Fibrinogen and CRP in Israeli families: Genetic and environmental sources of concentrations and longitudinal changes

Heritability of carotid intima-media thickness and inflammatory factors of atherosclerosis in a Chinese population

Carotid intima-media thickness (cIMT), a marker of subclinical atherosclerosis, has been found to be associated with incident stroke. High-sensitivity C-reactive protein (CRP) and fibrinogen have been demonstrated to be associated with atherosclerosis. Previous studies on heritability estimates of IMT, CRP, and fibrinogen among Chinese populations are limited. This study aims to estimate the heritability of these risk factors in residents who participated in the Taichung Community Health Study (TCHS) and their family members. A total of 2671 study subjects from 805 families were enrolled in the study, selected from a random sample of TCHS participants and their family members. CRP, and fibrinogen were obtained from each participant, and a questionnaire interview was conducted. cIMT was measured by high-resolution B-mode ultrasound and expressed as the mean of the maximum. Heritability estimates and the familial correlation of cIMT, CRP, and fibrinogen among family pairs were determined with SAGE software. With multivariate adjustments, significant heritability was found for cIMT (h2 = 0.26, P < 0.001), CRP (h2 = 0.34, P < 0.001), and fibrinogen (h2 = 0.48, P < 0.001). The intrafamilial correlation coefficients for the three indexes in the parent-offspring pairs were significant (P < 0.001) and ranged from 0.17 to 0.41. The full sibship correlations were also significant (P < 0.001) for the three indexes and ranged from 0.19 to 0.47. This study indicates that a moderate proportion of the variability in CRP, fibrinogen, and cIMT can be attributed to genetic factors in Chinese populations. The findings suggest that CRP is associated with cIMT, whereas no significant association exists between fibrinogen and cIMT.

CRP, but not fibrinogen, is associated with gait speed as early as middle age, in females but not males

Low grade systemic inflammation and age-related gait speed decline are known to be related in older adults, but their relations in the early stages of the aging process are yet to be fully described. The aim of this study was to examine the relationship between gait speed and two inflammation markers-c-reactive protein (CRP) and fibrinogen-in a cohort of middle-aged adults in Israel. 326 healthy, middle-aged, Muslim-Arabs from three villages in northern Israel participated in this cross-sectional study. Serum CRP and fibrinogen were measured via blood tests, and gait speed was assessed with the 6-min walk test (6MWT). After adjusting for sex, age, height, BMI, systolic blood pressure, fasting blood glucose and triglycerides, executive function, smoking status and aerobic physical activity, gait speed was negatively and significantly associated with CRP (b = - 0.01, p = 0.029). When stratifying by gender, this link remained significant only among females (b = - 0.012, p = 0.041), such as that an increase of one SD unit of CRP was associated with a 0.047 m/s decrease in gait speed. No significant link was found between fibrinogen levels and gait speed. Blood CRP levels are associated with a slower walking speed already in middle age, independent of age, executive function and cardio-metabolic factors, among female Arab-Muslims in Israel. Future studies should examine this relationship longitudinally and investigate a broader array of inflammation markers. Systemic inflammation may serve as an early marker for people at risk of decreased walking or accelerated aging; Early identification and intervention among at-risk individuals may help prevent or slow gait speed decline, and promote healthier aging.

The Relationships of Fibrinogen and C-Reactive Protein With Gait Performance: A 20-Year Longitudinal Study

Background

Gait speed, a central marker of aging, has been linked to various health outcomes, such as cognitive and physical functions in middle-aged adults. Although long-term systemic low-grade inflammation is considered a mechanism underlying a variety of aging-related risk factors, the longitudinal associations between inflammation markers and gait speed are yet to be fully investigated.

Objective

To explore the associations of CRP and fibrinogen levels, measured two decades ago, with gait speed among community dwelling adults, considering the contribution of cardio-metabolic factors and cognition.

Methods

Study participants took part in two phases of the of the “Kibbutzim Family Study” (i.e., Phase II, 1999–2000 and Phase III, 2017–2019). Blood samples collected in Phase II (baseline) were used to determine level of inflammatory markers. Gait speed was assessed under single-task (ST) and dual-task (DT) conditions in Phase III. Demographic, anthropometric and clinical data were collected in both phases. Linear regression models were used to assess the adjusted associations of inflammation and gait speed.

