Relationship of plasma interleukin-6 and its genetic variants with hypertension in Hong Kong Chinese

Circulating cytokines and risk of developing hypertension: A systematic review and meta-analysis

BACKGROUND

Immune responses play a significant role in hypertension, though the importance of key inflammatory mediators remains to be defined. We used a systematic literature review and meta-analysis to study the associations between key cytokines and incident hypertension.

METHODS

We performed a systematic search of Pubmed/Medline, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL), for peer-reviewed studies published up to August 2022. Incident hypertension was defined as systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg and/or the use of antihypertensive medications. Random effects meta-analyses were used to calculate pooled hazard ratios (HRs)/risk ratios (RRs) and 95% confidence intervals by cytokine levels (highest vs. lowest quartile).

RESULTS

Only IL-6 and IL-1β levels have evidence allowing for quantitative evaluation concerning the onset of hypertension. Six studies (10406 participants, 2932 incident cases) examined the association of IL-6 with incident hypertension. The highest versus lowest quartile of circulating IL-6 was associated with a significant HR/RR of hypertension (1.61, 95% CI: 1.00 to 2.60; I2 =87%). After adjusting for potential confounders, including body mass index (BMI), HR/RR was no longer significant (HR/RR: 1.24; 95% CI, 0.96 to 1.61; I2 = 56%). About IL-1β, neither the crude (HR/RR: 1.03; 95% CI, 0.60 to 1.76; n = 2) nor multivariate analysis (HR/RR: 0.97, 95% CI, 0.60 to 1.56; n = 2) suggested a significant association with the risk of developing hypertension.

CONCLUSIONS

A limited number of studies suggest that higher IL-6, but not IL-1β, might be associated with the development of hypertension.

Association of Interleukin-6 Genetic Polymorphisms (rs1800795, -174C > G and rs1800796, -572G > C) With Risk of Essential Hypertension in the Chinese Population

Background Interleukin-6 (IL-6) plays a critical role in essential hypertension (EH) and cardiovascular disease. Evidence suggests two hotspot single nucleotide polymorphisms (SNPs) of the IL-6 gene (rs1800795, -174C > G and rs1800796, -572G > C) might be associated with the susceptibility of EH. However, no consensus has yet been established. Thus, we aimed to investigate the potential association between IL-6 gene polymorphisms and the risk of EH based on a case-control study in a Chinese population. Materials and methods A total of 479 subjects (272 healthy controls and 207 EH patients) were randomly enrolled in our study. After extracting the genomic DNA, two SNPs of the IL-6 gene (rs1800795, -174C > G and rs1800796, -572G > C) were genotyped to analyze the potential association between these genetic variants and EH risk. Multiple genetic models were performed to investigate the strength of association by calculating the odds ratio (OR) and 95% confidence interval (95% CI). The potential effect of SNPs on gene expression was evaluated using expression quantitative trait loci (eQTL) analysis. Results The genotyping findings of IL-6 rs1800795, -174C > G polymorphism showed three study participants with CG genotype and 204 with GG genotype in the EH patients. The IL-6 -174C > G polymorphism was significantly associated with EH risk (P = 0.046) and conferred a reduced risk of EH development (OR = 0.99, 95%CI = 0.97-1.00). Conversely, no substantial association between IL-6 rs1800796, -572G > C polymorphism and the risk of EH was found in all genetic models (P > 0.05). Moreover, the eQTL analysis indicated that the -174C > G polymorphism was significantly associated with gene expression of IL-6 (P = 0.006), and the G allele corresponded to a reduced IL-6 gene expression (Beta = -0.397). Compared with -174C > G, the -572G > C polymorphism was not found to be significantly associated with IL-6 gene expression (Beta = -0.120, P = 0.560). Conclusions Our findings provide evidence that the rs1800795, -174C > G polymorphism can affect the expression levels of IL-6, and the risk of EH occurrence. However, the rs1800796, -572G > C polymorphism does not regulate the IL-6 gene expression levels and the susceptibility of EH.

