The gut microbiome and HLA-B27-associated anterior uveitis: a case-control study.

BACKGROUND: The human gut microbiome (GM) is involved in inflammation and immune response regulation. Dysbiosis, an imbalance in this ecosystem, facilitates pathogenic invasion, disrupts immune equilibrium, and potentially triggers diseases including various human leucocyte antigen (HLA)-B27-associated autoinflammatory and autoimmune diseases such as inflammatory bowel disease (IBD) and spondyloarthropathy (SpA). This study assesses compositional and functional alterations of the GM in patients with HLA-B27-associated non-infectious anterior uveitis (AU) compared to healthy controls. METHODS: The gut metagenomes of 20 patients with HLA-B27-associated non-infectious AU, 21 age- and sex-matched HLA-B27-negative controls, and 6 HLA-B27-positive healthy controls without a history of AU were sequenced using the Illumina NovaSeq 6000 platform for whole metagenome shotgun sequencing. To identify taxonomic and functional features with significantly different relative abundances between groups and to identify associations with clinical metadata, the multivariate association by linear models (MaAsLin) R package was applied. RESULTS: Significantly higher levels of the Eubacterium ramulus species were found in HLA-B27-negative controls (p = 0.0085, Mann-Whitney U-test). No significant differences in microbial composition were observed at all other taxonomic levels. Functionally, the lipid IVA biosynthesis pathway was upregulated in patients (p < 0.0001, Mann-Whitney U-test). A subgroup analysis comparing patients with an active non-infectious AU to their age- and sex-matched HLA-B27-negative controls, showed an increase of the species Phocaeicola vulgatus in active AU (p = 0.0530, Mann-Whitney U-test). An additional analysis comparing AU patients to age- and sex-matched HLA-B27-positive controls, showed an increase of the species Bacteroides caccae in controls (p = 0.0022, Mann-Whitney U-test). CONCLUSION: In our cohort, non-infectious AU development is associated with compositional and functional alterations of the GM. Further research is needed to assess the causality of these associations, offering potentially novel therapeutic strategies.

Serum biomarkers and their relationship to axial spondyloarthritis associated with inflammatory bowel diseases.

Spondyloarthritis (SpA) constitute a group of chronic inflammatory immune-mediated rheumatic diseases characterized by genetic, clinical, and radiological features. Recent efforts have concentrated on identifying biomarkers linked to axial SpA associated with inflammatory bowel disease (IBD), offering predictive insights into disease onset, activity, and progression. Genetically, the significance of the HLA-B27 antigen is notably diminished in ankylosing spondylitis (AS) associated with IBD, but is heightened in concurrent sacroiliitis. Similarly, certain polymorphisms of endoplasmic reticulum aminopeptidase (ERAP-1) appear to be involved. Carriage of variant NOD2/CARD15 polymorphisms has been demonstrated to correlate with the risk of subclinical intestinal inflammation in AS. Biomarkers indicative of pro-inflammatory activity, including C-reactive protein (CRP) along with erythrocyte sedimentation rate (ESR), are among the consistent predictive biomarkers of disease progression. Nevertheless, these markers are not without limitations and exhibit relatively low sensitivity. Other promising markers encompass IL-6, serum calprotectin (s-CLP), serum amyloid (SAA), as well as biomarkers regulating bone formation such as metalloproteinase-3 (MMP-3) and Dickkopf-related protein 1 (DKK-1). Additional candidate indicators of structural changes in SpA patients include matrix metalloproteinase-3 (MMP-3), vascular endothelial growth factor (VEGF), tenascin C (TNC), and CD74 IgG. Fecal caprotein (f-CLP) levels over long-term follow-up of AS patients have demonstrated predictive value in anticipating the development of IBD. Serologic antibodies characteristic of IBD (ASCA, ANCA) have also been compared; however, results exhibit variability. In this review, we will focus on biomarkers associated with both axial SpA and idiopathic intestinal inflammation, notably enteropathic spondyloarthritis.

Intraocular dendritic cells characterize HLA-B27-associated acute anterior uveitis.

