Interleukin 12 induces crescentic glomerular lesions in a high IgA strain of ddY mice, independently of changes in IgA deposition

BACKGROUND

Our recently established high immunoglobulin (Ig)A inbred strain (HIGA) of ddY mice showed constantly high serum IgA levels, progressive mesangial sclerosis accompanied by IgA deposits, and elevated renal expression of transforming growth factor (TGF)-beta, mimicking IgA nephropathy. In the present study, we assessed the role of the immune system, especially of T cells, in this strain.

METHODS

The in vitro production of interferon (IFN)-gamma, interleukin (IL)-4 and TGF-beta1 by splenic CD4+ T cells was assessed in HIGA mice at 14 and 28 weeks of age by comparison with age-matched C57BL/6 and BALB/c mice, T-helper (Th) 1, and Th2 prone controls respectively. Moreover, recombinant murine IL-12 was administered intraperitoneally to HIGA mice and serum IgA and renal lesions were analysed.

RESULTS

The production of IFN-gamma by splenic CD4+ T cells was markedly upregulated in HIGA mice at both ages as compared with age-matched C57BL/6 and BALB/c mice. Although splenic CD4+ T cells from HIGA mice produced less IL-4 than those from BALB/c mice at both ages, the former produced significantly more IL-4 with age, which contrasted with the age-associated decrease in the latter. Moreover, TGF-beta1 production of these cells in HIGA mice was equal to or greater than that in the two groups of control mice at both ages. Daily intraperitoneal administration of IL-12 for 1 week significantly enhanced crescent formation with glomerular macrophage accumulation and interstitial cell infiltration, whereas it reduced the serum IgA level.

CONCLUSIONS

In HIGA mice, Th1 is markedly upregulated from a young age and there is an age-associated Th2 increase with TGF-beta1 upregulation in helper T cells. The former may be related to the exacerbation of inflammatory renal lesions on IL-12 administration, while the latter may contribute to increased IgA production, leading to glomerular IgA deposition and progressive glomerulosclerosis in HIGA mice. The pathogenic role of T cell function and fluctuation of these subsets, especially the Th1/Th2 balance, is crucial to the immunopathological phenotype of the renal lesions in HIGA mice.

Increased frequency of surface IgA-positive plasma cells in the intestinal lamina propria and decreased IgA excretion in hyper IgA (HIGA) mice, a murine model of IgA nephropathy with hyperserum IgA

Because abnormalities of mucosal immunity have been suggested in human IgA nephropathy, we examined the involvement of mucosal immunity in IgA deposition to the kidney in hyper IgA (HIGA) mice, which was established as a mouse model for human IgA nephropathy with hyperserum IgA. The number of surface IgA+B220- lymphocytes in the intestinal lamina propria (LP) of HIGA mice increased 2.7-fold at 30 wk of age as compared with those at 10 wk of age, whereas normal mice did not show such increase. The surface IgA+B220- LP lymphocytes spontaneously secreted IgA in culture. Morphological studies showed that the surface IgA+B220- lymphocytes of murine intestinal LP are identical with plasma cells (PCs). About 20% of IgA+B220- PC in LP expressed both Mac-1 and CD19, suggesting that they may derive from peritoneal B-1 cells. Cell cycle study on intestinal IgA-PCs using bromodeoxyuridine revealed no difference between HIGA mice and normal mice, suggesting that the high frequency of IgA-producing PCs in HIGA mice is not due to enhanced proliferation or prolonged survival of IgA-producing PCs in LP. In addition, IgA secretion into the gut lumen of HIGA mice decreased drastically (to one forth) with aging. These data suggest that the increased number of intestinal IgA-producing PCs and the down-regulation of IgA excretion into the intestinal lumen might synergistically contribute to the hyperserum IgA in HIGA mice and resultant IgA deposition to the kidney.

