Review article: pathogenesis of Crohn's perianal fistula-understanding factors impacting on success and failure of treatment strategies

Does Combined Medical and Surgical Treatment Improve Perianal Fistula Outcomes in Patients With Crohn's Disease? A Systematic Review and Meta-Analysis

BACKGROUND

The optimal treatment of perianal fistulizing Crohn's disease [PFCD] is unknown. We performed a systematic review with meta-analysis to compare combined surgical intervention and anti-tumour necrosis factor [anti-TNF] therapy [combined therapy] vs either therapy alone.

METHODS

MEDLINE, EMBASE, and Cochrane databases were searched systematically up to end December 2023. Surgical intervention was defined as an exam under anaesthesia ± setons. We calculated weighted risk ratios [RRs] with 95% confidence intervals [CIs] for our co-primary outcomes: fistula response and healing, defined clinically as a reduction in fistula drainage or number of draining fistulas and fistula closure respectively.

RESULTS

Thirteen studies were analysed: 515 patients treated with combined therapy, 330 patients with surgical intervention, and 406 patients with anti-TNF therapy with follow-up between 10 weeks and 3 years. Fistula response [RR 1.10; 95% CI 0.93-1.30, p = 0.28] and healing [RR 1.06; 95% CI 0.86-1.31, p = 0.58] was not significantly different when comparing combined therapy with anti-TNF therapy alone. In contrast, combined therapy was associated with significantly higher rates of fistula response [RR 1.25; 95% CI 1.10-1.41, p < 0.001] and healing [RR 1.17; 95% CI 1.00-1.36, p = 0.05] compared with surgical intervention alone. Our results remained stable when limiting to studies that assessed outcomes within 1 year and studies where <10% of patients underwent fistula closure procedures.

CONCLUSION

Combined surgery and anti-TNF therapy was not associated with improved PFCD outcomes compared with anti-TNF therapy alone. Due to an inability to control for confounding and small study sizes, future, controlled trials are warranted to confirm these findings.

Allogenic Stem Cells in Anal Fistulas of Crohn's Disease: From Promising Premises to Real Life Experience

BACKGROUND

Allogenic adipocyte stem cells represent an unprecedented opportunity for regenerative therapy to treat Crohn anal fistulas. Apart from the results of one 8-year-old trial, scientific evidence remains scarce.

METHODS

Data from consecutive patients treated with darvadstrocel for Crohn anal fistulas were reviewed at 6 first tertiary reference centers. The judgment criteria combined asymptomatic status plus clinical occlusion of the fistula tract and MRI-confirmed healing of the tract (no inflammation and/or disappearance of the tract). Both clinical and MRI-confirmed healing of the tract defined a deep remission. Clinical remission was defined by an absence of complaint, occlusion of all external openings, and no fistula discharge.

RESULTS

A total of 116 patients were extracted (median follow-up after cell stem injection: 11 [6-14] months). No severe adverse events were reported after surgery except for subsequent anal surgery in 29 (25%) patients. Fifty-one (44%) patients had clinical remission defined by the absence of complaints, the occlusion of all external openings, and the presence of no fistula discharge. Deep remission was observed in 23 (29%) patients. Patients with clinical remission more often received combined therapy (immunosuppressant antitumor necrosis factors) than those with no improvement (31 of 51 [61%] vs 23 of 65 [35%]; P = .007). Regression analysis showed that high fistulas (odds ratio, 3.8 [1.1-12.5]; P = .03) and younger age (<38 years, odds ratio, 2.3 [1.0-58;4]; P = .02) were associated with a better outcome.

CONCLUSIONS

Allogeneic stem cell treatment of Crohn's anal fistulas results in complete remission in less than half of patients, with a significant reintervention rate.

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.

Clinical and magnetic resonance imaging spectrum of complex perianal fistulizing Crohn's disease: A cohort study from northern India

BACKGROUND

Fistulizing perianal Crohn's disease (CD) is a debilitating condition associated with significant morbidity and reduction in the quality of life. Magnetic resonance imaging (MRI) of the pelvis is the preferred imaging modality for the comprehensive assessment of the perianal fistula. There is a paucity of data from India on the MRI spectrum of complex perianal fistula in CD.

METHODS

A single-centre cross-sectional analysis of patients with fistulizing perianal CD, who underwent pelvic MRI between January 2020 and December 2021, was performed. The clinical (age, sex, disease duration, disease location and behavior, disease activity [Perianal Disease Activity Index, PDAI] and treatment received) and radiological (number and location of fistulae, extensions, number and location of internal and external openings, fistula activity, presence or absence of perianal abscess and associated proctitis) characteristics of complex perianal fistula (defined according to the American Gastroenterological Association classification) were recorded.

RESULTS

Of total 175 patients with CD who attended the gastroenterology clinic during the study period, 27 (15.42%) (mean age 42±15.5 years, 62.96% females and median disease duration four years) had complex perianal fistula and were included in the analysis. The mean PDAI was 5.48±2.53. The median Van Assche Index was 17 (interquartile range [IQR] 13-19). A majority (96.29%) of the fistulae were trans-sphincteric and four (14.81%) fistulae extended into the supralevator space. All fistulae were active on MRI. Concomitant perianal abscess and proctitis were seen in 59.26% (n=16) and 62.96% (n=17) of patients, respectively. Combination therapy with biologics and antibiotics/immune-suppressants were the most commonly prescribed medical therapy. Six (22.22%) patients underwent combined medical and surgical (non-cutting seton, fistulectomy, fecal diversion) treatment.

