👤 A Kent

Mendelian randomization studies suggest a causal effect of lipoprotein(a) (Lp(a)) on atherosclerotic cardiovascular disease. Noncardiovascular effects (eg, diabetes risk) are inadequately investigated. In this noninterventional phenome-wide association study designed to better understand the potential causal role of Lp(a), direct causal phenotypic effects of exposure to Lp(a) were estimated. Also, the association between LPA null allele rs41272114 with type 2 diabetes was assessed, and ancestry-specific Lp(a) thresholds were determined. In the UK Biobank (n = 425,677 adults, 55% female), we studied 1,456 phenotypes spanning 18 classes using 4 ancestry-specific polygenic risk scores and false discovery rate multiple testing correction. Network deconvolution Mendelian randomization was leveraged to separate direct from indirect (ie, associations via mediating variables) causal phenotypic effects and account for confounding, reverse causation, and bidirectionality. Lp(a) was significantly associated with 80 phenotypes across 7 classes. Higher Lp(a) exposure had significant direct causal effects, independent of low-density lipoprotein cholesterol, on coronary artery disease (OR: 1.36; 95% CI: 1.21-1.54) and glycated hemoglobin (HbA1c; β = 0.099; 95% CI: 0.051-0.15) only. Very low Lp(a) exposure was not associated with type 2 diabetes (OR: 0.92; 95% CI: 0.64-1.31) or HbA1c (β = -0.016; 95% CI: -0.062 to 0.030). Among European and African ancestries, 86 (77th percentile) and 93 (59th percentile) nmol/L optimally discriminated myocardial infarction risk, respectively. Increasing Lp(a) exposure had direct, independent causal effects on coronary artery disease and HbA1c only; very low Lp(a) exposure is suggested to not be causally associated with type 2 diabetes. The optimal European and African ancestry threshold to stratify cardiovascular risk is comparable, and below 125/105 nmol/L in current U.S./European medical professional society guidelines. Show less

Apolipoprotein B (apoB) distribution and its implications as an atherosclerotic cardiovascular disease (ASCVD) risk-enhancing factor among individuals of diverse Hispanic or Latino backgrounds have not been described. To describe the distribution of apoB in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) cohort and to characterize associations of baseline sociodemographic and clinical variables with apoB and self-identified Hispanic or Latino background. The HCHS/SOL was a prospective, population-based cohort study of diverse Hispanic or Latino adults living in the US who were recruited and screened between March 2008 and June 2011. Sampling weights were used to generate a population-based sample of Hispanic or Latino participants aged 18 to 74 years who resided in 4 US metropolitan areas (Bronx, New York; Chicago, Illinois; Miami, Florida; and San Diego, California). ApoB concentration was measured in participants from the HCHS/SOL, and apoB tertiles were compared across demographic groups, including self-identified Hispanic or Latino background. Median percentage continental genetic ancestry (West African, Amerindian, and European) was compared across apoB tertiles. ApoB measured in mg/dL from serum or plasma using an immunoturbidimetric assay. ApoB tertiles were determined, and traditional lipids were evaluated across apoB tertiles. ApoB and traditional lipid measurements were assessed across ASCVD risk categories. Additionally, scatterplots were created to observe correlations between apoB and low-density lipoprotein cholesterol or non-high-density lipoprotein cholesterol. Overall mean (SD) apoB concentration was 99.8 (0.4) mg/dL, with male participants displaying significantly higher mean levels than female participants (102.4 vs 97.4 mg/dL, respectively). Mean (SD) participant age was 41.1 (0.8) years, and 8376 participants (51.9%) were female. ApoB levels were higher among older age groups. There was significant heterogeneity in mean apoB concentrations across self-identified Hispanic or Latino background groups, ranging from 95.1 mg/dL in Dominican individuals to 104.8 mg/dL in Cuban individuals. The prevalence of elevated apoB (≥130 mg/dL) was greater across higher predicted ASCVD risk categories. Among participants with a 10-year predicted ASCVD risk of 7.5% or higher, 26.5% had an elevated apoB. Median West African ancestry was lower across higher tertiles of apoB. In this cohort study among participants from the HCHS/SOL, elevated apoB was present in one-quarter of a diverse cohort study of Hispanic or Latino individuals who were at intermediate or high predicted ASCVD risk. Differences in apoB distribution among Hispanic or Latino individuals may have important implications for apoB's use in ASCVD risk assessment. Show less

