Results of the Fifth Scientific Workshop of the ECCO (II): Pathophysiology of Perianal Fistulizing Disease

Efficacy and Safety of Hyperbaric Oxygen Therapy in Fistulizing Crohn's Disease: A Systematic Review and Meta-analysis

BACKGROUND

Hyperbaric oxygen therapy (HBOT) delivers 100% oxygen in a pressurized chamber, increasing tissue oxygen levels and regulating inflammatory pathways. Mounting evidence suggests that HBOT may be effective for inflammatory bowel disease. Our systematic review and meta-analysis aimed to quantify the efficacy and safety of HBOT in fistulizing Crohn's disease (CD).

METHODS

A systematic review was conducted using the EMBASE, Web of Science, Pubmed, and Cochrane Library databases according to the "Preferred Reporting Items for Systematic Reviews and Meta-analyses" criteria. Study bias was assessed using the Cochrane Handbook guidelines.

RESULTS

Sixteen studies with 164 patients were included in the analysis. For all fistula subtypes, the pooled overall clinical response was 87% (95% CI: 0.70-0.95, I2 = 0) and the pooled clinical remission was 59% (95% CI: 0.35-0.80, I2 = 0). The overall clinical response was 89%, 84%, and 29% for perianal, enterocutaneous, and rectovaginal fistulas, respectively. On meta-regression, hours in the chamber and the number of HBOT sessions were not found to correlate with clinical response. The pooled number of adverse events was low at 51.7 per 10,000 HBOT sessions for all fistula types (95% CI: 16.8-159.3, I2 = 0). The risk of bias was observed across all studies.

CONCLUSION

HBOT is a safe and potentially effective treatment option for fistulizing CD. Randomized control trials are needed to substantiate the benefit of HBOT in fistulizing CD.

Where Are We and Where to Next?-The Future of Perianal Crohn's Disease Management

Perianal fistulizing Crohn's Disease (pCD) affects about 25% of patients with Crohn's Disease (CD). It remains a difficult entity to manage with a therapeutic ceiling of treatment success despite improving medical and surgical management. The refractory nature of the disease calls for an imminent need to better understand its immunopathogenesis and classification to better streamline our treatment options. In this article, we overview the current state of pCD management and discuss where the future of its management may lie.

An Analysis of the Content of Metalloproteinases in the Intestinal Wall of Patients with Crohn's Disease

One of the inflammatory bowel diseases is Crohn's disease. Although this term has been used in the medical community since 1932, a significant increase in the number of publications occurs at the end of the 20th century and the beginning of the 21st century. Crohn's disease is a disease that cannot be fully cured. In many cases, it is chronic, i.e., recurrent. All preventive and therapeutic measures taken by doctors are aimed at inhibiting the development of the disease and minimizing the occurrence of any potential "side effects" resulting from the developing disease. One of the diagnostic methods is the qualitative and quantitative determination of metalloproteinases in inflammatory tissues and in the blood. The aim of the study was the quantitative and qualitative determination of metalloproteinases in inflammatory bowel tissues in patients diagnosed with Crohn's disease. The in vitro study was performed on surgical tissues from patients diagnosed with Crohn's disease. The results show that in inflammatory tissues the concentration of metalloproteinases -3, -7, -8, -9 was higher compared to tissues taken from the resection margin without signs of inflammation, defined as healthy. The experiment confirmed that the biochemical test, which is the determination of metalloproteinases in tissues, is a useful diagnostic tool to differentiate inflammatory from non-inflammatory tissues.

Management of Perianal Fistulizing Crohn's Disease

Perianal fistulizing Crohn's disease (CD) represents a severe phenotype of CD that is associated with significant morbidity and reduction in quality of life. Perianal fistulizing CD is caused by a complex interplay of genetic predisposition, immune dysregulation, gut dysbiosis, and various unknown physiological and mechanical factors. A multidisciplinary approach is hence required for optimal management . A detailed anatomical description and classification of perianal fistula, including comprehensive clinical, endoscopic, and radiological diagnostic workup, is an important prerequisite to treatment. For simple perianal fistulas, use of antibiotics and immunomodulators, with or without fistulotomy, are appropriate measures. The medical management of complex perianal fistula, on the other hand, requires adequate control of infection before initiation of therapy with immunomodulators. In active complex perianal fistula, anti-tumor necrosis factors remain the most accepted therapy, with concomitant use of antibiotics or immunomodulators enhancing the efficacy. For patients refractory to anti-tumor necrosis factors, treatment with anti-integrins, anti-interleukins, and small molecules is being evaluated. Mesenchymal stem cells, hyperbaric oxygen therapy, and exclusive enteral nutrition have also been investigated as adjunct therapies. Despite the expansion of the medical armamentarium, a large proportion of the patients require surgical interventions. In this review, we provide an up-to-date overview of the pathophysiology, clinical presentation, diagnosis, and medical management of perianal fistulizing CD. A brief overview of the surgical management of perianal fistulizing CD is also provided.

Network meta-analysis: efficacy and safety of treatments for fistulising Crohn's disease

INTRODUCTION

Fistulas are a debilitating complication of Crohn's disease and treatment options remain limited. There is a lack of head-to-head comparisons between treatments. To our knowledge, this is the first network meta-analysis on the efficacy of medical therapies in achieving fistula remission and maintenance of fistula closure in Crohn's disease.

METHODS

Biomedical databases and the Cochrane Central Registry were searched between 1978 and 2022 for randomized controlled trials (RCTs) reporting on treatments. A network meta-analysis was performed using the frequentist model with pooled relative risks (RRs) and P -scores used to rank treatments.

RESULTS

Twenty-five RCTs were included for analysis with 2239 patients included. At the 16-24 week time point, infliximab produced the only statistically significant result with the 5 mg/kg dose proving the most effective [RR, 2.30; 95% confidence interval (CI), 1.40-3.77]. At 44 weeks, ustekinumab was found to be most superior with it being 2.38 times (RR, 2.38; 95% CI, 1.24-4.56) more superior to placebo, with adalimumab (RR, 2.06; 95% CI, 1.06-3.99) and infliximab 5 mg/kg (RR, 1.68; 95% CI, 1.03-2.75) also producing a statistically significant result.

CONCLUSION

Despite infliximab being favoured in international guidelines for the treatment of perianal fistulising Crohn's disease, biologics such as ustekinumab, vedolizumab and adalimumab show promising results.

Management of Enterovesical Fistula in a Patient with Crohn's Disease: A Case Report and Literature Review

Enterovesical fistula (EVF) is a rare complication of Crohn's disease (CD), characterized by recurrent urinary tract infections, fecaluria, and pneumaturia. However, most diagnostic tools have low sensitivity for EVF. Management consists of conservative and surgical approaches. Conservative treatment is usually adopted first. However, the appropriate time to consider surgery remains controversial. Herein, we report on the case of a 34-year-old male who presented with diffuse abdominal pain with fullness for one day. Enteroscopy and biopsy confirmed the diagnosis of Crohn's disease. Contrast-enhanced computed tomography (CT) suggested a fistula between the ileum and urinary bladder; however, cystoscopy did not find an obvious tract. The patient initially received medical treatment, but the symptoms persisted with recurrent urinary tract infections and subsequent bilateral hydronephrosis. He then underwent successful fistulectomy, partial cystectomy, and two segmental resections of the small bowel with end-to-end primary sutures. No complications or symptomatic urinary tract infections were noted during 30 months of follow-up after surgery, suggesting no recurrence of EVF. Surgical intervention is warranted when medical treatment fails or complications occur. Clinical symptoms and laboratory data are often less informative for the diagnosis of EVF, and CT is the most helpful diagnostic modality. Our management strategy provides an option for such patients.

