Intraglomerular expressions of IL-1 alpha and platelet-derived growth factor (PDGF-B) mRNA in experimental immune complex-mediated glomerulonephritis

VEGF/VEGFR2 and PDGF-B/PDGFR-β expression in non-metastatic renal cell carcinoma: a retrospective study in 1,091 consecutive patients

PURPOSE

We aimed to investigate the correlations between the expression of VEGF, PDGF-B, and their receptors (VEGFR2 and PDGFR-β) with pathologic stage or cell type in non-metastatic renal cell carcinoma.

MATERIALS AND METHODS

VEGF, VEGFR2, PDGF-B, and PDGFR-β protein expression were evaluated immunohistochemically in prospectively collected 1,423 tumour samples obtained during radical or partial nephrectomy at a tertiary referral center. Intensity of expression was quantified on a scale of 0 to 3, and was compared among renal cell carcinoma cell types.

RESULTS

The study cohort consisted of 1,091 patients, of mean age 54 years, including 968 (88.7%) with clear cell, 82 (7.5%) with papillary, 31 (2.8%) with chromophobe, 4 (0.4%) with unclassified, and 6 (0.5%) with other types of renal cell carcinoma. VEGF expression increased with higher T and N stage and Fuhrman nuclear grade. PDGFR-β expression was highest in clear cell renal cell carcinoma, whereas VEGF and PDGF-B expression were highest in papillary renal cell carcinoma. After adjusting for T stage and Fuhrman nuclear grade using multivariate logistic regression analysis, VEGF (OR = 3.57, P < 0.001), VEGFR2 (OR = 1.82, P = 0.017), and PDGF-B (OR = 2.46, P = 0.019) expression were significantly greater in papillary than in clear cell type.

CONCLUSIONS

Our results indicate that the cytoplasmic expression of VEGF, VEGFR2, PDGF-B, and PDGFR-β in RCC tumour cells is different in various pathologic stage and cell type. Notably, VEGF and PDGF-B expression are higher in papillary than in clear cell renal cell carcinoma. Further studies using quantitative measurement of proangiogenic factors in tumour cell are needed.

The platelet-derived growth factor system in renal disease: an emerging role of endogenous inhibitors

The platelet-derived growth factor (PDGF) family consists of four isoforms which are secreted as homodimers (PDGF-AA, PDGF-BB, PDGF-CC and PDGF-DD) or heterodimers (PDGF-AB), and two receptor chains (PDGFR-α and -β). All members of the PDGF system are constitutively or inducibly expressed in renal cells and are involved in the regulation of cell proliferation and migration, the accumulation of extracellular matrix proteins and the secretion of pro- and anti-inflammatory mediators. Particular roles have been identified in mediating mesangioproliferative changes, renal interstitial fibrosis and glomerular angiogenesis. Different endogenous inhibitors of PDGF-induced biological responses exist which affect the activation/deactivation of PDGF isoforms, the activity of the PDGFRs, or which block downstream signaling pathways of the autophosphorylated PDGFRs. The novel endogenous inhibitor nephroblastoma overexpressed gene (NOV, CCN3) reduces PDGF-induced cell proliferation and is downregulated by PDGF isoforms itself. Among all identified inhibitors only few "true" PDGF antagonists have been identified. A better understanding of these inhibitors may aid in the design of novel therapeutic approaches to PDGF-mediated diseases.

H1-A extracted from Cordyceps sinensis suppresses the proliferation of human mesangial cells and promotes apoptosis, probably by inhibiting the tyrosine phosphorylation of Bcl-2 and Bcl-XL

