Glomerular lipidosis as a feature of renal-limited macrophage activation syndrome in a transplanted kidney: a case report.

BACKGROUND: Glomerular lipidosis is a rare histological feature presenting the extensive glomerular accumulation of lipids with or without histiocytic infiltration, which develops under various conditions. Among its various etiologies, macrophage activation syndrome (MAS) is a condition reported to be associated with histiocytic glomerular lipidosis. Here we describe the first case of glomerular lipidosis observed in a renal allograft that histologically mimicked histiocytic glomerulopathy owing to MAS. CASE PRESENTATION: A 42-year-old man underwent successful living-donor kidney transplantation. However, middle-grade proteinuria and increased serum triglyceride levels indicative of type V hyperlipidemia developed rapidly thereafter. An allograft biopsy performed 6 months after the transplantation showed extensive glomerular infiltration of CD68+ foam cells (histiocytes) intermingled with many CD3+ T-cells (predominantly CD8+ cells). Furthermore, frequent contact between glomerular T-cells and histiocytes, and the existence of activated CD8+ cells (CD8+, HLA-DR+ cells) were observed by double immunostaining. There was no clinicopathological data suggesting lipoprotein glomerulopathy or lecithin cholesterol acyltransferase deficiency, both of which are well-known causes of glomerular lipidosis. The histological findings were relatively similar to those of histiocytic glomerulopathy caused by MAS. As systemic manifestations of MAS, such as fever, pancytopenia, coagulation abnormalities, hyperferritinemia, increased liver enzyme levels, hepatosplenomegaly, and lymphadenopathy were minimal, this patient was clinicopathologically diagnosed as having renal-limited MAS. Although optimal treatment strategies for MAS in kidney transplant patients remains unclear, we strengthened lipid-lowering therapy using pemafibrate, without modifying the amount of immunosuppressants. Serum triglyceride levels were normalized with this treatment; however, the patient's extensive proteinuria and renal dysfunction did not improve. Biopsy analysis at 1 year after the transplantation demonstrated the disappearance of glomerular foamy changes, but the number of glomerular infiltrating cells remained similar. CONCLUSION: To our knowledge, this is the first reported case of glomerular lipidosis in a transplanted kidney. Increased interaction-activation of histiocytes (macrophages) and CD8+ T-cells, the key pathogenic feature of MAS, was observed in the glomeruli of this patient, who did not demonstrate overt systemic manifestations, suggesting a pathological condition of renal-limited MAS. The clinical effects of triglyceride-lowering therapy were limited, suggesting that hypertriglyceridemia was not the cause of but rather may be a consequence of renal-limited MAS.

Histological transition from minimal change disease to THSD7A-associated membranous nephropathy in a patient receiving long-term steroid treatment: A case report.

RATIONALE: A predominant Th2 immune response is suggested in the pathogenesis of both minimal change disease (MCD) and membranous nephropathy (MN); however, consecutive development of the 2 diseases in a patient is extremely rare. PATIENT CONCERN: A Japanese man, who developed nephrotic syndrome in his 50s and was diagnosed with MCD by renal biopsy, experienced a relapse of proteinuria approximately 3 years later during long-term steroid treatment. Since the proteinuria was resistant to increase in steroid dosage, repeat renal biopsy was performed, which revealed a small amount of glomerular subepithelial immune deposits containing immunoglobulin (Ig)G (dominantly IgG4). Immunostaining for thrombospondin-type-1-domain-containing-7A (THSD7A) was positive on the glomerular capillary walls, whereas that for other causative antigens of MN, such as phospholipase A2 receptor or neural epidermal growth factor-like 1 protein, was negative. Detailed examination found no associated condition, including malignancies and allergic diseases. DIAGNOSIS: The diagnosis of THSD7A-associated idiopathic MN was made. INTERVENTIONS AND OUTCOMES: He received further increased dose of steroids. Thereafter he maintained clinical improvement because his urinary protein level was decreased. LESSONS: The present case suggested that histological transition from MCD to MN is possible and repeat biopsy would be crucial for accurate diagnosis.

Anti-PLA2R Antibody Development During NELL1-Associated Membranous Glomerulonephritis Treatment: A Case Report.

