Association of subcutaneous and visceral fat with circulating microRNAs in a middle-aged Japanese population

GWAS of Folate Metabolism With Gene-environment Interaction Analysis Revealed the Possible Role of Lifestyles in the Control of Blood Folate Metabolites in Japanese: The J-MICC Study

BACKGROUND

The present genome-wide association study (GWAS) aimed to reveal the genetic loci associated with folate metabolites, as well as to detect related gene-environment interactions in Japanese.

METHODS

We conducted the GWAS of plasma homocysteine (Hcy), folic acid (FA), and vitamin B12 (VB12) levels in the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study participants who joined from 2005 to 2012, and also estimated gene-environment interactions. In the replication phase, we used data from the Yakumo Study conducted in 2009. In the discovery phase, data of 2,263 participants from four independent study sites of the J-MICC Study were analyzed. In the replication phase, data of 573 participants from the Yakumo Study were analyzed.

RESULTS

For Hcy, MTHFR locus on chr 1, NOX4 on chr 11, CHMP1A on chr 16, and DPEP1 on chr 16 reached genome-wide significance (P < 5 × 10-8). MTHFR also associated with FA, and FUT2 on chr 19 associated with VB12. We investigated gene-environment interactions in both studies and found significant interactions between MTHFR C677T and ever drinking, current drinking, and physical activity >33% on Hcy (β = 0.039, 0.038 and -0.054, P = 0.018, 0.021 and <0.001, respectively) and the interaction of MTHFR C677T with ever drinking on FA (β = 0.033, P = 0.048).

CONCLUSION

The present GWAS revealed the folate metabolism-associated genetic loci and gene-environment interactions with drinking and physical activity in Japanese, suggesting the possibility of future personalized cardiovascular disease prevention.

Association of Peri-Implant Keratinized Mucosa Width and Mucosal Thickness with Early Bone Loss: A Cross-Sectional Study

Objective: The objective of this study was to evaluate the effects of keratinized mucosa width (KMW) and mucosal thickness (MT) around dental implants on marginal bone loss (MBL). The evaluation was performed one year after loading by comparing clinical, radiographic, and biochemical parameters. Methods: The study included 87 implants in 87 patients undergoing regular follow-ups without hard or soft tissue augmentation one year after loading. Clinical measurements included plaque index (PI), gingival index (GI), bleeding on probing (BoP), probing depth (PD), KMW, and MT. MBL was assessed with periapical radiography. The peri-implant crevicular fluid (PICF) was analyzed for tumor necrosis factor-alpha (TNF-α), receptor activator of nuclear factor-kB ligand (RANKL), osteoprotegerin (OPG), and microRNA-27a. Results: The MBL of implants with thin MT (<2 mm) was higher than that of implants with thick MT (≥2 mm) (p < 0.05). A significant negative correlation (r: -0.217) was established between MT and MBL. No significant association was found between KMW and MBL (p > 0.05). No significant associations was found between KMW and MT with TNF-α, RANKL, OPG and RANKL/OPG (p > 0.05), with the exception of increased microRNA-27a levels in implants with KMW ≥ 2 mm (p < 0.05). Conclusions: Implants with a thick MT had a lower MBL. There may be an association between adequate KMW and high miRNA-27a levels. The relationship between MBL and miRNA-27a remains unclear.

Identification of extremely GC-rich micro RNAs for RT-qPCR data normalization in human plasma

