ABSRTACT Klebsiella pneumoniae is a common cause of human-pneumonia-derived sepsis with high morbidity and mortality. The microbiota promotes and maintains host immune homeostasis. The mechanisms by which the gut microbiota affects the host defenses in the respiratory system systematically, however, remain poorly understood. Here, we show that gut microbiota depletion increases susceptibility to extracellular K. pneumoniae infections in terms of increased bacterial burdens in lung and decreased survival rates. Oral supplementation with gut microbiota-derived short-chain fatty acids (SCFAs), subsequently activating G protein-coupled receptor 43 (GPCR43), enhances a macrophage’s capacity to phagocytose invading K. pneumoniae. Furthermore, SCFAs and GPR43 increase macrophage bacterial clearance by upregulating LAMTOR2, which is further identified as an antibacterial effector and elucidated to facilitate phagosome-lysosome fusion and extracellular signal-regulated kinase (ERK) phosphorylation. Lastly, conditional ablation of Lamtor2 in macrophages decreases their antimicrobial activity, even though mice were pretreated with exogenous SCFA supplementation. IMPORTANCE These observations highlight that SCFAs promote macrophage elimination of K. pneumoniae via a LAMTOR2-dependent signal pathway and suggest that it is possible to intervene in K. pneumoniae pneumonia by targeting the gut microbiota.
The aim of the study was to evaluate the effect of regulation of TLR7 on Mycobacterium tuberculosis (Mtb) survival in macrophages. TLR7 expression in macrophages infected by Mtb was detected by RT-PCR and Western blotting. Regulation of TLR7 was achieved by single strand RNA (ssRNA) or siRNA. The effects of TLR7 on Mtb survival and cell viability were detected by acid fast staining and cell counting kit-8, respectively. Cell ultrastructure was observed via transmission electron microscopy (TEM), and autophagy related protein LC3 was analyzed by Western blotting. TLR7 in Mtb infected macrophages was up-regulated and up-regulation of TLR7 could eliminate intracellular Mtb. Up-regulation of TLR7 could increase viability of Mtb infected cells, while down-regulation of TLR7 induced decrease of cell viability compared with the controls. Autophagosome was significantly increased in the Mtb infected macrophages after up-regulation of TLR7 and LC3-II protein showed obvious increase compared with the controls. Autophagosome could not be detected in macrophages after down-regulation of TLR7, rough endoplasmic reticulum was dilated, and nuclear week gap was widened. Moreover, LC3-II protein was reduced in Mtb infected macrophages based upon the down-regulation of TLR7. Up-regulation of TLR7 could eliminate intracellular Mtb through autophagy. J. Cell. Biochem. 118: 4222-4229, 2017. © 2017 Wiley Periodicals, Inc.
Background Intrauterine adhesion (IUA) is one of the leading causes of infertility and the main clinical challenge is the high recurrence rate. The key to solving this dilemma lies in elucidating the mechanisms of endometrial fibrosis. The aim of our team is to study the mechanism underlying intrauterine adhesion fibrosis and the origin of fibroblasts in the repair of endometrial fibrosis. Methods Our experimental study involving an animal model of intrauterine adhesion and detection of fibrosis-related molecules. The levels of molecular factors related to the endothelial-to-mesenchymal transition (EndMT) were examined in a rat model of intrauterine adhesion using immunofluorescence, immunohistochemistry, qPCR and Western blot analyses. Main outcome measures are levels of the endothelial marker CD31 and the mesenchymal markers alpha-smooth muscle actin (α-SMA) and vimentin. Results Immunofluorescence co-localization of CD31 and a-SMA showed that 14 days after moulding, double positive cells for CD31 and a-SMA could be clearly observed in the endometrium. Decreased CD31 levels and increased α-SMA and vimentin levels indicate that EndMT is involved in intrauterine adhesion fibrosis. Conclusions Endothelial cells promote the emergence of fibroblasts via the EndMT during the endometrial fibrosis of intrauterine adhesions.
Intrauterine adhesions (IUA) is a common gynecological disease and is a leading cause of female infertility. Mechanical or infectious damage to the endometrial basal layer can lead to endometrial fibrosis, which is the most common cause of IUA. Endoplasmic reticulum stress (ERS), the transforming growth factor beta signaling pathway (TGF-β/SMAD) and epithelial–mesenchymal transition (EMT) are important factors promoting endometrial fibrosis. The purpose of this study was to determine the up- and downstream regulatory relationships of the above three in the process of endometrial fibrosis. The rat IUA model was induced by double injury method and prophylactic injection of the ERS inhibitor 4-phenylbutyric acid (4-PBA) was given in vivo. The ERS activator tunicamycin and the TGF-β/SMAD pathway inhibitor A 83-01 were used in human endometrial epithelial cells (HEECs) in vitro. Masson’s trichrome, Sirius red staining, immunohistochemistry, immunofluorescence and west-ern blot analyses were used to determine ERS, TGF-β/SMAD pathway, EMT and fibrosis markers in the uterine tissue and HEECs of the different treatment groups. In animal experiments, ERS and the TGF-β/SMAD pathway had been activated and EMT occurred in an in vivo model of IUA, but suppressed in animals treated with prophylactic 4-PBA. In vitro experiments, tunicamycin-treated HEECs had increased the activation of ERS, the abundance of TGF-β/SMAD pathway and fibrosis markers while EMT occurred, but the TGF-β/SMAD pathway and EMT were significantly inhibited in the tunicamycin+A 83-01 group. Our data suggest that increased ERS can induce EMT and promote endometrial fibrosis through the TGF-β/SMAD pathway.
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