A Japanese man in his early 70s was referred to our hospital because of massive proteinuria. Analysis of his kidney biopsy demonstrated glomerular subepithelial immune deposits containing immunoglobulin (Ig)G, which was dominant for the IgG1 subclass. Immunoperoxidase staining for neural epidermal growth factor-like 1 protein (NELL1) was positive on the glomerular capillary walls, whereas neither serum anti-phospholipase A2 receptor (PLA2R) antibodies nor immunofluorescence staining for PLA2R was positive. Detailed investigation revealed no associated conditions, including underlying malignancies, and thus he was diagnosed as having NELL1-associated idiopathic membranous nephropathy (MN). The patient was treated with steroids, which substantially improved his nephrotic syndrome. Interestingly, serum anti-NELL1 as well as anti-PLA2R antibodies became positive during his clinical course. Serology-based approaches are currently proposed for the treatment of patients suspected of having MN; however, an accurate diagnosis of the present patient would have been difficult if such an approach was performed only at a later phase of the disease. Several target antigens for the glomerular immune deposits observed in patients with MN have recently been identified, and dual positivity of antibodies to these antigens reportedly occurs in some patients. Further accumulation and analyses of such patients are needed to establish more appropriate diagnostic approaches for MN.

Chronic Graft-versus-host Disease-associated Membranous Nephropathy Following Bone Marrow Transplantation, Successfully Treated with Rituximab.

A 67-year-old woman who had undergone bone marrow transplantation 2 years previously for acute myeloid leukemia (AML) developed complications of chronic graft-versus-host disease (cGVHD). She thereafter also developed nephrotic syndrome, and membranous nephropathy (MN) was diagnosed by a renal biopsy. Although the causative antigens of the MN were not detected, immunofluorescence staining showed codominant deposition of immunoglobulins G2 and G3, a finding indicating secondary MN, thereby suggesting an association between MN and cGVHD. Rituximab treatment was initiated, and her nephrotic syndrome gradually improved without relapse of AML. Our present case suggests that rituximab is a safe and effective therapeutic option for cGVHD-associated MN.

Thrombotic microangiopathy with transiently positive direct Coombs test in an adult with poststreptococcal acute glomerulonephritis: a case report.

BACKGROUND: To date, a few case reports have described the association between poststreptococcal acute glomerulonephritis (PSAGN) and hemolytic anemia/thrombocytopenia, both with or without a pathology similar to that of thrombotic microangiopathy (TMA). However, the detailed mechanism leading to the complication of TMA in PSAGN patients remains to be clarified. In contrast, infection with neuraminidase-producing Streptococcus pneumoniae is a well-known cause of TMA, and it has been reported that transient positivity of the direct Coombs test is observed in up to 90% of such patients. CASE PRESENTATION: A 44-year-old man was hospitalized for acute nephritic syndrome 3 weeks after developing pharyngitis. PSAGN was suspected owing to a low complement C3, increased antistreptolysin-O and serum creatinine (5.46 mg/dL), and hematuria/proteinuria. The throat antigen test for group A Streptococcus was positive. He developed hemolytic anemia with thrombocytopenia from hospital day 9. TMA was suspected owing to minimal coagulation abnormalities. ADAMTS-13 activity was normal, whereas the direct Coombs test was transiently positive. Renal biopsy demonstrated glomerular endocapillary proliferation without crescents, but with severe tubulitis and peritubular capillaritis on light microscopy. Immunofluorescence demonstrated C3 deposition along the glomerular capillary walls, and many subepithelial humps were observed on electron microscopy. The deposition of nephritis-associated plasmin receptor (NAPlr), a nephritogenic protein of Streptococcus pyogenes, was observed only in glomeruli. Thus, the histological diagnosis was typical PSAGN, but with atypical severe tubulointerstitial lesions. A positive direct Coombs test is often observed in pneumococcal TMA patients, which is attributed to the exposure of Thomsen-Friedenreich (T) antigen by neuraminidase. As Streptococcus pyogenes is one of the neuraminidase-producing bacteria other than Streptococcus pneumoniae, T-antigen exposure was analyzed in the renal tissue of this patient using labelled peanut lectin as a probe, which has strong and specific binding affinity for T-antigen. Exposure of T-antigen was found on tubular epithelial cells and small vessels in the tubulointerstitial area, but not in the glomeruli of this patient. CONCLUSION: These findings suggest that 2 pathogenic proteins of Streptococcus pyogenes, i.e., NAPlr and neuraminidase, induced glomerular lesions of PSAGN and tubulointerstitial inflammation with TMA, respectively, resulting in severe acute kidney injury in this patient.