Significantly high regional morbidity of MPO-ANCA-related angitis and/or nephritis with respiratory tract involvement after the 1995 great earthquake in Kobe (Japan)

Within a 3-year period after the Great Earthquake of Kobe (Japan) resulted in more than 6,000 deaths and complete destruction of the central area of Kobe City, 14 patients (group 1 [G1]) with myeloperoxidase (MPO)-antineutrophil cytoplasmic autoantibody (ANCA)-related angitis and/or nephritis presented to Nishi-Kobe Medical Center in western Kobe City. On the other hand, only 15 patients with this disease were encountered between 1990 and 1997 at Kyoto University Hospital in Kyoto City, which is located 80 km from Kobe City and was only minimally affected by the earthquake. These 15 patients and 1 patient who presented to Nishi-Kobe Medical Center before the Great Earthquake were classified as group 2 (G2). Although the average MPO-ANCA titer in G1 was almost the same as that in G2, G1 showed a significantly greater average value for white blood cells than G2 (11,321 +/- 4,369 versus 8,116 +/- 2, 389/microL; P < 0.05). Concerning renal function, a significant elevation in creatinine (Cr) levels at diagnosis (7.4 +/- 3.8 versus 2.1 +/- 1.4 mg/dL; P < 0.01) and rapidly declining rates of reciprocal Cr levels were noted in G1 (0.325 +/- 0.304 versus 0.087 +/- 0.069 dL/mg. wk; P < 0.01). The number of patients who required emergency hemodialysis was significantly greater in G1 than G2 (nine versus three patients; P < 0.02); however, the incidence of renal death and mortality were not significantly different between the groups. The number of patients who reported upper respiratory tract inflammation as an initial symptom was also significantly greater in G1 than G2 (eight versus two patients; P < 0.01). Moreover, patients in G1 experienced a significantly greater rate of severe pulmonary involvement during the hospital course than G2 (pulmonary hemorrhage, five versus no patients; interstitial pneumonitis, four versus two patients, respectively; P < 0.01). The relatively uniform and distinctive clinical features of the disease after the Great Earthquake, in conjunction with a high morbidity, suggest a relationship between disease development and this urban type of earthquake. Severely provoking air pollution caused by massive destruction and reconstruction of the city may have caused high frequencies of upper respiratory tract inflammation as an initial symptom and severe pulmonary involvement.

Anti-ischemic effect of a novel cardioprotective agent, JTV519, is mediated through specific activation of delta-isoform of protein kinase C in rat ventricular myocardium

BACKGROUND

A new 1,4-benzothiazepine derivative, JTV519, has a strong protective effect against Ca(2+) overload-induced myocardial injury. We investigated the effect of JTV519 on ischemia/reperfusion injury in isolated rat hearts.

METHODS AND RESULTS

At 30 minutes of reperfusion after 30-minute global ischemia, the percent recovery of left ventricular developed pressure was improved, and the creatine phosphokinase and lactate dehydrogenase leakage was reduced in a concentration-dependent manner when JTV519 was administered in the coronary perfusate both at 5 minutes before the induction of ischemia and at the time of reperfusion. The myocardial protective effect of JTV519 was completely blocked by pretreatment of the heart with GF109203X, a specific protein kinase C (PKC) inhibitor. In contrast, the effect of JTV519 was not affected by alpha(1)-, A(1)-, and B(2)-receptor blockers that couple with PKC in the cardiomyocyte. Both immunofluorescence images and immunoblots of JTV519-treated left ventricular myocardium and isolated ventricular myocytes demonstrated that this agent induced concentration-dependent translocation of the delta-isoform but not the other isoforms of PKC to the plasma membrane.

CONCLUSIONS

The mechanism of cardioprotection by JTV519 against ischemia/reperfusion injury involves isozyme-specific PKC activation through a receptor-independent mechanism. This agent may provide a novel pharmacological approach for the treatment of patients with acute coronary diseases via a subcellular mechanism mimicking ischemic preconditioning.

[A case of significant natriuresis and improvement of proteinuria by Temocapril, an ACE inhibitor with biliary excretion, in loop diuretics resistant edema in membranous nephropathy]

A 50-year-old man with WPW syndrome and chronic atrial fibrillation controlled by digoxin exhibited nephrotic syndrome due to membranous nephropathy in 1994. For massive edema resistant to loop diuretics, administration of 2 mg/day of Temocapril, an ACE inhibitor with biliary excretion, was started. It provided marked natriuresis and rapid improvement of massive anasarca. Moreover, 6 months later at the time of writing this report, nephrotic proteinuria has decreased and abnormally depressed Ccr level has elevated. For massive edema resistant to loop diuretics in nephrotic syndrome, Temocapril might bring about a beneficial effect possibly through the induction of natriuresis, which has been suppressed by the over-expression of angiotensin II in tubulointerstitium.

