Stem cells in renal biology: bone marrow transplantation for the treatment of IgA nephropathy.

The pathogenesis of IgA nephropathy (IgAN) is still obscure. In this study, we investigated whether the fundamental pathogenesis of IgAN lies in bone marrow stem cells (BMCs) and whether bone marrow transplantation from normal C57BL/6j (B6) mice can attenuate glomerular lesions in a murine IgAN model (high serum level IgA ddY mouse; HIGA mouse). Mesangial deposits of IgA and C3 and glomerular sclerosis in HIGA recipients of BMCs from B6 mice (B6-->HIGA) were decreased as compared with those in HIGA recipients of BMCs from HIGA mice (HIGA-->HIGA). Furthermore, the serum levels of IgA and macromolecular IgA were notably lower in B6-->HIGA mice than in HIGA-->HIGA mice. Of note, bone marrow derived H-2(b)-positive cells from B6 donors were observed in the glomeruli of H-2(b)-negative HIGA recipients. Our data suggest that qualitative and quantitative changes of serum IgA are determined at the level of stem cells and that bone marrow transplantation from normal mice may not only replace recipients' immune cells with donors' BMCs, but also regenerate glomerular cells in HIGA mice. This approach offers a promising strategy for the treatment of IgAN.     

Suppressive effects of Perilla frutescens on IgA nephropathy in HIGA mice.

BACKGROUND: Perilla frutescens (perilla) is a herbal medicine used in Japanese traditional Kampo medicine. The present study was conducted to evaluate the anti-nephritic effects of perilla in HIGA mice that spontaneously develop high levels of serum immunoglobulin A (IgA) along with mesangial IgA deposition. METHODS: A perilla decoction and its major active constituent, rosmarinic acid (RsA), were orally administrated to 10-week-old HIGA mice for 16 weeks. At study completion, we measured proteinuria and serum IgA levels and generated histological scores from kidney specimens. In addition, we measured concentrations of IgA in culture media of intestinal Peyer's patch cells and spleen cells obtained from the HIGA mice. RESULTS: Perilla suppressed proteinuria, proliferation of glomerular cells, serum levels of IgA, glomerular IgA and IgG depositions in HIGA mice. Cultured Peyer's patch cells and spleen cells from perilla-treated mice produced significantly less IgA than controls. Rosmarinic acid, by itself, suppressed serum IgA levels and glomerular IgA deposition in HIGA mice. Cultured spleen cells from RsA-treated mice produced less IgA than controls. CONCLUSIONS: The perilla decoction may suppress IgA nephropathy, in part, through modulation of the intestinal mucosal immune system. These effects were caused by RsA acting synergistically with other constituents.     

Role of transforming growth factor-β/Smad signalling pathway in enhanced production of glomerular extracellular matrix in IgA nephropathy of high-serum-IgA ddY mice

SUMMARY: The high-IgA inbred strain (HIGA) of ddY mice, an animal model of human IgA nephropathy, shows consistently high serum IgA levels, progressive mesangial sclerosis and IgA deposition, and elevated renal expression of transforming growth factor (TGF)-β. In the present study the role of the TGF-β/Smad signalling pathway in extracellular matrix (ECM) production was assessed in cultured mesangial cells derived from HIGA mice. the production of type I and type IV collagens in response to TGF-β1, expression of Smad2, Smad4, Smad7, and Sp1 and p300, and phosphorylation of Smad2 by TGF-β1 were assessed in cultured mesangial cells derived from HIGA mice at the age of 10 weeks by comparison with age-matched C57BL/6 mice as controls. In addtion, the expression of p300 and type I and type IV collagens in renal tissues of HIGA mice at the age of 60 weeks was determined. the production of type I and type IV collagens by cultured mesangial cells in HIGA mice was markedly upregulated compared with that in C57BL/6 mice. Although protein expression levels of Smad2, Smad4, Smad7, and Sp1 in the mesangial cells were simiiar in the two mouse strains, upregulation of p300 was marked in HIGA mice. Expression of p300 in renal tissues of HIGA mice was also enhanced in HIGA mice when compared with C57BL/6 mice. In HIGA mice, p300 expression was upregulated in the mesangial cells both in vitro and in vivo. It appears that the upregulation of p300 may be related to glomerular sclerosis associated with IgA nephropathy in HIGA mice.     

