Increase of serum uric acid levels associated with APOE ε2 haplotype: a clinico-genetic investigation and in vivo approach.

Elevated serum uric acid (SUA)-hyperuricemia-is caused by overproduction of urate or by its decreased renal and/or intestinal excretion. This disease, which is increasing in prevalence worldwide, is associated with both gout and metabolic diseases. Several studies have reported relationships between apolipoprotein E (APOE) haplotypes and SUA levels in humans; however, their results remain inconsistent. This prompted us to investigate the relationship between APOE polymorphisms and SUA levels. Our subjects were 5,272 Japanese men, premenopausal women, and postmenopausal women. Multiple linear regression analyses revealed the ε2 haplotype of APOE to be independently associated with higher SUA in men (N = 1,726) and postmenopausal women (N = 1,753), but not in premenopausal women (N = 1,793). In contrast, the ε4 haplotype was little related to SUA levels in each group. Moreover, to examine the effect of Apoe deficiency on SUA levels, we conducted animal experiments using Apoe knockout mice, which mimics ε2/ε2 carriers. We found that SUA levels in Apoe knockout mice were significantly higher than those in wild-type mice, which is consistent with the SUA-raising effect of the ε2 haplotype observed in our clinico-genetic analyses. Further analyses suggested that renal rather than intestinal underexcretion of urate could be involved in Apoe deficiency-related SUA increase. In conclusion, we successfully demonstrated that the ε2 haplotype, but not the ε4 haplotype, increases SUA levels. These findings will improve our understanding of genetic factors affecting SUA levels.

High-density lipoprotein levels have markedly increased over the past twenty years in Japan.

AIM: The high-density lipoprotein cholesterol(HDL-C) level is a major negative risk factor for atherosclerotic diseases dependent on various lifestyle parameters. Changes in the lifestyle of Japanese individuals over the past several decades is believed to have increased their total cholesterol levels and the incidence of cardiovascular disease in Japan. It is therefore important to assess the long-term trends in the HDL-C levels with respect to public health in the community. METHODS: In this study, accumulated data for the serum/plasma HDL-C levels published in cohort studies and obtained during health checkup programs in Japan were analyzed with respect to timedependent changes. RESULTS: The levels of HDL-C have continuously and significantly increased over the past 20 years by 12-15% according to the National Health and Nutrition Study, other cohort studies and commercially available data. On the other hand, the non-HDL-cholesterol levels demonstrated no changes or only a slight decrease during the same period. This finding is consistent with several sets of data obtained from health checkup programs. The commercially measured levels of serum apoA-I, an independent parameter of serum HDL, also showed a similar long-term increase, supporting the above findings. CONCLUSION: We concluded that the serum/plasma HDL concentrations in Japanese individuals, selectively, have increased continuously and significantly over the past 20 years or more. The reasons for this phenomenon and the consequent public health outcomes have yet to be investigated.