Uveitis describes a heterogeneous group of inflammatory eye diseases characterized by infiltration of leukocytes into the uveal tissues. Uveitis associated with the HLA haplotype B27 (HLA-B27) is a common subtype of uveitis and a prototypical ocular immune-mediated disease. Local immune mechanisms driving human uveitis are poorly characterized mainly due to the limited available biomaterial and subsequent technical limitations. Here, we provide the first high-resolution characterization of intraocular leukocytes in HLA-B27-positive (n = 4) and -negative (n = 2) anterior uveitis and an infectious endophthalmitis control (n = 1) by combining single-cell RNA-sequencing with flow cytometry and protein analysis. Ocular cell infiltrates consisted primarily of lymphocytes in both subtypes of uveitis and of myeloid cells in infectious endophthalmitis. HLA-B27-positive uveitis exclusively featured a plasmacytoid and classical dendritic cell (cDC) infiltrate. Moreover, cDCs were central in predicted local cell-cell communication. This suggests a unique pattern of ocular leukocyte infiltration in HLA-B27-positive uveitis with relevance to DCs.

Uveitis is a form of inflammation in the eye. It can occur in response to infection, or when the immune system mistakenly attacks the eye, in what is known as autoimmune uveitis. In approximately 80 percent of cases, the front part of the eye is affected. During an inflammatory episode, the liquid inside the front part of the eye fills with immune cells, but the nature of these cells remains unknown. This is because uveitis is rare, and doctors cannot routinely take samples from inside the eyes of affected individuals to diagnose the disease. This lack of samples makes research into this disease challenging. There are two main groups of immune cells that could be responsible for uveitis: myeloid cells and lymphoid cells. Myeloid cells form the first line of immune defense against infection by non-specifically attacking and removing pathogens . Lymphoid cells form the second line of immune defense, attacking specific pathogens. Lymphoid cells also have long-term memory, meaning they can 'remember' previous infections and fight them more effectively. Lymphoid cells receive instructions from a type of myeloid cell called a dendritic cell about what to attack. Dendritic cells relay their instructions to lymphoid cells using molecules called human leukocyte antigens (HLA). Autoimmune uveitis affecting the front part of the eye is common in individuals with an HLA type called HLA-B27, suggesting that communication between dendritic and lymphoid cells plays an important role in this type of inflammation. To make the most of limited patient samples, Kasper et al. used single cell techniques to examine the immune cells from the fluid inside the eye. Six samples came from people with autoimmune uveitis, and one from a person with an eye infection. The infection sample contained mainly myeloid cells that might attack bacteria responsible for the infection. In contrast, the autoimmune uveitis samples contained mainly lymphoid cells. Of these samples, four were from individuals with the gene that codes for the HLA-B27 molecule. These samples had a unique pattern of immune cells, with more dendritic cells than the samples from individuals that did not have this gene. This study included only a small number of individuals, but it shows that analysing single immune cells from the eye is possible in uveitis. This snapshot could help researchers understand the local immune response in the eye, and find an optimal treatment.

Reactive arthritis and undifferentiated peripheral spondyloarthritis share human leucocyte antigen B27 subtypes and serum and synovial fluid cytokine profiles.

OBJECTIVES: Peripheral SpA (pSpA) is comprised of ReA, PsA, enteritis-associated arthritis and undifferentiated pSpA (upSpA). ReA and upSpA share T cell oligotypes and metabolomics in serum and SF. We investigated HLA-B27 subtypes and cytokines in serum and SF that were compared between ReA and upSpA. METHODS: ReA and upSpA were compared in two cohorts. In cohort I (44 ReA and 56 upSpA), HLA-B27 subtyping was carried out. In cohort II (17 ReA and 21 upSpA), serum and SF cytokines were compared using a multiplex cytokine bead assay (27 cytokines). A total of 28 healthy controls with similar age and sex to cohort II were included for comparison of serum cytokine levels. RESULTS: In cohort I, HLA-B27 was positive in 81.8% (36/44) of ReA and 85.71% (48/56) of upSpA patients. HLA-B27 typing was successful in 70 patients (30 ReA and 40 uSpA). HLA-B*2705 was the most common, followed by HLA-B*2704 and HLA-B*2707. Frequencies were the same between ReA and upSpA. In cohort II, 14 cytokines were detectable in the serum of patients. The levels of eight cytokines were higher than in the controls. The cytokine levels of ReA and upSpA were similar. Sixteen cytokines were detectable in the SF of patients. There was no statistical difference in the levels between ReA and upSpA. The cytokine profiles in sera and SF were also similar among HLA-B27-positive and negative patients. CONCLUSION: ReA and upSpA have similar HLA-B27 subtype associations and similar cytokine profiles. They should be considered as a single entity during studies as well as clinical management.