IgA nephropathy: lessons from an animal model, the ddY mouse

IgA nephropathy is the most common primary chronic glomerulonephritis, and was first described by J. Berger (Transplant Proc. 1969;1:939-944). Histopathologically, IgA nephropathy is characterized by expansion of glomerular mesangial matrix, with mesangial cell proliferation. Glomeruli typically contain generalized-diffuse granular mesangial deposits of IgA, IgG and C3. Since pathogenesis of IgA nephropathy is still obscure, it is important to try to determine the initiation and progression of this disease using a suitable animal model. Several investigators, including Rifai's group (Rhode Island, USA) and Emancipator's group (Cleveland, Ohio, USA), reported various experimental animal models for this disease. In 1985, Imai et al first reported that the ddY strain of mouse can serve as a spontaneous animal model for IgA nephropathy. These mice show mild proteinuria without hematuria, and mesangioproliferative glomerulonephritis with severe glomerular IgA deposits in association with an increase of serum IgA level (Imai et al. Kidney Int. 1985;27:756-761). Electron-dense deposits are observed in the glomerular mesangial areas by electron microscopy. Furthermore, Muso's group succeeded in generating a mouse model of IgA nephropathy with a high incidence and early onset of glomerular IgA deposition (Miyawaki et al. Nephron. 1997;76:201-207). The selection procedure was successful in increasing the serum IgA level of the selected line. The selected ddY line (HIGA mice) showed only mild proteinuria (100-300 mg/dL) and did not show hematuria. These immunohistopathological findings in ddY mice resemble those in IgA nephropathy patients. The objectives of this review are to introduce the genetic background, Th1/Th2 polarization, expansion of extracellular matrices (ECMs) and treatment of IgA nephropathy of the ddY mouse. These findings from the ddY mouse appear to be useful in determining the pathogenesis and treatment of patients with IgA nephropathy.     

Roles of bone marrow cells in glomerular diseases

Bone marrow transplantation (BMT) has been used as a tool to investigate various roles of bone marrow cells in glomerular diseases. BMT from IgA nephropathy-prone mice caused glomerular IgA deposition associated with increased circulating macromolecular IgA in normal recipients. Conversely, glomerular mesangial lesions of IgA nephropathy-prone mice were markedly diminished by BMT from normal donors, and the circulating levels of macromolecular IgA were also decreased in the recipients. These data suggest that IgA nephropathy may be a stem-cell disease. BMT clearly decreased the glomerular injuries in glomerular diseases other than murine IgA nephropathy. Theoretically, one mechanism underlying the therapeutic effect of BMT is the replacement of the recipients destructive immune cells with the donors bone marrow cells. Interestingly, when BMT was performed by using bone marrow cells of green fluorescent protein (GFP) transgenic mice to investigate the differentiation of bone marrow stem cells in recipients, it was revealed that bone marrow-derived cells differentiated into glomerular cells in mice receiving BMT. This result suggests an alternative mechanism, in that bone marrow cells not only replace harmful immune cells but that they also replenish injured glomerular cells in BMT recipients, which results in the repair of glomerular lesions after BMT. In addition, the glomerular remodeling could participate in maintaining glomerular homeostasis. If the mechanisms of glomerular remodeling are investigated, this could offer a new therapeutic strategy for the repair of glomerular injuries.     

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.     

Interleukin-12 alters the physicochemical characteristics of serum and glomerular IgA and modifies glycosylation in a ddY mouse strain having high IgA levels.