Results

A total of 373 individuals aged 34–99 (mean 64 ± 13 years) in Phase III were included in the study. Gait speed under ST was negatively associated with baseline levels of fibrinogen (b per standard deviation (SD) = −0.053, p = 0.0007) and CRP (b per SD = −0.043, p = 0.010), after adjusting for baseline and concurrent cardiometabolic risk factors. Accounting for executive functions, associations of fibrinogen with gait under ST were somewhat attenuated, yet associations remained statistically significant (p < 0.05). Associations with CRP were attenuated to the null. In contrast, there were no associations between inflammation markers and gait under DT.

Conclusion

Our findings demonstrate that in a sample including younger to older adults, higher systemic inflammatory activity was linked with gait 20 years later, beyond age and cardiometabolic health, and to a certain extent, beyond executive functions. Thus, systemic inflammation may serve as an early marker to identify individuals at risk for gait decline.

Quantile-specific heritability of plasma fibrinogen concentrations

Background

Fibrinogen is a moderately heritable blood protein showing different genetic effects by sex, race, smoking status, pollution exposure, and disease status. These interactions may be explained in part by “quantile-dependent expressivity”, where the effect size of a genetic variant depends upon whether the phenotype (e.g. plasma fibrinogen concentration) is high or low relative to its distribution.

Purpose

Determine whether fibrinogen heritability (h²) is quantile-specific, and whether quantile-specific h² could account for fibrinogen gene-environment interactions.

Methods

Plasma fibrinogen concentrations from 5689 offspring-parent pairs and 1932 sibships from the Framingham Heart Study were analyzed. Quantile-specific heritability from offspring-parent (β_OP, h² = 2β_OP/(1+r_spouse)) and full-sib regression slopes (β_FS, h² = {(1+8r_spouseβ_FS)^0.05–1}/(2r_spouse)) were robustly estimated by quantile regression with nonparametric significance assigned from 1000 bootstrap samples.

Results

Quantile-specific h² (±SE) increased with increasing percentiles of the offspring’s age- and sex-adjusted fibrinogen distribution when estimated from β_OP (P_trend = 5.5x10^-6): 0.30±0.05 at the 10^th, 0.37±0.04 at the 25^th, 0.48±0.05 at the 50^th, 0.61±0.06 at the 75^th, and 0.65±0.08 at the 90^th percentile, and when estimated from β_FS (P_trend = 0.008): 0.28±0.04 at the 10^th, 0.31±0.04 at the 25^th, 0.36±0.03 at the 50^th, 0.41±0.05 at the 75^th, and 0.50±0.06 at the 90^th percentile. The larger genetic effect at higher average fibrinogen concentrations may contribute to fibrinogen’s greater heritability in women than men and in Blacks than Whites, and greater increase from smoking and air pollution for the FGB -455G>A A-allele. It may also explain greater fibrinogen differences between: 1) FGB -455G>A genotypes during acute phase reactions than usual conditions, 2) GTSM1 and IL-6 -572C>G genotypes in smokers than nonsmokers, 3) FGB -148C>T genotypes in untreated than treated diabetics, and LPL PvuII genotypes in macroalbuminuric than normoalbuminuric patients.

Conclusion

Fibrinogen heritability is quantile specific, which may explain or contribute to its gene-environment interactions. The analyses do not disprove the traditional gene-environment interpretations of these examples, rather quantile-dependent expressivity provides an alternative explanation that warrants consideration.

Long-term Trajectories of C-Reactive Protein Among Men Living With and Without HIV Infection in the Multicenter AIDS Cohort Study

BACKGROUND

C-reactive protein (CRP) is an inflammatory biomarker associated with all-cause mortality and morbidities such as cardiovascular disease. CRP is increased with HIV infection and thought to increase with age, though trajectories of CRP with aging have not been well characterized. We investigated trajectories of CRP in men from the Multicenter AIDS Cohort Study, according to HIV infection and HIV viral load status.

