A Novel Role of SLC26A3 in the Maintenance of Intestinal Epithelial Barrier Integrity

Exploring the therapeutic potential of Chinese herbs on comorbid type 2 diabetes mellitus and Parkinson's disease: A mechanistic study

ETHNOPHARMACOLOGICAL RELEVANCE

Type 2 diabetes mellitus (T2DM) and Parkinson's disease (PD) are chronic conditions that affect the aging population, with increasing prevalence globally. The rising prevalence of comorbidity between these conditions, driven by demographic shifts, severely impacts the quality of life of patients, posing a significant burden on healthcare resources. Chinese herbal medicine has been used to treat T2DM and PD for millennia. Pharmacological studies have demonstrated that medicinal herbs effectively lower blood glucose levels and exert neuroprotective effects, suggesting their potential as adjunctive therapy for concurrent management of T2DM and PD.

AIM OF THE STUDY

To elucidate the shared mechanisms underlying T2DM and PD, particularly focusing on the potential mechanisms by which medicinal herbs (including herbal formulas, single herbs, and active compounds) may treat these diseases, to provide valuable insights for developing therapeutics targeting comorbid T2DM and PD.

MATERIALS AND METHODS

Studies exploring the mechanisms underlying T2DM and PD, as well as the treatment of these conditions with medicinal herbs, were extracted from several electronic databases, including PubMed, Web of Science, Google Scholar, and China National Knowledge Infrastructure (CNKI).

RESULTS

Numerous studies have shown that inflammation, oxidative stress, insulin resistance, impaired autophagy, gut microbiota dysbiosis, and ferroptosis are shared mechanisms underlying T2DM and PD mediated through the NLRP3 inflammasome, NF-κB, MAPK, Keap1/Nrf2/ARE, PI3K/AKT, AMPK/SIRT1, and System XC--GSH-GPX4 signaling pathways. Thirty-four medicinal herbs, including 2 herbal formulas, 4 single herbs, and 28 active compounds, have been reported to potentially exert anti-T2DM and anti-PD effects by targeting these shared mechanisms.

CONCLUSIONS

Traditional Chinese medicine effectively combats T2DM and PD through shared pathological mechanisms, highlighting their potential for application in treating these comorbid conditions.

Intestinal Epithelial Tight Junction Barrier Regulation by Novel Pathways

Intestinal epithelial tight junctions (TJs), a dynamically regulated barrier structure composed of occludin and claudin family of proteins, mediate the interaction between the host and the external environment by allowing selective paracellular permeability between the luminal and serosal compartments of the intestine. TJs are highly dynamic structures and can undergo constant architectural remodeling in response to various external stimuli. This is mediated by an array of intracellular signaling pathways that alters TJ protein expression and localization. Dysfunctional regulation of TJ components compromising the barrier homeostasis is an important pathogenic factor for pathological conditions including inflammatory bowel disease (IBD). Previous studies have elucidated the significance of TJ barrier integrity and key regulatory mechanisms through various in vitro and in vivo models. In recent years, considerable efforts have been made to understand the crosstalk between various signaling pathways that regulate formation and disassembly of TJs. This review provides a comprehensive view on the novel mechanisms that regulate the TJ barrier and permeability. We discuss the latest evidence on how ion transport, cytoskeleton and extracellular matrix proteins, signaling pathways, and cell survival mechanism of autophagy regulate intestinal TJ barrier function. We also provide a perspective on the context-specific outcomes of the TJ barrier modulation. The knowledge on the diverse TJ barrier regulatory mechanisms will provide further insights on the relevance of the TJ barrier defects and potential target molecules/pathways for IBD.

GPA33 expression in colorectal cancer can be induced by WNT inhibition and targeted by cellular therapy

GPA33 is a promising surface antigen for targeted therapy in colorectal cancer (CRC). It is expressed almost exclusively in CRC and intestinal epithelia. However, previous clinical studies have not achieved expected response rates. We investigated GPA33 expression and regulation in CRC and developed a GPA33-targeted cellular therapy. We examined GPA33 expression in CRC cohorts using immunohistochemistry and immunofluorescence. We analyzed GPA33 regulation by interference with oncogenic signaling in vitro and in vivo using inhibitors and conditional inducible regulators. Furthermore, we engineered anti-GPA33-CAR T cells and assessed their activity in vitro and in vivo. GPA33 expression showed consistent intratumoral heterogeneity in CRC with antigen loss at the infiltrative tumor edge. This pattern was preserved at metastatic sites. GPA33-positive cells had a differentiated phenotype and low WNT activity. Low GPA33 expression levels were linked to tumor progression in patients with CRC. Downregulation of WNT activity induced GPA33 expression in vitro and in GPA33-negative tumor cell subpopulations in xenografts. GPA33-CAR T cells were activated in response to GPA33 and reduced xenograft growth in mice after intratumoral application. GPA33-targeted therapy may be improved by simultaneous WNT inhibition to enhance GPA33 expression. Furthermore, GPA33 is a promising target for cellular immunotherapy in CRC.

Escherichia coli Nissle Improves Short-Chain Fatty Acid Absorption and Barrier Function in a Mouse Model for Chronic Inflammatory Diarrhea

BACKGROUND

Defects in SLC26A3, the major colonic Cl-/HCO3- exchanger, result in chloride-rich diarrhea, a reduction in short-chain fatty acid (SCFA)-producing bacteria, and a high incidence of inflammatory bowel disease in humans and in mice. Slc26a3-/- mice are, therefore, an interesting animal model for spontaneous but mild colonic inflammation and for testing strategies to reverse or prevent the inflammation. This study investigates the effect of Escherichia coli Nissle (EcN) application on the microbiome, SCFA production, barrier integrity, and mucosal inflammation in slc26a3-/- mice.

METHODS

In vivo fluid absorption and bicarbonate secretion were assessed in the gut of slc26a3+/+ and slc26a3-/- mice before and during luminal perfusion with 100 mM sodium acetate. Age-matched slc26a3+/+ and slc26a3-/- mice were intragastrically gavaged twice daily with 2 × 108 CFU/100 µL of EcN for 21 days. Body weight and stool water content were assessed daily, and stool and tissues were collected for further analysis.

RESULTS

Addition of sodium acetate to the lumen of the proximal colon significantly increased fluid absorption and luminal alkalinization in the slc26a3-/- mice. Gavage with EcN resulted in a significant increase in SCFA levels and the expression of SCFA transporters in the slc26a3-/- cecum, the predominant habitat of EcN in mice. This was accompanied by an increase in mucus-producing goblet cells and a decrease in the expression of inflammatory markers as well as host defense antimicrobial peptides. EcN did not improve the overall diversity of the luminal microbiome but resulted in a significant increase in SCFA producers Lachnospiraceae and Ruminococcaceae in the slc26a3-/- feces.

CONCLUSIONS

These findings suggest that EcN is able to proliferate in the inflamed cecum, resulting in increased microbial SCFA production, decreased inflammation, and improved gut barrier properties. In sufficient dosage, probiotics may thus be an effective anti-inflammatory strategy in the diseased gut.

Exposure to toluene diisocyanate induces dysbiosis of gut-lung homeostasis: Involvement of gut microbiota

Toluene diisocyanate (TDI) is a major industrial compound that induces occupational asthma with steroid-resistant properties. Recent studies suggest that the gastrointestinal tract may be an effective target for the treatment of respiratory diseases. However, the alterations of the gut-lung axis in TDI-induced asthma remain unexplored. Therefore, in this study, a model of stable occupational asthma caused by TDI exposure was established to detect the alteration of the gut-lung axis. Exposure to TDI resulted in dysbiosis of the gut microbiome, with significant decreases in Barnesiella_intestinihominis, Faecalicoccus_pleomorphus, Lactobacillus_apodemi, and Lactobacillus_intestinalis, but increases in Alistipes_shahii and Odoribacter_laneus. The largest change in abundance was in Barnesiella_intestinihominis, which decreased from 12.14 per cent to 6.18 per cent. The histopathological abnormalities, including shorter length of intestinal villi, thinner thickness of muscularis, reduced number of goblet cells and inflammatory cell infiltration, were found in TDI-treated mice compared to control mice. In addition, increased permeability (evidenced by significantly reduced levels of ZO-1, Occludin and Claudin-1) and activation of TLR4/NF-κB signaling were observed in the intestine of these TDI-exposed mice. Concurrently, exposure to TDI resulted in airway hyperresponsiveness, overt cytokine production (e.g., IL-4, IL-5, IL-13, IL-25, and IL-33), and elevated IgE level within the respiratory tract. The expression of tight junction proteins is reduced and TLR4/NF-κB signaling is activated in the lung following TDI treatment. In addition, correlation analyses showed that changes in the gut microbiota were correlated with TDI exposure-induced airway inflammation. In conclusion, the present study suggests that the immune gut-lung axis may be involved in the development of TDI-induced asthma, which may have implications for potential interventions against steroid-resistant asthma.

Dexamethasone Upregulates the Expression of the Human SLC26A3 (DRA, Down-Regulated in Adenoma) Transporter (an IBD Susceptibility Gene) in Intestinal Epithelial Cells and Attenuates Gut Inflammation

BACKGROUND

Down-Regulated in Adenoma (DRA) plays a critical role in intestinal chloride absorption and a decrease in its expression is a key event in diarrheal disorders. Recently, DRA has emerged as an Inflammatory Bowel Disease (IBD) susceptibility gene. Therefore, the strategies to upregulate DRA expression are potentially novel approaches to not only treat IBD-associated diarrhea but also gut inflammation. In this study, the effect of dexamethasone (DEX), an anti-inflammatory corticosteroid on DRA expression was investigated.

