Mucin gene expression in the intestine of ulcerative colitis patients: a systematic review and meta-analysis

Unveiling gut microbiota's role: Bidirectional regulation of drug transport for improved safety

Drug safety is a paramount concern in the field of drug development, with researchers increasingly focusing on the bidirectional regulation of gut microbiota in this context. The gut microbiota plays a crucial role in maintaining drug safety. It can influence drug transport processes in the body through various mechanisms, thereby modulating their efficacy and toxicity. The main mechanisms include: (1) The gut microbiota directly interacts with drugs, altering their chemical structure to reduce toxicity and enhance efficacy, thereby impacting drug transport mechanisms, drugs can also change the structure and abundance of gut bacteria; (2) bidirectional regulation of intestinal barrier permeability by gut microbiota, promoting the absorption of nontoxic drugs and inhibiting the absorption of toxic components; (3) bidirectional regulation of the expression and activity of transport proteins by gut microbiota, selectively promoting the absorption of effective components or inhibiting the absorption of toxic components. This bidirectional regulatory role enables the gut microbiota to play a key role in maintaining drug balance in the body and reducing adverse reactions. Understanding these regulatory mechanisms sheds light on novel approaches to minimize toxic side effects, enhance drug efficacy, and ultimately improve drug safety. This review systematically examines the bidirectional regulation of gut microbiota in drug transportation from the aforementioned aspects, emphasizing their significance in ensuring drug safety. Furthermore, it offers a prospective outlook from the standpoint of enhancing therapeutic efficacy and reducing drug toxicity, underscoring the importance of further exploration in this research domain. It aims to provide more effective strategies for drug development and treatment.

The Potential Role of Plant Polysaccharides in Treatment of Ulcerative Colitis

Ulcerative colitis (UC) results in inflammation and ulceration of the colon and the rectum's inner lining. The application of herbal therapy in UC is increasing worldwide. As natural macromolecular compounds, polysaccharides have a significant role in the treatment of UC due to advantages of better biodegradation, good biocompatibility, immunomodulatory activity, and low reactogenicity. Therefore, polysaccharide drug formulation is becoming a potential candidate for UC treatment. In this review, we summarize the etiology and pathogenesis of UC and the therapeutic effects of polysaccharides on UC, such as regulating the expression of cytokines and tight junction proteins and modulating the balance of immune cells and intestinal microbiota. Polysaccharides can also serve as drug delivery carriers to enhance drug targeting and reduce side effects. This review provides a theoretical basis for applying natural plant polysaccharides in the prevention and treatment of UC.

Eubacterium coprostanoligenes alleviates chemotherapy-induced intestinal mucositis by enhancing intestinal mucus barrier

Chemotherapy-induced mucositis represents a severe adverse outcome of cancer treatment, significantly curtailing the efficacy of these treatments and, in some cases, resulting in fatal consequences. Despite identifying intestinal epithelial cell damage as a key factor in chemotherapy-induced mucositis, the paucity of effective treatments for such damage is evident. In our study, we discovered that Eubacterium coprostanoligenes promotes mucin secretion by goblet cells, thereby fortifying the integrity of the intestinal mucus barrier. This enhanced barrier function serves to resist microbial invasion and subsequently reduces the inflammatory response. Importantly, this effect remains unobtrusive to the anti-tumor efficacy of chemotherapy drugs. Mechanistically, E. copr up-regulates the expression of AUF1, leading to the stabilization of Muc2 mRNA and an increase in mucin synthesis in goblet cells. An especially significant finding is that E. copr activates the AhR pathway, thereby promoting the expression of AUF1. In summary, our results strongly indicate that E. copr enhances the intestinal mucus barrier, effectively alleviating chemotherapy-induced intestinal mucositis by activating the AhR/AUF1 pathway, consequently enhancing Muc2 mRNA stability.

Hyper Mucinous Proliferations in the Mucosa of Patients with Inflammatory Bowel Disease: Histological Lesions with a Real Potential for Neoplastic Evolution?

BACKGROUND AND AIMS

Mucin disfunction is a critical event in the pathogenesis of inflammatory bowel disease (IBD). Although hyper mucinous conditions have a still debated implication in the clinical evolution of this disorder, hyper mucinous villous proliferations were found to have a preneoplastic biologic potential. We studied morphologic and immunophenotypic characteristics of these lesions in ileocolonic resections for IBD to add evidence about the evolutive potential of these lesions in samples with well oriented wall structures.

METHODS

Morphologic characteristics of bowel samples from 20 patients resected for IBD and with raised lesions at gross examination were studied and sections from cases with hyper mucinous lesions were stained with the following antibodies: Ki 67, p21, and p27, which were employed to evaluate the characteristics of the proliferative and differentiative activity of the epithelial structures; mismatch repair proteins and p53 have been studied as proteins implicated in carcinogenesis in IBD-affected mucosa; mucins subtypes in hyper mucinous structures were evaluated with MUC-2 and MUC-6. The results in 11 cases of saplings were that they harbored hyper mucinous proliferations. The occurrence of hyper mucinous structures was not related to dysplastic lesions, pseudo pyloric metaplasia, subtype of disease, or activity. In only one of our cases, mild cytologic atypia in the proliferative compartment was detected. Proliferation markers (Ki 67, p53) were expressed in the proliferative compartments of mucosal crypts and antiproliferative proteins p21 and p27 were expressed in differentiated epithelium. MMR proteins expression was limited to the proliferative compartment of the hyper mucinous projections. Mucin subtypes distribution was regular in the epithelium of hyper mucinous proliferations.

