Proprotein Convertase Subtilisin Kexin Type 9 (PCSK9) Beyond Lipids: The Role in Oxidative Stress and Thrombosis.

Proprotein convertase subtilisin/kexin type 9 (PCSK9), mainly secreted in the liver, is a key regulator of cholesterol homeostasis inducing LDL receptors' degradation. Beyond lipid metabolism, PCSK9 is involved in the development of atherosclerosis, promoting plaque formation in mice and human, impairing the integrity of endothelial monolayer and promoting the events that induce atherosclerosis disease progression. In addition, the PCSK9 ancillary role in the atherothrombosis process is widely debated. Indeed, recent evidence showed a regulatory effect of PCSK9 on redox system and platelet activation. In particular, the role of PCSK9 in the activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox2) system, of MAP-kinase cascades and of CD36 and LOX-1 downstream pathways, suggests that PCSK9 may be a significant cofactor in atherothrombosis development. This evidence suggests that the serum levels of PCSK9 could represent a new biomarker for the occurrence of cardiovascular events. Finally, other evidence showed that PCSK9 inhibitors, a novel pharmacological tool introduced in clinical practice in recent years, counteracted these phenomena. In this review, we summarize the evidence concerning the role of PCSK9 in promoting oxidative-stress-related atherothrombotic process.

Insulin resistance and NAFLD may influence memory performance in obese patients with prediabetes or newly-diagnosed type 2 diabetes.

BACKGROUND AND AIMS: Diabetes has consistently been shown to increase risk for cognitive decline. Cognitive deficits may occur at the very earliest stages of diabetes. We sought to estimate the determinants of memory function in a group of middle-aged obese subjects with prediabetes or newly-diagnosed type 2 diabetes mellitus. METHODS AND RESULTS: Sixty-two obese patients in treatment with metformin-with prediabetes (n = 41) or newly diagnosed T2DM (n = 21), were studied. Short- and long-term memory function was assessed through a neuropsychological assessment consisting of two tests and a composite domain z score was calculated. Cardiometabolic variables, such as abdominal MRI quantification of subcutaneous (SAT) and visceral (VAT) adipose tissue content, and of intra-hepatocellular lipid content, as well as insulin sensitivity (Matsuda Index, HOMA-IR) and beta cell performance (Beta Index), by multiple sampling, 8-point oral glucose tolerance test, were also evaluated. Age, non-alcoholic fatty liver disease (NAFLD), and lnHOMA-IR together explained 18% (R square) of the variance in memory domain. Including NAFLD increased the explained variance by 8% and including lnHOMA-IR by 9.1%, whereas the contribution of age and other factors was negligible. CONCLUSION: Preventing and managing insulin resistance in precocious and possibly earlier stages of diabetes might provide benefit in slowering down future cognitive decline.

Sex-Specific Association of Endogenous PCSK9 With Memory Function in Elderly Subjects at High Cardiovascular Risk.

Background: Growing evidence indicates that cognitive decline and cardiovascular diseases (CVDs) share common vascular risk factors. Protease proprotein convertase subtilisin/kexin type 9 (PCSK9) is associated with CV disease risk and has been also involved in neuronal differentiation. Aim: Evaluate whether in patients at high CV risk cognitive function is related to PCSK9 levels. Methods. One hundred sixty-six patients (67 female) were enrolled. A detailed neuropsychological (NP) assessment was performed. PCSK9 levels were measured with ELISA. Results: Men had significantly higher short-term memory, executive function, and praxic and mental representation skills, as reflected by Forward Digit Span (FDS) (p = 0.005), Trail Making Test-A (TMT-A) (p = 0.047), Clock Drawing Test (CDT) (0.016). Endogenous PCSK9 levels were higher in female (p = 0.005). On linear regression analysis PCSK9 predicts short term memory only in females (Beta = 0.408, p = 0.001), with an interaction between PCSK9 and gender (p = 0.004 for interaction PCSK9 by sex). The association of PCSK9 with FDS in female was partially mediated by waist circumference (mediation effect 8.5%). Conclusions: In patients at high CV risk short term memory was directly related to PCSK9 levels only in women, revealing the relevance of sex in this relationship. The association of PCSK9 with memory function may be mediated, at least in part, by waist circumference.

