A previously unreported impact of a PLA2G7 gene polymorphism on the plasma levels of lipoprotein-associated phospholipase A2 activity and mass

Phospholipid metabolism-related genotypes of PLA2R1 and CERS4 contribute to nonobese MASLD

BACKGROUND

Abnormal phospholipid metabolism is linked to metabolic dysfunction-associated steatotic liver disease (MASLD) development and progression. We aimed to clarify whether genetic variants of phospholipid metabolism modify these relationships.

METHODS

This case-control study consecutively recruited 600 patients who underwent MRI-based proton density fat fraction examination (240 participants with serum metabonomics analysis, 128 biopsy-proven cases) as 3 groups: healthy control, nonobese MASLD, and obese MASLD, (n = 200 cases each). Ten variants of phospholipid metabolism-related genes [phospholipase A2 Group VII rs1805018, rs76863441, rs1421378, and rs1051931; phospholipase A2 receptor 1 (PLA2R1) rs35771982, rs3828323, and rs3749117; paraoxonase-1 rs662 and rs854560; and ceramide synthase 4 (CERS4) rs17160348)] were genotyped using SNaPshot.

RESULTS

The T-allele of CERS4 rs17160348 was associated with a higher risk of both obese and nonobese MASLD (OR: 1.95, 95% CI: 1.20-3.15; OR: 1.76, 95% CI: 1.08-2.86, respectively). PLA2R1 rs35771982-allele is a risk factor for nonobese MASLD (OR: 1.66, 95% CI: 1.11-1.24), moderate-to-severe steatosis (OR: 3.24, 95% CI: 1.96-6.22), and steatohepatitis (OR: 2.61, 95% CI: 1.15-3.87), while the paraoxonase-1 rs854560 T-allele (OR: 0.50, 95% CI: 0.26-0.97) and PLA2R1 rs3749117 C-allele (OR: 1.70, 95% CI: 1.14-2.52) are closely related to obese MASLD. After adjusting for sphingomyelin level, the effect of the PLA2R1 rs35771982CC allele on MASLD was attenuated. Furthermore, similar effects on the association between the CERS4 rs17160348 C allele and MASLD were observed for phosphatidylcholine, phosphatidic acid, sphingomyelin, and phosphatidylinositol.

CONCLUSIONS

The mutations in PLA2R1 rs35771982 and CERS4 rs17160348 presented detrimental impact on the risk of occurrence and disease severity in nonobese MASLD through altered phospholipid metabolism.

Associations of genetic variants of lysophosphatidylcholine metabolic enzymes with levels of serum lipids

OBJECTIVE

Metabolic disturbance of lysophosphatidylcholine (LPC) is related with dyslipidemia. Therefore, eight single-nucleotide polymorphisms (SNPs) were selected from LPC metabolic enzymes to study their associations with obesity and serum levels of lipids.

METHODS

A total of 3305 children were recruited from four independent studies. Eight SNPs of LPC metabolic enzymes were selected and genotyped with the matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The multivariable linear regression model was applied to detect the associations of eight SNPs with obesity-related phenotypes and levels of lipids in each study. Meta-analyses were used to combine the results of four studies.

RESULTS

Only SNP rs4420638 of APOC-1 gene was associated with serum lipids even after Bonferroni correction. The rs4420638 was positively associated with TC (β = 0.15, P = 8.59 × 10^-9) and low-density-lipoprotein-cholesterol (LDL-C, β = 0.16, P = 9.98 × 10^-14) individually.

CONCLUSION

The study firstly revealed the association between APOC-1/rs4420638 and levels of serum lipids in Chinese children, providing evidence for susceptible gene variants of dyslipidemia.

On the present and future role of Lp-PLA2 in atherosclerosis-related cardiovascular risk prediction and management

Circulating concentration and activity of secretory phospholipase A₂ (sPLA₂) and lipoprotein-associated phospholipase A₂ (Lp-PLA₂) have been proven as biomarkers of increased risk of atherosclerosis-related cardiovascular disease (ASCVD). Lp-PLA₂ might be part of the atherosclerotic process and may contribute to plaque destabilisation through inflammatory activity within atherosclerotic lesions. However, all attempts to translate the inhibition of phospholipase into clinically beneficial ASCVD risk reduction, including in randomised studies, by either non-specific inhibition of sPLA₂ (by varespladib) or specific Lp-PLA₂ inhibition by darapladib, unexpectedly failed. This gives us a strong imperative to continue research aimed at a better understanding of how Lp-PLA₂ and sPLA₂ regulate vascular inflammation and atherosclerotic plaque development. From the clinical viewpoint there is a need to establish and validate the existing and emerging novel anti-inflammatory therapeutic strategies to fight against ASCVD development, by using potentially better animal models and differently designed clinical trials in humans.

