Antibiotic Therapy for Active Crohn's Disease Targeting Pathogens: An Overview and Update

Crohn's disease (CD) is a multifactorial chronic disorder that involves a combination of factors, including genetics, immune response, and gut microbiota. Therapy includes salicylates, immunosuppressive agents, corticosteroids, and biologic drugs. International guidelines do not recommend the use of antibiotics for CD patients, except in the case of septic complications. Increasing evidence of the involvement of gut bacteria in this chronic disease supports the rationale for using antibiotics as the primary treatment for active CD. In recent decades, several pathogens have been reported to be involved in the development of CD, but only Escherichia coli (E. coli) and Mycobacterium avium paratubercolosis (MAP) have aroused interest due to their strong association with CD pathogenesis. Several meta-analyses have been published concerning antibiotic treatment for CD patients, but randomized trials testing antibiotic treatment against E. coli and MAP have not shown prolonged benefits and have generated conflicting results; several questions are still unresolved regarding trial design, antibiotic dosing, the formulation used, the treatment course, and the outcome measures. In this paper, we provide an overview and update of the trials testing antibiotic treatment for active CD patients, taking into account the role of pathogens, the mechanisms by which different antibiotics act on harmful pathogens, and antibiotic resistance. Finally, we also present new lines of study for the future regarding the use of antibiotics to treat patients with active CD.

Pathogens in Crohn's Disease: The Role of Adherent Invasive Escherichia coli

In Crohn's disease (CD), gut dysbiosis is marked by the prevalence of pathogenic bacterial species. Although several microbes have been reported as risk factors or causative agents of CD, it is not yet clear which is the real trigger of the disease. Thirty years ago, a new pathovar of Escherichia coli strain was isolated in the ileal mucosa of CD patients. This strain, called adherent invasive E. coli (AIEC), for its ability to invade the intestinal mucosa, could represent the causative agent of the disease. Several authors studied the mechanisms by which the AIEC penetrate and replicate within macrophages, and release inflammatory cytokines sustaining inflammation. In this review we will discuss about the role of AIEC in the pathogenesis of CD, the virulence factors mediating adhesion and invasion of AIEC in mucosal tissue, the environmental conditions improving AIEC survival and replication within macrophages. Finally, we will also give an overview of the new strategies developed to limit AIEC overgrowth.

Efficacy of ustekinumab in the treatment of patients with Crohn's disease with failure to previous conventional or biologic therapy: a prospective observational real-life study

Ustekinumab (UST), a human anti-IL12/23p40 monoclonal antibody, was approved by FDA and EMA for the treatment of moderate to severe Crohn's disease (CD). Whether UST is effective in inducing deep remission, including mucosal healing and transmural healing, in patients with CD in a real life setting is not completely clear. This study was performed on 92 subjects with confirmed diagnosis of moderate to severe Crohn's disease and no neoplasia. Before inclusion, all patients had been exposed and had failed to respond to conventional and/or at least one biological therapy. All patients underwent endoscopic examination and bowel MRI and ultrasonography at baseline (T0). At week 52 (T52), patients underwent colonoscopy for assessment of mucosal healing and MRI or ultrasonography for assessment of transmural healing. CDAI was used for the assessment of clinical response and clinical remission. SES-CD was used to assess endoscopic response and remission. Incidence of treatment-related adverse events (TRAEs) was recorded during the study period. Clinical response at week 52 was achieved in 38 (50.5%) patients and clinical remission in 29 (39%). Twenty-six (34%) patients showed mucosal healing, 34 (45%) showed partial endoscopic response. We observed a reduction in SES-CD of at least 50% in 34 (45%) patients as well as an SES-CD ≤ 2 in 26 (35%) patients. All patients with mucosal healing also showed transmural healing. No major TRAEs were observed during treatment. In this multicenter, real life study, we show that UST was well tolerated and effective in inducing clinical response and clinical remission in patients with moderate to severe CD who had previously failed to respond to conventional or biologic therapy. UST showed limited efficacy in inducing deep remission (i.e. mucosal+transmural healing).

Real-Life Effectiveness and Safety of Golimumab and Its Predictors of Response in Patients with Ulcerative Colitis

BACKGROUND

Golimumab is a new anti-TNF-alpha monoclonal antibody for patients with ulcerative colitis.

AIMS

To assess the short- and long-term effectiveness and safety of golimumab in daily clinical practice and to identify predictors of response.

