Serum apelin as a potential biomarker for infantile hemangiomas.

BACKGROUND: Infantile hemangiomas (IHs) are common benign vascular tumors in infants. Apelin, an endogenous cytokine, is implicated in the angiogenesis of neoplastic diseases. We aimed to explore the association between apelin and IHs, providing a foundation for clinical applications. METHODS: We identified differential expression of apelin in proliferative IHs compared to healthy controls (HCs) through bioinformatics analysis of publicly available databases and verified by Immunofluorescence. Enzyme-linked immunosorbent assay was used to quantify the serum levels of apelin and vascular endothelial growth factor (VEGF) in a cohort of 116 cases of proliferative IHs, 65 cases of capillary malformations (CMs), and 70 HCs. RESULTS: Apelin and APJ (APLNR, apelin receptor) were identified as the significantly upregulated differentially expressed genes (DEGs) in proliferative IHs. Immunofluorescence staining indicated high expression of apelin in proliferative IHs, while minimal expression in non-IH lesions. Apelin in IHs was reduced following 6 months of propranolol treatment. Serum apelin levels were significantly higher in the IH group compared to both the CM and HC groups. Moreover, apelin exhibited excellent discriminatory ability in distinguishing IHs from HCs, with an area under the curve (AUC) exceeding 0.90. A positive correlation was observed between the levels of apelin and the size of superficial IHs. The expression profiles of VEGF and apelin in IHs were found to be consistent. CONCLUSIONS: Apelin shows promise as a potential biomarker for IHs. The association between apelin and IH size, as well as its responsiveness to propranolol treatment, indicates its possible utility as a valuable indicator for the therapeutic evaluation of IHs.

Platelet apelin receptor expression is reduced in patients with acute myocardial infarction.

BACKGROUND: The G-protein-coupled apelin receptor and its apelin ligand are an emerging regulatory system of the vascular homeostasis. To date, the implications of the apelin/apelin receptor system in athero-thrombosis are not completely clarified yet. This study determines the expression of the apelin receptor on human platelets, the effect of different apelin isoforms on platelet aggregation and the potential role of the apelin/apelin receptor system in acute myocardial infarction. METHODS: We applied immunofluorescence staining, Western Blot analysis, aggregometry, and flow cytometry to elucidate the role of the apelin receptor in activated platelets. Furthermore, in an observational pilot study, we assessed platelet apelin recpetor expression and apelin-17 plasma levels in patients with acute myocardial infarction (AMI, n = 27). RESULTS: Immunofluorescence staining indicates that the apelin receptor is located at the cell membrane in resting platelets and diminishes upon activation with a selective thrombin receptor-activating peptide (AP1, 3 to 100 µM). Western Blot analyses of AP1-activated platelets and their supernatants suggest that the apelin receptor is not predominantly internalized but is released from activated platelets. The isoform apelin-17 attenuated AP-1-induced platelet activation in-vitro, presumably via a NO-dependent mechanism. Furthermore, platelet apelin receptor expression was significantly reduced in patients with AMI (n = 27) compared to age-matched controls (n = 14; p < 0.05) and inversely correlated with troponin I plasma levels (r = -0.46; p = 0.03). Besides that, circulating apelin-17 was significantly reduced in MI patients compared to the control group. CONCLUSION: Taken together, our data support a crucial role of the platelet apelinergic system assuming an antithrombotic effect and therefore holding a potential diagnostic and therapeutic impact.

Assessment of apelin, apelin receptor, resistin, and adiponectin levels in the primary tumor and serum of patients with esophageal squamous cell carcinoma.

BACKGROUND: Disturbances in adipokine secretion are associated with the risk of cancer growth and progression. OBJECTIVES: The aim of the study was to evaluate the mRNA expression and protein levels of apelin, the apelin receptor, resistin, and adiponectin in the tumor tissues of surgically treated esophageal squamous cell carcinoma (ESCC) patients. Concentrations of serum adipokines were assessed in relation to ESCC progression. MATERIAL AND METHODS: The study group consisted of 53 patients with ESCC and 27 controls. In the ESCC group, 27 patients were surgically treated and 26 were treated with palliative procedures. RT-PCR and ELISA tests were used to measure the mRNA expression and protein level of adipokines in tissues and their concentration in serum. RESULTS: We found that mRNA expression and protein concentrations of apelin, the apelin receptor and resistin were significantly higher in tumor tissue than in control tissue. The protein concentration of apelin were significantly increased in the tumors of patients with lymph node metastasis (p < 0.005). Circulating levels of apelin, the apelin receptor and resistin were significantly higher in the cancer patients than in controls (p < 0.05 for all). The concentration of serum apelin receptor significantly decreased in patients with stage IV cancer, the presence of lymph node or distant metastasis (p < 0.05). CONCLUSIONS: Apelin may participate in lymphangiogenesis and the progression of ESCC. The apelin receptor is intensely produced in the early stage of cancer development and it may take part in the carcinogenic processes of ESCC.