Mycophenolate mofetil slows progression in anti-thy1-induced chronic renal fibrosis but is not additive to a high dose of enalapril

Tubulointerstitial inflammation and fibrosis are hallmarks of chronic progressive renal diseases. To characterize the functional interaction between cell infiltration and matrix expansion, this study compared the immunosuppressant mycophenolate mofetil (MMF), intended as primarily anti-inflammatory intervention, the angiotensin-converting enzyme inhibitor enalapril, intended as primarily an anti-fibrotic drug, and a combination of both as anticipated anti-inflammatory/anti-fibrotic intervention. The model used was anti-thy1-induced chronic-progressive glomerulosclerosis (cGS) in the rat, where a brief anti-thy1-induced glomerular injury progresses spontaneously toward tubulointerstitial fibrosis and renal insufficiency. cGS was induced by injection of anti-thy1 antibody into uninephrectomized Wistar rats. One week after disease induction, animals were randomly assigned to the following groups: cGS, cGS plus MMF (20 mg·kg body wt−1·day−1), cGS plus high-dose enalapril (12 mg·kg body wt−1·day−1), and cGS plus both. At week 16 after disease induction, MMF or enalapril alone reduced signs of chronic renal disease significantly and similarly compared with the untreated cGS group. Variables measured included proteinuria, blood pressure, tubulointerstitial and glomerular matrix accumulation, expression of transforming growth factor-β1, fibronectin, and plasminogen activator inhibitor-1, infiltration of lymphocytes and macrophages, plasma creatinine and urea levels, and glomerular filtration rate. Combined MMF and enalapril treatment was not superior to single therapy. In conclusion, MMF slows the progression of chronic renal fibrosis and renal insufficiency as effectively as high-dose enalapril in the anti-thy1-induced chronic-progressive glomerulosclerosis model. The dual anti-inflammatory/anti-fibrotic intervention does not yield additive renoprotective effects, indicating that MMF and enalapril interfere with similar or very closely related pathways involved in progression of renal disease.

Post-inflammatory glomerular remodeling is influenced by transformed mesangial cells

To identify the role of transformed mesangial cells (MC) during glomerular remodeling, anti-thymocyte-1 (Thy1) nephritis; modified Thy1 nephritis (injections of anti-Thy1 antibody four times, weekly); and Thy1 nephritis treated with signal transduction inhibitor 571 (Thy1 + STI); were analyzed. At week 1 the index of MC proliferation in modified Thy1 nephritis and in mesangiolysis in Thy1 + STI nephritis was highest among the three models. From week 4, the index of alpha-smooth muscle actin (alpha-SMA) was significantly higher in modified Thy1 nephritis than the other two models. Production of the mesangial matrix including type IV collagen was increased in modified Thy1 but inhibited in Thy1 + STI nephritis. In contrast to modified Thy1 nephritis, the capillary numbers in glomeruli recovered to normal at week 4 in Thy1, and at week 8 in Thy1 + STI nephritis. At week 12, both the adhesive and sclerotic index was significantly higher in modified Thy1 than in the other two models. Data suggest that a moderate amount of mesangial matrix results in a complete repair of capillary loops. Overproduction of the mesangial matrix retards capillary remodeling and finally induces glomerulosclerosis. Insufficient mesangial matrix delays the repair of capillary loops. In conclusion, transformed MC may influence glomerular remodeling by changing the amount of mesangial matrix.

Interaction of human Thy-1 (CD 90) with the integrin αvβ3 (CD51/CD61): an important mechanism mediating melanoma cell adhesion to activated endothelium

The expression of the alphavbeta3 integrin (CD51/CD61) on human melanoma cells has been shown to be associated most closely with tumor progression and metastases formation in melanoma. Here, we demonstrated a specific interaction of the alphavbeta3 integrin on melanoma cells with the human Thy-1, an inducible cell adhesion molecule expressed on the cell surface of activated endothelial cells (EC). The interaction was shown by the binding of purified Thy-1 protein to alpha(V)beta(3) transfected cells, to alphavbeta3-expressing melanoma cells and to purified alpha(V)beta(3) integrin. Moreover, melanoma cells adhere specifically to Thy-1 transfectants via alphavbeta3 on melanoma cells showing the functional relevance of this interaction for cell adhesion. Finally, the importance of the alphavbeta3/Thy-1 interaction for the adhesion of melanoma cells to the activated endothelium was confirmed under static and flow conditions by the inhibition of melanoma cell adhesion to and transmigration across activated EC by blocking the alphavbeta3/Thy-1 interaction. In conclusion, we have identified a new pair of adhesion molecules Thy-1 and alphavbeta3 mediating the interaction of melanoma cells and activated EC. These data explain at least in part the high tumorigenicity of alphavbeta3-expressing melanoma cells and the association of alphavbeta3-positive melanoma cells with a high risk of metastasis and poor prognosis.

The keratan sulfate disaccharide Gal(6S03) beta1,4-GlcNAc(6S03) modulates interleukin 12 production by macrophages in murine Thy-1 type autoimmune disease

It has been reported that disaccharides of the glycosaminoglycans (GAGs), heparin, or heparan sulfate suppress the production of cytokines. Therefore, we examined the effects of GAGs (keratan sulfate, hyaluronan, chondroitin, chondroitin sulfate, and heparin sulfate) disaccharides on production of interleukin (IL)-12, a pivotal cytokine in the Th-1 type immune system. Among the GAG disaccharides, only a keratan sulfate disaccharide, Gal(6-SO(3))-GlcNAc(6-SO(3)) (L4), suppressed IL-12 production in macrophages stimulated with lipopolysaccharides and interferon-gamma. Neither keratan sulfate chains nor keratan sulfate tetrasaccharides elicited any change in the IL-12 production. N-Acetyl-lactosamine, Gal-GlcNAc (LacNAc), also did not change IL-12 production. These results indicated that a certain size, i.e. disaccharide and sulfate, are essential to suppress IL-12 production. L4 was then applied to MRL-lpr/lpr mice, a Th-1 type autoimmune disease model. The treatment of MRL-lpr/lpr mice with L4 1) decreased in serum IL-12, 2) induced apoptosis in T cells in lymph nodes thereby suppressing lymphoaccumulation, and 3) suppressed hypergammaglobulinemia and glomerulonephritis. We showed previously that IL-12 suppresses cell death of T cells, thereby enhancing the lymphoaccumulation in MRL-lpr/lpr mice. Moreover, it has been reported that IL-12 deficiency in MRL-lpr/lpr mice diminishes lymphoaccumulation and delays glomerulonephritis. The treatment with L4 suppressed phosphoprotein kinase C and phosphoinositide 3-kinase expression in macrophages, suggesting that L4 suppresses IL-12 production by inhibiting phosphoprotein kinase C and phosphoinositide 3-kinase pathways.

Multi-glycoside of Tripterygium wilfordii Hook f. ameliorates proteinuria and acute mesangial injury induced by anti-Thy1.1 monoclonal antibody

BACKGROUND/AIMS

Multi-glycoside from Tripterygium wilfordii Hook f. (GTW) is used for various immune and inflammatory diseases including renal diseases represented by mesangial proliferative glomerulonephritis (MsPGN) in China. However, there have been no fundamental studies on the operating mechanism of GTW on MsPGN. The aim of this study is to examine as the first step the effects of GTW on acute injurious process such as mesangial injury and proteinuria in an acute and reversible Thy.1.1 glomerulonephritis (Thy1.1GN) model and then to clarify the action mechanism of GTW at molecular level by examining its effects on various injurious factors in this model.

METHODS

Thy1.1 GN was induced in rats by a single intravenous injection with 500 microg of anti-Thy1.1 mAb 1-22-3. Daily oral administration of GTW and vehicle as a control was started from 3 days before injection of mAb to the day of sacrifice in each experiment. Fourteen rats were randomly divided into 2 groups, GTW-treated and vehicle-treated groups, and sacrificed on day 14 in experiment 1 or on day 7 in experiment 2 after induction of Thy1.1 GN. Proteinuria was determined on days 1, 3, 5, 7, 10 and 14 in experiment 1 or on 1, 3, 5 and 7 in experiment 2. From blood and kidneys taken at sacrifice, blood biochemical parameters, mesangial morphological changes, glomerular macrophage infiltration, and glomerular mRNA expression of cytokines were examined.

