Abstract Body (Do not enter title and authors here): Background:
Diabetic cardiomyopathy is a common complication of diabetes, which can progress to symptomatic heart failure. Current conventional medical therapy does not reverse the deleterious features of diabetic cardiomyopathy. The natriuretic peptide-cGMP system has been proven to provide a cardioprotective role in diabetic rats. Therefore, we developed CRRL094, a n bispecific peptide that simultaneously activates the natriuretic peptide system and glucagon-like peptide-1 (GLP-1) receptor. In this study, we aimed to characterize the cardioprotective role of CRRL094 and elucidate its downstream molecular mechanisms.
Methods:
In vitro, human cardiomyocytes (HCMs) were pretreated with PBS or CRRL094 (5 µM) for 6 hours, then exposed to high glucose treatment (HGT, 25 mM) for 48 hours. HCM hypertrophy was determined by assessing mRNA levels of hypertrophic gene markers (NPPA and NPPB) using real-time PCR. Lipid droplet staining was performed using BODIPY 493/503 dye and fluorescence images were analyzed. The protein levels of CIDEC (lipid droplet-related gene) and phosphorylation-AMPK and total AMPK (a key regulator of lipid metabolism) were analyzed by Western blot. In vivo, a type 2 diabetes (DM2) rat model was established by low-dose intraperitoneal Streptozotocin (STZ) injection and a high-fat diet in Wistar rats (male, 4- to 6-week-old). Diabetes was confirmed by fasting blood glucose > 350 mg/dL. Rats were then allocated to two groups: saline-treated controls (n=6) or CRRL094-treated (30 pmol/kg/min; n=6), with treatment delivered via osmotic pumps for 28 days. Heart tissues were collected and analyzed.
Results:
HGT in HCMs significantly increased the mRNA levels of NPPA and NPPB, whereas CRRL094 significantly attenuated markers of hypertrophy. Further, HGT increased lipid accumulation in HCMs, which was decreased with CRRL094 treatment. Moreover, CRRL094 increased p-AMPK protein levels and decreased CIDEC protein levels in HCMs under HGT. In a DM2 rat model, chronic CRRL094 therapy was associated with suppression of NPPA and NPPB, downregulation of CIDEC, and upregulation of p-AMPK expression in the heart tissue.
Conclusion:
CRRL094 protects against HGT-induced hypertrophy and inhibits lipid accumulation through regulating the AMPK/CIDEC pathway in vitro and in vivo. These findings support CRRL094 as a novel therapeutic candidate to prevent diabetic cardiomyopathy.