus (IAV), respiratory syncytial virus (RSV), or treated with the viral derivative dsRNA (polyinosine-polycytidylic acid [poly (I:C)] have not been compared. METHODS: Mice were exposed to CS or filtered air for 4 weeks and received a single dose of vehicle, AV, or RSV infection and extent of inflammation and emphysema was evaluated 14 d later. In another set of experiments, mice were instilled with poly (I:C) twice a week during the third and fourth weeks of CS exposure and immediately analyzed for extent of inflammation and lung pathologies. RESULTS: In CS-exposed mice, inflammation was characterized mainly by macrophages, lymphocytes, and neutrophils after IAV infection, mainly by lymphocytes, and neutrophils after RSV infection, and mainly by lymphocytes and neutrophils after poly (I:C) instillations. Despite increased inflammation, extent of emphysema by poly (I:C) was very mild; but was robust and similar for both IAV and RSV infections with enhanced MMP-12 mRNA expression and TUNEL positivity. Both IAV and RSV infections increased the levels of IL-17, IL-1ß, IL-12b, IL-18, IL-23a, Ccl-2, Ccl-7 mRNAs in the lungs of CS-exposed mice with IAV causing more increases than RSV. CONCLUSION: CS-induced inflammatory responses and extent of emphysematous changes differ depending on the type of viral infection. These animal models may be useful to study the mechanisms by which different viruses exacerbate CS-induced inflammation and emphysema.
Assuntos
Fumar Cigarros/efeitos adversos , Vírus da Influenza A/patogenicidade , Infecções por Orthomyxoviridae/virologia , Pneumonia Viral/virologia , Poli I-C , Enfisema Pulmonar/virologia , Infecções por Vírus Respiratório Sincicial/virologia , Vírus Sinciciais Respiratórios/patogenicidade , Fumaça/efeitos adversos , Animais , Quimiotaxia de Leucócito , Citocinas/genética , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Interações Hospedeiro-Patógeno , Mediadores da Inflamação/metabolismo , Pulmão/imunologia , Pulmão/metabolismo , Pulmão/patologia , Pulmão/virologia , Linfócitos/imunologia , Linfócitos/virologia , Macrófagos/imunologia , Macrófagos/virologia , Metaloproteinase 12 da Matriz/genética , Metaloproteinase 12 da Matriz/metabolismo , Camundongos Endogâmicos C57BL , Infiltração de Neutrófilos , Neutrófilos/imunologia , Neutrófilos/virologia , Infecções por Orthomyxoviridae/imunologia , Infecções por Orthomyxoviridae/metabolismo , Infecções por Orthomyxoviridae/patologia , Pneumonia Viral/imunologia , Pneumonia Viral/metabolismo , Pneumonia Viral/patologia , Enfisema Pulmonar/imunologia , Enfisema Pulmonar/metabolismo , Enfisema Pulmonar/patologia , Infecções por Vírus Respiratório Sincicial/imunologia , Infecções por Vírus Respiratório Sincicial/metabolismo , Infecções por Vírus Respiratório Sincicial/patologia , Vírus Sinciciais Respiratórios/imunologia , Fatores de TempoAssuntos
Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Células Epiteliais/fisiologia , Interleucina-13/fisiologia , Proteínas Mitocondriais/fisiologia , Proteínas Proto-Oncogênicas c-bcl-2/fisiologia , Alérgenos/imunologia , Compostos de Anilina/farmacologia , Compostos de Anilina/uso terapêutico , Animais , Proteínas Reguladoras de Apoptose , Asma/tratamento farmacológico , Asma/imunologia , Células Cultivadas , Células Epiteliais/patologia , Humanos , Hiperplasia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mucina-5AC/fisiologia , Ovalbumina/imunologia , Sulfonamidas/farmacologia , Sulfonamidas/uso terapêutico , Traqueia/citologiaRESUMO
Although chronic low-grade inflammation does not cause immediate clinical symptoms, over the longer term, it can enhance other insults or age-dependent damage to organ systems and thereby contribute to age-related disorders, such as respiratory disorders, heart disease, metabolic disorders, autoimmunity, and cancer. However, the molecular mechanisms governing low-level inflammation are largely unknown. We discovered that Bcl-2-interacting killer (Bik) deficiency causes low-level inflammation even at baseline and the development of spontaneous emphysema in female but not male mice. Similarly, a single nucleotide polymorphism that reduced Bik levels was associated with increased inflammation and enhanced decline in lung function in humans. Transgenic expression of Bik in the airways of Bik-deficient mice inhibited allergen- or LPS-induced lung inflammation and reversed emphysema in female mice. Bik deficiency increased nuclear but not cytosolic p65 levels because Bik, by modifying the BH4 domain of Bcl-2, interacted with regulatory particle non-ATPase 1 (RPN1) and RPN2 and enhanced proteasomal degradation of nuclear proteins. Bik deficiency increased inflammation primarily in females because Bcl-2 and Bik levels were reduced in lung tissues and airway cells of female compared with male mice. Therefore, controlling low-grade inflammation by modifying the unappreciated role of Bik and Bcl-2 in facilitating proteasomal degradation of nuclear proteins may be crucial in treating chronic age-related diseases.
