Risk factors for serious infections and infection-related mortality in patients with microscopic polyangiitis: Multicentre REVEAL cohort study

OBJECTIVE

Infections are a critical concern for patients with microscopic polyangiitis (MPA). This study aimed to identify the risk factors associated with serious infections (SIs) and infection-related mortality in patients with MPA, as well as the effect of glucocorticoid (GC) dose tapering on these outcomes.

METHODS

This multicentre, retrospective, and observational study utilised data from a cohort of patients with MPA in Japan [Registry of Vasculitis Patients to Establish REAL World Evidence (REVEAL) cohort]. Patients were categorised based on the occurrence of SIs or infection-related deaths, and various characteristics were compared among the groups.

RESULTS

Among 182 patients, 66 (36.2%) experienced 129 SIs and 27 (14.8%) developed infection-related deaths. Advanced age, elevated C-reactive protein (CRP) levels, and higher ratio of the GC dose at 3 months to the initial dose were identified as independent risk factors for SIs. Older age was also associated with infection-related deaths. Furthermore, the cumulative incidence of infection-related deaths was significantly higher in patients with a higher ratio of the GC dose at 24 months to the initial dose.

CONCLUSION

Older age, elevated CRP levels, and slower GC dose tapering predispose patients to SIs and infection-related deaths. Strategies, such as rapid GC dose tapering, are anticipated to mitigate the risk of infections.

Avacopan's potential to decrease MPO-ANCA titres concurrent with ameliorated activity in ANCA-associated vasculitis

Avacopan, an orally administered C5a receptor antagonist, is effective in microscopic polyangiitis via the inhibition of neutrophil priming induced by C5a. However, the exact effect of avacopan on the production of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) is yet to be clearly established. This report presents a microscopic polyangiitis patient without major organ damage where high levels of MPO-ANCA persisted with high-dose steroid therapy and azathioprine, but the addition of avacopan led to a reduction in MPO-ANCA titres. The present case implies that avacopan-mediated inhibition of C5a may lead to a reduction in MPO-ANCA levels, thereby potentially ameliorating the pathophysiology of ANCA-associated vasculitis. Nevertheless, the impact of avacopan on MPO-ANCA production cannot be asserted solely based on this report; therefore, further examination is necessary through subgroup analysis using data from larger-scale studies.

Pathogenicity of IgG-Fc desialylation and its association with Th17 cells in an animal model of systemic lupus erythematosus

OBJECTIVES

Decreased sialylation of IgG-Fc glycans has been reported in autoimmune diseases, but its role in systemic lupus erythematosus (SLE) is not fully understood. In this study, we examined the pathogenicity of IgG desialylation and its association with Th17 in SLE using an animal model.

METHODS

B6SKG mice, which develop lupus-like systemic autoimmunity due to the ZAP70 mutation, were used to investigate the pathogenicity of IgG desialylation. The proportion of sialylated IgG was compared between B6SKG and wild-type mice with or without β-glucan treatment-induced Th17 expansion. Anti-interleukin (IL)-23 and anti-IL-17 antibodies were used to examine the role of Th17 cells in IgG glycosylation. Activation-induced cytidine deaminase-specific St6gal1 conditionally knockout (cKO) mice were generated to examine the direct effect of IgG desialylation.

RESULTS

The proportions of sialylated IgG were similar between B6SKG and wild-type mice in the steady state. However, IgG desialylation was observed after β-glucan-induced Th17 expansion, and nephropathy also worsened in B6SKG mice. Anti-IL-23/17 treatment suppressed IgG desialylation and nephropathy. Glomerular atrophy was observed in the cKO mice, suggesting that IgG desialylation is directly involved in disease exacerbation.

CONCLUSIONS

IgG desialylation contributes to the progression of nephropathy, which is ameliorated by blocking IL-17A or IL-23 in an SLE mouse model.

