Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) is characterized by uncontrolled progressive lung inflammation. Macrophages serve a key role in the pathogenesis of ALI/ARDS. Macrophage pyroptosis is a process of cell death releasing the proinflammatory cytokines interleukin (IL)‑1β and IL‑18. It was hypothesized that macrophage pyroptosis may partially account for the uncontrolled lung inflammation of ALI/ARDS. In the present study, greater macrophage pyroptosis in lipopolysaccharide (LPS)‑treated macrophages and the ALI/ARDS mouse model was observed. The expression of nucleotide‑binding domain, leucine‑rich‑containing family, pyrin domain‑containing (NLRP)3 and IL‑1β and cleavage of caspase‑1 were significantly elevated following LPS treatment accompanied by greater activation of p38 mitogen‑activated protein kinase (MAPK) signaling in vitro and in vivo. However, blocking p38 MAPK signaling through the inhibitor SB203580 significantly suppressed the acute lung injury and excessive lung inflammation in vivo, consistent with the reduced expression of the NLRP3 inflammasome and IL‑1β and cleavage of caspase‑1. Pretreatment of the rat NR8383 macrophage cell line with SB203580 significantly decreased the population of caspase‑1+PI+ pyroptotic cells and expression of NLRP3/IL‑1β. However, a larger population of Annexin V+PI‑ apoptotic cells was observed following blocking of the p38 MAPK signaling pathway. The results indicated that blockage of p38 MAPK signaling pathway skewed macrophage cell death from proinflammatory pyroptosis towards non‑inflammatory apoptosis. These effects may contribute to attenuated acute lung injury and excessive inflammation in the SB203580‑treated mice. The results may provide a novel therapeutic strategy for the treatment of uncontrolled lung inflammation in patients with ALI/ARDS.

Melatonin is a well-known anti-inflammatory and antioxidant molecule, which plays a crucial role in various physiological functions. In this study, mice received a single dose of 15 Gy radiation delivered to the lungs and daily intraperitoneal administration of melatonin. After 7 days, mice were processed to harvest either bronchoalveolar lavage fluid for cytokine assays or lungs for flow cytometry and histopathological studies. Herein, we showed that melatonin markedly alleviated the oxidative stress and injury, especially suppressing the infiltration of macrophages (CD11b+CD11c−) and neutrophils (CD11b+Ly6G+) to the irradiated lungs. Moreover, in the irradiated RAW 264.7 cells, melatonin blocked the NLRP3 inflammasome activation accompanied with the inhibition of the IL-1β release and caspase-1 activity. However, melatonin restored the downregulated miR-30e levels. Quantitative PCR analysis of miR-30e and NLRP3 indicated the negative correlation between them. Notably, immunofluorescence staining showed that overexpression of miR-30e dramatically diminished the increased NLRP3 expression. Luciferase reporter assay confirmed that NLRP3 was a target gene of miR-30e. Western blotting revealed that transfection with miR-30e mimics markedly reduced the expressions of NLRP3 and cleaved caspase-1, whereas this phenomenon was reversed by the miR-30e inhibitor. Consistent with this, the beneficial effect of melatonin under irradiated exposure was blunted in cells transfected with anti-miR-30e. Collectively, our results demonstrate that the NLRP3 inflammasome contributed to the pathogenesis of radiation-induced lung injury. Meanwhile, melatonin exerted its protective effect through negatively regulating the NLRP3 inflammasome in macrophages. The melatonin-mediated miR-30e/NLRP3 signaling may provide novel therapeutic targets for radiation-induced injury.