METHODS

GR (glucocorticoid receptor) overexpressed Caco-2 cells and C57BL/6/J mice and anti-αIL-10R mAb model of IBD were used. Protein expression was assessed by immunoblotting and immunofluorescence. Transcript levels were assessed by quantative-real-time polymerase chain reaction (qRT-PCR) and promoter activity was measured by luciferase assays.

RESULTS

Our results showed that DEX significantly increased DRA mRNA and protein expression in GR overexpressing Caco-2 cells. DEX-induced upregulation of DRA was GR dependent and appeared at least in part to occur via a transcriptional mechanism, as promoter activity of the DRA construct (-1183/+114 bp) was significantly increased in response to DEX. The increase in DRA mRNA was abrogated in the presence of MKP-1 inhibitor, triptolide. Administration of DEX (2 mg/kg body weight) to mice for 24 and 48 hours significantly increased the DRA expression in mouse colon. DEX treatment to mice for 7 days in the αIL-10R mAb model of colitis was able to significantly attenuate the gut inflammation and associated decrease in DRA expression.

CONCLUSIONS

We demonstrate that DEX stimulates DRA expression via transcriptional mechanisms and suggest that upregulation of DRA may contribute to both anti-inflammatory and pro-absorptive effects of DEX.

RNA-Seq transcriptome profiling of Nile rat livers reveals novel insights on the anti-diabetic mechanisms of Water-Soluble Palm Fruit Extract

Water-Soluble Palm Fruit Extract (WSPFE) has been shown to confer anti-diabetic effects in the Nile rat (NR) (Arvicanthis niloticus). Liquid and powder WSPFE both deterred diabetes onset in NRs fed a high-carbohydrate (hiCHO) diet, but the liquid form provided better protection. In this study, NRs were fed either a hiCHO diet or the same diet added with liquid or powder WSPFE. Following feeding of the diets for 8 weeks, random blood glucose levels were measured to categorize NRs as either diabetes-resistant or diabetes-susceptible, based on a cut-off value of 75 mg/dL. Livers were then obtained for Illumina HiSeq 4000 paired end RNA-sequencing (RNA-Seq) and the data were mapped to the reference genome. Consistent with physiological and biochemical parameters, the gene expression data obtained indicated that WSPFE was associated with protection against diabetes. Among hepatic genes upregulated by WSPFE versus controls, were genes related to insulin-like growth factor binding protein, leptin receptor, and processes of hepatic metabolism maintenance, while those downregulated were related to antigen binding, immunoglobulin receptor, inflammation- and cancer-related processes. WSPFE supplementation thus helped inhibit diabetes progression in NRs by increasing insulin sensitivity and reducing both the inflammatory effects of a hiCHO diet and the related DNA-damage compensatory mechanisms contributing to liver disease progression. In addition, the genetic permissiveness of susceptible NRs to develop diabetes was potentially associated with dysregulated compensatory mechanisms involving insulin signaling and oxidative stress over time. Further studies on other NR organs associated with diabetes and its complications are warranted.

Butyrate Inhibits the HDAC8/NF-κB Pathway to Enhance Slc26a3 Expression and Improve the Intestinal Epithelial Barrier to Relieve Colitis

Dietary fiber is known to promote the production of short-chain fatty acids (SCFAs) by gut bacteria, which can enhance intestinal epithelial barrier function and ameliorate intestinal inflammation in patients with inflammatory bowel disease (IBD). Interestingly, some IBD patients show reduced expression of solute carrier family member 3 (Slc26a3) in intestinal epithelial cells. The objective of this research was to investigate the interaction between SCFAs and Slc26a3 during colitis and assess how this interaction affects intestinal epithelial barrier function. We showed that butyrate alleviated colonic inflammation in a dose-dependent manner in a dextran sulfate sodium salt (DSS)-induced colitis model. Consistent with this, butyrate increased Slc26a3 and tight junction protein levels. In addition, butyrate inhibited histone deacetylase (HDAC) levels and significantly increased the expression of Slc26a3 by the acetylation of histones in Caco-2BBe cells. The utilization of a pan-HDAC inhibitor or inhibitors specific to certain classes of HDACs revealed that butyrate primarily suppressed HDAC8 to blunt the NF-κB pathways and enhance the expression of Slc26a3. Notably, we demonstrated that HDAC8 activation counteracted the beneficial effect of butyrate in DSS-induced colitis. Therefore, we concluded that butyrate improves the expression of Slc26a3 via inhibition of the HDAC8/NF-κB pathway, leading to increased intestinal epithelial barrier function.

ROS/pH dual-responsive quercetin-loaded guanosine borate supramolecular hydrogel enema in dextran sulfate sodium-induced colitis in mice

Ulcerative colitis (UC) is an inflammatory bowel disease that predominantly impacts the colon, typically starting in the rectum. A significant characteristic of UC is its propensity to affect the distal colon, which is particularly beneficial for targeted treatments such as enemas. This localized approach ensures that the medication is delivered directly to the affected areas, resulting in minimal systemic absorption. In this research, we have formulated a novel stimuli-responsive quercetin-loaded guanosine borate supramolecular hydrogel (named GBQ hydrogel), designed to prolong the residence time of the drug and protect the ulcerated intestinal tissues. The GBQ hydrogel has exhibited excellent injectability, self-healing capabilities, and biocompatibility, rendering it an ideal candidate for enema administration. In vitro studies have highlighted its ROS/pH dual-responsive release profile, which mimics the microenvironment of intestinal inflammation. Furthermore, we assessed the efficacy of the GBQ hydrogel on dextran sulfate sodium (DSS)-induced colitis, a common animal model for UC. Our findings indicate that the GBQ hydrogel significantly reduces disease activity, mitigates oxidative stress, restores the intestinal mucosal barrier, and prevents colonic cell apoptosis. Collectively, this study underscores the therapeutic potential of the GBQ hydrogel in managing inflammatory bowel conditions and paves the way for a novel hydrogel enema-based treatment strategy for UC.

Jianpi-Huatan-Huoxue-Anshen formula ameliorates gastrointestinal inflammation and microecological imbalance in chemotherapy-treated mice transplanted with H22 hepatocellular carcinoma

BACKGROUND

Jianpi-Huatan-Huoxue-Anshen formula [Tzu-Chi cancer-antagonizing & life-protecting II decoction (TCCL)] is a Chinese medical formula that has been clinically shown to reduce the gastrointestinal side effects of chemotherapy in cancer patients and improve their quality of life. However, its effect and mechanism on the intestinal microecology after chemotherapy are not yet clear.

AIM

To discover the potential mechanisms of TCCL on gastrointestinal inflammation and microecological imbalance in chemotherapy-treated mice transplanted with hepatocellular carcinoma (HCC).

METHODS

Ninety-six mice were inoculated subcutaneously with HCC cells. One week later, the mice received a large dose of 5-fluorouracil by intraperitoneal injection to establish a HCC chemotherapy model. Thirty-six mice were randomly selected before administration, and feces, ileal tissue, and ileal contents were collected from each mouse. The remaining mice were randomized into normal saline, continuous chemotherapy, Yangzheng Xiaoji capsules-treated, and three TCCL-treated groups. After treatment, feces, tumors, liver, spleen, thymus, stomach, jejunum, ileum, and colon tissues, and ileal contents were collected. Morphological changes, serum levels of IL-1β, IL-6, IL-8, IL-10, IL-22, TNF-α, and TGF-β, intestinal SIgA, and protein and mRNA expression of ZO-1, NF-κB, Occludin, MUC-2, Claudin-1, and IκB-α in colon tissues were documented. The effect of TCCL on the abundance and diversity of intestinal flora was analyzed using 16S rDNA sequencing.

RESULTS

TCCL treatment improved thymus and spleen weight, thymus and spleen indexes, and body weight, decreased tumor volumes and tumor tissue cell density, and alleviated injury to gastric, ileal, and colonic mucosal tissues. Among proteins and genes associated with inflammation, IL-10, TGF-β, SIgA, ZO-1, MUC-2, and Occludin were upregulated, whereas NF-κB, IL-1β, IL-6, TNF-α, IL-22, IL-8, and IκB-α were downregulated. Additionally, TCCL increased the proportions of fecal Actinobacteria, AF12, Adlercreutzia, Clostridium, Coriobacteriaceae, and Paraprevotella in the intermediate stage of treatment, decreased the proportions of Mucipirillum, Odoribacter, RF32, YS2, and Rikenellaceae but increased the proportions of p_Deferribacteres and Lactobacillus at the end of treatment. Studies on ileal mucosal microbiota showed similar findings. Moreover, TCCL improved community richness, evenness, and the diversity of fecal and ileal mucosal flora.

CONCLUSION

TCCL relieves pathological changes in tumor tissue and chemotherapy-induced gastrointestinal injury, potentially by reducing the release of pro-inflammatory factors to repair the gastrointestinal mucosa, enhancing intestinal barrier function, and maintaining gastrointestinal microecological balance. Hence, TCCL is a very effective adjuvant to chemotherapy.