We aimed at extending the repertoire of high-quality miRNA normalizers for reverse transcription-quantitative PCR (RT-qPCR) of human plasma with special emphasis on the extremely guanine-cytosine-rich portion of the miRNome. For high-throughput selection of stable candidates, microarray technology was preferred over small-RNA sequencing (sRNA-seq) since the latter underrepresented miRNAs with a guanine-cytosine (GC) content of at least 75% (p = 0.0002, n = 2). miRNA abundances measured on the microarray were ranked for consistency and uniformity using nine normalization approaches. The eleven most stable sequences included miRNAs of moderate, but also extreme GC content (45%-65%: miR-320d, miR-425-5p, miR-185-5p, miR-486-5p; 80%-95%: miR-1915-3p, miR-3656-5p, miR-3665-5p, miR-3960-5p, miR-4488-5p, miR-4497 and miR-4787-5p). In contrast, the seven extremely GC-rich miRNAs were not found in the two plasma miRNomes screened by sRNA-seq. Stem-loop RT-qPCR was employed for stability verification in 32 plasma samples of healthy male Caucasians (age range: 18-55 years). In general, inter-individual variance of miRNA abundance was low or very low as indicated by coefficient of variation (CV) values of 0.6%-8.2%. miR-3665 and miR-1915-3p outperformed in this analysis (CVs: 0.6 and 2.4%, respectively). The eight most stable sequences included four extremely GC-rich miRNAs (miR-1915-3p, miR-3665, miR-4787-5p and miR-4497). The best-performing duo normalization factor (NF) for the condition of human plasma, miR-320d and miR-4787-5p, also included a GC-extreme miRNA. In summary, the identification of extremely guanine-cytosine-rich plasma normalizers will help to increase accuracy of PCR-based miRNA quantification, thus raise the potential that miRNAs become markers for psychological stress reactions or early and precise diagnosis of clinical phenotypes. The novel miRNAs might also be useful for orthologous contexts considering their conservation in related animal genomes.

Association between the Extent of Peripheral Blood DNA Methylation of HIF3A and Accumulation of Adiposity in community-dwelling Women: The Yakumo Study

INTRODUCTION

DNA methylation in the CpG sites of intron 1 of HIF3A is associated with body mass index (BMI). This cross-sectional study investigated correlations between DNA methylation of HIF3A and BMI or adiposity parameters in the Japanese population.

METHOD

DNA methylation of HIF3A was quantified via pyrosequencing.

RESULT

DNA methylation of HIF3A differed only in women; DNA methylation level at cg27146050 was associated with visceral adipose tissue thickness and correlated with BMI and percent (%) body fat after excluding smokers.

CONCLUSION

Peripheral blood DNA methylation at the CpG site (cg27146050) of HIF3A correlated with VAT thickness in Japanese women.

The potential role of miR-27a and miR-320a in metabolic syndrome in obese Egyptian females

BACKGROUND

Metabolic syndrome (MetS) is a combination of many health complications, such as obesity, high blood pressure, hyperlipidemia, hyperglycemia, and insulin resistance, with an increasing threat of type 2 diabetes mellitus (T2DM) and cardiovascular diseases. As the MetS develops, an alteration in the expression of some genes regulated by circulating microRNAs may also develop as a consequence. TaqMan microRNA primers specific for both miR-27a and miR-320a were used to estimate their expression levels in plasma samples collected from two groups: obese females with metabolic syndrome (n = 49) and lean healthy female volunteers (n = 23), to detect if their expression levels were deregulated with MetS.

RESULTS

The study results revealed that miR-27a was upregulated in the plasma of MetS group compared to the healthy controls, while miR-320a was downregulated (p ≤ 0.005). There was a highly significantly positive correlation between miR-27a expression and body mass index (BMI), waist circumference (WC), fasting blood glucose (FBG), insulin resistance (represented as HOMA-IR), and triglycerides (TG), while it showed significantly negative correlation only with HDL-cholesterol (p ≤ 0.0001). miR-320a showed significantly negative correlation with BMI, WC, waist-hip ratio (WHR), FBG, HOMA-IR, and TG. The expression value of miR-320a was positively correlated with HDL-cholesterol. Area under the curves (AUC) was equal to 1.000 for both microRNAs.

CONCLUSION

Our study added more evidence that monitoring changes in expression levels of both miR-27a and miR-320a in MetS patients could help in the evaluation of disease progression, risk, and susceptibility.