CONCLUSIONS

The present monocentric retrospective study was conducted on surgical samplings with well oriented crypts. Collected data show that hyper mucinous features are frequent occurrences in raised lesions in IBD patients. In hyper mucinous proliferations of the selected cases, the status of the proliferative cycle, the expression of the proteins most frequently involved in carcinogenetic pathways of mucosa affected by IBD, and the mucins subtypes expression have no evident anomalies. Findings are not consistent with the increased risk of neoplastic evolution observed in other studies; rather, they suggest a hyperplastic nature. However, the capacity of hyper mucinous raised lesions for neoplastic evolution should be ruled out with more extensive prospective studies to identify functional defects that could explain the hypothesized neoplastic potential.

Muc2 mucin O-glycosylation interacts with enteropathogenic Escherichia coli to influence the development of ulcerative colitis based on the NF-kB signaling pathway

BACKGROUND

Ulcerative colitis (UC) is a chronic inflammatory disease of the intestine characterized by a compromised intestinal epithelial barrier. Mucin glycans are crucial in preserving barrier function during bacterial infections, although the underlying mechanisms remain largely unexplored.

METHODS

A cohort comprising 15 patients diagnosed with UC and 15 healthy individuals was recruited. Stool samples were collected to perform 16S rRNA gene sequencing, while biopsy samples were subjected to nanocapillary liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) to assess O-glycosylation. Gene expression was evaluated through qPCR analysis and Western blotting. Furthermore, animal experiments were conducted to investigate the effects of Escherichia coli and/or O-glycan inhibitor benzyl-α-GalNAc on the development of colitis in mice.

RESULTS

Our findings revealed that the mucus barrier was disrupted during the early stages of UC, while the MUC2 protein content remained unaltered. Additionally, a noteworthy reduction in the O-glycosylation of MUC2 was observed, along with significant changes in the intestinal microbiota during the early stages of UC. These changes included a decrease in intestinal species richness and an increase in the abundance of Escherichia coli (E. coli). Moreover, subsequent to the administration of galactose or O-glycan inhibitor to intestinal epithelial cells, it was observed that the cell culture supernatant had the ability to modify the proliferation and adhesive capacity of E. coli. Furthermore, when pathogenic E. coli or commensal E. coli were cocultured with intestinal epithelium, both strains elicited activation of the NF-KB signaling pathway in epithelial cells and facilitated the expression of serine protease in comparison to the untreated control. Consistently, the inhibition of O-glycans has been observed to enhance the pathogenicity of E. coli in vivo. Furthermore, a correlation has been established between the level of O-glycans and the development of ulcerative colitis. Specifically, a reduction in the O-glycan content of MUC2 cells has been found to increase the virulence of E. coli, thereby compromising the integrity of the intestinal epithelial barrier.

CONCLUSIONS

Together, there exist complex interactions between the intestinal epithelium, O-glycans, and the intestinal microbiota, which may inform the development of novel therapeutic strategies for the treatment of ulcerative colitis.

The mechanism of traditional medicine in alleviating ulcerative colitis: regulating intestinal barrier function

Ulcerative colitis (UC) is an idiopathic inflammatory disease mainly affects the large bowel and the rectum. The pathogenesis of this disease has not been fully elucidated, while the disruption of the intestinal barrier function triggered by various stimulating factors related to the host genetics, immunity, gut microbiota, and environment has been considered to be major mechanisms that affect the development of UC. Given the limited effective therapies, the treatment of this disease is not ideal and its incidence and prevalence are increasing. Therefore, developing new therapies with high efficiency and efficacy is important for treating UC. Many recent studies disclosed that numerous herbal decoctions and natural compounds derived from traditional herbal medicine showed promising therapeutic activities in animal models of colitis and have gained increasing attention from scientists in the study of UC. Some of these decoctions and compounds can effectively alleviate colonic inflammation and relieve clinical symptoms in animal models of colitis via regulating intestinal barrier function. While no study is available to review the underlying mechanisms of these potential therapies in regulating the integrity and function of the intestinal barrier. This review aims to summarize the effects of various herbal decoctions or bioactive compounds on the severity of colonic inflammation via various mechanisms, mainly including regulating the production of tight junction proteins, mucins, the composition of gut microbiota and microbial-associated metabolites, the infiltration of inflammatory cells and mediators, and the oxidative stress in the gut. On this basis, we discussed the related regulators and the affected signaling pathways of the mentioned traditional medicine in modulating the disruption or restoration of the intestinal barrier, such as NF-κB/MAPK, PI3K, and HIF-1α signaling pathways. In addition, the possible limitations of current studies and a prospect for future investigation and development of new UC therapies are provided based on our knowledge and current understanding. This review may improve our understanding of the current progression in studies of traditional medicine-derived therapies in protecting the intestinal barrier function and their roles in alleviating animal models of UC. It may be beneficial to the work of researchers in both basic and translational studies of UC.

