Anti-TNFα alters the natural history of experimental Crohn's disease in rats when begun early, but not late, in disease

Infliximab modifies CD74-mediated lymphatic abnormalities and adipose tissue alterations in creeping fat of Crohn's disease

BACKGROUND

Lymphatic abnormalities are essential for pathophysiologic changes of creeping fat (CrF) in Crohn's disease (CD). Anti-tumor necrosis factor (TNF) therapy has been proved to alleviate CrF lesions, however, whether it achieves these by remodeling lymphatics is unknown.

METHODS

CD74 expression was detected in CrF and uninvolved mesentery of CD patients. Lymphatic functions in vitro were evaluated and lymphatic endothelium barrier were checked by transendothelial electrical resistance (TEER) and FITC-Dextran permeability. Protein level of tight junction and signaling pathways were detected by western blotting.

RESULTS

CD74 was upregulated in LECs of CrF and positively correlated with TNF-α synthesis. This was suppressed by IFX administration. In vitro, TNF-α stimulated LECs to express CD74 through NF-κB signaling pathway, and this was rescued by IFX. CD74 downregulation suppressed the abilities of LECs in proliferation, migration and tube formation. Interaction of CD74-MIF impaired LECs' barrier via reducing tight junction proteins in an ERK1/2-dependent manner, which was reversed by CD74 downregulation. Consistently, the CD patients receiving IFX therapy displayed decreased lymphangiogenesis and improved mesenteric lymphatic endothelium barrier, companied with reduced adipocyte size and adipokine levels in CrF.

CONCLUSIONS

Anti-TNF therapy could modify pathological changes in CrF by alleviating CD74-mediated lymphatic abnormalities.

Can we change the natural course of inflammatory bowel disease?

Inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), are lifelong diseases characterized by chronic inflammation of the gastrointestinal tract leading to its progressive and irreversible destruction. Whether early initiation of IBD-specific therapy impacts the long-term course of the disease remains unclear and has to be further explored in prospective disease-modification trials. Historically, surgery and hospitalization rates have been the surrogate markers to measure disease progression in IBD, providing an overview of the effectiveness of medical therapies. However, neither surgery nor hospitalization necessarily reflects a fail in therapeutic medical management, and many confounding factors make them biased outcomes. The Selecting Endpoints for Disease-Modification Trials consensus has defined the disease-modification endpoints required for these trials, including the impact of the disease on patient's life (health-related quality of life, disability, and fecal incontinence), the mid-term disease complications (bowel damage in CD, IBD-related surgery and hospitalizations, disease extension in UC, extra-intestinal manifestations, permanent stoma, short bowel syndrome), and the development of dysplasia/cancer and mortality in the long term. Most available data in the literature regarding the impact of current therapies on disease progression focused on anti-tumor necrosis factor agents and are based on retrospective or post-hoc studies. Thus, prospective disease-modification trials are pressingly required to explore the effectiveness of early intensified treatment in patients with severe disease or at risk for disease progression.

Immunological Regulation of Intestinal Fibrosis in Inflammatory Bowel Disease

Intestinal fibrosis is a late-stage phenotype of inflammatory bowel disease (IBD), which underlies most of the long-term complications and surgical interventions in patients, particularly those with Crohn's disease. Despite these issues, antifibrotic therapies are still scarce, mainly due to the current lack of understanding concerning the pathogenetic mechanisms that mediate fibrogenesis in patients with chronic intestinal inflammation. In the current review, we summarize recent evidence regarding the cellular and molecular factors of innate and adaptive immunity that are considered critical for the initiation and amplification of extracellular matrix deposition and stricture formation. We focus on the role of cytokines by dissecting the pro- vs antifibrotic components of the immune response, while taking into consideration their temporal association to the progressive stages of the natural history of IBD. We critically present evidence from animal models of intestinal fibrosis and analyze inflammation-fibrosis interactions that occur under such experimental scenarios. In addition, we comment on recent findings from large-scale, single-cell profiling of fibrosis-relevant populations in IBD patients. Based on such evidence, we propose future potential targets for antifibrotic therapies to treat patients with IBD.

Earlier Anti-Tumor Necrosis Factor Therapy of Crohn's Disease Correlates with Slower Progression of Bowel Damage

INTRODUCTION

Crohn's disease (CD) follows a relapsing and remitting course incurring cumulative bowel damage over time. The question of whether or not the timing of the initiating biologic therapy affects long-term disease progression remains unanswered. Herein, we calculated rates of change in the Lémann index-which quantifies accumulated bowel damage-as a function of the time between the disease onset and initiation of biologic therapy. We aimed to explore the impact of the earlier introduction of biologics on the rate of progression of long-term cumulative bowel damage.