DNA methylation level of the gene encoding thioredoxin-interacting protein in peripheral blood cells is associated with metabolic syndrome in the Japanese general population

Metabolic syndrome (MetS) is cluster of metabolic diseases, including abdominal obesity, hyperglycemia, high blood pressure, and dyslipidemia, that directly escalate the risk of type 2 diabetes, heart disease, and stroke. Thioredoxin-interacting protein (TXNIP) is a binding protein for thioredoxin, a molecule that is a key inhibitor of cellular oxidation, and thus regulates the cellular redox state. Epigenetic alteration of the TXNIP-encoding locus has been associated with components of MetS. In the present study, we sought to determine whether the level of TXNIP methylation in blood is associated with MetS in the general Japanese population. DNA was extracted from the peripheral blood cells of 37 subjects with and 392 subjects without MetS. The level of TXNIP methylation at cg19693031 was assessed by the bisulfite-pyrosequencing method. We observed that TXNIP methylation levels were lower in MetS subjects (median 74.9%, range 71.7-78.4%) than in non-MetS subjects (median 77.7%, range 74.4-80.5%; p = 0.0024). Calculation of the confounding factor-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for hypomethylation revealed that subjects with MetS exhibited significantly higher ORs for hypomethylation than did those without MetS (OR, 2.92; 95% CI, 1.33-6.62; p = 0.009). Our findings indicated that lower levels of TXNIP methylation are associated with MetS in the general Japanese population. Altered levels of DNA methylation in TXNIP at cg19693031 might play an important role in the pathogenesis of MetS.

Circulating Levels of MiRNAs From 320 Family in Subjects With Lipodystrophy: Disclosing Novel Signatures of the Disease

Lipodystrophy (LD) indicates a group of rare disorders, with generalized or partial loss of white adipose tissue (WAT) often associated with metabolic derangements. Heterogeneity/wide spectrum of the disease and lack of biomarkers make diagnosis often difficult. MicroRNAs are important to maintain a correct WAT function and WAT is a source of circulating miRNAs (cmiRs). miRNAs from 320 family were previously detected in the WAT and variably associated to the metabolic syndrome. Our aim was then to investigate if LD can result in altered abundance of cmiRs-320. We collected samples from a cohort of LD subjects of various subtypes and from age matched controls. Use of quantitative PCR determined that cmiRs- 320a-3p, 320b, 320c, 320e are upregulated, while 320d is downregulated in LD. CmiRs-320 power as classifiers was more powerful in the most extreme and defined forms of LD, including the generalized and the Dunnigan subtypes. cmiR-320a-3p showed significant inverse relationships with plasma leptin (P < 0.0001), typically low in LD. The hepatic enzymes gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and the marker of inflammation C-reactive protein (CRP) were inversely related to cmiR 320d (P < 0.05, for CRP and GGT; P < 0.01, for AST and ALT). Gene ontology analysis revealed cell-cell adhesion as a process regulated by 320 miRNAs targets, thus disclosing a novel route to investigate origin of WAT loss/dysfunction. In conclusion, cmiRs-320 constitute novel biomarkers of LD, abundance of miR320a-3p is inversely associated to indicators related to WAT function, while downregulation of cmiR-320d predicts an altered hepatic profile and higher inflammation.

Maternal fructose consumption downregulates hippocampal catalase expression via DNA methylation in rat offspring

Some studies have demonstrated that excessive fructose consumption negatively impact brain function. Recently, the Developmental Origins of Health and Disease hypothesis - which suggests that maternal nutritional status during gestation and lactation can alter offspring phenotype - has received much attention. In a previous study, we demonstrated that maternal fructose consumption increases levels of lipid peroxides in hippocampi of offspring. The hypothesis in the present study was that maternal fructose intake would affect hippocampal antioxidant enzyme via epigenetic regulation. Upon confirmation of gestation, female rats were assigned to receive either water (control group) or a 20% fructose solution (fructose-fed group). Water or fructose solution were administered to dams from day 1 of gestation to postnatal day 21. Immediately after weaning, hippocampi of offspring were removed for analysis of antioxidant enzyme (Sod1, Sod2, Gpx1, Gpx4, and Cat) messenger RNA transcript levels. Levels of the Cat transcript were significantly lower in the fructose-fed relative to the control group. The Cat protein level was also significantly lower in the fructose-fed relative to the control group as with the messenger RNA transcript levels. Moreover, Cat promoter DNA methylation levels were higher in the fructose-fed group. The present study indicates that maternal fructose consumption may decrease offspring hippocampal Cat transcript levels via altered DNA methylation, which may result in higher levels of oxidative stress due to a decreased ability to neutralize lipid peroxides.

