Early-onset pauciarticular juvenile chronic arthritis is associated with a mutation in the Y-box of the HLA-DQA1 promoter

Langfristentwicklungen in der Kinder- und Jugendrheumatologie

Im Gebiet der Kinderrheumatologie gab es in den letzten Jahrzehnten immense Fortschritte, die sowohl die Diagnostik, als auch die Therapie nachhaltig verbessert haben. Obwohl erst seit 2003 in Deutschland offiziell als Zusatzbezeichnung anerkannt, stehen heutzutage über 200 Kinder- und Jugendrheumatologen (d. h. 1,4 Kinderrheumatologen pro 100 000 Kinder) für die Erkennung und Behandlung von rheumatischen Erkrankungen bei Kindern und Jugendlichen bundesweit zur Verfügung. Neue Erkenntnisse in der Pathogenese rheumatischer Erkrankungen und die sich stetig weiterentwickelnde genetische Diagnostik haben das rheumatische Krankheitsspektrum und die Behandlungsmöglichkeiten dramatisch erweitert Internationale Forschungsnetzwerke und eine spezielle Gesetzgebung für die Entwicklung von pädiatrischen Medikamenten führten zur Zulassung von zahlreichen neuen Rheumamedikamenten, deren Sicherheit im klinischen Alltag seit der Jahrtausendwende systematisch in Deutschland untersucht wird. Maßnahmen zur Sicherung der Versorgungsqualität wurden implementiert, Standardinstrumente zur Bewertung der Krankheitsaktivität und Krankheitslast aus Patientensicht eingeführt sowie Initiativen zur Verbesserung der Versorgung Betroffener (z. B. die ProKind-Initiative) auf den Weg gebracht. Diese Veränderungen haben die Prognose und Lebensperspektive rheumakranker Kinder und Jugendlicher verbessert, wenngleich noch weiterer Optimierungsbedarf besteht.

[Polyarticular juvenile idiopathic arthritis and rheumatoid arthritis : Common features and differences]

The spectrum of polyarthritic diseases in childhood as well as in adulthood is wide. In the differential diagnostics different age-related diseases must be taken into consideration. Although, a clear similarity is obvious in all age groups for the classical diseases of polyarticular juvenile idiopathic arthritis and rheumatoid arthritis with respect to the pathogenesis, clinical manifestation and treatment options, this review points to specific differences. The prognosis of polyarthritis in children mainly depends on the joint manifestation, whereas extra-articular comorbidities play a predominant role in the older adult population.

High Levels of DEK Autoantibodies in Sera of Patients With Polyarticular Juvenile Idiopathic Arthritis and With Early Disease Flares Following Cessation of Anti-Tumor Necrosis Factor Therapy

OBJECTIVE

The nuclear oncoprotein DEK is an autoantigen associated with juvenile idiopathic arthritis (JIA), especially the oligoarticular subtype. DEK is a secreted chemotactic factor. Abundant levels of DEK and DEK autoantibodies are found in inflamed synovium in JIA. We undertook this study to further characterize the nature of DEK autoantibodies in screening serum samples from 2 different cohorts that consisted mostly of patients with JIA.

METHODS

DEK autoantibody levels were analyzed in sera from 33 JIA patients, 13 patients with other inflammatory conditions, and 11 healthy controls, as well as in 89 serum samples from JIA patients receiving anti-tumor necrosis factor (anti-TNF) therapy. Recombinant His-tagged full-length DEK protein (1-375 amino acids [aa]) and the 187-375-aa and 1-350-aa His-tagged DEK fragments made in a baculovirus system were used for enzyme-linked immunosorbent assay (ELISA) and immunoblotting. The C-terminal 25-aa fragment of DEK was expressed in a glutathione S-transferase-tagged vector. ELISA results were calculated as area under the curve by the trapezoidal rule.

RESULTS

DEK autoantibody levels were significantly higher in patients with polyarticular JIA than in those with oligoarticular JIA, and were higher in patients with polyarticular JIA who had more active disease after cessation of anti-TNF therapy. Immunoblotting against the C-terminal 25-aa fragment of DEK confirmed that this section of the DEK molecule is the most immunogenic domain.

CONCLUSION

DEK autoantibody levels are higher in patients with polyarticular JIA than in those with oligoarticular JIA, and higher in patients who have disease flares after cessation of anti-TNF therapy. The C-terminal 25-aa fragment is the most immunogenic portion of DEK. These findings are significant with respect to the nature of DEK autoantibodies, their contribution to JIA pathogenesis, and their implications for JIA management.