Hypertension Is Associated with Joint Pain Severity Among Individuals with Osteoarthritis

Previous studies have reported an association between hypertension (HTN) and osteoarthritis (OA). However, limited research has examined the association between HTN and symptoms, such as pain severity, in people with OA. Therefore, the aim was to investigate the prevalence of HTN in individuals with OA and the association between HTN and pain severity in this population. This study was cross-sectional and included participants aged 50 years and older from the community. Demographic data were included and self-reported history of chronic illnesses including diabetes, HTN, cardiovascular disease, dyslipidemia, anemia, osteoporosis, neurological disease, and back pain were obtained. Numerous medications and chronic diseases were included. A subsample of people who self-reported osteoarthritis was included in this study. Pain severity was measured over the past 7 days using a pain numeric rating scale. Multiple linear regression was used after adjusting for covariates. A total of 82 participants with OA were included, and the prevalence of HTN among individuals with OA was 28.91%. Hypertension was significantly associated with increased joint pain severity in this population after adjustments for covariates (B=1.81; 95% CI, 0.65, 2.97; p = .003). Hypertension is prevalent in individuals with OA and is significantly associated with pain severity in this population. Future research should consider the effect of HTN control and medication on symptoms in people with OA. Clinicians may implement screening for HTN among individuals with OA because of the association between HTN and symptoms, such as pain, in this population.

Interleukin 6 mediated activation of the mineralocorticoid receptor in the aldosterone-sensitive distal nephron

Hypertension is characterized by increased sodium (Na+) reabsorption along the aldosterone-sensitive distal nephron (ASDN) as well as chronic systemic inflammation. Interleukin-6 (IL-6) is thought to be a mediator of this inflammatory process. Interestingly, increased Na+ reabsorption within the ASDN does not always correlate with increases in aldosterone (Aldo), the primary hormone that modulates Na+ reabsorption via the mineralocorticoid receptor (MR). Thus, understanding how increased ASDN Na+ reabsorption may occur independent of Aldo stimulation is critical. Here, we show that IL-6 can activate the MR by activating Rac1 and stimulating the generation of reactive oxygen species (ROS) with a consequent increase in thiazide-sensitive Na+ uptake. Using an in vitro model of the distal convoluted tubule (DCT2), mDCT15 cells, we observed nuclear translocation of eGFP-tagged MR after IL-6 treatment. To confirm the activation of downstream transcription factors, mDCT15 cells were transfected with mineralocorticoid response element (MRE)-luciferase reporter constructs; then treated with vehicle, Aldo, or IL-6. Aldosterone or IL-6 treatment increased luciferase activity that was reversed with MR antagonist cotreatment, but IL-6 treatment was reversed by Rac1 inhibition or ROS reduction. In both mDCT15 and mpkCCD cells, IL-6 increased amiloride-sensitive transepithelial Na+ current. ROS and IL-6 increased 22Na+ uptake via the thiazide-sensitive sodium chloride cotransporter (NCC). These results are the first to demonstrate that IL-6 can activate the MR resulting in MRE activation and that IL-6 increases NCC-mediated Na+ reabsorption, providing evidence for an alternative mechanism for stimulating ASDN Na+ uptake during conditions where Aldo-mediated MR stimulation may not occur.

Hypertension and psychosis

Hypertension, a prevalent component of metabolic syndrome (MetS), is a well-known risk factor for cardiovascular diseases (CVD). Psychosis is a feature in the schizophrenia spectrum. Meta-analysis suggests that the prevalence of hypertension in schizophrenia and related disorders is 39%. This may be explained by a unidirectional association between hypertension and psychosis, in that psychosis can be a causative factor of hypertension via antipsychotic medication, inflammation and irregular autonomic nervous system activity through multiple mechanisms. Obesity is a side effect of antipsychotic medication and is a risk factor for hypertension. Obesity leads to raised blood pressure, atherosclerosis, increased triglyceride concentration and decreased high-density lipoprotein concentration. Inflammation accompanies hypertension and obesity. In recent years, the role of inflammation in the onset of psychosis has been increasingly recognised. It underlies the immune dysregulation observed in both schizophrenia and bipolar disorder. Interleukin-6, a marker and driver of inflammation, is related to obesity and plays a role in the pathogenesis of MetS and hypertension. The lack of preventive care of hypertension and other MetS risk factors for patients on antipsychotic medication is reflected in the high incidence of CVD in this population. It is important to detect and treat MetS and hypertension in patients with psychosis in order to reduce cardiovascular morbidity and mortality in this population.

