Upward-directed exit-site of the swan-neck catheter and "Easy-to-disinfect the backside area of exit-site" may prevent PD complications.

BACKGROUND: Upward-directed exit-site has been believed to be the worst for frequent ESI by an old retrospective study using straight catheters. No comparison study of 3 exit-site directions using swan-neck catheter has been performed regarding which direction is the best for our endpoints, Easy-to-see the backside area of exit-site: ESBE, Easy-to-disinfect the backside area of exit-site: EDBE, reduction of both exit-site infection (ESI), symptomatic catheter dislocation and peritonitis. METHODS: We assessed the relationship of exit-site direction with our endpoints in a quantitative cross-sectional, multicentered questionnaire survey. Patients who received either non-surgical catheter implantation or exit-site surgery were excluded. RESULTS: The numbers (percentage) of exit-site directions in included 291 patients were upward 79 (26.0), lateralward 108 (37.5) and downward 105 (36.5). Cochran-Armitage analysis showed a significant step-ladder increase in the prevalence of ESI as the direction changed from upward to lateralward to downward (0.15 ± 0.41, 0.25 ± 0.54, 0.38 ± 0.69 episodes/patient-year, p = 0.03). Multivariable regression analysis revealed the upward exit-site independently associates with both higher frequency of ESBE (OR 5.55, 95% CI 2.23-16.45, p < 0.01) and reduction of prevalence of ESI (OR 0.55, 95%CI 0.27-0.98, p = 0.04). Positive association between the prevalence of symptomatic catheter dislocation and ESI (OR 2.84, 95% CI 1.27-7.82, p = 0.01), and inverse association between EDBE and either prevalence of symptomatic catheter dislocation (OR 0.27, 95% CI 0.11-0.72) or peritonitis (OR 0.48, 95% CI 0.23-0.99) observed. CONCLUSION: Upward-directed swan-neck catheter exit-site may be the best for both ESBE and prevention of ESI. EDBE may reduce catheter dislocation and peritonitis. Symptomatic catheter dislocation may predict ESI.

Late relapse of IgM nephropathy-associated nephrotic syndrome after repeated administration of immune checkpoint inhibitor against pulmonary adenocarcinoma.

ICPIs were effective for primary and metastatic foci of lung adenocarcinoma, but their repeated use provoked a late relapse of IgM nephropathy and lethal lesions in pancreas and lung. ICPIs should be used carefully in cases of immune-related disease.

[An 89-year-old man who underwent percutaneous peritoneal dialysis catheter placement and had peritoneal dialysis introduced].

The number of elderly patients requiring dialysis is continuously increasing. In Japan, many patients undergo hemodialysis; however, it has been associated with huge stress-mainly on the cardiovascular system-and requires frequent hospital visits. Conversely, peritoneal dialysis is much less invasive with a much lower frequency of hospital visits than that of hemodialysis; therefore, it is suitable for elderly patients. In addition, peritoneal dialysis, which originally had a high affinity for home care, has become more useful for elderly patients with renal failure thanks to the recent introduction of a cloud-based remote monitoring system at home. We performed percutaneous placement of a peritoneal dialysis catheter to reduce physical invasiveness and initiate peritoneal dialysis. The Barthel Index before hospitalization was 0 but increased to 65 at discharge. Further technology advancements in peritoneal dialysis are expected in the future. The cloud-based remote monitoring system is also expected to maintain or increase activities of daily living and the quality of life in elderly patients with renal failure with decreased activities of daily living.

Renal redox dysregulation in AKI: application for oxidative stress marker of AKI.