Study of the roles of caspase-3 and nuclear factor kappa B in myenteric neurons in a P2X7 receptor knockout mouse model of ulcerative colitis

BACKGROUND

The literature indicates that the enteric nervous system is affected in inflammatory bowel diseases (IBDs) and that the P2X7 receptor triggers neuronal death. However, the mechanism by which enteric neurons are lost in IBDs is unknown.

AIM

To study the role of the caspase-3 and nuclear factor kappa B (NF-κB) pathways in myenteric neurons in a P2X7 receptor knockout (KO) mouse model of IBDs.

METHODS

Forty male wild-type (WT) C57BL/6 and P2X7 receptor KO mice were euthanized 24 h or 4 d after colitis induction by 2,4,6-trinitrobenzene sulfonic acid (colitis group). Mice in the sham groups were injected with vehicle. The mice were divided into eight groups (n = 5): The WT sham 24 h and 4 d groups, the WT colitis 24 h and 4 d groups, the KO sham 24 h and 4 d groups, and the KO colitis 24 h and 4 d groups. The disease activity index (DAI) was analyzed, the distal colon was collected for immunohistochemistry analyses, and immunofluorescence was performed to identify neurons immunoreactive (ir) for calretinin, P2X7 receptor, cleaved caspase-3, total caspase-3, phospho-NF-κB, and total NF-κB. We analyzed the number of calretinin-ir and P2X7 receptor-ir neurons per ganglion, the neuronal profile area (µm²), and corrected total cell fluorescence (CTCF).

RESULTS

Cells double labeled for calretinin and P2X7 receptor, cleaved caspase-3, total caspase-3, phospho-NF-κB, or total NF-κB were observed in the WT colitis 24 h and 4 d groups. The number of calretinin-ir neurons per ganglion was decreased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups, respectively (2.10 ± 0.13 vs 3.33 ± 0.17, P < 0.001; 2.92 ± 0.12 vs 3.70 ± 0.11, P < 0.05), but was not significantly different between the KO groups. The calretinin-ir neuronal profile area was increased in the WT colitis 24 h group compared to the WT sham 24 h group (312.60 ± 7.85 vs 278.41 ± 6.65, P < 0.05), and the nuclear profile area was decreased in the WT colitis 4 d group compared to the WT sham 4 d group (104.63 ± 2.49 vs 117.41 ± 1.14, P < 0.01). The number of P2X7 receptor-ir neurons per ganglion was decreased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups, respectively (19.49 ± 0.35 vs 22.21 ± 0.18, P < 0.001; 20.35 ± 0.14 vs 22.75 ± 0.51, P < 0.001), and no P2X7 receptor-ir neurons were observed in the KO groups. Myenteric neurons showed ultrastructural changes in the WT colitis 24 h and 4 d groups and in the KO colitis 24 h group. The cleaved caspase-3 CTCF was increased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups, respectively (485949 ± 14140 vs 371371 ± 16426, P < 0.001; 480381 ± 11336 vs 378365 ± 4053, P < 0.001), but was not significantly different between the KO groups. The total caspase-3 CTCF, phospho-NF-κB CTCF, and total NF-κB CTCF were not significantly different among the groups. The DAI was recovered in the KO groups. Furthermore, we demonstrated that the absence of the P2X7 receptor attenuated inflammatory infiltration, tissue damage, collagen deposition, and the decrease in the number of goblet cells in the distal colon.

CONCLUSION

Ulcerative colitis affects myenteric neurons in WT mice but has a weaker effect in P2X7 receptor KO mice, and neuronal death may be associated with P2X7 receptor-mediated caspase-3 activation. The P2X7 receptor can be a therapeutic target for IBDs.

View from the Biological Property: Insight into the Functional Diversity and Complexity of the Gut Mucus

Due to mucin's important protective effect on epithelial tissue, it has garnered extensive attention. The role played by mucus in the digestive tract is undeniable. On the one hand, mucus forms "biofilm" structures that insulate harmful substances from direct contact with epithelial cells. On the other hand, a variety of immune molecules in mucus play a crucial role in the immune regulation of the digestive tract. Due to the enormous number of microorganisms in the gut, the biological properties of mucus and its protective actions are more complicated. Numerous pieces of research have hinted that the aberrant expression of intestinal mucus is closely related to impaired intestinal function. Therefore, this purposeful review aims to provide the highlights of the biological characteristics and functional categorization of mucus synthesis and secretion. In addition, we highlight a variety of the regulatory factors for mucus. Most importantly, we also summarize some of the changes and possible molecular mechanisms of mucus during certain disease processes. All these are beneficial to clinical practice, diagnosis, and treatment and can provide some potential theoretical bases. Admittedly, there are still some deficiencies or contradictory results in the current research on mucus, but none of this diminishes the importance of mucus in protective impacts.

