Discoidin domain receptor 1(DDR1) promote intestinal barrier disruption in Ulcerative Colitis through tight junction proteins degradation and epithelium apoptosis

The E3 ubiquitin ligase MARCH2 controls TNF-α mediated inflammation by autoubiquitination

BACKGROUND

Regulation of the nuclear factor-kappa B (NF-kB) signaling pathway is a major host homeostatic mechanism for controlling hyper-inflammation or chronic inflammation. Despite extensive research, the regulatory factors of NF-kB signaling required to preserve homeostasis and control inflammatory disorders are not fully understood. Moreover, the role of MARCH2 in chronic inflammation models and the regulation of MARCH2 activation remain to be elucidated.

METHODS

We monitored disease severity and mortality in MARCH2-/- or MARCH2+/+ mice induced experimental colitis. Susceptibility to DSS-induced experimental colitis was determined by various methods, including Swiss roll assay and fluorescein isothiocyanate (FITC)-dextran treatment, respectively. RNA-sequencing was conducted to recognize the inflammatory response-related genes in the distal colon of colitis-induced mice. Enzyme-linked immunosorbent assay (ELISA) was used to measure the cytokines and chemokines with in vitro and in vivo samples. Affinity purification and LC-MS/MS analysis were used to identify the MARCH2 interacting proteins and posttranslational modifications. The underlying mechanism was elucidated using immunoblotting, co-immunoprecipitation, ubiquitination assay, and confocal microscopy.

RESULT

Here, we report that MARCH2-/- mice were more susceptible to experimental inflammatory bowel disease (IBD) due to the massive production of cytokines. Stimulation by inflammatory cytokines such as TNF induces dimerization of MARCH2 at a later stage and dimerized MARCH2 undergoes K63-linked autoubiquitination at lysine 127 and 238, which promotes NEMO recognition, ubiquitination and proteasomal degradation. We also show an interaction between MARCH2 and MARCH8 in resting cells that inhibits MARCH2 activation. Taken together, these findings provide new insights into the molecular mechanism of MARCH2 and suggest a crucial role of MARCH2 in the modulation of inflammation and cellular homeostasis.

CONCLUSION

Our results indicate that MARCH2 plays a critical role in regulating NEMO/IKKγ under the inflammatory and resting conditions, thereby suppressing excessive or unexpected inflammatory responses. Our findings here not only demonstrate a biological role of MARCH2 in inflammatory signaling pathways but also provide a novel insight in the underlying mechanism.

Reducing severity of inflammatory bowel disease through colonization of Lactiplantibacillus plantarum and its extracellular vesicles release

Inflammatory bowel disease (IBD) is characterized by compromised intestinal barrier function and a lack of effective treatments. Probiotics have shown promise in managing IBD due to their ability to modulate the gut microbiota, enhance intestinal barrier function, and exert anti-inflammatory effects. However, the specific mechanisms through which probiotics exert these therapeutic effects in IBD treatment remain poorly understood. Our research revealed a significant reduction of Lactiplantibacillus plantarum (L. plantarum) in the gut microbiota of IBD patients. L. plantarum is a well-known probiotic strain in the list of edible probiotics, recognized for its beneficial effects on gut health, including its ability to strengthen the intestinal barrier and reduce inflammation. We demonstrated that supplementation with L. plantarum could alleviate IBD symptoms in mice, primarily by inhibiting apoptosis in intestinal epithelial cells through L. plantarum's bacterial extracellular vesicles (L. plant-EVs). This protective effect is dependent on the efficient uptake of L. plant-EVs by intestinal cells. Intriguingly, watermelon enhances L. plantarum colonization and L. plant-EVs release, further promoting intestinal barrier repair. Our findings contribute to the understanding of L. plant-EVs in the probiotic-based therapeutic approach for IBD, as they are promising candidates for nanoparticle-based therapeutic methods that are enhanced by natural diets such as watermelon. This study thereby offers a potential breakthrough in the management and treatment of IBD.

Elevated SPARC Disrupts the Intestinal Barrier Integrity in Crohn's Disease by Interacting with OTUD4 and Activating the MYD88/NF-κB Pathway

Disruption of the intestinal epithelial barrier results in increased permeability and is a key factor in the onset and progression of Crohn's disease (CD). The protein SPARC is primarily involved in cell interaction and migration, but its specific role in the intestinal epithelial barrier remains unclear. This study demonstrates that SPARC is significantly overexpressed in both CD patients and murine models of colitis. Furthermore, mice deficient in SPARC exhibits resistance to chemically induced colitis, a phenomenon associated with the modulation of barrier-associated proteins. Mechanistically, it is elucidated that SPARC competitively binds to OTUD4 in conjunction with MYD88, facilitating the translocation of p65 from the cytoplasm to the nucleus and subsequent activation of the p65-MLCK/MLC2 pathway, thereby compromising barrier integrity. Additionally, it is identified that the elevated expression of SPARC in CD is regulated via the METTL3-YTHDF1 axis. These findings indicate that SPARC levels are elevated in patients with CD and in colitis-induced mice, leading to intestinal barrier damage through direct interaction with OTUD4 and subsequent activation of the MYD88/p65/MLCK/MLC2 signaling pathway. Consequently, targeting SPARC or the OTUD4/MYD88/p65/MLCK/MLC2 axis may offer novel insights into the molecular mechanisms underlying CD and represent a potential therapeutic strategy.

