Acute and Chronic Impact of Bariatric Surgery on Plasma LDL Cholesterol and PCSK9 Levels in Patients With Severe Obesity

Maternal Obesity Modulates Cord Blood Concentrations of Proprotein Convertase Subtilisin/Kexin-type 9 Levels

Context

In utero exposure to maternal obesity or diabetes is considered a pro-inflammatory state.

Objective

To evaluate whether cord blood proprotein convertase subtilisin/kexin-type 9 (PCSK9), which is regulated by inflammation and metabolic derangements, is elevated in neonates born to overweight, obese, or diabetic mothers.

Methods

A retrospective study in full-term neonates born between 2010 and 2023, at Brigham and Women's Hospital. There were 116 neonates included in our study, of which 74 (64%) were born to overweight/obese mothers and 42 (36%) were born to nonoverweight/nonobese mothers.

Results

Neonates born to overweight/obese mothers had significantly higher cord blood concentrations of PCSK9 compared with neonates born to nonoverweight/nonobese group (323 [253-442] ng/mL compared with 270 [244-382] ng/mL, P = .041). We found no significant difference in cord blood concentrations of PCSK9 between neonates of diabetic mothers compared with neonates of nondiabetic mothers. In multivariate linear regression analysis, higher cord plasma PCSK9 concentration was significantly associated with maternal overweight/obesity status (b = 50.12; 95% CI, 4.02-96.22; P = .033), after adjusting for gestational age, birth weight, male sex, and intrauterine growth restriction.

Conclusion

Neonates born to mothers with overweight/obesity have higher cord blood PCSK9 concentrations compared with the nonoverweight/nonobese group, and higher cord blood PCSK9 concentrations were significantly associated with maternal overweight/obesity status, after adjusting for perinatal factors. Larger longitudinal studies are needed to examine the role of PCSK9 in the development of metabolic syndrome in high-risk neonates born to overweight, obese, or diabetic mothers.

Effectiveness of Roux-en-Y Gastric Bypass vs Sleeve Gastrectomy on Lipid Levels in Type 2 Diabetes: a Meta-analysis

INTRODUCTION

Obesity and its co-morbidities, including type 2 diabetes (T2DM) and dyslipidemia, are accompanied by excess cardiovascular morbi-mortality. Aside from excess low density lipoprotein-cholesterol (LDL-C), atherogenic dyslipidemia (AD), mainly characterized by elevated triglycerides and decreased high density lipoprotein-cholesterol (HDL-C) levels, is often present in T2DM obese patients. Bariatric surgery, such as Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), has become a reference treatment in that population. However, the respective effects of RYGB vs SG on lipid metabolism in T2DM patients have been rarely studied.

METHODS

A meta-analysis of randomized controlled trials, comparing the effects of RGYBG vs SG on lipid metabolism 12 months after surgery in T2DM patients, was performed.

RESULTS

Four studies including a total of 298 patients (151 patients in the RYGB and 147 patients in the SG group) were examined. Despite a greater decrease in body mass index and greater improvement in glycemic control in RYGB compared to SG. RYGB vs SG was more effective in reducing total cholesterol, LDL-C, and non-HDL-C levels (mean difference [MD] -26.10 mg/dL, 95 % CI -38.88 to -13.50, p<0.00001; [MD] -20.10 mg/dL, 95 % CI -27.90 to -12.20, p<0.00001 and MD 31.90 mg/dl, 95 % CI -46.90 to -16.80, p<0.00001, respectively).

CONCLUSIONS

The superiority of RYGB vs SG in reducing LDL-C, with an effect comparable to a moderate-intensity statin, suggests RYBG should be favored in hypercholesterolemic T2DM patients in order to further reduce cardiovascular risk.

