Effects of sevoflurane on lung alveolar epithelial wound healing and survival in a sterile in vitro model of acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is a serious lung condition that often leads to hospitalization in intensive care units and a high mortality rate. Sevoflurane is a volatile anesthetic with growing interest for sedation in ventilated patients with ARDS. It has been shown to have potential lung-protective effects, such as reduced inflammation and lung edema, or improved arterial oxygenation. In this study, we investigated the effects of sevoflurane on lung injury in cultured human carcinoma-derived lung alveolar epithelial (A549) cells. We found that sevoflurane was associated with improved wound healing after exposure to inflammatory cytokines, with preserved cell proliferation but no effect on cell migration properties. Sevoflurane exposure was also associated with enhanced cell viability and active autophagy in A549 cells exposed to cytokines. These findings suggest that sevoflurane may have beneficial effects on lung epithelial injury by promoting alveolar epithelial wound healing and by influencing the survival and proliferation of A549 epithelial cells in vitro. Further research is needed to confirm these findings and to investigate the key cellular mechanisms explaining sevoflurane's potential effects on lung epithelial injury.

Antibiotic-induced disturbances of the gut microbiota result in accelerated breast tumor growth.

The gut microbiota's function in regulating health has seen it linked to disease progression in several cancers. However, there is limited research detailing its influence in breast cancer (BrCa). This study found that antibiotic-induced perturbation of the gut microbiota significantly increases tumor progression in multiple BrCa mouse models. Metagenomics highlights the common loss of several bacterial species following antibiotic administration. One such bacteria, Faecalibaculum rodentium, rescued this increased tumor growth. Single-cell transcriptomics identified an increased number of cells with a stromal signature in tumors, and subsequent histology revealed an increased abundance of mast cells in the tumor stromal regions. We show that administration of a mast cell stabilizer, cromolyn, rescues increased tumor growth in antibiotic treated animals but has no influence on tumors from control cohorts. These findings highlight that BrCa-microbiota interactions are different from other cancers studied to date and suggest new research avenues for therapy development.

CRISPR/Cas9-Engineered HLA-Deleted Glomerular Endothelial Cells as a Tool to Predict Pathogenic Non-HLA Antibodies in Kidney Transplant Recipients.

BACKGROUND: After kidney transplantation, donor-specific antibodies against human leukocyte antigen donor-specific antibodies (HLA-DSAs) drive antibody-mediated rejection (ABMR) and are associated with poor transplant outcomes. However, ABMR histology (ABMRh) is increasingly reported in kidney transplant recipients (KTRs) without HLA-DSAs, highlighting the emerging role of non-HLA antibodies (Abs). METHODS: W e designed a non-HLA Ab detection immunoassay (NHADIA) using HLA class I and II-deficient glomerular endothelial cells (CiGEnCΔHLA) that had been previously generated through CRISPR/Cas9-induced B2M and CIITA gene disruption. Flow cytometry assessed the reactivity to non-HLA antigens of pretransplantation serum samples from 389 consecutive KTRs. The intensity of the signal observed with the NHADIA was associated with post-transplant graft histology assessed in 951 adequate biopsy specimens. RESULTS: W e sequentially applied CRISPR/Cas9 to delete the B2M and CIITA genes to obtain a CiGEnCΔHLA clone. CiGEnCΔHLA cells remained indistinguishable from the parental cell line, CiGEnC, in terms of morphology and phenotype. Previous transplantation was the main determinant of the pretransplantation NHADIA result (P<0.001). Stratification of 3-month allograft biopsy specimens (n=298) according to pretransplantation NHADIA tertiles demonstrated that higher levels of non-HLA Abs positively correlated with increased glomerulitis (P=0.002), microvascular inflammation (P=0.003), and ABMRh (P=0.03). A pretransplantation NHADIA threshold of 1.87 strongly discriminated the KTRs with the highest risk of ABMRh (P=0.005, log-rank test). A multivariate Cox model confirmed that NHADIA status and HLA-DSAs were independent, yet synergistic, predictors of ABMRh. CONCLUSION: The NHADIA identifies non-HLA Abs and strongly predicts graft endothelial injury independent of HLA-DSAs.

Antibiotics induce sustained dysregulation of intestinal T cell immunity by perturbing macrophage homeostasis.