Helicobacter hepaticus CdtB Triggers Colonic Mucosal Barrier Disruption in Mice via Epithelial Tight Junction Impairment Mediated by MLCK/pMLC2 Signaling Pathway

Background:Helicobacter hepaticus (H. hepaticus) has been demonstrated to have clinical relevance to the development of colitis in rodents. H. hepaticus produces cytolethal distending toxins (CDTs), which are identified as the most important virulence factors to the pathogenicity of CDT-producing bacteria in animals. However, the precise relationship between CDTs of H. hepaticus and intestinal barrier dysfunction remains unclear. The objective of the present study was to ascertain the impact of CdtB, the active subunit of CDTs, on the colonic mucosal barrier during H. hepaticus infection. Materials and Methods: We investigated the infection of male BALB/c mice, intestinal organoids, and IEC-6 cell monolayers by H. hepaticus or CdtB-deficient H. hepaticus (ΔCdtB). A comprehensive histopathological examination was conducted, encompassing the assessment of H. hepaticus colonization, the levels of mRNA expression for inflammatory cytokines, the expression levels of tight junction proteins, and the related signaling pathways. Results: The results demonstrate that the presence of ΔCdtB led to a mitigation of the symptoms associated with H. hepaticus-induced colitis, as evidenced by colon length shortening and the colon histological inflammation score. In addition, the levels of pro-inflammatory cytokines were reduced in the ΔCdtB group. Moreover, a downward trend was observed in the phosphorylation levels of STAT3 and nuclear factor-κB (p65). In vitro, the presence of H. hepaticus resulted in a reduction in the expression of tight junction (TJ) markers (ZO-1 and occludin) and an impairment of the F-actin structure in either the intestinal epithelium or intestinal organoids. However, these effects were reversed by CdtB deletion. Concurrently, both ROS levels and apoptosis levels were found to be significantly reduced in cells treated with the ΔCdtB strain. Mechanistically, myosin light chain kinase (MLCK) activation was observed in the H. hepaticus-infected group in vivo, whereas the MLCK inhibitor ML-7 was found to reverse the CdtB-induced alterations in TJ proteins in IEC6 cells. Conclusions: The collective findings demonstrate that CdtB plays a pivotal role in the H. hepaticus-induced colonic mucosal barrier. This is achieved through the regulation of TJs via the MLCK/pMLC2 signaling pathway, which is linked to elevations in oxidative stress and inflammation within intestinal epithelial cells.

Identification of DDR1 Inhibitors from Marine Compound Library Based on Pharmacophore Model and Scaffold Hopping

Ulcerative colitis (UC) is a chronic inflammatory condition that affects the intestines. Research has shown that reducing the activity of DDR1 can help maintain intestinal barrier function in UC, making DDR1 a promising target for treatment. However, the development of DDR1 inhibitors as drugs has been hindered by issues such as toxicity and poor binding stability. As a result, there are currently no DDR1-targeting drugs available for clinical use, highlighting the need for new inhibitors. In a recent study, a dataset of 85 DDR1 inhibitors was analyzed to identify key characteristics for effective inhibition. A pharmacophore model was constructed and validated to screen a library of marine natural products for potential DDR1 inhibitors. Through high-throughput virtual screening and precise docking, 17 promising compounds were identified from a pool of over 52,000 molecules in the marine database. To improve binding affinity and reduce potential toxicity, scaffold hopping was employed to modify the 17 compounds, resulting in the generation of 1070 new compounds. These new compounds were further evaluated through docking and ADMET analysis, leading to the identification of three compounds-39713a, 34346a, and 34419a-with superior predicted activity and drug-like properties compared to the original 17 compounds. Further analysis showed that the binding free energy values of the three candidate compounds were less than -12.200 kcal/mol, which was similar to or better than -12.377 kcal/mol of the known positive compound VU6015929, and the drug-like properties were better than those of the positive compounds. Molecular dynamics simulations were then conducted on these three candidate compounds, confirming their stable interactions with the target protein. In conclusion, compounds 39713a, 34346a, and 34419a show promise as potential DDR1 inhibitors for the treatment of ulcerative colitis.

Wolfberry Honey and Its Extract Alleviate Dextran Sodium Sulfate-Induced Ulcerative Colitis by Improving Intestinal Barrier Function and Reducing Oxidative Stress and Inflammation

Inflammatory bowel disease (IBD) is a chronic condition characterized by gut inflammation causing persistent diarrhea and abdominal pain. Despite the nutritional benefits of wolfberry honey (from Lycium barbarum L.), its potential to alleviate IBD remains underexplored. This study evaluated the protective effects of wolfberry honey and its extract (wolfberry honey extract [WHE]) against dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) using in vivo and in vitro models. Mice pretreated with wolfberry honey showed significant symptom improvement in DSS-induced UC, linked to reduced expression of proinflammatory markers (Il-1β, Il-6, Tnf-α, and Mcp-1) and increased antioxidant genes (Nrf2, Sod2). Increased Occludin levels indicated improved intestinal barrier function. In vitro, WHE protected DSS-treated Caco-2 cells by lowering reactive oxygen species (ROS), stabilizing mitochondrial membrane potential, and inhibiting TLR4/NF-κB signaling. It enhanced the expression of antioxidant genes and tight junction proteins (ZO-1, Occludin, and Claudin-1). Metabolomic analysis revealed that WHE modulated glycerophospholipid metabolism, increasing phosphatidylcholine and choline levels and decreasing lysophosphatidylcholine levels. These results highlight the potential of wolfberry honey and its extract as nutraceuticals for managing UC through their effects on inflammation, oxidative stress, and intestinal barrier function. Further research is warranted to elucidate their mechanisms of action and assess their long-term therapeutic benefits in IBD management.

Downregulated KLF4, induced by m6A modification, aggravates intestinal barrier dysfunction in inflammatory bowel disease

BACKGROUND

Krüppel-like factor 4 (KLF4), a transcription factor, is involved in various biological processes. However, the role of KLF4 in regulating the intestinal epithelial barrier (IEB) in inflammatory bowel disease (IBD) and its mechanism have not been extensively studied.

