Experimental evidence suggesting that heat shock protein 70 (Hsp70) gene or associated genes are responsible for the pathophysiology of hypertension is accumulating. In this study, we focused on five polymorphisms in three genes (HSPA1A, HSPA1B, and HSPA1L) of Hsp70 family to explore the genetic contribution, alone and in combination, of these polymorphisms to essential hypertension risk in a Uygur population. Genotyping was performed using PCR-RFLP and direct sequencing techniques. Data were analyzed using haplotype and multifactor dimensionality reduction (MDR) methods. Genotype distributions of all the polymorphisms satisfied the Hardy–Weinberg proportions in cases and controls. Statistical significance was only observed in the genotype (P = 0.0028) and (P = 0.0146) allele distributions of −110A/C polymorphism, with the −110C allele conferring a 1.45- and 2.83-fold of relative risk, assuming the additive and recessive models, respectively, and in 1267A/G genotype distribution (P = 0.0106) with the 1267G allele conferring a 44% reduced risk. The interaction information analysis indicated that polymorphisms −110A/C and 1267A/G had a strong synergistic effect, while polymorphisms 2074G/C and 2437T/C had a moderate synergistic effect. Haplotype analyses further strengthened the interaction information. Using the haplotype H1 as a reference, haplotype H4 had a 40% reduced risk, while haplotypes H5 and H8 had a significantly 5.00- and 3.75-fold increased risk for essential hypertension, respectively. Taken together, our results supported strong genetic interaction of the studied polymorphisms with the risk of having essential hypertension in Uygur ethnicity. Functional studies are warranted to confirm or refute these findings. This is the first study to evaluate the genetic interaction information of the Hsp70 in Uygur ethnicity, which represents one of the major nationalities in China with high homogeneity and unique lifestyles. Moreover, we employed the haplotype and MDR methods to explore the potential interaction of Hsp70 genetic polymorphisms in the pathogenesis of essential hypertension in Uygur.
Heat shock protein 70; Uygur; Haplotype; Interaction; Single-locus; MDR
Three heat shock protein 70 (HSP70) genes, HSPA1L, HSPA1A, and HSPA1B, are located within the human leukocyte antigen (HLA) class III region. HSPs act as stress signals and regulate natural killer cell response to cancer. HSP70 gene polymorphisms show disease associations partly due to their linkage disequilibrium with HLA alleles. To systematically evaluate their associations with childhood acute lymphoblastic leukemia (ALL), we examined the three functional single nucleotide polymorphisms (SNPs) rs2227956 (T493M) in HSPA1L, rs1043618 in HSPA1A 5′UTR, and rs1061581 (Q351Q) in HSPA1B by TaqMan assays or polymerase chain reaction–restriction fragment length polymorphism in 114 ALL cases and 414 controls from Wales (UK), in 100 Mexican Mestizo ALL cases and 253 controls belonging to the same ethnic group, and in a panel of 82 HLA-typed reference cell line samples. Homozygosity for HSPA1B rs1061581 minor allele G was associated with protection (odds ratio (OR) = 0.37, 95% confidence interval (CI) = 0.16–0.78; P = 0.007) with gene-dosage effect (additive model) reaching significance (P = 0.0001) in the Welsh case–control group. This association was replicated in the second case–control group from Mexico (OR (recessive model) = 0.49, 95% CI = 0.24–0.96; P = 0.03), and the pooled analysis yielded a strong association (Mantel–Haenszel OR = 0.43, 95% CI = 0.27–0.69, P = 0.0004). The association was stronger in males in each group and in the pooled analysis. A three-SNP haplotype including the major allele A of rs1061581 showed a highly significant increase in Welsh cases compared with respective controls (6.7% vs 1.8%; P = 0.0003) due to the difference between male cases and controls. The protective allele of rs1061581 occurred more frequently on the HLA-DRB3 haplotypes (especially DRB1*03) in the cell line panel, but the HSPA1B association was independent from the HLA-DRB4 association previously detected in the same case–control group from Wales (adjusted P = 0.001). Given the cancer promoting roles played by HSPs intracellularly as well as roles in immune surveillance when expressed on the cell surface and the known correlations between expression levels and the HSP polymorphisms, these results are likely to indicate a primary association and warrant detailed assessment in childhood ALL development.