HLA-B27 is associated with reduced disease activity in axial spondyloarthritis.

HLA-B27 is associated with increased susceptibility and disease activity of ankylosing spondylitis, but the effect of HLA-B27 on the activity of the broader category now called axial spondyloarthritis (AxSpA) is apparently the opposite. A modified Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) was used to assess disease activity among 3435 patients with spondyloarthritis (SpA) who participated in a survey designed to assess the effect of their disease and its treatment on the susceptibility and severity of Covid-19. Chi square testing was used to compare BASDAI scores between HLA-B27 positive and negative subjects. 2836 survey respondents were HLA B27 positive. The average BASDAI for the HLA-B27 negative cohort was 4.92 compared to 4.34 for the HLA-B27 positive subjects. Based on linear regression, a subject's sex could not fully account for the differing BASDAI score in HLA-B27 negative subjects compared to those who are HLA-B27 positive. The difference between B27 positive and negative subjects was skewed by those with a BASDAI score of one or two. HLA-B27 positive subjects were more than twice as likely to have a BASDAI score of 1 compared to HLA B27 negative subjects and about 60% more likely to have a BASDAI score of 2 (p < 0.0001). HLA-B27 positive subjects have less active spondyloarthritis compared to HLA-B27 negative subjects as measured by a BASDAI score. Our data indicate that patients with mild back pain and a diagnosis of AxSpA are disproportionately HLA-B27 positive. The HLA-B27 test facilitates the diagnosis of axial spondyloarthritis such that patients from a community survey with mild back pain may be disproportionately diagnosed as having AxSpA if they are HLA-B27 positive. The test result likely introduces a cognitive bias into medical decision making and could explain our observations.

Classification Criteria for Spondyloarthritis/HLA-B27-Associated Anterior Uveitis.

PURPOSE: The purpose of this study was to determine classification criteria for spondyloarthritis/HLA-B27-associated anterior uveitis DESIGN: Machine learning of cases with spondyloarthritis/HLA-B27-associated anterior uveitis and 8 other anterior uveitides. METHODS: Cases of anterior uveitides were collected in an informatics-designed preliminary database, and a final database was constructed of cases achieving supermajority agreement on the diagnosis, using formal consensus techniques. Cases were split into a training set and a validation set. Machine learning using multinomial logistic regression was used in the training set to determine a parsimonious set of criteria that minimized the misclassification rate among the anterior uveitides. The resulting criteria were evaluated in the validation set. RESULTS: A total of 1,083 cases of anterior uveitides, including 184 cases of spondyloarthritis/HLA-B27-associated anterior uveitis, were evaluated by machine learning. The overall accuracy for anterior uveitides was 97.5% in the training set and 96.7% in the validation set (95% CI: 92.4-98.6). Key criteria for spondyloarthritis/HLA-B27-associated anterior uveitis included 1) acute or recurrent acute unilateral or unilateral alternating anterior uveitis with either spondyloarthritis or a positive test result for HLA-B27; or 2) chronic anterior uveitis with a history of the classic course and either spondyloarthritis or HLA-B27; or 3) anterior uveitis with both spondyloarthritis and HLA-B27. The misclassification rates for spondyloarthritis/HLA-B27-associated anterior uveitis were 0% in the training set and 3.6% in the validation set. CONCLUSIONS: The criteria for spondyloarthritis/HLA-B27-associated anterior uveitis had a low misclassification rate and appeared to perform well enough for use in clinical and translational research.

Spondyloarthritis and the Human Leukocyte Antigen (HLA)-B*27 Connection.

