Review article: the pathogenesis of pouchitis

Preventive effect of Clostridium butyricum MIYAIRI against pouchitis in children with ulcerative colitis

PURPOSE

Pouchitis is a major complication after ileal pouch-anal anastomosis (IPAA) for ulcerative colitis in children (UCc). In this study, we investigated whether the oral administration of Clostridium butyricum MIYAIRI 588 (CBM) can reduce the incidence of pouchitis after IPAA in UCc.

METHODS

We reviewed the data for pediatric patients with UC, who underwent IPAA in Mie University Hospital between 2004 and 2022. Data on the presence and type of postoperative probiotic medication and the timing of probiotic initiation, as well as clinical variables, were collected from the patients' medical records.

RESULTS

During the study period, 55 children with UC underwent radical surgery. During the first 5 years after ileostomy closure, 23 (41.8%) patients suffered at least one pouchitis episode. The incidence of acute pouchitis was significantly lower in the CBM group than in the non-CBM group (CBM vs. non-CBM: 10.5% vs. 58.3%, p < 0.01). Furthermore, even among patients who had been taking any probiotics postoperatively, the CBM group had a significantly lower incidence of both acute and chronic pouchitis than the 'other probiotics' group (p < 0.01).

CONCLUSION

Oral CBM administration after ileostomy closure may be effective in preventing postoperative pouchitis.

The Effect of Non-pooled Multidonor Faecal Microbiota Transplantation for Inducing Clinical Remission in Patients with Chronic Pouchitis: Results from a Multicentre, Randomised, Double-blinded, Placebo-controlled Trial [MicroPouch]

BACKGROUND AND AIMS

To investigate if treatment with non-pooled, multidonor faecal microbiota transplantation [FMT] for 4 weeks was superior to placebo to induce clinical remission in patients with chronic pouchitis.

METHODS

The study was a randomised, double-blinded, placebo-controlled study with a 4-week intervention period and 12-month follow-up. Eligible patients with chronic pouchitis were recruited from five Danish hospitals. Participants were randomised to non-pooled, multidonor FMT derived from four faecal donors, or placebo. Treatment was delivered daily by enema for 2 weeks, followed by every second day for 2 weeks. Disease severity was accessed at inclusion and 30-day follow-up, using the Pouchitis Disease Activity Index [PDAI]; PDAI <7 was considered equivalent to clinical remission. Faecal samples from participants and donors were analysed by shotgun metagenomic sequencing.

RESULTS

Inclusion was stopped after inclusion of 30 participants who were randomised 1:1 for treatment with FMT or placebo. There was no difference in participants achieving clinical remission between the two groups at 30-day follow-up, relative risk 1.0 (95% CI [0.55; 1.81]). Treatment with FMT resulted in a clinically relevant increase in adverse events compared with placebo, incidence rate ratio 1.67 (95% CI [1.10; 2.52]); no serious adverse events within either group. Faecal microbiota transplantation statistically significantly increased the similarity of participant faecal microbiome to the faecal donor microbiome at 30-day follow-up [p = 0.01], which was not seen after placebo.

CONCLUSIONS

Non-pooled, multidonor FMT was comparable to placebo in inducing clinical remission in patients with chronic pouchitis, but showed a clinically relevant increase in adverse events compared with placebo. ClincialTrials.gov number, NCT04100291.

A comprehensive review on lncRNA LOXL1-AS1: molecular mechanistic pathways of lncRNA LOXL1-AS1 in tumorigenicity of cancer cells

Long non-coding RNAs (lncRNAs) are versatile RNAs that regulate various cellular processes, such as gene regulation, by acting as signals, decoys, guides, and scaffolds. A novel recognized lncRNA, LOXL1-antisense RNA 1 (LOXL1-AS1), is dysregulated in some diseases, including cancer, and acts as an oncogenic lncRNA in many types of cancer cells. Upregulation of LOXL1-AS1 has been involved in proliferation, migration, metastasis, and EMT, as well as inhibiting apoptosis in cancer cells. Most importantly, the malignant promoting activity of LOXL1-AS1 can be mostly mediated by sequestering specific miRNAs and inhibiting their binding to the 3´UTR of their target mRNAs, thereby indirectly regulating gene expression. Additionally, LOXL1-AS1 can decoy transcription factors and proteins and prevent their binding to their regulatory regions, inhibiting their mechanistic activity on the regulation of gene expression and signaling pathways. This review presents the mechanistic pathways of the oncogenic role of LOXL1-AS1 by modulating its target miRNAs and proteins in various cancer cells. Having information about the molecular mechanisms regulated by LOXL1-AS1 in cancer cells can open ways to find out particular prognostic biomarkers, as well as discover novel therapeutic approaches for different types of cancer.

Diagnosis and Medical Treatment of Acute and Chronic Idiopathic Pouchitis in Inflammatory Bowel Disease

Despite the decreased rates in inflammatory bowel disease (IBD) colectomies due to high advances in therapeutic options, a significant number of patients still require proctocolectomy with ileal pouch-anal anastomosis (IPPA) for ulcerative colitis (UC). Pouchitis is the most common complication in these patients, where up to 60% develop one episode of pouchitis in the first two years after UC surgery with IPAA with severe negative impact on their quality of life. Acute cases usually respond well to antibiotics, but 15% of patients will still develop a refractory disease that requires the initiation of advanced immunosuppressive therapies. For chronic idiopathic pouchitis, current recommendations suggest using the same therapeutic options as for IBD in terms of biologics and small molecules. However, the available data are limited regarding the effectiveness of different biologics or small molecules for the management of this condition, and all evidences arise from case series and small studies. Vedolizumab is the only biologic agent that has received approval for the treatment of adult patients with moderately to severely active chronic refractory pouchitis. Despite the fact that IBD treatment is rapidly evolving with the development of novel molecules, the presence of pouchitis represents an exclusion criterion in these trials. Recommendations for the approach of these conditions range from low to very low certainty of evidence, resulting from small randomized controlled trials and case series studies. The current review focuses on the therapeutic management of idiopathic pouchitis.