Genetic predisposition to disease; Heat shock protein gene polymorphism; HLA complex; Sex effect; Association study; Childhood leukemia susceptibility
OBJECTIVES--To determine which heat shock proteins (hsps) are overexpressed in systemic lupus erythematosus (SLE), and to examine the relevance of these findings to clinical disease activity. METHODS--Hsp levels in peripheral blood mononuclear cells (PBMC) of patients with SLE and normal controls were measured. Levels were analysed with respect to detailed clinical activity scores. Other hsps were also quantified in 30-50% of these samples. RESULTS--There was significant increase of the 90 kilodalton heat shock protein (hsp90) in patients with SLE and active neuropsychiatric (p < 0.005) and cardiorespiratory (p < 0.01) disease. There was also significant increase of the inducible 72 kilodalton member (hsp72), but not the constitutive 73 kilodalton member (hsp73) of the hsp70 family, and no increase of the 60 kilodalton hsp (hsp60) was seen in patients compared with controls. There was no association of hsp72 with disease activity, and no correlation between hsp90 and hsp72 levels was seen in individual patients. CONCLUSION--There may a specific role for hsp90 in distinct, clinically active subsets of patients with SLE.
There is ample evidence that Hsp70 takes part in the progress of coronary heart disease (CHD). This implies that genetic variants of Hsp70 genes such as HSPA8 (HSC70) gene might contribute to the development of CHD. The present study aimed to investigate whether certain genetic variants of HSPA8 gene are associated with CHD in Han Chinese people.
A total of 2006 subjects (1003 CHD cases and 1003 age- and sex- matched healthy controls) were recruited. Genetic variants in the HSPA8 gene were identified by sequencing of the gene in 60 unrelated Chinese. Four tag single nucleotide polymorphisms (tagSNPs) (rs2236659, rs2276077, rs10892958, and rs1461496) were selected and genotyped. The function of the significant SNP was evaluated using luciferase reporter assays in two cell lines. By sequencing the promoter and all exons and introns of the HSPA8 gene, 23 genetic variants were identified. One promoter SNP rs2236659 was associated with susceptibility to CHD. Carriers of the “C” allele of rs2236659 had decreased CHD risk with odds ratio (OR) of 0.78 (95% CI: 0.62, 0.98; P = 0.033) after adjustment for conventional risk factors. Haplotype analyses indicated that haplotype GCGC contributed to a lower CHD risk (OR = 0.78, 95% CI: 0.65, 0.93; P = 0.006) compared with the common haplotype AGGT. In a transfection assay, the C allele of rs2236659 showed a 37–40% increase in luciferase expression of the reporter gene luciferase in endothelial and non-endothelial cells compared with the T allele.
These findings suggest that genetic variants in HSPA8 gene (especially promoter SNP rs2236659) contribute to the CHD susceptibility by affecting its expression level.
In the present study we determined the expression pattern of HSPA1 and HSPA2 proteins in various normal human tissues by tissue-microarray based immunohistochemical analysis. Both proteins belong to the HSPA (HSP70) family of heat shock proteins. The HSPA2 is encoded by the gene originally defined as testis-specific, while HSPA1 is encoded by the stress-inducible genes (HSPA1A and HSPA1B). Our study revealed that both proteins are expressed only in some tissues from the 24 ones examined. HSPA2 was detected in adrenal gland, bronchus, cerebellum, cerebrum, colon, esophagus, kidney, skin, small intestine, stomach and testis, but not in adipose tissue, bladder, breast, cardiac muscle, diaphragm, liver, lung, lymph node, pancreas, prostate, skeletal muscle, spleen, thyroid. Expression of HSPA1 was detected in adrenal gland, bladder, breast, bronchus, cardiac muscle, esophagus, kidney, prostate, skin, but not in other tissues examined. Moreover, HSPA2 and HSPA1 proteins were found to be expressed in a cell-type-specific manner. The most pronounced cell-type expression pattern was found for HSPA2 protein. In the case of stratified squamous epithelia of the skin and esophagus, as well as in ciliated pseudostratified columnar epithelium lining respiratory tract, the HSPA2 positive cells were located in the basal layer. In the colon, small intestine and bronchus epithelia HSPA2 was detected in goblet cells. In adrenal gland cortex HSPA2 expression was limited to cells of zona reticularis. The presented results clearly show that certain human tissues constitutively express varying levels of HSPA1 and HSPA2 proteins in a highly differentiated way. Thus, our study can help designing experimental models suitable for cell- and tissue-type-specific functional differences between HSPA2 and HSPA1 proteins in human tissues.
Electronic supplementary material
The online version of this article (doi:10.1007/s00418-011-0791-5) contains supplementary material, which is available to authorized users.
HSP70 family proteins; HSPA2 protein; HSPA1 protein; Cell-type-specific expression; Tissue microarrays; Normal human tissues
Circulating heat shock protein 70 (Hsp70) is present in the circulation of healthy individuals and in patients with various disorders, including chronic heart failure (CHF). However, the source and routes of release of Hsp70 is only partially characterised in clinical samples.
The purpose of this study was to study the clinical and biological correlates of Hsp70 in a CHF population and, for the first time, to investigate the association of HspA1B (also known as Hsp70-2) +1267 alleles with serum Hsp70 levels.
