Gastroenterology
Abstract
Metabolic dysfunction–associated steatotic liver disease (MASLD) is the most common chronic liver disease worldwide for which there is only one approved treatment. Adenosine monophosphate–activated protein kinase (AMPK) is an interesting therapeutic target since it acts as a central regulator of cellular metabolism. Despite efforts to target AMPK, no direct activators have yet been approved for treatment of this disease. This study investigated the effect of the AMPK activator ATX-304 in a preclinical mouse model of progressive fatty liver disease. The data demonstrated that ATX-304 diminishes body fat mass, lowers blood cholesterol levels, and mitigates general liver steatosis and the development of liver fibrosis, but with pronounced local heterogeneities. The beneficial effects of ATX-304 treatment were accompanied by a shift in the liver metabolic program, including increased fatty acid oxidation, reduced lipid synthesis, as well as remodeling of cholesterol and lipid transport. We also observed variations in lipid distribution among liver lobes in response to ATX-304, and a shift in the zonal distribution of lipid droplets upon treatment. Taken together, our data suggested that ATX-304 holds promise as a potential treatment for MASLD.
Authors
Emanuel Holm, Isabeau Vermeulen, Saba Parween, Ana López-Pérez, Berta Cillero-Pastor, Michiel Vandenbosch, Silvia Remeseiro, Andreas Hörnblad
Abstract
Authors
Máté Sándor, Balázs Csaba Németh, Alexandra Demcsák, Miklós Sahin-Tóth
Abstract
Infectious complications (ICs) in acute pancreatitis (AP) are primarily driven by intestinal bacterial translocation, significantly increasing mortality and hospital stays. Despite this, the role of the gut microenvironment, particularly its metabolic aspects, in AP remains poorly understood. In this study, we investigated a cohort of patients with AP, and conducted supplemental murine studies, to explore the relationship between the gut metabolome and the development of ICs. Metabolomic analysis revealed that disruptions in gut tryptophan metabolism — especially reductions in serotonin and indole pathways — are key features associated with IC occurrence. Additionally, elevated plasma levels of tryptophan metabolites within the kynurenine pathway were identified as valuable predictive biomarkers for ICs. Mechanistic studies in murine models demonstrated that an impaired intestinal Th17 response, modulated by these tryptophan metabolites, plays a critical role in IC development. Serotonin supplementation enhanced Th17 responses, reducing IC incidence, while administration of kynurenic acid, a kynurenine metabolite, exacerbated pancreatic infections, potentially through immunosuppressive effects. These findings highlight the pivotal role of tryptophan metabolites in AP pathogenesis, emphasizing their potential as both predictive markers and therapeutic targets in IC management.
Authors
Daosheng Wang, Silei Sun, Qianli Zhao, Bing Zhao, Li Ma, Tongxuan Su, Lili Xu, Menglu Gui, Dan Xu, Wei Chen, Yu Zeng, Yining Shen, Yiyue Liu, Cen Jiang, Qi Ni, Yingchao Cui, Yide Lu, Qiuya Lu, Danfeng Dong, Yibing Peng, Enqiang Mao
Abstract
Crohn’s disease (CD) involves a complex intestinal microenvironment driven by chronic inflammation. While single-cell RNA sequencing has provided valuable insights into this biology, the spatial context is lost during single-cell preparation of mucosal biopsies. To deepen our understanding of the distinct inflammatory signatures of CD and overcome the limitations of single-cell RNA sequencing, we combined spatial transcriptomics of frozen CD surgical tissue sections with single-cell transcriptomics of ileal CD mucosa. Coexpressed genes and cell-cell communication from single-cell analyses and factorized genes from spatial transcriptomics revealed overlapping pathways affected in inflamed CD, like antigen presentation, phagosome activity, cell adhesion, and extracellular matrix. Within the pathways, early epithelial cells showed evidence of significant changes in gene expression and subtype composition, while spatial mapping revealed the location of the events, particularly antigen presentation from epithelial cells in the base of the crypt. Furthermore, we identified early epithelial cells as a potential mediator of the MHC class II pathway during inflammation, which we validated by spatial transcriptomics cell subtype deconvolution. Therefore, the inflammation from CD appears to change the types of interactions detectable between epithelial cells with immune and mesenchymal cells, likely promoting the conditions for more macrophage infiltration into these inflammatory microdomains.
