Medical Therapy of Crohn's Disease

Novel Rho/MRTF/SRF inhibitors block matrix-stiffness and TGF-β-induced fibrogenesis in human colonic myofibroblasts

BACKGROUND

Ras homolog gene family, member A (RhoA)/Rho-associated coiled-coil forming protein kinase signaling is a key pathway in multiple types of solid organ fibrosis, including intestinal fibrosis. However, the pleiotropic effects of RhoA/Rho-associated coiled-coil forming protein kinase signaling have frustrated targeted drug discovery efforts. Recent recognition of the role of Rho-regulated gene transcription by serum response factor (SRF) and its transcriptional cofactor myocardin-related transcription factor A (MRTF-A) suggest a novel locus for pharmacological intervention.

METHODS

Because RhoA signaling is mediated by both physical and biochemical stimuli, we examined whether pharmacological inhibition of RhoA or the downstream transcription pathway of MRTF-A/SRF could block intestinal fibrogenesis in 2 in vitro models.

RESULTS

In this study, we demonstrate that inhibition of RhoA signaling blocks both matrix-stiffness and transforming growth factor beta-induced fibrogenesis in human colonic myofibroblasts. Repression of alpha-smooth muscle actin and collagen expression was associated with the inhibition of MRTF-A nuclear localization. CCG-1423, a first-generation Rho/MRTF/SRF pathway inhibitor, repressed fibrogenesis in both models, yet has unacceptable cytotoxicity. Novel second-generation inhibitors (CCG-100602 and CCG-203971) repressed both matrix-stiffness and transforming growth factor beta-mediated fibrogenesis as determined by protein and gene expression in a dose-dependent manner.

CONCLUSIONS

Targeting the Rho/MRTF/SRF mechanism with second-generation Rho/MRTF/SRF inhibitors may represent a novel approach to antifibrotic therapeutics.

Crohn's disease clinical issues and treatment: what the radiologist needs to know and what the gastroenterologist wants to know

Crohn's disease is an idiopathic chronic intestinal illness that requires specialized medical care for prompt disease diagnosis and appropriate management. Clinicians must accurately interpret and integrate findings from multitude of sources in order to achieve diagnostic certainty. Ileocolonoscopy remains the most relied modality, allowing for a direct mucosal visualization and biopsies for histologic assessments. Serologic markers currently serve an adjunctive role, often utilized in attempts to further subtype patients with indeterminate colitis. Radiologic imaging, such as computed tomography enterography can evaluate the far reaches of the small intestine, while also providing information about penetrating complications and extraintestinal disease manifestations. Treatment options and strategies continue to evolve with new biologic agents and ongoing testing of aggressive "top-down" approaches. In addition, identification of increased colorectal cancer risks in individuals with Crohn's colitis has led to formal surveillance guidelines. The clinical diagnosis and management of Crohn's disease continues to be an area of rapid change and exciting developments.

Functional consequences of NOD2/CARD15 mutations in Crohn disease

Crohn disease (CD) is a chronic, relapsing inflammatory disorder of the gastrointestinal tract. Its etiology remained obscure until recently, when, through an overwhelming body of research, the main theme of its origin became clear. CD develops in individuals who carry risk alleles for the disease that can cause a loss of physiological tolerance to commensal bacteria. As a consequence, immune responses develop that activate a whole range of immunocompetent cells, resulting in the secretion of proinflammatory mediators that ultimately cause mucosal breaks and the formation of ulceration, edema, and loss of proper function.