Genetics of systemic lupus erythematosus

Macrophage subpopulations in pediatric patients with lupus nephritis and other inflammatory diseases affecting the kidney

BACKGROUND

Macrophages play an important role in the pathogenesis of lupus nephritis (LN), but less is known about macrophage subtypes in pediatric LN. Here we compared renal inflammation in LN with other inflammatory pediatric kidney diseases and assessed whether inflammation correlates with clinical parameters.

METHODS

Using immunofluorescence microscopy, we analyzed renal biopsies from 20 pediatric patients with lupus nephritis (ISN/RPS classes II-V) and pediatric controls with other inflammatory kidney diseases for infiltration with M1-like (CD68 + /CD206 - , CD68 + /CD163 -), M2a-like (CD206 + /CD68 +), and M2c-like macrophages (CD163 + /CD68 +) as well as CD3 + T-cells, CD20 + B-cells, and MPO + neutrophilic granulocytes. In addition, the correlation of macrophage infiltration with clinical parameters at the time of renal biopsy, e.g., eGFR and serum urea, was investigated. Macrophage subpopulations were compared with data from a former study of adult LN patients.

RESULTS

The frequency of different macrophage subtypes in biopsies of pediatric LN was dependent on ISN/RPS class and showed the most pronounced M1-like macrophage infiltration in patients with LN class IV, whereas M2c-like macrophages were most abundant in class III and IV. Interestingly, on average, only half as many macrophages were found in renal biopsies of pediatric LN compared to adult patients with LN. The distribution of frequencies of macrophage subpopulations, however, was different for CD68 + CD206 + (M2a-like) but comparable for CD68 + CD163 - (M1-like) CD68 + CD163 + (M2c-like) cells in pediatric and adult patients. Compared to other inflammatory kidney diseases in children, fewer macrophages and other inflammatory cells were found in kidney biopsies of LN. Depending on the disease, the frequency of individual immune cell types varied, but we were unable to confirm disease-specific inflammatory signatures in our study due to the small number of pediatric cases. Worsened renal function, measured as elevated serum urea and decreased eGFR, correlated particularly strongly with the number of CD68 + /CD163 - M1-like macrophages and CD20 + B cells in pediatric inflammatory kidney disease.

CONCLUSION

Although M1-like macrophages play a greater role in pediatric LN patients than in adult LN patients, M2-like macrophages appear to be key players and are more abundant in other pediatric inflammatory kidney diseases compared to LN.

Sjögren's syndrome

Sjögren's syndrome (SS) is characterised as keratoconjunctivitis sicca (dry eyes), xerostomia (dry mouth) commonly associated with salivary gland enlargement, and is referred to as Primary Sjögren's syndrome. It is known as Secondary Sjögren's syndrome when it occurs in patients, with connective tissue disease, such as rheumatoid arthritis, systemic lupus erythematosus, polyarthritis nodosa, polymyositis, and systemic sclerosis. SS has also been associated with chronic graft-versus-host disease after allogeneic bone marrow transplantation, human immunodeficiency syndrome (AIDS), hepatitis C infection (HCV), chronic biliary cirrhosis, neoplastic and myeloplastic syndromes, fibromyalgia, and chronic fatigue syndrome.

Recent advances in understanding the genetic basis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a polygenic chronic autoimmune disease leading to multiple organ damage. A large heritability of up to 66% is estimated in SLE, with roughly 180 reported susceptibility loci that have been identified mostly by genome-wide association studies (GWASs) and account for approximately 30% of genetic heritability. A vast majority of risk variants reside in non-coding regions, which makes it quite challenging to interpret their functional implications in the SLE-affected immune system, suggesting the importance of understanding cell type-specific epigenetic regulation around SLE GWAS variants. The latest genetic studies have been highly fruitful as several dozens of SLE loci were newly discovered in the last few years and many loci have come to be understood in systemic approaches integrating GWAS signals with other biological resources. In this review, we summarize SLE-associated genetic variants in both the major histocompatibility complex (MHC) and non-MHC loci, examining polygenetic risk scores for SLE and their associations with clinical features. Finally, variant-driven pathogenetic functions underlying genetic associations are described, coupled with discussion about challenges and future directions in genetic studies on SLE.

Resveratrol Role in Autoimmune Disease-A Mini-Review

Autoimmune diseases are still considered to be pressing concerns due the fact that they are leaders in death and disability causes worldwide. Resveratrol is a polyphenol derived from a variety of foods and beverages, including red grapes and red wine. Anti-inflammatory, antioxidant, and antiaging properties of resveratrol have been reported, and in some animal and human studies this compound reduced and ameliorated the progression of autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, psoriasis, inflammatory bowel disease, and type 1 diabetes mellitus. Thus, this review aims to summarize and critically analyze the role of resveratrol in the modulation of several organ-specific or systemic autoimmune diseases.

