Lack of association between TGF-beta-1 genotypes and microalbuminuria in essential hypertensive men

Interrelation of cardiovascular risk factors with high albuminury among patients with arterial hypertension living in Mountain Shoriya

AIM

To evaluate the association of a complex of cardiovascular risk factors and genetic markers with the development of high albuminuria among patients with arterial hypertension in the population of Mountain Shoriya, taking into account ethnicity.

MATERIALS AND METHODS

A clinical epidemiological study of a compactly residing population in remote areas of Mountain Shoria was carried out. 1409 people were examined [901 people - representatives of the indigenous nationality (Shorians), 508 people - representatives of non-indigenous nationality (90% of them are Caucasians)]. Hypertension was diagnosed according to the National Guidelines of the Russian Society of Cardiology/the Russian Medical Society on Arterial Hypertension (2010). All patients underwent clinical, laboratory and instrumental investigation. To study the state of the kidneys, the concentration (the presence of elevated levels) of albumin (albuminuria) in the morning portion of urine by an immunoturbidimetric method was analyzed. Polymorphisms of genes ACE (I/D, rs4340), АGT (c.803T>C, rs699), AGTR1 (А1166С, rs5186), ADRB1 (с.145A>G, Ser49Gly, rs1801252), ADRA2B (I/D, rs28365031), MTHFR (c.677С>Т, Ala222Val, rs1801133) and NOS3 (VNTR, 4b/4a) were tested using PCR.

RESULTS

In the group of shors with arterial hypertension, high albuminuria was associated with polymorphisms of the ACE genes (OR=2.05), ADRA2B (OR=6.00), elevated triglyceride level (OR=2.86), decreased index of cholesterol of high density lipoproteins (OR=5.57) and increased index of low density lipoproteins (OR=2.49); in the new population - with polymorphisms of the AGTR1 genes (OR=8.66), ADRA2B (OR=6.53), MTHFR (OR=7.16), obesity (OR=2.72), and abdominal obesity (OR=3.14).

CONCLUSION

The primary predictors determining the development of high albuminuria among patients with arterial hypertension in both ethnic groups were genetic ones. In addition to them, non-genetic risk factors also contributed to the development of this organ damage to the kidneys: age and lipid metabolism disorders in representatives of indigenous nationality; age and abdominal obesity in the examined patients non-indigenous nationality.

Single-trait and multi-trait genome-wide association analyses identify novel loci for blood pressure in African-ancestry populations

Hypertension is a leading cause of global disease, mortality, and disability. While individuals of African descent suffer a disproportionate burden of hypertension and its complications, they have been underrepresented in genetic studies. To identify novel susceptibility loci for blood pressure and hypertension in people of African ancestry, we performed both single and multiple-trait genome-wide association analyses. We analyzed 21 genome-wide association studies comprised of 31,968 individuals of African ancestry, and validated our results with additional 54,395 individuals from multi-ethnic studies. These analyses identified nine loci with eleven independent variants which reached genome-wide significance (P < 1.25×10-8) for either systolic and diastolic blood pressure, hypertension, or for combined traits. Single-trait analyses identified two loci (TARID/TCF21 and LLPH/TMBIM4) and multiple-trait analyses identified one novel locus (FRMD3) for blood pressure. At these three loci, as well as at GRP20/CDH17, associated variants had alleles common only in African-ancestry populations. Functional annotation showed enrichment for genes expressed in immune and kidney cells, as well as in heart and vascular cells/tissues. Experiments driven by these findings and using angiotensin-II induced hypertension in mice showed altered kidney mRNA expression of six genes, suggesting their potential role in hypertension. Our study provides new evidence for genes related to hypertension susceptibility, and the need to study African-ancestry populations in order to identify biologic factors contributing to hypertension.