A total of 167 patients (123 men, 44 women) with <45% left ventricular ejection fraction (LVEF) were enrolled; serum Hsp70 level was determined by enzyme-linked immunosorbent assay and HspA1B +1267 polymorphism by polymerase chain reaction–restriction fragment length polymorphism.
Increased Hsp70 levels were present in patients with severe CHF (NYHA III–IV) as compared to the group of NYHA I–II (p = 0.003). Hsp70 levels correlated with LVEF, NT-proBNP, serum bilirubin, aspartate aminotransferase, alanine aminotransferase, γGT (p < 0.05) concentrations in patients with severe CHF, although no correlation was observed between Hsp70 and CRP, TNF-α, or IL-6. HspA1B allele G was associated with higher Hsp70 levels (p = 0.001) in patients in NYHA IV class as compared to carriers of allele A.
Serum Hsp70 levels were associated with disease severity in heart failure patients. An interaction with the presence of HspA1B +1267 allele G was observed for Hsp70 concentrations. Hsp70 correlates with markers of heart function and hepatic injury, but not with signs of inflammation.
Heart failure; Inflammation; Liver; Stress proteins
In this manuscript, we describe the generation of a gene library for the expression of HSP110/HSPH, HSP70/HSPA and HSP40/DNAJ members. First, the heat shock protein (HSP) genes were collected from the gene databases and the gene families were analyzed for expression patterns, heat inducibility, subcellular localization, and protein homology using several bioinformatics approaches. These results can be used as a working draft model until data are confirmed by experimental approaches. In addition, we describe the generation of a HSPA/DNAJ overexpression library and tested the effect of different fusion tags on HSPA and DNAJ members using different techniques for measuring chaperone activity. These results show that we have cloned a high-quality heat shock protein expression library containing most members from the HSPH, HSPA, DNAJA and DNAJB families which will be useful for the chaperone community to unravel the function of the highly diverse family of human molecular chaperones.
HspH; HspA; DnaJ; Hsp110; Hsp70; Hsp40; Human chaperones; Bio-informatics
Heat shock proteins (Hsps) constitute an important component in the heat shock response of all living systems. Among the various plant Hsps (i.e. Hsp100, Hsp90, Hsp70 and Hsp20), Hsp20 or small Hsps (sHsps) are expressed in maximal amounts under high temperature stress. The characteristic feature of the sHsps is the presence of α-crystallin domain (ACD) at the C-terminus. sHsps cooperate with Hsp100/Hsp70 and co-chaperones in ATP-dependent manner in preventing aggregation of cellular proteins and in their subsequent refolding. Database search was performed to investigate the sHsp gene family across rice genome sequence followed by comprehensive expression analysis of these genes.
We identified 40 α-crystallin domain containing genes in rice. Phylogenetic analysis showed that 23 out of these 40 genes constitute sHsps. The additional 17 genes containing ACD clustered with Acd proteins of Arabidopsis. Detailed scrutiny of 23 sHsp sequences enabled us to categorize these proteins in a revised scheme of classification constituting of 16 cytoplasmic/nuclear, 2 ER, 3 mitochondrial, 1 plastid and 1 peroxisomal genes. In the new classification proposed herein nucleo-cytoplasmic class of sHsps with 9 subfamilies is more complex in rice than in Arabidopsis. Strikingly, 17 of 23 rice sHsp genes were noted to be intronless. Expression analysis based on microarray and RT-PCR showed that 19 sHsp genes were upregulated by high temperature stress. Besides heat stress, expression of sHsp genes was up or downregulated by other abiotic and biotic stresses. In addition to stress regulation, various sHsp genes were differentially upregulated at different developmental stages of the rice plant. Majority of sHsp genes were expressed in seed.
We identified twenty three sHsp genes and seventeen Acd genes in rice. Three nucleocytoplasmic sHsp genes were found only in monocots. Analysis of expression profiling of sHsp genes revealed that these genes are differentially expressed under stress and at different stages in the life cycle of rice plant.
We evaluated the roles of five single-nucleotide polymorphisms (SNPs) within PDCD1, and haplotypes defined by these SNPs, for the development of systemic lupus erythematosus (SLE) and specific sub-phenotypes (nephritis, antiphospholipid antibody positive, arthritis and double-stranded DNA positive) within a multiethnic US cohort of 1036 patients. Family based analyses were performed using 844 simplex families from four ethnic groups (Caucasian, Asian, Hispanic and African American). Subjects were genotyped for five ‘tag’ SNPs (selected from 15) to provide complete genetic information in all main ethnic groups. We employed transmission disequilibrium testing to assess risk for SLE by allele or haplotype, and multiple logistic regression analysis of SLE cases to examine associations with specific sub-phenotypes. In family based analyses, a haplotype containing the PD1.3A allele was significantly associated with SLE susceptibility among Caucasian families (P = 0.01). Among Hispanic families, two novel SNPs were associated with SLE risk (P = 0.005 and 0.01). In multivariate logistic regression analyses, five haplotypes were associated with specific sub-phenotypes among the different ethnic groups. These results suggest that PDCD1 genetic variation influences the risk and expression of SLE and that these associations vary according to ethnic background.