Causal Link between Inflammatory Bowel Disease and Fistula: Evidence from Mendelian Randomization Study

BACKGROUND

Previous observational studies have found that fistulas are common in Crohn's disease (CD) and less common in ulcerative colitis (UC). However, some patients have a fistula before diagnosis. Based on retrospective analysis, it was not possible to determine whether there was a bi-directional causal relationship between inflammatory bowel disease (IBD) and fistulas.

METHODS

Data were extracted from the open GWAS database; 25,042 cases and 34,915 controls were included for IBD, and 6926 cases and 30,228 controls were included for fistula. Two-sample Mendelian randomization and multivariable Mendelian randomization were used in combination to determine the causal relationship between IBD and fistula.

RESULTS

Forward MR showed that IBD increased the risk of colonic or urogenital fistula (FISTULA) (OR: 1.09, 95% CI: 1.05 to 1.13, p = 1.22 × 10^-6), mainly associated with fissure and fistula of the anal and rectal regions (FISSANAL) (OR:1.10, 95% CI:1.06 to 1.14, p = 6.12 × 10^-8), but not with fistulas involving the female genital tract (FEMGENFISTUL) (OR:0.97, 95% CI: 0.85 to 1.11, p = 0.669). Furthermore, both UC and CD increased the risk of FISTULA. However, after adjusting by MVMR, only CD increased the risk of FISTULA (OR: 1.06, 95% CI: 1.02 to 1.11, p = 0.004), and UC did not increase the risk of FISTULA (OR: 1.01, 95% CI: 0.95 to 1.06, p = 0.838). Reverse MR showed that fistulas did not increase the risk of IBD.

CONCLUSION

Our study confirms it is CD, rather than UC, that casually leads to an increased risk of fistula, but fistulas do not increase the risk of IBD.

The Intersection of Human and Veterinary Medicine-A Possible Direction towards the Improvement of Cell Therapy Protocols in the Treatment of Perianal Fistulas

The effective treatment of perianal fistulizing Crohn's disease is still a challenge. Local administration of mesenchymal stromal cells (MSCs) is becoming a part of accepted treatment options. However, as a fledgling technique, it still can be optimized. A new trend in translational research, which is in line with "One Health" approach, bases on exploiting parallels between naturally occurring diseases affecting humans and companion animals. Canine anal furunculosis (AF) has been indicated as condition analogous to human perianal Crohn's disease (pCD). This narrative review provides the first comprehensive comparative analysis of these two diseases based on the published data. The paper also outlines the molecular mechanisms of action of MSCs which are likely to have a role in modulating the perianal fistula niche in humans, and refers them to the current knowledge on the immunomodulatory properties of canine MSCs. Generally, the pathogenesis of both diseases shares main determinants such as the presence of genetic predispositions, dysregulation of immune response and the relation to intestine microbiota. However, we also identified many aspects which should be further specified, such as determining the frequency of true fistulas formation in AF patients, elucidating the role of TNF and Th17 pathway in the pathogenesis of AF, or clarifying the role of epithelial-to-mesenchymal transition phenomenon in the formation of canine fistulae. Nevertheless, the available data support the hypothesis that the results from testing cell therapies in dogs with anal furunculosis have a significant translational value in optimizing MSC transplants procedures in pCD patients.

Endoscopic Therapy for Fistulas and Abscesses in Crohn's Disease

Crohn disease (CD) patients can develop fistula or abscess from persistent active disease or postsurgical complications. Penetrating CD is traditionally treated with medication and surgery. The role of medication alone in the treatment of fistula is limited, except perianal fistulas or enterocutaneous fistula. Surgery is the standard treatment in those with hollow-organ to hollow-organ fistula, like ileovesicular fistula. Surgery is invasive with a higher risk of postoperative complications. Endoscopic therapy has evolved as a valid option. Fistulotomy, surgical or endoscopic, should be considered first-line therapy when feasible. Incision and drainage of perianal abscesses with an endoscopic device may be attempted.

Pathogenesis of Fistulating Crohn's Disease: A Review

Sustained, transmural inflammation of the bowel wall may result in the development of a fistula in Crohn's disease (CD). Fistula formation is a recognized complication and cause of morbidity, occurring in 40% of patients with CD. Despite advanced treatment, one-third of patients experience recurrent fistulae. Development of targeting treatment for fistulae will be dependent on a more in depth understanding of its pathogenesis. Presently, pathogenesis of CD-associated fistulae remains poorly defined, in part due to the lack of accepted in vitro tissue models recapitulating the pathogenic cellular lesions linked to fistulae and limited in vivo models. This review provides a synthesis of the existing knowledge of the histopathological, immune, cellular, genetic, and microbial contributions to the pathogenesis of CD-associated fistulae including the widely accredited contribution of epithelial-to-mesenchymal transition, upregulation of matrix metalloproteinases, and overexpression of invasive molecules, resulting in tissue remodeling and subsequent fistula formation. We conclude by exploring how we might utilize advancing technologies to verify and broaden our current understanding while exploring novel causal pathways to provide further inroads to future therapeutic targets.

Crohn's Disease with Fistula: 10 Year Trends and Mortality in the United States

BACKGROUND/AIMS

Crohn's disease (CD) results in significant morbidity, mortality, and healthcare burden. This study evaluated the temporal trends of CD hospitalizations with a fistula over the last decade to understand the outcomes of severe CD.

METHODS

National Inpatient Sample database from 2009 to 2019 was used to identify CD hospitalizations with a fistula. The outcomes of interest included temporal trend analysis of length of stay (LOS), mean inpatient cost (MIC), and mortality.

RESULTS

There was an increase in the total number of fistulizing CD hospitalizations from 5,386 in 2009 to 12,900 in 2019 (p<0.01). The mean age decreased from 44.9±0.6 to 41.8±0.4 years for the study period (p<0.01). Caucasians were the predominant ethnicity, followed by Africans, Hispanics, and others (p<0.001). The mean LOS for fistulizing CD hospitalizations decreased significantly from 11.57±0.09 days in 2009 to 7.20±0.05 days in 2019 (p<0.001). There was a significant decrease in inpatient mortality from 1.72% in 2009 to 0.73% in 2019 (p<0.01). The MIC did not have a significant trend. There was a decreasing trend toward partial/total colectomies, rectosigmoid, and small bowel surgeries from 2009 to 2019 (p<0.001).

CONCLUSIONS

There has been a rise in CD hospitalizations with fistulizing disease in the last decade. Despite this, the mortality and inpatient LOS have been decreasing significantly. In addition, the increase in CD hospitalizations with fistulizing disease has had no significant effect on hospital costs.

A Microbial Signature for Paediatric Perianal Crohn's Disease

BACKGROUND AND AIMS

Perianal fistulising disease can affect up to 25% of patients with Crohn's disease [CD] and lead to significant morbidity. Although the role of the gut microbiota in inflammatory bowel disease [IBD] has been increasingly recognised, its role in fistula development has scarcely been studied. Here, we aimed to define the microbial signature associated with perianal fistulising CD in children.

METHODS

A prospective observational study including children age 6-18 years with a diagnosis of perianal fistulising CD was conducted. Stool samples and rectal and perianal fistula swabs were collected. Stool samples and rectal swabs from children with CD without perianal disease and healthy children were included as comparison. Whole shotgun metagenomic sequencing was performed.

RESULTS

A total of 31 children [mean age 15.5 ± 3.5 years] with perianal CD were prospectively enrolled. The fistula-associated microbiome showed an increase in alpha diversity and alteration in the abundance of several taxa compared with the rectal- and faecal-associated microbiome with key taxa belonging to the Proteobacteria phylum. Genes conferring resistance to the clinically used antibiotic regimen ciprofloxacin and metronidazole were found in the three sample types. In comparison with children without the perianal phenotype [N = 36] and healthy controls [N = 41], the mucosally-associated microbiome of children with perianal CD harboured a reduced butyrogenic potential. Linear discriminant analysis identified key taxa distinguishing the rectal mucosally-associated microbiome of children with perianal CD from children without this phenotype.