Ion Transport Basis of Diarrhea, Paneth Cell Metaplasia, and Upregulation of Mechanosensory Pathway in Anti-CD40 Colitis Mice

BACKGROUND

Anti-Cluster of differentiation (CD)-40-induced colitis, driven by innate inflammatory responses in the intestine, is a potent animal model exhibiting IBD pathophysiology including diarrhea. However, the ion transport basis of diarrhea and some key mucosal pathways (Paneth cells, stem cell niche, and mechanosensory) in this model have not been investigated.

METHODS

Mucosal scrapings and intestinal tissue from control and CD40 antibody (150 µg) treated Rag2-/- mice were examined for gut inflammation, Paneth cell numbers, expression of key transporters, tight/adherens junction proteins, stem cell niche, and mechanosensory pathway via hematoxylin and eosin staining, quantitative polymerase chain reaction, and western blotting.

RESULTS

Compared with control, anti-CD40 antibody treatment resulted in a significant loss of body weight (P < .05) and diarrhea at day 3 postinjection. Distal colonic tissues of anti-CD40 mice exhibited increased inflammatory infiltrates, higher claudin-2 expression, and appearance of Paneth cell-like structures indicative of Paneth cell metaplasia. Significantly reduced expression (P < .005) of downregulated in adenoma (key Cl- transporter), P-glycoprotein/multidrug resistantance-1 (MDR1, xenobiotic transporter), and adherens junction protein E-cadherin (~2-fold P < .05) was also observed in the colon of anti-CD40 colitis mice. Interestingly, there were also marked alterations in the stem cell markers and upregulation of the mechanosensory YAP-TAZ pathway, suggesting the activation of alternate regeneration pathway post-tissue injury in this model.

CONCLUSION

Our data demonstrate that the anti-CD40 colitis model shows key features of IBD observed in the human disease, hence making it a suitable model to investigate the pathophysiology of ulcerative colitis (UC).

A Direct Link Implicating Loss of SLC26A6 to Gut Microbial Dysbiosis, Compromised Barrier Integrity, and Inflammation

BACKGROUND & AIMS

Putative anion transporter-1 (PAT1, SLC26A6) plays a key role in intestinal oxalate and bicarbonate secretion. PAT1 knockout (PKO) mice exhibit hyperoxaluria and nephrolithiasis. Notably, diseases such as inflammatory bowel disease are also associated with higher risk of hyperoxaluria and nephrolithiasis. However, the potential role of PAT1 deficiency in gut-barrier integrity and susceptibility to colitis is currently elusive.

METHODS

Age-matched PKO and wild-type littermates were administered 3.5% dextran sulfate sodium in drinking water for 6 days. Ileum and colon of control and treated mice were harvested. Messenger RNA and protein expression of tight junction proteins were determined by reverse transcription polymerase chain reaction and western blotting. Severity of inflammation was assessed by measuring diarrheal phenotype, cytokine expression, and hematoxylin and eosin staining. Gut microbiome and associated metabolome were analyzed by 16S ribosomal RNA sequencing and mass spectrometry, respectively.

RESULTS

PKO mice exhibited significantly higher loss of body weight, gut permeability, colonic inflammation, and diarrhea in response to dextran sulfate sodium treatment. In addition, PKO mice showed microbial dysbiosis and significantly reduced levels of butyrate and butyrate-producing microbes compared with controls. Co-housing wild-type and PKO mice for 4 weeks resulted in PKO-like signatures on the expression of tight junction proteins in the colons of wild-type mice.

CONCLUSIONS

Our data demonstrate that loss of PAT1 disrupts gut microbiome and related metabolites, decreases gut-barrier integrity, and increases host susceptibility to intestinal inflammation. These findings, thus, highlight a novel role of the oxalate transporter PAT1 in promoting gut-barrier integrity, and its deficiency appears to contribute to the pathogenesis of inflammatory bowel diseases.

Duodenal transcriptomics demonstrates signatures of tissue inflammation and immune cell infiltration in children with environmental enteric dysfunction across global centers

BACKGROUND

Environmental enteric dysfunction (EED) is an inflammatory condition of the small intestine that is prevalent in children residing in low- and middle-income countries. EED is accompanied by profound histopathologic changes in the small bowel, loss of absorptive capacity, increased intestinal permeability, increased microbial translocation, and nutrient loss.

OBJECTIVES

We sought to identify dysregulated genes and pathways that might underlie pediatric EED.

METHODS

RNA-sequencing libraries were generated from endoscopically obtained duodenal tissue from undernourished children with EED from 3 prospective cohorts of children with EED. The EED transcriptome was defined in comparison to North American children without EED. Weighted gene coexpression network analysis (WGCNA) was tested for gene modules associated with EED and its histologic features.

RESULTS

The 1784 upregulated genes in EED were highly enriched for immune and inflammatory processes, including IL-17 and JAK-STAT signaling, and cytokine-cytokine receptor interactions. The 1388 downregulated genes included genes corresponding to xenobiotic metabolism, detoxification, and antioxidant capacities. A gene coexpression module enriched for antimicrobial responses and chemokine activity was significantly associated with villous blunting, goblet cell depletion, and overall histologic severity of EED.

CONCLUSIONS

The transcriptome signatures of EED include specific innate and adaptive immune responses that are consistently elevated across study centers, coupled with reduced detoxification and antioxidant capacities. These data may have implications for targeted interventions to improve EED outcomes.

Ganoderic Acid A Mitigates Inflammatory Bowel Disease through Modulation of AhR Activity by Microbial Tryptophan Metabolism

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a complex gastrointestinal condition influenced by genetic, microbial, and environmental factors, among which the gut microbiota plays a crucial role and has emerged as a potential therapeutic target. Ganoderic acid A (GAA), which is a lanostane triterpenoid compound derived from edible mushroom Ganoderma lucidum, has demonstrated the ability to modulate gut dysbiosis. Thus, we investigated the impact of GAA on IBD using a dextran sodium sulfate (DSS)-induced colitis mouse model. GAA effectively prevented colitis, preserved epithelial and mucus layer integrity, and modulated the gut microbiota. In addition, GAA promoted tryptophan metabolism, especially 3-IAld generation, activated the aryl hydrocarbon receptor (AhR), and induced IL-22 production. Fecal microbiota transplantation validated the mediating role of the gut microbiota in the IBD protection conferred by GAA. Our study suggests that GAA holds potential as a nutritional intervention for ameliorating IBD by influencing the gut microbiota, thereby regulating tryptophan metabolism, enhancing AhR activity, and ultimately improving gut barrier function.

Gut Dysbiosis Drives Inflammatory Bowel Disease Through the CCL4L2-VSIR Axis in Glycogen Storage Disease

Patients with glycogen storage disease type Ib (GSD-Ib) frequently have inflammatory bowel disease (IBD). however, the underlying etiology remains unclear. Herein, this study finds that digestive symptoms are commonly observed in patients with GSD-Ib, presenting as single or multiple scattered deep round ulcers, inflammatory pseudo-polyps, obstructions, and strictures, which differ substantially from those in typical IBD. Distinct microbiota profiling and single-cell clustering of colonic mucosae in patients with GSD are conducted. Heterogeneous oral pathogenic enteric outgrowth induced by GSD is a potent inducer of gut microbiota immaturity and colonic macrophage accumulation. Specifically, a unique population of macrophages with high CCL4L2 expression is identified in response to pathogenic bacteria in the intestine. Hyper-activation of the CCL4L2-VSIR axis leads to increased expression of AGR2 and ZG16 in epithelial cells, which mediates the unique progression of IBD in GSD-Ib. Collectively, the microbiota-driven pathomechanism of IBD is demonstrated in GSD-Ib and revealed the active role of the CCL4L2-VSIR axis in the interaction between the microbiota and colonic mucosal immunity. Thus, targeting gut dysbiosis and/or the CCL4L2-VISR axis may represent a potential therapy for GSD-associated IBD.

Enhancing gut barrier integrity: Upregulation of tight junction proteins by chitosan oligosaccharide through the ERK1/2 signaling pathway

OBJECTIVES

This study aimed to explore the protective mechanism of chitosan oligosaccharide (COS) against lipopolysaccharide (LPS)-induced inflammatory responses in IEC-6 cells and dextran sodium sulfate (DSS)-induced colitis in mice.

METHODS

The cell inflammation model was constructed by LPS in vitro and enteritis model by DSS in vivo.

RESULTS

Following LPS exposure, IEC-6 cell proliferation significantly decreased, epithelial cell integrity was compromised, and TNF-α and IL-1β levels were increased. However, COS pretreatment reversed these changes. In vivo, DSS-treated mice exhibited evident pathological alterations, including heightened inflammatory levels and significantly decreased expression of tight junction proteins and critical proteins in the Mitogen activated proteins kinase signaling pathway. Nevertheless, COS administration notably reduced inflammatory levels and increased the expression of tight junction proteins and key proteins in the Mitogen activated proteins kinase signaling pathway.

CONCLUSIONS

Our findings suggest that COS safeguards gut barrier integrity by upregulating tight junction proteins through the ERK1/2 signaling pathway. Therefore, COS has emerged as a promising candidate for novel drug interventions against inflammatory bowel disease.

Enzyme/ROS dual-sensitive nanoplatform with on-demand Celastrol release capacity for enhanced ulcerative colitis therapy by ROS scavenging, microbiota rebalancing, inflammation alleviating

BACKGROUND

The oral administration of drugs for treating ulcerative colitis (UC) is hindered by several factors, including inadequate gastrointestinal stability, insufficient accumulation in colonic lesions, and uncontrolled drug release.