TAFRO syndrome is associated with anti-SSA/Ro60 antibodies, in contrast to idiopathic castleman disease

TAFRO syndrome is an acute systemic inflammatory disease characterized by thrombocytopenia, anasarca, fever, reticulin fibrosis/renal dysfunction, and organomegaly. There have been increasing reports that TAFRO is a disease distinct from idiopathic multicentric Castleman disease and that TAFRO patients may be positive for anti-SSA antibodies. To assess anti-SSA antibody positivity and the clinical characteristics of the two diseases, we retrospectively compared 7 TAFRO and 10 iMCD patients in our hospital. The mean age of onset of TAFRO and iMCD was 48.0 (interquartile range [IQR], 41-53) and 45.0 (IQR, 35-53) years, respectively. The TAFRO and iMCD groups had 6 (86%) and 4 (40%) male patients, respectively, and the following pretreatment laboratory values: platelet count, 3.8 (IQR, 2.2-6.4) and 35.5 (IQR, 22.2-42.8) × 104/μL, respectively; C-reactive protein, 10.2 (IQR, 6.8-21.4) and 9.5 (IQR, 6.2-13.6) mg/dL, respectively; IgG, 1431 (IQR, 1112-1815) and 4725 (IQR, 3755-5121) mg/dL, respectively. RNA immunoprecipitation (5 cases for anti-SSA) or protein array (5 cases for anti-SSA/Ro60) detected anti-SSA antibodies in six (86%) TAFRO patients but not in iMCD patients; it did not detect anti-SSB antibodies in any of the patients. None of the patients were diagnosed with Sjögren syndrome. All iMCD patients treated with tocilizumab (TCZ) responded well. Meanwhile, two of six TAFRO patients treated with TCZ showed inadequate responses; thus, both patients were switched to rituximab, following which they achieved remission. TAFRO and iMCD have different clinical features. TAFRO may be categorized as a severe phenotype of the anti-SSA antibody syndrome.

A case of atypical IgG4-related disease presenting hypereosinophilia, polyneuropathy, and liver dysfunction

Ig (immunoglobulin) G4-related disease (Ig4-RD) affects several organs, including salivary glands, lacrimal glands, pancreas, biliary ducts, and retroperitoneum. A 72-year-old woman was examined for hypereosinophilia, high levels of IgG4, polyneuropathy, liver dysfunction, enlargement of lymph nodes and lacrimal glands, and beaded dilation of the bile ducts. We diagnosed Ig4-RD based on biopsies of the lymph nodes, liver, and submandibular gland. The symptoms of the patient improved after glucocorticoid treatment. This was a novel and atypical case of Ig4-RD that was difficult to differentiate from other diseases, including eosinophilic granulomatosis with polyangiitis, idiopathic hypereosinophilic syndrome, and polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, skin changes syndrome. This case report highlights the importance of biopsies in differentiating Ig4-RD.

Comparisons of SLE-DAS and SLEDAI-2K and classification of disease activity based on the SLE-DAS with reference to patient-reported outcomes

OBJECTIVES

Although the SLE Disease Activity Score (SLE-DAS) and its definitions to classify disease activity have been recently developed to overcome the drawbacks of the SLE Disease Activity Index 2000 (SLEDAI-2K), the performance of the SLE-DAS for patient-reported outcomes (PROs) has not been fully examined. We aimed to compare SLE-DAS with SLEDAI-2K and validate the classifications of disease activity based on SLE-DAS in terms of PROs.

METHODS

We assessed generic quality of life (QoL) using the Medical Outcome Survey 36-Item Short-Form Health Survey (SF-36), disease-specific QoL using the lupus patient-reported outcome tool (LupusPRO), burden of symptoms using the SLE Symptom Checklist (SSC), patient global assessment (PtGA) and physician global assessment (PhGA).

RESULTS

Of the 335 patients with SLE, the magnitudes of the mean absolute error, root mean square error, Akaike information criterion, and Bayesian information criterion were comparable for most PROs between the SLE-DAS and SLEDAI-2K. In contrast, SLEDAI-2K had a higher predictive value for health-related QoL of LupusPRO and PtGA than SLE-DAS. Low disease activity, Boolean and index-based remission and categories of disease activity (remission, mild and moderate/severe activity) were significantly associated with health-related QoL in LupusPRO, SSC and PhGA, but not SF-36 or PtGA.