Cis-regulatory evolution in a wild primate: Infection-associated genetic variation drives differential expression of MHC-DQA1 in vitro

Few studies have combined genetic association analyses with functional characterization of infection-associated SNPs in natural populations of nonhuman primates. Here, we investigate the relationship between host genetic variation, parasitism and natural selection in a population of red colobus (Procolobus rufomitratus tephrosceles) in Kibale National Park, Uganda. We collected parasitological, cellular and genomic data to test the following hypotheses: (i) MHC-DQA1 regulatory genetic variation is associated with control of whipworm (Trichuris) infection in a natural population of red colobus; (ii) infection-associated SNPs are functional in driving differential gene expression in vitro; and (iii) balancing selection has shaped patterns of variation in the MHC-DQA1 promoter. We identified two SNPs in the MHC-DQA1 promoter, both in transcription factor binding sites, and both of which are associated with decreased control of Trichuris infection. We characterized the function of both SNPs by testing differences in gene expression between the two alleles of each SNP in two mammalian cell lines. Alleles of one of the SNPs drove differential gene expression in both cell lines, while the other SNP drove differences in expression in one of the cell lines. Additionally, we found evidence of balancing selection acting on the MHC-DQA1 promoter, including extensive trans-species polymorphisms between red colobus and other primates, and an excess of intermediate-frequency alleles relative to genome-wide, coding and noncoding RADseq data. Our data suggest that balancing selection provides adaptive regulatory flexibility that outweighs the consequences of increased parasite infection intensity in heterozygotes.

A knowledge-based method for association studies on complex diseases

Complex disorders are a class of diseases whose phenotypic variance is caused by the interplay of multiple genetic and environmental factors. Analyzing the complexity underlying the genetic architecture of such traits may help develop more efficient diagnostic tests and therapeutic protocols. Despite the continuous advances in revealing the genetic basis of many of complex diseases using genome-wide association studies (GWAS), a major proportion of their genetic variance has remained unexplained, in part because GWAS are unable to reliably detect small individual risk contributions and to capture the underlying genetic heterogeneity. In this paper we describe a hypothesis-based method to analyze the association between multiple genetic factors and a complex phenotype. Starting from sets of markers selected based on preexisting biomedical knowledge, our method generates multi-marker models relevant to the biological process underlying a complex trait for which genotype data is available. We tested the applicability of our method using the WTCCC case-control dataset. Analyzing a number of biological pathways, the method was able to identify several immune system related multi-SNP models significantly associated with Rheumatoid Arthritis (RA) and Crohn's disease (CD). RA-associated multi-SNP models were also replicated in an independent case-control dataset. The method we present provides a framework for capturing joint contributions of genetic factors to complex traits. In contrast to hypothesis-free approaches, its results can be given a direct biological interpretation. The replicated multi-SNP models generated by our analysis may serve as a predictor to estimate the risk of RA development in individuals of Caucasian ancestry.

Impact of tumour necrosis factor-α polymorphisms on irritant contact dermatitis

BACKGROUND

Genetic variations in genes coding for cytokines involved in skin inflammation may alter their expression, thus changing the susceptibility to irritant contact dermatitis (ICD).

OBJECTIVES

To determine the prevalence of polymorphisms in the cytokine genes TNFA-238 and TNFA-308 in patients with occupational ICD, and to compare it with that in controls.

METHODS

In a case-control study, 478 patients with occupational ICD of the hands were genotyped for TNFA-238 and TNFA-308 polymorphisms. The results were compared with those for 393 apprentices from the same high-risk occupations (controls).

RESULTS

For a carrier of a variant TNFA-238A allele, the odds ratio (OR) of acquiring ICD was 0.57 [95% confidence interval (CI) 0.34-0.97], suggesting a protective effect of the A allele. The genotype distributions were 94.4% wild type (G/G), 5.6% heterozygous (G/A) and 0% homozygous for variant allele (A/A) in patients, and 90.9%, 8.5%, and 0.6%, respectively in controls. In contrast, carriers of the variant TNFA-308A allele had an increased risk of ICD [OR 1.33; 95% CI 1.05-1.74; G/G 66.4%, G/A 31.2%, and A/A 2.4% (patients) versus 73.5%, 24.6%, 1.9% in controls].

CONCLUSIONS

Individuals with a TNFA-238 polymorphism are less prone and those with a TNFA-308 polymorphism are more prone to develop ICD of the hands, suggesting a protective versus a detrimental effect of the A allele respectively.

DEK in the synovium of patients with juvenile idiopathic arthritis: characterization of DEK antibodies and posttranslational modification of the DEK autoantigen

OBJECTIVE

DEK is a nuclear phosphoprotein and autoantigen in a subset of children with juvenile idiopathic arthritis (JIA). Autoantibodies to DEK are also found in a broad spectrum of disorders associated with abnormal immune activation. We previously demonstrated that DEK is secreted by macrophages, is released by apoptotic T cells, and attracts leukocytes. Since DEK has been identified in the synovial fluid (SF) of patients with JIA, this study was undertaken to investigate how DEK protein and/or autoantibodies may contribute to the pathogenesis of JIA.

METHODS

DEK autoantibodies, immune complexes (ICs), and synovial macrophages were purified from the SF of patients with JIA. DEK autoantibodies and ICs were purified by affinity-column chromatography and analyzed by 2-dimensional gel electrophoresis, immunoblotting, and enzyme-linked immunosorbent assay. DEK in supernatants and exosomes was purified by serial centrifugation and immunoprecipitation with magnetic beads, and posttranslational modifications of DEK were identified by nano-liquid chromatography tandem mass spectrometry (nano-LC-MS/MS).