Bone marrow transplantation attenuates murine IgA nephropathy: role of a stem cell disorder

BACKGROUND

The pathogenesis of IgA nephropathy is still obscure. The aim of this study was to investigate whether the fundamental pathogenesis of IgA nephropathy lies in bone marrow stem cells (BMCs).

METHODS

We used donors of two different strains for bone marrow transplantation (BMT) into mice with a high content of serum IgA (ddY strain, HIGA mice), a murine model of IgA nephropathy. One group (B6-->HIGA, N = 5) received BMCs of C57BL/6j (B6) mice, and the other (HIGA-->HIGA, N = 8) were reconstituted with BMCs of HIGA mice.

RESULTS

Twenty-six weeks after BMT, in B6-->HIGA mice, mesangial deposits of IgA and C3 were statistically milder than those in HIGA-->HIGA mice. Light microscopic observations disclosed that glomerular sclerosis and mesangial matrix expansion in B6-->HIGA mice were decreased compared with those in HIGA-->HIGA mice. These B6-->HIGA mice also excreted less urinary albumin than HIGA-->HIGA mice. Furthermore, serum levels of IgA in B6-->HIGA mice were markedly lower than those in HIGA-->HIGA mice. Size analysis of serum IgA revealed that macromolecular IgA were notably lower in B6-->HIGA mice than in HIGA-->HIGA mice.

CONCLUSIONS

Our results suggest that qualitative and quantitative changes of serum IgA are determined at the level of stem cells, and that BMT from normal donors can attenuate glomerular lesions in HIGA mice. This approach may offer a new avenue to study the pathogenesis of IgA nephropathy.

Ultrastructural localization of dominantly increased fibronectin in the markedly thickened glomerular basement membrane in a selectively mated murine high IgA strain (HIGA mice)

To clarify which matrix component(s) contributes to glomerular sclerosis with mesangial IgA deposits in a murine high serum IgA strain (HIGA) derived from ddY mice, morphological and immunopathological analyses of glomeruli were performed in comparison with original ddY and BALB/c mice as controls. Significantly increased thickness of the glomerular basement membrane (GBM), especially the lamina densa, was observed in HIGA mice. Immunofluorescent staining showed marked increases in levels of fibronectin and laminin in both the mesangium and capillary wall in aged HIGA mice. Analysis of the distribution of immunogold-labeled antibody in GBM revealed a significant increase (p < 0.0001) and specific orientation of fibronectin in the endothelial side, which suggested that mesangial fibronectin produced at high levels due to IgA deposition extended to the endothelial side of GBM and contributed to the thickening of GBM with further development to glomerulosclerosis in the HIGA mice.

Suppressive effects of Perilla frutescens on spontaneous IgA nephropathy in ddY mice

Perilla frutescens (perilla) is a common herb used in Japan for garnishing raw seafood to protect the alimentary tract from inflammatory diseases. The present study was performed to investigate whether or not perilla prevents the development of lesions of IgA nephropathy in ddY mice which spontaneously develop this disease. After orally administering perilla extract to ddY mice from 8 to 42 weeks of age, the changes in urine, serum, and kidneys were evaluated. Perilla extract significantly suppressed proteinuria and glomerular IgA deposition (p < 0.01 and p < 0.05, respectively). The decreased serum IgA concentration in perilla-treated mice showed a significant correlation with glomerular IgA deposition. Such findings suggest that perilla reduced glomerular IgA deposition via suppression of IgA production in the serum. On the other hand, the nitric oxide concentration in the serum of perilla-treated mice was significantly higher than that observed in the controls. The addition of the sera of perilla-treated mice to quiescent cultured murine mesangial cells resulted in a cell proliferation which was less than in controls, suggesting that perilla might either directly prevent mesangial cell proliferation or prevent proliferation by regulating circulating cytokines. Such results indicate that perilla should prevent IgA nephropathy, thus representing a promising herbal medicine for glomerulonephritis.

