Immunology and targeted therapy in Castleman disease.

INTRODUCTION: Castleman disease (CD) is a benign lymphoproliferative disease causing severe systemic inflammation. Interleukin-6 (IL-6) is a major pathogenesis of multicentric CD (MCD), but only 30-60% of patients respond to IL-6 inhibitors. Novel agents for IL-6 inhibitor-refractory cases are needed. Clinical data and samples are being collected on a large scale and the clinical, pathological, and pathogenetic aspects are being elucidated. AREAS COVERED: The pathological and clinical classification of CD is outlined. Focusing on idiopathic MCD (iMCD), this review identifies therapeutic targets and summarizes currently recommended drugs and promising therapeutic candidates. EXPERT OPINION: The pathogenesis of MCD has been implicated in the activation of the Janus kinase (JAK)-transcriptional signaling activator (STAT) 3 pathway and the phosphatidylinositol 3-kinase (PI3K)/Akt/mechanical target of rapamycin (mTOR) signaling pathway. iMCD-TAFRO (thrombocytopenia, anasarca, fever/elevated CRP, reticulin myelofibrosis/renal dysfunction, organ enlargement) is resistant to IL-6 inhibitors, and cyclosporine and mTOR inhibitors are sometimes effective. JAK inhibitors and mTOR inhibitors may be therapeutic agents for iMCD. Recently, we have shown that peripheral helper T (Tph) cell abnormalities are at the core of iMCD pathogenesis. Therapies targeting chemokine (C-X-C motif) ligand 13 (CXCL13) produced by Tph cells and blocking the Tph-CXCL13-B cell pathway may satisfy unmet need in refractory cases.

Association of a Single Nucleotide Variant in TERT with Airway Disease in Japanese Rheumatoid Arthritis Patients.

Interstitial lung disease and airway disease (AD) are often complicated with rheumatoid arthritis (RA) and have a poor prognosis. Several studies reported genetic associations with interstitial lung disease in RA. However, few genetic studies have examined the susceptibility to AD in RA patients. Here, we investigated whether single nucleotide variants susceptible to idiopathic pulmonary fibrosis might be associated with interstitial lung disease or AD in Japanese RA patients. Genotyping of rs2736100 [C/A] in TERT and rs1278769 [G/A] in ATP11A was conducted in 98 RA patients with usual interstitial pneumonia, 120 with nonspecific interstitial pneumonia (NSIP), 227 with AD, and 422 without chronic lung disease using TaqMan assays. An association with AD in RA was found for rs2736100 (p = 0.0043, Pc = 0.0129, odds ratio [OR] 1.40, 95% confidence interval [CI] 1.11-1.77). ATP11A rs1278769 was significantly associated with NSIP in older RA patients (>65 years, p = 0.0010, OR 2.15, 95% CI 1.35-3.40). This study first reported an association of rs2736100 with AD in RA patients and ATP11A rs1278769 with NSIP in older RA patients.

A Case of Acute Kidney Injury Caused by Myoglobin Cast Nephropathy With Sars-Cov-2 Infection in a Living-Donor Kidney Transplant Recipient.

When COVID-19 affects patients with risk factors such as chronic kidney disease or on immunosuppressive drugs, they often rapidly become seriously ill. We describe a 50-year-old man who was affected with SARS-CoV-2 and had undergone an ABO-compatible living-donor kidney transplantation from his father 14 years ago because of end-stage renal failure due to hypertensive nephrosclerosis. He had continued on immunosuppressive drugs and completed vaccination twice (9 months ago and 6 months ago) with messenger RNA (mRNA) vaccines against SARS-CoV-2. However, he was temporarily on a mechanical ventilator due to respiratory failure and hemodialysis due to acute kidney injury (AKI). He was finally weaned from the ventilator and hemodialysis by taking steroid and antiviral drugs. Echo-guided renal biopsy revealed myoglobin cast nephropathy. We experienced 14 outpatients after living-donor kidney transplantation infected with SARS-CoV-2, but only this case developed AKI.

Increased levels of plasma nucleotides in patients with rheumatoid arthritis.

