Introduction

A dysfunctional intestinal mucosal barrier is a key pathophysiological hallmark and driver of a broad range of gastrointestinal diseases including celiac disease and inflammatory bowel disease. To date, there are no adequate treatment strategies to ameliorate impaired barrier function.
IMU-856 is an orally available and systemically acting small molecule modulator of sirtuin 6 (SIRT6), a histone/non-histone protein deacetylase which serves as a transcriptional regulator of intestinal barrier function and regeneration of bowel epithelium. IMU-856 may represent a new approach to treat gastrointestinal diseases with compromised barrier function.

Aims & Methods

This was a first-in-human, double-blind, randomized, placebo-controlled clinical trial of IMU-856 in healthy volunteers and patients with celiac disease. In the multiple ascending dose part, healthy human subjects were dosed once-daily for 14 consecutive days with IMU-856 at three different dose levels or placebo. Additionally, the Phase 1/1b study was designed to assess safety and tolerability of IMU-856 at two different dose levels in patients with celiac disease during periods of gluten-free diet and a 15-day gluten challenge. Further objectives included pharmacokinetics and the assessment of histological changes. Biomarkers reflecting intestinal enterocyte mass and function, nutrient absorption, and enteroendocrine hormones like GLP-1 were analyzed to assess potential effects on gut health.

Results

IMU-856 was safe and well-tolerated with a benign adverse event profile and pharmacokinetics that allow once-daily dosing. Treatment with IMU-856 protected against gluten-induced histologic deterioration, improved the health and metabolic function of intestinal enterocytes as measured by nutrient uptake and citrulline [1], and had positive effects on enteroendocrine cells increasing endogenous GLP-1 levels in a dose-dependent manner.

Conclusion

IMU-856 is a safe, highly selective and potent epigenetic modulator, improving the intestinal barrier function in patients with celiac disease undergoing a gluten challenge.
Positive effects of IMU-856 on gut hormones and various biomarkers for overall gut health including intestinal function and integrity were observed. Therefore, IMU-856 may offer extensive potential for treatment of gastrointestinal diseases with compromised intestinal barrier function and metabolic diseases.

References

1. Daveson AJM, Stubbs R, Polasek TM, Isola J, Anderson R, Tye-Din JA, et al. Safety, clinical activity, pharmacodynamics, and pharmacokinetics of IMU-856, a SIRT6 modulator, in coeliac disease: a first-in-human, randomised, double-blind, placebo-controlled, phase 1 trial.

Disclosure

AS, MW, EP: employees of Immunic AG, option and shareholders of Immunic, Inc.
IPO, JF, IK, SE: employees of Immunic AG, option and/or shareholders of Immunic, Inc.
HK: employee of Immunic AG, shareholder of Immunic, Inc., co-inventor of patents for the drug in investigation
DP: option holder of Immunic, Inc.
DV, AM: employees of Immunic AG and Immunic, Inc., shareholders of Immunic, Inc., co-inventors of patents for the drug in investigation

Introduction

Very early onset inflammatory bowel disease (VEO-IBD) is often associated with a severe disease course and unique characteristics including an underlying monogenic defect. In this study, we identified new pathogenic mutations in CGNL1 associated with VEO-IBD and other inflammatory GI disease. CGNL1 (Cingulin Like 1) encodes an epithelial junctional protein whose function was previously unknown in the gastrointestinal tract.

Aims & Methods

Whole exome sequencing (WES) was performed on the affected patient with VEO-IBD and all first-degree relatives with IBD and other inflammatory disease. Intestinal epithelial organoids (IEOs) were generated from the affected patient and were characterized by transepithelial electrical resistance (TEER), FITC-dextran permeability assay on epithelial cell monolayer, immunostaining, RNA sequencing, and transmission electron microscopy (TEM). In addition, we generated a new Cgnl1^-/- mouse model, which was characterized using FITC-dextran permeability assay, TEM, dextran-sodium sulfate (DSS)-induced colitis, and infections by Citrobacter rodentium and Clostridioides difficile. Single-cell datasets were analyzed to determine CGNL1 expression in IBD, primary sclerosing cholangitis (PSC), and autoimmune hepatitis (AIH).

Results

In the affected patient with VEO-IBD who required early total colectomy and pouch formation with coexistent PSC and celiac disease, WES identified two rare, new, pathogenic variants in the CGNL1 gene. Both pathogenic variants were also present in the patient’s younger sister, who has a similar history including early-onset, fulminant ulcerative colitis requiring total colectomy with ileostomy and PSC-AIH overlap syndrome. Furthermore, multiple relatives of the patient suffer from IBD and other inflammatory conditions including celiac disease, eosinophilic esophagitis, and type-1 diabetes. The RNA and protein levels of CGNL1 were significantly diminished in the patient’s intestinal epithelial cells compared to that of healthy individuals and other IBD patients by RNA-seq, immunoblotting, and immunostaining. The patient’s IEOs from pouch body and pre-pouch ileum formed smaller 3D spheroids with altered cell composition and significantly impaired barrier function compared to those from healthy controls and other IBD patients. Immunofluorescence and TEM demonstrated that CGNL1 is required for the assembly of junctional complexes in human IEOs and an epithelial cell line. Similarly to findings from the patient, impaired junctional complexes in intestinal epithelial cells and elevated intestinal permeability were present in Cgnl1^-/- mice at steady state. Cgnl1^-/- mice showed substantial vulnerability to DSS-induced colitis and bacterial infections that directly compromise the epithelial barrier. In addition, 6-month-old Cgnl1^-/- mice exhibited spontaneous inflammation in the colon and terminal ileum due to disrupted intestinal barrier, which was microbiome-dependent. Furthermore, single-cell analysis revealed diminished expression of CGNL1 in the intestinal and hepatic epithelial cells from patients with IBD or PSC/AIH, respectively.

Conclusion

The pathogenic CGNL1 variants contribute to VEO-IBD by disrupting gut barrier integrity, as demonstrated by patient’s cells and novel murine models. This study expands our understanding of epithelial barrier impairment in the pathogenesis of VEO-IBD, and highlights intestinal epithelium as a therapeutic target in some IBD patients.