Pharmacological Therapies for the Management of Fistulizing Crohn's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Fistulas are a debilitating complication of Crohn's disease [CD]. We conducted a systematic review to assess the efficacy of medical therapies for fistulizing CD.

METHODS

MEDLINE, Embase, and CENTRAL were searched on May 26, 2022, for randomized controlled trials [RCTs] of pharmacological therapy in adults with fistulizing CD. The primary outcome was induction and maintenance of fistula response. Pooled risk ratios [RRs] and 95% confidence intervals [CIs] were calculated. GRADE was used to assess the certainty of evidence.

RESULTS

Thirty-eight RCTs were included. Nineteen trials [50%] exclusively involved perianal fistula. The remaining studies included some participants with non-perianal fistula. Pooled RRs for anti-tumour necrosis factor [TNF] agents were not statistically significant for induction [RR 1.36, 95% CI 0.97-1.91] or maintenance of fistula response [RR 1.48, 95% CI 0.97-2.27]. However, in a sensitivity analysis of studies with fistula response as the primary outcome, anti-TNFs were superior to placebo for induction [RR 1.94, 95% CI 1.10-3.41] and maintenance [RR 1.88, 95% CI 1.23-2.88] of fistula response. Oral small molecules [RR 2.56, 95% CI 1.18-5.53] and mesenchymal stem cell [MSC] therapy [RR 1.26, 95% CI 1.01-1.57] were effective for induction of fistula response. Ustekinumab was associated with maintenance of fistula response [RR 1.80, 95% CI 1.04-3.11]. Vedolizumab was not superior to placebo. The certainty of evidence ranged from very low to moderate.

CONCLUSION

Very low- to moderate-certainty evidence suggests that anti-TNF therapy, oral small molecules, ustekinumab, and MSCs are effective for perianal fistulizing CD. Dedicated fistula studies evaluating biologics and small molecules are needed.

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-TNF therapy (combined therapy) vs. either therapy alone.

METHODS

MEDLINE, EMBASE, and Cochrane databases were searched systematically through December 2023. Surgical intervention was defined as an exam under anesthesia ± setons. We calculated weighted risk ratios (RR) with 95% confidence intervals (CI) 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 (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.

Comparative Effectiveness of Biologic Therapies in Preventing Penetrating Complications in Patients With Crohn's Disease

BACKGROUND & AIMS

Comparative effectiveness of biologics in preventing penetrating disease (PD) in Crohn's disease (CD) is not well established. We compared the risk of developing luminal and perianal PD (LPD and PPD) between biologics used as first-line therapies.

METHODS

Adults (>17 years) with CD who initiated their first biologic (anti-tumor necrosis factor [anti-TNF], ustekinumab [UST], or vedolizumab [VDZ]) were identified from Merative Commercial Database (2006 and 2020). We excluded preexisting PD using a minimum look-back period of 1 year. Cohorts were balanced by inverse probability of treatment weighting based on age, sex, comorbidities, prior CD surgery, and CD severity. Pairwise comparisons were performed by Cox proportional hazards models, adjusted for immunomodulator exposure, and with biologic exposure treated as a time-dependent variable based on a medication possession ratio of 0.8.

RESULTS

Our analysis included 40,693 patients: 93% anti-TNF, 3% UST, and 4% VDZ. After inverse probability of treatment weighting all comparisons were well balanced. Anti-TNF was protective against LPD (hazard ratio, 0.66; 95% confidence interval, 0.55-0.78; P < .0001) and PPD (hazard ratio, 0.88; 95% confidence interval, 0.80-0.96; P = .0045) compared with VDZ and LPD (hazard ratio, 0.37; 95% confidence interval, 0.30-0.46; P < .0001) compared with UST. There were no significant differences in the risk of LPD and PPD between VDZ and UST. These results were similar after limiting the study period to after 2016.

CONCLUSIONS

Anti-TNF therapy was associated with a lower risk of LPD and PPD compared with VDZ, and lower risk of LPD compared with UST. Further studies are needed to validate these findings and to determine potential reasons for these differences.

Comparative Efficacy of Advanced Therapies for Achieving Endoscopic Outcomes in Crohn's Disease: A Systematic Review and Network Meta-Analysis

BACKGROUND & AIMS

We conducted a network meta-analysis to compare the efficacy of advanced therapies for achieving endoscopic outcomes in patients with moderate-to-severely active Crohn's disease.

METHODS

MEDLINE, Embase, and Cochrane CENTRAL databases were searched from inception to August 2, 2023 to identify phase II and III randomized controlled trials (RCTs) in adults (≥18 years) with moderate-to-severe Crohn's disease treated with tumor necrosis factor (TNF) antagonists, etrolizumab, vedolizumab, anti-interleukin (IL)12/23p40, anti-IL23p19, or Janus kinase-1 (JAK1) inhibitors, compared with placebo/active comparator, for induction and/or maintenance of remission and reported endoscopic outcomes. Primary outcome was endoscopic response after induction therapy, and endoscopic remission after maintenance therapy. We performed a random-effects network meta-analysis using a frequentist approach, and estimated relative risk (RRs), 95% confidence interval (CI) values, and P score for ranking agents. We used GRADE to ascertain certainty of evidence.

RESULTS

A total of 20 RCTs (19 placebo-controlled and 1 head-to-head trial; 5592 patients) were included out of which 12 RCTs reported endoscopic outcomes for the induction phase, 5 reported for the maintenance phase, and 3 reported for both induction and maintenance phases. JAK1 inhibitors (RR, 3·49 [95% CI, 1·48-8·26]) and anti-IL23p19 (RR, 2·30 [95% CI, 1·02-5·18]) agents were more efficacious than etrolizumab (moderate certainty of evidence), and JAK1 inhibitors (RR, 2·34 [95% CI, 1·14-4·80]) were more efficacious than anti-IL12/23p40 agents for inducing endoscopic response (moderate certainty of evidence). JAK1 inhibitors and anti-IL23p19 ranked highest for induction of endoscopic response. There was paucity of RCTs of TNF antagonists reporting endoscopic outcomes with induction therapy. On network meta-analysis of 6 RCTs, all agents except vedolizumab (RR, 1.89 [95% CI, 0.61-5.92]) were effective in maintaining endoscopic remission compared with placebo. TNF antagonists, IL12/23p40, and JAK1 inhibitors were ranked highest.

CONCLUSIONS

On network meta-analysis, JAK1 inhibitors and anti-IL23p19 agents may be the most effective among non-TNF-targeting advanced therapies for inducing endoscopic response. Future head-to-head trials will further inform positioning of different therapies for the management of Crohn's disease.

Development of an MRI-Based Prediction Model for Anti-TNF Treatment Failure in Perianal Crohn's Disease: A Multicenter Study

BACKGROUND & AIMS

Clinical and radiologic variables associated with perianal fistula (PAF) outcomes are poorly understood. We developed prediction models for anti-tumor necrosis factor (TNF) treatment failure in patients with Crohn's disease-related PAF.

METHODS

In a multicenter retrospective study between 2005 and 2022 we included biologic-naive adults (>17 years) who initiated their first anti-TNF therapy for PAF after pelvic magnetic resonance imaging (MRI). Pretreatment MRI studies were prospectively reread centrally by blinded radiologists. We developed and internally validated a prediction model based on clinical and radiologic parameters to predict the likelihood of anti-TNF treatment failure, clinically, at 6 months. We compared our model and a simplified version of MRI parameters alone with existing imaging-based PAF activity indices (MAGNIFI-CD and modified Van Assche MRI scores) by De Long statistical test.

RESULTS

We included 221 patients: 32 ± 14 years, 60% males, 76% complex fistulas; 68% treated with infliximab and 32% treated with adalimumab. Treatment failure occurred in 102 (46%) patients. Our prediction model included age at PAF diagnosis, time to initiate anti-TNF treatment, and smoking and 8 MRI characteristics (supra/extrasphincteric anatomy, fistula length >4.3 cm, primary tracts >1, secondary tracts >1, external openings >1, tract hyperintensity on T1-weighted imaging, horseshoe anatomy, and collections >1.3 cm). Our full and simplified MRI models had fair discriminatory capacity for anti-TNF treatment failure (concordance statistic, 0.67 and 0.65, respectively) and outperformed MAGNIFI-CD (P = .002 and < .0005) and modified Van Assche MRI scores (P < .0001 and < .0001), respectively.

CONCLUSIONS

Our risk prediction models consisting of clinical and/or radiologic variables accurately predict treatment failure in patients with PAF.

Perianal Fistulas Are Associated with Persistently Higher Direct Health Care Costs in Crohn's Disease: A Population-Based Study

BACKGROUND

The economic impact of perianal fistulas in Crohn's disease (CD) has not been formally assessed in population-based studies in the biologic era.

AIM

To compare direct health care costs in persons with and without perianal fistulas.

METHODS

We performed a longitudinal population-based study using administrative data from Ontario, Canada. Adults (> 17 years) with CD were identified between 2007 and 2013 using validated algorithms. Perianal fistula positive "cases" were matched to up to 4 "controls" with CD without perianal fistulas based on age, sex, geographic region, year of CD diagnosis and duration of follow-up. Direct health care costs, excluding drug costs from private payers, were estimated annually beginning 5 years before (lookback) and up to 9 years after perianal fistula diagnosis (study completion) for cases and a standardized date for matched controls.