systemic lupus erythematosus; PDCD1; family-based methods; haplotypes
The spontaneous increase in the transcription of the heat shock protein (hsp 70) gene in peripheral blood mononuclear cells of patients with active systemic lupus erythematosus (SLE) is shown by nuclear run on transcription assay. The transcription of hsp 70 gene in the peripheral blood mononuclear cells of five patients with active SLE was more than 10 times greater than that in five normal healthy subjects or three patients with bronchial asthma as controls. This suggests that heat shock proteins may be produced during an active immune response in patients with active SLE and play a part in a change related to lupus of the essential intracellular functions of peripheral blood mononuclear cells.
An Hsp70 transgene system is used to identify cis-elements required for gene-specific association with nuclear speckles.
Many mammalian genes localize near nuclear speckles, nuclear bodies enriched in ribonucleic acid–processing factors. In this paper, we dissect cis-elements required for nuclear speckle association of the heat shock protein 70 (Hsp70) locus. We show that speckle association is a general property of Hsp70 bacterial artificial chromosome transgenes, independent of the chromosome integration site, and can be recapitulated using a 2.8-kilobase HSPA1A gene fragment. Association of Hsp70 transgenes and their transcripts with nuclear speckles is transcription dependent, independent of the transcribed sequence identity, but dependent on the Hsp70 promoter sequence. Transgene speckle association does not correlate with the amount of transcript accumulation, with large transgene arrays driven by different promoters showing no speckle association, but smaller Hsp70 transgene arrays with lower transcript accumulation showing high speckle association. Moreover, despite similar levels of transcript accumulation, Hsp70 transgene speckle association is observed after heat shock but not cadmium treatment. We suggest that certain promoters may direct specific chromatin and/or transcript ribonucleoprotein modifications, leading to nuclear speckle association.
In spite of the well-known clustering of multiple autoimmune disorders in families, analyses of specific shared genes and polymorphisms between systemic lupus erythematosus (SLE) and other autoimmune diseases (ADs) have been limited. Therefore, we comprehensively tested autoimmune variants for association with SLE, aiming to identify pleiotropic genetic associations between these diseases. We compiled a list of 446 non–Major Histocompatibility Complex (MHC) variants identified in genome-wide association studies (GWAS) of populations of European ancestry across 17 ADs. We then tested these variants in our combined Caucasian SLE cohorts of 1,500 cases and 5,706 controls. We tested a subset of these polymorphisms in an independent Caucasian replication cohort of 2,085 SLE cases and 2,854 controls, allowing the computation of a meta-analysis between all cohorts. We have uncovered novel shared SLE loci that passed multiple comparisons adjustment, including the VTCN1 (rs12046117, P = 2.02×10−06) region. We observed that the loci shared among the most ADs include IL23R, OLIG3/TNFAIP3, and IL2RA. Given the lack of a universal autoimmune risk locus outside of the MHC and variable specificities for different diseases, our data suggests partial pleiotropy among ADs. Hierarchical clustering of ADs suggested that the most genetically related ADs appear to be type 1 diabetes with rheumatoid arthritis and Crohn's disease with ulcerative colitis. These findings support a relatively distinct genetic susceptibility for SLE. For many of the shared GWAS autoimmune loci, we found no evidence for association with SLE, including IL23R. Also, several established SLE loci are apparently not associated with other ADs, including the ITGAM-ITGAX and TNFSF4 regions. This study represents the most comprehensive evaluation of shared autoimmune loci to date, supports a relatively distinct non–MHC genetic susceptibility for SLE, provides further evidence for previously and newly identified shared genes in SLE, and highlights the value of studies of potentially pleiotropic genes in autoimmune diseases.
It is well known that multiple autoimmune disorders cluster in families. However, all of the genetic variants that explain this clustering have not been discovered, and the specific genetic variants shared between systemic lupus erythematosus (SLE) and other autoimmune diseases (ADs) are not known. In order to better understand the genetic factors that explain this predisposition to autoimmunity, we performed a comprehensive evaluation of shared autoimmune genetic variants. First we considered results from 17 ADs and compiled a list with 446 significant genetic variants from these studies. We identified some genetic variants extensively shared between ADs, as well as the ADs that share the most variants. The genetic overlap between SLE and other ADs was modest. Next we tested how important all the 446 genetic variants were in our collection with a minimum of 1,500 SLE patients. Among the most significant variants in SLE, the majority had already been identified in previous studies, but we also discovered variants in two important immune genes. In summary, our data identified diseases with common genetic risk factors and novel SLE effects, and this supports a relatively distinct genetic susceptibility for SLE. This study helps delineate the genetic architecture of ADs.
