Linkage analysis of angiotensin-converting enzyme (ACE) insertion/deletion polymorphism and systemic lupus erythematosus

Association of angiotensin-converting enzyme (ACE) I/D variation with biochemical parameters and oxidative stress markers in systemic lupus erythematosus patients in west of Iran

PURPOSE

We aimed to study insertion/deletion (I/D) variation (rs4646994) of ACE gene in a group of SLE patients in west of Iran and its possible relationship with oxidative stress.

METHOD AND RESULTS

Genotypes and allele frequencies related to ACE (I/D) variation were determined in 108 SLE patients and 110 gender and age-matched healthy controls using PCR. Neopterin, malondialdehyde (MDA), and serum lipid concentrations were determined by HPLC and enzyme assay respectively. The overall distribution of ACE I/D genotypes in SLE patients was different from that of the control group (P = 0.005). DD genotype compared to ID genotype increased the risk of SLE (OR = 2.57, 95% CI 1.4-4.8, P = 0.003). ID genotype compared to the II genotype decreased the risk of disease (OR = 0.45, 95% CI 0.2-0.99, p = 0.042). SLE patients with DD, ID, and II genotypes had lower paraoxonase (PON) activity and higher serum levels of MDA and neopterin versus control patients. We also detected a significant protective effect against SLE in presence of ACE I alleles and lack of angiotensin II receptor, type 1 (AGTR1) A1166C (NCBI reference SNP id: rs5186), C alleles in this study (OR = 0.31, 95% CI 0.14-0.68, P = 0.002).

CONCLUSIONS

Carriers of the DD genotype of ACE gene with higher serum concentrations of neopterin and MDA, and lower PON activity had a high risk to develop SLE, while ID genotype decreased the risk of disease development by 2.22 times compared to II genotype.

Upregulation of Proinflammatory Bradykinin Peptides in Systemic Lupus Erythematosus and Rheumatoid Arthritis

Our recent study has implicated bradykinin (BK) signaling as being of pathogenic importance in lupus. This study aims to investigate the biomarker potential of BK peptides, BK and BK-des-arg-9, in lupus and other rheumatic autoimmune diseases. Sera from systemic lupus erythematosus (SLE) patients and healthy subjects were screened for BK and BK-des-arg-9 by liquid chromatography-mass spectrometry metabolomics. Serum from 6-mo-old C57BL/6 mice and three murine lupus strains were also screened for the two peptides by metabolomics. Given the promising initial screening results, validation of these two peptides was next conducted using multiple reaction monitoring in larger patient cohorts. In initial metabolomics screening, BK-des-arg-9 was 22-fold higher in SLE serum and 106-fold higher in mouse lupus serum compared with healthy controls. In validation assays using multiple reaction monitoring and quadrupole time-of-flight mass spectrometry, BK and BK-des-arg-9 showed significant elevations in SLE serum compared with controls (p < 0.0001; area under the curve = 0.79-0.88), with a similar but less pronounced increase being noted in rheumatoid arthritis serum. Interestingly, increased renal SLE disease activity index in lupus patients was associated with reduced circulating BK-des-arg-9, and the reasons for this remain to be explored. To sum, increased conversion of BK to the proinflammatory metabolite BK-des-arg-9 appears to be a common theme in systemic rheumatic diseases. Besides serving as an early marker for systemic autoimmunity, independent studies also show that this metabolic axis may also be a pathogenic driver and therapeutic target in lupus.

Autoimmune Disease-Associated Hypertension

Purpose of Review

To highlight important new findings on the topic of autoimmune disease-associated hypertension.

Recent Findings

Autoimmune diseases including systemic lupus erythematosus and rheumatoid arthritis are associated with an increased risk for hypertension and cardiovascular disease. A complex interaction among genetic, environmental, hormonal, and metabolic factors contribute to autoimmune disease susceptibility while promoting chronic inflammation that can lead to alterations in blood pressure. Recent studies emphasize an important mechanistic role for autoantibodies in autoimmune disease-associated hypertension. Moving forward, understanding how sex hormones, neutrophils, and mitochondrial dysfunction contribute to hypertension in autoimmune disease will be important.

Summary

This review examines the prevalent hypertension in autoimmune disease with a focus on the impact of immune system dysfunction on vascular dysfunction and renal hemodynamics as primary mediators with oxidative stress as a main contributor.

Angiotensin-Converting Enzyme Gene I/D Polymorphism Is Associated With Systemic Lupus Erythematosus Susceptibility: An Updated Meta-Analysis and Trial Sequential Analysis

Angiotensin-converting enzyme (ACE) gene is indispensable for endothelial control and vascular tone regulatory systems, usually affected in Systemic Lupus Erythematosus (SLE). ACE insertion/deletion (I/D) polymorphism may influence the progress of SLE. Earlier studies have investigated this association without any consistency in results. We performed this meta-analysis to evaluate the precise association between ACE I/D polymorphism and SLE susceptibility. The relevant studies were searched until December, 2017 using Medline (PubMed), Google-Scholar and EMBASE search engines. Twenty-five published studies involving 3,308 cases and 4,235 controls were included in this meta-analysis. Statistically significant increased risk was found for allelic (D vs. I: p = 0.007; OR = 1.202, 95% CI = 1.052–1.374), homozygous (DD vs. II: p = 0.025; OR = 1.347, 95% CI = 1.038–1.748), dominant (DD+ID vs. II: p = 0.002; OR = 1.195, 95% CI = 1.070–1.334), and recessive (DD vs. ID+II: p = 0.023; OR = 1.338, 95% CI = 1.042–1.718) genetic models. Subgroup analysis stratified by Asian ethnicity revealed significant risk of SLE in allelic (D vs. I: p = 0.045; OR = 1.238, 95% CI = 1.005–1.525) and marginal risk in dominant (DD+ID vs. II: p = 0.056; OR = 1.192, 95% CI = 0.995–1.428) models; whereas, no association was observed for Caucasian and African population. Publication bias was absent. In conclusion, ACE I/D polymorphism has significant role in overall SLE risk and it can be exploited as a prognostic marker for early SLE predisposition.