CONCLUSION

No clear differences were identified in the use of the SLE-DAS over the SLEDAI-2K in assessing PROs in patients with SLE. The classification of disease activity based on the SLE-DAS was validated against several PROs. SLE-DAS and its categories of disease activity effectively explain some of the PROs.

Risk prediction model for mortality in microscopic polyangiitis: multicentre REVEAL cohort study

BACKGROUND

To establish refined risk prediction models for mortality in patients with microscopic polyangiitis (MPA) by using comprehensive clinical characteristics.

METHODS

Data from the multicentre Japanese registry of patients with vasculitis (REVEAL cohort) were used in our analysis. In total, 194 patients with newly diagnosed MPA were included, and baseline demographic, clinical, laboratory, and treatment details were collected. Univariate and multivariate analyses were conducted to identify the significant risk factors predictive of mortality.

RESULTS

Over a median follow-up of 202.5 (84-352) weeks, 60 (30.9%) of 194 patients died. The causes of death included MPA-related vasculitis (18.3%), infection (50.0%), and others (31.7%). Deceased patients were older (median age 76.2 years) than survivors (72.3 years) (P < 0.0001). The death group had shorter observation periods (median 128.5 [35.3-248] weeks) than the survivor group (229 [112-392] weeks). Compared to survivors, the death group exhibited a higher smoking index, lower serum albumin levels, higher serum C-reactive protein levels, higher Birmingham Vasculitis Activity Score (BVAS), higher Five-Factor Score, and a more severe European Vasculitis Study Group (EUVAS) categorization system. Multivariate analysis revealed that higher BVAS and severe EUVAS independently predicted mortality. Kaplan-Meier survival curves demonstrated lower survival rates for BVAS ≥20 and severe EUVAS, and a risk prediction model (RPM) based on these stratified patients into low, moderate, and high-risk mortality groups.

CONCLUSIONS

The developed RPM is promising to predict mortality in patients with MPA and provides clinicians with a valuable tool for risk assessment and informed clinical decision-making.

Long-Term Prognosis of Antimelanoma Differentiation-Associated Gene 5-Positive Dermatomyositis With Interstitial Lung Disease

OBJECTIVE

Antimelanoma differentiation-associated gene 5 (anti-MDA5)-positive dermatomyositis with interstitial lung disease (DM-ILD) progresses rapidly and has a poor prognosis. Previously, we reported the efficacy of a combination therapy comprising high-dose glucocorticoids (GCs), calcineurin inhibitors (CNIs), and intravenous cyclophosphamide (IV CYC) in a multicenter clinical trial (UMIN000014344). In the present study, we evaluated the long-term outcomes and effects of induction therapy on the maintenance of remission.

METHODS

All participants from our previous trial were followed up for > 5 years. Seventy-three other patients with anti-MDA5-positive DM-ILD from our institute were retrospectively integrated into the previous trial for further analysis. Sixty-eight patients achieved remission and survived for > 6 months. Based on the induction treatment, we classified the patients into 2 groups: (1) group T (n = 56), with triple combination therapy (GCs, CNIs, and IV CYC), and (2) group C (n = 12), with monotherapy/dual therapy. The recurrence-free and drug-withdrawal rates of immunosuppressive agents were compared.

RESULTS

The overall survival and recurrence-free survival rates at 5 years were 100% for the participants in the previous trial. The 5-year cumulative withdrawal rates for CNIs and GCs were 70% and 53%, respectively. In a comprehensive analysis, the recurrence-free rates in group T were higher than those in group C (90% vs 56%; P < 0.05). The drug-withdrawal rates of CNIs and GCs at 10 years in group T were also higher than those in group C (79% vs 0% and 43% vs 0%, respectively; P < 0.05).

CONCLUSION

Triple combination therapy in the induction phase can reduce the risk of recurrence and facilitate drug withdrawal in anti-MDA5-positive DM-ILD.

Prediction model for respiratory-related mortality in microscopic polyangiitis with interstitial lung disease: multicenter REVEAL cohort study

OBJECTIVE

This study aimed to establish prediction models for respiratory-related mortality in microscopic polyangiitis (MPA) complicated by interstitial lung disease (ILD) using clinical characteristics.