Heritability of Spondyloarthritis (SpA) is highlighted by several familial studies and a high association with the presence of human leukocyte antigen (HLA)-B*27. Though it has been over four decades since the association of HLA-B*27 with SpA was first determined, the pathophysiological roles played by specific HLA-B*27 allotypes are not fully understood. Popular hypotheses include the presentation of arthritogenic peptides, triggering of endoplasmic reticulum (ER) stress by misfolded HLA-B*27, and the interaction between free heavy chains or heavy chain homodimers of HLA-B*27 and immune receptors to drive IL-17 responses. Several non-HLA susceptibility loci have also been identified for SpA, including endoplasmic reticulum aminopeptidases (ERAP) and those related to the IL-23/IL-17 axes. In this review, we summarize clinical aspects of SpA including known characteristics of gut inflammation, enthesitis and new bone formation and the existing models for understanding the association of HLA-B*27 with disease pathogenesis. We also examine newer insights into the biology of HLA class I (HLA-I) proteins and their implications for expanding our understanding of HLA-B*27 contributions to SpA pathogenesis.

Perspectives on the Genetic Associations of Ankylosing Spondylitis.

Ankylosing spondylitis (AS) is a common form of inflammatory spinal arthritis with a complex polygenic aetiology. Genome-wide association studies have identified more than 100 loci, including some involved in antigen presentation (HLA-B27, ERAP1, and ERAP2), some in Th17 responses (IL6R, IL23R, TYK2, and STAT3), and others in macrophages and T-cells (IL7R, CSF2, RUNX3, and GPR65). Such observations have already helped identify potential new therapies targeting IL-17 and GM-CSF. Most AS genetic associations are not in protein-coding sequences but lie in intergenic regions where their direct relationship to particular genes is difficult to assess. They most likely reflect functional polymorphisms concerned with cell type-specific regulation of gene expression. Clarifying the nature of these associations should help to understand the pathogenic pathways involved in AS better and suggest potential cellular and molecular targets for drug therapy. However, even identifying the precise mechanisms behind the extremely strong HLA-B27 association with AS has so far proved elusive. Polygenic risk scores (using all the known genetic associations with AS) can be effective for the diagnosis of AS, particularly where there is a relatively high pre-test probability of AS. Genetic prediction of disease outcomes and response to biologics is not currently practicable.

Differences in Cellular Clearing Mechanisms of Aggregates of Two Subtypes of HLA-B27.

Ankylosing spondylitis (AS) belongs to a group of diseases, called spondyloarthropathies (SpA), that are strongly associated with the genetic marker HLA-B27. AS is characterized by inflammation of joints and primarily affects the spine. Over 160 subtypes of HLA-B27 are known, owing to high polymorphism. Some are strongly associated with disease (e.g., B*2704), whereas others are not (e.g., B*2709). Misfolding of HLA-B27 molecules [as dimers, or as high-molecular-weight (HMW) oligomers] is one of several hypotheses proposed to explain the link between HLA-B27 and AS. Our group has previously established the existence of HMW species of HLA-B27 in AS patients. Still, very little is known about the mechanisms underlying differences in pathogenic outcomes of different HLA-B27 subtypes. We conducted a proteomics-based evaluation of the differential disease association of HLA B*2704 and B*2709, using stable transfectants of genes encoding the two proteins. A clear difference was observed in protein clearance mechanisms: whereas unfolded protein response (UPR), autophagy, and aggresomes were involved in the degradation of B*2704, the endosome-lysosome machinery was primarily involved in B*2709 degradation. These differences offer insights into the differential disease association of B*2704 and B*2709.

Use of Anti-Tumour Necrosis Factor-Alpha Agents in the Management of HLA-B-27-Associated Uveitis: The First Case Series from India.

Purpose: The aim of this study was to evaluate the efficacy of adalimumab (ADL) and golimumab (GLM) in patients with HLA-B-27-associated uveitis.Method: We conducted a retrospective analysis of patients with HLA-B-27-associated uveitis who had received subcutaneous GLM and ADL between 2014 and 2018.Results: The study included 14 patients, 12 of whom received subcutaneous ADL and two patients were treated with subcutaneous GLM. Median age of the patients was 31.5 years (range 17-53 years). The most common associated systemic disease in these patients was ankylosing spondylitis (92.8%). Majority of the patients had anterior uveitis (71.4%) followed by anterior uveitis and intermediate uveitis (28.6%).Conclusion: ADL/GLM is a useful therapeutic option in refractory cases of HLA-B-27-associated uveitis, especially in patients with associated systemic manifestations.