An Extensive Study of the Functional Polymorphisms of Kinin-Kallikrein System in Rheumatoid Arthritis Susceptibility

Objectives

This study aims to examine the following functional polymorphisms in rheumatoid arthritis (RA) susceptibility: (i) the 587C>T of kininogen gene, (ii) the 287 bp Alu repeat insertion of angiotensin converting enzyme gene, (iii) the 9 bp insertion of bradykinin receptor 2 gene, (iv) the -58T>C of bradykinin receptor 2 gene, and (v) the -699G>C of bradykinin receptor 1 gene.

Patients and methods

The study included 136 RA patients (27 males; 109 females; mean age 60.8 years; range 39 to 75 years) and 149 ethnic matching controls (30 males, 119 females; mean age 56.2 years; range 35 to 78 years). Polymerase chain reaction coupled with restriction assay was performed for 587C>T, -58T>C, and -699G>C.

Results

Rheumatoid arthritis patients and controls carried the wild type allele of 587C>T; therefore, produced the high molecular weight kininogen. No significant difference was observed in genotype or allele distribution of the studied functional polymorphisms between RA patients and controls.

Conclusion

Kinin-kallikrein system related genes might not be major RA susceptibility loci.

Association of angiotensin-converting enzyme insertion/deletion polymorphism with susceptibility to systemic lupus erythematosus: a meta-analysis

BACKGROUND

The aim of this study was to determine whether the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism confers susceptibility to systemic lupus erythematosus (SLE)/lupus nephritis (LN).

METHODS

A meta-analysis was conducted on the association between the ACE I/D polymorphism and SLE/LN (when available) using: (i) the allelic contrast; (ii) the recessive; (iii) the dominant; and (iv) the additive models.

RESULTS

A total of 27 relevant comparisons meeting the inclusion criteria were identified, involving 2718 SLE patients and 3655 controls. Meta-analysis showed a significant association between SLE and the allele D in overall populations (odds ratio [OR] = 1.25, 95% CI: 1.07-1.48, P = 0.004). Stratification by ethnicity indicated a strong association between the allele D and SLE in Asians (OR = 1.36, 95% CI: 1.05-1.75, P = 0.019). Meta-analysis also showed a significant association between SLE and the DD genotype in overall populations (additive model) (OR = 1.38, 95% CI: 1.05-1.83, P = 0.022). In addition, we found significant associations between the recessive model and SLE in overall populations, Asians and Europeans (OR = 1.44, 95% CI: 1.11-1.88, P = 0.007; OR = 1.69, 95% CI: 1.07-2.68, P = 0.024; and OR = 1.31, 95% CI: 1.06-1.62, P = 0.013, respectively). With respect to the association between ACE I/D gene polymorphism and LN risk, there was no significant association in either the overall populations or subpopulations.

CONCLUSION

The present study might suggest that ACE I/D polymorphism may be a genetic molecular marker to predict SLE, while this polymorphism may not correlate with LN susceptibility.

Immunologic Effects of the Renin-Angiotensin System

Inappropriate activation of the renin-angiotensin system (RAS) exacerbates renal and vascular injury. Accordingly, treatment with global RAS antagonists attenuates cardiovascular risk and slows the progression of proteinuric kidney disease. By reducing BP, RAS inhibitors limit secondary immune activation responding to hemodynamic injury in the target organ. However, RAS activation in hematopoietic cells has immunologic effects that diverge from those of RAS stimulation in the kidney and vasculature. In preclinical studies, activating type 1 angiotensin (AT₁) receptors in T lymphocytes and myeloid cells blunts the polarization of these cells toward proinflammatory phenotypes, protecting the kidney from hypertensive injury and fibrosis. These endogenous functions of immune AT₁ receptors temper the pathogenic actions of renal and vascular AT₁ receptors during hypertension. By counteracting the effects of AT₁ receptor stimulation in the target organ, exogenous administration of AT₂ receptor agonists or angiotensin 1-7 analogs may similarly limit inflammatory injury to the heart and kidney. Moreover, although angiotensin II is the classic effector molecule of the RAS, several RAS enzymes affect immune homeostasis independently of canonic angiotensin II generation. Thus, as reviewed here, multiple components of the RAS signaling cascade influence inflammatory cell phenotype and function with unpredictable and context-specific effects on innate and adaptive immunity.

