Cellular and Molecular Gastroenterology and Hepatology最新文献

Backgrounds & aims: Since the Omicron variant emerged as a major SARS-CoV-2 variant, COVID-19-associated mortality has decreased remarkably. Nevertheless, patients with a history of SARS-CoV-2 infection have been suffering from an aftereffect commonly known as 'long COVID', affecting diverse organs. However, the effect of SARS-CoV-2 on gastric cells and disease progression was not previously known. We aimed to investigate whether SARS-CoV-2 infection affects stomach cells and if post-COVID-19 conditions can lead to severe gastric disease.

Methods: Stomach specimens obtained from male K18-hACE2 mice 7 days after SARS-CoV-2 infection were subjected to a transcriptomic analysis for molecular profiling. To investigate the putative role of SARS-CoV-2 in gastric carcinogenesis, K18-hACE2 mice affected by nonlethal COVID-19 were also inoculated with Helicobacter pylori SS1.

Results: Despite the lack of viral dissemination and pathological traits in the stomach, SARS-CoV-2 infection caused dramatic changes to the molecular profile and some immune subsets in this organ. Notably, the gene sets related to metaplasia and gastric cancer were significantly enriched after viral infection. As a result, chronic inflammatory responses and preneoplastic transitions were promoted in these mice.

Conclusion: SARS-CoV-2 infection indirectly leads to profound and post-acute COVID-19 alterations in the stomach at the cellular and molecular levels, resulting in adverse outcomes following co-infection with SARS-CoV-2 and H. pylori. Our results show that two prevalent pathogens of humans elicit a negative synergistic effect and provide evidence of the risk of severe chronic gastritis in the post-COVID-19 era.

More than 300 genomic loci have been associated with increased susceptibility to inflammatory bowel disease through genome-wide association studies (GWAS). A major challenge in the translation of GWAS to mechanistic insights lies in connecting non-coding variants to function. For example, single nucleotide variants (SNVs) in the vicinity of the gene encoding the transcription factor ETS2 on human chromosome 21 are associated with the risk of developing inflammatory bowel disease (IBD) in Europeans. The peak of SNV association lies within a distal enhancer that may regulate ETS2 transcription. The interpretation of this and many other SNV associations with IBD depends upon a model linking variation in transcriptional regulation to the likelihood of developing chronic intestinal inflammation. One model for the ETS2 locus is that over-expression in monocytes is causally associated with the risk allele which in turn leads to a hyper-inflammatory state. Here we summarise evidence for an alternative mechanism focussed on negative regulators of monocyte-macrophage activation. We argue that IBD susceptibility arises from dysregulation of monocyte adaptation in the intestinal milieu to form resident intestinal macrophages that are anergic to inflammatory stimuli. This process depends upon signals initiated by macrophage colony-stimulating factor (CSF1) binding to its receptor (CSF1R). Within this framework, ETS2 is a myeloid-specific transcription factor, expressed in pluripotent and committed progenitors and monocytes, and is down-regulated by CSF1, in common with many genes associated with IBD susceptibility, including NOD2. ETS2 is also both a downstream target and a mediator of the CSF1/CSF1R signalling pathway. Therapeutic targeting of ETS2 and its upstream regulators has the potential to prevent CSF1-dependent monocyte differentiation towards a pro-repair resident macrophage phenotype and consequently exacerbate intestinal inflammation.

Background and aims: The incidence of Barrett esophagus (BE) and Gastroesophageal Adenocarcinoma (GEAC) correlates with obesity and a diet rich in fat. Bile acids (BA) support fat digestion and undergo microbial metabolism in the gut. The farnesoid X receptor (FXR) is an important modulator of the BA homeostasis. When activated, FXR can inhibit cancer-related processes and thus, it is an appealing therapeutic target. Here, we assess the effect of diet on the microbiota-BA axis and evaluate the role of FXR in disease progression.

Methods: L2-IL1B mice (mouse model of BE and GEAC) under different diets, and L2-IL1B-FXR KO-mice were characterized. L2-IL1B-derived organoids were exposed to different BAs and to the FXR agonist obeticholic acid, OCA. The BA profile in serum and stool of healthy controls, BE- and GEAC-patients was assessed.

