Association between dysphagia risk and sleep quality in community-dwelling older adults: A cross-sectional study.

Objectives: Exploring the effects of swallowing function on sleep quality could provide valuable insights into the potential impact of reduced swallowing function on sleep. However, pertinent studies are limited. Therefore, this study aimed to investigate the relationship between dysphagia risk and sleep health in community-dwelling older adults. Methods: Data for this cross-sectional study were obtained from the Shizuoka and Daiko studies conducted as part of the Japan Multi-Institutional Collaborative Cohort Study. Information on demographics, overall lifestyle, dysphagia risk, as well as sleep quality, duration, satisfaction, and regularity, was obtained using a self-administered questionnaire. Dysphagia risk and sleep quality were assessed using the Dysphagia Risk Assessment Questionnaire for the Community-dwelling Elderly and the Japanese version of the Pittsburgh Sleep Questionnaire Index, respectively. Multivariate logistic regression, adjusted for covariates, was employed to assess the association between dysphagia risk and sleep health. Results: Among the 3058 participants (1633 males, 1425 females) aged ≥60 years, 28.0 % exhibited dysphagia risk, and 19.1 % reported poor sleep quality. Those with dysphagia risk were more likely to experience poor sleep quality than those without dysphagia risk. In male participants, dysphagia was significantly associated with poor sleep quality, unsatisfactory sleep, and sleep irregularity, but was not significantly associated with unsatisfactory or irregular sleep in female participants. The Japanese version of the Pittsburgh Sleep Questionnaire Index components-subjective sleep quality, sleep latency, sleep disturbances, and daytime dysfunction-were associated with dysphagia risk in both sexes. Conclusions: Dysphagia risk is associated with sleep quality in older individuals in Japan. Thus, preserving swallowing function may contribute to enhancing sleep quality.

The Inverse Association between the Frequency of Forest Walking (Shinrin-yoku) and the Prevalence of Insomnia Symptoms in the General Japanese Population: A Japan Multi-Institutional Collaborative Cohort Daiko Study.

Since a single forest walk (Shinrin-yoku or forest bathing) session is reported to improve sleep temporarily, occasional forest walks may have a positive effect on daily sleep. Therefore, this study aimed to examine whether more frequent forest walking is associated with better daily sleep conditions. Data from the second survey of the Japan Multi-Institutional Collaborative Cohort (J-MICC) Daiko Study conducted among residents of Nagoya City, Japan, were used. The study design was a cross-sectional study. In total, 2044 participants (529 men and 1515 women; age, mean ± standard deviation: 58.8 ± 9.9 years) were included in the analysis. Frequent forest walks were associated with a low percentage of insomnia symptoms (Insomnia Severity Index ≥10) in women, but not in men. The adjusted odds ratio for the group that rarely took forest walks with reference to the group that engaged in the activity once a month or more often was 2.04 (95% confidence interval: 1.29-3.23) in women. Forest walk frequency was not significantly associated with sleep duration or sleep efficiency as measured by actigraphy in either men or women. In conclusion, the results suggested that increasing the frequency of forest walks or Shinrin-yoku may be effective in preventing insomnia in women.

Intraindividual variation in histone acetylation and its impact on autoimmune thyroid diseases.

Autoimmune thyroid diseases (AITDs), such as Graves' disease (GD) and Hashimoto's disease (HD), are organ-specific autoimmune diseases. Histone acetylation, especially that of histone H3, is an epigenetic mechanism that regulates gene expression and is associated with the development of autoimmune diseases. However, physiological variations in histone acetylation are not yet clear, and we believe that physiological variations should be examined prior to analysis of the role of histone H3 in the pathogenesis of AITDs. In this study, we analyzed histone H3 acetylation levels in peripheral blood mononuclear cells (PBMCs) using a histone H3 total acetylation detection fast kit. Blood samples were collected before meals, between 8:30-9:00 am, daily for 10 weeks to evaluate the daily variation. At 4 days, blood was also collected before meals three times a day (at 8:30-9:00, 12:30-13:00, and 16:30-17:00) to evaluate circadian variation. Then, histone H3 acetylation levels were evaluated in AITD patients to clarify the association with the pathogenesis of AITD. Although we could not find a common pattern of circadian variance, we observed daily variation in histone H3 acetylation levels, and their coefficient of variances (CVs) were approximately 48.3%. Then, we found that histone H3 acetylation levels were significantly lower in GD and HD patients than in control subjects and these differences were larger than the daily variation in histone acetylation. In conclusion, histone H3 acetylation levels were associated with the development of AITD, even allowing for daily variation.