Association of Hypertension with Knee Pain Severity Among People with Knee Osteoarthritis

PURPOSE

To examine the association of hypertension with knee pain severity in individuals with knee osteoarthritis (OA).

DESIGN

Cross-sectional study of baseline data collected by the Osteoarthritis Initiative.

METHODS

Participants with knee OA (N=1,363) were categorized into four groups based on blood pressure (BP): 1) systolic < 120 mm HG and diastolic < 80 mm Hg; 2) 120 ≤ systolic < 130 mm Hg and diastolic < 80 mm Hg; 3) 130 ≤ systolic < 140 mm Hg or 80 ≤ diastolic < 90 mm Hg; 4) systolic ≥ 140 mm Hg or diastolic ≥ 90 mm Hg. OA knee pain severity was measured by Pain subscale of Western Ontario and McMaster Universities Osteoarthritis Index in the past 48 hours, Pain subscale of Knee Injury and Osteoarthritis Outcome Score (KOOS) in the past 7 days, and numeric rating scale (NRS) in the past 30 days. Linear regression was used to examine the relationship between hypertension and knee pain severity.

RESULTS

Compared with the normal BP group, individuals with stage 2 hypertension reported significantly higher OA knee pain severity by KOOS in the past 7 days (β=-2.05 [95% CI -4.09, -0.01], p=0.049) and by NRS in the past 30 days (β=0.31 [95% CI 0.01, 0.62], p=0.045) after adjustments for demographic and medical factors.

CONCLUSIONS

Hypertension was associated with higher OA knee pain severity in individuals with knee OA.

CLINICAL IMPLICATIONS

Nurses can recommend adjunctive non-pharmacological treatments and adherence strategies to help control hypertension, which may help decrease OA knee pain.

Association of the Risk of Osteoarthritis and Hypertension in the Korean Adult Population Aged 40-59 in Pre- and Postmenopausal Women: Using Korea National Health and Nutrition Examination Survey 2012-2016 Data

Purpose

Previous studies reported the relation of osteoarthritis (OA) and hypertension (HTN) mostly in postmenopausal women. This study aimed to identify the association between OA and HTN in pre- and postmenopausal women.

Methods

We used data of 4,627 middle-aged (40–59 years) women from the Korea National Health and Nutrition Examination Survey (KNHANES) from 2012 to 2016. Chi-square and t-test compared the characteristics of the participants. Binomial logistic regression was used to identify an association between OA and HTN under controlling covariates such as age, tobacco smoking, alcohol consumption, and obesity.

Results

There were 1,859 participants with non-OA and menopause, 104 with OA and nonmenopause, and 375 with OA and menopause, respectively. The number of women with OA and HTN was 129. OA was significantly associated with HTN diagnosis in postmenopausal women under controlling covariates (odds ratio: 1.408, 95% CI: 1.092–1.815, p=0.008). However, this relationship was weakened in premenopausal women (odds ratio: 1.651, 95% CI: 0.950–2.869, p=0.075).

Conclusion

In conclusion, women with HTN showed a distinct association with OA than the normotensives, and this relationship was more apparent among postmenopausal women. Further research is needed for a preventive approach.

Investigation of Genetic Susceptibility to Blastomycosis Reveals Interleukin-6 as a Potential Susceptibility Locus