Poria cocos oligosaccharides ameliorate dextran sodium sulfate-induced colitis mice by regulating gut microbiota dysbiosis

Poria cocos, a widely accepted function food in China, has multiple pharmacological activities. This study aimed to investigate the therapeutic effect and molecular mechanism of Poria cocos oligosaccharides (PCOs) against dextran sodium sulfate (DSS)-induced mouse colitis. In this study, BALB/c mice were treated with 3% (w/v) DSS for seven days to establish a colitis model. The results showed that oral administration of PCOs (200 mg per kg per day) significantly reversed the changes in the physiological indices in colitis mice, including body weight, disease activity index scores (DAI), spleen index, and colon length. From the qRT-PCR assay, it was observed that PCOs suppressed the mRNA expression of pro-inflammatory cytokines, such as Tnf-α, Il-1β, and Il-6. In addition, PCOs protected the intestinal barrier from damage by promoting the expression of mucins and tight junction proteins at both mRNA and protein levels. Upon 16S rDNA sequencing, it was observed that PCO treatment partly reversed the changes in the gut microbiota of colitis mice by selectively regulating the abundance of specific bacteria. And Odoribacter, Muribaculum, Desulfovibrio, Oscillibacter, Escherichia-Shigella, and Turicibacter might be the critical bacteria in improving colitis via PCOs. Finally, using antibiotic mixtures to destroy the intestinal bacteria, we documented that PCO fermentation broth (PCO FB) instead of PCOs prevented the occurrence of colitis in gut microbiota-depleted mice. In conclusion, PCOs showed a protective effect on colitis by reversing gut microbiota dysbiosis. Our study sheds light on the potential application of PCOs as a prebiotic for treating colitis.

Sanhuang Xiexin decoction ameliorates DSS-induced colitis in mice by regulating intestinal inflammation, intestinal barrier, and intestinal flora

ETHNOPHARMACOLOGICAL RELEVANCE

Sanhuang Xiexin decoction (SXD) is a widely applicated traditional Chinese medicine (TCM) with a significant intestinal anti-inflammatory effect.

AIM OF THE STUDY

To evaluate the therapeutic effect and elucidate the possible underlying mechanisms of SXD on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice.

METHODS

To model UC, 3% DSS was added to the drinking water for 7 days. The UC mice were grouped and treated with three doses of SXD (1.3, 2.6, and 6 g/kg) orally for 7 days. Mice body weight and disease activity index (DAI) scores were recorded daily. After treatment with SXD, the colon was removed, and the colon length and histopathological changes were recorded. Blood cells were counted and colonic inflammatory cytokines and oxidative stress indicators were examined. The key proteins in TLR4-MyD88-NF-κB signaling and the colonic barrier were determined by Western blot analysis. The restorative effect of SXD on intestinal flora was determined.

RESULTS

Treatment with SXD reduced DAI scores, increased body weight, improved colon shortening, and decreased colonic damage. SXD decreased the numbers of white blood cells (WBCs), increased the numbers of red blood cells (RBCs), and inhibited the expression of inflammatory cytokines and oxidative stress indicators. In addition, SXD displayed an effective anti-inflammatory effect by inhibiting the expression levels of p-IκBα, TLR4, MyD88, and p65. Furthermore, SXD significantly restored the integrity of the colonic barrier and the abundance of beneficial flora.

CONCLUSIONS

SXD significantly reduced DSS-induced colon damage when the dose was higher than 1.3 g/kg, and the middle dose group (2.6 g/kg) indicated the best effect. SXD effectively ameliorated DSS-induced UC in mice, possibly by inhibiting oxidative stress, protecting the mucosal barrier, inhibiting the TLR4-MyD88-NF-κB signaling pathway, and regulating the intestinal flora.

Aberrant Mucin Expression Profiles Associate With Pediatric Inflammatory Bowel Disease Presentation and Activity

BACKGROUND

Intestinal mucosal healing is nowadays preferred as the therapeutic endpoint in inflammatory bowel disease (IBD), but objective measurements at the molecular level are lacking. Because dysregulated mucin expression is suggested to be involved in mucosal barrier dysfunction in IBD, we investigated mucin expression in association with barrier mediators and clinical characteristics in colonic tissue of a pediatric IBD population.

METHODS

In this cross-sectional monocentric study, we quantified messenger RNA (mRNA) expression of mucins, intercellular junctions, and cell polarity complexes in inflamed and noninflamed colonic biopsies from pediatric IBD (n = 29) and non-IBD (n = 15) patients. We then validated mucin expression at protein level and correlated mucin mRNA expression with expression of barrier mediators and clinical data.

RESULTS

The expression of MUC1, MUC3A, MUC4, and MUC13 was increased in the inflamed colon of pediatric IBD patients compared with the noninflamed colon of non-IBD control subjects. Especially MUC13 mRNA expression associated with the expression of barrier mediators, including CDH1, OCLN, and TJP2. MUC1 and MUC3B mRNA expression in combination with calprotectin levels most accurately discriminated IBD patients from non-IBD control subjects (90.6% area under the receiver-operating characteristic curve [AUCROC], 92.0% sensitivity, 73.7% specificity), whereas aberrant mRNA expression of MUC1, MUC3A, MUC4, and MUC13 was distinctive for ulcerative colitis and of MUC3B for Crohn's disease. Furthermore, expression of MUC3A, MUC3B, and MUC4 correlated with clinical disease activity (ie, Pediatric Ulcerative Colitis Activity Index and Pediatric Crohn's Disease Activity Index), and of MUC1, MUC2, MUC4, and MUC13 with endoscopic colitis severity in ulcerative colitis patients.

CONCLUSIONS

Colonic mucin expression is disturbed in pediatric IBD patients and associates with disease activity and presentation, suggesting its use as molecular marker to aid in disease diagnosis and management.