Relationships between sleep efficiency and lifestyle evaluated by objective sleep assessment: SLeep Epidemiology Project at University of Tsukuba.

Objectively measured sleep efficiency has recently been shown to be associated with health problems. Although several factors have previously been reported to be associated with sleep efficiency, most of these studies were conducted on older or younger adults, and the factors associated with sleep efficiency in healthy workers remain unknown. The aim of this study was to investigate the relationship between sleep efficiency and lifestyle factors using sleep measurement data recorded by an activity meter worn by workers. In total, 693 workers (male, 43.6%; mean age, 42.7 ± 11.3 years) were recruited from five offices in 2017. Sleep was measured over the period of 1 week by actigraphy. Workers' attributes, lifestyle habits, and occupational stress were identified using a questionnaire, and the association of sleep efficiency with lifestyle, occupational stress, and attributes was explored by logistic regression analysis. A logistic regression analysis using attributes and occupational stress as adjustment variables revealed that "longer sleeping hours on weekends than on weekdays" [odds ratios (OR), 0.66; 95% confidence interval (CI), 0.47-0.94], "water ingestion at bedtime" [OR, 2.09; 95% CI, 1.28-3.41], and "smartphone use at bedtime" [OR, 1.90; 95% CI, 1.28-2.83] were associated with decreased sleep efficiency. This study found that lifestyle habits were associated with sleep efficiency among workers. It is necessary to verify whether intervention in these lifestyle habits would contribute to the improvement of sleep efficiency in future studies.

Morning preference is associated with subjective happiness among Japanese female workers: A moderation analysis by sleep characteristics from the SLEPT study.

Research on mental health in working populations has predominantly focussed on negative outcomes, while studies on the positive aspects of life remain very limited, especially in Japan. Although morningness has recently been considered a factor for being happy, the role of sleep characteristics as it relates to the association between morningness and happiness has not been substantiated. The aim of this study is to investigate the associations between diurnal preference and level of subjective happiness in healthy, full-time, daytime workers in Japan. We also tested the moderation effect of sleep parameters on the relationship between diurnal preference and subjective happiness. This is an exploratory analysis from the cross-sectional data of the SLeep Epidemiology Project at the University of Tsukuba (SLEPT Study). Subjective happiness was evaluated using a single-item question. Diurnal preference was assessed using the Morningness-Eveningness Questionnaire (MEQ), in which higher scores indicate greater tendency to have morning preference. The participants underwent assessment of sleep parameters for 7 consecutive days using a waist-worn actigraphy device and kept a sleep diary. Sleep parameters investigated were subjective sleep quality, sleep disturbance, daytime sleepiness, weekend oversleep, total sleep time, sleep onset time, wake time, and sleep efficiency. A total of 205 males (average 42.6 ± 10.4 years) and 272 females (41.1 ± 9.8 years) were eligible for analysis. Hierarchical liner regression analysis was used to show the relationships of subjective happiness with MEQ score, and the sleep parameters. Further, moderation analysis was conducted by adding the interaction between MEQ score and the sleep parameters. After adjusting for age, psychological distress, self-rated health, and occupational stress, we found that subjective happiness was significantly associated with higher MEQ score and sleep efficiency but only in female. The moderating role of sleep parameters was not found. We discussed the implications of the obtained results and a possible strategy to maintain and improve subjective happiness of female workers who have evening preference.