RESULTS

A total of 581 cases were matched to 1902 controls. The annual per capita direct cost for cases was similar at lookback compared to controls ($2458 ± 6770 vs $2502 ± 10,752; p = 0.952), maximally greater in the first year after perianal fistulas diagnosis ($16,032 ± 21,101 vs $6646 ± 13,021; p < 0.001) and remained greater at study completion ($11,358 ± 17,151 vs $5178 ± 9792; p < 0.001). At perianal fistula diagnosis, the cost difference was driven primarily by home care cost (tenfold greater), publicly-covered prescription drugs (threefold greater) and hospitalizations (twofold greater), whereas at study completion, prescription drugs were the dominant driver (threefold greater).

CONCLUSION

In our population-based cohort, perianal fistulas were associated with significantly higher direct healthcare costs at the time of perianal fistulas diagnosis and sustained long-term.

Video Capsule Endoscopy can Identify Occult Luminal Crohn's Disease in Patients with Isolated Perianal Fistulas

BACKGROUND

Accurate tools to distinguish Crohn's disease [CD] from cryptoglandular disease in patients with perianal fistulas without detectable luminal inflammation on ileocolonoscopy and abdominal enterography (isolated perianal fistulas [IPF]) are lacking. We assessed the ability of video capsule endoscopy [VCE] to detect luminal inflammation in patients with IPF.

METHODS

We studied consecutive adults [>17 years] with IPF who were evaluated by VCE after a negative ileocolonoscopy and abdominal enterography between 2013 and 2022. We defined luminal CD by VCE as diffuse erythema, three or more aphthous ulcers, or a Lewis score greater than 135. We compared rates of intestinal inflammation in this cohort with age- and sex-matched controls without perianal fistulas, who underwent VCE for other indications. We excluded persons with pre-existing inflammatory bowel disease [IBD] and exposure to non-steroidal anti-inflammatory drugs or immunosuppressive treatments.

RESULTS

A total of 45 patients with IPF underwent VCE without complications. Twelve patients [26%] met our definition of luminal CD. Luminal CD was more common in patients with IPF than in controls [26% vs 3%; p <0.01]. Among patients with IPF, male sex (OR [odds ratio], 9.2; 95% confidence interval [CI] [1.1-79.4]), smoking (OR, 4.5; 95% CI [0.9-21.2]), abscess (OR, 6.3; 95% CI [1.5-26.8]), rectal enhancement on magnetic resonance imaging [MRI] (OR, 9.0; 95% CI [0.8-99.3]), and positive antimicrobial serology (OR, 7.1; 95% CI, [0.7-70.0]) were more common in those with a positive VCE study.

CONCLUSIONS

VCE detected small intestinal inflammation suggestive of luminal CD in approximately one-quarter of patients with IPF. Larger studies are required to validate these findings.

Venous Thromboembolism After COVID-19 Infection Among People With and Without Immune-Mediated Inflammatory Diseases

Importance

Immune-mediated inflammatory diseases (IMIDs) and COVID-19 are independently associated with venous thromboembolisms (VTEs).

Objective

To determine if individuals with IMIDs are at higher risk of VTE following COVID-19 infection compared with individuals without IMIDs.

Design, Setting, and Participants

Population-based matched cohort study using multiple deterministically linked health administrative databases from Ontario, Canada, and including patients testing positive for COVID-19 between January 1, 2020, and December 30, 2021, and followed up until March 31, 2022. Individuals with IMIDs (n = 28 440) who tested positive for COVID-19 were matched with up to 5 individuals without an IMID (n = 126 437) who tested positive for COVID-19. Matching was based on year of birth, sex, neighborhood income, and rural/urban residence. Data analysis was performed from August 6, 2022, to August 21, 2023.

Exposure

Diagnosis of an IMID, identified using algorithms based on diagnostic codes, procedures, and specialist visits.

Main Outcome and Measure

The main outcome was estimated age- and sex-standardized incidence of VTE. Proportional cause-specific hazard models compared the risk of VTE in people with and without IMIDs. Death was a competing risk. Models adjusted for history of VTE, 2 or more doses of a COVID-19 vaccine 14 or more days prior to COVID-19 diagnosis, and the Charlson Comorbidity Index. Routinely collected health data were used, so the hypothesis tested was formulated after data collection but prior to being granted access to data.

Results

The study included 28 440 individuals (16 741 [58.9%] female; 11 699 [41.1%] male) with an IMID diagnosed prior to first COVID-19 diagnosis, with a mean (SD) age of 52.1 (18.8) years at COVID-19 diagnosis. These individuals were matched to 126 437 controls without IMIDs. The incidence of VTE within 6 months of COVID-19 diagnosis among 28 440 individuals with an IMID was 2.64 (95% CI, 2.23-3.10) per 100 000 person-days compared with 2.18 (95% CI, 1.99-2.38) per 100 000 person-days among 126 437 matched individuals without IMIDs. The VTE risk was not statistically significantly different among those with vs without IMIDs (adjusted hazard ratio, 1.12; 95% CI, 0.95-1.32).

Conclusions and Relevance

In this retrospective population-based cohort study of individuals with IMIDs following COVID-19, individuals with IMIDs did not have a higher risk of VTE compared with individuals without an IMID. These data provide reassurance to clinicians caring for individuals with IMIDs and COVID-19.

Effectiveness of Tofacitinib for Hospitalized Patients with Acute Severe Ulcerative Colitis: Case Series

BACKGROUND

Treatment options for acute severe ulcerative colitis (ASUC) are limited. Tofacitinib, an approved treatment for moderate to severe ulcerative colitis, could be a potential rescue therapy for ASUC given its rapid onset of action.

OBJECTIVE

To evaluate the effectiveness of tofacitinib in hospitalized patients with ASUC refractory to standard therapy in a real-world setting.

METHODS

Retrospective observational study of hospitalized adult patients with ASUC treated with tofacitinib between January 2019 and September 2020 at five Canadian centers. We extracted patient demographics, clinical status, biomarkers (C-reactive protein and fecal calprotectin), endoscopic findings, and colectomy-free rate at admission, 30 days, 90 days, and 6 months after tofacitinib initiation.

RESULTS

Eight patients with symptoms refractory to standard rescue therapy (corticosteroids ± infliximab if infliximab-naïve prior to admission) were treated with tofacitinib. During index hospitalization, clinical response was observed in 5/8 patients. The median time to discharge post-tofacitinib initiation was 5 days (IQR 5.0-6). At 30 and 90 days, all five responders were in clinical remission. At 6 months, only 3/5 responders remained in clinical remission. The colectomy-free rate was 37.5% during the follow-up period (two colectomies occurred within 30 days; one occurred within 90 days). No drug-related adverse reaction occurred.

CONCLUSION

In this small case-series, tofacitinib was an effective rescue therapy in patients with refractory ASUC. These findings need to be evaluated in a randomized controlled trial.

Strategies to Distinguish Perianal Fistulas Related to Crohn's Disease From Cryptoglandular Disease: Systematic Review With Meta-Analysis

BACKGROUND

Management of perianal fistulas differs based on fistula type. We aimed to assess the ability of diagnostic strategies to differentiate between Crohn's disease (CD) and cryptoglandular disease (CGD) in patients with perianal fistulas.

METHODS

We performed a diagnostic accuracy systematic review and meta-analysis. A systematic search of electronic databases was performed from inception through February 2021 for studies assessing a diagnostic test's ability to distinguish fistula types. We calculated weighted summary estimates with 95% confidence intervals for sensitivity and specificity by bivariate analysis, using fixed effects models when data were available from 2 or more studies. The Quality Assessment of Diagnostic Accuracy Studies tool was used to assess study quality.

RESULTS

Twenty-one studies were identified and included clinical symptoms (2 studies; n=154), magnetic resonance imaging (MRI) characteristics (3 studies; n=296), ultrasound characteristics (7 studies; n=1003), video capsule endoscopy (2 studies; n=44), fecal calprotectin (1 study; n=56), and various biomarkers (8 studies; n=440). MRI and ultrasound characteristics had the most robust data. Rectal inflammation, multiple-branched fistula tracts, and abscesses on pelvic MRI and the Crohn's ultrasound fistula sign, fistula debris, and bifurcated fistulas on pelvic ultrasonography had high specificity (range, 80%-95% vs 89%-96%) but poor sensitivity (range, 17%-37% vs 31%-63%), respectively. Fourteen of 21 studies had risk of bias on at least 1 of the Quality Assessment of Diagnostic Accuracy Studies domains.

CONCLUSIONS

Limited high-quality evidence suggest that imaging characteristics may help discriminate CD from CGD in patients with perianal fistulas. Larger, prospective studies are needed to confirm these findings and to evaluate if combining multiple diagnostic tests can improve diagnostic sensitivity.

Pancolonic Dye Spray Chromoendoscopy to Detect and Resect Ill-Defined Neoplastic Lesions in Colonic Inflammatory Bowel Disease

Background

Pancolonic dye spray chromoendoscopy (DCE) is used as an adjunct to white light endoscopy (WLE) to enhance the detection and delineation of ill-defined neoplastic (dysplastic) lesions in persons with colonic inflammatory bowel diseases (cIBD). We evaluated the utility of DCE as follow-up to high-definition WLE (HD-WLE) to "unmask" and/or facilitate endoscopic resection of neoplastic lesions.

Methods

We retrospectively studied persons with cIBD who underwent DCE as follow-up to HD-WLE between 2013 and 2020. We describe neoplastic findings and management during HD-WLE and DCE exams and report outcomes from post-DCE surveillance exams.

