Factors related to elevated serum immunoglobulin G4 (IgG4) levels in a Japanese general population.

BACKGROUND: Elevated serum immunoglobulin G4 (IgG4) concentrations are one of the characteristic findings in IgG4-related disease (IgG4-RD). This study investigated the frequency of elevated serum IgG4 levels and associated factors in a general Japanese population. METHODS: Serum IgG4 concentrations were measured in 1,201 residents of Ishikawa prefecture who underwent general medical examinations. Factors associated with elevated serum IgG4 concentrations were assessed by logistic regression analysis. Participants with elevated serum IgG4 were subjected to secondary examinations. RESULTS: The mean serum IgG4 concentration was 44 mg/dL, with 42 (3.5%) participants having elevated serum IgG4 levels. Age- and sex-adjusted logistic regression analyses showed that male sex, older age, and lower intake of lipids and polyunsaturated fatty acids and higher intake of carbohydrates in daily diet were associated with elevated serum IgG4 concentration. Subgroup analyses in men showed that older age, lower estimated glomerular filtration rates based on serum cystatin C (eGFR-cysC) levels, and higher hemoglobin A1c (HbA1c) levels were associated with elevated serum IgG4 concentration. Analyses in women showed that lower intake of lipids and fatty acids and higher intake of carbohydrates were significantly associated with elevated serum IgG4 concentration. One of the 15 participants who underwent secondary examinations was diagnosed with possible IgG4-related retroperitoneal fibrosis. CONCLUSIONS: Elevated serum IgG4 levels in a Japanese general population were significantly associated with older age, male gender, and dietary intake of nutrients, with some of these factors identical to the epidemiological features of IgG4-RD.

Efficacy of sutimlimab for cold agglutinin disease in a patient on chronic hemodialysis.

Reports of cold agglutinin disease (CAD), an autoimmune hemolytic anemia, in dialysis patients are limited. Recently, sutimlimab for CAD was covered by insurance. Herein, we report a case in which sutimlimab was effective in the treatment of CAD in a patient undergoing hemodialysis (HD). The patient was a 73 year-old Japanese man with an 11 year history of HD for diabetic nephropathy. He was admitted to our hospital for examination and treatment of erythropoiesis-stimulating agent (ESA)-induced hyporesponsive anemia and fatigue, which was present in the previous year October to March when temperatures were cooler. The patient was diagnosed with hemolytic anemia based on decreased hemoglobin levels, elevated reticulocyte count, elevated lactate dehydrogenase levels, and decreased haptoglobin levels. Furthermore, he was diagnosed with CAD based on a positive direct antiglobulin test for C3 and cold agglutinin tests. The patient did not respond well to an elevated dialysate temperature or rituximab therapy. After initiating sutimlimab treatment, an increase in the hemoglobin level was observed despite a decrease in temperature, and his fatigue disappeared. Anemia in hemodialysis patients is generally renal; however, some ESA resistance exists, which may be due to hemolytic anemia. In this case, the use of sutimlimab was effective in controlling hemolytic anemia due to CAD.

A Case of Macrophage Activation Syndrome With Elderly Onset Still's Disease Under Tocilizumab Treatment.

