PCSK9 Activity Is Potentiated Through HDL Binding.

Rationale: Proprotein convertase subtilisin/kexin type 9 (PCSK9) circulates in a free and lipoprotein-bound form, yet the functional consequence of the association between PCSK9 and high-density lipoprotein (HDL) remains unexplored. Objective: This study sought to interrogate the novel relationship between PCSK9 and HDL in humans. Methods and Results: Comparing lipoprotein and apolipoprotein profiles by nuclear magnetic resonance and targeted mass spectrometry measurements with PCSK9 levels in the community-based Bruneck (n=656) study revealed a positive association of plasma PCSK9 with small HDL, alongside a highly significant positive correlation between plasma levels of PCSK9 and apolipoprotein-C3, an inhibitor of lipoprotein lipase. The latter association was replicated in an independent cohort, the SAPHIR study (n=270). Thus, PCSK9-HDL association was determined during the postprandial response in two dietary studies (n=20 participants each, 8 times points). Peak triglyceride levels coincided with an attenuation of the PCSK9-HDL association, a loss of apolipoprotein-C3 from HDL and lower levels of small HDL as measured by nuclear magnetic resonance. Crosslinking mass spectrometry (XLMS) upon isolated HDL identified PCSK9 as a potential HDL-binding partner. PCSK9 association with HDL was confirmed through size-exclusion chromatography and immuno-isolation. Quantitative proteomics upon HDL isolated from patients with coronary artery disease (n=172) returned PCSK9 as a core member of the HDL proteome. Combined interrogation of the HDL proteome and lipidome revealed a distinct cluster of PCSK9, phospholipid transfer protein, clusterin and apolipoprotein-E within the HDL proteome, that was altered by sex and positively correlated with sphingomyelin content. Mechanistically, HDL facilitated PCSK9-mediated low-density lipoprotein receptor degradation and reduced low-density lipoprotein uptake through the modulation of PCSK9 internalisation and multimerisation. Conclusions: This study reports HDL as a binder of PCSK9 and regulator of its function. The combination of -omic technologies revealed postprandial lipaemia as a driver of PCSK9 and apolipoprotein-C3 release from HDL.

Inadequate hepcidin serum concentrations predict incident type 2 diabetes mellitus.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is closely associated with elevated body iron stores. The hormone hepcidin is the key regulator of iron homeostasis. Inadequately low hepcidin levels were recently reported in subjects with manifest T2DM. We investigated whether alterations of hepcidin levels precede the manifestation of T2DM and predict T2DM development independently of established risk conditions. METHODS: This prospective population-based study included 675 subjects aged 50-89 years, 51.9% of whom were female. Hepcidin levels were measured by gold standard tandem mass spectrometry. Diabetes was diagnosed according to American Diabetes Association criteria, and incident diabetes was recorded between baseline in 2000 and 2010. RESULTS: The baseline hepcidin-to-ferritin ratio in subjects that subsequently developed diabetes during follow-up was reduced on average by 29.8% as compared with subjects with normal glucose tolerance (95% confidence interval, -50.7% to -0.2%; p = 0.049). After adjustment for age, sex, and serum ferritin, higher hepcidin levels were associated with reduced risk of incident diabetes (hazard ratio per 1-unit higher log2 hepcidin, 0.80; 95% confidence interval, 0.64-0.98; p = 0.035; 33 events). Additional adjustment for established diabetes risk factors and determinants of hepcidin concentration did not appreciably change these results (HR, 0.81; 95% CI, 0.66-0.99). Likewise, inadequately low hepcidin levels were also detected in subjects with prevalent T2DM (n = 76). CONCLUSIONS: Hepcidin levels that are inadequately low in relation to body iron stores are an independent predictor for incident T2DM and may contribute to diabetes-related tissue iron overload. Copyright © 2015 John Wiley & Sons, Ltd.

Long-term life history predicts current gut microbiome in a population-based cohort study.

Extensive scientific and clinical microbiome studies have explored contemporary variation and dynamics of the gut microbiome in human health and disease1-3, yet the role of long-term life history effects has been underinvestigated. Here, we analyzed the current, quantitative microbiome composition in the older adult Bruneck Study cohort (Italians, Bruneck, n = 304 (male, 154; female, 150); age 65-98 years) with extensive clinical, demographic, lifestyle and nutritional data collected over the past 26 years4. Multivariate analysis of historical variables indicated that medication history, historical physical activity, past dietary habits and specific past laboratory blood parameters explain a significant fraction of current quantitative microbiome variation in older adults, enlarging the explanatory power of contemporary covariates by 33.4%. Prediction of current enterotype by a combination of past and contemporary host variables revealed good levels of predictability (area under the curve (AUC), 0.78-0.83), with Prevotella and dysbiotic Bacteroides 2 being the best predicted enterotypes. These findings demonstrate long-term life history effects on the microbiota and provide insights into lifestyle variables and their role in maintaining a healthy gut microbiota in later life.

Lipoprotein-associated phospholipase A2 activity, ferritin levels, metabolic syndrome, and 10-year cardiovascular and non-cardiovascular mortality: results from the Bruneck study.