HSP70 plays crucial roles in endothelial cell apoptosis, which is involved in the early phase and progress of coronary heart disease (CHD). However, the association between polymorphisms of HSP70 genes and the risk of CHD still remains unclear. Our aim was to determine whether genetic variants in the HSPA1A gene are associated with the risk of CHD.
By resequencing and genotyping, the associations of 2 single nucleotide polymorphisms (SNPs) +190G/C (rs1043618) and −110A/C (rs1008438) in the HSPA1A gene with risk of CHD were determined in a 1,003 pairs case-control study. The SNP function was further analyzed using a luciferase reporter assay in two cell lines. The results indicated that +190CC genotype was associated with significantly higher risk of CHD when compared with +190GG genotype (OR = 1.56, 95% CI: 1.10–2.20, P = 0.012), while association between −110A/C polymorphism and CHD was not statistically significant (P>0.05). However, the −110C/+190C haplotype had a significantly higher risk of CHD when compared with the −110A/+190G haplotype (OR = 1.17, 95% CI: 1.01–1.34, P = 0.031). Luciferase reporter assays showed that the +190C allele resulted in 14%∼45% reduction in luciferase expression in endothelial and non-endothelial cells when compared with the +190G allele.
The identified genetic variants in the HSPA1A gene combinatorially contribute towards the susceptibility to CHD likely by affecting the level of synthesis of HSP70. This study may provide useful markers for identification of subjects at risk for CHD.
Anti–heat shock protein 60 autoantibodies (anti-Hsp60) are associated with cardiovascular disease and are known to affect endothelial cells in vitro, and we have recently shown that anti-Hsp60 promote thrombosis in a murine model of arterial injury. Based on those findings, we undertook the present study to investigate the hypothesis that the presence of anti-Hsp60, alone or in combination with other thrombogenic risk factors, is associated with an elevated risk of vascular events.
The study population was derived from 3 ongoing cohort studies: 2 independent systemic lupus erythematosus (SLE) registries and 1 cohort comprising SLE patients and non-SLE patients. Data from a total of 402 participants were captured; 199 of these participants had had confirmed vascular events (arterial vascular events in 102, venous vascular events in 76, and both arterial and venous vascular events in 21). Anti-Hsp60 were detected by enzyme-linked immunoassay, and association with vascular events was assessed by regression analysis.
Multiple regression analysis revealed that arterial vascular events were associated with male sex, age, and hypertension. Analyses of the vascular events according to their origin showed an association of anti-Hsp60 with arterial vascular events (odds ratio 2.26 [95% confidence interval 1.13–4.52]), but not with venous vascular events. Anti-Hsp60 increased the risk of arterial vascular events (odds ratio 5.54 [95% confidence interval 1.89–16.25]) in antiphospholipid antibody (aPL)–positive, but not aPL-negative, individuals.
We demonstrate that anti-Hsp60 are associated with an increased risk of arterial vascular events, but not venous vascular events, in aPL-positive individuals. These data suggest that anti-Hsp60 may serve as a useful biomarker to distinguish risk of arterial and venous vascular events in patients with aPL.
PMID: 21506099 CAMSID: cams2354
Heat shock proteins (HSP) are a family of ubiquitous and phylogenically highly conserved proteins which play an essential role as molecular chaperones in protein folding and transport. Heat Shock Protein 90 (Hsp90) is not mandatory for the biogenesis of most proteins, rather it participate in structural maturation and conformational regulation of a number of signaling molecules and transcription factors. Hsp90 has been shown to play an important role in antigen presentation, activation of lymphocytes, macrophages, maturation of dendritic cells, and in the enhanceosome mediated induction of inflammation. Systemic lupus erythematosus (SLE) is a chronic autoimmune inflammatory disease with complex immunological and clinical manifestations. Dysregulated expression of Type I interferon α, activation of B cells and production of autoantibodies are hallmarks of SLE. The enhanced levels of Hsp90 were detected in the serum of SLE patients. The elevated level of Hsp90 in SLE has also been correlated with increased levels of IL-6 and presence of autoantibodies to Hsp90. This suggests that Hsp90 may contribute to the inflammation and disease progression and that targeting of Hsp 90 expression may be a potential treatment of SLE. The pharmacologic inhibition of Hsp90 was successfully applied in mouse models of autoimmune encephalomyelitis and SLE—like autoimmune diseases. Thus targeting Hsp90 may be an effective treatment for SLE, especially if combined with other targeted therapeutic approaches.