Membranous Nephropathy With Monoclonal IgM Lambda Deposits in a Patient With IgM Monoclonal Gammopathy: A Case Report.

We report a case of membranous nephropathy with monoclonal immunoglobulin (Ig)M lambda deposits in a patient with IgM monoclonal gammopathy, in whom histological changes were observed on repeat renal biopsy. A 72-year-old Japanese woman was referred to our hospital because of massive proteinuria. A prominent increase in monoclonal IgM lambda level was identified, and she was diagnosed as having IgM monoclonal gammopathy of undetermined significance. Renal biopsy showed glomerular subepithelial electron-dense deposits that were found to be granular deposits of IgM lambda but not kappa or IgG by immunofluorescence staining, resulting in a diagnosis of membranous nephropathy with monoclonal IgM deposits. The second biopsy, which was performed 2 years later because of exacerbation of her nephrotic syndrome, demonstrated less immunofluorescence staining of IgM, and dominant IgG2 deposition without light chain restriction. Interestingly, immunostaining for thrombospondin-type-1-domain-containing-7A was positive in both renal biopsy tissues, although the second biopsy showed clearly stronger immunoreactivity. The effect of steroid therapy was limited; however, rituximab treatment improved both the hematological and renal abnormalities. Solitary deposition of IgM in membranous nephropathy is a quite rare condition. To our knowledge, this is the first case of monoclonal gammopathy of renal significance presenting as membranous nephropathy with monoclonal IgM deposits, in which chronological immunohistochemical changes were observed and rituximab therapy was effective.

Complete remission of DnaJ homolog subfamily B member 9-positive fibrillary glomerulonephritis following steroid monotherapy in an elderly Japanese woman.

A 74-year-old Japanese woman was referred to our department because of anasarca and massive proteinuria. She was clinically diagnosed with nephrotic syndrome, and renal biopsy showed membranoproliferative glomerulonephritis accompanied by marked glomerular infiltration with macrophages and full-house immunofluorescence glomerular deposition. Furthermore, randomly arranged nonbranching fibrils, approximately 12 nm in diameter, were found by electron microscopy, and immunostaining for DnaJ homolog subfamily B member 9 (DNAJB9), a recently identified diagnostic biomarker of fibrillary glomerulonephritis (FGN), showed positive result, thereby confirming the diagnosis of FGN. Steroid treatment was initiated, and she obtained complete remission of nephrotic syndrome and has maintained it. FGN is an uncommon form of glomerular disease, and reported cases of DNAJB9-positive FGN among Asians, particularly among Japanese population, are rare. There have been no established therapeutic regimens and its renal prognosis is generally unfavorable. The present case suggests that some patients with FGN can achieve favorable clinical outcomes through steroid monotherapy.

Development of anti-glomerular basement membrane glomerulonephritis during the course of IgA nephropathy: a case report.

BACKGROUND: Anti-glomerular basement membrane (GBM) glomerulonephritis does not usually coexist with another glomerulonephritis such as IgA nephropathy. We present a rare case having a combination of these two diseases, and furthermore, histological evaluation could be performed before and after the development of anti-GBM glomerulonephritis over a period of only10 months. CASE PRESENTATION: A 66-year-old woman was admitted with complaints of microscopic hematuria and mild proteinuria for the past 3 years. Serum creatinine level was normal at that time. The first renal biopsy was performed. Light microscopy revealed mesangial proliferative glomerulonephritis with fibro-cellular crescents in one out of 18 glomeruli, excluding one global sclerotic glomerulus. Immunofluorescence (IF) showed IgA and C3 deposition in the mesangium. Therefore, the diagnosis was IgA nephropathy. Eight months later, the patient's serum creatinine suddenly rose to 4.53 mg/dL and urinalysis showed 100 red blood cells per high power field with nephrotic range proteinuria (12.3 g/gCr). The serological tests revealed the presence of anti-GBM antibody at the titer of 116 IU/mL. Treatments were begun after admission, consisting of hemodialysis, plasma exchange, and intravenous methylprednisolone pulse therapy. At 4 weeks after admission, the second renal biopsy was performed. Light microscopy revealed crescents in 18 of 25 glomeruli, excluding six global sclerotic glomeruli. IF showed linear IgG deposition along the GBM in addition to granular IgA and C3 deposition. Based on these findings, the diagnosis of anti-GBM glomerulonephritis and IgA nephropathy was confirmed. Renal function was not restored despite treatment, but alveolar hemorrhage was prevented. CONCLUSIONS: We report a patient with a diagnosis of anti-GBM disease during the course of IgA nephropathy. This case strongly suggests that the presence of autoantibodies should be checked to rule out overlapping autoimmune conditions even in patient who have previously been diagnosed with chronic glomerulonephritis, such as IgA nephropathy, who present an unusually rapid clinical course.