RESULTS

In experiment 1, proteinuria and mesangial matrix expansion were significantly attenuated by GTW treatment. In experiment 2, GTW treatment significantly ameliorated proteinuria, mesangial lesions and macrophage accumulation in glomerulus. In addition, it significantly reduced the glomerular expression of mRNA for PDGF, MCP-1 and IL-2.

CONCLUSION

GTW ameliorated not only proteinuria but also mesangial alterations in Thy1.1 GN most likely by reducing expression of injurious cytokines, indicating that GTW has suppressive effects on acute inflammatory changes in glomeruli.

Temporary, but essential requirement of CD8+ T cells early in the pathogenesis of diabetes in BB rats as revealed by thymectomy and CD8 depletion

Autoimmunity-prone BB rats demonstrate a T lymphocytopenia and abnormal T cell subset distribution. To test whether the life span of all T cells or only of certain subsets is reduced in BB rats, we thymectomised 8-week-old BB and PVG rats and subsequently assessed size and composition of the T cell population over a 6-week-period. In both strains, thymectomy (Tx) was followed by a decrease in peripheral T cell numbers, which was proportionally larger in BB rats. The decline of the Thy-1⁺ recent thymic migrant (RTM) T cell phenotype was similar in both strains. BB rats showed a rapid preferential loss of CD8⁺ and CD45RC⁺ T cells, whereas the relative loss of RT6⁺ T cells was proportional to that of all T cells and not significantly different from that in PVG rats. Tx at 8-week did not prevent diabetes. Tx of 4-week-old BB rats revealed essentially the same changes in peripheral T cell subset distribution as in 8-week-old animals. However, Tx at week 4 did prevent diabetes. Since this raised the possibility of a temporary requirement of CD8⁺ T cells for the development of diabetes, we performed CD8 depletions during different pre-diabetic intervals. We found that CD8 depletion from 4 to 8 and 4 to 14 weeks, but not from 8 to 14 weeks of age prevented diabetes. We conclude that the protective effect of early adult Tx is, at least in part, due to the rapid loss of CD8⁺ T cells, and that these cells are only required between 4 and 8 weeks of age for diabetes to develop in BB rats.

Ex vivo transfer of the decorin gene into rat glomerulus via a mesangial cell vector suppressed extracellular matrix accumulation in experimental glomerulonephritis

The activation of transforming growth factor-beta (TGF-beta) is known to be one of the major causes of glomerulosclerosis. Decorin (DCN) is a natural inhibitor of TGF. The purpose of this study was to assess the feasibility of transferring the DCN gene to antithymocyte serum (ATS) glomerulonephritis glomeruli via a mesangial cell vector to treat glomerulonephritis fibrosis. For this process, the recombinant eukaryotic expression plasmid pcDNA3.1A-DCN was constructed and transfected into mesangial cell. The DCN-positive cloned cells were transferred to rat antithymocyte serum glomeruli by a left renal artery injection. Using immunohistochemical staining, approximately 37-60% (48.6% +/- 11.34%; mean +/- SE, n = 8) of the glomeruli were BrdU-positive in the injected-side kidney. DCN proteins were observed in the cytoplast beginning 12 h after injection. TGF-beta1 expression in the injected side glomeruli decreased significantly at day 4 (P < 0.05), compared with that in the uninjected-side kidney. The expression leaves of fibronectin and collagen IV decreased significantly at days 1-2 (P < 0.01) and day 4 (fibronectin, P < 0.01; collagen IV, P < 0.05). These results suggest that the use of DCN can decrease antithymocyte serum glomerulonephritis extracellular matrix (ECM) ingredients and that such use offers a favorable experimental basis for gene therapy for kidney disease.

Nephrin expression is increased in anti-Thy1.1-induced glomerulonephritis in rats

Nephrin is an important constituent of the glomerular filtration barrier and alteration of its expression is associated with severe proteinuria. In this study we show that injection of an anti-Thy1.1 antibody in rats not only induces a mesangioproliferative glomerulonephritis associated with increased proteinuria, but also leads to a sustained increase of nephrin mRNA and protein expression in renal glomeruli over a time period of 29 days. In contrast, podocin and CD2AP, two proteins shown to interact with nephrin in the slit diaphragm, are acutely downregulated at days 3-7 and, thereafter, recovered again to normal levels after 29 days. Interestingly, immunofluorescence staining of kidney sections at day 10 of the disease shows a highly heterogeneous pattern, in that some podocytes show complete absence of nephrin, whereas others show highly accumulated staining for nephrin compared to control sections, which in total results in an increased level of nephrin per glomerulus. In summary, our data show that in the course of mesangioproliferative glomerulonephritis in rats, an upregulation of nephrin expression occurs with a concomitant transient downregulation of podocin and CD2AP which may account for a highly dysregulated filtration barrier and increased proteinuria.

The characterization of a specific Thy-1 molecular epitope expressed on rat mesangial cells

BACKGROUND

An Experimental model of proliferative glomerulonephritis induced by an antibody against Thy-1 antigen has been established. However, the pathophysiologic role and the critical epitope of Thy-1 molecule for induction of mesangial cell dysfunction remain unknown. We have reported that monoclonal antibody 1-22-3 recognizes specific epitope which could transduce highly effective activation in mesangial cells. Identification of functional domains on cell surfaces is indispensable for understanding the molecular mechanisms of mesangial cell function. This study was undertaken to determine the functional domain containing the specific epitope recognized by monoclonal antibody 1-22-3.

METHODS

A series of glutathione-S-transferase (GST)-truncated-Thy-1 proteins were generated using pGEX 4T-1 vector. COS cells were transiently transfected with plasmid vectors which could express the rat Thy-1 and mutant-Thy-1.

RESULTS

Western blot analysis using recombinant GST-truncated-Thy-1 revealed that 1-22-3 bound to epitope at amino acids 15-23 (LRLDCRHEN). Enzyme-linked immunosorbent assay (ELISA) revealed that synthetic LRLDCRHEN peptides could inhibit the binding of 1-22-3 to rat mesangial cells and GST-Thy-1 protein. Using peptides as antigens, ELISA showed that 1-22-3 bound to the LRLDCRHEN but not to the RVNLFSDRF, which was corresponding to at amino acids 59-67 of rat Thy-1. 1-22-3 could bind the COS cells which express rat Thy-1 proteins, but could not bind rat truncated-Thy-1 which lacks residues 15-23.

CONCLUSION

Critical epitope detected by 1-22-3 in this study may play an important role in mesangial function and injury.

Specific antibodies to mouse Sca-1- (Ly-6A/E) or Thy-1-positive haematopoietic progenitor cells induce formation of nitric oxide which inhibits subsequent colony formation

Mouse bone marrow cells were exposed to specific monoclonal antibodies, so that lineage positive (Lin+) cells could be removed with magnetic beads. The Lin- cells were cultured with Sca-1 or CD90 (Thy-1) monoclonal antibodies (MoAbs) in semi-solid medium for 7 d. We found that Sca-1 MoAb suppressed colony formation (20-30%), and the effect was largely abolished by N-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthase. Similar results were obtained with antibodies to CD90. The findings suggest that the unknown physiological ligands to Sca-1 and Thy-1 markers on haematopoietic progenitor cells can inhibit colony formation, with NO as a pivotal mediator. Primitive progenitors may be a primary target of this Sca-1 ligand, as the Sca-1+ cell population contains the major part of the multipotent haematopoietic stem cells.

Decreased collagen-degrading activity could be a marker of prolonged mesangial matrix expansion

BACKGROUND

Mesangial matrix expansion is caused by the overproduction and/or the impaired proteolytic degradation of the extracellular matrix. However, the relative contribution of these changes to the development of prolonged mesangial matrix expansion is still poorly understood. We aimed to elucidate the relative role of the matrix metalloproteinase (MMP)/tissue inhibitors of metalloproteinases (TIMPs) system in the development of prolonged mesangial matrix expansion.

METHODS

We prepared two rat models, showing reversible or prolonged mesangial matrix expansion, induced by a single injection or two consecutive injections of anti-Thy-1.1 monoclonal antibody 1-22-3, respectively. We analyzed the glomerular expression of type I and type IV collagens; MMP-2, -9, and -13; membrane type 1-MMP (MT1-MMP); TIMP-1; and urinary type I collagen-degrading activity in both models.