Evidence-Based Approach to Chronic Antibiotic Refractory Pouchitis: A Review

BACKGROUND

Chronic antibiotic refractory pouchitis after restorative proctocolectomy with IPAA, characterized by at least 4 weeks of pouchitis symptoms that have not responded to standard antibiotic therapy, presents a therapeutic challenge for patients and health care providers.

OBJECTIVE

The aim of this narrative review was to summarize the current evidence regarding the management of chronic antibiotic refractory pouchitis.

DATA SOURCES

Studies were identified through a search of the PubMed database from the National Library of Medicine.

STUDY SELECTION

We included case series, cohort studies, randomized controlled trials, and systematic reviews with meta-analyses that addressed chronic antibiotic refractory pouchitis management, with prioritization of data published within the past 3 to 5 years.

INTERVENTION

Studies examining pharmacologic and select nonpharmacologic interventions were included.

MAIN OUTCOME MEASURE

Outcomes measures included clinical, endoscopic, and histologic end points.

RESULTS

Mesalamine has demonstrated efficacy in symptom improvement but no improvement in quality of life. Budesonide has demonstrated high rates of clinical remission that have mostly been sustained in a small number of patients. Anti-tumor necrosis factor therapies have demonstrated efficacy in reaching clinical and even endoscopic end points, although rates of treatment discontinuation were not insignificant. Limited evidence is encouraging for the use of ustekinumab in achieving clinical response. Data for vedolizumab are favorable across clinical, endoscopic, and histologic end points, including one of the only randomized, placebo-controlled trials. Nonmedication therapies, including hyperbaric oxygen therapy and fecal microbiota transplant, have undergone limited evaluation, and concerns about the ultimate accessibility of these therapies remain.

LIMITATIONS

Overall, studies assessing therapeutic options for chronic antibiotic refractory pouchitis are mostly limited to case series and retrospective studies with small sample sizes.

CONCLUSIONS

Biologic therapies have demonstrated efficacy in the management of chronic antibiotic refractory pouchitis and offer a steroid-sparing option for refractory disease. Nonpharmacologic therapies, including hyperbaric oxygen and fecal microbiota transplant, require further exploration. See video from symposium .

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.

Ouch, my pouch! a clinician's guide to pouchitis

Pouchitis is defined as inflammation of the ileal pouch created during a restorative proctocolectomy with ileal pouch-anal anastomosis. Although the incidence of this inflammatory condition is high, the exact etiology often remains unclear and the management challenging. In this review, we summarize the clinical presentation, pathogenesis, diagnosis, and management of this common complication.

Gut bacteriome in inflammatory bowel disease: An update on recent advances

Inflammatory bowel diseases (IBD) are chronic inflammatory gut disorders, majorly classified as ulcerative colitis and Crohn's disease. The complex, multifactorial etiopathogenesis of IBD involves genetic predisposition, environmental cues, aberrant mucosal immune response and a disturbed gut microbiota. Epidemiological trends, studies in gnotobiotic mice models and genome-wide association studies, identifying genes involved in microbial handling, together mount evidence in support of the gut microbiota playing a pivotal role in IBD pathogenesis. Both Crohn's disease and ulcerative colitis are characterized by severe dysbiosis of the gut microbiome, marked by an expansion of detrimental taxa and concomitant depletion of beneficial members. IBD is characterized by reduction in abundances of bacterial genera involved in production of short-chain fatty acids, bio-transformations of bile acids and synthesis of indole-based tryptophan compounds such as Faecalibacterium, Ruminococcus, Coprococcus, Dorea, Parabacteroides, Eubacterium, Oscillibacter and Prevotella and elevation in members of phyla Proteobacteria and Actinobacteria. This imbalance not only results in exaggerated immune signaling towards the microbial antigens, but also results in an altered metabolomic milieu that triggers additional inflammatory cascades. The present review provides insights into the bacterial dysbiosis observed across different intestinal sites and their metabolomic imprints participating in IBD.

Comprehensive systematic review and pooled analysis of real-world studies evaluating immunomodulator and biologic therapies for chronic pouchitis treatment

Background and Aim

Pouchitis is a common complication after restorative ileal pouch-anal anastomosis following proctocolectomy for ulcerative colitis. Antibiotic-dependent or antibiotic-refractory chronic pouchitis (CP), which is a common cause of pouch failure affecting 15-20% of patients, is challenging to treat. The efficacy of second-line immunomodulator and biologic therapy remains poorly defined. We present a pooled analysis of real-world efficacy data from peer-reviewed full-text manuscripts, focusing on immunomodulator and biologic therapies in CP.

Methods

Embase and PubMed databases were searched for full-text articles describing the treatment of CP. We performed a systematic review and pooled analysis of published studies to assess the efficacy of immunomodulators, including thiopurines and methotrexate, and biologics including antitumor necrosis factor, anti-integrin, and interleukin-12/23 antagonists. Clinical and endoscopic response and remission rates were combined for pooled analyses. Rates of treatment discontinuation and safety were also assessed.

Results

Pooled analysis comprised 20 full-text articles (485 patients). Overall clinical response rate was 46% (95% CI: 35-59%) and clinical remission rate was 35% (95% CI: 21-52%). Overall endoscopic response and remission rates were 41% (95% CI: 18-68%) and 15% (95% CI: 5-39%), respectively. Individual agents' safety profile was reassuring, with vedolizumab being the most favorable.

Conclusion

The real-world efficacy data of immunomodulators in the treatment of CP is insufficient. Vedolizumab and ustekinumab appeared effective and safe for CP, whereas anti-TNFs showed higher rates of adverse events. The high heterogeneity within the studies is attributed to the real-world study design, obfuscating drug efficacy comparisons across the studies. Further studies are required to define the comparative effectiveness of available treatments of CP.

Curable leakage in stapled IPAA has little effect on the long-term pouch function

PURPOSE

This study aimed to evaluate the frequency and grade of anastomotic leakage (AL) in stapled ileal pouch-anal anastomosis (IPAA) and its long-term impact on the pouch functions.

