Investigation of Clinical Features and Association between Vascular Endothelial Injury Markers and Cytomegalovirus Infection Associated with Thrombotic Microangiopathy in Patients with Anti-Neutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis: Case-Based Research.

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) can occasionally trigger thrombotic microangiopathy (TMA). Cytomegalovirus (CMV) may be reactivated during intensive immunosuppressive therapy for AAV and cause TMA. Therefore, we aimed to evaluate the clinical features of and the association between vascular endothelial injury markers and TMA due to CMV in patients with AAV. A 61-year-old female was diagnosed with AAV and severe kidney injury. Immunosuppressive therapy gradually improved her symptoms and laboratory findings. However, 2 weeks after induction therapy initiation, she exhibited altered consciousness, a significant decrease in platelet count, and hemolytic anemia, resulting in a TMA diagnosis. Plasma exchange did not improve TMA findings and routine screening test revealed CMV infection. Ganciclovir injection improved the infection and TMA findings. Consequently, we diagnosed her with CMV-induced TMA. Both AAV and CMV may induce severe vascular endothelial injury, potentially leading to TMA development. CMV-induced TMA should be considered when TMA develops during induction therapy against AAV. Moreover, of the three serum markers of vascular injury-serum sulfatides, soluble thrombomodulin, and pentraxin 3-serum sulfatides may be associated with the development of TMA, and a high level of soluble thrombomodulin may be associated with the development of CMV viremia during the clinical course of AAV.

Enterocolic granulomatous phlebitis associated with epidermal growth factor-containing fibulin-like extracellular matrix protein 1 deposition and focal amyloid properties: A case report.

A woman in her 60s with rheumatoid arthritis was admitted with fever and abdominal pain. Laparoscopic examination with the differential diagnosis of peritoneal neoplasm and infection revealed granulomatous phlebitis in the resected greater omentum. Amorphous eosinophilic deposits observed in the resected tissue exhibited focal, weak positivity for Congo red but were strongly positive for thioflavin S, confirming their focal amyloid properties. Marked degeneration of elastic fibers was also evident. Electron microscopy revealed deposits around the affected elastic fibers. Immunohistochemistry revealed the deposition of epidermal growth factor-containing fibulin-like extracellular matrix protein 1 (EFEMP1) along with T-cell-predominant lymphocytic inflammation. The definitive diagnosis was granulomatous enterocolic lymphocytic phlebitis (ELP) associated with EFEMP1 deposition exhibiting focal amyloid properties (EFEMP1/AEFEMP1), supported by proteomics analysis. This type of vasculitis is similar to amyloid-ß-related angiitis of the central nervous system. Thus, we speculate that granulomatous ELP also results from an immune response that recognizes EFEMP1/AEFEMP1 deposits as foreign material and attempts to remove them. Confirmation of EFEMP1/AEFEMP1 deposition with Congo red staining is challenging, particularly in the presence of inflammation, and warrants comprehensive evaluation.

Lysinuric protein intolerance exhibiting renal tubular acidosis/Fanconi syndrome in a Japanese woman.

Lysinuric protein intolerance (LPI), caused by pathogenic variants of SLC7A7, is characterized by protein aversion, failure to thrive, hyperammonemia, and hepatomegaly. Recent studies have reported that LPI can cause multiple organ dysfunctions, including kidney disease, autoimmune deficiency, pulmonary alveolar proteinosis, and osteoporosis. We report the case of a 47-year-old Japanese woman who was initially diagnosed with renal tubular acidosis (RTA), Fanconi syndrome, and rickets. At the age of 3 years, she demonstrated a failure to thrive. Urinary amino acid analysis revealed elevated lysine and arginine levels, which were masked by pan-amino aciduria. She was subsequently diagnosed with rickets at 5 years of age and RTA/Fanconi syndrome at 15 years of age. She was continuously treated with supplementation of vitamin D3, phosphate, and bicarbonate. A renal biopsy at 18 years of age demonstrated diffuse proximal and distal tubular damage with endocytosis-lysosome pathway abnormalities. Distinctive symptoms of LPI, such as protein aversion and postprandial hyperammonemia were not observed throughout the patient's clinical course. The patient underwent a panel-based comprehensive genetic testing and was diagnosed with LPI. As the complications of LPI involve many organs, patients lacking distinctive symptoms may develop various diseases, including RTA/Fanconi syndrome. Our case indicates that proximal and distal tubular damages are notable findings in patients with LPI. The possibility of LPI should be carefully considered in the management of RTA/Fanconi syndrome and/or incomprehensible pathological tubular damage, even in the absence of distinctive symptoms; furthermore, a comprehensive genetic analysis is useful for diagnosing LPI.