RESULTS

There were no differences in glomerular mRNA levels of type I and type IV collagens between the reversible and the prolonged models. MMP-9 mRNA expression and protein level was lower in the prolonged model than in the reversible one, whereas there were no differences in mRNA levels of MMP-2, -13, MT1-MMP, or TIMP-1 between the two models. Urinary type I collagen-degrading activity in the prolonged model was lower than that in the reversible one. Furthermore, there was a significant correlation between the mesangial matrix expansion and urinary type I collagen-degrading activity.

CONCLUSIONS

Impaired expression of MMP-9 may contribute to the development of prolonged mesangial matrix expansion. Analysis of urinary type I collagen-degrading activity may provide additional diagnostic information in mesangial proliferative glomerulonephritis. Mesangial matrix expansion is caused by the overproduction and/or the impaired proteolytic degradation of the extracellular matrix. However, the relative contribution of these changes to the development of prolonged mesangial matrix expansion is still poorly understood. We aimed to elucidate the relative role of the matrix metalloproteinase (MMP)/tissue inhibitors of metalloproteinases (TIMPs) system in the development of prolonged mesangial matrix expansion.

[Therapeutical effects of esculentoside A on rats with MsPGN induced by anti-Thy1.1 antibody]

OBJECTIVE

To observe the therapeutical effects of esculentoside A (EsA) on rats with mesangial proliferative glomerulonephritis (MsPGN) induced by anti-Thy1.1 antibody and make a comparison of the effects between EsA and dexamethasone (DXM).

METHODS

Wistar rats with MsPGN induced by anti-Thy1.1 serum (ATS) were randomly divided into 3 groups: EsA group, DXM group, and model group. Moreover, a normal group was used for comparison. The BUN, SCr, urinary protein and renal pathological changes were examined after 7 d treatment with EsA and DXM.

RESULTS

The urinary protein, cell count and mesangium area of glomerulus were significantly higher in all modeled groups than in normal group (P<0.001-0.05), and they were significantly lower in the treated groups than in untreated group (P<0.001-0.01).

CONCLUSION

The results suggest that EsA is effective for reducing the urinary protein excretion and inhibiting the proliferation process of glomerular mesangium and matrix in rats with MsPGN.

Involvement of filamentous actin in setting the threshold for degranulation in mast cells

Previous studies using cytochalasins and latrunculin B, inhibitors of actin polymerization, showed that filamentous (F)-actin had a negative regulatory role in Fc epsilon receptor I (Fc epsilon RI) signaling. How F-actin is involved in regulating the activation of mast cells is unknown. In this study we investigated the role of F-actin in mast cell activation induced by aggregation of the glycosylphosphatidylinositol (GPI)-anchored proteins Thy-1 and TEC-21, and compared it to activation via Fc epsilon RI. Pretreatment of rat basophilic leukemia cells with latrunculin B inhibited the Thy-1-induced actin polymerization and elevated the Thy-1-mediated secretory and calcium responses. Inhibition of actin polymerization followed by Thy-1 aggregation resulted in an increased tyrosine phosphorylation of Syk, phospholipase C gamma (PLC gamma), Gab2 and linker for activation of T cells (LAT) adapters, and some other signaling molecules. Enzymatic activities of phosphatidylinositol 3-kinase, PLC gamma, and phosphatase SHP-2 were also up-regulated, but tyrosine phosphorylation of ezrin was inhibited. Similar changes were observed in Fc epsilon RI-activated cells. Significant changes in intracellular distribution, tyrosine phosphorylation, and/or enzymatic activities of signaling molecules occurred in latrunculin-pretreated cells before cell triggering. The combined data suggest that actin polymerization is critical for setting the thresholds for mast cell signaling via aggregation of both Fc epsilon RI and GPI-anchored proteins.

Preparation of Genetically Homogeneous Antigen-Specific Thymidine Kinase Positive T-Lymphocyte Clones for the Control of Alloreactivity Post-Bone Marrow Transplantation

We have previously proposed the use of HLA-specific T-cell clones transduced with a suicide gene to produce an allogeneic effect that can be controlled after allogeneic bone marrow transplantation. Procedures described so far to obtain specific T-cells transduced with a suicide gene have led to the recovery of heterogeneous polyclonal T-cells with a limited level of purity. We have therefore developed an approach to select specific T-cell clones in which the suicide transgene is inserted at a unique site of the genome, and used it to produce CD(+)-cytotoxic HLA-DP-specific T-cell clones. Immunization was performed by a one-way mixed lymphocyte culture and responder T lymphocytes were transduced at day 16, 6 days after the second stimulation. Transductions were carried out using gibbon ape leukemia virus (GALV)-pseudotyped retroviral particles harboring a bicistronic Thy-1/TK vector produced by TEFLY GA16-pKM4 clone 34 packaging cells. Three to 5 days later, CD90 immunomagnetic selection and cloning were performed on the transduced T cells. Our results demonstrate that this procedure led to the recovery of T-cell clones, the majority of which had the expected specificity and a single site of transgene insertion. Such clonotransgenic T-cell populations represent suitable tools to drive a defined alloreaction that can be controlled after bone marrow transplantation.

Podocyte changes upon induction of albuminuria in Thy-1.1 transgenic mice

BACKGROUND

Thy-1.1 transgenic mice, characterized by ectopic expression of the Thy-1.1 protein on podocytes, spontaneously develop proteinuria and focal glomerulosclerosis (FGS). Injection of a monoclonal antibody (mAb) directed against the Thy-1.1 protein in young transgenic mice induces a massive albuminuria that is followed by an accelerated FGS within 3 weeks. This albuminuria is complement and leukocyte independent. The time course of proteinuria, the pathogenesis of the acute proteinuria and the dose dependency of FGS are unknown.

METHODS

Albuminuria was measured in Thy-1.1 transgenic mice after injection of different doses of anti-Thy-1.1 mAb and at different time points within the first 24 h after injection. Podocytic foot processes and slit pore diameter were quantitated by electron microscopy. Changes in expression of slit pore constituents (podocin, CD2AP, nephrin and ZO-1), cytoskeleton-associated proteins (actin, alpha-actinin, ezrin and synaptopodin), the GDH-podocyte adhesion molecules alpha(3)-integrin, and heparan sulfate were studied by immunofluorescence. FGS was scored by light microscopy at 3 weeks after induction of albuminuria.

RESULTS

Albuminuria in Thy-1.1 transgenic mice was observed within 10 min after anti-Thy-1.1 mAb injection. This rapid development of albuminuria was accompanied by a reduction in number of podocytic foot processes from 20.0 +/- 0.7/10 microm glomerular basement membrane (GBM) in saline-treated transgenic mice to 8.0 +/- 0.5 and 2.2 +/- 0.2 in anti-Thy-1.1-treated mice, at 10 min and 8 h after treatment, respectively. In addition, we observed a significant decrease in width of remaining slit pores, from 32.7 +/- 1.1 to 26.8 +/- 1.4 nm at 10 min after mAb injection. By immunofluorescence, we did not observe major changes in the expression pattern of any of the proteins studied. There was no correlation between the injected dose of the anti-Thy-1.1 mAb and the acute albuminuria. In contrast, the percentage of FGS at 3 weeks correlated with the dose, and a significant correlation between the percentage of FGS and the time-averaged albuminuria over the 3 week study period (P < 0.001) was found.

CONCLUSION

Injection of mAb directed against the Thy-1.1 protein, in young non-albuminuric Thy-1.1 transgenic mice, induced an acute albuminuria within 10 min, which was accompanied by foot process effacement. Notably, we observed a decrease in slit pore width although the expression of slit pore proteins was unchanged. Also, the acute albuminuria could not be related to alterations in cytoskeleton-associated proteins, the GBM adhesion molecule alpha(3)-integrin or heparan sulfate in the GBM. The dose-dependent development of FGS and the correlation between the percentage FGS and time-averaged albuminuria suggest that, in our model, FGS is a consequence of podocyte injury. However, the data leave open the possibility that albuminuria itself contributes to FGS development. The Thy-1.1 transgenic mouse model is an excellent model to study further the relationship between podocytic injury, albuminuria and the development of FGS.