RESULTS

DEK autoantibodies and protein were found in the SF of patients with JIA. Secretion of DEK by synovial macrophages was observed both in a free form and via exosomes. DEK autoantibodies (IgG2) may activate the complement cascade, primarily recognize the C-terminal portion of DEK protein, and exhibit higher affinity for acetylated DEK. Consistent with these observations, DEK underwent acetylation on an unprecedented number of lysine residues, as demonstrated by nano-LC-MS/MS.

CONCLUSION

These results indicate that DEK can contribute directly to joint inflammation in JIA by generating ICs through high-affinity interaction between DEK and DEK autoantibodies, a process enhanced by acetylation of DEK in the inflamed joint.

Do infections trigger juvenile idiopathic arthritis?

Juvenile idiopathic arthritis (JIA) is a disease that was prominent with increased inflammation response in immune system, appeared mostly with peripheral arthritis and endogenous and exogenous antigens play a role in the pathogenesis of disease. Two major reasons were thinking to be considerably important. First of them is immunological predisposition and the second one is environmental factors. Infections are considered to be the most important between environmental factors but also stress and trauma are also important in the etiology of the disease. However, the relation between JIA and infections is not clearly defined but the relation between adult chronic arthritis and infections was well-defined. A total of 70 patients, 26 with primer JIA, 20 with recurrent JIA, 24 healthy control were included in this study. Mycoplasma pneumoniae, Chlamydophila pneumoniae and C. Jejuni were detected in 4, 1 and 1 of 10 (38.46%) patients with primer JIA, respectively. Salmonella enteritidis, EBV, M. pneumoniae, C. jejuni and Borrelia burgdorferi were detected in 1, 2, 2, 2, and 1 of the 8(40%) patients with recurrent JIA, respectively. S. enteritidis were isolated in feces culture and also identified by agglutination method. Infection was detected in total 18 (39.13%) of patient groups. C. pneumoniae and C. jejuni were detected in 1 and 1 of 2(8.33) healthy control groups, respectively. Throat culture positivity was not detected in any of the patient and healthy control groups. In conclusion, etiopathogenesis of JIA is not clearly understood and suggested that various factors can trigger the disease and it is the most common rheumatoid disease of childhood. However, there are some studies focusing especially on one infectious agent but this is the first study including such a big range of infectious agents in the literature for the microorganisms that can be suggested to have a role in the etiopathogenesis of JIA. We have a conclusion in the light of our results and suggest that some microorganisms can trigger and increase the intensity of clinical situation according to the case. When we evaluate the primer and recurrent JIA groups; M. pneumoniae and C. jejuni come forward and seen common in JIA cases. We also suggest that the pre-diagnosis of microorganisms, which can play a role as primarily or by intervening in the etiopathogenesis of JIA and adding specific antimicrobial therapy to the standard JIA therapy, it is possible to perform new, extended, especially molecular based serial case studies.

HLA-DQA1 gene expression profiling in oligoarticular JIA

Polymorphisms in the upstream regulatory region of the HLA class II DQA1 gene are currently defined by 10 different alleles. Two of them carrying a Y-box mutation are associated with susceptibility to oligoarticular juvenile idiopathic arthritis (OA-JIA). We investigated allele-dependent differences in HLA-DQA1 gene expression in OA-JIA patients. In cells from affected joints compared to peripheral blood, gene expression of HLA-DRA as well as total HLA-DQA1 was significantly upregulated. Differential analyses of HLA-DQA1 allelic expression showed DQA1*02 and *04 to be comparatively increased. Intra-articular upregulation of HLA-DQA1 was predominantly observed for the OA-JIA associated allele HLA-DQA1*04. Nevertheless, the Y-box mutation of the disease-associated allele DQA1*0401 was not a common denominator for expression behaviour.

A survey of H2 gene sequences, including new wild-derived genes

A comprehensive collection of mouse major histocompatibility complex (MHC) promoter and exon 2 sequences is here presented and analysed. It covers the three best known class II genes and one class I gene, and includes new wild mouse sequences from the 'w' back-cross strains and from the Jackson collection. All sequences are in GenBank, and the new exon sequences largely confirm previous typing by serology and immune function. As in human leucocyte antigen (HLA), the overall nucleotide diversity is higher in the class II genes, in keeping with their more diverse function. Diversity along the promoters is highest in the region of known transcription factor binding, most notably in and around the CRE and rCAAT sequences. This distribution parallels that of maximum single nucleotide polymorphism impact previously obtained with reporter constructs. Taking into account the low nucleotide diversity of the CIITA promoter, we conclude that MHC promoters are likely to have diversified through co-evolution with their exons, while themselves also directly subject to natural selection. The H2Eb(p) alleles form a distinct group, associated with their lack of the recombination hot spot located between exon 2 and exon 3. The collection is expected to prove useful in guiding functional and evolutionary studies.

