Epidemiology of interleukin-6: the 30-year follow-up of the 1982 Pelotas (Brazil) birth cohort study

BACKGROUND

Cardiovascular diseases are the main cause of death globally. Interleukin-6 (IL-6) is a biomarker of cardiovascular risk.

AIM

To investigate factors associated with IL-6 concentration in serum, from early life up to 30 years of age.

SUBJECTS AND METHODS

In the 2012-2013 follow-up, IL-6 was measured in 2809 participants of the 1982 Pelotas Birth Cohort (1369 males). Multivariable linear regressions, stratified by sex, were performed to evaluate the associations of African ancestry, family income and maternal education at birth, monthly income and education at 30 years, smoking status, harmful alcohol intake, physical activity, and body composition with IL-6, considering a conceptual hierarchical framework.

RESULTS

Males with low educational levels and current smokers had the highest mean IL-6. Among females, African ancestry and low monthly income were associated with the highest mean values for the outcome. Physical activity had an inverse association with IL-6 concentration among females. A direct relationship was observed between the measures of adiposity on IL-6, in both sexes.

CONCLUSION

Body composition was the main predictor for the outcome evaluated in males and females. Thus, the avoidance of overweight remains an important strategy for the prevention and control of cardiovascular risk and biomarkers associated with these diseases.

Association of modifiable risk factors and IL-6, CRP, and adiponectin: Findings from the 1993 Birth Cohort, Southern Brazil

Background

The literature on the relationship between lifestyle behaviors and inflammatory markers is scarce.

Methods

A birth cohort was followed since birth up to 22 years in Southern Brazil. Interleukin-6 (IL-6), C-reactive protein (CRP) and adiponectin were measured in nonfasting blood samples drawn at 18 and 22 years of age. Exposures including smoking, alcohol intake, physical inactivity and obesity, were collected at 15, 18 and 22 years. Cross sectional analyses were based on the number of follow-up visits with these exposures and the association with IL-6, CRP and adiponectin at 22 years old. We also carried out a longitudinal Generalized Least Squares (GLS) random-effects analysis with outcomes at 18 and at 22 years old. All analyses were adjusted for several covariates.

Results

The sample comprised 3,479 cohort members at 22 years. The presence of obesity at ≥ 2 follow-ups showed the highest mean values (SE) for IL-6 [2.45 (1.05)] and CRP [3.74 (1.11)] and the lowest mean value for adiponectin [8.60 (0.37)] (adjusted analyses, females) compared with other exposures; the highest mean of IL-6 [1.65 (1.05)] and CRP [1.78 (1.11)] and the lowest mean of adiponectin [9.98 (0.38)] were for the number of follow-ups with ≥2 exposures compared to those with no exposures at any follow-up (adjusted analyses, females). The longitudinal analysis showed an increase in obesity associated with IL-6 and CRP in both sexes and an inverse association with adiponectin in females; smoking (in males) was associated with IL-6 and CRP, harmful alcohol intake was associated with CRP in males, and increased in physical activity was inversely associated with CRP in men.

Conclusion

We concluded that obesity is the main exposure positively associated with IL-6 and CRP and inversely associated with adiponectin (mainly in females). Smoking is also associated with these markers in the longitudinal analysis (in males).

Associations of Cigarette Smoking With Subclinical Inflammation and Atherosclerosis: ELSA-Brasil (The Brazilian Longitudinal Study of Adult Health)

Background

There is a need to identify sensitive biomarkers of early tobacco‐related cardiovascular disease. We examined the association of smoking status, burden, time since quitting, and intensity, with markers of inflammation and subclinical atherosclerosis.

Methods and Results

We studied 14 103 participants without clinical cardiovascular disease in ELSA‐Brasil (Brazilian Longitudinal Study of Adult Health). We evaluated baseline cross‐sectional associations between smoking parameters and inflammation (high‐sensitivity C‐reactive protein [hsCRP]) and measures of subclinical atherosclerosis (carotid intima–media thickness, ankle‐brachial index, and coronary artery calcium [CAC]). The cohort included 1844 current smokers, 4121 former smokers, and 8138 never smokers. Mean age was 51.7±8.9 years; 44.8% were male. After multivariable adjustment, compared with never smokers, current smokers had significantly higher levels of hsCRP (β=0.24, 0.19–0.29 mg/L; P<0.001) and carotid intima–media thickness (β=0.03, 0.02–0.04 mm; P<0.001) and odds of ankle‐brachial index ≤1.0 (odds ratio: 2.52; 95% confidence interval, 2.06–3.08; P<0.001) and CAC >0 (odds ratio: 1.83; 95% confidence interval, 1.46–2.30; P<0.001). Among former and current smokers, pack‐years of smoking (burden) were significantly associated with hsCRP (P<0.001 and P=0.006, respectively) and CAC (P<0.001 and P=0.002, respectively). Among former smokers, hsCRP and carotid intima–media thickness levels and odds of ankle‐brachial index ≤1.0 and CAC >0 were lower with increasing time since quitting (P<0.01). Among current smokers, number of cigarettes per day (intensity) was positively associated with hsCRP (P<0.001) and CAC >0 (P=0.03) after adjusting for duration of smoking.

Conclusions

Strong associations were observed between smoking status, burden, and intensity with inflammation (hsCRP) and subclinical atherosclerosis (carotid intima–media thickness, ankle‐brachial index, CAC). These markers of early cardiovascular disease injury may be used for the further study and regulation of traditional and novel tobacco products.

Association between a Healthy Lifestyle Score and inflammatory markers among Puerto Rican adults

BACKGROUND AND AIMS

The relationship between multiple lifestyle components analyzed in combination and inflammation remains understudied. We aimed to assess the association between a Healthy Lifestyle Score (HLS) that includes adherence to five behavioral components (diet, physical activity and sedentary behaviors, smoking, social support and network, and sleep) and inflammatory markers, as well as the role of the HLS in inflammation among individuals with cardiometabolic conditions, in Puerto Rican adults.

METHODS AND RESULTS

In a cross-sectional study of 842 Puerto Ricans adults (aged 45-75 y) living in Boston, MA, the HLS (range = 0-190; maximum indicative of healthiest adherence) was analyzed for association with three inflammatory markers: interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP). In multivariable-adjusted models, the HLS was inversely associated with IL-6 (β ± SE = -0.55 ± 0.13; P < 0.001) and TNF-α (-0.39 ± 0.13; P = 0.004). The dietary and smoking components were associated with both inflammatory markers independently of the other HLS components. Significant inverse associations were observed for each 20-unit increase in HLS and IL-6 and TNF-α for participants with hypertension (n = 600; β ± SE = -0.58 ± 0.16; -0.46 ± 0.16, respectively) and with overweight/obesity (n = 743; β ± SE = -0.59 ± 0.13; -0.50 ± 0.14, respectively), but not for those with diabetes (n = 187) or heart disease (n = 192). The HLS was not associated with CRP, after adjustment for potential confounders.

CONCLUSION

Higher adherence to multiple lifestyle behaviors was associated with lower concentrations of inflammatory markers. Because low-grade inflammation may precede chronic diseases, following an overall healthy lifestyle may help lower risk of these diseases.