Age-dependent changes in heat shock response (HSR) were studied in mononuclear cells (monocytes and lymphocytes) collected from young (mean age = 22.6 ± 1.7 years) and middle-aged (mean age = 56.3 ± 4.7 years) subjects after 1 hour of heat shock at 42°C. Genotype-specific HSR was measured by genotyping the subjects for 3 single nucleotide polymorphisms, HSPA1A(A-110C), HSPA1B(A1267G), and HSPA1L(T2437C), 1 each in the 3 HSP70 genes. A significant age-related decrease in the induction of Hsp70 occurred after heat shock in both monocytes and lymphocytes. The noninducible and inducible forms of Hsp70 decreased 1.3-fold (P < 0.001) and 1.4-fold (P < 0.001), respectively, in the monocytes with age. In the young subjects, a positive association was found between HSPA1L(T2437C) polymorphism and HSR. CC carriers had a significantly lower induction than TT carriers in both monocytes (P = 0.015) and lymphocytes (P = 0.044). This polymorphism, which is present in the coding region of HSPA1L gene, can affect the chaperoning function of Hsp70. These data consolidate our other observations that the CC genotype is unfavorable for human longevity and provide a functional explanation in terms of variations in HSR.
Systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) are related chronic autoimmune diseases of complex aetiology in which the interferon (IFN) pathway plays a key role. Recent studies have reported an association between IRF7 and SLE which confers a risk to autoantibody production. A study was undertaken to investigate whether the IRF7 genomic region is also involved in susceptibility to SSc and the main clinical features.
Two case-control sets of Caucasian origin from the USA and Spain, comprising a total of 2316 cases of SSc and 2347 healthy controls, were included in the study. Five single nucleotide polymorphisms (SNPs) in the PHRF1-IRF7-CDHR5 locus were genotyped using TaqMan allelic discrimination technology. A meta-analysis was performed to test the overall effect of these genetic variants on SSc.
Four out of five analysed SNPs were Significantly associated with the presence of anticentromere autoantibodies (ACA) in the patients with SSc in the combined analysis (rs1131665: pFDR=6.14 × 10−4, OR=0.78; rs4963128: pFDR=6.14 × 10−4, OR=0.79; rs702966: pFDR=3.83 × 10−3, OR=0.82; and rs2246614: pFDR=3.83 × 10−3, OR=0.83). Significant p values were also obtained when the disease was tested globally; however, the statistical significance was lost when the ACA-positive patients were excluded from the study, suggesting that these associations rely on ACA positivity. Conditional logistic regression and allelic combination analyses suggested that the functional IRF7 SNP rs1131665 is the most likely causal variant.
The results show that variation in the IRF7 genomic region is associated with the presence of ACA in patients with SSc, supporting other evidence that this locus represents a common risk factor for autoantibody production in autoimmune diseases.
High-altitude illness (HAI) is a potentially fatal condition involving genetic and environmental components. Accumulated experimental evidence suggests that heat shock proteins (Hsps), especially HSP70, can protect cells and organs against different types of damage. We investigated whether genetic variation in constitutive and inducible hsp70 genes could be associated with risk of HAI. The association between polymorphisms of the HSP70 family genes and risk of HAI was determined in 56 patients with HAI and in 100 matched controls by genotyping for the polymorphisms +190 G/C, +1267 A/G, 2437 G/C in the hsp70-1, hsp70-2, and hsp70-hom genes by using polymerase chain reaction–restriction fragment length polymorphism. The data showed that there was no statistically significant difference in the genotype and allele distributions of hsp70-1, in hsp70-2 allele and hsp70-2 A/A and A/B genotypes, and in allele distribution of hsp70-hom among patients with HAI and controls (χ2 test, P > 0.05). However, there was a significantly higher frequency of hsp70-2 B/B and hsp70-hom A/A and B/B genotypes and a significantly lower frequency of the hsp70-hom A/B genotype in the HAI patients compared with the controls (P < 0.05 for all). The risk associated with the hsp70-2 B/B and hsp70-hom A/A, A/B, and B/B genotypes were 4.017 (95% CI = 1.496–10.781; P = 0.004), 2.434 (95% CI = 1.184–5.003; P = 0.012), 0.299 (95% CI = 0.148–0.602, P = 0.001), and 5.880 (95% CI =1.145–30.196, P = 0.026), respectively. Our results suggest that individuals with hsp70-2 B/B and hsp70-hom A/B and B/B genotypes may be more susceptible to HAI, whereas those with hsp70-hom A/B genotype may be tolerant to HAI. Further studies in individuals of different age and sex are warranted to elucidate the underlying mechanisms of this association and the possible functions of different genotypes of hsp70-2 and hsp70-hom under hypoxic stress.
