CD8+ tissue-resident memory T cells are essential in bleomycin-induced pulmonary fibrosis.

Human tissue-resident memory T (TRM) cells play a crucial role in protecting the body from infections and cancers. Recent research observed increased numbers of TRM cells in the lung tissues of idiopathic pulmonary fibrosis patient. However, the functional consequences of TRM cells in pulmonary fibrosis remain unclear. Here, we found that the numbers of TRM cells, especially the CD8+ subset, were increased in the mouse lung with bleomycin-induced pulmonary fibrosis. Increasing or decreasing CD8+ TRM cells in mouse lungs accordingly altered the severity of fibrosis. In addition, adoptive transfer of CD8+ T cells containing a large number of CD8+ TRM cells from fibrotic lungs was sufficient to induce pulmonary fibrosis in control mice. Treatment with CCL18 to induced CD8+ TRM cell expansion and exacerbated fibrosis, while blocking CCR8 prevented CD8+ TRM recruitment and inhibited pulmonary fibrosis. In conclusion, CD8+ TRM cells are essential for bleomycin-induced pulmonary fibrosis, and targeting CCL18/CCR8/CD8+ TRM cells may be a potential therapeutic approach.

DEC1 is involved in circadian rhythm disruption-exacerbated pulmonary fibrosis.

BACKGROUND: The alveolar epithelial type II cell (AT2) and its senescence play a pivotal role in alveolar damage and pulmonary fibrosis. Cell circadian rhythm is strongly associated with cell senescence. Differentiated embryonic chondrocyte expressed gene 1 (DEC1) is a very important circadian clock gene. However, the role of DEC1 in AT2 senescence and pulmonary fibrosis was still unclear. RESULTS: In this study, a circadian disruption model of light intervention was used. It was found that circadian disruption exacerbated pulmonary fibrosis in mice. To understand the underlying mechanism, DEC1 levels were investigated. Results showed that DEC1 levels increased in lung tissues of IPF patients and in bleomycin-induced mouse fibrotic lungs. In vitro study revealed that bleomycin and TGF-ß1 increased the expressions of DEC1, collagen-I, and fibronectin in AT2 cells. Inhibition of DEC1 mitigated bleomycin-induced fibrotic changes in vitro and in vivo. After that, cell senescence was observed in bleomycin-treated AT2 cells and mouse models, but these were prevented by DEC1 inhibition. At last, p21 was confirmed having circadian rhythm followed DEC1 in normal conditions. But bleomycin disrupted the circadian rhythm and increased DEC1 which promoted p21 expression, increased p21 mediated AT2 senescence and pulmonary fibrosis. CONCLUSIONS: Taken together, circadian clock protein DEC1 mediated pulmonary fibrosis via p21 and cell senescence in alveolar epithelial type II cells.

BMAL1/p53 mediating bronchial epithelial cell autophagy contributes to PM2.5-aggravated asthma.

BACKGROUND: Fine particulate matter (PM2.5) is associated with increased incidence and severity of asthma. PM2.5 exposure disrupts airway epithelial cells, which elicits and sustains PM2.5-induced airway inflammation and remodeling. However, the mechanisms underlying development and exacerbation of PM2.5-induced asthma were still poorly understood. The aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) is a major circadian clock transcriptional activator that is also extensively expressed in peripheral tissues and plays a crucial role in organ and tissue metabolism. RESULTS: In this study, we found PM2.5 aggravated airway remodeling in mouse chronic asthma, and exacerbated asthma manifestation in mouse acute asthma. Next, low BMAL1 expression was found to be crucial for airway remodeling in PM2.5-challenged asthmatic mice. Subsequently, we confirmed that BMAL1 could bind and promote ubiquitination of p53, which can regulate p53 degradation and block its increase under normal conditions. However, PM2.5-induced BMAL1 inhibition resulted in up-regulation of p53 protein in bronchial epithelial cells, then increased-p53 promoted autophagy. Autophagy in bronchial epithelial cells mediated collagen-I synthesis as well as airway remodeling in asthma. CONCLUSIONS: Taken together, our results suggest that BMAL1/p53-mediated bronchial epithelial cell autophagy contributes to PM2.5-aggravated asthma. This study highlights the functional importance of BMAL1-dependent p53 regulation during asthma, and provides a novel mechanistic insight into the therapeutic mechanisms of BMAL1. Video Abstract.