METHODS

A longitudinal cohort study was conducted on UC patients who underwent stapled IPAA at Yokohama City University Medical Center between 2007 and 2018. The diagnosis and grading of AL were performed in accordance with the recommendations of the International Study Group of Rectal Cancer. We assessed the functional pouch rate, late complication, pouch survival rate, bowel function (bowel movements per day, soiling, spotting, difficulty in distinguishing feces from flatus) and pouch inflammation (pouchitis disease activity index; PDAI) in the long-term period.

RESULTS

Two hundred seventy-six patients were analyzed. Twenty-three (8.3%; grade B/C; 13/10) patients were diagnosed with AL, but a functional pouch was achieved in all the twenty-three patients. Anastomotic stricture was significantly more common in patients with AL (AL group) than in patients without AL (non-AL group; AL/non-AL: 13.0/3.2%, p = 0.020). There were no differences in other late complications. Furthermore, the pouch survival rate did not differ between the AL and non-AL groups (100.0/97.9%/10 years, p = 0.494). There were no differences between the groups in bowel movements per day, spotting, soling, difficulty in distinguishing feces from flatus, or PDAI postoperatively.

CONCLUSIONS

Curable AL may not affect late complications (except anastomotic stricture), pouch survival, the bowel function, or pouch inflammation over the long term. Perioperative management to prevent the severity of AL is as important as preventing its occurrence.

The efficacy of probiotics on the prevention of pouchitis for patients after ileal pouch-anal anastomosis: A meta-analysis

BACKGROUND

To date, a few studies indicated that probiotics are beneficial to pouchitis, but no meta-analyses summarized the outcomes of probiotics in pouchitis in detail.

OBJECTIVE

This meta-analysis discusses probiotics in the prevention of pouchitis for patients after ileal pouch-anal anastomosis (IPAA) and the relationship between probiotics preventive effect and the duration of therapy and history.

METHODS

PubMed, EMBASE and Cochrane Library databases were searched from inception until February 2022. Risk ratio (RR), mean difference (MD) and their 95% confidence interval (CI) were analyzed by Review Manager 5.3. The subgroup analysis was also performed to explore the agent for influencing outcomes.

RESULTS

A total of 8 studies were included in this meta-analysis. The incidence of pouchitis in probiotics was significantly lower than that in the control (RR = 0.19, 95%CI [0.12, 0.32], P⁢ï⁢¼⁢ 0.00001), and the PDAI (pouchitis disease activity index) in probiotics was also significantly lower (MD =-5.65, 95%CI [-9.48, -1.83]). After the subgroup analysis, we found that probiotics work better in the short-term (RR = 0.12, 95%CI [0.04, 0.40], P= 0.0004), but may not achieve the desired effect in the long-term (RR = 1.20, 95%CI [0.40, 3.60], P= 0.75).

CONCLUSIONS

Probiotics are beneficial in the prevention of pouchitis after IPAA, especially in the short-term.

Inflammatory bowel disease-specific findings are common morphological changes in the ileal pouch with ulcerative colitis

Why inflammation is common in ileal pouches with ulcerative colitis (UC) is unclear. We therefore clarified the morphological changes in pouches and afferent limbs (AL) of patients with UC and explored the relationship between these findings. We evaluated the morphological findings (histological and endoscopic inflammation as the Pouchitis Disease Activity Index [PDAI] histology subscore [hPDAI] and endoscopy subscore [ePDAI], inflammatory bowel disease [IBD]-specific findings using the IBD score [S_IBD], colonic metaplasia using the colonic metaplasia score [CMS], and goblet cell [GC] ratio) in the pouch and AL of patients with UC. A total of 261 pouchoscopies were analyzed. The pouch body had a higher hPDAI (p < 0.001), S_IBD (p < 0.001), CMS (p < 0.001), GC ratio (p < 0.001), and ePDAI (p < 0.001) than the AL. The hPDAI was correlated with the S_IBD (Spearman's coefficient r = 0.538; p < 0.001), CMS (r = 0.687; p < 0.001), and the ePDAI (r = 0.552; p < 0.001), but not with GC ratio (r = 0.175; p < 0.001) or the pouch usage duration (r = -0.057; p = 0.107). The incidence of histological inflammation was higher in specimens showing basal plasmacytosis with severe mononuclear cell infiltration (BP) than in those without BP (odds ratio [OR] 6.790, p < 0.001), BP was commonly found with crypt hyperplasia (OR 3.414, p < 0.001) and the crypt length correlated with neutrophil infiltration (r = 0.469; p < 0.001). Histological inflammation, colonic metaplasia, the GC ratio, endoscopic inflammation, and IBD-specific findings were commonly present in the pouch than in the AL. Histological inflammation occurs with IBD-specific findings and colonic metaplasia, and these signify endoscopic inflammation.

Pouchitis: insight into the pathogenesis and clinical aspects

Ulcerative colitis (UC) is a chronic intestinal inflammatory disease and familial adenomatous polyposis (FAP) is an autosomal dominant inherited disease. Both diseases, despite being different, may require the same surgical procedure: proctocolectomy with ileal pouch-anal anastomosis (IPAA). The main complication after this procedure is pouch inflammation (pouchitis). This inflammatory complication can affect up to 60 percent of patients who receive IPAA for UC, and a very small percentage of the FAP patients. The purpose of this review was to determine the current molecular mechanisms in its pathogenesis and detail the risk factors involved in pouchitis, its diagnosis, and treatment.