CONCLUSIONS

The microbial community within CD-related anorectal fistula is compositionally and functionally unique. Taken together, these findings emphasise the need to better understand the ecosystem of the fistula milieu to guide development of novel microbiome-based strategies in this CD phenotype.

Serological biomarkers of type I, III and IV collagen turnover are associated with the presence and future progression of stricturing and penetrating Crohn's disease

BACKGROUND

Increased collagen remodelling is a key pathophysiological component underlying intestinal stricture and fistula development in Crohn's disease (CD).

AIMS

To investigate associations between serological biomarkers of collagen turnover and disease behaviour according to the Montreal classification in patients with CD.

METHODS

Serological biomarkers of type III/IV collagen formation (PRO-C3, PRO-C4) and matrix metalloproteinase (MMP) or granzyme-B (GrzB)-mediated type I, III, IV and VI collagen degradation (C1M, C3M, C4M, C4G, C6Ma3) were measured using neo-epitope protein fingerprint assays in 101 patients with CD (Montreal B1: n = 37; B2: n = 27; B3: n = 37) and 96 controls. Patients were followed up until their last outpatient visit to monitor stricturing/penetrating disease progression and recurrence and the occurrence of surgical interventions.

RESULTS

C1M, C3M and C4M were significantly reduced in patients with stricturing disease (Montreal B2) and accurately differentiated them from patients with either non-stricturing, non-penetrating (B1) or penetrating (B3) disease (all p < 0.001, multivariable analysis). Similarly, the type IV collagen formation/degradation (PRO-C4/C4M) ratio demonstrated high discriminative capacity (B1/B2: AUC = 0.90; B1/B3: AUC = 0.87, both p < 0.001, multivariable analysis). Prospectively, higher baseline levels of C1M and C4G were associated with an increased risk of penetrating disease progression (C4G: hazard ratio [HR] 1.71 [1.05-2.81], p < 0.05).

CONCLUSIONS

Elevated degradation of type I, III and IV collagen and excessive (relative) formation of type IV collagen strongly associates with stricturing CD. Type I and IV collagen fragments show predictive potential for the risk of penetrating disease progression. These biomarkers may become valuable tools for detection and prediction of stricturing and penetrating CD.

MMP9 expression in intestinal fistula from patients with fistulizing CD and from human xenograft mouse model

Fistula treatment represents a major unmet medical need in the therapy of Crohn's disease (CD). Current medical therapies, such as anti-TNF antibody treatments, are often insufficient and do not achieve permanent fistula closure. Previously published data point toward a critical role for metalloproteinase-9 (MMP-9)/gelatinase B in fistula pathogenesis. The aim of this project was to investigate in detail MMP-9 expression in different fistula types and to confirm that MMP-9 is a potential target for fistula therapy in CD patients.Immunohistochemistry for total and active MMP-9, Cytokeratin 8 (CK-8) and co-staining of active MMP-9/CK-8 was performed in specimen derived from perianal fistulas, entero-enteric fistulas and fistulas from patients not responding to anti-TNF therapy. In addition, fistulas from the xenograft mouse model (anti-TNF treated or untreated) were analyzed.Total and active MMP-9 protein was detectable in cells lining the tracts of perianal and entero-enteric fistulas. Of note, total and active MMP-9 was also expressed in fistulas of CD patients non-responding to anti-TNF treatment. Interestingly, we detected considerable co-staining of active MMP-9 and CK-8 in particular in cells lining the fistula tract and in transitional cells around the fistulas. Furthermore, total and active MMP-9 are detectable in both anti-TNF treated and untreated xenograft fistulas.Taken together, our data suggest that MMP-9 is involved in fistula pathogenesis in CD patients, in fistulas of different origins and particularly in patients non-responding to anti-TNF therapy. Our xenograft fistula model is suitable for in vivo studies investigating a possible therapeutic role for MMP-9 targeting as fistula therapy.

Vedolizumab for perianal fistulizing Crohn's disease: systematic review and meta-analysis

BACKGROUND/AIMS

Perianal fistulas are a debilitating manifestation of Crohn's disease (CD). Despite the advent of anti-tumor necrosis factor (anti-TNF) therapy, the medical management of fistulizing CD continues to be challenged by unmet needs. We conducted a systematic review and meta-analysis of the effectiveness of vedolizumab for the management of perianal fistulizing CD.

METHODS

A search of PubMed, EMBASE and the Cochrane Library was performed from inception to June 2020 for studies reporting rates of perianal fistula healing in CD patients treated with vedolizumab. The primary outcome of interest was complete healing of perianal fistulas and the secondary outcome was partial healing. The pooled fistula healing rates with 95% confidence intervals (CI) were calculated utilizing a random effects model.

RESULTS

A total of 74 studies were initially identified, 4 of which met the inclusion criteria. A total of 198 patients with active perianal fistulas were included, 87% of whom had failed previous anti-TNF therapy. The pooled complete healing rate was 27.6% (95% CI, 18.9%-37.3%) with moderate heterogeneity (I2=49.4%) and the pooled partial healing rate was 34.9% (95% CI, 23.2%-47.7%) with high heterogeneity (I2=67.1%).

CONCLUSIONS

In a meta-analysis of 4 studies that included 198 patients with perianal fistulizing CD, the majority of whom had failed previous anti-TNF therapy, vedolizumab treatment led to healing of perianal fistulas in nearly one-third of the patients. The lack of high-quality data and significant study heterogeneity underscores the need for future prospective studies of fistula healing in patients receiving anti-integrin therapy.

Does Anti-TNF-α Therapy Affect the Bacteriological Profile of Specimens Collected from Perianal Lesions? A Retrospective Analysis in Patients with Crohn's Disease

Anal abscesses and fistulas are potential complications of Crohn’s disease (CD). Chronic immunosuppression, loose stools, and poor wound healing in this population present challenges to the management of perianal diseases. The purpose of the study was to determine the predominant bacterial species found in specimens from perianal lesions causing anal abscess and/or fistula drainage in hospitalized patients, and to compare the number and type of microorganisms isolated from samples taken from patients undergoing biological therapy or traditionally treated. The outcomes of studies of patients treated for anal abscesses or fistulas from 2017 to 2019 were evaluated. Data obtained from medical records included culture and antibiotic sensitivity results of swabs from perianal lesions of isolated microorganisms. A total of 373 swabs were collected from perianal lesions during the analysis period, including 51 (49 positive samples) from patients with CD. The predominant pathogen was Escherichia coli (55%, p < 0.001), the second most common microorganism was Staphylococcus aureus (14.3%, p < 0.001). In vitro susceptibility testing showed E. coli, ESBL (strain with Extended Spectrum Beta-Lactamase) in five cases, S. aureus, MRSA (methicillin-resistant S. aureus -resistant to all beta-lactam antibiotics: penicillins with inhibitors, cephalosporins, monobactams, carbapenems, except for ceftaroline) in one sample. Biologic therapy does not affect the type of microorganisms isolated from perianal abscesses in patients with CD.

Surgical closure, mainly with glue injection and anti-tumour necrosis factor α, in fistulizing perianal Crohn's disease: A multicentre randomized controlled trial

AIM

In patients with fistulizing perianal Crohn's disease (CD), the need for a secondary surgical step is not defined. The aim was to assess the efficacy of surgical closure compared to a single seton removal in patients with drained fistulizing perianal CD treated with adalimumab.

METHODS

This was a multicentre, randomized controlled trial, comparing seton removal + surgical closure (closure group) to seton removal alone (control group) with a stratification according to the American Gastroenterological Association classification. The primary end-point was fistula closure at month 12 defined by the association of the following criteria: no seton, absence of a visible external opening, absence of discharge from the tract after finger compression, absence of an internal opening, absence of perianal pain/abscess and absence of fistula-related abnormalities.