CONCLUSION

The cumulative risk of the development of fistulizing perianal CD in a northern Indian cohort was similar to the western populations. Complex perianal fistulae were predominantly trans-sphincteric and commoner in females. MRI evaluation is pivotal for the delineation of fistula anatomy, assessment of disease extent and activity and the evaluation of concomitant perianal abscess and other complications.

Autologous Fat Grafting: an Emerging Treatment Option for Complex Anal Fistulas

BACKGROUND

Autologous fat grafting (AFG) has shown promise in the treatment of complex wounds, with trials reporting good healing rates and safety profile. We aim to investigate the role of AFG in managing complex anorectal fistulas.

METHODS

This was a retrospective review of a prospectively maintained IRB-approved database. We examined the rates of symptom improvement, clinical closure of fistula tracts, recurrence, complications, and worsening fecal incontinence. Perianal disease activity index (PDAI) was obtained for patients undergoing combination of AFG and fistula plug treatment.

RESULTS

In total, 52 unique patients underwent 81 procedures, of which Crohn's was present in 34 (65.4%) patients. The majority of patients previously underwent more common treatments such as endorectal advancement flap or ligation of intersphincteric fistula tract. Fat-harvesting sites and processing technique were selected by the plastic surgeons based on availability of trunk fat deposits. When analyzing patients by their last procedure, 41 (80.4%) experienced symptom improvement, and 29 (64.4%) experienced clinical closure of all fistula tracts. Recurrence rate was 40.4%, and complication rate was 15.4% (7 postoperative abscesses requiring I&D and 1 bleeding episode ligated at bedside). The abdomen was the most common site of lipoaspirate harvest at 63%, but extremities were occasionally used. There were no statistically significant differences in outcomes when comparing single graft treatment to multiple treatments, Crohn's and non-Crohn's, different methods of fat preparation, and diversion.

CONCLUSION

AFG is a versatile procedure that can be done in conjunction with other therapies and does not interfere with future treatments if recurrence occurs. It is a promising and affordable method to safely address complex fistulas.

Stromal vascular fraction with platelet-rich plasma injection during surgery is feasible and safe in treatment-refractory perianal fistulising Crohn's disease: A pilot study

BACKGROUND

An unmet need remains for improved management in perianal fistulising Crohn's disease (pCD). Recently, local administration of adipose-derived cells has shown promising results.

AIMS

To assess the safety and feasibility of injection of stromal vascular fraction (SVF) with platelet-rich plasma (PRP) in patients with pCD.

METHODS

Patients ≥ 18 years with pCD were included and underwent fistula curettage, SVF with PRP injection, and closure of the internal opening. The primary endpoint was safety at 12 months. The secondary outcomes were complete radiological healing at 3 months (absence of fluid-containing tracts on MRI) and partial and complete clinical response at 3 and 12 months (closure of ≥1, respectively, all treated external opening(s)).

RESULTS

Twenty-five patients were included (35 [IQR 25-40] years; 14 [56%] female); median CD duration 4 [IQR 2-8] years. Twenty-four (95%) patients had previously undergone fistula surgery. No adverse events were encountered at lipoharvesting sites. Two (8%) patients were readmitted to hospital and six (24%) underwent unplanned re-interventions. Post-operative MRI (n = 24) showed complete radiological healing in nine (37.5%) patients. Partial clinical response was present in 48% (12/25) at 3 months and in 68% (17/25) at 12 months, and complete clinical closure in five (20%) patients at 3 months and in 10 (40%) patients at 12 months.

CONCLUSION

Injection with autologous SVF with PRP is feasible and safe in patients with treatment-refractory pCD. Early complete radiological healing was observed in more than one-third of patients, and clinical response in two-thirds of patients at 12 months.

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.

Clinical and endoscopic outcomes of patients with colonic Crohn's disease treated with 5-aminosalicylates as monotherapy

BACKGROUND

In spite of the lack of evidence regarding the clinical benefits of oral 5-aminosalicylic acid (5-ASA) compounds in Crohn's disease (CD), these drugs are frequently used in daily clinical practice, particularly for colonic CD. Our aim is to assess the use and clinical outcomes of 5-ASA of those patients with colonic CD treated with 5-ASA as monotherapy.

METHODS

Patients diagnosed with isolated colonic CD and treated with 5-ASA but never exposed to immunosuppressants or biologicals were identified from the local databases of five referral centres. A retrospective review of clinical and endoscopic outcomes was performed.

RESULTS

Out of 545 patients with isolated colonic CD, 106 (19%) were treated with oral 5-ASA in monotherapy as maintenance therapy. The median follow-up was 144 months (interquartile range [IQR], 48-234). Almost all of the patients (92%) presented an inflammatory pattern and 11% developed perianal disease. Half of the patients had already received 5-ASA at diagnosis, and the median duration of 5-ASA treatment was 107 months (IQR 22.5-187). Endoscopic remission, as defined by the absence of ulcers at the last complete colonoscopy, was observed in 65% of those patients undergoing at least one colonoscopy during follow-up. Male gender and extraintestinal manifestations were associated with a lower likelihood of achieving endoscopic remission. Nine patients required colectomy, but mostly soon after CD diagnosis.

CONCLUSIONS

5-ASA seems to be of benefit in the long-term in one fifth of patients with colonic CD as the only maintenance therapy and should be considered in fragile patients with Crohn's colitis.

A Novel Patient-like Swine Model of Perianal Crohn's Disease

BACKGROUND

Perianal Crohn's disease is associated with poor outcomes and high medical costs. It is notoriously difficult to treat despite therapeutic advancements for luminal disease. A large animal model that mimics human perianal disease is needed to test innovative therapies.

