Tranilast Reduces Pathological Cardiac Fibrosis and Improves Diastolic Function Following Kidney Dysfunction: Implication for Cardio-Renal Syndrome

Abstract

Tissue microarrays (TMAs) enable high-throughput molecular profiling of multiple tissue samples by immunohistochemistry. Our arrays comprise 10 × 12 sections of 1 mm cores obtained from fixed formalin, paraffin-embedded myocardium. Each heart is represented by two separate core samples. We developed four TMAs containing cardiac samples from patients undergoing heart transplantation; in addition to samples from several non-failing (unused donor) hearts, which served as healthy controls. To validate the TMAs for quantitative protein expression, we undertook a pilot study to measure the protein expression of four-and-a-half LIM protein-2 (FHL2) in hypertrophic and dilated cardiomyopathy relative to non-failing hearts. The LIM domain is a cysteine-histidine rich, zinc-coordinating domain, consisting of two tandemly repeated zinc fingers. Many LIM domain proteins were initially identified as cytoskeletonassociated proteins but are now known to influence gene expression by interacting with transcription factors such as members of the cyclic-AMP-response-element binding protein family. We studied FHL2 as it is preferentially expressed in high levels in the adult heart and is seen in both healthy and diseased states. The antibody was raised in rabbits against synthetic peptides of the FHL2 gene sequence to produce affinity-purified polyclonal FHL2 antibodies. We confirmed changes in FHL2 expression using Western blotting of SDS-PAGE gels. This pilot study demonstrated that FHL2 largely localises at the intercalated discs in cardiomyocytes. Preliminary evidence suggests there is a significant decrease in expression of FHL2 in hypertrophic cardiomyopathy and a trend towards decreased expression in idiopathic dilated cardiomyopathy. http://dx.Background: Cardio-renal syndrome (CRS) in heart failure (HF) is associated with increased mortality, morbidity and cost of care. Fibrosis plays an important role in disease progression in HF in patient with CRS. We examined the effect of the anti-fibrotic agent, tranilast on ameliorating these processes.Methods: 5/6 nephrectomy (STNx) was induced in Sprague Dawley (SD) rats, then randomised to tranilast (300 mg/kg/day, p.o.) or vehicle for 12 weeks, then echocardiogram was performed. Myocardial tissues were harvested for histological analysis.Results: Tranilast reduced blood pressure, increased GFR improved diastolic cardiac function and reduced collagen I and III deposition in the heart post-STNx (Table).Conclusion: Tranilast reduced cardiac fibrosis and improved diastolic cardiac function, renal function and blood pressure in STNx rats. These findings support the use of direct antifibrotic strategies in CRS to improve cardiac structure and function.