METHODS

KLF4 expression in IBD patients and colitis mice was analyzed using Gene Expression Omnibus(GEO) database, immunohistochemistry (IHC) and Western blot. The roles of KLF4 in IEB and colitis symptoms were verified in dextran sulfate sodium (DSS)-induced and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis model mice using an adenovirus carrying KLF4 shRNA (shKLF4-Adv). Furthermore, the influence of KLF4 on trans-epithelium electrical resistance (TEER), paracellular permeability, apical junction complex (AJC) protein expression and apoptosis was assessed in vitro and in vivo. MeRIP and RIP assays were used to verify the effects of m6A modification on KLF4 expression.

RESULTS

KLF4 expression was significantly decreased in IBD patients and was negatively associated with inflammatory features. KLF4 deletion aggravated colitis symptoms and IEB injuries by reducing AJC protein expression and increasing apoptosis in mice with colitis. Furthermore, KLF4 transcriptionally regulated the expression of AJC proteins and inhibited apoptosis by reducing cellular ROS levels and proinflammatory cytokine expression. Moreover, we observed that METTL3/ALKBH5/YTHDF2-mediated m6A modification led to a decrease in KLF4 expression in Caco-2 cells. In addition, APTO-253, an inducer of KLF4, exhibited a synergistic effect with mesalazine on IEB function.

CONCLUSIONS

Our study demonstrated that KLF4 is a crucial regulator of IEB, suggesting that targeting KLF4 may be a promising therapeutic alternative for IBD.

Advances in research on the role of high carbohydrate diet in the process of inflammatory bowel disease (IBD)

Inflammatory bowel disease (IBD) is a chronic, systemic gastrointestinal disorder characterized by episodic inflammation that requires life-long management. Although the etiology of IBD is not fully understood, it is hypothesized to involve a multifaceted interplay among genetic susceptibility, the host immune response, and environmental factors. Previous studies have largely concluded that IBD is associated with this complex interplay; however, more recent evidence underscores the significant role of dietary habits as risk factors for the development of IBD. In this review, we review the molecular mechanisms of high-sugar and high-fat diets in the progression of IBD and specifically address the impacts of these diets on the gut microbiome, immune system regulation, and integrity of the intestinal barrier, thereby highlighting their roles in the pathogenesis and exacerbation of IBD.

A highly selective inhibitor of discoidin domain receptor-1 (DDR1-IN-1) protects corneal epithelial cells from YAP/ACSL4-mediated ferroptosis in dry eye

BACKGROUND AND PURPOSE

This study investigated the involvement of discoidin domain receptor (DDR) in dry eye and assessed the potential of specific DDR inhibitors as a therapeutic strategy for dry eye by exploring the underlying mechanism.

EXPERIMENTAL APPROACH

Dry eye was induced in Wistar rats by applying 0.2% benzalkonium chloride (BAC), after which rats were treated topically for 7 days with DDR1-IN-1, a selective inhibitor of DDR1. Clinical manifestations of dry eye were assessed on Day-7 post-treatment. Histological evaluation of corneal damage was performed using haematoxylin and eosin (H&E) staining. In vitro, immortalized human corneal epithelial cells (HCECs) exposed to hyperosmotic stress (HS) were treated with varying doses of DDR1-IN-1 for 24 h. The levels of lipid peroxidation in dry eye corneas or HS-stimulated HCECs were assessed. Protein levels of DDR1/DDR2 and related pathways were detected by western blotting. The cellular distribution of acyl-CoA synthetase long chain family member 4 (ACSL4) and Yes-associated protein (YAP) was evaluated using immunohistochemistry or immunofluorescent staining.

KEY RESULTS

In dry eye corneas, only DDR1 expression was significantly up-regulated compared with normal controls. DDR1-IN-1 treatment significantly alleviated dry eye symptoms in vivo. The treatment remarkably reduced lipid hydroperoxide (LPO) levels and suppressed the expression of ferroptosis markers, particularly ACSL4. Overexpression or reactivation of YAP diminished the protective effects of DDR1-IN-1, indicating the involvement of the Hippo/YAP pathway in DDR1-targeted therapeutic effects.

CONCLUSIONS AND IMPLICATIONS

This study confirms the significance of DDR1 in dry eye and highlights the potential of selective DDR1 inhibitor(s) for dry eye treatment.

Interferon regulatory factor 7 alleviates the experimental colitis through enhancing IL-28A-mediated intestinal epithelial integrity

BACKGROUND

The incidence of inflammatory bowel disease (IBD) is on the rise in developing countries, and investigating the underlying mechanisms of IBD is essential for the development of targeted therapeutic interventions. Interferon regulatory factor 7 (IRF7) is known to exert pro-inflammatory effects in various autoimmune diseases, yet its precise role in the development of colitis remains unclear.

METHODS

We analyzed the clinical significance of IRF7 in ulcerative colitis (UC) by searching RNA-Seq databases and collecting tissue samples from clinical UC patients. And, we performed dextran sodium sulfate (DSS)-induced colitis modeling using WT and Irf7-/- mice to explore the mechanism of IRF7 action on colitis.

RESULTS

In this study, we found that IRF7 expression is significantly reduced in patients with UC, and also demonstrated that Irf7-/- mice display heightened susceptibility to DSS-induced colitis, accompanied by elevated levels of colonic and serum pro-inflammatory cytokines, suggesting that IRF7 is able to inhibit colitis. This increased susceptibility is linked to compromised intestinal barrier integrity and impaired expression of key molecules, including Muc2, E-cadherin, β-catenin, Occludin, and Interleukin-28A (IL-28A), a member of type III interferon (IFN-III), but independent of the deficiency of classic type I interferon (IFN-I) and type II interferon (IFN-II). The stimulation of intestinal epithelial cells by recombinant IL-28A augments the expression of Muc2, E-cadherin, β-catenin, and Occludin. The recombinant IL-28A protein in mice counteracts the heightened susceptibility of Irf7-/- mice to colitis induced by DSS, while also elevating the expression of Muc2, E-cadherin, β-catenin, and Occludin, thereby promoting the integrity of the intestinal barrier.