METHODS

CRP measurements from 12 250 serum samples, provided by 2132 men over a span of 30 years, were categorized by HIV status at sample collection: HIV uninfected (HIV-, n = 1717), HIV infected with undetectable RNA (HIV+ suppressed, n = 4075), and detectable HIV RNA (HIV+ detectable, n = 6458). Age-related trajectories of CRP were fit to multivariable linear mixed models; we tested for differences in trajectories by HIV status.

RESULTS

CRP increased with age in all sample groups. HIV+ detectable and HIV+ suppressed samples had higher CRP than HIV- samples throughout the observed age range of 20-70 years (p < .05). CRP concentrations at age 45 years were 38% (95% CI: 26%-50%) and 26% (15%-38%) higher in HIV+ detectable and HIV+ suppressed samples, respectively, relative to HIV- samples. HIV+ detectable samples showed more rapid linear increases with age (8% higher/decade, 0.3%-16%) than HIV- samples.

CONCLUSIONS

We observed higher concentrations of CRP across 5 decades of age in men living with HIV, and steeper increases with age in men with detectable HIV RNA, relative to HIV- men. These results are consistent with a contribution of inflammation to the higher risk of age-related comorbidities with HIV infection.

Quantile-dependent expressivity of serum C-reactive protein concentrations in family sets

BACKGROUND

"Quantile-dependent expressivity" occurs when the effect size of a genetic variant depends upon whether the phenotype (e.g., C-reactive protein, CRP) is high or low relative to its distribution. We have previously shown that the heritabilities (h 2) of coffee and alcohol consumption, postprandial lipemia, lipoproteins, leptin, adiponectin, adiposity, and pulmonary function are quantile-specific. Whether CRP heritability is quantile-specific is currently unknown.

METHODS

Serum CRP concentrations from 2,036 sibships and 6,144 offspring-parent pairs were analyzed from the Framingham Heart Study. Quantile-specific heritability from full-sib (βFS, h 2 ={(1 + 8rspouseβFS)0.5 - 1}/(2rspouse)) and offspring-parent regression slopes (βOP, h 2 = 2βOP/(1 + rspouse)) were estimated robustly by quantile regression with nonparametric significance determined from 1,000 bootstrap samples.

RESULTS

Quantile-specific h 2 (±SE) increased with increasing percentiles of the offspring's age- and sex-adjusted CRP distribution when estimated from βOP (P trend = 0.0004): 0.02 ± 0.01 at the 10th, 0.04 ± 0.01 at the 25th, 0.10 ± 0.02 at the 50th, 0.20 ± 0.05 at the 75th, and 0.33 ± 0.10 at the 90th percentile, and when estimated from βFS (P trend = 0.0008): 0.03±0.01 at the 10th, 0.06 ± 0.02 at the 25th, 0.14 ± 0.03 at the 50th, 0.24 ± 0.05 at the 75th, and 0.53 ± 0.21 at the 90th percentile.

CONCLUSION

Heritability of serum CRP concentration is quantile-specific, which may explain or contribute to the inflated CRP differences between CRP (rs1130864, rs1205, rs1800947, rs2794521, rs3091244), FGB (rs1800787), IL-6 (rs1800795, rs1800796), IL6R (rs8192284), TNF-α (rs1800629) and APOE genotypes following CABG surgery, stroke, TIA, curative esophagectomy, intensive periodontal therapy, or acute exercise; during acute coronary syndrome or Staphylococcus aureus bacteremia; or in patients with chronic rheumatoid arthritis, diabetes, peripheral arterial disease, ankylosing spondylitis, obesity or inflammatory bowel disease or who smoke.

A study of Kibbutzim in Israel reveals risk factors for cardiometabolic traits and subtle population structure

Genetic studies in isolated populations often increase power for identifying loci associated with complex diseases and traits. We present here the Kibbutzim Family Study (KFS), aimed at investigating the genetic basis of cardiometabolic traits in extended Israeli families characterized by long-term social stability and a homogeneous environment. Extensive information on cardiometabolic traits, as well as genome-wide genotypes, were collected on 901 individuals. We observed that most KFS participants were of Ashkenazi Jewish (AJ) genetic origin, confirmed a recent severe bottleneck in the AJ recent history, and detected a subtle within-AJ population structure. Focusing on genetic variants relatively common in the KFS but very rare in Europeans, we observed that AJ-enriched variants appear in cancer-related pathways more than expected by chance. We conducted an association study of the AJ-enriched variants against 16 cardiometabolic traits, and found seven loci (24 variants) to be significantly associated. The strongest association, which we also replicated in an independent study, was between a variant upstream of MSRA (frequency ≈1% in the KFS and nearly absent in Europeans) and weight (P = 3.6∙10-8). In conclusion, the KFS is a valuable resource for the study of the population genetics of Israel as well as the genetics of cardiometabolic traits.