Systemic lupus erythematosus in southern Spain: a comparative clinical and genetic study between Caucasian and Gypsy patients

We evaluated the influence of the hereditary make-up on the development of systemic lupus erythematosus (SLE) in two ethnic groups [Gypsy and white Caucasian Mediterranean (WCM) populations], living in the same geographic area. We compared 81 WCM and 25 Gypsy patients with SLE. The control group consisted of 185 healthy unrelated individuals, 105 WC and 80 Gypsies. In the Gypsy population, the onset of SLE occurred at earlier ages than in the other ethnic group (25.9 versus 32.0 years, P = 0.02), and showed lower SLEDAI peak values (4.9 versus 7.0, P = 0.016). The frequency of joint, kidney, gastrointestinal and eye involvement was significantly lower in Gypsy patients. In contrast, SLE-associated antiphospholipid syndrome, thrombosis and livedo reticularis were more frequent in Gypsies than in the majority ethnic group (WCM). In WCM patients, DRB1*1303- DQB1*0301 haplotype was associated with SLE ( P = 0.001, Pc = 0.038). We found SLE to be associated with DR5 ( P = 0.006, Pc = 0.05) in the Gypsy population as well as a protective effect of DPB1*0401 when DR5 was not present ( P = 0.008, Pc = 0.032). In conclusion, we found some clinical differences between WCM and Gypsy patients with SLE. Furthermore, HLA associations between HLA-DRB1-DQB1 and SLE were different for Gypsy people.

Linking susceptibility genes and pathogenesis mechanisms using mouse models of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) represents a challenging autoimmune disease from a clinical perspective because of its varied forms of presentation. Although broad-spectrum steroids remain the standard treatment for SLE, they have many side effects and only provide temporary relief from the symptoms of the disease. Thus, gaining a deeper understanding of the genetic traits and biological pathways that confer susceptibility to SLE will help in the design of more targeted and effective therapeutics. Both human genome-wide association studies (GWAS) and investigations using a variety of mouse models of SLE have been valuable for the identification of the genes and pathways involved in pathogenesis. In this Review, we link human susceptibility genes for SLE with biological pathways characterized in mouse models of lupus, and discuss how the mechanistic insights gained could advance drug discovery for the disease.

Pharmacological regulators of autophagy and their link with modulators of lupus disease

Autophagy is a central regulator of cell survival. It displays both anti- and pro-death roles that are decisive in the maintenance of cell homeostasis. Initially described in several eukaryotic cellular models as being induced under nutrient stress favouring survival by energy supply, autophagy was found later to display other decisive physiological roles, especially in the immune system. Thus, it is involved in antigen presentation and lymphocyte differentiation as well as in the balance regulating survival/death and activation of lymphocytes. Autophagy therefore appears to be central in the regulation of inflammation. The observation that autophagy is deregulated in systemic lupus erythematosus is recent. This discovery revives the programme dealing with the design and development of pharmacological autophagy regulators in the therapeutic context of lupus, a debilitating autoimmune disease that affects several million people in the world. A large number of molecules that positively and negatively regulate autophagy have been described, most of them with therapeutic indications in cancer and infection. Only a few, however, are effectively potent activators or inhibitors endowed with experimentally demonstrated selective properties. In this review article, we highlight the most relevant ones and summarize what we know regarding their mechanism of action. We emphasize the link between pharmacological regulators of autophagy and inducers or inhibitors of lupus disease and discuss the fundamental and pharmacological/therapeutic interest of this functional interplay.

Insight into gene polymorphisms involved in toll-like receptor/interferon signalling pathways for systemic lupus erythematosus in South East Asia

Polymorphisms in genes involved in toll-like receptor/interferon signalling pathways have been reported previously to be associated with SLE in many populations. This study aimed to investigate the role of seven single nucleotide polymorphisms within TNFAIP3, STAT4, and IRF5, which are involved in upstream and downstream pathways of type I interferon production, in SLE in the South East Asian populations. Genotyping of 360 Malaysian SLE patients and 430 normal healthy individuals revealed that minor alleles of STAT4 rs7574865 and rs10168266 were associated with elevated risk of SLE in the Chinese and Malay patients, respectively (P = 0.028, odds ratio (OR) = 1.42; P = 0.035, OR = 1.80, respectively). Polymorphisms in TNFAIP3 and IRF5 did not show significant associations with SLE in any of the ethnicities. Combined analysis of the Malays, Chinese, and Indians for each SNP indicated that STAT4 rs10168266 was significantly associated with the Malaysian SLE as a whole (P = 0.014; OR = 1.435). The meta-analysis of STAT4 rs10168266, which combined the data of other studies and this study, further confirmed its importance as the risk factor for SLE by having pooled OR of 1.559 and P value of <0.001.

Fatigue in systemic lupus erythematosus

Systemic lupus erythematosus is a chronic inflammatory autoimmune disease often characterized by fatigue, with significant effects on physical functioning and wellbeing. The definition, prevalence and factors associated with fatigue, including physical activity, obesity, sleep, depression, anxiety, mood, cognitive dysfunction, vitamin D deficiency/insufficiency, pain, effects of medications and comorbidities, as well as potential therapeutic options of fatigue in the systemic lupus erythematosus population are reviewed. Due to variability in the reliability and validity of various fatigue measures used in clinical studies, clinical trial data have been challenging to interpret. Further investigation into the relationships between these risk factors and fatigue, and improved measures of fatigue, may lead to an improvement in the management of this chronic inflammatory disease.