CONCLUSION

These findings underscore the pivotal role of IRF7 in preserving intestinal homeostasis and forestalling the onset of colitis.

Rapamycin promotes the intestinal barrier repair in ulcerative colitis via the mTOR/PBLD/AMOT signaling pathway

Intestinal barrier dysfunction characterized by the functional loss of the intestinal epithelium's tight junction (TJ) barrier is a key factor in the pathogenesis of ulcerative colitis (UC). Although rapamycin, an mTOR (mechanistic target of rapamycin) inhibitor, has shown promise in inducing clinical remission and mucosal healing in inflammatory bowel disease, its underlying mechanism remains elusive. Thus, this study investigated the role of the mTOR pathway in regulating the intestinal barrier. To investigate the molecular mechanism regulating the intestinal barrier, specific intestinal epithelial phenazine biosynthesis-like domain-containing protein (PBLD)-deficient (PBLDIEC-/-) mice and control wild-type (WT) mice were intraperitoneally injected with rapamycin or MHY1485. To determine the relevance of the findings for UC, we analyzed transcriptome data and single-cell expression profiles from public databases and intestinal mucosal tissues obtained from patients with active UC or colon cancer. We observed that mTOR activation in the intestinal epithelium of patients with active UC. Moreover, in vivo, rapamycin markedly increased the expressions of PBLD and TJ proteins and reduced intestinal inflammation in mice with dextran sulfate sodium-induced enteritis. However, the therapeutic efficacy of rapamycin was notably reduced in PBLDIEC-/- mice. In vitro, rapamycin influenced PBLD expression by modulating the nuclear transcription of transcription factor EB (TFEB). Angiomotin (AMOT) could directly bind to PBLD, and rapamycin could not effectively increase the expression of TJ proteins after the knockdown of PBLD or AMOT. In summary, the administration of rapamycin is a potential treatment for UC, and targeting the mTOR/PBLD/AMOT axis is a potential novel approach for UC treatment.

Potentials of dietary fiber and polyphenols in whole grain wheat flour to release the liver function and intestinal tract injury in lead-induced mice

The presence of lead as an environmental pollutant is widespread. However, safe and effective treatments for the resulting intestinal and liver damage from high levels of lead exposure remain limited. The study aimed to investigate the protective effects of dietary fiber and polyphenols in whole grain wheat flour on lead-induced mice. The results indicated that the daily intake of 12 mg of polyphenols, 0.5 g of dietary fiber, and their combination effectively reduced blood and liver lead accumulation by approximately 50 % in mice exposed to lead, while also mitigating lead-induced oxidative stress though a reduction in malondialdehyde levels and an enhancement in antioxidant enzyme activities including superoxide dismutase, catalase, and glutathione peroxidase. Furthermore, all three treatments enhanced cytokine secretion with the combined treatment exhibiting the highest efficacy. Specifically, the combination treatment decreased tumor necrosis factor-α and interleukin 1β by 56.78 %, 47.86 % in intestinal tissue while increasing increased interleukin 4 and interleukin 10 by 81.84 %, 145.14 %. Additionally, it promoted the expression of tight junction proteins like Zonula occludens-1, Occludin and Claudin-1. The study presented a potential strategy for alleviating liver and intestinal tract damage from high-dose lead exposure.

Repurposing metformin as adjuvant therapy in patients with ulcerative colitis treated with mesalamine: A randomized controlled double-blinded study

BACKGROUND

Ulcerative colitis (UC) is a type of inflammatory bowel disease associated with persistent inflammation. Animal studies proved the efficacy of metformin in UC.

AIM

To investigate the potential role of metformin and its protective pathways in patients with UC.

METHODS

This is a randomized, controlled, and double-blinded clinical trial that included 60 participants with mild to moderate UC and was divided randomly into two groups (n = 30). For 6 months, the mesalamine group received 1 g of mesalamine three times daily (t.i.d.). For six months, the metformin group received mesalamine 1 g t.i.d. and metformin 500 mg twice daily. A gastroenterologist evaluated patients at baseline and 6 months after starting the treatment in order to measure serum levels of zonulin, sphingosine 1 phosphate (S1P), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). Biopsies from the colon were used to measure gene expression of zonula occuldin-1 (ZO-1), signal transducer and activator of factor-3 (STAT-3), and intracellular adhesion molecule-1 (ICAM-1). The numeric pain rating scale (NRS) and partial Mayo score were also assessed for each patient.

RESULTS

When compared to the mesalamine group, the metformin group demonstrated a statistical decrease in serum IL-6, zonulin, TNF-α, SIP, gene expression of ICAM-1 and STAT-3, and a significant increase in colonic ZO-1 when compared to the mesalamine group. The metformin group also showed a significant decrease in NRS and partial Mayo score index in comparison with the mesalamine group.

CONCLUSION

Metformin may be a promising additional therapy for UC patients. Trial registration identifier: NCT05553704.

Circadian rhythm disruption-mediated downregulation of Bmal1 exacerbates DSS-induced colitis by impairing intestinal barrier

Background

Circadian rhythm disruption (CRD) is thought to increase the risk of inflammatory bowel disease. The deletion of Bmal1, a core transcription factor, leads to a complete loss of the circadian rhythm and exacerbates the severity of dextran sodium sulfate (DSS)-induced colitis in mice. However, the underlying mechanisms by which CRD and Bmal1 mediate IBD are still unclear.