BACKGROUND: We recently developed a ddY mouse strain having high IgA levels (HIGA) that provided a murine model of IgA nephropathy. We additionally showed that administration of interleukin (IL)-12, a potent helper T (Th)1-inducing cytokine, induced an apparent reduction in serum IgA levels. In the present study, we assessed the influence of IL-12 administration on several physicochemical characteristics of nephritogenic IgA molecules in HIGA mice. METHODS: HIGA mice received daily intraperitoneal injections of IL-12 or control injections of phosphate-buffered saline for 3 weeks. Crescent formation and levels of circulating and glomerular IgA were analysed. Moreover, potential changes in charge, size, and glycosylation of serum and glomerular IgA were investigated. RESULTS: In the IL-12 group, glomerular IgA deposition was faint, although crescent formation was more marked than in the control group. Serum IgA levels in IL-12 mice were significantly lower than in controls. IL-12-treated mice also showed markedly decreased acidic and polymeric IgA both in sera and in glomerular eluate. A lectin-binding study revealed a markedly reduced ratio of sialylated and galactosylated IgA in the sera and in glomerular eluate from HIGA mice kidneys. IL-12 treatment significantly increased sialylation and galactosylation of circulating IgA, although glycosylation of IgA in glomerular eluate remained low. CONCLUSIONS: In HIGA mice showing under-glycosylation, IL-12 administration may lead to changes in the physicochemical characteristics of IgA, and this may occur through a shift to Th1. These results suggest that the Th1 and Th2 balance might play a role in the development of immunopathologic lesions in this model of IgA nephropathy.     

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.     

Heminephrectomy causes the progression of glomerulosclerosis and apoptosis in high IgA strain ddY mice

BACKGROUND: The reduction in nephrons in IgA nephropathy is critical to the prognosis of this disease. However, the immunopathological mechanism of the modifications seen in glomerular lesions is not clear. We thus investigated the influence of nephron reduction by heminephrectomy on renal lesions in a high immunoglobulin A inbred strain of ddY mouse (HIGA mouse), which shows progressive mesangial sclerosis with elevated renal expression of transforming growth factor (TGF)-beta. METHODS: Five-week-old HIGA mice were heminephrectomized (Nx), and were evaluated in comparison with a sham-operated group (S) at 40 weeks old. Histological findings, immunoglobulin depositions (IgG, IgA, and IgM), and expressions of cytokine and extracellular matrix proteins (TGF-beta, fibronectin, collagen type I and IV) were analysed. PCNA and TUNEL stainings were performed with electron microscopic detection of apoptosis. Tissue renin-angiotensin systems (RAS) were also investigated by real-time quantitative RT-PCR. RESULTS: In the Nx group, the glomerular tuft area and ratio of mesangial matrix area per tuft were significantly increased, and the glomerular cell count per tuft area was significantly decreased. Glomerular immunoglobulin deposits of IgG, IgA, and IgM in Nx were all significantly expanded in the paramesangium. The glomerular expressions of TGF-beta and the extracellular matrix proteins were significantly increased in Nx mice. In contrast to the significant decrease of PCNA-positive cells, TUNEL-positive cells were significantly increased in Nx. Angiotensin-converting enzyme (ACE) was significantly increased in the renal cortex of Nx. CONCLUSION: Simple heminephrectomy, other than 5/6 renal ablation, of HIGA mice may be a potential model for research into the progressive glomerulosclerosis of human IgA nephropathy. The pathological role of apoptosis is apparently involved in these disease processes, possibly through upregulated RAS.     

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.     

Development of albuminuria and glomerular lesions in normoglycemic B6 recipients of db/db mice bone marrow: the role of mesangial cell progenitors

The pathologic hallmarks of diabetic nephropathy are excess mesangial extracellular matrix (ECM) and mesangial cell proliferation. We previously showed that mesangial cell phenotypic changes play an important role in the pathogenesis of diabetic nephropathy. We concluded that phenotypic changes were present in bone marrow (BM)-derived mesangial cell progenitors, as transplantation of BM from db/db mice, a model of type 2 diabetic nephropathy, transferred the db genotype and a nephropathy phenotype to naive B6 mice recipients. The recipients did not develop diabetes; however, they did develop albuminuria and glomerular lesions mirroring those in the donors (i.e., glomerular hypertrophy, increased ECM, and increased cell number with cell proliferation). We found that matrix metalloproteinase 2 (MMP-2) facilitated invasion of the mesangial cells into ECM and proliferation in vitro. Thus, increased MMP-2 activity in db/db mesangial cell progenitors may partially explain increased mesangial cell repopulation and proliferation in B6 recipients of db/db BM. In summary, BM-derived mesangial cell progenitors may play a crucial role in the development and progression of ECM accumulation and mesangial cell proliferation in this model of diabetic nephropathy in type 2 diabetes.     