Lutein inhibits tumor progression through the ATR/Chk1/p53 signaling pathway in non-small cell lung cancer.

Lung cancer is the leading cause of cancer-related death. In particular, non-small cell lung cancer (NSCLC) accounts for approximately 85% of all lung cancer cases. Due to tumor resistance and the toxicity of chemotherapeutic agents, it is increasingly critical to discover novel, potent antitumorigenic drugs for treating NSCLC. Lutein, a carotenoid, has been reported to exert toxic effects on cells in several tumor types. However, the detailed functions and underlying mechanisms of lutein in NSCLC remain elusive. The present study showed that lutein significantly and dose-dependently inhibited cell proliferation, arrested the cell cycle at the G0/G1 phase, and induced apoptosis in NSCLC cells. RNA-sequencing analysis revealed that the p53 signaling pathway was the most significantly upregulated in lutein-treated A549 cells. Mechanistically, lutein exerted antitumorigenic effects by inducing DNA damage and subsequently activating the ATR/Chk1/p53 signaling pathway in A549 cells. In vivo, lutein impeded tumor growth in mice and prolonged their survival. In conclusion, our findings demonstrate the antitumorigenic potential of lutein and reveal its molecular mechanism of action, suggesting that lutein is a promising candidate for clinical NSCLC treatment.

Pleural mesothelial cell migration into lung parenchyma by calpain contributes to idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is defined as a specific form of chronic, progressive fibrosing interstitial pneumonia. It is unknown why fibrosis in IPF distributes in the peripheral or named sub-pleural area. Migration of pleural mesothelial cells (PMC) should contribute to sub-pleural fibrosis. Calpain is known to be involved in cell migration, but the role of calpain in PMC migration has not been investigated. In this study, we found that PMCs migrated into lung parenchyma in patients with IPF. Then using Wt1tm1(EGFP/Cre)Wtp /J knock-in mice, we observed PMC migration into lung parenchyma in bleomycin-induced pleural fibrosis models, and calpain inhibitor attenuated pulmonary fibrosis with prevention of PMC migration. In vitro studies revealed that bleomycin and transforming growth factor-ß1 increased calpain activity in PMCs, and activated calpain-mediated focal adhesion (FA) turnover as well as cell migration, cell proliferation, and collagen-I synthesis. Furthermore, we determined that calpain cleaved FA kinase in both C-terminal and N-terminal regions, which mediated FA turnover. Lastly, the data revealed that activated calpain was also involved in phosphorylation of cofilin-1, and p-cofilin-1 induced PMC migration. Taken together, this study provides evidence that calpain mediates PMC migration into lung parenchyma to promote sub-pleural fibrosis in IPF.

VEGF/Src signaling mediated pleural barrier damage and increased permeability contributes to subpleural pulmonary fibrosis.

The distribution of fibrosis in idiopathic pulmonary fibrosis (IPF) is subpleural with basal predominance. Alveolar epithelial cell was considered as the key cell in the initial phase of IPF. However, the idea of activation and damage of alveolar epithelial cells is very difficult to explain why fibrosis distributes in the subpleural area. In this study, human pleural mesothelial cell (PMC) line and primary rat PMC was used as in vitro model. Intraperitoneal injection of bleomycin was used for making a pulmonary fibrosis model. The integrity of cultured monolayer PMCs was determined by transepithelial electric resistance (TEER). Pleural permeability was estimated by measuring paracellular transport of fluorescein isothiocyanate (FITC)-conjugated dextran. Changes in lung tissue of patients with IPF were analyzed by Masson's and immunofluorescence staining. We found bleomycin induced PMCs damage and increased PMCs permeability; increased PMCs permeability aggravated bleomycin-induced subpleural inflammation and pulmonary fibrosis. Moreover, bleomycin was found to activate VEGF/Src signaling which increased PMCs permeability. In vivo, inhibition of VEGF/Src signaling prevented bleomycin-induced subpleural pulmonary fibrosis. At last, activation of VEGF/Src signaling was confirmed in subpleural area in patients with IPF. Taken together, our findings indicate that VEGF/Src signaling mediated pleural barrier damage and increased permeability which contributes to subpleural pulmonary fibrosis.