METHODS

Medical records of CD patients treated during 2009-2014 at The Mount Sinai Hospital were queried. Inclusion criteria were two comprehensive assessments allowing calculation of the index at t₁ and t₂: two time-points ≥ 1 year apart. Patients with biologics introduced before or within 3 months at inclusion (t₁) were defined as Bio-pre-t₁ and those who did not as Bio-post-t₁. The rate of disease progression was calculated as the change in the index per year during t₁-t₂.

RESULTS

A total of 88 patients were studied: 58 Bio-pre-t₁ and 30 Bio-post-t₁. Among the 58 Bio-pre-t₁ cases, damage progressed in 29 (50%), regressed in 20 (34.5%), and stabilized in 9 (15.5%). Median time to initiation of biologics among patients whose index improved was nominally shorter compared to that in patients whose index progressed (8 vs. 15 years). Earlier introduction of biologics tended to correlate with the slower rate of progression (ρ = 0.241; p = 0.069).

CONCLUSIONS

Earlier introduction of biologics tended to correlate with the slower progression of bowel damage in CD, reflected by the reduced rate of Lémann index progression.

Early Initiation of Anti-TNF is Associated with Favourable Long-term Outcome in Crohn's Disease: 10-Year-Follow-up Data from the Swiss IBD Cohort Study

BACKGROUND AND AIMS

The optimal timing of treatment escalation in Crohn's disease [CD] remains a challenging issue, and very little is known about its long-term development following early versus late administration of anti-TNF antibodies. The long-term outcome of Swiss CD patients was comparatively assessed in an up to 10-year follow-up, using patients participating in the Swiss Inflammatory Bowel Disease Cohort Study [SIBDCS].

METHODS

Prospectively collected SIBDCS patient data, including disease history, baseline characteristics at enrolment, and course of disease, were analysed in patients with early versus late [<24 versus ≥24 months after diagnosis] and no anti-TNF treatment.

RESULTS

A reduced risk of developing bowel stenosis was found in patients who received early anti-TNF treatment. This association was seen in patients overall and also in the subgroups of CD patients without pre-existing complications [Log-rank test: p < 0.001].Furthermore, osteoporosis and anaemia were observed significantly less frequently in patients who received early anti-TNF treatment, compared with either patients who received treatment late [p < 0.001 and p = 0.046, respectively] or were never [p < 0.001 for both] treated with anti-TNF antibodies. Patients with early anti-TNF administration sought medical consultations significantly less often, including gastroenterologists in private practice [p = 0.017], ambulatory [outpatient] hospital visits [p = 0.038], and a composite of any medical visits [p = 0.001]. The percentage of patients unable to work was lowest for early-anti-TNF-treated patients, in comparison with patients who were treated late or never [3.6% vs 8.8% vs 3.7%, p = 0.016].

CONCLUSIONS

In CD patients within the SIBDCS, early anti-TNF administration was found to be associated with several indicators of a more favourable long-term outcome.

Mouse models of inflammatory bowel disease for investigating mucosal immunity in the intestine

PURPOSE OF REVIEW

Currently several mouse models are considered representative of inflammatory bowel disease (IBD). This review presents recent developments regarding the role of animal models of intestinal inflammation as research tools in IBD.

RECENT FINDINGS

Preclinical studies in animal models of intestinal inflammation have generated novel findings in several areas of IBD research. The combination of chemical and genetically engineered models have revealed protective or harmful roles for various components of the innate immune system in response to acute injury and repair mechanisms for the intestinal mucosa. Advances in the use of endoscopic and radiologic techniques have allowed identification of inflammatory biomarkers and in-vivo monitoring of cell trafficking towards inflammatory sites. Translational research has shed light on pathogenic mechanisms through which recent biological treatments may exert their beneficial effects in patients with IBD. Finally, novel therapies are continuously tested in animal models of IBD as part of preclinical drug development programs.

SUMMARY

Animal models of intestinal inflammation continue to be important research tools with high significance for understanding the pathogenesis of IBD and exploring novel therapeutic options. Development of additional experimental models that address existing limitations, and more closely resemble the characteristics of Crohn's disease and ulcerative colitis are greatly needed.