Rapid normalization of interleukin-8 production after low-density lipoprotein apheresis in steroid-resistant nephrotic syndrome

BACKGROUND

Low-density lipoprotein apheresis (LDL-A) treatment combined with steroids demonstrated significant improvement of nephrotic proteinuria in steroid- or immunosuppressive-resistant patients from focal and segmental glomerulosclerosis (FGS). The mechanisms of the effect of LDL-A in nephrotic syndrome (NS) are unknown, but a reduction in inflammatory cytokines and chemokines secreted from macrophages has been supposed.

METHODS

Serum levels of interleukin (IL)-8, tumor necrosis factor-alpha (TNF-alpha), and monocyte chemoattractant protein-1 (MCP-1) were measured by enzyme-linked immunosorbent assay in 27 patients with NS [13 with FGS and 14 with minimal change nephrotic syndrome (MCNS)] before and after LDL-A and in 13 age-matched, healthy controls. We also selected three FGS patients who were resistant to steroid therapy for at least one month and who had undergone six LDL-A procedures. The effects of steroids and LDL-A on the production of IL-8, TNF-alpha, and MCP-1 by peripheral blood mononuclear cells (PBMCs) were also determined in some patients.

RESULTS

In NS, the serum levels of IL-8 and TNF-alpha, but not MCP-1, were significantly higher than in healthy controls. After LDL-A, IL-8 and TNF-alpha tended to decrease. IL-8 production by lipopolysaccharide (LPS)-stimulated PBMC, mainly adherent cells, was significantly reduced in both the steroid-resistant FGS group and nontreated NS group compared with controls, but TNF-alpha production was reduced in the only FGS group. After LDL-A, only IL-8 production recovered to the control group level.

CONCLUSION

Significant amelioration of IL-8 production independent of any effect of steroids on LPS-stimulated PBMCs may reflect a beneficial effect of LDL-A in normalizing the function of circulating monocytes in steroid-resistant FGS.

Direct inhibitory effects of simvastatin on matrix accumulation in cultured murine mesangial cells

BACKGROUND

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been demonstrated to suppress glomerular injuries in various renal diseases. These agents inhibit in vitro proliferation of several cell types, including mesangial cells. This effect indicates the ability to ameliorate mesangioproliferative lesions, independent of the improvement of hypercholesterolemia. On the other hand, it is not clear whether HMG-CoA reductase inhibitors directly regulate extracellular matrix (ECM) accumulation from mesangial cells.

METHODS

In this study, to examine the in vitro effects of simvastatin, an HMG-CoA reductase inhibitor, on mRNA expressions of matrix proteins, growth factors, and matrix turnover proteins, we incubated cultured murine mesangial cells stimulated by fetal calf serum (FCS) with or without simvastatin for 24 hours, and Northern analysis was performed.

RESULTS

Simvastatin showed a slightly suppressive effect on mRNA expression of type IV collagen and fibronectin and a slightly up-regulative effect on that of type I collagen, whereas mRNA expression of type III collagen was markedly up-regulated. mRNA expression of platelet-derived growth factor (PDGF)-B chain and PDGF receptor beta-subunit was suppressed, whereas that of transforming growth factor-beta (TGF-beta) was not affected by simvastatin. Concerning matrix turnover proteins, simvastatin markedly reduced mRNA expression of plsminogen activator inhibitor-1 (PAI-1) without affecting the expression of tissue-type plasminogen activator (tPA).

CONCLUSION

These results suggest type-specific modulation of matrix protein production independent of TGF-beta and the suppressive effects of autocrine PDGF by administration of HMG-CoA reductase inhibitors in mesangial cells. Moreover, the beneficial effects of these agents on matrix protein accumulation may be through promoting ECM degradation derived from PAI-1 suppression.

Low density lipoprotein apheresis therapy for steroid-resistant nephrotic syndrome. Kansai-FGS-Apheresis Treatment (K-FLAT) Study Group

BACKGROUND

The pathogenic role of hyperlipidemia in long-standing nephrotic syndrome (NS) is known to be responsible for both the progression of glomerulosclerosis and tubulointerstitial injury, especially in focal segmental glomerulosclerosis (FGS).

METHODS

Aggressive lipid lowering treatment by low density lipoprotein (LDL) apheresis (LDL-A) using a dextran sulfate cellulose column to treat patients with steroid-resistant or frequently recurrent severe NS was performed first without fixing the protocol in eight patients with FGS and one with minimal change nephrotic syndrome (MCNS). The period of NS before LDL-A, number and average intervals of LDL-A until the end of the therapy, and the prognosis were investigated. Next, a multicenter study with a fixed protocol of LDL-A treatment was designed in combination with steroid therapy for treatment twice a week for three weeks and weekly for six weeks, and was performed in 17 patients with FGS. The effects on the state of NS in addition to the change of urinary eicosanoid metabolites and remission rates were evaluated.