Results

Twenty-four persons were studied (mean age 56.7 ± 13.8 years, 50.0% male, 70.8% ulcerative colitis, mean disease duration 18.0 ± 11.0 years). Overall, 32 visible neoplastic lesions were unmasked during DCE, of which 24 were endoscopically resected. DCE facilitated the diagnosis of two cancers. Among 17 persons referred for evaluation of "invisible" neoplasia (detected in non-targeted biopsies) during HD-WLE, DCE identified neoplastic lesions at the same site in eight persons and a different site in four persons. Among seven persons referred for ill-defined visible neoplasia, DCE facilitated complete endoscopic resection in four individuals, whereas two individuals required colectomy for a diagnosis of cancer. Among 19 individuals with post-DCE surveillance, five developed new visible neoplastic lesions, including one high-grade neoplasia which was completely resected.

Conclusions

In our cohort, DCE aided in unmasking invisible neoplasia and facilitated endoscopic resection of ill-defined neoplasia, suggesting that it is a useful surveillance tool in selected persons with cIBD. Large prospective studies are needed to validate these findings.

Examination Under Anesthesia May Not Be Universally Required Prior to Anti-TNF Therapy in Perianal Crohn's Disease: A Comparative Cohort Study

BACKGROUND

Multidisciplinary care involving exam under anesthesia (EUA) and tumor necrosis factor (TNF) inhibitors is recommended for perianal Crohn's disease. However, the impact of this combined approach is not well established.

METHODS

We performed a comparative cohort study between 2009 and 2019. Patients with perianal Crohn's disease treated with EUA before anti-TNF therapy (combined modality therapy) were compared with anti-TNF alone. The primary outcome was fistula closure assessed clinically. Secondary outcomes included subsequent local surgery and fecal diversion. Multivariable analysis adjusted for abscesses, concomitant immunomodulators, and time to anti-TNF initiation was performed.

RESULTS

Anti-TNF treatment was initiated 188 times in 155 distinct patients: 66 (35%) after EUA. Abscesses (50% vs 15%; P < .001) and concomitant immunomodulators (64% vs 50%; P = .07) were more common in the combined modality group, while age, smoking status, disease duration, and intestinal disease location were not significantly different. Combined modality therapy was not associated with higher rates of fistula closure at 3 (adjusted odds ratio [aOR], 0.7; 95% confidence interval [CI], 0.3-1.8), 6 (aOR, 0.8; 95% CI, 0.4-2.0) and 12 (aOR, 1.0; 95% CI, 0.4-2.2) months. After a median follow-up of 4.6 (interquartile range, 5.95; 2.23-8.18) years, combined therapy was associated with subsequent local surgical intervention (adjusted hazard ratio, 2.2; 95% CI, 1.3-3.6) but not with fecal diversion (adjusted hazard ratio, 1.3; 95% CI, 0.45-3.9). Results remained consistent when excluding patients with abscesses and prior biologic failure.

CONCLUSIONS

EUA before anti-TNF therapy was not associated with improved clinical outcomes compared with anti-TNF therapy alone, suggesting that EUA may not be universally required. Future prospective studies controlling for fistula severity are warranted.

Surgery and the Subtype of Inflammatory Bowel Disease Impact the Risk of Venous Thromboembolism After Hospital Discharge

BACKGROUND

Surgery for inflammatory bowel disease (IBD) is associated with an increased risk of venous thromboembolism (VTE) during hospitalization. It is unclear whether this association persists after hospital discharge.

AIMS

We assessed the association between surgery and VTE following hospital discharge in IBD.

METHODS

We conducted a population-based cohort study between 2002 and 2016 in Ontario, Canada. Adults with IBD hospitalized for ≥ 72 h who underwent an intra-abdominal surgery were compared to hospitalized, nonsurgical IBD patients. Multivariable Cox proportional hazard models were used to compare VTE risk within 12 months of discharge.

RESULTS

A total of 80,445 hospital discharges were analyzed: 60% Crohn's disease (CD) and 40% ulcerative colitis (UC). The median time to VTE was three times longer for nonsurgical patients with CD and 1.6 times longer for nonsurgical patients with UC. Compared with nonsurgical patients, surgery for CD was associated with a lower cumulative risk of VTE in the 2 weeks after discharge and persisted through to 12 months after discharge (adjusted HR 0.24; 95% CI 0.15-0.40). In contrast, urgent surgery for UC was associated with an increased risk of VTE. The increased risk was greatest at 2 weeks after discharge (aHR, 1.80; 95% CI 1.26-2.57) and declined progressively over the course of 12 months.

CONCLUSIONS

Surgery was associated with a greater risk of VTE after hospital discharge in UC but not CD. In patients with UC who have undergone urgent surgery, healthcare providers should consider an extended period of prophylaxis after hospital discharge.

Fecal Diversion for Perianal Crohn Disease in the Era of Biologic Therapies: A Multicenter Study

BACKGROUND

The natural history of perianal Crohn disease (PCD) after fecal diversion in the era of biologics is poorly understood. We assessed clinical and surgical outcomes after fecal diversion for medically refractory PCD and determined the impact of biologics.

METHODS

We performed a retrospective, multicenter study from 1999 to 2020. Patients who underwent fecal diversion for refractory PCD were stratified by diversion type (ostomy with or without proctectomy). Times to clinical and surgical outcomes were estimated using Kaplan-Meier methods, and the association with biologics was assessed using multivariable Cox proportional hazards models.

RESULTS

Eighty-two patients, from 3 academic institutions, underwent a total of 97 fecal diversions: 68 diversions without proctectomy and 29 diversions with proctectomy. Perianal healing occurred more commonly after diversion with proctectomy than after diversion without proctectomy (83% vs 53%; P = 0.021). Among the patients who had 68 diversions without proctectomy, with a median follow-up of 4.9 years post-diversion (interquartile range, 1.66-10.19), 37% had sustained healing, 31% underwent surgery to restore bowel continuity, and 22% underwent proctectomy. Ostomy-free survival occurred in 21% of patients. Biologics were independently associated with avoidance of proctectomy (hazard ratio, 0.32; 95% confidence interval, 0.11-0.98) and surgery to restore bowel continuity (hazard ratio, 3.10; 95% confidence interval, 1.02-9.37), but not fistula healing.

CONCLUSIONS

In this multicenter study, biologics were associated with bowel restoration and avoidance of proctectomy after fecal diversion without proctectomy for PCD; however, a minority of patients achieved sustained fistula healing after initial fecal diversion or after bowel restoration. These results highlight the refractory nature of PCD.

Epidemiology and Natural History of Perianal Crohn's Disease: A Systematic Review and Meta-Analysis of Population-Based Cohorts

BACKGROUND AND AIMS

Perianal Crohn's disease (pCD) is a potentially severe phenotype of CD. We conducted a systematic review with meta-analysis to estimate cumulative incidence, risk factors, and outcomes of pCD in population-based cohort studies.

METHODS

Through a systematic literature review through March 1, 2021, we identified population-based inception cohort studies reporting cumulative incidence of perianal disease (primarily abscess and/or fistula) in patients with CD. We estimated the cumulative incidence of pCD at presentation and 1-, 5-, and 10-year follow-up, and risk factors for perianal disease and outcomes including risk of major (bowel resection, proctectomy, ostomy) and minor perianal (incision and drainage, seton placement, etc.) surgery.

RESULTS

In 12 population-based studies, prevalence of pCD was 18.7% (95% confidence interval [CI], 12.5%-27.0%) with 1-, 5-, and 10-year risk of perianal disease being 14.3% (95% CI, 7.9%-24.6%), 17.6% (95% CI, 11.3%-26.5%), and 18.9% (95% CI, 15.0%-23.4%), respectively. Approximately 11.5% of patients (95% CI, 6.7%-19.0%) had perianal disease at or before CD diagnosis. Colonic disease location and rectal involvement were associated with higher risk of pCD. Overall, 63.3% of patients (95% CI, 53.3-72.3) required minor perianal surgery and 6.4% of patients (95% CI, 1.8%-20.6%) required major abdominal surgery for pCD. Use of biologic therapy for pCD is common and has steadily increased throughout the years.

CONCLUSIONS

Approximately 1 in 5 patients with CD develops perianal disease within 10 years of CD diagnosis, including 11.5% who have perianal disease at presentation. Approximately two-thirds of patients require perianal surgery, with a smaller fraction requiring major abdominal surgery.

Inflammatory Bowel Disease Increases the Risk of Venous Thromboembolism in Children: A Population-Based Matched Cohort Study

BACKGROUND AND AIMS

Although venous thromboembolism [VTE] is a well-known complication of inflammatory bowel disease [IBD] in adults, limited data exist on the risk in children. We report the incidence of VTE among children with and without IBD.

METHODS

We conducted a matched cohort study within a distributed network of population-based Canadian provincial health administrative databases. Children <16 years diagnosed with IBD were identified using validated algorithms from administrative data in Alberta, Manitoba, Nova Scotia, Ontario and Québec and compared to age- and sex-matched children without IBD. Hospitalizations for VTE within 5 years of IBD diagnosis were identified. Generalized linear mixed-effects models were used to pool province-specific incidence rates and incidence rate ratios [IRR] with 95% confidence intervals [CI]. Hazard ratios [HR] from Cox proportional hazards models were pooled with fixed-effects meta-analysis.

RESULTS

The 5-year incidence of VTE among 3593 children with IBD was 31.2 [95% CI 23.7-41.0] per 10 000 person-years [PY] compared to 0.8 [95% CI 0.4-1.7] per 10 000 PY among 16 289 children without IBD [unadjusted IRR 38.84, 95% CI 16.59-90.83; adjusted HR 22.91, 95% CI 11.50-45.63]. VTE was less common in Crohn's disease than ulcerative colitis [unadjusted IRR 0.47, 95% CI 0.27-0.83; adjusted HR 0.52, 95% CI 0.29-0.94]. The findings were similar for deep vein thrombosis and pulmonary embolism when comparing children with and without IBD.