Methods

We used a CRD mouse model, a mouse colitis model, and an in vitro model of colonic epithelial cell monolayers. We also knocked down and overexpressed Bmal1 in Caco-2 cells by transfecting lentivirus in vitro. The collected colon tissue and treated cells were assessed and analyzed using immunohistochemistry, immunofluorescence staining, quantitative reverse transcription-polymerase chain reaction, western blot, flow cytometry, transmission electron microscopy, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling staining.

Results

We found that CRD mice with downregulated Bmal1 expression were more sensitive to DSS-induced colitis and had more severely impaired intestinal barrier function than wild-type mice. Bmal1-/- mice exhibited more severe colitis, accompanied by decreased tight junction protein levels and increased apoptosis of intestinal epithelial cells compared with wild-type mice, which were alleviated by using the autophagy agonist rapamycin. Bmal1 overexpression attenuated Lipopolysaccharide-induced apoptosis of intestinal epithelial cells and impaired intestinal epithelial cells barrier function in vitro, while inhibition of autophagy reversed this protective effect.

Conclusion

This study suggests that CRD leads to the downregulation of Bmal1 expression in the colon, which may exacerbate DSS-induced colitis in mice, and that Bmal1 may serve as a novel target for treating inflammatory bowel disease.

Polysaccharides extracted from larvae of Lucilia sericata ameliorated ulcerative colitis by regulating the intestinal barrier and gut microbiota

Pest management technology has been a promising bioconversion method for waste resource utilization. Unlike many pests that consume waste, the larvae of Lucilia sericata, also known as maggots, have many outstanding advantages as following: with their strong adaption to environment and not easily infected and exhibiting a medicinal nutritional value. Herein, the potential efficacies of maggot polysaccharides (MP), as well as their underlying mechanisms, were explored in Dextran sulfate sodium (DSS)-induced colitis mice and TNF-α-elicited Caco-2 cells. We extracted two bioactive polysaccharides from maggots, MP-80 and MP-L, whose molecular weights were 4.25 × 103 and 2.28 × 103 g/mol, respectively. MP-80 and MP-L contained nine sugar residues: 1,4-α-Arap, 1,3-β-Galp, 1,4,6-β-Galp, 1,6-α-Glcp, 1-α-Glcp, 1,4-β-Glcp, 1-β-Xylp, 1,2-α-Manp, and 1-β-Manp. We demonstrated that MP-80 and MP-L significantly ameliorated DSS-induced symptoms and histopathological damage. Immuno-analysis revealed that compared with MP-L, MP-80 could better restore intestinal barrier and reduced inflammation by suppressing NLRP3/NF-κB pathways, which might be attributed to its enriched galactose fraction. Moreover, 16S rRNA sequencing revealed that MP-80 and MP-L both improved the dysbiosis and diversity of gut microbiota and acted on multiple microbial functions. Our study sheds new light on the possibility of using maggot polysaccharides as an alternative therapy for colitis.

Ferroptosis in ulcerative colitis: Potential mechanisms and promising therapeutic targets

Ulcerative colitis (UC) is a complex immune-mediated chronic inflammatory bowel disease. It is mainly characterized by diffuse inflammation of the colonic and rectal mucosa with barrier function impairment. Identifying new biomarkers for the development of more effective UC therapies remains a pressing task for current research. Ferroptosis is a newly identified form of regulated cell death characterized by iron-dependent lipid peroxidation. As research deepens, ferroptosis has been demonstrated to be involved in the pathological processes of numerous diseases. A growing body of evidence suggests that the pathogenesis of UC is associated with ferroptosis, and the regulation of ferroptosis provides new opportunities for UC treatment. However, the specific mechanisms by which ferroptosis participates in the development of UC remain to be more fully and thoroughly investigated. Therefore, in this review, we focus on the research advances in the mechanism of ferroptosis in recent years and describe the potential role of ferroptosis in the pathogenesis of UC. In addition, we explore the underlying role of the crosslinked pathway between ferroptosis and other mechanisms such as macrophages, neutrophils, autophagy, endoplasmic reticulum stress, and gut microbiota in UC. Finally, we also summarize the potential compounds that may act as ferroptosis inhibitors in UC in the future.

Lianweng Granules Alleviate Intestinal Barrier Damage via the IL-6/STAT3/PI3K/AKT Signaling Pathway with Dampness-Heat Syndrome Diarrhea

Dampness-heat syndrome diarrhea (DHSD) is a common clinical disease with a high prevalence but still has no satisfactory therapeutic medicine, so the search for a safe and effective drug candidate is ongoing. This study aims to explore the efficacy and mechanisms of Lianweng granules (LWG) in the treatment of DHSD and to identify the blood transport components of LWG. We assessed the efficacy of LWG in DHSD by various in vivo metrics such as body weight, disease activity index (DAI), histopathologic examination, intestinal barrier function, levels of inflammatory, apoptotic biomarkers, and oxidative stress. We identified the blood components of LWG using ultra-high performance liquid chromatography-mass spectrometry/mass spectrometry (UHPLC-MS/MS), and the resolved key components were used to explore the relevant targets. We next predicted the potential mechanisms of LWG in treating DHSD using network pharmacology and molecular docking based on the relevant targets. Finally, the mechanisms were validated in vivo using RT-qPCR, Western blotting, ELISA, and immunofluorescence and evaluated in vitro using Cell Counting Kit-8 (CCK-8), small interfering RNA, cellular enthusiasm transfer assay (CETSA), and drug affinity response target stability (DARTS). Ninety-one pharmacodynamic components of LWG enter the bloodstream and exert possible therapeutic effects. In vivo, LWG treatment improved body weight, reduced colonic injury and DAI scores, lowered inflammation, oxidative stress, and apoptosis markers, and partially restored intestinal barrier function in DHSD mice. Guided by network pharmacology and molecular docking, it is suggested that LWG may exert therapeutic effects by inhibiting IL-6/STAT3/PI3K/AKT signaling. LWG significantly decreased the expression of IL-6, p-STAT3, p-PI3K, p-AKT, and other proteins. These findings were supported by in vitro experiments, where CETSA, DARTS, and siRNA evidenced LWG's targeting of STAT3. LWG targeted STAT3 to inhibit inflammation, oxidative stress, and apoptosis in the colon, thereby restoring the intestinal barrier function to some extent and exerting a therapeutic effect on DHSD.