Angiotensin-converting enzyme insertion/deletion gene polymorphism in Egyptian children with systemic lupus erythematosus: a possible relation to proliferative nephritis

Introduction Angiotensin-converting enzyme (ACE) is crucial in the pathogenesis of systemic lupus erythematosus through angiotensin II which regulates vascular tone and endothelial functions. Objectives To study the frequency of ACE insertion/deletion (I/D) gene polymorphism in Egyptian children with systemic lupus erythematosus and its possible relation to the renal pathology in cases with lupus nephritis. Subjects and methods The frequency of ACE gene insertion/deletion polymorphism genotypes was determined in 78 Egyptian children with systemic lupus erythematosus and compared to a matched group of 140 healthy controls using polymerase chain reaction. Results The DD genotype of the ACE gene was higher in systemic lupus erythematosus patients when compared to controls ( P<0.0001; odds ratio (OR) 2.4; 95% confidence interval (CI) 1.7-3.3) and the D allele was more frequent than the I allele in systemic lupus erythematosus patients in comparison to controls ( P < 0.0001; OR = 2.2; 95% CI = (1.6-3.1). In the lupus nephritis group, the DD genotype was significantly higher in those with proliferative lupus nephritis when compared to those with non-proliferative lupus nephritis ( P = 0.02; OR = 1.45; 95% CI = 1.4-1.6). Also, patients with proliferative lupus nephritis showed a higher frequency of the D allele ( P < 0.001; OR = 1.98; 95% CI = 1.3-2.9). Conclusion The D allele and DD genotype of the ACE gene appear to be a risk factor for the susceptibility of systemic lupus erythematosus and occurrence of proliferative nephritis in Egyptian children.

Polymorphisms of the renin-angiotensin system genes in Brazilian patients with lupus nephropathy

Genetic polymorphisms of the renin-angiotensin system (RAS) has been associated with cardiovascular events and the progression of nephropathy in several diseases. The objective of this study was to evaluate a possible association of the genetic polymorphisms of RAS with the development and/or progression of lupus nephritis in a Brazilian population. Seventy-five SLE patients with lupus nephropathy (LN group) were compared to 72 SLE patients without LN (SLE group) and 65 healthy individuals (CONTROL group), of sex and ethnic matched, in a Brazilian population sample. Mean global follow-up was 9 + 6 years for lupus without nephropathy and 11 + 7 years for lupus nephropathy. Following the extraction of genomic DNA from the leukocytes in the peripheral blood, angiotensin converting enzyme (ACE I/D), angiotensinogen (AGT M235T) and angiotensin II type 1 receptor (AGTR1 A1166C) genotypes were determined by the polymerase chain reaction.

No significant difference of ACE, AGT and AGTR1 genotypes distribution between groups was observed in this study. There was no significant association between the variables of the RAS genotypes and the presence of hypertension in SLE. However, an increased frequency of DD genotype (ACE I/D) was observed in SLE patients with LN who progressed to CRF compared to healthy controls (DD 60%, DI 26.7%, II 13.3% versus 27.7%, 60% and 12.3%, respectively; x2 = 6.299, P = 0.0429). In the population studied, there was no influence of the RAS genetic polymorphisms in the development of lupus nephropathy, but the progression to CRF was associated with ACE DD polymorphism.

The renin-angiotensin system in lupus: physiology, genes and practice, in animals and humans

Although multiple studies suggest a potential role for angiotensin II in inflammation, most were performed either in vitro or in animals with non-immune-complex-mediated diseases. Extrapolation of these findings to humans, particularly patients with lupus, which involves multiple immunoregulatory pathways, is unclear. In autoimmune-prone MRL/lpr mice, angiotensin-converting-enzyme (ACE) inhibition improved survival although to a lesser degree than cyclophosphamide and diminished the glomerular histopathologic damage, proteinuria, lymphoid hyperplasia, dermatitis, and hypergammaglobulinemia, with a reduction in TGF-beta1 and beta 2 expression in the kidneys and renal chemokine mRNA expression. Spleen levels of IL-4 and IL-10 were also reduced. Uncontrolled studies in patients with treatment-refractory lupus nephritis showed a significant reduction in proteinuria with ACE-inhibitors and Angiotensin receptor blockers treatment. The ‘masking’ effect of ACE-inhibitors should be taken into consideration, as an exacerbation of lupus nephritis may be missed when estimated by the magnitude of proteinuria, which is decreased by these treatments. No single ACE genotype was consistently associated with subsets of SLE patients. In retrospective analyses, ACE-inhibitor use predicted a favourable outcome in 94 cases of pauci-immune vasculitis. The attenuating effect of angiotensin II inhibitors on the progression of chronic renal disease is well recognized. The data on the role of this intervention in lupus is limited.

Understanding mechanisms of hypertension in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder that predominately affects women of reproductive age. Hypertension is an important cardiovascular risk factor that is prevalent in this patient population. Despite the high incidence of hypertension in women with SLE, the pathophysiological mechanisms underlying the development of hypertension remain poorly understood. This review will focus on disease-related factors, including inflammation, autoantibodies, and sex hormones that may contribute to hypertension in patients with SLE. In addition, we will highlight studies performed by our laboratory using the female NZBWF1 (F1 hybrid of New Zealand Black and New Zealand White strains) mouse model, a spontaneous model of SLE that mimics human disease and develops hypertension and renal injury. Specifically, using female NZBWF1 mice, we have demonstrated that multiple factors contribute to the pathogenesis of hypertension, including the inflammatory cytokine, tumor necrosis factor (TNF)-α, oxidative stress, as well as B-cell hyperactivity and autoantibody production.