OBJECTIVE

This study aimed to create a swine model that replicates the inflammatory component and therapeutic challenges found in patients with perianal Crohn's disease.

DESIGN

This was an animal preclinical study.

SETTINGS

The experiments were performed at the animal laboratory at the Johns Hopkins University.

PATIENTS

Four sus scrufus female pigs were included in the study.

INTERVENTIONS

Four female pigs underwent creation of 3 surgical perianal fistulas each, 1 rectovaginal and 2 perianal. Size 24 French setons were placed to maintain patency of the fistula tracts for 4 weeks. After removal of the setons, trinitrobenzene sulfonic acid was administered into the fistula tract to create and maintain local inflammation mimicking perianal Crohn's disease.

MAIN OUTCOMES MEASURES

An MRI was obtained to assess the fistulas and the pigs were euthanized to review histopathology.

RESULTS

Three inflammatory chronic fistula tracts were successfully created in each pig as confirmed by MRI and examination under anesthesia. This is the first report of maintaining patent fistulas in swine 2 weeks after removal of setons. For the first time, we reported that 2 pigs developed branching fistulas and small abscesses reminiscent of human perianal Crohn's disease. The corresponding histopathologic examination found significant chronic active inflammation on standard hematoxylin and eosin staining.

LIMITATIONS

The fistulas were surgically induced and did not occur naturally.

CONCLUSIONS

A chronic perianal fistula model in pigs that strongly resembles human perianal Crohn's disease was successfully created. This model can be used to test novel therapeutics and techniques to pave the path for human trials. See Video Abstract at http://links.lww.com/DCR/B969 .

UN NUEVO MODELO PORCINO SIMILAR A UN PACIENTE DE LA ENFERMEDAD DE CROHN PERIANAL ANTECEDENTES

La enfermedad de Crohn perianal se asocia con malos resultados y altos costos médicos. Es notoriamente difícil de tratar a pesar de los avances terapéuticos para la enfermedad luminal. Se precisa de un modelo animal grande que imite la enfermedad perianal humana para probar terapias innovadoras.OBJETIVO:Nuestro objetivo de este estudio fue crear un modelo porcino que replique el componente inflamatorio y los desafíos terapéuticos que se encuentran en los pacientes con enfermedad de Crohn perianal.DISEÑO:Este fue un estudio preclínico en animales.AJUSTES:Los experimentos se realizaron en el laboratorio de animales de la Universidad Johns Hopkins.PACIENTES:Se incluyeron en el estudio cuatro cerdas sus scrofa.INTERVENCIONES:Cuatro cerdas fueron sometidas a la creación de 3 fístulas perianales quirúrgicas cada una: 1 recto vaginal y 2 perianales. Se colocaron sedales de 24 French para mantener la permeabilidad de los trayectos fistulosos durante 4 semanas. Tras el retiro de los sedales, se administró ácido trinitrobenceno sulfónico en el trayecto de la fístula para crear y mantener la inflamación local simulando la enfermedad de Crohn perianal.PRINCIPALES MEDIDAS DE RESULTADOS:Se obtuvo una resonancia magnética para evaluar las fístulas y los cerdos fueron sacrificados para revisar la histopatología.RESULTADOS:Se crearon de manera exitosa tres trayectos fistulosos inflamatorios crónicos en cada cerdo, confirmados por imágenes de resonancia magnética y examen bajo anestesia. Este es el primer informe de preservación de fístulas permeables en cerdos 2 semanas tras el retiro de los setones. Por primera vez, informamos que dos cerdos desarrollaron fístulas ramificadas y pequeños abscesos que recuerdan a la enfermedad de Crohn perianal humana. El examen histopatológico correspondiente encontró una significativa inflamación crónica activa en la tinción estándar de hematoxilina y eosina.LIMITACIONES:Las fístulas se indujeron quirúrgicamente y no se produjeron de forma natural.CONCLUSIONES:Se logro recrear con éxito un modelo de fístula perianal crónica en cerdos que se asemeja mucho a la enfermedad de Crohn perianal humana. Este modelo se puede utilizar para probar nuevas terapias y técnicas para allanar el camino para los ensayos en humanos. Consulte Video Resumen en http://links.lww.com/DCR/B969 . (Traducción-Dr Osvaldo Gauto).

Surgical management of complex perianal fistula revisited in a systematic review: a critical view of available scientific evidence

BACKGROUND

Treating complex perianal fistulas in Crohn's disease patients remains a challenge. Classical surgical treatments for Crohn's disease fistulas have been extrapolated from cryptoglandular fistulas treatment, which have different etiology, and this might interfere with its effectiveness, in addition, they increase fecal incontinence risk. Recently, new surgical techniques with support from biological approaches, like stem cells, have been developed to preserve the function of the sphincter. We have performed a systematic literature review to compare the results of these different techniques in the treatment of Crohn's or Cryptoglandular fistula.

METHODS

PubMed, EMBASE, Database of Abstracts of Reviews of Effectiveness, Cochrane Central Register of Controlled Trials were searched systematically for relevant articles. We included randomized controlled trials and observational studies that referred to humans, were written in English, included adults 18+ years old, and were published during the 10-year period from 2/01/2010 to 2/29/2020. Evidence level was assigned as designated by the Scottish Intercollegiate Guidelines Network.