Protein intake in inhabitants with regular exercise is associated with sleep quality: Results of the Shika study.

STUDY OBJECTIVES: Although associations between sleep quality and environmental factors and nutrient intake have been reported, interactions between these factors have not been elucidated in detail. Therefore, this cross-sectional study examined the effects of regular exercise and nutrient intake on sleep quality using the Pittsburgh Sleep Quality Index (PSQI), which is the most frequently used index for sleep evaluation. METHODS: The participants included 378 individuals aged 40 years or older living in Shika Town, Ishikawa Prefecture. Of these individuals, 185 met the inclusion criteria. The participants completed a self-administered questionnaire assessing lifestyle habits and frequency and duration of exercise, the PSQI, and the brief-type self-administered diet history questionnaire (BDHQ) on nutrient intake. RESULTS: A two-way analysis of covariance on regular exercise and PSQI scores indicated that protein intake (17.13% of energy) was significantly higher in the regular exercise and PSQI ≤10 groups than in the non-regular exercise or PSQI ≥11 groups (p = 0.002). In a multiple logistic regression analysis with PSQI scores (≤10 and ≥11), protein intake was a significant independent variable in any of the models adjusted for confounding factors such as age, sex, body mass index, current smoker, and current drinker (OR: 1.357, 95% CI: 1.081, 1.704, p = 0.009) in the regular exercise group but not in the non-regular exercise group.Conclusions We identified a positive relationship between sleep quality and protein intake in the regular exercise group. These findings suggest that regular exercise at least twice a week for 30 minutes or longer combined with high protein intake contributes to good sleep quality.

Frequency of forest walking is not associated with prevalence of hypertension based on cross-sectional studies of a general Japanese population: a reconfirmation by the J-MICC Daiko Study.

Forest walking or Shinrin-yoku is a health promotion activity in Japan. Although some studies have reported the acute effects of walking a few hours in forested areas in reducing blood pressure level compared to other environments, studies investigating whether successive walking has long-term effects in lowering blood pressure levels or lowering prevalence of hypertension are rare. This study aimed to reconfirm the presence or absence of an association between the frequency of forest walking and prevalence of hypertension in a Japanese population. This J-MICC Daiko Study was conducted targeting residents in Nagoya City. A total of 5,109 participants (1,452 men and 3,657 women; age, mean ± standard deviation: 52.5 ± 10.3 years) were included in the analysis. Age-adjusted blood pressure level by frequency of forest walking was not significant. After adjusting for age and lifestyle, the adjusted odds ratios (aORs) of the most frequent group (n=88, 1.7%; once a week or more group) relative to the less than once a month group (n=4,558, 89.2%) for prevalence of hypertension were not also significant [0.80 (95% CI: 0.40-1.62) for men and 1.48 (95% CI: 0.73-3.00) for women]. This study reconfirmed that either lowering blood pressure level or lowering the prevalence of hypertension is not associated with frequency of forest walking, similar to the results of our previous J-MICC Shizuoka Study. Given that these two studies were cross-sectional studies, cohort studies investigating the causal relationship are required to evaluate the effect of frequent forest walking on the prevention of hypertension.

Methylation levels of the TNFA gene are different between Graves' and Hashimoto's diseases and influenced by the TNFA polymorphism.