Up-regulated TGF-beta mRNA expression in splenic T cells of high IgA-prone mice: a murine model of IgA nephropathy with glomerulosclerosis

BACKGROUND/AIMS: Recently, we established a high serum IgA-prone inbred (HIGA) mouse strain as a murine model of spontaneous IgA nephropathy by selective mating of high serum IgA ddY mice, and found that they showed enhanced production of glomerular extracellular matrix components with increased expression of TGF-beta mRNA and protein in the kidneys. In this study, we examined the roles of lymphocytes in the development of high serum IgA in this strain. METHODS: We performed flow cytometric analyses of T and B cells in splenic mononuclear cells (SMNCs) from these mice using BALB/c mice as normal controls. We also compared serum TGF-beta1 concentrations and TGF-beta mRNA expression levels in the B-cell-depleted (T-cell-rich) fraction of SMNCs in these mice. RESULTS: HIGA mice showed significantly fewer CD3-positive cells compared with BALB/c mice when young, but not when aged. The CD4/CD8 ratio of HIGA mice was lower than that of BALB/c mice, but this difference was not significant. Although the number of B220-positive cells did not vary significantly, the ratio of surface IgA-positive B cells was significantly increased in both young and adult HIGA mice. The B-cell-depleted SMNCs from HIGA mice exhibited higher levels of expression of TGF-beta and TGF-beta1 mRNA than controls from a young age, which were maintained throughout life, but there were no differences in PDGF, MCP-1 or bFGF expression between these two strains. In contrast to local mRNA expression, serum TGF-beta1 concentration was decreased in HIGA mice compared with BALB/c controls. CONCLUSION: These findings suggest that the mating procedure performed to establish HIGA mice selected for a unique phenotype of local up-regulation of TGF-beta production in the kidneys, as well as T cells that may contribute to both the early and consistently high serum IgA expression and enhanced production of renal extracellular matrix components in HIGA mice. Additionally, TGF-beta1 may act locally, not systemically, in a paracrine or autocrine manner.     

肾小管肝型脂肪酸结合蛋白对小鼠IgA肾病的肾脏保护作用

Objective To investigate the renoprotection of tubular L-FABP in murine IgA nephropathy (IgAN） induced by bone marrow transplantation(BMT). Methods IgAN models were reconstituted by BMT from IgAN-prone mice into mice (Tg) transgenically tubular overexpressing human L-FABP (hL-FABP) and wild type (WT) mice. These recipients were sacrificed at 6 and 12 weeks after BMT and their kidneys were collected. The expressions of hL-FABP, fibronectin (FN) and monocyte chemoattractant protein-1(MCP-1) mRNA were detected by real-time PCR. hL-FABP, FN, type Ⅳ collagen (Col Ⅳ), hemeoxygenase-1(HO-1) and 4-hydroxy-2-nonenal (4-HNE) modified proteins were detected by Western blotting. The distribution of hL-FABP and FN protein in kidney was detected by immunohistochemistry. The level of serum IgA, urinary albumin and urinary hL-FABP was detected by ELISA. Results (1) IgAN was reconstituted in both Tg and WT mice by BMT: mesangial IgA deposition and up-regulation of serum IgA. The levels were not significantly different between two groups (Tg-ddY and WT-ddY). (2) hL-FABP was expressed in proximal tubular cells of normal Tg mice. The mRNA (1.62±0.32 vs 0.46±0.09, P<0.01) and protein expression (1.74±0.76 vs 1.14±0.31, P<0.01) of hL-FABP was up-regulated in Tg-ddY kidney and urinary hL-FABP level (?滋g/g creatinine) was significantly increased (59.87±26.75 vs 31.01±14.86, P<0.05) at the 6th week after BMT. (3) WT-ddY mice showed a significantly higher urinary albumin level (mg/L) (828±656 vs 82±22, P<0.01), severer mesangial matrix expansion (P<0.01),more glomerular FN and Col Ⅳ deposition at the 12th week. (4) Up-regulation of renal hL-FABP was associated with significant suppression of renal HO-1 expression (P<0.05), accumulation of 4-HNE modified proteins (P<0.05) and MCP-1 mRNA expression (P<0.01) in Tg-ddY mice. Conclusion Tubular L-FABP may lessen the progression of glomerular damage at early stages of IgAN by reducing oxidative stress and inflammatory mediators.     