Immunoelectron microscopy findings in a patient with C3 glomerulonephritis.

We performed a kidney biopsy in a 36-year-old man to evaluate microscopic hematuria and proteinuria. Light microscopy showed increased mesangial matrix and partial swelling of the glomerular basement membrane (GBM), and immunofluorescence showed positive staining only for C3. Immunoelectron microscopy showed that gold particle-labeled C3 was localized in the electron-dense and moderately electron-dense deposits shown by electron microscopy in the mesangium, the thickened GBM near the paramesangium, and the thickened distal portion of the GBM but was not localized in the non-thickened GBM. Gold-labeled immunoglobulin G, κ, and λ were not seen. C3 glomerulonephritis was more evident in gold-labeled electron microscopy, which further clarified the localization of C3 deposition.

Histiocytic Glomerulopathy With Noncrystalline Inclusion Associated With IgG-Kappa Plasma Cell Dyscrasia.

The kidney pathology of monoclonal gammopathy of renal significance varies greatly. In this report, we present a woman in her 20s with nephrotic syndrome and monoclonal immunoglobulin G kappa (serum and urine) without diabetes. She had a family history of nephrotic syndrome as well as hematologic and connective tissue disorders. A kidney biopsy showed nodular glomerulosclerosis, with the glomerular capillary full of histiocytes, which were strongly positive for kappa, not lambda. Immunoelectron microscopy revealed that histiocytes had infiltrated the glomerular subendothelial space, and enlarged lysosomes of histiocytes contained kappa light chains, without apparent crystalline formation. Bone marrow examination was negative for malignancy; thus, we diagnosed this case as histiocytic glomerulopathy with noncrystalline inclusion associated with immunoglobulin G-kappa plasma cell dyscrasia. Hematologic treatment with bortezomib and daratumumab decreased her level of serum kappa chain and proteinuria. Two years after diagnosis, her kidney function remained normal, urinary protein level decreased to 1 g/d, and free light-chain ratio decreased to 3.1.

AL-Kappa Primary Amyloidosis with Apolipoprotein A-IV Deposition.

A 70-year-old woman with complaints of edema, general malaise, and hypotension was diagnosed with renal amyloidosis, and laser microdissection mass spectrometry revealed her amyloidosis to predominantly comprise the apolipoprotein A-IV type. The M-protein turned from negative to positive during the course, and a bone marrow biopsy showed smoldering myeloma. Treatment with bortezomib and dexamethasone failed to save her from heart failure six months after the onset. Western blotting of urine samples at the time of the renal biopsy showed that amyloid light-chain κ amyloidosis had been present since the onset. Unlike the myeloma, Congo red staining was positive in the plasma cells of the bone marrow.

Combined light chain crystalline tubulopathy, podocytopathy, and histiocytosis associated with Bence-Jones κ protein diagnosed via immuno-electron microscopy.

We herein report a case of a combined crystalline light chain tubulopathy, podocytopathy, histiocytosis, and cast nephropathy in a patient with monoclonal gammopathy of renal significance (MGRS). A 66-year-old female with impaired renal function was referred to our department. Despite intravenous fluid resuscitation, the kidney function worsened progressively; thus, a kidney biopsy was performed. The kidney biopsy revealed light chain proximal tubulopathy (LCPT) with crystals, light chain crystal podocytopathy (LCCP), crystal-storing histiocytosis (CSH), and light chain cast nephropathy (LCCN). Of note, LCCP and CSH were diagnosed via electron microscopy. Serum and urine immunoelectrophoresis (IEP) revealed the presence of monoclonal Bence-Jones protein and free κ light chains. Bone marrow aspiration showed < 10% plasma cell proliferation. Thus, we had encountered a rare case in which a variety of kidney lesions were combined with MGRS. Most of the LCPT, LCCP, and CSH cases show monoclonal IgG κ, while our case showed Bence-Jones protein κ.