Participation of the matrix metalloproteinase inhibitor in Thy-1 nephritis

What influence would be shown in Thy-1 glomerulonephritis when the synthetic matrix metalloproteinase (MMP) inhibitor SI-27 is administered? Five groups of 80 male Wistar rats were studied: healthy group; treated healthy group; nephritic group; pretreated nephritic group; and post-treated nephritic group. SI-27 treatment of nephritic animals was initiated either 2 days before or 2 days after anti-Thy-1.1 antibody injection. On days 7, 14, 26 and 42 after disease induction, we examined renal histology, extracellular matrix (ECM) constituent, and MMP activity. SI-27 treated Thy-1 groups resulted in significant reduction of glomerular cells including alpha-smooth muscle actin (alpha-SMA) positive mesangial cells and suppressed expression of type IV collagen at 7 days. Moreover, type I collagen was also decreased by SI-27 at 42 days. However, glomerular cell numbers did not show any significant changes at 14, 26 and 42 days. In gelatin zymography, the gelatinolytic band for MMP-9 was expressed in SI-27 treated Thy-1 nephritis groups, although it was not expressed in the nephritic group at day 7. However, the expression of MMP-9 was no longer seen at 14, 26 and 42 days. The bands for an active form of MMP-2 were expressed throughout the experimental period in the Thy-1 nephritic groups. These results suggest that MMP plays an important role in the development of Thy-1 nephritis, and even if the synthetic MMP inhibitor intercepts the initial increase of glomerular cells and matrices, it does not inhibit recovery to normal glomerular capillary structures in Thy-1 nephritis.

[Pathogenesis of rat mesangial proliferative glomerulonephritis induced by anti-Thy1 antibody]

OBJECTIVE

To probe into the pathogenesis of rat mesangial proliferative glomerulonephritis (MsPGN) induced by anti-Thy1 antibody.

METHODS

Anti-Thy1 serum was produced, and then intravenously injected into Wistar rats for establishing an experimental model of MsPGN. The control group received intravenous injection of normal saline. Urinary volume and urinary protein were examined every other day. The IL-1, IL-6 and TNF contents of serum were detected by radioimmunoassay. Pathologic morphology of renal section was observed with micrscope and BI2000 Image Analysis System. The rats of model group were killed on the 1st, 3rd, 5th and 7th days.

RESULTS

No significant difference was seen between the model group and control group in regard to the volume of urine and in-take water (P > 0.05). The levels of urinary protein, IL-1, IL-6 and TNF in model group were significantly higher than those in control group at all time points (P < 0.001-0.005). Glomerular mesangium cells and matrix in the model group were obviously proliferative, compared with those in control group.

CONCLUSION

It is suggested that cytokine plays an important role in the onset of MsPGN.

Spironolactone in Combination with Cilazapril Ameliorates Proteinuria and Renal Interstitial Fibrosis in Rats with Anti-Thy-1 Irreversible Nephritis

Blockade of the renin-angiotensin system has been established as a treatment for heart failure with hypertension and left ventricular hypertrophy, and for progressive kidney diseases. The present study was conducted to examine whether spironolactone, a mineralocorticoid receptor antagonist, alone or in combination with cilazapril, an angiotensin converting enzyme (ACE) inhibitor, ameliorates proteinuria and renal lesions in an immune-initiated progressive nephritis model. Wistar rats were uninephrectomized 7 days before injection of anti-Thy-1 monoclonal antibody 1-22-3 to induce progressive glomerulonephritis. The nephritic rats were untreated or treated with spironolactone (400 mg/kg body weight/day), cilazapril (1 mg/kg body weight/day), or both for 10 weeks. Proteinuria was increased in the untreated rats 1 week after nephritis induction and was maintained throughout the experiment. Compared with the untreated animals (212.9+/-49.2 mg/day), proteinuria was significantly reduced in the spironolactone-treated group (62.0+/-4.0 mg/day, p=0.0046) and the cilazapril-treated group (71.8+/-26.0 mg/day, p=0.0048) on day 70 after antibody injection. Further reduction of proteinuria (42.4+/-4.5 mg/day, p=0.0019 vs. the untreated group) and less renal cortex interstitial fibrotic change (fibrosis score: 142.0+/-18.4 vs. 80.3+/-18.5 in the untreated group, p=0.0123) were detected in the spironolactone plus cilazapril-treated group. Blood pressure did not differ among the three treatment groups. In conclusion, spironolactone ameliorates proteinuria to the same degree as cilazapril, and concomitant use of spironolactone and an ACE inhibitor further suppresses renal disease progression. These data suggest that concomitant treatment with spironolactone and an ACE inhibitor has beneficial effects on immune-initiated progressive kidney disease.

[The antagonistic effect on anti-thy-1 serum-induced nephritis of rats injected by decorin-transfected mesangial cells vector]

OBJECTIVES

To inject decorin-transfected mesangial cells (MsC) vector into the kidneys of rats with anti-thy-1 serum-induced nephritis via left renal artery and observe the survival condition of MsC vector and its influence on glomerular lesions in rats with anti-thy-1 serum induced nephritis.

METHODS

Rat mesangio-proliferative glomerulonephritis was established by tail intravenous injection with rabbit anti-thy-1 serum (ATS). Decorin-transfected MsC was injected into rat kidneys via left renal artery. Primary culture, immunostaining for BrdU and decorin of transfected MsC lines were performed to observe their survival. Immunohistochemistry with image analysis was performed to detect the expression of BrdU, alpha-SMA, decorin, TGF-beta1, FN and ColIV in diseased glomeruli.

RESULTS

Rat anti-thy-1 serum-induced nephritis identified by pathological examination was successfully established by injecting rabbit ATS, and decorin transfected MsC vector was transfused to rat glomeruli via left renal artery. The active growth and positive expressions of BrdU and decorin proteins on the nuclei and cytoplasms of ex vivo MsC were observed respectively. TGF-beta1, FN, ColIV expressions in diseased glomeruli of rats with ATS nephritis were decreased significantly at day 4 (TGF-beta1, P < 0.05) and day 2 (FN and ColIV, P < 0.01) respectively, compared to uninjected kidneys.

CONCLUSIONS

MsC vector is successfully transferred to the glomeruli of experimental rats via left renal artery injection with no affect on cell survival. Decorin protein is expressed on the transfected MsC and shows antagonistic effect on the glomerular lesions of ATS rats. It suggests that the use of ex vivo MsC vector system can provide useful experimental basis for gene therapy of kidney disease in animal model.

The cytolytic activity of natural killer cells is not involved in the restriction of Mycobacterium avium growth

Severe combined immunodeficiency (SCID) mice were used to analyze the role of NK cells in resistance to Mycobacterium avium. The neutralization of IFN-gamma in these animals led to an exacerbation of the infection associated with a reduction in macrophage activation, suggesting a role for NK cells in innate immunity to mycobacteria. In contrast, administration of anti-asialo-GM(1) polyclonal serum or mAb specific for Thy1.2 did not affect mycobacterial growth or macrophage activation despite causing the almost complete abrogation of the natural cytolysis of a tumor cell target. Treatment with anti-asialo-GM(1)-specific serum depleted only two-thirds of the Thy1.2+ spleen cells, and anti-Thy1.2 treatment allowed for the persistence of a small number of cells still exhibiting an NK cell marker recognized by mAb DX5 and able to express IFN-gamma as analyzed by flow cytometry. In vivo treatment of B6.SCID mice with anti-NK1.1 mAb again failed to affect resistance to infection and allowed for the persistence of 2-8% of IFN-gamma-producing cells, many of them still expressing the DX5 marker. In vitro depletion studies showed that removal of IFN-gamma-expressing cells required the combined action of anti-Thy1.2, anti-Ly49C and DX5 antibodies in the presence of complement. Our data show that resistance to M. avium mediated by NK cells is independent of their cytolytic activity, and that there is a marked phenotypic and functional heterogeneity of the NK cell lineage in vivo during infection.

Bone-marrow-derived cells contribute to glomerular endothelial repair in experimental glomerulonephritis

Glomerular endothelial injury plays an important role in the pathogenesis of renal diseases and is centrally involved in renal disease progression. Glomerular endothelial repair may help maintain renal function. We examined whether bone-marrow (BM)-derived cells contribute to glomerular repair. A rat allogenic BM transplant model was used to allow tracing of BM-derived cells using a donor major histocompatibility complex class-I specific mAb. In glomeruli of chimeric rats we identified a small number of donor-BM-derived endothelial and mesangial cells, which increased in a time-dependent manner. Induction of anti-Thy-1.1-glomerulonephritis (transient mesangial and secondary glomerular endothelial injury) caused a significant, more than fourfold increase in the number of BM-derived glomerular endothelial cells at day 7 after anti-Thy-1.1 injection compared to chimeric rats without glomerular injury. The level of BM-derived endothelial cells remained high at day 28. We also observed a more than sevenfold increase in the number of BM-derived mesangial cells at day 28. BM-derived endothelial and mesangial cells were fully integrated in the glomerular structure. Our data show that BM-derived cells participate in glomerular endothelial and mesangial cell turnover and contribute to microvascular repair. These findings provide novel insights into the pathogenesis of renal disease and suggest a potential role for stem cell therapy.

