Preclinical Model of Perianal Fistulizing Crohn's Disease

Bergapten enhances mitophagy to regulate intestinal barrier and Th17/Treg balance in mice with Crohn's disease-like colitis via PPARγ/NF-κB signaling pathway

This study aimed to investigate whether bergapten (BG), a furanocoumarin phytohormone, holds promise for Crohn's disease (CD)-like colitis treatment and to preliminarily explore its potential mechanisms. 2,4,6-Trinitrobenzenesufonic acid (TNBS)-treated mice were applied to establish an in vivo research model, and BG was administered with different concentrations. The status of mice in each group was evaluated by disease activity index (DAI), and the severity was evaluated by pathological sections. The intestinal barrier was assessed by measuring in vivo intestinal permeability, peripheral blood intestinal fatty acid-binding protein (I-FABP) levels, epithelial resistance values, and tight junction protein levels. Markers were then used to assess Th17/Treg levels, mitophagy, and the peroxisome proliferator-activated receptor (PPAR)γ/ nuclear factor kappa B (NF-κB) signaling pathway. BG significantly reduced colon tissue damage in a concentration-dependent manner. DAI scores showed that the loose feces, occult blood, and weight loss of mice in the BG treatment were significantly reduced, and pathological section results revealed reduced inflammatory infiltration and fibrosis. Reduced serum FITC-dextran and I-FABP and increased levels of epithelial resistance and tight junction proteins support that the intestinal barrier was protected upon BG. The proportion of Th17 in mesenteric lymph nodes increased while Treg decreased in the model group. BG treatment effectively reduced the conversion of Treg to Th17. Additionally, BG was found to enhance mitophagy and activate the PPARγ/NF-κB signaling. BG demonstrates promising effects in ameliorating intestinal barrier damage and Th17/Treg imbalance in a murine model of CD-like colitis, while also promoting intracellular mitophagy. The PPARγ/NF-κB signaling pathway may serve as a key mediator of BG's regulatory mechanisms.

Extracellular Vesicles Delivered by a Nanofiber-Hydrogel Composite Enhance Healing In Vivo in a Model of Crohn's Disease Perianal Fistula

Perianal fistulas represent a common, aggressive, and disabling complication of Crohn's disease (CD). Despite recent drug developments, novel surgical interventions as well as multidisciplinary treatment approaches, the outcome is dismal, with >50% therapy failure rates. Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) offer potential therapeutic benefits for treating fistulizing CD, due to the pro-regenerative paracrine signals. However, a significant obstacle to clinical translation of EV-based therapy is the rapid clearance and short half-life of EVs in vivo. Here, an injectable, biodegradable nanofiber-hydrogel composite (NHC) microgel matrix that serves as a carrier to deliver MSC-derived EVs to a rat model of CD perianal fistula (PAF) is reported. It is found that EV-loaded NHC (EV-NHC) yields the best fistula healing when compared to other treatment arms. The MRI assessment reveals that the EV-NHC reduces inflammation at the fistula site and promotes tissue healing. The enhanced therapeutic outcomes are contributed by extended local retention and sustained release of EVs by NHC. In addition, the EV-NHC effectively reduces inflammation at the fistula site and promotes tissue healing and regeneration via macrophage polarization and neo-vascularization. This EV-NHC platform provides an off-the-shelf solution that facilitates its clinical translation.

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.

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).

A nanofiber-hydrogel composite improves tissue repair in a rat model of Crohn's disease perianal fistulas

Perianal fistulas (PAFs) represent a severe complication of Crohn's disease (CD). Despite the advent of biologic and small-molecule therapeutics for luminal disease, PAFs in CD (CD-PAF) are relatively resistant to treatment, with less than 50% responding to any therapy. We report an injectable, biodegradable, mechanically fragmented nanofiber-hydrogel composite (mfNHC) loaded with adipose-derived stem cells (ADSCs) for the treatment of fistulas in a rat model of CD-PAF. The ADSC-loaded mfNHC results in a higher degree of healing when compared to surgical treatment of fistulas, which is a standard treatment. The volume of fistulas treated with mfNHC is decreased sixfold compared to the surgical treatment control. Molecular studies reveal that utilization of mfNHC reduced local inflammation and improved tissue regeneration. This study demonstrates that ADSC-loaded mfNHC is a promising therapy for CD-PAF, and warrants further studies to advance mfNHC toward clinical translation.

Timing of individualized surgical intervention in Crohn’s disease

Crohn’s disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract with an increasing incidence worldwide. Comprehensive therapy for CD focuses on symptom control and healing the intestinal mucosa to improve the quality of life and prevent complications. Surgical intervention plays a vital role in comprehensive therapy. However, deciding the optimal timing for surgical intervention has long been a focus of controversy. This review provides insights into the timing of surgery for CD and guides clinicians in daily treatment.

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.