Preliminary Report on Interleukin-22, GM-CSF, and IL-17F in the Pathogenesis of Acute Anterior Uveitis.

Purpose:Anterior uveitis is the most common anatomic subset of uveitis. We developed a novel multi-parametric flow cytometry panel to identify immune dysregulation signatures in HLA B27-associated acute anterior uveitis (AAU) and axial spondyloarthritis (AxSpA).Methods: We used fluorescence activated cell sorting to characterize T cell cytokine expression in stimulated T cell subsets from patients with AAU (n = 4) compared to healthy controls (n = 14) or subjects with AxSpA (n = 6).Results: Positive findings among subjects with AAU included a statistically significant increase in stimulated granulocyte-macrophage colony stimulating factor (GM-CSF), IL-17, and IL-22 synthesized by CD8 cells, a trend for stimulated ILC (innate lymphoid cells)-3 cells to synthesize more IL-22 (p = .07), and stimulated MAIT (mucosa associated innate lymphoid cells)-like cells that express the T cell receptor V alpha 7.2 to express IL-17A, IL-17F, and IL-22 in a greater percentage of cells relative to controls. IL-17F, GM- CSF, and IL-22 represent potentially novel targets in AAU.Conclusion: Our report is arguably the first to implicate IL-17F or ILC-3 and MAIT cells in the pathogenesis of AAU.Abbreviations AAU: acute anterior uveitis; AxSpA: axial spondyloarthritis; BASDAI: Bath ankylosing spondylitis disease activity index; CCR: chemokine receptor; DMSO: dimethylsulfoxide; EULAR:European League Against Rheumatism; FACS: fluorescence activated cell sorter; FBS: fetal bovine serum; FSC: orward light scatter; GM-CSF: granulocyte-macrophage colony stimulating factor; HC: healthy control; ILC: innate lymphoid cell; KIR: killer immunoglobulin receptor; MAIT: mucosal associated immune T cell; ND: not detected; NK: natural killer cell; OHSU-Oregon Health & Science University; PBMC: peripheral blood mononuclear cell; SSC: side light scatter; TCR: T cell receptor.

Tear IL-6 and IL-10 levels in HLA-B27-Associated Uveitis and Its clinical Implications.

Purpose: To evaluate the cytokine levels in tear samples of human leukocyte antigen B27 (HLA-B27)-associated uveitis.Methods: Twenty HLA-B27-associated uveitis patients and 10 non-HLA-B27 uveitis controls were enrolled for the estimation of interleukin-6 (IL-6) and IL-10 levels in the tear samples. The cytokine levels were determined by flow cytometry using a bead-based assay.Results: IL-6, and IL-10 levels and IL-6/IL-10 ratio were found to be higher in the tear samples of HLA-B27-associated uveitis patients as compared to controls. IL-6 levels were also elevated in the active disease as compared to the quiescent group; likewise, IL-6 levels were higher even in the quiescent phase in comparison to non-HLA-B27 disease control. Additionally, levels of IL-6 were significantly correlated with multiple disease episodes. Moreover, IL-6 showed a good area under the curve in receiver operating characteristic analysis.Conclusions: Elevated tear IL-6 levels were associated with active disease and multiple disease episodes and thus could be used as putative markers for disease episodes.

Diagnostic value of anti-CD74 antibodies in early and late axial spondyloarthritis and its relationship to disease activity.