Lipoprotein-associated phospholipase A2: The story continues

Inflammation is thought to play an important role in the pathogenesis of vascular diseases. Lipoprotein-associated phospholipase A2 (Lp-PLA2) mediates vascular inflammation through the regulation of lipid metabolism in blood, thus, it has been extensively investigated to identify its role in vascular inflammation-related diseases, mainly atherosclerosis. Although darapladib, the most advanced Lp-PLA2 inhibitor, failed to meet the primary endpoints of two large phase III trials in atherosclerosis patients cotreated with standard medical care, the research on Lp-PLA2 has not been terminated. Novel pathogenic, epidemiologic, genetic, and crystallographic studies regarding Lp-PLA2 have been reported recently, while novel inhibitors were identified through a fragment-based lead discovery strategy. More strikingly, recent clinical and preclinical studies revealed that Lp-PLA2 inhibition showed promising therapeutic effects in diabetic macular edema and Alzheimer's disease. In this review, we not only summarized the knowledge of Lp-PLA2 established in the past decades but also emphasized new findings in recent years. We hope this review could be valuable for helping researchers acquire a much deeper insight into the nature of Lp-PLA2, identify more potent and selective Lp-PLA2 inhibitors, and discover the potential indications of Lp-PLA2 inhibitors.

Lipoprotein-associated phospholipase A2 and oxidized low-density lipoprotein in young patients with acute coronary syndrome in China

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is considered to be a risk factor for acute coronary syndrome (ACS), but this remains controversial. This study investigated the role of Lp-PLA2 in young Chinese patients with ACS. 228 young patients (aged ≤55 years) with ACS and 237 age-matched controls were included. Lp-PLA2 and oxidized low-density lipoprotein (ox-LDL) levels were measured by sandwich enzyme-linked immunosorbent assay. Lp-PLA2 levels were significantly correlated with smoking, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and ox-LDL levels (all P < 0.05). Multivariate logistic regression analysis showed that male sex (OR = 3.25, 95%CI = 1.26–8.38), smoking (OR = 3.50, 95%CI = 1.75–7.0), triglyceride (OR = 1.76, 95%CI = 1.08–2.87), high sensitivity C-reactive protein (hs-CRP) (OR = 2.11, 95%CI = 1.14–3.90) and ox-LDL (OR = 2.98, 95%CI = 1.72–5.1) were independently associated with ACS risk in young patients. Lp-PLA2 was associated with risk of ACS in young patients when adjusted for traditional risk factors, including age, sex, diabetes, hypertension, smoking, TC, LDL-C, triglyceride and hs-CRP (OR = 1.98, 95%CI = 1.10–3.56). When further adjusted for ox-LDL levels, the association between Lp-PLA2 and ACS became insignificant (OR = 1.69, 95%CI = 0.90–3.17). Lp-PLA2 was a marker of oxidative stress and inflammation, rather than an independent risk factor for ACS in young Chinese patients.

Apolipoprotein E-containing high-density lipoprotein (HDL) modifies the impact of cholesterol-overloaded HDL on incident coronary heart disease risk: A community-based cohort study

BACKGROUND

Experimental studies have shown that cholesterol-overloaded high-density lipoprotein (HDL) can promote the formation of apolipoprotein E (APOE)-containing HDL, a process correcting the atherogenic function of cholesterol-overloaded HDL.

OBJECTIVE

The objective of the study was to explore whether APOE-containing HDL can attenuate the defective impact of cholesterol-overloaded HDL on the development of coronary heart disease (CHD) in humans.

METHODS

We measured APOE-HDL cholesterol (APOE-HDLC), HDL cholesterol (HDLC), and HDL particle number in 1112 participants aged 45 to 74 years at baseline in a community-based cohort study. Cholesterol molecules per HDL particle (HDL-C/P ratio) were calculated as the ratio of HDLC to HDL particle number. The ratio of APOE-HDLC to total HDLC (APOE-HDLC/HDLC ratio) was calculated to assess the relative proportion of APOE-HDLC in total HDLC.

RESULTS

The HDL-C/P ratio was strongly correlated with APOE-HDLC (partial-r: 0.615). Participants with cholesterol-overloaded HDL (indicated by the highest level of the HDL-C/P ratio) had a high APOE-HDLC/HDLC ratio. Baseline cholesterol-overloaded HDL significantly increased the 10-year risk of incident CHD (hazard ratio = 2.42; 95% confidence interval = 1.06-8.32), but this was attenuated by an increased APOE-HDLC/HDLC ratio. Participants with high HDL-C/P ratio and APOE-HDLC/HDLC ratio had a 42% lower risk, whereas those with a high HDL-C/P ratio and low APOE-HDLC/HDLC ratio had a 2.54-fold higher risk, than those with low HDL-C/P ratio and APOE-HDLC/HDLC ratio after multiple adjustments.

CONCLUSION

Cholesterol-overloaded HDLs are related with increased APOE-containing HDL species. APOE-containing HDL was found to attenuate the impact of cholesterol-overloaded HDL on increased incident CHD risk, suggesting that APOE-containing HDL may correct the dysfunction of cholesterol-overloaded HDL.