The TNF α-induced protein 3 (TNFAIP3) is an ubiquitin-modifying enzyme and an essential negative regulator of inflammation. Genome-wide association studies have implicated the TNFAIP3 locus in susceptibility to autoimmune disorders in European cohorts, including rheumatoid arthritis, coronary artery disease, psoriasis, celiac disease, type 1 diabetes, inflammatory bowel disease, and systemic lupus erythematosus (SLE). There are two nonsynonymous coding polymorphisms in the deubiquitinating (DUB) domain of TNFAIP3: F127C, which is in high-linkage disequilibrium with reported SLE-risk variants, and A125V, which has not been previously studied. We conducted a case–control study in African-American SLE patients using these coding variants, along with tagging polymorphisms in TNFAIP3, and identified a novel African-derived risk haplotype that is distinct from previously reported risk variants (odds ratio = 1.6, p = 0.006). In addition, a rare protective haplotype was defined by A125V (odds ratio = 0.31, p = 0.027). Although A125V was associated with protection from SLE, surprisingly the same allele was associated with increased risk of inflammatory bowel disease. We tested the functional activity of nonsynonymous coding polymorphisms within TNFAIP3, and found that the A125V coding-change variant alters the DUB activity of the protein. Finally, we used computer modeling to depict how the A125V amino acid change in TNFAIP3 may affect the three-dimensional structure of the DUB domain to a greater extent than F127C. This is the first report of an association between TNFAIP3 polymorphisms and autoimmunity in African-Americans.
Variations in genetic background are the leading cause of differential susceptibility to traumatic infection. Heat shock protein 90 (HSP90), a broadly distributed and conserved molecule, regulates inflammation under stressful and traumatic conditions. However, the relationships between HSP90 genetic polymorphisms, post-traumatic inflammatory responses and organ function remain unknown.
A total of 286 healthy volunteers and patients with severe trauma took part in a single nucleotide polymorphism (SNP)-based analysis of the HSP90beta gene and a clinical association analysis. HSP90beta and TNF-alpha levels were determined using quantitative PCR and western blot. The transcriptional activity of the HSP90beta promoter was assayed using the Dual-Luciferase Reporter Assay System.
The minor allele frequencies for the SNP located at −144 bp relative to the HSP90beta transcriptional start site were 28.47% and 28.52% in the normal and trauma populations, respectively; no significant differences were found between these two distributions. However, the results showed that a promoter containing the -144A allele had a higher transcriptional activity than did a promoter containing the wild-type -144C allele. Furthermore, the -144A promoter induced high expression of HSP90beta and low expression of the inflammatory factor TNF-alpha in a lipopolysaccharide-induced inflammatory model. A clinical association analysis showed that the multiple organ dysfunction scores for -144AA genotype carriers were significantly lower than those of -144CC carriers following trauma. No significant correlations were found between the presence of the two alleles and the incidence of sepsis.
These results indicate that differences in expression caused by the -144 polymorphism in the HSP90beta promoter are associated with cellular inflammatory responses and the severity of organ injury. These findings will aid in risk assessment and early prevention of complications for patients with severe trauma.
Variants of the osteopontin (OPN) gene have been associated with systemic lupus erythematosus (SLE) susceptibility and cytokine profiles in SLE patients. It is not known whether these alleles are associated with specific clinical phenotypes in SLE. We studied 252 well-characterized SLE patients from a multiethnic cohort, genotyping the rs11730582, rs28357094, rs6532040, and rs9138 SNPs in the OPN gene. Ancestry informative markers were used to control for genetic ancestry. The SLE-risk allele rs9138C in the 3′ UTR region was associated with photosensitivity in lupus patients across all ancestral backgrounds (meta-analysis OR = 3.2, 95% CI = 1.6–6.5, P = 1.0 × 10−3). Additionally, the promoter variant rs11730582C demonstrated suggestive evidence for association with two hematologic traits: thrombocytopenia (OR = 2.1, P = 0.023) and hemolytic anemia (OR = 2.6, P = 0.036). These clinical associations with SNPs in the promoter and 3′ UTR regions align with previously reported SLE-susceptibility SNPs in OPN and suggest potential roles for these variants in antibody-mediated cytopenias and skin inflammation in SLE.
Cytochrome P-450 2E1 (CYP2E1) is an important member of the CYP superfamily, which is involved in the metabolism and activation of many low molecular weight toxic compounds. We tried to investigate the possible association of CYP2E1 tag single nucleotide polymorphisms (SNPs) with susceptibility to systemic lupus erythematosus (SLE) in a Chinese Han population.
The coding and flanking regions of the CYP2E1 gene were scanned for polymorphisms and tag SNPs were selected. A two-stage case-control study was performed to genotype a total of 876 SLE patients and 680 geographically matched healthy controls (265 cases and 288 controls in stage I and 611 cases and 392 controls in stage II). SLE associations of alleles, genotypes and haplotypes were tested by age and sex adjusted logistic regression. The gene transcription quantitation was carried out for peripheral blood mononuclear cell (PBMC) samples from 120 healthy controls.
