A Novel Smad7 Genetic Variant Mapping on the Genomic Region Targeted by Mongersen Is Associated with Crohn’s Disease

Davide Di Fusco,Paolo Giuffrida,Elisabetta Lolli,Flavio Caprioli,Giovanni Monteleone,Antonio Di Sabatino,Stefano Mazza,Ivan Monteleone,Cascella Raffaella,Irene Marafini,Edoardo Troncone,Paola Borgiani,Laura Manzo,Sara Onali,Carmine Stolfi

doi:10.3390/biomedicines8080234

Abstract

Background: Down-regulation of Smad7 with a specific Smad7 antisense (AS) oligonucleotide-containing oral drug (Mongersen) was effective in pre-clinical studies and initial clinical trials in Crohn’s disease (CD) patients. A recent phase 3 trial was discontinued due to an apparent inefficacy of the drug, but factors contributing to the failure of this study remain unknown. Here, we analysed the frequency in CD of rs144204026 C/T single nucleotide polymorphism (SNP), which maps on the corresponding region targeted by the Smad7 AS contained in the Mongersen formulation and examined whether such a variant allele affects the ability of Smad7 AS to knockdown Smad7. Methods: rs144204026 SNP frequency was evaluated in two independent Italian cohorts of Crohn’s disease patients and normal controls. Genotyping was performed by allelic discrimination assay. Smad7 expression was evaluated in wild-type or heterozygous PBMCs treated with Smad7 AS. Results: No TT genotype was seen in CD patients and controls. Heterozygous genotype was more frequent in CD patients of both cohort 1 (11/235, 4.68%) and cohort 2 (8/122, 6.56%) as compared to controls (6/363, 1.65%; p = 0.029 and p = 0.01 respectively). Overall, a statistically significant association was observed between the T variant allele and CD patients’ susceptibility (p = 0.008; OR = 3.28, 95%CI: 1.3–8.3). Smad7 AS down-regulated Smad7 RNA independently of the presence of the variant allele. Conclusions: This is the first study to show an association between Smad7 rs144204026 SNP and CD patients. Data indicate that such a variant does not negatively influence the in vitro inhibitory effect of Smad7 AS on Smad7.

Highlights

Crohn’s disease (CD) and ulcerative colitis (UC), the two major forms of inflammatory bowel diseases (IBD), are chronic immune-mediated disorders of the gastrointestinal tract the incidence of which is rising worldwide [1]
CT heterozygous genotype was more frequent in CD patients than in controls (11/235, 4.68% vs. 6/363, 1.65%; p = 0.029) while there was no difference between UC patients
A statistically significant association between T variant allele and CD susceptibility was observed (p = 0.03; Odds ratios (OR) = 2.87, 95%Confidence intervals (CI) 1.06–7.83), while no association was found for UC

Summary

Introduction

Crohn’s disease (CD) and ulcerative colitis (UC), the two major forms of inflammatory bowel diseases (IBD), are chronic immune-mediated disorders of the gastrointestinal tract the incidence of which is rising worldwide [1]. In the last years several studies have contributed to delineate some of the major pathways of tissue damage in IBD, thereby facilitating the development of various therapeutic compounds which inhibit the mucosal inflammatory response in these disorders [1,2]. In this context, we have previously shown that the activity of transforming growth factor (TGF)-β1, one of the major counter-regulatory molecules, is severely impaired in the gut of IBD patients due to the elevated levels of the intracellular inhibitor Smad7 [3,4,5]. Smad expression was evaluated in wild-type or heterozygous PBMCs treated with Smad AS

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