Oxidative stress is a major determinant of acute kidney injury (AKI); however, the effects of an AKI on renal redox system are unclear, and few existing AKI markers are suitable for evaluating oxidative stress. We measured urinary levels of the redox-regulatory protein thioredoxin 1 (TRX1) in patients with various kinds of kidney disease and in mice with renal ischemia-reperfusion injury. Urinary TRX1 levels were markedly higher in patients with AKI than in those with chronic kidney disease or in healthy subjects. In a receiver operating characteristic curve analysis to differentiate between AKI and other renal diseases, the area under the curve for urinary TRX1 was 0.94 (95% confidence interval, 0.90-0.98), and the sensitivity and specificity were 0.88 and 0.88, respectively, at the optimal cutoff value of 43.0 µg/g creatinine. Immunostaining revealed TRX1 to be diffusely distributed in the tubules of normal kidneys, but to be shifted to the brush borders or urinary lumen in injured tubules in both mice and humans with AKI. Urinary TRX1 in AKI was predominantly in the oxidized form. In cultured human proximal tubular epithelial cells, hydrogen peroxide specifically and dose dependently increased TRX1 levels in the culture supernatant, while reducing intracellular levels. These findings suggest that urinary TRX1 is an oxidative stress-specific biomarker useful for distinguishing AKI from chronic kidney disease and healthy kidneys.

Serial renal biopsy findings in a case of POEMS syndrome with recurrent acute renal failure.

This report describes a patient presenting with recurrent acute renal failure occurring in the course of POEMS syndrome, a multisystem disease associated with plasma cell dyscrasia. Several combined immunosuppression therapies failed to resolve recurrent acute renal failure; autologous peripheral blood stem cell transplantation was therefore applied. A renal biopsy was performed on each of four occasions when he developed renal dysfunction. The renal biopsy showed typical renal histology of POEMS, membranoproliferative glomerulonephritis-like lesions and narrowing of vessel lumina of various sizes caused by endothelial injury, which progressed to glomerulosclerosis and vessel occlusion. Recurrent acute renal failure might be caused by ischemia due to arterial occlusion. Serum levels of vascular epithelial growth factor (VEGF), which is considered to be a causative factor of endothelial lesions in POEMS syndrome, were not elevated throughout the course of this case.

Sairei-to ameliorates rat peritoneal fibrosis partly through suppression of oxidative stress.

BACKGROUND: Sairei-to is a herbal prescription originating from traditional Chinese medicine. We conducted an experimental study on rat peritoneal fibrosis to clarify the suppressive mechanisms of sairei-to. METHODS: Wistar rats were intraperitoneally injected with chlorhexidine gluconate (CG) every day. Peritoneal specimens were collected after 28 days of CG injection and oral administration of sairei-to. Macrophage infiltration, extracellular matrix accumulation, and angiogenesis were evaluated by immunostaining for ED-1, fibronectin, and CD-31, respectively. To observe oxidative stress in the tissue, 4-hydroxy-2-noneal (HNE) accumulation and plasma levels of superoxide dismutase (SOD) activity were detected. As a candidate of antioxidative components in sairei-to, plasma levels of baicalin were determined by high-performance liquid chromatography. RESULTS: Compared with the disease control group, serum total protein levels were significantly recovered in the sairei-to treatment group. Thickness of the submesothelial compact zone, trichrome-stained area, ED-1-positive cells, fibronectin-staining area, and HNE accumulation were suppressed in the treatment group. Concurrently, decreased plasma levels of SOD activity were recovered by sairei-to treatment. Increased CD-31-positive vessel number and area were also suppressed in the sairei-to group. Baicalin was detected in the plasma samples of the sairei-to group at 0.29 ± 0.11 µg/ml (mean±SEM). CONCLUSION: These results suggest that sairei-to ameliorates peritoneal fibrosis, partly through suppressing oxidative stress and macrophage infiltration.

Churg-Strauss syndrome with severe granulomatous angiitis and crescentic glomerulonephritis, which developed during therapy with a leukotriene receptor antagonist.

