Faecal Proteases from Pouchitis Patients Activate Protease Activating Receptor-2 to Disrupt the Epithelial Barrier

Tryptophan Metabolites Improve Intestinal Mucosal Barrier via the Aryl Hydrocarbon Receptor-Interleukin-22 Pathway in Murine Dextran Sulfate Sodium-Induced Pouchitis

BACKGROUND

Pouchitis is the most common complication after IPAA for ulcerative colitis. The protective effect of tryptophan metabolites on the mucosal barrier may be effective for treating pouchitis. The role of tryptophan metabolites on pouchitis remained unclear.

OBJECTIVE

We aimed to establish a murine model of dextran sulfate sodium-induced pouchitis to examine the roles of tryptophan metabolites in its pathogenesis.

DESIGN

This is a study that combines clinical patient data and animal research. A total of 22 patients were enrolled: 5 patients with familial adenomatous polyposis after IPAA, 8 patients with ulcerative colitis after IPAA with pouchitis, and 9 patients with ulcerative colitis after IPAA with normal pouch. The demographic data and fecal samples of patients were collected. Male C57BL/6 mice were purchased from a licensed breeder and underwent IPAA to establish a murine model of the pouch. The blood, feces, and tissues of mice were collected.

SETTINGS

This study was performed in an academic medical center in China.

INTERVENTIONS

The demographic data of patients were observationally collected. The mice that underwent IPAA were divided into a control group that received a chow diet and 5 study groups: 1) dextran sulfate sodium, 2) 6-formylindolo[3,2-b] carbazole + dextran sulfate sodium, 3) high tryptophan diet + dextran sulfate sodium, 4) CH-223191 + dextran sulfate sodium, and 5) indole-3-carboxaldehyde + dextran sulfate sodium. Animals were euthanized after receiving dextran sulfate sodium for 7 days.

MAIN OUTCOME MEASURES

Fecal tryptophan metabolite level and microbiome composition, the severity of pouchitis, intestinal mucosal barrier function, and activation of the aryl hydrocarbon receptor-interleukin 22 pathway were assessed.

RESULTS

Patients with pouchitis had lower fecal microbial diversity and indole-3-acetic acid levels. In the murine pouchitis model, high tryptophan diet increased fecal levels of 3-indoleglyoxylic acid, indole-3-aldehyde, and indole. A high tryptophan diet and intraperitoneal aryl hydrocarbon receptor ligand 6-formylindolo[3,2-b] carbazole injection alleviated pouchitis. Tryptophan metabolites improved pouch mucosal barriers. Aryl hydrocarbon receptor inhibitors exacerbated experimental pouchitis and disrupted the mucosal barrier; however, the aryl hydrocarbon receptor ligand indole-3-carboxaldehyde reversed this effect.

LIMITATIONS

This study was limited by a small human sample size and lacked an aryl hydrocarbon receptor knockout mouse model.

CONCLUSIONS

A high tryptophan diet and aryl hydrocarbon receptor ligand alleviated dextran sulfate sodium-induced pouchitis in a murine IPAA model, which might be achieved through regulating epithelial tight junctions and promoting goblet cell differentiation, as well as maintaining the integrity and function of the mucosal barrier. This study provides a rationale for the clinical application of aryl hydrocarbon receptor ligands in the treatment of pouchitis. See Video Abstract .

LOS METABOLITOS DEL TRIPTFANO MEJORAN LA BARRERA DE LA MUCOSA INTESTINAL A TRAVS DE LA VA DEL RECEPTOR DE HIDROCARBUROS ARILOINTERLEUCINA EN LA RESERVORITIS INDUCIDA POR SULFATO DE SODIO Y DEXTRANO EN MODELO MURINO