RESULTS

In the preliminary study, along with a rapid improvement of hyperlipidemia, a high incidence of remission was achieved by LDL-A performed at relatively short intervals. In the multicenter study with a fixed protocol, there was a significant decrease of urinary protein (P < 0.001) and increase of serum albumin (P < 0.02) as well as a decrease of thromboxane B2 (TXB2) excretion (P < 0.05) after the treatment. Urinary excretion of TXB2 was significantly reduced after LDL-A (P < 0.05). The rate of entering into complete or incomplete remission was 71% with a relatively short duration of nephrotic-range proteinuria using the LDL-A therapy in comparison with steroid therapy alone.

CONCLUSION

The rapid improvement of hypercholesterolemia with LDL-A treatment may provide a new approach for a high rate of improvement in the degree of NS in steroid-resistant NS of FGS and MCNS.

Effect of Perilla frutescens extract on nitric oxide production by cultured murine mesangial cells

The effects of a water extract of perilla (Perilla frutescens Britton) leaves on nitric oxide (NO) production by cultured murine mesangial cells were investigated. Perilla extract significantly induced NO production from mesangial cells, which was enormously augmented without cytotoxity by combination with interferon (IFN)-gamma or tumor necrosis factor-alpha. On the other hand, perilla extract suppressed a large amount of NO production induced by IFN-gamma combined with lipopolysaccharide. Northern blot analysis revealed that such effects of perilla extract were dependent on inducible NO synthase mRNA expression. Perilla extract exhibited an inhibitory effect on cytokine-induced mesangial cell proliferation, and this effect was significantly decreased upon combination with N(G)-monomethyl-L-arginine (L-NMMA), a non-specific NO synthase inhibitor, suggesting that perilla extract inhibits mesangial cell proliferation partially through the induction of NO production. Such results indicate that perilla may be a promising agent for the prevention of the progression of glomerulonephritis.

Up-regulation of glomerular extracellular matrix and transforming growth factor-beta expression in RF/J mice

BACKGROUND

RF/J mice were first reported as a murine model of spontaneous glomerulosclerosis by Gude and Lupton in 1960, but the precise histologic characteristics and immunopathological background of this mouse have not been investigated further.

METHODS

Measurements of serum levels of immunoglobulins, anti-single strand DNA (anti-ss-DNA) antibody, complement (C3), and circulating immune complex (IC) were performed. Analyses of glomerular histological and immunopathological lesions in association with the detection of mRNA expression of collagen IV, TGF-beta, matrix protein turnover related enzymes, matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase-2 (TIMP-2) and platelet-derived growth factor (PDGF) were also performed in young (10-week-old) and elderly (60-week-old) RF/J mice with age-matched BALB/C mice as the controls.

RESULTS

High levels of serum IgA and IgG from as early as 20 weeks of age were noted in the RF/J mice. Serum anti-ss-DNA antibody of aged RF/J mice increased up to 23% of that of aged MRL-lpr/lpr mice, and serum C3 concentration significantly decreased with age, reaching lower levels than that of BALB/c mice. IgA-IC levels were significantly high compared to BALB/C mice both in the early and late stages of life, whereas IgG-IC levels were high only in mice younger than 20 weeks. Semiquantitative and quantitative analyzes of renal histopathological findings revealed significantly marked and age-related mesangial matrix expansion in RF/J mice, with increasing frequency of global glomerular sclerosis and tubulointerstitial damage. On the other hand, although precise measurements of glomerular cell numbers also showed an apparent augmentation in both young and old RF/J mice compared to BALB/C mice, glomerular cellularity decreased with age in RF/J mice. Immunohistochemical study revealed massive immunoglobulin deposition from a young age in association with significantly higher accumulation of matrix proteins, such as types I and IV collagen and laminin from the early stage of life. In addition, in these glomeruli, transforming growth factor-beta1 (TGF-beta1) was highly expressed both in young and old mice. The mRNA expression of MMP-2 was up-regulated only in the early stage of life. Although PDGF mRNA of RF/J mice was significantly up-regulated in the early stage of life, the differences between the mice disappeared in the late stage of life.

