a b c e f g P. Reiner , Paula Diehr , Warren S. Browner , Stephen E. Humphries , , , h h i h j k Nancy S. Jenny , Mary Cushman , Russell P. Tracy , Jeremy Walston , , , , c l m l a d e Thomas Lumley , Anne B. Newman , Lewis H. Kuller , Bruce M. Psaty

16 September 2004; received in revised form 6 December 2004; accepted 10 January Available online 19 February 2005

Abstract

Inflammatory response genes may influence life span or quality at advanced ages. Using data from the population-based cardiovascular study (CHS) cohort, we examined the associations between promoter polymorphisms of several inflammation and thrombosis genes longevity. We ascertained genotypes for interleukin (IL)-6 −174 G/C, (cid:1)-fibrinogen −455 G/A, plasminogen activator inhibitor (PAI)-1 4G/5G, and thrombin-activatable fibrinolysis inhibitor (TAFI) −438 G/A in 2224 men and women ≥65 years old at baseline. During 10 of follow-up, men with the TAFI −438 A/A genotype had decreased mortality due to all causes, and lived, on average, 0.9 more years life, or 1.1 more years of healthy life, than men with the −438 G allele. The effects of TAFI −438 G/A in women were smaller and not significant. PAI-1 4G/4G genotype appeared to be associated with lower non-cardiovascular mortality in men, but with greater mortality in women. In exploratory analyses, we observed a possible interaction among anti-inflammatory drugs, interleukin-6 C/C genotype, and longevity. These findings suggest that modulators of fibrinolytic activity may have a generalized influence on aging, merit further investigation in studies of genetic determinants of human longevity.

Thrombin-activatable fibrinolysis inhibitor; Longevity; Inflammation; Fibrinolysis; Promoter polymorphism

Genetic factors appear to influence mortality, even at ad- vanced ages [1,2]. Inflammation, an evolutionarily conserved stress response, may reduce the length or quality of life in older adults by affecting adaptation to stressful events, chronic diseases, or the rate of aging. In case–control studies

A.P. Reiner et al. / Atherosclerosis 181 (2005) 175–183

provide complete mortality follow-up. For the current anal- ysis, we used complete 10-year follow-up data on all par- ticipants (corresponding to June 2000 for the original CHS cohort and June 2002 for the second CHS cohort).

of exceptional survival, inflammation and thrombosis gene promoter variants were associated with longevity, often, in a − sex-specific manner [3–5]. For example, the 174 C allele of interleukin-6 was more common among male, but not female, centenarians,comparedtoyounger,sex-matchedcontrols[4]. These retrospective studies of longevity have several limita- tions. The comparison group is sampled from another birth cohort, whose environmental exposures may differ from the long-lived case group. In addition, observed differences in case–control genotype or allele frequency may reflect sur- vival due to association with a single, common age-related condition such as coronary heart disease, rather than any in- fluence on the aging process per se.

Primary endpoints for this analysis included “years of life”, as well as “years of healthy life”, defined as the num- ber of years the person reported being in excellent, very good or good health in the 10 years after enrolment [7,8]. This outcome was derived from standard information on self-rated health status (excellent/very good/good/fair/poor) collected at baseline and every 6 months during follow- up. Missing data were imputed by linear interpolation of the available longitudinal data recorded 6 months before and after the missing value [7,8]. For the 3% of subjects whose final 10-year follow-up measurement was still miss- ing, we used the ‘last observation carried forward’ method of imputation.

Longitudinal cohort studies may allow more accurate as- sessment of genetic influences on longevity because both cause-specific and overall mortality can be ascertained. We therefore performed an analysis of genotype data available £ for promoter polymorphisms of interleukin-6, -fibrinogen, PAI-1, and TAFI on a sub-sample of participants from the car- diovascular health study (CHS; for details see Appendix A), a U.S. cohort of white and black men and women 65 years and older. After 10 years of follow-up, we assessed sex-specific associations of these gene variants with outcomes that reflect overall longevity (as years of life), life span and quality of life (as years of healthy life), and all-cause and cause-specific mortality. Finally, we explored potential interactions of in- flammation genotypes with other common risk factors that influence inflammatory responses, such as cigarette smok- ing, obesity, and selected medications.

1.3. Participant sampling and laboratory assays

Genotyping assays were performed on blood drawn at baseline for a subset of 2334 CHS participants who were sampled as part of a nested case–control study of incident cardiovascular events [9,10], and who gave informed con- sent to DNA preparation and testing. We excluded nine sub- jects whose self-reported race was other than white or black. Another 101 participants (80 whites and 21 blacks) were ex- cluded because an adequate DNA sample was unavailable at the time of testing. Therefore, a total of 2224 partici- pants (1874 whites and 350 blacks) were included in the cur- − rent analyses. Genotyping for the interleukin-6 174 G/C, − − − PAI-1 675 4G/5G, fibrinogen 455 G/A, and TAFI 438 G/A polymorphisms was performed with standard methods [9–12].

1. Methods

1.1. Study subjects