Colon mucus in colorectal neoplasia and beyond

Little was known about mammalian colon mucus (CM) until the beginning of the 21^st century. Since that time considerable progress has been made in basic research addressing CM structure and functions. Human CM is formed by two distinct layers composed of gel-forming glycosylated mucins that are permanently secreted by goblet cells of the colonic epithelium. The inner layer is dense and impenetrable for bacteria, whereas the loose outer layer provides a habitat for abundant commensal microbiota. Mucus barrier integrity is essential for preventing bacterial contact with the mucosal epithelium and maintaining homeostasis in the gut, but it can be impaired by a variety of factors, including CM-damaging switch of commensal bacteria to mucin glycan consumption due to dietary fiber deficiency. It is proven that impairments in CM structure and function can lead to colonic barrier deterioration that opens direct bacterial access to the epithelium. Bacteria-induced damage dysregulates epithelial proliferation and causes mucosal inflammatory responses that may expand to the loosened CM and eventually result in severe disorders, including colitis and neoplastic growth. Recently described formation of bacterial biofilms within the inner CM layer was shown to be associated with both inflammation and cancer. Although obvious gaps in our knowledge of human CM remain, its importance for the pathogenesis of major colorectal diseases, comprising inflammatory bowel disease and colorectal cancer, is already recognized. Continuing progress in CM exploration is likely to result in the development of a range of new useful clinical applications addressing colorectal disease diagnosis, prevention and therapy.

Pectolinarigenin Suppresses LPS-Induced Inflammatory Response in Macrophages and Attenuates DSS-Induced Colitis by Modulating the NF-κB/Nrf2 Signaling Pathway

Pectolinarigenin (PEC), a natural flavonoid present in cirsium chanroenicum and citrus fruits, has possess the distinct pharmacological activities. However, its molecular mechanisms and pharmacological effects on intestinal illness have not been elucidated. In the present study, we investigated the potential beneficial effects of pectolinarigenin (PEC) on lipopolysaccharide (LPS)-induced macrophage cells and the dextran sulfate sodium (DSS)-induced colitis model. Our findings showed that PEC pretreatment inhibits the LPS-induced nuclear factor-kappa B (NF-κB) activation by interfering with the degradation of IκB-α. Further, increased Nrf2 protein expression was reported on PEC treated RAW 264.7 and THP1 cell lines. In addition, we revealed that PEC mediated the NF-κB/Nrf2 pathway regulation, which in turn inhibits the synthesis of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), interleukin-1beta (IL-1β), and tumor necrosis factor-alpha (TNF-α) on RAW 264.7 and THP1 cells. Furthermore, PEC dose-dependently reduced the DSS-induced inflammation in the colon by regulating NF-κB/Nrf2 signaling pathway and enhancing the myeloperoxidase (MPO) activity and redox regulators such as superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and lipid peroxidation byproduct malondialdehyde (MDA) in DSS-induced inflamed colon. Similarly, we reported the minimal pathological damages in the PEC-treated mice colon, as well as increase goblet cell population and mucin-2 production. In conclusion, our findings demonstrate that PEC reduces the DSS-induced colitis in mice by regulating the NF-κB/Nrf2 pathway. Thus, PEC might be a promising therapeutic agent for the treatment of inflammatory bowel disease.

The Role and Function of Mucins and Its Relationship to Inflammatory Bowel Disease

Mucus is present throughout the gastrointestinal tract and is essential for regulating gut microbiota homeostasis and preventing disease by protecting the gastrointestinal barrier from microorganisms, pathogens and toxins or other irritants. Mucin (MUC)-2 is a secreted protein produced by epithelial goblet cells as the main component of mucus. Defects in the gastrointestinal tract, such as inflammation and ulcers, cause damage to the mucus barrier, which can worsen mucus quality and reduce mucus production. Therefore, we would like to review the characteristics of MUC2 and its role in intestinal disorders and highlight the importance of further studies. We also investigated whether the role of MUC2 differs between children and adults, ulcerative colitis (UC) and Crohn's disease (CD).

The genomic landscape of Cronkhite-Canada syndrome: Possible clues for pathogenesis

OBJECTIVES

Cronkhite-Canada syndrome (CCS) is a rare hamartomatous polyposis syndrome with a proposed association with chronic autoimmune inflammation. To date, genetic background of patients with CCS remains less investigated. In this study we aimed to explore the genomic landscape of CCS.

METHODS

Whole exome sequencing was performed on peripheral blood samples extracted from 18 patients with CCS. Potential function-impacting germline variants were filtered by R software. Through systematic data analysis, a number of genetic variants were identified. Enrichment analysis was performed using the R package ClusterProfiler.

RESULTS

Overall, 3960 low-frequency (<0.05 or not reported in the Exome Aggregation Consortium East Asian, 1000 Genomes, or ESP6500 database) potentially function-impacting germline variants were identified, with 18 genes (FDFT1, LOC400863, MUC3A, MUC4, ZNF806, GXYLT1, MUC6, PABPC3, PSPH, ZFPM1, CIC, LOC283710, ARSD, GOLGA6L2, LOC388282, SLC25A5, TMEM247, WDR89) involved over half the patients. Functional enrichment of these genes revealed several biological processes in relation to innate immune responses and glycosylation. Only one likely pathogenic germline variant of an hamartomatous polyposis syndrome-associated gene, PTCH1, was detected in one patient.