Genetic differences are hypothesized to underlie ethnic disparities in incidence rates of the endemic systemic mycoses, including blastomycosis. Individuals of Hmong ancestry display elevated risk for this serious fungal infection. Here, we interrogated the genomes of Wisconsin (WI) Hmong blastomycosis patients using homozygosity mapping to uncover regions of the genome that are likely shared among the greater Hmong population and filtered for variants with high potential to affect disease susceptibility. This approach uncovered 113 candidate susceptibility variants, and among the most promising are those in genes involved in the interleukin-17 (IL-17) response. In particular, we identified 25 linked variants near the gene encoding IL-6 (IL6). We validated differences in cytokine production between Hmong and European volunteers and formally demonstrated a critical role for IL-6 in the development of adaptive immunity to Blastomyces dermatitidis Our findings suggest that the dysregulation of IL-17 responses underlies a recently reported and poorly understood ethnic health disparity.IMPORTANCE Blastomycosis is a potentially life-threatening infection caused by the fungus Blastomyces dermatitidis As with related fungal diseases, blastomycosis is noted to affect some populations more than others. These patterns of illness are often not related to predisposing conditions or exposure risks; thus, genetic differences are thought to underlie these health disparities. People of Hmong ancestry in Wisconsin are at elevated risk of blastomycosis compared to the general population. We studied the genetic codes of Hmong blastomycosis patients and identified candidate sites in their genomes that may explain their susceptibility to this infection. We further studied one particular region of the genome that is involved with the immune processes that fight B. dermatitidis Our work revealed population differences in the response to fungi. A better understanding of the genetic underpinnings of susceptibility to infectious diseases has broader implications for community health, especially in the paradigm of personalized medicine.

Factors Associated with the Risk of Developing Coronary Artery Disease in Medicated Patients with Major Depressive Disorder

Background: The aim of this study was to identify factors associated with high Framingham Risk Score (FRS) in medicated patients with major depressive disorder (MDD). Methods: We examined 61 medicated patients with MDD (mean age 37.77 ± 7.67, 90.2% women) and 43 non-depressed controls (mean age 38.26 ± 9.20, 90.7% women). We administered the Hamilton Depression Rating Scale (HAM-D) and measured systolic blood pressure (SBP), diastolic BP (DBP), mean arterial BP (MAP), pulse wave velocity (PWV), intima-media thickness (IMT), interleukin-6 (IL-6) and triglycerides. Results: We found that medicated patients with MDD had significantly higher levels of HAM-D score (p < 0.01), SBP (p = 0.015), MAP (p = 0.037), IL−6 level (p = 0.007), as compared with controls. Medicated patients who remained moderately to severely depressed showed significantly higher SBP (p = 0.049), DBP (p = 0.009), MAP (p = 0.024), IL−6 level (p = 0.019), left PWV (p = 0.004) and average PWV (p = 0.026) than those with mild depression. Multivariate regression showed that the interaction effect between HAM-D score and triglyceride level (p = 0.018) was significantly associated with FRS in medicated patients with MDD. Conclusions: This study highlights that the interaction effect of the severity of depression and the triglyceride level, was a modifiable factor positively associated with high FRS.

CRP genetic variants are associated with mortality and depressive symptoms in chronic heart failure patients

OBJECTIVE

Heart failure (HF) is a complex medical condition with a multitude of genetic and other factors being involved in the pathogenesis. Emerging evidence points to an involvement of inflammatory mechanisms at least in subgroups of patients. The same is true for depression and depressive symptoms, which have a high prevalence in HF patients and are risk factors for the development and outcomes of cardiovascular disease.

METHODS

In 936 patients of the Interdisciplinary Network Heart Failure (INH) program, CRP and IL-6 protein blood levels were measured and genetic variants (single nucleotide polymorphisms) of the CRP and IL6 gene analyzed regarding their influence on mortality.

RESULTS

Less common recessive genotypes of two single nucleotide polymorphisms in the CRP gene (rs1800947 and rs11265263) were associated with significantly higher mortality risk (p < 0.006), higher CRP levels (p = 0.029, p = 0.006) and increased depressive symptoms in the PHQ-9 (p = 0.005, p = 0.003). Variants in the IL-6 gene were not associated with mortality.

CONCLUSION

Our results hint towards an association of less common CRP genetic variants with increased mortality risk, depressive symptoms and peripheral CRP levels in this population of HF patients thereby suggesting a possible role of the inflammatory system as link between poor prognosis in HF and depressive symptoms.