CONCLUSIONS

The risk of VTE is much higher in children with IBD than controls without IBD. While the absolute risk is low, we found a higher incidence rate than previously described in the pediatric literature.Conference Presentation: An abstract based on the data included in this paper was presented at Canadian Digestive Diseases Week [Montréal, Canada] in March 2020.

A74 INCREASING RATES OF CT IMAGING IN THE EMERGENCY DEPARTMENT AMONG PATIENTS WITH INFLAMMATORY BOWEL DISEASE

Background

Computed tomography (CT) imaging of the abdomen is often performed in the emergency department (ED) to exclude urgent pathology in patients with Inflammatory Bowel Disease (IBD). However, concerns over excessive radiation exposure from repeated use have led to expert consensus guidelines advising against CT imaging unless there is suspicion of complications (obstruction, perforation, abscess) or a non-IBD cause for symptoms.

Aims

Our study aimed to determine trends in abdominal CT utilization and findings among patients with IBD in the ED.

Methods

We performed a retrospective cohort study between 01/01/2009 and 31/12/2018 at a single academic center. We identified ED encounters for adults (age ≥17 years) with a pre-existing diagnosis of IBD from our institutional database and determined the proportion resulting in an abdominal CT scan within 72 hours of presentation. IBD subtypes were classified based on ICD-10 claims: K50.90* for Crohn’s disease (CD), K51.90* for Ulcerative colitis (UC) and IBD undifferentiated (IBDU) for patients with both claims. A time trend analysis was performed using a generalized linear model that assumed a Poisson distribution. CT scans were classified according to the dominant imaging finding. For this part we excluded studies performed within 1-month of surgery or those re-assessing a known abscess or malignancy.

Results

A total of 14783 encounters were identified. Among these encounters 3000 CT scans were performed: 2000 for patients with CD (21.9%), 652 for UC (16.5%) and 348 for IBDU (20.4%). The rates of CT utilization significantly increased by 2.7% (95% CI, 1.2–4.3; p=0.0004) in patients with CD, by 4.2% (95% CI, 1.7–6.7; p=0.0009) in patients with UC and by 6.3% in patients with IBDU (95% CI, 2.5–10.0; p=0.0011). Among the eligible CT scans performed for CD, the following dominant findings were reported: normal (25%), inflammation (23%), obstruction (23%), penetrating (18%) and unrelated to IBD (8.6%). In contrast, the following findings for patients with UC were reported: normal (20%), inflammation (39%), obstructive (19%), penetrating (8%) and unrelated to IBD (15%).

Conclusions

In this single center study, a steady increase in CT utilization in the ED was observed in patients with IBD. Interestingly, only a small proportion of the CT scans demonstrated urgent findings. Future studies are required to determine the factors that contribute to the ongoing increase in CT utilization in this patient population.

Funding Agencies

None

A158 THE EFFECTIVENESS AND SAFETY OF HYPERBARIC OXYGEN THERAPY IN INFLAMMATORY BOWEL DISEASE AND ITS ASSOCIATED CONDITIONS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

Hyperbaric oxygen therapy (HBOT) corrects tissue hypoxia, mobilizes stem cells and has immunomodulatory effects, all of which are key mechanisms for healing wounds. A number of studies have suggested that HBOT may be effective for healing inflammatory bowel disease (IBD).

Aims

Our systematic review aimed to quantify the effectiveness and safety of HBOT in IBD and its associated conditions.

Methods

We performed a proportional meta-analysis. MEDLINE, EMBASE, Web of Knowledge and The Cochrane Central Register of Controlled Trials were systematically searched from inception through November 2020 with no language restriction. We included randomized controlled studies, cohort studies and case series that contained a minimum of three patients and reported effectiveness and/or safety outcomes for HBOT in patients with IBD. Studies were stratified by IBD phenotype and weighted summary estimates with 95% confidence intervals (CI) were calculated for clinical response and remission using random-effects models. Study quality was assessed using the Cochrane risk-of-bias tool for randomized trials and a modified version of the National Institutes of Health (NIH) checklist for observational studies.

Results

Nineteen studies met our study criteria: 3 randomized controlled trials and 16 case series. The studies reported outcomes for luminal ulcerative colitis (UC) (n=373), luminal Crohn’s disease (CD) (n=250), enterocutaneous fistulae (ECF) (n=21), perianal CD (n=115), pouch disorders (n=60), pyoderma gangrenosum (PG) (n=5) and perianal sinus/metastatic CD (n=7). Rates of clinical response were 86% (95% CI, 66–95%) for luminal UC, 86% (95% CI, 81–90%) for luminal CD, 85% (95% CI, 61–95%) for ECF, 80% (95% CI, 70–87%) for perianal CD, 65% (95% CI, 52–76%) for pouch disorders, 92% (95% CI, 38–99%) for PG and 79% (95% CI, 36–96%) for perianal sinus/metastatic CD. Rates of clinical remission were 87% (95% CI, 10–100%) for luminal UC, 88% for luminal CD (95% CI, 46–98%), 50% for ECF (95% CI, 12–88%), 64% (95% CI, 52–75%) for perianal CD, 31% (95% CI, 16–50%) for pouch disorders, 92% (95% CI, 38–100%) for PG and 65% (95% CI, 10–97%) for perianal sinus/metastatic CD. Of the ten studies that reported on safety of HBOT, 19 patients (10.5%) had minor adverse events and no major event was reported. Study quality was low in the majority of studies due to an absence of comparator arms, inadequate description of interventions, and poorly defined outcomes.

Conclusions

Limited high-quality evidence suggest that HBOT is safe and associated with high rates of clinical response and remission for luminal IBD, perianal CD and pouch disorders. A well-designed large multicenter randomized controlled trial is warranted to confirm the benefit of HBOT in IBD.

doi:10.17605/osf.io/gpz6d

Funding Agencies

None

A194 A POSSIBLE ASSOCIATION BETWEEN SECUKINUMAB AND NEW-ONSET INFLAMMATORY BOWEL DISEASE: A CASE SERIES

Background

Secukinumab is a monoclonal antibody targeting interleukin-17A and is commonly used for managing autoimmune diseases such as, psoriasis, psoriatic arthritis, and ankylosing spondylitis. Prior studies have suggested that anti-IL17 therapy may worsen symptoms in patients with pre-existing inflammatory bowel disease (IBD). However, it remains unclear if secukinumab is associated with new-onset IBD or in provoking a flare of previously quiescent IBD.

Aims

We evaluated patients referred to our IBD clinic who developed intestinal inflammation after starting secukinumab for the management of autoimmune diseases.

Methods

We performed a retrospective, observational study at a single tertiary care center between 2017 and 2020. Patients referred to our IBD clinic who developed intestinal inflammation after starting secukinumab were included. We excluded patients with an established pre-existing diagnosis of IBD and patients who had positive stool testing for infectious organisms. Patient demographics, disease characteristics, distribution of intestinal inflammation and clinical outcomes were assessed. The pathology slides were reinterpreted by a single pathologist with a specialty in gastroenterology to determine the histologic characteristics of the inflammation.

Results

A total of 8 patients developed gastrointestinal symptoms after starting secukinumab: 4 (50%) males with a median age of 42.5 (IQR: 35–50 years old). Secukinumab was initiated for psoriasis in 3 (37.5%) patients, psoriatic arthritis in 2 (25%) patients, ankylosing spondylitis in 2 (25%) patients and juvenile idiopathic arthritis in 1 (12.5%) patient. The median time of onset for gastrointestinal symptoms after starting secukinumab was 7 months (IQR: 4–15 months). Of the patients who underwent testing for inflammatory biomarkers, the median CRP was 25.5 (IQR 25.4–34.2). Endoscopic disease distribution involved the colon in 5 (62.5%) patients and the ileum and colon in 3 (37.5%) patients. In this series of patients, the histologic characteristics demonstrated three patterns of colitis: IBD-like (ulcerative colitis or Crohn’s disease) in 6 (75%) patients based on mucosal granulomas and/or chronic inflammatory changes, MMF-like histology in 1 (12.5%) patient, characterized by an abundance of intraepithelial eosinophils in the lamina propria and numerous crypt apoptotic bodies, and finally active colitis in 1 (12.5%) patient characterized by an absence of chronic mucosal injury or granulomas. The treatment for these patients was cessation of secukinumab and initiating alternative therapies with close clinical monitoring.

Conclusions

In this small case series, Secukinumab was temporally associated with the development of gastrointestinal inflammation. Further larger studies are required to confirm this association and to determine if IL-17 contributes to the pathogenesis of IBD.

Funding Agencies

None

A159 ANTI-TUMOR NECROSIS FACTOR THERAPY PERSISTENCE IN PATIENTS WITH PERIANAL CROHN’S DISEASE AND LUMINAL CROHN’S DISEASE: A COMPARATIVE COHORT STUDY

Background

Anti-tumor necrosis factor therapy has revolutionized the management of Crohn’s disease. Despite its effectiveness, a substantial proportion of patients discontinue therapy over time. Evaluating drug persistence rates reveals a real-world pattern of biologic use. Perianal Crohn’s disease (PCD) is considered one of the most difficult phenotypes of Crohn’s disease (CD) to treat. Therefore, we hypothesized that patients with PCD have a shorter biologic persistence time due to refractory disease.

Aims

Our aim is to compare drug persistence rates of anti-TNF therapy between PCD and LCD patients.