Association between circulating microRNAs and changes in kidney function: A five-year prospective study among Japanese adults without CKD

BACKGROUND

Although a number of microRNAs (miRNA) reflecting kidney function has been identified, prospective studies are now urgently needed to determine a clinical utility of these miRNAs among general populations. The purpose of this study was to examine the associations between serum miRNAs and kidney function in a population-based study.

METHODS

We conducted a five-year prospective study (2012-2017) of 169 individuals without chronic kidney disease (CKD) at the baseline survey (mean age, 62.5; 96 women). The real-time qPCR was used to measure serum levels of five previously reported miRNAs. Participants with eGFR < 60 mL/min/1.73 m² were defined as having CKD. Changes in eGFR were defined as eGFR₂₀₁₇ - eGFR₂₀₁₂.

RESULTS

After adjusting for covariates including baseline eGFR, lower serum levels (1st tertile) of miR-126 were associated with a greater decline of eGFR (β [SE] = -3.18 [1.50]) and a higher odds ratio (OR) of CKD onset over five years (OR [95% CI] = 3.85 [1.01-16.8]), compared with the 3rd tertile.

CONCLUSIONS

We found baseline serum miR-126 levels were associated with changes in eGFR and new CKD cases in a five-year prospective study. This result suggests that miR-126 may be a potential biomarker of CKD even among general populations.

Circulating miR-21, miR-29a, and miR-126 are associated with premature death risk due to cancer and cardiovascular disease: the JACC Study

Primary prevention of premature death is a public health concern worldwide. Circulating microRNAs (miRNAs) have been described as potential diagnostic biomarkers for diseases as cancer and cardiovascular disease (CVD). This case-cohort study aimed to investigate the potential relationship between circulating miRNAs and the risk of premature death. A total of 39,242 subjects provided baseline serum samples in 1988–1990. Of these, 345 subjects who died of intrinsic disease (< 65 years old) and for which measurable samples were available were included in this study. We randomly selected a sub-cohort of 879 subjects. Circulatring miR-21, miR-29a, and miR-126 were determined using qRT-PCR. Conditional logistic regression models were used to analyse the data with respect to stratified miRNA levels. Multivariable logistic regression revealed that subjects with high circulating miR-21 and miR-29a individual levels had a significantly higher risk of total death, cancer death, and CVD death than those with medium miR-21 and miR-29a individual levels. Conversely, subjects with low circulating miR-126 levels had a significantly higher risk of total death than those with medium levels. This suggests that circulating miRNAs are associated with the risk of premature death from cancer and CVD, identifying them as potential biomarkers for early detection of high-risk individuals.

The role of miR-320 in glucose and lipid metabolism disorder-associated diseases

Glucose and lipids are important nutrients that provide the majority of energy for each organ to maintain homeostasis of the body. With the continuous improvement in living standards, the incidence of metabolic disorder-associated diseases, such as diabetes, hyperlipidemia, and atherosclerosis, is increasing worldwide. Among them, diabetes, which could be induced by both glucose and lipid metabolic disorders, is one of the five diseases with the highest incidence and mortality worldwide. However, the detailed molecular mechanisms underlying glucose and lipid metabolism disorders and target-organ damage are still not fully defined. MicroRNAs (miRNAs) are small, non-coding, single-stranded RNAs, which usually affect their target mRNAs in the cytoplasm by post-transcriptional regulation. Previously, we have found that miR-320 contributed to glucose and lipid metabolism via different signaling pathways. Most importantly, we identified that nuclear miR-320 mediated diabetes-induced cardiac dysfunction by activating the transcription of fatty acid metabolic genes to cause lipotoxicity in the heart. Here, we reviewed the roles of miR-320 in glucose and lipid metabolism and target-organ damage.