METHODS

Consecutive patients treated with golimumab in 22 Italian centers were enrolled. Clinical, laboratory, and endoscopic data were prospectively collected before and during treatment. A subgroup of patients completed a questionnaire to assess personal satisfaction with a golimumab autoinjector system.

RESULTS

A total of 196 patients were included. After 3 months, 130 patients were responders (66.3%) and showed significant reductions in mean partial, total, and endoscopic Mayo scores and in mean ESR, C-reactive protein, and fecal calprotectin levels (p < 0.001). Multivariate analysis revealed that a higher total Mayo score (p < 0.001, OR 1.5, 95% CI 1.2-1.8) and naïve status to anti-TNF-alpha (p = 0.015, OR 3.0, 95% CI 1.2-7.5) were predictive of a favorable response. Seventy-seven (39.3%) of the 130 responders maintained a response at month 12 of therapy. There were 17 adverse events, 28 patients needed hospitalization, and 15 patients underwent surgery. Self-administration of the drug was appreciated by most patients.

CONCLUSIONS

The efficacy and safety of golimumab in daily clinical practice were confirmed for the short- and long-term treatment of patients with active ulcerative colitis. Patients naïve to the anti-TNF-alpha monoclonal antibody and those with a higher total Mayo score were more likely to respond to golimumab.

IBD: Role of intestinal compartments in the mucosal immune response

BACKGROUND AND AIMS

Laser capture microdissection (LCM) is a powerful tool for the isolation of specific tissue compartments. We aimed to investigate the mucosal immune response that takes place in different intestinal compartments of IBD patients, dissected by LCM, analyzing cytokines expression profile and endoplasmic reticulum (ER) stress markers.

METHODS

Frozen sections of gut were obtained from patients with Crohn's disease (CD), ulcerative colitis (UC) and from controls. Using LCM, surface epithelium (SE) and lamina propria (LP) compartments were isolated and total RNA extracted. The relative expression of Th1, Th17 and Treg cytokines was evaluated by quantitative reverse transcriptase real-time PCR (qRT-PCR), in addition to the assessment of mRNA splicing of the transcription factor X-box binding protein-1 (XBP1). Human neutrophil elastase (HNE) and the transcription factor forkhead box P3 (Foxp3) were also analyzed by immunohistochemistry.

RESULTS

The increased expression of IL-17 was observed in both intestinal compartments of IBD patients when compared to controls. IFN- γ, TNF-α , IL-10, HNE and Foxp3 were overexpressed in the LP compartment of both IBD patients as compared to controls. An upregulation of IFN-γ and an infiltration of HNE+ cells was found in the SE of patients with UC. Splicing of XBP1 mRNA was recognized in both intestinal compartments of IBD patients when compared to controls.

CONCLUSIONS

In IBD patients, both intestinal compartments are involved in Th17 response, whereas, LP compartment plays a prominent role in Th1 and Treg immune responses. Nevertheless, high level of IFN- γ was found in the SE of UC patients, suggesting that this compartment is involved in the Th1 immune response. Our data also suggested that ER stress signalling is active in both LP and SE compartment of IBD patients, thus advocating that ER stress and immunity are intertwined.

Interobserver agreement in describing video capsule endoscopy findings: a multicentre prospective study

BACKGROUND AND AIM

Few studies have specifically addressed interobserver agreement in describing lesions identified during capsule endoscopy. The aim of our study is to evaluate interobserver agreement in the description of capsule endoscopy findings.

MATERIALS AND METHODS

Consecutive short segments of capsule endoscopy were prospectively observed by 8 investigators. Seventy-five videos were prepared by an external investigator (gold standard). The description of the findings was reported by the investigators using the same validated and standardized capsule endoscopy structured terminology. The agreement was assessed using Cohen's kappa statistic.

RESULTS

As concerns the ability to detect a lesion, the agreement with the gold standard was moderate (kappa 0.48), as well as the agreement relating to the final diagnosis (κ 0.45). The best agreement was observed in identifying the presence of active bleeding (κ 0.72), whereas the poorest agreement concerned the lesion size (κ 0.32). The agreement with the GS was significantly better in endoscopists with higher case/volume of capsule endoscopy per year. Diagnostic concordance was better in the presence of angiectasia than in the presence of polyps or ulcers/erosions.

CONCLUSIONS

Correct lesion identification and diagnosis seem more likely to occur in presence of angiectasia, and for readers with more experience in capsule endoscopy reading.