Ileal Pouch-Anal Anastomosis and Pouchitis: The Role of the Microbiota in the Pathogenesis and Therapy

Inflammatory bowel diseases, Crohn's disease and ulcerative colitis, are life-long disorders characterized by the chronic relapsing inflammation of the gastrointestinal tract with the intermittent need for escalation treatment and, eventually, even surgery. The total proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the surgical intervention of choice in subjects affected by ulcerative colitis (UC). Although IPAA provides satisfactory functional outcomes, it can be susceptible to some complications, including pouchitis as the most common. Furthermore, 10-20% of the pouchitis may develop into chronic pouchitis. The etiology of pouchitis is mostly unclear. However, the efficacy of antibiotics in pouchitis suggests that the dysbiosis of the IPAA microbiota plays an important role in its pathogenesis. We aimed to review the role of the microbiota in the pathogenesis and as a target therapy in subjects who develop pouchitis after undergoing the surgical intervention of total proctocolectomy with IPAA reconstruction.

Association Between Portal Vein Thrombosis and Pouchitis in Patients with Ulcerative Colitis

BACKGROUND

Pouchitis is the most common long-term complication in patients requiring colectomy ileal pouch-anal anastomosis with medically refractory ulcerative colitis or colitis-associated neoplasia. A previous small case series suggests associated between portal vein thrombosis (PVT) and ischemic pouchitis.

AIM

To evaluate the association between PVT and other demographic and clinical factors and pouchitis.

METHODS

We used Explorys Inc., a population-based database, to search medical records between 1999 and 2020 with SNOMED-CT code criteria for "construction of pouch" and "ileal pouchitis." Patients with pouchitis were compared to those with previous pouch construction without pouchitis. Factors associated with pouchitis identified with univariable analysis were introduced into a multivariable model. A post hoc analysis further stratified demographical findings of the association between PVT and pouchitis.

RESULTS

We identified 7900 patients with ileal pouchitis (7.5%) and 97,510 with pouch construction without pouchitis. In multivariate binary logistic regression, adjusted odds ratio (aOR) for the risk of pouchitis in patients with PVT was 10.78 (95% confidence interval [CI] 7.04-16.49, P < 0.001). Other significant factors associated with pouchitis included male gender (aOR 1.11, 95% CI 1.02-1.21, P = 0.018), deep vein thrombosis (aOR 1.46, 95% CI 1.23-1.72, P < 0.001), and the use of non-steroidal anti-inflammatory drugs (aOR 1.37, 95% CI 1.28-1.45, P < 0.001). Smoking was a protective factor (aOR 0.30, 95% CI 0.33-0.36, P < 0.001). Further sub-analysis showed a higher prevalence of younger patients with PVT and pouchitis.

CONCLUSIONS

We report PVT as an independent risk factor associated with pouchitis. Our findings support that PVT is a potentially manageable perioperative complication, and intervention may reduce the risk of pouchitis.

Prevalence of pouchitis in both ulcerative colitis and familial adenomatous polyposis: A systematic review and meta-analysis

AIM

Pouchitis is a clinically significant complication of ileal pouch-anal anastomosis with its prevalence varying in the literature. Pouchitis is thought to occur more commonly in patients with ulcerative colitis (UC) than in patients with familial adenomatous polyposis (FAP). We conducted a systematic review with meta-analysis of all published literature to report the prevalence of pouchitis in all pouch patients as well as specifically in UC and FAP. We also investigated the prevalence of acute and chronic pouchitis in UC and FAP.

METHODS

A meta-analysis was conducted by searching the Embase, Embase Classic and PubMed databases between 1978 and 2021 exploring the prevalence of pouchitis in UC and FAP. We then performed a random effects model in order to find the pooled prevalence of pouchitis and used odds ratios to report differences in the prevalence of pouchitis in UC and FAP.

RESULTS

Fifty-nine full papers and conference abstracts were included in the meta-analysis comprising 18 117 patients with UC and 860 with FAP. The prevalence of pouchitis in UC was 0.32 (95% CI 0.27-0.37) and in FAP was found to be 0.06 (95% CI 0.03-0.15). The odds ratio of pouchitis in UC patients compared with FAP patients was 4.95 (95% CI 3.17-7.72, P < 0.0001).

CONCLUSIONS

Our findings support the consensus that the prevalence of pouchitis is higher in UC than in FAP. More significantly our findings suggest that the true prevalence of pouchitis is higher than commonly reported in the literature. This literature may help counsel patients prior to undergoing restorative proctocolectomy.

α4β7 integrin-dependent adhesion of T cells to MAdCAM-1 is blocked by vedolizumab in patients with chronic refractory pouchitis

BACKGROUND

The anti-α4β7 integrin antibody vedolizumab is an established therapeutic option for the treatment of inflammatory bowel disease (IBD). It has also been successfully used in patients with chronic antibiotic-refractory pouchitis following proctocolectomey with ileal pouch-anal anastomosis. However, the expression and function of gut-homing markers as well as strategies to predict the response to vedolizumab in pouchitis are understudied so far.

METHODS

We used flow cytometry and dynamic adhesion assays to study the expression and function of gut-homing integrins on T cells from patients with pouchitis and controls as well as longitudinally during therapy of pouchitis with vedolizumab. Moreover, we describe clinical effects of vedolizumab in a cohort of patients with pouchitis.

RESULTS

T cells from patients with pouchitis express a specific profile of gut-homing integrins. Integrin α4β7 on T cells from patients with pouchitis mediates adhesion to mucosal addressin cell adhesion molecule (MAdCAM)-1, which can be blocked by vedolizumab in vitro. Vedolizumab efficiently treats pouchitis in a portion of patients and response correlates with dynamic adhesion profiles to MAdCAM-1.

CONCLUSION

Our data suggest that T cell trafficking seems to be important for the pathogenesis of pouchitis and support the therapeutic use of vedolizumab. Integrin function might serve as a biomarker to predict response to vedolizumab.

Computational Learning of microRNA-Based Prediction of Pouchitis Outcome After Restorative Proctocolectomy in Patients With Ulcerative Colitis

BACKGROUND

Ileal pouch-anal anastomosis (IPAA) is the standard of care after total proctocolectomy for ulcerative colitis (UC). However, inflammation often develops in the pouch, leading to acute or recurrent/chronic pouchitis (R/CP). MicroRNAs (miRNA) are used as accurate diagnostic and predictive biomarkers in many human diseases, including inflammatory bowel diseases. Therefore, we aimed to identify an miRNA-based biomarker to predict the occurrence of R/CP in patients with UC after colectomy and IPAA.