H1-A, a pure compound used in traditional Chinese medicine, is effective in the treatment of autoimmune disorders of MRL lpr/lpr mice. We have previously reported that after 8 weeks of oral therapy with H1-A, 40 microg/kg/day, MRL lpr/lpr mice demonstrated significantly less proteinuria, lower serum creatinine levels, and less renal mesangial proliferation than mice in an untreated group. To clarify the pharmacologic properties of H1-A, we studied its cellular and subcellular effects in cultured human mesangial cells. Our results show that H1-A inhibits cell proliferation and promotes the apoptosis of interleukin (IL)-1- and platelet-derived growth factor (PDGF)-BB-activated human mesangial cells in vitro. Uptake of tritiated thymidine was nearly totally suppressed by the addition of 12.5 micromol/L H1-A (counts per minute decreased from 3905 +/- 70 to 141 +/- 5). The population of S-phase cells decreased from 15.5% +/- 1.7% to 10.0% +/- 0.3%, and G0 + G1 phase cells increased from 68.8% +/- 0.07% to 74.6% +/- 0.05%. This suppression was not a result of cytotoxicity. Apoptosis of human mesangial cells was detectable after treatment with 12.5 or 25 micromol/L H1-A. Using immunoprecipitation and immunoblotting, we found that H1-A inhibits tyrosine phosphorylation of human mesangial proteins and that Bcl-2 and Bcl-XL were probably among these proteins. These findings suggest that H1-A modulates some subcellular signal-transduction pathways and changes the balance between proliferation and apoptosis of mesangial cells in vitro or in vivo. H1-A may be effective in the management of autoimmune disorders, and the modulation of the signal transduction proteins Bcl-2 and Bcl-XL may represent a target for future pharmacologic interventions.

Induction of cyclooxygenase-2 expression in glomeruli by aggregated protein

Cyclooxygenase has two isozymes, a constitutive type (cyclooxygenase-1) and an inducible type (cyclooxygenase-2). The aim of the present study was to determine whether cyclooxygenase-2 is associated with the increased production in prostaglandin E2 in glomeruli by aggregated protein. Mice were injected with aggregated bovine serum albumin. Glomeruli were isolated using sieves and a magnet. Production of prostaglandin E2 was increased in glomeruli after injection of aggregated bovine serum albumin. RT-PCR analysis indicated enhanced expression of cyclooxygenase-2 mRNA in aggregated bovine serum albumin-loaded glomeruli. Western blotting analysis indicated an increase in cyclooxygenase-2 protein in glomeruli by aggregated bovine serum albumin. Glomeruli were incubated with indomethacin, NS-398 or niflumic acid in the presence of arachidonic acid. Indomethacin resulted in remarkable reduction of prostaglandin E2 levels in aggregated bovine serum albumin-loaded glomeruli. Niflumic acid also inhibited prostaglandin E2 production, and its inhibitory rate was more than that of NS-398. In conclusion, aggregated protein induces cyclooxygenase-2 in glomeruli, suggesting that cyclooxygenase-2 is involved in the process of disposal of aggregated protein in glomeuli.

Thromboxane A(2) causes retarded clearance of aggregated protein in glomeruli of nephritic mice

Recently, it has been demonstrated that the production of prostaglandins and thromboxane is increased in patients with chronic glomerulonephritis and lupus nephritis. We recently demonstrated that thromboxane A(2) delayed the clearance of heat-aggregated bovine serum albumin deposited in glomeruli. In the present study, we investigated the effect of thromboxane A(2) on the clearance of macromolecules in nephritic glomeruli. First, we attempted to clarify the conditions for the clearance of heat-aggregated bovine serum albumin in nephritic glomeruli, using glomeruli isolated from control and anti-glomerular basement membrane nephritic mice. Heat-aggregated bovine serum albumin was injected twice into each mouse. The glomeruli were then isolated and incubated in culture medium. The heat-aggregated bovine serum albumin content of control glomeruli gradually diminished with incubation time up to 24 h. The heat-aggregated bovine serum albumin content of nephritic glomeruli was 69% higher than that of control glomeruli at 24 h incubation. The production of thromboxane B(2) (the stable metabolite of thromboxane A(2)) in nephritic glomeruli showed about a sevenfold increase compared with control. DP-1904 [6-(1-imidazolylmethyl)-5,6,7,8-tetrahydro-naphthalene-2-carboxylic acid hydrochloride], a thromboxane A(2) synthase inhibitor, and KT2-962 [sodium 3-(4-(4-chlorophenyl-butylsulfonamido) butyl)-6-isopropylazulene-1-sulfonate], a selective thromboxane A(2) receptor antagonist, significantly reduced the heat-aggregated bovine serum albumin content in nephritic glomeruli. Normal glomeruli treated with U-46619 [15S-hydroxy-11a,9a-(epoxymethano)prosta-5Z,13E-dienoic acid], a stable analogue of thromboxane A(2), had significantly more heat-aggregated bovine serum albumin than control glomeruli. We next investigated whether thromboxane A(2) could affect the uptake/disposal of heat-aggregated bovine serum albumin by cultured rat mesangial cells. U-46619 significantly enhanced the uptake and inhibited the disposal of heat-aggregated bovine serum albumin by mesangial cells. Finally, we performed experiments to elucidate the role of the thromboxane A(2) receptor (TP receptor) in the clearance of heat-aggregated bovine serum albumin using TP-deficient mice. The glomerular heat-aggregated bovine serum albumin content of TP-receptor knockout [TP(-/-)] mice was lower than that of wild-type [WT(+/+)] mice. U-46619 dose dependently increased the uptake of heat-aggregated bovine serum albumin by mesangial cells in WT(+/+) mice, but not in the TP(-/-) mice. These findings suggest that thromboxane A(2) retards the clearance of aggregated protein in nephritic glomeruli and may contribute to the pathophysiology of glomerulonephritis.