Ancient polymorphism and functional variation in the primate MHC-DQA1 5' cis-regulatory region

Precise regulation of MHC gene expression is critical to vertebrate immune surveillance and response. Polymorphisms in the 5' proximal promoter region of the human class II gene HLA-DQA1 have been shown to influence its transcriptional regulation and may contribute to the pathogenesis of autoimmune diseases. We investigated the evolutionary history of this cis-regulatory region by sequencing the DQA1 5' proximal promoter region in eight nonhuman primate species. We observed unexpectedly high levels of sequence variation and multiple strong signatures of balancing selection in this region. Specifically, the considerable DQA1 promoter region diversity was characterized by abundant shared (or trans-species) polymorphism and a pronounced lack of fixed differences between species. The majority of transcription factor binding sites in the DQA1 promoter region were polymorphic within species, and these binding site polymorphisms were commonly shared among multiple species despite evidence for negative selection eliminating a significant fraction of binding site mutations. We assessed the functional consequences of intraspecific promoter region diversity using a cell line-based reporter assay and detected significant differences among baboon DQA1 promoter haplotypes in their ability to drive transcription in vitro. The functional differentiation of baboon promoter haplotypes, together with the significant deviations from neutral sequence evolution, suggests a role for balancing selection in the evolution of DQA1 transcriptional regulation in primates.

Polymorphisms in the TNFA gene promoter region show evidence of strong linkage disequilibrium with HLA and are associated with delayed neutrophil engraftment in unrelated donor hematopoietic stem cell transplantation

Sustained myeloid engraftment is an important determinant of outcome in hematopoietic stem cell transplantation (HSCT). Human tumor necrosis factor (TNF)-alpha is encoded by a gene, TNFA, located in the class III region of the major histocompatibility complex on chromosome 6, flanked by the human leukocyte antigen (HLA) class I and II regions. A number of polymorphisms in the promoter region of the TNFA gene have been associated with increased production of TNF-alphain vivo. Additionally, raised TNF-alpha levels have been reported to have a detrimental effect on the outcome in HSCT, in particular on early complications such as acute graft vs host disease, failure to engraft, and transplant-related mortality. There is evidence of linkage disequilibrium (LD) between TNFA promoter polymorphisms and extended HLA haplotypes. We have genotyped 73 cell lines and 189 donor/recipient pairs (undergoing HSCT) for their TNFA polymorphism, all of which had been well characterized with respect to their HLA genes. We found evidence of strong LD between HLA genes and TNFA; however, there was also evidence for recombination events having taken place, as we found that a number of transplant pairs who were matched for their HLA haplotypes were not matched for their TNFA alleles. We analyzed early outcomes in the transplant recipients and found a significant delay in engraftment in those pairs where both donor and recipients possessed an AG allele (associated with higher TNF-alpha levels). Our results suggest a functional effect of TNFA polymorphisms on myeloid engraftment in unrelated HSCT.

The prevalence of human leukocyte antigen (HLA) DR/DQ/DP alleles in Kuwaiti children with oligoarticular juvenile idiopathic arthritis

We have determined the prevalence of human leukocyte antigen (HLA)-DR, DQ and DP alleles in Kuwaiti children with oligoarticular juvenile idiopathic arthritis (OA-JIA) and healthy controls using the PCR-SSP (sequence specific primers) method. The analysis took into account the presence of antinuclear antibodies and chronic anterior uveitis. DRB1*03 (RR 2.20, P<0.001), DRB1*08 (RR 5.280, P<0.026), DQA1*0501 (RR 1.930, P<0.001), DQB1*0304 (RR 7.920, P<0.002), DQB1*0501 (RR 3.080, P<0.007) and DPB1*0101 (RR 8.8, P<0.001) were the main HLA alleles associated with OA-JIA in Kuwaiti Arabs in this study. DRB1*03 was detected in 71% of children with positive ANA, and in 50% of children with anterior uveitis. DQA1 alleles *0501, *0103 and *0105 (P<0.001; 0.029 and 0.024 respectively) were found to be associated with OA-JIA. In contrast, DQA1*0301 and DQA1*0302 alleles appear to be protective in Kuwaiti children (RR 0.153, P<0.001 and RR 0.278, P<0.016 respectively). The DQB1 alleles *0304 and *0501 were associated with OA-JIA (P<0.002 and P<0.007 respectively). In the case of DPB1, only one allele (*0101) was associated with OA-JIA (P<0.001). Most Kuwaiti Arab patients with OA-JIA who carried a DQ or DP susceptibility allele also had an accompanying DRB1*03 or *8 allele.

Does the polymorphism of MHC class II promoters matter?

The promoters of genes of the major histocompatibility complex vary not only because of linkage disequilibrium with their coding sequences but also, we argue, because of natural selection that acts particularly strongly on MHC II gene promoters. Thus, the promoter of H2Eb varies more than that of H2K, to an extent that cannot be accounted for by coding variation, and the same applies to HLA.DRB1 in comparison with H2D. We discuss how transduction by lentivirus vectors followed by adoptive transfer of monoclonal T cells could be used to test the functional activity of variant mouse promoters in vivo, and how homologous recombination in suitable cell lines might provide a short cut to obtaining promoter knock-ins.