CONCLUSIONS

These findings suggest that in RF/J mice, an immunopathological background inducing high serum immunoglobulin and IC levels from the early stage of life is closely related to mesangioproliferative glomerular lesions mediated by PDGF, and that development of massive extracellular matrix accumulation in glomeruli was induced by up-regulated expression of TGF-beta with inappropriate regulation of protein turnover-related enzyme production.

Does circulating erythropoietin reflect progression of IgA nephropathy? Comparison with urinary N-acetyl-beta-D-glucosaminidase

BACKGROUND

Recent reports describe that erythropoietin (Epo) is produced by peritubular interstitial fibroblast-like cells in response to a hypoxic stimulus. We studied serum Epo levels as a possible marker of tubulointerstitial damage in the progression of IgA nephropathy (IgAN), in comparison with urinary (u-) levels of N-acetyl-beta-D-glucosaminidase (NAG), which is mainly derived from proximal tubular cells and is used as a marker of tubular damage.

METHODS

Thirty-eight patients with IgA nephropathy (IgAN) with relatively preserved renal function (serum creatinine: sCr, 0.5-2.2 mg/dl) were examined. The severity of glomerulosclerosis and interstitial fibrosis of the renal biopsy tissue was expressed by semiquantitative grading scores. Clinical parameters including serum creatinine (sCr), blood pressures, and 24-h proteinuria levels were obtained at the renal biopsy. Epo was measured by a radioimmunoassay (RIA) of sera obtained in the morning and u-NAG was measured by colorimetric method of 24-h urine samples.

RESULTS

The mean Epo level of the patients (17.7+/-6.3 mU/ml) was not different from the control level (19.3+/-3.7 mU/ml). There were no significant correlations between Epo levels and red blood cell (RBC) counts, haematocrit (Hct), or haemoglobin (Hb) levels. The mean u-NAG level of the patients (6.7+/-6.2 U/gCr) was significantly higher than the control level (1.9+/-0.5 U/gCr). There was an inverse quantitative correlation between Epo and u-NAG levels in the patients (P<0.02). The u-NAG levels showed quantitative positive correlations with sCr (P<0.001), u-proteins (P<0.001), systolic (SBP) (P<0.001), and diastolic blood pressures (DBP) (P<0.05). Conversely, Epo levels were inversely correlated with sCr, SBP and DBP (each P<0.05). The patients with higher u-proteins (>2.0 g/day) showed significantly decreased Epo levels (P<0.05) than those with lower u-proteins (<2.0 g/day). The both scores of glomerulosclerosis and interstitial fibrosis were positively correlated with the u-NAG levels (each P<0.001), but were not correlated with the Epo levels.

CONCLUSIONS

The significant correlation between u-NAG and serum Epo levels suggests that tubular damage and interstitial cell dysfunction are associated each other in the progression of IgAN. Serum Epo levels bearing inverse correlations with sCr, blood pressure levels and heavy proteinuria seem to reflect clinical severity of IgAN, whereas u-NAG can be more useful progression marker of IgAN bearing correlations with both clinical and histological findings.

Inhibitory effect of Perilla frutescens and its phenolic constituents on cultured murine mesangial cell proliferation

The inhibitory effects of Perilla frutescens and its phenolic constituents on cytokine-induced proliferation of murine cultured mesangial cells were investigated. DNA synthesis of mesangial cells stimulated by platelet derived growth factor (PDGF, 10 ng/ml) or tumor necrosis factor (TNF)-alpha (100 U/ml) was inhibited by the extract of P. frutescens (IC50 values, 3.3 and 1.4 micrograms/ml, respectively). The strength of the anti-proliferative activity was nearly equal in various chemotypes of P. frutescens. Caffeic acid, methyl caffeate, rosmarinic acid, and luteolin 7-O-glucuronide-6"-methyl ester were isolated as active constituents from the extract of the typical strain of P. frutescens, and their IC50 values for PDGF-induced mesangial cell proliferation were estimated as 26 microM, 2.6 microM, 1.8 microM, and 4.1 microM, respectively. We also compared the activities of related flavonoids previously isolated from P. frutescens, and luteolin had the highest anti-proliferative activity.