The effect of alcohol use on IL-6 responses across different racial/ethnic groups

AIMS

Chronic inflammation has become increasingly recognized as a health threat for people living with HIV, given its associations with multiple diseases. Accordingly, the scientific community has prioritized the need to identify mechanisms triggering inflammation.

PARTICIPANTS METHODS

A clinic-based case-control study was designed to elucidate the plausible effects of alcohol use on IL-6. Peripheral blood mononuclear cells for measuring IL-6 culture supernatant and plasma for HIV assessments were collected from 59 hazardous alcohol users and 66 nonhazardous alcohol users, who were matched according to their age, gender and US CDC HIV severity status.

RESULTS

Stimulated peripheral blood mononuclear cells produced significantly higher amounts of IL-6 in hazardous alcohol users compared with nonhazardous alcohol users. However, racial status and receiving HAART significantly moderated this effect. Notably, in both HAART and non-HAART scenarios, IL-6 levels were associated with CD4 counts and viral burden. A distinctive IL-6 production pattern across racial/ethnic groups was also evident and showed that, when prescribed HAART, Hispanic hazardous alcohol users have a particularly high risk of morbidity compared with their Caucasian and African-American counterparts. After adjusting for confounders (e.g., sociodemographics and HIV disease status), regression analyses confirmed that chronic inflammation, as indicated by IL-6 levels (log), is associated with alcohol use, race/ethnicity and thrombocytopenia, and tended to be related to concurrent smoking.

CONCLUSION

Our data confirm that, despite HAART, people living with HIV still have a persistent inflammatory response that, in our study, was associated with chronic hazardous alcohol use. The data also highlight racial/ethnic disparities in IL-6 that justify further investigations.

Population differences in proinflammatory biology: Japanese have healthier profiles than Americans

The pleiotropic cytokine, interleukin-6 (IL-6), has emerged as a key factor in the biology of aging and the physiology of inflammation. Yet much of what we know about the normal functioning of IL-6 has been generated primarily from research on European populations and Americans of European descent. Our analyses compared IL-6 levels in 382 middle-aged and older Japanese to the values found in 1209 Caucasian- and African-Americans from the Midlife in the United States survey (MIDUS). Across the life span from 30 to 80 years of age, mean IL-6 levels were strikingly lower in Japanese individuals. Significantly lower levels of C-reactive protein (CRP) and fibrinogen (FBG) provided confirmatory evidence for a population difference in proinflammatory activity. Because IL-6 release has been associated with obesity, differences in body mass index (BMI) were taken into consideration. Japanese had the lowest, and African-Americans had the highest overall BMIs, but significant group differences in IL-6 persisted even after BMI was included as a covariate in the analyses. Additional support for distinct variation in IL-6 biology was generated when systemic levels of the soluble receptor for IL-6 (sIL-6r) were evaluated. Serum sIL-6r was higher in Japanese than Americans, but was most notably low in African-Americans. Our cytokine data concur with national differences in the prevalence of age-related illnesses linked to inflammatory physiology, including cardiovascular disease. The findings also highlight the importance of broadening the diversity of people included in population studies of health and aging, especially given the relative paucity of information for some Asian countries and on individuals of Asian heritage living in the US.

Leptin, insulin, and obesity-related phenotypes: genetic influences on levels and longitudinal changes

This study estimated the genetic and environmental determinants of plasma leptin and insulin levels and of obesity-related phenotypes. Included in this analysis were family members from 80 families living in kibbutz settlements, who participated in two examinations 8-10 years apart. We estimated that polygenes explained 30-50% of the adjusted leptin and insulin levels and 30-70% of the anthropometric phenotypes. This study demonstrated a significant genetic influence on longitudinal changes in leptin and BMI (h(2) = 0.45) and small-to-moderate heritability estimates for changes in insulin and other obesity-related phenotypes. In bivariate genetic analyses, we observed positive genetic correlations between leptin and anthropometric phenotypes, suggesting that shared effects of the same sets of loci account for 20-30% of the additive genetic variance in these pairs of variables. Shared genetic factors also account for 20-25% of the additive genetic variance in insulin-anthropometric pairs of variables.