Mapping susceptibility gene in systemic lupus erythematosus

Genome-wide association studies have identified many dozen genetic intervals that harbor single-nucleotide polymorphisms (SNPs) showing statistical association with systemic lupus erythematosus. Despite the wealth of data produced, there are limitations of these studies. The causal alleles at a given locus are not identified; only SNP is strong linkage disequilibrium with the putative causative alleles. In order to address identification of the causative SNPs for lupus susceptibility genes, we have initiated a candidate gene study for which more than 40 investigators have contributed patient and control samples. In addition, these investigators have designated SNPs to be placed on a custom array. In this way fine mapping of genetic association findings can occur in order to identify causal alleles. These efforts have thus far benefitted greatly from comparisons of different ethnicities. Work on about ten previously identified associations has been published using this resource. Genome-wide association studies cannot identify rare SNPs or mutations, which may impart greater relative risks than common variants. Much of the genetics of lupus may be from rare variants or mutations. In order to approach this aspect of lupus genetics, next-generation sequencing has begun in which all exons will be sequenced in controls and patients. This effort can also be used to identify causal alleles from association intervals not yet otherwise identified.

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.

HLA-A*11 and novel associations in Malays and Chinese with systemic lupus erythematosus

We investigated the association of the HLA genes in Malaysian patients with systemic lupus erythematosus (SLE) and their associations with the clinical manifestations in 160 SLE patients (99 Chinese and 61 Malays) and 107 healthy control individuals (58 Chinese and 49 Malays) were studied. Sequence specific primer amplification (PCR-SSP) phototyping techniques were used to analyse 25 HLA-A allele groups, 31 HLA-DR allele groups and 9 HLA-DQ allele groups. Appreciable increases in allele frequencies of HLA-A*11, DRB1*0701, DRB1*1601-1606, DRB5*01-02 and DQB1*05, and decrease in HLA-DRB1*1101-1121, 1411, DRB1*1201-3, DRB1*1301-22, DRB3*0101, 0201, 0202, 0203, 0301 and DQB1*0301, 1304 in SLE patients compared with healthy control individuals. However, after Bonferroni correction (p(c)<0.05) only HLA-A*1101, 1102, DRB5*01-02, DQB1*05, DRB1*1201-3, DRB3*0101, 0201, 0202, 0203, 0301 and DQB1*0301, 0304 remained significant. Allele frequencies of DRB1*0701 and DRB4*0101101, 0102, 0103, DQB1*05, DRB1*1301-22, DRB3*0101, 0201, 0202, 0203, 0301 and DQB1*0301, 0304 were significantly increased in Malay SLE patients compared with healthy control individuals. In contrast, Chinese SLE patients had increased allele frequencies of DRB1*1601-1606, DQB1*05, DRB1*1201-3, DRB3*0101, 0201, 0202, 0203, 0301, DRB3*0101, 0201, 0202, 0203, 0301 and DQB1*0301, 0304 compared with healthy control individuals. HLA-A*6801-02 and DRB1*1601-1606 frequencies appeared elevated in a subset of patients with serositis and DRB1* 0401-1122 frequency was elevated in those displaying neurologic disorder. However, unequivocal evidence of these associations would require investigation of substantially larger cohorts. On the whole, our findings suggest that HLA allele associations with SLE are race specific in Malays and Chinese.

HLA association in SLE patients from Lahore-Pakistan

The first genetic factors to be identified as important in the pathogenesis of Systemic lupus erythematosus (SLE) were those of the major histocompatibility complex (MHC) on chromosome 6. It is now widely accepted that MHC genes constitute a part of the genetic susceptibility to SLE. The study population comprised 61 SLE patients fulfilling at least four of the American college of Rheumatology criteria for SLE and 61 healthy blood donors as controls. SLE female versus male ratio was approximately 9:1. Mean age at diagnosis was 30.35 ± 1.687 (12-68 years). DNA-based HLA Typing for HLA-A, HLA-B, and HLA-DRB1 was carried out by Polymerase chain reaction with sequence specific primers using genomic DNA obtained from blood samples. A total of 22 alleles have been studied at locus A, 37 alleles at locus B and 17 DRB1 alleles. The allelic frequencies of HLA-A, HLA-B, and HLA-DRB1 antigens in SLE patients from Pakistan were compared with the controls. A significant increase was observed in the frequency of HLA-A*01, A*03, A*11, A*23, A*26 A*69, HLA-B*27, B*40, B*49, B*51, B*52, B*53, B*54, B*95, HLA-DRBI*01, DRBI*03, DRBI*11, DRBI*14 among SLE patients indicating a positive association of these alleles with SLE. HLA-A*24, A*29, A*31, A*34, A*68, A*92, HLA-B*18, HLA-DRB1*12, were found to be decreased in the patient group as compared to controls indicating a negative association of these alleles with SLE. Thus from this study we can conclude that SLE is associated with certain MHC alleles in Pakistani population.