RESULTS

Among the 64 included patients (262 expected) (48 complex fistula, 75%), 33 were randomized to the closure group and 31 to the control group. In the closure group, 26 patients (78.8%) had glue. At month 12, overall fistula closure was achieved in 35 of the evaluable 58 patients (60%): 18/32 (56%) in the surgery group and 17/26 (65%) in the control group (P = 0.479). In the closure group, fistula closure was observed in 13/25 (52%) and 5/7 (71%) patients with complex and simple fistula respectively (P = 0.426), compared with 12/18 (67%) and 5/8 (63%), respectively in the control group (P = 1.000).

CONCLUSIONS

Seton removal alone seems to be no more effective than a secondary surgical step (in particular glue injection) in patients having fistulizing perianal CD controlled by an initial drainage combined with adalimumab. The results should be interpreted with caution.

Perianal magnetic resonance imaging findings and their potential impact on outcome in children with perianal fistulizing Crohn disease

BACKGROUND

Children with perianal fistulizing Crohn disease require intensive medical management but also have a higher risk for subsequent surgical interventions.

OBJECTIVE

We performed a retrospective study to identify patient factors and perianal anatomical features by pelvic MR that are associated with surgical interventions in these children.

MATERIALS AND METHODS

We included children with Crohn disease and perianal fistula who underwent pelvic MR with available, archived images and collected demographic, clinical and laboratory data. Radiologists reviewed pelvic MR exams and identified Park classification and additional anatomical features of perianal fistulas, including fistula branching, horseshoe ramifications, abscess, inflammatory mass, supralevator extension, anal sphincter damage, proctitis and posterior anal space involvement. We performed univariate and subsequent multivariate analysis to determine features associated with subsequent surgical intervention.

RESULTS

Ninety-nine children with Crohn disease underwent pelvic MR. In this cohort, 69 children had no surgical interventions prior to baseline MRI, with subsequent median clinical follow-up of 5.5 years. Univariate analysis demonstrated that branching (P=0.009), supralevator extension (P=0.015) and anal sphincter damage (P=0.031) were significantly associated with subsequent surgical intervention. Age at baseline MRI was also associated with intervention (hazard ratio [HR] every 5 years: 2.13; 95% confidence interval [CI]: 1.18-3.83; P=0.012). A multivariable model identified only fistula branching (HR: 2.31; 95% CI: 1.28-4.15; P=0.005) and age (HR: 5.18; CI: 1.57-17.14; P=0.007) as independent predictors of subsequent surgery. No demographic, clinical or laboratory parameter predicted subsequent surgical intervention.

CONCLUSION

Age and anatomical MR features indicating fistula complexity (branching, supralevator extension) and sphincter damage confer a higher risk of subsequent surgical intervention in children with perianal Crohn disease.

Expression of Cytokine-Coding Genes BMP8B, LEFTY1 and INSL5 Could Distinguish between Ulcerative Colitis and Crohn's Disease

Ulcerative colitis (UC) and Crohn’s disease (CD) are characterized by an imbalance between pro-inflammatory and anti-inflammatory cytokines, interfering with the resolution of inflammation. Due to the crucial role of cytokines, new insights into their profiles in UC and CD would help to improve our understanding of pathogenesis and enable the development of new treatment modalities. We provide an expression profile of cytokines in UC and CD, using bioinformatics approach, and experimental validation of expression of the selected genes. We retrieved data and analyzed the cytokine gene expression profiles of UC and CD. From ten genes with inverse expression, common to CD and UC, BMP8B, LEFTY1 and INSL5 were selected for gene expression experimental validation. Experimentally, BMP8B and INSL5 were down-regulated in both CD and UC but followed the bioinformatics trend. The expression of genes LEFTY1 and BMP8B was statistically significant when comparing UC and CD in colon and the expression of gene LEFTY1 showed statistical significance when CD in ileum and colon were compared. Using the bioinformatics approach and experimental validation, we found differences in expression profiles between UC and CD for INSL5, LEFTY1 and BMP8B. These three promising candidate genes need to be further explored at different levels, such as DNA methylation and protein expression, to provide more evidence on their potential diagnostic role in CD and UC.

Current concepts in the pathogenesis of cryptoglandular perianal fistula

Cryptoglandular perianal fistula is a common benign anorectal disorder that is managed mainly with surgery. A fistula is typically defined as a pathological communication between two epithelialized surfaces. More specifically, perianal fistula manifests as an abnormal tract between the anorectal canal and the perianal skin. Perianal fistulas are often characterized by significantly decreased patient quality of life. The cryptoglandular theory of perianal fistulas suggests their development from the proctodeal glands, which originate from the intersphincteric plane and perforate the internal sphincter with their ducts. Involvement of proctodeal glands in the inflammatory process could play a primary role in the formation of cryptoglandular perianal fistula. The objective of this narrative review was to investigate the current knowledge of the pathogenesis of cryptoglandular perianal fistula with the specific aims of characterizing the potential role of proinflammatory factors responsible for the development of chronic inflammation. Further studies are crucial to improve the therapeutic management of cryptoglandular perianal fistulas.

Contribution of CD3+CD8- and CD3+CD8+ T Cells to TNF-α Overexpression in Crohn Disease-Associated Perianal Fistulas and Induction of Epithelial-Mesenchymal Transition in HT-29 Cells

BACKGROUND

Fistulas represent a frequent and severe complication in patients with Crohn disease (CD). Tumor necrosis factor-alpha (TNF-α), transforming growth factor-beta, and interleukin (IL)-13 are known to trigger epithelial-mesenchymal transition (EMT), promoting fistula formation. Here, we investigated the role of T-lymphocytes (T cells) in fistula pathogenesis.

METHODS

CD3+CD8-, CD3+CD8+, or CD45+CD3- cells from healthy volunteers, patients with CD, and patients with CD with perianal fistula were co-cultured with HT-29 cells. The EMT, cytokine production, and mRNA expression were analyzed. Perianal CD fistula specimens were immunohistochemically stained for cytokines and their receptors. The effect of cytokines on EMT induction was investigated using an EMT spheroid model.

RESULTS

Patients with CD with fistula revealed more CD3+CD8- and less CD3+CD8+ T cells in blood than healthy control patients and patients with CD without fistula. In perianal fistula specimens, CD4+ cells-and to a lesser extent CD8+ cells-were highly present around fistula tracts. When co-cultured with HT-29 cells, both cell subsets promoted EMT-related gene expression and TNF-α production in a time-dependent manner. The CD3+CD8- T cells from patients with CD with fistula also produced higher amounts of IL-13 than cells from healthy control patients or patients with CD without a fistula. We found that IL-22 and IL-22Rα1 were highly expressed in perianal CD fistula specimens and that IL-22 cotreatment potentiated TNF-α-induced EMT in HT-29 spheroids.

CONCLUSIONS

Our data indicate that both CD3+CD8- and CD3+CD8+ T cells play an important role in the pathogenesis of perianal CD fistulas by the secretion of TNF-α. Our data support clinical evidence indicating that anti-TNF-α therapy is effective in fistula treatment and identify IL-13 and IL-22 as possible novel therapeutic targets for fistula therapy.

Treatment Strategy for Perianal Fistulas in Crohn Disease Patients: The Surgeon's Point of View

Perianal fistula is a frequent complication and one of the subclassifications of Crohn disease (CD). It is the most commonly observed symptomatic condition by colorectal surgeons. Accurately classifying a perianal fistula is the initial step in its management in CD patients. Surgical management is selected based on the type of perianal fistula and the presence of rectal inflammation; it includes fistulotomy, fistulectomy, seton procedure, fistula plug insertion, video-assisted ablation of the fistulous tract, stem cell therapy, and proctectomy with stoma creation. Perianal fistulas are also managed medically, such as antibiotics, immunomodulators, and biologics including anti-tumor necrosis factor-alpha agents. The current standard treatment of choice for perianal fistula in CD patients is the multidisciplinary approach combining surgical and medical management; however, the rate of long-term remission is low and is reported to be 50% at most. Therefore, the optimum management strategy for perianal fistulas associated with CD remains controversial. Currently, the goal of management for CD-related perianal fistulas are controlling symptoms and maintaining long-term anal function without proctectomy, while monitoring progression to anorectal carcinoma. This review evaluates perianal fistula in CD patients and determines the optimal surgical management strategy based on recent evidence.

