Infection with enteric pathogens Salmonella typhimurium and Citrobacter rodentium modulate TGF-beta/Smad signaling pathways in the intestine

Sivelestat sodium alleviated sepsis-induced acute lung injury by inhibiting TGF-β/Smad signaling pathways through upregulating microRNA-744-5p

Background

Acute lung injury (ALI) is one of the most common critical illnesses in clinical practice, with sepsis being the most common cause of ALI. Sivelestat sodium (SV) hydrate is a highly effective inhibitor of neutrophil elastase, specifically targeting ALI related to systemic inflammatory response syndrome. The aim of this study is to examine the mechanisms by which SV can reduce the severity of ALI resulting from sepsis.

Methods

Cecum ligation and puncture (CLP) was employed for creating an animal model of ALI caused by sepsis. Primary human pulmonary microvascular endothelial cells (HPMECs) were treated with lipopolysaccharide (LPS) to develop an in vitro model of infection-induced ALI. Lung tissue damage was assessed by employing hematoxylin-eosin (H&E) and Masson staining. Lung edema was determined by calculating the lung wet-to-dry weight ratio. Lung tissue and cell samples were analyzed using Enzyme-linked immunosorbent assay (ELISA) to detect levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. The 5-ethynyl-2'-deoxyuridine (EdU) and wound-healing assay were used to determine the cell proliferation and migration, while flow cytometry was used for detecting cell apoptosis. The association between microRNA (miR)-744 and transforming growth factor (TGF)-β1 was discovered and confirmed through the utilization of bioinformatics analyses and dual-luciferase gene reporter assay. The analysis of TGF-β1, p-Smad3, and Smad3 was carried out through western blotting and immunohistochemistry in both in vitro and in vivo scenarios.

Results

In both in vivo and in vitro settings of ALI models of sepsis, there was a significant decrease in the level of miR-744-5p, a significant elevation in the expression of inflammatory factors, and a significant intensification of lung tissue damage. Administration of SV resulted in a significant increase in the level of miR-744-5p, suppressed the inflammatory response, and ultimately improved lung injury. Cell proliferation was significantly enhanced by SV and cell apoptosis was inhibited. The protection of SV was significantly reversed by inhibiting the effect of miR-744-5p. The double-luciferase reporter gene assay revealed substantial interactions occurring between miR-744-5p and TGF-β1. The TGF-β/Smad signaling pathway was significantly inhibited by SV, however, the inhibitory effect can be counteracted by utilizing the miR-744-5p inhibitor.

Conclusions

The upregulation of miR-744-5p by SV inhibits the TGF-β/Smad signaling pathway, thereby reducing sepsis-induced ALI.

Irisin Ameliorates Renal Tubulointerstitial Fibrosis by Regulating the Smad4/β-Catenin Pathway in Diabetic Mice

Background

The primary pathophysiology of diabetic kidney disease (DKD) is tubulointerstitial fibrosis (TIF), and an essential contributing element is excessive extracellular matrix deposition. Irisin is a polypeptide formed by splitting fibronectin type III domain containing 5 (FNDC5), which participates in a number of physiological and pathological processes.

Methods

The purpose of this article is to examine irisin's function in DKD and analyze both its in vitro and in vivo effects. The Gene Expression Omnibus (GEO) database was used to download GSE30122, GSE104954, and GSE99325. Analysis of renal tubule samples from nondiabetic and diabetic mice identified 94 differentially expressed genes (DEGs). The transforming growth factor beta receptor 2 (TGFBR2), irisin, and TGF-β1 were utilized as DEGs to examine the impact of irisin on TIF in diabetic kidney tissue, according to the datasets retrieved from the GEO database and Nephroseq database. Additionally, the therapeutic impact of irisin was also examined using Western blot, RT-qPCR, immunofluorescence, immunohistochemistry, and kits for detecting mouse biochemical indices.