Novel biomarkers of rheumatoid arthritis (RA), in addition to antibodies against cyclic citrullinated peptides, are required. Metabolome analysis is a promising approach to identify metabolite biomarkers for clinical diagnosis. We adopted a comprehensive non-targeted metabolomics approach combining capillary electrophoresis time-of-flight mass spectrometry (TOFMS) and liquid chromatography TOFMS. We constructed metabolomics profiling of 286 plasma samples of a Japanese population [92 RA patients, 13 systemic lupus erythematosus (SLE) patients and 181 healthy controls). RA case-control association tests showed that seven metabolites exhibited significantly increased levels in RA samples compared with controls (P < 1.0 × 10-4; UTP, ethanolamine phosphate, ATP, GDP, ADP, 6-aminohexanoic acid and taurine), whereas one exhibited a decreased level (xanthine). The plasma levels of these eight metabolites were not significantly different between seropositive and seronegative RA patients (P > 0.05; n = 68 and 24, respectively). The four nucleotide levels (UTP, ATP, GDP and ADP) were significantly higher in the non-treatment patients in comparison between patients with and without treatment (P < 0.014; n = 57 and 35, respectively). Furthermore, we found that none of the four nucleotide levels showed significant differences in SLE case-control association tests (P > 0.2; 13 patients with SLE and the 181 shared controls) and psoriatic arthritis (PsA) case-control association tests (P > 0.11; 42 patients with PsA and 38 healthy controls), indicating disease specificity in RA. In conclusion, our large-scale metabolome analysis demonstrated the increased plasma nucleotide levels in RA patients, which could be used as potential clinical biomarkers of RA, especially for seronegative RA.

Sustained discontinuation of infliximab with a raising-dose strategy after obtaining remission in patients with rheumatoid arthritis: the RRRR study, a randomised controlled trial.

OBJECTIVES: The aim of this study is to determine whether the 'programmed' infliximab (IFX) treatment strategy (for which the dose of IFX was adjusted based on the baseline serum tumour necrosis factor α (TNF-α)) is beneficial to induction of clinical remission after 54 weeks and sustained discontinuation of IFX for 1 year. METHODS: In this multicentre randomised trial, patients with IFX-naïve rheumatoid arthritis with inadequate response to methotrexate were randomised to two groups; patients in programmed treatment group received 3 mg/kg IFX until week 6 and after 14 weeks the dose of IFX was adjusted based on the baseline levels of serum TNF-α until week 54; patients in the standard treatment group received 3 mg/kg of IFX. Patients who achieved a simplified disease activity index (SDAI) ≤3.3 at week 54 discontinued IFX. The primary endpoint was the proportion of patients who sustained discontinuation of IFX at week 106. RESULTS: A total of 337 patients were randomised. At week 54, 39.4% (67/170) in the programmed group and 32.3% (54/167) in the standard group attained remission (SDAI ≤3.3). At week 106, the 1-year sustained discontinuation rate was not significantly different between two groups; the programmed group 23.5% (40/170) and the standard group 21.6% (36/167), respectively (2.2% difference, 95% CI -6.6% to 11.0%; p=0.631). Baseline SDAI <26.0 was a statistically significant predictor of the successfully sustained discontinuation of IFX at week 106. CONCLUSION: Programmed treatment strategy did not statistically increase the sustained remission rate after 1 year discontinuation of IFX treatment.

Serum neopterin as well as ferritin, soluble interleukin-2 receptor, KL-6 and anti-MDA5 antibody titer provide markers of the response to therapy in patients with interstitial lung disease complicating anti-MDA5 antibody-positive dermatomyositis.

Objective: This study identified biomarkers that can be used to assess disease activity and response to therapy in patients with interstitial lung disease complicating anti-melanoma differentiation-associated gene 5 (MDA5) antibody (Ab)-positive clinically amyopathic dermatomyositis (CADM). Methods: In 15 patients with interstitial lung disease complicating anti-MDA5 Ab-positive CADM, anti-MDA5 Ab, neopterin, interleukin (IL)-18, ferritin, and soluble interleukin 2 receptor (sIL-2R) levels were measured in cryopreserved serum specimens before and at multiple times after remission induction therapy, and their correlations were assessed. Results: Anti-MDA5 Ab, neopterin, IL-18, ferritin, and sIL-2R levels did not differ significantly between patients who survived and those who succumbed to the disease. In many cases, serum anti-MDA5 Ab titers were over the upper limit (over 150 index value) before treatment in the usual measuring method, and gradually decreased to the normal range at stable phase. Meanwhile, serum neopterin levels (21.6 [15.3-48.3] nmol/L) were significantly elevated in newly diagnosed patients and fell to 6.8 (5-11.4) nmol/L at 6 months after treatment introduction. Conclusions: Elevated serum neopterin as well as ferritin, sIL-2R, KL-6, and anti-MDA5 Ab titer might help identify patients with interstitial lung disease complicated with DM and might be useful in monitoring response to therapy.