METHODS

We conducted a retrospective study in 3 tertiary centers in France. We included patients with UC who had undergone IPAA with or without subsequent R/CP. Paraffin-embedded biopsies collected from the terminal ileum during the proctocolectomy procedure were used for microarray analysis of miRNA expression profiles. Deep neural network-based classifiers were used to identify biomarkers predicting R/CP using miRNA expression and relevant biological and clinical factors in a discovery cohort of 29 patients. The classification algorithm was tested in an independent validation cohort of 28 patients.

RESULTS

A combination of 11 miRNA expression profiles and 3 biological/clinical factors predicted the outcome of R/CP with 88% accuracy (area under the curve = 0.94) in the discovery cohort. The performance of the classification algorithm was confirmed in the validation cohort with 88% accuracy (area under the curve = 0.90). Apoptosis, cytoskeletal regulation by Rho GTPase, and fibroblast growth factor signaling were the most dysregulated targets of the 11 selected miRNAs.

CONCLUSIONS

We developed and validated a computational miRNA-based algorithm for accurately predicting R/CP in patients with UC after IPAA.

Dysbiosis in Metabolic Genes of the Gut Microbiomes of Patients with an Ileo-anal Pouch Resembles That Observed in Crohn's Disease

Crohn's disease (CD), ulcerative colitis (UC), and pouchitis are multifactorial and chronic inflammatory bowel diseases (IBD). Pouchitis develops in former UC patients after proctocolectomy and ileal-pouch-anal anastomosis and is characterized by inflammation of the previously normal small intestine comprising the pouch. The extent to which microbial functional alteration (dysbiosis) in pouchitis resembles that of CD or UC has not been investigated, and the pathogenesis of pouchitis remains unknown. We collected 208 fecal metagenomes from 69 patients with a pouch (normal pouch and pouchitis) and compared them to publicly available metagenomes of patients with CD (n = 88), patients with UC (n = 76), and healthy controls (n = 56). Patients with pouchitis presented the highest alterations in species, metabolic pathways, and enzymes, which was correlated with intestinal inflammation. Ruminococcus gnavus strains encoding mucin-degrading glycoside hydrolases were highly enriched in pouchitis. Butyrate and secondary bile acid biosynthesis pathways were decreased in IBD phenotypes and were especially low in pouchitis. Pathways such as amino acid biosynthesis and degradation of aromatic compounds and sugars, encoded by members of the Enterobacteriaceae, were enriched in pouch and CD but not in UC. We developed microbial feature-based classifiers that can distinguish between patients with a normal pouch and pouchitis and identified species and genes that were predictive of pouchitis. We propose that the noninflamed pouch is already dysbiotic and microbially is similar to CD. Our study reveals microbial functions that outline the pathogenesis of pouchitis and suggests bacterial groups and functions that could be targeted for intervention to attenuate small intestinal inflammation present in pouchitis and CD.

IMPORTANCE Crohn's disease (CD), ulcerative colitis (UC), and pouchitis are chronic inflammatory conditions of the bowel. Pouchitis develops in former UC patients after proctocolectomy and ileal-pouch-anal anastomosis and is characterized by inflammation of the previously normal small intestine comprising the pouch. The extent to which microbial dysbiosis in patients with pouchitis resembles that of CD or UC and the pathogenesis of pouchitis remains unclear. We investigated the functions in the gut microbiomes of these patients using metagenomics. We found that the noninflamed pouch is already dysbiotic and microbially is similar to CD. Our study reveals microbial functions with a potential role in pouchitis pathogenesis such as depletion in butyrate and secondary bile acid synthesis and enrichment of amino acid synthesis and degradation of aromatic compounds, encoded by members of the Enterobacteriaceae. We developed microbial feature-based classifiers that can distinguish between patients with a normal pouch and pouchitis and identified species and genes that were predictive of pouchitis. We suggest species and functions that could be targeted for intervention to attenuate small intestinal inflammation present in pouchitis and CD.

Fungal Dysbiosis Aggravates Pouchitis in a Rat Model of Ileal Pouch Anal Anastomosis

BACKGROUND

Although the interaction between gut microbiota and pouchitis after ileal pouch anal anastomosis (IPAA) for ulcerative colitis (UC) has been confirmed, evidence of commensal mycobiota in the etiology of pouchitis is still lacking. This study aimed to investigate the role of fungi in the pathogenesis of pouchitis.

METHODS

Fecal samples were collected from UC patients with or without pouchitis after IPAA. Experimental pouchitis was induced by 5% dextran sulfate sodium for 7 consecutive days in a rat model of IPAA. Fungal dysbiosis was induced by 0.5% fluconazole (Flu), and commensal fungal recognition through dectin-1 was blocked by 5% laminarin. Fecal fungal composition was analyzed using internal transcribed spacer 2 sequencing. Severity of pouchitis and activation of the CARD9-nuclear factor kappa-B pathway was determined among different groups.

RESULTS

Patients with pouchitis had a lower alpha (α) diversity in mycobiota composition and a higher abundance of Saccharomyces at the genus level compared with those with a normal pouch. In the rat model of pouchitis, Flu treatment decreased fungal burden but induced fungal dysbiosis, characterized by increased α diversity, a decreased relative abundance of Kazachstania, and increased Polythrincium and Saccharomyces. In addition, Flu treatment worsened dextran sulfate sodium pouchitis, as indicated by increased mortality, weight loss, higher histological score, and CD4+ cell infiltration. Laminarin also increased the severity of pouchitis. In the Flu and laminarin groups, the expression of interferon-γ, tumor necrosis factor-α, CARD9, and phosphorylated nuclear factor kappa-B inhibitor alpha was decreased.

CONCLUSIONS

Patients with pouchitis had altered fungal composition. Fungal dysbiosis or recognition deficiency by the host may exacerbate experimental pouchitis. Strategies targeting commensal mycobiota may provide therapeutic potential against pouchitis, especially for antibiotic-refractory patients.