Immunoadsorption therapy for neuromyelitis optica spectrum disorders long after the acute phase.

Neuromyelitis optica (NMO) is a severe inflammatory demyelinating disease with exacerbations involving recurrent or bilateral optic neuritis and longitudinally extensive transverse myelitis. Pulse steroid therapy is recommended as the initial, acute-phase treatment for NMO. If ineffective, treatment with plasma exchange (PE) should commence. However, no evidence exists to support the effectiveness of PE long after the acute phase. Immunoadsorption therapy (IA) eliminates pathogenic antibodies while sparing other plasma proteins. With IA, side effects of PE resulting from protein substitution can be avoided. However, whether IA is effective for NMO remains unclear. We describe a patient with anti-aquaporin-4-positive myelitis who responded to IA using a tryptophan polyvinyl alcohol gel column that was begun 52 days after disease onset following the acute phase. Even long after the acute phase when symptoms appear to be stable, IA may be effective and should not be excluded as a treatment choice.

Role of (p)ppGpp in biofilm formation and expression of filamentous structures in Bordetella pertussis.

Bordetella pertussis, the causative agent of whooping cough, is highly adapted to cause human infection. The production of virulence factors, such as adhesins and toxins, is just part of an array of mechanisms by which B. pertussis causes infection. The stringent response is a global bacterial response to nutritional limitation that is mediated by the accumulation of cellular ppGpp and pppGpp [termed together as (p)ppGpp]. Here, we demonstrate that production of (p)ppGpp was controlled by RelA and SpoT proteins in B. pertussis, and that mutation-induced loss of both proteins together caused deficiencies in (p)ppGpp production. The (p)ppGpp-deficient mutants also exhibited defects in growth regulation, decreases in viability under nutritionally limited conditions, increases in susceptibility to oxidative stress and defects in biofilm formation. Analysis of the secreted proteins and the respective transcripts showed that lack of (p)ppGpp led to decreased expression of fim3 and bsp22, which encode a fimbrial subunit and the self-polymerizing type III secretion system tip protein, respectively. Moreover, electron microscopic analysis also indicated that (p)ppGpp regulated the formation of filamentous structures. Most virulence genes - including fim3 and bsp22 - were expressed in the Bvg(+) phase during which the BvgAS two-component system was activated. Although fim3 and bsp22 were downregulated in a (p)ppGpp-deficient mutant, normal expression of fhaB, cyaA and ptxA persisted. Lack of coherence between virulence gene expression and (p)ppGpp production indicated that (p)ppGpp did not modulate the Bvg phase. Taken together, our data indicate that (p)ppGpp may govern an as-yet-unrecognized system that influences B. pertussis pathogenicity.

Neutrophil extracellular trap components in fibrinoid necrosis of the kidney with myeloperoxidase-ANCA-associated vasculitis.

In response to antineutrophil cytoplasmic antibody (ANCA), activated neutrophils release decondensed chromatin associated with cytoplasmic granular proteins composed of proteolytic enzymes and myeloperoxidase (MPO); these complexes are named neutrophil extracellular traps (NETs). NET formation requires peptidylarginine deiminase 4 (PAD4) to citrullinate chromatin histones and also MPO and neutrophil elastase to aid in decondensation and release of chromatin. Immunostaining of renal biopsy revealed that NET components of citrullinated histone, MPO and PAD4 were concurrently deposited both around fibrinoid necrosis in necrotizing glomerulonephritis in the early focal phase of ANCA-associated polyangiitis and along an interlobular arterial wall.