RESULTS

Of the 577 citations screened, a total of 79 were ultimately included in our review. In Crohn's disease patients, classical techniques such as primarily seton, Ligation of Intersphincteric Fistula Tracks, or lay open, healing rates were approximately 50-60%, while in cryptoglandular fistula were around, 70-80% for setons or flaps. In Crohn's disease patients, new surgical techniques using derivatives of adipose tissue reported healing rates exceeding 70%, stem cells-treated patients achieved higher combined remission versus controls (56.3% vs 38.6%, p = 0.010), mesenchymal cells reported a healing rate of 80% at week 12. In patients with cryptoglandular fistulas, a healing rate of 70% using derivatives of adipose tissue or platelets was achieved, and a healing rate of 80% was achieved using laser technology. Fecal incontinence was improved after the use of autologous platelet growth factors and Nitinol Clips.

CONCLUSION

New surgical techniques showed better healing rates in Crohn's disease patients than classical techniques, which have better results in cryptoglandular fistula than in Crohn's disease. Healing rates for complex cryptoglandular fistulas were similar between the classic and new techniques, being the new techniques less invasive; the incontinence rate improved with the current techniques.

Anti TNF treatment of complex perianal fistulas in children without luminal Crohn's disease: Is it an option?

OBJECTIVES

Complex perianal fistulas (CPFs) in children even in the absence of luminal symptoms prompt evaluation for Crohn's disease (CD). Reports of isolated CPF in children, however, are sparse. In perianal CD, antitumor necrosis factor α (anti TNF) therapy is recommended. We aimed to describe our experience with anti TNF therapy in children with isolated CPF without evidence of luminal CD.

METHODS

We retrospectively reviewed charts of patients with isolated CPF who were treated with anti TNF agents between 2011 and 2019 in a tertiary center. MRI pelvis findings at baseline versus end of follow up were scored using MAGNIFI-CD. Outcomes included clinical remission, radiological response and radiological remission based on MAGNIFI-CD score at end of follow up.

RESULTS

Overall, 17 patients were identified, [10 males (59%), mean age at anti TNF initiation 13.4 ± 2.9 years]. Median time from perianal disease onset to anti TNF was 16.5 months (IQR 9.4-36.4). None of the patients had luminal inflammation. Prior to anti TNF, all patients had been treated with antibiotics without sufficient improvement, and 9/17 with abscess drainage and or Seton insertion. Nine patients (53%) were treated with infliximab while 8 (47%) received adalimumab. Median duration of follow up was 30.7 months (IQR = 12.7-44.8). At the end of follow up 9 patients (53%) achieved clinical remission. When comparing MRI prior to and after anti TNF, 36% (5/14) had radiologic response, of whom 2 (14%) achieved radiologic resolution.

CONCLUSION

Anti TNF agents may be an effective treatment option for children with isolated CPF. Whether these patients should be considered part of the CD phenotypic spectrum or a distinct entity is unclear.

LEVELS OF EVIDENCE

Therapeutic.

Perioperative optimization of Crohn's disease

Crohn's disease (CD) is a chronic inflammatory disease mainly affecting the gastrointestinal tract. With the increased availability of modalities in the last two decades, the treatment of CD has advanced remarkably. Although medical treatment is the mainstay of therapy, most patients require surgery during the course of their illness, especially those who experience complications. Nutritional optimization and ERAS implementation are crucial for patients with CD who require surgical intervention to reduce postoperative complications. The increased surgical risk was found to be associated with the use of corticosteroids, but the association of surgical risk with immunomodulators, biologic therapy, such as anti-TNF mediations, anti-integrin medications, and anti-IL 12/23 was low in certainty. Decisions about preoperative medication must be made on an individual case-dependent basis. Preoperative imaging studies can assist in the planning of appropriate surgical strategies and approaches. However, patients must be informed of any alterations to their treatment. In summary, the management of perioperative medications and surgery-related decision-making should be individualized and patient-centered based on a multidisciplinary approach.

Time to Revisit Disease Classification in Inflammatory Bowel Disease: Is the Current Classification of Inflammatory Bowel Disease Good Enough for Optimal Clinical Management?

Inflammatory bowel disease (IBD), historically subdivided into Crohn's disease and ulcerative colitis, is a very heterogeneous condition. While the tendency in medicine is to try to reduce complexity, IBD is a disease that cannot justify a one-size-fits-all principle. Our current clinical classification tools are suboptimal and need further refinement to capture, at least in part, the variety of phenotypes encountered in daily clinical practice. Although these revised classification tools alone will not be sufficient and should be complemented by more detailed molecular subclassifications, optimized clinical phenotypes can contribute to improved trial designs, future translational research approaches, and better treatment outcomes. In the current review, we discuss key clinical features important in IBD disease heterogeneity, tackle limitations of the current classification systems, propose some potential improvements, and raise priorities for future research in this domain.

The Essential Role of a Multidisciplinary Approach in Inflammatory Bowel Diseases: Combined Medical-Surgical Treatment in Complex Perianal Fistulas in CD

Perianal fistulizing Crohn's disease (PFCD) represents a challenging and complex disease phenotype. Patients typically suffer a more severe disease course than those without perianal complications and are often managing debilitating symptoms. Etiology is understood to be multifactorial, with genetic predisposition, microbiological insult, aberrant immunity, and mechanical factors all implicated. As a result, multimodal treatment strategies must be employed to achieve disease control and fistula closure. This requires the complimentary involvement of medical and surgical disciplines in order to ensure thorough assessment and treatment tailored to the individual scenario and patient goals. The aim of this article is to describe an overview of the various treatment strategies available for PFCD, focusing on how a synergistic approach is required to ensure maximal chances of success.