Methods

We performed a retrospective, comparative cohort study at a tertiary care center between Nov 2019 and July 2020. Patients with CD were identified by our institutional data-base, using the ICD-10 code K50.90. A longitudinal chart review determine anti-TNF utilization and classified patients based on luminal CD only [LCD] or PCD. Patients with PCD were matched (1:1) to patients with LCD based on sex, age, and year of first anti-TNF initiation within 5 years. Time to discontinuation of anti-TNF therapy was estimated by Kaplan-Meier methods and compared between groups by Log-rank test.

Results

A total of 142 patients with PCD (55% male, 38.7 ± 13.7 years old at anti-TNF start) were matched to 142 patients with LCD (55% male, 38.7 ± 14.0 years old at anti-TNF start). The initial treatments included infliximab (67.6% vs. 57.7%) and adalimumab (32.4% vs. 42.3%) for patients with PCD and LCD respectively. Concomitant immunomodulator were used in 61.3% of patients with PCD and 54.9% of patients with LCD. The cumulative persistence of the initial anti-TNF therapy was similar between cohorts (Log rank, p = 0.633; Figure 1): mean time to discontinuation was 27.7 ± 26.8 months for patients with PCD and 26.5 ± 23.0 months for patients with LCD. The reasons for treatment discontinuation included: refractory disease (19% vs. 16%), anti-drug antibodies (6% vs. 12%), and side effects (12.7% vs. 16.2%) in patients PCD and LCD respectively. Of the patients who discontinued their first anti-TNF therapy, 36 patients (55.4%) with PCD and 42 patients (60.9%) with LCD were treated with a second anti-TNF therapy. Discontinuation of the second-line anti-TNF therapy occurred in 18 patients (50%) with PCD and 18 patients (42.9%) with LCD: mean time to discontinuation was 17.3 ± 14.3 months and 27.8 ± 28.8 months respectively.

Conclusions

In this single-center, observational study a substantial percentage of patients discontinue anti-TNF therapy overtime, and there does not appear to be a difference between patients with PCD and LCD.

Funding Agencies

None

Risk of Venous Thromboembolism After Hospital Discharge in Patients With Inflammatory Bowel Disease: A Population-based Study

BACKGROUND

Inflammatory bowel disease (IBD) is associated with a high risk of venous thromboembolism (VTE) during hospitalization. It is unclear if this association persists after discharge. We aimed to assess the incidence of postdischarge VTE in IBD patients and to determine if IBD is associated with increased VTE risk.

METHODS

We performed a population-based cohort study between 2002 and 2016 using Ontario health administrative data sets. Hospitalized (≥72 hours) adults with IBD were stratified into nonsurgical and surgical cohorts and matched on propensity score to non-IBD controls. Time to postdischarge VTE was assessed by Kaplan-Meier methods, and VTE risk was assessed by Cox proportional hazard models.

RESULTS

A total of 81,900 IBD discharges (62,848 nonsurgical and 19,052 surgical) were matched to non-IBD controls. The cumulative incidence of VTE at 12 months after discharge was 2.3% for nonsurgical IBD patients and 1.6% for surgical IBD patients. The incidence increased in the nonsurgical IBD cohort by 4% per year (incidence rate ratio, 1.04; 95% CI, 1.02-1.05). In our propensity score-matched analysis, the risk of VTE at 1-month postdischarge was greater in nonsurgical IBD patients (hazard ratio [HR], 1.72; 95% CI, 1.51-1.96) and surgical patients with ulcerative colitis (HR, 1.68; 95% CI, 1.16-2.45) but not surgical patients with Crohn's disease. These trends persisted through 12 months.

CONCLUSIONS

Nonsurgical IBD patients and surgical patients with ulcerative colitis are 1.7-fold more likely to develop postdischarge VTE than non-IBD patients. These findings support the need for increased vigilance and consideration of thromboprophylaxis in this population.

The risk of diarrhea and colitis in patients with lung cancer treated with immune checkpoint inhibitors: a systematic review and meta-analysis

Background

Immune checkpoint inhibitors (icis), including inhibitors of PD-1, PD-L1, and ctla-4, are relatively novel therapies for lung cancer, although their use might be limited by gastrointestinal toxicity. The aim of the present study was to determine the risk of diarrhea and colitis associated with icis in lung cancer and the rates of discontinuation because of those toxicities.

Methods

Electronic databases were searched for prospective trials reporting the risk of diarrhea and colitis in patients with lung cancer treated with PD-1, PD-L1, and ctla-4 inhibitors. The incidences of diarrhea and colitis and their grades were assessed clinically using standardized reporting criteria. Pooled incidence and weighted relative risk estimates for diarrhea and colitis with 95% confidence intervals (cis) were estimated using a random effects model. The incidence of discontinuations for gi toxicity was also calculated.

Results

Twenty-seven studies were included: sixteen studies with PD-1 inhibitors, nine studies with PD-L1 inhibitors, and four studies combining PD-based strategies with ctla-4 inhibitors. The incidence of all-grade diarrhea was 9.1% (95% ci: 7.8% to 10.5%) for anti-PD-1 therapy and 11.0% (95% ci: 7.5% to 14.5%) for anti-PD-L1 therapy. The incidence of all-grade colitis was 0.9% (95% ci: 0.4% to 1.3%) for anti-PD-1 therapy and 0.4% (95% ci: 0.0% to 0.8%) for anti-PD-L1 therapy. The relative risk for all-grade diarrhea was higher with combination anti-PD-1 and anti-ctla-4 than with anti-PD-1 monotherapy (relative risk: 1.61; 95% ci: 1.14 to 2.29). Anti-PD-1 therapy was discontinued in 4.1% of patients with diarrhea (95% ci: 0.7% to 7.4%) and in 35.7% of those with colitis (95% ci: 0.0% to 81.1%); combination therapy was discontinued in 10.1% of patients with diarrhea (95% ci: 4.8% to 15.4%) and in 39.9% of those with colitis (95% ci: 3.9% to 75.9%).

Conclusions

Diarrhea is a relatively frequently encountered gi toxicity when ici therapy is used in lung cancer treatment. Colitis is less frequently encountered, although when it does occur, it often results in therapy discontinuation.

Absence of Day 3 Steroid Response Predicts Colitis-Related Complications and Colectomy in Hospitalized Ulcerative Colitis Patients

BACKGROUND AND AIMS

Rates and predictors of complications among hospitalized ulcerative colitis (UC) patients requiring high-dose corticosteroids have not been well-characterized, especially in the era of biologics.

METHODS

We retrospectively studied consecutive UC admitted for a colitis flare requiring high-dose corticosteroids between April 2006 and December 2016. We evaluated rates and determinants of serious in-hospital complications (colitis-related complications, systemic complications, peri-operative complications and death) and colectomy. We performed multivariable logistic regression analysis to assess the independent association between day 3 steroid response and the risk of incurring in-hospital complications and colectomy.

RESULTS

Of 427 consecutive admissions, serious in-hospital complications occurred in 87 cases (20%), while colitis-related complications occurred in 47 cases (11%). There were significantly fewer colitis-related complications during the 2012 to 2016 period as compared to the 2006 to 2011 period (7% versus 16%, P < 0.01), but significantly more systemic complications (16% versus 5%, P = 0.001). In-hospital colectomy occurred in 50 hospitalizations (12%). Day 3 steroid response was achieved in 167 hospitalizations (39%). Day 3 steroid nonresponse was significantly associated with colitis-related complications among males (adjusted odds ratio [aOR] 8.22, 95% confidence interval [CI] 1.77 to 38.17), but not among females (aOR 1.39, 95% CI 0.54 to 3.60). Older age, C. difficile infection and admission to a non-gastroenterology service were also associated with a higher risk of in-hospital complications. Day 3 steroid nonresponse was significantly associated with in-hospital colectomy (aOR 10.10, 95% CI 3.56 to 28.57).

CONCLUSION

In our series of UC hospitalizations for a colitis flare, absence of day 3 steroid response was associated with an increased risk of colitis-related complications among males and of in-hospital colectomy. Clinicians should recognize the importance of early steroid response as a marker to guide the need for treatment optimization.

Tumor Necrosis Factor Inhibitors May Have Limited Efficacy for Complex Perianal Fistulas Without Luminal Crohn's Disease

BACKGROUND

Complex perianal fistulas occurring in the absence of luminal inflammation (isolated perianal disease, IPD) may represent a specific phenotype of Crohn's disease (CD).

AIM

We assessed the effectiveness of tumor necrosis factor (TNF)-antagonists in patients with IPD compared to those with perianal CD (PCD) with luminal inflammation.

METHODS

Patients were identified through our institutional radiology database and were classified as PCD or IPD based on the presence or absence of luminal inflammation by ileocolonoscopy and abdominal enterography. Consecutive adults (> 17 years) with recurrent IPD who were treated with TNF antagonists were matched by age and gender to patients with complex PCD (1:2 ratio). Fistula remission was defined as an absence of fistula drainage. Surgery-free survival was assessed by Cox proportional hazard models.

RESULTS

Twenty-two patients with IPD treated with a TNF antagonist were compared with 44 matched patients with PCD. A similar proportion of patients with IPD and PCD were treated with concomitant immunomodulators (55% vs. 66%) and underwent examinations under anesthesia prior to therapy (36% vs. 46%). Fistula remission at 3, 6, and 12 months was lower for the IPD cohort: 9.5% versus 34%; 19% versus 39%; and 19% versus 43%. Surgical intervention after initiating anti-TNF therapy was more common for patients with IPD (HR 3.99: 95% CI, 1.62-9.83; p = 0.0026).

CONCLUSIONS

Fewer patients with IPD achieved fistula remission, and more required surgical intervention after anti-TNF therapy, suggesting that TNF antagonists may not be as effective in these patients.

