Extraglomerular C3 deposition and metabolic impacts in patients with IgA nephropathy.

BACKGROUND: The aim of the present study was to explore the significance of extraglomerular (Bowman's capsule and/or arteriole) C3 (ex-C3) deposits in IgA nephropathy (IgAN). METHODS: One hundred and seventy patients with IgAN were divided into two groups: Group A (n=79), patients who did not have ex-C3 deposits, and Group B (n=91), patients who had ex-C3 deposits. RESULTS: At the time of renal biopsy, Group B was characterized by a marked increase in diastolic blood pressure, total cholesterol, triglyceride and low-density lipoprotein-cholesterol compared with those of Group A. After 4 years, the estimated glomerular filtration rate (eGFR) in Group B was significantly worse than that of Group A. Upon examination by electron microscopy, the arteriolar dense deposits in Group B were found to occur in significantly higher amounts than in Group A. One hundred and thirty-four patients underwent a 3-year follow-up study after intervention and were re-divided by therapeutic factors as follows: 'conventional therapy', treatment with anti-hypertensive drugs and/or anti-platelet drugs, and 'aggressive therapy', additional treatment with either tonsillectomy or corticosteroid. Patients treated with conventional therapy in Group B had significantly higher body mass index and levels of C3 and CH50 compared with other Groups. Aggressive therapy was significantly effective in urinary protein reduction in both Group A and Group B. Except for the patients who received aggressive therapy in Group A, the levels of the eGFR gradually declined. CONCLUSIONS: It appears that IgAN patients who have ex-C3 deposits have worse clinical outcomes.

Determination of severity of murine IgA nephropathy by glomerular complement activation by aberrantly glycosylated IgA and immune complexes.

The pathogenic roles of glomerular deposition of components of the complement cascade in IgA nephropathy (IgAN) are not completely clarified. To investigate the pathologic role of complement pathways in IgAN, two IgAN-prone mouse models were examined. Grouped ddY (gddY) mice showed significant high proteinuria, severe glomerular lesions, and extracellular matrix expansion compared with high serum IgA (HIGA) mice but with similar intensity of glomerular IgA deposition. Glomerular activation of the classical, lectin, and alternative pathways was demonstrated by significantly stronger staining for complement (C)3, C5b-9, C1q, C4, mannose-binding lectin (MBL)-A/C, MBL-associated serine protease-2, and factor B and properdin in gddY mice than in HIGA mice. Similarly, the serum levels of IgA-IgG2a/IgM and IgA-MBL-A/C immune complexes and polymeric IgA were significantly higher in gddY mice than in HIGA mice. Moreover, the serum levels of aberrantly glycosylated IgA characterized by the binding of Sambucus nigra bark lectin and Ricinus communis agglutinin I were significantly higher in gddY mice than in HIGA mice. This aberrancy in glycosylation was confirmed by monosaccharide compositional analysis of purified IgA using gas-liquid chromatography. This study is the first to demonstrate that aberrantly glycosylated IgA may influence the formation of macromolecular IgA including IgA-IgG immune complexes and subsequent complement activation, leading to full progression of IgAN.

Development of a model of early-onset IgA nephropathy.

ddY mice spontaneously develop IgA nephropathy (IgAN) with a variable age of disease onset. Establishing a model with early-onset IgAN could aid the investigation of mechanisms that underlie the pathogenesis of this disease. On the basis of histologic grading in serial biopsies, we previously classified ddY mice into early-onset, late-onset, and quiescent groups. Here, we selectively mated mice with the early-onset phenotype for >20 generations and established "grouped ddY" mice that develop IgAN within 8 weeks of age. Similar to human IgAN, the prognosis was worse for male mice than females. These mice homogeneously retained genotypes of four marker loci previously associated with the early-onset phenotype, confirming a close association of these loci with early-onset IgAN in ddY mice. Grouped ddY mice comprised two sublines, however, which had distinct genotypes at a susceptibility locus for high serum IgA levels, which maps within the Ig heavy-chain gene complex. The subline bearing the Igh-2(a) IgA allotype had a more rapid course of fatal disease and lower oligosaccharide content, suggesting that aberrant IgA glycosylation may promote the progression of murine IgAN. Taken together, these data indicate that grouped ddY mice may be a useful model for the identification of susceptibility genes and the underlying molecular mechanisms involved in the pathogenesis of human IgAN.