Advanced Regenerative Medicine Strategies for Treatment of Perianal Fistula in Crohn's Disease

Regenerative medicine is an emerging therapeutic method that aims to reconstruct tissues and organs. This advanced therapeutic approach has demonstrated great potential in addressing the limitations of medical and surgical procedures for treating perineal fistula in patients with Crohn's disease. Recent developments in stem cell technology have led to a massive good manufacturing practices (GMPs) production of various stem cells, including mesenchymal and embryonic cells, along with induction of pluripotent stem cells to repair damaged tissues in the fistula. The recent advances in separation and purification of exosomes, as biologic nanovesicles carrying anti-inflammatory and regenerative agents, have made them powerful tools to treat this inflammatory disease. Further, tremendous advances in nanotechnology, biomaterials, and scaffold fabrication methods enable tissue engineering methods to synthesize tissue-like structures to assist surgical techniques. This review focuses on advanced regenerative-based methods including stem cell therapy, exosome therapy, and tissue engineering used in the treatment of perianal fistula. Relevant in vitro and in vivo studies and the latest innovations in implementation of regenerative medicine for this disease are also separately reviewed. Additionally, current challenges regarding implementation of g stem cells, exosomes, and tissue engineering methods for bridging the gaps between laboratory findings and clinic application will be discussed.

Lack of anti-TNF drugs levels in fistula tissue - a reason for nonresponse in Crohn's perianal fistulating disease?

INTRODUCTION

Anti-TNF therapy is recommended as treatment for patients with Crohn´s perianal fistulas. However, a significant proportion of patients have a sub-optimal response to anti-TNF therapy. Higher serum levels of anti-TNF agents have been associated with improved outcomes in perianal Crohn's disease. Currently, it is unknown whether anti-TNF agent levels can be detected in tissue from fistula tracts themselves and whether this is associated with response.

AIMS AND METHODS

We undertook a pilot study to measure fistula tissue levels of anti-TNF medication (infliximab and adalimumab). We used a previously validated targeted proteomic technique, employing ultraperformance liquid chromatography-mass spectrometry, to detect/quantify anti-TNF drugs. Biopsies were obtained from fistula tracts of patients with Crohn's disease on maintenance treatment; with idiopathic (cryptoglandular) fistula tissues used as negative controls as well as positive controls (by spiking the latter tissues with anti-TNF drugs).

RESULTS

Tissue was sampled from the fistula tracts of seven patients with Crohn's perianal disease (five patients were on adalimumab and two patients were on infliximab). The anti-TNF drugs, infliximab and adalimumab, were not detected in fistula samples from any of the Crohn's patients despite detection in 'spiked' positive control samples.

CONCLUSION

Absence of detection of the anti-TNF drugs in fistula tissue raises the question on the role of tissue penetrance of anti-TNF drugs in response to therapy. Further work is required in a larger number of patients to validate the findings observed and investigate if any correlation exists between tissue and serum levels of anti-TNF and clinical outcome.

SUMMARY

Predicting response in Crohn's fistula patients on biologic therapy is difficult with no reliable biomarkers. This pilot study uses targeted proteomics to investigate the potential role of tissue drug levels in acting as a biomarker of treatment response.

Differences in amino acid and lipid metabolism distinguish Crohn's from idiopathic/cryptoglandular perianal fistulas by tissue metabonomic profiling and may offer clues to underlying pathogenesis

INTRODUCTION

Few studies have investigated perianal fistula etiopathogenesis, and although the cryptoglandular theory is widely accepted in idiopathic cases, in Crohn's disease, it is thought to involve the interplay between microbiological, immunological and genetic factors. A pilot study was conducted to assess for metabolic variations in Crohn's perianal fistula tissue that might differ from that of idiopathic (cryptoglandular) perianal fistula tissue as a comparator. The goal was to identify any potential biomarkers of disease, which may improve the understanding of pathogenesis.

AIMS AND METHODS

Fistula tract biopsies were obtained from 30 patients with idiopathic perianal fistula and 20 patients with Crohn's anal fistula. Two different assays were used in an ultra-high-performance liquid chromatography system coupled with a mass spectrometric detector to achieve broad metabolome coverage. Univariate and multivariate statistical data analyses were used to identify differentiating metabolic features corresponding to the perianal fistula phenotype (i.e. Crohn's disease vs. idiopathic).

RESULTS

Significant orthogonal partial least squares discriminant analysis predictive models (validated with cross-validated-analysis of variance P value <0.05) differentiated metabolites from tissue samples from Crohn's vs. idiopathic anal fistula patients using both metabolic profiling platforms. A total of 41 metabolites were identified, suggesting alterations in pathways, including amino acid, carnitine and lipid metabolism.

CONCLUSION

Metabonomics may reveal biomarkers of Crohn's perianal fistula. Further work in larger numbers is required to validate the findings of these studies as well as cross-correlation with microbiome work to better understand the impact of host-gut/environment interactions in the pathophysiology of Crohn's and idiopathic perianal fistulas and identify novel therapeutic targets.

Current Overview on the Use of Mesenchymal Stem Cells for Perianal Fistula Treatment in Patients with Crohn's Disease

Perianal fistula in patients with Crohn’s disease is an extremely challenging condition. The disease tends to reoccur, and with current treatment options, a large number of patients are left with active ailment and experience major morbidity. In recent years, hopeful results regarding local use of mesenchymal stem cells (MSCs) in perianal Crohn’s disease have been published. Although to this day there are no clear guidelines determining optimal dosage, injections frequency and culture conditions, their efficiency has proven to be much higher than conventionally used methods. According to studies, they can effectively induce as well as maintain fistula closure. This approach also avoids common side effects related to conventional surgical treatment.

