Ketogenesis alleviates TNFα-induced apoptosis and inflammatory responses in intestinal cells

Peiminine ameliorates Crohn's disease-like colitis by enhancing the function of the intestinal epithelial barrier through Nrf2/HO1 signal

BACKGROUND AND AIMS

Impaired intestinal barrier function is key in maintaining intestinal inflammation in Crohn's disease (CD). However, no targeted treatment in clinical practice has been developed. Peiminine (Pm) strongly protects the epithelial barrier, the purpose of this study is to investigate whether Pm affects CD-like colitis and potential mechanisms for its action.

METHODS

Trinitro-benzene-sulfonic acid (TNBS)-induced mice and Il-10-/- mice were used as CD animal models. Colitis symptoms, histological analysis, and intestinal barrier permeability were used to assess the Pm's therapeutic effect on CD-like colitis. The colon organoids were induced by TNF-α to evaluate the direct role of Pm in inhibiting apoptosis of the intestinal epithelial cells. Western blotting and small molecule inhibitors were used to investigate further the potential mechanism of Pm in inhibiting apoptosis of intestinal epithelial cells.

RESULTS

Pm treatment reduced body weight loss, disease activity index (DAI) score, and inflammatory score, demonstrating that colonic inflammation in mice were alleviated. Pm decreased the intestinal epithelial apoptosis, improved the intestinal barrier function, and prevented the loss of tight junction proteins (ZO1 and claudin-1) in the colon of CD mice and TNF-α-induced colonic organoids. Pm activated Nrf2/HO1 signaling, which may protect intestinal barrier function.

CONCLUSIONS

Pm inhibits intestinal epithelial apoptosis in CD mice by activating Nrf2/HO1 pathway. This partially explains the potential mechanism of Pm in ameliorating intestinal barrier function in mice and provides a new approach to treating CD.

Perfluorooctanesulfonic acid exposure leads to downregulation of 3-hydroxy-3-methylglutaryl-CoA synthase 2 expression and upregulation of markers associated with intestinal carcinogenesis in mouse intestinal tissues

Perfluorooctanesulfonic acid (PFOS) is a widely recognized environment pollutant known for its high bioaccumulation potential and a long elimination half-life. Several studies have shown that PFOS can alter multiple biological pathways and negatively affect human health. Considering the direct exposure to the gastrointestinal (GI) tract to environmental pollutants, PFOS can potentially disrupt intestinal homeostasis. However, there is limited knowledge about the effect of PFOS exposure on normal intestinal tissues, and its contribution to GI-associated diseases remains to be determined. In this study, we examined the effect of PFOS exposure on the gene expression profile of intestinal tissues of C57BL/6 mice using RNAseq analysis. We found that PFOS exposure in drinking water significantly downregulates mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), a rate-limiting ketogenic enzyme, in intestinal tissues of mice. We found that diets containing the soluble fibers inulin and pectin, which are known to be protective against PFOS exposure, were ineffective in reversing the downregulation of HMGCS2 expression in vivo. Analysis of intestinal tissues also demonstrated that PFOS exposure leads to upregulation of proteins implicated in colorectal carcinogenesis, including β-catenin, c-MYC, mTOR and FASN. Consistent with the in vivo results, PFOS exposure leads to downregulation of HMGCS2 in mouse and human normal intestinal organoids in vitro. Furthermore, we show that shRNA-mediated knockdown of HMGCS2 in a human normal intestinal cell line resulted in increased cell proliferation and upregulation of key proliferation-associated proteins such as cyclin D, survivin, ERK1/2 and AKT, along with an increase in lipid accumulation. In summary, our results suggest that PFOS exposure may contribute to pathological changes in normal intestinal cells via downregulation of HMGCS2 expression and upregulation of pro-carcinogenic signaling pathways that may increase the risk of colorectal cancer development.

