Kay Sauder

Intestinal fibrosis is reduced by early elimination of inflammation in a mouse model of IBD: Impact of a “Top‐Down” approach to intestinal fibrosis in mice

Background: The natural history of Crohns disease follows a path of progression from an inflammatory to a fibrostenosing disease, with most patients requiring surgical resection of fibrotic strictures. Potent antiinflammatory therapies reduce inflammation but do not appear to alter the natural history of intestinal fibrosis. The aim of this study was to determine the relationship between intestinal inflammation and fibrogenesis and the impact of a very early “top‐down” interventional approach on fibrosis in vivo. Methods: In this study we removed the inflammatory stimulus from the Salmonella typhimurium mouse model of intestinal fibrosis by eradicating the S. typhimurium infection with levofloxacin at sequential timepoints during the infection. We evaluated the effect of this elimination of the inflammatory stimulus on the natural history of inflammation and fibrosis as determined by gross pathology, histopathology, mRNA expression, and protein expression. Results: Fibrogenesis is preceded by inflammation. Delayed eradication of the inflammatory stimulus by antibiotic treatment represses inflammation without preventing fibrosis. Early intervention significantly ameliorates but does not completely prevent subsequent fibrosis. Conclusions: This study demonstrates that intestinal fibrosis develops despite removal of an inflammatory stimulus and elimination of inflammation. Early intervention ameliorates but does not abolish subsequent fibrosis, suggesting that fibrosis, once initiated, is self‐propagating, suggesting that a very early top‐down interventional approach may have the most impact on fibrostenosing disease. (Inflamm Bowel Dis 2012;)

Prior Helicobacter pylori infection ameliorates Salmonella typhimurium‐induced colitis: Mucosal crosstalk between stomach and distal intestine

Background: Helicobacter pylori infection is associated with a lower risk of chronic autoimmune diseases including inflammatory bowel disease (IBD). H. pylori modulates the gastric immune response, decreasing the local inflammatory response to itself. In mice, chronic Salmonella typhimurium infection induces colitis similar to Crohns disease, characterized by inflammation, which progresses toward fibrosis. The aim of this study was to determine whether prior H. pylori infection acts at a distance to modulate the immune response of S. typhimurium‐induced colitis. Methods: Mice were infected with the mouse‐adapted strain of H. pylori (SS1), followed by infection with S. typhimurium. The effect of H. pylori on colitis was determined by gross pathology, histopathology, cytokine response, and development of fibrosis in the cecum. Gastritis and systemic immune response was measured in response to infection. Results: H. pylori suppresses the Th17 response to S. typhimurium infection in the mouse cecum, but does not alter the Th2 or T‐regulatory response or the development of fibrosis. H. pylori infection induces IL‐10 in the mesenteric lymph nodes, suggesting an extragastric mechanism for immunomodulation. H. pylori / S. typhimurium coinfection decreases inflammation in both the cecum and the stomach. Conclusions: This study demonstrates a potential mechanism for the negative association between H. pylori and IBD in humans. H. pylori represses the lower gastrointestinal tract Th17 response to bacterially induced colitis via extragastric immunomodulatory effects, illustrating immunological crosstalk between the upper and lower gastrointestinal tract. (Inflamm Bowel Dis 2011;)

Matrix Stiffness Corresponding to Strictured Bowel Induces a Fibrogenic Response in Human Colonic Fibroblasts

Background:Crohns disease is characterized by repeated cycles of inflammation and mucosal healing which ultimately progress to intestinal fibrosis. This inexorable progression toward fibrosis suggests that fibrosis becomes inflammation-independent and auto-propagative. We hypothesized that matrix stiffness regulates this auto-propagation of intestinal fibrosis. Methods:The stiffness of fresh ex vivo samples from normal human small intestine, Crohns disease strictures, and the unaffected margin were measured with a microelastometer. Normal human colonic fibroblasts were cultured on physiologically normal or pathologically stiff matrices corresponding to the physiological stiffness of normal or fibrotic bowel. Cellular response was assayed for changes in cell morphology, &agr;-smooth muscle actin staining, and gene expression. Results:Microelastometer measurements revealed a significant increase in colonic tissue stiffness between normal human colon and Crohn’s strictures and between the stricture and adjacent tissue margin. In Ccd-18co cells grown on stiff matrices corresponding to Crohn’s strictures, cellular proliferation increased. Pathologic stiffness induced a marked change in cell morphology and increased &agr;-smooth muscle actin protein expression. Growth on a stiff matrix induced fibrogenic gene expression, decreased matrix metalloproteinase, and proinflammatory gene expression and was associated with nuclear localization of the transcriptional cofactor MRTF-A. Conclusions:Matrix stiffness, representative of the pathologic stiffness of Crohn’s strictures, activates human colonic fibroblasts to a fibrogenic phenotype. Matrix stiffness affects multiple pathways, suggesting that the mechanical properties of the cellular environment are critical to fibroblast function and may contribute to auto-propagation of intestinal fibrosis in the absence of inflammation, thereby contributing to the intractable intestinal fibrosis characteristic of Crohn’s disease.