Bleomycin induced apical-basal polarity loss in alveolar epithelial cell contributes to experimental pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrosing interstitial lung disease with limited therapeutic options and a median survival of 3 years after diagnosis. Dysregulated epithelial regeneration is key event involved in initiating and sustaining IPF. The type II alveolar epithelial cells (AECIIs) play a crucial role for epithelial regeneration and stabilisation of alveoli. Loss of cell apical-basal polarity contributes to fibrosis. AECII has apical-basal polarity, but it is poorly understood whether AECII apical-basal polarity loss is involved in fibrosis. Bleomycin is a traditional inducer of pulmonary fibrosis. Here firstly we observed that bleomycin induced apical-basal polarity loss in cultured AECIIs. Next, cell polarity proteins lethal (2) giant larvae 1 (Lgl1), PAR-3A, aPKC and PAR-6B were investigated. We found bleomycin induced increases of Lgl1 protein and decreases of PAR-3A protein, and bleomycin-induced PAR-3A depression was mediated by increased-Lgl1. Then Lgl1 siRNA was transfected into AECIIs. Lgl1 siRNA prevented apical-basal polarity loss in bleomycin-treated AECIIs. At last, Lgl1-conditional knockout mice were applied in making animal models. Bleomycin induced pulmonary fibrosis, but this was attenuated in Lgl1-conditional knockout mice. Together, these data indicated that bleomycin mediated AECII apical-basal polarity loss which contributed to experimental pulmonary fibrosis. Inhibition of Lgl1 should be a potential therapeutic strategy for the disease.

Early Use of Corticosteroid May Prolong SARS-CoV-2 Shedding in Non-Intensive Care Unit Patients with COVID-19 Pneumonia: A Multicenter, Single-Blind, Randomized Control Trial.

BACKGROUND: There is still no clinical evidence available to support or to oppose corticosteroid treatment for coronavirus disease 2019 (COVID-19) pneumonia. OBJECTIVE: To investigate the efficacy and safety of corticosteroid given to the hospitalized patients with COVID-19 pneumonia. METHODS: This was a prospective, multicenter, single-blind, randomized control trial. Adult patients with COVID-19 pneumonia who were admitted to the general ward were randomly assigned to either receive methylprednisolone or not for 7 days. The primary end point was the incidence of clinical deterioration 14 days after randomization. RESULTS: We terminated this trial early because the number of patients with COVID-19 pneumonia in all the centers decreased in late March. Finally, a total of 86 COVID-19 patients underwent randomization. There was no difference of the incidence of clinical deterioration between the methylprednisolone group and control group (4.8 vs. 4.8%, p = 1.000). The duration of throat viral RNA detectability in the methylprednisolone group was 11 days (interquartile range, 6-16 days), which was significantly longer than that in the control group (8 days [2-12 days], p = 0.030). There were no significant differences between the 2 groups in other secondary outcomes. Mass cytometry discovered CD3+ T cells, CD8+ T cells, and NK cells in the methylprednisolone group which were significantly lower than those in the control group after randomization (p < 0.05). CONCLUSIONS: From this prematurely closed trial, we found that the short-term early use of corticosteroid could suppress the immune cells, which may prolong severe acute respiratory syndrome coronavirus 2 shedding in patients with COVID-19 pneumonia. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04273321.

Lethal (2) giant larvae regulates pleural mesothelial cell polarity in pleural fibrosis.