Association between genetic polymorphisms of ACE & eNOS and diabetic nephropathy

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease, with multiple genetic and environmental factors involving in its etiology. ACE and eNOS gene were considered to have important roles in the development and progression of DN. In this study, a case-control study was carried out to investigate the effects of 7 SNPs in ACE gene and 2 SNPs in eNOS gene in the development of DN in Northern China.7 SNPs including A240T, A2350G, A5466C, A2215G, T3892C, C1237T and C3409T of ACE gene and 2 SNPs (G894T and T786C) of eNOS gene were genotyped by polymerase chain reaction restriction fragment length polymorphism method. 431 type 2 diabetic patients with nephropathy (cases) were compared to 420 type 2 diabetic patients without nephropathy (controls) in the study. Data were analyzed by SPSS 17.0 and HaploView software. The frequency distribution of A2350G, 4 haplotyps in ACE gene and G894T in eNOS gene were demonstrated to be different between case and control groups significantly. Whereas other SNPs and haplotypes had no differences in two cohorts. The results revealed that variations of ACE and eNOS gene had association with DN, which indicated ACE and eNOS gene may play an important role in pathogenesis of DN in Northern Chinese Han population.

Insertion/deletion polymorphism of the ACE gene increased risk of Behcet disease: evidence from a meta-analysis

BACKGROUND AND OBJECTIVES

Endothelial dysfunction has a role in the development of the Behcet disease (BD). Local renin-angiotensin system (RAS) plays a crucial role in the endothelial control, and angiotensin-converting enzyme (ACE) is the monitoring component of the RAS. We investigated the relationship between the ACE Ins/Del (I/D) variants and the risk of BD.

DESIGN AND SETTINGS

A meta-analysis was conducted from all published studies on the associations be.tween the ACE I/D polymorphism and BD.

METHODS

We systemically searched all published studies from PubMed and EMBASE, and data were quantitatively synthesized. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for allele, homozygous, heterozygous, and combined genetic models.

RESULTS

Out of 5 eligible studies, 676 healthy controls and 534 BD cases were included in the present meta.analysis. D allele carrier was significantly associated with increased BD risk (D vs I: P=.002; OR=1.321, 95% CI=1.111-1.570). Homozygous mutant DD genotype also revealed 1.5-fold increased risk (DD vs II; P=.004; OR=1.573, 95% CI=1.156-2.141). In addition, the dominant genetic model demonstrated an increased risk of developing BD (DD vs II+ID: P=.001; OR=1.610, 95% CI=1.242-2.087).

CONCLUSION

The current study suggests that ACE gene polymorphism (Ins/Del) contributes an increased susceptibility to BD. However, larger studies with stratified case control population and biological characterization are needed to validate this finding.

Association between the LCE3C_LCE3B deletion polymorphism and susceptibility to psoriasis: a meta-analysis of published studies

OBJECTIVE

To determine whether a deletion comprising the LCE3C and LCE3B genes (LCE3C_LCE3B-del) confers susceptibility to psoriasis.

METHODS

A meta-analysis was conducted to assess the association between the LCE3C_LCE3B-del polymorphism and psoriasis.

RESULTS

A total of 12,196 patients with psoriasis and 13,092 controls from 19 comparative studies were included in this meta-analysis. The meta-analysis showed a significant association between psoriasis and the LCE3C_LCE3B-del allele (odds ratio [OR], 1.220; 95% confidence interval [CI], 1.152-1.292; p<1.0×10(-9)). Stratification by ethnicity indicated an association between the LCE3C_LCE3B-del allele and psoriasis in Europeans and Asians (OR, 1.213; 95% CI, 1.130-1.302; p=8.0×10(-9) and OR, 1.260; 95% CI, 1.135-1.398; p=1.4×10(-6), respectively). Analysis using a recessive model, dominant model, and homozygote contrast showed the same pattern for the LCE3C_LCE3B-del allele. The analysis performed in a single Tunisian study showed no association between the LCE3C_LCE3B-del allele and psoriasis. Meta-analysis of the LCE3C_LCE3B-del allele showed no association between psoriatic arthritis and the LCE3C_LCE3B-del polymorphism (OR, 1.087; 95% CI, 0.870-1.359; p=0.464).

CONCLUSION

Our meta-analysis demonstrates a significant association between psoriasis and the LCE3C_LCE3B-del polymorphism in Europeans and Asians, but no association with psoriatic arthritis.

Relationship between angiotensin-converting enzyme insertion/deletion gene polymorphism and systemic lupus erythematosus/lupus nephritis: a systematic review and metaanalysis

OBJECTIVE

Results from studies of the association between angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism and systemic lupus erythematosus (SLE)/lupus nephritis (LN) are controversial. We performed this metaanalysis to evaluate the relationship between ACE I/D gene polymorphism and SLE/LN and to explore whether the ACE D allele or DD genotype could become a predictive marker for risk of SLE/LN.

METHODS

Association studies were identified from the databases of PubMed, Embase, Cochrane Library and CBM-disc (China Biological Medicine Database) as of May 1, 2011, and eligible investigations were synthesized using a metaanalysis method. Results were expressed with OR for dichotomous data, and 95% CI were calculated.

RESULTS

Sixteen investigations were identified for the analysis of association between ACE I/D gene polymorphism and SLE, consisting of 1959 patients with SLE and 2078 controls. In the overall populations, there was a marked association between D allele or DD genotype and SLE susceptibility (D: OR 1.29, 95% CI 1.04-1.58, p = 0.02; DD: OR 1.60, 95% CI 1.17-2.19, p = 0.003), and DD homozygous was associated with LN risk (OR 2.78, 95% CI 1.26-6.11, p = 0.01). In the subgroup analysis, DD genotype associated with SLE risk was observed in Asians; no other association was found in Asians, whites, Africans, and Brazilians.

