Rab26 alleviates sepsis-induced immunosuppression as a master regulator of macrophage ferroptosis and polarization shift.

Macrophage dysfunction is a significant contributor to more than 70 % of sepsis-related deaths, specifically secondary bacterial infections, during the immunosuppression stage of sepsis. Nevertheless, the role of Rab26 in this context remains unclear. In this study, we observed a substantial decrease in Rab26 expression in macrophages during the immunosuppressive phase of sepsis, which was also found to be suppressed by high extracellular levels of HMGB1. During the progression of sepsis, Rab26 deficiency promotes a polarization shift from the M1 to the M2-like phenotype in macrophages, rendering them susceptible to ferroptosis. Subsequent experimentation has revealed that Rab26 deficiency facilitates the degradation of GPX4, thereby aggravating macrophage ferroptosis through the upregulation of levels of lipid ROS, MDA, and ferrous iron induced by RSL3, a ferroptosis inducer. Additionally, Rab26-deficient mice in the immunosuppressed phase of sepsis exhibit heightened susceptibility to secondary infections, leading to exacerbated lung tissue damage and increased mortality rate. Overall, these findings indicate that Rab26 plays a crucial role in sepsis-induced macrophage immunosuppression by regulating macrophage ferroptosis and polarization. Hence, it represents a potential novel target for sepsis therapy.

Rab26 promotes macrophage phagocytosis through regulation of MFN2 trafficking to mitochondria.

Acute respiratory distress syndrome (ARDS) is an inflammatory disorder of the lungs caused by bacterial or viral infection. Timely phagocytosis and clearance of pathogens by macrophages are important in controlling inflammation and alleviating ARDS. However, the precise mechanism of macrophage phagocytosis remains to be explored. Here, we show that the expression of Rab26 is increased in Escherichia coli- or Pseudomonas aeruginosa-stimulated bone marrow-derived macrophages. Knocking out Rab26 reduced phagocytosis and bacterial clearance by macrophages. Rab26 interacts with mitochondrial fusion protein mitofusin-2 (MFN2) and affects mitochondrial reactive oxygen species generation by regulating MFN2 transport. The levels of MFN2 in mitochondria were reduced in Rab26-deficient bone marrow-derived macrophages, and the levels of mitochondrial reactive oxygen species and ATP were significantly decreased. Knocking down MFN2 using small interfering RNA resulted in decreased phagocytosis and killing ability of macrophages. Rab26 knockout reduced phagocytosis and bacterial clearance by macrophages in vivo, significantly increased inflammatory factors, aggravated lung tissue damage, and increased mortality in mice. Our results demonstrate that Rab26 regulates phagocytosis and clearance of bacteria by mediating the transport of MFN2 to mitochondria in macrophages, thus alleviating ARDS in mice and potentially in humans.

Chronic exposure to IQOS results in impaired pulmonary function and lung tissue damage in mice.

The use of IQOS brand heated tobacco products (HTPs) is increasing worldwide; however, little is known about the long-term effects of HTPs aerosol exposure on the lungs. Herein, we exposed C57BL/6 J mice for 24 weeks to clean air, IQOS aerosol, or cigarette smoke, and determined pulmonary function, lung tissue pathology, inflammation, and oxidative stress. Compared with the control group mice, IQOS group mice showed substantially decreased weight and lung function. Levels of IL-6 and TNF-a, as well as oxidative stress markers, were comparable to those found in the cigarette group. In addition, hematoxylin and eosin staining showed that the alveolar space was enlarged and that emphysema had formed in the IQOS group. Masson staining showed that collagen deposition areas were substantially increased in the airway walls in the IQOS group than in the control group. Immunohistochemical staining showed epithelial-mesenchymal transition in the airways of mice in the IQOS group. In conclusion, chronic exposure to IQOS aerosol results in impaired pulmonary function and lung tissue damage; hence, concern should be raised regarding the long-term safety of this product.

miR-137 represses migration and cell motility by targeting COX-2 in non-small cell lung cancer.