Effect of soluble form CTLA‐4 on spontaneous IgA nephropathy in ddY mice

The aim of the present study was to examine the role of CD28‐B7 signalling in the development of glomerulonephritis in ddY mice, an animal model for IgA nephropathy. To achieve this aim, we investigated whether the CTLA‐4 (CD152) fusion protein, which binds to B7.1 (CD80) and B7.2 (CD86), affects glomerular pathological changes (including IgA deposition), or functional parameters (such as serum creatinine and proteinuria). Each group (n = 4) was given either human CTLA‐4 fused with human IgG (CTLA4Ig) or control human IgG1. All treated groups of mice were injected intraperitoneally at a dose of 0.1 mg twice a week for the duration of the study. Mice given control human IgG1 progressively developed typical mesangioproliferative glomerulonephritis, with remarkable glomerular IgA deposits. In contrast, mice treated with CTLA4Ig showed a significant reduction in proteinuria and mesangioproliferative change, with an expansion of the mesangial matrix at 40 weeks of age. The serum IgA levels of these mice were considerably lower than those in mice given the control human IgG1. A direct immunofluorescence study showed the reduction of glomerular IgA deposits in CTLA4Ig‐treated mice. We have demonstrated for the first time that the development of spontaneously occurring IgA nephropathy can be prevented in ddY mice by blocking the CD28‐B7 interaction using a soluble form of CTLA4Ig. These results suggest that a costimulatory signal via CD28‐B7 may play a crucial role in the development and progression of IgA nephropathy.     

Th1 polarization in murine IgA nephropathy directed by bone marrow-derived cells

IgA nephropathy is the most common form of progressive glomerulonephritis although the pathophysiology of this nephropathy is unclear. The ddY mouse is a spontaneous animal model with variable incidence and extent of glomerular injury mimicking human IgA nephropathy. Here, we transplanted bone marrow cells from 20-week-old ddY mice with beginning or quiescent IgA nephropathy into irradiated similar ddY mice, C57Bl/6 (Th1 prone) mice, or BALB/c (Th2 prone) mice. Serum IgA/IgG complex and Th1/Th2 polarization of spleen cells was determined by enzyme-linked immunosorbent assay and confirmed by fluorescent cytometric analysis. The ddY mice with commencing IgA nephropathy demonstrated strong polarization toward Th1, while those with quiescent disease were Th2 polarized. Serum levels of IgA/IgG2a immune complex significantly correlated with the severity of the glomerular lesions. Bone marrow taken from mice with commencing IgA nephropathy conferred IgA nephropathy with Th1 polarization in recipient-quiescent mice, while transplantation from the quiescent mice ablated glomerular injury and mesangial IgA/IgG deposition in those commencing IgA disease. However, adoptive transfer of CD4(+) T cells from those whose disease began failed to induce any IgA deposition or renal injury. Our study suggests that bone marrow cells, presuming IgA producing cells, may initiate this disease. Th1 cells may be involved in the pathophysiology of the disease after glomerular IgA deposition.     

Pathogenetic and therapeutic approaches to IgA nephropathy using a spontaneous animal model,the ddY mouse

IgA nephropathy is the most common primary chronic glomerulonephritis in the world and was first described by Berger et al. (J Urol Nephrol 74:694–695;1968). Histopathologically, IgA nephropathy is characterized by expansion of the glomerular mesangial matrix with mesangial cell proliferation. Glomeruli typically contain generalized diffuse granular mesangial deposits of IgA (mainly IgA1), IgG and C3. In advanced patients, global glomerular sclerosis, crescent formation and tubulo-interstitial fibrosis are marked in light microscopy. IgA nephropathy is generally considered to be an immune-complex mediated glomerulonephritis. Although more than 40 years have passed since this disease was firstly described, the pathogenesis/initiation factors of IgA nephropathy are still obscure. The objective of this review is to explain the pathogenesis and treatment based on our previous data of ddY mouse, a spontaneous animal model for IgA nephropathy.     

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.     