Analysis of MHC region genetics in Finnish patients with juvenile idiopathic arthritis: evidence for different locus-specific effects in polyarticular vs pauciarticular subsets and a shared DRB1 epitope

This study used Finnish juvenile idiopathic arthritis (JIA) probands with pauciarticular and rheumatoid factor (RF) negative polyarticular subtypes of JIA to further define the genetic susceptibility to JIA. We examined 16 markers spanning an 18 cM region of chromosome 6 encompassing the MHC and surrounding genomic region in a set of 235 Finnish JIA nuclear families and 639 Finnish control individuals. Analysis by case/control association and transmission disequilibrium test (TDT) methods each demonstrated strong evidence for a susceptibility locus near the D6S2447 microsatellite (P<10(-6) for both methods) that is flanked by DQB1 and DRB1. Analysis of the DRB1 locus suggested that DRB1*0801 and DRB1*1101 rather than DQA1 or other HLA alleles may be responsible for conferring susceptibility to disease. These findings are consistent with the most compelling results of previous reports on HLA associations and suggest a JIA DRB1 shared epitope encompassing critical amino-acid residues in the third hypervariable region of this molecule. Most importantly, in pauciarticular patients, the strong association does not extend to proximal markers as it does in polyarticular patients (P<0.00001). Analysis strongly suggests that the difference is because of additional JIA susceptibility loci within the MHC being present in polyarticular RF negative patients.

DEK binding to class II MHC Y-box sequences is gene- and allele-specific

Using electrophoretic mobility shift assays, we examined sequence-specific binding of DEK, a potential autoantigen in juvenile rheumatoid arthritis, to conserved Y-box regulatory sequences in class II MHC gene promoters. Nuclear extracts from several cell lines of different phenotypes contained sequence-specific binding activity recognizing DRA, DQA1*0101, and DQA1*0501 Y-box sequences. Participation of both DEK and NF-Y in the DQA1 Y-box binding complex was confirmed by 'supershifting' with anti-DEK and anti-NF-Y antibodies. Recombinant DEK also bound specifically to the DQA1*0101 Y box and to the polymorphic DQA1*0501 Y box, but not to the consensus DRA Y box. Measurement of the apparent dissociation constants demonstrated a two- to fivefold difference in DEK binding to the DQA1 Y-box sequence in comparison with other class II MHC Y-box sequences. Residues that are crucial for DEK binding to the DQA1*0101 Y box were identified by DNase I footprinting. The specific characteristics of DEK binding to these related sequences suggests a potential role for DEK in differential regulation of class II MHC expression, and thus in the pathogenesis of juvenile rheumatoid arthritis and other autoimmune diseases.

Relative quantification of HLA-DRA1 and -DQA1 expression by real-time reverse transcriptase-polymerase chain reaction (RT-PCR)

Polymorphism in the upstream regulatory region (URR) of the MHC class II DQA1 gene defines 10 different alleles named QAP (DQA1 promoter). In vitro studies have suggested that allelic polymorphism in the HLA-DQA promoter region may result in differences in HLA-DQA1 gene expression. In the present study, we used real-time reverse transcriptase-polymerase chain reaction (RT-PCR) to quantify differences in HLA-DQA1 gene expression. After the isolation of total mRNA, reverse transcription into cDNA was carried out using random hexamer priming and moloney murine leukaemia virus (MMLV) reverse transcriptase. Quantification of DQA1 mRNA species using a set of six group-specific primer pairs for the detection of HLA-DQA1*01, *02, *03, *04, *05 and *06 was carried out on an ABI PRISM GeneAmp 7700 Sequence Detection System (Perkin Elmer, Foster City, CA) with real-time detection and quantification taking advantage of the fluorescence TaqMan technology (Perkin Elmer, Foster City, CA). Normalization of cDNA templates was achieved by glyceraldehyde-3-phosphate dehydrogenase (GAPDH) quantification. In addition, the total amount of mRNA produced by HLA-DQA1 and HLA-DRA1 expression was quantified for comparison. Subsequently, this approach was validated using Raji and HUT-78 cell lines and tested with peripheral mononuclear cells (PBMC) of 45 samples taken from healthy volunteers. The sensitivity was determined with > or = 10(2) copies. Comparison of the allele-specific DQA1 expression with the total expression of DQA1 and DRA1 mRNA indicated that DQA1*04 expression was increased compared with the expression of other alleles of the DQA1 gene. Thus, allele-specific quantification of DQA1 gene products could be achieved by real-time RT-PCR suitable for the analysis of differential expression of DQA1 mRNAs in homozygote and heterozygote combinations.

Regulation of class II expression in monocytic cells after HIV-1 infection

Human macrophage hybridoma cells were used to study HLA-DR expression after HIV-1 infection. HLA-DR surface expression was lost 2 wk after infection that was associated with decreased mRNA transcription. Transfecting HLA-DR-alpha and HLA-DR-beta cDNA driven by a nonphysiological CMV promoter restored expression, suggesting that regulatory DNA-binding proteins may be affected by HIV-1 infection. There was no protein binding to conserved class II DNA elements (W/Z/S box, X-1 and X-2 boxes, and Y box) in a HIV-1-infected human macrophage hybridoma cell line, 43(HIV), and in primary monocytes that lost HLA-DR expression after HIV-1(BaL) infection. PCR analysis of the HIV-1-infected cells that lost HLA-DR expression revealed mRNA for W/Z/S (RFX-5), X-1 (RFX-5), X-2 (hX-2BP), and one Y box DNA-binding protein (NF-YB), and CIITA, a non-DNA-binding protein necessary for class II transcription. There was no mRNA for the Y box-binding protein, NF-YA. However, HLA-DR expression could be restored by transfection with NF-YA driven by a CMV promoter, although HLA-DR failed to localize in either the late endosomes, lysosomes, or acidic compartments. This was associated with a loss of class II-associated invariant chain peptide and leupeptin-induced protein in the 43(HIV) cells. To address this further, non-HIV-1-infected 43 cells were infected with vaccinia virus containing HIV-1 gag, nef, pol, and env proteins. HLA-DR failed to localize in neither the late endosomes, lysosomes, or acidic compartments in the vaccinia-infected cells containing HIV-1 env protein. HIV-1 appears to have multiple effects on class II expression in monocytic cells that may contribute to the immune defects seen in HIV-1-infected patients.