Association between hypertension and risk of knee osteoarthritis: A meta-analysis of observational studies

Evidence from observational studies shows that hypertension may be a risk factor for knee osteoarthritis (OA). However, the relationship between hypertension and knee OA risk remains controversial. This study aimed to quantitatively assess the relationship between hypertension and risk of knee OA.Three electronic databases (PubMed, Embase, and Cochrane Library) were searched up to July 25, 2016. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were extracted from the included observational studies. Publication bias, heterogeneity test, and subgroup analyses were performed.Eight studies including 2 cohort studies and 6 cross-sectional studies with 9762 participants were finally included in this meta-analysis. The results showed that hypertension was significantly associated with higher radiographic knee OA and symptomatic knee OA risks of 2.01 (95% CI, 1.28-3.15, I = 90.2%, P for heterogeneity <.001) and 1.49 (95% CI, 1.26-1.77, I = 0%, P for heterogeneity <.412), respectively. No publication bias was detected. The subgroup analysis showed that the study design did not influence the results (radiographic knee OA: OR = 1.42, 95% CI, 1.19-1.71 for cross-sectional studies and OR = 2.17, 95% CI, 1.30-3.63 for cohort studies; and symptomatic knee OA: OR = 1.85, 95% CI, 1.10-3.13) for cross-sectional studies and OR = 2.74, 95% CI, 1.81-4.16 for cohort studies).This meta-analysis showed that there was a significant relationship between hypertension and knee OA (both radiographic and symptomatic). However, further original studies are needed that use a better design.

Novel Immune Mechanisms in Hypertension and Cardiovascular Risk

PURPOSE OF REVIEW

Hypertension is a common disorder with substantial impact on public health due to highly elevated cardiovascular risk. The mechanisms still remain unclear and treatments are not sufficient to reduce risk in majority of patients. Inflammatory mechanisms may provide an important mechanism linking hypertension and cardiovascular risk. We aim to review newly identified immune and inflammatory mechanisms of hypertension with focus on their potential therapeutic impact.

RECENT FINDINGS

In addition to the established role of the vasculature, kidneys and central nervous system in pathogenesis of hypertension, low-grade inflammation contributes to this disorder as indicated by experimental models and GWAS studies pointing to SH2B3 immune gene as top key driver of hypertension. Immune responses in hypertension are greatly driven by neoantigens generated by oxidative stress and modulated by chemokines such as RANTES, IP-10 and microRNAs including miR-21 and miR-155 with other molecules under investigation. Cells of both innate and adoptive immune system infiltrate vasculature and kidneys, affecting their function by releasing pro-inflammatory mediators and reactive oxygen species.

SUMMARY

Immune and inflammatory mechanisms of hypertension provide a link between high blood pressure and increased cardiovascular risk, and reduction of blood pressure without attention to these underlying mechanisms is not sufficient to reduce risk.

Interleukin-6 and rs1800796 locus single nucleotide polymorphisms in response to hypoxia/reoxygenation in hepatocytes

Ischemia-reperfusion injury due to hypoxia/reoxygenation (H/R) is one of the main causes of liver damage during liver surgery. Donor interleukin-6 (IL-6) rs1800796 single nucleotide polymorphisms (SNPs) affect the metabolism of tacrolimus following liver transplantation-related hepatic H/R. This study investigated the response of IL-6 and its promoter polymorphisms to hepatic H/R in liver parenchymal cells. The association between IL-6 rs1800796 SNPs and IL‑6 expression was measured in 84 disease-free liver tissues using tissue microarrays and immunohistochemistry. Subsequently, LO2G, LO2C and NC-LO2 cells were successfully constructed via stable lentivirus-mediated transfection. The effects of IL-6 and its SNPs on the biological function of LO2 cells were examined using a cell model of H/R. Our results revealed that IL-6 was mainly expressed in hepatocytes. The intermediate IL-6 expression rate in genotype CC carriers was higher than that in genotype CG/GG carriers (P=0.006), which was subsequently verified at the IL-6 mRNA level (P=0.002). The concentrations of alanine aminotransferase in the LO2G cells were significantly higher than those in the LO2C cells following H/R for 6 h and H/R for 24 h (P<0.05). The viability of the LO2C cells was higher than that of the LO2G cells (P<0.05). Furthermore, the expression of IL-6 and its downstream molecules was significantly increased in the LO2C cells compared with the LO2G cells (P<0.05). Therefore, the sequence variants of rs1800796 SNPs (G→C) exhibit an increased IL-6 transcription efficiency in liver parenchymal cells. In addition, the increased expression of IL-6 protects the hepatocytes following hepatic H/R injury.