METHODS

A multiple sensitive nano-delivery system comprising β-cyclodextrin (CD) and 4-(hydroxymethyl)phenylboronic acid (PAPE) with enzyme/reactive oxygen species (ROS) sensitivity was developed to load celastrol (Cel) as a comprehensive treatment for UC.

RESULTS

Owing to the positive charge in the site of inflamed colonic mucosa, the negatively charged nanomedicine (Cel/NPs) could efficiently accumulate. Expectedly, Cel/NPs showed excellent localization ability to colon in vitro and in vivo tests. The elevated concentration of ROS and intestinal enzymes in the colon microenvironment quickly break the CD, resulting in Cel release partially to rebalance microbiota and recover the intestinal barrier. The accompanying cellular internalization of residual Cel/NPs, along with the high concentration of cellular ROS to trigger Cel burst release, could decrease the expression of inflammatory cytokines, inhibit colonic cell apoptosis, promote the macrophage polarization, scavenge ROS, and regulate the TLR4/NF-κB signaling pathway, which certified that Cel/NPs possessed a notably anti-UC therapy outcome.

CONCLUSIONS

We provide a promising strategy for addressing UC symptoms via an enzyme/ROS-sensitive oral platform capable of releasing drugs on demand.

Protective effects of patchouli alcohol against DSS-induced ulcerative colitis

Patchouli alcohol (PA) is a widely used pharmaceutical ingredient in various Chinese traditional herbal medicine (THM) formulations, known for its modulatory effects on the gut microbiota. The present study investigated PA's anti-inflammatory and regulatory effects on gut microbiota and its mode of action (MOA). Based on the assessments of ulcerative colitis (UC) symptoms, PA exhibited promising preventions against inflammatory response. In accordance, the expressions of pro-inflammatory factors, including interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and chemokine ligand 5 were significantly attenuated under PA treatment. Furthermore, PA enhanced the intestinal barrier damage caused by dextran sodium sulfate (DSS). Interestingly, PA exhibited negligible inventions on DSS-induced gut microbiota dysbiosis. PA did not affect the diversity of the DSS gut microbiota, it did alter the composition, as evidenced by a significant increase in the Firmicutes-Bacteroidetes (F/B) ratio. Finally, the MOA of PA against inflammation in DSS-treated mice was addressed by suppressing the expressions of heme oxygenase-1 (HO-1) and inducible nitric oxide synthase (iNOS). In conclusion, PA prevented inflammatory response in the DSS-induced UC mice model via directly suppressing HO-1 and iNOS-associated antioxidant signal pathways, independent of its effects on gut microbiota composition.

Breaking Down Barriers: Epithelial Contributors to Monogenic IBD Pathogenesis

Monogenic causes of inflammatory bowel diseases (IBD) are increasingly being discovered. To date, much attention has been placed in those resulting from inborn errors of immunity. Therapeutic efforts have been largely focused on offering personalized immune modulation or curative bone marrow transplant for patients with IBD and underlying immune disorders. To date, less emphasis has been placed on monogenic causes of IBD that pertain to impairment of the intestinal epithelial barrier. Here, we provide a comprehensive review of monogenic causes of IBD that result in impaired intestinal epithelial barrier that are categorized into 6 important functions: (1) epithelial cell organization, (2) epithelial cell intrinsic functions, (3) epithelial cell apoptosis and necroptosis, (4) complement activation, (5) epithelial cell signaling, and (6) control of RNA degradation products. We illustrate how impairment of any of these categories can result in IBD. This work reviews the current understanding of the genes involved in maintaining the intestinal barrier, the inheritance patterns that result in dysfunction, features of IBD resulting from these disorders, and pertinent translational work in this field.

Mechanism of Nicotiflorin in San-Ye-Qing rhizome for anti-inflammatory effect in ulcerative colitis

BACKGROUND

The incidence of ulcerative colitis (UC) is on the rise globally and the development of drugs targeting UC is urgent. Finding the target of action of natural products is important for drug discovery, elucidation of drug action mechanism, and disease mechanism. San-Ye-Qing (SYQ), is an ancient herbal medicine, but whether the powder of its rhizome has pharmacological effects against UC and its mechanism of action are not clear.

PURPOSE

To evaluate the therapeutic effectiveness of rhizome powder of SYQ in treating UC, and conduct an isolation and characterization of the chemical constituents of the powder. Further, screen the most potent compounds among them and determine the potential mechanism for treating UC.

METHODS

In vivo, the therapeutic effect of SYQ's rhizome powder on UC was assessed by mice's body weight, DAI score, colon length, tissue MPO activity, serum inflammatory markers, etc. Additionally, HPLC was used to isolate and identify the specific chemical components of SYQ's rhizome powder. Then, the most effective compounds and their therapeutic targets were analysed and screened in SYQ rhizome powder using network pharmacology, combined with CCK-8 assay, NO release assay and molecular docking assay, in conjunction with CETSA, DARTS, SPR and enzyme activity assay. Finally, the biological effects of the key compound on the targets were validated using Western blot and ELISA.

RESULTS

In vivo, SYQ rhizome powder effectively restored mice's body weight, lowered DAI and pathological score, downregulated the expression of inflammatory biomarkers, and restored colon length, as well as the colonic epithelial and mucus barriers. Afterward, 9 compounds were isolated and identified from the powder of the rhizomes of SYQ by HPLC. Nicotiflorin is the primary compound in SYQ with the highest concentration. According to both CCK-8 and NO release tests, Nicotiflorin is also the most efficacious compound. Combined with network pharmacological prediction, molecular docking analysis, CETSA, DARTS, SPR and enzyme activity assay, Nicotiflorin may ultimately suppress inflammation by targeting p65 and inhibiting the NF-κB pathway, thereby attenuating the activation of NLRP3 inflammasome. To verify this conclusion, Western blot and ELISA experiments were conducted.

CONCLUSIONS

Our results suggest that the extract from SYQ rhizomes has therapeutic properties for UC. Its active ingredient Nicotiflorin exerted potent anti-UC effects by binding to p65 and inhibiting the activation of NF-κB and NLRP3 inflammasomes.

Myeloid-derived growth factor ameliorates dextran sodium sulfate-induced colitis by regulating macrophage polarization

Inflammatory bowel disease (IBD) is characterized by inflammatory conditions in the gastrointestinal tract. According to reports, IBD prevalence is increasing globally, with heavy economic and physical burdens. Current IBD clinical treatment is limited to pharmacological methods; therefore, new strategies are needed. Myeloid-derived growth factor (MYDGF) secreted by bone marrow-derived mononuclear macrophages has beneficial effects in multiple inflammatory diseases. To this end, the present study aimed to establish an experimental IBD mouse model using dextran sulfate sodium in drinking water. MYDGF significantly alleviated DSS-induced colitis, suppressed lymphocyte infiltration, restored epithelial integrity in mice, and decreased apoptosis in the colon tissue. Moreover, the number of M1 macrophages was decreased and that of M2 macrophages was increased by the action of MYDGF. In MYDGF-treated mice, the NF-κB and MAPK pathways were partially inhibited. Our findings indicate that MYDGF could mitigate DSS-induced mice IBD by reducing inflammation and restoring epithelial integrity through regulation of intestinal macrophage polarization via NF-κB and MAPK pathway inhibition. KEY MESSAGES: MYDGF alleviated DSS-induced acute colitis. MYDGF maintains colon epithelial barrier integrity and relieves inflammation. MYDGF regulates colon macrophage polarization. MYDGF partially inhibited the activation of NF-κB and MAPK pathway.

Magnolin inhibits intestinal epithelial cell apoptosis alleviating Crohn's disease-like colitis by suppressing the PI3K/AKT signalling pathway

BACKGROUND AND AIMS

Previous reports have shown that preventing excessive intestinal epithelial cell (IEC) apoptosis is a crucial approach for protecting the intestinal barrier in patients with Crohn's disease (CD). Magnolin (MGL) has various biological activities, including antiapoptotic activities, but its role in CD has largely not been determined. This study investigated how MGL impacts CD-like colitis and the underlying mechanism involved.

METHODS

Mice were treated with TNBS to establish a disease model, and these mice were used to assess the therapeutic effects of MGL on CD-like colitis. TNF-α-treated colon organoids were used to evaluate the impact of MGL on intestinal barrier function and IEC apoptosis. Enrichment analysis was performed to examine the potential pathways through which MGL inhibits IEC apoptosis. Finally, rescue experiments showed the mechanism by which MGL suppresses IEC apoptosis.

RESULTS

The animal experiments demonstrated that MGL treatment alleviated the weight loss, colon shortening, elevated disease activity index (DAI) scores, increased colitis histological scores and upregulated inflammatory factor expression that were observed in model mice. MGL ameliorated intestinal barrier dysfunction and the loss of tight junction (TJ) proteins (ZO-1 and Claudin-1) by inhibiting IEC apoptosis in both TNBS-treated mice and TNF-α-treated colon organoids. MGL inhibited the PI3K/AKT signalling pathway, thus safeguarding the intestinal barrier and alleviating CD-like colitis in vivo and in vitro.