Tag SNP rs2480256 was found significantly associated with SLE in both stages of the study. The "A" allele was associated with slightly higher risk (odds ratio (OR) = 1.165, 95% confidence interval (CI) 1.073 to 1.265, P = 2.75E-4) and "A/A" genotype carriers were with even higher SLE risk (OR = 1.464 95% CI 1.259 to 1.702, P = 7.48E-7). When combined with another tag SNP rs8192772, we identified haplotype "rs8192772-rs2480256/TA" over presented in SLE patients (OR 1.407, 95% CI 1.182 to 1.675, P = 0.0001) and haplotype "TG" over presented in the controls (OR 0.771, 95% CI 0.667 to 0.890, P = 0.0004). The gene transcription quantitation analysis further proved the dominant effect of rs2480256 as the "A/A" genotype showed highest transcription.
Our results suggest the involvement of CYP2E1 as a susceptibility gene for SLE in the Chinese population.
Genetic factors influence susceptibility to systemic lupus erythematosus (SLE). A recent family-based analysis in Caucasian and Chinese populations provided evidence for association of single-nucleotide polymorphisms (SNPs) in the complement receptor 2 (CR2/CD21) gene with SLE. Here we confirmed this result in a case-control analysis of an independent European-derived population including 2084 patients with SLE and 2853 healthy controls. A haplotype formed by the minor alleles of three CR2 SNPs (rs1048971, rs17615, rs4308977) showed significant association with decreased risk of SLE (30.4% in cases vs. 32.6% in controls, P = 0.016, OR = 0.90 [0.82-0.98]). Two of these SNPs are in exon 10, directly 5′ of an alternatively spliced exon preferentially expressed in follicular dendritic cells (FDC), and the third is in the alternatively spliced exon. Effects of these SNPs as well as a fourth SNP in exon 11 (rs17616) on alternative splicing were evaluated. We found that the minor alleles of these SNPs decreased splicing efficiency of exon 11 both in vitro and ex vivo. These findings further implicate CR2 in the pathogenesis of SLE and suggest that CR2 variants alter the maintenance of tolerance and autoantibody production in the secondary lymphoid tissues where B cells and FDCs interact.
Alternative splicing; systemic lupus erythematosus; complement receptors; single-nucleotide polymorphisms; B cells; follicular dendritic cells
Patients with systemic lupus erythematosus (SLE) develop multiple autoantibodies to self-antigens. Analysis of autoantibody systems in this and related autoimmune disorders can provide information of etiologic and pathogenetic significance. We report here a previously unrecognized autoantibody to the 90,000-D heat-shock protein, hsp90, a molecule thought to have important functions in the cellular response to stress, virus-induced transformation, steroid hormone receptor action, and cellular activation. Autoantibodies to hsp90 were exclusively of the IgG class, and were detected in approximately 50% of unselected patients with SLE and 2/6 patients with idiopathic polymyositis. Anti-hsp90 antibodies were not detected in sera from 10 normal subjects, 10 patients with rheumatoid arthritis, or 7 patients with scleroderma. The identity of this major intracytoplasmic antigen was established by its specific removal from nonionic detergent cell lysates following immunoabsorption with monospecific rabbit anti-hsp90, and by demonstration of increased synthesis following a 10-min 45 degrees C heat shock. These data define the frequent occurrence of a novel autoantibody to a major heat-shock protein in patients with SLE.
Sequence variation in gene promoters is often associated with disease risk. In this study, we tested the hypothesis that common promoter variation in the APOH gene (encoding for β2-glycoprotein I) is associated with systemic lupus erythematosus (SLE) risk and SLE-related clinical phenotypes in a Caucasian cohort.
We used a case-control design and genotyped 345 SLE women and 454 healthy control women for 8 APOH promoter single nucleotide polymorphisms (SNPs) (−1284C>G, −1219G>A, −1190G>C, −759 A>G, − 700C>A, −643T>C, −38G>A, and −32C>A). Association analyses were performed on single SNPs and haplotypes. Haplotype analyses were performed using EH (Estimate Haplotype-frequencies) and Haploview programs. In vitro reporter gene assay was performed in COS-1 cells. Electrophoretic mobility shift assay (EMSA) was performed using HepG2 nuclear cells.
Overall haplotype distribution of the APOH promoter SNPs was significantly different between cases and controls (P = 0.009). The −643C allele was found to be protective against carotid plaque formation (adjusted OR = 0.37, P = 0.013) among SLE patients. The −643C allele was associated with a ~ 2-fold decrease in promoter activity as compared to wild-type −643T allele (mean ± standard deviation: 3.94 ± 0.05 vs. 6.99 ± 0.68, P = 0.016). EMSA showed that the −643T>C SNP harbors a binding site for a nuclear factor. The −1219G>A SNP showed a significant association with the risk of lupus nephritis (age-adjusted OR = 0.36, P = 0.016).
Our data indicate that APOH promoter variants may be involved in the etiology of SLE, especially the risk for autoimmune-mediated cardiovascular disease.
APOH; β2-glycoprotein I; promoter; SLE; lupus; polymorphism