Graves' disease (GD) and Hashimoto's disease (HD) are different pathological types of autoimmune thyroid diseases (AITDs). However, the epigenetic differences between these diseases have not been elucidated. DNA methylation is one of the primary epigenetic modifications that reflect environmental influences on gene expression. In this study, we evaluated the methylation status of six CpG sites in the TNFA promoter using pyrosequencing and analyzed the data in combination with functional polymorphisms (-1031 T/C and +123 C/T) in the TNFA gene to clarify the role of gene methylation on the prognosis of AITDs. We examined the methylation pattern in 52 patients with GD, 60 patients with HD, and 29 healthy controls by pyrosequencing. Additionally, we also genotyped the polymorphisms from 163 patients with GD, 152 patients with HD, and 94 healthy controls using the restriction fragment length polymorphism (RFLP) method. Each proportion of subjects with low methylation of the -72 CpG site (≤11.9%), low methylation of the -49 CpG site (≤15.5%), and low methylation of the -38 CpG site (≤8.9%) was significantly increased in the groups with high concentration of TNF-α (≥0.134 pg/mL). The methylation level of the -72 CpG site was significantly higher in GD cases (10.7 ± 4.9%) than in healthy controls (6.8 ± 3.9%). The methylation level of the -49 and -38 CpG sites were significantly higher in patients with GD in remission (20.5 ± 9.5%, 17.6 ± 8.0%, respectively) than in healthy controls (13.0 ± 7.6%, 7.9 ± 7.3%, respectively). The frequency of the TNFA - 1031C carrier (CT + CC) is correlated with higher TNF-α production and was significantly higher in GD (35.0%) and HD (39.5%) cases than in controls (19.1%). In the subjects with the TNFA - 1031C carrier (CT + CC), the methylation level of the -72 CpG site was significantly higher in GD (11.5 ± 5.7%) than in HD (6.0 ± 3.4%). However, there was no difference between GD and HD in patients with the TT genotype. Cumulatively, our data indicate the methylation levels of CpG sites in the TNFA gene may be related to the difference between GD and HD in AITDs and may be influenced by the TNFA gene polymorphism.

Effects of self-reported calorie restriction on correlations between SIRT1 polymorphisms and body mass index and long-term weight change.

SIRT1 acts as a cellular sensor to detect energy availability and modulates fat and glucose metabolism. This study assessed the effects of self-reported calorie restriction (CR) and exercise on correlations between SIRT1 polymorphisms and body mass index (BMI) and long-term weight change. This cross-sectional study enrolled 4023 subjects aged 35-69years (1847 men and 2176 women) selected from participants in the Japan Multi-Institutional Collaborative Cohort Study. This study was based on a self-administered questionnaire. No significant correlations between SIRT1 polymorphisms and BMI or long-term weight change were found in either the CR or the active groups. In the no-CR group, women with the rs1467568 G allele had a higher BMI than women without (p=0.02). Moreover, women with the rs7895833 A or rs1467568 G allele gained more weight from the age of 20years than women without these alleles (p=0.03 for rs7895833 and p=0.003 for rs1467568). In addition, the odds ratios (95% confidence intervals) of these alleles for overweight (BMI >27.5kg/m2) were significantly high in the no-CR women group (1.78 (1.06-2.99) for rs7895833 and 1.88 (1.13-3.15) for rs1467568) but not in the CR group. The results of this study suggest that CR might override the genetic contributions of the SIRT1 rs7895833 A and rs1467568 G alleles to BMI and long-term weight change.

ALDH2 polymorphism is associated with fasting blood glucose through alcohol consumption in Japanese men.

Associations between alcohol consumption and type 2 diabetes risk are inconsistent in epidemiologic studies. This study investigated the associations of ADH1B and ALDH2 polymorphisms with fasting blood glucose levels, and the impact of the associations of alcohol consumption with fasting blood glucose levels in Japanese individuals. This cross-sectional study included 907 men and 912 women, aged 35-69 years. The subjects were selected from among the Japan Multi-institutional Collaborative Cohort study across six areas of Japan. The ADH1B and ALDH2 polymorphisms were genotyped by Invader Assays. The ALDH2 Glu504Lys genotypes were associated with different levels of fasting blood glucose in men (P = 0.04). Mean fasting glucose level was positively associated with alcohol consumption in men with the ALDH2 504 Lys allele (P trend = 0.02), but not in men with the ALDH2 504Glu/Glu genotype (P trend = 0.45), resulting in no statistically significant interaction (P = 0.38). Alcohol consumption was associated with elevated fasting blood glucose levels compared with non-consumers in men (P trend = 0.002). The ADH1B Arg48His polymorphism was not associated with FBG levels overall or after stratification for alcohol consumption. These findings suggest that the ALDH2 polymorphism is associated with different levels of fasting blood glucose through alcohol consumption in Japanese men. The interaction of ALDH2 polymorphisms in the association between alcohol consumption and fasting blood glucose warrants further investigation.