OBJECTIVES: This study was designed to evaluate the role of anti-CD74 antibodies in diagnosis of axial spondyloarthritis (axSpA) and their relationship to disease duration and disease activity. METHODS: Fifty patients with axSpA, 15 patients with RA and 15 healthy subjects were included in the study. Clinical examination and laboratory tests were done. The ESR, CRP level and ASDAS were measured as markers of the disease activity. Quantitative determination of human CD74 IgG antibodies was done. RESULTS: The mean age of the patients was 38.22 (S.D.12.20) years. The level of CD74 autoantibodies was significantly higher in axSpA in comparison to control groups. Most patients with positive articular and extra-articular manifestations were positive for CD74 autoantibodies. In patients with inactive disease, 33.3% were positive for CD74 autoantibodies, as were 83% with active disease. High percentages of patients with early and late axSPA were CD74 autoantibody positive. The majority of patients with positive disease activity in early and late axSpA were CD74 autoantibody positive. CD74 autoantibodies had 80% sensitivity vs both control groups with 87% specificity vs the healthy control group and 80% vs the RA control group in the diagnosis of axSpA. CONCLUSIONS: The frequency of positive anti-CD74 IgG antibodies was as high in patients with early axSpA as in those with late axSpA, with no significant differences. There was a significant difference in the frequency of positive anti-CD74 IgG antibodies between patients with positive and negative disease activity. Based on the sensitivity and specificity of anti-CD74 IgG, this is a promising diagnostic tool to support the clinical diagnosis of axSpA.

Juvenile Spondyloarthritis in the Childhood Arthritis and Rheumatology Research Alliance Registry: High Biologic Use, Low Prevalence of HLA-B27, and Equal Sex Representation in Sacroiliitis.

OBJECTIVE: To describe characteristics of children with enthesitis-related arthritis (ERA) and juvenile psoriatic arthritis (PsA) who were enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) registry. METHODS: All children with ERA and those with juvenile PsA were identified. Demographic characteristics, clinical characteristics, and treatments were described. The children with sacroiliitis and those without sacroiliitis were compared. In the children with sacroiliitis, the first visit with clinically active sacroiliitis (which came first in 72% of cases) was compared to the first visit without clinically active sacroiliitis. RESULTS: A total of 902 children with ERA or juvenile PsA were identified. Children with ERA were older at diagnosis (ages 10.8 years versus 8.2 years; P < 0.01) and were more likely to be male (56% versus 38%; P < 0.01). Polyarticular involvement was reported in 57% of children with ERA and in 72% of those with juvenile PsA. Of the children tested, HLA-B27 was positive in 38% of those in the ERA group and in 12% of those in the juvenile PsA group. At least 1 biologic was taken by 72% of those with ERA and 64% of those with juvenile PsA. Sacroiliitis (diagnosed clinically and/or by imaging) was reported in 28% of the children (40% of those with ERA and 12% of those with juvenile PsA). Of these, 54% of the children were female, 36% were HLA-B27 positive, and 81% took at least 1 biologic. In children with sacroiliitis, scores according to the physician global assessment of disease activity, parent/patient global assessment of well-being, and clinical Juvenile Arthritis Disease Activity Score 10 were all significantly worse at the first visit with clinically active sacroiliitis versus the first visit without active sacroiliitis. CONCLUSION: In this registry, there are more than 900 children with ERA or juvenile PsA. There was high biologic use in this population, especially in those with sacroiliitis. Further, there was equal sex representation in those children with sacroiliitis.

Understanding the Pathogenesis of Spondyloarthritis.

Spondyloarthritis comprises a group of inflammatory diseases of the joints and spine, with various clinical manifestations. The group includes ankylosing spondylitis, reactive arthritis, psoriatic arthritis, arthritis associated with inflammatory bowel disease, and undifferentiated spondyloarthritis. The exact etiology and pathogenesis of spondyloarthritis are still unknown, but five hypotheses explaining the pathogenesis exist. These hypotheses suggest that spondyloarthritis is caused by arthritogenic peptides, an unfolded protein response, HLA-B*27 homodimer formation, malfunctioning endoplasmic reticulum aminopeptidases, and, last but not least, gut inflammation and dysbiosis. Here we discuss the five hypotheses and the evidence supporting each. In all of these hypotheses, HLA-B*27 plays a central role. It is likely that a combination of these hypotheses, with HLA-B*27 taking center stage, will eventually explain the development of spondyloarthritis in predisposed individuals.

Association of ERAP2 polymorphisms in Colombian HLA-B27+ or HLA-B15+ patients with SpA and its relationship with clinical presentation: axial or peripheral predominance.