Circulating microRNAs (miR-126, miR-197, and miR-223) are associated with chronic kidney disease among elderly survivors of the Great East Japan Earthquake

Background

A recent study has reported that incidence of chronic kidney disease (CKD) is higher in evacuees, but the molecular mechanism still remains unclear. One plausible hypothesis is a change in vascular function following to psychological distress. In order to assess molecular mechanisms underlying this association, we examined whether cardiovascular disease (CVD)-associated miRNAs (miR-126, miR-197, and miR-223) were associated with CKD among Japanese elderly survivors after an earthquake.

Methods

We analyzed 1385 individuals (670 men and 715 women) who participated in a post-disaster health check-up after the Great East Japan Earthquake, which occurred in 2011. The check-up involved collection of information about lifestyle, clinical history, the degree of housing damage, and baseline measurement of the estimated glomerular filtration rate. Expression levels of miRNAs were determined using real-time polymerase chain reaction. Estimated glomerular filtration rate (eGFR) was calculated using sex, age, and serum creatinine. CKD was defined as eGFR < 60 ml/min/1.73m². The multivariable regression analyses were performed to examine the associations between CVD-associated miRNAs and CKD after adjusting potential confounders.

Results

Mean age (standard deviation) of participants with normal kidney function and CKD was 62.7 (10.6) and 71.9 (8.1) years, respectively. Expression levels of these miRNAs in participants with CKD were significantly lower than normal kidney function (all p < 0.001). Even after adjusting for lifestyle, clinical profiles, and psychological distress, significant associations between three miRNAs and CKD still remained. A significant linear association between the cumulative score of these miRNAs and CKD was found (p = 0.04).

Conclusions

This cross-sectional study suggested that CVD-associated miRNAs were an important factor of CKD in an elderly Japanese population after earthquake. Future studies need to examine this association in longitudinal dataset.

Association of circulating miR-20a, miR-27a, and miR-126 with non-alcoholic fatty liver disease in general population

Non-alcoholic fatty liver disease (NAFLD) is closely associated with obesity, metabolic syndrome, and type II diabetes mellitus. Recently, circulating microRNAs (miRNAs) have been proposed as useful disease biomarkers. We examined whether circulating miRNAs, such as miR-20a, miR-27a, and miR-126, were useful biomarkers for NAFLD. We conducted a cross-sectional analysis of 527 subjects aged 39 years or older who had undergone a health examination in the Yakumo Study. Of the residents, 92 were diagnosed with NAFLD using a registered medical sonographer. Serum miR-20a, miR-27a and miR-126 levels were measured by quantitative real-time PCR. We then calculated the odds ratios for serum miRNA level changes according to the severity of NAFLD using normal liver status as the reference group. Serum levels of miR-20a and 27a, but not miR-126, were significantly lower in NAFLD subjects than normal subjects. Serum miR-20a and miR-27a levels were significantly lower in both male and female severe NAFLD subjects. Logistic regression analysis showed a significant relationship between low circulating miR-20a and 27a levels and severe NAFLD. Down-regulated circulating miR-20a and 27a levels were significantly associated with severe NAFLD in the general population. Circulating miR-20a and miR-27a may be useful biomarkers for severe NAFLD.