CONCLUSIONS

CCS has genomic alteration patterns completely distinct from those of traditional hamartomatous polyposis syndrome. The germline mutation landscape indicates potential roles of innate immune responses and glycosylation in the pathogenesis of CCS.

Three important short-chain fatty acids (SCFAs) attenuate the inflammatory response induced by 5-FU and maintain the integrity of intestinal mucosal tight junction

BACKGROUND

5-Fluorouracil (5-FU) is a used chemotherapy drug for cancer, and its main side effect is intestinal mucositis which causes chemotherapy to fail. It was known that short-chain fatty acids (SCFAs) can inhibit immune cell release of various proinflammatory factors and inhibit excessive intestinal inflammation. However, the inhibitory effect of SCFAs on 5-FU-induced intestinal mucositis is still unclear.

RESULTS

To simulate the effects of SCFAs on immune and intestinal epithelial cells, the cells (THP-1 cells and Caco-2 cells) were pretreated with sodium acetate (NaAc), sodium propionate (NaPc) and sodium butyrate (NaB), then inflammation was induced by 5-FU. The expressions of reactive oxygen species (ROS), Beclin-1, LC3-II, NF-κB p65, NLRP3 inflammasome, proinflammatory/anti-inflammatory cytokines and mucosal tight junction proteins were determined. In our results, the three SCFAs could inhibit ROS expressions, NLRP3, Caspase-1, IL-1β, IL-6, IL-18, Beclin-1 and LC3-II, when induced by 5-FU. In a 5-FU-induced chemoentermuctis mouse model, Lactobacillus rhamnoides can increase the concentrations of three SCFAs in faeces and increase the concentrations of IL-1β, IL-6 and IgA in serum, and decrease the expressions of NLRP3 and IL-17 in spleen cells. The expressions of ZO-1 and Occludin in intestinal mucosa were significantly increased.

CONCLUSIONS

These results indicated that the three SCFAs can effectively suppress the inflammation of THP-1 cells and Caco-2 cells and maintain tight junction integrity in intestinal mucosal epithelial cells.

Characterization of mucin gene expression and goblet cell proportion in inflammatory colorectal polyps in miniature dachshunds

Hyperplastic goblet cells and abundant mucus are significant characteristics of inflammatory colorectal polyps (ICRPs) in miniature dachshunds. In this study, selected mucin gene expressions and goblet cell proportions were evaluated in miniature dachshunds with ICRPs and in healthy dogs. Mucin 2 (MUC2) gene expression was not significantly different among the groups, whereas mucin 5AC (MUC5AC) gene expression was significantly higher in the polypoid lesions than in healthy colonic mucosa. Although the percentage of goblet cells in the upper crypt regions did not significantly differ between the groups, that in the lower crypt regions was significantly decreased in polypoid lesions. In conclusion, increased MUC5AC gene expression and goblet cell proportion changes may be associated with the pathogenesis of ICRPs.

Mucins Dynamics in Physiological and Pathological Conditions

Maintaining intestinal health requires clear segregation between epithelial cells and luminal microbes. The intestinal mucus layer, produced by goblet cells (GCs), is a key element in maintaining the functional protection of the epithelium. The importance of the gut mucus barrier is highlighted in mice lacking Muc2, the major form of secreted mucins. These mice show closer bacterial residence to epithelial cells, develop spontaneous colitis and became moribund when infected with the attaching and effacing pathogen, Citrobacter rodentium. Furthermore, numerous observations have associated GCs and mucus layer dysfunction to the pathogenesis of inflammatory bowel disease (IBD). However, the molecular mechanisms that regulate the physiology of GCs and the mucus layer remain obscured. In this review, we consider novel findings describing divergent functionality and expression profiles of GCs subtypes within intestinal crypts. We also discuss internal (host) and external (diets and bacteria) factors that modulate different aspects of the mucus layer as well as the contribution of an altered mucus barrier to the onset of IBD.

Therapeutic potential of isobavachalcone, a natural flavonoid, in murine experimental colitis by inhibiting NF-κB p65

The incidence of ulcerative colitis (UC), one of the two types of inflammatory bowel disease, is increasing in many countries. Various natural products have been demonstrated with therapeutic potentials for UC. Herein, the therapeutic effects and mechanisms of isobavachalcone (IBC), a natural chalcone, were evaluated in dextran sulfate sodium (DSS)-induced colitis mice and lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. The results demonstrated that IBC treatment significantly improved the clinical symptoms, assessed by the disease activity index (DAI) scores and the histological changes of the colon. The levels of myeloperoxidase (MPO), TNF-α, IL-6, IL-1β, and prostaglandin E2 (PGE2) in colon tissues were suppressed by IBC. The upregulation of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and NF-κB p65 in colon tissues were reversed by IBC as well. Furthermore, IBC significantly inhibited LPS-triggered secretion of TNF-α, IL-6, and nitrite, and nuclear translocation of NF-κB p65, in RAW264.7 cells. The luciferase reporter assay indicated that IBC significantly inhibited LPS-triggered transcription of toll-like receptor 4 (TLR4). Molecular docking results showed that the binding pocket of IBC was adjacent to Ser276 of p65-p50 heterodimer and IBC could form H-bond with Thr191. Collectively, these results demonstrated that IBC ameliorated colitis in mice possibly through inhibition of NF-κB p65.