Authors
Vasantha L. Kolachala, Sushma Chowdary Maddipatla, Shanta Murthy, Yeonjoo Hwang, Anne F. Dodd, Garima Sharma, Sachith Munasinghe, Ranjit Singh Pelia, Suresh Venkateswaran, Murugadas Anbazhagan, Tarun Koti, Navdeep Jhita, Gaurav N. Joshi, Chrissy A. Lopez, Duke Geem, Hong Yin, David J. Cutler, Peng Qiu, Jason D. Matthews, Subra Kugathasan
Abstract
Postinfectious, diarrhea-predominant, irritable bowel syndrome (PI-IBS-D) is difficult to treat owing to its unknown pathophysiology. Extracellular vesicles (EVs) derived from human colon tissue and long noncoding RNAs (lncRNAs), such as growth arrest–specific 5 (GAS5), may play key roles in the pathophysiology of PI-IBS-D. To determine whether altered colonic EV lncRNA signaling leads to gastrointestinal dysfunction and heightened visceral nociception in patients with PI-IBS-D via the GAS5/miR-23ab/NMDA NR2B axis, we conducted translational studies, including those on (a) the role of colonic EV lncRNAs in patients with PI-IBS-D, human colonoids, and PI-IBS-D tissues; (b) i.p. injection of colonic EVs from patients with PI-IBS-D into Rab27a/b–/– mice (P-EV mice) to investigate whether colonic EVs drive visceral hypersensitivity in vivo via the GAS5/miR-23ab/NMDA NR2B axis; and (c) treatment of mice with oligo-miR-23 precursors and anti-GAS5 Vivo-Morpholinos for GAS5/miR-23ab/NMDA NR2B axis mechanisms. Colonic EVs from patients with PI-IBS-D, but not from control participants, demonstrated reduced miR-23a/b expression caused by enhanced GAS5 expression, which drives increased NR2B expression. Intraperitoneal injection of anti–GAS5-Vivo-Morpholino into P-EV mice increased miR-23 levels and decreased NR2B expression and VMR to CD. EVs are internal messengers that alter gastrointestinal function and increase visceral nociception in patients with PI-IBS-D. Strategies to deliver EVs to modulate GAS5/miR-23ab/NMDA NR2B axis signaling may lead to new and innovative treatments for patients with PI-IBS-D.
Authors
QiQi Zhou, Liuqing Yang, Zachary T. Verne, Benjamin B. Zhang, Jeremy Z. Fields, Amber T. Thacker, G. Nicholas Verne
Abstract
Although biologics have been revolutionizing the treatment of inflammatory bowel diseases (IBD) over the past decade, a significant number of patients still fail to benefit from these drugs. Overcoming the nonresponse to biologics is one of the top challenges in IBD treatment. In this study, we revealed that hyaluronan (HA), an extracellular matrix (ECM) component in the gut, is associated with nonresponsiveness to infliximab and vedolizumab therapy in patients with IBD. In murine colitis models, inhibition of HA synthase 2–mediated (HAS2-mediated) HA synthesis sensitized the therapeutic response to infliximab. Mechanistically, HA induced the expression of MMP3 in colonic fibroblasts by activating STAT3 signaling, thereby mediating the proteolytic cleavage of multiple IgG1 biologics. Finally, we found that macrophage-derived factors upregulated HAS2 expression in fibroblasts, thereby contributing to infliximab nonresponse. In summary, we identified a pathogenic connection between abnormal ECM remodeling and biologics nonresponse and provided insights for the precise therapy for IBD.