Lipoprotein(a) [Lp(a)] is associated with atherosclerotic cardiovascular disease. An Lp(a) threshold of ≥125 nmol/L is commonly used to identify individuals at higher risk for events, but there is a paucity of data on individuals of Hispanic/Latino descent. The purpose of this study was to provide a comprehensive evaluation of Lp(a) and its association with 10-year cardiovascular disease risk and mortality among Hispanic/Latino adults in the United States. We evaluated the association between Lp(a) and myocardial infarction (MI), ischemic stroke, and all-cause mortality among 16,117 Hispanic Community Health Study/Study of Latinos individuals. Event rates were compared across Lp(a) quintiles. Multivariable Cox proportional hazards models assessed the relationship between events and Lp(a) across increasing quintiles, log-transformed Lp(a), and ≥125 nmol/L vs <125 nmol/L. Sampling weights and survey methods were used to account for the stratified probability sampling of the cohort. Among the Hispanic Community Health Study/Study of Latinos target population (median age 41.1 years, 52.4% women), the median Lp(a) was 19.7 nmol/L (Q1-Q3: 7.3-60.6 nmol/L), with 11.4% having Lp(a) ≥125 nmol/L, and the highest Lp(a) quintile defined as >77 nmol/L. Over a median follow-up of 9.8 years, 883 events (135 MI, 99 stroke, 649 all-cause mortality) occurred. The age-adjusted incidence rate of the composite events (MI, stroke, and all-cause mortality) was 505.2 per 100,000 person-years. After multivariable adjustment, each 1-SD increase in log-transformed Lp(a) was associated with a higher risk of MI (HR: 1.47; 95% CI: 1.14-1.89). Compared with Lp(a) <125 nmol/L, elevated Lp(a) ≥125 nmol/L conferred an increased risk of MI (HR: 2.29; 95% CI: 1.45-3.63), all-cause mortality (HR: 1.43; 95% CI: 1.05-1.93), and composite events (HR: 1.56; 95% CI: 1.22-2.01), but not stroke. Findings were consistent when comparing the highest Lp(a) quintile to the lower 4 quintiles, but the elevated risk was observed only for MI and composite events. Hispanic/Latino individuals with elevated Lp(a) are at an increased risk of MI and all-cause mortality. Although Lp(a) ≥125 nmol/L is a valid risk threshold, Hispanics/Latinos show a continuous relationship between increasing Lp(a) levels and MI risk. Show less

Fetal development is modulated by maternal nutrition during pregnancy. The dietary intake of linoleic acid (LA), an essential dietary n-6 polyunsaturated fatty acid (PUFA), has increased. We previously published that increased LA consumption during pregnancy does not alter offspring or placental weight but fetal plasma fatty acid composition; the developing fetus obtains their required PUFA from the maternal circulation. However, it is unknown if increased maternal linoleic acid alters placental fatty acid storage, metabolism, transport, and general placental function. Female Wistar-Kyoto rats were fed either a low LA diet (LLA; 1.44% of energy from LA) or high LA diet (HLA; 6.21% of energy from LA) for 10 weeks before pregnancy and during gestation. Rats were sacrificed at embryonic day 20 (E20, term = 22 days) and placentae collected. The labyrinth of placentae from one male and one female fetus from each litter were analyzed. High maternal LA consumption increased placental total n-6 and LA concentrations, and decreased total n-3 PUFA, alpha-linolenic acid (ALA), and docosahexaenoic acid (DHA). Fatty acid desaturase 1 ( Show less