β-hydroxybutyrate restrains colitis-associated tumorigenesis by inhibiting HIF-1α-mediated angiogenesis

Decreased levels of β-hydroxybutyrate (BHB), a lipid metabolic intermediate known to slow the progression of colorectal cancer (CRC), have been observed in the colon mucosa of patients with inflammatory bowel diseases (IBD). In particular, patients with recurrent IBD present an increased risk of developing colitis-associated colorectal cancer (CAC). The role and molecular mechanism of BHB in the inflammatory and carcinogenic process of CAC remains unclear. Here, the anti-tumor effect of BHB was investigated in the Azoxymethane (AOM)/Dextran Sulfate Sodium (DSS)-induced CAC model and tumor organoids derivatives. The underlying mechanisms were studied using transcriptome and non-target metabolomic assay and further validated in colon tumor cell lineage CT26 in vitro. The tumor tissues and the nearby non-malignant tissues from colon cancer patients were collected to measure the expression levels of ketogenic enzymes. The exogenous BHB supplement lightened tumor burden and angiogenesis in the CAC model. Notably, transcriptome analysis revealed that BHB effectively decreased the expression of VEGFA in the CAC tumor mucosa. In vitro, BHB directly reduced VEGFA expression in hypoxic-treated CT26 cells by targeting transcriptional factor HIF-1α. Conversely, the deletion of HIF-1α largely reversed the inhibitory effect of BHB on CAC tumorigenesis. Additionally, decreased expression of ketogenesis-related enzymes in tumor tissues were associated with poor survival outcomes in patients with colon cancer. In summary, BHB carries out anti-angiogenic activity in CAC by regulating HIF-1α/VEGFA signaling. These findings emphasize the role of BHB in CAC and may provide novel perspectives for the prevention and treatment of colonic tumors.

Exploring the impacts of ketogenic diet on reversible hepatic steatosis: initial analysis in male mice

Metabolic dysfunction-associated fatty liver disease (MAFLD) is the most common chronic liver disease. Ketogenic diet (KD), a diet with very low intake in carbohydrates, gained popularity as a weight-loss approach. However, in mice models, it has been reported that an excess exposition of dietary fat induces hepatic insulin resistance and steatosis. However, data published is inconsistent. Herein, we investigated in a mouse model, the metabolic effects of KD and its contribution to the pathogenesis of NALFD. Mice were exposed to KD or CHOW diet for 12 weeks while a third group was exposed to KD for also 12 weeks and then switched to CHOW diet for 4 weeks to determine if we can rescue the phenotype. We evaluated the effects of diet treatments on fat distribution, glucose, and insulin homeostasis as well as hepatic steatosis. Mice fed with KD developed glucose intolerance but not insulin resistance accompanied by an increase of inflammation. KD-fed mice showed an increase of fat accumulation in white adipose tissue and liver. This effect could be explained by an increase in fat uptake by the liver with no changes of catabolism leading to MAFLD. Interestingly, we were able to rescue the phenotype by switching KD-fed mice for 4 weeks on a CHOW diet. Our studies demonstrate that even if mice develop hepatic steatosis and glucose intolerance after 12 weeks of KD, they do not develop insulin resistance and more importantly, the phenotype can be reversed by switching the mice from a KD to a CHOW.

Colonic ketogenesis, a microbiota-regulated process, contributes to blood ketones and protects against colitis in mice