Association between functional SIRT1 polymorphisms and the clinical characteristics of patients with autoimmune thyroid disease.

Sirtuin1 (SIRT1) is a Class 3 nicotinamide adenine dinucleotide-dependent histone deacetylase (HDAC) that is thought to be implicated in the protection against autoimmune diseases. However, an association between SIRT1 and autoimmune thyroid disease (AITD) has not been reported. In this study, we selected four single nucleotide polymorphisms (SNPs) in the SIRT1 gene, rs12049646 T/C (termed SNP1), rs12778366 T/C (termed SNP2), rs3758391 T/C (termed SNP3), and rs4746720 T/C (termed SNP4). We genotyped each of these polymorphic sites in 185 patients with Graves' disease (GD), including 76 patients with intractable GD and 57 patients with GD in remission; 151 patients with Hashimoto's disease (HD), including 68 patients with severe HD and 54 patients with mild HD; and 96 healthy volunteers. SNP1 and SNP3 were genotyped by the PCR-RFLP method; SNP2 and SNP4 were genotyped using TaqMan® SNP genotyping assays. We also measured the levels of SIRT1 mRNA in CD4(+) T cells from 18 control subjects, 16 patients with GD in remission and 14 patients with mild HD using a real-time PCR method. In patients with GD and HD, the C carriers (TC + CC genotypes) of SNP3 showed significantly higher titers of McAb than the TT genotype (p = 0.0261 and p = 0.0309, respectively). Additionally, the T carriers (TT + TC genotypes) of SNP4 showed significantly higher titers of McAb than the CC genotype in patients with GD (p = 0.0079). In conclusion, the polymorphisms in the SIRT1 gene were associated with a greater production of thyroid autoantibodies.

Genome-wide association study of clinically defined gout identifies multiple risk loci and its association with clinical subtypes.

OBJECTIVE: Gout, caused by hyperuricaemia, is a multifactorial disease. Although genome-wide association studies (GWASs) of gout have been reported, they included self-reported gout cases in which clinical information was insufficient. Therefore, the relationship between genetic variation and clinical subtypes of gout remains unclear. Here, we first performed a GWAS of clinically defined gout cases only. METHODS: A GWAS was conducted with 945 patients with clinically defined gout and 1213 controls in a Japanese male population, followed by replication study of 1048 clinically defined cases and 1334 controls. RESULTS: Five gout susceptibility loci were identified at the genome-wide significance level (p<5.0×10(-8)), which contained well-known urate transporter genes (ABCG2 and SLC2A9) and additional genes: rs1260326 (p=1.9×10(-12); OR=1.36) of GCKR (a gene for glucose and lipid metabolism), rs2188380 (p=1.6×10(-23); OR=1.75) of MYL2-CUX2 (genes associated with cholesterol and diabetes mellitus) and rs4073582 (p=6.4×10(-9); OR=1.66) of CNIH-2 (a gene for regulation of glutamate signalling). The latter two are identified as novel gout loci. Furthermore, among the identified single-nucleotide polymorphisms (SNPs), we demonstrated that the SNPs of ABCG2 and SLC2A9 were differentially associated with types of gout and clinical parameters underlying specific subtypes (renal underexcretion type and renal overload type). The effect of the risk allele of each SNP on clinical parameters showed significant linear relationships with the ratio of the case-control ORs for two distinct types of gout (r=0.96 [p=4.8×10(-4)] for urate clearance and r=0.96 [p=5.0×10(-4)] for urinary urate excretion). CONCLUSIONS: Our findings provide clues to better understand the pathogenesis of gout and will be useful for development of companion diagnostics.

No association between Helicobacter pylori infection and diabetes mellitus among a general Japanese population: a cross-sectional study.