Recent advances in the genetics of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by the production of antinuclear autoantibodies and the inflammatory infiltration of many organ systems. SLE is a complex disorder in which multiple genetic variants, together with environmental and hormonal factors, contribute to disease risk. In this article, we summarize our current understanding of the genetic contribution to SLE in light of recent genome-wide association studies, which have brought the total number of confirmed SLE susceptibility loci to 29. In the second section, we explore the functional implications of these risk loci and, in particular, highlight the role that many of these genes play in the Toll-like receptor and type I interferon signaling pathways. Finally, we discuss the genetic overlap between SLE and other autoimmune and inflammatory conditions as several risk loci are shared among multiple disorders, suggesting common underlying pathogenic mechanisms.

Male-only systemic lupus

OBJECTIVE

Systemic lupus erythematosus (SLE) is more common among women than men, a ratio of about 10 to 1. We undertook this study to describe familial male SLE within a large familial SLE cohort.

METHODS

SLE families (2 or more patients) were identified from the Lupus Multiplex Registry and Repository. Genomic DNA and blood samples were obtained using standard methods. Autoantibodies were determined by multiple methods. Medical records were abstracted for SLE clinical data. Fluorescent in situ hybridization (FISH) was performed with X and Y centromere-specific probes, and a probe specific for the Toll-like receptor 7 gene on the X chromosome.

RESULTS

Among 523 SLE families, we found 5 families in which all the SLE patients were male. FISH found no yaa gene equivalent in these families. SLE-unaffected primary female relatives from the 5 families with only-male SLE patients had a statistically increased rate of positive antinuclear antibodies compared to SLE-unaffected female relatives in other families. White men with SLE were 5 times more likely to have an offspring with SLE than White women with SLE, but there was no difference in this likelihood among Black men.

CONCLUSION

Because women in the all-male families had positive antinuclear antibodies, and men are more likely to have children with SLE, these data suggest genetic susceptibility factors that act only in men.

Identification of gp96 as a novel target for treatment of autoimmune disease in mice

Heat shock proteins have been implicated as endogenous activators for dendritic cells (DCs). Chronic expression of heat shock protein gp96 on cell surfaces induces significant DC activations and systemic lupus erythematosus (SLE)-like phenotypes in mice. However, its potential as a therapeutic target against SLE remains to be evaluated. In this work, we conducted chemical approach to determine whether SLE-like phenotypes can be compromised by controlling surface translocation of gp96. From screening of chemical library, we identified a compound that binds and suppresses surface presentation of gp96 by facilitating its oligomerization and retrograde transport to endoplasmic reticulum. In vivo administration of this compound reduced maturation of DCs, populations of antigen presenting cells, and activated B and T cells. The chemical treatment also alleviated the SLE-associated symptoms such as glomerulonephritis, proteinuria, and accumulation of anti-nuclear and -DNA antibodies in the SLE model mice resulting from chronic surface exposure of gp96. These results suggest that surface translocation of gp96 can be chemically controlled and gp96 as a potential therapeutic target to treat autoimmune disease like SLE.

Genetics of systemic lupus erythematosus and Sjögren's syndrome

PURPOSE OF REVIEW

To determine the advances made in the genetics of systemic lupus erythematosus (SLE) or Sjögren's syndrome as the era of genome-wide association and high-throughput single nucleotide typing begins.

RECENT FINDINGS

Several genome-wide association studies have been performed in SLE but there are no such studies published or in progress for Sjögren's syndrome. Genetics and the functional significance of risk alleles in the interferon pathway are being worked out in detail. This is especially true for STAT4 and IRF5. Gene copy number variation, a major source of genetic variability, is important for several genes that impart risk for SLE. An X chromosome copy number dose effect has recently been identified. Genetic evaluation of Sjögren's syndrome is limited to small studies that have concentrated on genes already shown to be risk factors in SLE.

SUMMARY

Knowledge of the genetics of SLE is advancing rapidly, whereas that of Sjögren's syndrome lags behind considerably.

A study of association of the complement C4 mutations with systemic lupus erythematosus in the Malaysian population

The aim of the present study was to investigate the association of C4 gene mutations with systemic lupus erythematosus, in 130 Malaysian SLE patients and 130 healthy controls. Generally, various PCR approaches were used to screen the mutations of the C4 genes, which included 2 bp (+TC) insertions at codon 1213 in exon 29, 1 bp deletions (-C) at codon 811 in exon 20, 1 bp (-C), 2 bp (-GT) deletions at codons 522 and 497 in exon 13 and null alleles. No mutations located at exons 13, 20 and 29 of the C4 gene, were detected amongst the patient and control samples in this study. C4A*Q0 was found in two out of the 130 control samples, while C4B*Q0 was present in two out of the 130 SLE patients. Overall, our results do not demonstrate a significant association to these known C4 mutations identified by previous studies, in the Malaysian scenario.