METHODS

We enrolled patients with MPA with ILD between May 2005 and June 2021 in a multicentre cohort of Japanese patients with MPA (REVEAL cohort). We evaluated the demographic, clinical, laboratory, radiological findings, treatments, and the presence of honeycombing 1 cm above the diaphragm using chest high-resolution computed tomography (HRCT) on admission. We explored the risk factors predictive of respiratory-related mortality.

RESULTS

Of 115 patients, 26 cases died of respiratory-related diseases during a median follow-up of 3.8 years. Eighteen patients (69%) died due to respiratory infection, three (12%) had diffuse alveolar hemorrhage (DAH), and five (19%) had exacerbation of ILD. In univariate analysis, older age, lower percent forced vital capacity (%FVC), lower percent diffusing capacity of carbon monoxide (%DLco), and the presence of honeycombing in the right lower lobe were identified as risk factors. Additionally, in multivariate analysis adjusted for age and treatment, %FVC, %DLco, and the presence of honeycombing in the right lower lobe were independently associated with respiratory-related mortality. We created prediction models based on the values of %FVC, %DLco, and presence of honeycombing on chest HRCT (MPF model). The 5-year respiratory-related death-free rate was significantly different between patients with MPA with ILD stratified by the number of risk factors based on the MPF model.

CONCLUSIONS

Our study indicates that the MPF model may help predict respiratory-related death in patients with MPA with ILD.

Prognosis of patients with systemic sclerosis-related interstitial lung disease on the lung transplant waiting list: a retrospective study

Advanced systemic sclerosis-associated interstitial lung disease (SSc-ILD) can be treated with lung transplantation. There is limited data on lung transplantation outcomes in patients with SSc-ILD, in non-Western populations.We assessed survival data of patients with SSc-ILD, on the lung transplant (LT) waiting list, and evaluated post-transplant outcomes in patients from an Asian LT center. In this single-center retrospective study, 29 patients with SSc-ILD, registered for deceased LT at Kyoto University Hospital, between 2010 and 2022, were identified. We investigated post-transplant outcomes in recipients who underwent LT for SSc-ILD, between February 2002 and April 2022. Ten patients received deceased-donor LT (34%), two received living-donor LT (7%), seven died waiting for LT (24%), and ten survived on the waiting list (34%). Median duration from registration to deceased-donor LT was 28.9 months and that from registration to living-donor LT or death was 6.5 months. Analysis of 15 recipients showed improved forced vital capacity with a median of 55.1% at baseline, 65.8% at 6 months, and 80.3% at 12 months post-transplant. The 5-year survival rate for post-transplant patients with SSc-ILD was 86.2%. The higher post-transplant survival rate at our institute than previously reported suggests that lung transplantation is acceptable in Asian patients with SSc-ILD.

Genetic architecture underlying IgG-RF production is distinct from that of IgM-RF

OBJECTIVE

HLA-DRB1 alleles, particularly the shared epitope (SE) alleles, are strongly associated with RA. Different genetic structures underlie the production of different autoantibodies in RA. While extensive genetic analyses were conducted for detailed profiles of ACPA, a representative autoantibody in RA, the genetic architecture underlying subfractions of RF other than IgM-RF, namely IgG-RF, known to be associated with rheumatoid vasculitis, is not well understood.

METHODS

We enrolled a total of 743 RA subjects whose detailed autoantibody (IgG-RF, IgM-RF, and ACPA) data were available. We evaluated co-presence and correlations of the levels of these autoantibodies. We analyzed associations between the presence or levels of the autoantibodies and HLA-DRB1 alleles for the 743 RA patients and 2,008 healthy controls.

RESULTS

We found both IgG-RF(+) and IgG-RF(-) RA subjects showed comparable associations with SE, which was not observed for the other autoantibodies. Furthermore, there was a clear difference in SE associations between IgG-RF(+) and (-) subsets; the association with the IgG-RF(+) subsets was solely driven by HLA-DRB1*04:05, the most frequent SE allele in the Japanese, while not only HLA-DRB1*04:05 but HLA-DRB1*04:01, less frequent in the Japanese but the most frequent SE in Europeans, were main drivers in IgG-RF(-) subset. We confirmed that these associations were irrespective of ACPA presence.