Vedolizumab in Crohn’s disease with rectal fistulas and presacral abscess: A case report

BACKGROUND

Fistula and intraabdominal abscess are common complications of Crohn’s disease (CD), but complex rectal fistula with abscess formation is rare. Tumor necrosis factor antagonists combined with percutaneous drainage or surgical intervention is optimal treatment for fistulizing CD with intraabdominal abscess. There is no study showing the efficacy of vedolizumab in such complicated condition.

CASE SUMMARY

A 47-year-old man has decompensated liver cirrhosis, Child B. He suffered from abdominal pain, bloody diarrhea, fever, and body weight loss. CD with rectoprostatic fistula, rectopresacral fistula, presacral abscess and cyto-megalovirus (CMV) infection were noted. He received antibiotics, anti-viral therapy, transverse colostomy and vedolizumab treatment. Six months later, he had deep remission and complete fistula tracts closure.

CONCLUSION

Early vedolizumab and stool diversion are effective and safe in treating CD with complex rectal fistula with abscess formation.

Perianal Crohn's Disease in Children and Adolescents

The incidence of Crohn's disease is increasing worldwide. The clinical course of childhood onset Crohn's disease is particularly aggressive with characteristic disease localization in the ileocecal region and colon, often associated with perianal disease. Severe complications of perianal disease include recurrent perianal sepsis, chronic fistulae, fecal incontinence, and rectal strictures that impair quality of life and may require fecal diversion. Care of patients with perianal Crohn's disease requires a multidisciplinary approach with systematic clinical evaluation, endoscopic assessment, and imaging studies followed by combined medical and surgical management. In this review, we provide an update of the epidemiology, pathophysiology, diagnostics, and management of perianal Crohn's disease in children and adolescents.

The Effect of Adalimumab Treatment on Linear Growth in Children With Crohn Disease: A Post-hoc Analysis of the PAILOT Randomized Control Trial

OBJECTIVES

Growth impairment is common in children with Crohn disease (CD). We aimed to assess the effect of adalimumab (ADL) treatment on linear growth in children with CD in a post-hoc analysis of the Pediatric Crohn's Disease AdalImumab Level-based Optimization Treatment randomized controlled trial.

METHODS

Children 6 to 17 years who responded to ADL induction were assessed consecutively for anthropometric parameters. Associations of these parameters with disease characteristics and disease activity were analyzed.

RESULTS

Overall, 66 patients completed 72 weeks of follow-up (25% girls, mean age of 15.6 ± 2.5 years). Median (interquartile range [IQR]) height z score improved from -0.6 (-1.6-0.15) at baseline to -0.33 (-1.3-0.5) at week 72 (P = 0.005) with lesser improvement in patients with perianal disease. Similar effect was noted in children with growth potential (boys younger than 16 years, girls younger than 14 years). Median (IQR) height velocity standard deviation was -0.32 (-1.5-0.8) at week 26, and +0.11 (-1.1-1.3) at week 72. Median weight z score increased from -0.54 (-1.2-0.15) to -0.1 (-0.9-0.6), P < 0.001 and body mass index from -0.4 (-1.0-0.5) to 0.0 (-0.8-0.9), P = 0.005. Pediatric CD activity index and erythrocyte sedimentation rate at week 4 correlated negatively with height z score changes (P = 0.043 and P = 0.048, respectively), whereas sustained clinical and biologic remission (week 4-72) were positively associated with changes in height z scores. Significant improvement in linear growth was predicted by lower pediatric CD activity index and erythrocyte sedimentation rate at the end of induction and sustained clinical remission (P = 0.05) and sustained normal C-reactive protein (P = 0.001) at all visits.

CONCLUSION

In children with moderate-to-severe CD, ADL treatment had a significant effect on linear growth, with normalization of weight and body mass index (clinicaltrials.gov no: NCT02256462).

Stromal Cells in the Pathogenesis of Inflammatory Bowel Disease

Up till now, research on inflammatory bowel disease [IBD] has mainly been focused on the immune cells present in the gastrointestinal tract. However, recent insights indicate that stromal cells also play an important and significant role in IBD pathogenesis. Stromal cells in the intestines regulate both intestinal epithelial and immune cell homeostasis. Different subsets of stromal cells have been found to play a role in other inflammatory diseases [e.g. rheumatoid arthritis], and these various stromal subsets now appear to carry out also specific functions in the inflamed gut in IBD. Novel potential therapies for IBD utilize, as well as target, these pathogenic stromal cells. Injection of mesenchymal stromal cells [MSCs] into fistula tracts of Crohn's disease patients is already approved and used in clinical settings. In this review we discuss the current knowledge of the role of stromal cells in IBD pathogenesis. We further outline recent attempts to modify the stromal compartment in IBD with agents that target or replace the pathogenic stroma.

Management of patients with complex perianal fistulas in Crohn's disease: Optimal patient flow in the Italian clinical reality

Perianal fistulizing Crohn's disease (PFCD) is a common, disabling and aggressive phenotype that negatively impacts on the quality of life of affected patients. Its successful treatment is still a struggle for both physicians and patients. Significant advances in the management of this condition have occurred in the last two decades holding promise for a better future. This culminated into the concept of a collaborative multidisciplinary approach using the latest medical therapies combined with modern surgical and endoscopic techniques. Despite this, PFCD management and treatment have not been standardized yet. Thus the gastroenterologist and surgeon have to be familiar with several approaches and/or techniques. The positioning of each therapeutic option will certainly evolve with new data, but for the time being it should be driven by patient's characteristics, physician's preference and/or experience, costs and availability in local practice. Additionally, patient's perception of benefits and risks of treatment may differ from those of physicians and recognition of this difference is a starting point for difficult clinical decision-making. In this paper, a multidisciplinary group of Italian IBD experts explore and discuss current medical and surgical therapeutic options, highlighting areas of unmet needs in PFCD, with particular focus on the optimal patient flow within the Italian clinical reality.

Succinate Activates EMT in Intestinal Epithelial Cells through SUCNR1: A Novel Protagonist in Fistula Development

The pathogenesis of Crohn’s disease-associated fibrostenosis and fistulas imply the epithelial-to-mesenchymal transition (EMT) process. As succinate and its receptor (SUCNR1) are involved in intestinal inflammation and fibrosis, we investigated their relevance in EMT and Crohn’s disease (CD) fistulas. Succinate levels and SUCNR1-expression were analyzed in intestinal resections from non-Inflammatory Bowel Disease (non-IBD) subjects and CD patients with stenosing-B2 or penetrating-B3 complications and in a murine heterotopic-transplant model of intestinal fibrosis. EMT, as increased expression of Snail1, Snail2 and vimentin and reduction in E-cadherin, was analyzed in tissues and succinate-treated HT29 cells. The role played by SUCNR1 was studied by silencing its gene. Succinate levels and SUCNR1 expression are increased in B3-CD patients and correlate with EMT markers. SUCNR1 is detected in transitional cells lining the fistula tract and in surrounding mesenchymal cells. Grafts from wild type (WT) mice present increased succinate levels, SUCNR1 up-regulation and EMT activation, effects not observed in SUCNR1^−/− tissues. SUCNR1 activation induces the expression of Wnt ligands, activates WNT signaling and induces a WNT-mediated EMT in HT29 cells. In conclusion, succinate and its receptor are up-regulated around CD-fistulas and activate Wnt signaling and EMT in intestinal epithelial cells. These results point to SUCNR1 as a novel pharmacological target for fistula prevention.

