Cardiotrophin-1 attenuates experimental colitis in mice

Cytokines of the interleukin-6 family as emerging targets in inflammatory bowel disease

INTRODUCTION

Inflammatory bowel disease (IBD) is an umbrella term that includes different chronic inflammatory diseases of the gastrointestinal tract, most commonly Crohn's disease and ulcerative colitis. IBD affects more than 6 million people worldwide and constitutes not only a debilitating disease for the patients, but also a significant factor for society due to costs for health care and reduced working capacity. Despite the introduction of biologicals for the treatment of IBD, the identification of novel targets that could lead to novel therapeutics is still needed.

AREAS COVERED

In this review, we summarize current knowledge about the interleukin-6 family of cytokines as potential therapeutic targets for improving the therapy of patients with IBD. We discuss cytokines like IL-6 itself for which therapeutics such as inhibitory monoclonal antibodies have already entered the clinics, but also focus on other family members whose therapeutic potential has not been explored yet.

EXPERT OPINION

The different cytokines of the IL-6 family offer multiple therapeutic targets that can potentially be used to treat patients with inflammatory bowel disease, but unwanted side effects like inhibition of epithelial regeneration have to be considered.

New insights into IL-6 family cytokines in metabolism, hepatology and gastroenterology

IL-6 family cytokines are defined by the common use of the signal-transducing receptor chain glycoprotein 130 (gp130). Increasing evidence indicates that these cytokines are essential in the regulation of metabolic homeostasis as well as in the pathophysiology of multiple gastrointestinal and liver disorders, thus making them attractive therapeutic targets. Over the past few years, therapies modulating gp130 signalling have grown exponentially in several clinical settings including obesity, cancer and inflammatory bowel disease. A newly engineered gp130 cytokine, IC7Fc, has shown promising preclinical results for the treatment of type 2 diabetes, obesity and liver steatosis. Moreover, drugs that modulate gp130 signalling have shown promise in refractory inflammatory bowel disease in clinical trials. A deeper understanding of the main roles of the IL-6 family of cytokines during homeostatic and pathological conditions, their signalling pathways, sources of production and target cells will be crucial to the development of improved treatments. Here, we review the current state of the role of these cytokines in hepatology and gastroenterology and discuss the progress achieved in translating therapeutics targeting gp130 signalling into clinical practice.

Preventive Effect of Cardiotrophin-1 Administration before DSS-Induced Ulcerative Colitis in Mice

Ulcerative colitis is a relatively frequent, chronic disease that impacts significantly the patient's quality of life. Although many therapeutic options are available, additional approaches are needed because many patients either do not respond to current therapies or show significant side effects. Cardiotrophin-1 (CT-1) is a cytokine with potent cytoprotective, anti-inflammatory, and antiapoptotic properties. The purpose of this study was to assess if the administration of CT-1 could reduce colon damage in mice with experimental colitis was induced with 5% dextran sulfate sodium (DSS) in the drinking water. Half of the mice received an i.v. dose of CT-1 (200 µg/kg) 2 h before and 2 and 4 days after DSS administration. Animals were followed during 7 days after DSS administration. The severity of colitis was measured by standard scores. Colon damage was assessed by histology and immunohistochemistry. Inflammatory mediators were measured by Western blot and PCR. CT-1 administration to DSS-treated mice ameliorated both the clinical course (disease activity index), histological damage, inflammation (colon expression of TNF-α, IL-17, IL-10, INF IFN-γ, and iNOS), and apoptosis. Our results suggest that CT-1 administration before induction of colitis improves the clinical course, tissue damage, and inflammation in DSS-induced colitis in mice.

Potential clinical treatment of colitis with cardiotrophin-1

In a recent issue of Clinical Science, Prieto-Vicente et al. [Clin. Sci. (2018) 132, 985-1001] have smartly demonstrated a potential new use of cardiotrophin-1 (CT-1) to treat and palliate an inflammatory bowel disease such as ulcerative colitis. In that work, authors report that in ulcerative colitic mice, administration of exogenous recombinant CT-1 (rCT-1) promotes lower colon damage and lower disease activity index, reducing systemic levels of tumor necrosis factor α (TNF-α) and also diminishing TNF-α expression in colon together with the reduction in other common inflammation markers. Besides, in vivo rCT-1 administration induces activation of several molecular pathways, including nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription (STAT)-3, and abolishes bacterial translocation from intestine to other organs, including mesenteric ganglia, lungs, and spleen. Additionally, these results were nicely corroborated in CT-1 depleted mice; in which colon damage and ulcerative colitis severity were greater compared with the wild-type counterparts. All together, these results suggested that CT-1 could be a promising new therapeutic approach for treating inflammatory bowel disease, particularly ulcerative colitis. However, further studies are required to determine its major mechanisms of action and the potential efficacy of CT-1 in human inflammatory bowel diseases.