Several case-control studies have reported that patients with diabetes mellitus (DM) had a higher prevalence of Helicobacter pylori infection than those without DM, but these findings remain equivocal. Additionally, there are few studies examining associations between East Asian CagA-positive H. pylori and DM. This cross-sectional study aimed to investigate whether H. pylori infection was a possible risk factor for DM in a general Japanese population. The study included 5165 subjects (1467 men, 3698 women) aged 35-69 years from the Daiko Study, part of the Japan Multi-Institutional Collaborative Cohort Study. A urinary anti-H. pylori antibody was used to detect H. pylori infection. The medical history of physician-diagnosed DM was confirmed by self-administered questionnaire. The odds ratios (ORs) and their 95 % confidence intervals (CIs) for DM (current and former) were calculated using unconditional logistic regression analysis, adjusting for age, sex, educational status, alcohol use, smoking status, body mass index, energy intake, and physical activity. The prevalence of DM was 4.6 % (95 % CI 3.7-5.6 %) among 1878 participants with H. pylori infection and 3.2 % (2.6-3.8 %) among 3287 without the infection (p = 0.009). The crude, age-adjusted, and multivariate-adjusted ORs for DM in those with the infection relative to those without were 1.47 (95 % CI 1.10-1.97), 1.02 (0.76-1.38), and 0.97 (0.71-1.32), respectively. We found a significantly higher DM prevalence among those with H. pylori infection than among those without. However, almost all the difference in prevalence could be explained by the older age of those infected. Our findings did not support an association between H. pylori infection and DM.

Polymorphisms in CYP19A1, HSD17B1 and HSD17B2 genes and serum sex hormone level among postmenopausal Japanese women.

OBJECTIVE: Extraovarian sex hormone production plays an important role in estrogen biosynthesis in postmenopausal women. We examined possible associations between serum sex hormone level and polymorphisms in CYP19A1, HSD17B1, and HSD17B2. We also assessed possible interaction between these polymorphisms and current overweight. METHODS: We conducted a cross-sectional study. 785 Japanese natural postmenopausal women were randomly selected from the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study database. Information on lifestyle factors was obtained from a self-administered questionnaire. Serum estrogens and androgens levels were measured by liquid chromatography-tandem mass spectrometry. Four tag SNPs (single nucleotide polymorphisms) of CYP19A1, one missense SNP of HSD17B1 and three tag SNPs of HSD17B2 were examined by Invader assay. A trend test was conducted using linear regression. RESULTS: After adjustment for multiple comparisons, we found that rs4441215 and rs936306 in CYP19A1 and rs4888202 and rs2955160 in HSD17B2 were associated with differences in serum estrone level. Further, rs4441215 and rs936306 were associated with differences in serum estradiol level. None of these polymorphisms showed a significant interaction with current body mass index (BMI). CONCLUSIONS: Our findings suggested that CYP19A1 and HSD17B2 polymorphisms might be associated with circulating sex hormone levels in Japanese postmenopausal women, independent of current BMI.

ATP-binding cassette transporter A1 (ABCA1) R219K (G1051A, rs2230806) polymorphism and serum high-density lipoprotein cholesterol levels in a large Japanese population: cross-sectional data from the Daiko Study.