CONCLUSION

We found a unique genetic architecture of IgG-RF(-) RA, which showed a strong association with the SE allele less frequent among Japanese but the most frequent in Europeans. The findings could shed light on uncovered RA pathology.

Medium-term impact of the SARS-CoV-2 mRNA vaccine against disease activity in patients with systemic lupus erythematosus

OBJECTIVES

Numerous case reports have referred to new onset or flare of SLE after SARS-CoV-2 messenger RNA (mRNA) vaccines. Several observational studies showed that the short-term flare rate of SLE after SARS-CoV-2 vaccination is low. However, well-controlled clinical surveys are unavailable and the medium-term impact of the SARS-CoV-2 mRNA vaccines against the flare of SLE is uncertain. Therefore, we aimed to analyse the association between vaccination and medium-term subjective and objective disease activities of SLE and flares using matched pair methods.

METHODS

Altogether, 150 patients with SLE from the Kyoto Lupus Cohort were included. Patients who received two doses of the SARS-CoV-2 mRNA vaccines were 1:1 matched with unvaccinated patients based on the first vaccination date. The outcome measures were the SLE Disease Activity Index-2000 (SLEDAI-2K), the Japanese version of the SLE Symptom Checklist Questionnaire (SSC-J) and the Safety of Estrogens in Lupus Erythematosus National Assessment-SLEDAI flare index at 30, 60 and 90 days after vaccination.

RESULTS

SLEDAI-2K levels were not significantly different in vaccinated and unvaccinated patients with SLE at 30, 60 and 90 days after the second vaccination (adjusted estimate (95% CI): 30 days: -0.46 (-1.48 to 0.56), p=0.39; 60 days: 0.38 (-0.64 to 1.40), p=0.47; 90 days: 0.40 (-0.54 to 1.34), p=0.41). Similar results were observed in the SSC-J score (adjusted estimate (95% CI), 30 days: 0.05 (-1.46 to 1.56), p=0.95; 60 days: -0.63 (-2.08 to 0.82), p=0.40; 90 days: 0.27 (-1.04 to 1.58), p=0.69) and flare index (adjusted OR (95% CI), 30 days: 0.81 (0.36 to 1.85), p=0.62; 60 days: 1.13 (0.50 to 2.54), p=0.77; 90 days: 0.85 (0.32 to 2.26), p=0.74).

CONCLUSION

SARS-CoV-2 vaccination did not significantly influence the medium-term subjective and objective disease activities or flares of SLE until 90 days after the second vaccination.

AB0470 THE ASSOCIATIONS OF ANTI-DNA ANTIBODIES WITH DISEASE ACTIVITY INDICES AND PATIENT REPORT OUTCOME PARAMETERS OF SLE IN KYOTO LUPUS COHORT

Background

Since the goals of remission or low disease activity are becoming more realistic with advances in treatment for SLE, there is a need to examine the measurements for SLE especially in patients with low disease activity. It has been known that disease activities in SLE are correlated with anti-DNA antibodies (Abs). However, it was not clear which measurements of disease activities or patient reported outcomes correlate better with anti-DNA Abs.

Objectives

To examine the association between parameters for SLE and anti-DNA Abs measured with RIA in Kyoto Lupus Cohort, a SLE registry in Kyoto University Hospital from 2019 to 2021.

Methods

1)Correlations between anti-DNA Abs with SLEDAI, M-SLEDAI (SLEDAI without anti-DNA Abs), VAS, LupusPRO, SF-36, and Systemic lupus erythematosus Symptom Checklist (SSC) were evaluated cross-sectionally (n = 310).

2)The alterations in SLE parameters and anti-DNA Abs between two visits were examined (n = 106). Further, the correlations within 3 months were examined in cases with flare-ups of SLE (the alteration in SLEDAI > 0 and anti-DNA Abs≧0, n = 39). The associations of the alterations of anti-DNA Abs with each item of SLEDAI classified by organs were also examined.