Q192R Paraoxonase (PON)1 Polymorphism, Insulin Sensitivity, and Endothelial Function in Essential Hypertensive Men

AIMS

Essential hypertension is characterized by increased reactive oxygen species (ROS) generation harmful for insulin sensitivity and nitric oxide (NO)-mediated vasomotor function, a noxious effect that paraoxonase (PON)1, an antioxidant circulating high-density lipoprotein (HDL)-bound esterase, may counteract. The PON1 gene contains several polymorphisms including a glutamine (Q) to arginine (R) transition at position 192 encoding circulating allozymes with higher antioxidant activity that might influence both parameters.

METHODS

Q192R was determined by polymerase chain reaction in 72 never-treated, glucose-tolerant, uncomplicated essential hypertensive men. Insulin sensitivity was assessed by homeostasis model assessment (HOMA) and endothelial function by forearm vasodilation (strain-gage venous plethysmography) to intra-arterial acetylcholine (ACH) with sodium nitroprusside (NIP) as a NO-independent control. Additional evaluation variables included 24-hour blood pressure (BP), lipids, BMI, smoking status, and metabolic syndrome (MetS) by Adult Treatment Panel (ATP)-III criteria. R192 was considered as the rare allele, and its associations analyzed by dominant models (Q/Q vs. Q/R + R/R).

RESULTS

Genotype frequencies were consistent with the Hardy–Weinberg equilibrium. HOMA was lower and insulin resistance (the upper fourth of HOMA values distribution) less prevalent in Q/R + R/R carriers in whom ACH-mediated vasodilatation was greater and endothelial dysfunction (the bottom fourth of ACH^AUC values distribution) less frequent than in Q/Q homozygotes. Q192R polymorphism and MetS were unrelated parameters despite their common association with insulin resistance. 24-hour BP, BMI, lipids, and smoking habits were homogeneously distributed across genotypes.

CONCLUSIONS

Q192R polymorphism associates differentially with insulin sensitivity and endothelial function in essential hypertensive men.

The rs1800471 Polymorphism of TGFB1 Gene, Serum TGF-Beta1 Level and Chronic Kidney Disease Progression

The aim of the study was to investigate whether rs1800471 polymorphism in TGFB1 gene is associated with the development and progression of non-diabetic chronic kidney disease. Moreover, we examined the serum TGF-beta1 concentration and its association with that polymorphism and progression of the disease. We applied two different methodological approaches. Firstly, a family based study was carried out, comprised of 109 patients with non-diabetic chronic kidney disease and their 218 healthy parents, using the transmission/disequilibrium test. The rs1800471 polymorphism and serum TGF-beta1 level were determined in all subjects. Serum TGF-beta1 concentration was also measured in 40 healthy controls. Secondly, we performed a case-control orientated study to determine whether rs1800471 polymorphism and other factors influence the progression of renal impairment. We found no relationships between rs1800471 polymorphism allele transfer and the incidence or progression of non-diabetic chronic kidney disease. We found, however, that the serum TGF-beta1 was significantly higher in patients than in controls. In conclusion, rs1800471 polymorphism in TGFB1 gene does not have an impact on the development and progression of non-diabetic chronic kidney disease caused by primary glomerulopathy and chronic interstitial nephritis. The increased serum TGF-beta1 concentration in such patients suggests its role in the pathomechanism of the disease. Circulating TGF-beta1 level is determined in a multifactorial way, not by rs1800471 polymorphism in TGFB1 gene.

Association of rs1800471 polymorphism of TGFB1 gene with chronic kidney disease occurrence and progression and hypertension appearance

INTRODUCTION

Transforming growth factor β1 (TGF-β1) is a cytokine involved in the process of pathological tissue sclerosis, which is part of the pathophysiological mechanism of end stage renal disease development. The aim of the study was to evaluate the association of the single nucleotide polymorphism rs1800471 of the TGFB1 gene with chronic kidney disease (CKD) occurrence and progression as well as hypertension appearance.

MATERIAL AND METHODS

It was a case-control study where 109 patients with CKD and 111 very old people were enrolled. The association of the studied polymorphism with mentioned diseases was assessed in the whole study group as well as in the subgroups stratified according to the underlying etiology of CKD: nephropathy in type 1 diabetes (n = 13), chronic glomerulonephritis (n = 50) and chronic interstitial nephritis (n = 46).