Pleural fibrosis is barely reversible and the underlying mechanisms are poorly understood. Pleural mesothelial cells (PMCs) which have apical-basal polarity play a key role in pleural fibrosis. Loss of cell polarity is involved in the development of fibrotic diseases. Partition defective protein (PAR) complex is a key regulator of cell polarity. However, changes of PMC polarity and PAR complex in pleural fibrosis are still unknown. In this study, we observed that PMC polarity was lost in fibrotic pleura. Next we found increased Lethal (2) giant larvae (Lgl) bound with aPKC and PAR-6B competing against PAR-3A in PAR complex, which led to cell polarity loss. Then we demonstrated that Lgl1 siRNA prevented cell polarity loss in PMCs, and Lgl1 conditional knockout (ER-Cre+/-Lgl1flox/flox) attenuated pleural fibrosis in a mouse model. Our data indicated that Lgl1 regulates cell polarity of PMCs, inhibition of Lgl1 and maintenance of cell polarity in PMCs could be a potential therapeutic treatment approach for pleural fibrosis.

IL-4-induced caveolin-1-containing lipid rafts aggregation contributes to MUC5AC synthesis in bronchial epithelial cells.

BACKGROUND: Mucus overproduction is an important feature of asthma. Interleukin (IL)-4 is required for allergen-induced airway inflammation and mucus production. MUC5AC gene expression is regulated by transcript factors NF-κB. The intracellular Ca2+ ([Ca2+]i) signal is required for activation of NF-κB. The transient receptor potential canonical 1 (TRPC1) channel has been shown to contribute for agonist-stimulated Ca2+ influx in some types of cells. However, the relationships among IL-4, TRPC1 and mucus overproduction in bronchial epithelial cells (BECs) in asthma are poorly understood. METHODS: BECs were isolated from large bronchial airway of rats and used as cell model. To present changes of lipid raft, caveolin-1 and TRPC1, immunofluorescence staining and sucrose gradient centrifugation were performed. [Ca2+]i was measured after loading with Fura-2. NF-κB activities were measured by an ELISA-based assay. MUC5AC mRNA and protein levels were detected by real-time quantitative RT-PCR, ELISA analysis and immunofluorescence staining respectively. RESULTS: IL-4 induced Ca2+ influx in BECs, and this was blocked by a Ca2+ influx inhibitor (2-APB). 2-APB also prevented MUC5AC protein synthesis induced by IL-4. Depletion of extracellular Ca2+ resulted in partial decrease in expression of MUC5AC in IL-4 treated cells. NF-κB rather than STAT6 activation mediated IL-4-induced MUC5AC protein synthesis. Then the mechanism of Ca2+ influx was investigated. Immunofluorescence staining and sucrose gradient centrifugation revealed that caveolin-1-containing lipid rafts aggregation was involved in TRPC1 activation and Ca2+ influx in BECs. Lastly, the data revealed that blocking lipid rafts aggregation exactly prevented Ca2+ influx, NF-κB activation and MUC5AC synthesis induced by IL-4. CONCLUSIONS: Our results indicate that IL-4-induced caveolin-1-containing lipid rafts aggregation at least partly contributes to MUC5AC synthesis in BECs.

Causal association between peripheral immune cells and IgA nephropathy: a Mendelian randomization study.