Triphenyl phosphate exposure impairs colorectal health by altering host immunity and colorectal microbiota

Colorectal diseases such as colorectal cancer (CRC) and inflammatory bowel disease (IBD) have become one of the most common public health concerns worldwide due to the increasing incidence. Environmental factors are one of the important causes of colorectal diseases, as they can affect the intestinal barrier function, immune response and microbiota, causing intestinal inflammation and tumorigenesis. Triphenyl phosphate (TPHP), a widely used organophosphorus flame retardant that can leach and accumulate in various environmental media and biota, can enter the human intestine through drinking water and food. However, the effects of TPHP on colorectal health have not been well understood. In this study, we investigated the adverse influence of TPHP exposure on colorectal cells (in vitro assay) and C57BL/6 mice (in vivo assay), and further explored the potential mechanism underlying the association between TPHP and colorectal disease. We found that TPHP exposure inhibited cell viability, increased apoptosis and caused G1/S cycle arrest of colorectal cells. Moreover, TPHP exposure damaged colorectal tissue structure, changed immune-related gene expression in the colorectal transcriptome, and disrupted the composition of colorectal microbiota. Importantly, we found that TPHP exposure upregulated chemokine CXCL10, which was involved in colorectal diseases. Our study revealed that exposure to TPHP had significant impacts on colorectal health, which may possibly stem from alterations in host immunity and the structure of the colorectal microbial community.

Identifying Spatial Co-occurrence in Healthy and InflAmed tissues (ISCHIA)

Sequencing-based spatial transcriptomics (ST) methods allow unbiased capturing of RNA molecules at barcoded spots, charting the distribution and localization of cell types and transcripts across a tissue. While the coarse resolution of these techniques is considered a disadvantage, we argue that the inherent proximity of transcriptomes captured on spots can be leveraged to reconstruct cellular networks. To this end, we developed ISCHIA (Identifying Spatial Co-occurrence in Healthy and InflAmed tissues), a computational framework to analyze the spatial co-occurrence of cell types and transcript species within spots. Co-occurrence analysis is complementary to differential gene expression, as it does not depend on the abundance of a given cell type or on the transcript expression levels, but rather on their spatial association in the tissue. We applied ISCHIA to analyze co-occurrence of cell types, ligands and receptors in a Visium dataset of human ulcerative colitis patients, and validated our findings at single-cell resolution on matched hybridization-based data. We uncover inflammation-induced cellular networks involving M cell and fibroblasts, as well as ligand-receptor interactions enriched in the inflamed human colon, and their associated gene signatures. Our results highlight the hypothesis-generating power and broad applicability of co-occurrence analysis on spatial transcriptomics data.

Metabolite itaconate in host immunoregulation and defense

Metabolic states greatly influence functioning and differentiation of immune cells. Regulating the metabolism of immune cells can effectively modulate the host immune response. Itaconate, an intermediate metabolite derived from the tricarboxylic acid (TCA) cycle of immune cells, is produced through the decarboxylation of cis-aconitate by cis-aconitate decarboxylase in the mitochondria. The gene encoding cis-aconitate decarboxylase is known as immune response gene 1 (IRG1). In response to external proinflammatory stimulation, macrophages exhibit high IRG1 expression. IRG1/itaconate inhibits succinate dehydrogenase activity, thus influencing the metabolic status of macrophages. Therefore, itaconate serves as a link between macrophage metabolism, oxidative stress, and immune response, ultimately regulating macrophage function. Studies have demonstrated that itaconate acts on various signaling pathways, including Keap1-nuclear factor E2-related factor 2-ARE pathways, ATF3-IκBζ axis, and the stimulator of interferon genes (STING) pathway to exert antiinflammatory and antioxidant effects. Furthermore, several studies have reported that itaconate affects cancer occurrence and development through diverse signaling pathways. In this paper, we provide a comprehensive review of the role IRG1/itaconate and its derivatives in the regulation of macrophage metabolism and functions. By furthering our understanding of itaconate, we intend to shed light on its potential for treating inflammatory diseases and offer new insights in this field.

Wheat Germ-Derived Peptide Alleviates Dextran Sulfate Sodium-Induced Colitis in Mice

This study explores the protective properties and potential mechanisms of wheat-germ-derived peptide APEPEPAF (APE) against ulcerative colitis. Colitis mice induced by dextran sulfate sodium (DSS) were used as the animal model. The results showed that the APE peptide could alleviate colitis symptoms including weight loss, colon shortening, and histopathological changes. This peptide attenuated the generation of inflammatory cytokines by inhibiting the phosphorylation of protein kinase PKCζ (Thr410) and NF-κB transcriptional activity in DSS-induced mice, suggesting that APE ameliorates colitis inflammation by regulating the PKCζ/NF-κB signaling pathway. APE also preserved the barrier function of the colon by dose-dependently promoting the expression of tight junction proteins (claudin-1, zonula occluded-1, and occludin). In addition, APE significantly decreased the abundance of Bacteroides and increased the abundance of Dubosiella and Lachnospiraceae_UCG-006 to improve the intestinal flora imbalance in DSS-induced colitis mice. Therefore, wheat germ peptide APE can be used as a novel agent and dietary supplement to treat ulcerative colitis..