Results

In vitro, the findings demonstrated that irisin not only down-regulated the expression of Smad4 and β-catenin but also reduced the expression of proteins linked to fibrosis, the epithelial-mesenchymal transition (EMT), and mitochondrial dysfunction in HK-2 cells maintained in high glucose (HG) environment. In vivo, overexpressed FNDC5 plasmid was injected into diabetic mice to enhance its expression. Our studies found that overexpressed FNDC5 plasmid not only reversed the biochemical parameters and renal morphological characteristics of diabetic mice but also alleviated EMT and TIF by inhibiting Smad4/β-catenin signaling pathway.

Conclusion

The above experimental results revealed that irisin could reduce TIF in diabetic mice via regulating the Smad4/β-catenin pathway.

Blocking GARP-mediated activation of TGF-β1 did not alter innate or adaptive immune responses to bacterial infection or protein immunization in mice

Abstract

Transmembrane protein GARP binds latent TGF-β1 to form GARP:(latent)TGF-β1 complexes on the surface of several cell types including Tregs, B-cells, and platelets. Upon stimulation, these cells release active TGF-β1. Blocking TGF-β1 activation by Tregs with anti-GARP:TGF-β1 mAbs overcomes resistance to PD1/PD-L1 blockade and induces immune-mediated regressions of murine tumors, indicating that Treg-derived TGF-β1 inhibits anti-tumor immunity. TGF-β1 exerts a vast array of effects on immune responses. For example, it favors differentiation of T_H17 cells and B-cell switch to IgA production, two important processes for mucosal immunity. Here, we sought to determine whether treatment with anti-GARP:TGF-β1 mAbs would perturb immune responses to intestinal bacterial infection. We observed no aggravation of intestinal disease, no systemic dissemination, and no alteration of innate or adaptative immune responses upon oral gavage of C. rodentium in highly susceptible Il22r^−/− mice treated with anti-GARP:TGF-β1 mAbs. To examine the effects of GARP:TGF-β1 blockade on Ig production, we compared B cell- and T_H cell- responses to OVA or CTB protein immunization in mice carrying deletions of Garp in Tregs, B cells, or platelets. No alteration of adaptive immune responses to protein immunization was observed in the absence of GARP on any of these cells. Altogether, we show that antibody-mediated blockade of GARP:TGF-β1 or genetic deletion of Garp in Tregs, B cells or platelets, do not alter innate or adaptive immune responses to intestinal bacterial infection or protein immunization in mice. Anti-GARP:TGF-β1 mAbs, currently tested for cancer immunotherapy, may thus restore anti-tumor immunity without severely impairing other immune defenses.

Précis

Immunotherapy with GARP:TGF-β1 mAbs may restore anti-tumor immunity without impairing immune or inflammatory responses required to maintain homeostasis or host defense against infection, notably at mucosal barriers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00262-021-03119-8.

Enterobacterial LPS-inducible LINC00152 is regulated by histone lactylation and promotes cancer cells invasion and migration

Gut microbes participate in pathogenesis by interacting with the host genome through epigenetic mechanisms, such as long non-coding RNAs. However, the mechanisms by which the microbiota induce expression alteration of long non-coding RNAs remains unclear. Here, we quantified the transcriptome alteration of human colon cell lines after being infected by a common enteric pathogen Salmonella typhimurium SL1344. We observed a widespread lncRNAs expression alteration. Among them, the elevated expression of LINC00152 was verified and proved to be induced by enteric bacteria-derived lipopolysaccharide (LPS). The inducible LINC00152 were found to inhibit Salmonella invasion and inflammation response. LINC00152 was overexpressed in tumors of the clinical CRC samples compared with adjacent normal tissues. Accordingly, we also demonstrated that overexpression of LINC00152 promoted the migration and invasion of colorectal cancer cells. Consistently, we observed an increased abundance of gram-negative bacteria and LPS in tumors tissue. Taken together, the above data implicated that enriched gram-negative bacteria in tumor tissue might promote tumor growth through modulating the expression of LINC00152. Furthermore, we demonstrated that LPS upregulated the expression of LINC00152 by introducing histone lactylation on its promoter and decreasing the binding efficiency of the repressor, YY1, to it. Our results provide new insights into how enterobacteria affect host epigenetics in human disease.