Identification of two independent risk factors for lupus within the MHC in United Kingdom families

The association of the major histocompatibility complex (MHC) with SLE is well established yet the causal variants arising from this region remain to be identified, largely due to inadequate study design and the strong linkage disequilibrium demonstrated by genes across this locus. The majority of studies thus far have identified strong association with classical class II alleles, in particular HLA-DRB1*0301 and HLA-DRB1*1501. Additional associations have been reported with class III alleles; specifically, complement C4 null alleles and a tumor necrosis factor promoter SNP (TNF-308G/A). However, the relative effects of these class II and class III variants have not been determined. We have thus used a family-based approach to map association signals across the MHC class II and class III regions in a cohort of 314 complete United Kingdom Caucasian SLE trios by typing tagging SNPs together with classical typing of the HLA-DRB1 locus. Using TDT and conditional regression analyses, we have demonstrated the presence of two distinct and independent association signals in SLE: HLA-DRB1*0301 (nominal p = 4.9 x 10(-8), permuted p < 0.0001, OR = 2.3) and the T allele of SNP rs419788 (nominal p = 4.3 x 10(-8), permuted p < 0.0001, OR = 2.0) in intron 6 of the class III region gene SKIV2L. Assessment of genotypic risk demonstrates a likely dominant model of inheritance for HLA-DRB1*0301, while rs419788-T confers susceptibility in an additive manner. Furthermore, by comparing transmitted and untransmitted parental chromosomes, we have delimited our class II signal to a 180 kb region encompassing the alleles HLA-DRB1*0301-HLA-DQA1*0501-HLA-DQB1*0201 alone. Our class III signal importantly excludes independent association at the TNF promoter polymorphism, TNF-308G/A, in our SLE cohort and provides a potentially novel locus for future genetic and functional studies.

B cells in glomerulonephritis: focus on lupus nephritis

The production of pathogenic antibody has been traditionally viewed as the principle contribution of B cells to the pathogenesis of immune-mediated glomerulonephritis. However, it is increasingly appreciated that B cells play a much broader role in such diseases, functioning as antigen-presenting cells, regulators of T cells, dendritic cells, and macrophages and orchestrators of local lymphatic expansion. In this review, we provide an overview of basic B cell biology and consider the evidence implicating B cells in one of the archetypal immune-mediated glomerulonephritides, lupus nephritis.

HLA-DRB1 alleles in juvenile-onset systemic lupus erythematosus: renal histologic class correlations

Human leukocyte antigens (HLA) DRB1*03 and DRB1*02 have been associated with systemic lupus erythematosus (SLE) in Caucasians and black populations. It has been observed that certain HLA alleles show stronger associations with SLE autoantibodies and clinical subsets, although they have rarely been associated with lupus renal histologic class. In the present study, HLA-DRB1 allele correlations with clinical features, autoantibodies and renal histologic class were analyzed in a cohort of racially mixed Brazilian patients with juvenile-onset SLE. HLA-DRB1 typing was carried out by polymerase chain reaction amplification with sequence-specific primers using genomic DNA from 55 children and adolescents fulfilling at least four of the American College of Rheumatology criteria for SLE. Significance was determined by the chi-square test applied to 2 x 2 tables. The HLA-DRB1*15 allele was most frequent in patients with renal, musculoskeletal, cutaneous, hematologic, cardiac, and neuropsychiatric involvement, as well as in patients positive for anti-dsDNA, anti-Sm, anti-U1-RNP, and anti-SSA/Ro antibodies, although an association between HLA alleles and SLE clinical features and autoantibodies could not be observed. The HLA-DRB1*17, HLA-DRB1*10, HLA-DRB1*15, and HLA-DRB1*07 alleles were significantly higher in patients with renal histologic class I, class IIA, class IIB, and class V, respectively. The present results suggest that the contribution of HLA- DRB1 alleles to juvenile-onset SLE could not be related to clinical or serological subsets of the disease, but it may be related to renal histologic classes, especially class I, class II A, class II B, and class V. The latter correlations have not been observed in literature.

A theoretical analysis of HLA-DRbeta1*0301-CLIP complex using the first three multipolar moments of the electrostatic field

Interactions between the HLA-DRbeta1*0301 molecule and several occupying peptides obtained from computational substitutions made to the CLIP peptide are studied. The exploration was carried out using a vector composed of the first three terms of the multipolar expansion of the electrostatic field, namely, charge (q), dipole (d) and quadrupole (C). Comparisons between pocket-peptide interactions established that the binding pockets for this HLA molecule are ordered in terms of their importance for binding peptides, as follows: P1 >>> P4 > P6 > P7 > P9. A set of electrostatically distinct amino acids that determine interaction stability and specificity were identified for each pocket. The beta74R residue was especially identified as being the key amino acid mediating the occupying peptide binding for pocket 4; this residue has been recently associated with Graves' disease.

The −169C/T polymorphism inFCRL3 is not associated with susceptibility to rheumatoid arthritis or systemic lupus erythematosus in a case–control study of Koreans

OBJECTIVE

In Japanese individuals, the -169C/T single-nucleotide polymorphism (SNP) in FCRL3 has been reported to be associated with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and autoimmune thyroid diseases. The objective of this study was to test the association of this SNP with RA and SLE, in a case-control study of Korean individuals.

METHODS

The -169C/T SNP in FCRL3 was genotyped in 1,060 patients with RA, 457 patients with SLE, and 697 unaffected control subjects, using the MassARRAY SNP genotyping system. Associations were tested by multivariate logistic regression, with adjustments for age and sex.