Association Between Interleukin-6 -572 C>G and -174 G>C Polymorphisms and Hypertension: A Meta-analysis of Case-control Studies

Whether hypertension is associated with -572 C>G or -174 G>C polymorphism in interleukin (IL)-6 genes still remains hazy and ambiguous.We conducted a meta-analysis to offer a more reliable and clearer evaluation about the association.Electronic literature databases including PubMed, Web of Science, EMBASE, Google Scholar, Chinese National Knowledge Infrastructure and Wanfang database were searched.The study included the following: evaluating associations between -572 C>G or -174 G>C polymorphism in IL-6 gene and hypertension; case-control design; essential information must be offered; precise diagnostic criteria of hypertension; and no language restriction.Patients who met the diagnostic criteria and controls without a history of hypertension were included. Interventions were not available.A quality assessment was conducted using Newcastle-Ottawa scale. Combined odds ratios with 95% confidence intervals were calculated in 5 genetic models. Sources of heterogeneity were explored by subgroup analysis, meta-regression, and Galbraith plots. Finally, test for publication bias was performed to prove the stabilization.Fifteen studies were finally included. Eleven articles were judged high-quality reports. Overall, the -572 C>G polymorphism was proved to be significantly associated with hypertension in 4 genetic models. Subgroup analysis based on ethnicity revealed significant associations in Asian population in recessive model and homozygote comparison. The association in Europeans and Mid-East required further confirmation. No significant association was observed between the -174 G>C polymorphism and hypertension under all of the genetic models.The limitations of the study were the following: restrictive number of eligible studies limited the extrapolation range in subgroup analysis; gene-environment factors could not be described due to lack of data; some relevant studies could not be included because of various reasons.Current researches supported the association between the development of hypertension and the -572 C>G rather than -174 G>C polymorphism. Future well designed epidemiological studies may evaluate the possible gene-environment interactions.

Overweight, adipocytokines and hypertension: a prospective population-based study

OBJECTIVE

The adipocytokines, leptin, adiponectin, and interleukin-6, which stimulate liver C-reactive protein (CRP) production, are regarded as potential candidate intermediates between adipose tissue and overweight-induced hypertension.

METHODS

We examined the associations between leptin, adiponectin, and CRP levels with both prevalent and 5-year incident hypertension (IHT) in a general population of Danish adults (n = 5,868, 51.3% women, mean age 45.8 ± 7.9 years).

RESULTS

We recorded 2195 prevalent and 379 incident cases of hypertension. In models including leptin, CRP, adiponectin, sex, age, lifestyle risk factors, lipids, insulin, hemoglobin A1c, and in the incident model also baseline heart rate and blood pressure, only leptin of the three candidate intermediates was significantly associated with both prevalent and IHT [odds ratio (OR) = 1.18, 95% confidence interval (CI) 1.06-1.32, P = 0.002, and OR = 1.24, 95% CI 1.01-1.54, P = 0.044] for one standard deviation increase in log-transformed leptin levels, respectively. Log-transformed CRP was associated with prevalent (OR = 1.16, 95% CI 1.07-1.26, P < 0.001) but not IHT (OR = 0.98, 95% CI 0.84-1.14, P = 0.76). Log-transformed adiponectin was neither associated with prevalent nor IHT (OR = 0.94, 95% CI 0.87-1.02, P = 0.11 and OR = 0.93, 95% CI 0.80-1.08, P = 0.33). Comparing the lowest with the highest quintile of sex-specific BMI levels, there was an almost two-fold increase in IHT (OR = 1.89, 95% CI 1.10-3.25, P = 0.023) in the fully adjusted model. The population attributable risk estimate of IHT owing to overweight was 31%.

CONCLUSION

Leptin, but not adiponectin or CRP, may play a mediating role in overweight-induced hypertension. However, as BMI was a strong independent predictor of hypertension, other factors than leptin must be involved in the pathogenesis of overweight-related hypertension.