Authors
Peng Xiao, Zhehang Chen, Xuechun Cai, Wenhao Xia, Xia Liu, Zhangfa Song, Huijuan Wang, Yuening Zhao, Youling Huang, Yu Zhang, Ke Guo, Haotian Chen, Rongbei Liu, Changcheng Meng, Yanfei Fang, Yunkun Lu, Qian Cao
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is a drug resistant and lethal cancer. Identification of the genes that consistently show altered expression across patients’ cohorts can expose effective therapeutic targets and strategies. To identify such genes, we separately analyzed five human PDAC microarray datasets. We defined genes as ‘consistent’ if upregulated or downregulated in ≥ 4 datasets (adjusted P<0.05). The genes were subsequently queried in additional datasets, including single-cell RNA-sequencing data, and we analyzed their pathway enrichment, tissue-specificity, essentiality for cell viability, association with cancer features e.g., tumor subtype, proliferation, metastasis and poor survival outcome. We identified 2,010 consistently upregulated and 1,928 downregulated genes of which >50%, to our knowledge, were uncharacterized in PDAC. These genes spanned multiple processes, including cell cycle, immunity, transport, metabolism, signaling and transcriptional/epigenetic regulation – cell cycle and glycolysis being the most altered. Several upregulated genes correlated with cancer features, and their suppression impaired PDAC cell viability in prior CRISPR/Cas9 and RNA interference screens. Further, the upregulated genes predicted sensitivity to bromodomain and extraterminal (epigenetic) protein inhibition, which, in combination with gemcitabine, disrupted amino acid metabolism and in vivo tumor growth. Our results highlight genes for further studies in the quest for PDAC mechanisms, therapeutic targets and biomarkers.
Authors
Zeribe C. Nwosu, Heather Giza, Maya Nassif, Verodia Charlestin, Rosa E. Menjivar, Daeho Kim, Samantha B. Kemp, Peter Sajjakulnukit, Anthony Andren, Li Zhang, William K.M. Lai, Ian Loveless, Nina G. Steele, Jiantao Hu, Biao Hu, Shaomeng Wang, Marina Pasca di Magliano, Costas A. Lyssiotis
Abstract
Crohn's disease (CD) is the chronic inflammation of the terminal ileum and colon triggered by a dysregulated immune response to bacteria, but insights into specific molecular perturbations at the critical bacteria-epithelium interface are limited. Here we report that the membrane mucin MUC17 protected small intestinal enterocytes against commensal and pathogenic bacteria. In non-inflamed CD ileum, reduced MUC17 levels and a compromised glycocalyx barrier allowed recurrent bacterial contact with enterocytes. Muc17 deletion in mice rendered the small intestine particularly prone to atypical bacterial infection while maintaining resistance to colitis. The loss of Muc17 resulted in spontaneous deterioration of epithelial homeostasis and in the extra-intestinal translocation of bacteria. Finally, Muc17-deficient mice harbored specific small intestinal bacterial taxa observed in CD patients. Our findings highlight MUC17 as an essential regiospecific line of defense in the small intestine with relevance for early epithelial defects in CD.
Authors
Elena Layunta, Sofia Jäverfelt, Fleur C. van de Koolwijk, Molly Sivertsson, Brendan Dolan, Liisa Arike, Sara I.M. Thulin, Bruce A. Vallance, Thaher Pelaseyed
Abstract
Authors
Huafeng Fu, Qinbo Cai, Zhijun Zhou, Yulong He, Min Li, DongJie Yang
Abstract
The pathogenesis of the murine model of autoimmune pancreatitis associated with IgG4-related disease (AIP/IgG4-RD) induced by administration of polyinosinic-polycytidylic acid, is incompletely understood. While it is known that murine and human AIP/IgG4-RD is driven by plasmacytoid dendritic cells (pDCs) producing IFN-α, the origin of these cells and their relation to effector T cells is not known. Here we show that murine AIP was initiated by TLR3-bearing conventional DCs in the uninflamed pancreas whose activation by TLR3 ligand (polyinosinic-polycytidylic acid) caused IFN-α, CXCL9, and CXCL10 secretion. This, in turn, induced pancreatic recruitment of CXCR3+ T cells and these T cells, via their secretion of CCL25, facilitated migration of pDCs bearing CCR9 into the pancreas. This established a feedback loop anchored by the now dominant pDC production of IFN-α and the continued CXCR3+ T cell facilitation of pDC migration. Remarkably, the interaction between CXCR3+ T cells and pDCs also existed at the functional levels since this interaction enhanced the production of CCL25 and IFN-α by CXCR3+ T cells and pDCs, respectively. Evidence presented here that a similar disease mechanism was present in human AIP/IgG4-RD creates new avenues of disease treatment.
Authors
Akane Hara, Tomohiro Watanabe, Kosuke Minaga, Tomoe Yoshikawa, Masayuki Kurimoto, Ikue Sekai, Yasuhiro Masuta, Ryutaro Takada, Yasuo Otsuka, Ken Kamata, Shiki Takamura, Masatoshi Kudo, Warren Strober
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