Ketogenesis is considered to occur primarily in liver to generate ketones as an alternative energy source for non-hepatic tissues when glucose availability/utilization is impaired. 3-Hydroxy-3-methylglutaryl-CoA synthase-2 (HMGCS2) mediates the rate-limiting step in this mitochondrial pathway. Publicly available databases show marked down-regulation of HMGCS2 in colonic tissues in Crohn's disease and ulcerative colitis. This led us to investigate the expression and function of this pathway in colon and its relevance to colonic inflammation in mice. Hmgcs2 is expressed in cecum and colon. As global deletion of Hmgcs2 showed significant postnatal mortality, we used a conditional knockout mouse with enzyme deletion restricted to intestinal tract. These mice had no postnatal mortality. Fasting blood ketones were lower in these mice, indicating contribution of colonic ketogenesis to circulating ketones. There was also evidence of gut barrier breakdown and increased susceptibility to experimental colitis with associated elevated levels of IL-6, IL-1β, and TNF-α in circulation. Interestingly, many of these phenomena were mostly evident in male mice. Hmgcs2 expression in colon is controlled by colonic microbiota as evidenced from decreased expression in germ-free mice and antibiotic-treated conventional mice and from increased expression in a human colonic epithelial cell line upon treatment with aqueous extracts of cecal contents. Transcriptomic analysis of colonic epithelia from control mice and Hmgcs2-null mice indicated an essential role for colonic ketogenesis in the maintenance of optimal mitochondrial function, cholesterol homeostasis, and cell-cell tight-junction organization. These findings demonstrate a sex-dependent obligatory role for ketogenesis in protection against colonic inflammation in mice.

Ginseng-derived nanoparticles alleviate inflammatory bowel disease via the TLR4/MAPK and p62/Nrf2/Keap1 pathways

Inflammatory bowel disease (IBD) is closely linked to the homeostasis of the intestinal environment, and exosomes can be used to treat IBD due to their high biocompatibility and ability to be effectively absorbed by the intestinal tract. However, Ginseng-derived nanoparticles (GDNPs) have not been studied in this context and their mechanism of action remains unclear. Here, we investigated GDNPs ability to mediate intercellular communication in a complex inflammatory microenvironment in order to treat IBD. We found that GDNPs scavenge reactive oxygen species from immune cells and intestinal epithelial cells, inhibit the expression of pro-inflammatory factors, promote the proliferation and differentiation of intestinal stem cells, as well as enhancing the diversity of the intestinal flora. GDNPs significantly stabilise the intestinal barrier thereby promoting tissue repair. Overall, we proved that GDNPs can ameliorate inflammation and oxidative stress in vivo and in vitro, acting on the TLR4/MAPK and p62/Keap1/Nrf2 pathways, and exerting an anti-inflammatory and antioxidant effect. GDNPs mitigated IBD in mice by reducing inflammatory factors and improving the intestinal environment. This study offers new evidence of the potential therapeutic effects of GDNPs in the context of IBD, providing the conceptual ground for an alternative therapeutic strategy.

1,25(OH)2D3 alleviates oxidative stress and inflammation through up-regulating HMGCS2 in DSS-induced colitis

BACKGROUND

Previous study found that supplements with active vitamin D3 alleviated experimental colitis. The objective of this study was to investigate the possible role of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), a ketone synthase, on vitamin D3 protecting against experimental colitis.

METHODS

HMGCS2 and vitamin D receptor (VDR) were measured in UC patients. The effects of vitamin D deficiency (VDD) and exogenous 1,25(OH)2D3 supplementation on experimental colitis were investigated in dextran sulfate sodium (DSS)-treated mice. DSS-induced oxidative stress and inflammation were analyzed in HT-29 cells. HMGCS2 was detected in 1,25(OH)2D3-pretreated HT-29 cells and mouse intestines. HMGCS2 was silenced to investigate the role of HMGCS2 in 1,25(OH)2D3 protecting against experimental colitis.

RESULTS

Intestinal HMGCS2 downregulation was positively correlated with VDR reduction in UC patients. The in vivo experiments showed that VDD exacerbated DSS-induced colitis. By contrast, 1,25(OH)2D3 supplementation ameliorated DSS-induced colon damage, oxidative stress and inflammation. HMGCS2 was up-regulated after 1,25(OH)2D3 supplementation both in vivo and in vitro. Transfection with HMGCS2-siRNA inhibited antioxidant and anti-inflammatory effects of 1,25(OH)2D3 in DSS-treated HT-29 cells.

CONCLUSION

1,25(OH)2D3 supplementation up-regulates HMGCS2, which is responsible for 1,25(OH)2D3-mediated protection against oxidative stress and inflammation in DSS-induced colitis. These findings provide a potential therapeutic strategy for alleviating colitis-associated oxidative stress and inflammation.