Analysis of Risk Factors for Anorectal Stenosis of Perianal Fistulizing Crohn's Disease

Background

To analyze the risk factors of anorectal stenosis associated with perianal fistulizing Crohn’s disease (PFCD).

Material/Methods

We retrospectively analyzed 139 cases of PFCD from January 2010 to December 2017 at the Affiliated Hospital of Nanjing University of Chinese Medicine. They were divided into 2 groups according to whether anorectal stenosis occurred. The possible factors associated with anorectal stenosis of PFCD were selected based on the literature review and clinical observations. Univariate analysis was performed to screen the risk factors of anorectal stenosis, and multivariate logistic regression analysis was performed on these risk factors and factors that were clinically considered to be potentially influential, to screen out the independent risk factors of anorectal stenosis.

Results

We found that 44 cases (31.7%) of PFCD were associated with anorectal stenosis. Univariate analysis showed that CDAI, lesion location, and age at diagnosis were risk factors for anorectal stenosis of PFCD. Logistic regression analysis showed that mild (fair to good) (OR=3.833, 95% CI: 1.123~13.080) to moderate (poor) (OR=7.345, 95% CI: 1.964~27.474) CDAI and age at diagnosis (OR=1.067, 95% CI: 1.013~1.124) were independent risk factors for anorectal stenosis of PFCD.

Conclusions

Higher CDAI and older age at diagnosis appear to confer higher risk of anorectal stenosis associated with PFCD.

Prevalence of Anal Fistulas in Europe: Systematic Literature Reviews and Population-Based Database Analysis

Introduction

Despite the fact that perianal fistulas are associated with significant morbidity and impaired quality of life, their prevalence in Europe is unknown. The aim of this study was to estimate the prevalence of perianal fistulas in Europe, overall and according to etiology.

Methods

Two independent literature reviews were performed using different search strategies to maximize the identification of potentially relevant studies. Data from relevant articles were used to estimate the prevalence of perianal fistulas in Europe. The robustness of the estimate was evaluated using data from a large population-based database from the UK.

Results

A total of 26 studies provided epidemiological data on perianal fistulas, of which 16 provided suitable data to estimate the prevalence. Estimations using these data yielded a total prevalence of 1.69 per 10,000 population. Cryptoglandular infection and Crohn’s disease (CD) were the predominant etiologies, with prevalence rates at 0.86 and 0.76 per 10,000 population, respectively. Comparison of prevalence data from the UK population-based database with the European population resulted in a standardized prevalence estimate of all perianal fistulas of 1.83 per 10,000 population, confirming the robustness of the literature-based estimate.

Conclusion

Although in terms of incidence cryptoglandular fistulas were clearly predominant, the prevalence of fistulas in CD and cryptoglandular infection appeared more balanced. This is due to the longer duration and higher frequency of relapses of fistulas in CD. The estimated prevalence implies that perianal fistulas meet the criteria to be considered as a rare condition in Europe (prevalence less than 5 per 10,000 population).

Funding

This study was funded by Takeda Pharmaceutical U.S.A., Inc. and TiGenix SAU.

Electronic Supplementary Material

The online version of this article (10.1007/s12325-019-01117-y) contains supplementary material, which is available to authorized users.

Prevalence of Fistulizing Crohn's Disease in the United States: Estimate From a Systematic Literature Review Attempt and Population-Based Database Analysis

BACKGROUND

Fistulas may arise as a relevant complication of Crohn's disease (CD). Despite their clinical significance and the substantial burden imposed on patients, limited data are available on the epidemiology of fistulizing CD in the United States.

METHODS

A systematic literature review was conducted to identify data published between 1970 and 2017 on the epidemiology of fistulas in patients with CD, with the aim to estimate the number of prevalent cases in the United States. Retrieved titles and abstracts were screened by 2 independent researchers for inclusion criteria (US population-based studies reporting data on the epidemiology of fistulizing CD). To validate the literature-based estimate, data from a US claims database (Truven Health MarketScan database) were analyzed. This database has broad geographic coverage, with health care data for >60 million patients during the period of the analysis.

RESULTS

The literature search retrieved 7 articles for full-text review, and only 1 met the criteria for inclusion. This study described the cumulative incidence of fistulas in a CD population from Minnesota over 20 years. From the reported data, the estimated number of prevalent cases with fistulizing CD in the United States was ~76,600 in 2017 (~52,900 anal, ~7400 rectovaginal, ~2300 enterocutaneous, and ~14,100 internal). Analysis from the US health care database resulted in an estimated number of ~75,700 patients, confirming the robustness of the original estimate from the literature.

CONCLUSIONS

Based on 2 separate analyses, the estimated number of patients with fistulizing CD in the United States is ~77,000 patients.

Anorectal Crohn's Disease

Medical treatment remains the mainstay of perianal disease management for CD; however, aggressive surgical management should be considered for severe or recurrent disease. In all cases of perianal CD, medical and surgical treatments should be used in tandem by a multidisciplinary team. Significant development has been made in the treatment of Crohn's-related fistulas, particularly minimally invasive options with recent clinical trials showing success with mesenchymal stem cell applications. Inevitably, some patients with severe refractory disease may require fecal diversion or proctectomy. When considering reversal of a diverting or end ileostomy, cessation of proctitis is the most important factor.

Faecal Microbiota Dynamics and their Relation to Disease Course in Crohn's Disease

BACKGROUND

Microbial shifts have been associated with disease activity in Crohn's disease [CD], but findings on specific taxa are inconsistent. This may be due to differences in applied methods and cross-sectional study designs. We prospectively examined the faecal microbiota in adult CD patients with changing or stable disease course over time.

METHODS

Faeces were collected at two time-points from 15 healthy control individuals [HCs], 35 CD patients who were in remission and who maintained remission [RRs], and 22 CD patients during remission and also during subsequent exacerbation [RAs]. The microbial composition was assessed by 16S rRNA [V4] gene sequencing.

RESULTS

Compared with HCs, patients with CD had a lower microbial richness [p = 0.0002] and diversity [p = 0.005]. Moreover, the microbial community structure of a subset of patients, clustered apart from HCs, was characterized by low microbial diversity and Faecalibacterium abundance. Patients within this cluster did not differ with respect to long-term disease course compared with patients with a 'healthy-appearing' microbiota.Over time, microbial richness and diversity did not change in RR versus RA patients. Although the microbial community structure of both RR and RA patients was less stable over time compared with that of HCs, no differences were observed between the patient groups [p = 0.17]; nor was the stability impacted by Montreal classification, medication use, or surgery.

CONCLUSION

The altered microbiota composition and stability in CD was neither associated with disease activity nor long-term disease course, questioning its involvement in the development of an exacerbation. The aberrant microbiota composition in a subset of CD patients warrants further exploration of a more microbiota-driven etiology in this group.

Cx601 (darvadstrocel) for the treatment of perianal fistulizing Crohn's disease

Introduction: Given the well-documented difficulty to treat perianal fistulizing Crohn's disease (pCD), with 40% of patients experiencing recurrence even after reiterative surgery and advanced medical therapy, research in this field has focused on the role of mesenchymal stem cells (MSC). Areas covered: The aim of this article is to furnish an overview of the pathogenetic mechanisms, clinical applications and evidences for the use of MSC for pCD with particular focus on adipose-derived allogenic MSC including darvadstrocel. Expert Opinion: The effect of MSC on fistula healing is probably mediated by their anti-inflammatory properties more than by their ability to engraft and trans-differentiate in the healthy tissue. A holistic treatment of pCD, addressing different pathophysiological factors, may represent the key for an improvement in the healing rate. In this setting, MSC might play a role as 'augmentation' therapy in combination with more conventional treatments. Whether MSC have benefit in non-complex fistula in biological naïve patients, in complex fistula with many tracts and/or in rectovaginal fistulas, are unexplored fields that need further investigation. A central registry of pCD patients undergoing treatment with MSC should be created in order to elucidate the efficacy, safety and costs of stem cells treatment on long term follow up.