Thy-1 signaling in the context of costimulation provided by dendritic cells provides signal 1 for T cell proliferation and cytotoxic effector molecule expression, but fails to trigger delivery of the lethal hit

Cross-linking of the GPI-anchored protein Thy-1 results in T cell proliferation and IL-2 synthesis. However, the exact function of Thy-1 in the process of T cell activation remains unknown, as does the effect of costimulation on Thy-1-driven T cell responses. In this study, we have investigated the ability of Thy-1 to substitute for traditional signal 1 in the context of costimulation provided by dendritic cells. Dendritic cells dramatically enhanced T cell proliferation and IL-2 synthesis in response to Thy-1 triggering by anti-Thy-1 mAb. This effect was not dependent on dendritic cell Fcgamma receptors, but was a result of B7-mediated costimulation (signal 2). T cells were also activated when microbeads coated with a combination of anti-Thy-1 and anti-CD28 mAbs were used to supply signals 1 and 2, respectively. Thy-1-stimulated T cells adhere to target cells and express perforin, granzyme B, and Fas ligand, but fail to kill target cells due to an inability to reorganize their secretion machinery. Moreover, in contrast to TCR signaling, Thy-1 triggering failed to induce cytotoxicity in redirected lysis assays. We conclude that Thy-1 triggering can partially substitute for signal 1, which, in combination with a strong signal 2, leads to robust T cell proliferation, IL-2 synthesis, and cytotoxic effector molecule expression, but does not induce cytolytic function. The block at the level of cytotoxic effector function that results when T cells are activated in the absence of a classical, Ag-specific signal 1 may constitute a mechanism to ensure the specificity of CTL responses and prevent potentially harmful promiscuous cytotoxicity.

Pathways to recovery and loss of nephrons in anti-Thy-1 nephritis

The present histopathologic study of anti-Thy-1.1 models of mesangioproliferative glomerulonephritis in rats provides a structural analysis of damage development and of pathways to recovery and to nephron loss. As long as the disease remains confined to the endocapillary compartment, the damage may be resolved or recover with a mesangial scar. Irreversible lesions with loss of nephrons emerge from extracapillary processes with crucial involvement of podocytes, leading to tuft adhesions to Bowman's capsule (BC) and subsequent crescent formation. Two mechanisms appeared to be responsible: (1) Epithelial cell proliferation at BC and the urinary orifice and (2) misdirected filtration and filtrate spreading on the outer aspect of the nephron. Both may lead to obstruction of the tubule, disconnection from the glomerulus, and subsequent degeneration of the entire nephron. No evidence emerged to suggest that the kind of focal interstitial proliferation associated with the degeneration of injured nephrons was harmful to a neighboring healthy nephron.

Comparison of potassium currents in human decidua before and after the onset of labor

The human decidua plays a prominent role in the signaling between maternal and fetal tissues. It also secretes a plethora of molecules that modulate uterine function. Ion-channel activity underpins many cellular functions; however, the channels in human decidua have not been characterized in any detail. We have used the whole-cell recording mode of the patch-clamp technique to carry out current-clamp and voltage-clamp recordings of membrane properties and whole-cell potassium (K+) currents of freshly isolated decidual stromal cells. Decidual tissue was obtained from women after spontaneous vaginal delivery (SVD) or elective cesarean section (CS). Cells from both groups generated action potentials, the overshoots and durations of which were dependent on extracellular calcium levels, inhibited by cobalt and enhanced by barium. Potassium current (IK) density was higher in the CS than in the SVD group. Outwardly directed currents were heterogeneous with respect to their activation/inactivation profiles and exhibited outward rectification. The main difference between the SVD and CS group was the presence of a sustained current component in CS cells that is tetraethylammonium chloride-resistant and appears to be unaffected by E-4031. No evidence for the activation of any calcium-activated K+ currents was obtained. We propose that human parturition is associated with subtle changes in K+ channel remodeling, reflecting the transition from uterine quiescence to activation and stimulation. An understanding of the signal transduction events underlying these process may eventually lead to novel approaches to prevent preterm labor via decidual rather than myometrial intervention.

Laser capture microdissection and real-time PCR for analysis of glomerular endothelin-1 gene expression in mesangiolysis of rat anti-Thy 1.1 and murine Habu Snake Venom glomerulonephritis

Molecular analysis of pathologic changes in glomeruli requires methods allowing rapid and exact detection of alterations in gene expression. Here, we analyzed endothelin-1 (ET-1) mRNA expression in mesangiolytic glomeruli during the course of a rat and murine model of mesangioproliferative glomerulonephritis (GN). A novel method combining laser capture microdissection (LCM), which permits the precise removal of selected mesangiolytic glomeruli, with a highly sensitive real-time RT-PCR technique was used. Anti-Thy 1.1. GN was introduced in male Sprague-Dawley rats (1.0 mg/kg body weight of OX-7 IV) and Habu Snake Venom GN was introduced in C57BL6 mice (habu snake venom toxin 6 mg/kg body weight IV). The degree of mesangiolysis during both GNs was analyzed using a semiquantitative scoring system. Mesangiolytic glomeruli were microdissected at different days of the diseases (day 2, 6, and 12 in anti-Thy 1.1 GN and days 1, 3, 7, and 14 in Habu Snake Venom GN) and from normal control animals. After RNA extraction and cDNA synthesis, ET-1 gene expression was measured by real-time RT-PCR. In parallel, in anti-Thy 1.1. GN ET-1 mRNA expression was analyzed using semiquantitative nonradioactive in situ hybridization; ET-1 protein expression was investigated by immunohistochemistry. Mesangiolysis peaked at day 6 in anti-Thy1.1 GN and at day 1 in Habu Snake Venom GN. Mesangiolytic glomeruli were easily microdissected on cryostat sections in both models; quantification of mRNA with RT-PCR was reliable and reproducible. Glomerular ET-1 mRNA expression increased during the course of anti-Thy 1.1 GN and Habu Snake Venom GN peaked when mesangiolysis was most pronounced. This was seen by RT-PCR after glomerular LCM and by in situ hybridization; in parallel, glomerular ET-1 protein expression was increased. Combination of LCM and RT-PCR is a reliable method for quantification of localized gene expression in isolated renal structures. The above data argue for an important role of ET-1 in pathogenesis and/or repair of mesangiolysis in experimental mesangioproliferative GN.

Spermatogonial stem cells share some, but not all, phenotypic and functional characteristics with other stem cells

Spermatogonial stem cells (SSCs) are responsible for maintaining spermatogenesis throughout life in the male by continuous production of daughter cells that differentiate into spermatozoa. However, no unique phenotypic markers to identify SSCs have been described. In this study, the SSC surface phenotype was characterized by using flow cytometric cell sorting in conjunction with a transplantation functional assay for SSCs. Highly enriched stem cell activity was found in the MHC class I (MHC-I)-Thy-1+c-kit- cell fraction of the mouse cryptorchid testis. There was little or no stem cell activity in any other fraction. The antigenic phenotype of the MHC-I-Thy-1+c-kit- SSCs was alpha6-integrin+CD24+alphavintegrin-Sca-1-CD34-. Subsequently, testis side population (SP) cells, which are defined by a Hoechst dye efflux assay, were identified. Their surface phenotype was found to be MHC-I+Thy-1-Sca-1+, and the transplantation assay demonstrated that the testis SP and SSCs are distinct populations. In several other tissues, the SP has been shown to contain stem cells, but we found that this characteristic does not define SSCs. The identification of a surface phenotype that allows production of a highly enriched SSC population will facilitate functional and genomic studies and enable further comparison with other stem cells.