OBJECTIVE: To determine the association between endoplasmic reticulum aminopeptidase (ERAP)1 and ERAP2 single-nucleotide polymorphisms (SNPs) and human leukocyte antigens (HLA)-B27+ or HLA-B15+ patients with spondyloarthritis (SpA). METHODS: 104 patients with SpA according to Assessment of Spondyloarthritis International Society criteria were included in the study. HLA typing was performed by PCR. The polymorphisms were determined by real-time PCR on genomic DNA using customised probes for SNPs rs27044, rs17482078, rs10050860 and rs30187 in ERAP1, and rs2910686, rs2248374 and rs2549782 in ERAP2. RESULTS: 70 of the104 patients with SpA were HLA-B27+ and 34 were HLA-B15+. The distribution of ERAP1 and ERAP2 SNPs between the HLA-B15+ and HLA-B27+ patients with SpA did not reveal differences. Likewise, no differences in the frequencies of ERAP1 SNP haplotypes and alleles HLA-B15 or HLA-B27 were found. Interestingly, however, the frequencies of three particular haplotypes formed by ERAP2 SNPs rs2549782/rs2248374/rs2910686 varied between HLA-B15+ and HLA-B27+ patients: the ERAP2 SNPs haplotype TGT was more common in HLA-B15+ patients with SpA (OR 2.943, 95% CI 1.264 to 6.585; P=0.009), whereas the ERAP2 SNP haplotypes TGC and CAT were more associated with HLA-B27+ patients with SpA: (OR 4.483, 95% CI 1.524 to 13.187; p=0.003) and (OR 9.014, 95% CI 1.181 to 68.807; p=0.009), respectively. CONCLUSION: An association was found between HLA-B15+ patients with SpA and haplotype TGT of ERAP2 SNPs. On the other hand, HLA-B27+ patients with SpA were associated with ERAP2 haplotypes TGC and CAT. These associations could be related to the clinical presentation of the disease, specifically with a peripheral or axial predominance, respectively.

Juvenile Spondyloarthritis: focus on uveitis.

BACKGROUND: Juvenile spondyloarthritis (JSpA) represents a group of inflammatory arthritides with several distinctive features (enthesitis, involvement of spine and sacroiliac joint, HLA-B27 association and development of uveitis). There are limited data on the course of uveitis in children with JSpA. This study aims to estimate the prevalence of uveitis and to look at the presence of HLA-B27 in relation to uveitis occurrence and ocular symptoms in a cohort of JSpA patients. FINDINGS: This is a cross sectional/retrospective study involving patients with JSpA followed in a tertiary referral hospital. Two hundred twenty-three patients were enrolled in the study. The prevalent diagnosis was enthesitis-related arthritis (ERA) (62%) followed by juvenile psoriatic arthritis (PsA), undifferentiated arthritis (UA), and the arthropathies associated with inflammatory bowel disease (IBD-A) (18, 14, 6%, respectively). Uveitis was reported in twenty-four patients (11%) of the JSpA cohort (JSpA-U). ERA patients had the highest uveitis prevalence (ERA-U) (13%) with similar prevalences in UA, PsA and in IBD-A (7% each). The prevalence of HLA-B27 positivity was similar amongst the entire JSpA-U cohort (N = 22, 45%) and those with ERA-U (N = 8, 44%). The overall prevalence of symptomatic uveitis was 79%. Neither the likelihood of uveitis, nor of symptomatic uveitis, varied by HLA-B27 status either in the entire cohort nor in those with ERA. CONCLUSIONS: About one-tenth of patients developed uveitis, the majority of which was symptomatic. Fewer than half of the patients with uveitis were HLA-B27 positive. HLA-B27 status was not statistically associated with either the development of uveitis or symptomaticity of uveitis.

A FcɣRIIa polymorphism has a HLA-B57 and HLA-B27 independent effect on HIV disease outcome.