Colonization resistance: metabolic warfare as a strategy against pathogenic Enterobacteriaceae

The intestine is home to a large and complex bacterial ecosystem (microbiota), which performs multiple beneficial functions for the host, including immune education, nutrition, and protection against invasion by enteric pathogens (colonization resistance). The host and microbiome symbiotic interactions occur in part through metabolic crosstalk. Thus, microbiota members have evolved highly diverse metabolic pathways to inhibit pathogen colonization via activation of protective immune responses and nutrient acquisition and utilization. Conversely, pathogenic Enterobacteriaceae actively induce an inflammation-dependent disruption of the gut microbial ecosystem (dysbiosis) to gain a competitive metabolic advantage against the resident microbiota. This review discusses the recent findings on the crucial role of microbiota metabolites in colonization resistance regulation. Additionally, we summarize metabolic mechanisms used by pathogenic Enterobacteriaceae to outcompete commensal microbes and cause disease.

Fermentation and Metabolism of Dietary Protein by Intestinal Microorganisms

Dietary protein is linked to the intestinal microorganisms. The decomposition of dietary protein can provide nutrients for microbial growth, which in turn can ferment protein to produce some metabolites. This review elaborates that the effects of different protein levels and types on intestinal microorganisms and their metabolites fermented by intestinal microorganisms, as well as the effects of these metabolites on organisms. It is well known that intestinal microbial imbalance can cause some diseases. Dietary protein supplementation can alter the composition of intestinal microorganisms and thus regulates the body health. However, protein can also produce some harmful metabolites. Therefore, how to rationally supplement protein is particularly important.

Clostridium species as probiotics: potentials and challenges

Clostridium species, as a predominant cluster of commensal bacteria in our gut, exert lots of salutary effects on our intestinal homeostasis. Up to now, Clostridium species have been reported to attenuate inflammation and allergic diseases effectively owing to their distinctive biological activities. Their cellular components and metabolites, like butyrate, secondary bile acids and indolepropionic acid, play a probiotic role primarily through energizing intestinal epithelial cells, strengthening intestinal barrier and interacting with immune system. In turn, our diets and physical state of body can shape unique pattern of Clostridium species in gut. In view of their salutary performances, Clostridium species have a huge potential as probiotics. However, there are still some nonnegligible risks and challenges in approaching application of them. Given this, this review summarized the researches involved in benefits and potential risks of Clostridium species to our health, in order to develop Clostridium species as novel probiotics for human health and animal production.

Gut Bacterial Metabolite Urolithin A (UA) Mitigates Ca2+ Entry in T Cells by Regulating miR-10a-5p

The gut microbiota influences several biological functions including immune responses. Inflammatory bowel disease is favorably influenced by consumption of several dietary natural plant products such as pomegranate, walnuts, and berries containing polyphenolic compounds such as ellagitannins and ellagic acid. The gut microbiota metabolizes ellagic acid resulting in the formation of bioactive urolithins A, B, C, and D. Urolithin A (UA) is the most active and effective gut metabolite and acts as a potent anti-inflammatory and anti-oxidant agent. However, whether gut metabolite UA affects the function of immune cells remains incompletely understood. T cell proliferation is stimulated by store operated Ca2+ entry (SOCE) resulting from stimulation of Orai1 by STIM1/STIM2. We show here that treatment of murine CD4+ T cells with UA (10 μM, 3 days) significantly blunted SOCE in CD4+ T cells, an effect paralleled by significant downregulation of Orai1 and STIM1/2 transcript levels and protein abundance. UA treatment further increased miR-10a-5p abundance in CD4+ T cells in a dose dependent fashion. Overexpression of miR-10a-5p significantly decreased STIM1/2 and Orai1 mRNA and protein levels as well as SOCE in CD4+ T cells. UA further decreased CD4+ T cell proliferation. Thus, the gut bacterial metabolite UA increases miR-10a-5p levels thereby downregulating Orai1/STIM1/STIM2 expression, store operated Ca2+ entry, and proliferation of murine CD4+ T cells.