Among polymorphisms in ATP-binding cassette transporter A1 (ABCA1) gene, the available evidence demonstrates that the ABCA1 R219K polymorphism (G1051A, rs2230806) K allele is associated with a higher high-density lipoprotein cholesterol (HDL- C) level and may play a protective role against coronary artery disease (CAD) risk in Asians and Caucasians. The findings from many underpowered studies from Asian countries (n=71-597), however, still remain inconsistent. The objective of this study was to overcome the limitations of previous studies in Asia and provide solid epidemiologic evidence. Subjects were participants of a cohort study, who visited the Daiko Medical Center in Nagoya, Japan. The cohort study belongs to the Japan Multi-Institutional Collaborative Cohort Study (J-MICC Study). In the Daiko Study, 5,133 participants (1,458 men and 3,675 women) aged 35-69 years enrolled from 2008 through 2010 were eligible for the analyses. The ABCA1 polymorphism was genotyped by the polymerase chain reaction with confronting two-pair primers (PCR-CTPP) method. Among all the subjects, the genotype frequencies were 23.9% (n=1,225) for RR, 49.3% (n=2,532) for RK, and 26.8% (n=1,376) for KK, which was in Hardy-Weinberg's equilibrium (P =0.36). Background characteristics did not significantly differ among the genotypes including alcohol and tobacco use. The mean ± SD of HDL-C concentration was higher in men and women with RK or KK genotype than those with RR, although the difference between these genotypes was not statistically significant in both sexes (P =0.31 in men and 0.26 in women by ANOVA). In the multiple linear regression analysis to estimate the independent effects of the R219K polymorphism on HDL-C level, however, the number of K allele was significantly correlated with an increased level of HDL-C (trend P=0.033). Those with the KK genotype showed a significantly higher HDL-C concentration compared with those with the RR genotype by a mean of 1.18 mg/dL. The R219K polymorphism of ABCA1 independently associated with serum level of HDL-C in a large Japanese population.

Common variants of cGKII/PRKG2 are not associated with gout susceptibility.

OBJECTIVE: Recently, genetic analyses indicated the association between gout and cGMP-dependent protein kinase 2 (cGKII/PRKG2) gene in a Fukien-Taiwanese heritage population. However, no replication study has been reported in other ancestries. Therefore, we investigated this association in a Japanese population. METHODS: Genotyping of 4 variants (rs11736177, rs10033237, rs7688672, and rs6837293) of cGKII was performed in 741 male gout patients and 1302 male controls. RESULTS: cGKII variants have no association with gout. CONCLUSION: Our replication study suggests that cGKII is not involved in gout susceptibility.

Common variant of leucine-rich repeat-containing 16A (LRRC16A) gene is associated with gout susceptibility.

Gout is a common disease resulting from hyperuricemia which causes acute arthritis. Recently, genome-wide association studies revealed an association between serum uric acid levels and a common variant of leucine-rich repeat-containing 16A (LRRC16A) gene. However, it remains to be clarified whether LRRC16A contributes to the susceptibility to gout. In this study, we investigated the relationship between rs742132 in LRRC16A and gout. A total of 545 Japanese male gout cases and 1,115 male individuals as a control group were genotyped. rs742132 A/A genotype significantly increased the risk of gout, conferring an odds ratio of 1.30 (95 % CI 1.05-1.60; p = 0.015). LRRC16A encodes a protein called capping protein ARP2/3 and myosin-I linker (CARMIL), which serves as an inhibitor of the actin capping protein (CP). CP is an essential element of the actin cytoskeleton, which binds to the barbed end of the actin filament and regulates its polymerization. In the apical membrane of proximal tubular cells in the human kidney, the urate-transporting multimolecular complex (urate transportsome) is proposed to consist of several urate transporters and scaffolding proteins, which interact with the actin cytoskeleton. Thus, if there is a CARMIL dysfunction and regulatory disability in actin polymerization, urate transportsome may be unable to operate appropriately. We have shown for the first time that CARMIL/LRRC16A was associated with gout, which could be due to urate transportsome failure.

ASSOCIATIONS BETWEEN BODY MASS INDEX AND SERUM URIC ACID LEVELS IN A JAPANESE POPULATION WERE SIGNIFICANTLY MODIFIED BY LRP2 rs2544390.