Background: The relationship between peripheral immune cells and immunoglobulin A nephropathy (IgAN) is widely known; however, causal evidence of this link is lacking. Here, we aimed to determine the causal effect of peripheral immune cells, specifically total white blood cells, lymphocytes, monocytes, basophils, eosinophils, and neutrophils, as well as lymphocyte subset traits, on the IgAN risk using a Mendelian randomization (MR) analysis. Methods: The inverse-variance weighted (IVW) method was used for the primary analysis. We applied three complementary methods, including the weighted median, MR-Egger regression, and MR-PRESSO, to detect and correct for the effect of horizontal pleiotropy. Additionally, we performed a multivariable MR (MVMR) analysis, adjusting for the effects of C-reactive protein (CRP) levels. The roles of specific lymphocyte subtypes and their significance have garnered interest. Bidirectional two-sample MR analysis was performed to test the potential causal relationships between immune traits, including median fluorescence intensities (MFIs) and the relative cell count (AC), and IgAN. Results: The IVW-MR analysis suggested a potential causal relationship between lymphocyte counts and IgAN in Europe (OR per 1-SD increase: 1.43, 95% CI: 1.08-1.88, P = 0.0123). The risk effect of lymphocytes remained even after adjusting for CRP levels using the MVMR method (OR per 1-SD increase: 1.44, 95% CI: 1.05-1.96, P = 0.0210). The other sensitivity analyses showed a consistent trend. The largest GWAS published to date was used for peripheral blood immunophenotyping to explore the potential causal relationship between peripheral immune cell subsets and IgAN. Six AC-IgAN and 14 MFI-IgAN pairs that reached statistical significance (P < 0.05) were detected. Notably, CD3, expressed in eight subsets of T cells, consistently showed a positive correlation with IgAN. The bidirectional MR analysis did not reveal any evidence of reverse causality. According to the sensitivity analysis, horizontal pleiotropy was unlikely to distort the causal estimates. Conclusions: Genetically determined high lymphocyte counts were associated with IgAN, supporting that high lymphocyte counts is causal risk factor for IgAN.

PM2.5 exposure-induced senescence-associated secretory phenotype in airway smooth muscle cells contributes to airway remodeling.

Fine particulate matter (PM2.5) has been linked to increased severity and incidence of airway diseases, especially chronic obstructive pulmonary disease (COPD) and asthma. Airway remodeling is an important event in both COPD and asthma, and airway smooth muscle cells (ASMCs) are key cells which directly involved in airway remodeling. However, it was unclear how PM2.5 affected ASMCs. This study investigates the effects of PM2.5 on airway smooth muscle and its mechanism. We first showed that inhaled particulate matter was distributed in the airway smooth muscle bundle, combined with increased airway smooth muscle bundle and collagen deposition in vivo. Then, we demonstrated that PM2.5 induced up-regulation of collagen-I and alpha-smooth muscle actin (α-SMA) expression in rat and human ASMCs in vitro. Next, we found PM2.5 led to rat and human ASMCs senescence and exhibited senescence-associated secretory phenotype (SASP) by autophagy-induced GATA4/TRAF6/NF-κB signaling, which contributed to collagen-I and α-SMA synthesis as well as airway smooth muscle remodeling. Together, our results provided evidence that SASP induced by PM2.5 in airway smooth muscle cells prompted airway remodeling.

A New Predictive Model for the Prognosis of MDA5+ DM-ILD.

Purpose: The purpose of this study is to analyze clinical information and combine significant parameters to generate a predictive model and achieve a better prognosis prediction of dermatomyositis-associated interstitial lung disease with positive melanoma differentiation-associated gene 5 antibody (MDA5+ DM-ILD) and stratify patients according to prognostic risk factors appropriately. Methods: We retrospectively reviewed 63 patients MDA5+ DM-ILD who were treated in our hospital from January 2018 to January 2021. Our study incorporated most clinical characteristics in clinical practice to explore the associations and predictive functions of clinical characteristics and prognosis. Student's t-test, Mann-Whitney U-test, chi-squared test, Pearson correlation analysis, Cox regression analysis, R, receiver operating characteristic curves (ROC curves), and Kaplan-Meier survival curves were performed to identify independent predictors for the prognosis of MDA5+DM-ILD. Results: In all the 63 patients with MDA5+DM-ILD, 44 improved but 19 did not. Poor prognosis was found more frequently in patients who were older, clinically amyopathic variant of dermatomyositis (CADM), and/or with short duration, short interval of DM and ILD, long length of stay, fever, dyspnea, non-arthralgia, pulmonary infection, pleural effusion (PE), high total computed tomography scores (TCTs), ground-glass opacity (GGO), consolidation score, reticular score and fibrosis score, decreased forced vital capacity (FVC), forced expiratory volume in 1s (FEV1), albumin, A/G, glomerular filtration rate (GFR) and tumor necrosis factor α (TNFα), high titer of anti-MDA5, proteinuria, high levels of monocyte, lactate dehydrogenase (LDH), ferritin (FER), neuron specific enolase (NSE) and glucocorticoid, antibiotic, antiviral, and non-invasive positive pressure ventilation (NPPV). The multivariate Cox regression analysis demonstrated that duration, fever, PE, TCTs and aspartate transaminase (AST) were independent predictors of poor prognosis in patients with MDA5+DM-ILD. The nomogram model quantified the risk of 400-day death as: duration ≤ 4 months (5 points), fever (88 points), PE (21 points), TCTs ≥10 points (22 points), and AST ≥200 U/L (100 points) with high predictive accuracy and convenience. The ROC curves possessed good discriminative ability for combination of fever, PE, TCTs, and AST, as reflected by the area under curve (AUC) being.954, 95% CI 0.902-1.000, and sensitivity and specificity being 84.2 and 94.6%, respectively. Conclusion: We demonstrated that duration, fever, PE, TCTs, and AST could be integrated together to be independent predictors of poor prognosis in MDA5+ DM-ILD with highly predictive accuracy.

