High serum level of methylglyoxal-derived AGE, Nδ-(5-hydro-5-methyl-4-imidazolone-2-yl)-ornithine, independently relates to renal dysfunction.

BACKGROUND: The dicarbonyl methylglyoxal reacts primarily with arginine residues to form advanced glycation end products, including Nδ-(5-hydro-5-methyl-4 -imidazolone-2-yl)-ornithine (MG-H1), which are risk factors for not only diabetic complications but also lifestyle-related disease including renal dysfunction. However, the data on serum level and clinical significance of this substance in chronic kidney disease are limited. METHODS: Serum levels of MG-H1 and Nε-(carboxymethyl) lysine (CML) in 50 patients with renal dysfunction were measured by liquid chromatography/triple-quadruple mass spectrometry. RESULTS: The median serum MG-H1 levels in patients with estimated glomerular filtration rate (eGFR) of ≥30, 15-30, and <15 ml/min/1.73 m2 was 4.16, 12.58, and 14.66 mmol/mol Lys, respectively (p > 0.05). On the other hand, MG-H1 levels in patients with HbA1c of <6 and ≥6 % was 12.85 and 10.45 mmol/mol Lys, respectively, the difference between which is not significant. In logistic regression analysis, decreased renal function (eGFR <15 ml/min/1.73 m2) significantly associated with high serum levels of MG-H1 [odds ratio: 9.39 (95 % confidence interval 1.528-57.76), p = 0.015; Spearman rank correlation: MG-H1 vs. eGFR, r = -0.691, p < 0.01]. In contrast, the serum level of CML did not correlate with eGFR, but correlated with systolic blood pressure [odds ratio 16.17 (95 % confidence interval 1.973-132.5), p = 0.010; Spearman rank correlation coefficient: CML vs. eGFR, r = 0.454, p < 0.01]. CONCLUSION: These results showed that the serum concentration of MG-H1 was strongly related to renal function rather than to DM.

IL-1ß promotes tubulointerstitial injury in MPO-ANCA-associated glomerulonephritis
.

BACKGROUND: It is widely accepted that tubulointerstitial injury (TII) is caused by glomerular injury (GI) in glomerular diseases. Glomerular endocapillary inflammation may result in crescent formation and exuded protein leakage, which may induce TII in antineutrophil cytoplasmic antibody-associated glomerulonephritis (ANCAGN). However, some reports have indicated a glomerulonephritis-independent mechanism of TII in ANCAGN. The aim of this study was to determine the principle cytokines correlated with TII severity and to elucidate a characteristic mechanism for TII in ANCAGN. METHODS: 28 myeloperoxidase-ANCA-positive ANCAGN patients were enrolled, and their kidney biopsy specimens were histologically evaluated with regard to GI and TII. The mRNA expression of various cytokines was examined in 28 specimens. RESULTS: Interleukin (IL)-1ß was significantly correlated with the severity of TII. The mRNA expression of Toll-like receptor 4 (TLR4) and Nod-like receptor family pyrin domain-containing-3 (NLRP3) also correlated with TII severity. Immunohistochemical analysis demonstrated that TLR4 protein was positively stained in the tubulointerstitial infiltrating cells. NRLP3 protein was detected in macrophages in the severe infiltrating area but was absent or only very faintly expressed in the glomeruli. These results indicated that NLRP3 inflammasome-dependent processing in macrophages releases the mature active form of IL-1ß, which may lead to the development and deterioration of TII. CONCLUSIONS: Sterile inflammation leads to the formation of ANCA-mediated neutrophil extracellular traps (NETs), which may stimulate macrophages and dendritic cells via TLR4 and induce NF-κB-dependent mRNA expression and translation of pro-IL-1ß. Simultaneously, damage-associated molecular pattern signals resulting from NETs promote NLRP3 inflammasome-dependent processing and release mature active IL-1ß. Sterile inflammation utilizing the NLRP3 inflammasome might be a characteristic reaction limited to the tubulointerstitium. Thus, neutralizing IL-1ß may be a promising strategy to suspend the progress of TII and improve the prognosis of chronic kidney disease resulting from ANCAGN.
.

[A case of AKI-caused minimal change nephrotic syndrome with concomitant pleuritis].