Systematic review with meta-analysis: a history of smoking is not associated with a higher risk of pouchitis

BACKGROUND

Ileal pouch-anal anastomosis is a common surgical procedure in patients with an initial diagnosis of ulcerative colitis or indeterminate colitis. Tobacco smoking has been associated with protection from onset of ulcerative colitis. Smoking has been reported to be both a protective factor and a risk factor for the development of pouchitis.

AIM

To examine the influence of smoking on the risk of pouchitis.

METHODS

We identified 15 studies evaluating smoking as a risk factor for developing pouchitis in ulcerative colitis or indeterminate colitis patients with a history of ileal pouch-anal anastomosis in a systematic search performed from inception through May 4, 2020. A meta-analysis was then performed using a random-effects model to generate risk ratios (RR) and 95% confidence intervals (CI).

RESULTS

A history of smoking compared with never smoking was not associated with an increased risk of developing pouchitis (RR = 0.94, 95% CI 0.76-1.18, I²  = 73.7%). There was also no significant risk of pouchitis when comparing current smokers vs nonsmokers (RR = 0.93, 95% CI 0.70-1.24, I²  = 78.5%) and former smokers vs nonsmokers (RR = 0.96, 95% CI 0.74-1.23, I²  = 78.5%).

CONCLUSIONS

Smoking, past or present, is not associated with an increased risk for the development of pouchitis in patients with ulcerative colitis or indeterminate colitis.

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.

Continent Ileostomy as an Alternative to End Ileostomy

Continent ileostomy (CI) was once a prevalent surgical technique for patients who required total proctocolectomy but then gave way to ileal pouch-anal anastomosis (IPAA) after 1980. Although IPAA has been the gold standard procedure preferred by most patients when total proctocolectomy is required, due to its imitation of physiological function of rectum and preserved function of anus, various complications have been observed with a relatively high rate of morbidity that could affect pouch longevity. Once serious complications such as pelvic abscesses and/or fistula occur, the pouch often needs to be removed. In addition, for some patients with a shortened small intestine or foreshortened mesentery, it is impossible for the ileal pouch to reach the pelvic floor, thus making the creation of an IPAA difficult. Previously, most of these patients would be referred for an end ileostomy, with an associated poor quality of life. In this circumstance, we propose that CI may deserve a reappraisal and serve as an alternative. In this article, we review the indications, contraindications, technique evolution, and outcomes of CI.

Prolyl Hydroxylase Inhibition Mitigates Pouchitis

BACKGROUND

Pouchitis is the most common long-term complication after restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC) or familial adenomatous polyposis (FAP), which can eventually progress to pouch failure, necessitating permanent stoma construction. Hypoxia-inducible transcription factor prolyl hydroxylase-containing enzymes (PHD1, PHD2, and PHD3) are molecular oxygen sensors that control adaptive gene expression through hypoxia-inducible factor (HIF). Emerging evidence supports PHDs as being therapeutic targets in intestinal inflammation. However, pharmacological inhibition of PHDs has not been validated as a treatment strategy in pouchitis.

METHODS

PHD1-3 mRNA and protein expression were analyzed in mucosal pouch and prepouch ileal patient biopsies. After establishment of a preclinical IPAA model in rats, the impact of the pan-PHD small-molecule inhibitor dimethyloxalylglycine (DMOG) on dextran sulfate sodium (DSS)-induced pouchitis was studied. Clinical and molecular parameters were investigated.

RESULTS

PHD1, but not PHD2 or PHD3, was overexpressed in pouchitis in biopsies of patients with IPAA for UC but not FAP. In addition, PHD1 expression correlated with disease activity. DMOG treatment profoundly mitigated DSS-induced pouchitis in a rodent IPAA model. Mechanistically, DMOG restored intestinal epithelial barrier function by induction of tight junction proteins zona occludens-1 and claudin-1 and alleviation of intestinal epithelial cell apoptosis, thus attenuating pouch inflammation.

CONCLUSIONS

Together, these results establish a strong therapeutic rationale for targeting PHD1 with small-molecule inhibitors in pouchitis after IPAA for UC.

Pouchitis: diagnosis and management

PURPOSE OF REVIEW

Pouchitis is the most common complication in patients who undergo ileal pouch-anal anastomosis (IPAA), occurring more frequently in patients with ulcerative colitis. Pouchitis - the inflammation of the pouch - can be due to idiopathic or secondary causes. Chronic antibiotic-dependent pouchitis (CADP) and chronic antibiotic-resistant pouchitis (CARP) are the most difficult forms of chronic idiopathic pouchitis to treat. Crohn's disease of the pouch may develop de novo in ulcerative colitis patients following colectomy with IPAA. It carries a high risk for pouch failure, and its diagnosis and management are challenging. The purpose of this review is to illustrate the present trends in the diagnosis and treatment of idiopathic pouchitis and Crohn's disease of the pouch.

RECENT FINDINGS

The use of the newer biologic agents, vedolizumab and ustekinumab, has shown promising results in patients with CADP, CARP, and Crohn's disease of the pouch. Fecal microbiota transplantation has also been reported to have encouraging preliminary results in small studies and case series for the treatment of chronic pouchitis.

SUMMARY

Promising new treatments are emerging for difficult-to-treat forms of pouchitis. Larger prospective and head-to-head comparative studies among the various treatments are needed to evaluate the efficacy and safety of these agents across the pouchitis subgroups, and to identify predictors of response.

DIAGNOSTIC AND MANAGEMENT APPROACH TO POUCHITIS IN INFLAMMATORY BOWEL DISEASE

In patients with ulcerative colitis refractory to medical therapy, total proctocolectomy and posterior ileal-anal pouch anastomosis is the standard surgical therapy. One of the possible complications is pouchitis. Depending on the duration of the symptoms, it can be classified as acute, recurrent, or chronic. The latter, according to the response to therapy, can be defined as antibiotic-dependent or refractory. The treatment of pouchitis is based on the use of antibiotics and probiotics. Thiopurine and biological therapy have been suggested in patients with refractory pouchitis. Special care should be taken in the endoscopic surveillance of these patients, especially if they present risk factors such as dysplasia or previous colorectal cancer, primary sclerosing cholangitis or ulcerative colitis for more than 10 years.