ANTECEDENTES:La reservoritis es la complicación más frecuente después de la anastomosis del reservorio ileal con el ano en la colitis ulcerosa. El efecto protector de los metabolitos del triptófano sobre la barrera mucosa puede ser un método eficaz para tratar la reservoritis. El papel de los metabolitos del triptófano en la reservoritis sigue sin estar claro.OBJETIVO:Nuestro objetivo era establecer un modelo murino de reservoritis inducida por sulfato de dextrano sódico para examinar el papel de los metabolitos del triptófano en su patogenia.DISEÑO:Este es un estudio que combina datos clínicos de pacientes e investigación animal. Se inscribieron un total de 22 pacientes: 5 con poliposis adenomatosa familiar después de un reservorio ileal, ocho pacientes con colitis ulcerosa después de un reservorio ileal que desarrollaron reservoritis y 9 pacientes con colitis ulcerosa después de un reservorio ileal que no presentaron reservoritis. Se recogieron los datos demográficos y las muestras fecales de los pacientes. Se adquirieron ratones macho C57BL/6 de un criador autorizado y se les realizó un reservorio ileal para establecer un modelo murino del reservorio. Se recogieron sangre, heces y tejidos de los ratones.CONFIGURACIÓN:Este estudio se realizó en un centro médico académico en China.INTERVENCIONES:Los datos demográficos de los pacientes se recogieron de forma observacional. Los ratones sometidos a un reservorio ileal se dividieron en seis grupos: grupo de control con dieta normal, sulfato de dextrano sódico, 6-formilindolo[3,2-b] carbazol + sulfato de dextrano sódico, dieta rica en triptófano + sulfato de dextrano sódico, CH-223191 + sulfato de dextrano sódico, indol-3-carboxaldehído + sulfato de dextrano sódico. Los animales fueron sacrificados después de la administración de sulfato de dextrano sódico durante 7 días.PRINCIPALES MEDIDAS DE RESULTADOS:Se evaluaron los niveles de metabolitos de triptófano y la composición del microbioma fecal, la gravedad de la reservoritis, la función de barrera de la mucosa intestinal y la activación de la vía del receptor de hidrocarburos de arilo-interleucina 22.RESULTADOS:Los pacientes con reservoritis tenían una menor diversidad microbiana fecal y niveles de ácido indol-3-acético. En el modelo de reservoritis murino, la dieta rica en triptófano aumentó los niveles fecales de ácido 3-indolglioxílico, indol-3-aldehído e indol. Una dieta rica en triptófano y una inyección intraperitoneal del ligando del receptor de hidrocarburos de arilo 6-formilindolo[3,2-b] carbazol aliviaron la reservoritis. Los metabolitos de triptófano mejoraron las barreras de la mucosa de la reservoritis. Los inhibidores del receptor de hidrocarburos de arilo exacerbaron la reservoritis experimental y alteraron la barrera mucosa; sin embargo, el ligando del receptor de hidrocarburos de arilo indol-3-carboxaldehído revirtió este efecto.LIMITACIONES:Este estudio estuvo limitado por el pequeño tamaño de la muestra humana y la falta de un modelo de ratón con deficiencia del receptor de hidrocarburos arílicos.CONCLUSIONES:Una dieta rica en triptófano y un ligando del receptor de hidrocarburos arílicos aliviaron la reservoritis inducida por sulfato de dextrano sódico en un modelo murino de anastomosis de reservorio ileo-anal, lo que podría deberse a la regulación de las uniones estrechas epiteliales y la promoción de la diferenciación de las células caliciformes, así como al mantenimiento de la integridad y la función de la barrera mucosa. Este estudio proporciona una justificación para la aplicación clínica de los ligandos del receptor de hidrocarburos arílicos en el tratamiento de la reservoritis. (Traducción-Dr. Felipe Bellolio ).