Prolonged SARS-CoV-2 Viral Shedding in Patients with COVID-19 was Associated with Delayed Initiation of Arbidol Treatment and Consulting Doctor Later: A Retrospective Cohort Study.

OBJECTIVE: To study data about SARS-CoV-2 virus shedding and clarify the risk factors for prolonged virus shedding. METHODS: Data were retrospectively collected from adults hospitalized with laboratory-confirmed coronavirus disease-19 (COVID-19) in Wuhan Union Hospital. We compared clinical features among patients with prolonged (a positive SARS-CoV-2 RNA on day 23 after illness onset) and short virus shedding and evaluated risk factors associated with prolonged virus shedding by multivariate regression analysis. RESULTS: Among 238 patients, the median age was 55.5 years, 57.1% were female, 92.9% (221/238) were administered with arbidol, 58.4% (139/238) were given arbidol in combination with interferon. The median duration of SARS-CoV-2 virus shedding was 23 days (IQR, 17.8-30 days) with a longest one of 51 days. The patients with prolonged virus shedding had higher value of D-dimer (P=0.002), IL-6 (P<0.001), CRP (P=0.005) and more lobes lung lesion (P=0.014) on admission, as well as older age (P=0.017) and more patients with hypertension (P=0.044) than in those the virus shedding less than 23 days. Multivariate regression analysis revealed that prolonged viral shedding was significantly associated with initiation arbidol >8 days after symptom onset [OR: 2.447, 95% CI (1.351-4.431)], ≥3 days from onset of symptoms to first medical visitation [OR: 1.880, 95% CI (1.035-3.416)], illness onset before Jan. 31, 2020 [OR: 3.289, 95% CI (1.474-7.337)]. Arbidol in combination with interferon was also significantly associated with shorter virus shedding [OR: 0.363, 95% CI (0.191-0.690)]. CONCLUSION: Duration of SARS-CoV-2 virus shedding was long. Early initiation of arbidol and arbidol in combination with interferon as well as consulting doctor timely after illness onset were helpful for SARS-CoV-2 clearance.

Corticosteroids Treatment of Patients with Coronavirus Disease 2019: A Propensity Score Matching Study.

The role of corticosteroids in the treatment of Coronavirus disease 2019 (COVID-19) is controversial. In the present study, we evaluated the effects of adjuvant corticosteroids treatment on the outcome of patients with COVID-19 (n=966), using Propensity Score Matching to adjust for potential differences between the corticosteroids group (n=289) and the non-corticosteroids group (n=677). Analysis of data without adjusting differences in baseline characteristics indicated that the proportion of mechanical ventilation and the mortality was higher in the corticosteroids treatment group in total or severe/critical patients. The duration of viral shedding was longer in the non-corticosteroids treatment group in total or general/mild patients. After adjusting the difference between the corticosteroids and non-corticosteroids treatment group, the analysis revealed that the use of corticosteroids had no effect on the duration of viral shedding, in-hospital mortality or 28-day mortality.