Linkage and association between interleukin-6 gene polymorphisms and ischemic stroke: a family-based study in the northern Chinese Han population

BACKGROUND

Numerous genetic risk factors of ischemic stroke (IS) have been reported from both candidate gene and genome-wide strategies with inconsistent results. The objective of this study was to confirm the relationship between 10 previously identified single-nucleotide polymorphisms (SNPs) and IS in the Chinese population.

METHODS

A family-based study was conducted in a rural area of Beijing, with a total of 227 IS families with 622 participants recruited. Both linkage and association analyses were performed, with all the sibling pairs derived from the 227 families analyzed using the sib-pair test of model-free linkage to assess linkage between SNPs and IS, with association analyses including a family-based association test (FBAT) and generalized estimating equations (GEE).

RESULTS

Nonparametric linkage analysis revealed that the rs1800796 polymorphism in the interleukin-6 (IL-6) gene is significantly linked to the small arterial occlusion (SAO) subtype (p=0.022), while the rs7193343 polymorphism in the ZFHX3 gene is linked to IS (p=0.002) under the dominant model. Significant allelic associations were identified between the G allele of rs1800796 and IS (p=0.042) and the SAO subtype (p=0.025) in the FBAT. The GEE method revealed that the G allele of rs1800796 increased IS risk by 1.55-fold (95% 95% confidence interval [CI]: 1.01, 2.37; p=0.043) and 2.43-fold (95% CI: 1.32, 4.45; p=0.004) in the SAO subtype in the dominant model, which correlated with the significant associations detected in the FBAT.

CONCLUSIONS

In this study, we confirmed that the SNP of rs1800796 in the IL-6 gene is related to IS and the SAO subtype using different statistical approaches. These findings could contribute to identifying individuals with a high IS risk.

Response to the dipeptidyl peptidase-4 inhibitors in Japanese patients with type 2 diabetes might be associated with a diplotype of two single nucleotide polymorphisms on the interleukin-6 promoter region under a certain level of physical activity

Aims/Introduction

Muscle-derived interleukin-6 (IL-6) has been reported to promote glucagon-like peptide-1 (GLP-1) secretion, and we explored the association of single nucleotide polymorphisms (SNPs) in the human IL-6 promoter region with the responsiveness to dipeptidyl peptidase-4 inhibitors (DPP-4Is), drugs that increase circulating GLP-1.

Materials and Methods

The present observational study enrolled Japanese patients with type 2 diabetes who took a DPP-4I over 3 months, and most of the clinical information was collected retrospectively. We defined non-responders as those having less than a 0.2% decrease of the glycated hemoglobin level at 3 or 4 months after starting DPP-4I treatment. Physical activity was retrospectively estimated by the Japanese short version of International Physical Activity Questionnaire.

Results

We studied 316 patients whose physical activity corresponding to the season of the DPP-4I administration was estimated. The non-responder rate was 29.7%. We analyzed rs1800796 and rs2097677, both are suggested to be functional in Japanese. Multivariate analysis for all patients showed that the adjusted odds ratio for the non-responder risk of the diplotype rs1800796 G/*–rs2097677 A/* against C/C-G/G (OR_G*A*) was 0.445 (P = 0.068). When patients were stratified by the International Physical Activity Questionnaire into low (n = 149) and moderate/high (n = 167) activity groups, however, OR_G*A* in each group was 1.58 (P = 0.615) and 0.153 (P = 0.003), respectively.

Conclusions

The diplotype rs1800796 G/*–rs2097677 A/* might contribute to responsiveness to DPP-4Is in Japanese patients with type 2 diabetes under a certain level of physical activity. However, further investigation is warranted to confirm this.

A single nucleotide polymorphism of interleukin-6 gene is related to plasma adrenomedullin levels

OBJECTIVE

Elevated plasma adrenomedullin (ADM) levels are associated with cardiovascular diseases. Single nucleotide polymorphisms (SNPs) in the gene encoding ADM (ADM) are associated with plasma ADM levels. The presence of a nuclear factor for interleukin-6 (IL-6) expression binding site in the promoter region of the ADM gene suggests a possible relationship between the expression of the ADM and IL-6. Therefore, we investigated whether plasma ADM levels are related to SNPs in the gene encoding IL-6 (IL6).