Mesangiolytic glomerulopathy in severe congestive heart failure

To study the glomerular morphological abnormalities in congestive heart failure (CHF), we analyzed 27 autopsy cases without other causes of renal disease. Their mean age was 59 years, and they showed mild prerenal azotemia. They had generally been treated with digitalis and diuretics, and a few of them with captopril or nifedipine. The abnormal glomerular findings of enlargement, hyperemia, and mesangial thickening were observed at high frequencies (61%, 64%, and 57%, respectively). They characteristically showed mesangiolysis (ML) by the findings of microaneurysms (81%) and mesangial degeneration (70%) such as loose reticular matrix and poor matrix area. In addition, glomerular infiltration of mononuclear leukocytes including macrophages was noted in 70% of the cases. Glomerular enlargement was not correlated with the grade of hyperemia, but it was correlated with the grade of ML index of % glomeruli with microaneurysms (F = 7.22, p < 0.004). There was an inverse relationship between the grades of mesangial thickening and of the ML index (P < 0.005). The number of glomerular leukocytes was positively correlated with mean glomerular size (P < 0.002) and with the ML index (P < 0.03). Notably, the glomerular macrophage-positive cases showed a prominently higher mean ML index than the negative cases (P < 0.005). There was an inverse correlation between the mean glomerular size and the partial oxygen pressure in arterial blood (PaO2; P < 0.01), and a positive correlation between the mean glomerular size and hematocrit (Hct) levels (P < 0.02). The cases positive for mesangiolytic mesangial degeneration showed significantly lower PaO2 values than the cases negative for this lesion (P < 0.04). In the analysis of the various causes of CHF, the patients with congenital cardiac anomalies showed mean levels of the lowest PaO2 (P < 0.02) and the highest Hct (P < 0.03) and histologically the largest mean glomerular size (P < 0.04). There was no difference in the ML index and the glomerular leukocyte number among the subgroups classified by the causes. These results indicate that ML associated with glomerular enlargement is the major glomerular abnormality characteristic in patients with severe CHF and suggest that glomerular infiltration of leukocytes, especially of macrophages, should play an important role in the progression of both ML and glomerulomegaly. The contributions of persistent hypoxia and up-regulated angiotensin II as the causative factors of these glomerular abnormalities in congestive heart failure are discussed.

Localization of insulin receptor-related receptor in the rat kidney

Insulin receptor-related receptor (IRR), a member of the insulin receptor family, is most abundantly expressed in the kidney. However, its endogenous ligand and physiological roles are still unknown. To elucidate the physiological role of IRR, an orphan receptor, in the kidney, we examined the localization of IRR mRNA and its immunoreactivity in the rat kidney by in situ hybridization and immunohistochemistry, respectively. IRR mRNA was found to be exclusively localized in the cortical collecting duct. The localization of IRR immunoreactivity was consistent with that of IRR mRNA. Furthermore, IRR immunoreactivity was found to be localized on the basolateral plasma membrane of the epithelial cells that were a minor cell subpopulation (20 to 30%) of the duct. The present findings indicated that IRR in the kidney was exclusively localized on the basolateral plasma membrane of type B intercalated cells of the cortical collecting duct.

[A case of necrotizing crescentic glomerulonephritis with arteritis due to secondary amyloidosis following rheumatoid arthritis]

A 47-year-old woman was admitted on August 4th, 1995, because of edema of the lower extremities. She had been suffering from RA for about 20 years and underwent total knee-replacements 5 years previously. On admission, nephrotic syndrome and rapidly progressive glomerulonephritis had developed in association with ileus, melena, diarrhea, dyspnea and hemoptysis. She showed a high titer of serum rheumatoid factor (357.0 IU/ml) and amyloid A protein (83.9 micrograms/ml) with positive antinuclear antibodies (homogeneous and speckled patterns). However, anti-neutrophil cytoplasmic autoantibody (ELISA), immune complexes and anti-glomerular basement membrane antibody (ELISA) were negative. Renal biopsy showed microscopic PN overlapping A-type positive amyloidosis. Although the maintenance of hemodialysis was necessary, aggressive immunosuppressive therapy with steroid pulse therapy and frequent plasma exchange provided a rapid improvement of systemic symptoms possibly due to vasculitis. We suggested that in this case, massive necrotizing crescentic glomerulonephritis with systemic arteritis developed on the basis of secondary amyloidosis due to rheumatoid arthritis. In such a case, even if various serum autoantibodies and immune complexes were negative, plasma exchange was suggested to be effective to remove not only pathogenic autoantibodies but also various serum inflammatory cytokines which may be related with severe vasculitis and glomerulitis, in addition to aggressive steroid therapy which may suppress the invasion of inflammatory cells producing these cytokines.