Results

1)31 percent of the cases in the entire registry was classified as remission or low disease activity (Table 1). SLEDAI (mean±SD) was higher in patients positive for anti-DNA Abs (7.94±5.20) than that in patients negative for anti-DNA Abs (4.56±4.65) (p < 0.0001). Anti-DNA Abs were weakly correlated with SLEDAI (R = 0.24 [p < 0.0001]), M-SLEDAI (R = 0.15 [p = 0.014]), and Physician-VAS (R = 0.19 [p = 0.0016]). On the other hand, there were no significant correlations between anti-DNA Abs and LupusPRO and SSC. Some dimensions in SF-36 had weak correlations with anti-DNA Abs, while no component summary scores had significant correlations with anti-DNA Abs.

Table 1.

Patients’ demographics and disease characteristics in the cohort (n = 310).

VariableResultsAge (years)47.7 (39.4, 57.5)Female sexn = 284 (91.6%)Disease duration (years)15.9 (9.4, 24.5)Anti-DNA Ab positivity†n = 106 (34.2%)Anti- DNA Ab titer (U/mL)4 (0, 8)SLEDAI4 (2, 8)SLEDAI<=4n = 162 (52.1%)SSC31 (16.2, 52.5)Remission or LDAn = 95 (30.7%)Patient-VAS38 (15, 52)Physician-VAS13.3 (3.3, 23.3)SF-36 PCS45.4 (36.6, 52.4)SF-36 MCS48.2 (41.5, 53.6)SF-36 RCS51.3 (42.6, 58.6)LupusPRO HQOL70.2 (54.8, 86.5)LupusPRO NHQOL41.7 (31.3, 51.0)Glucocorticoid (mg/day)5 (4, 8)

* Data are n (%) or median (Q1, Q3).

† Anti-DNA Ab positivity at the time of the cross-sectional observation.

2)No significant correlations were observed between the alterations of SLEDAI and anti-DNA Abs (R = 0.00 [95% CI: -0.23 – 0.22, p = 0.95]) in the total of patients with various range of observation periods (Figure 1A). In contrast, a significant correlation was observed (R = 0.32, p = 0.04) within 3 months after the flare-ups of SLE (Figure 1B). No significant correlations were found between the alterations in VAS and anti-DNA Abs, or the alterations of SSC and anti-DNA Abs. They showed the following organ symptoms: renal involvement, 62.8%; musculoskeletal, 17.1%; neuropsychiatric, 11.4%; hematological, 5.7%; mucocutaneous, 11.4%; serositis, 2.9%, and fever, 2.9%.

Figure 1.

The associations between the alteration in anti-DNA Ab and SLEDAI

Conclusion

The associations between anti-DNA Abs with several parameters of SLE were examined. Anti-DNA Abs correlated with disease activities (SLEDAI) in SLE patients, especially when observed in the condition of flare-up.

References

[1]Ho A, et al. Arthritis Rheum. 2001;44:2342-9.

Disclosure of Interests

None declared

NR4A nuclear receptors in T and B lymphocytes: Gatekeepers of immune tolerance. Immunol Rev 2022;307:116-133. [PMID: 35174510 DOI: 10.1111/imr.13072]

Random VDJ recombination early in T and B cell development enables the adaptive immune system to recognize a vast array of evolving pathogens via antigen receptors. However, the potential of such randomly generated TCRs and BCRs to recognize and respond to self-antigens requires layers of tolerance mechanisms to mitigate the risk of life-threatening autoimmunity. Since they were originally cloned more than three decades ago, the NR4A family of nuclear hormone receptors have been implicated in many critical aspects of immune tolerance, including negative selection of thymocytes, peripheral T cell tolerance, regulatory T cells (Treg), and most recently in peripheral B cell tolerance. In this review, we discuss important insights from many laboratories as well as our own group into the function and mechanisms by which this small class of primary response genes promotes self-tolerance and immune homeostasis to balance the need for host defense against the inherent risks posed by the adaptive immune system.