Primary Myelofibrosis-Related Renal Disorders Treated with a Janus Kinase Inhibitor.

Extramedullary hematopoiesis is widely known to occur in patients with primary myelofibrosis (PMF). Autopsy studies on individuals with PMF revealed that extramedullary hematopoiesis occurred in the kidneys in 35% of the cases, but there is little awareness regarding such lesions. A 63-year-old man was diagnosed with PMF based on a detailed examination of persistent high white blood cells. An examination of the patient's medical records revealed an increased white blood cell count, deterioration of kidney function, and urinary protein excretion developed simultaneously. Thus, a kidney biopsy was performed. Advanced lymphocyte invasion was recognized in the interstitial tissue, and the tubular structure was highly disrupted. Based on these findings, he was diagnosed with interstitial nephritis. However, because of the large number of cells with nuclear atypia in the stroma, additional immunohistochemical staining was also performed, such as glycophorin A, naphthol AS-D, myeloperoxidase, and CD42b. As a result, invasion of three lineages of immature cells, erythroblasts, megakaryocytes, and granulocytes, was identified. Renal dysfunction resulting from interstitial cellular infiltration due to extramedullary hematopoiesis was therefore diagnosed. Treatment with ruxolitinib was initiated after a renal biopsy and the rate of decline in renal function was slightly reduced. Although, in myeloproliferative disorders, proliferative glomerular lesions are widely considered to be renal disorders, there is little awareness regarding interstitial lesions. Extramedullary hematopoiesis of the kidney in PMF is not uncommon, but 40% of cases are reportedly misdiagnosed as interstitial nephritis. Because extramedullary hematopoiesis can be controlled by ruxolitinib, early detection is important.

Collagenofibrotic Glomerulopathy.

Collagenofibrotic glomerulopathy or LMX1B-associated nephropathy is a rare disease in which type III collagen accumulates in the glomeruli. We herein report a 64-year-old Japanese woman with an elevated serum creatinine level and persistent proteinuria for 7 years. An electron microscopic study using tannic acid showed curved and frayed collagen fibers within mesangial and subendothelial regions compatible with type III collagen depositions. The distribution of type IV collagen α1-6 chains was normal. Since no pathogenic mutations were identified in the LMX1B gene, she was diagnosed with collagenofibrotic glomerulopathy and treated with angiotensin II receptor blocker and calcium antagonist to control her blood pressure.

Fibrillary Glomerulopathy with a High Level of Myeloperoxidase-ANCA: A Case Report.

An elderly woman was admitted with the chief complaint of gross hematuria. Laboratory values indicated a high myeloperoxidase-ANCA level. In renal histological examination, 40% of the glomeruli showed crescent formation, but immunofluorescence staining showed positivity for IgG, C3, and C1q. Furthermore, the deposition of fibrils in the glomerulus was noted on electron microscopy, and immunohistochemical staining showed strong positivity for DNA-J heat shock protein family member B9 (DNAJB9). Crescent formation is a common feature of fibrillary glomerulonephritis (FGN). Thus, in ANCA-positive crescentic glomerulonephritis, immunohistochemical assessments for immunoglobulins and DNAJB9, as well as electron microscopy, are important to correctly diagnose FGN.

An autopsy case of amyloid tubulopathy exhibiting characteristic spheroid-type deposition.