Transplantation of Human Intestine Into the Mouse: A Novel Platform for Study of Inflammatory Enterocutaneous Fistulas

BACKGROUND AND AIMS

Enteric fistulas represent a severe and medically challenging comorbidity commonly affecting Crohn's disease [CD] patients. Gut fistulas do not develop in animal models of the disease. We have used transplantation of the human fetal gut into mice as a novel platform for studying inflammatory enterocutaneous fistulas.

METHODS

Human fetal gut segments were transplanted subcutaneously into mature SCID mice, where they grew and fully developed over the course of several months. We first analysed the resident immune cells and inflammatory response elicited by systemic lipopolysaccharide [LPS] in normal, fully developed human gut xenografts. Thereafter, we used immunostaining to analyse fully developed xenografts that spontaneously developed enterocutaneous fistulas.

RESULTS

Resident human innate and adaptive immune cells were demonstrated in gut xenografts during steady state and inflammation. The expression of human IL-8, IL-1β, IL-6, TNF-α, A20, and IkBα was significantly elevated in response to LPS, with no change in IL-10 gene expression. Approximately 17% [19/110] of fully developed subcutaneous human gut xenografts spontaneously developed enterocutaneous fistulas, revealing striking histopathological similarities with CD fistula specimens. Immunohistochemical analyses of fistulating xenografts revealed transmural lymphocytic enteritis associated with massive expansion of resident human CD4+ lymphocytes and their migration into the intraepithelial compartment. Regionally, mucosal epithelial cells assumed spindle-shaped mesenchymal morphology and formed fistulous tracts towards chronic non-healing wounds in the host mouse skin overlying the transplants.

CONCLUSIONS

Inflammation and fistulas developed in human gut xenografts lacking IL-10 gene response. This novel model system will enable systematic studies of the inflamed and fistulating human gut in live animals.

Challenges in IBD Research: Preclinical Human IBD Mechanisms

Preclinical human IBD mechanisms is part of five focus areas of the Challenges in IBD research document, which also include environmental triggers, novel technologies, precision medicine and pragmatic clinical research. The Challenges in IBD research document provides a comprehensive overview of current gaps in inflammatory bowel diseases (IBD) research and delivers actionable approaches to address them. It is the result of a multidisciplinary input from scientists, clinicians, patients, and funders, and represents a valuable resource for patient centric research prioritization. In particular, the preclinical human IBD mechanisms manuscript is focused on highlighting the main research gaps in the pathophysiological understanding of human IBD. These research gap areas include: 1) triggers of immune responses; 2) intestinal epithelial homeostasis and wound repair; 3) age-specific pathophysiology; 4) disease complications; 5) heterogeneous response to treatments; and 6) determination of disease location. As an approach to address these research gaps, the prioritization of reverse translation studies is proposed in which clinical observations are the foundation for experimental IBD research in the lab, and for the identification of new therapeutic targets and biomarkers. The use of human samples in validating basic research findings and development of precision medicine solutions is also proposed. This prioritization aims to put emphasis on relevant biochemical pathways and humanized in vitro and in vivo models that extrapolate meaningfully to human IBD, to eventually yield first-in-class and effective therapies.

Gracilis muscle transposition for treatment of recurrent anovaginal, rectovaginal, rectourethral, and pouch-vaginal fistulas in patients with inflammatory bowel disease

Background

The aim of this study was to evaluate the effectiveness of gracilis muscle transposition (GMT) to treat recurrent anovaginal, rectovaginal, rectourethral, and pouch–vaginal fistulas in patients with inflammatory bowel disease (IBD).

Methods

A retrospective study was conducted in patients with IBD who had GMT performed by a single surgeon between 2000 and 2018. Follow-up data regarding healing rate, complications, additional procedures, and stoma closure rate was collected.

Results

A total of 30 women and 2 men had GMT. In all patients fistula was associated with Crohn's disease. In 1 female patient, contralateral gracilis transposition was required after a failed attempt at repair. The primary healing rate was 47% (15/32) and the definitive healing rate (healed by the time of data collection and after secondary procedures) was 71% (23/32). Additional surgical procedures due to fistula persistence or recurrence were performed on 17 patients (53%).At least 7 patients (21%) suffered complications including one wound infection with ischemia of the gracilis muscle. Stoma closure was successful in 18 of 31 cases of patients with stoma (58% of the patients).

Conclusions

GMT for the treatment of recurrent and complex anorectal fistulas in patients with IBD patient is eventually successful in almost 2/3 of patients.

Trends and Attributable Costs of Anorectal Involvement in Pediatric Crohn's Disease

BACKGROUND

Pediatric Crohn's disease (CD) with anorectal involvement has not been well characterized. We sought to describe trends in the prevalence of pediatric CD with anorectal involvement and its influence on health-care utilization.

MATERIALS AND METHODS

Patients (<21 y of age) with an International Classification of Diseases, Ninth Revision diagnosis of CD (555.X) were identified in the Kid's Inpatient Database (2003, 2006, 2009, 2012) and stratified by anorectal involvement based on the International Classification of Diseases, Ninth Revision diagnosis and procedural codes. Patient characteristics and resource utilization (length of stay [LOS] and costs) were compared between CD patients with and without anorectal involvement using univariate and multivariable analyses. Propensity score matching was used to estimate attributable LOS and costs.

RESULTS

There were 26,029 patients with CD identified in the study interval. Of these, 1706 (6.6%) had anorectal involvement. Those with anorectal disease were younger (age 16 versus 17 y old), more likely to be male (59.4% versus 49.9%) and black or Hispanic (24.7% versus 18.2%), and were more commonly treated in urban teaching hospitals compared with rural or nonteaching hospitals (83.2% versus 70.9%) (P < 0.001 for all). The proportion of patients with anorectal involvement increased over time (odds ratio 1.03, 95% confidence interval 1.02-1.05). After propensity score matching, attributable LOS and costs were 0.5 d and approximately $1600, respectively.

CONCLUSIONS

There has been an increase in the proportion of pediatric CD hospitalizations with anorectal manifestations. This pattern of disease is associated with longer hospitalization and higher costs compared with CD alone. Further research is required to understand the underlying etiology of these observed trends.

A series of seton techniques involving "top-down therapy" for patients with Crohn's disease who initially presented with perianal fistulas

OBJECTIVES

We determined the outcomes of seton treatment through a series of techniques using biological agents (BIOs) in 18 patients with Crohn's disease (CD) who initially presented with perianal fistulas.

METHODS

The patients underwent seton drainage using three seton types: a Penrose tube for fistulas with massive purulent discharge, a vessel loop for a small amount of discharge, and a rubber band for unproductive fistulas. If the distal end of the fistula extended more than 4 cm from the anal orifice, the skin and subcutaneous tissue were dissected along the outer edge of the anal sphincter to divide the fistulous tract into two portions. One seton encircled the sphincter from the primary opening throughout the anal canal (medial seton), and the other was inserted through the distal tract outside the sphincter (lateral seton). A BIO was then introduced immediately. When discharge ceased, the Penrose tube or vessel loop was replaced sequentially with a rubber band, which was tied fittingly and subsequently removed in medial to lateral order.

RESULTS

The mean interval between fistula onset and CD diagnosis was 2.1 years, and that between CD diagnosis and introduction of BIOs was 0.5 years. The mean follow-up duration was 4 years. The BIOs currently used were infliximab in 10 patients, adalimumab in 7, and ustekinumab in 1. The overall success rate was 94.4%, including unproductive fistulas in 10 (55.6%) patients and fistula disappearance in 7 (38.9%).

CONCLUSIONS

Our seton drainage techniques via the "top-down" approach represent a promising avenue for treating perianal fistulas in patients with CD.