Adult-onset Still's disease in older adults is referred to as elderly onset Still's disease (EOSD). Few cases of tocilizumab (TCZ) use for EOSD management have been reported. Here, we report the case of an 87-year-old Japanese woman with EOSD who was not previously taking any medication. She had fatigue, sore throat, and loss of appetite for several days and gradually experienced difficulty walking. On examination, she was found to have a fever and erythema on the buttocks and extremities. Laboratory tests revealed leukocytosis with neutrophil predominance, elevated C-reactive protein (CRP) levels, and hyperferritinemia. A contrast-enhanced computed tomography scan of the chest to the abdomen showed no abnormalities. Antimicrobial therapy was initiated; however, the fever did not resolve. On day seven, 40 mg/day prednisolone (PDN) was started for EOSD in the absence of an obvious infection or a malignancy. On day 20, the fever recurred, and the patient was started on intravenous methylprednisolone (mPDN) half-pulse therapy (500 mg/day for three days). The fever resolved, and the CRP level decreased to 1 mg/dL but did not return to normal. On day 35, the fever recurred; therefore, 320 mg of TCZ was injected intravenously, and the PDN was tapered. On day 43, the patient tested positive for cytomegalovirus (CMV) antigenemia and improved on ganciclovir. On day 70, the patient developed fever, decreased white blood cell (WBC) and hemoglobin (Hb) levels, high lactate dehydrogenase (LDH) levels, hyperferritinemia, and elevated liver enzymes. Macrophage activation syndrome (MAS) was diagnosed due to hemophagocytosis on bone marrow examination. The patient was started on pulse therapy with glucocorticosteroids and cyclosporine. The patient's fever decreased, and her WBC count and LDH level normalized. The patient continued rehabilitation for muscle weakness due to prolonged hospitalization and high-dose steroid use and was discharged from the hospital on day 150. The findings in this case suggest that the use of TCZ during the remission induction phase of EOSD may lead to MAS.

Long-term outcomes of lupus nephritis with low-level proteinuria: a multicenter, retrospective study.

OBJECTIVES: Reportedly, patients with lupus nephritis (LN) and low-level proteinuria have favorable short-term renal outcomes. We aimed to clarify the long-term renal outcomes and overall survival of them, and the significance of renal biopsy in the early phase with low-level proteinuria. METHODS: We included 144 Japanese patients with biopsy-proven LN from ten hospitals. Low-level proteinuria was defined by a urine protein: creatinine ratio (UPCR) of ≤ 1 g/gCr based on previous reports. The outcomes were end-stage renal disease (ESRD) and death. RESULTS: Compared with patients with high-level proteinuria (UPCR > 1), those with low-level proteinuria (n = 67 [46.5%]) had significantly improved renal function at the time of renal biopsy, and low activity index and chronicity index (CI) while the frequency of class III/IV was similar (79.1% vs 84.4%, p = 0.409). In patients with low-level proteinuria, cyclophosphamide usage was less, and the incidence of ESRD (3.0% vs 13.0%, p = 0.036) or death (3.0% vs 16.9%, p = 0.006) during the total observation period (median, 72 months) were low. Kaplan-Meier analysis showed significant differences in the incidence of ESRD and death between the groups. Multivariate Cox regression analysis revealed that the significant risk factors for ESRD were high CI and hypertension, whereas those for death were increased age and high-level proteinuria. CONCLUSION: Patients with LN and low-level proteinuria had favorable long-term renal and life outcomes. As these patients have substantial active pathological lesions, renal biopsy in the early phase with low-level proteinuria could enable early diagnosis and treatment and thus improve prognosis.

Factors contributing to discrepant estimated glomerular filtration values measured by creatinine and cystatin C in patients with rheumatoid arthritis.

This study aimed to clarify the factors underlying the discrepancy that has been noted between estimated glomerular filtration ratio (eGFR) measured using serum creatinine (Cr) and eGFR using serum cystatin C (CysC) in patients with rheumatoid arthritis (RA) and to identify those patients whose renal function should be evaluated using CysC. We retrospectively evaluated clinical features, disease activity, Steinbrocker radiological staging, and co-morbidities (diabetes mellitus, hypertension, dyslipidemia) in 238 RA patients. eGFR using serum creatinine (eGFR-Cr) and eGFR using serum cystatin C (eGFR-CysC) were calculated using the new Japanese coefficient-modified Modification of Diet in Renal Disease study equation. To clarify the cause(s) of differences of 20% or more between the two eGFRs, we divided our RA patients into Group A (eGFR-Cr/eGFR-CysC ≥ 1.2) and Group B (eGFR-Cr/eGFR-CysC < 1.2), and searched for factors independently related to Group A. Forty-five patients (18.9%) were assigned to Group A, and 193 (81.1%) to Group B. BMI (Odds Ratio [OR] 0.820, 95% confidence interval [CI] 0.675-0.996), Hb (OR 0.633, 95% CI 0.433-0.926), CK (OR 0.773 per 10 units, 95% CI 0.644-0.933), NSAID use (OR 0.099, 95% CI 0.020-0.494), diabetes mellitus (OR 6.024, 95% CI 1.508-24.390) and stage 4 Steinbrocker radiological stage (OR 10.309, 95% CI 2.994-35.714) were identified as independent relevant factors for Group A by a multifactorial analysis. Renal function in RA patients with low BMI, diabetes, anemia and low CK may be overestimated using eGFR-Cr alone, and such patients need to be evaluated using eGFR-CysC.