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

BACKGROUND AND AIMS

The pathogenesis of pouch inflammation may involve epithelial barrier disruption. We investigated whether faecal proteolytic activity is increased during pouchitis and results in epithelial barrier dysfunction through protease activating receptor [PAR] activation, and assessed whether the intestinal microbiome may be the source of the proteases.

METHODS

Faecal samples were measured for protease activity using a fluorescein isothiocyanate [FITC]-casein florescence assay. Caco-2 cell monolayers were exposed to faecal supernatants to assess permeability to FITC-dextran. Tight junction protein integrity and PAR activation were assessed by immunoblot and immunofluorescence. A truncated PAR2 protein in Caco-2 cells was achieved by stable transfection using CRISPR/Cas9 plasmid. PAR2 activation in pouch biopsies was examined using antibodies directed to the N-terminus of the protein. Microbial composition was analysed based on 16S rRNA gene sequence analysis.

RESULTS

Ten pouchitis patients, six normal pouch [NP] patients and nine healthy controls [HC] were recruited. The pouchitis patients exhibited a 5.19- and 5.35-fold higher faecal protease [FP] activity [p ≤ 0.05] compared to the NP and HC participants, respectively. The genus Haemophilus was positively associated with FP activity [R = 0.718, false discovery rate < 0.1]. Faecal supernatants from pouchitis patients activated PAR2 on Caco-2 monolayers, disrupted tight junction proteins and increased epithelial permeability. PAR2 truncation in Caco-2 abrogated faecal protease-mediated permeability. Pouch biopsies obtained from pouchitis patients, but not from NP patients, displayed PAR2 activation.

CONCLUSIONS

Protease-producing bacteria may increase faecal proteolytic activity that results in pouch inflammation through disruption of tight junction proteins and increased epithelial permeability in a PAR2-dependent manner. This mechanism may initiate or propagate pouch inflammation.

Increase in chromogranin A- and serotonin-positive cells in pouch mucosa of patients with ulcerative colitis undergoing proctocolectomy

BACKGROUND

Inflammatory bowel disease (IBD) is associated with neuroendocrine cell hyperplasia.

AIMS

We investigated neuroendocrine cells in J-pouches of patients with ulcerative colitis undergoing restorative proctocolectomy and ileal pouch-anal anastomosis.

METHODS

Sections from pouch biopsies of 17 patients and ileal biopsies of 17 active IBD patients and 16 controls were processed by immunohistochemistry for chromogranin A (CgA) and serotonin. Mucosal tryptophan hydroxylase (TpH)-1 and serotonin-selective reuptake transporter (SERT) transcripts were measured by quantitative RT-PCR. TpH-1 and SERT transcripts were detected in pouch biopsies cultured with infliximab or its isotype control, while interleukin (IL)-6 and IL-8 were measured in biopsy supernatants.

RESULTS

A significant increase in CgA-positive cells and serotonin-positive cells was observed in both pouch and IBD ileum compared to control ileum. Significantly raised transcripts of TpH-1, but not SERT, were found in IBD ileum in comparison to control ileum, with no significant difference between pouch and IBD ileum. Infliximab had no influence on ex vivo pouch expression of TpH-1 and SERT, nor on the production of IL-6 and IL-8.

CONCLUSION

We here demonstrated neuroendocrine cell hyperplasia in pouch mucosa. Further studies are needed to clarify the pathophysiological implication of this finding.

Smoking and the Risk of Pouchitis in Ulcerative Colitis Patients With Ileal Pouch-Anal Anastomosis

BACKGROUND

Ulcerative colitis (UC) patients who undergo proctocolectomy with ileal pouch-anal anastomosis (IPAA) may develop pouchitis, a poorly understood inflammatory condition. There is controversy over whether tobacco use can protect against pouchitis. We undertook this investigation to further evaluate whether smoking reduces the risk of developing pouchitis and to determine whether other previously associated clinical factors change the risk for pouchitis.

METHODS

We performed a retrospective analysis using a consented inflammatory bowel disease (IBD) natural history registry between the years 1995-2015 from a single tertiary care referral center. Demographic data, medical history, surgical information, medication use, laboratory data, and smoking history were abstracted. Former smokers had quit for at least 1 year. The primary end point was development of pouchitis.

RESULTS

Of the 353 UC patients with IPAA in this study, 126 (35.6%) developed pouchitis. Prior tobacco use (P < 0.0001) was more common in patients who developed pouchitis. Former and active smokers were more likely to develop pouchitis compared with those without a history of tobacco use (63.4% vs 27.3% respectively, P < 0.001). There was no significant difference in active smoking rate between those without pouchitis and the group that did develop pouchitis. Multivariate analysis demonstrated that the only independent risk factor associated with pouchitis was a history of tobacco use.

CONCLUSIONS

These results suggest that smoking cessation may increase the likelihood of developing pouchitis in tobacco users with UC and IPAA, but active smoking does not seem to be more effective in preventing this condition.

Systematic review: ileoanal pouch microbiota in health and disease

BACKGROUND

The resident gut microbiota is essential for physiological processes; the disturbance of its balance is linked to intestinal inflammation. The ileoanal pouch is a model for the study of intestinal inflammation, as inflammation of the pouch is common and mostly develops within 12 months following ileostomy closure. This allows the longitudinal study of the microbiota, giving insight into the microbiota changes during transition from a normal to an inflamed pouch.

AIM

To explore the literature on the microbiota of the ileoanal pouch in health and disease.

METHODS

A systematic computer search of the on-line bibliographic databases MEDLINE and EMBASE was performed between 1966 and February 2017. Randomised controlled trials, cohort studies and observational studies were included. Studies were included if they reported microbiota analysis on faecal samples or tissue from the ileoanal pouch.

