Expression of ApoA5 and its function in the right ventricular failing and remodeling secondary to pulmonary hypertension

Apolipoprotein A5 ameliorates MCT induced pulmonary hypertension by inhibiting ER stress in a GRP78 dependent mechanism

Background

Pulmonary arterial hypertension (PAH) is a chronic, progressive lung vascular disease accompanied by elevated pulmonary vascular pressure and resistance, and it is characterized by increased pulmonary artery smooth muscle cell (PASMC) proliferation. Apolipoprotein A5 (ApoA5) improves monocrotaline (MCT)-induced PAH and right heart failure; however, the underlying mechanism remains unknown. Here we speculate that ApoA5 has a protective effect in pulmonary vessels and aim to evaluate the mechanism.

Methods

ApoA5 is overexpressed in an MCT-induced PAH animal model and platelet-derived growth factor (PDGF)-BB-induced proliferating PASMCs. Lung vasculature remodeling was measured by immunostaining, and PASMC proliferation was determined by cell counting kit‐8 and 5‐ethynyl‐2'‐deoxyuridine5‐ethynyl‐2'‐deoxyuridine incorporation assays. Coimmunoprecipitation-mass spectrometry was used to investigate the probable mechanism. Next, its role and mechanism were further verified by knockdown studies.

Results

ApoA5 level was decreased in MCT-induced PAH lung as well as PASMCs. Overexpression of ApoA5 could help to inhibit the remodeling of pulmonary artery smooth muscle. ApoA5 could inhibit PDGF-BB-induced PASMC proliferation and endoplasmic reticulum stress by increasing the expression of glucose-regulated protein 78 (GRP78). After knocking down GRP78, the protecting effects of ApoA5 have been blocked.

Conclusion

ApoA5 ameliorates MCT-induced PAH by inhibiting endoplasmic reticulum stress in a GRP78 dependent mechanism.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01680-4.

Association of Serum Apolipoprotein A5 Concentration with Nonalcoholic Fatty Liver Disease in Ningbo, China

Nonalcoholic fatty liver disease (NAFLD) is a common chronic disease characterized by the excessive accumulation of hepatocyte fat and steatosis in the absence of alcohol or any other clear contributing factors to liver injury. NAFLD has been confirmed to be closely associated with obesity, insulin resistance, and dyslipidemia. Genetic polymorphism studies have shown the relations between the apolipoprotein A5 gene (APOA5) and NAFLD. However, the association between the serum ApoA5 level and NAFLD remains unclear. Between September 2018 and August 2019, adults who attended the hospital-based health checkup center were enrolled in this study. Anthropometric examination, laboratory investigations on fasting blood, and abdominal ultrasonography were performed. The serum ApoA5 level was determined by enzyme-linked immunosorbent assay. A total of 517 eligible participants (317 females and 200 males) were involved in this study, with a mean age of 54.7 ± 16.7 years. The mean ApoA5 concentration was 28.8 ± 4.7 μg/ml, among which the males had higher concentration levels than females (29.3 ± 4.5 vs. 28.5 ± 4.7 μg/mL, P=0.04). Serum ApoA5 level was not significantly correlated with NAFLD or metabolic profiles. However, the prevalence rate of hypertriglyceridemia (triglyceride ≥ 1.7 mmol/L) showed a significant inverted “U”-shaped trend in individuals with the serum ApoA5 level of quartile one to quartile four after adjusting the confounding factors. Moreover, individuals with higher serum ApoA5 levels were also more likely to suffer from hyperglycemia. The ApoA5 levels and the prevalence of hypertriglyceridemia are in an inverted “U-shaped” correlation, but there is no significant difference between ApoA5 levels, NAFLD, and metabolic syndrome.