Mechanism of Qingchang Suppository on repairing the intestinal mucosal barrier in ulcerative colitis

Ulcerative colitis (UC) is a refractory inflammatory bowel disease, and the outcomes of conventional therapies of UC, including 5-aminosalicylic acid, glucocorticoids, immunosuppressants, and biological agents, are not satisfied with patients and physicians with regard to adverse reactions and financial burden. The abnormality of the intestinal mucosal barrier in the pathogenesis of UC was verified. Qingchang Suppository (QCS) is an herbal preparation and is effective in treating ulcerative proctitis. The mechanism of QCS and its active ingredients have not been concluded especially in mucosal healing. This review elucidated the potential mechanism of QCS from the intestinal mucosal barrier perspective to help exploring future QCS research directions.

TGR5 agonist inhibits intestinal epithelial cell apoptosis via cAMP/PKA/c-FLIP/JNK signaling pathway and ameliorates dextran sulfate sodium-induced ulcerative colitis

Excessive apoptosis of intestinal epithelial cell (IEC) is a crucial cause of disrupted epithelium homeostasis, leading to the pathogenesis of ulcerative colitis (UC). The regulation of Takeda G protein-coupled receptor-5 (TGR5) in IEC apoptosis and the underlying molecular mechanisms remained unclear, and the direct evidence from selective TGR5 agonists for the treatment of UC is also lacking. Here, we synthesized a potent and selective TGR5 agonist OM8 with high distribution in intestinal tract and investigated its effect on IEC apoptosis and UC treatment. We showed that OM8 potently activated hTGR5 and mTGR5 with EC50 values of 202 ± 55 nM and 74 ± 17 nM, respectively. After oral administration, a large amount of OM8 was maintained in intestinal tract with very low absorption into the blood. In DSS-induced colitis mice, oral administration of OM8 alleviated colitis symptoms, pathological changes and impaired tight junction proteins expression. In addition to enhancing intestinal stem cell (ISC) proliferation and differentiation, OM8 administration significantly reduced the rate of apoptotic cells in colonic epithelium in colitis mice. The direct inhibition by OM8 on IEC apoptosis was further demonstrated in HT-29 and Caco-2 cells in vitro. In HT-29 cells, we demonstrated that silencing TGR5, inhibition of adenylate cyclase or protein kinase A (PKA) all blocked the suppression of JNK phosphorylation induced by OM8, thus abolished its antagonizing effect against TNF-α induced apoptosis, suggesting that the inhibition by OM8 on IEC apoptosis was mediated via activation of TGR5 and cAMP/PKA signaling pathway. Further studies showed that OM8 upregulated cellular FLICE-inhibitory protein (c-FLIP) expression in a TGR5-dependent manner in HT-29 cells. Knockdown of c-FLIP blocked the inhibition by OM8 on TNF-α induced JNK phosphorylation and apoptosis, suggesting that c-FLIP was indispensable for the suppression of OM8 on IEC apoptosis induced by OM8. In conclusion, our study demonstrated a new mechanism of TGR5 agonist on inhibiting IEC apoptosis via cAMP/PKA/c-FLIP/JNK signaling pathway in vitro, and highlighted the value of TGR5 agonist as a novel therapeutic strategy for the treatment of UC.

Dietary Supplementation of Ancientino Ameliorates Dextran Sodium Sulfate-Induced Colitis by Improving Intestinal Barrier Function and Reducing Inflammation and Oxidative Stress

Ancientino, a complex dietary fiber supplement mimicking the ancient diet, has improved chronic heart failure, kidney function, and constipation. However, its effect on ulcerative colitis is unknown. This study explores the impact of Ancientino on colitis caused by dextran sulfate sodium (DSS) and its mechanisms. Data analyses showed that Ancientino alleviated bodyweight loss, colon shortening and injury, and disease activity index (DAI) score, regulated levels of inflammatory factors (tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), interleukin-1 beta (IL-1β), and interleukin 6 (IL-6)), reduced intestinal permeability (d-lactate and endotoxin), fluorescein isothiocyanate-dextran (FITC-dextran), and diamine oxidase (DAO), repaired colonic function (ZO-1 and occludin), and suppressed oxidative stress (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA)) in vivo and in vitro. In short, this study demonstrated that Ancientino alleviates colitis and exerts an anticolitis effect by reducing inflammatory response, suppressing oxidative stress, and repairing intestinal barrier function. Thus, Ancientino may be an effective therapeutic dietary resource for ulcerative colitis.

Liposome-embedded SOD attenuated DSS-induced ulcerative colitis in mice by ameliorating oxidative stress and intestinal barrier dysfunction

Oxidative stress is generally considered inseparable from the development and exacerbation of ulcerative colitis (UC). Therefore, reducing oxidative stress has become a possible way to alleviate UC. In this study, the therapeutic effects of different doses of liposome-embedded superoxide dismutase (L-SOD) on mice with DSS-induced UC were systematically investigated. The results showed that L-SOD significantly attenuated the signs of colitis in mice, including colonic shortening, diarrhoea, bloody stools, and histopathological changes. L-SOD ameliorated DSS-induced oxidative damage, increased SOD, catalase (CAT), and glutathione (GSH) activities, and decreased malondialdehyde (MDA) levels. In addition, L-SOD ameliorated the inflammatory response by inhibiting the expression of myeloperoxidase (MPO) and pro-inflammatory cytokines and protected barrier function by promoting the expression of the tight junction proteins occludin and ZO-1 in the colon. Importantly, the results demonstrated a bell-shaped distribution of therapeutic effects relative to the administered dose, with an optimal dose of 150 000 U kg^-1. These results indicate that L-SOD has great potential as an ingredient in functional foods for the prevention and mitigation of UC.