Introduction of anti-TNF therapy has not yielded expected declines in hospitalisation and intestinal resection rates in inflammatory bowel diseases: a population-based interrupted time series study

OBJECTIVES

To better understand the real-world impact of biologic therapy in persons with Crohn's disease (CD) and ulcerative colitis (UC), we evaluated the effect of marketplace introduction of infliximab on the population rates of hospitalisations and surgeries and public payer drug costs.

DESIGN

We used health administrative data to study adult persons with CD and UC living in Ontario, Canada between 1995 and 2012. We used an interrupted time series design with segmented regression analysis to evaluate the impact of infliximab introduction on the rates of IBD-related hospitalisations, intestinal resections and public payer drug costs over 10 years among patients with CD and 5 years among patients with UC, allowing for a 1-year transition.

RESULTS

Relative to what would have been expected in the absence of infliximab, marketplace introduction of infliximab did not produce significant declines in the rates of CD-related hospitalisations (OR at the last observation quarter 1.06, 95% CI 0.811 to 1.39) or intestinal resections (OR 1.10, 95% CI 0.810 to 1.50), or in the rates of UC-related hospitalisations (OR 1.22, 95% CI 1.07 to 1.39) or colectomies (OR 0.933, 95% CI 0.54 to 1.61). The findings were similar among infliximab users, except that hospitalisation rates declined substantially among UC patients following marketplace introduction of infliximab (OR 0.515, 95% CI 0.342 to 0.777). There was a threefold rise over expected trends in public payer drug cost among patients with CD following infliximab introduction (OR 2.98,95% CI 2.29 to 3.86), suggesting robust market penetration in this group, but no significant change among patients with UC (OR 1.06, 95% CI 0.955 to 1.18).

CONCLUSIONS

Marketplace introduction of infliximab has not yielded anticipated reductions in the population rates of IBD-related hospitalisations or intestinal resections, despite robust market penetration among patients with CD. Misguided use of infliximab in CD patients and underuse of infliximab in UC patients may largely explain our study findings.

Strategies to Optimize Anti-tumor Necrosis Factor Therapy for Perianal Fistulizing Crohn's Disease: A Systematic Review

Tumor necrosis factor (TNF) antagonists are considered the cornerstone therapy for fistulizing perianal Crohn's disease (PCD), yet a substantial proportion of patients fail to achieve healing. Therefore, we reviewed the evidence for strategies to enhance the efficacy of TNF antagonists for PCD. A systematic search of electronic databases through July 2018 was performed to identify studies that assessed the effectiveness of TNF antagonists combined with another medical or surgical intervention for PCD; or assessed the association between anti-TNF serum concentrations and fistula healing. Twelve studies compared anti-TNF therapy alone versus a combined approach: four with surgery, three with antibiotics, and five with immunomodulators. Only two studies, both with antibiotics, were rated high quality. The addition of antibiotics to anti-TNF therapy resulted in significantly higher rates of fistula response and healing in one study, and a trend toward reduction in fistula drainage in the other. Three of four studies found higher rates of fistula healing when surgery was combined with TNF antagonists. In contrast, one of five studies found a trend toward higher rates of fistula healing in patients treated concomitantly with immunomodulators. Five observational studies assessed the association between anti-TNF concentration and fistula healing. Higher infliximab serum concentrations were consistently associated with fistula healing. In conclusion, few high-quality studies assessing strategies to optimize anti-TNF therapy for PCD exist. Although antibiotics, possibly surgery, and higher serum infliximab concentrations appear to improve fistula healing, future prospective studies are needed to determine the optimal treatment strategy.

History of malignancy and relevant symptoms may predict a positive computed tomography enterography in obscure gastrointestinal bleeds

BACKGROUND AND AIM

This study aimed to assess the clinical utility of computed tomography enterography (CTE) and identify factors associated with a diagnostic CTE for patients with obscure gastrointestinal bleeding (OGIB).

METHODS

A retrospective observational study was performed at a Canadian tertiary care center from 2005 to 2015. A total of 138 patients underwent a CTE for OGIB. Univariate and multivariate logistic regressions were performed to determine factors associated with a diagnostic CTE. A highly sensitive clinical rule was then developed to help identify OGIB patients for whom a CTE may be beneficial in their clinical work-up.

RESULTS

A possible bleeding source was identified in 30 (22%) cases. The presence of abdominal or constitutional symptoms as well as history of colorectal cancer was significantly associated with a positive CTE in univariate and multivariate analyses (P < 0.05). A positive CTE could be predicted based on the presence of abdominal or constitutional symptoms and history of colorectal cancer with 90% sensitivity (95% CI 74-98%) in our population.

CONCLUSION

CTE identified a possible source of OGIB in one in five cases. In patients with the presence of abdominal or constitutional symptoms and a personal history of colorectal cancer, CTE may contribute to their diagnostic work-up.

A clinical predictive model for post-hospitalisation venous thromboembolism in patients with inflammatory bowel disease

BACKGROUND

Patients with inflammatory bowel disease (IBD) are at increased risk of venous thromboembolism (VTE) during hospitalisation and potentially post-discharge.

AIMS

To determine the incidence and risk factors for post-discharge VTE in IBD patients and create a point of care predictive model to assess VTE risk.

METHODS

Hospitalised IBD patients were identified from our institutional discharge database between 2009 and 2016, and were assessed for VTE by chart review. Risk factors for VTE within 3 months of discharge were determined by univariable and multivariable logistic regression. A point of care model was created using variables from the univariate analysis with P < 0.05, and internally validated by bootstrap methods.

RESULTS

Sixty-six of 2161 eligible discharges (3%) were associated with VTE within 6 months of hospitalisation. The median time to event was 37 days (range 3-182 days). On multivariable analysis age >45 years (OR 3.76; 95% CI 1.80-7.89) and multiple admissions (OR 2.62; 95% CI 1.34-5.11) were independently associated with VTE risk. Our final model incorporated age >45 years, multiple admissions, intensive care unit admission, length of admission >7 days and central catheter and was able to discriminate between discharges associated with and without VTE (optimism-corrected c-statistic, 0.70; 95% CI 0.58-0.77). By limiting treatment to a high-risk group, extended thromboprophylaxis could be avoided in 92% of discharges with a miss rate of 1.6% (32/1982 discharges).

CONCLUSION

Patients with IBD remain at risk of VTE after hospital discharge. Our model may help clinicians stratify which patients will benefit most from extended thrombophrophylaxis.

Clinical Benefit of Capsule Endoscopy in Crohn's Disease: Impact on Patient Management and Prevalence of Proximal Small Bowel Involvement

BACKGROUND

Ileocolonoscopy and computed tomography (CT) or magnetic resonance (MR) enterography (CTE/MRE) are utilized to evaluate patients with small bowel (SB) Crohn's disease (CD). The purpose of our study was to estimate the impact of capsule endoscopy (CE) on patient management after clinical assessment, ileocolonoscopy, and CTE/MRE.

METHODS

We prospectively analyzed 50 adult CD patients without strictures at clinically indicated ileocolonoscopy and CTE/MRE exams. Providers completed pre- and post-CE clinical management questionnaires. Pre-CE questionnaire assessed likelihood of active SBCD and management plan using a 5-point level of confidence (LOC) scales. Post-CE questionnaire assessed alteration in management plans and contribution of CE findings to these changes. A change of ≥2 on LOC scale was considered clinically meaningful.

RESULTS

Of the 50 patients evaluated (60% females), median age was 38 years, median disease duration was 3 years, and median Crohn's Disease Activity Index (CDAI) score was 238 points. All CTE/MRE studies were negative for proximal disease. CE detected proximal disease in 14 patients (28%) with a median Lewis score of 215 points. CE findings altered management in 17 cases (34%). The most frequent provider-perceived benefits of CE were addition of new medication (29%) and exclusion of active SB mucosal disease (24%).

CONCLUSION

CE is a safe imaging modality that alters clinical management in patients with established SBCD by adding incremental information not available at ileocolonoscopy and cross-sectional enterography.

Systematic review with meta-analysis: the impact of Clostridium difficile infection on the short- and long-term risks of colectomy in inflammatory bowel disease

BACKGROUND

Clostridium difficile infection (CDI) is associated with increased mortality in inflammatory bowel disease (IBD), but the risk of colectomy is variable and has not been adequately studied.

AIM

To perform a systematic review and meta-analysis to assess the impact of CDI on colectomy risk in IBD.

METHODS

Multiple databases were searched systematically for observational studies reporting colectomy risk in IBD, stratified by the presence of CDI, and the duration of follow-up (short term 3 months, and long term at least 1 year). Weighted summary estimates were calculated using generalised inverse variance with random-effects model. Study quality was assessed using the Newcastle-Ottawa scale.

RESULTS

Twelve observational studies were identified and included 35 057 IBD patients with CDI, and 929 259 without CDI. CDI did not increase the short-term colectomy risk in IBD patients overall (10 studies) (OR: 1.35; 95% CI: 0.68-2.67), or in patients with ulcerative colitis (nine studies) (OR: 1.20; 95% CI: 0.39-3.76). In contrast, CDI was associated with higher long-term colectomy risk in patients with IBD overall (five studies) (OR: 2.23; 95% CI: 1.18-4.21), and in patients with ulcerative colitis (four studies) (OR: 2.96; 95% CI: 1.19-7.34). The results were stable in subgroups stratified by recruitment period, hospitalisation status and geographical location. All studies were at least of moderate quality. The results were limited in the ability to compare IBD severity and the type of anti-microbial therapy.

CONCLUSION

Based on 12 observational studies with at least moderate quality, Clostridium difficile infection appears to increase colectomy risk in IBD in the long- but not short- term.