Macrophages in the healthy intestine are highly specialized and usually respond to the gut microbiota without provoking an inflammatory response. A breakdown in this tolerance leads to inflammatory bowel disease (IBD), but the mechanisms by which intestinal macrophages normally become conditioned to promote microbial tolerance are unclear. Strong epidemiological evidence linking disruption of the gut microbiota by antibiotic use early in life to IBD indicates an important role for the gut microbiota in modulating intestinal immunity. Here, we show that antibiotic use causes intestinal macrophages to become hyperresponsive to bacterial stimulation, producing excess inflammatory cytokines. Re-exposure of antibiotic-treated mice to conventional microbiota induced a long-term, macrophage-dependent increase in inflammatory T helper 1 (TH1) responses in the colon and sustained dysbiosis. The consequences of this dysregulated macrophage activity for T cell function were demonstrated by increased susceptibility to infections requiring TH17 and TH2 responses for clearance (bacterial Citrobacter rodentium and helminth Trichuris muris infections), corresponding with increased inflammation. Short-chain fatty acids (SCFAs) were depleted during antibiotic administration; supplementation of antibiotics with the SCFA butyrate restored the characteristic hyporesponsiveness of intestinal macrophages and prevented T cell dysfunction. Butyrate altered the metabolic behavior of macrophages to increase oxidative phosphorylation and also promoted alternative macrophage activation. In summary, the gut microbiota is essential to maintain macrophage-dependent intestinal immune homeostasis, mediated by SCFA-dependent pathways. Oral antibiotics disrupt this process to promote sustained T cell-mediated dysfunction and increased susceptibility to infections, highlighting important implications of repeated broad-spectrum antibiotic use.

Structural basis for the role of serine-rich repeat proteins from Lactobacillus reuteri in gut microbe-host interactions.

Lactobacillus reuteri, a Gram-positive bacterial species inhabiting the gastrointestinal tract of vertebrates, displays remarkable host adaptation. Previous mutational analyses of rodent strain L. reuteri 100-23C identified a gene encoding a predicted surface-exposed serine-rich repeat protein (SRRP100-23) that was vital for L. reuteri biofilm formation in mice. SRRPs have emerged as an important group of surface proteins on many pathogens, but no structural information is available in commensal bacteria. Here we report the 2.00-Å and 1.92-Å crystal structures of the binding regions (BRs) of SRRP100-23 and SRRP53608 from L. reuteri ATCC 53608, revealing a unique ß-solenoid fold in this important adhesin family. SRRP53608-BR bound to host epithelial cells and DNA at neutral pH and recognized polygalacturonic acid (PGA), rhamnogalacturonan I, or chondroitin sulfate A at acidic pH. Mutagenesis confirmed the role of the BR putative binding site in the interaction of SRRP53608-BR with PGA. Long molecular dynamics simulations showed that SRRP53608-BR undergoes a pH-dependent conformational change. Together, these findings provide mechanistic insights into the role of SRRPs in host-microbe interactions and open avenues of research into the use of biofilm-forming probiotics against clinically important pathogens.

Lactobacillus reuteri Surface Mucus Adhesins Upregulate Inflammatory Responses Through Interactions With Innate C-Type Lectin Receptors.

The vertebrate gut symbiont Lactobacillus reuteri exhibits strain-specific adhesion and health-promoting properties. Here, we investigated the role of the mucus adhesins, CmbA and MUB, upon interaction of L. reuteri ATCC PTA 6475 and ATCC 53608 strains with human monocyte-derived dendritic cells (moDCs). We showed that mucus adhesins increased the capacity of L. reuteri strains to interact with moDCs and promoted phagocytosis. Our data also indicated that mucus adhesins mediate anti- and pro-inflammatory effects by the induction of interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-α), IL-1ß, IL-6, and IL-12 cytokines. L. reuteri ATCC PTA 6475 and ATCC 53608 were exclusively able to induce moDC-mediated Th1 and Th17 immune responses. We further showed that purified MUB activates moDCs and induces Th1 polarized immune responses associated with increased IFNγ production. MUB appeared to mediate these effects via binding to C-type lectin receptors (CLRs), as shown using cell reporter assays. Blocking moDCs with antibodies against DC-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) or Dectin-2 did not affect the uptake of the MUB-expressing strain, but reduced the production of TNF-α and IL-6 by moDCs significantly, in line with the Th1 polarizing capacity of moDCs. The direct interaction between MUB and CLRs was further confirmed by atomic force spectroscopy. Taken together these data suggest that mucus adhesins expressed at the cell surface of L. reuteri strains may exert immunoregulatory effects in the gut through modulating the Th1-promoting capacity of DCs upon interaction with C-type lectins.