A twenty-year-old man complaining of chest pain was diagnosed as nephrotic syndrome complicated with pleural effusion and ascites. Despite treatment with antibiotics, his fever and high inflammatory reaction persisted. After hospitalization, his urine volume decreased and renal function had deteriorated. As he was suffering from dyspnea, hemodialysis was performed together with chest drainage. His pleural effusion was exudative, and IVIG treatment was added to the antibiotic treatment. He was diagnosed as suspected developed minimal change nephrotic syndrome (MCNS) and administered prednisolone intravenously. His renal function ameliorated as a result of this treatment, enabling him to withdraw from hemodialysis. Inflammatory reaction gradually decreased and his general condition improved. The result of a renal biopsy examination carried out after the hemodialysis treatment confirmed MCNS, which suggested that MCNS had induced acute kidney injury (AKI) atypically in this case. Generally AKI is not induced by MCNS in youth, but it may occur under severe inflammatory conditions. Physicians should be aware that MCNS in young patients may lead to the development of AKI requiring hemodialysis treatment.

Persistence of renal function in a patient diagnosed with concurrent amyloid amyloidosis and immunoglobulin light chain amyloidosis.

This case describes a 68-year-old woman exhibiting initial proteinuria at age 55. Subsequently, at age 57, a mixed-type of amyloidosis consisting of amyloid amyloidosis (A A) and immunoglobulin (Ig) light chain amyloidosis (AL) was diagnosed by a renal biopsy examination. Monoclonal paraproteinemia was concurrently identified and diagnosed as monoclonal gammopathy of undeterminate significance (MGUS). Combined melphalan and prednisolone (MP) therapy was initiated. At age 65, anti-hypertensive drugs were administered upon finding an increased urine protein concentration and elevated blood pressure. Because there was no change in the state of MGUS detected by a bone marrow biopsy examination, MP therapy was discontinued. However, the urinary protein concentration increased, and a renal biopsy was performed again at age 66. This revealed a mixed-type amyloidosis of AA and AL, as diagnosed earlier, but AL amyloid deposition in the glomeruli had increased during the intervening period. Life-preserving treatment was continued thereafter, but nephrotic syndrome and renal dysfunction progressed rapidly. End-stage renal failure deposition is rarely seen in the same individual. Although amyloidosis is generally thought to cause a rapid decline in renal function, the patient's renal function was maintained for 13 years. This could be attributed to the following factors : l)the underlying etiology of the AA amyloidosis, which was not clear, 2)a lack of any current evidence of chronic inflammation, and 3) MGUS as the cause of AL amyloidosis. This, together with MP therapy, may have slowed down the pathological decline normally associated with AL amyloidosis.

Concurrent minimal change disease and retroperitoneal liposarcoma successfully treated by tumor resection and steroid therapy.

A 54-year-old Japanese woman developed simultaneous abdominal distension and bilateral leg edema. Her medical history and results of periodic medical check-up were unremarkable. Blood tests revealed severe hypoproteinemia and acute kidney injury, and urinalysis revealed 4+ proteinuria and 2+ hematuria. Abdominal computed tomography revealed a large intra-abdominal mass with fat tissue density. She underwent emergency tumor excision, splenectomy, and distal pancreatectomy. However, hypoproteinemia and acute kidney injury worsened. Therefore, she was transferred to the nephrology division for confirmation of diagnosis and for treatment of acute kidney injury and nephrotic syndrome. We conducted percutaneous kidney biopsy and diagnosed minimal change disease (MCD). Intravenous prednisolone was started, and heavy proteinuria and systemic edema were gradually alleviated. She achieved complete remission 2 months later, and oral prednisolone was tapered. Histopathological diagnosis of abdominal tumor was dedifferentiated liposarcoma of retroperitoneal origin. Immunohistochemical staining revealed strong expression of vascular endothelial growth factor in the tumor cells in the dedifferentiated component. Currently, her clinical course is stable without recurrence of liposarcoma and nephrotic syndrome. MCD develops in patients with Hodgkin's lymphoma, solid organ cancers, hematological malignancies, and thymoma, whereas concurrent MCD and liposarcoma are rare. Remission of nephrotic syndrome and normalized kidney function induced by steroid therapy are important for better management of patients with malignancy.

Clopidogrel-induced Thrombotic Microangiopathy in a Patient with Hypocomplementemia.

Clopidogrel was administered to a 67-year-old Japanese man to prevent the recurrence of cerebral infarction. Twelve weeks later, he was admitted to our hospital with acute renal failure, hemolytic anemia and thrombocytopenia, and was diagnosed with clopidogrel-induced thrombotic microangiopathy. Clopidogrel was immediately discontinued and corticosteroid and plasma exchange therapy were administered simultaneously. Thereafter, the patient's condition gradually improved. The patient had a decreased serum complement C3 level. This suggests that the activated alternative pathway is related to thrombotic microangiopathy (TMA). TMA is a critical drug-associated adverse reaction that clinicians should always be vigilant about, because clopidogrel is widely prescribed.