CARD-024, a vitamin D analog, attenuates the pro-fibrotic response to substrate stiffness in colonic myofibroblasts

Intestinal fibrosis is one of the major complications of Crohns disease (CD) for which there are no effective pharmacological therapies. Vitamin D deficiency is common in CD, though it is not known whether this is a contributing factor to fibrosis, or simply a consequence of the disease itself. In CD, fibrosis is mediated mainly by activated intestinal myofibroblasts during remodeling of extracellular matrix in response to wound healing. We investigated the effects of CARD-024 (1-alpha-hydroxyvitamin D5), a vitamin D analog with minimal hypercalcemic effects, on the pro-fibrotic response of intestinal myofibroblasts to two fibrogenic stimuli: TGFβ stimulation and culture on a physiologically stiff matrix. TGFβ stimulated a fibrogenic phenotype in Ccd-18co colonic myofibroblasts, characterized by an increase in actin stress fibers and mature focal adhesions, and increased αSMA protein expression, while CARD-024 repressed αSMA protein expression in a dose-dependent manner. Culture of colonic myofibroblasts on physiological high stiffness substrates induced morphological changes with increased actin stress fibers and focal adhesion staining, induction of αSMA protein expression, FAK phosphorylation, induction of fibrogenic genes, and repression of COX-2 and IL-1β. CARD-024 treatment repressed the stiffness-induced morphological features including stellate cell morphology and the maturation of focal adhesions. CARD-024 repressed the stiffness-mediated induction of αSMA protein expression, FAK phosphorylation, and MLCK and ET-1 gene expression. In addition, CARD-024 partially stimulated members of the COX-2/IL-1β inflammatory pathway. In summary, CARD-024 attenuated the pro-fibrotic response of colonic myofibroblasts to high matrix stiffness, suggesting that vitamin D analogs such as CARD-024 may ameliorate intestinal fibrosis.

Transient or persistent norovirus infection does not alter the pathology of Salmonella typhimurium induced intestinal inflammation and fibrosis in mice

Murine noroviruses (MNV) are currently the most prevalent viruses infecting mouse research colonies. Concurrent infection of research mice with these viruses can dramatically alter the experimental outcome in some research models, but not others. In this report, we investigated the effect of MNV1 and MNV4 on a murine model of intestinal inflammation and fibrosis induced by Salmonella typhimurium infection in C57BL/6 mice. Subsequent co-infection of these mice with MNV1 or MNV4 did not lead to major changes in histopathology, the inflammatory response, or the fibrotic response. Thus, MNV does not substantially alter all gastrointestinal research models, highlighting the importance of investigating potential alterations in the research outcome by MNV on an individual basis. We hypothesize that this is particularly important in cases of research models that use immunocompromised mice, which could be more sensitive to MNV infection-induced changes.

Machine Learning Algorithms for Objective Remission and Clinical Outcomes with Thiopurines

Background and Aims Big data analytics leverage patterns in data to harvest valuable information, but are rarely implemented in clinical care. Optimising thiopurine therapy for inflammatory bowel disease [IBD] has proved difficult. Current methods using 6-thioguanine nucleotide [6-TGN] metabolites have failed in randomized controlled trials [RCTs], and have not been used to predict objective remission [OR]. Our aims were to: 1) develop machine learning algorithms [MLA] using laboratory values and age to identify patients in objective remission on thiopurines; and 2) determine whether achieving algorithm-predicted objective remission resulted in fewer clinical events per year. Methods Objective remission was defined as the absence of objective evidence of intestinal inflammation. MLAs were developed to predict three outcomes: objective remission, non-adherence, and preferential shunting to 6-methylmercaptopurine [6-MMP]. The performance of the algorithms was evaluated using the area under the receiver operating characteristic curve [AuROC]. Clinical event rates of new steroid prescriptions, hospitalisations, and abdominal surgeries were measured. Results Retrospective review was performed on medical records of 1080 IBD patients on thiopurines. The AuROC for algorithm-predicted remission in the validation set was 0.79 vs 0.49 for 6-TGN. The mean number of clinical events per year in patients with sustained algorithm-predicted remission [APR] was 1.08 vs 3.95 in those that did not have sustained APR [p < 1 x 10-5]. Reductions in the individual endpoints of steroid prescriptions/year [-1.63, p < 1 x 10-5], hospitalisations/year [-1.05, p < 1 x 10-5], and surgeries/year [-0.19, p = 0.065] were seen with algorithm-predicted remission. Conclusions A machine learning algorithm was able to identify IBD patients on thiopurines with algorithm-predicted objective remission, a state associated with significant clinical benefits, including decreased steroid prescriptions, hospitalisations, and surgeries.