CONCLUSION

D allele and DD homozygous are significant genetic molecular markers to predict SLE susceptibility, and DD genotype is a valuable marker to predict the LN risk. More investigations are required to clarify the association of the D allele or DD homozygous with SLE/LN susceptibility.

A meta-analysis of the association between cytokine gene polymorphisms and systemic sclerosis

We conducted a comprehensive meta-analysis to quantitatively evaluate the association of cytokine gene polymorphisms with systemic sclerosis (SSc) susceptibility. Electronic databases were used to identify published studies before July 2011. In total, 23 case-control studies including 3524 SSc cases and 6086 healthy controls were included in the meta-analysis. We examined the relationship between five gene polymorphisms [cytotoxic T lymphocyte associated antigen 4 (CTLA-4) -1722T/C, CTLA-4 -318C/T, CTLA-4 +49A/G, angiotensin-converting enzyme I/D, STAT-4 rs7574865] and susceptibility to SSc. The combined odds ratio (OR) with 95% confidence interval (95% CI) was calculated to estimate the strength of the association in a fixed or random effect model. Heterogeneity and publication bias were also assessed. We found a significant association between SSc and STAT rs7574865 (TT vs. GG: OR 0.44, 95% CI 0.36-0.54; TT vs. TG + GG: OR 0.48, 95% CI 0.39-0.59; TT + TG vs. GG: OR 0.74, 95% CI 0.66-0.83; T vs. G: OR 0.72, 95% CI 0.66-0.79), but there were no other statistically significant associations with other gene polymorphisms. Our study suggested that SSc is associated with STAT gene rs7574865 polymorphism.

Angiotensin-converting enzyme (ACE) serum levels and gene polymorphism in Egyptian patients with systemic lupus erythematosus

Objectives: to investigate the association of angiotensin-converting enzyme (ACE) gene polymorphism and serum ACE level among Egyptian SLE patients and its relation to disease activity parameters. Subjects and methods: we enrolled 50 Egyptian female systemic lupus erythematosus (SLE) patients and 29 healthy controls. Measurement of serum ACE level was done using ELISA, and the ACE genotype was determined by polymerase chain reaction using genomic DNA from peripheral blood. Results: a significant difference was found in ACE genotypes between SLE patients and controls (χ2 = 7.84, p = 0.02). The frequency of ACE DD versus (DI and II) genotypes was significantly higher in SLE patients compared with controls (χ2 = 5.57, p = 0.018 and OR for risk of SLE was 3.1 with 95% confidence interval: 1.198.06). Mean serum ACE level was significantly higher in the SLE group compared with controls ( p = 0.006). Subjects with DD genotype had a significantly higher mean level than those with DI ( p = 0.015) and II genotypes ( p = 0.02). Lupus nephritis patients had a significantly higher frequency of DD versus DI and II genotypes compared with lupus patients without nephritis (Fisher's exact test, p = 0.025) and controls (χ 2 =8.74, p = 0.003). SLE patients with vasculopathy had a significantly higher frequency of DD versus DI/II genotypes compared with SLE patients without vasculopathy (Fisher's exact test, p = 0.04) and controls (χ2 = 9.84 and p = 0.002). Mean serum ACE level was significantly higher in the lupus nephritis and SLE patients with vasculopathy compared with controls ( p = 0.008, p = 0.001, respectively). Significant positive correlations were found between serum ACE level and serum creatinine and 24 h proteinuria ( p = 0.03, 0.009, respectively). SLE patients with DD genotype had a statistically significant higher mean SLEDAI score than those with (DI/II) genotypes ( p = 0.02). Significant positive correlation was found between serum ACE levels and SLEDAI scores ( p = 0.04). Conclusion: ACE genotype and subsequently serum ACE level could be associated with the disease activity of Egyptian SLE patients; in addition, ACE deletion polymorphism might be used as one of the predictive factors for the activity of SLE. Further studies on a larger number of patients should be done to determine the exact prevalence of ACE gene polymorphism among Egyptian SLE patients.

Genetic risk factors of systemic lupus erythematosus in the Malaysian population: a minireview

SLE is an autoimmune disease that is not uncommon in Malaysia. In contrast to Malays and Indians, the Chinese seem to be most affected. SLE is characterized by deficiency of body's immune response that leads to production of autoantibodies and failure of immune complex clearance. This minireview attempts to summarize the association of several candidate genes with risk for SLE in the Malaysian population and discuss the genetic heterogeneity that exists locally in Asians and in comparison with SLE in Caucasians. Several groups of researchers have been actively investigating genes that are associated with SLE susceptibility in the Malaysian population by screening possible reported candidate genes across the SLE patients and healthy controls. These candidate genes include MHC genes and genes encoding complement components, TNF, FcγR, T-cell receptors, and interleukins. However, most of the polymorphisms investigated in these genes did not show significant associations with susceptibility to SLE in the Malaysian scenario, except for those occurring in MHC genes and genes coding for TNF-α, IL-1β, IL-1RN, and IL-6.

Association of the genetic polymorphisms of the ACE gene and the eNOS gene with lupus nephropathy in northern Chinese population

BACKGROUND

It has been reported that some single nucleotide polymorphisms (SNPs) of the angiotensin converting enzyme (ACE) gene and the endothelial nitric oxide synthase (eNOS) gene are associated with the development of systemic lupus erythematosus (SLE) and the progression of nephropathy. The aim of this study was to evaluate the possible association between six SNPs (A-5466C, T-3892C, A-240T, C1237T, G2215A and A2350G) of the ACE gene and two SNPs (T-786C and G894T) of the eNOS gene with lupus nephropathy in a northern Chinese population.