Reevaluation of the mucosa-bone marrow axis in IgA nephropathy with animal models.

Impaired immune regulation along the 'mucosa-bone marrow axis' has been postulated to play an important role in the pathogenesis of IgA nephropathy (IgAN). Animal models have allowed us to study such changes in detail. Recently, we established several useful animal models, including IgAN-prone mice. Using these animal models, our group is approaching the underlying mechanisms by which bone marrow and mucosal cell interrelate and finally induce this disease. Accumulating evidence from these approaches suggests that there is dysregulation of innate and cellular immunity in IgAN resulting in changes in the mucosal immune system. These changes appear to be closely linked to disruption of mucosal tolerance, resulting in abnormal priming and dissemination of cells to sites such as the bone marrow where they are responsible for synthesis of nephritogenic IgA. Our clinical studies further support these ideas and indicate that the tonsils may be a major mucosal priming site in human IgAN. In addition, our findings also suggest clinical application of nephritogenic IgA (IgA1) as a biological marker and possible future treatment strategies that focus on manipulating the priming and dissemination of these memory cells in order to prevent the appearance of nephritogenic IgA (IgA1) in the systemic compartment.

[Three adult cases of severe acute glomerulonephritis with acute renal failure requiring hemodialysis].

Acute poststreptococcal glomerulonephritis (APSGN) typically recovers within 2 weeks with conservative therapy, but severe cases are known to develop acute renal failure and or nephrotic syndrome. We experienced 3 adult cases of APSGN with acute renal failure. All 3 cases required hemodialysis, 2 cases received double filtration plasmapheresis, and 2 cases received steroid therapy. In all cases, renal biopsy specimens showed endocapillary proliferative glomerulonephritis. One case had 25% cellular crescents and the others showed wide subendothelial deposits. There were no tubulointerstitial lesions. These 3 cases of severe APSGN with acute renal failure showed the benefits of combination therapy, hemodialysis, double filtration plasmapheresis and steroid therapy. Further clinical study is required to determine which therapy, double filtration plasmapheresis or steroid therapy, is useful.

Diastereoselective Brook rearrangement-mediated [3+4] annulation: application to a formal synthesis of (+)-laurallene.

The formal synthesis of (+)-laurallene, a halogenated eight-membered ring ether, was accomplished. The synthesis involves construction of a trans alpha,alpha'-disubstituted oxocene structure 16 through a Brook rearrangement-mediated [3+4] annulation using acryloylsilane 10 and 6-oxa-2-cycloheptenone 9 and its conversion into 2, which has been transformed into (+)-laurallene by Crimmins and co-workers.

[A case of acute renal and liver dysfunction with light chain deposition disease].

A 62 year old woman was referred to our hospital because of acute renal and liver dysfunction. Prior to admission, she had already been started on hemodyalysis filtration(HDF). She showed facial edema and lumbar pain caused by an Ll compressive fracture. Laboratory examinations revealed hypercalcemia (13.2 mg/dL), hyperammonemia (297 microg/dL) and her serum creatinine, blood urea nitrogen and total bilirubin levels were 3.9 mg/dL, 37.4 mg/dL and 3.2 mg/dL, respectively. Among the components of immunoglobulin, IgA was increased, while IgG and IgM were decreased. Serum immunoelectrophoresis revealed the presence of the IgA kappa type of M component. Punched out lesions were noted on her head radiography. Severe plasmacytosis (60-70 % of total cells) were observed by a bone marrow aspiration test, indicating the diagnosis of multiple myeloma. Steroid pulse therapy was started with dexamethasone (40 mg/day, 3 days), and plasma exchange was performed 8 times with continuous HDF. These treatments failed to control hemodynamics and she died of disseminated intravascular coagulation (DIC). Autopsy demonstrated amyloid-like depositions in perisinusoidal space in the liver. In the kidney, there were nodular lesions in the glomeruli, and depositions in the basement membrane of the uriniferous tubuli. Congo red staining of these organs for amyloid yielded negative results. Immunohistochemical staining gave positive results for IgA and kappa. Electron microscopy revealed granular electron deposits in the glomeruli and tubular basement membrane as well. Taken altogether, the diagnosis of the patient could be light chain deposition disease (LCDD).