CONCLUSIONS

MGL improves the intestinal barrier integrity and prevents CD-like colitis by inhibiting IEC apoptosis. The potential mechanism of its anti-apoptotic impact on IECs could be associated with the PI3K/AKT pathway, presenting novel approaches and avenues for the clinical management of CD.

Shifts in uterine microbiome associated with pregnancy outcomes at first insemination and clinical cure in dairy cows with metritis

Objectives were to assess differences in uterine microbiome associated with clinical cure and pregnancy outcomes in dairy cows treated for metritis. Cows with metritis (reddish-brownish, watery, and fetid vaginal discharge) were paired with cows without metritis based on parity and days postpartum. Uterine contents were collected through transcervical lavage at diagnosis, five days later following antimicrobial therapy (day 5), and at 40 days postpartum. Uterine microbiome was assessed by sequencing the V4 hypervariable region of the 16S rRNA gene. Although alpha-diversity based on Chao1, Shannon, and inverse Simpson indexes at diagnosis did not differ between cows with and without metritis, disease was associated with differences in beta-diversity. Prevalence of Porphyromonas, Bacteroides, and Veillonella was greater in cows with metritis. Streptococcus, Sphingomonas, and Ureaplasma were more prevalent in cows without metritis. Differences in beta-diversity between cows with and without metritis persisted on day 5. Uterine microbiome was not associated with clinical cure. Richness and alpha-diversity, but not beta-diversity, of uterine microbiome 40 days postpartum were associated with metritis and pregnancy. No relationship between uterine microbiome and pregnancy outcomes was observed. Results indicate that factors other than changes in intrauterine bacterial community underlie fertility loss and clinical cure in cows with metritis.

Blockade of PI3K/AKT signaling pathway by Astragaloside IV attenuates ulcerative colitis via improving the intestinal epithelial barrier

BACKGROUND

The specific pathogenesis of UC is still unclear, but it has been clear that defects in intestinal barrier function play an important role in it. There is a temporary lack of specific drugs for clinical treatment. Astragaloside IV (AS-IV) is one of the main active ingredients extracted from Astragalus root and is a common Chinese herbal medicine for the treatment of gastrointestinal diseases. This study aimed to determine whether AS-IV has therapeutic value for DSS or LPS-induced intestinal epithelial barrier dysfunction in vivo and in vitro and its potential molecular mechanisms.

METHODS

The intestinal tissues from UC patients and colitis mice were collected, intestinal inflammation was observed by colonoscopy, and mucosal barrier function was measured by immunofluorescence staining. PI3K/AKT signaling pathway activator YS-49 and inhibitor LY-29 were administered to colitic mice to uncover the effect of this pathway on gut mucosal barrier modulation. Then, network pharmacology was used to screen Astragaloside IV (AS-IV), a core active component of the traditional Chinese medicine Astragalus membranaceus. The potential of AS-IV for intestinal barrier function repairment and UC treatment through blockade of the PI3K/AKT pathway was further confirmed by histopathological staining, FITC-dextran, transmission electron microscopy, ELISA, immunofluorescence, qRT-PCR, and western blotting. Finally, 16 S rRNA sequencing was performed to uncover whether AS-IV can ameliorate UC by regulating gut microbiota homeostasis.

RESULTS

Mucosal barrier function was significantly damaged in UC patients and murine colitis, and the activated PI3K/AKT signaling pathway was extensively involved. Both in vivo and vitro showed that the AS-IV-treated group significantly relieved inflammation and improved intestinal epithelial permeability by inhibiting the activation of the PI3K/AKT signaling pathway. In addition, microbiome data found that gut microbiota participates in AS-IV-mediated intestinal barrier recovery as well.

CONCLUSIONS

Our study highlights that AS-IV exerts a protective effect on the integrality of the mucosal barrier in UC based on the PI3K/AKT pathway, and AS-IV may serve as a novel AKT inhibitor to provide a potential therapy for UC.

hUC-MSCs therapy for Crohn's disease: efficacy in TNBS-induced colitis in rats and pilot clinical study

BACKGROUND

The use of mesenchymal stem cells (MSCs) has recently emerged as a promising new therapeutic strategy for many diseases including perianal fistulizing Crohn's disease (CD). Whether hUC-MSCs can promote the healing of luminal ulcer in CD has not been studied so far.

METHODS

The model of TNBS-induced colitis in rats was used to confirm the efficacy of hUC-MSCs in the treatment of CD. Then, seventeen CD patients refractory to or unsuitable for currently available therapies were enrolled and received once submucosal local injection through colonoscopy combined with once intravenous drip on the next day. All patients received a 24-week follow-up. Clinical and laboratory assessments were monitored at baseline, week 4, 8, 12, and 24. Endoscopic evaluations were conducted at baseline and week 12. Mucosal specimens were obtained at the margin of lesions by endoscopy biopsies and used for RNA sequencing. Two hUC-MSCs co-culture systems were established in vitro, one with the mucosa specimens and the other with M1 macrophages induced from THP1. The expressions of genes representing inflammation (TNFα, IL-6, and IL-1β) and intestinal barrier function (ZO1, CLAUDIN1, and CDH1) were tested by RT-PCR.

FINDINGS

hUC-MSCs treatment increased body weight and decreased disease activity index (DAI), colon macroscopic damage index (CMDI), and histopathological score (HPS) of rats with TNBS-induced colitis. The results of the clinical study also showed that this mode of hUC-MSCs application was associated with regression of intestinal ulceration. Eight patients (47%) got endoscopic responses (SES-CD improvement of ≥50% from baseline) and three patients (17.65%) got mucosal healing (SES-CD is zero), with a parallel improvement of clinical and laboratory parameters without serious adverse events. RNA sequencing showed hUC-MSCs therapy was associated with an upregulation of transcripts linked to intestinal epithelial barrier integrity and a downregulation of inflammatory signaling pathways in the intestinal mucosa, especially the TNF signaling pathway, IL-17 signaling pathway, and TLR signaling pathway. RNA expression of intestinal epithelial tight junction protein (ZO1, CLAUDIN1, and CDH1), and the RNA expression of major intestinal inflammatory factors in CD (IL-1β, IL-6, and TNFα, p < 0.001 for all) were improved significantly. Moreover, hUC-MSCs could attenuate the polarization of M1 macrophage induced from THP1, thereby decreasing the mRNA expression of IL-1β, IL-6, and TNFα significantly (p < 0.05 for all). TSG-6 expression was evaluated in hUC-MSCs culture supernatant after treatment with TNFα, IFNγ, and LPS for 48 h. And hUC-MSCs could inhibit the phosphorylation of JAK/STAT1 in the intestinal mucosa of CD patients.

INTERPRETATION

hUC-MSCs transplantation alleviated TNBS-induced colitis in rats. In this pilot clinical study, preliminary data suggested that this approach to administering hUC-MSCs might have potential for clinical efficacy and manageable safety in treating refractory CD, potentially providing hope for better outcomes. No serious adverse events were observed.

FUNDING

This work was funded by General Program of National Natural Science Foundation of China (Grant No. 82270639), the Scientific research project of Shanghai Municipal Health Committee (Grant No. 202240001), Specialty Feature Construction Project of Shanghai Pudong New Area Health Commission (Grant No. PWZzb2022-05), Shanghai East Hospital Youth Research and Cultivation Foundation program (Grant No. DFPY2022015), Peak Disciplines (Type IV) of Institutions of Higher Learning in Shanghai and Technology Development Project of Pudong Science, Technology and Economic Commission of Shanghai (Grant No. PKJ2021-Y08).

Bicarbonate secretion and acid/base sensing by the intestine

The transport of bicarbonate across the enterocyte cell membrane regulates the intracellular as well as the luminal pH and is an essential part of directional fluid movement in the gut. Since the first description of "active" transport of HCO3- ions against a concentration gradient in the 1970s, the fundamental role of HCO3- transport for multiple intestinal functions has been recognized. The ion transport proteins have been identified and molecularly characterized, and knockout mouse models have given insight into their individual role in a variety of functions. This review describes the progress made in the last decade regarding novel techniques and new findings in the molecular regulation of intestinal HCO3- transport in the different segments of the gut. We discuss human diseases with defects in intestinal HCO3- secretion and potential treatment strategies to increase luminal alkalinity. In the last part of the review, the cellular and organismal mechanisms for acid/base sensing in the intestinal tract are highlighted.

Traditional herbal pair Portulacae Herba and Granati Pericarpium alleviates DSS-induced colitis in mice through IL-6/STAT3/SOCS3 pathway

BACKGROUND

Portulacae Herba and Granati Pericarpium pair (PGP) is a traditional Chinese herbal medicine treatment for colitis, clinically demonstrating a relatively favorable effect on relieving diarrhea and abnormal stools. However, the underlying mechanism remain uncertain.

PURPOSE

The present study intends to evaluate the efficacy of PGP in treating colitis in mice and investigate its underlying mechanism.

METHODS

The protective effect of PGP against colitis was determined by monitoring body weight, colon length, colon weight, and survival rate in mice. Colonic inflammation was assessed by serum cytokine levels, colonic H&E staining, and local neutrophil infiltration. The reversal of intestinal epithelial barrier damage by PGP was subsequently analyzed with Western blot and histological staining. Furthermore, RNA-seq analysis and molecular docking were performed to identify potential pathways recruited by PGP. Following the hints of the transcriptomic results, the role of PGP through the IL-6/STAT3/SOCS3 pathway in DSS-induced colitis mice was verified by Western blot.