METHODS

In this study, 225 patients with lupus nephropathy were compared to 232 healthy controls, matched by gender, age and ethnicity. Following the extraction of genomic DNA from the leukocytes in the peripheral blood, the genotypes of the eight selected SNPs were determined by the method of PCR-RFLP; the haplotypes were inferred using PHASE 2.1. The associations between the SNPs and the risk of lupus nephropathy were analyzed using Chi-square test and Logistic regression with SPSS13.0 software.

RESULTS

Statistically significant differences of the allele frequency distribution of three SNPs (A-5466C, A2350G and G894T) were observed between cases and controls (P<0.05). Among the 53 haplotypes identified, the frequencies of five haplotypes (CTTCGA, ACTTAA, ACATGG, ACACGG and ATTCGA) were significantly different between cases and controls (P<0.05).

CONCLUSIONS

Our study indicated an association between the risk of lupus nephropathy and the sequence variations of both the ACE gene and the eNOS gene, which may play an important role in the pathogenesis of lupus nephropathy in the northern Chinese population. Further studies are warranted to validate our findings.

Association of angiotensin converting enzyme gene insertion/deletion polymorphism with lung cancer in Turkey

Angiotensin-converting enzyme (ACE) plays an important role in the physiological control of blood pressure and inflammation. We investigated an insertion/deletion (I/D) polymorphism of the gene for ACE in relation to cardiovascular, cerebrovascular, neurodegenerative, and inflammatory diseases. The purpose of the present study was to investigate a possible association between lung cancer and insertion/deletion polymorphism of the ACE gene. A total of 125 patients with lung cancer and 165 control subjects were enrolled in the present study. ACE I/D genotypes were determined by polymerase chain reaction. Allelic frequencies and genotype distribution of the ACE I/D polymorphism in the patient group were significantly different from control subjects (ACE II genotype 29.6 vs. 17.6%, P = 0.011; ACE I allele 49.6 vs. 39.4%, P =0.009). Our data suggest that the ACE I/D polymorphism could be a risk factor for patients with lung cancer.

Glomerular type 1 angiotensin receptors augment kidney injury and inflammation in murine autoimmune nephritis

Studies in humans and animal models indicate a key contribution of angiotensin II to the pathogenesis of glomerular diseases. To examine the role of type 1 angiotensin (AT1) receptors in glomerular inflammation associated with autoimmune disease, we generated MRL-Faslpr/lpr (lpr) mice lacking the major murine type 1 angiotensin receptor (AT1A); lpr mice develop a generalized autoimmune disease with glomerulonephritis that resembles SLE. Surprisingly, AT1A deficiency was not protective against disease but instead substantially accelerated mortality, proteinuria, and kidney pathology. Increased disease severity was not a direct effect of immune cells, since transplantation of AT1A-deficient bone marrow did not affect survival. Moreover, autoimmune injury in extrarenal tissues, including skin, heart, and joints, was unaffected by AT1A deficiency. In murine systems, there is a second type 1 angiotensin receptor isoform, AT1B, and its expression is especially prominent in the renal glomerulus within podocytes. Further, expression of renin was enhanced in kidneys of AT1A-deficient lpr mice, and they showed evidence of exaggerated AT1B receptor activation, including substantially increased podocyte injury and expression of inflammatory mediators. Administration of losartan, which blocks all type 1 angiotensin receptors, reduced markers of kidney disease, including proteinuria, glomerular pathology, and cytokine mRNA expression. Since AT1A-deficient lpr mice had low blood pressure, these findings suggest that activation of type 1 angiotensin receptors in the glomerulus is sufficient to accelerate renal injury and inflammation in the absence of hypertension.

The pathophysiology of hypertension in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune inflammatory disorder that predominantly affects women during their reproductive years. Although SLE can affect any organ system, the kidneys are prominently involved in the form of immune complex glomerulonephritis. In addition, in women with SLE, risk for the development of cardiovascular disease is dramatically increased. Hypertension is a major risk factor for cardiovascular disease and is highly prevalent in women with SLE. Nevertheless, there has been little exploration of the pathophysiological mechanisms that promote SLE hypertension. This review discusses the role of several mechanisms, with an emphasis on the kidney, in SLE hypertension. These mechanisms include the renin-angiotensin system, endothelin, oxidative stress, sex steroids, metabolic changes, peroxisome proliferator-activated receptor-gamma, and, perhaps most importantly, chronic inflammation and cytokines. Growing evidence suggests a link between chronic inflammation and hypertension. Therefore, elucidation of mechanisms that promote SLE hypertension may be of significant value not only for patients with SLE, but also for a better understanding of the basis for essential hypertension.

Association of angiotensin-converting enzyme gene insertion/deletion polymorphism with allergic contact dermatitis

Angiotensin-converting enzyme (ACE) plays an important role in the physiological control of blood pressure and inflammation. Insertion/deletion (I/D) polymorphism of the gene for ACE was investigated in relation to cardiovascular, cerebrovascular, neurodegenerative and inflammatory diseases. The purpose of the present study was to investigate the possible association between allergic contact dermatitis and insertion/deletion polymorphism of the ACE gene. A total of 90 patients with allergic contact dermatitis and 160 control persons were enrolled in the present study. ACE I/D genotypes were determined by the polymerase chain reaction. Allelic frequencies and genotype distribution of the ACE I/D polymorphism in the patient group were significantly different from control group (ACE II genotype 30.0% versus 17.5%, P = 0.022; ACE I allele 51.7% versus 39.4%, P = 0.008). Our data suggest that the ACE polymorphism could be a risk factor for patients with allergic contact dermatitis.