Efficacy of Permacol injection for perianal fistulas in a tertiary referral population: poor outcome in patients with complex fistulas

AIM

Injection of Permacol collagen paste can be used as a sphincter-sparing treatment for perianal fistulas. In a tertiary referral population we aimed to evaluate the efficacy of Permacol injection and the clinical and fistula-related factors associated with recurrence.

METHOD

This was a retrospective analysis of consecutive patients with perianal fistulas treated with Permacol injection at a specialist centre between June 2015 and April 2019. Endoanal ultrasonography was systematically reanalysed, blinded to treatment outcome. Rectovaginal, anovaginal and Crohn's disease fistulas were excluded. Healed fistulas were defined as absent anal symptoms and a closed external opening on physical examination at a minimum follow-up of 6 months. Regression analyses were performed to identify factors associated with unhealed fistulas.

RESULTS

A total of 90 patients (51 men; median age 45 years) were analysed. Seventy-two (80.0%) patients had complex perianal fistulas (greater than one-third sphincter involvement or multiple tracts). After a single Permacol injection, fistulas were healed in 20 (22.2%) patients at 3 months follow-up and in 18 (20.0%) patients at a median follow-up of 30 months (interquartile range 17-37). Eight (11.1%) patients with unhealed fistulas had significant improvement in their symptoms. Complex fistulas were significantly associated with unhealed status [OR 3.53 (95% CI 1.12-11.09); p = 0.031]. Twenty patients underwent subsequent Permacol injections, which were successful in six (30.0%) patients after one (n = 3) or two (n = 3) additional injections.

CONCLUSION

This largest study to date in patients with mainly complex perianal fistulas, demonstrated that the efficacy of a single Permacol injection was only 20%. Complex fistulas were associated with a poor outcome.

Application of platelet-rich plasma in rectovaginal fistulas in the patients with ulcerative colitis

BACKGROUND

There is a need for other than surgical methods of therapy for small and low rectovaginal fistulas (RVF) in the course of inflammatory bowel diseases (IBD), such as application of fibrin sealants, stem cells, biological therapy, or platelet-rich plasma. The aim of this study was to evaluate the results of the treatment after local application of PRP in aforementioned fistulas, exclusively in the patients with ulcerative colitis (UC).

PATIENTS AND METHODS

Medical records of 13 patients with small and low-lying, active RVF in the course of UC, and after restorative proctocolectomy for UC were evaluated. Curettage of fistulous tracts was performed with the following application of PRP in all patients.

RESULTS

Complete closure of RVF was achieved after the first injection in 4 patients, 3 women healed their fistulas following the second application, and two of them closed RVF after 3 injections. To sum up, the complete closure of RVF was achieved in 9 (69%) patients. Fistulas remained closed from 6 to 12 months.

CONCLUSIONS

The application of PRP in small, low, and recurrent IBD anal fistulas is effective, simple, and safe with an acceptable rate of healing. This therapy might also precede any further, surgical methods of treatment.

Adjunctive Hyperbaric Oxygen Therapy in Refractory Crohn's Disease: An Observational Study

Background and Aims

Patients may experience complications of Crohn's disease (CD) even when treated with optimal medical therapy strategies. Previous data have shown the efficacy of hyperbaric oxygen therapy (HBOT) in the management of complicated CD. However, there is no consensus regarding the optimal number of sessions or duration of treatment regimens. The aim of the present study was to investigate the efficacy of HBOT in CD patients who were refractory to conventional medical management.

Methods

This study included patients who underwent HBOT for the treatment of the following complications: perianal fistulizing Crohn's disease (pCD), enterocutaneous fistulas (ECF), or pyoderma gangrenosum (PG). Complete healing was defined as the closure of external orifice and the absence of active draining (in pCD), complete wound healing (in PG), and granulation or complete wound epithelialization with no enteric draining (in ECF). The persistence of draining and the absence of wound granulation were defined as incomplete healing.

Results

Forty patients were included. The mean CD duration was 10.6 ± 5.8 years. pCD comprised most of the included patients (25/62.5%), followed by ECF (n = 13/32.5%) and PG (n = 6/15%). In two patients (5%), a combination of ECF and PG was diagnosed, and in one patient (2.5%), all three complications were observed. A total of 32 patients (82.5%) had complete healing. Patients with PG had the highest healing rates (100%), followed by those with ECF (84.6%) and pCD (80%).

Conclusions

Adjunctive HBO was associated with significant healing rates for CD-associated complications such as pCD, ECF, and PG.

Histologic progression of acne inversa/hidradenitis suppurativa: Implications for future investigations and therapeutic intervention

Since first recognized in 1839, the pathogenesis of acne inversa (AI) has undergone repeated revisions. Although there is agreement that AI involves occlusion of hair follicles with subsequent inflammation and the formation of tracts, the histologic progression of this disease still requires refinement. The objective of this study was to examine the histologic progression of AI based on the examination of a large cohort of punch biopsies and excisional samples that were examined first by hematoxylin and eosin staining. The most informative of these samples were step‐sectioned and stained by immunohistochemistry for epithelial and inflammatory markers. Based on this examination, the following observations were made: 1) AI arises from the epithelium of the infundibulum of terminal and vellus hairs; 2) These form cysts and epithelial tendrils that extend into soft tissue; 3) Immunohistochemical staining demonstrates the epithelium of AI is disordered with infundibular and isthmic differentiation and de novo expression of stem cell markers; 4) The inflammatory response in AI is heterogeneous and largely due to cyst rupture. The conclusions of this investigation were that AI is an epithelial‐driven disease caused by infiltrative, cyst forming tendrils and most of the inflammation is due to cyst rupture and release of cornified debris and bacteria. Cyst rupture often occurs below the depths of punch biopsy samples indicating their use for analysis may give an incomplete picture of the disease. Finally, our data suggest that unless therapies inhibit tendril development, it is unlikely they will cause prolonged treatment‐induced remission in AI.