Inflammation related miRNAs as an important player between obesity and cancers

The growing trend in addition to their burden, prevalence, and death has made obesity and cancer two of the most concerning diseases worldwide. Obesity is an important risk factor for common types of cancers where the risk of some cancers is directly related to the obesity. Various inflammatory mechanisms and increased level of pro-inflammatory cytokines have been investigated in many previous studies, which play key roles in the pathophysiology and development of both of these conditions. On the other hand, in the recent years, many studies have individually focused on the biomarker's role and therapeutic targeting of microRNAs (miRNAs) in different types of cancers and obesity including newly discovered small noncoding RNAs (sncRNAs) which regulate gene expression and RNA silencing. This study is a comprehensive review of the main inflammation related miRNAs in obesity/obesity related traits. For the first time, the main roles of miRNAs in obesity related cancers have been discussed in response to the question raised in the following hypothesis; do the main inflammatory miRNAs link obesity with obesity-related cancers regarding their role as biomarkers? Graphical abstractConceptual design of inflammatory miRNAs which provide link between obesity and cancers.

Associations of Circulating MicroRNAs (miR-17, miR-21, and miR-150) and Chronic Kidney Disease in a Japanese Population

Background

MicroRNAs (miRNAs) play crucial roles in the development of various diseases, including chronic kidney disease (CKD). Although previous studies in clinically severe patients have investigated associations between CKD and miRNAs, with particular attention on renal fibrosis, relationships in a general population have yet to be established. The aim of this study was to examine the relationship between expression level of circulating miRNAs and CKD in a middle-aged Japanese population.

Methods

A final total of 513 individuals (216 men and 297 women) who participated in the health check-up program in 2012 were included in our analysis. Quantitative real-time polymerase chain reaction was used to determine expression levels of 22 miRNAs. Estimated glomerular filtration rate (eGFR) was calculated based on serum creatinine level, sex, and age. Participants with eGFR <60 mL/min/1.73 m² were defined as having CKD.

Results

Three different miRNAs (miR-17, miR-21, and miR-150) showed significant correlations with eGFR after Bonferroni correction and were selected for further analyses. Expression levels of miR-17, miR-21, and miR-150 miRNAs were positively associated with eGFR after adjusting for potential confounders (P = 0.004, 0.002, and 0.004, respectively). Logistic regression analyses showed significantly lower odds ratios for CKD (eGFR <60 mL/min/1.73 m²) in the highest tertile of all three miRNAs (miR-17, miR-21, and miR-150) compared with the lowest tertile (P = 0.003, 0.01, and 0.02, respectively).

Conclusions

We found that three circulating miRNAs were significantly associated with CKD in a general Japanese population, which suggested that these miRNAs may be biomarkers for CKD among general adults.

Establishment of a simpler method for measuring HDL-microRNAs

Background

MicroRNAs are present not only in exosomes but also in high-density lipoprotein (HDL) and have the potential as biomarkers for various diseases. Various purification methods have been developed to quantify HDL-miRNAs; however, they are unsuitable for clinical applications. Therefore, we aimed to establish a simpler analytical method to quantify HDL-miRNAs for clinical applications.

Methods

We purified HDL fraction from pooled plasma using a three-step protocol consisting of ultracentrifugation, phosphotungstic acid/MgCl2 precipitation and desalting/buffer exchange followed by the quantification of HDL-miRNAs by quantitative real-time PCR. In order to establish a method to quantify HDL-miRNAs by quantitative real-time PCR, we prepared standard curves for miR-223 and miR-92. The HDL-miRNAs of 10 volunteers were assessed.

Results

Exosomes and LDL were not detected in the purified HDL fraction. Furthermore, we confirmed that only HDL was purified and that the HDL recovery rate of our method was at least approximately 50%. The threshold cycle values of miR-223, miR-92, miR-146a and miR-150 in the same subject were 32.11 ± 0.58, 32.50 ± 0.35, 34.30 ± 0.70 and 34.91 ± 0.77, respectively ( n = 10). The coefficient of variation values for these miRNAs were 1.08–2.21%. In addition, the standard curve for the quantitative analysis of miRNAs showed high linearity (30–30,000 copies/ μL) with a correlation coefficient of >0.99. The concentrations of HDL-miR-223 and HDL-miR-92 in the plasma of 10 subjects were 1.98 ± 0.32 and 0.90 ± 0.14 copies/mL (×104).

Conclusions

We established a simple method for quantifying HDL-miRNAs and improved the sample processing capacity compared with conventional methods.