Effects of leukocytosis and macrophage activation on anti-Thy 1.1 glomerulonephritis in the rat

OBJECTIVE

In anti-Thy 1.1 proliferative glomerulonephritis (GN), glomerular infiltration of polymorphonuclear leukocytes (PMNs) reaches a peak level after 1 h and that of macrophages does so 24 h after induction. However, the roles of PMNs and macrophages in the pathogenesis of anti-Thy 1.1 GN remain unclear. We examined the effects on this model of leukocytosis induced by granulocyte colony-stimulating factor (G-CSF) and of macrophages stimulated by macrophage colony-stimulating factor (M-CSF).

MATERIAL AND METHODS

Anti-Thy 1.1 GN was induced in male Wistar rats by intravenous injection of OX-7, a monoclonal antibody to the Thy 1 antigen. G-CSF (10 microg/kg/day), M-CSF (20 microg/kg/day) or vehicle was administered intraperitoneally for 7 days starting 24 h before the injection of OX-7. Histological examination of renal biopsy specimens was performed on Days 1, 5 and 14 after induction.

RESULTS

Circulating and glomerular-infiltrating PMNs (RP-3-positive cells) were increased at Day 5 in G-CSF-treated rats compared with controls receiving vehicle, and glomerular mesangiolysis continued at Day 5. The number of proliferating cells positive for proliferating cell nuclear antigen at Day 5 and matrix scores at Day 14 were smaller in G-CSF-treated rats than in control rats. The mesangiolysis score was significantly higher in the G-CSF group than in the control group at Days 5 and 14, but not at Day 1. ED-1-positive cells were increased in number at Day 5 and matrix accumulation decreased at Day 14 in M-CSF-treated rats compared with controls. Serum creatinine level at Day 14 was lower in the M-CSF group, but not in the G-CSF group, compared with the control group.

CONCLUSIONS

Activated macrophages may inhibit excess matrix accumulation and ameliorate the recovery of renal function, whereas leukocytosis inhibits the repair of mesangial cell injury in this model.

Angiogenic protein Cyr61 is expressed by podocytes in anti-Thy-1 glomerulonephritis

Dynamic recovery of glomerular structure occurs after severe glomerular damage in anti-Thy-1 glomerulonephritis (Thy-1 GN), but its mechanism remains to be investigated. To identify candidate genes possibly involved in glomerular reconstruction, screening was performed for genes that are specifically expressed by podocytes and are upregulated in glomeruli of Thy-1 GN. Among them, cysteine-rich protein 61 (Cyr61 or CCN1), a soluble angiogenic protein belonging to the CCN family, was identified. By Northern blot analysis, Cyr61 mRNA was markedly upregulated in glomeruli of Thy-1 GN from day 3 through day 7, when mesangial cell migration was most prominent. By in situ hybridization and immunohistochemistry, Cyr61 mRNA and protein were expressed by proximal straight tubules and afferent and efferent arterioles in normal rat kidneys and were intensely upregulated at podocytes in Thy-1 GN. Platelet-derived growth factor-BB (PDGF-BB) and transforming growth factor-beta1 (TGF-beta1), of which the gene expression in the glomeruli of Thy-1 GN was upregulated in similar time course as Cyr61, induced Cyr61 mRNA expression in cultured podocytes. Furthermore, supernatant of Cyr61-overexpressing cells inhibited PDGF-induced mesangial cell migration. In conclusion, it is shown that Cyr61 is strongly upregulated at podocytes in Thy-1 GN possibly by PDGF and TGF-beta. Cyr61 may be involved in glomerular remodeling as a factor secreted from podocytes to inhibit mesangial cell migration.

Moderate alcohol intake has no impact on acute and chronic progressive anti-thy1 glomerulonephritis

Moderate alcohol consumption has shown beneficial effects in experimental and human cardiovascular disease. With the use of rat models of acute and chronic progressive anti-thy1 glomerulonephritis (GN), we tested the hypothesis that moderate alcohol intake is protective in renal fibrotic disease. In acute anti-thy1 GN, untreated nephritic rats showed marked mesangial cell lysis and induced nitric oxide production at day 1 and high proteinuria, glomerular matrix accumulation, and transforming growth factor (TGF)-beta(1), fibronectin, and plasminogen activator inhibitor (PAI)-1 expression at day 7 after disease induction, respectively. In animals 15 wk after induction of chronic progressive anti-thy1 GN, disease was characterized by significantly reduced renal function, persisting albuminuria as well as increased glomerular and tubulointerstitial matrix expansion, TGF-beta(1), fibronectin, and PAI-1 protein expression. In both anti-thy1 GN models, an ethanol intake of approximately 2 ml per day and animal was achieved, however, disease severity was not significantly altered by moderate alcohol consumption in any of the protocols. In conclusion, moderate alcohol intake does not influence renal matrix protein production and accumulation in acute and chronic progressive anti-thy1 glomerulofibrosis. The study suggests that, in contrast to cardiovascular disorders, moderate alcohol consumption might not provide specific protection in renal fibrotic disease.

Combination of radiation and vaccination with autologous tumor cells expressing IL-2, IFN-gamma and GM-CSF for treatment of murine renal carcinoma

BACKGROUND

We previously showed, in a murine renal cell carcinoma (RCC) model, that lung irradiation plus vaccination with autologous tumor cells producing recombinant interleukin-2 (IL-2), interferon-gamma (IFN-gamma) and granulocyte-macrophage colony-stimulating factor (GM-CSF) (Renca/cytokine) reduces the number of lung metastases by over 90%. The present study investigates the host cellular mechanisms mediating this anti-tumor activity.

MATERIALS AND METHODS

Lung metastases were produced by injection of BALB/c mice i.v. with wild-type Renca cells (wt Renca) on day 0. The mice were then injected s.c. with irradiated Renca/cytokine vaccine cells on days 4, 8 and 11. Lungs were irradiated (300 rads) on day 7. Natural killer (NK) cells or T cells were depleted by injection i.p. with an antibody against anti-asialo GM1 or Thy1.2, respectively. Polyinosinic-polycytidylic acid (poly I:C) was injected i.p. to activate NK cells. Lung tumors were enumerated on day 21.

RESULTS

The anti-asialo GM I antibody totally abolished the antitumor activity elicited by the combined vaccination/radiation treatment regime. In contrast, anti-Thyl.2 antibody did not significantly decrease treatment efficacy. Poly I:C elicited over 95% reduction in lung metastases and strong NK activation as assayed against YAC-1 cells in vitro.

CONCLUSIONS

It appears that NK cells and granulocytes are predominantly involved in the antitumor action elicited by the cytokine-secreting autologous tumor cell vaccine in this metastatic RCC model.

Morphological insights into the origin of glomerular endothelial and mesangial cells and their precursors

Glomerular endothelial and mesangial cells may originate from the metanephric mesenchyme. We used the MAb Thy1.1, a mesangial cell marker in the adult rat kidney, and rat endothelial cell markers MAb RECA-1, MAb PECAM-1 (CD31), and MAb Flk-1 as potential markers to characterize the spatial and temporal distribution of mesangial and endothelial cell precursors during nephrogenesis in the rat. At early stages of glomerulogenesis, RECA-1- and Thy1.1-positive cells were detected in the metanephric blastema at 14 days post conception (dpc) embryos and 15 dpc, respectively, with Thy1.1 expression in cells surrounding the ureteric bud. At 17 and 18 dpc, both RECA-1- and Thy1.1-positive cells were found in the cleft of the S-shaped bodies and in the capillary loops of maturing glomeruli. Double staining for BrdU, a marker of proliferation, and for RECA-1 or BrdU and Thy1.1 also localize in the cleft of S-shaped bodies and in glomerular capillary loops at later stages of development. PDGFRbeta co-localizes in cells expressing endothelial or mesangial markers. The data suggest that endothelial and mesangial cell precursors share common markers during the course of glomerulogenesis and that full differentiation of these cells occurs at late stages of glomerular maturation. Thy1.1- and RECA-1-positive cells may be derived from the metanephric blastemal cells at early stages of kidney development. A subpopulation of these Thy1.1- or RECA-1-positive cells may be precursors that can migrate into the cleft of comma and S-shaped bodies and proliferate in situ to form glomerular capillary tufts.