Diagnostic Accuracy of Blood-Based Tests and Histopathology for Cytomegalovirus Reactivation in Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

BACKGROUND

It is unclear if traditional histopathology and noninvasive blood-based tests are sufficiently accurate to detect cytomegalovirus (CMV) reactivation in inflammatory bowel disease. Therefore, we assessed the diagnostic accuracy of these tests compared with immunohistochemistry (IHC) and tissue polymerase chain reaction (PCR).

METHODS

A systematic search of electronic databases was performed from inception through January 2016 for observational studies comparing diagnostic tests for CMV reactivation in inflammatory bowel disease. IHC and tissue PCR were considered reference standards and were used to evaluate the accuracy of blood-based tests and hematoxylin and eosin histopathology. Weighted summary estimates with 95% confidence intervals (CIs) were calculated using bivariate analysis.

RESULTS

Nine studies examined the accuracy of blood-based tests for predicting colonic CMV reactivation: 5 studies by pp65 antigenemia and 4 studies by blood PCR. The overall sensitivity was 50.8% (95% CI, 19.9-81.6), the specificity was 99.9% (95% CI, 99-100), and the positive predictive value was 83.8% (95% CI, 58.6-95.0). The sensitivities of pp65 and blood PCR were 39.7% (95% CI, 27.4-52.1) and 60.0% (95% CI, 46.5-73.5), respectively. Nine studies examined the sensitivity of histopathology. The overall sensitivity was 12.5% (95% CI, 3.6-21.4), 34.6% by IHC (95% CI, 13.8-55.4), and 4.7% by tissue PCR (95% CI, 1.2-17.1).

CONCLUSIONS

Although blood-based tests seem to predict colonic CMV reactivation, they are insensitive tests. Similarly, histopathology has poor sensitivity for detecting colonic CMV. In agreement with current guidelines, these tests should not replace IHC or tissue PCR for detecting CMV reactivation in inflammatory bowel disease.

Corticosteroids and Thiopurines, But Not Tumor Necrosis Factor Antagonists, are Associated With Cytomegalovirus Reactivation in Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

BACKGROUND

The association between cytomegalovirus (CMV) reactivation and individual immunosuppressive agents in inflammatory bowel disease (IBD) has not been clearly defined. Therefore, we performed a systematic review and meta-analysis to assess this association.

METHODS

Multiple electronic databases were searched systematically through July 2015 for observational studies reporting CMV reactivation (based on serum-based or tissue-based tests) in IBD patients stratified by medication exposure. We estimated summary odds ratios (ORs) and 95% confidence intervals (CI) using random-effects model. Study quality was assessed using the Newcastle-Ottawa scale.

RESULTS

Sixteen observational studies were identified. As compared with nonexposed patients, exposure to corticosteroids (CS) (12 studies, 1180 patients, 52.3% exposed; OR, 2.05; 95% CI, 1.40-2.99) and thiopurines (14 studies, 1273 patients, 24.1% exposed; OR, 1.56; 95% CI, 1.01-2.39) was associated with increased risk of CMV reactivation. In contrast, as compared with patients not exposed to tumor necrosis factor (TNF) antagonists, exposure to TNF antagonists was not associated with an increased risk of CMV reactivation (7 studies, 818 patients, 18.5% exposed; OR, 1.44; 95% CI, 0.93-2.24). The results remained stable for CS and thiopurines when the analysis was limited to hospitalized patients, and by a tissue-based diagnosis. Studies were limited in the ability to assess the impact of concomitant immunosuppressive therapy, duration of medication exposure, and disease severity.

CONCLUSIONS

On the basis of 16 observational studies, exposure to CS or thiopurines, but not TNF antagonists, was associated with an increased risk of CMV reactivation in IBD patients.

A model for identifying cytomegalovirus in patients with inflammatory bowel disease

BACKGROUND & AIMS

The presentation of cytomegalovirus (CMV) disease in patients with inflammatory bowel disease (IBD) can be similar to that of idiopathic IBD. It is a challenge to identify patients at highest risk for CMV. We investigated risk factors and generated a clinical score to identify patients with IBD at highest risk for CMV disease.

METHODS

We performed a retrospective case-control study of 68 patients with IBD (66% with ulcerative colitis, 31% with Crohn's disease, and 3% with unclassified IBD) diagnosed with CMV disease on the basis of tissue analysis from January 2005 through December 2011 at Mayo Clinic, Rochester. The patients were each matched with 3 patients with IBD and suspected CMV disease (controls). An a priori set of the most objective variables was used to create a model to identify those with CMV disease. Scores were assigned to each significant factor from the multivariable analysis. Cutoff values that identified patients with CMV with ≥85% sensitivity and specificity were selected.

RESULTS

Patients with medically refractory IBD (odds ratio [OR], 3.69; P < .001) or endoscopic ulcers (OR, 3.06; P < .001) and those treated with corticosteroids (OR, 2.95; P < .001) or immunomodulators (OR, 1.86; P = .030) but not tumor necrosis factor antagonists (OR, 1.30; P = .376) were more likely to have CMV disease than patients with IBD without these features. In a multivariable model, refractory disease, treatment with immunomodulators, and age older than 30 years were independently associated with CMV disease. Use of tumor necrosis factor antagonists was an insignificant factor even after adjustment.

CONCLUSIONS

Clinical features can identify patients with IBD at risk for CMV disease. This model may help clinicians stratify patients on the basis of risk when CMV disease is suspected.

Mixed lymphocyte reactivity against normal cells by splenic lymphocytes from tumor-bearing mice : I. Studies of vigorous immune responsiveness induced in f(1) mice by parental strain tumor cells

The establishment of an intimate connection between autoimmunity and neoplasia would require the demonstration of an experimentally induced, tumor-dependent autoimmune process. For this reason, we have studied cellular immune reactions of mice bearing a transplantable leukemia (L1210). Spleen cells from hybrid BDF₁ mice bearing the L1210 tumor (BDFt) reacted vigorously in mixed lymphocyte culture with mitomycin-treated, normal spleen cells from mice of the parental strain from which the L1210 tumor was derived (DBA/2). Spleen cells from nontumor-bearing BDF₁ mice reacted only weakly with these parental cells. The BDFt cells likewise did not respond when cultured with mitomycin-treated spleen cells from the other parental strain (C57B1/6). The vigorous mixed lymphocyte reaction (MLR) by BDFt cells against normal parental cells of the same strain as the tumor was not due to a double exposure of the reacting cells to histocompatibility antigens shared by tumor cells and normal parental cells. The response of cells from tumor-bearing F₁ mice against normal parental cells seen in these experiments suggests the possibility of the induction of an autoimmune-like process against host lymphocytes by spleen cells from leukemic mice. Theoretically such a phenomenon would considerably reduce an animal's ability to mount an immune attack against malignant cells.

Mixed lymphocyte reactivity against normal cells by splenic lymphocytes from tumor-bearing mice : ii. Studies of autoimmune-like activity in completely syngeneic and semisyngeneic systems

A possible consequence of an antilymphocytic autoimmune process would be serious impairment of an animal's ability to destroy tumor cells. One measure of autoimmune reactivity of this type would be the demonstration of cellular immune responsiveness by cells from tumor-bearing mice against syngeneic normal cells. These experiments demonstrate that spleen cells from mice bearing a lymphocytic leukemia of identical histocompatability type as the host mounted a vigorous immune response against normal syngeneic cells in a mixed lymphocyte reaction (MLR). Moreover, ascitic cells from leukemic mice responded significantly to normal syngeneic spleen cells in MLR's. The former reactions are usually much more vigorous than the responses of normal to malignant cells. These results are discussed in terms of the relationship between autoimmunity and neoplasia. Alternative explanations necessitated by the dangers involved in the interpretation of the immunology of transplantable tumors are considered.

Toll-like receptor-mediated activation of mast cells: implications for allergic disease?

Toll-like receptors have a critical role in innate immunity and host defence. However their role in allergic disease has not been studied in great detail. The presence of these receptors on mast cells opens up new possibilities concerning the role of Toll-like receptors in the pathogenesis of asthma and atopic dermatitis. The current review examines the biology of Toll-like receptors expressed on mast cells. In particular, mast cell expression of Toll-like receptors and the diverse responses observed following Toll-like receptor-mediated activation are considered. Several pathogens such as Staphylococcus aureus and respiratory syncytial virus are known to contribute to the development or maintenance of allergic disease and also express potent activators of the Toll-like receptor pathways. The importance of such interactions and the full role of pathogens in chronic allergic disease remain to be elucidated. The unusual ability of Toll-like receptor 2 activators to selectively induce leukotriene production by mast cells opens up new possibilities concerning mechanisms of disease exacerbation during infection.

Mast cell cytokine and chemokine responses to bacterial and viral infection

Mast cells have been most widely studied in the context of allergic disease but also play a critical role in host defence against bacterial infection, most elegantly demonstrated in studies using mast cell deficient w/wv mice. There is less data available concerning the role of mast cells in defence against viral pathogens, however, mast cells have been demonstrated to be a potential reservoir of infection for several pathogens, such as HIV-1 and dengue, and capable of producing mediators following challenge with a number of viral products. Traditional mast cell mediators such as histamine, protease enzymes and leukotrienes are important for effective host responses. The cytokines and chemokines produced by mast cells in response to pathogens are known to profoundly alter the nature of the innate immune response and its effectiveness in eliminating infection. Cytokine and chemokine production by mast cells is closely regulated and may occur independently of classical mast cell degranulation. Depending upon the nature of the stimulus or type of infection, a unique profile of cytokines is induced. In this review, we will examine the role and regulation of mast cell cytokines and chemokines in the context of a number of bacterial and viral infections, emphasizing the multiple receptor mechanisms used to activate mast cells. This area of research is still in its early stages and much work remains to be done. However, understanding the unique properties of resident tissue mast cells and how their cytokine responses are regulated by pathogens or pathogen products, will provide important opportunities for the therapeutic manipulation of local immune responses.