Mucin in cancer: a stealth cloak for cancer cells

Mucins are high molecular-weight epithelial glycoproteins and are implicated in many physiological processes, including epithelial cell protection, signaling transduction, and tissue homeostasis. Abnormality of mucus expression and structure contributes to biological properties related to human cancer progression. Tumor growth sites induce inhospitable conditions. Many kinds of research suggest that mucins provide a microenvironment to avoid hypoxia, acidic, and other biological conditions that promote cancer progression. Given that the mucus layer captures growth factors or cytokines, we propose that mucin helps to ameliorate inhospitable conditions in tumor-growing sites. Additionally, the composition and structure of mucins enable them to mimic the surface of normal epithelial cells, allowing tumor cells to escape from immune surveillance. Indeed, human cancers such as mucinous carcinoma, show a higher incidence of invasion to adjacent organs and lymph node metastasis than do non-mucinous carcinoma. In this mini-review, we discuss how mucin provides a tumor-friendly environment and contributes to increased cancer malignancy in mucinous carcinoma.

Exploring Mucin as Adjunct to Phage Therapy

Conventional phage therapy using bacteriophages (phages) for specific targeting of pathogenic bacteria is not always useful as a therapeutic for gastrointestinal (GI) dysfunction. Complex dysbiotic GI disorders such as small intestinal bowel overgrowth (SIBO), ulcerative colitis (UC), or Crohn’s disease (CD) are even more difficult to treat as these conditions have shifts in multiple populations of bacteria within the microbiome. Such community-level structural changes in the gut microbiota may require an alternative to conventional phage therapy such as fecal virome transfer or a phage cocktail capable of targeting multiple bacterial species. Additionally, manipulation of the GI microenvironment may enhance beneficial bacteria–phage interactions during treatment. Mucin, produced along the entire length of the GI tract to protect the underlying mucosa, is a prominent contributor to the GI microenvironment and may facilitate bacteria–phage interactions in multiple ways, potentially serving as an adjunct during phage therapy. In this review, we will describe what is known about the role of mucin within the GI tract and how its facilitation of bacteria–phage interactions should be considered in any effort directed at optimizing effectiveness of a phage therapy for gastrointestinal dysbiosis.

Mucins in Intestinal Mucosal Defense and Inflammation: Learning From Clinical and Experimental Studies

Throughout the gastrointestinal (GI) tract, a distinct mucus layer composed of highly glycosylated proteins called mucins plays an essential role in providing lubrication for the passage of food, participating in cell signaling pathways and protecting the host epithelium from commensal microorganisms and invading pathogens, as well as toxins and other environmental irritants. These mucins can be broadly classified into either secreted gel-forming mucins, those that provide the structural backbone for the mucus barrier, or transmembrane mucins, those that form the glycocalyx layer covering the underlying epithelial cells. Goblet cells dispersed among the intestinal epithelial cells are chiefly responsible for the synthesis and secretion of mucins within the gut and are heavily influenced by interactions with the immune system. Evidence from both clinical and animal studies have indicated that several GI conditions, including inflammatory bowel disease (IBD), colorectal cancer, and numerous enteric infections are accompanied by considerable changes in mucin quality and quantity. These changes include, but are not limited to, impaired goblet cell function, synthesis dysregulation, and altered post-translational modifications. The current review aims to highlight the structural and functional features as well as the production and immunological regulation of mucins and the impact these key elements have within the context of barrier function and host defense in intestinal inflammation.

The role of MUC2 mucin in intestinal homeostasis and the impact of dietary components on MUC2 expression

MUC2 mucin is an important secretory protein found in the human gut. Recent studies indicated that MUC2 mucin plays a role in the protection of gut barrier, the regulation of microbiome homeostasis and the prevention of diseases. In this review, the physiological properties of MUC2 mucin and its interactions with the intestinal microbiome are firstly discussed. Its roles in intestinal diseases including inflammatory bowel disease, colorectal cancer and parasitic infections are concluded. We also reviewed dietary components known to have modulative effects on MUC2 mucin expression, such as polysaccharides, amino acids and polyphenols.

IL-8 and LYPD8 expression levels are associated with the inflammatory response in the colon of patients with ulcerative colitis

Ulcerative colitis (UC) is an idiopathic chronic inflammatory disorder affecting the large intestine, which may involve mucosal degeneration. Glycoproteins, mucin2 (MUC2) and the LY6/PLAUR domain containing 8 (LYPD8) are present on the mucous layer of the colon and can hinder the invasion of bacteria, thus contributing to the prevention of colitis. The present study investigated the expression levels of interleukin-8 (IL-8), MUC2 and LYPD8 on the mucous membranes of patients with UC. A total of 18 patients with UC (6 females and 12 males) were examined. Biopsies of the lesions as well as matching normal membranes were obtained and the mRNA expression levels of IL-8, MUC2 and LYPD8 were compared. LYPD8 expression was downregulated in the lesions and the relapsing-remitting subtype of lesions was associated with higher levels of MUC2 expression compared with single attack and chronic lesions subtypes. A positive correlation between Matts' histopathological grade and IL-8, as well as a negative correlation between Matts' histopathological grade and LYPD8 were observed. The expression levels of LYPD8 were lower in highly active lesions and these levels decreased according to the intensity of the mucosal inflammation. Conversely, an increase in MUC2 expression levels may reflect the recovery of the outer mucus layer in the remission phase. Therefore, the examination of MUC2 and LYPD8 expression levels may be useful indicators of mucosal healing in patients with UC.