Background: Lung cancer is a common malignant tumor, with, non-small cell lung cancer (NSCLC) accounting for about 80-85% of cases. This study investigated the expression of miR-137 in NSCLC tissues and cells and its effects on the migration and invasion of NSCLC cells and related mechanisms. Methods: We collected the neoplastic and paracancerous tissues of NSCLC patients, detected the expression of miR-137 in NSCLC tissues and cell lines by real-time quantitative polymerase chain reaction (RT-qPCR), and analyzed the correlation between miR-137 expression and the clinicopathological features and survival of NSCLC. Following transfection with miR-137 mimic or inhibitor in NSCLC cell lines (A549 or H1299) to upregulate or downregulate the expression of miR-137, transwell assay was employed to detect the effects of miR-137 on migration or invasion. Online software was employed to predict and analyze the target gene of miR-137, and luciferase reporter gene system was adopted to validate it. The effects of miR-137 on the expressions of COX-2 and Epithelial-Mesenchymal Transition (EMT) related proteins were investigated by Western blot. Results: Compared to paracancerous tissues and BEAS-2B cells, the expressions of miR-137 in NSCLC tissues, A549 and H1299 cells were dramatically down-regulated (P<0.01). After transfection with miR-137 mimic or inhibitor in A549 and H1299 cells, the miR-137 expressions were markedly up-regulated or down-regulated (P<0.01), respectively. The number of migrating or invading cells was observably decreased or increased (P<0.01) after transfected with mimic or inhibitor, respectively, while relative luciferase activity was evidently decreased in cells co-transfected with miR-137 mimic and wild type recombined vector of 3'UTR of COX-2. While the expressions of COX-2 and E-cadherin were both substantially reduced in A549 cells treated with miR-137 mimic, that of vimentin was substantially raised. The expression of miR-137 correlated with smoking history, lymph node metastasis, and TNM clinical stage, and patients with high miR-137 expression had apparent longer survival. Conclusions: The expression of miR-137 was significantly down-regulated in NSCLC tissues and cells, and correlated with NSCLC progress. miR-137 suppressed the migration and invasion of NSCLC cells through regulating EMT relative proteins by targeting COX-2. miR-137 is expected to become a novel biomarker and therapeutic target of NSCLC.

AMPK α1 Downregulates ROS Levels Through Regulating Trx Leading to Dysfunction of Apoptosis in Non-Small Cell Lung Cancer.

PURPOSE: AMP-activated protein kinase α1 (AMPK α1) associates closely with cancers. However, the relationship between AMPK α1 and non-small cell lung cancer (NSCLC) is not fully understood. In this study, we aim to explore the role and mechanism of AMPK α1 in NSCLC initiation and progression. MATERIALS AND METHODS: A total of 165 clinical NSCLC specimens were included in the formalin-fixed and paraffin-embedded (FFPE) lung cancer tissue arrays. The expression levels of AMPK α1 and thioredoxin (Trx) in NSCLC cancer tissues and adjacent non-tumor lung tissues were measured through using immunohistochemistry. MTT assay was used to detect cell proliferation. Intracellular ROS levels were measured by using H2DCFDA reagent. Lentiviruses including LV-PRKAA1-RNAi, LV-PRKAA1 and a negative LV-control were used to infect A549 cells to modulate AMPK α1 expression in vitro. Immunoblotting was used to determine the modulation relationship between AMPK α1 and Trx. Log rank test and Kaplan-Meier survival analysis were performed to evaluate the significances of AMPK α1 and Trx expression levels on NSCLC patients' prognoses. RESULTS: AMPK α1 was highly expressed in NSCLC cancer tissues and correlated with poor prognosis in patients with NSCLC. In A549 cells, overexpression of AMPK α1 promoted proliferation, suppressed ROS levels and inhibited apoptosis. Moreover, inhibition of AMPK α1 expression achieved the opposite effects. Trx was significantly overexpressed in NSCLC cancer tissues; furthermore, Trx expressed much more in cytoplasm when compared with cell nucleus. Trx expression levels were positively correlated with AMPK α1 expression levels in NSCLC tissues. AMPK α1 could regulate Trx in A549 cells. No significant correlations were observed between Trx expression variances and prognoses in NSCLC patients. Combination of AMPK α1 and Trx had no advantage in predicting prognoses of NSCLC patients. CONCLUSION: These results suggest that AMPK α1 serves a carcinogenic role at least in part through the regulation of Trx expression, and thus represents a potential treatment target in patients with NSCLC.

The demographic and treatment options for patients with large cell neuroendocrine carcinoma of the lung.

INTRODUCTION: Lung large cell neuroendocrine carcinoma (L-LCNEC) is a rare, aggressive tumor, for which the optimal treatment strategies for LCNEC have not yet been established. In order to explore how to improve the outcome of prognosis for patients with LCNEC, this study investigated the effect of different treatments based on the data obtained from the Surveillance, Epidemiology, and End Results (SEER) database. METHODS: A total of 2594 LCNEC cases with conditional information were extracted from SEER database. Propensity Score Matching (PSM) method was conducted to reduce possible bias between groups. One-way ANOVA was used to test the differences of characteristics between groups. Univariate and multivariate Cox proportional hazard models were applied to identify prognostic factors. RESULTS: Clinicopathologic characteristics including gender, age, TNM stage, T stage, N stage, and M stage were all identified as independent prognostic factors. Surgery benefited stage I, II, and III LCNEC patients' prognoses. The combination treatment that surgery combining with chemotherapy was the optimal treatment for stage I, II, and III LCENC patients. Compared with palliative treatment, stage IV patients obtained better prognoses with the treatment of radiation, chemotherapy, or chemoradiation. When comparing the effect of the three treatments (radiation, chemotherapy, and chemoradiation) in achieving better prognosis for stage IV patients, chemotherapy alone was better than the other treatments. CONCLUSION: Surgery combining with chemotherapy was the optimal treatment for stage I, II, and III LCNEC patients; chemotherapy alone achieves more benefit than the other treatments for stage IV patients.