Negative feedback by NUR77/Nr4a1 restrains B cell clonal dominance during early T-dependent immune responses

B cell clones compete for entry into and dominance within germinal centers (GCs), where the highest-affinity B cell receptors (BCRs) are selected. However, diverse and low-affinity B cells can enter and reside in GCs for extended periods. To reconcile these observations, we hypothesize that a negative feedback loop may operate within B cells to preferentially restrain high-affinity clones from monopolizing the early GC niche. Here, we report a role for the nuclear receptor NUR77/Nr4a1 in this process. We show that NUR77 expression scales with antigen stimulation and restrains B cell expansion. Although NUR77 is dispensable for regulating GC size when GCs are elicited in a largely clonal manner, it serves to curb immunodominance under conditions where diverse clonal populations must compete for a constrained niche. We propose that this is important to preserve early clonal diversity in order to limit holes in the post-immune repertoire and to optimize GC selection.

NR4A family members regulate T cell tolerance to preserve immune homeostasis and suppress autoimmunity

The NR4A family of orphan nuclear receptors (Nr4a1–3) plays redundant roles to establish and maintain Treg identity; deletion of multiple family members in the thymus results in Treg deficiency and a severe inflammatory disease. Consequently, it has been challenging to unmask redundant functions of the NR4A family in other immune cells. Here we use a competitive bone marrow chimera strategy, coupled with conditional genetic tools, to rescue Treg homeostasis and unmask such functions. Unexpectedly, chimeras harboring Nr4a1^–/– Nr4a3^–/– (double-knockout, DKO) bone marrow developed autoantibodies and a systemic inflammatory disease despite a replete Treg compartment of largely WT origin. This disease differs qualitatively from that seen with Treg deficiency and is B cell extrinsic. Negative selection of DKO thymocytes is profoundly impaired in a cell-intrinsic manner. Consistent with escape of self-reactive T cells into the periphery, DKO T cells with functional, phenotypic, and transcriptional features of anergy accumulated in chimeric mice. Nevertheless, we observed upregulation of genes encoding inflammatory mediators in anergic DKO T cells, and DKO T cells exhibited enhanced capacity for IL-2 production. These studies reveal cell-intrinsic roles for the NR4A family in both central and peripheral T cell tolerance and demonstrate that each is essential to preserve immune homeostasis.

HLA-DRB1 Analysis Identified a Genetically Unique Subset within Rheumatoid Arthritis and Distinct Genetic Background of Rheumatoid Factor Levels from Anticyclic Citrullinated Peptide Antibodies

OBJECTIVE

HLA-DRB1 is the most important locus associated with rheumatoid arthritis (RA) and anticitrullinated protein antibodies (ACPA). However, fluctuations of rheumatoid factor (RF) over the disease course have made it difficult to define fine subgroups according to consistent RF positivity for the analyses of genetic background and the levels of RF.

METHODS

A total of 2873 patients with RA and 2008 healthy controls were recruited. We genotyped HLA-DRB1 alleles for the participants and collected consecutive data of RF in the case subjects. In addition to RF+ and RF- subsets, we classified the RF+ subjects into group 1 (constant RF+) and group 2 (seroconversion). We compared HLA-DRB1 alleles between the RA subsets and controls and performed linear regression analysis to identify HLA-DRB1 alleles associated with maximal RF levels. Omnibus tests were conducted to assess important amino acid positions.

RESULTS

RF positivity was 88%, and 1372 and 970 RF+ subjects were classified into groups 1 and 2, respectively. RF+ and RF- showed similar genetic associations to ACPA+ and ACPA- RA, respectively. We found that shared epitope (SE) was more enriched in group 2 than 1, p = 2.0 × 10^-5, and that amino acid position 11 showed a significant association between 1 and 2, p = 2.7 × 10^-5. These associations were independent of ACPA positivity. SE showed a tendency to be negatively correlated with RF titer (p = 0.012). HLA-DRB1*09:01, which reduces ACPA titer, was not associated with RF levels (p = 0.70).