Differential diagnosis of inflammatory bowel disease: imitations and complications

Inflammatory bowel disease (IBD) is characterised by episodes of relapse and periods of remission. However, the clinical features, such as abdominal pain, diarrhoea, and rectal bleeding, are not specific. Therefore, the differential diagnosis can include a broad spectrum of inflammatory or infectious diseases that mimic IBD, as well as others that might complicate existing IBD. In this Review, we provide an overview of ileocolitis of diverse causes that are relevant in the differential diagnosis of IBD. We highlight the importance of accurate patient profiling and give a practical approach to identifying factors that should trigger the search for a specific cause of intestinal inflammation. Mimics of IBD include not only infectious causes of colitis-and particular attention is required for patients from endemic areas of tuberculosis-but also vascular diseases, diversion colitis, diverticula or radiation-related injuries, drug-induced inflammation, and monogenic diseases in very-early-onset refractory disease. A superinfection with cytomegalovirus or Clostridium difficile can aggravate intestinal inflammation in IBD, especially in patients who are immunocompromised. Special consideration should be made to the differential diagnosis of perianal disease.

Perianal fistulizing Crohn's disease: pathogenesis, diagnosis and therapy

Perianal fistulizing Crohn's disease has a major negative effect on patient quality of life and is a predictor of poor long-term outcomes. Factors involved in the pathogenesis of perianal fistulizing Crohn's disease include an increased production of transforming growth factor β, TNF and IL-13 in the inflammatory infiltrate that induce epithelial-to-mesenchymal transition and upregulation of matrix metalloproteinases, leading to tissue remodelling and fistula formation. Care of patients with perianal Crohn's disease requires a multidisciplinary approach. A complete assessment of fistula characteristics is the basis for optimal management and must include the clinical evaluation of fistula openings, endoscopic assessment of the presence of proctitis, and MRI to determine the anatomy of fistula tracts and presence of abscesses. Local injection of mesenchymal stem cells can induce remission in patients not responding to medical therapies, or to avoid the exposure to systemic immunosuppression in patients naive to biologics in the absence of active luminal disease. Surgery is still required in a high proportion of patients and should not be delayed when criteria for drug failure is met. In this Review, we provide an up-to-date overview on the pathogenesis and diagnosis of fistulizing Crohn's disease, as well as therapeutic strategies.

Misbalance in type III collagen formation/degradation as a novel serological biomarker for penetrating (Montreal B3) Crohn's disease

BACKGROUND

Misbalances in extracellular matrix turnover are key factors in the development of stricturing (Montreal B2) and penetrating (Montreal B3) Crohn's disease.

AIM

To determine whether serological markers for collagen formation and degradation could serve as biomarkers for complications of Crohn's disease.

METHODS

Serum biomarkers for type I, III, V and VI collagen formation (P1NP, Pro-C3, Pro-C5, Pro-C6) and matrix metalloproteinase mediated degradation (C1M, C3M, C5M and C6M) were measured in a retrospective, single centre cohort of 112 patients with Crohn's disease in the terminal ileum (nonstricturing/nonpenetrating: n=40, stricturing: n=55, penetrating: n=17) and 24 healthy controls. Active inflammation was defined as CRP >5 mg/L.

RESULTS

C3M and Pro-C5 levels were higher in penetrating vs nonpenetrating/nonstricturing and stricturing disease (33.6±5 vs 25.8±2.2 [P=.004] and 27.2±2.3 [P=.018] nmol/L C3M, 1262.7±259.4 vs 902.9±109.9 [P=.005] and 953.0±106.4 [P=.015] nmol/L Pro-C5). C1M (71.2±26.1 vs 46.2±6.2 nmol/L [P<.001]), C3M (31.6±3.9 vs 26.1±1.6 nmol/L [P=.002] and Pro-C5 levels (1171.7±171.5 vs 909.6±80.4 nmol/L [P=.002]) were higher in patients with active inflammation vs without active inflammation. Pro-C3/C3M-ratios were best to differentiate between penetrating vs nonstricturing/nonpenetrating and stricturing disease with area under the curves of 0.815±0.109 (P<.001) and 0.746±0.114 (P=.002) respectively.

CONCLUSIONS

Serological biomarkers show that penetrating Crohn's disease is characterised by increased matrix metalloproteinase-9 degraded type III collagen and formation of type V collagen. Active inflammation in Crohn's disease is characterised by increased formation of type V collagen and increased matrix metalloproteinase mediated breakdown of type I, III collagen. Pro-C3/C3M ratios are superior in differentiating between penetrating Crohn's disease vs inflammatory and stricturing Crohn's disease.

Factors associated with surgery in patients with intra-abdominal fistulizing Crohn's disease

AIM

To characterize radiological and clinical factors associated with subsequent surgical intervention in Crohn’s disease (CD) patients with intra-abdominal fistulae.

METHODS

From a cohort of 1244 CD patients seen over an eight year period (2006 to 2014), 126 patients were identified as having intra-abdominal fistulae, and included in the study. Baseline patient information was collected from the medical records. Imaging studies were assessed for: anatomic type and number of fistulae; diameter of the inflammatory conglomerate; length of diseased bowel; presence of a stricture with pre-stenotic dilatation; presence of an abscess; lymphadenopathy; and the degree of bowel enhancement. Multivariate analysis for the prediction of abdominal surgery was calculated via Generalized Linear Models.

RESULTS

In total, there were 193 fistulae in 132 patients, the majority (52%) being entero-enteric. Fifty-nine (47%) patients underwent surgery within one year of the imaging study, of which 36 (29%) underwent surgery within one month. Radiologic features that were associated with subsequent surgery included: multiple fistulae (P = 0.009), presence of stricture (P = 0.02), and an entero-vesical fistula (P = 0.01). Evidence of an abscess, lymphadenopathy, or intense bowel enhancement as well as C-reactive protein levels was not associated with an increased rate of surgery. Patients who were treated after the imaging study with combination immunomodulatory and anti-TNF therapy had significantly lower rates of surgery (P = 0.01). In the multivariate analysis, presence of a stricture [RR 4.5 (1.23-16.3), P = 0.02] was the only factor that increased surgery rate.

CONCLUSION

A bowel stricture is the only factor predicting an increased rate of surgery. Radiological parameters may guide in selecting treatment options in patients with fistulizing CD.

The Gastroenterologist's Role in Management of Perianal Fistula

Perianal fistula occurs frequently in the Crohn disease population. Therapy for fistulas has changed through the years from primarily surgical management to multidisciplinary management among gastroenterologists, radiologists, and surgeons. Gastroenterologists play a role in assisting with diagnosis through endoscopic ultrasound and assessment of luminal disease activity, providing medical therapy including biologic therapy and antibiotics, and coordinating the multidisciplinary care with surgical and radiologic colleagues.

The two sides of the coin: Similarities and differences in the pathomechanisms of fistulas and stricture formations in irritable bowel disease

Fistulas and fibrosis or strictures represent frequent complications in irritable bowel disease (IBD) patients. To date, treatment options for fistulas are limited and surgery is often required. Similarly, no preventive treatment for fibrosis and stricture formation has been established. Frequently, stricture formation and fibrosis precede fistula formation, indicating that both processes may be connected or interrelated. Knowledge about the pathology of both processes is limited. A crucial role for the epithelial-to-mesenchymal transition (EMT) in fistula development has been demonstrated. Of note, EMT also plays a major role in the pathogenesis of fibrosis in many organs, and most likely also plays that role in the intestine. In addition, aberrant matrix remodeling, as well as soluble factors such as tumor necrosis factor (TNF), interleukin 13 (IL-13) and tumor growth factor beta (TGFβ) were involved, both in the onset of the fistula and fibrosis formation. Both fistulas and fibrosis may occur due to deregulated wound healing mechanisms from chronic and severe intestinal inflammation; however, further research is required to obtain a better understanding of the complex pathophysiology of fistula and intestinal fibrosis formation, to allow the development of new and more effective preventive treatment options for those important disease complications.