Co-infection of SARS-COV-2 and Influenza A Virus: A Case Series and Fast Review.

Coronavirus disease 2019 (COVID-19) occurs in the influenza season and has become a global pandemic. The present study aimed to examine severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) co-infection with influenza A virus (IAV) in an attempt to provide clues for the antiviral interventions of co-infected patients. We described two patients who were co-infected with SARS-CoV-2 and IAV treated at Wuhan Union Hospital, China. In addition, we performed a review in PubMed, Web of Science and CNKI (from January 1 up to November 1, 2020) with combinations of the following key words: "COVID-19, SARS-COV-2, influenza A and co-infection". A total of 28 co-infected patients were enrolled in the analysis. Of the 28 patients, the median age was 54.5 years (IQR, 34.25-67.5) and 14 cases (50.0%) were classified as severe types. The most common symptoms were fever (85.71%), cough (82.14%) and dyspnea (60.71%). Sixteen patients had lymphocytopenia on admission and 23 patients exhibited abnormal radiological changes. The median time from symptom onset to hospital admission was 4 days (IQR, 3-6), and the median time of hospital stay was 14 days (IQR, 8.5-16.75). In conclusion, patients with SARS-COV-2 and IAV co-infection were similar to those infected with SARS-COV-2 alone in symptoms and radiological images. SARS-COV-2 co-infection with IAV could lead to more severe clinical condition but did not experience longer hospital stay compared with patients infected with SARS-COV-2 alone.

Splicing factor SRSF6 mediates pleural fibrosis.

Pleural fibrosis is defined as an excessive deposition of extracellular matrix that results in destruction of the normal pleural tissue architecture and compromised function. Tuberculous pleurisy, asbestos injury, and rheumatoid pleurisy are main causes of pleural fibrosis. Pleural mesothelial cells (PMCs) play a key role in pleural fibrosis. However, detailed mechanisms are poorly understood. Serine/arginine-rich protein SRSF6 belongs to a family of highly conserved RNA-binding splicing-factor proteins. Based on its known functions, SRSF6 should be expected to play a role in fibrotic diseases. However, the role of SRSF6 in pleural fibrosis remains unknown. In this study, SRSF6 protein was found to be increased in cells of tuberculous pleural effusions (TBPE) from patients, and decellularized TBPE, bleomycin, and TGF-ß1 were confirmed to increase SRSF6 levels in PMCs. In vitro, SRSF6 mediated PMC proliferation and synthesis of the main fibrotic protein COL1A2. In vivo, SRSF6 inhibition prevented mouse experimental pleural fibrosis. Finally, activated SMAD2/3, increased SOX4, and depressed miRNA-506-3p were associated with SRSF6 upregulation in PMCs. These observations support a model in which SRSF6 induces pleural fibrosis through a cluster pathway, including SRSF6/WNT5A and SRSF6/SMAD1/5/9 signaling. In conclusion, we propose inhibition of the splicing factor SRSF6 as a strategy for treatment of pleural fibrosis.

Crosstalk between pleural mesothelial cell and lung fibroblast contributes to pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a specific form of chronic, progressive and fibrosing interstitial pneumonia of unknown cause. The main feature of IPF is a heterogeneous appearance with areas of sub-pleural fibrosis. However, the mechanism of sub-pleural fibrosis was poorly understood. In this study, our in vivo study revealed that pleural mesothelial cells (PMCs) migrated into lung parenchyma and localized alongside lung fibroblasts in sub-pleural area in mouse pulmonary fibrosis. Our in vitro study displayed that cultured-PMCs-medium induced lung fibroblasts transforming into myofibroblast, cultured-fibroblasts-medium promoted mesothelial-mesenchymal transition of PMCs. Furthermore, these changes in lung fibroblasts and PMCs were prevented by blocking TGF-ß1/Smad2/3 signaling with SB431542. TGF-ß1 neutralized antibody attenuated bleomycin-induced pulmonary fibrosis. Similar to TGF-ß1/Smad2/3 signaling, wnt/ß-catenin signaling was also activated in the process of PMCs crosstalk with lung fibroblasts. Moreover, inhibition of CD147 attenuated cultured-PMCs-medium induced collagen-I synthesis in lung fibroblasts. Blocking CD147 signaling also prevented bleomycin-induced pulmonary fibrosis. Our data indicated that crosstalk between PMC and lung fibroblast contributed to sub-pleural pulmonary fibrosis. TGF-ß1, Wnt/ß-catenin and CD147 signaling was involved in the underling mechanism.