Antiphospholipid antibody syndrome-associated renal thrombotic microangiopathy improved not with rivaroxaban but with warfarin in a systemic lupus erythematosus patient without lupus nephritis.

A 34-year-old Japanese woman with systemic lupus erythematosus (SLE) was admitted to our hospital for exacerbation of renal dysfunction, hemolytic anemia and thrombocytopenia. Twenty-two years before admission, she was diagnosed with SLE. Eight years before, lupus anticoagulant (LAC) positivity was detected without any thrombotic findings. Fourteen months before, renal function started to worsen. Three months before, unprovoked left leg swelling appeared. She was diagnosed with deep vein thrombosis (DVT) by ultrasonography. Blood examination revealed mild anemia, thrombocytopenia, and renal dysfunction. Rivaroxaban was started after which the left leg swelling subsided. When she was referred to our hospital, LAC was positive, but hypocomplementemia nor elevation of serum anti-double-stranded DNA antibodies was detected. Renal biopsy showed acute and chronic thrombotic microangiopathy (TMA) without concurrent lupus nephritis. Brain magnetic resonance imaging showed new small multiple cerebral infarcts. Antiphospholipid antibody syndrome (APS), causing renal TMA, new cerebral infarction, and DVT was diagnosed. Rivaroxaban was changed to warfarin. Two months after admission, renal impairment improved, and the complete disappearance of DVT and brain infarcts was confirmed. This case suggests that warfarin may be more effective than direct oral anticoagulants in the treatment of APS-associated renal TMA.

A case of IgG4-related tubulointerstitial nephritis and membranous glomerulonephritis during the clinical course of gastric cancer: Imaging features of IgG4-related kidney disease.

We describe an 81-year-old man with immunoglobulin G4-related disease (IgG4-RD) presenting with submandibular gland, lymph node, lung, kidney, aortic wall, and prostate lesions with concomitant gastric cancer. After curative surgical treatment of the gastric cancer, corticosteroid therapy for progressively decreasing renal function was started. Before starting steroid therapy, fluorodeoxyglucose positron emission tomography-computed tomography revealed multiple lesions of IgG4-RD but no metastasis of the cancer. However, the patient died 3 months after initiation of corticosteroid therapy because of recurrence of the gastric cancer. In this case, the imaging features of IgG4-tubulointerstitial nephritis dramatically changed during the clinical course of co-existing gastric cancer. The imaging features of the present case may provide clues to the pattern of spread of IgG4 lesions in the kidney.

A case developing minimal change disease during the course of IgG4-related disease.

We describe a 66-year-old male with immunoglobulin G4-related disease (IgG4-RD) presenting with minimal change disease (MCD). Three years prior to this admission, the patient had been diagnosed with IgG4-RD. The development of sudden massive proteinuria (4+; 16.7 g/gCr) with a weight gain of 8 kg within a two-week period was noted, and nephrotic syndrome was suspected. The patient's serum IgG4 level did not increase and hypocomplementemia was not found. A renal biopsy showed no cellular infiltration in the renal interstitium, and no spiking or bubbling was found on periodic acid methenamine silver staining. On electron microscopy, foot process effacement was seen, but no subepithelial electron-dense deposits were found. The patient was diagnosed with MCD. Ten days after starting prednisolone (60 mg/day), proteinuria was negative. Since IgG4-RD and MCD share a T-helper 2-dominant immunoreaction, the development of MCD in IgG4-RD patients may reflect more than a mere coincidence.