Fcɣ receptors (FcɣRs) are key immune regulatory receptors that connect antibody-mediated immune responses to cellular effector functions. They are involved in the control of various immune functions including responses to infections. Genetic polymorphisms of FcɣRs coding genes (FCGR) have been associated with the regulation of HIV infection and progression. In this study, we analyzed the potential impact of five candidate FcɣR SNPs on viral control by genotyping 251 HIV controllers and 250 progressors. The rs10800309 AA genotype of the FcɣRIIa coding gene FCGR2A was found to be significantly associated with HIV control and this association was independent of HLA-B57 and HLA-B27 (OR, 2.84; 95% CI, 1.20-6.89; Pcor = 0.033). We further confirmed the functional role of this polymorphism by showing an association of this same AA genotype with an increased in vitro FcɣRII expression on myeloid cells including dendritic cells (P = 0.0032). Together, these results suggest that the AA genotype of rs10800309 confers an improved immune response through FcɣRII upregulation and that this polymorphism may serve as an additional predictive marker of HIV control.

HLA-B*27:05 alters immunodominance hierarchy of universal influenza-specific CD8+ T cells.

Seasonal influenza virus infections cause 290,000-650,000 deaths annually and severe morbidity in 3-5 million people. CD8+ T-cell responses towards virus-derived peptide/human leukocyte antigen (HLA) complexes provide the broadest cross-reactive immunity against human influenza viruses. Several universally-conserved CD8+ T-cell specificities that elicit prominent responses against human influenza A viruses (IAVs) have been identified. These include HLA-A*02:01-M158-66 (A2/M158), HLA-A*03:01-NP265-273, HLA-B*08:01-NP225-233, HLA-B*18:01-NP219-226, HLA-B*27:05-NP383-391 and HLA-B*57:01-NP199-207. The immunodominance hierarchies across these universal CD8+ T-cell epitopes were however unknown. Here, we probed immunodominance status of influenza-specific universal CD8+ T-cells in HLA-I heterozygote individuals expressing two or more universal HLAs for IAV. We found that while CD8+ T-cell responses directed towards A2/M158 were generally immunodominant, A2/M158+CD8+ T-cells were markedly diminished (subdominant) in HLA-A*02:01/B*27:05-expressing donors following ex vivo and in vitro analyses. A2/M158+CD8+ T-cells in non-HLA-B*27:05 individuals were immunodominant, contained optimal public TRBV19/TRAV27 TCRαß clonotypes and displayed highly polyfunctional and proliferative capacity, while A2/M158+CD8+ T cells in HLA-B*27:05-expressing donors were subdominant, with largely distinct TCRαß clonotypes and consequently markedly reduced avidity, proliferative and polyfunctional efficacy. Our data illustrate altered immunodominance patterns and immunodomination within human influenza-specific CD8+ T-cells. Accordingly, our work highlights the importance of understanding immunodominance hierarchies within individual donors across a spectrum of prominent virus-specific CD8+ T-cell specificities prior to designing T cell-directed vaccines and immunotherapies, for influenza and other infectious diseases.

MHC class I associations beyond HLA-B27: the peptide binding hypothesis of psoriatic arthritis and its implications for disease pathogenesis.

PURPOSE OF REVIEW: To provide an overview of the heterogeneous human leucocyte antigen (HLA) associations of psoriatic arthritis, their relationship to particular clinical features of the disease, and how a hypothesis of binding specific peptides could provide a unifying basis for this heterogeneity. RECENT FINDINGS: There have been substantive advances in understanding the role of HLA molecules in binding self-peptides that select our repertoire of T cells, the specific peptide-binding properties of these HLA allotypes, and their crystallographic structure. These advances provide a means to envision the significance of the heterogeneous psoriatic arthritis HLA associations. The clinical relevance of these allotypes if heightened by emerging knowledge of their relationship to particular clinical features of the disease that serve as subphenotypes. SUMMARY: We propose a peptide binding hypothesis of psoriatic arthritis based on a shared pattern of negative charge in the 'B' pocket of the HLA-B and HLA-C molecules encoded by the susceptibility allotypes. This hypothesis suggests that peptides characterized by the presence of arginine at position 2 or 3 are bound to the susceptibility allotypes and drive the T-cell clones selected on them to attack molecules containing these peptides located in sites of psoriatic arthritis inflammation.