Cutting edge: distinct Toll-like receptor 2 activators selectively induce different classes of mediator production from human mast cells

Mast cells play a critical role in host defense against bacterial infection. Murine mast cells produce cytokines in response to bacterial peptidoglycan and LPS via Toll-like receptor (TLR) TLR2- and TLR4-dependent mechanisms. The expression of TLRs by human mast cells and responses to known TLR activators was examined. Human mast cells expressed mRNA for TLR1, TLR2, and TLR6 but not TLR4. Bacterial peptidoglycan and yeast zymosan were potent inducers of GM-CSF and IL-1beta and also induced substantial short-term cysteinyl leukotriene generation. In contrast, a synthetic triacylated lipopeptide induced short-term degranulation but failed to induce cysteinyl leukotriene production. The TLR4 activator Escherichia coli LPS did not induce a GM-CSF, IL-1beta leukotriene, or degranulation response. These data demonstrate highly selective production of different classes of mast cell mediators in response to distinct TLR activators of potential importance to the host response to bacterial or fungal pathogens.

Selective early production of CCL20, or macrophage inflammatory protein 3alpha, by human mast cells in response to Pseudomonas aeruginosa

Mast cells are important as sentinel cells in host defense against bacterial infection. Much of their effectiveness depends upon recruiting other immune cells; however, little is known about the mechanisms of this response. CCL20, also known as macrophage inflammatory protein-3alpha (MIP-3alpha), Exodus, and LARC, is a chemokine known to be a potent chemoattractant for immature dendritic cells and T cells. In this study, we examined the human mast cell production of both CCL20 and granulocyte-macrophage colony-stimulating factor (GM-CSF), a critical cytokine for innate immune responses in the lung, in response to Pseudomonas aeruginosa. Reverse transcription-PCR and Western blot analysis demonstrated that the human mast cells (HMC-1) express CCL20 mRNA and are able to produce a significant amount (32.4 ng/ml) of CCL20 protein following stimulation by calcium ionophore and phorbol myristate acetate. Importantly, P. aeruginosa potently stimulated CCL20 production in human cord blood-derived mast cells (CBMC), with production peaking at 6 h after stimulation. This time course of expression was distinct from that of GM-CSF, which peaked after 24 to 48 h. Significant CCL20 production did not occur following immunoglobulin E-mediated activation of CBMC under conditions which induced a substantial GM-CSF response. Interestingly, the CCL20 response of mast cells to P. aeruginosa was relatively resistant to inhibition by the corticosteroid dexamethasone, interleukin-10, or cyclosporine, while GM-CSF production was potently inhibited. However, P. aeruginosa-induced CCL20 production was blocked by the protein kinase C (PKC) inhibitor Ro 31-8220 and a PKC pseudosubstrate. These results support a role for human mast cells in the initiation of immune responses to P. aeruginosa infection.

Toll-like receptor 4-mediated activation of murine mast cells

Toll-like receptors (TLRs) are a family of pattern recognition receptors that are critical for cellular responses to a variety of bacterial, viral, and fungal products. Mast cells are important to host survival in a number of models of bacterial infection and might act as sentinel cells in host defense. We therefore examined the expression of TLRs and associated molecules by murine bone marrow-derived mast cells (BMMCs). BMMCs and the murine mast cell line MC/9 expressed mRNA for TLR2, TLR4, and TLR6 but not TLR5 and for both adapter molecule MD-2 and signaling molecule MyD88 but lacked surface CD14. After activation with the TLR2- and TLR4-dependent stimuli Staphylococcus aureus-derived peptidoglycan and Escherichia coli-derived lipopolysaccharide (LPS), respectively, mast cells produced significant levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha). To determine whether mast cells require TLR4 for cellular responses to LPS, mast cells were derived from the bone marrow cells of C3H/HeJ and C57Bl/10ScNCr mice containing a point mutation and a null mutation, respectively, in TLR4. Using these models, we demonstrated that the BMMC IL-6 and TNF-alpha responses to LPS were completely dependent on functional TLR4 with no significant LPS response observed in its absence. These findings have important implications for the mechanism of mast cell responses to pathogens and their products and suggest that different TLR4-expressing cells might have different thresholds for activation with LPS.

Association of leucogenenol, a thymothyroid hormone, with carrier proteins in the thymus

Leucogenenol a heterocyclic enolic thymothyroid hormone (MW 383) whose concentration in the serum regulates the rate at which already committed cells of the bone marrow develop into functional cells, was found to be associated in the thymus with a carrier protein. The carrier protein for leucogenenol is not precipitated by heating to 80 degrees but following this treatment leucogenenol is precipitated in association with proteins precipitated by acetone and then by saturated ammonium sulfate. On chromatography on Sephacryl G-200 it was found that leucogenenol was associated with proteins of MW approximately 38,000. Leucogenenol is not eluted from the chromatographic column if it is not associated with its carrier proteins. It is suggested that other hormones such as those associated with the reproductive cycle or compounds that result from tissue damage induce the liberation of leucogenenol from its carrier protein in the thymus to the circulation where it is associated as previously described, with a protein of approximately MW 300,000.

Effect of leucogenenol, a thymothyroid hormone, on the growth of immature and neonatally thymectomized rats

The reports of early investigators that growth is delayed by thymectomy of immature animals have been confirmed. Although growth is delayed by thymectomy, thymectomized animals approach asymptotically with age the same final weight as corresponding intact animals. Treatment with leucogenenol, a thymothyroid hormone, accelerates the rate of growth of immature neonatally thymectomized rats to that of normal rats. However, treatment with leucogenenol does not increase the rate of growth of normal rats. Treatment with leucogenenol does not change levels of growth hormone (GH) or thyroxine (T4) in the serum of either thymectomized or intact immature and adult rats. Neither is the depression in levels of serum leucogenenol that follows thymectomy associated with a change in serum levels of GH or T4. Thus it is apparent that levels of serum leucogenenol do not affect the rate of growth of immature animals by increasing serum levels of GH or T4. By analogy with the finding that treatment with leucogenenol increases the rate at which committed cells of the bone marrow and cells involved in the immune response develop into functional cells, it is suggested that the levels of serum leucogenenol are one of the factors that determine the rate at which types of body cells that make up bone and other body tissues develop from committed precursors.

Effect of leucogenenol, a thymothyroid hormone, on allograft rejection and hemolysin formation

Recent investigations in this laboratory have established that daily treatment with leucogenenol, an enolic heterocyclic hormone synthesized by the thymus and/or thyroid, induces neonatally thymectomized mice that have accepted a skin allograft to reject this allograft in 7 to 14 days. Also, daily treatment with leucogenenol causes neonatally thymectomized mice to respond to challenge with sheep erythrocytes with the formation of normal titers of hemolysin. These results demonstrate that the hormone leucogenenol induces the development of those cells, absent in neonatally thymectomized mice, that are necessary for a normal immune response.

Effect of leucogenenol, a thymothyroid hormone, on allograft rejection and hemolysin formation

Recent investigations in this laboratory have established that daily treatment with leucogenenol, an enolic heterocyclic hormone synthesized by the thymus and/or thyroid, induces neonatally thymectomized mice that have accepted a skin allograft to reject this allograft in 7 to 14 days. Also, daily treatment with leucogenenol causes neonatally thymectomized mice to respond to challenge with sheep erythrocytes with the formation of normal titers of hemolysin. These results demonstrate that the hormone leucogenenol induces the development of those cells, absent in neonatally thymectomized mice, that are necessary for a normal immune response.

Effect of tumors on the concentration of leucogenenol in the serum of mice

It was found that inoculation of several strains of mice with several types of tumor cells resulted, within 24 hr, in a significant decrease in the serum leucogenenol levels of the mice. Serum leucogenenol levels of the mice inoculated with tumors that are rejected become normal or temporarily above normal at approximately the time the tumor is observed to be rejected. Contrariwise, serum leucogenenol levels of mice inoculated with tumors that are not rejected remain at significantly lower than normal levels during the life of the mice. Unlike tumors, skin allografts increase serum leucogenenol levels. When tumors are rejected because of the previous immunization of the mice, serum leucogenenol levels become normal at approximately the time the tumor is observed to be rejected. Excision of the tumor after 1 week of growth, with the consequent recovery of the mice, is accompanied by a recovery of normal serum leucogenenol levels. Also, it was found that injection of mice with a cell-free 0.9% NaCl solution extract of a tumor results in a temporary decrease in serum leucogenenol levels comparable to that observed with the inoculation of a viable tumor which lasts from 24 to 96 hr. It is suggested that the suppression of serum leucogenenol levels is one of the factors responsible for the immunosuppression associated with a growing tumor.

Leucogenenol a thymothyroid hormone

Thymectomy and, to a lesser extent, thyroidectomy cause a significant decrease in the serum leucogenenol levels of rats. Daily injections of neonatally thymectomized mice with leucogenenol causes the mice to maintain a normal level of neutrophils and lymphocytes in their circulation. The thymus and thyroid are the only tissues in rats and mice that afford radioactive leucogenenol when incubated in a medium containing radioactive D-glucose. It is concluded that the thymus and possibly the thyroid are responsible for the normal biosynthesis of leucogenenol in animals.