Positive selection of anti-thy-1 autoreactive B-1 cells and natural serum autoantibody production independent from bone marrow B cell development

A natural serum autoantibody specific for the Thy-1 glycoprotein (anti-Thy-1 autoantibody [ATA]) is produced by B-1 cells that are positively selected by self-antigen. Here, using ATA micro kappa transgenic mice we show that cells with this B cell receptor are negatively selected during bone marrow (BM) development. In a Thy-1 null environment, BM ATA B cells progress to a normal follicular stage in spleen. However, in a self-antigen-positive environment, development is arrested at an immature stage in the spleen, concomitant with induction of CD5. Such cells are tolerant and short-lived, different from B-1. Nonetheless, ATA-positive selection was evident by self-antigen-dependent high serum ATA production, comprising approximately 90% of serum immunoglobulin M in ATA micro kappa mice. Splenectomy did not eliminate ATA production and transfer of tolerant splenic B cells did not induce it. These findings demonstrate that B-1 positive selection, resulting in the production of natural serum ATA, arises independently from the major pathway of BM B cell development and selection.

P2 receptor antagonist PPADS inhibits mesangial cell proliferation in experimental mesangial proliferative glomerulonephritis

BACKGROUND

Although extracellular nucleotides have been shown to confer mitogenic effects in cultured rat mesangial cells through activation of purinergic P2 receptors (P2Y receptors), thus far the in vivo relevance of these findings is unclear. Virtually all cells and in particular the dense granules of platelets contain high levels of nucleotides that are released upon cell injury or platelet aggregation. In experimental mesangial proliferative glomerulonephritis in the rat (anti-Thy1 model), mesangiolysis and glomerular platelet aggregation are followed by a pronounced mesangial cell (MC) proliferative response leading to glomerular hypercellularity. Therefore, we examined the role of extracellular nucleotides and their corresponding receptors in nucleotide-stimulated cultured mesangial cells and in inflammatory glomerular disease using the P2 receptor antagonist PPADS.

METHODS

The effects of PPADS on nucleotide- or fetal calf serum (FCS)-stimulated proliferation of cultured MC were measured by cell counting and [3H]thymidine incorporation assay. After induction of the anti-Thy1 model, rats received injections of the P2-receptor antagonist PPADS at different doses (15, 30, 60 mg/kg BW). Proliferating mesangial and non-mesangial cells, mesangial cell activation, matrix accumulation, influx of inflammatory cells, mesangiolysis, microaneurysm formation, and renal functional parameters were assessed during anti-Thy1 disease. P2Y-mRNA and protein expression was assessed using RT-PCR and real time PCR, Northern blot analysis, in situ hybridization, and immunohistochemistry.

RESULTS

In cultured mesangial cells, PPADS inhibited nucleotide, but not FCS-stimulated proliferation in a dose-dependent manner. In the anti-Thy1 model, PPADS specifically and dose-dependently reduced early (day 3), but not late (day 8), glomerular mesangial cell proliferation as well as phenotypic activation of the mesangium and slightly matrix expansion. While no consistent effect was obtained in regard to the degree of mesangiolysis, influx of inflammatory cells, proteinuria or blood pressure, PPADS treatment increased serum creatinine and urea in anti-Thy1 rats. P2Y receptor expression (P2Y2 and P2Y6) was detected in cultured MC and isolated glomeruli, and demonstrated a transient marked increase during anti-Thy1 disease.

CONCLUSION

These data strongly suggest an in vivo role for extracellular nucleotides in mediating early MC proliferation after MC injury.

Effects of anti-alpha1 integrin subunit antibody on anti-Thy-1 glomerulonephritis

alpha1beta1 integrin is a potential collagen-binding extracellular matrix receptor that mediates collagen-dependent cell adhesion, proliferation, migration, and collagen matrix assembly and thereby may participate in the wound healing and pathologic scarring observed in some damaged organs. To clarify the role of alpha1beta1 integrin predominantly expressed on the mesangial cell (MC) surface in nephritic glomeruli, we investigated the involvement of MC-alpha1beta1 integrin in rat anti-Thy-1 glomerulonephritis (GN) by administering function-blocking monoclonal mouse anti-rat alpha1 integrin subunit antibody (anti-alpha1 Ab). Assay of collagen types I and IV mixed gel contraction, an in vitro model of pathologic collagen matrix remodeling, with function-blocking anti-alpha1 Ab and anti-beta1 Ab, revealed that collagen I and IV matrix reorganization is mediated by MC-alpha1beta1 integrin. In addition, conditioned medium from isolated Day 3 anti-Thy-1 nephritic glomeruli showed increased activity of MC-alpha1beta1 integrin-induced mixed collagen gel contraction as compared with that from isolated normal rat glomeruli. Treatment of Day 3 conditioned medium with anti-platelet-derived growth factor-BB antibody significantly inhibited conditioned media-induced gel contraction, whereas treatment with anti-transforming growth factor-beta antibody did not have a significant effect. Rats that received anti-alpha1 Ab from the left renal artery 3 days after anti-Thy-1 GN induction showed significant decreases of glomerular hypercellularity and mesangial matrix accumulation, including collagen I and IV in the left kidney, compared with those rats in which the left kidney received control mouse IgG1. These results suggest that MC-alpha1beta1 integrin is an important extracellular matrix receptor mediating mesangial remodeling characterized by MC proliferation and mesangial matrix reorganization in anti-Thy-1 GN. Platelet-derived growth factor-BB may be involved in early collagen matrix reorganization leading to pathologic mesangial remodeling in this GN model.

Supplementation of heterologous complement induces anti-Thy-1.1 nephritis in the Mongolian gerbil (Meriones unguiculatus)

Anti-Thy-1.1 nephritis in the rat is a popular experimental model for mesangial proliferative glomerulonephritis (GN). This model is characterized by direct binding of anti-Thy-1.1 antibody with Thy-1.1 antigen expressed on mesangial cells (MCs) of glomeruli in the rat. A single injection of anti-rat thymocyte serum (ARTS) results in GN with proteinuria and extensive mesangiolysis. Development of mesangiolysis and proteinuria are complement-dependent. We previously demonstrated Thy-1.1 antigen, similar to the rat, in thymocytes, brain cells and MCs of the kidney in the Mongolian gerbil (MG). In this study, we attempted to develop a MG nephritis model, but an injection of ARTS did not induce GN. An additional injection of guinea pig serum as a complement after ARTS injection resulted in anti-Thy-1.1 nephritis in MG. Degeneration of MCs and neutrophil infiltration were observed 1 hr after GP serum injection. Mesangiolysis and fibrin exudation occurred 12 hr after the injection and MC proliferation was apparent 7 days after the injection. In the complement-dependent hemolytic test, MG serum could not hemolyze sheep erythrocytes. These results suggested low activity, or depletion of some factors, in complements of MG serum.

Glucocorticoid diminishes vascular endothelial growth factor and exacerbates proteinuria in rats with mesangial proliferative glomerulonephritis

Glucocorticoids are widely prescribed for renal diseases. It is believed that glucocorticoids attenuate immune-mediated renal diseases by suppressing the cell-mediated immune system. However, there is evidence that glucocorticoids influence the expression of such growth factors as vascular endothelial growth factor (VEGF), transforming growth factor-beta1 (TGF-beta1), and connective tissue growth factor (CTGF), which are known to influence the development or progression of renal diseases. Therefore, we undertook this study to determine whether glucocorticoids regulate proteinuria or extracellular matrix (ECM) production by altering these growth factors. Mesangial proliferative glomerulonephritis was induced in rats by intravenous injection of monoclonal antibody (OX-7), and dexamethasone (20 mg/kg) was administered intraperitoneally from the third to seventh disease day. Glomerular expression of VEGF, TGF-beta1, and CTGF, the amount of urinary protein, and glomerular ECM were measured on the seventh disease day. The nephritic group showed proteinuria and greater VEGF, TGF-beta1, and ECM production. Dexamethasone aggravated proteinuria (protein, 0.4 +/- 0.1 mg/mg creatinine in the NC group, 6.3 +/- 2.0 mg/mg creatinine in the DC group, and 21.1 +/- 1.9 mg/mg creatinine in the D-Dex group; P < 0.05) and diminished VEGF release (22 +/- 3 pg/mg total protein in the NC group, 292 +/- 26 pg/mg total protein in the DC group, and 198 +/- 23 pg/mg total protein in the D-Dex group; P < 0.05). Expression of TGF-beta1, CTGF, and ECM was not altered significantly by dexamethasone treatment. We found that glucocorticoid diminishes VEGF release and at the same time exacerbates proteinuria in rats with this type of glomerulonephritis.