An 84-year-old woman with a history of haemodialysis for renal failure from approximately 1 year before death. Autopsy revealed numerous spheroid-type amyloid deposits in the kidney that were observed mainly in the interstitium but not the glomeruli and vessels. In addition, intracytoplasmic small globular amyloid deposits in the proximal tubules in addition to amyloid casts were identified. Immunohistochemistry and proteomic analyses indicated these deposits were composed of λ light chains. Amyloid deposition was also found in the lung and heart. λ-type monoclonal protein was detected in her serum and increased numbers of CD138-positive cells with λ-restriction was observed in the bone marrow. The case was diagnosed as amyloid tubulopathy (AT) associated with systemic ALλ amyloidosis related to plasma cell neoplasm. This case indicates that AT is associated with ALλ amyloidosis, which developed systemically with characteristic amyloid deposition forms. These pathological features may be associated with her rapid progressive renal failure.

Nephrotic Syndrome due to Focal Segmental Glomerulosclerosis Complicating Sjögren's Syndrome: A Case Report and Literature Review.

BACKGROUND: Renal tubular acidosis and tubulointerstitial nephritis constitute the primary renal complications associated with Sjögren's syndrome (SjS), and glomerulonephritis and nephrotic syndrome are rare. CASE PRESENTATION: A 79-year-old Japanese woman presented with bilateral leg edema and weight gain and was diagnosed with nephrotic syndrome. In addition, she reported a 5-year history of dryness of mouth and was diagnosed with SjS. Renal biopsy revealed segmental glomerulosclerosis, with some specimens showing collapse of the glomerular capillary loops, proliferation of glomerular epithelial cells, and sclerotic lesions at the tubular poles, without spike formation, double contour lesions, or any other changes of the glomerular basement membrane. Immunofluorescence staining showed no immune complex (immunoglobulin IgG, IgA, or IgM) or complement (C3) deposition in the glomerular capillary walls. Based on these findings, she was diagnosed with focal segmental glomerulosclerosis (FSGS). The administration of steroid and cyclosporine achieved complete remission of nephrotic syndrome. CONCLUSION: Although glomerular diseases are rare, a variety of glomerular lesions including FSGS are reported in patients with SjS. Therefore, renal biopsy is warranted in patients with SjS presenting with severe urinary abnormalities.

Coexistence of Anti-Glomerular Basement Membrane Glomerulonephritis and Membranous Nephropathy in a Female Patient with Preserved Renal Function.

Renal prognosis for anti-glomerular basement membrane (GBM) glomerulonephritis is poor. The greater the amount of anti-GBM antibody binding the antigen (type IV collagen of the glomerular basement membrane), the greater the number of crescents that develop in glomeruli, resulting in progression of renal impairment. Immunofluorescence staining reveals linear IgG depositions on glomerular capillary walls. Membranous nephropathy (MN) is one of the most common causes of nephrotic syndrome in middle-aged to elderly patients. Immune complex is deposited in the sub-epithelial space of the glomerulus resulting in the development of a membranous lesion. Immunofluorescence staining reveals granular IgG depositions on glomerular capillary walls. Coexisting anti-GBM glomerulonephritis and MN are rare and, here we report a case of coexisting anti-GBM glomerulonephritis and MN with preserved renal function. There are some cases of coexisting anti-GBM glomerulonephritis and MN do not show severely decreased renal function. A 76-year-old Japanese woman presented with nephrotic syndrome, microscopic hematuria, and was positive for anti-GBM antibody. Kidney biopsy revealed linear and granular IgG depositions in glomerular capillary walls, crescent formations, and electron-dense deposits in the sub-epithelial space. She was diagnosed with anti-GBM glomerulonephritis and MN. Steroid and cyclosporine therapy achieved complete remission, and kidney function was preserved. In conclusion, coexisting anti-GBM glomerulonephritis and MN can have preserved renal function. IgG subclass of deposited anti-GBM antibody may be associated with the severity of anti-GBM glomerulonephritis. In addition, in the case of nephrotic syndrome with hematuria, we should consider the possibility of coexisting anti-GBM glomerulonephritis and MN.

A Case of Lipoprotein Glomerulopathy with apoE Chicago and apoE (Glu3Lys) Treated with Fenofibrate.