RESULTS

No association was detected between the -169C/T SNP and RA (odds ratio [OR] 1.11, 95% confidence interval [95% CI] 0.83-1.48, P = 0.50) or SLE (OR 1.00, 95% CI 0.73-1.37, P = 0.99). This SNP was not associated with rheumatoid factor status, shared epitope status, radiographic severity in patients with RA, or disease manifestations in patients with SLE.

CONCLUSION

The association of the -169C/T SNP in FCRL3 with RA and SLE that was observed in Japanese patients was not replicated in a Korean population.

Heritable factors shape natural human IgM reactivity to Ro60/SS-A and may predispose for SLE-associated IgG anti-Ro and anti-La autoantibody production

Systemic lupus erythematosus (SLE) is characterized by various IgG autoreactivities, among which anti-Ro/SS-A is particularly pathology-associated and early detectable. SLE also shows significant familial aggregation, but genetic factors are not well understood and remain controversial for disease-associated IgG. Here we report that IgM anti-Ro showed a uniquely high degree of heritability in a study of SLE-affected families. Unlike IgM anti-La or anti-dsDNA, IgM anti-Ro was also significantly correlated to IgG anti-Ro among SLE patients, as well as to IgG anti-La and anti-dsDNA. We conclude that largely genetically determined, thus natural IgM anti-Ro-bearing precursor B-cells, may be an important factor for class switching and determinant spreading in early phases of SLE pathogenesis. Furthermore, we found unexpected sex differences in isotype/specificity correlations among SLE-unaffected relatives and control subjects, which could help understand the strong gender bias associated with SLE. We propose that the study of such correlation structures may reveal characteristic spreading pathways relevant for human SLE.

Arginine at position 74 of the HLA-DR beta1 chain is associated with Graves' disease

Graves' disease (GD) is associated with HLA-DR3 (DRB1*03) in Caucasians, but the exact amino-acid sequence in the DR beta1 chain conferring susceptibility to GD is unknown. Therefore, the aim of our study was to identify the critical sequence among the HLA-DRB1 amino-acid residues occupying the peptide-binding pocket, which conferred susceptibility to GD. We sequenced the HLA-DRB1 locus in 208 Caucasian GD patients and 149 Caucasian controls. Sequence analysis showed an increased frequency of DR beta-Arg-74 in GD patients compared to controls (41.8 and 13.4%, respectively; P=2.3 x 10(-8), OR=4.6). Moreover, subset analyses showed that DR beta-Arg-74 was also significantly more frequent in the HLA-DR3 negative GD patients than in controls (7.6 vs 0.8%, P=0.02, OR=10.5), suggesting that the association with DR beta-Arg-74 is independent of the association with HLA-DR3. Structural modeling studies demonstrated that the change at position 74 from the neutral amino acids Ala or Gln to the positively charged amino-acid Arg significantly modifies the three-dimensional structure of the DR peptide-binding pocket. Our results suggested that structural heterogeneity of the DR beta-chain peptide-binding pocket P4 at residue 74 predispose some at risk individuals to GD.

HLA-DRB1 and -DQB1 alleles and gene polymorphisms of selected cytokines in systemic lupus erythematosus

OBJECTIVE

The objective of this study was to evaluate the genetic profiles of selected cytokines (transforming growth factor beta 1, tumor necrosis factor alpha, interleukin-6, interferon gamma, and interleukin-10) in systemic lupus erythematosus and the contributions of human leukocyte antigen (HLA)-DRB1 and -DQB1 alleles to susceptibility for this disease.

PATIENTS AND METHODS

The study was carried out in 24 SLE patients and 36 healthy controls (from Upper Silesia) using polymerase chain reaction methods. All persons were of Caucasoid origin. Standard association analysis was used to compare the HLA alleles and frequency of cytokine gene polymorphisms between these groups.

RESULTS

Only the frequency of HLA-DRB1*07 allele was higher in SLE patients than controls (odds ratio 2.92, 95% confidence interval 1.16-7.33), but the difference did not reach statistical significance when Bonferroni's adjustment procedure was performed. No other significant associations were noted between class II alleles (DR1-DR6, DR8-DR10, DQ1-DQ4) and SLE. The frequency of the interleukin-6 GG and GC genotypes was significantly higher in SLE patients than in controls, and a significantly higher percentage of the G vs C alleles between patients and controls was revealed (odds ratio 2.53, 95% confidence interval 1.37-4.65, chi-squared test 8.16, P < 0.05). The most significant association of increased frequency of the G allele with SLE was more commonly noted in HLA-DRB1*07-positive patients (odds ratio 10.29, 95% confidence interval 5.34-19.83, P < 0.001). These data indicate that this combination could contribute toward determining the susceptibility to SLE, but its possible significance will require confirmation by further studies.

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.

Pathogenesis of systemic lupus erythematosus

The exact patho-aetiology of systemic lupus erythematosus (SLE) remains elusive. An extremely complicated and multifactorial interaction among various genetic and environmental factors is probably involved. Multiple genes contribute to disease susceptibility. The interaction of sex, hormonal milieu, and the hypothalamo-pituitary-adrenal axis modifies this susceptibility and the clinical expression of the disease. Defective immune regulatory mechanisms, such as the clearance of apoptotic cells and immune complexes, are important contributors to the development of SLE. The loss of immune tolerance, increased antigenic load, excess T cell help, defective B cell suppression, and the shifting of T helper 1 (Th1) to Th2 immune responses leads to B cell hyperactivity and the production of pathogenic autoantibodies. Finally, certain environmental factors are probably required to trigger the disease.

