Successful treatment with bortezomib and dexamethasone for proliferative glomerulonephritis with monoclonal IgG deposits in multiple myeloma: a case report.

BACKGROUND: Proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) is a form of renal involvement by monoclonal IgG deposits that was found in mesangial, subendothelial or subepithelial regions. The distribution of glomerular deposits was completely different from that in monoclonal immunoglobulin deposition disease. PGNMID is reported to be rarely associated with a hematological malignancy. Previously, only five cases of PGNMID with multiple myeloma have been reported. However, the pathogenic relationship between PGNMID and multiple myeloma was unclear because a detailed description was not provided. We report that a patient with PGNMID associated with multiple myeloma was treated with bortezomib and dexamethasone and underwent the second renal biopsy after treatment, showing that chemotherapy was effective for PGNMID clinically and pathologically. CASE PRESENTATION: A 75-year-old man presented with progressive leg edema, had nephrotic range proteinuria, hypoalbuminemia, moderate renal failure, and occult blood in his urine. Electrophoresis results showed serum and urinary monoclonal spikes of IgGκ type immunoglobulin. A renal biopsy specimen showed lobular mesangial proliferation with mesangiolysis, glomerular micro-aneurysm, and endocapillary hypercellularity. Immunofluorescence results revealed strong granular capillary and mesangial staining for IgG1, C3 and κ light chain in glomeruli without tubular deposits of any immunoglobulin. Electron microscopy also showed dense granular deposits in subendothelial and mesangial areas. PGNMID associated with multiple myeloma (IgGκ type) was diagnosed on the basis of a subsequent bone marrow examination. Bortezomib and dexamethasone therapy significantly reduced proteinuria and elevated serum albumin level. Eight months later, the second renal biopsy showed no active lesions and that the IgG1 and κ light chain deposits had drastically disappeared. CONCLUSIONS: This is the first case of PGNMID with multiple myeloma successfully treated with bortezomib and dexamethasone in which comparative renal biopsies were performed before and after treatment. Our findings suggest the pathogenesis of PGNMID and therapeutic options for PGNMID.

Reappraisal of PLA2R1 in membranous nephropathy: immunostaining method influence and association with IgG4-dominant phenotype.

The M-type phospholipase A2 receptor (PLA2R1) was identified recently as a specific target antigen in idiopathic membranous nephropathy. However, the influence of different sample preparation techniques on the immunostaining of PLA2R1 is unclear. Previous studies have identified IgG4 as the dominant subclass of PLA2R1 antibodies. However, it remains unclear whether the IgG subclass profiles of the glomerular immune complexes of PLA2R1-positive and -negative idiopathic membranous nephropathy cases are similar. To address these questions, we conducted the present study of 58 idiopathic membranous nephropathy cases. The PLA2R1 positivity rate for the paraffin-embedded sections was 61%, whereas that for the frozen sections was 65%. Nonspecific background staining was observed in the frozen sections. Discrepancies between different sample preparations occurred in three cases (6%); two cases were PLA2R1-positive in paraffin sections and PLA2R1-negative in frozen sections and one case was PLA2R1-negative in paraffin sections and PLA2R1-positive in frozen sections. Regarding the IgG subclass profile, 89% of the PLA2R1-positive cases demonstrated the IgG4-dominant/codominant phenotype versus 31% of the PLA2R1-negative cases (p < 0.001). Clinical characteristics and pathological findings did not significantly differ between PLA2R1-positive and -negative cases. In summary, the PLA2R1 immunofluorescence results were not affected by the different sample preparation techniques, although paraffin-embedded sections were preferred for the histological detection of PLA2R1 because of the nonspecific background staining observed in frozen sections. The observed lower frequency of the non-IgG4-dominant/codominant phenotype in PLA2R1-negative idiopathic membranous nephropathy cases may suggest that there are heterogeneous subgroups of this disease.

Calcification of the thoracic aorta determined by three-dimensional computed tomography predicts cardiovascular complications in patients undergoing hemodialysis.

