Growth Hormone Alleviates Atherosclerosis Through Regulating the Activity of PI3K/AKT Pathway: Insights From Single-Cell Sequence and Mechanism Exploration

Purpose: This research sought to investigate the impact and underlying mechanisms of growth hormone (GH) on atherosclerosis (AS) based on the analysis of single-cell RNA Sequencing (scRNA-seq) data.

Methods: We analyzed the impact of GH on arterial vascular smooth muscle cells (VSMCs) by utilizing scRNA-seq data obtained from both atherosclerotic and healthy vascular tissues in mice. AS was induced in C57BL/6 and apoE^-/- mice through hypophysectomy performed via the parapharyngeal approach, followed by a high-fat diet (HFD), resulting in the C57-Hx and apoE^-/--Hx models. AS was evaluated by measuring arterial lipid deposition, plaque progression, Collagen loss, vascular inflammation, and oxidative stress. Serum metabolite alterations were assessed using liquid chromatography-mass spectrometry (LC-MS). RNA Sequencing was employed to examine the underlying mechanisms of GH in the context of AS treatment, with findings further confirmed through western blot analysis. In vitro experiments involved treating VSMCs with oxidized low-density lipoprotein (ox-LDL) to simulate atherosclerotic injury. The formation of foam cells was evaluated by measuring lipid accumulation, inflammatory responses, Apoptosis, and the expression levels of foam cell-related markers. Finally, the PI3K/Akt Inhibitor LY294002 confirmed that GH alleviates AS via the PI3K/Akt signaling pathway.

Results: scRNA-seq data analysis showed that growth hormone signaling was reduced in VSMCs of atherosclerotic arteries. HFD led to elevated levels of serum total Cholesterol (TC), triglycerides (TGs), and low-density lipoprotein Cholesterol (LDL-C), accompanied by increased lipid deposition, inflammatory responses, and oxidative stress. In contrast, high-density lipoprotein Cholesterol (HDL-C) and insulin-like growth factor 1 (IGF-1) levels were lower in C57-Hx mice. GH treatment improved HFD-induced AS in apoE^-/--Hx mice. LC-MS analysis revealed that GH altered lipid metabolism in serum samples from C57-sham, C57-Hx, apoE^-/--Hx, and apoE^-/--Hx-GH(3) mice. GH maintained lipid balance by increasing 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine (POPC), PE-NMe2(18:1(9z)/18:1(9z)) (DMPE), and 4-chloro-2-nitrobenzylalcohol levels and decreasing 1-heptadecanoyl-sn-glycerol-3-phosphocholine. RNA Sequencing showed significant gene expression differences in the aortas of C57-sham and C57-Hx mice. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that GH inhibited the progression of AS by modulating the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway, a finding that was validated through western blotting. Further in vitro studies demonstrated that GH exerted protective effects on VSMCs against ox-LDL-induced damage through activation of the PI3K/Akt pathway, as evidenced by experiments using the specific PI3K Inhibitor LY294002.

Conclusion: GH alleviates the development of AS through the activation of the PI3K/Akt pathway. The findings of this research emphasize the therapeutic potential of GH in inhibiting AS and highlight the importance of the PI3K/Akt pathway as a promising target for clinical intervention.

PI3K/AKT signaling pathway; atherosclerosis; growth hormone; inflammatory responses; oxidative stress.