Throat microbiota drives alterations in pulmonary alveolar microbiota in patients with septic ARDS.

OBJECTIVES: The translocation of intestinal flora has been linked to the colonization of diverse and heavy lower respiratory flora in patients with septic ARDS, and is considered a critical prognostic factor for patients. METHODS: On the first and third days of ICU admission, BALF, throat swab, and anal swab were collected, resulting in a total of 288 samples. These samples were analyzed using 16S rRNA analysis and the traceability analysis of new generation technology. RESULTS: On the first day, among the top five microbiota species in abundance, four species were found to be identical in BALF and throat samples. Similarly, on the third day, three microbiota species were found to be identical in abundance in both BALF and throat samples. On the first day, 85.16% of microorganisms originated from the throat, 5.79% from the intestines, and 9.05% were unknown. On the third day, 83.52% of microorganisms came from the throat, 4.67% from the intestines, and 11.81% were unknown. Additionally, when regrouping the 46 patients, the results revealed a significant predominance of throat microorganisms in BALF on both the first and third day. Furthermore, as the disease progressed, the proportion of intestinal flora in BALF increased in patients with enterogenic ARDS. CONCLUSIONS: In patients with septic ARDS, the main source of lung microbiota is primarily from the throat. Furthermore, the dynamic trend of the microbiota on the first and third day is essentially consistent.It is important to note that the origin of the intestinal flora does not exclude the possibility of its origin from the throat.

Melatonin Exerts Cardioprotective Effects by Inhibiting NLRP3 Inflammasome-Induced Pyroptosis in Mice following Myocardial Infarction.

Myocardial infarction- (MI-) induced myocardial damage is mainly attributed to the loss of cardiomyocytes. Pyroptosis is a newly recognized form of programmed cell necrosis that is associated with the progression of MI. Melatonin has been shown to exert cardioprotective effects against cardiac damage in multiple cardiovascular diseases. However, the effect of melatonin on pyroptosis-induced cardiac injury in MI has not been elucidated. Herein, we found that melatonin administration ameliorated cardiac dysfunction and reduced cardiomyocyte death both in mice following coronary artery ligation and in H9C2 cells exposed to hypoxia. The results also showed that pyroptosis was induced both in vivo and in vitro, as evidenced by increased NLRP3, cleaved caspase-1, GSDMD-N, and mature IL-1ß and IL-18 levels, and these changes were decreased by melatonin treatment. Furthermore, we observed that TLR4 and NF-κB levels were increased by MI or hypoxia, and these increases were reversed by melatonin. The antipyroptotic action of melatonin was abrogated by treatment with an agonist of the TLR4/NF-κB signaling pathway. Our results indicate that melatonin can exert cardioprotective effects by inhibiting NLRP3 inflammasome-induced pyroptosis through modulation of the TLR4/NF-κB signaling pathway and provide strong evidence for the utility of melatonin in the treatment of MI.

Knockdown CD44 promote the inflammatory response through the autophagy pathway in mouse models of pulmonary contusion.

BACKGROUND: The effects of CD44, via the anti-inflammatory functions of autophagy, on lung injuries following pulmonary contusion (PC) and cell apoptosis were investigated. METHODS: Acute lung injury (ALI) mouse models were established by inducing lung injury via PC. This injury was verified using hematoxylin and eosin (H&E) staining, following which bronchoalveolar lavage fluid (BALF) was collected from these mice for analysis and further experimentation. CD44, LC3 I/II ratio, Beclin-1, and p62 expression levels in A549 cells were determined using immunohistochemistry, and western blot assays. CCK-8, flow cytometry, and acridine orange/ethidium bromide (AO/EB) fluorescence staining were used to quantify cell growth induced by BALF. LC3 II and LC3 I expression was determined through immunofluorescence. CD44-knockdown mice were used to demonstrate lung function after PC. RESULTS: The successful establishment of the ALI mouse models, created via PC was confirmed by an enhanced inflammatory response in the lung tissue, markers of cell autophagy. The ALI mice were found to have elevated CD44 expression. The viability of A549 cells exposed to BALF was downregulated, while the knockdown of CD44 promoted this effect. AO/EB and flow cytometry also indicated that the knockdown of CD44 promoted the cell apoptosis induced by BALF. Western blot analysis showed that knockdown of CD44 can inhibit LC3 I/II, p62, and Beclin-1 expression induced by BALF exposure. Additionally, knockdown of CD44 in mice was found to promote PC-induced lung injury through the attenuation of autophagy. CONCLUSIONS: Knockdown CD44 was shown to inhibit cell growth and induced cell apoptosis via autophagy signaling pathways, promote mice with ALI induced by PC in vivo and in vitro.