Age-specific effects of juvenile rheumatoid arthritis-associated HLA alleles

OBJECTIVE

To define the onset and duration of effect of the HLA alleles that are associated with disease susceptibility and protection in juvenile rheumatoid arthritis (JRA) and 2 of its subtypes.

METHODS

We typed 680 patients with JRA and 254 ethnically matched unrelated controls for HLA class I and II genes. The frequency of each allele was calculated for each of the age-at-onset, onset type, and sex categories and plotted against the allele frequency in the control population. Survival analysis (with onset of disease as the terminating event) was used to calculate the age by which 50% (St0.5) and 80% (St0.2) of the children with particular alleles and combinations of alleles develop disease. This allele-specific survival analysis also allowed for the comparison of the overall survival functions for the various JRA subtype and sex categories.

RESULTS

Certain alleles are strongly associated with early susceptibility to pauciarticular JRA, including HLA-A2, DR8, DR5, and DPB1*0201. Fifty percent of the children carrying at least 1 of these alleles had disease onset prior to their third birthday. Among children who carried HLA-A2 and any 2 HLA-DR alleles (DR3, DR5, DR6, or DR8), the median age at the onset of pauciarticular disease was 2.7 years. Combinations of A2 and DPB1*0201 and one DR allele narrowed the window further to a median age at onset of 2.4 years. B27 and DR4 were associated with protection early in life but with increased risk later in childhood, with St0.5 values of 7.3 and 6.6 years, respectively, for pauciarticular JRA and St0.5 values of 10.2 and 10.7 years, respectively, for polyarticular JRA. Sex strongly influenced the age at which many of the alleles have their effect.

CONCLUSION

These data define at what age and for how long various HLA alleles influence susceptibility and protection (window-of-effect) in patients with JRA. In addition, these data establish more clearly the boundaries of ages-at-onset for 2 of the subtypes of the disease.

Nationwide collaborative study of HLA class II associations with distinct types of juvenile chronic arthritis (JCA) in Greece

The aim of this study was to investigate the association of different groups and subgroups of juvenile chronic arthritis (JCA) with HLA class II (DR, DP, DQ) alleles and/or haplotypes. Groups and subgroups were mainly distinguished on the basis of the type of onset, the course and complications of the disease, and some predefined disease markers according to the criteria proposed by the ILAR Standing Committee (Chile, 1994). On the basis of these criteria the following five JCA groups and their subgroups were included in the study: (1) define systemic onset (n = 25) and systemic progressing to persistent arthritis (n = 14); (2) JCA of oligoarthritis onset (O-JCA, n = 124) and of oligoarthritis onset and course (n = 98), O-JCA of early (< 6 years) or late (> 6 years) onset (EOO-JCA n = 71 and LOO-JCA n = 44), O-JCA with ANA positive (n = 69) or negative (n = 55) and O-JCA progressing to extended arthritis (n = 22); (3) JCA of polyarthritis onset (P-JCA) with rheumatic factor (RF) negative (n = 29), and P-JCA RF negative with antinuclear antibodies (ANA) positive (n = 13) or negative (n = 16); (4) JCA complicated with chronic anterior uveitis (CAU, n = 32); (5) juvenile psoriatic arthritis (n = 20). To assess the HLA allele frequencies in the above 223 Greek children with JCA, these frequencies were compared to those of 98 age-matched and 250 adult controls. The main findings were the following. A common HLA-DRB1* allele was not involved in the JCA groups and subgroups studied; on the other hand, the DQA1*0501 allele was found to be associated with different JCA groups/subgroups (O-JCA, P-JCA RF-negative ANA-positive, JCA with CAU), probably suggesting a closer relationship of this locus with the immunogenetic background of JCA. The DPB1*0201 allele was associated with the development of either EOO-JCA or CAU. Susceptibility to CAU was stronger when the DPB1*0201 was combined with the presence of DRB1*13. Another allele, DQB1*0301, was also associated with O-JCA and CAU. Finally, no specific HLA class II allele was found to be related to the presence of ANA or psoriatic lesions or to the severity of the arthritis. Our findings suggest that the wide clinical and laboratory spectrum of JCA is associated with an immunogenetic background that is linked with HLA alleles of more than one locus. Some of them, such as the DPB1*0201 allele, confer susceptibility to certain clinical onsets and courses or complications of the disease. The rapidly advancing techniques of typing of DNA profiles may lead to more definite conclusions.