Identifying Macrophage-Related Genes in Ulcerative Colitis Using Weighted Coexpression Network Analysis and Machine Learning

Ulcerative colitis (UC) is an inflammatory bowel disease of unknown cause that typically affects the colon and rectum. Innate intestinal immunity, including macrophages, plays a significant role in the pathological development of UC. Using the CIBERSORT algorithm, we observed elevated levels of 22 types of immune cell infiltrates, as well as increased M1 and decreased M2 macrophages in UC compared to normal colonic mucosa. Weighted gene coexpression network analysis (WGCNA) was used to identify modules associated with macrophages and UC, resulting in the identification of 52 macrophage-related genes (MRGs) that were enriched in macrophages at single-cell resolution. Consensus clustering based on these 52 MRGs divided the integrated UC cohorts into three subtypes. Machine learning algorithms were used to identify ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), sodium- and chloride-dependent neutral and basic amino acid transporter B(0+) (SLC6A14), and 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) in the training set, and their diagnostic value was validated in independent validation sets. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) revealed the main biological effects, and that interleukin-17 was one of several signaling pathways enriched by the three genes. We also constructed a competitive endogenous RNA (CeRNA) network reflecting a potential posttranscriptional regulatory mechanism. Expression of diagnostic markers was validated in vivo and in biospecimens, and our immunohistochemistry (IHC) results confirmed that HMGCS2 gradually decreased during the transformation of UC to colorectal cancer. In conclusion, ENPP1, SLC6A14, and HMGCS2 are associated with macrophages and the progression of UC pathogenesis and have good diagnostic value for patients with UC.

Mechanisms underlying the Effects of Heat Stress on Intestinal Integrity, Inflammation, and Microbiota in Chickens

Poultry meat and egg production benefits from a smaller carbon footprint, as well as feed and water consumption, per unit of product, than other protein sources. Therefore, maintaining a sustainable production of poultry meat is important to meet the increasing global demand for this staple. Heat stress experienced during the summer season or in tropical/subtropical areas negatively affects the productivity and health of chickens. Crucially, its impact is predicted to grow with the acceleration of global warming. Heat stress affects the physiology, metabolism, and immune response of chickens, causing electrolyte imbalance, oxidative stress, endocrine disorders, inflammation, and immunosuppression. These changes do not occur independently, pointing to a systemic mechanism. Recently, intestinal homeostasis has been identified as an important contributor to nutrient absorption and the progression of systemic inflammation. Its mechanism of action is thought to involve neuroendocrine signaling, antioxidant response, the presence of oxidants in the diet, and microbiota composition. The present review focuses on the effect of heat stress on intestinal dysfunction in chickens and the underlying causative factors. Understanding these mechanisms will direct the design of strategies to mitigate the negative effect of heat stress, while benefiting both animal health and sustainable poultry production.

Integrated Bioinformatics Analysis and Experimental Verification of Immune Cell Infiltration and the Related Core Genes in Ulcerative Colitis

Background

Ulcerative colitis is a recurrent autoimmune disease. At present, the pathogenesis of UC is not completely clear. Hence, the etiology and underlying molecular mechanism need to be further investigated.

Methods

Three sets of microarray datasets were included from the Gene Expression Omnibus database. The differentially expressed genes in two sets of datasets were analyzed using the R software, and the core genes of UC were screened using machine learning. The sensitivity and specificity of the core genes were evaluated with the receiver operating characteristic curve in another microarray dataset. Subsequently, the CIBERSORT tool was used to analyze the relationship between UC and its core genes and immune cell infiltration. To verify the relationship between UC and core genes and the relationship between core genes and immune cell infiltration in vivo.