METHODS

Plasma ADM levels were measured in 476 subjects in the Hong Kong Cardiovascular Risk Factor Prevalence Study-2 (CRISPS2). The subjects were genotyped for three tagging SNPs in the IL6 gene.

RESULTS

The minor allele frequencies of the IL6 SNPs rs17147230, rs1800796 and rs2069837 were 41·8%, 20·0% and 15·4%, respectively. The tagging SNP, rs17147230, was associated with plasma ADM levels after adjusting for age and sex (β=-0·096, P = 0·034). The association was significant in women (β=-0·115, P = 0·021) but not in men. Among all subjects, plasma ADM levels decreased with an increasing number of minor alleles of rs17147230 in multivariate analysis (P = 0·034). Compared to subjects with the AA genotype, subjects with the TT genotype had plasma ADM levels 12·8% lower (95% CI: 0·6-23·5%, P = 0·041). Haplotype analysis demonstrated a significant association of the haplotype ACA with plasma ADM levels in women (P < 0·05).

CONCLUSION

Plasma ADM levels are related to the SNP rs17147230 in IL6 gene. The effect of the polymorphism on inflammation and cardiovascular disease remains to be determined.

The mosaic theory revisited: common molecular mechanisms coordinating diverse organ and cellular events in hypertension

More than 60 years ago, Dr. Irvine Page proposed the Mosaic Theory of hypertension, which states that many factors, including genetics, environment, adaptive, neural, mechanical, and hormonal perturbations interdigitate to raise blood pressure. In the past two decades, it has become clear that common molecular and cellular events in various organs underlie many features of the Mosaic Theory. Two of these are the production of reactive oxygen species and inflammation. These factors increase neuronal firing in specific brain centers, increase sympathetic outflow, alter vascular tone and morphology, and promote sodium retention in the kidney. Moreover, factors such as genetics and environment contribute to oxidant generation and inflammation. Other common cellular signals, including calcium signaling and endoplasmic reticulum stress are similarly perturbed in different cells in hypertension and contribute to components of Page's theory. Thus, Page's Mosaic Theory formed a framework for future studies of molecular and cellular signals in the context of hypertension, and has greatly aided our understanding of this complex disease.

Association between metabolic syndrome and carotid atherosclerosis: a community-based study in Hong Kong

BACKGROUND

Carotid atherosclerosis should not be neglected as a cause for stroke in China, despite its low prevalence. This study was performed to evaluate the association between ultrasonographic markers for different stages of carotid atherosclerosis and metabolic syndrome.

METHODS

This was a community-based study in Hong Kong. Metabolic syndrome was defined as having three or more of the following conditions or receiving specific treatment for these conditions: Abdominal obesity, elevated triglycerides, low high-density lipoprotein cholesterol, hypertension, and impaired fasting blood glucose. All subjects underwent carotid duplex ultrasonography. Mean carotid intima media thickness (CIMT) of bilateral common carotid arteries was used as the CIMT value for a single subject. CIMT within the 4(th) quartile was regarded as increased CIMT. Carotid plaque was defined as a focal CIMT of >1.5 mm. A carotid plaque obstructing ≥50% of vessel lumen was considered as carotid stenosis.

RESULTS

A total of 653 subjects (mean age 55.1±10.4; 47.2% male) were recruited. Metabolic syndrome was found in 188 (28.8%) subjects (30.8% in males and 27.0% in females). Mean CIMT was 0.74±0.12 mm. Increased CIMT, carotid plaque, and carotid stenosis were detected in 163 (25.0%), 95 (14.5%), and 6 (1.4%) subjects, respectively. In multivariate linear regression, CIMT significantly increased with increasing numbers of metabolic syndrome components (P<0.001). In multivariate logistic regression analysis, metabolic syndrome was independently associated with increased CIMT [odds ratio (OR) 1.17; 95% confidence interval (CI) 1.11-2.64; P=0.014), but not presence of carotid plaque (OR 1.50; 95% CI 0.92-2.46; P=0.108).

CONCLUSIONS

Metabolic syndrome may be independently associated with the early stage but not the later and advanced stages of carotid atherosclerosis in community residents in China.