Bacterial pneumonia is a major cause of mechanical ventilation in intensive care units. We hypothesized that the presence of particular microbiota in endotracheal tube aspirates during the course of intubation was associated with clinical outcomes such as extubation failure or 28-day mortality. Sixty mechanically ventilated ICU (intensive care unit) patients (41 patients with pneumonia and 19 patients without pneumonia) were included, and tracheal aspirates were obtained on days 1, 3, and 7. Gene sequencing of 16S rRNA was used to measure the composition of the respiratory microbiome. A total of 216 endotracheal aspirates were obtained from 60 patients. A total of 22 patients were successfully extubatedwithin3 weeks, and 12 patients died within 28days. Microbiota profiles differed significantly between the pneumonia group and the non-pneumonia group (Adonis, p < 0.01). While α diversity (Shannon index) significantly decreased between day 1 and day 7 in the successful extubation group, it did not decrease in the failed extubation group among intubated patients with pneumonia. There was a significant difference in the change of βdiversity between the successful extubation group and the failed extubation group for Bray-Curtis distances (p < 0.001). At the genus level, Rothia, Streptococcus, and Prevotella correlated with the change of β diversity. A low relative abundance of Streptococci at the time of intubation was strongly associated with 28-day mortality. The dynamics of respiratory microbiome were associated with clinical outcomes such as extubation failure and mortality. Further large prospective studies are needed to test the predictive value of endotracheal aspirates in intubated patients.

While a higher incidence of lung cancer in subjects with previous tuberculous infection has been reported in epidemiologic data, the mechanism by which previous tuberculosis affects lung cancer remains unclear. We investigated the role of NOX4 in tuberculous pleurisy-assisted tumorigenicity both in vitro and in vivo.Heat-killed Mycobacterium tuberculosis-stimulated mesothelial cells augmented the migrationand invasive potential of lung cancer cells in a NOX4-dependent manner. Mice with Mycobacterium bovis bacillus Calmette–Guérin (BCG) pleural infection exhibited increased expression of NOX4 and enhanced malignant potential of lung cancer compared to mice with intrathoracic injection of phosphate-buffered saline. The BCG+ KLN205 (KLN205 cancer cell injection after BCG treatment) NOX4 KO mice group showed reduced tuberculous fibrosis-promoted metastatic potential of lung cancer, increased autophagy, and decreased expression of TGF-β, IL-6, and TNF-α compared to the BCG+KLN205 WT mice group. Finally, NOX4 silencing mitigated the malignant potential of A549 cells that was enhanced by tuberculous pleural effusion and restored autophagy signaling. Our results suggest that the NOX4–autophagy axis regulated by tuberculous fibrosis could result in enhanced tumorigenic potential and that NOX4-P62 might serve as a target for tuberculous fibrosis-induced lung cancer.

Extracellular matrix production by pleural mesothelial cells in response to Mycobacterium tuberculosis contributes to tuberculous fibrosis. NOX4 is involved in the pathogenesis of tuberculous fibrosis. In this study, we evaluated whether NOX4 gene-targeting microRNAs showed protective effects in tuberculosis fibrosis. TargetScan prediction software was used to identify candidate microRNAs that bind the 3′ UTRs of NOX4, and microRNA-148a (miR-148a) was selected as the best miRNA candidate. A repressed and forced expression assay in Met5A cells was performed to investigate the causal relationship between miR-148a and NOX4. The role of miR-148a in tuberculous pleural fibrosis was studied using a murine model of Mycobacterium bovis bacillus Calmette–Guérin (BCG) pleural infection. Heat-killed M. tuberculosis (HKMT) induces NOX4 and POLDIP2 expression. We demonstrated the inhibitory effect of miR-148a on NOX4 and POLDIP2 expression. The increased expression of miR-148a suppressed HKMT-induced collagen-1A synthesis in PMC cells. In the BCG pleurisy model, miR-148a significantly reduced fibrogenesis and epithelial mesenchymal transition. High levels of miR-148a in tuberculous pleural effusion can be interpreted as a self-limiting homeostatic response. Our data indicate that miR-148a may protect against tuberculous pleural fibrosis by regulating NOX4 and POLDIP2.

Extracellular vesicles (EVs) regulate various cellular and immunological functions in human diseases. There is growing interest in the clinical role of microbial EVs in pneumonia. However, there is a lack of research on the correlation between lung microbiome with microbial EVs and the microbiome of other body sites in pneumonia. We investigated the co-occurrence of lung microbiome and plasma microbe-derived EVs (mEVs) in 111 samples obtained from 60 mechanically ventilated patients (41 pneumonia and 19 non-pneumonia cases). The microbial correlation between the two samples was compared between the pneumonia and non-pneumonia cases. Bacterial composition of the plasma mEVs was distinct from that of the lung microbiome. There was a significantly higher correlation between lung microbiome and plasma mEVs in non-pneumonia individuals compared to pneumonia patients. In particular, Acinetobacter and Lactobacillus genera had high correlation coefficients in non-pneumonia patients. This indicates a beneficial effect of mEVs in modulating host lung immune response through EV component transfer.

Background: Healthcare-associated pneumonia (HCAP) is a heterogeneous disease. Previous studies reported that identifying risk factors for HCAP may lead to more accurate predictions of drug-resistant pathogens. We examined new nursing-home- and hospital-associated infections (NHAI) by revising existing HCAP risk factors. Our aim was to determine whether respiratory microbiota profiles are related to newly defined risk factors for NHAI in critically ill patients on mechanical ventilation.Methods: The NHAI group comprised nursing home residents with a poor functional status, or recent (past 90 days) hospitalization or recent (past 180 days) antibiotic therapy. Endotracheal aspirates were prospectively collected from patients in the intensive care unit (ICU) of a university hospital. The 180 endotracheal aspirates from 60 mechanically ventilated ICU patients (NHAI group, n = 24; non-NHAI group, n = 36) were obtained on days 1, 3 and 7. The bacterial community profiles of the endotracheal tube aspirates (ETAs) were explored by 16S rRNA gene sequencing. A phylogenetic-tree-based microbiome association test (TMAT), generalized linear mixed models (GLMMs), the Wilcoxon test and the reference frame method were used to analyze the association between microbiome abundance (number of operational taxonomic units [OTUs]) and disease phenotype.Results: The microbiome analysis revealed significantly lower α-diversity in the NHAI group than in the non-NHAI group. In the analysis of β-diversity, the structure of the microbiome also differed significantly between the two groups (weighted UniFrac distance, Adonis, P <0.001). The abundance of Corynebacterium was significantly higher, and the relative abundances of Granulicatella, Staphylococcus, Streptococcus and Veillonella were significantly lower, in the NHAI than in the non-NHAI group. Conclusions: The microbiota signature of the ETAs distinguished between patients with and without risk factors for NHAI. Thus, the lung microbiome may serve as a biomarker and therapeutic target for intubated patients exposed to nursing home and hospital environments.