Perianal fistula and the ileoanal pouch - different aetiologies require distinct evaluation

AIM

Restorative proctocolectomy has been widely adopted as the procedure of choice for restoring gastrointestinal continuity following proctocolectomy. It is often associated with improved quality of life and high patient satisfaction; however, the development of a pouch anal fistula can cause significant morbidity. Pouch fistulas are notoriously difficult to treat and there is great heterogeneity in the management reported of these fistulas. A lack of classification, and the assumption that fistulas originating from completely different aetiologies will behave and respond similarly to a particular treatment strategy, precludes meaningful comparison of management outcomes. We aim to introduce consistency in the reporting of pouch fistulas using a novel classification system.

METHODS

A consensus process involving clinicians experienced in the management of pouch fistulas from two high volume tertiary centres was performed.

RESULTS

We propose that pouch anal fistulas should be classified into four distinct groups according to their aetiology: group 1, anastomotic related; group 2, inflammatory bowel disease related, with sub-classifications Crohn's (type A) and non-Crohn's (type B) in origin; group 3, cryptoglandular related; and group 4, malignancy related.

CONCLUSION

Classification of pouch fistulas according to their aetiology will provide consistency in the literature and improve the quality of prospective evidence for the management of pouch fistulas.

Current review of the management of fistulising perianal Crohn's disease

Perianal manifestations of Crohn's disease constitute a distinct disease phenotype commonly affecting patients and conferring an increased risk of disability and disease burden. Much research has gone into management of fistulising manifestations, with biological therapy changing the landscape of treatment. In this article, we discuss the up-to-date surgical and medical management of perianal fistulas, highlighting current consensus management guidelines and the evidence behind them, as well as future directions in management.

Enterocutaneous Fistula: A Simplified Clinical Approach

A “fistula” is an abnormal connection between two epithelial surfaces. Fistulae are named based on the two surfaces or lumens they connect to. Fistulae form due to loss of wall integrity from an underlying insult, leading to the penetrance of an adjacent organ or epithelized surface. Common causes of small bowel fistulae include sequelae of surgical intervention, foreign body, bowel diverticula, Crohn's disease, malignancy, radiation, and infection. A histopathological analysis displays acute and/or chronic inflammation due to the underlying pathology.

A thorough history and physical examination are important components of patient evaluation. Generally, patients will present with non-specific constitutional symptoms in addition to local symptoms attributed to the fistula. In rare instances, symptoms may be severe and life-threatening. Initial laboratory workup includes complete blood count, comprehensive metabolic panel, and lactate level. Radiologic imaging is useful for definitive diagnosis and helps delineate anatomy. In practice, computed tomography (CT) is the initial imaging modality. The addition of intravenous or enteric contrast may be helpful in certain situations. Magnetic resonance imaging (MRI) may also be used in special circumstances. Invasive procedures, such as endoscopy, can assist in the evaluation of mucosal surfaces to diagnose pathology such as inflammatory processes.

Appropriate management should include optimizing nutritional status, delineating fistulous tract anatomy, skincare, and managing the underlying disease. A non-operative approach is generally accepted as the initial approach especially in the acute/subacute setting. However, operative intervention is indicated in the setting of failed non-operative management. Successful management of small bowel fistulae requires a multidisciplinary team approach.

To conclude, a small bowel fistula is a complex clinical disease, with surgical intervention being the most common cause in developed countries. The non-operative approach should be trialed before an operative approach is considered.

Preclinical Model of Perianal Fistulizing Crohn's Disease

BACKGROUND

Fistulizing anoperineal lesions (FAPLs) are common and severe complications of Crohn's disease (CD), exposing patients to the risk of anal sphincter alteration and permanent stoma. Due to the limited efficacy of current treatments, identifying new local therapies is mandatory. However, testing new treatments is currently limited because no relevant preclinical model of Crohn's-like FAPL is available. Thus, a reliable and reproducible experimental model of FAPLs is needed to assess new therapeutic strategies.

METHODS

Twenty-one rats received a rectal enema of 2,4,6-trinitrobenzensulfonic acid (TNBS) to induce proctitis. Seven days later, a transsphincteric fistula tract was created with a surgical thread, instilled with TNBS twice a week until its removal at day 7 (group 1), day 14 (group 2), or day 28 (group 3). In each rat, pelvic MRI was performed just before and 7 days after thread removal. Rats were sacrificed 7 days after thread removal for pathological assessment of the fistula tract.

RESULTS

The optimal preclinical model was obtained in group 3. In this group, 7 days after thread removal, all animals (9 of 9) had a persistent fistula tract visible on MRI with T2-hypersignal (normalized T2 signal intensity: 2.36 ± 0.39 arbitrary units [a.u.] [2.08-2.81]) and elevation of the apparent diffusion coefficient (1.33 ± 0.16 10-3 millimeter squared per seconds [1.18-1.49]). The pathological examination of the fistula tract revealed acute and chronic inflammation, granulations, fibrosis, epithelialization, and proctitis in the adjacent rectum.

CONCLUSIONS

This reproducible preclinical model could be used to assess the effectiveness of innovative treatments in perianal fistulizing CD.

