Background: Cardiac fibrosis is a crucial aspect of cardiac remodeling that can severely affect cardiac function. Cardiac fibroblasts surely influence this process. Besides, macrophage plays an essential role in cardiac remodeling after heart injury. However, whether macrophage influence fibroblasts remain a question worth exploring. This study aimed to define the role of berberine (BBR) on isoprenaline (ISO)-induced cardiac fibrosis in an in vivo rat model and try to figure out the mechanism in vitro study.
Methods: The Sprague-Dawley rats were divided into five groups: control group, ISO-treated group, and ISO + BBR (10 mg/kg/d, 30 mg/kg/d, and 60 mg/kg/d orally)-pretreatment groups. Fibrosis was induced by ISO administration (5 mg/kg/d subcutaneously) for 10 days. One day after the last injection, all of the rats were sacrificed. Using picrosirius red (PSR) straining, immunohistochemistry, immunofluorescence, flow cytometry, western blot, RT-qPCR and cell co-culture, we explored the influence of pretreatment by BBR on ISO-induced cardiac fibrosis.
Results: Our results showed that BBR pretreatment greatly limited ISO-induced cardiac fibrosis and dysfunction. Moreover, BBR administration reduced macrophage infiltration into the myocardium of ISO-treated rats and inhibited transforming growth factor (TGF)-β1/smads signaling pathways in comparison to that seen in the ISO group. Besides, in vitro study showed that BBR-pretreatment reduced ISO-induced TGF-β1 mRNA expression in macrophages and ISO stimulation of macrophages significantly increased the expression of fibrotic markers in fibroblasts, but BBR-pretreatment blocked this increase.
Conclusion: Our results showed that BBR may have a protective role to cardiac injury via reducing of macrophage infiltration and forbidding fibroblasts transdifferent into an 'activated' secretory phenotype, myofibroblasts.
Keywords: Berberine; Cardiac fibrosis; Cytokines; Fibroblast; Macrophage; TGF-β1.