Lipoprotein glomerulopathy (LPG) is characterized by the accumulation of lipoprotein thrombi within glomerular capillaries. This rare disorder is associated with various types of mutations in the apolipoprotein E gene (apoE). Herein, we present a case of LPG with a combination of apoE Chicago (Arg147Pro) and apoE (Glu3Lys) mutations. A 51-year-old Japanese woman presented with severe (3+) proteinuria. The initial renal biopsy showed glomerular capillary dilation and occlusion with lipid granules, a specific characteristic of LPG. Phenotype, genotype, and apoE DNA sequence analyses detected 2 mutations as described above within the same allele. Although both mutations had already been reported in 1 case of LPG each, this is the first time that the combination of the 2 mutations was identified in the same case. Familial analysis detected the same mutations in the patient's mother. However, she has not suffered LPG thus far. In addition, a re-analysis of the previous LPG case with apoE (Glu3Lys) also identified the apoE Chicago mutation, as was observed in our case. Treatment with fenofibrate and irbesartan was initiated, and urinary protein excretion ceased within 1 year; recurrence was not observed after an additional 2 years of follow-up. A second biopsy after 2 years showed great improvement, with lipoprotein thrombi identified only in 2 of 18 glomeruli.

Acute Phosphate Nephropathy with Diffuse Tubular Injury Despite Limited Calcium Phosphate Deposition.

An 86-year-old woman developed acute kidney injury after colonoscopy. A renal biopsy showed diffuse tubular injury with minimal calcium phosphate deposits (CPDs), which were thought to be caused by an oral sodium phosphate bowel purgative before colonoscopy. According to these findings, she was diagnosed with acute phosphate nephropathy (APhN). In contrast to previous reports of diffuse tubular injury associated with tubular CPDs in APhN, this case demonstrated diffuse tubular injury despite a limited distribution of CPDs, suggesting that calcium phosphate can cause tubular injury without deposition. This case thus supports the hypothesis that urinary calcium phosphate crystals may cause tubular injury via other mechanisms, including inflammatory cytokines.

Fatty Acid-Binding Protein 4 mediates apoptosis via endoplasmic reticulum stress in mesangial cells of diabetic nephropathy.

Type 2 diabetes is characterized by hyperglycemia and deregulated lipid metabolism with increased plasma non-esterified fatty acids (NEFA). Apoptosis of glomerular cells is a hallmark in diabetic glomerulosclerosis. Fatty acid-binding protein 4 (FABP4), a carrier protein for fatty acids, has been linked to diabetes and diabetic nephropathy (DN). Here we aimed to investigate the link between FABP4 and apoptosis in diabetic glomerulosclerosis. We first evaluated the presence of FABP4 and ER stress markers as well as apoptosis-related proteins in renal biopsies of patients with DN. Then we used FABP4 inhibitor BMS309403 or siRNA to further investigate the role of FABP4 in ER stress and apoptosis induced by NEFA or high glucose in cultured human mesangial cells (HMCs). We found FABP4 was expressed mainly in glomerular mesangial cells of the human renal biopsies and the glomerular FABP4 was increased in renal biopsies of DN. The up-regulation of FABP4 was accompanied with increased glucose-regulated protein 78 (GRP78) and Caspase-12 as well as down-regulated B-cell CLL/lymphoma 2 (Bcl-2) in glomeruli. Along with the induction of FABP4 and apoptosis, GRP78 and its three sensors as well as C/EBP homologous protein (CHOP) and Caspase-12 were induced in HMCs treated with NEFA or high glucose and these responses were attenuated or even abrogated by treating with FABP4 inhibitor or FABP4 siRNA. Ultrastructure observation confirmed the lipotoxicity of oleic acid by showing the morphological damage in HMCs. Our data suggest that FABP4 in glomerular mesangial cells is up-regulated in DN and FABP4 mediates apoptosis via the ER stress in HMCs.

Renal complications in 6p duplication syndrome: microarray-based investigation of the candidate gene(s) for the development of congenital anomalies of the kidney and urinary tract (CAKUT) and focal segmental glomerular sclerosis (FSGS).