Liraglutide improves memory in obese patients with prediabetes or early type 2 diabetes: a randomized, controlled study.

BACKGROUND/OBJECTIVES: Diabetic subjects are at increased risk of subtle cognitive impairment since the disease early stages and of dementia later in life. In animal models, glucagon-like peptide-1 receptor agonizts (GLP1-RAs) have been shown to exert neuroprotective effects, expecially in the memory domain. We assessed whether treatment with a GLP1-RA might affect cognitive functions in type 2 diabetic subjects independently on the weight loss it might induce. SUBJECTS/METHODS: Forty metformin-treated obese subjects with prediabetes or newly diagnosed type 2 diabetes mellitus, received liraglutide (1.8 mg/d) (n = 20) or lifestyle counseling (dietary intervention and exercise training) (n = 20) until achieving a modest and comparable weight loss (-7% of initial body weight). INTERVENTIONS/METHODS: A detailed neuropsychological assessment before and after weight loss was completed in 16 patients per arm, who were administered a total of seven psychological tests, thus assessing three composite domain z-scores for attention, memory, and executive control. RESULTS: After comparable weight loss and superimposable glycemic control and insulin sensitivity, a significant increase in short term memory (mean Digit Span Z score from -0.06 to 0.80, p = 0.024) and memory composite z-score (mean memory z-score from -0.67 to 0.032, p = 0.0065) was observed in the liraglutide exposed subjects (between group p = 0.041 and p = 0.033, respectively). CONCLUSIONS: Liraglutide might slow down memory function decline in diabetic patients in early, and possibly preclinical stages of the disease.

Effects of Liraglutide on Weight Loss, Fat Distribution, and ß-Cell Function in Obese Subjects With Prediabetes or Early Type 2 Diabetes.

OBJECTIVE: Obesity is associated with an increased risk of type 2 diabetes and cardiovascular complications. The risk depends significantly on adipose tissue distribution. Liraglutide, a glucagon-like peptide 1 analog, is associated with weight loss, improved glycemic control, and reduced cardiovascular risk. We determined whether an equal degree of weight loss by liraglutide or lifestyle changes has a different impact on subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) in obese subjects with prediabetes or early type 2 diabetes. RESEARCH DESIGN AND METHODS: Sixty-two metformin-treated obese subjects with prediabetes or newly diagnosed type 2 diabetes, were randomized to liraglutide (1.8 mg/day) or lifestyle counseling. Changes in SAT and VAT levels (determined by abdominal MRI), insulin sensitivity (according to the Matsuda index), and ß-cell function (ß-index) were assessed during a multiple-sampling oral glucose tolerance test; and circulating levels of IGF-I and IGF-II were assessed before and after a comparable weight loss (7% of initial body weight). RESULTS: After comparable weight loss, achieved by 20 patients per arm, and superimposable glycemic control, as reflected by HbA1c level (P = 0.60), reduction in VAT was significantly higher in the liraglutide arm than in the lifestyle arm (P = 0.028), in parallel with a greater improvement in ß-index (P = 0.021). No differences were observed in SAT reduction (P = 0.64). IGF-II serum levels were significantly increased (P = 0.024) only with liraglutide administration, and the increase in IGF-II levels correlated with both a decrease in VAT (ρ = -0.435, P = 0.056) and an increase in the ß-index (ρ = 0.55, P = 0.012). CONCLUSIONS: Liraglutide effects on visceral obesity and ß-cell function might provide a rationale for using this molecule in obese subjects in an early phase of glucose metabolism dysregulation natural history.