RESULTS

DSS-induced colitis in mice was significantly curbed by PGP treatment. PGP treatment significantly mitigated DSS-induced colitis in mice, as evidenced by improvements in body weight, DAI severity, survival rate, and inflammatory cytokines levels in serum and colon. Moreover, PGP treatment up-regulated the level of Slc26a3, thereby increasing the expressions of the tight junction/adherens junction proteins ZO-1, occludin and E-cadherin in the colon. RNA-seq analysis revealed that PGP inhibits the IL-6/STAT3/SOCS3 pathway at the transcriptional level. Molecular docking indicated that the major components of PGP could bind tightly to the proteins of IL-6 and SOCS3. Meanwhile, the result of Western blot revealed that the IL-6/STAT3/SOCS3 pathway was inhibited at the protein level after PGP administration.

CONCLUSION

PGP could alleviate colonic inflammation and reverse damage to the intestinal epithelial barrier in DSS-induced colitis mice. The underlying mechanism involves the inhibition of the IL-6/STAT3/SOCS3 pathway.

Reduced surface pH and upregulated AE2 anion exchange in SLC26A3-deleted polarized intestinal epithelial cells

Loss of function mutations in the SLC26A3 gene cause chloride-losing diarrhea in mice and humans. Although systemic adaptive changes have been documented in these patients and in the corresponding knockout mice, how colonic enterocytes adapt to loss of this highly expressed and highly regulated luminal membrane anion exchanger remains unclear. To address this question, SLC26A3 was deleted in the self-differentiating Caco2BBe colonic cell line by the CRISPR/Cas9 technique. We selected a clone with loss of SLC26A3 protein expression and morphological features indistinguishable from those of the native cell line. Neither growth curves nor development of transepithelial electrical resistance (TEER) differed between wild-type (WT) and SLC26A3 knockout (KO) cells. Real-time qPCR and Western analysis in SLC26A3-KO cells revealed an increase in AE2 expression without significant change in NHE3 expression or localization. Steady-state pHi and apical and basolateral Cl-/HCO3- exchange activities were assessed fluorometrically in a dual perfusion chamber with independent perfusion of luminal and serosal baths. Apical Cl-/HCO3- exchange rates were strongly reduced in SLC26A3-KO cells, accompanied by a surface pH more acidic than that of WT cells. Steady-state pHi was not significantly different from that of WT cells, but basolateral Cl-/HCO3- exchange rates were higher in SLC26A3-KO than in WT cells. The data show that CRISPR/Cas9-mediated SLC26A3 deletion strongly reduced apical Cl-/HCO3- exchange rate and apical surface pH, but sustained a normal steady-state pHi due to increased expression and function of basolateral AE2. The low apical surface pH resulted in functional inhibition of NHE-mediated fluid absorption despite normal expression of NHE3 polypeptide.NEW & NOTEWORTHY SLC26A3 gene mutations cause chloride-losing diarrhea. To understand how colonic enterocytes adapt, SLC26A3 was deleted in Caco2BBe cells using CRISPR/Cas9. In comparison to the wild-type cells, SLC26A3 knockout cells showed similar growth and transepithelial resistance but substantially reduced apical Cl-/HCO3- exchange rates, and an acidic surface pH. Steady-state intracellular pH was comparable between the WT and KO cells due to increased basolateral AE2 expression and function.

Pharmacological Activation of TRPC6 Channel Prevents Colitis Progression

We recently reported that transient receptor potential canonical (TRPC) 6 channel activity contributes to intracellular Zn2+ homeostasis in the heart. Zn2+ has also been implicated in the regulation of intestinal redox and microbial homeostasis. This study aims to investigate the role of TRPC6-mediated Zn2+ influx in the stress resistance of the intestine. The expression profile of TRPC1-C7 mRNAs in the actively inflamed mucosa from inflammatory bowel disease (IBD) patients was analyzed using the GEO database. Systemic TRPC3 knockout (KO) and TRPC6 KO mice were treated with dextran sulfate sodium (DSS) to induce colitis. The Zn2+ concentration and the mRNA expression levels of oxidative/inflammatory markers in colon tissues were quantitatively analyzed, and gut microbiota profiles were compared. TRPC6 mRNA expression level was increased in IBD patients and DSS-treated mouse colon tissues. DSS-treated TRPC6 KO mice, but not TRPC3 KO mice, showed severe weight loss and increased disease activity index compared with DSS-treated WT mice. The mRNA abundances of antioxidant proteins were basically increased in the TRPC6 KO colon, with changes in gut microbiota profiles. Treatment with TRPC6 activator prevented the DSS-induced colitis progression accompanied by increasing Zn2+ concentration. We suggest that TRPC6-mediated Zn2+ influx activity plays a key role in stress resistance against IBD, providing a new strategy for treating colitis.

YAP represses intestinal inflammation through epigenetic silencing of JMJD3

BACKGROUND

Epigenetics plays an important role in the pathogenesis of inflammatory bowel disease (IBD). Some studies have reported that YAP is involved in inflammatory response and can regulate target genes through epigenetic modifications. JMJD3, a histone H3K27me3 demethylase, is associated with some inflammatory diseases. In this study, we investigated the role of YAP in the development of IBD and the underlying epigenetic mechanisms.

RESULTS

YAP expression was significantly increased in both in vitro and in vivo colitis models as well as in patients with IBD. Epithelial-specific knockout of YAP aggravates disease progression in dextran sodium sulfate (DSS)-induced murine colitis. In the TNF-α-activated cellular inflammation model, YAP knockdown significantly increased JMJD3 expression. Coimmunoprecipitation experiments showed that YAP and EZH2 bind to each other, and chromatin immunoprecipitation-PCR (ChIP-PCR) assay indicated that silencing of YAP or EZH2 decreases H3K27me3 enrichment on the promoter of JMJD3. Finally, administration of the JMJD3 pharmacological inhibitor GSK-J4 alleviated the progression of DSS-induced murine colitis.

CONCLUSION

Our findings elucidate an epigenetic mechanism by which YAP inhibits the inflammatory response in colitis through epigenetic silencing of JMJD3 by recruiting EZH2.

SLC26 Anion Transporters

Solute carrier family 26 (SLC26) is a family of functionally diverse anion transporters found in all kingdoms of life. Anions transported by SLC26 proteins include chloride, bicarbonate, and sulfate, but also small organic dicarboxylates such as fumarate and oxalate. The human genome encodes ten functional homologs, several of which are causally associated with severe human diseases, highlighting their physiological importance. Here, we review novel insights into the structure and function of SLC26 proteins and summarize the physiological relevance of human members.

SECTM1 promotes the development of glioblastoma and mesenchymal transition by regulating the TGFβ1/Smad signaling pathway

Objective: Secreted and transmembrane protein 1 (SECTM1) is a gene encoding a transmembrane protein. The role of SECTM1 in glioblastoma (GBM) is unclear. Here, we reported the abnormal expression of SECTM1 in GBM for the first time and studied the role and mechanism of SECTM1 in GBM. Methods: qRT-PCR, Western blotting and immunofluorescence were used to detect the expression of SECTM1 in gliomas of different grades and GBM cell lines. After the knockdown of SECTM1 expression in cell lines by shRNA, the effect of SECTM1 in GBM cell lines was verified by CCK-8, Transwell, EdU and wound healing experiments. We further investigated the effect and mechanism of SECTM1 on GBM in vitro and in vivo. The effect of SECTM1 on glioma growth was detected by subcutaneous tumor xenografts in nude mice in vivo. Results: The results showed that the knockdown of SECTM1 expression in cell lines significantly inhibited the proliferation, migration and invasion of GBM cells while inhibiting the progression of subcutaneous xenograft tumors in nude mice. However, the role and molecular mechanism of SECTM1 in GBM remain unclear. SECTM1 was found to promote GBM epithelial-mesenchymal transition (EMT) like processes. Bioinformatics analysis and Western blotting showed that SECTM1 regulates glioblastoma invasion and EMT-like processes mainly through the TGFβ1/Smad signaling pathway. Conclusion: The low expression of SECTM1 has an inhibitory effect on GBM and is a potential target for GBM treatment. SECTM1 may also be a promising biomarker for the diagnosis and prognosis of GBM.

Research progress on the relationship between Paneth cells-susceptibility genes, intestinal microecology and inflammatory bowel disease

Inflammatory bowel disease (IBD) is a disorder of the immune system and intestinal microecosystem caused by environmental factors in genetically susceptible people. Paneth cells (PCs) play a central role in IBD pathogenesis, especially in Crohn's disease development, and their morphology, number and function are regulated by susceptibility genes. In the intestine, PCs participate in the formation of the stem cell microenvironment by secreting antibacterial particles and play a role in helping maintain the intestinal microecology and intestinal mucosal homeostasis. Moreover, PC proliferation and maturation depend on symbiotic flora in the intestine. This paper describes the interactions among susceptibility genes, PCs and intestinal microecology and their effects on IBD occurrence and development.

