ObjectivePlasmablasts play important roles in autoimmune diseases, including systemic lupus erythematosus (SLE). Activation of mechanistic target of rapamycin complex 1 (mTORC1) is regulated by amino acid levels. In patients with SLE, mTORC1 is activated in B cells and modulates plasmablast differentiation. However, the detailed mechanisms of amino acid metabolism in plasmablast differentiation remain elusive. We undertook this study to evaluate the effects of methionine in human B cells.MethodsPurified CD19+ cells from healthy donors (n = 21) or patients with SLE (n = 35) were cultured with Toll‐like receptor 7/9 ligand, interferon‐α (IFNα), and B cell receptor crosslinking, and we determined the types of amino acids that were important for plasmablast differentiation and amino acid metabolism. We also identified the transcriptional regulatory mechanisms induced by amino acid metabolism, and we assessed B cell metabolism and its relevance to SLE.ResultsThe essential amino acid methionine strongly committed cells to plasmablast differentiation. In the presence of methionine, Syk and mTORC1 activation synergistically induced methyltransferase EZH2 expression. EZH2 induced H3K27me3 at BTB and CNC homolog 2 (Bach2) loci and suppressed Bach2 expression, leading to induction of B lymphocyte–induced maturation protein 1 and X‐box binding protein 1 expression and plasmablast differentiation. CD19+ cells from patients with SLE overexpressed EZH2, which was correlated with disease activity and autoantibody production.ConclusionOur findings show that methionine activated signaling by controlling immunologic metabolism in B cells and played an important role in the differentiation of B cells into plasmablasts through epigenome modification of Bach2 by the methyltransferase EZH2.

Objective To evaluate the dysfunction of B cell metabolism and its involvement in SLE pathology. Methods We assessed the expression of metabolic markers of B cells in the peripheral blood of healthy controls (HCs) and SLE patients by using flow cytometry. In vitro, peripheral B cells were isolated from HCs and SLE patients to investigate the metabolic regulation mechanisms involved in their differentiation. Results The expression level of DiOc6 (mitochondrial membrane hyperpolarization) was higher in B cells from SLE patients than in HCs, and correlated to the percentage of plasmablasts in CD19+ cells and with SLEDAI, a disease activity score. Stimulation of CD19+ cells with the Toll-like receptor 9 (TLR9) ligand CpG and IFN-α enhanced glycolysis, oxidative phosphorylation (OXPHOS), DiOc6 expression, and plasmablast differentiation in vitro. In the absence of glutamine, both glycolysis and OXPHOS were reduced, and plasmablast differentiation was suppressed, whereas there was no change in the absence of glucose. As glutamine is an important nutrient for protein synthesis, we further investigated the effect of the glutaminase inhibitor BPTES, which inhibits glutamine degradation, on metabolic regulation. BPTES reduced DiOc6 expression, OXPHOS, reactive oxygen species (ROS) production, ATP production, plasmablast differentiation without affecting glycolysis. Metformin inhibited CpG- and IFN-α-induced glutamine uptake, mitochondrial functions and suppressed plasmablast differentiation. Conclusions Mitochondrial dysfunction in B cells is associated with plasmablast differentiation and disease activity in SLE. Enhanced mitochondrial functions mediated by glutamine metabolism are important for plasmablast differentiation, which may be a potential therapeutic target for SLE.