A Novel Microbial Dysbiosis Index and Intestinal Microbiota-Associated Markers as Tools of Precision Medicine in Inflammatory Bowel Disease Paediatric Patients

Recent evidence indicates that the gut microbiota (GM) has a significant impact on the inflammatory bowel disease (IBD) progression. Our aim was to investigate the GM profiles, the Microbial Dysbiosis Index (MDI) and the intestinal microbiota-associated markers in relation to IBD clinical characteristics and disease state. We performed 16S rRNA metataxonomy on both stools and ileal biopsies, metabolic dysbiosis tests on urine and intestinal permeability and mucosal immunity activation tests on the stools of 35 IBD paediatric patients. On the GM profile, we assigned the MDI to each patient. In the statistical analyses, the MDI was correlated with clinical parameters and intestinal microbial-associated markers. In IBD patients with high MDI, Gemellaceae and Enterobacteriaceae were increased in stools, and Fusobacterium, Haemophilus and Veillonella were increased in ileal biopsies. Ruminococcaceae and WAL_1855D were enriched in active disease condition; the last one was also positively correlated to MDI. Furthermore, the MDI results correlated with PUCAI and Matts scores in ulcerative colitis patients (UC). Finally, in our patients, we detected metabolic dysbiosis, intestinal permeability and mucosal immunity activation. In conclusion, the MDI showed a strong association with both severity and activity of IBD and a positive correlation with clinical scores, especially in UC. Thus, this evidence could be a useful tool for the diagnosis and prognosis of IBD.

Key Focus Areas in Pouchitis Therapeutic Status: A Narrative Review

Pouchitis, as the most common complication after ileal pouch-anal anastomosis (IPAA), has an incidence from 7% to 46%. Pouchitis treatment still represents one of the biggest gaps of knowledge in the treatment of diseases. This review has focused on achievements and challenges in the treatment of pouchitis. A combined assessment of symptoms, endoscopic findings, histologic results, quick biomarkers, and fecal calprotectin test were determined to be valuable diagnostic criteria. Conventional therapy was described as a modification of bacterial flora, mainly with antibiotics and more recently with probiotics such as bifidobacteria, lactobacilli, and streptococci. Other therapeutic approaches such as anti-tumor necrosis factor, infliximab, adalimumab, vedolizumab, ustekinumab, tacrolimus, tofacitinib, thiopurines, corticosteroids, prolyl hydroxylase-containing enzymes, povidone-iodine, dextrose spray, fecal microbiota transplantation, herbal medicines, and leukocyte apheresis have been discussed. Changes in dietary components, and administration of complementary and alternative medicine, probiotics, and fecal transplantation in addition to conventional therapies were also shown to affect the outcome of disease. Due to the potential significant impairment in quality of life caused by pouchitis, it is essential to address the gaps in knowledge for both patients and physicians in its treatment. Therefore, well-designed and adequately powered studies should assess the optimal treatment for pouchitis.

Normal Ileal Mucus Is Inadequate for Epithelial Protection in Ileal Pouch Mucosa

BACKGROUND

Clinical, nonspecific pouchitis is common after restorative proctocolectomy for ulcerative colitis, but its cause is unknown. A possible lack of protection for the ileal mucosa in its role as a reservoir for colonic-type bacteria may be the missing piece in defining the causes of pouchitis.

OBJECTIVE

The study aimed to review the causes of pouchitis and introduce the hypothesis that inadequate mucus protection in the pouch, combined with a predisposition to abnormal inflammation, is the most common cause of nonspecific pouchitis.

DATA SOURCES

Review of PubMed and MEDLINE for articles discussing pouchitis and intestinal mucus.

STUDY SELECTION

Studies published from 1960 to 2023. The main search terms were "pouchitis," and "intestinal mucus," whereas Boolean operators were used with multiple other terms to refine the search. Duplicates and case reports were excluded.

MAIN OUTCOME MEASURES

Current theories about the cause of pouchitis, descriptions of the role of mucus in the physiology of intestinal protection, and evidence of the effects of lack of mucus on mucosal inflammation.