6p duplication syndrome is a rare chromosomal disorder that frequently manifests renal complications, including proteinuria, hypoplastic kidney, and hydronephrosis. We report a girl with the syndrome, manifesting left hydronephrosis, proteinuria/hematuria, and focal segmental glomerular sclerosis (FSGS) resulting in chronic end-stage renal failure, successfully treated with renal transplantation. Microarray comparative genomic hybridization showed the derivative chromosome 6 to have a 6.4-Mb duplication at 6p25.3-p25.1 with 32 protein-coding genes and a 220-Kb deletion at 6p25.3 with two genes of no possible relation to the renal pathology. Review of the literature shows that variation of renal complications in the syndrome is compatible with congenital anomalies of the kidney and urinary tract (CAKUT). FSGS, observed in another patient with 6p duplication syndrome, could be a non-coincidental complication. FOXC1, located within the 6.4-Mb duplicated region at 6p25.3-p25.2, could be a candidate gene for CAKUT, but its single gene duplication effect would not be sufficient. FSGS would be a primary defect associated with duplicated gene(s) albeit no candidate could be proposed, or might occur in association with CAKUT.

Combined IgG4κ and IgG1λ deposition in the glomerular and tubular basement membrane accompanied by autoimmune neutropenia (AIN) and immune thrombocytopenia (ITP).

A 48-year-old male was admitted to our hospital with nephrotic syndrome. Light-microscopic examination of a renal biopsy specimen showed almost normal glomerular appearance, however, immunofluorescence examination revealed linear and granular IgG deposits on the glomerular basement membrane (GBM), accompanied by slight IgG deposition in the tubular basement membrane (TBM). Further investigation of the IgG subclass and light chain staining revealed that the glomerular deposits were composed of IgG1 and IgG4, with both κ and λ light chains, while the tubular deposits were composed of only IgG4 and κ light chains. The electron-microscopic findings of small granular deposits in the GBM and TBM closely resembled those of light and heavy chain deposition disease (LHCDD). Immunoelectron microscopy confirmed the presence of κ and λ chains in the GBM and TBM, however, only significant κ chain deposition was found in the TBM. There was no evidence of monoclonal gammopathy. Clinically, the patient subsequently developed neutropenia and thrombocytopenia associated with the presence of anti-neutrophil antibody and anti-GPIIb/IIIa antibody-producing B cells in the blood. Oral steroid administration was initiated, which led to amelioration of the neutropenia, thrombocytopenia and proteinuria. This may be a very rare case of combined IgG4κ and IgG1λ deposition disease accompanied by autoimmune neutropenia (AIN) and immune thrombocytopenia (ITP) suggestive of biclonal immunoglobulin deposition disease (BIDD). Investigation of the IgG subclass and of the light chains was useful for recognizing the clonality of the immunoglobulin deposits in the kidney.

A case of endocapillary proliferative glomerulonephritis with macrophages phagocytosing monoclonal immunoglobulin lambda light chain.

Multiple myeloma (MM) is a plasma-cell neoplasm that can cause renal disorders. Renal lesions in MM can present with a very rare pathological manifestation involving a specific monoclonal immunoglobulin (Ig). We report the case of a 33-year-old woman who had edema, fatigue, elevated serum creatinine levels, hypoalbuminemia, and hypercholesterolemia. She had persistent hematuria and proteinuria lasting 3 years. Serum protein electrophoresis showed an M-spike, and serum immunofixation demonstrated the presence of monoclonal IgG λ. She had proteinuria in the nephrotic range, and a monoclonal λ fragment was present on urine immunofixation. Renal biopsy showed proliferative glomerulonephritis with λ light chain and C3c deposition and inflammatory cell infiltration with CD68. Macrophage lysosomes contained λ light chains, suggesting their partial phagocytosis. She was diagnosed with symptomatic MM and was treated with bortezomib and dexamethasone and an autologous peripheral stem cell transplant conditioned with intravenous melphalan. She achieved a partial response with decreased serum monoclonal protein and improved renal function. This case may be categorized as a monoclonal gammopathy-associated proliferative glomerulonephritis. The biopsy finding of partially phagocytosed Ig λ light chains by macrophages is very rare; this pathological condition is similar to crystal-storing histiocytosis.