ObjectivesTo investigate short-term prognosis and prognostic factors for connective tissue disease-associated pneumocystis pneumonia (CTD-PCP) using the Japanese nationwide diagnosis procedure combination (DPC) inpatient database.MethodsThe present retrospective cohort study from April 2014 to March 2016 included data of patients with CTD-PCP extracted from the DPC database using the 10th revision of International Classification of Diseases and Injuries codes.ResultsIn 15 901 766 cases registered from 1329 hospitals, 333 of 67 890 patients who were admitted with PCP were diagnosed with CTD-PCP and included in the study. The median age was 71.0 years, and 214 (64.3%), 80 (24.0%), and 29 (8.7%) patients received sulfamethoxazole/trimethoprim (ST) monotherapy and pentamidine-containing and atovaquone-containing therapy, respectively. There were 114 (34.2%) in-hospital deaths, and the 30-day and 60-day in-hospital survival rates after PCP treatment initiation were 66.0% and 53.7%, respectively. Older age (HR 1.06, 95% CI 1.03 to 1.08) and concomitant interstitial lung disease (ILD) (HR 1.65, 95% CI 1.12 to 2.42) were poor prognostic factors. Patients who completed PCP treatment with ST monotherapy had a significantly higher survival rate than those treated with those not treated with ST monotherapy (p=0.015; log-rank test). Pentamidine versus atovaquone as second-line therapy was significantly higher with atovaquone (p=0.012; log-rank test).ConclusionOlder age and concomitant ILD were poor prognostic factors for CTD-PCP. ST was a reasonable first-line therapy in patients with CTD-PCP, and patients with inadequate response to ST treated with atovaquone tended to have a better prognosis than those treated with pentamidine.

Recent reports have shown the importance of IFN-γ and T-bet+ B cells in the pathology of SLE, suggesting the involvement of IFN-γ-producing T-bet+ CD4+ cells, i.e., Th1 cells. This study determined the changes in Th1 subsets with metabolic shift and their potential as therapeutic targets in SLE. Compared with healthy donors, patients with SLE had higher numbers of T-bethiCXCR3lo effector cells and T-bet+Foxp3lo non-suppressive cells, which excessively produce IFN-γ, and lower number of non-IFN-γ-producing T-bet+Foxp3hi activated-Treg cells. These changes were considered to be involved in treatment resistance. The differentiation mechanism of Th1 subsets was investigated in vitro using memory CD4+ cells obtained from healthy donors and patients with SLE. In memory CD4+ cells of healthy donors, both rapamycin and 2-deoxy-D-glucose (2DG) suppressed T-bet+Foxp3- cells, and induced T-bet+Foxp3+(lo/hi) cells. Rapamycin induced IFN-γ-producing T-bet+Foxp3lo cells accompanied with enhanced lipid metabolism, whereas 2DG induced IFN-γ-non-producing T-bet+Foxp3hi cells. In memory CD4+ cells of SLE patients, inhibition of fatty acid synthesis, but not β-oxidation, suppressed IFN-γ production, and up-regulated of Foxp3 expression in T-bet+Foxp3+ cells. Metabolic regulators such as fatty acid synthesis inhibitors may improve the pathological status by correcting Th1 subset imbalance and overproduction of IFN-γ in SLE.

Objectives This study aimed to clarify the usefulness of screening for malignancies using computed tomography (CT) before the initiation of biologics and targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) in patients with active rheumatoid arthritis (RA). Methods We examined 2,192 patients with RA who underwent plain CT scans prior to the initiation of b/tsDMARDs. The sensitivity for detecting malignancy was measured and compared with that of Regular screening (physical examination and X-ray). We then evaluated the clinical characteristics, prognosis, and treatment of patients with RA with concomitant malignancies. Additionally, we determined the incidence rate of malignancy in patients with RA who were initiated b/tsDMARDs after CT screening. Results Of the 2,192 patients, 33 (1.5%) were diagnosed with malignancy after CT screening. Whereas regular screening detected only 7 malignancies, CT screening further detected 26 (including 19 at the early stage). On the other hand, 86% of the malignancies detectable by regular screening were at advanced stage. Patients diagnosed with early-stage malignancies received RA treatments that included b/tsDMARDs after curative resection; 80% of these patients achieved low disease activity after 1 year. This rate was comparable of the patients without malignancy detection after screening (70%). The 5 years-incidence of malignancy after the initiation of b/tsDMARDs after CT screening was lower to that of RA cohort without CT screening (standardized incidence ratio: 0.35). Conclusion Screening in patients with RA using CT before the initiation of b/tsDMARDs allows for the early detection and treatment of malignancy, resulting in safer and more stable b/tsDMARD treatments.