Mucin glycoproteins block apoptosis; promote invasion, proliferation, and migration; and cause chemoresistance through diverse pathways in epithelial cancers

Overexpression of mucin glycoproteins has been demonstrated in many epithelial-derived cancers. The significance of this overexpression remains uncertain. The aim of this paper was to define the association of mucin glycoproteins with apoptosis, cell growth, invasion, migration, adhesion, and clonogenicity in vitro as well as tumor growth, tumorigenicity, and metastasis in vivo in epithelial-derived cancers by performing a systematic review of all published data. A systematic review of PubMed, Embase, and the Cochrane Central Register of Controlled Trials was performed to identify all papers that evaluated the association between mucin glycoproteins with apoptosis, cell growth, invasion, migration, adhesion, and clonogenicity in vitro as well as tumor growth, tumorigenicity, and metastasis in vivo in epithelial-derived cancers. PRISMA guidelines were adhered to. Results of individual studies were extracted and pooled together based on the organ in which the cancer was derived from. The initial search revealed 2031 papers, of which 90 were deemed eligible for inclusion in the study. The studies included details on MUC1, MUC2, MUC4, MUC5AC, MUC5B, MUC13, and MUC16. The majority of studies evaluated MUC1. MUC1 overexpression was consistently associated with resistance to apoptosis and resistance to chemotherapy. There was also evidence that overexpression of MUC2, MUC4, MUC5AC, MUC5B, MUC13, and MUC16 conferred resistance to apoptosis in epithelial-derived cancers. The overexpression of mucin glycoproteins is associated with resistance to apoptosis in numerous epithelial cancers. They cause resistance through diverse signaling pathways. Targeting the expression of mucin glycoproteins represents a potential therapeutic target in the treatment of epithelial-derived cancers.

Decreased expression of MUC2 due to a decrease in the expression of lectins and apoptotic defects in colitis patients

INTRODUCTION

The involvement of mucin, lectin, and apoptosis in colitis is still unclear. This study aimed to investigate changes in MUC2 expression, inflammation, and changes in lectin expression in colitis patients.

METHODS

A total of 17 patients were divided into two groups including 11 hemorrhoid patients as a control group and 6 colitis patients. MUC2 mutation analysis was carried out using immunofluorescent and FISH techniques. Assessment of caspase-3, Ki-67, NF-kB, and lectin expressions was also carried out by immunofluorescent technique then analyzed by confocal laser scanning microscope.

RESULTS

The MUC2, caspase-3, and lectin expressions were significantly lower in the colitis group than in the control group (p < 0.05).

CONCLUSIONS

It was concluded that in colitis there was a change in MUC2 expression due to changes in lectins accompanied by apoptotic defects.conclusion.

Impact of Genes and the Environment on the Pathogenesis and Disease Course of Inflammatory Bowel Disease

Crohn's disease and ulcerative colitis constitute two major subgroups of inflammatory bowel diseases (IBD), a group of complex polygenic diseases characterized by chronic and progressive inflammation in the gastrointestinal tract. In recent years, methodological advances in genetic analysis have greatly expanded our understanding of the genetic background of IBD. So far, more than 240 genetic risk loci have been identified for IBD. However, these risk alleles explain less than 30% of the susceptibility to disease development, suggesting that environmental factors contribute considerably. The increasing occurrence of IBD in Eastern countries following their 'westernization', as well as the increased risk of disease among those who migrate to high-incidence regions, also suggest that the environment is key in the pathogenesis of IBD. In this review, we summarize the current evidence on the role of genetic and environmental factors in the susceptibility to, and disease course of, IBD, and we suggest how these findings might be applied to clinical practice.

Mucoadhesive role of tamarind xyloglucan on inflammation attenuates ulcerative colitis

Tamarind xyloglucan (TXG) is edible, bioavailable and mucoadhesive polysaccharide. The aim of this study was (i) to investigate molecular docking studies on the interaction of TXG to MUC1 and cytokine receptors and (ii) to assess the mucoadhesive role of TXG in UC. In vivo study: C57Bl6 mice were administered with DSS 3% (w/v) in drinking water; TXG 100 or 300 mg/kg/day was given orally for 7 days simultaneously. TXG consistently binds to MUC1 and cytokine receptors in molecular docking studies. TXG decreased the expression of MUC1 and MUC2. The mucoadhesive ability of TXG decreased IL-1β and IL-6 levels. Furthermore, TXG decreased the expression of TLR4, MyD88, I-κB and NF-κB thereby attenuating inflammation via TLR4/NF-κB signaling pathway. TXG mucoadhesion to MUC1 played a pivotal role in attenuating inflammation. To conclude, the mucoadhesive role of TXG is important in the attenuation of inflammation and healing of UC.