Angiotensin-converting enzyme gene insertion/deletion polymorphism in Korean patients with systemic sclerosis

To determine whether angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism is associated with the development and clinical features of systemic sclerosis (SSc) in Korean, we studied seventy two Korean patients with SSc fulfilling the ACR preliminary classification criteria. The controls were 114 healthy, disease free Koreans. ACE I/D genotypes were determined by PCR method using oligonucleotides. Sixty eight patients (94.4%) were women and age at diagnosis was 43.5+/-12.6 yr old (mean+/-SD). Thirty nine patients (54.2%) had a diffuse type of SSc. There were no statistical differences in the frequencies of all ACE I/D genotypes and D allele between patients and controls, and neither between diffuse and limited types of SSc. ACE I/D gene polymorphism was not associated with the development of SSc in Korea. The investigation for the pathogenesis of SSc requires more studies about the role of other candidate genes such as endothelin, TGF-beta, nitric oxide, or angiotensin II receptor in addition to the ACE genes.

Genetics of systemic lupus erythematosus: how far have we come?

There are two primary mechanisms for studying the genetic forces at work in systemic lupus erythematosus (SLE). Several groups have collected large numbers of pedigrees in which multiple family members have SLE for use in linkage studies. These linkage studies serve to isolate areas of the genome in which susceptibility genes lie. Other groups have taken a more direct approach of investigating genes that might contribute to disease pathogenesis in sets of lupus subjects and matched controls. These association studies are accumulating in greater numbers as the technology to determine the genotype at a given locus becomes more accessible. This article discusses the results of both types of studies.

Renin-angiotensin system gene polymorphisms predict the progression to renal insufficiency among Asians with lupus nephritis

The renin-angiotensin system (RAS) is a strong candidate as a mediator for the development and progression of lupus nephritis (LN). We performed an ethnically stratified analysis of 642 systemic lupus erythematosus (SLE) patients to determine whether various functional RAS gene polymorphisms are associated with SLE renal outcomes. Patients were genotyped for two angiotensin-converting enzyme (ACE) gene polymorphisms: Alu insertion/deletion (I/D) and 23 949 (CT)(2/3), and for two angiotensinogen (Atg) gene polymorphisms: M235T and C-532T. Multivariate analyses demonstrated associations between the ACE I/D, ACE (CT)(2/3) and Atg C-532T functional polymorphisms and LN among Asians. In stratified analyses among LN cases according to high vs low glomerular filtration rate (GFR), associations remained significant for the ACE D (odds ratio (OR) 5.9, P=0.001) and (CT)(2) (OR 6.2, P=0.001) alleles among Asian subjects with low GFR. Lastly, we found allelic dose-dependent associations between the ACE I/D (P=0.003), ACE (CT)(2/3) (P=0.005) and Atg M235T (P=0.04) polymorphisms, and GFR analyzed as a continuous variable among Asians. These findings suggest a significant role for ACE and Atg gene sequence variation and severity of LN among Asians with SLE.

Angiotensin-converting enzyme I/D polymorphism in Behçet's disease

OBJECTIVE

To investigate a potential relationship between I/D polymorphism within intron 16 of the angiotensin-converting enzyme (ACE) gene located on human chromosome 17 and Behçet's disease.

MATERIALS AND METHODS

Genomic DNA was obtained from 35 Turkish patients diagnosed with Behçet's disease according to the International Study Group criteria and 150 healthy individuals. Polymerase chain reaction was used to detect the presence of I and D (insertion and deletion) alleles in intron 16 of the ACE gene in these DNA samples.

RESULTS

We found differences in ACE I/D polymorphism between Behçet's disease and healthy controls (chi2=4.61, d.f.=1, p=0.044). In Behçet's disease patients, the D allele frequency was 84.3% and I allele frequency 15.7%.

CONCLUSION

An association between Behçet's disease and ACE polymorphism may provide a useful basis for future molecular studies and therapeutic approaches in this complex disease.

Uncovering the genetics of systemic lupus erythematosus: implications for therapy

Although it is well known that genetic factors contribute significantly to the expression of systemic lupus erythematosus (SLE) it was only recently realized, through genome-wide searches, that the number of involved genes is rather large. The published information hints at two facts: first, the number of genomic loci identified in various diverse cohorts is large and not necessarily overlapping; and second, certain loci may be preferentially linked with specific clinical manifestations. The latter may ultimately lead to a better understanding of the nature of the clinical entity that we know as SLE, and identification of groups of patients prone to respond better to treatment or to develop significant adverse effects. Advances attained regarding the nature of the biochemical and molecular defects that underwrite the aberrant function of immune cells parallel the progress made on the genetic origin of the disease. The genetic links need to be connected with aberrant function of their products to validate their significance. It is expected that correction of molecular aberrations either medicinally or by gene therapy will provide the needed specific treatment for patients with SLE.