Results

A total of 36 DEGs were identified. AQP8, HMGCS2, and VNN1 were determined to be the core genes of UC. These genes had high sensitivity and specificity in receiver operating characteristic curve analysis. According to the analysis of immune cell infiltration, neutrophils, monocytes, and macrophages were positively correlated with UC. AQP8, HMGCS2, and VNN1 were also correlated with immune cell infiltration to varying degrees. In vivo experiments verified that the expressions of neutrophils, monocytes, and macrophages increased in the UC colon. Furthermore, the expressions of AQP8 and HMGCS2 decreased, whereas that of VNN1 increased. Azathioprine treatment improved all the indicators to different degrees.

Conclusion

AQP8, HMGCS2, and VNN1 are the core genes of UC and exhibit different degrees of correlation with immune cells. These genes are expected to become new therapeutic targets for UC. Moreover, the occurrence and development of UC are influenced by immune cell infiltration.

Establishment of a lipopolysaccharide-induced inflammation model of human fetal colon cells

BACKGROUND

Inflammatory bowel disease (IBD) is a global health problem and there are few cell models for IBD at present. To culture a human fetal colon (FHC) cell line in vitro and establish an FHC cell inflammation model that meets the requirements for high expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α).

METHODS AND RESULTS

FHC cells were cultured with various concentrations of Escherichia coli lipopolysaccharide (LPS) in appropriate media for 0.5, 1, 2, 4, 8, 16 and 24 h to stimulate an inflammatory reaction. The viability of FHC cells was detected by a Cell Counting Kit-8 (CCK-8) assay. The transcriptional levels and protein expression changes of IL-6 and TNF-α in FHC cells were detected by Quantitative Real‑Time Polymerase Chain Reaction (qRT-PCR) and Enzyme‑Linked Immunosorbent Assay (ELISA), respectively. Appropriate stimulation conditions were selected (i.e., LPS concentration and treatment time), based on changes in cell survival rate, and IL-6 and TNF-α expression levels. An LPS concentration higher than 100 µg/mL or a treatment time longer than 24 h resulted in morphological changes and decreased cell survival. By contrast, expression levels of IL-6 and TNF-α significantly increased within 24 h when LPS concentration lower than 100 µg/mL and peaked at 2 h, whilst maintaining cell morphology and viability in FHC cells.

CONCLUSION

The treatment of FHC cells with 100 µg/mL LPS within 24 h was optimal in terms of stimulating IL-6 and TNF-α expression.

The Ketogenic Diet in Colorectal Cancer: A Means to an End

Some diets, such as high lipid and high glucose diets, are known to increase the risk of colorectal cancer. On the other hand, little is known about diets that prevent colonic carcinogenesis. The ketogenic diet, which is characterized by high fat and very low carbohydrate content, is one such diet. The ketogenic diet decreases the amount of available glucose for tumors and shifts to the production of ketone bodies as an alternative energy source for healthy cells. Cancer cells are unable to use the ketone bodies for energy thus depriving them of the energy needed for progression and survival. Many studies reported the beneficial effects of the ketogenic diet in several types of cancers. Recently, the ketone body β-hydroxybutyrate has been found to possess anti-tumor potential in colorectal cancer. Despite its beneficial effects, the ketogenic diet also has some drawbacks, some of which are related to gastrointestinal disorders and weight loss. Thus, studies are being directed at this time towards finding alternatives to following a strict ketogenic diet and supplementing patients with the ketone bodies responsible for its beneficial effects in the hope of overcoming some potential setbacks. This article discusses the mechanism by which a ketogenic diet influences growth and proliferation of tumor cells, it sheds the light on the most recent trials regarding its use as an adjunctive measure to chemotherapy in patients with metastatic colorectal cancer, and it explains the limitations of its usage in metastatic patients and the promising role of exogenous ketone supplementation in this setting.

Pediatric Crohn's disease diagnosis aid via genomic analysis and machine learning

Introduction

Determination of pediatric Crohn's disease (CD) remains a major diagnostic challenge. However, the rapidly emerging field of artificial intelligence has demonstrated promise in developing diagnostic models for intractable diseases.

Methods

We propose an artificial neural network model of 8 gene markers identified by 4 classification algorithms based on Gene Expression Omnibus database for diagnostic of pediatric CD.