Effects of bariatric surgery on lipid-lipoprotein profile

Most patients with severe obesity will present some lipid-lipoprotein abnormalities. The atherogenic dyslipidemia associated with severe obesity is characterized by elevated fasting and postprandial triglyceride levels, low high-density lipoprotein cholesterol concentrations, and increased proportion of small and dense low-density lipoproteins. Bariatric surgery has been proven safe and successful in terms of long-term weight loss and improvement in obesity co-existing metabolic conditions including lipid-lipoprotein abnormalities. Nevertheless, bariatric surgery procedures are not all equivalent. We conducted a comprehensive critical analysis of the literature related to severe obesity, bariatric surgery and lipid-lipoprotein metabolism/profile. In this review, we described the metabolic impacts of different bariatric surgery procedures on the lipid-lipoprotein profile, and the mechanisms linking bariatric surgery and dyslipidemia remission based on recent epidemiological, clinical and preclinical studies. Further mechanistic studies are essential to assess the potential of bariatric/metabolic surgery in the management of lipid-lipoprotein abnormalities associated with severe obesity. Understanding the beneficial effects of various bariatric surgery procedures on the lipid-lipoprotein metabolism and profile may result in a wider acceptance of this strategy as a long-term metabolic treatment of lipid-lipoprotein abnormalities in severe obesity and help clinician to develop an individualized and optimal approach in the management of dyslipidemia associated with severe obesity. BRIEF SUMMARY: Abnormal lipid-lipoprotein profile is frequent in patients with severe obesity. Significant improvements in lipid-lipoprotein profile following bariatric surgery occur early in the postoperative period, prior to weight loss, and persists throughout the follow-up. The mechanisms that facilitate the remission of dyslipidemia after bariatric surgery, may involve positive effects on adipose tissue distribution/function, insulin sensitivity, liver fat content/function and lipid-lipoprotein metabolism.

PCSK9: Associated with cardiac diseases and their risk factors?

PCSK9 plays a critical role in cholesterol metabolism via the PCSK9-LDLR axis. Liver-derived, circulating PCSK9 has become a novel drug target in lipid-lowering therapy. Accumulative evidence supports the possible association between PCSK9 and cardiac diseases and their risk factors. PCSK9 exerts various effects in the heart independently of LDL-cholesterol regulation. Acute myocardial infarction (AMI) induces local and systemic inflammation and reactive oxygen species generation, resulting in increased PCSK9 expression in hepatocytes and cardiomyocytes. PCSK9 upregulation promotes excessive autophagy and apoptosis in cardiomyocytes, thereby contributing to cardiac insufficiency. PCSK9 might also participate in the pathophysiology of heart failure by regulating fatty acid metabolism and cardiomyocyte contractility. It also promotes platelet activation and coagulation in patients with atrial fibrillation. PCSK9 is an independent predictor of aortic valve calcification and accelerates calcific aortic valve disease by regulating lipoprotein(a) catabolism. Accordingly, the use of PCSK9 inhibitors significantly reduced infarct sizes and arrhythmia and improves cardiac contractile function in a rat model of AMI. Circulating PCSK9 levels are positively correlated with age, diabetes mellitus, obesity, and hypertension. Here, we reviewed recent clinical and experimental studies exploring the association between PCSK9, cardiac diseases, and their related risk factors and aiming to identify possible underlying mechanisms.

Roux-en-Y gastric bypass, but not sleeve gastrectomy, decreases plasma PCSK9 levels in morbidly obese patients

AIM

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a master regulator of low-density lipoprotein cholesterol (LDL-C) metabolism, acting as an endogenous inhibitor of the LDL receptor. While it has been shown that bariatric surgery differentially affects plasma LDL-C levels, little is known of its effects on plasma PCSK9 concentrations. Therefore, the present study aimed to: (i) investigate the effect of sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) on plasma PCSK9 concentrations; and (ii) correlate baseline or postoperative plasma PCSK9 concentration variations with anthropometric and metabolic parameters.

METHODS

Fasting plasma PCSK9 levels were measured by ELISA in morbidly obese patients before and 6 months after bariatric surgery. Patients were recruited from three prospective cohorts (in Nantes and Colombes in France, and Antwerp in Belgium).

RESULTS

A total of 156 patients (34SG, 122RYGB) were included. Plasma PCSK9, LDL-C and non-high-density lipoprotein cholesterol (non-HDL-C) levels were significantly reduced after RYGB (-19.6%, -16.6% and -19.5%, respectively; P<0.0001), but not after SG. In all patients, postoperative PCSK9 change was positively correlated with fasting plasma glucose (FPG; r=0.22, P=0.007), HOMA-IR (r=0.24, P=0.005), total cholesterol (r=0.17, P=0.037) and non-HDL-C (r=0.17, P=0.038) variations, but not LDL-C. In contrast to what was observed for glucose parameters (FPG, HOMA-IR), correlation between PCSK9 and non-HDL-C changes after RYGB was independent of total weight loss.

CONCLUSION

RYGB, but not SG, promotes a significant reduction in plasma PCSK9 levels, and such changes in circulating PCSK9 levels after RYGB appear to be more associated with glucose improvement than with lipid homoeostasis parameters.