Predicting Corticosteroid-Free Biologic Remission with Vedolizumab in Crohn’s Disease

Background and Aims Vedolizumab (VDZ) is effective for Crohns disease (CD) but costly and is slow to produce remission. Early knowledge of whether vedolizumab is likely to succeed is valuable for physicians, patients, and insurers. Methods Phase 3 clinical trial data on VZD for CD were used to predict outcomes. Random forest modeling on the training cohort was used to predict the outcome of corticosteroid-free biologic remission at week 52 on the testing cohort. Models were constructed using baseline data, or data through week 6 of VDZ therapy. Results The clinical trial included 594 subjects who received VDZ with baseline active inflammation [elevated C-reactive protein (>5 mg/L)]. Subjects with missing predictor variables (N = 120) or missing outcome data (N = 2) were excluded to produce a modeling dataset of 472 subjects. The Area Under the Receiver Operating Characteristic curve (AuROC) for corticosteroid-free biologic remission at week 52 using baseline data was only 0.65 (95% CI: 0.53 - 0.77), but was 0.75 (95% CI: 0.64 - 0.86) with data through week 6 of VDZ . Patients predicted to be in corticosteroid-free biologic remission at week 52 by the model achieved this endpoint 35.8% of the time, whereas patients predicted to fail only succeeded 6.7% of the time. Conclusions An algorithm using laboratory data through week 6 of VDZ therapy was able to identify which CD patients with baseline inflammation would achieve corticosteroid-free biologic remission on VDZ at week 52. A majority of patients can be identified by week 6 as very unlikely to achieve remission.

Predicting corticosteroid-free endoscopic remission with vedolizumab in ulcerative colitis

Vedolizumab is an effective therapy for ulcerative colitis (UC), but costly and slow to work. New clinical responses occur after 30 weeks of therapy.

External Validation of a Thiopurine Monitoring Algorithm on the SONIC Clinical Trial Dataset

Several reports leverage patterns in Electronic Medical Record (EMR) data to create algorithms to optimize outcomes in healthcare.1–3 More recently, there has been an increasing call for the use of clinical trial data repositories.4 Open clinical trial data sharing has allowed us evaluate the generalizability of algorithms to predict response to thiopurines in patients with inflammatory bowel disease. Yale University Open Data Access (YODA, http://yoda.yale.edu/) is a data-sharing platform which provides access to multiple clinical trial datasets. Previously we internally validated machine learning algorithms for both clinical and biological remission among patients on thiopurines.2,3 We now sought to externally validate the previously developed algorithm to predict objective remission in the SONIC clinical trial of azathioprine, infliximab, or the combination of azathioprine and infliximab in Crohn’s disease using open clinical trial data. Thiopurines continue to be used as monotherapy or as part of combination therapy for the treatment of inflammatory bowel disease (IBD). Worldwide, thiopurines are frequently used as a monotherapy as they remain a low-cost option for steroid-sparing therapy. Experts in IBD rely on patterns in the complete blood count and differential (CBCD) and comprehensive chemistry panel (COMP) to monitor their patients, as thiopurine metabolites perform poorly in the evaluation of clinical response.5 Metabolites have also failed to show benefit in two prospective randomized controlled trials.6–7 Patterns in the CBCD and COMP can be successfully used to predict objective remission with high accuracy, and have been internally validated.3

W1849 Late Removal of Inflammatory Stimulus Does Not Abrogate Fibrosis Development In Vivo in a Mouse Model of Inflammation and Fibrosis

Background: Intestinal scarring is a major cause of morbidity in Crohns disease. Current therapies treat inflammation, but do not alter the progression of fibrosis and bowel obstruction. Given the observation that late use of potent anti-inflammatory therapies does not reduce stenosis or obstruction, we hypothesized that intestinal fibrosis becomes self-propagating, despite removal of inflammatory stimuli. Methods: The Salmonella typhimurium murine model of inflammation and fibrosis in which clearance of commensal microbiota by streptomycin, followed by infection with S. typhimurium, produces chronic inflammation, culminating with fibrosis by day 21 post infection was used. The inflammatory stimulus (S. typhimurium) was removed with the oral antibiotic levofloxacin at day 2, 4, or 8 post-infection. Eradication of S.typhimurium was confirmed by stool plating and T-RFLP analysis. Results: By day 2 post-infection, the mouse cecae infected with S.typhimurium developed an inflammatory phenotype, characterized by a shrunken yet heavier cecum, expansion of the cecal submucosa, and induction of inflammatory genes (IL-1b, TNFa, IL-6, IL-17, IL12p40). However, fibrotic gene expression (CTGF, IGF-1, TGFb) was indistinguishable from uninfected controls. In addition, aSMA protein expression was not induced until day 8 postinfection. Early intervention (day 2 & 4) repressed inflammation as determined by gross pathology, histopathology, and repression of inflammatory genes. Fibrotic gene expression was partially repressed by day 2 levofloxacin treatment. However, day 8 levofloxacin treatment did not prevent induction of aSMA protein or pro-fibrotic genes (CTGF, IGF-1, TGFb) by day 8 and which continued to increase after levofloxacin treatment to day 21, remaining significantly higher than uninfected controls or matched S.typhimurium infected mice harvested at day 4 and 8 post-infection (p < 0.03) Conclusions: Early removal of the inflammatory stimulus reduces fibrosis, but fibrosis after initiation continues to propagate in the absence of an inflammatory stimulus. Since many Crohns patients develop complications of fibrosis, understanding the mechanisms of auto-propagation of fibrosis and developing anti-fibrotic therapies is critical to improving outcomes in Crohns disease.