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.

A retrospective analysis of 7 cases of familial mediterranean fever.

BACKGROUND: Familial mediterranean fever (FMF) is a single inherited autoinflammatory disease characterized by periodic fever with relatively short duration of 1 to 3 days and sterile serositis. Although the prevalence rate is highest in the Mediterranean coastal area, a large number of cases have been reported recently by genetic analysis by identification of MEFV (Mediterranean fever) which is responsible gene in Japan too. In outpatient department of rheumatology, diagnosis and treatment of FMF is performed in cases where fever and abdominal pain attack are repeated for a short period of time. PATIENTS AND METHODS: We examined cases in which symptoms considered periodic seizures were repeated, excluding autoimmune diseases, infectious diseases, and malignant tumors. In both cases, genetic analysis is performed as auxiliary diagnosis. RESULTS: Seven cases satisfied the Tel-Hashomer criteria criteria and MEFV gene mutation was detected. Everyone was a female, and half had seizure symptoms at menstruation. Even though there is a difference in the amount of colchicine to be used, either one is effective. CONCLUSION: In cases of periodic symptoms or cases called periodic fever, exclusion diagnosis is carried out, there is a need to suspect FMF, determine the effect of colchicine, and perform genetic analysis.

[A case of anti-PL-7 antibody positive polymyositis with thrombotic microangiopathy].

  A 65-year-old woman with a 17-year history of polymyositis and 8-year history of rheumatoid arthritis who was treated with a low dose of prednisolone and tacrolimus (Tac) was admitted to our hospital because of general malaise and hypertension. Blood tests showed thrombocytopenia, hemolytic anemia with fragmented erythrocytes, and hypercreatinemia. Based on these clinical features, she was diagnosed with thrombotic micro-angiopathy (TMA). Thrombocytopenia and hemolytic anemia with fragmented erythrocytes improved with the discontinuation of Tac and plasma exchange; however, hypertension and renal dysfunction persisted. TMA due to calcineurin inhibitor (CNI) nephropathy was suspected based on the histopathological findings of renal biopsy. However, the condition was atypical of a CNI nephropathy because the trough level of Tac was lower than that reported previously and renal dysfunction persisted after drug discontinuation. She had mild sclerodactylia and Raynaud's symptoms, although the diagnostic criteria for systemic sclerosis (SSc) were not satisfied. Moreover, the patient tested positive for anti PL-7 antibody. The relationship between anti PL-7 antibody and pathogenesis of SSc has been reported. In this case, it was suspected that CNI nephropathy worsened because of the potential basic factors of SSc. These findings indicate that TMA may occur in patients testing positive for anti PL-7 antibody who are treated with Tac.

Cytokine profile in adult-onset Still's disease: Comparison with systemic juvenile idiopathic arthritis.

To compare pro-inflammatory cytokine profiles and kinetics in patients with adult-onset Still's disease (AOSD) to those in patients with systemic juvenile idiopathic arthritis (s-JIA), we analyzed serum cytokine concentrations in 33 patients with AOSD and 77 patients with s-JIA and compared them with clinical features. Patients with AOSD and s-JIA shared a common cytokine profile pattern of a significant increase in IL-18. Patients with AOSD were classified into two subgroups based on serum IL-6 and IL-18 levels. The number of patients with arthritis was significantly higher in the IL-6-dominant subgroup. The cytokine patterns associated with s-JIA and AOSD share common features, such as a significant and predominant increase in IL-18. Distinct IL-6- and IL-18-based cytokine profiles might be responsible for distinct clinical manifestations. The presence of two distinct subgroups in patients with both diseases further supports the view that s-JIA and AOSD share a disease category.

Reliability and clinical utility of Enzyme-linked immunosorbent assay for detection of anti-aminoacyl-tRNA synthetase antibody.