Assuntos
Enfisema , Hexosiltransferases , Masculino , Animais , Feminino , Humanos , Camundongos , Apoptose , Proteínas Mitocondriais , Proteínas Reguladoras de Apoptose , Proteínas Proto-Oncogênicas c-bcl-2 , Inflamação/genética , Proteínas Nucleares , Complexo de Endopeptidases do Proteassoma/genéticaRESUMO
RATIONALE: Aberrant regulation of airway epithelial cell numbers in airways leads to increased mucous secretions in chronic lung diseases such as chronic bronchitis. Because the Bcl-2 family of proteins is crucial for airway epithelial homeostasis, identifying the players that reduce cigarette smoke (CS)-induced mucous cell metaplasia can help to develop effective therapies. OBJECTIVES: To identify the Bcl-2 family of proteins that play a role in reducing CS-induced mucous cell metaplasia. METHODS: We screened for dysregulated expression of the Bcl-2 family members. MEASUREMENTS AND MAIN RESULTS: We identified Bik to be significantly reduced in bronchial brushings of patients with chronic epithelial cell hyperplasia compared with nondiseased control subjects. Reduced Bik but increased MUC5AC mRNA levels were also detected when normal human airway epithelial cells (HAECs) were exposed to CS or when autopsy tissues from former smokers with and without chronic bronchitis were compared. Similarly, exposure of C57Bl/6 mice to CS resulted in increased numbers of epithelial and mucous cells per millimeter of basal lamina, along with reduced Bik but increased Muc5ac expression, and this change was sustained even when mice were allowed to recover in filtered air for 8 weeks. Restoring Bik expression significantly suppressed CS-induced mucous cell metaplasia in differentiated primary HAEC cultures and in airways of mice in vivo. Bik blocked nuclear translocation of phospho-ERK1/2 to induce apoptosis of HAECs. The conserved Leu61 within Bik and ERK1/2 activation were essential to induce cell death in hyperplastic mucous cells. CONCLUSIONS: These studies show that CS suppresses Bik expression to block airway epithelia cell death and thereby increases epithelial cell hyperplasia in chronic bronchitis.
Assuntos
Células Epiteliais/patologia , Genes bcl-2/genética , Mucosa/patologia , Fumar/genética , Fumar/patologia , Animais , Western Blotting , Modelos Animais de Doenças , Eletroforese em Gel de Poliacrilamida , Feminino , Humanos , Hiperplasia , Pulmão/patologia , Masculino , Metaplasia , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Muco , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Hyperplastic airway epithelial cells may be the cause for increased risk for lung cancer in patients with chronic lung diseases. The B-cell lymphoma 2 (Bcl-2) family member, Bcl-2-interacting killer (BIK), triggers cell death specifically in these hyperplastic cells because of adequate presence of Death-associated Protein Kinase 1 (DAPk1), BCL-2 Antagonist Killer (BAK), and Extracellular Signal-regulated Kinase 1/2 (ERK1/2). Therefore, BIK may be a useful tool to control the development of lung cancer in patients with chronic diseases.
RESUMO
Bik reduces hyperplastic epithelial cells by releasing calcium from endoplasmic reticulum stores and causing apoptosis, but the detailed mechanisms are not known. Here we report that Bik dissociates the Bak/Bcl-2 complex to enrich for ER-associated Bak and interacts with the kinase domain of DAPk1 to form Bik-DAPk1-ERK1/2-Bak complex. Bik also disrupts the Bcl2-IP3R interaction to cause ER Ca2+ release. The ER-associated Bak interacts with the kinase and calmodulin domains of DAPk1 to increase the contact sites of ER and mitochondria, and facilitate ER Ca2+ uptake by mitochondria. Although the Bik BH3 helix was sufficient to enrich for ER-Bak and elicit ER Ca2+ release, Bik-induced mitochondrial Ca2+ uptake is blocked with reduced Bak levels. Further, the Bik-derived peptide reduces allergen- and cigarette smoke-induced mucous cell hyperplasia in mice and in differentiated primary human airway epithelial cultures. Therefore, Bik peptides may have therapeutic potential in airway diseases associated with chronic mucous hypersecretion.Bcl-2 interacting killer (Bik) decreases airway epithelial hyperplasia via apoptosis mediated by calcium release from the endoplasmic reticulum (ER), but the mechanism is unclear. Here the authors show that Bik promotes Bak enrichment at the ER to tether mitochondria for efficient calcium transfer.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Cálcio/metabolismo , Proteínas Quinases Associadas com Morte Celular/metabolismo , Retículo Endoplasmático/metabolismo , Células Epiteliais/metabolismo , Hiperplasia/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Proteína Killer-Antagonista Homóloga a bcl-2/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Alérgenos/farmacologia , Animais , Apoptose , Proteínas Reguladoras de Apoptose/farmacologia , Células Cultivadas , Humanos , Camundongos , Camundongos Knockout , Proteínas Mitocondriais/metabolismo , Peptídeos/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Mucosa Respiratória/citologia , Mucosa Respiratória/efeitos dos fármacos , Mucosa Respiratória/metabolismo , Fumaça , Produtos do TabacoRESUMO
IFNgamma induces cell death in epithelial cells, but the mediator for this death pathway has not been identified. In this study, we find that expression of Bik/Blk/Nbk is increased in human airway epithelial cells (AECs [HAECs]) in response to IFNgamma. Expression of Bik but not mutant BikL61G induces and loss of Bik suppresses IFNgamma-induced cell death in HAECs. IFNgamma treatment and Bik expression increase cathepsin B and D messenger RNA levels and reduce levels of phospho-extracellular regulated kinase 1/2 (ERK1/2) in the nuclei of bik(+/+) compared with bik(-/-) murine AECs. Bik but not BikL61G interacts with and suppresses nuclear translocation of phospho-ERK1/2, and suppression of ERK1/2 activation inhibits IFNgamma- and Bik-induced cell death. Furthermore, after prolonged exposure to allergen, hyperplastic epithelial cells persist longer, and nuclear phospho-ERK is more prevalent in airways of IFNgamma(-/-) or bik(-/-) compared with wild-type mice. These results demonstrate that IFNgamma requires Bik to suppress nuclear localization of phospho-ERK1/2 to channel cell death in AECs.