Lupus is characterized by the autoantibodies against nuclear Ags, underscoring the importance of identifying the B cell subsets driving autoimmunity. Our research focused on the mitochondrial activity and CXCR4 expression in CD11c + B cells from lupus patients after ex vivo stimulation with a TLR9 agonist, CpG-oligodeoxyribonucleotide (ODN). We also evaluated the response of CD11c + B cells in ODN-injected mice. Post-ex vivo ODN stimulation, we observed an increase in the proportion of CD11chi cells, with elevated mitochondrial activity and CXCR4 expression in CD11c + B cells from lupus patients. In vivo experiments showed similar patterns, with TLR9 stimulation enhancing mitochondrial and CXCR4 activities in CD11chi B cells, leading to the generation of anti-dsDNA plasmablasts. The CXCR4 inhibitor AMD3100 and the mitochondrial complex I inhibitor IM156 significantly reduced the proportion of CD11c + B cells and autoreactive plasmablasts. These results underscore the pivotal roles of mitochondria and CXCR4 in the production of autoreactive plasmablasts.

Lupus is characterized by the autoantibodies against nuclear Ags, underscoring the importance of identifying the B cell subsets driving autoimmunity. Our research focused on the mitochondrial activity and CXCR4 expression in CD11c + B cells from lupus patients after ex vivo stimulation with a TLR9 agonist, CpG-oligodeoxyribonucleotide (ODN). We also evaluated the response of CD11c + B cells in ODN-injected mice. Post-ex vivo ODN stimulation, we observed an increase in the proportion of CD11chi cells, with elevated mitochondrial activity and CXCR4 expression in CD11c + B cells from lupus patients. In vivo experiments showed similar patterns, with TLR9 stimulation enhancing mitochondrial and CXCR4 activities in CD11chi B cells, leading to the generation of anti-dsDNA plasmablasts. The CXCR4 inhibitor AMD3100 and the mitochondrial complex I inhibitor IM156 significantly reduced the proportion of CD11c + B cells and autoreactive plasmablasts. These results underscore the pivotal roles of mitochondria and CXCR4 in the production of autoreactive plasmablasts.

Lupus is characterized by the autoantibodies against nuclear Ags, underscoring the importance of identifying the B cell subsets driving autoimmunity. Our research focused on the mitochondrial activity and CXCR4 expression in CD11c + B cells from lupus patients after ex vivo stimulation with a TLR9 agonist, CpG-oligodeoxyribonucleotide (ODN). We also evaluated the response of CD11c + B cells in ODN-injected mice. Post-ex vivo ODN stimulation, we observed an increase in the proportion of CD11chi cells, with elevated mitochondrial activity and CXCR4 expression in CD11c + B cells from lupus patients. In vivo experiments showed similar patterns, with TLR9 stimulation enhancing mitochondrial and CXCR4 activities in CD11chi B cells, leading to the generation of anti-dsDNA plasmablasts. The CXCR4 inhibitor AMD3100 and the mitochondrial complex I inhibitor IM156 significantly reduced the proportion of CD11c + B cells and autoreactive plasmablasts. These results underscore the pivotal roles of mitochondria and CXCR4 in the production of autoreactive plasmablasts.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) comprises group of small vessel vasculitides, including granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). In 2022, the American College of Rheumatology (ACR) and the European Alliance of Associations for Rheumatology (EULAR) jointly proposed new classification criteria for AAV (the 2022 ACR/EULAR criteria). In this review, we briefly summarize the 2022 ACR/EULAR criteria for GPA, MPA, and EGPA, and introduce our clinical experience with applying them to patients who were previously diagnosed with AAV based on three criteria: firstly, the classification criteria for GPA and EGPA proposed by the ACR in 1990; secondly, the algorithm for the classification of AAV and polyarteritis nodosa proposed by the European Medicines Agency algorithm in 2007 (the 2007 EMA algorithm); and thirdly, the revised International Chapel Hill Consensus Conference nomenclature of vasculitides in 2012 (the 2012 CHCC definitions). We found that concordance rate was highest in patients with MPA (96.6%), followed by those with EGPA (86.3%) and GPA (73.8%). In addition, compared to previous criteria, we noted several issues of the undervalued or overvalued items in the 2022 ACR/EULAR criteria for classifying AAV and provided several suggestions. To increase the diagnostic accuracy and reduce the discordance rate among the new and previous criteria for AAV, we suggest that the previous criteria should be considered together with the 2022 ACR/EULAR criteria when applying the classification criteria for AAV to patients suspected of AAV.