The genome-wide association study identified associations between the LRP2 polymorphism rs2544390 and serum uric acid (SUA) levels in a Japanese population. Our previous study on the LRP2 rs2544390 polymorphism identified an interaction between SUA and alcohol consumption. Here, we investigated an interaction with body mass index (BMI) using the same dataset. Subjects were 3,742 health checkup examinees (2,544 males and 1,198 females) aged 35-69 years. Those with the SLC22A12 258WW genotype, SLC2A9 rs11722228 C allele, and ABCG2 126QQ genotype and 141Q allele were selected for analysis to remove the strong influences of these genetic traits. In males, the odds ratio of BMI ≥25.0 relative to BMI <18.5 for hyperuricemia (SUA ≥7 mg/dL and/or under medication for hyperuricemia) was 6.58 (95% confidence interval [CI], 0.84-51.32) for CC, 10.08 (2.38-42.83) for CT, and 2.53 (0.54-11.78) for TT. The interaction was 0.59 (p=0.029) from the model including BMI (<25.0 and ≥25.0), genotype (CC/CT and TT), and the multiplicative interaction term between BMI ≥25.0 and the TT genotype. In females, the odds ratio of BMI ≥25.0 relative to BMI <18.5 for high SUA (≥5 mg/dL and/or under medication for hyperuricemia) was 6.35 (95%CI, 1.68-24.08) for CC, 4.55 (1.85-11.18) for CT, and 5.93 (1.97-17.90) for TT. The interaction term was significant in the opposite direction for females (OR=2.75, p=0.011). The association between BMI and SUA was therefore modified by the LRP2 polymorphism in this Japanese population.

Common variants of a urate-associated gene LRP2 are not associated with gout susceptibility.

A recent genome-wide association study revealed that there is an association between serum uric acid (SUA) levels and rs2544390, a common variant in low-density lipoprotein-related protein 2 (LRP2/Megalin) gene. Two other variants of LRP2, rs2229268 and rs3755166, are also found to have associations with dyslipidemia and Alzheimer's disease, respectively, which also could have a relationship with SUA in human. Although no studies report that LRP2 transports urate, LRP2 is a multi-ligand receptor and expresses in many tissues including kidney, suggesting a direct and/or indirect relationship with gout. In the present study, we investigated the association between gout and these variants of LRP2 with 741 clinically diagnosed male gout patients and 1,302 controls. As a result, the three common LRP2 variants, rs2544390, rs2229268 and rs3755166, showed no association with gout (P = 0.76, 0.55, and 0.22, respectively). Our study is the first to reveal that an SUA-related gene LRP2 is not involved in gout susceptibility.

Gene-gene combination effect and interactions among ABCA1, APOA1, SR-B1, and CETP polymorphisms for serum high-density lipoprotein-cholesterol in the Japanese population.

BACKGROUND/OBJECTIVE: Gene-gene interactions in the reverse cholesterol transport system for high-density lipoprotein-cholesterol (HDL-C) are poorly understood. The present study observed gene-gene combination effect and interactions between single nucleotide polymorphisms (SNPs) in ABCA1, APOA1, SR-B1, and CETP in serum HDL-C from a cross-sectional study in the Japanese population. METHODS: The study population comprised 1,535 men and 1,515 women aged 35-69 years who were enrolled in the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study. We selected 13 SNPs in the ABCA1, APOA1, CETP, and SR-B1 genes in the reverse cholesterol transport system. The effects of genetic and environmental factors were assessed using general linear and logistic regression models after adjusting for age, sex, and region. PRINCIPAL FINDINGS: Alcohol consumption and daily activity were positively associated with HDL-C levels, whereas smoking had a negative relationship. The T allele of CETP, rs3764261, was correlated with higher HDL-C levels and had the highest coefficient (2.93 mg/dL/allele) among the 13 SNPs, which was statistically significant after applying the Bonferroni correction (p<0.001). Gene-gene combination analysis revealed that CETP rs3764261 was associated with high HDL-C levels with any combination of SNPs from ABCA1, APOA1, and SR-B1, although no gene-gene interaction was apparent. An increasing trend for serum HDL-C was also observed with an increasing number of alleles (p<0.001). CONCLUSIONS: The present study identified a multiplier effect from a polymorphism in CETP with ABCA1, APOA1, and SR-B1, as well as a dose-dependence according to the number of alleles present.