miR-4739 mediates pleural fibrosis by targeting bone morphogenetic protein 7.

BACKGROUND: Pleural fibrosis is defined as excessive depositions of matrix components that result in pleural tissue architecture destruction and dysfunction. In severe cases, the progression of pleural fibrosis leads to lung entrapment, resulting in dyspnea and respiratory failure. However, the mechanism of pleural fibrosis is poorly understood. METHODS: miR-4739 levels were detected by miRNA array and real-time PCR. Real-time PCR, western blotting and immunofluorescence were used to identify the expression profile of indicators related to fibrosis. Target gene of miR-4739 and promoter activity assay was measured by using dual-luciferase reporter assay system. In vivo, pleural fibrosis was evaluated by Masson staining and miR-4739 level was detected by In situ hybridization histochemistry. FINDINGS: We found that bleomycin induced up-regulation of miR-4739 in pleural mesothelial cells (PMCs). Over-regulated miR-4739 mediated mesothelial-mesenchymal transition and increased collagen-I synthesis in PMCs. Investigation on the clinical specimens revealed that high levels of miR-4739 and low levels of bone morphogenetic protein 7 (BMP-7) associated with pleural fibrosis in patients. Then we next identified that miR-4739 targeted and down-regulated BMP-7 which further resulted in unbalance between Smad1/5/9 and Smad2/3 signaling. Lastly, in vivo studies revealed that miR-4739 over-expression induced pleural fibrosis, and exogenous BMP-7 prevented pleural fibrosis in mice. INTERPRETATION: Our data indicated that miR-4739 targets BMP-7 which mediates pleural fibrosis. The miR-4739/BMP-7 axis is a promising therapeutic target for the disease. FUND: The National Natural Science Foundation of China.

Cigarette smoking aggravates bleomycin-induced experimental pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease that typically leads to respiratory failure and death. The cause of IPF is poorly understood. Although several environmental and occupational factors are considered as risk factors in IPF, cigarette smoking seems to be the most strongly associated risk factor. Here firstly, we treated mice with cigarette (16 mg tar, 1.0 mg nicotine in each cigarette) smoking and tried to explore the role of cigarette smoking in pulmonary fibrosis. Mice were continuously subjected to smoke for about 1 h each day (12 cigarettes per day, 5 days per week) during 40 days. Bleomycin was administrated by intraperitoneal injection at a dose of 40 mg/kg on days 1, 5, 8, 11 and 15. We found bleomycin induced pulmonary fibrosis in mice, and cigarette smoking augmented bleomycin-induced fibrosis reflected by both in fibrotic area and percentages of collagen in the lungs. Then we prepared and employed cigarette smoke extract (CSE) in cell models and found that CSE could induce the activation of p-Smad2/3 and p-Akt, as well as collagen-I synthesis and cell proliferation in lung fibroblasts and pleural mesothelial cells (PMCs). TGF-ß1 signaling mediated CSE-induced PMCs migration. Moreover, in vitro studies revealed that CSE had superimposed effect on bleomycin-induced activation of TGF-ß-Smad2/3 and -Akt signaling. TGF-ß-Smad2/3 and -Akt signaling were further augmented by cigarette smoking in the lung of bleomycin-treated mice. Taken together, these findings represent the first evidence that cigarette smoking aggravated bleomycin-induced pulmonary fibrosis via TGF-ß1 signaling.