Selective breeding for high serum IgA levels from noninbred ddY mice: isolation of a strain with an early onset of glomerular IgA deposition

An outbred mouse strain known as ddY has been reported to spontaneously develop, late in life, mesangioproliferative glomerulonephritis with a severe glomerular immunoglobulin A (IgA) deposition that mimics human IgA nephropathy. However, the incidence of the disease in this strain is not very high, probably due to its heterogeneous genetic background. Therefore, we attempted to isolate a strain with a high incidence and an early onset of the disease through selection for high serum IgA from the outbred ddY mice. The selection procedure was successful in increasing the serum IgA level of the selected line and proved effective both in increasing the incidence and in accelerating the onset of the disease. We propose to designate this line of mice 'HIGA', denoting a line with high serum IgA levels. More than half of the mice from the HIGA strain showed a moderate to severe glomerular IgA deposition as early as 25 weeks of age. The severe deposition observed was comparable to that occasionally seen in the original nonselected ddY strain after 40 weeks of age. Thus, we have succeeded in generating a mouse model of IgA nephropathy with a high incidence and an early onset of glomerular IgA deposition. Using light microscopy, progressive and marked mesangial matrix accumulation was shown to develop in HIGA mice. However, they showed only mild proteinuria (100-300 mg/dl) and did not show hematuria.

Enhanced production of glomerular extracellular matrix in a new mouse strain of high serum IgA ddY mice

To investigate the relationship between high serum levels of IgA and glomerular lesions, selective mating was performed in high serum IgA ddY mice, a murine model of spontaneously developing mesangioproliferative glomerulonephritis mimicking human IgA nephropathy. The selection and mating of high IgA ddY mice were accomplished when the mice were three to four months old. In the 12th generation of high IgA ddY (HIGA) mice, significantly higher levels of serum IgA from 10 age weeks to 60 weeks (P < 0.0002 to 0.0001) were observed in comparison with BALB/c mice. Relatively high proteinuria was observed at 40 weeks of age, although hematuria was consistently negative. Microscopic observations of renal tissue disclosed a marked glomerular mesangial matrix increase and a reduction of cell proliferation with age by both semiquantitative and morphometric analyses with moderate tubulointerstitial damage. These mesangial matrices were stained markedly by antisera for collagen type IV and by fibronectin, but not by collagen type I. Localization of TGF-beta protein was also detected in the mesangium of the HIGA mice. The positive mesangial IgA deposition was maintained consistently by this mating procedure and became more marked with age. Size analysis of IgA from ten pooled HIGA mice aged 50 to 60 weeks revealed dominant polymeric IgA in sera and dimeric IgA in glomerular eluates. Clonal analysis of serum IgA disclosed heterogeneous spectrotypes in a wide pH range (4.5 to 6.5), in contrast to very limited spectrotypes in the acidic pH range (4.5 to 5.2) of IgA in the glomerular eluates from these mice. The analyses of retroviral gp70 antigen involvement in the HIGA mice disclosed a significant increase of serum levels of gp70 anti-gp70 immune complexes with age, with no relationship to the severity of glomerular gp70 deposition. Northern blot analysis of renal tissue revealed markedly high mRNA expression of collagen type I, IV, fibronectin and TGF-beta even in 10-week-old HIGA mice in comparison with BALB/c mice. The expression became more significant in 60-week-old animals. The genetic background required to induce the expansion of IgA-producing B-cell clones is suggested to be closely related to the increased gene expression of TGF-beta, which induces enhanced glomerular extracellular matrix (especially fibronectin) accumulation in HIGA mice, being possibly mediated by the mesangial deposition of dimeric and highly acidic IgA. This newly established strain may provide a model for investigating the relationship between progressive glomerular sclerotic lesions and the induction of pathogenic IgA in human IgA nephropathy.