A 77-year-old Japanese female developed Churg-Strauss syndrome (CSS), showing fever and numbness in bilateral hands. She was being treated for bronchial asthma with combination inhalant of corticosteroid with beta(2)-agonist, and an oral leukotriene receptor antagonist (LTRA), montelukast, for 15 months. She presented fever up to 38°C with microscopic hematuria and proteinuria, serum creatinine level of 0.7 mg/dl, and C-reactive protein of 11 mg/dl. After referral to our hospital, eosinophilia and high myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA) level were observed together with hematuria and proteinuria; renal biopsy examination was performed to clarify the disorder. Renal biopsy specimens showed necrotizing crescent formation, severe granulomatous angiitis in an interlobular artery, and interstitial eosinophilic infiltration. It was noted that nearly intact glomeruli were infiltrated with eosinophils. After treatment with oral prednisolone at initial dose of 40 mg (1 mg/kg body weight), urinary findings rapidly became normal with mild elevation of serum creatinine to 1.5 mg/dl and trace level of serum C-reactive protein in 1 month. Because she was previously treated with montelukast without oral corticosteroid, linkage between CSS and LTRA was highly suspected.

[Case of kidney failure with thrombotic microangiopathy lesions in renal biopsy caused by accelerated hypertension in young adult].

A 19-year-old male was admitted to our hospital for the treatment of severe hypertension with renal dysfunction. Two years before admission, his hypertension had been diagnosed as essential hypertension based on a series of examinations when his renal function was not impaired. Visits to his primary physician ended when he developed severe hypertension of 210/140 mmHg, at which time renal dysfunction and serum creatinine of 2.25 mg/dL were discovered. Renin and antidiuretic hormone were slightly elevated, but renal artery stenosis or other abnormalities were not detected by magnetic resonance imaging and computer tomography. After the hypertension was controlled by medication, a renal biopsy was performed to assess renal impairment. Histology demonstrated lesions compatible with thrombotic microangiopathy (TMA) and ischemic lesions, including fibrinoid necrosis, intimal thickening, occlusion in the small arteries, wrinkling and duplication of the glomerular basement membrane with microthrombi, and focal interstitial fibrosis. Renal function ameliorated after the hypertension was controlled. This case suggests that severe and accelerated hypertension can cause TMA with renal impairment even in young people.

Lipopolysaccharide-triggered acute aggravation of mesangioproliferative glomerulonephritis through activation of coagulation in a high IgA strain of ddY mice.

BACKGROUND: The high IgA (HIGA) strain of ddY mice represents an inbred model of IgA nephropathy that shows mesangioproliferative glomerulonephritis with mesangial IgA deposition. In this study, aggravation of glomerulonephritis in HIGA mice through lipopolysaccharide (LPS)-triggered activation of coagulation was investigated. METHODS: Twelve-week-old HIGA and BALB/c mice were intraperitoneally injected with LPS twice at an interval of 3 days, and kidney specimens were collected 7 days after the second LPS injection. In an intervention experiment, the factor Xa inhibitor danaparoid was injected intraperitoneally every day for 7 days after the first LPS injection. RESULTS: LPS injection induced macrophage infiltration and cellular proliferation in the mesangium together with fibrin deposition and monocyte chemoattractant protein 1 mRNA expression, as well as antigen deposition of tissue factor, factor V, factor X, and protease-activated receptor 2. These phenomena were obvious in HIGA mice when compared to BALB/c mice. Interestingly, toll-like receptor 4 was intensely expressed in HIGA mice before LPS injection and subsequently decreased. Danaparoid treatment significantly ameliorated proteinuria, cellular proliferation, and fibrin deposition. CONCLUSIONS: The present data suggest that tissue factor and factor V induction by LPS may in part accelerate mesangioproliferative glomerulonephritis through activation of factor X and downstream proinflammatory and procoagulant mechanisms.

Tissue factor and factor v involvement in rat peritoneal fibrosis.