PURPOSE: In patients on dialysis, the most common cause of death is cardiovascular disease. This is caused, at least in part, by excessive vascular calcification. Studies that have examined coronary calcification have been published, but these measurements require expensive equipment. Here, we used computed tomography to determine aortic calcification and evaluated these data as prognostic markers for cardiovascular disease. METHODS: Computed tomography with contrast medium was performed on 49 patients undergoing hemodialysis (29 males and 20 females; average age, 68.9 ± 11.0 years). A calcification score (CS) was defined as the ratio of the volume of vascular calcification to the volume of the thoracic aorta. All patients were monitored for cardiovascular end points, which included cerebral infarction or hemorrhage, myocardial infarction, electrocardiographic, or echocardiographic abnormalities that suggested myocardial ischemia, cardiac surgery, leg amputation, and hospitalization or death due to heart failure. RESULTS: Patients were followed for 3 years, with 12 patients reaching the end point. Both high CS (p = 0.007) and male gender (p = 0.009) were significantly associated with cardiovascular events. In contrast, events were not related to age, dialysis duration, diabetes mellitus, smoking status, low-density lipoprotein cholesterol level, pulse-wave velocity, maximum intima-media thickness of the carotid artery wall, systolic blood pressure, or left ventricular hypertrophy. Multiple logistic regression analysis revealed that a high baseline CS was a significant predictor for cardiovascular events (p < 0.05). CONCLUSIONS: Calcification of the thoracic aorta determined by three-dimensional computed tomography predicts cardiovascular complications in patients on hemodialysis.

Basic helix-loop-helix transcriptional factor MyoR regulates BMP-7 in acute kidney injury.

MyoR was originally identified as a transcriptional repressor in embryonic skeletal muscle precursors, but its function in adult kidney has not been clarified. In this study, we tried to clarify the functional role of MyoR using MyoR(-/-) mice. Cisplatin induced a significantly higher degree of severe renal dysfunction, tubular injury, and mortality in MyoR(-/-) mice than in wild-type mice. The injection of cisplatin significantly increased the number of apoptotic cells in the kidney tissues of MyoR(-/-) mice, compared with that in wild-type mice. To clarify the mechanism of severe cisplatin-induced damage and apoptosis in MyoR(-/-) mice, we focused on the p53 signaling pathway and bone morphogenic protein-7 (BMP-7). Treatment with cisplatin significantly activated p53 signaling in cultured renal proximal tubular epithelial cells (RTECs) in both wild-type and MyoR(-/-) mice, but no significant difference between the groups was observed. The injection of cisplatin significantly increased the expression of BMP-7 in the kidney tissues of wild-type mice, but no increase was observed in the MyoR(-/-) mice. Treatment with cisplatin significantly increased the expression of BMP-7 in cultured RTECs from wild-type mice but not in those from MyoR(-/-) mice. Moreover, treatment with recombinant BMP-7 rescued the cisplatin-induced apoptosis in RTECs from MyoR(-/-) mice. Taken together, our results demonstrate a new protective role of MyoR in adult kidneys that acts through the regulation of BMP-7.

Eicosapentaenoic acid regulates IκBα and prevents tubulointerstitial injury in kidney.

Fish oil containing n-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is well known to prevent the progression of IgA nephropathy. However, the mechanism through which fish oil prevents the progression of renal injury remains uncertain. We tried to clarify the effects of EPA on tubulointerstitial injury in the kidney both in vivo and in vitro. We examined the effects of EPA, especially to focus on nuclear factor kappa B (NF-κB), using Thy-1 nephritis models. Also the mechanism of EPA was investigated using small-interfering RNA (siRNA) in lipopolysaccharide (LPS)-stimulated proximal tubular epithelial cells (PTECs). In Thy-1 nephritis models, EPA significantly inhibited tubulointerstitial injury and the infiltration of macrophages into tubulointerstitial lesions except severe glomerular injury at early stage. Compared with control animals, NF-κB activation was significantly augmented in the Thy-1 nephritic kidney. However, treatment with EPA significantly reduced NF-κB activation, down-regulated the expressions of NF-κB-dependent molecules. Also in LPS-stimulated PTECs, LPS augmented NF-κB activation and the expression of NF-κB-dependent molecules. As in the case with the Thy-1 nephritis models, treatment with EPA inhibited them, prevented the degradation of IκBα in LPS-stimulated PTECs. Pre-treatment with siRNA for IκBα abolished the inhibitory effect of EPA on LPS-induced NF-κB activation, suggesting that EPA inhibited NF-κB activation by regulating IκBα. Our results indicate that EPA prevents the early progression of tubulointerstitial injury in Thy-1 nephritis models, and the inhibitory effect of EPA on the expression of inflammatory molecules via the regulation of IκBα in cultured cells may explain this mechanism.