Decoy against nuclear factor-kappa B attenuates myocardial cell infiltration and arterial neointimal formation in murine cardiac allografts

Acute rejection and graft arteriopathy in cardiac transplantation limit the long-term survival of recipients; these processes are enhanced by several cytokines and adhesion molecules. Nuclear factor-kappa B (NFkappaB) is critical in the transcription of multiple genes involved in inflammation and cell proliferation. To test the hypothesis that NFkappaB decoy can attenuate acute rejection and arteriopathy, we performed single intraluminal delivery of NFkappaB decoy into murine cardiac allografts using a hemagglutinating virus of Japan (HVJ)-artificial viral envelope (AVE)-liposome method. No decoy or scrambled decoy transfer was performed for control. Hearts were heterotopically transplanted from BALB/c to C3H/He mice (major mismatch group) and from DBA/2 to B10.D2 mice (minor mismatch group). Nontreated or scrambled decoy transfected allografts of the major mismatch group were acutely rejected, while NFkappaB decoy prolonged their survival. While severe cell infiltration and intimal thickening with enhancement of inflammatory factors were observed in untreated or scrambled decoy-treated allografts of minor mismatch group at day 28, NFkappaB decoy attenuated these changes. We conclude that NFkappaB is critically involved in the development of acute as well as chronic rejection of the transplanted hearts. NFkappaB decoy attenuates both acute rejection and graft arteriopathy by blocking the activation of several genes.

The C5a receptor is expressed by human renal proximal tubular epithelial cells

The C5a receptor is expressed by a variety of cell types. These studies demonstrate by immunohistochemistry that the receptor is present on the surface of proximal and distal tubular epithelial cells from normal kidney. In addition, the receptor was detected on transitional epithelial cells of the ureter and bladder. Primary proximal tubular cultures and a proximal tubular cell line both also expressed the C5a receptor, as demonstrated by immunofluorescence and by FACS analysis. The presence of mRNA encoding the receptor was confirmed by reverse transcriptase-polymerase chain reaction analysis. As opposed to its effect on glomerular mesangial cells, the receptor did not mediate a proliferative response by the proximal tubular cells. C5a also did not enhance the synthesis/secretion of transforming growth factor-beta 1, monocyte chemoattractant protein-1, platelet-derived growth factor-AB or tumour necrosis factor-alpha by cultured proximal tubular cells. Therefore, although the C5a receptor clearly is expressed by proximal tubular cells, clarification of its functional relevance on this cell type awaits further studies.

Prevention of cardiac allograft arteriosclerosis using antisense proliferating-cell nuclear antigen oligonucleotide

Cardiac allograft arteriosclerosis limits long-term survival of recipients and is characterized by intimal thickening comprised of proliferative smooth muscle cells. Proliferating-cell nuclear antigen (PCNA) plays a pivotal role in the cell cycle regulatory genes involved in smooth muscle cell proliferation. To test the hypothesis that antisense PCNA oligodeoxynucleotide (ODN) can prevent allograft arterial intimal hyperplasia, we performed single intraluminal delivery of the antisense or sense PCNA ODN or no transfer into murine cardiac allografts. DBA/2 murine hearts were transfected and transplanted into B10.D2 mice; the allografts were harvested 4 weeks later. Severe intimal thickening with enhanced expression of PCNA was observed in untransfected and sense PCNA ODN-treated allografts, whereas antisense PCNA ODN prevented neointimal formation.