RESULTS

The crossreference of "intestinal mucus" with "pouchitis" produced 9 references, none of which discussed the role of mucus in the development of pouchitis. Crossing "intestinal mucus" with "pouch" resulted in 32 articles, combining "pouchitis" with "barrier function" yielded 37 articles, and "pouchitis" with "permeability" yielded only 8 articles. No article discussed the mucus coat as a barrier to bacterial invasion of the epithelium or mentioned inadequate mucus as a factor in pouchitis. However, an ileal pouch produces a colonic environment in the small bowel, and the ileum lacks the mucus protection needed for this sort of environment. This predisposes pouch mucosa to bacterial invasion and chronic microscopic inflammation that may promote clinical pouchitis in patients prone to an autoimmune response.

LIMITATIONS

No prior studies address inadequate mucus protection and the origin of proctitis. There is no objective way of measuring the autoimmune tendency in patients with ulcerative colitis.

CONCLUSIONS

Studies of intestinal mucus in the ileal pouch and its association with pouchitis are warranted.

The proteolytic activity in inflammatory bowel disease: insight from gut microbiota

Inflammatory bowel disease (IBD) is a chronic, recurrent inflammatory disease caused by the destruction of the intestinal mucosal epithelium that affects a growing number of people worldwide. Although the etiology of IBD is complex and still elucidated, the role of dysbiosis and dysregulated proteolysis is well recognized. Various studies observed altered composition and diversity of gut microbiota, as well as increased proteolytic activity (PA) in serum, plasma, colonic mucosa, and fecal supernatant of IBD compared to healthy individuals. The imbalance of intestinal microecology and intestinal protein hydrolysis were gradually considered to be closely related to IBD. Notably, the pivotal role of intestinal microbiota in maintaining proteolytic balance received increasing attention. In summary, we have speculated a mesmerizing story, regarding the hidden role of PA and microbiota-derived PA hidden in IBD. Most importantly, we provided the diagnosis and therapeutic targets for IBD as well as the formulation of new treatment strategies for other digestive diseases and protease-related diseases.

Bifidobacterium breve CCFM1078 Alleviates Collagen-Induced Arthritis in Rats via Modulating the Gut Microbiota and Repairing the Intestinal Barrier Damage

This study focused on the effects of Bifidobacterium breve CCFM1078 on the intestinal barrier and systemic inflammation of collagen-induced arthritis (CIA) rats. Female rats were divided into three groups with daily intragastric administration of either saline (control group and model group) or B. breve CCFM1078 (CCFM1078 group, 3 × 10⁹cfu/rat per day) for 5 weeks. In the Model and CCFM1078 groups, arthritis was induced by subcutaneous collagen injection. We found that B. breve CCFM1078 can repair the intestinal barrier, reduce LPS translocation, regulate gut microbiota composition, and increase short-chain fatty acids in the intestine. Then, it can reduce pro-inflammatory cytokines release, adjust immune dysfunction, and inhibit TLR4-MyD88-dependent pathways and downstream inflammatory pathways to alleviate joint inflammation in CIA rats. These findings suggest that B. breve CCFM1078 may alleviate joint inflammation by adjusting the profile of gut microbiota and enhancing the intestinal barrier.

The Effect of the Crohn's Disease Exclusion Diet on Patients With Pouch Inflammation: An Interventional Pilot Study

Restorative proctocolectomy with ileal pouch-anal anastomosis is the surgical treatment of choice for patients with ulcerative colitis.¹ Unfortunately, pouch inflammation (ie, pouchitis) is reported in up to 72% of pouch patients.^1,2.

The relationship between gut microbiota and proteolytic activity in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disease that affects 3.8-9.2% of the world population. It affects the physiology and psychology of patients and increases the burden on families, the healthcare system, society, and economic development. Presently, a large number of studies have shown that compared to healthy individuals, the composition and diversity of gut microbiota in IBS patients have changed, and the proteolytic activity (PA) in fecal supernatant and colonic mucosa of IBS patients has also increased. These findings indicate that the imbalance of intestinal microecology and intestinal protein hydrolysis is closely related to IBS. Furthermore, the intestinal flora is a key substance that regulates the PA and is associated with IBS. The current review described the intestinal microecology and intestinal proteolytic activity of patients with IBS and also discussed the effect of intestinal flora on PA. In summary, this study proposed a pivotal role of gut microbiota and PA in IBS, respectively, and provided an in-depth insight into the diagnosis and treatment targets of IBS as well as the formulation of new treatment strategies for other digestive diseases and protease-related diseases.