Immunopathology and the gene therapy of lupus

Lupus is a chronic autoimmune inflammatory disease with complex clinical manifestations. In humans, lupus, also known as systemic lupus erythematosus (SLE), affects between 40 and 250 individuals, mostly females, in each 100 000 of the population. There are also a number of murine models of lupus widely used in studies of the genetics, immunopathology, and treatment of lupus. Human patients and murine models of lupus manifest a wide range of immunological abnormalities. The most pervasive of these are: (1) the ability to produce pathogenic autoantibodies; (2) lack of T- and B-lymphocyte regulation; and (3) defective clearance of autoantigens and immune complexes. This article briefly reviews immunological abnormalities and disease mechanisms characteristic of lupus autoimmunity and highlight recent studies on the use of gene therapy to target these abnormalities.

HLA class II antigens associated with lupus nephritis in Italian SLE patients

Human leukocyte antigen DR2 (HLA-DR2), namely the allelic variant HLA-DR15, have been associated with lupus nephritis (LN) in Caucasians. The study investigated the relationships between HLA class II alleles and lupus nephritis in Italian patients. Two hundred forty-four patients fulfilling the American Rheumatism Association criteria for systemic lupus erythematosus (SLE) were typed for HLA-DRB1*, -DQA1*, -DQB1*, and -DPB1* alleles by polymerase chain reaction-sequence-specific oligonucleotide and polymears chain reaction-single-strand polymorphism; 71 patients had renal damage assessed by renal biopsy. Glomerulonephritis was classified using WHO criteria. Significance was tested by X(2) on 2x2 tables. HLA-DQA1*0101 was strongly associated with LN (OR = 2.72 [1.43-5.19]; p = 0.002), whereas HLA-DRB1*1501 was only marginally associated (OR = 1.94 [0.88-4.26]; p = not significant). HLA-DQA1*0102 demonstrated a significant protective effect (OR = 0.31 [0.14-0.86]; p = 0.002). On analyzing the distribution of HLA-DRB1*1501 bearing haplotypes in our SLE patients we found that the HLA-DRB1*1501 greatly enhanced the risk of developing LN conferred by the DQA1*0101 allele (OR = 65.96 [9.35-1326.25]), whereas DQA1*0102 suppressed the nephritogenic effect of DRB1*1501. At renal biopsy, 80% of DRB1*15 positive patients were classified as having class IV LN with the remaining 20% having class III LN. The figures were 19% and 21%, respectively, among the HLA-DR15 negative patients. In the Italian population HLA-DQA and HLA-DR alleles interact in conferring susceptibility to or protection against lupus nephritis, the diffuse proliferative glomerulonephritis (i.e., the most severe form of nephritis) is associated with the HLA-DR15 bearing haplotypes.

Interferon-inducible gene expression signature in peripheral blood cells of patients with severe lupus

Systemic lupus erythematosus (SLE) is a complex, inflammatory autoimmune disease that affects multiple organ systems. We used global gene expression profiling of peripheral blood mononuclear cells to identify distinct patterns of gene expression that distinguish most SLE patients from healthy controls. Strikingly, about half of the patients studied showed dysregulated expression of genes in the IFN pathway. Furthermore, this IFN gene expression "signature" served as a marker for more severe disease involving the kidneys, hematopoetic cells, and/or the central nervous system. These results provide insights into the genetic pathways underlying SLE, and identify a subgroup of patients who may benefit from therapies targeting the IFN pathway.

The genetic basis for systemic lupus erythematosus

Genetic factors play a major role in the development of lupus. More than 5% of cases are familial, and the concordance rate between identical twins is 40%. Genetic studies in mice suggest a complex mechanism of transmission involving interactions among several susceptibility genes and, probably, protective genes. Genetic studies in humans have identified nearly 50 chromosomal areas possibly involved in lupus transmission. Significant linkage has been found for at least six regions, two on chromosome 1, one near the HLA region on chromosome 6, and three on chromosomes 2, 4, and 16, respectively. Many candidate genes have been identified based on their location or possible pathogenic effects. Specific characteristics of the HLA region, as well as complement factor deficiencies, may promote nuclear antigen presentation, thereby triggering autoantibody production. The genetic polymorphism of cytokines and, perhaps, of the T-cell receptor (TCR) may contribute to deregulate lymphocyte activity. The polymorphism of the Fc receptors of immunoglobulins may affect immune complex clearance, thereby promoting tissue damage. Further genetic studies are needed to enrich the fund of knowledge on lupus and to identify new targets for treatment.

Familial collapsing glomerulopathy: clinical, pathological and immunogenetic features

BACKGROUND

Collapsing glomerulopathy (CG) is an aggressive form of glomerular injury frequently seen in association with HIV infection, although it is also recognized in non-HIV patients as a primary disease. Until now, the occurrence of CG in a familial pattern has not been reported.