Background: There is difference in the incidence of multi-system inflammatory syndrome in children (MIS-C) in patients with different variants of severe acute respiratory syndrome coronavirus 2, however, little is known about the epidemiology in Asian countries. We investigated and compared the epidemiology of the MIS-C during omicron-dominant period with that of previous periods in South Korea. Methods: We obtained clinical, epidemiological and laboratory data on MIS-C cases from national MIS-C surveillance in South Korea. We defined pre-delta period as January 2020–May 2021; delta period as June 2021–December 2021; and omicron period as January 2022–April 2022. We describe the clinical characteristics and outcomes of MIS-C patients by period. Results: A total of 91 cases were assessed to be MIS-C cases. Number of MIS-C cases have increased from six cases during pre-delta period to 66 cases during omicron period, while the incidence rate (the number of MIS-C cases per 100,000 cases of reported coronavirus disease 2019) has decreased from 38.5 cases per 100,000 (95% confidence interval [CI], 14.1–83.9) during pre-delta period to 1.6 cases per 100,000 (95% CI, 1.2–2.0) during omicron periods. During pre-delta period, 66.7% and 100% had hypotension and gastrointestinal involvement, respectively; while during omicron period, 12.1% and 6.1% had such clinical manifestations. Fifty percent of pre-delta MIS-C patients were taken intensive care unit (ICU) cares, while 10.6% of patients during omicron periods were in ICUs. Conclusion Omicron period were associated with less severe clinical manifestation compared to pre-delta and delta periods. Although incidence rate of MIS-C was lower for the omicron period than pre-delta and delta periods, number of patients reported with MIS-C may pose a substantial clinical burden.

Objective: This study retrospectively reviewed the process of classifying antineutrophil cytoplasmic antibody (ANCA)-negative granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) in a cohort of patients with ANCA-associated vasculitis (AAV), and investigated the association between recurrent idiopathic cutaneous leukocytoclastic angiitis and ANCA-negative MPA. Methods: The medical records of 242 patients with AAV were retrospectively reviewed. Of 49 patients with ANCA-negative AAV, 24 patients with ANCA-negative eosinophilic GPA (EGPA) were excluded, because ANCA positivity or negativity is not critical in classifying EGPA. Ultimately, 25 patients with ANCA-negative GPA and MPA were analysed in this study. The classification of GPA and MPA were based on the 2007 European Medicines Agency algorithm for AAV. Results: The median age of patients with ANCA-negative GPA and MPA was 54.0 years and 24% were male. Of the 25 patients without ANCA, 8 patients were classified as GPA and 17 as MPA. Eight patients with ANCA-negative GPA were easily confirmed as definitive GPA. Fourteen of the 17 patients ANCA-negative MPA were classified as MPA based on histological features suggestive of AAV without granuloma formation and the absence of surrogate markers for GPA. Meanwhile, three of the patients that were ANCA-negative exhibited only recurrent idiopathic cutaneous leukocytoclastic angiitis without other major organs affected and thus were classified as possible MPA. Within one year, they were classified as definitive MPA based on ANCA positivity and/or renal histology. Conclusion Recurrent idiopathic cutaneous leukocytoclastic angiitis may be associated with ANCA-negative MPA in patients who exhibit cutaneous necrotising vasculitis.

Background: We investigated and compared the initial clinical features at diagnosis and the poor outcomes during follow-up in Korean patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) based on sex. Methods: The medical records of 223 immunosuppressive drug-naïve patients with AAV were reviewed. Age, body mass index (BMI), smoking history, AAV subtypes, ANCA positivity, clinical manifestations, Birmingham vasculitis activity score (BVAS), five-factor score (FFS), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) at diagnosis were collected. All-cause mortality, end-stage renal disease (ESRD), cerebrovascular accident (CVA) and cardiovascular disease (CVD) were assessed as the poor outcomes of AAV during follow-up. Results: The median age was 59.0 years and 74 of 223 AAV patients (33.2%) were men.Among variables at diagnosis, male patients exhibited higher BMI than female. However, there were no differences in other demographic data, AAV subtypes, ANCA positivity, BVAS, FFS, ESR and CRP between the two groups. Male patients received cyclophosphamide more frequently, but there were no significant differences in the frequencies of the poor outcomes of AAV between the two groups. Male patients exhibited a significantly lower cumulative patients' survival rate than female patients during the follow-up period based on all-cause mortality (P = 0.037). In the multivariable analysis, both male sex (hazard ratio [HR], 2.378) and FFS (HR, 1.693) at diagnosis were significantly and independently associated with allcause mortality during follow-up. Conclusion Male sex is a significant and independent predictor of all-cause mortality in AAV patients.