OBJECTIVE: Fibrin deposition on the peritoneum has been frequently observed in peritoneal fibrosis induced by long-term peritoneal dialysis. The present study was conducted to clarify the contribution of factor Xa through tissue factor and factor V expression in peritoneal fibrosis. METHODS: Wistar rats were intraperitoneally injected with chlorhexidine gluconate (CG) every day. For the interventional study, the factor Xa inhibitor fondaparinux was subcutaneously administered. After 28 days of CG injection, peritoneal specimens were examined by immunohistochemical analyses and in situ hybridization. RESULTS: The peritoneal submesothelial compact zone was observed to be markedly thicker in the CG-injected groups than in the normal group, and that thickness was dose dependent. Immunohistochemical study revealed massive fibrin, fibronectin, and type IV collagen depositions in the CG-injected groups, which was markedly higher than that in the normal group. Macrophage infiltration and staining for tissue factor, factor V, factor X, and protease-activated receptor-2 were intense in the CG-injected groups and negative/trace in the normal group. Tissue factor and factor V mRNAs were abundant in cells in the thickened peritoneum. A double-labeling experiment revealed that tissue factor was observed mainly in macrophages, and factor V was abundantly distributed in the fibrotic tissue together with macrophages. Fondaparinux treatment decreased the thickness of submesothelial fibrotic tissue, and size and number of CD31-positive vessels. CONCLUSION: These results suggest that expression of tissue factor and factor V in infiltrated macrophages, together with factor X deposition, may progress angiogenesis and accumulation of extracellular matrix components, partly via profibrotic and procoagulant mechanisms in the peritoneum after inflammatory stimulation.

Glomerulonephritis induced by methicillin-resistant Staphylococcus aureus infection that progressed during puerperal period.

A 28-year-old Japanese woman developed fever, leg edema, purpura, and abdominal pain during the puerperal period, showing nephrotic syndrome with microscopic hematuria. At first she was thought to have Henoch-Shönlein purpura nephritis and was given steroids at another hospital. Because anasarca and massive urinary protein excretion developed, she was referred to our hospital. Renal biopsy specimens showed endocapillary proliferative glomerulonephritis with massive IgA and C3d deposition along the capillary loops and in the mesangium. A bacteriological study detected methicillin-resistant Staphylococcus aureus (MRSA) in cultures of vaginal secretions, urine, stool, and pharyngeal mucus samples. Based on the diagnosis of MRSA nephritis, anti-MRSA therapy with antibiotics was started, and MRSA became negative for each culture, and urinary protein decreased. Two months after the first renal biopsy, a second renal biopsy was performed, which revealed feeble endocapillary proliferation with mild IgA and C3d deposition in the mesangium. This case showed that the delivery procedure can cause MRSA nephritis after MRSA infection, and that steroid therapy should be avoided in the early phase of this type of nephritis.

Roles of coagulation pathway and factor Xa in rat mesangioproliferative glomerulonephritis.

Tissue factor initiates the extrinsic coagulation pathway by activating coagulation factor X to factor Xa, and factor V is a cofactor for the prothrombin activation by factor Xa. As factor Xa is known to promote the proliferation of mesangial cells in culture, the roles of the coagulation pathway and factor Xa were studied in an animal model of mesangioproliferative glomerulonephritis (MsPGN). MsPGN was induced in Wistar rats by an intravenous injection of anti-Thy 1.1 monoclonal antibody, OX-7. To clarify the role of factor Xa in MsPGN, a specific factor Xa inhibitor, DX-9065a, was injected intravenously at 2.5 or 10 mg/kg at the same time as OX-7, and kidney involvement was assessed by immunohistological analyses. We also examined p44/42 mitogen-activated protein (MAP) kinase activation. Time-course study revealed that expressions of tissue factor, factor V, and protease-activated receptor 2 (PAR2) were peaked on day 3, followed by factor X accumulation and mesangial proliferation. DX-9065a treatment significantly ameliorated proteinuria in a dose-dependent manner on day 8. Histological analyses showed a significant reduction in the size of glomeruli, the total number of glomerular cells, and crescent formation by DX-9065a treatment. Macrophage infiltration, which was rapidly observed on day 1 in disease control rats was not inhibited on days 1-3 by DX-9065a treatment, however it was suppressed on days 5-8. The deposition of fibrin, the number of PCNA-positive cells, and phosphorylation of p44/42 MAP kinase were markedly increased in the disease control group, whereas they were significantly reduced in the treatment group. Tissue factor and factor V induction may accelerate MsPGN through the activation and accumulation of factor X via proinflammatory and procoagulant mechanisms, and the inhibition of factor Xa would be a promising method to regulate the disease process.

