Evidence that tirzepatide protects against diabetes-related cardiac damages

BACKGROUND

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are effective antidiabetic drugs with potential cardiovascular benefits. Despite their well-established role in reducing the risk of major adverse cardiovascular events (MACE), their impact on heart failure (HF) remains unclear. Therefore, our study examined the cardioprotective effects of tirzepatide (TZT), a novel glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) receptor agonist.

METHODS

A three-steps approach was designed: (i) Meta-analysis investigation with the primary objective of assessing major adverse cardiovascular events (MACE) occurrence from major randomized clinical trials.; (ii) TZT effects on a human cardiac AC16 cell line exposed to normal (5 mM) and high (33 mM) glucose concentrations for 7 days. The gene expression and protein levels of primary markers related to cardiac fibrosis, hypertrophy, and calcium modulation were evaluated. (iii) In silico data from bioinformatic analyses for generating an interaction map that delineates the potential mechanism of action of TZT.

RESULTS

Meta-analysis showed a reduced risk for MACE events by TZT therapy (HR was 0.59 (95% CI 0.40-0.79, Heterogeneity: r2 = 0.01, I2 = 23.45%, H2 = 1.31). In the human AC16 cardiac cell line treatment with 100 nM TZT contrasted high glucose (HG) levels increase in the expression of markers associated with fibrosis, hypertrophy, and cell death (p < 0.05 for all investigated markers). Bioinformatics analysis confirmed the interaction between the analyzed markers and the associated pathways found in AC16 cells by which TZT affects apoptosis, fibrosis, and contractility, thus reducing the risk of heart failure.

CONCLUSION

Our findings indicate that TZT has beneficial effects on cardiac cells by positively modulating cardiomyocyte death, fibrosis, and hypertrophy in the presence of high glucose concentrations. This suggests that TZT may reduce the risk of diabetes-related cardiac damage, highlighting its potential as a therapeutic option for heart failure management clinical trials. Our study strongly supports the rationale behind the clinical trials currently underway, the results of which will be further investigated to gain insights into the cardiovascular safety and efficacy of TZT.

MicroRNA-208a-3p contributes to connexin40 remolding in human chronic atrial fibrillation

Previous studies have demonstrated that connexin40 (Cx40) remolding is involved in atrial fibrillation (AF). GJA5 encoding Cx40 is a potential target mRNA of microRNA-208a-3p (miR-208a-3p), as indicated by preliminary bioinformatics analyses. However, the exact effect of miR-208a-3p on Cx40 in human chronic AF has remained elusive. The present study demonstrated the role of miR-208a-3p in human chronic AF and further investigated the effect of miR-208a-3p on Cx40 expression. A total of 19 patients with AF and 18 patients with sinus rhythm (SR) were enrolled. The AC16 cell line was treated with miR-208a-3p inhibitor or mimics. The miR-208a-3p in right atrial appendage (RAA) tissues of patients was measured by in situ hybridization and reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Furthermore, the expression of Cx40 in the RAA of patients and in AC16 cells treated with miR-208a-3p inhibitor or mimics were detected by RT-qPCR and western blot analysis. A luciferase assay was performed to confirm whether Cx40 was directly targeted by miR-208a-3p. The miR-208a-3p levels in patients with AF were significantly increased compared with those in patients with SR. Conversely, the Cx40 protein levels were significantly decreased and lateralization of Cx40 was observed in patients with AF. miR-208a-3p inhibitor led to a significant upregulation of the protein expression of Cx40 in AC16 cells, while miR-208a-3p mimics led to a significant downregulation. However, the luciferase assay demonstrated that GJA5 was not a direct target gene of miR-208a-3p. The findings still suggested that miR-208a-3p may be involved in human chronic AF by mediating atrial Cx40 remolding, and may represent a potential therapeutic target for AF.