A Preclinical Validation of Iron Oxide Nanoparticles for Treatment of Perianal Fistulizing Crohn's Disease

Fistulizing anoperineal lesions are severe complications of Crohn's disease (CD) that affect quality of life with a long-term risk of anal sphincter destruction, incontinence, permanent stoma, and anal cancer. Despite several surgical procedures, they relapse in about two-thirds of patients, mandating innovative treatments. Ultrasmall particles of iron oxide (USPIO) have been described to achieve in vivo rapid healing of deep wounds in the skin and liver of rats thanks to their nanobridging capability that could be adapted to fistula treatment. Our main purpose was to highlight preclinical data with USPIO for the treatment of perianal fistulizing CD. Twenty male Sprague Dawley rats with severe 2,4,6-trinitrobenzenesulfonic acid solution (TNBS)-induced proctitis were operated to generate two perianal fistulas per rat. At day 35, two inflammatory fistulas were obtained per rat and perineal magnetic resonance imaging (MRI) was performed. After a baseline MRI, a fistula tract was randomly drawn and topically treated either with saline or with USPIO for 1 min (n = 17 for each). The rats underwent a perineal MRI on postoperative days (POD) 1, 4, and 7 and were sacrificed for pathological examination. The primary outcome was the filling or closure of the fistula tract, including the external or internal openings. USPIO treatment allowed the closure and/or filling of all the treated fistulas from its application until POD 7 in comparison with the control fistulas (23%). The treatment with USPIO was safe, permanently closed the fistula along its entire length, including internal and external orifices, and paved new avenues for the treatment of perianal fistulizing Crohn's disease.

Establishing a rabbit model of perianal fistulizing Crohn’s disease

BACKGROUND

Crohn's disease (CD) is a chronic nonspecific intestinal inflammatory disease. The aetiology and pathogenesis of CD are still unclear. Anal fistula is the main complication of CD and is a difficult problem to solve at present. The main limitation of developing new therapies is bound up with the short of preclinical security and effectiveness data. Therefore, an ideal animal model is needed to establish persistent anal fistula and an inflamed rectal mucosa.

AIM

To improve the induction method of colitis and establish a reliable and reproducible perianal fistulizing Crohn’s disease animal model to evaluate new treatment strategies.

METHODS

Twenty male New Zealand rabbits underwent rectal enema with different doses of 2,4,6-trinitrobenzene sulfonic acid to induce proctitis. Group A was treated with an improved equal interval small dose increasing method. The dosage of group B was constant. Seven days later, the rabbits underwent surgical creation of a transsphincteric fistula. Then, three rabbits were randomly selected from each group every 7 d to remove the seton from the fistula. The rabbits were examined by endoscopy every 7 days, and biopsy forceps were used to obtain tissue samples from the obvious colon lesions for histological analysis. The disease activity index (DAI), colonoscopy and histological scores were recorded. Perianal endoscopic ultrasonography (EUS) was used to evaluate the healing of fistulas.

RESULTS

Except for the DAI score, the colonoscopy and histological scores in group A were significantly higher than those in group B (P < 0.05). In the ideal model rabbit group, on the 7^th day after the removal of the seton, all animals had persistent lumens on EUS imaging, showing continuous full-thickness high signals. Histological inspection of the fistula showed acute and chronic inflammation, fibrosis, epithelialization and peripheral proctitis of the adjoining rectum.

CONCLUSION

The improved method of CD colitis induction successfully established a rabbit perianal fistula CD preclinical model, which was confirmed by endoscopy and pathology.

Adipose-Derived Stem Cells in the Treatment of Perianal Fistulas in Crohn's Disease: Rationale, Clinical Results and Perspectives

Between 20 to 25% of Crohn’s disease (CD) patients suffer from perianal fistulas, a marker of disease severity. Seton drainage combined with anti-TNFα can result in closure of the fistula in 70 to 75% of patients. For the remaining 25% of patients there is room for in situ injection of autologous or allogenic mesenchymal stem cells such as adipose-derived stem/stromal cells (ADSCs). ADSCs exert their effects on tissues and effector cells through paracrine phenomena, including the secretome and extracellular vesicles. They display anti-inflammatory, anti-apoptotic, pro-angiogenic, proliferative, and immunomodulatory properties, and a homing within the damaged tissue. They also have immuno-evasive properties allowing a clinical allogeneic approach. Numerous clinical trials have been conducted that demonstrate a complete cure rate of anoperineal fistulas in CD ranging from 46 to 90% of cases after in situ injection of autologous or allogenic ADSCs. A pivotal phase III-controlled trial using allogenic ADSCs (Alofisel^®) demonstrated that prolonged clinical and radiological remission can be obtained in nearly 60% of cases with a good safety profile. Future studies should be conducted for a better knowledge of the local effect of ADSCs as well as for a standardization in terms of the number of injections and associated procedures.

Evaluation of animal models of Crohn's disease with anal fistula (Review)

Anal fistula is a common and serious complication of Crohn's disease (CD). A sufficiently suitable animal model that may be used to simulate this disease is yet to be established. The aim of the present review was to summarize the different characteristics and experimental methods of commonly used animal models of CD with anal fistula. Electronic databases were searched for studies reporting on the use of this type of animal model. A total of 234 related articles were retrieved, of which six articles met the inclusion criteria; these were used as references for the present review article. The characteristics of the animal models, the advantages and disadvantages of the modeling methods and the similarities with patients with CD and anal fistula were summarized and analyzed. The evidence suggests that a sufficiently suitable animal preclinical model requires to be established.