Purpose: The present study compared the efficacy of mycophenolate mofetil (MMF) with that of azathioprine (AZA) in Korean patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA). Materials and Methods: The medical records of 69 patients with MPA and GPA who received cyclophosphamide and subsequently received AZA or MMF for remission maintenance therapy were reviewed. All-cause mortality, relapse, end-stage renal disease (ESRD), cerebrovascular accident, and cardiovascular disease were evaluated as poor outcomes. Having a lower Birmingham Vasculitis Activity Score (BVAS) was defined as the lowest tertile of BVAS (BVAS ≤11 in this study). Results: In comparative analysis of the occurrence of poor outcomes among patients taking AZA only, MMF only, and MMF after AZA, patients taking MMF only exhibited a significantly lower cumulative ESRD-free survival rate than patients taking AZA only (p=0.028). In terms of ESRD occurrence between the groups based on BVAS at diagnosis, among patients with MPA and GPA with higher BVAS at diagnosis, patients taking MMF only exhibited a significantly lower cumulative ESRD-free survival rate than those taking AZA only (p=0.047). Among patients with MPA and GPA with the lowest tertile of BVAS at diagnosis, cumulative ESRD-free survival rates did not differ. Conclusion With regard to ESRD occurrence, the efficacy of MMF in remission maintenance therapy was less effective than AZA in patients with MPA and GPA. However, among patients with lower BVAS, there was no difference in the occurrence of poor outcomes between patients taking MMF and those taking AZA.

Background: We investigated and compared the initial clinical features at diagnosis and the poor outcomes during follow-up in Korean patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) based on sex. Methods: The medical records of 223 immunosuppressive drug-naïve patients with AAV were reviewed. Age, body mass index (BMI), smoking history, AAV subtypes, ANCA positivity, clinical manifestations, Birmingham vasculitis activity score (BVAS), five-factor score (FFS), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) at diagnosis were collected. All-cause mortality, end-stage renal disease (ESRD), cerebrovascular accident (CVA) and cardiovascular disease (CVD) were assessed as the poor outcomes of AAV during follow-up. Results: The median age was 59.0 years and 74 of 223 AAV patients (33.2%) were men.Among variables at diagnosis, male patients exhibited higher BMI than female. However, there were no differences in other demographic data, AAV subtypes, ANCA positivity, BVAS, FFS, ESR and CRP between the two groups. Male patients received cyclophosphamide more frequently, but there were no significant differences in the frequencies of the poor outcomes of AAV between the two groups. Male patients exhibited a significantly lower cumulative patients' survival rate than female patients during the follow-up period based on all-cause mortality (P = 0.037). In the multivariable analysis, both male sex (hazard ratio [HR], 2.378) and FFS (HR, 1.693) at diagnosis were significantly and independently associated with allcause mortality during follow-up. Conclusion Male sex is a significant and independent predictor of all-cause mortality in AAV patients.

Purpose: The present study compared the efficacy of mycophenolate mofetil (MMF) with that of azathioprine (AZA) in Korean patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA). Materials and Methods: The medical records of 69 patients with MPA and GPA who received cyclophosphamide and subsequently received AZA or MMF for remission maintenance therapy were reviewed. All-cause mortality, relapse, end-stage renal disease (ESRD), cerebrovascular accident, and cardiovascular disease were evaluated as poor outcomes. Having a lower Birmingham Vasculitis Activity Score (BVAS) was defined as the lowest tertile of BVAS (BVAS ≤11 in this study). Results: In comparative analysis of the occurrence of poor outcomes among patients taking AZA only, MMF only, and MMF after AZA, patients taking MMF only exhibited a significantly lower cumulative ESRD-free survival rate than patients taking AZA only (p=0.028). In terms of ESRD occurrence between the groups based on BVAS at diagnosis, among patients with MPA and GPA with higher BVAS at diagnosis, patients taking MMF only exhibited a significantly lower cumulative ESRD-free survival rate than those taking AZA only (p=0.047). Among patients with MPA and GPA with the lowest tertile of BVAS at diagnosis, cumulative ESRD-free survival rates did not differ. Conclusion With regard to ESRD occurrence, the efficacy of MMF in remission maintenance therapy was less effective than AZA in patients with MPA and GPA. However, among patients with lower BVAS, there was no difference in the occurrence of poor outcomes between patients taking MMF and those taking AZA.