Ethnic groups and high sensitivity C-reactive protein in Israel

High-sensitivity C-reactive protein (hs-CRP) is a biomarker that correlates with atherothrombotic risk and outcome. hs-CRP is influenced by various modifiable and non-modifiable factors. We studied the relationship between ethnic background and hs-CRP level, among the Jewish population in Israel. A total of 3659 men and 2180 women were divided into two ethnic groups (Ashkenazi and Sephardic Jews), based on the knowledge of Jewish immigration patterns throughout the centuries. Mean hs-CRP levels were calculated for each group and were adjusted for various factors known to influence hs-CRP. Sephardic Jews were found to have higher adjusted mean hs-CRP levels (2.0 mg l(-1) for men and 3.9 mg l(-1) for women) compared with Ashkenazi Jews (1.5 mg l(-1) for men and 2.9 mg l(-1) for women). Ethnic background emerged as an independent significant predictor of hs-CRP levels. We demonstrated that ethnicity is an important factor when considering hs-CRP as a marker of atherothrombotic risk.

Evidence of major genes effects on serum homocysteine and fibrinogen levels, and premature ischemic heart disease in Italian extended families

OBJECTIVES

The purpose of the present study was to investigate the effect of novel genetic factors on plasma levels of total homocysteine (tHcy) and fibrinogen (FIB). As tHcy and FIB have been consistently associated to increased risk of ischemic heart disease (IHD) and acute myocardial infarction (MI) also genes-trait-MI mediational effects were tested.

METHODS

A complex segregation analysis, and a mediation analysis of a highly selected group of 44 extended families (302 subjects), each including at least one member with fatal premature (<50 years) IHD were carried out.

RESULTS

tHcy and FIB levels turned out to be influenced by at least two major genes. A significant tHcy latent class-MI association (OR = 3.24; 95% CI, 1.37 to 7.68), and a non-significant tHcy plasma level-MI association (OR = 1.65 per 1 = log 10 mumol/l, 95% CI, 0.56 to 4.81) were estimated, suggesting a direct influence of the homocysteine major gene as suppressor of plasma tHcy levels effect. In contrast, FIB latent class-MI association (OR = 0.97; 95% CI, 0.31 to 3.05) and FIB level-MI association (OR = 1.32 per 1 = 70 g/l; 95% CI, 0.88 to 2.00) were not statistically significant.

CONCLUSION

These data provide evidence for a major latent gene effect influencing variation in tHcy plasma levels, which is independent on C677T MTHFR polymorphism, and significantly affecting the risk of MI.

Heritability of serum hs-CRP concentration and 5-year changes in the Stanislas family study: association with apolipoprotein E alleles

We aimed at estimating additive genetic heritability, household component effect and the influence of common alleles of the apolipoprotein E gene (APOE) on serum high-sensitivity C-reactive protein (hs-CRP) concentrations and the subsequent changes over 5 years. A sub-sample of 320 nuclear families was randomly selected from the Stanislas Family Study. Serum hs-CRP concentration was measured by immunonephelometry at entrance and after 5 years. APOE alleles were determined by restriction fragment length polymorphism. After adjustment for covariates, the number of the epsilon4 allele was negatively associated with serum concentration of hs-CRP in the whole sample, at entrance and 5 years later, without significant interaction with sex by generation groups (P=0.003 and P=0.0003, respectively). However, no significant association was found between epsilon4 allele and 5-year changes in hs-CRP concentration. Using a variance component analysis, no significant genetic influence was shown in family aggregation of both hs-CRP measurements and 5-year changes; the household common component was between 6.5 and 12.8%. In addition, after adjustment for APOE gene polymorphisms, degrees of resemblance were almost unchanged. In the Stanislas Family Study, epsilon4 allele of the APOE gene was associated with lower hs-CRP concentration, but not with 5-year changes. However, variance component analysis did not evidence a significant polygenic effect.