Effect of soluble form CTLA-4 on spontaneous IgA nephropathy in ddY mice

The aim of the present study was to examine the role of CD28-B7 signalling in the development of glomerulonephritis in ddY mice, an animal model for IgA nephropathy. To achieve this aim, we investigated whether the CTLA-4 (CD152) fusion protein, which binds to B7.1 (CD80) and B7.2 (CD86), affects glomerular pathological changes (including IgA deposition), or functional parameters (such as serum creatinine and proteinuria). Each group ( n = 4) was given either human CTLA-4 fused with human IgG (CTLA4Ig) or control human IgG1. All treated groups of mice were injected intraperitoneally at a dose of 0.1 mg twice a week for the duration of the study. Mice given control human IgG1 progressively developed typical mesangioproliferative glomerulonephritis, with remarkable glomerular IgA deposits. In contrast, mice treated with CTLA4Ig showed a significant reduction in proteinuria and mesangioproliferative change, with an expansion of the mesangial matrix at 40 weeks of age. The serum IgA levels of these mice were considerably lower than those in mice given the control human IgG1. A direct immunofluorescence study showed the reduction of glomerular IgA deposits in CTLA4Ig-treated mice. We have demonstrated for the first time that the development of spontaneously occurring IgA nephropathy can be prevented in ddY mice by blocking the CD28-B7 interaction using a soluble form of CTLA4Ig. These results suggest that a costimulatory signal via CD28-B7 may play a crucial role in the development and progression of IgA nephropathy.     

The clinical use of serum beta-2-microglobulin and fractional beta-2-microglobulin excretion in IgA nephropathy

We measured serum beta-2-microglobulin (B2-m) and fractional beta-2-microglobulin excretion in 29 patients with IgA nephropathy. The mean serum B2-m in IgA nephropathy patients was significantly higher than that of healthy controls (p less than 0.025). The serum B2-m correlated well with serum creatinine and endogenous creatinine clearance (p less than 0.01). Patients with diffuse mesangial proliferation and glomerulosclerosis had a significantly higher level of B2-m than those with minor glomerular pathology (p less than 0.01). Patients with hypertension had significantly different levels of serum B2-m from normotensive patients (p less than 0.01). The mean fractional B2-m excretion in IgA nephropathy patients was significantly higher than that of healthy controls (p less than 0.001). Patients with moderate tubulo-interstitial involvement had significantly higher fractional B2-m excretion than those with mild tubulo-interstitial changes (p less than 0.01). Our study suggests that serum B2-m and fractional B2-m excretion may be useful indicators in the long-term prognosis of patients with IgA nephropathy.     

Extrarenal cytokines modulate the glomerular response to IgA immune complexes.

Clinical episodes of IgA nephropathy coincide recurrently with microbial infections. Cytokines produced during such infections may play a role in the pathogenesis of IgA-associated glomerulonephritis. To test this hypothesis, we examined the influence of passively administered proinflammatory cytokines (IL-1, IFN-gamma and IL-6) on the development of glomerulonephritis in an experimental model of IgA nephropathy. Glomerular IgA immune deposits were induced in mice by administration of IgA anti-phosphorylcholine (PC) with either a PC-containing carbohydrate antigen of Pneumococcal C polysaccharide (PnC) or a protein antigen of PC-conjugated bovine serum albumin (PC-BSA). The effect of IL-1 on the IgA-PC-BSA induced glomerular changes resulted in an increase of mesangial hypercellularity that was associated with mild proteinuria and hematuria. Mice treated with IL-1 and IgA-PnC developed diffuse proliferative glomerulonephritis with proteinuria and hematuria. In contrast, IL-6 treatment with IgA-PC-BSA of IgA-PnC failed to exert any significant renal effect. The combination of IL-6 and IL-1, however, intensified the mesangial hypercellularity of the IgA-PC-BSA, and induced severe proliferative glomerulonephritis with inflammatory monocytes and neutrophils infiltrates in the IgA-PnC treated mice. These glomerular changes were also accompanied by increased proteinuria and hematuria. Similarly, the combination of IFN with IL-1 produced histologic changes and compromised renal function more than IFN or IL-1 exerted independently. These results suggest that extrarenal cytokines influence the renal response to IgA immune deposits. We also conclude that a synergy of multiple cytokines and nephritogenic antigens immobilized in glomerular IgA immune deposits may lead to rapid progression of IgA-associated glomerulonephritis.