Different binding of NF-Y transcriptional factor to DQA1 promoter variants

Polymorphism in the HLA-DQA1 promoter (QAP) sequences could influence the gene expression through a differential binding of transcriptional factors. Considering the main role played by the Y-box in the transcription, we focused on the QAP4 variants differing for a G vs A transition from the QAP Y-box consensus sequence. Electrophoretic Mobility Shift Assay using the two Y-box sequences was performed to determine whether this mutation could be reflected in an allele-specific binding of transcriptional factors. Indeed, the NF-Y specific band, recognised by supershift experiments, was clearly observed using the Y-box consensus probe but it was barely detectable with the QAP4 one. On the contrary, two other complexes were found to more strongly interact with QAP4 Y-box in comparison to the consensus sequence. The analysis of a selected panel of HLA homozygous lymphoblastoid cell lines by competitive RT-PCR and by Northern blotting revealed that the DQA1 *0401, *0501,*0601 alleles regulated by the QAP4 promoters were less expressed at the mRNA level than the DQA1* 0201 allele regulated by the QAP2.1 variant. In conclusion, these results show an evident reduction of NF-Y binding to the mutated QAP4 Y-box and a decreased mRNA accumulation of the DQA1 alleles regulated by these variants.

Juvenile arthritis: genetic update

Juvenile arthritis (JA) is a term that covers a number of different disease entities, of which only three present with significant Human Leukocyte Antigen (HLA) associations. (1) Pauciarticular JA with late onset and a strong male proponderance is associated with HLA-B27 and represents the group of juvenile spondyloarthropathies related to adult ankylosing spondylitis. (2) Early onset pauciarticular JA with a preponderance of females and a frequent occurance of chronic iridocyclitis and the frequent presence of anti-nuclear antibodies is associated with alleles from three different regions of the HLA system: HLA-A2, which shows a very strong correlation with early age of onset; DR8, DR11 and DR12 as well as DQA1*0401, *0501, *0601 and finally DPB1*0201. These alleles show no linkage disequilibrium in the control population. (3) Rheumatoid factor positive polyarticular JA is associated, as is adult rheumatoid arthritis, with DR4. Concerning the possible mechanisms of the immunopathogenesis, it is speculated that the normal function of HLA molecules, namely the presentation of antigenic peptides, plays a major role. Data collected on HLA associations in early onset pauciarticular JA have been interpreted as indicating that alleles of the DQA1 locus (*0401, *0501, *0601) are probably responsible for presenting the hypothetical arthritogenic peptides. It is speculated that the pathogenic process includes the presentation of HLA-A2 or HLA-DPB1*0201 derived peptides presented by DQ molecules. It is clearly stated that typing for HLA alleles has very little or no importance for clinical diagnosis and prognosis.

A tumor necrosis factor-alpha (TNF-alpha) promoter polymorphism is associated with chronic hepatitis B infection

Cytokines such as TNF-alpha and interferon gamma (IFN-gamma) are important for the elimination of infected hepatocytes during acute hepatitis B virus (HBV) infection. Two G versus A transitions in the TNF-alpha promoter region at positions -308 and -238 possibly influence TNF-alpha expression. We investigated these TNF-alpha polymorphisms in 71 patients with chronic HBV infection, in 32 subjects that had spontaneously recovered from acute HBV infection, and in 99 healthy controls. The -238 A promoter variant was present in 18 (25%) of 71 patients with chronic HBV infection compared with two (6%) of 32 subjects with acute infection (P<0.04), and seven (7%) of 99 controls (P<0.003). By contrast, the prevalence of the variant at position -308 was similar in all investigated groups. The observed differences could not be explained by linkage disequilibrium to HLA-B or -DRB1* alleles. These findings suggest an association between the TNF-alpha promoter polymorphism at position -238 and the development of chronic HBV infection. This promoter variant appears to be linked to defective viral clearance.

Tumor necrosis factor alpha promoter polymorphism at position -238 is associated with chronic active hepatitis C infection

Tumor necrosis factor alpha (TNF-alpha) is involved in the pathogenesis of chronic hepatitis C virus infection. The gene for TNF-alpha is encoded in the major histocompatibility locus (MHC). Two polymorphisms at positions -308 and -238 in the TNF-alpha promoter region might influence TNF-alpha expression. These promoter polymorphisms have been linked previously to a number of infectious diseases. TNF-alpha promoter polymorphisms at positions -238 and -308 were studied by DNA sequencing and sequence-specific oligonucleotide hybridization in 82 individuals with chronic hepatitis C and 99 control subjects. Subjects had been HLA class I and class II typed in a previous study. The frequency of the TNF238.2 promoter allele was significantly higher in the hepatitis C group (18.7%) compared to the controls (3.5%; P < 0.0001; pcorr < 0.009). No significant differences in the frequency of the TNF308.2 allele were observed between patients and controls. The increased frequency of the TNF238.2 allele could not be explained by linkage disequilibrium to HLA-B or -DR genes. These findings show an association between the TNF238.2 promoter variant and chronic active hepatitis C. They suggest that this polymorphism or a linked gene may be a host factor contributing to the development of chronic active hepatitis C.