Comparison of Short and Long Term Cardiovascular Outcomes After Bariatric Surgery in Patients With vs Without Coronary Artery Disease

There is little data regarding the risks and benefits of bariatric surgery in patients with coronary artery disease (CAD). We aimed to assess the short- and long-term cardiovascular outcomes of patients with CAD undergoing bariatric surgery. Patients with a history of CAD were identified from a dedicated database with prospectively collected outcomes, comprising all 6795 patients who underwent bariatric surgery between January 1992 and October 2017. Patients were matched with patients who did not have CAD before the bariatric surgery procedure. The primary endpoints were mortality (cardiac and noncardiac) and major adverse cardiocerebral events (MACCE), including all-cause death, myocardial infarction, stroke, and myocardial revascularization at 30 days after bariatric surgery and throughout follow-up. After propensity score matching, 249 patients with chronic CAD were matched with 249 patients without CAD. Throughout follow-up (7.4 years; interquartile range 4.1 to 11.5, maximum 22 years), mortality (mainly cardiac mortality) remained significantly higher in the CAD compared with the non-CAD group (18% vs 10%, hazard ratio [HR] 1.70, 95% confidence interval [CI]: 1.03 to 2.79, p = 0.037). At 30 days, MACCE rate was significantly higher in the CAD compared with the non-CAD group (3.6% vs 0.4%, p = 0.011), essentially driven by non-ST elevation myocardial infarctions. After 30 days, MACCE rates remained significantly higher in the CAD group (30% vs 14%, HR 2.18, 95% CI: 1.45-3.28, p = 0.0002). In conclusion, patients with severe obesity and CAD referred to bariatric surgery were at a higher risk of early and late MACCE compared with non-CAD severely obese patients. Further study is required to define how this cardiovascular risk compares with nonoperated patients.

Effect of Sleeve Gastrectomy on Proprotein Convertase Subtilisin/Kexin Type 9 (Pcsk9) Content and Lipid Metabolism in the Blood Plasma and Liver of Obese Wistar Rats

Nowadays, obesity and its complications are heavy burdens to western civilization. Surgical procedures remain one of the available therapies for obesity and obesity-associated diseases treatment. Among them, sleeve gastrectomy is the most common bariatric procedure. Despite the well-established fact that sleeve gastrectomy results in significant weight loss, some of its other divergent effects still need to be established. To fulfill this knowledge gap, we examined whether sleeve gastrectomy affects lipid metabolism in the plasma and liver of obese rats. We demonstrated that chronic high-fat diet feeding led to an increment in the level of Proprotein Convertase Subtilisin/Kexin (PCSK)-a regulator of plasma cholesterol concentration-in the liver, which was decreased after the gastrectomy. Moreover, we noticed significant increases in both plasma and liver contents of free fatty acids, diacylgycerides and triacylglycerides in the obese animals, with their reduction after the bariatric surgery. In conclusion, we revealed, presumably for the first time, that sleeve gastrectomy affects lipid metabolism in the liver of obese rats.

Acute and chronic effect of bariatric surgery on circulating autotaxin levels

Autotaxin (ATX), an adipose tissue-derived lysophospholipase, has been involved in the pathophysiology of cardiometabolic diseases. The impact of bariatric surgery on circulating ATX levels is unknown. We examined the short- (24 h, 5 days) and longer-term (6 and 12 months) impact of bariatric surgery; as well as the short-term effect of caloric restriction (CR) on plasma ATX levels in patients with severe obesity. We measured ATX levels in 69 men and women (mean age: 41 ± 11 years, body mass index: 49.8 ± 7.1 kg/m2 ), before and after biliopancreatic diversion with duodenal switch surgery (BPD-DS) as well as in a control group (patients with severe obesity without surgery; n = 34). We also measured ATX levels in seven patients with severe obesity and type 2 diabetes who underwent a 3-day CR protocol before their BPD-DS. At baseline, ATX levels were positively associated with body mass index, fat mass, insulin resistance (HOMA-IR) as well as insulin and leptin levels and negatively with fat-free mass. ATX concentrations decreased 26.2% at 24 h after BPD-DS (342.9 ± 152.3 pg/mL to 253.2 ± 68.9 pg/mL, P < 0.0001) and by 16.4% at 12 months after BPD-DS (342.9 ± 152.3 pg/mL to 286.8 ± 182.6 pg/mL, P = 0.04). ATX concentrations were unchanged during follow-up in the control group (P = 0.4), and not influenced by short-term CR. In patients with severe obesity, bariatric surgery induced a rapid and sustained decrease in plasma ATX levels. Acute changes in ATX may not be explained by bariatric surgery-induced CR.