AIMS: To identify factors that influence plasma levels and assess the prognostic value of lipoprotein-associated phospholipase A2 (Lp-PLA2) activity in a prospective, population-based survey of the epidemiology and pathogenesis of atherosclerosis. METHODS AND RESULTS: The Bruneck study is a prospective, population-based survey initiated in 1990. Lp-PLA2 activity and baseline variables for the current analysis were measured in 765 subjects aged 45-84 years in 1995. Incident cardiovascular disease (CVD) (cardiovascular death, myocardial infarction, stroke, and transient ischaemic attack) and rates of non-CVD mortality were assessed between 1995 and 2005. Subjects with incident CVD had higher levels of Lp-PLA2 activity (884 +/- 196 vs. 771 +/- 192 micromol/min/L, P < 0.001). Increased Lp-PLA2 activity was significantly related to incident CVD [age- and sex-adjusted hazard ratio (95%CI) 2.9 (1.6-5.5); third vs. first tertile group; P < 0.001] and with vascular mortality but not with non-CVD mortality. Lp-PLA2 activity was enhanced in subjects with the metabolic syndrome and showed highly significant positive associations with LDL-C, apoB-100, ferritin, and HOMA-IR, and inverse associations with HDL-C and anti-oxidant levels. CONCLUSION: Increased Lp-PLA2 activity is associated with metabolic syndrome and incident fatal and non-fatal CVD, but not with non-CVD mortality. Furthermore, Lp-PLA2 activity is strongly influenced by ferritin levels, LDL-C, and apoB-100 supporting its integral role in lipid peroxidation. Clinical utility of Lp-PLA2 activity for prediction of cardiovascular risk has to be explored in future studies.

Cardiovascular Risk Factors Associated With Venous Thromboembolism.

Importance: It is uncertain to what extent established cardiovascular risk factors are associated with venous thromboembolism (VTE). Objective: To estimate the associations of major cardiovascular risk factors with VTE, ie, deep vein thrombosis and pulmonary embolism. Design, Setting, and Participants: This study included individual participant data mostly from essentially population-based cohort studies from the Emerging Risk Factors Collaboration (ERFC; 731 728 participants; 75 cohorts; years of baseline surveys, February 1960 to June 2008; latest date of follow-up, December 2015) and the UK Biobank (421 537 participants; years of baseline surveys, March 2006 to September 2010; latest date of follow-up, February 2016). Participants without cardiovascular disease at baseline were included. Data were analyzed from June 2017 to September 2018. Exposures: A panel of several established cardiovascular risk factors. Main Outcomes and Measures: Hazard ratios (HRs) per 1-SD higher usual risk factor levels (or presence/absence). Incident fatal outcomes in ERFC (VTE, 1041; coronary heart disease [CHD], 25 131) and incident fatal/nonfatal outcomes in UK Biobank (VTE, 2321; CHD, 3385). Hazard ratios were adjusted for age, sex, smoking status, diabetes, and body mass index (BMI). Results: Of the 731 728 participants from the ERFC, 403 396 (55.1%) were female, and the mean (SD) age at the time of the survey was 51.9 (9.0) years; of the 421 537 participants from the UK Biobank, 233 699 (55.4%) were female, and the mean (SD) age at the time of the survey was 56.4 (8.1) years. Risk factors for VTE included older age (ERFC: HR per decade, 2.67; 95% CI, 2.45-2.91; UK Biobank: HR, 1.81; 95% CI, 1.71-1.92), current smoking (ERFC: HR, 1.38; 95% CI, 1.20-1.58; UK Biobank: HR, 1.23; 95% CI, 1.08-1.40), and BMI (ERFC: HR per 1-SD higher BMI, 1.43; 95% CI, 1.35-1.50; UK Biobank: HR, 1.37; 95% CI, 1.32-1.41). For these factors, there were similar HRs for pulmonary embolism and deep vein thrombosis in UK Biobank (except adiposity was more strongly associated with pulmonary embolism) and similar HRs for unprovoked vs provoked VTE. Apart from adiposity, these risk factors were less strongly associated with VTE than CHD. There were inconsistent associations of VTEs with diabetes and blood pressure across ERFC and UK Biobank, and there was limited ability to study lipid and inflammation markers. Conclusions and Relevance: Older age, smoking, and adiposity were consistently associated with higher VTE risk.

Higher spermidine intake is linked to lower mortality: a prospective population-based study.

Background: Spermidine administration is linked to increased survival in several animal models. Objective: The aim of this study was to test the potential association between spermidine content in diet and mortality in humans. Design: This prospective community-based cohort study included 829 participants aged 45-84 y, 49.9% of whom were male. Diet was assessed by repeated dietitian-administered validated food-frequency questionnaires (2540 assessments) in 1995, 2000, 2005, and 2010. During follow-up between 1995 and 2015, 341 deaths occurred. Results: All-cause mortality (deaths per 1000 person-years) decreased across thirds of increasing spermidine intake from 40.5 (95% CI: 36.1, 44.7) to 23.7 (95% CI: 20.0, 27.0) and 15.1 (95% CI: 12.6, 17.8), corresponding to an age-, sex- and caloric intake-adjusted 20-y cumulative mortality incidence of 0.48 (95% CI: 0.45, 0.51), 0.41 (95% CI: 0.38, 0.45), and 0.38 (95% CI: 0.34, 0.41), respectively. The age-, sex- and caloric ratio-adjusted HR for all-cause death per 1-SD higher spermidine intake was 0.74 (95% CI: 0.66, 0.83; P < 0.001). Further adjustment for lifestyle factors, established predictors of mortality, and other dietary features yielded an HR of 0.76 (95% CI: 0.67, 0.86; P < 0.001). The association was consistent in subgroups, robust against unmeasured confounding, and independently validated in the Salzburg Atherosclerosis Prevention Program in Subjects at High Individual Risk (SAPHIR) Study (age-, sex-, and caloric ratio-adjusted HR per 1-SD higher spermidine intake: 0.71; 95% CI: 0.53, 0.95; P = 0.019). The difference in mortality risk between the top and bottom third of spermidine intakes was similar to that associated with a 5.7-y (95% CI: 3.6, 8.1 y) younger age. Conclusion: Our findings lend epidemiologic support to the concept that nutrition rich in spermidine is linked to increased survival in humans. This trial was registered at www.clinicaltrials.gov as NCT03378843.