Association of Interleukin-10 Promoter Single Nucleotide Polymorphisms (cid:1)819 T/C and (cid:1)592 A/C With Aging

Okayama, Yuichiro Hamanaka, Yutaka Suehiro, Yoshinori Hasui, 2 1,2 Junji Nakamura, and Yuji Hinoda

1Department of Clinical Laboratory Science, 2Division of Laboratory, Yamaguchi University Yamaguchi University School of Medicine, Japan. 3Department of Oral and Maxillofacial Surgery, Yamaguchi University School of Medicine, Japan.

Increased inflammatory activity is known to accompany aging. Single nucleotide polymorphisms of inflammatory mediator genes might therefore affect the aging process. Relation of eight SNPs (tumor necrosis factor-a [TNF-a] (cid:1)1031 T/C, interleukin-10 [IL-10] (cid:1)819 T/C, IL-1b (cid:1)511 C/ T, IL-6 (cid:1)634 C/G, IL-18 (cid:1)607 A/C, transforming growth factor-b [TGF-b] þ869 C/ T, matrix metalloproteinase-1 [MMP-1] (cid:1)1607 1G/2G, and MMP-3 (cid:1)1171 5A/6A) with age or gender was evaluated in 500 Japanese persons (mean age: 56.7 years old, range: 19–100) by the chi-square test. There was a significant association of IL-10 (cid:1)819 T/C with age (p ¼ .0026). The association remained significant after multivariate logistic regression analysis (odds ratio for an age interval for 1 year, 1.009; 95% CI, 1.002–1.016). Furthermore, the genotype distribution of IL-10 (cid:1)819 T/C was completely consistent with that of (cid:1)592 A/C. These data suggest that IL-10 (cid:1)819 T/C and (cid:1)592 A/C may be a promising candidate for an aging-related gene in a Japanese population.

also might be derived from a case–control design by which frequency of genotypes is compared between cases (elderly people) and controls (younger people). To reduce such statistical problems, Tan and colleagues (18,19) recently reported a logistic regression model for measuring gene– longevity associations that enables us to estimate the probability of observing one genotype as a function of age, assuming that frequency of the genotype that affects individual survival should change in the genotypic pool with advancing age (18). In the present study, we evaluated the relationship of cytokine and MMP gene SNPs with age in a randomly selected population by using a multivariate logistic regression analysis.

unrelated individuals is one of the most popular study designs used to clarify the molecular basis of inherited components in human longevity (1). A variety of genes involved in DNA repair, drug or lipid metabolism, immune response, tumor suppression, and blood coagulation, have been investigated (1). Among these, inflammatory mediators have gained increasing attention because there is accumu- lating evidence that: (a) low-grade increases in plasma levels of tumor necrosis factor-a (TNF-a) and interleukin-6 (IL-6) are strong predictors of all-cause mortality risk independent of other known risk factors in elderly cohorts (2) and (b) anti-inflammatory drugs reduce the risk of vascular events, and possibly Alzheimer’s disease and cancer (3,4). Inflammatory mediators are also involved in glucose and lipid metabolism (5). TNF-a inhibits insulin- receptor signaling in adipocytes, hepatocytes, and skeletal muscle, and is implicated in the insulin resistance of aging. IL-6 stimulates hepatic glucose release, leading to hyper- glycemia. Of interest, caloric restriction strongly inhibits in- flammatory responses of aging (5).

P ARTICIPANTS

Peripheral blood samples were obtained from 500 unrelated Japanese individuals (252 males, 248 females; mean age, 56.7 years; range, 19–100 years) after obtaining written informed consents. Number and sex ratio (male/ female) of the 500 participants in each decade age were as follows: 5 (0/5) in 10s, 133 (70/63) in 20s, 39 (23/16) in 30s, 43 (22/21) in 40s, 30 (11/19) in 50s, 28 (22/6) in 60s, 79 (57/22) in 70s, 100 (35/65) in 80s, 42 (12/30) in 90s, and 1 (0/1) in 100s. Among these individuals, 337 were healthy volunteers including students, hospital staff members, and elderly people who visited the Yamaguchi University Hospital for regular physical examinations (187 males, 150 females; mean age, 44.3 years; range, 19–98 years), and 163 were patients treated in that hospital for a variety of chronic disorders including ischemic heart disease, essential hypertension, diabetes mellitus, peptic ulcer, and liver disease (65 males, 98 females; mean age, 82.3 years; range,

Single nucleotide polymorphisms (SNPs) in the following inflammatory mediator genes have been reported to be associated with longevity or aging: IL-6 (2), TNF-a (6), IL- 1 (7), IL-10 (8,9), interferon-c (IFN-c) (10), transforming growth factor-b (TGF-b) (11), and matrix metalloproteinase (MMP)-3 (12). Although it is highly possible that these genes are important candidates, conflicting data have been obtained for IL-6 (2), TNF-a (13–15), IL-1 (14,16), IL-10 (14,15,17), and IFN-c (15,17). One possible explanation for these discrepancies is the complex interaction between lifestyle and genetic factors together with cultural and genetic differences across countries (2). The discrepancies

(21). MMP-1 (cid:1)1607 1G/2G, IL-18 (cid:1)607 A/C, and IL-10 (cid:1)592 A/C were genotyped using a TaqMan assay, and TGF- b þ869 C/T and IL-10 (cid:1)1082 A/G were genotyped using PCR-RFLP. Primers, probes, and restriction enzymes used in this study are shown in Table 1.

Table 1. Primers, Probes, and Restriction Enzymes