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

(E)-N-[(3,4-dimethoxyphenethyl)]-N-methyl-3-(3-pyridyl)-2-propenamide (TJN-331) inhibits mesangial expansion in experimental IgA nephropathy in ddY mice

BACKGROUND

TJN-331 is an inhibitor of transforming growth factor β1 (TGF-β1) production that has similar structural features to the natural product acteoside. This study was performed to examine the antinephritic effects of TJN-331 in a mouse model of experimental IgA nephropathy.

MATERIALS AND METHODS

IgA nephropathy was induced in ddY mice by oral administration of bovine γ globulin, followed by reticuloendothelial blocking by colloidal carbon injection and heminephrectomy. Effects of TJN-331 were examined over oral administration periods from 10 to 15 weeks after the third colloidal carbon injection. Intravenous administration of a TGF-β1-neutralizing antibody was used to investigate the role of TGF-β1 in IgA nephropathy.

RESULTS

Administration of TJN-331 or captopril prevented elevation of serum creatinine. Histopathological examination after both experimental periods showed that TJN-331 inhibited increases in the mesangial matrix index and the number of nuclei per glomerular cross-section, compared with in untreated ddY mice with IgA nephropathy. TJN-331 prevented increase in glomerular TGF-β1 staining without affecting IgA. In the in vitro study, TJN-331 prevented total TGF-β1 production from splenocytes stimulated with concanavalin A. A neutralizing antibody against TGF-β1 prevented increase in the mesangial matrix index and the number of glomerular cells per cross-sectional area.

CONCLUSION

These results suggest that TJN-331 is effective against IgA nephropathy in ddY mice and acts via suppression of TGF-β1 production in glomeruli.

TJN-259 improves mesangial lesions in experimental immunoglobulin A nephropathy in ddY mice

TJN-259 is a chemical substance based on the structural features of the botanically derived ingredient acteoside. This study was performed in order to elucidate the antinephritic effects of TJN-259 in experimental immunoglobulin A (IgA) nephropathy. In this study, 28-week-old ddY mice were used as a spontaneous model of IgA nephropathy. With regard to spontaneous IgA nephropathy, we investigated the effects of TJN-259 administered from 28 to 40 weeks. In addition, an accelerated model of IgA nephropathy was experimentally induced in ddY mice by oral administration of bovine serum albumin, followed by reticuloendothelial blocking by colloidal carbon injection and heminephrectomy. At 10 weeks after the 3rd carbon injection, we also examined the effects of TJN-259 on accelerated IgA nephropathy. To investigate the effects of TJN-259 on transforming growth factor (TGF)-beta1 production in accelerated IgA nephropathy, kidneys were isolated and measured TGF-beta1 by the enzyme-linked immunosorbent assay (ELISA) method. The administration of TJN-259 to mice with spontaneous IgA nephropathy decreased the incidence of mesangial expansion as well as the number of nuclei per glomerular cross-section in comparison with that of non-treated mice. In addition, TJN-259 treatment prevented the increase in the incidence of mesangial expansion, crescent formation, and segmental sclerosis in glomeruli in accelerated IgA nephropathy. TJN-259 also inhibited the increased immunostaining score of collagen type IV and TGF-beta1 in glomeruli of accelerated IgA nephropathy. Treatment with TJN-259 inhibited the increases in renal total and mature TGF-beta1 protein levels in accelerated type IgA nephropathy. TJN-259 failed to inhibit the increase in serum IgA levels in both models. These results suggest that TJN-259 was an effective treatment against IgA nephropathy in ddY mice, acting via the suppression of TGF-beta1 production in glomeruli.

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.

CR1/CR2 deficiency alters IgG3 autoantibody production and IgA glomerular deposition in the MRL/lpr model of SLE

CR1 and CR2 expression is decreased by approximately 50% on B cells of patients with systemic lupus erythematosus (SLE). Expression is also decreased in the MRL/lpr murine model of SLE prior to the development of clinical disease, suggesting that this alteration may play a role in pathogenesis. To determine whether the decrease in receptor levels affects the development of SLE, we analyzed MRL/lpr mice in which CR1/CR2 expression was altered by gene targeting. Mice from each cohort (Cr2+/+, Cr2+/-, and Cr2-/-) were analyzed biweekly for the development of proteinuria and autoantibodies. Kidneys were examined at 12 and 16 weeks for evidence of immune complex deposition and renal disease. Deficiency of CR1/CR2 did not affect survival or development of renal disease as measured by proteinuria. Mice deficient in CR1/CR2 had significantly lower levels of IgG3 rheumatoid factor (RF) and total serum IgG3, suggesting a specific defect in production of IgG3 in response to endogenous autoantigens. Since IgG3 RF has been associated with the development of vasculitis in this model, we examined the mice for alterations in development of this clinical manifestation. Although there was no difference in the development of ear necrosis among the three groups, renal arteritis was not identified in any of the Cr2+/- mice, whereas it was present in 20% of the Cr2+/- and 40% of the Cr2+/+ mice. Finally, significantly higher levels of IgA were seen in the glomeruli of Cr2+/- mice compared to Cr2+/- or Cr2+/+ mice, suggesting that CR1/CR2 are involved in either the regulation of IgA production or the clearance of IgA immune complexes. Together these data support the concept that alterations in CR1/CR2 expression or function affect the regulation of autoantibody production and/or clearance and may have clinical consequences.