Tubulointerstitial nephritis with monotypic lympho-plasmacytic infiltrates in a patient with primary Sjögren's syndrome accompanied by IgA-type monoclonal gammopathy.

BACKGROUND: Although most cases of tubulointerstitial nephritis in paraproteinemia are monoclonal light chain deposition-mediated, interstitial nephritis as neoplastic interstitial cell infiltration has rarely been described. On the other hand, lympho-plasma-cell-rich tubulointerstitial nephritis, in which the infiltrative cells are usually polytypic, is often evident in primary Sjögren's syndrome (pSS). Herein we present a rare case of pSS in a patient who had been diagnosed as having IgA kappa-type monoclonal gammopathy of undetermined significance (MGUS) and developed tubulointerstitial nephritis with monotypic (IgA kappa) lympho-plasmacytic infiltrates. CASE PRESENTATION: A 74-year-old Japanese woman with pSS who had been diagnosed as having IgA kappa-type MGUS developed progressive renal dysfunction. Renal biopsy revealed tubulointerstitial nephritis with abundant plasma cell-rich mononuclear cell infiltrates without atypia. Immunohistochemical staining for immunoglobulins and light chains showed that most infiltrates were positive for IgA and kappa. Most of the infiltrative cells were positive for CD38 and CD138, and cells positive for CD 19 and CD 45 were also widely evident. Electron microscopy and immunofluorescence studies revealed no apparent immunological deposits in the glomeruli and tubules. Bone marrow and whole-body radiological examinations revealed no findings suggestive of multiple myeloma or lymphoma. Renal function improved rapidly with prednisolone 40 mg daily and has been maintained at the same level on low-dose prednisolone and azathioprine for 18 months. CONCLUSION: Tubulointerstitial nephritis with monotypic cell infiltrates, without immunological deposits, is a quite rare histological picture in MGUS, and might be a unique renal manifestation in patients with pSS.

Dysregulated heme oxygenase-1low M2-like macrophages augment lupus nephritis via Bach1 induced by type I interferons.

BACKGROUND: Innate immunity including macrophages (Mϕ) in lupus nephritis (LN) has been gaining attention, but roles of Mϕ in LN remain uncertain. METHODS: Immunohistochemical staining was performed to determine CD68, CD163, heme oxygenase (HO)-1 (a stress-inducible heme-degrading enzyme with anti-inflammatory property), pSTAT1, and CMAF-expressing Mϕ in the glomeruli of patients with LN. Effects of type I interferons on the expression levels of CD163, HO-1, BTB and CNC homology 1 (Bach1; a transcriptional HO-1 repressor), interleukin (IL)-6, and IL-10 by human M2-like Mϕ, which were differentiated in vitro from peripheral monocytes with macrophage colony-stimulating factor, were assessed by RT-PCR and immunocytostaining. Clinical manifestations, anti-double-stranded DNA (anti-dsDNA), and local HO-1 expression were compared in Bach1-deficient and wild-type MRL/lpr mice. RESULTS: The number of glomerular M2-like Mϕ correlated with the amounts of proteinuria in patients with LN. Unlike monocyte-derived M2-like Mϕ, HO-1 expression was defective in the majority of glomerular M2-like Mϕ of patients with LN. Stimulation of human M2-like Mϕ with type I interferons led to reduced HO-1 expression and increased Bach1 and IL-6 expression. Bach1-deficient MRL/lpr mice exhibited increased HO-1 expression in kidneys, prolonged survival, reduced urine proteins, and serum blood urea nitrogen levels, but serum anti-dsDNA antibody levels were comparable. Increased expression of CD163 and HO-1 was found in peritoneal Mϕ from Bach1-deficient MRL/lpr mice. CONCLUSIONS: Our data suggest that dysregulated M2-like Mϕ play a proinflammatory role in LN. Bach1 is a potential therapeutic target that could restore the anti-inflammatory property of M2 Mϕ.

Initial predictors of poor survival in myositis-associated interstitial lung disease: a multicentre cohort of 497 patients.

OBJECTIVE: To identify initial predictors of poor survival in patients with PM/DM-associated interstitial lung disease (ILD). METHODS: We established a multicentre retrospective cohort of incident cases of PM/DM-associated ILD from 44 institutions across Japan (Multicentre Retrospective Cohort of Japanese Patients with Myositis-associated ILD, JAMI). Inclusion criteria were an onset age ⩾16 years; PM/DM or clinically amyopathic DM according to the published criteria; imaging evidence of ILD; and availability of serum samples for assays of autoantibodies such as anti-melanoma differentiation-associated gene 5 and anti-aminoacyl tRNA synthetase. We collected demographic data and clinical characteristics recorded at the time of diagnosis, as well as follow-up survival data. Predictors of ILD-related mortality were identified by univariate and multivariate analyses. RESULTS: JAMI enrolled a cohort of 497 patients with PM (15%), classic DM (32%) and clinically amyopathic DM (53%). During the observation period (median 20 months), 76 died of respiratory insufficiency directly related to ILD. Univariate analysis revealed several initial parameters associated with ILD mortality, including demographic, clinical, laboratory, imaging and autoantibody variables. We used multivariate analysis with a stepwise selection of parameters to generate an appropriate predictive model, and identified the following independent risk factors for ILD mortality: age at onset ⩾60 years [hazard ratio (HR) = 4.3, 95% CI: 2.4, 7.5], CRP ⩾1 mg/dl (HR = 2.6, 95% CI: 1.5, 4.8), peripheral capillary oxygen saturation <95% (HR = 2.0, 95% CI: 1.2, 3.4) and anti-melanoma differentiation-associated gene 5 antibody (HR = 7.5, 95% CI: 2.8, 20.2). CONCLUSION: We established a large cohort of incident cases of PM/DM-associated ILD, and successfully identified independent predictors of short-term ILD mortality.