RESULTS

No association of CKD progression with rs1800471 polymorphism was observed. The C allele was identified as the one associated with higher risk of the disease occurrence in the dominant model of inheritance (p = 0.035). The C allele in women, opposite to male gender, was associated with higher risk of CKD development (p = 0.038). GG genotype was associated with elevated risk of hypertension appearance (p = 0,0021).

CONCLUSIONS

Due to the lack of accordance with previously performed studies it is still impossible to state an unequivocal conclusion regarding the association between rs1800471 polymorphism of the TGFB1 gene and risk of CKD occurrence and progression as well as hypertension appearance. That is why it is necessary to perform further studies in this field.

High-salt diet and hypertension: focus on the renin-angiotensin system

A high-salt diet is one of the major risk factors in the development and maintenance of hypertension. Numerous experimental and observational studies have confirmed the association of sodium intake with blood pressure levels. The effects of a high-salt diet are related to the function of the renin-angiotensin system, which is normally suppressed by a high-salt diet. Endothelial dysfunction probably plays an important role in the influence of high sodium intake on blood pressure, although the exact mechanisms remain elusive. Genetic factors are known to be very important, and various consomic and congenic rat strains as animal models have proven to be very useful in bringing us a step closer to understanding the interaction between salt intake and hypertension. In this article, experimental data obtained in studies on animals and humans, as well as epidemiological data are reviewed.

Inflammation gene variants and susceptibility to albuminuria in the U.S. population: analysis in the Third National Health and Nutrition Examination Survey (NHANES III), 1991-1994

BACKGROUND

Albuminuria, a common marker of kidney damage, serves as an important predictive factor for the progression of kidney disease and for the development of cardiovascular disease. While the underlying etiology is unclear, chronic, low-grade inflammation is a suspected key factor. Genetic variants within genes involved in inflammatory processes may, therefore, contribute to the development of albuminuria.

METHODS

We evaluated 60 polymorphisms within 27 inflammatory response genes in participants from the second phase (1991-1994) of the Third National Health and Nutrition Examination Survey (NHANES III), a population-based and nationally representative survey of the United States. Albuminuria was evaluated as logarithm-transformed albumin-to-creatinine ratio (ACR), as ACR ≥ 30 mg/g, and as ACR above sex-specific thresholds. Multivariable linear regression and haplotype trend analyses were conducted to test for genetic associations in 5321 participants aged 20 years or older. Differences in allele and genotype distributions among non-Hispanic whites, non-Hispanic blacks, and Mexican Americans were tested in additive and codominant genetic models.

RESULTS

Variants in several genes were found to be marginally associated (uncorrected P value < 0.05) with log(ACR) in at least one race/ethnic group, but none remained significant in crude or fully-adjusted models when correcting for the false-discovery rate (FDR). In analyses of sex-specific albuminuria, IL1B (rs1143623) among Mexican Americans remained significantly associated with increased odds, while IL1B (rs1143623), CRP (rs1800947) and NOS3 (rs2070744) were significantly associated with ACR ≥ 30 mg/g in this population (additive models, FDR-P < 0.05). In contrast, no variants were found to be associated with albuminuria among non-Hispanic blacks after adjustment for multiple testing. The only variant among non-Hispanic whites significantly associated with any outcome was TNF rs1800750, which failed the test for Hardy-Weinberg proportions in this population. Haplotypes within MBL2, CRP, ADRB2, IL4R, NOS3, and VDR were significantly associated (FDR-P < 0.05) with log(ACR) or albuminuria in at least one race/ethnic group.

CONCLUSIONS

Our findings suggest a small role for genetic variation within inflammation-related genes to the susceptibility to albuminuria. Additional studies are needed to further assess whether genetic variation in these, and untested, inflammation genes alter the susceptibility to kidney damage.