A bulk of evidence identified that macrophages, including resident alveolar macrophages and recruited macrophages from the blood, played an important role in the pathogenesis of acute respiratory distress syndrome (ARDS). However, the molecular mechanisms of macrophages-induced acute lung injury (ALI) by facilitating oxidative stress and inflammatory responses remain unclear. Herein, we noticed that the levels of mitochondrial reactive oxygen species (mtROS), SPHK2 and activated NLRP3 inflammasome were higher in peripheral blood mononuclear cells (PBMCs) of ARDS patients than that in healthy volunteers. Similar observations were recapitulated in LPS-treated RAW264.7 and THP-1 cells. After exposure to LPS, the SPHK2 enzymatic activity, NLRP3 inflammasome activation and mtROS were significantly upregulated in macrophages. Moreover, knockdown SPHK2 via shRNA or inhibition SPHK2 could prominently decrease LPS-induced M1 macrophage polarization, oxidative stress and NLRP3 inflammasome activation. Further study indicated that upregulated SPHK2 could increase nuclear sphingosine-1-phosphate (S1P) levels and then restrict the enzyme activity of HDACs to facilitate p53 acetylation. Acetylation of p53 reinforced its binding to the specific region of the NLRP3 promoter and drove expression of NLRP3. In the in vivo experiments, it was also observed that treating with Opaganib (ABC294640), a specific SPHK2 inhibitor, could observably alleviate LPS-induced ALI, evidencing by lowered infiltration of inflammatory cells, increased M2 macrophages polarization and reduced oxidative damage in lung tissues. Besides, SPHK2 inhibition can also decrease the accumulation of acetylated p53 protein and the activation of NLRP3 inflammasome. Taken together, our results demonstrated for the first time that nuclear S1P can regulate the acetylation levels of non-histone protein through affecting HDACs enzyme activities, linking them to oxidative stress and inflammation in response to environmental signals. These data provide a theoretical basis that SPHK2 may be an effective therapeutic target of ARDS.

Background. Severe community-acquired pneumonia (SCAP) requiring intensive care unit (ICU) treatment commonly causes acute respiratory distress syndrome (ARDS) with high mortality. This study was aimed at evaluating whether microRNAs (miRNAs) in circulating exosomes have the predictive values for patients at risk of developing ARDS due to SCAP. Methods. ARDS/ALI-relevant miRNAs were obtained by literature search. Exosomes in serum were isolated by ultracentrifugation method and identified by Transmission Electron Microscopy. Then the miR profiling in the exosomes using real-time PCR was analyzed in SCAP patients with or without ARDS. Moreover, multivariate Cox proportional regression analysis was performed to estimate the odds ratio of miRNA for the occurrence of ARDS and prognosis. The receiver operating characteristics (ROC) curves were calculated to discriminate ARDS cases. Finally, the Kaplan-Meier curve using log-rank method was performed to test the equality for survival distributions with different miRNA classifiers. Results. A total of 53 SCAP patients were finally recruited. Ten miRNAs were picked out. Further, a subset of exosomal miRNAs, including the miR-146a, miR-27a, miR-126, and miR-155 in ARDS group exhibited significantly elevated levels than those in non-ARDS group. The combined expression of miR-126, miR-27a, miR-146a, and miR-155 predicted ARDS with an area under the curve of 0.909 (95 % CI 0.815 –1). Only miR-126 was selected to have potential to predict the 28-day mortality (OR=1.002, P=0.024) with its median value classifier. Conclusions. The altered levels of circulating exosomal microRNAs may be useful biologic confirmation of ARDS in patients with SCAP.

Objective: To describe and evaluate the impact of diseases control and prevention on epidemics dynamics and clinical features of SARS-CoV-2 outbreak in Shanghai. Design: A retrospective descriptive study Setting: China Participants: Epidemiology information was collected from publicly accessible database. 265 patients admitted to Shanghai Public Health Center with confirmed COVID-19 were enrolled for clinical features analysis. Main outcome measure: Prevention and control measures taken by Shanghai government, epidemiological, demographic, clinical, laboratory and radiology data were collected. Weibull distribution, Chi-square test, Fisher’s exact test, t test or Mann-Whitney U test were used in statistical analysis. Results: COVID-19 transmission rate within Shanghai had reduced over 99% than previous speculated, and the exponential growth has been stopped so far. Epidemic was characterized by the first stage mainly composed of imported cases and the second stage where >50% of cases were local. The incubation period was 6.4 (95% CI 5.3 to 7.6) days and the mean onset-admission interval was 5.5 days (95% CI, 5.1 to 5.9). Median time for COVID-19 progressed to severe diseases were 8.5 days (IQR: 4.8-11.0 days). By February 11 ^th , proportion of patients being mild, moderate, severe and critically ill were 1.9%(5/265), 89.8%(238/265), 3.8%(10/265), 4.5%(12/265), respectively; 47 people in our cohort were discharged, and 1 patient died. Conclusion: Strict controlling of the transmission rate at the early stage of an epidemic in metropolis can quickly prohibit the spread of the diseases. Controlling local clusters is the key to prevent outbreaks from imported cases. Most COVID-19 severe cases progressed within 14 days of disease onset. Multiple systemic laboratory abnormalities had been observed before significant respiratory dysfunction.