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.

Suppression of mesangial-cell proliferation by trapidil in glomerulonephritis induced by anti-thymocyte serum in rats

Trapadil (Mochida Pharmaceuticals, Japan), an antiplatelet drug, suppresses the growth of several cell types and is thought to antagonize platelet-derived growth factor. The effects of trapidil on mesangial-cell proliferation in glomerulonephritis induced by anti-thymocyte serum in Wistar rats were investigated. Control rats were treated with phosphate-buffered saline (group I); group II rats were injected with a single dose of anti-thymocyte serum (8 ml/kg body weight), and group III rats were treated with both a single dose of anti-thymocyte serum (8 ml/kg body weight) and with trapidil (5 mg/kg body weight/day). Three rats in each group were killed on day 3, and the other three on day 10. Control rats showed no significant histological changes on day 3 or day 10. In group II, on day 3, there was a marked decrease in glomerular cell numbers, with mesangiolysis. Histologically severe mesangial-cell proliferation with expansion of mesangial areas was noted on day 10. None of the rats in group III showed mesangial alterations, histologically, indicating that mesangial-cell proliferation was suppressed by trapidil. This suppression may result from antagonism of the binding of platelet-derived growth factor to the specific surface receptors in the mesangial cells. Trapidil may have clinical value in the treatment of mesangial-cell proliferative glomerular diseases.

PDGF and TGF-beta contribute to the natural course of human IgA glomerulonephritis

PDGF and TGF-beta are known mediators of mesangial cell proliferation and matrix expansion. The presence of these regulatory factors was examined in 30 renal biopsies from patients with IgA glomerulonephritis (IgA-GN) at the mRNA and protein level. Normal renal tissue served as control. The mRNA expression of PDGF A/B chains, PDGF-beta R and TGF-beta 1 was evaluated by means of RT/PCR with subsequent Southern blot hybridization and/or non-radioactive in situ hybridization. In addition, PDGF-AB/BB, PDGF-beta R, TGF-beta isoforms (beta 1, beta 1 + 2, beta 2 + 3), the small TGF-beta 1 latency associated peptide (TGF-beta 1 LAP) and the extracellular matrix proteins tenascin and decorin were analyzed by immunocytochemistry. The expression of growth factors was correlated with light microscopic and clinical features. Compared to normal control kidneys, an increased expression of PDGF-BB/PDGF-beta R mRNAs and the corresponding proteins was observed in all biopsies with IgA-GN. Up-regulation was related to the degree of glomerular proliferation and the extent of fibrosing interstitial lesions. In contrast, there was a discordance between TGF-beta 1 mRNA and protein expression (evaluated by immunocytochemistry). In all biopsies, irrespective of the stage of the disease, abundant TGF-beta 1 transcripts were detected, whereas TGF-beta 1 immunoreactivity was expressed to a lesser degree and disclosed a more variable staining pattern. In patients with significant proliferative glomerular lesions and minor tubulointerstitial alterations, TGF-beta 1 positivity was confined to areas of glomerular proliferation, whereas in cases with more severe histology including sclerosing lesions TGF-beta 1 immunoreactivity was less prominent. The distribution and the intensity of TGF-beta 1 LAP staining commonly exceeded the positivity noted for TGF-beta 1, indicating only limited TGF-beta 1 activation. A decreased reactivity for tenascin accompanied the morphological features of glomerular sclerosis. The staining patterns and the fact that only very few inflammatory cells, particularly CD68 positive monocytes/macrophages, were detected in glomeruli confirm that predominantly resident glomerular cells (mesangial and endothelial cells) are the major source of up-regulated growth factor production in IgA-GN. Since the expression of PDGF-AB/BB paralleled the severity of proliferative glomerular changes, PDGF seems to represent a potential indicator of activity in this condition. It is suggested that an imbalance between PDGF and TGF-beta (by restricted translation and/or activation) production contribute to the progressive nature of IgA-GN.