A TNF-alpha promoter polymorphism is associated with juvenile onset psoriasis and psoriatic arthritis

Tumor necrosis factor-alpha is considered to be one of the important mediators in the pathogenesis of psoriasis. A strong association of juvenile onset psoriasis with the major histocompatibility complex encoded HLA-Cw6 antigen has been reported but it is unclear whether Cw6 itself or a closely linked gene is involved in the pathogenesis. This study has focused on the association of promoter polymorphisms of the major histocompatibility complex encoded tumor necrosis factor-alpha gene with psoriasis and psoriatic arthritis. Tumor necrosis factor-alpha promoter polymorphisms were sought by sequence-specific oligonucleotide hybridization and by direct sequencing in Caucasian patients with juvenile onset psoriasis and with psoriatic arthritis and in healthy controls. A mutation at position -238 of the tumor necrosis factor-alpha promoter was present in 23 of 60 patients (38%; p < 0.0001; p[corr] < 0.008) with juvenile onset psoriasis and in 20 of 62 patients (32%; p < 0.0003; p[corr] < 0.03) with psoriatic arthritis, compared with seven of 99 (7%) Caucasian controls. There was a marked increase of homozygotes for this mutation in the psoriasis group. Another mutation at position -308 was found in similar proportions of patients and controls. Our study shows a strong association of the tumor necrosis factor-alpha promoter polymorphism at position -238 with psoriasis and psoriatic arthritis. Our findings suggest that this promoter polymorphism itself or a gene in linkage disequilibrium with tumor necrosis factor-alpha predispose to the development of psoriasis.

DQB1 promoter sequence variability and linkage in caucasoids

Sequence variability in the upstream regulatory regions (URR) of HLA class II genes has been described as an additional mechanism of diversity in these polymorphic genes. For HLA-DQB1, 12 URR variants have been identified previously by sequence analysis of approx. 600 bp located immediately upstream of the first exon of the DQB1 gene. To investigate the distribution of these promoter alleles and their linkage with the structural portion of the DQB1 gene, a population-based study was carried out. Sequence information was utilized to develop 25 sequence-specific oligonucleotide probes to analyze enzymatically amplified locus-specific DNA. Supplemented with one sequence-specific primer pair to differentiate QBP1-6.2 from -6.3, all known 12 QBP1 alleles could be identified. Subsequently, 215 healthy, unrelated German controls were investigated for the distribution and linkage of DQB1 and QBP1 alleles. A total of 10 out of 12 known QBP1 alleles were observed. Since there was tight linkage between the promoter region and exon 2 of DQB1, the phenotype and genotype frequencies of the promoter alleles corresponded by and large to the frequencies observed for their linked DQB1 alleles. Exceptions were mainly seen for DQ5 and DQ6 haplotypes, as single DQB1 alleles could be linked to different, however, closely related QBP1 alleles and vice versa. Interestingly, for each DQB1 allele a single DQB1/QBP1 haplotype dominated (75.9 to 96.4%) the distribution. It is concluded that promoter and coding region variability are tightly linked by linkage disequilibrium. Exceptions are restricted to DQB1 DQ5 and DQ6 haplotypes. Since functional differences between different QBP1 alleles exist, the maintenance of haplotypic integrity may be of functional importance.

Immunoprinting excludes many potential susceptibility genes as predisposing to early onset pauciarticular juvenile chronic arthritis except HLA class II and TNF

DNA profiles (immunoprints) were generated for 120 patients suffering from early onset pauciarticular chronic arthritis (EOPA-JCA) and > 500 healthy controls utilizing highly polymorphic microsatellites in the vicinity of immunorelevant genes. Six T cell receptor (TCR) markers for the CD3D, TCRDVAJ, TEA, TCRBV6S1, BV6S3, BV6S7 and BV13S2 genes were analysed. Furthermore markers for the cell surface molecule CD40L, for cytokine genes (IL-1A, IL-2, IFN-alpha, FGF-alpha, TNF-alpha), the chromosomal region of the IRF2 and the cytokine receptor gene IL5RA were studied as well as two polymorphisms within the promotor region of the TNF-alpha gene. Coding region polymorphisms were evidenced indirectly by repeat length variation or they were predicted from the microsatellite distribution profiles and then confirmed by direct sequence analysis. Statistical evaluations were performed with respect to known predispositions, predominance of females (> 80%) and HLA-DR and -DQ haplotypes. Cell surface molecules (TCR, CD40L, IL5RA) as well as almost all cytokines (IL-1A, IFN alpha, FGFA, IRF2 region) were excluded as predisposing in our JCA panel. The TNF-alpha microsatellite alleles (GT)10-12 contribute considerably to manifestation of the disease, in HLA-DRB1*11(12) individuals (RR = 12.8). The TNF-alpha allele is not found in linkage disequilibrium with HLA-DRB1*11(12) and may be present on either chromosome 6. Thus, a novel susceptibility factor probably within the TNFA/TNFB gene region has been identified via linkage with the TNF-alpha microsatellite allele. Apparently complex compositions of the genetic background rather than single genes provide the precondition for manifestation of the autoimmune disease EOPA-JCA. Immunoprinting unravels the variability of the immunological genome via the semi-directed microsatellite approach efficiently.