Clinical efficacy of intravenous immunoglobulin for patients with MPO-ANCA-associated rapidly progressive glomerulonephritis.

BACKGROUND: To determine whether intravenous immunoglobulin (IVIg) can control disease activity in patients with myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-associated rapidly progressive glomerulonephritis (RPGN). METHODS: Twelve patients with serologically and histologically confirmed MPO-ANCA-associated RPGN (7 men, 5 women; mean age 71 +/- 3 years) received IVIg (400 mg/kg/day) alone for 5 days. The effects of IVIg were evaluated by white blood cell counts, serum C-reactive protein levels, Birmingham Vasculitis Activity Score, rate of change in reciprocal creatinine (1/Cre), and plasma tumor necrosis factor-alpha levels after IVIg administration. Corticosteroids with or without cyclophosphamide were commenced after IVIg. RESULTS: After IVIg treatment, a significant decrease was observed in white blood cell count (p < 0.05), C-reactive protein values (p < 0.001), and Birmingham Vasculitis Activity Score (p < 0.001) concomitant with the amelioration of systemic symptoms. The rate of change in 1/Cre significantly improved (p < 0.05). Plasma tumor necrosis factor-alpha levels that were significantly elevated in patients before IVIg compared with normal controls (p < 0.0001), rapidly declined after IVIg with a significant reduction (p < 0.05). Three months post-treatment with IVIg, all patients showed improvement of disease without serious infectious complications. CONCLUSION: IVIg is a potential component of remission induction therapy for patients with MPO-ANCA-associated RPGN.

Chromosomal mapping of hyperserum IgA and glomerular IgA deposition in a high IgA (HIGA) strain of DdY mice.

BACKGROUND: The high IgA (HIGA) strain of ddY mice is an inbred model of IgA nephropathy (IgAN), established by selective mating of outbred ddY mice. HIGA mice show high levels of serum IgA and glomerulonephritis with mesangial IgA deposition. To identify the genetic loci responsible for hyperserum IgA and glomerular IgA deposition in this strain, quantitative trait loci analysis was carried out. METHODS: By crossing HIGA with BALB/c mice, 244 F2 generations were produced. Serum IgA levels and glomerular IgA deposition were examined at 40 weeks of age. Genetic markers were typed at 105 microsatellites and the quantitative trait loci of hyperserum IgA and glomerular IgA deposition were confirmed using Map Manager QTX software. RESULTS: Two significant quantitative trait loci of hyperserum IgA were identified on chromosome 2 [logarithm of odds (LOD) = 5.01] and chromsome 4 (LOD = 4.45), and a suggestive quantitative trait locus of hyperserum IgA was located on chromosome 1 (LOD = 3.49). On chromosome 15, a significant quantitative trait locus of glomerular IgA deposition was identified (LOD = 4.40) without the hyperserum IgA locus. Serum IgA level was weakly correlated with the intensity of glomerular IgA in 244 F2 mice; however, the quantitative trait loci of hyperserum IgA were not significantly associated with glomerular IgA deposition. CONCLUSION: These findings indicate that, in HIGA mice, glomerular IgA deposition is mainly regulated by a quantitative trait locus on chromosome 15, and hyperserum IgA synergistically but weakly affect glomerular IgA deposition. The immune disturbance similar to IgAN was revealed to be under multigenic control in HIGA mice.

The Na+-excreting efficacy of indapamide in combination with furosemide in massive edema.