METHODS

We studied five members of a family (siblings), admitted for evaluation of proteinuria and nephrotic syndrome. They had no other family history of renal disease. Blood samples for major histocompatibility complex (MHC) analysis were obtained from the five siblings, both parents and four relatives.

RESULTS

Renal biopsy performed in four out of the five siblings revealed capillary collapse and retraction with visceral epithelial cell swelling and reabsorption droplets, consistent with CG. Two of the patients had suggestive symptoms of systemic lupus erythematosus, such as arthritis, rash, hair loss, moderate leukopenia and lymphopenia, low titers of antinuclear antibodies (ANA) and anti-SSA/Ro antibodies, but no immune complex deposition on renal biopsy. IgG serology for parvovirus B19 (PVB-19) was positive only in two siblings but polymerase chain reaction (PCR) was negative. Immunogenetic analysis showed that all patients shared the same MHC haplotype inherited from the mother.

CONCLUSIONS

CG can present in a familial pattern. Since a similar MHC haplotype was observed in affected and non-affected members of the family, we conclude that the environment plays an important role in the development of the disease.

Analysis of human leukocyte antigens class II-DR in Brazilian children and adolescents with systemic lupus erythematosus

OBJECTIVE

To analyze the frequency of human leukocyte antigens class II-DR in children and adolescents with systemic lupus erythematosus.

PATIENTS AND METHODS

Fifty-fiveBrazilian systemic lupus erythematosus children and adolescents and 308 healthy individuals were studied. Gender, race, and age of onset of systemic lupus erythematosus were recorded. The human leukocyte antigens typing of class II-DR was carried out by polymerase chain reaction amplification with sequence-specific primers (PCR-SSP). Data were analyzed statistically using the chi square test with Yates' correction, Fisher's exact test, and Bonferroni's correction.

RESULTS

Human leukocyte antigen-DR 15 was the most frequently detected antigen in this group of children and adolescents, and it also occurred more frequently in the female group, in children with onset of systemic lupus erythematosus between 0 and 9 years and between 10 to 14 years, and in the Black race group, but these associations were not statistically significants.

CONCLUSION

In this group of children and adolescents with a high degree of racial admixture, we could not verify a significant association between human leukocyte antigens class II-DR and systemic lupus erythematosus.

FcgammaRIIa/IIIa polymorphism and its association with clinical manifestations in Korean lupus patients

The aim of this study was to determine the distribution of the FcgammaRlla and FcgammaRIIIa polymorphisms and their association with clinical manifestations in Korean lupus patients. Three hundred SLE (systemic lupus erythematosus) patients (48 male, 252 female) meeting 1982 ACR criteria and 197 Korean disease-free controls were enrolled. Genotyping for FcgammaRlla 131 R/H and FcgammaRIIIa 176 F/V was performed by PCR of genomic DNA using allele-specific primers and the FcgammaRIIIa genotype was confirmed by direct sequencing of PCR product in some cases. There was significant skewing in the distribution of the three FcgammaRIIa genotypes between the SLE and the controls (P=0.002 for R/R131 vs R/H131 and H/H131, OR 2.5 (95% Cl 1.4-4.5), but not in FcgammaRIIIa genotypes. FcgammaRIIa-R allele was a significant predictor of lupus nephritis, as compared with SLE patients without nephritis (P=0.034 for R131 vs H131, OR 1.4 (95% Cl 1.03-1.9)), but proliferative nephritis (WHO class III and IV) was less common in patients with FcgammaRlla-R/R131 and in FcgammaRIIa-R allele. In 300 SLE patients, high binding allele combination H131/V176 was less common in SLE with nephritis than in SLE without nephritis. Hemolytic anemia was less common in R131/F176 allele combination among four FcgammaRIIa/FcgammaRIIIa allelic combinations. Male SLE patients showed a higher frequency of renal involvement, serositis, thrombocytopenia, malar rash and discoid rash than female SLE, and male SLE had a higher frequency of FcgammaRIIa-R/R131 or R131-allele than male controls, but FcgammaRIIa or FcgammaRIIIa genotypes had no association with renal involvement in male SLE patients. FcgammaRIIa-H/H131 showed a higher frequency of hemolytic anemia and less pulmonary complications in male SLE. Female SLE patients showed higher frequency of any hematologic abnormality, lymphopenia, anticardiolipin antibody (+) and anti-Ro antibody (+) than male SLE, and had earlier onset of first symptoms. There was no skewing in FcgammaRIIa or FcgammaRIIIa genotypes between female SLE and female controls, but FcgammaRIIa-R131 allele showed skewing between female SLE with nephritis and female SLE without nephritis. The age at onset of thrombocytopenia was earlier in FcgammaRIIa R/R131 among three FcgammaRIIa genotypes, and serositis in FcgammaRIIIa-F/F176 among three FcgammaRIIIa genotypes. FcgammaRIIa-R131 homozygote was a major predisposing factor to the development of SLE and FcgammaRIIa-RI31 homozygote and R131 allele were a predisposing factor, and H131/V176 was a protective allele combination in lupus nephritis. In contrast to other ethnic patients, in our study cohort, clinical manifestation was different between male and female, and FcgammaRIIa and FcgammaRIIIa showed somewhat different clinical associations between the genders.