Results

The model achieved over 85% accuracy and area under ROC curve value in both training set and testing set for diagnosing pediatric CD. Additionally, immune infiltration analysis was performed to address why these markers can be integrated to develop a diagnostic model.

Conclusion

This study supports further clinical facilitation of precise disease diagnosis by integrating genomics and machine learning algorithms in open-access database.

Revealing immune infiltrate characteristics and potential diagnostic value of immune-related genes in ulcerative colitis: An integrative genomic analysis

Objectives

Ulcerative colitis (UC) is an autoimmune disease of the colon. The aim of this study was to explore the characteristics of immune infiltrates in UC patients and identify immune-related diagnostic biomarkers for UC.

Methods

Three gene expression profiles were acquired from the GEO database, followed by identification of differentially expressed genes (DEGs) by Linear Modeling of Microarray Data. Enrichment analysis of Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Disease Ontology (DO) were performed to analyze the biological functions of DEGs. Subsequently, the single sample gene set enrichment analysis (ssGSEA) was performed to identify immune infiltration characteristics of UC. Correlations between diagnostic genes and immune infiltration were explored to identify markers with the greatest diagnostic potential, and a UC diagnostic model was subsequently constructed. Finally, the prediction performance of the model was quantified by nomogram, non-correlated nomogram, and ROC curve.

Results

A total of 3111 DEGs (1,608 up-regulated and 1,503 down-regulated genes) were identified. DEGs were significantly involved in the immune system and UC-related pathways. Immune infiltration profiles of colonic tissue were significantly different between healthy individuals and UC patients. High proportions of resting of aDCs, B cells, CD8⁺ T cells, DCs, iDCs, Macrophages, Neutrophils, pDCs, T helper cells, Tfh, Th1 cells, Th2 cells, TIL and Treg were found in UC samples. A 5-gene based diagnostic prediction model was constructed and the results of nomogram, non-correlated nomogram and ROC curve suggested the powerful diagnostic value of the model.

Conclusions

This study identified the immune infiltrate characteristics and 5 immune-related genes for UC. The model based on the immune-related genes facilitates the early diagnosis of UC and provides a basis for the evaluation of the prognosis of UC.

Artemisinin Alleviates Intestinal Inflammation and Metabolic Disturbance in Ulcerative Colitis Rats Induced by DSS

Objective

This study is aimed to reveal the possible mechanisms of artemisinin in the treatment of ulcerative colitis (UC) through bioinformatics analysis and experimental verification in UC model rats.

Methods

Firstly, we searched two microarray data of the Gene Expression Omnibus (GEO) database to explore the differentially expressed genes (DEGs) between UC samples and normal samples. Then, we selected DEGs for gene ontology (GO) function enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. The acute UC model of rats was established by using 3.5% dextran sulfate sodium (DSS) for 10 days to verify the core pathway. Finally, we evaluated the therapeutic effect of artemisinin at the molecular level and used metabonomics to study the endogenous metabolites in the rat serum.

Results

We screened in the GEO database and selected two eligible microarray datasets, GSE36807 and GSE9452. We performed GO function and KEGG pathway enrichment analyses of DEGs and found that these DEGs were mainly enriched in the inflammatory response, immune response, and IL-17 and NF-κB signaling pathways. Finally, we verified the IL-17 signaling pathway and key cytokines, and ELISA and immunohistochemical results showed that artemisinin could downregulate the expression of proinflammatory cytokines such as IL-1β and IL-17 in the IL-17 signaling pathway and upregulate the expression of the anti-inflammatory cytokine PPAR-γ. Metabolomics analysis showed that 33 differential metabolites were identified in the artemisinin group (AG) compared to the model group (MG). Differential metabolites were mainly involved in alanine, aspartate, and glutamate metabolism and synthesis and degradation of ketone bodies.

Conclusion

In this study, we found that artemisinin can significantly inhibit the inflammatory response in UC rats and regulate metabolites and related metabolic pathways. This study provides a foundation for further research on the mechanism of artemisinin in the treatment of UC.