BACKGROUND: Massive systemic edema is often observed in patients with severe nephrotic syndrome, including diabetic nephropathy. Although furosemide, a loop diuretic, is often administered to these patients, some patients do not respond to this treatment, still showing massive edema. METHODS: The efficacy of indapamide which has a thiazide-like effect on distal convoluted tubules in combination with furosemide, was evaluated in eight patients with massive edema, in regard to both Na+ excretion and diuresis. Indapamide 2 mg was administered once a day, in the morning, to patients in whom it was considered that furosemide treatment of 40-120 mg a day for 1 week was ineffective. RESULTS: Urinary Na+ excretion was markedly increased, from 83.7 +/- 82.2 mEq/day to 140.7 +/- 33.8 mEq/day after 1 week of the combination therapy compared with furosemide alone (P < 0.01); urine volume was also increased, from 1070 +/- 230 ml to 1359 +/- 296 ml after 1 week of the combination therapy (P < 0.05). In this context, body weight was significantly decreased, from 57.2 +/- 12.3 kg to 53.4 +/- 12.8 kg, after the combination therapy (P = 0.01). Indapamide in combination with furosemide was well tolerated, and no significant changes in serum levels of creatinine and potassium were observed. CONCLUSIONS: This combination therapy appears to be effective in patients with massive edema, as it increased diuresis, and achieved potent Na+ excretion.

Role of coagulation factor Xa and protease-activated receptor 2 in human mesangial cell proliferation.

BACKGROUND: Fibrin deposition and mesangial cell proliferation are frequently observed in the active type of mesangioproliferative glomerulonephritis. Coagulation factors, such as factor V and factor Xa are colocalized with fibrin in the mesangial areas in active type of IgA nephropathy with mesangial cell proliferation. In this study, therefore, we studied the role of factor Xa and its receptor, protease-activated receptor 2 (PAR2) in mesangial cell proliferation and fibrin deposition, and examined ant-proliferative effects of a specific factor Xa inhibitor, DX-9065a, in cultured human mesangial cells. METHODS: To examine the effect of DX-9065a on the factor Xa-induced proliferation of cultured human mesangial cells, we measured thymidine incorporation and cell numbers. We also examined the effect of DX-9065a on extracellular regulated kinase (ERK) activation and fibrin production induced by factor Xa in human mesangial cells. RESULTS: Factor Xa increased [(3)H]-thymidine incorporation and cell numbers in a dose-dependent manner in mesangial cells, which was inhibited by DX-9065a. DX-9065a also suppressed factor Xa-triggered fibrin deposition on mesangial cell surface. Factor Xa induced the activation of ERK in mesangial cells and this activation was also completely inhibited by DX-9065a, but not inhibited by PAR1 antagonist. Factor Xa-induced cell proliferation and ERK activation were inhibited by PD98059. CONCLUSION: There results suggest that factor Xa can induce mesangial cell proliferation through the activation of ERK via PAR2 in mesangial cells and that PAR2 may play a crucial role in the cell proliferation induced by factor Xa. Our results implicate that DX-9065a may be a promising agent to regulate proliferation of mesangial cellss and inhibit the coagulation process in mesangium.

Suppressive mechanisms of Sairei-to on mesangial matrix expansion in rat mesangioproliferative glomerulonephritis.