Colitis-associated carcinogenesis: crosstalk between tumors, immune cells and gut microbiota

Colorectal cancer (CRC) is the third most common cancer worldwide. One of the main causes of colorectal cancer is inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD). Intestinal epithelial cells (IECs), intestinal mesenchymal cells (IMCs), immune cells, and gut microbiota construct the main body of the colon and maintain colon homeostasis. In the development of colitis and colitis-associated carcinogenesis, the damage, disorder or excessive recruitment of different cells such as IECs, IMCs, immune cells and intestinal microbiota play different roles during these processes. This review aims to discuss the various roles of different cells and the crosstalk of these cells in transforming intestinal inflammation to cancer, which provides new therapeutic methods for chemotherapy, targeted therapy, immunotherapy and microbial therapy.

Efficient Therapy of Inflammatory Bowel Disease (IBD) with Highly Specific and Durable Targeted Ta2 C Modified with Chondroitin Sulfate (TACS)

Non-invasive localization of lesions and specific targeted therapy are still the main challenges for inflammatory bowel disease (IBD). Ta, as a medical metal element, has been widely used in the treatment of different diseases because of its excellent physicochemical properties but is still far from being explored in IBD. Here, Ta2 C modified with chondroitin sulfate (CS) (TACS) is evaluated as a highly targeted therapy nanomedicine for IBD. Specifically, TACS is modified with dual targeting CS functions due to IBD lesion-specific positive charges and high expression of CD44 receptors. Thanks to the acid stability, sensitive CT imaging function, and strong reactive oxygen species (ROS) elimination ability, oral TACS can accurately locate and delineate IBD lesions through non-invasive CT imaging, and specifically targeted treat IBD effectively because high levels of ROS are a central factor in the progression of IBD. As expected, TACS has much better imaging and therapeutic effects than clinical CT contrast agent and first-line drug 5-aminosalicylic acid, respectively. The mechanism of TACS treatment mainly involves protection of mitochondria, elimination of oxidative stress, inhibiting macrophage M1 polarization, protection of intestinal barrier, and restoration of intestinal flora balance. Collectively, this work provides unprecedented opportunities for oral nanomedicines to targeted therapy of IBD.

Vitamin D is a potential treatment for the management of gastrointestinal mucositis

PURPOSE OF THE REVIEW

Gastrointestinal mucositis (GM) is a severe side effect of cancer treatments, negatively impacting the patient's quality of life, and has limited treatment. GM consists of complex biological processes involving apoptosis and inflammation, leading to damage and ulceration of the gastrointestinal system. Recently, vitamin D has been shown to have multiple roles in the gut, including immunomodulation, epithelial barrier regulation and microbiome regulation. Hence, this review aims to put forth vitamin D as a potential therapeutic due to its protective role in the intestine.

RECENT FINDINGS

Recent studies have shown that vitamin D can reduce intestinal inflammation by reducing NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) activation. Vitamin D also targets and maintains the intestinal epithelial barrier via the tight junction protein expression and the inhibition of microbiome translocation. Significant evidence also suggests that vitamin D exerts multiple therapeutic effects through binding to vitamin D receptors (VDRs), and the downregulation of VDR has been associated with the severity of the disease. Additionally, vitamin D deficiency is reported in cancer patients.

SUMMARY

There is a dire need for effective treatment for GM, and recent animal and human studies show that vitamin D may be a potential therapy to prevent or treat GM.

SLC26A3/NHERF2-IκB/NFκB/p65 feedback loop suppresses tumorigenesis and metastasis in colorectal cancer

Colorectal cancer (CRC) is a formidable disease due to the intricate mechanisms that drive its proliferation and metastasis. Despite significant progress in cancer research, the integration of these mechanisms that influence cancer cell behavior remains elusive. Therefore, it is imperative to comprehensively elucidate the underlying mechanisms driving CRC proliferation and metastasis. In this study, we reported a novel role of SLC26A3 in suppressing CRC progression. We found that SLC26A3 expression was downregulated in CRC, which was proportionally correlated with survival. Our in vivo and in vitro experiments demonstrated that up-regulation of SLC26A3 inhibited CRC proliferation and metastasis, while down-regulation of SLC26A3 promoted CRC progression by modulating the expression level of IκB. Furthermore, we identified NHERF2 as a novel interacting protein of SLC26A3 responsible for stabilizing the IκB protein and removing ubiquitination modification. Mechanistically, SLC26A3 augmented the interaction between NHERF2 and IκB, subsequently reducing its degradation. This process inhibited the dissociation of p65 from the IκB/p65/p50 complex and reduced the translocation of p65 from the cytoplasm to the nucleus. Moreover, our investigation revealed that NF-κB/p65 directly bound to the promoter of SLC26A3, leading to a decline in its mRNA expression. Thus, SLC26A3 impeded the nuclear translocation of NF-κB/p65, enhancing the transcription of SLC26A3 and establishing a positive regulatory feedback loop in CRC cells. Collectively, these results suggest that a SLC26A3/NHERF2-IκB/NF-κB/p65 signaling loop suppresses proliferation and metastasis in CRC cells. These findings propose a novel SLC26A3-driven signaling loop that regulates proliferation and metastasis in CRC, providing promising therapeutic interventions and prognostic targets for the management of CRC.

Pharmacologic inhibition of glycolysis prevents the development of lupus by altering the gut microbiome in mice

Gut dysbiosis has been associated with lupus pathogenesis, and fecal microbiota transfers (FMT) from lupus-prone mice shown to induce autoimmune activation into healthy mice. The immune cells of lupus patients exhibit an increased glucose metabolism and treatments with 2-deoxy-D-glucose (2DG), a glycolysis inhibitor, are therapeutic in lupus-prone mice. Here, we showed in two models of lupus with different etiologies that 2DG altered the composition of the fecal microbiome and associated metabolites. In both models, FMT from 2DG-treated mice protected lupus-prone mice of the same strain from the development of glomerulonephritis, reduced autoantibody production as well as the activation of CD4+ T cells and myeloid cells as compared to FMT from control mice. Thus, we demonstrated that the protective effect of glucose inhibition in lupus is transferable through the gut microbiota, directly linking alterations in immunometabolism to gut dysbiosis in the hosts.

Oxalate Homeostasis in Non-Stone-Forming Chronic Kidney Disease: A Review of Key Findings and Perspectives

Chronic kidney disease (CKD) is a significant global public health concern associated with high morbidity and mortality rates. The maintenance of oxalate homeostasis plays a critical role in preserving kidney health, particularly in the context of CKD. Although the relationship between oxalate and kidney stone formation has been extensively investigated, our understanding of oxalate homeostasis in non-stone-forming CKD remains limited. This review aims to present an updated analysis of the existing literature, focusing on the intricate mechanisms involved in oxalate homeostasis in patients with CKD. Furthermore, it explores the key factors that influence oxalate accumulation and discusses the potential role of oxalate in CKD progression and prognosis. The review also emphasizes the significance of the gut-kidney axis in CKD oxalate homeostasis and provides an overview of current therapeutic strategies, as well as potential future approaches. By consolidating important findings and perspectives, this review offers a comprehensive understanding of the present knowledge in this field and identifies promising avenues for further research.

SLC26 family: a new insight for kidney stone disease

The solute-linked carrier 26 (SLC26) protein family is comprised of multifunctional transporters of substrates that include oxalate, sulphate, and chloride. Disorders of oxalate homeostasis cause hyperoxalemia and hyperoxaluria, leading to urinary calcium oxalate precipitation and urolithogenesis. SLC26 proteins are aberrantly expressed during kidney stone formation, and consequently may present therapeutic targets. SLC26 protein inhibitors are in preclinical development. In this review, we integrate the findings of recent reports with clinical data to highlight the role of SLC26 proteins in oxalate metabolism during urolithogenesis, and discuss limitations of current studies and potential directions for future research.

The Air-Liquid Interface Reorganizes Membrane Lipids and Enhances the Recruitment of Slc26a3 to Lipid-Rich Domains in Human Colonoid Monolayers

Cholesterol-rich membrane domains, also called lipid rafts (LRs), are specialized membrane domains that provide a platform for intracellular signal transduction. Membrane proteins often cluster in LRs that further aggregate into larger platform-like structures that are enriched in ceramides and are called ceramide-rich platforms (CRPs). The role of CRPs in the regulation of intestinal epithelial functions remains unknown. Down-regulated in adenoma (DRA) is an intestinal Cl-/HCO3- antiporter that is enriched in LRs. However, little is known regarding the mechanisms involved in the regulation of DRA activity. The air-liquid interface (ALI) was created by removing apical media for a specified number of days; from 12-14 days post-confluency, Caco-2/BBe cells or a colonoid monolayer were grown as submerged cultures. Confocal imaging was used to examine the dimensions of membrane microdomains that contained DRA. DRA expression and activity were enhanced in Caco-2/BBe cells and human colonoids using an ALI culture method. ALI causes an increase in acid sphingomyelinase (ASMase) activity, an enzyme responsible for enhancing ceramide content in the plasma membrane. ALI cultures expressed a larger number of DRA-containing platforms with dimensions >2 µm compared to cells grown as submerged cultures. ASMase inhibitor, desipramine, disrupted CRPs and reduced the ALI-induced increase in DRA expression in the apical membrane. Exposing normal human colonoid monolayers to ALI increased the ASMase activity and enhanced the differentiation of colonoids along with basal and forskolin-stimulated DRA activities. ALI increases DRA activity and expression by increasing ASMase activity and platform formation in Caco-2/BBe cells and by enhancing the differentiation of colonoids.