Corylin ameliorates chronic ulcerative colitis via regulating the gut-brain axis and promoting 5-hydroxytryptophan production in the colon

BACKGROUND

Chronic ulcerative colitis (UC) is a lifelong disease, patients with chronic UC have a high prevalence of common mental disorders. The increasing interest in the role of gut-brain axis is seen in inflammatory bowel diseases.

PURPOSE

Corylin is a representative flavonoid compound isolated from the Psoraleae Fructus. This study aimed to identify the effects and mechanism of corylin on the inflammation interactions and 5-HT synthesis between the gut and brain in chronic UC.

METHODS

Dextran sulfate sodium (DSS) induced chronic UC mouse model was established to assess the therapeutic effect of corylin on chronic UC symptoms. The expression of inflammatory cytokines was detected in the colon and brain. The expression of tight junction (TJ) proteins of intestinal mucosal barrier and blood-brain barrier (BBB) and the ionized calcium-binding adaptor molecule 1 (Iba1) in the hippocampus were determined by western blotting and immunofluorescence staining. In addition, several tryptophan (Trp) metabolites and related neurotransmitters in faeces, colon, serum, and brain were detected by UPLC-MS/MS. The interaction between corylin and 5-hydroxytryptophan decarboxylase (5-HTPDC) was performed by molecular docking and surface plasmon resonance (SPR). Finally, the changes of gut microbiota composition were analyzed by 16S rRNA sequencing.

RESULTS

Corylin significantly alleviated colitis symptoms and inhibited inflammatory response in the colon and brain of DSS-induced chronic UC mice. The TJ proteins of intestinal mucosal barrier and BBB were improved and the expression of Iba1 in the hippocampus was normalized after corylin treatment. In addition, corylin treatment increased the expression of neurotransmitters in the brain, especially 5-hydroxytryptamine (5-HT) and 5-hydroxytryptophan (5-HTP), but the expression of 5-HT in the colon was inhibited. Further study firstly proved that corylin could bind to the 5-HTDPC, and then inhibit the expression of 5-HTDPC and VB₆, resulting in the 5-HT reduction and 5-HTP accumulation in the colon. Moreover, the intake of corylin transformed the diversity and composition of intestinal microbiota, Bacteroides, Escherichia-Shigella, and Turicibacter were decreased but Dubosiella, Enterorhabdus, and Candidatus_Stoquefichus were increased.

CONCLUSION

Corylin administration ameliorated DSS-induced colitis and inhibited intestinal inflammation and neuroinflammation via regulating the inflammation interactions across gut-brain axis and increasing 5-HTP generation in the colon.

The effect of the "Oral-Gut" axis on periodontitis in inflammatory bowel disease: A review of microbe and immune mechanism associations

Periodontitis and inflammatory bowel diseases (IBD) are inflammatory diseases of the gastrointestinal tract that share common features of microbial-induced ecological dysregulation and host immune inflammatory response. The close relationship between periodontitis and IBD is characterized by a higher prevalence of IBD in patients with periodontitis and a higher prevalence and severity of periodontitis in patients with IBD, indicating that periodontitis and IBD are different from the traditional independent diseases and form an "Oral-Gut" axis between the two, which affect each other and thus form a vicious circle. However, the specific mechanisms leading to the association between the two are not fully understood. In this article, we describe the interconnection between periodontitis and IBD in terms of microbial pathogenesis and immune dysregulation, including the ectopic colonization of the gut by pathogenic bacteria associated with periodontitis that promotes inflammation in the gut by activating the host immune response, and the alteration of the oral microbiota due to IBD that affects the periodontal inflammatory response. Among the microbial factors, pathogenic bacteria such as Klebsiella, Porphyromonas gingivalis and Fusobacterium nucleatum may act as the microbial bridge between periodontitis and IBD, while among the immune mechanisms, Th17 cell responses and the secreted pro-inflammatory factors IL-1β, IL-6 and TNF-α play a key role in the development of both diseases. This suggests that in future studies, we can look for targets in the "Oral-Gut" axis to control and intervene in periodontal inflammation by regulating periodontal or intestinal flora through immunological methods.

Tongxie-Yaofang formula regulated macrophage polarization to ameliorate DSS-induced colitis via NF-κB/NLRP3 signaling pathway

BACKGROUND

Macrophages infiltration and activation play multiple roles in maintaining intestinal homeostasis and participate in the occurrence and development of UC. Thus, the restoration of immune balance can be achieved by targeting macrophage polarization. Previous studies have reported that TXYF could effectively ameliorate DSS-induced colitis. However, the underlying mechanisms of TXYF for DSS-induced colitis are still ill-defined.

METHODOLOGY

This study was designed to explore the therapeutic effect of TXYF and its regulation in macrophages polarization during DSS-induced mice. In C75BL/6 mice, dextran sulfate sodium (DSS) was used to induce colitis and concomitantly TXYF was taken orally to evaluate its curative effect. In vitro experiment was implemented on BMDMs by lipopolysaccharide, IFN- and ATP.

RESULTS

Here, we found that TXYF ameliorated clinical features in DSS-induced mice, decreased macrophages M1 polarization but remarkably increased M2 polarization. Mechanically, TXYF treatment effectively inhibited the activities of nuclear transcription factor NF-κB, which further contributed to the decrease of the inflammasome genes of NLRP3, limiting the activation of NLRP3 inflammasome in vivo and in vitro.

CONCLUSION

Our findings demonstrated administration of TXYF can interfere with macrophage infiltration and polarization to improve the symptoms of acute colitis, by repressing NF-κB/NLRP3 signaling pathway activation. This enriches the mechanism and provides new prospect for TXYF in the treatment of colitis.