Results: Here we show that high fat diet accelerated tumorigenesis in L2-IL1B mice while increasing BA levels and altering the composition of the gut microbiota. While upregulated in BE, expression of FXR was downregulated in GEAC in mice and humans. In L2-IL1B mice, FXR knockout enhanced the dysplastic phenotype and increased Lgr5 progenitor cell numbers. Treatment of murine BE organoids and L2-IL1B mice with OCA notably ameliorated the phenotype.

Conclusion: GEAC carcinogenesis appears to be partially driven via loss or inhibition of FXR on progenitor cells at the gastroesophageal junction. Considering that the resulting aggravation in the phenotype could be reversed with OCA treatment, we suggest that FXR agonists have great potential as a preventive strategy against GEAC progression.

Background and aims: Patients with obesity and mouse models of obesity exhibit abnormalities in intestinal epithelial cells, including enhanced stemness. Adipose tissue (AT) is the largest endocrine organ secreting cytokines, hormones, and extracellular vesicles (EVs). Here, we characterized EV protein cargo from obese and non-obese AT and demonstrate the role of obese adipose-derived EVs in enhancing colonic stemness.

Methods: EVs were isolated from visceral AT from mice fed high-fat diet to induce obesity or control matched-diet. EV cargo was characterized by unbiased proteomics. Mouse colonoids were treated with EVs and analyzed for fatty acid β-oxidation (FAO), expression of stem marker genes, stem function, and β-catenin expression and acetylation. Mice deficient in adipocyte-specific Tsg101 expression were generated to alter adipocyte EV protein cargo and colonic stemness was measured.

Results: EVs secreted from obese visceral AT (Ob EVs) were significantly enriched with acyl-CoA dehydrogenase long chain (ACADL), an initiator enzyme of FAO. Compared to non-obese EVs, colonoids treated with Ob EVs exhibited increased exogenous ACADL protein expression, FAO, growth, persistence of stem/progenitor function, and increased β-catenin protein expression and acetylation that was abolished by FAO inhibition. Mice deficient in adipocyte-specific Tsg101 expression exhibited Ob EVs with altered protein expression profiles and were protected from obesity-induced enhanced colonic stemness.

Conclusions: The contents of Ob EVs are poised to fuel FAO and to promote obesity-induced stemness in the colon. Alteration of metabolism is a key mechanism of adipose-to-intestinal tissue communication elicited by EVs, thereby influencing basal colonic stem cell homeostasis during obesity.

Background & aims: Hepatocellular carcinoma (HCC), the dominant form of liver cancer, is a leading cause of cancer death worldwide. Sorafenib and lenvatinib have been the two limited options of first-line treatments for unresectable advanced HCC patients for long. However, the single drug treatment strategy only shows modest survival benefit, mostly because of the survival ability of cancer cells to activate alternative pathways for compensation. In this study, we aim to identify druggable targets contributing to lenvatinib resistance and evaluate the efficacy of combining respective inhibitors and lenvatinib on HCC.

Methods: Genome-scale clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 knockout library screening was applied on vehicle group and lenvatinib treatment group. Identified druggable candidates were validated individually on HCC cell model. Therapeutic effects of the combined treatment of inhibitors of candidate genes and lenvatinib were evaluated in vitro and in vivo.

Results: We successfully identified NFKB1 and MET as critical drivers for the development of lenvatinib resistance in HCC cells. By perturbing the two genes with either CRISPR knockout or RNA interference approaches, lenvatinib treatments were significantly sensitized. Moreover, using small molecules QNZ and cabozantinib to target NFKB1 and MET respectively, together with lenvatinib could synergistically induce apoptosis and suppress HCC growth in vitro and in vivo.

Conclusion: Our results demonstrated that genome-wide CRISPR/Cas9 screening is a powerful tool for the design of rational combinational cancer therapy and provided candidate genes possible for combined treatments with lenvatinib to improve therapy efficacy.