Epithelial Gab1 calibrates RIPK3-dependent necroptosis to prevent intestinal inflammation

As a hallmark of inflammatory bowel disease (IBD), elevated intestinal epithelial cell (IEC) death compromises the gut barrier, activating the inflammatory response and triggering more IEC death. However, the precise intracellular machinery that prevents IEC death and breaks this vicious feedback cycle remains largely unknown. Here, we report that Grb2-associated binder 1 (Gab1) expression is decreased in patients with IBD and inversely correlated with IBD severity. Gab1 deficiency in IECs accounted for the exacerbated colitis induced by dextran sodium sulfate owing to sensitizing IECs to receptor-interaction protein kinase 3-mediated (RIPK3-mediated) necroptosis, which irreversibly disrupted the homeostasis of the epithelial barrier and promoted intestinal inflammation. Mechanistically, Gab1 negatively regulated necroptosis signaling through inhibiting the formation of RIPK1/RIPK3 complex in response to TNF-α. Importantly, administration of RIPK3 inhibitor revealed a curative effect in epithelial Gab1-deficient mice. Further analysis indicated mice with Gab1 deletion were prone to inflammation-associated colorectal tumorigenesis. Collectively, our study defines a protective role for Gab1 in colitis and colitis-driven colorectal cancer by negatively regulating RIPK3-dependent necroptosis, which may serve as an important target to address necroptosis and intestinal inflammation-related disease.

Vitamin D receptor involves in the protection of intestinal epithelial barrier function via up-regulating SLC26A3

BACKGROUND

Vitamin D receptor (VDR) and SLC26A3 (DRA) have been identified as pivotal protective factors in maintaining gut homeostasis in IBD patients. However, the specific mechanism underlying the increased intestinal susceptibility to inflammation induced by the loss of VDR and whether DRA participates in the role of VDR regulating intestinal epithelial barrier function are undefined.

AIM

The current study is undertaken to elucidate the regulatory effects of VDR on DRA and VDR prevents intestinal epithelial barrier dysfunction via up-regulating the expression of DRA.

METHODS

WT and VDR^-/- mice are used as models for intestinal epithelial response. Paracellular permeability is measured by TEER and FD-4 assays. Immunohistochemistry, immunofluorescence, qPCR and immunoblotting are performed to determine the effects of VDR and DRA on gut epithelial barrier function.

RESULTS

VDR^-/- mice exhibits significant hyperpermeability of intestine with greatly decreased levels of ZO-1 and Claudin1 proteins. DRA is located on the intestinal epithelial apical membrane and is tightly modulated by VDR in vivo and in vitro via activating ERK1/2 MAPK signaling pathway. Notably, the current study for the first time demonstrates that VDR maintains intestinal epithelial barrier integrity via up-regulating DRA expression and the lack of DRA induced by VDR knockdown leads to a more susceptive condition for intestine to DSS-induced colitis.

CONCLUSION

Our study provides evidence and deep comprehension regarding the role of VDR in modulating DRA expression in gut homeostasis and makes novel contributions to better generally understanding the links between VDR, DRA and intestinal epithelial barrier function.

Increased intestinal permeability and downregulation of absorptive ion transporters Nhe3, Dra, and Sglt1 contribute to diarrhea during Clostridioides difficile infection

BACKGROUND & AIM

Clostridioides difficile infection (CDI) is the leading cause of hospital-acquired diarrhea and pseudomembranous colitis. Two protein toxins, TcdA and TcdB, produced by C. difficile are the major determinants of disease. However, the pathophysiological causes of diarrhea during CDI are not well understood. Here, we investigated the effects of C. difficile toxins on paracellular permeability and apical ion transporters in the context of an acute physiological infection.

METHODS

We studied intestinal permeability and apical membrane transporters in female C57BL/6J mice. Üssing chambers were used to measure paracellular permeability and ion transporter function across the intestinal tract. Infected intestinal tissues were analyzed by immunofluorescence microscopy and RNA-sequencing to uncover mechanisms of transporter dysregulation.

RESULTS

Intestinal permeability was increased through the size-selective leak pathway in vivo during acute CDI in a 2-day-post infection model. Chloride secretory activity was reduced in the cecum and distal colon during infection by decreased CaCC and CFTR function, respectively. SGLT1 activity was significantly reduced in the cecum and colon, accompanied by ablated SGLT1 expression in colonocytes and increased luminal glucose concentrations. SGLT1 and DRA expression was ablated by either TcdA or TcdB during acute infection, but NHE3 was decreased in a TcdB-dependent manner. The localization of key proteins that link filamentous actin to the ion transporters in the apical plasma membrane was unchanged. However, Sglt1, Nhe3, and Dra were drastically reduced at the transcript level, implicating downregulation of ion transporters in the mechanism of diarrhea during CDI.

CONCLUSIONS

CDI increases intestinal permeability and decreases apical abundance of NHE3, SGLT1, and DRA. This combination likely leads to dysfunctional water and solute absorption in the large bowel, causing osmotic diarrhea. These findings provide insights into the pathophysiological mechanisms underlying diarrhea and may open novel avenues for attenuating CDI-associated diarrhea.

Loss of SLC26A3 Results in Colonic Mucosal Immune Dysregulation via Epithelial-Immune Cell Crosstalk

BACKGROUND & AIMS

Down-regulation of chloride transporter SLC26A3 or down-regulated in adenoma (DRA) in colonocytes has recently been linked to the pathogenesis of ulcerative colitis (UC). Because exaggerated immune responses are one of the hallmarks of UC, these current studies were undertaken to define the mechanisms by which loss of DRA relays signals to immune cells to increase susceptibility to inflammation.

METHODS

NanoString Immunology Panel, fluorescence assisted cell sorting, immunoblotting, immunofluorescence, and quantitative real-time polymerase chain reaction assays were used in wild-type and DRA knockout (KO) mice. Interleukin (IL)-33 blocking was used to determine specific changes in immune cells and co-housing/broad spectrum antibiotics administration, and ex vivo studies in colonoids were conducted to rule out the involvement of microbiota. Colonoid-derived monolayers from healthy and UC patient biopsies were analyzed for translatability.

RESULTS

There was a marked induction of Th2 (>2-fold), CD4⁺ Th2 cells (∼8-fold), RORγt⁺ Th17, and FOXP3⁺ regulatory T cells (Tregs). DRA KO colons also exhibited a robust induction of IL-33 (>8-fold). In vivo studies using blocking of IL-33 established that T2 immune dysregulation (alterations in ILC2, Th2, and GATA3⁺ iTregs) in response to loss of DRA was due to altered epithelial-immune cell crosstalk via IL-33.

CONCLUSIONS

Loss of DRA in colonocytes triggers the release of IL-33 to drive a type 2 immune response. These observations emphasize the critical importance of DRA in mucosal immune homeostasis and its implications in the pathogenesis of UC.

Gene/environment interaction in the susceptibility of Crohn's disease patients to aluminum

BACKGROUND & AIM

The key role of environmental factors in the pathogenesis of Inflammatory Bowel Diseases (IBD) is recognized. Aluminum is suspected to be a risk factor for IBD. However, mechanisms linking aluminum exposure to disease development are unknown. We examined the role of aluminum transport and subcellular localisation on human colon susceptibility to aluminum-induced inflammation.

METHODS

Human colon biopsies isolated from Crohn's disease (CD) or control patients and Caco-2 cells were incubated with aluminum. The effects of aluminum were evaluated on cytokine secretion and transporter expression. The role of aluminum kinetics parameters was studied in Caco-2 using transport inhibitors and in human colon biopsies by assessing genetic polymorphisms of transporters.

RESULTS

Aluminum exposure was shown to induce cytokine secretion in colon of CD but not healthy patients. In Caco-2 cells, aluminum internalisation was correlated with inflammatory status. In human colon, analysis of genetic polymorphisms and expression of ABCB1 and SLC26A3 transporters showed that their decreased activity was involved in aluminum-induced inflammation.

CONCLUSIONS

We hypothesize that alteration in detoxifying response would lead to a deregulation of intestinal homeostasis and to the expression of IBD. Our study emphasizes the complexity of gene/environment interaction for aluminum adverse health effect, highlighting at risk populations or subtypes of patients. A better understanding of correlations between gene expression or SNP and xenobiotic kinetics parameters would shift the medical paradigm to more personalized disease management and treatment.

Ischemic Stroke Impacts the Gut Microbiome, Ileal Epithelial and Immune Homeostasis

Ischemic stroke critically impacts neurovascular homeostasis, potentially resulting in neurological disorders. However, the mechanisms through which stroke-induced inflammation modifies the molecular and metabolic circuits, particularly in ileal epithelial cells (iECs), currently remain elusive. Using multiomic approaches, we illustrated that stroke impaired the ileal microbiome and associated metabolites, leading to increased inflammatory signals and altered metabolites, potentially deteriorating the iEC homeostasis. Bulk transcriptomic and metabolomic profiling demonstrated that stroke enhanced fatty acid oxidation while reducing the tricarboxylic acid (TCA) cycle in iECs within the first day after stroke. Intriguingly, single-cell RNA sequencing analysis revealed that stroke dysregulated cell-type-specific gene responses within iECs and reduced frequencies of goblet and tuft cells. Additionally, stroke augmented interleukin-17A+ γδ T cells but decreased CD4+ T cells in the ileum. Collectively, our findings provide a comprehensive overview of stroke-induced intestinal dysbiosis and unveil responsive gene programming within iECs with implications for disease development.