Human Intestinal Barrier: Effects of Stressors, Diet, Prebiotics, and Probiotics

The objectives of this article are to understand the effects of stressors (nonsteroidal antiinflammatory drug, exercise, and pregnancy) and components in the diet, specifically prebiotics and probiotics, on intestinal barrier function. Stressors generally reduce barrier function, and these effects can be reversed by supplements such as zinc or glutamine that are among the substances that enhance the barrier. Other dietary factors in the diet that improve the barrier are vitamins A and D, tryptophan, cysteine, and fiber; by contrast, ethanol, fructose, and dietary emulsifiers increase permeability. Effects of prebiotics on barrier function are modest; on the other hand, probiotics exert direct and indirect antagonism of pathogens, and there are documented effects of diverse probiotic species, especially combination agents, on barrier function in vitro, in vivo in animal studies, and in human randomized controlled trials conducted in response to stress or disease. Clinical observations of benefits with combination probiotics in inflammatory diseases have simultaneously not appraised effects on intestinal permeability. In summary, probiotics and synbiotics enhance intestinal barrier function in response to stressor or disease states. Future studies should address the changes in barrier function and microbiota concomitant with assessment of clinical outcomes.

The Interplay Between Genetic Risk Factors and Proteolytic Dysregulation in the Pathophysiology of Inflammatory Bowel Disease

Crohn's disease [CD] and ulcerative colitis [UC] are the two main forms of inflammatory bowel disease [IBD]. Previous studies reported increased levels of proteolytic activity in stool and tissue samples from IBD patients, whereas the re-establishment of the proteolytic balance abrogates the development of experimental colitis. Furthermore, recent data suggest that IBD occurs in genetically predisposed individuals who develop an abnormal immune response to intestinal microbes once exposed to environmental triggers. In this review, we highlight the role of proteases in IBD pathophysiology, and we showcase how the main cellular pathways associated with IBD influence proteolytic unbalance and how functional proteomics are allowing the unambiguous identification of dysregulated proteases in IBD, paving the way to the development of new protease inhibitors as a new potential treatment.

Heat shock transcription factor 2 inhibits intestinal epithelial cell apoptosis through the mitochondrial pathway in ulcerative colitis

UC is a chronic inflammatory disease of the colonic mucosa and lacks effective treatments because of unclear pathogenesis. Excessive apoptosis of IECs damages the intestinal epithelial barrier and is involved in the progression of UC, but the mechanism is unknown. HSPs are important in maintaining homeostasis and regulate apoptosis through the mitochondrial pathway. In our previous studies, HSF2, an important regulator of HSPs, was highly expressed in UC patients and negatively correlated with inflammation in mice and IECs. Therefore, we hypothesized that HSF2 may protect against intestinal mucositis by regulating the apoptosis of IECs. In this study, a DSS-induced colitis model of hsf2^-/- mice was used to explore the relationship between HSF2 and apoptosis in IECs for the first time. The expression of HSF2 increased in the WT + DSS group compared with that in the WT + H₂O group. Moreover, the extent of apoptosis was more severe in the KO + DSS group than in the WT + DSS group. The results showed that HSF2 was negatively correlated with apoptosis in vivo. The expression of HSF2 in Caco-2 cells was changed by lentiviral transfection, and the expression of Bax, cytoplasmic Cyto-C, Cleaved Caspase-9 and Cleaved Caspase-3 were negatively correlated with the different levels of HSF2. These results suggest that HSF2 negatively regulates apoptosis of IECs through the mitochondrial pathway. This may be one of the potential mechanisms to explain the protective role of HSF2 in UC.