BACKGROUND: Sairei-to (TJ-114) is a Japanese herbal medicine of standardized quality, originating from traditional Chinese medicine. In the present in vivo study, we investigated the suppressive effects of TJ-114 and related drugs, Shosaiko-to (TJ-9), and Saiboku-to (TJ-96), on mesangioproliferative glomerulonephritis (MsPGN) in rats. TJ-9 is a basal prescription of TJ-96 and TJ-114. We evaluated the efficacy of these drugs on proteinuria, extracellular matrix (ECM) accumulation, and superoxide dismutase (SOD)-activity. METHODS: MsPGN in Wistar rats was induced by intravenous injection of rabbit anti-rat thymocyte serum (ATS). TJ-114, TJ-9, TJ-96 (500 mg/kg/day), or prednisolone (PSL, 2 mg/kg/day) was orally administered to the rats as drinking water from the day of ATS injection (day 0) to day 8, when rats were sacrificed and the kidney specimens were collected. Macrophage infiltration was evaluated by immunostaining for ED-1. ECM was measured by trichrome-staining, and fibronectin immunostaining. Northern blotting was performed to clarify the mRNA expression of cytokines and fibronectin. SOD-activity in the homogenate of renal cortex was also evaluated. RESULTS: The amount of urinary protein was significantly decreased only in the TJ-114-treated group compared with the disease control group (p < 0.05). The number of ED-1-positive cells was significantly decreased in all the treatment groups (p < 0.05, respectively). Decreases in the trichrome-stained area were observed moderately in the TJ-114-treated group (66% of control, p < 0.001) and mildly in the PSL-treated group (76% of control, p < 0.001). The staining area of fibronectin in the glomerulus was significantly decreased in all the treated groups except PSL, and was especially suppressed in the TJ-114-treated group (45% of control, p < 0.001). Transforming growth factor (TGF) and connective tissue growth factor (CTGF) expression significantly decreased in the TJ-114-treated group to the control level (p < 0.05). TGF-beta, CTGF, and fibronectin mRNA were upregulated in the disease control group, and TJ-114 suppressed these mRNA expressions in glomeruli. The SOD-activity of renal cortex-homogenate was significantly augmented in all the treated groups except PSL, markedly in the TJ-96- and TJ-114-treated groups. CONCLUSION: These results suggest that TJ-114 ameliorates ECM accumulation in experimental rat MsPGN, partly suppressing TGF-beta and CTGF expression through the recovery of SOD-activity.

Role of mesangial Factor V expression in crescent formation in rat experimental mesangioproliferative glomerulonephritis.

It has been suggested that fibrin deposition participates in the development of crescents in active glomerulonephritis (GN). In human IgA nephropathy, which is a common form of mesangioproliferative GN (MsPGN), crescent formation is occasionally observed in active disease, leading to end-stage renal failure. Factor V is a membrane-bound potent cofactor for the conversion of prothrombin to thrombin by Factor Xa. An in vivo study was conducted to clarify the contribution of local fibrin production to crescent formation in MsPGN through mesangial Factor V expression. Wistar rats were injected intravenously with rabbit anti-rat thymocyte serum. Three days after injection, mesangiolysis with intense mesangial Factor V expression was observed and immunoelectron microscopy revealed fibrin localization in mesangiolytic lesions, which had spread into the glomerular basement membrane adjacent to the destroyed mesangium, accompanied by clots in Bowman's space. Marked glomerular fibrin deposition, together with its deposition in Bowman's space and cellular crescent formation, was noted with mesangial proliferation on day 8. Specific bands for Factor V mRNA were also detected from isolated glomeruli. Fibrin deposition and cellular crescent formation were significantly suppressed by treatment with anti-Factor V antibody. These results suggest that local fibrin production, following mesangial Factor V expression, together with mesangiolysis that spreads to the adjacent glomerular basement membrane, plays a role in crescent formation in MsPGN.

Quantitative trait loci (QTL) analysis reveals a close linkage between the hinge region and trimeric IgA dominancy in a high IgA strain (HIGA) of ddY mice.

Polymerization of IgA has been suggested as one of the causes of mesangial deposition in IgA nephropathy. HIGA mice are an inbred model of IgA nephropathy, established by selective mating of ddY mice. This strain is characterized by a unique profile of the IgA molecule that is dominantly polymeric and has high serum levels with intense IgA deposition on the mesangium. We carried out quantitative trait loci (QTL) analysis, using F2 generations by crossing HIGA with BALB/c mice. Significant linkage of polymeric IgA in serum samples was identified around D12Mit263, which is close to the gene of the immunoglobulin heavy chain on chromosome 12. The amino acid sequence of the alpha heavy chain revealed marked differences between BALB/c and HIGA mice. Furthermore, most differences were focussed on the hinge region. The DBA/2J strain, which has the same amino acid sequence in the hinge region as the HIGA strain, also showed polymeric IgA dominance but low IgA levels in sera. Size fraction analysis revealed that these polymeric IgA showed trimer dominance in both DBA/2J and HIGA mice. In conclusion, the hinge region plays a key role in trimeric IgA formation in HIGA mice.