Angiotensin-converting enzyme gene polymorphism and vascular manifestations in Korean patients with SLE

Systemic lupus erythematosus (SLE) is an inflammatory multisystem disease of unknown etiology with immunologic aberrations. Many studies have shown that genetic and environmental factors are implicated in the development of SLE. Angiotensin-converting enzyme (ACE) affects various immune phenomena through the renin-angiotensin and kallikrein-kininogen systems by creating angiotensin II and inactivating bradykinin. We investigated the correlation between insertion/ deletion polymorphism of the ACE gene and the clinical manifestations of SLE, especially vascular involvement and lupus nephritis. Two-hundred and eleven Korean patients fulfilling the ACR criteria and 114 healthy subjects were enrolled. The ACE genotype was determined by polymerase chain reaction using genomic DNA from peripheral blood. The nephritis patients were classified by the WHO classification. In addition, the activity and chronicity index were used to assess the severity of renal involvement. We evaluated vascular involvement by the presence or absence of hypertension, Raynaud's phenomenon, livedo reticularis, antineutrophil cytoplasmic antibody and the SLICC/ACR Damage Index. The gene frequency of ACE gene polymorphism was as follows: II 39 vs 34%, ID 41 vs 50%, DD 20 vs 16% in SLE patients and controls, respectively. There was no difference in genotype frequency between both groups. There were no significant differences between the distribution of ACE gene genotypes and lupus nephritis and its related parameters, including WHO classification, activity index, chronicity index, renal dysfunction and amount of 24 h urinary protein. The ACE genotypes and alleles did not affect the presence of vascular manifestations evaluated, but the frequency of DD genotype was significantly low in SLE patients with Raynaud's phenomenon compared to those without Raynaud's phenomenon (P = 0.002 for ACE ID vs DD and II, OR 2.7, 95% CI 1.43-5.09; P=0.023 for ACE DD vs ID and II, OR 0.33, 95% CI 0.12-0.89). Also skewing from DD to II genotype was noted in patients with anti-Sm antibody compared to those without anti-Sm antibody (P = 0.025 for ACE DD vs ID and II, OR 0.21, 95% CI 0.05-0.93). The onset age of serositis was older in patients with the ID genotype than the others (ID= 34.5+/-10.8, II + DD = 25.6+/-10.2, P= 0.002). Also the onset age of malar rash was older in patients with II genotype than the others (II=26.7+/-8.4, ID+DD=21.3+/-9.0; P=0.021). The patients with I allele showed a significantly higher frequency of serositis (P = 0.022). Taken together, the I/D polymorphisms of ACE gene did not affect susceptibility of SLE, lupus nephritis and the vascular manifestations, including Raynaud's phenomenon, in Korean SLE patients, although the DD genotype was negatively associated with Raynaud's phenomenon among SLE patients. However, it would be valuable to evaluate the role of other genes potentially related to vascular events, such as endothelin, nitric oxide or angiotensin II receptor as well as ACE gene.

Association of angiotensin-converting enzyme polymorphisms with systemic lupus erythematosus and nephritis: analysis of 644 SLE families

Angiotensin II is a strong candidate for the perpetuation of autoimmunity, nephritis and visceral damage in systemic lupus erythematosus (SLE). Our goal was to determine whether angiotensin-converting enzyme (ACE) gene polymorphisms are associated with SLE and/or lupus nephritis (LN). We genotyped 644 SLE patients and 1130 family members for three ACE gene polymorphisms: Alu insertion/deletion (I/D), 23949 (CT)(2/3) and 10698 (G)(3/4). All patients met the American College of Rheumatology (ACR) criteria for SLE, and all LN patients met ACR renal criteria and/or had biopsy evidence of LN. We used the transmission/disequilibrium test (TDT) to examine associations between each polymorphism and SLE, including Caucasian, non-Caucasian, and LN subgroups. We also examined transmission of haplotypes defined by these polymorphisms. The ACE I/D polymorphism was associated with SLE among non-Caucasians (61% transmission, P = 0.026) and the 23949 (CT)(2/3) polymorphism was associated with LN among non-Caucasians (69% transmission, P = 0.014). Several haplotypes defined by these 2 markers demonstrated strikingly increased transmission among non-Caucasians (81% - 66% transmission, P = 0.0046 to 0.010). Due to the choice of study design and analytic method these results are unlikely to be due to population admixture. Our findings suggest that DNA sequence variation in the ACE gene influences the risk of developing SLE and LN.

An update on genetic studies of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex, multifactorial autoimmune disease. Genetic factors are thought to contribute to its pathogenesis. There have been numerous recent advances in the study of murine and human lupus genetics. In well-defined experimental transgenic or gene-knockout mouse models, the development of lupus-like disease has implicated specific genes and pathways in the disease pathogenesis. Linkage analyses have mapped multiple susceptibility loci and disease suppressive loci using inbred strains of mice that spontaneously develop lupus-like disease. Elegant genetic dissection and function studies have led to the recent identification of two murine candidate susceptibility genes, Ifi202 (encoding an interferon-inducible protein) and Cr2 (encoding complement receptors 1 and 2). In human lupus, case- control studies have established associations of SLE with certain major histocompatibility class II alleles, complement deficiencies, and polymorphisms of Fc gamma receptor genes, a complement-related gene, and cytokine genes. During the past several years, linkage analyses using SLE multiplex families have provided many chromosomal regions for further exploration of susceptibility genes. Six regions exhibiting significant linkage to SLE are promising. Studies are underway to fine map these linked regions and to identify the genes in the susceptibility regions. An understanding of the genes involved in the development of lupus should provide targets for more focused therapy in lupus.