RESULTS

Twenty-six papers were eligible. Following ileostomy closure, anaerobic bacteria are the abundant species in the ileoanal pouch with presence of a diverse microbiota key to maintaining a healthy ileoanal pouch. Acute pouchitis is associated with an increase in Clostridia species, while chronic pouchitis is associated with an increase in Staphylococcus aureus. In the treatment of pouchitis, a decrease in Clostridia species appears to be associated with treatment response.

CONCLUSION

The microbiota plays an important role in both the inflamed and the healthy ileoanal pouch. A direct causal relationship between individual microbiota changes and inflammation has not yet been established, but manipulation of the ileoanal pouch microbiota may be a novel therapeutic avenue to explore.

NOD2 Genetic Variants Predispose One of Two Familial Adenomatous Polyposis Siblings to Pouchitis Through Microbiome Dysbiosis

BACKGROUND AND AIMS

Individuals with familial adenomatous polyposis (FAP) may undergo a total proctocolectomy with ileal pouch-anal anastomosis (IPAA) to surgically treat their disease. Inflammation of the ileal pouch, termed pouchitis, is uncommon in FAP patients but prevalent in patients who received IPAA for ulcerative colitis, a type of inflammatory bowel disease (IBD).

METHODS AND RESULTS

We report on two FAP siblings, living in the same household, who underwent IPAA surgery within one week of each other. Their mother also had an IPAA for FAP. One sibling developed pouchitis while his brother and mother have remained pouchitis-free. We investigated the genetic and microbial factors that might explain the development of pouchitis in the one sibling. We surveyed DNA isolated from the two brothers and their parents for NOD2 IBD risk variants by Sanger sequencing. The composition of mucosa-associated bacteria was analyzed by 16S rRNA gene sequencing on terminal ileum and rectal tissue collected at the time of surgical resection from the two brothers. The sibling with pouchitis inherited the IBD-associated risk alleles for NOD2 (rs17221417 and rs2076756) from his healthy father. Both the mother and unaffected brother lacked these variants. Microbiome sequencing of the terminal ileum and rectum found reduced levels of potentially 'beneficial' bacteria (Faecalibacterium prausnitzii, Bacteroides, and Ruminococcaceae) in the sibling with pouchitis relative to his brother.

CONCLUSION

These findings suggest that the NOD2 signaling pathway may contribute to intrinsic bacterial dysbiosis which is pre-existing and which may then predispose individuals to pouchitis after IPAA surgery.

The outcome of ulcerative colitis patients undergoing pouch surgery is determined by pre-surgical factors

BACKGROUND

Pouch surgery, a common intervention for ulcerative colitis (UC) complications, is often associated with the development of pouchitis.

AIM

To identify predictors of pouch outcome in a cohort of patients with UC.

METHODS

We conducted a retrospective unmatched case-cohort study in a tertiary IBD referral centre. Adult patients with UC were classified into the worst phenotype throughout follow-up: normal pouch, a form of chronic pouchitis (either chronic pouchitis or Crohn's like disease of pouch [CLDP]), or episodic recurrent acute pouchitis (RAP). Risk factors for pouchitis (chronic forms) were detected using statistical models.

RESULTS

Two hundred and fifty-three pouch patients were followed up for 13.1±7.3 years. Only 71 patients (28.1%) maintained a favourable outcome of a sustained normal pouch. These patients were older at UC diagnosis (27.8±12.5 vs 23.0±11.4 years), had longer UC duration until surgery (13.4±9.5 vs 8.2±7.9 years), and had higher rates of referral to surgery due to nonrefractory (dysplasia/neoplasia) complications (42.3% vs 16.2%) compared with pouchitis patients. Median survival for sustained normal pouch was 10.8 years (95% CI 8.9-12.7 years), and it was longer in the nonrefractory group (20.3 vs 9.4 years for the refractory group, HR=2.37, 95% CI 1.25-3.52, P=.004).

CONCLUSIONS

Most patients with UC undergoing pouch surgery will develop pouchitis. Patients operated for nonrefractory indications have a more favourable outcome. These results may contribute to pre- and post-surgical decision-making. The findings imply that the processes determining UC severity may be similar to that causing pouchitis.

Predictors of pouchitis after ileal pouch-anal anastomosis in pediatric-onset ulcerative colitis

OBJECTIVES

Few studies have reported on the incidence and risk factors for pouchitis following colectomy and ileal pouch-anal anastomosis (IPAA) in patients with pediatric-onset ulcerative colitis (UC). We aimed to determine clinical predictors for the development of pouchitis following IPAA in this population.

PATIENTS AND METHODS

We performed a retrospective chart review of all pediatric UC cases that were diagnosed at the Schneider Children's Medical Center of Israel between 1981 and 2013 and who underwent colectomy during disease course. Potential predictors for pouchitis and chronic pouchitis including various demographic, clinical, endoscopic, and histological variables at diagnosis and at the time of surgery were assessed.

RESULTS

Of 188 patients with pediatric-onset UC, 33 (18%) underwent colectomy and IPAA surgery. During a median postsurgical follow-up of 7.6 (range: 1-21.5) years following IPAA, 20/33 (60%) patients developed pouchitis including 11/33 (33%) patients who developed chronic pouchitis. Kaplan-Meier survival estimates of the cumulative probability for pouchitis were 9% at 1 year and 36 and 55% at 5 and 10 years, respectively. Multivariate Cox models showed that older age at colectomy (hazard ratio: 0.86, P=0.024) was a protective factor, whereas preoperative vitamin-D deficiency (≤20 ng/ml) (hazard ratio: 4.4, P=0.021) increased the risk for pouchitis. Age at diagnosis, sex, disease extent, and preoperative therapeutic regimens did not affect the risk of pouchitis.

CONCLUSION

Long-term risk for pouchitis is significantly high in pediatric-onset UC after IPAA. Vitamin-D deficiency and younger age at colectomy may increase the risk for pouchitis.