CONCLUSION

The seroconversion group was shown to have distinct genetic characteristics. The genetic architecture of RF levels is different from that of ACPA.

Splicing variant of WDFY4 augments MDA5 signalling and the risk of clinically amyopathic dermatomyositis

OBJECTIVES

Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare autoimmune diseases in which both genetic and environmental factors play important roles. To identify genetic factors of IIM including polymyositis, dermatomyositis (DM) and clinically amyopathic DM (CADM), we performed the first genome-wide association study for IIM in an Asian population.

METHODS

We genotyped and tested 496 819 single nucleotide polymorphism for association using 576 patients with IIM and 6270 control subjects. We also examined the causal mechanism of disease-associated variants by in silico analyses using publicly available data sets as well as by in in vitro analyses using reporter assays and apoptosis assays.

RESULTS

We identified a variant in WDFY4 that was significantly associated with CADM (rs7919656; OR=3.87; P=1.5×10^-8). This variant had a cis-splicing quantitative trait locus (QTL) effect for a truncated WDFY4isoform (tr-WDFY4), with higher expression in the risk allele. Transexpression QTL analysis of this variant showed a positive correlation with the expression of NF-κB associated genes. Furthermore, we demonstrated that both WDFY4 and tr-WDFY4 interacted with pattern recognition receptors such as TLR3, TLR4, TLR9 and MDA5 and augmented the NF-κB activation by these receptors. WDFY4 isoforms also enhanced MDA5-induced apoptosis to a greater extent in the tr-WDFY4-transfected cells.

CONCLUSIONS

As CADM is characterised by the appearance of anti-MDA5 autoantibodies and severe lung inflammation, the WDFY4 variant may play a critical role in the pathogenesis of CADM.

Only rheumatoid factor-positive subset of anti-citrullinated peptide/protein antibody-negative rheumatoid arthritis may seroconvert to anti-citrullinated peptide/protein antibody-positive

AIM

Anti-citrullinated peptide/protein antibody (ACPA) has been reported to occur in about 60% of patients with early rheumatoid arthritis (RA), and about 80% in patients with established RA. While ACPA seroconversion is possible, previous reports have shown that it rarely occurs. We retrospectively determined the proportion of patients who underwent ACPA seroconversion and described the clinical characteristics of these cases.

METHODS

ACPA-negative RA patients who had undergone ACPA assessment more than once with an interval of 3 months or longer were investigated for ACPA seroconversion. The clinical characteristics of seroconverted patients were assessed.

RESULTS

In 149 ACPA-negative RA patients, only eight patients (5.4%) converted to ACPA-positive during follow-up. We found that all eight of the seroconverted cases were positive for rheumatoid factor (RF) and showed bone erosions by X-ray. Of 56 ACPA-negative RF-positive RA patients, 14.3% of them seroconverted to ACPA-positive. None of the ACPA-negative RF-negative RA patients seroconverted to ACPA-positive.

CONCLUSION

The proportion of total RA patients who experienced seroconversion from ACPA-negative to ACPA-positive was 5.4%. When ACPA-negative RA patients were subdivided into RF-negative and RF-positive subsets, only the RF-positive subset seroconverted to ACPA-positive. These results imply that RF-negative and RF-positive patients are distinct subsets within ACPA-negative RA patients.

Misfolded proteins complexed with MHC class II molecules are targets for autoantibodies

Major histocompatibility complex (MHC) molecule is important for immune system through its function of presentation of peptide antigens. MHC is the gene most strongly associated with susceptibility to many autoimmune diseases. We recently found a novel function of MHC class II molecules to transport cellular misfolded proteins to the cell surface without processing to peptides. Interestingly, misfolded proteins transported to the cell surface by MHC class II molecules were found to be a specific targets for autoantibodies produced in patients with autoimmune diseases such as rheumatoid arthritis and antiphospholipid syndrome. Furthermore, autoantibody binding to misfolded proteins complexed with MHC class II molecules is strongly associated with the susceptibility to autoimmune diseases conferred by each MHC class II allele. Therefore, misfolded proteins associated with MHC class II molecules might be involved in the pathogenesis of autoimmune diseases.