Anti-aminoacyl-tRNA synthetase (ARS) antibody is one of the myositis-specific autoantibodies to make a diagnosis of polymyositis (PM) and dermatomyositis (DM). Recently a new enzyme-linked immunosorbent assay (ELISA) kit of concurrently detected anti-ARS antibodies (anti-Jo-1, anti-PL-7, anti-PL-12, anti-EJ and anti-KS) have become to measure in the clinical setting. To evaluate the reliability of this ELISA kit, we measured anti-ARS antibodies in 75 PM and DM patients using by this ELISA assay and compared them with the results by RNA immunoprecipitation assay. Between the measurements of anti-PL-7, anti-PL-12, anti-EJ and anti-KS autoantibodies by ELISA assay and RNA-IP assay, the concordance rate of reproducibility is 95.1% and the positive agreement rate is 90.9% and negative agreement rate is 96.0% and kappa statistic is 0.841. Between the measurements of existing anti-Jo-1 antibody ELISA kit and anti-ARS antibody ELISA kit, the concordance rate of reproducibility is 96.9%, the positive agreement rate is 100%, negative agreement rate is 96.1% and kappa statistic is 0.909. The lung involvement in patients with PM and DM patients are positive of anti-ARS antibodies and anti-melanoma differentiation associated gene5 (MDA5) antibody at a rate around 70%. Then most life-threatening ILD with anti-MDA5 positive clinically amyopathic dermatomyositis patients could be highly guessed when anti-ARS antibodies are negative.

A case of anti-aminoacyl tRNA synthetase antibody syndrome complicated by hemophagocytic syndrome.

A 48-year-old woman had suffered from a fever and general fatigue, and visited the other hospital for fever elevation in November 2013, at which time interstitial lung disease was revealed. In January 2014, she experienced an eruption in the hand and developed peripheral blood flow damage. Under a diagnosis of adult Still's disease, the patient was administered 0.5 mg of betamethasone as well as cyclosporin at 75 mg/day. In November 2014, general fatigue, fever, and headache were noted, while MRI revealed an enlarged hypophysis and laboratory findings were positive for the anti-pituitary cell antibody, thus a diagnosis of autoimmune hypophysitis was made. Although disease activity was low, she requested hospitalization and was admitted by the Division of Endocrinology and Metabolism at our hospital in May 2015, though only observed. Fever developed again, along with interstitial lung disease, Raynaud's phenomenon, and pain in the crural area again, and we considered the possibility of another disease. After stopping administration of betamethasone and cyclosporin, we made a diagnosis of anti-aminoacyl tRNA synthetase antibody syndrome, and administered methylprednisolone at 500 mg for 3 days as well as prednisolone at 35 mg/day following steroid pulse therapy. Although her condition soon improved, fever, muscle pain, and pancytopenia returned after 3 days. Bone marrow findings revealed the existence of hemophagocytosis, for which we again gave methylprednisolone at 500 mg for 3 days and cyclosporin at 125 mg/day. Thereafter, the patient recovered and was discharged from the hospital.

IgG4-related Kidney Disease in Which the Urinalysis, Kidney Function and Imaging Findings Were Normal.

IgG4-related kidney disease (IgG4RKD) is recognized as a fibroinflammatory disease characterized by storiform fibrosis, lymphoplasmacytic infiltration and a high serum IgG4 level. A renal biopsy is necessary to diagnose IgG4RKD in patients without any lesions in other organs. Nephrologists typically perform renal biopsies in patients with abnormal urinalysis, such as proteinuria or hematuria, or renal failure. However, we experienced a patient with IgG4RKD without abnormalities in the urinalysis, renal function or imaging, who had severe interstitial lesions. We therefore propose that renal biopsies should be considered if patients do not show abnormal urinalysis findings and are suspected to have IgG4RKD.

[Tuberculous peritonitis during etanercept therapy for rheumatoid arthritis].

In August 2010, a 73-year-old woman with rheumatoid arthritis receiving etanercept (ETN) therapy for two years, developed high-fever and abdominal fullness. Though she had not been exposed to tuberculosis, isoniazid prophylaxis was administrated. Antibiotics were not effective. CT images revealed the massive ascites and peritonitis, and Ga scintigraphy demonstrated notable uptake in the peritoneum. Ascites analysis showed an elevated adenosine deaminase activity value (104.9 IU/l) without malignant cells. Moreover, PCR and culture for Mycobacterium tuberculosis were positive. Finally, a diagnosis of tuberculous peritonitis was established. After initiating a standard anti-tuberculosis regimen with four drugs, her clinical condition ameliorated and ascites promptly regressed. Although the tuberculous peritonitis during ETN therapy is rare, this report emphasized the importance of initial suspicion of tuberculosis in these patients with tumor necrosis factor inhibitors such as ETN.