Bone undergoes continuous remodeling due to balanced bone formation and resorption mediated by osteoblasts and osteoclasts, respectively. Osteoclasts arise from the macrophage lineage, and their differentiation is dependent on RANKL, a member of the TNF family of cytokines. Here, we have provided evidence that RANKL controls the expression of 3BP2, an adapter protein that is required for activation of SRC tyrosine kinase and simultaneously coordinates the attenuation of β-catenin, both of which are required to execute the osteoclast developmental program. We found that RANKL represses the transcription of the E3 ubiquitin ligase RNF146 through an NF-κB-related inhibitory element in the RNF146 promoter. RANKL-mediated suppression of RNF146 results in the stabilization of its substrates, 3BP2 and AXIN1, which consequently triggers the activation of SRC and attenuates the expression of β-catenin, respectively. Depletion of RNF146 caused hypersensitivity to LPS-induced TNF-α production in vivo. RNF146 thus acts as an inhibitory switch to control osteoclastogenesis and cytokine production and may be a control point underlying the pathogenesis of chronic inflammatory diseases. Show less

Metabolic syndrome (MetS) is an aberration associated with increased risk for cancer and inflammation. Adiponectin, an adipocyte-produced abundant protein hormone, has countering effect on the diabetogenic and atherogenic components of MetS. Plasma levels of adiponectin are negatively correlated with onset of cancer and cancer patient mortality. We previously performed microsatellite linkage analyses using adiponectin as a surrogate marker and revealed two QTLs on chr5 (5p14) and chr14 (14q13). Using individuals from 85 extended families that contributed to the linkage and who were measured for 42 clinical and biologic MetS phenotypes, we tested QTL-based SNP associations, peripheral white blood cell (PWBC) gene expression, and the effects of cis-acting SNPs on gene expression to discover genomic elements that could affect the pathophysiology and complications of MetS. Adiponectin levels were found to be highly intercorrelated phenotypically with the majority of MetS traits. QTL-specific haplotype-tagging SNPs associated with MetS phenotypes were annotated to 14 genes whose function could influence MetS biology as well as oncogenesis or inflammation. These were mechanistically categorized into four groups: cell-cell adhesion and mobility, signal transduction, transcription and protein sorting. Four genes were highly prioritized: cadherin 18 (CDH18), myosin X (MYO10), anchor protein 6 of AMPK (AKAP6), and neuronal PAS domain protein 3 (NPAS3). PWBC expression was detectable only for the following genes with multi-organ or with multi-function properties: NPAS3, MARCH6, MYO10 and FBXL7. Strong evidence of cis-effects on the expression of MYO10 in PWBC was found with SNPs clustered near the gene's transcription start site. MYO10 expression in PWBC was marginally correlated with body composition (p = 0.065) and adipokine levels in the periphery (p = 0.064). Variants of genes AKAP6, NPAS3, MARCH6 and FBXL7 have been previously reported to be associated with insulin resistance, inflammatory markers or adiposity studies using genome-wide approaches whereas associations of CDH18 and MYO10 with MetS traits have not been reported before. Adiponectin QTLs-based SNP association and mRNA expression identified genes that could mediate the association between MetS and cancer or inflammation. Show less

Infection with Helicobacter pylori is a major risk factor for the development of gastric cancer, and infection with strains carrying the virulence factor CagA significantly increases this risk. To investigate the mechanisms by which CagA promotes carcinogenesis, we generated transgenic zebrafish expressing CagA ubiquitously or in the anterior intestine. Transgenic zebrafish expressing either the wild-type or a phosphorylation-resistant form of CagA exhibited significantly increased rates of intestinal epithelial cell proliferation and showed significant upregulation of the Wnt target genes cyclinD1, axin2 and the zebrafish c-myc ortholog myca. Coexpression of CagA with a loss-of-function allele encoding the β-catenin destruction complex protein Axin1 resulted in a further increase in intestinal proliferation. Coexpression of CagA with a null allele of the key β-catenin transcriptional cofactor Tcf4 restored intestinal proliferation to wild-type levels. These results provide in vivo evidence of Wnt pathway activation by CagA downstream of or in parallel to the β-catenin destruction complex and upstream of Tcf4. Long-term transgenic expression of wild-type CagA, but not the phosphorylation-resistant form, resulted in significant hyperplasia of the adult intestinal epithelium. We further utilized this model to demonstrate that oncogenic cooperation between CagA and a loss-of-function allele of p53 is sufficient to induce high rates of intestinal small cell carcinoma and adenocarcinoma, establishing the utility of our transgenic zebrafish model in the study of CagA-associated gastrointestinal cancers. Show less