British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults

Ulcerative colitis and Crohn's disease are the principal forms of inflammatory bowel disease. Both represent chronic inflammation of the gastrointestinal tract, which displays heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management relies on understanding and tailoring evidence-based interventions by clinicians in partnership with patients. This guideline for management of inflammatory bowel disease in adults over 16 years of age was developed by Stakeholders representing UK physicians (British Society of Gastroenterology), surgeons (Association of Coloproctology of Great Britain and Ireland), specialist nurses (Royal College of Nursing), paediatricians (British Society of Paediatric Gastroenterology, Hepatology and Nutrition), dietitians (British Dietetic Association), radiologists (British Society of Gastrointestinal and Abdominal Radiology), general practitioners (Primary Care Society for Gastroenterology) and patients (Crohn's and Colitis UK). A systematic review of 88 247 publications and a Delphi consensus process involving 81 multidisciplinary clinicians and patients was undertaken to develop 168 evidence- and expert opinion-based recommendations for pharmacological, non-pharmacological and surgical interventions, as well as optimal service delivery in the management of both ulcerative colitis and Crohn's disease. Comprehensive up-to-date guidance is provided regarding indications for, initiation and monitoring of immunosuppressive therapies, nutrition interventions, pre-, peri- and postoperative management, as well as structure and function of the multidisciplinary team and integration between primary and secondary care. Twenty research priorities to inform future clinical management are presented, alongside objective measurement of priority importance, determined by 2379 electronic survey responses from individuals living with ulcerative colitis and Crohn's disease, including patients, their families and friends.

British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults

Ulcerative colitis and Crohn's disease are the principal forms of inflammatory bowel disease. Both represent chronic inflammation of the gastrointestinal tract, which displays heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management relies on understanding and tailoring evidence-based interventions by clinicians in partnership with patients. This guideline for management of inflammatory bowel disease in adults over 16 years of age was developed by Stakeholders representing UK physicians (British Society of Gastroenterology), surgeons (Association of Coloproctology of Great Britain and Ireland), specialist nurses (Royal College of Nursing), paediatricians (British Society of Paediatric Gastroenterology, Hepatology and Nutrition), dietitians (British Dietetic Association), radiologists (British Society of Gastrointestinal and Abdominal Radiology), general practitioners (Primary Care Society for Gastroenterology) and patients (Crohn's and Colitis UK). A systematic review of 88 247 publications and a Delphi consensus process involving 81 multidisciplinary clinicians and patients was undertaken to develop 168 evidence- and expert opinion-based recommendations for pharmacological, non-pharmacological and surgical interventions, as well as optimal service delivery in the management of both ulcerative colitis and Crohn's disease. Comprehensive up-to-date guidance is provided regarding indications for, initiation and monitoring of immunosuppressive therapies, nutrition interventions, pre-, peri- and postoperative management, as well as structure and function of the multidisciplinary team and integration between primary and secondary care. Twenty research priorities to inform future clinical management are presented, alongside objective measurement of priority importance, determined by 2379 electronic survey responses from individuals living with ulcerative colitis and Crohn's disease, including patients, their families and friends.

Fistulotomy and primary sphincteroplasty for anal fistula: long-term data on continence and patient satisfaction

BACKGROUND

The aim of this study was to evaluate the safety and long-term efficacy of fistulotomy and primary sphincteroplasty (FIPS). Secondary endpoints were its impact on postoperative continence status and patients' satisfaction.

METHODS

A retrospective study was conducted on patients with cryptoglandular anal fistula (AF) who had FIPS between June 2006 and May 2017. Patients were evaluated with standardized telephone interviews and clinical/instrumental assessment. Main outcome measures included fistula healing rate, continence status, and patient satisfaction. Incontinence was defined as an inability to hold either gas, liquid, or solid stools, as well as postdefecation soiling, and was measured by the Cleveland Clinic fecal incontinence score. Patient satisfaction was evaluated by an 11-point numeric rating scale.

RESULTS

There were 203 patients (139 males; mean age: 48.7 years) who had FIPS. The overall healing rate was 93% (188 patients) with a mean follow-up period of 56 ± 31 months. Half of the total cohort (51%) had a complex fistula. Preoperatively, 8 (4%) patients complained of postdefecation soiling and 2 (1%) of gas incontinence. Postoperatively, 26 (13%) patients had continence impairment (de novo n = 24), mainly consisting of postdefecation soiling (10%). In univariate analysis, patients with recurrent (RR 6.153 95% CI 2.097-18.048; p = 0.002) or complex (RR 3.005 95% CI 1.203-7.506; p = 0.012) AF and those with secondary tracts (RR 8.190 95% CI 2.188-30.654; p = 0.004) or previous set on drainage (RR 5.286 95% CI 2.235-12.503; p = 0.0001) were at higher risk of incontinence. In multivariate analysis, no significant predictors were found, although fistula complexity approached statistical significance (RR 5.464 95% CI 0.944-31.623; p = 0.050). The mean patient satisfaction numeric rating scale was 9.3 ± 1.6. Lower satisfaction rates were found in patients with transphincteric (p = 0.011) or complex (p = 0.0001) AF, with secondary tracts (p = 0.041) or previous seton drainage (p = 0.008), and in those with postoperative continence impairment (p = 0.0001). Postoperative onset of incontinence was the only significant factor in multivariate analysis (p = 0.0001).

CONCLUSIONS

FIPS should be considered a valid therapeutic option for selected AF. However, the risk of postoperative minor fecal incontinence exists, and should be discussed during preoperative patient counselling.

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.