Goto-Kakizaki rat is protected from proteinuria after induction of anti-Thy1 nephritis

Hyperglycemia, although necessary, alone is insufficient for the development of progressive diabetic nephropathy. Two factors implicated in its pathogenesis are mesangial cell activation and/or proliferation and monocyte/macrophage influx. We have shown that prolonged hyperglycemia in the Goto-Kakizaki (GK) rat is associated with renal structural changes similar to those in patients with diabetes before the onset of progressive nephropathy. The aim of the current study is to examine the role of mesangial cell injury and macrophage influx on renal structure and function. After induction of nephritis in either hyperglycemic GK rats or normoglycemic Wistar rats by the administration of Ox-7 antibody, the degree of mesangiolysis and subsequent mesangial proliferation was no different between GK and Wistar rats. Similarly, macrophage influx and mesangial cell activation (assessed by alpha-smooth actin expression) was no different between the two groups. Wistar rats developed marked albuminuria; conversely, no significant proteinuria or albuminuria was seen in GK rats. Analysis of glomerular proteoglycans (PGs) showed an increase in (35)S incorporation into heparan sulfate PGs of GK compared with Wistar rats, with no alteration in glycosaminoglycan chain size or charge density. These changes were kidney specific and not seen in spleen, lung, or heart tissue. Western blot analysis showed increased agrin core protein expression in whole-kidney homogenates of untreated GK rats. Induction of Thy1.1 nephritis was associated with reduced expression of agrin in both GK and Wistar rats. However, agrin expression was greater in GK rats at all times. In summary, acute mesangial cell injury associated with a macrophage influx did not initiate progressive diabetic nephropathy in GK rats. Despite a similar magnitude of glomerular/mesangial injury, GK rats, in contrast to normoglycemic Wistar rats, did not develop proteinuria after the administration of anti-Thy1 antibody. We postulate that altered expression of agrin in this model accounts for the lack of proteinuria and thus may protect against progressive nephropathy.

Effects of antioxidants on kidney disease

Kidney mesangial cells (MCs) and vascular smooth muscle cells (VSMCs) are closely related in terms of origin, microscopic anatomy, histochemistry, and contractility. This relationship suggests a similarity between kidney glomerular sclerosis and atherosclerosis. Vitamin E appears beneficial in the prevention and treatment of coronary disease and also inhibits the proliferation of VSMCs in vitro. We used vitamin E and probucol to treat glomerular sclerosis and MC-proliferative glomerulonephritis (GN) in two animal models of glomerular disease. Using rats, a remnant kidney model accelerated with hyperlipidemia was employed to reflect progressive glomerular sclerosis leading to chronic renal failure, and an anti-thymocyte serum treatment was used to model acute MC-proliferative GN. Supplemental dietary antioxidants suppress MC proliferation and glomerular sclerosis in models of glomerular disease in rats. These results suggest that treatment with antioxidants may be a promising intervention to prevent progression of kidney disease.

FK506 ameliorates proteinuria and glomerular lesions induced by anti-Thy 1.1 monoclonal antibody 1-22-3

BACKGROUND

We have previously reported that CD4 T lymphocytes and their cytokines contribute to development of Thy 1.1 glomerulonephritis (GN). FK506 is reported to suppress the production of Th1 cytokines. The aims of this study were to elucidate the role of Th1 cytokines on mesangial alteration and to examine whether FK506 is available for therapy of mesangial proliferative GN.

METHODS

The effects of daily treatments of FK506 from day -5 and from day +1 of Thy 1.1 GN induction on glomerular alterations were analyzed.

RESULTS

FK506 treatment with 1.0 and 0.3 mg/kg body weight (BW) daily from day 1 to day 4 significantly reduced the glomerular expression of mRNA for interferon-gamma (IFN-gamma; 1.0 mg/kg BW FK506, 32.4% to the placebo group, P < 0.01) and IL-2 (55.6%, P < 0.01) on day 5. FK506 treatment from day -5 of GN induction reduced proteinuria and glomerular alteration in a dose-dependent manner. Although no side effects were detected in rats with 0.3 mg/kg BW of FK506 treatment from day +1, the treatment also ameliorated proteinuria (day 14, 3.7 +/- 0.89 vs. 19.8 +/- 12.3 mg/100 g BW/day P < 0.05) and glomerular alterations [total cell number, 63.1 +/- 3.1 vs. 80.2 +/- 7.4, P < 0.01; matrix expansion, 0.90 +/- 0.30 vs. 1.34 +/- 0.27, P < 0.05; alpha-smooth muscle actin (alphaSMA) expression; 1.20 +/- 0.12 vs. 1.96 +/- 0.29, P < 0.01] on day 14.

CONCLUSION

Th1 cytokines may play an important role in the development of mesangial proliferative glomerulonephritis, and could be targets for therapy. FK506 might be available for clinical use.

Interleukin-10 inhibits experimental mesangial proliferative glomerulonephritis

Conflicting reports exist regarding the effects of interleukin-10 (IL-10) on mesangial cells. There have been reports of both proliferative and antiproliferative effects, and both proinflammatory and anti-inflammatory effects of IL-10 on mesangial cells. However, the potential for IL-10 to affect glomerulonephritis characterized by mesangial proliferation is not known. To test the hypothesis that IL-10 would limit experimental mesangial proliferative glomerulonephritis, IL-10 was administered to rats in which mesangial proliferative glomerulonephritis was induced by administration of anti-Thy 1 antibody. Compared to control treated rats, IL-10 treated rats showed less proliferation, with fewer cells in glomeruli. Glomerular cellular proliferation was reduced, assessed by the numbers of cells within glomeruli expressing either proliferating cell nuclear antigen (PCNA) or bromodeoxyuridine. Glomerular macrophage influx (but not the proportion of glomerular macrophages that were PCNA positive) was reduced by IL-10 administration. There was no significant reduction in glomerular alpha-smooth muscle actin staining. IL-10 treatment resulted in reduced renal IL-1beta mRNA expression and reduced glomerular ICAM-1 expression, but renal expression of MCP-1 and osteopontin mRNA was unaltered. This study demonstrates that in experimental mesangial proliferative glomerulonephritis IL-10 diminishes inflammatory cell recruitment and mesangial cell proliferation. The effects of IL-10 in inhibiting mesangial cell proliferation are likely to be due to a combination of direct effects of IL-10 on mesangial cells and effects mediated by macrophages.

The effects of platelet-derived growth factor antagonism in experimental glomerulonephritis are independent of the transforming growth factor-beta system

Platelet-derived growth factor B-chain (PDGF-B)- and transforming growth factor beta (TGF-beta)-mediated accumulation of extracellular matrix proteins contributes to many progressive renal diseases. In vivo, specific antagonism of either PDGF-B or TGF-beta in experimental mesangioproliferative glomerulonephritis resulted in an almost complete inhibition of matrix protein accumulation, which suggests an interaction between signaling pathways of these two growth factors. Because nothing is known on the nature of this possible interaction, PDGF-B was antagonized in the rat anti-Thy 1.1 model of glomerulonephritis by use of specific aptamers and its effects on the TGF-beta system were investigated. Antagonism of PDGF-B led to a significant reduction of glomerular matrix accumulation compared with scrambled aptamer-treated nephritic controls. PDGF-B antagonism had no effect on the overexpression of glomerular TGF-beta mRNA, TGF-beta protein, or the expression of TGF-beta receptor type I and II mRNA. By immunohistology, it was possible to detect overexpression of the cytoplasmic TGF-beta signaling molecules Smad2 (agonistic) and Smad7 (antagonistic) in glomeruli of nephritic control rats which peaked on day 7 after disease induction, i.e., the peak of mesangial cell proliferation in this model. However, immunohistology and Western blot analysis again revealed no difference in the glomerular expression of both Smad proteins between PDGF-B antagonized and nonantagonized nephritic animals. In addition, no difference in the glomerular expression of phosphorylated Smad2 (P-Smad2) was detected between the differently treated nephritic groups. These observations suggest that the effects of PDGF-B antagonism are independent of TGF-beta in mesangioproliferative glomerulonephritides.

Impairment of vascular regeneration precedes progressive glomerulosclerosis in anti-Thy 1 glomerulonephritis

BACKGROUND

It has been proposed that glomerular hemodynamic changes or glomerular growth response may promote the development of glomerulosclerosis, irrespective of its etiology. Further experimental models are needed to clarify the cellular and molecular mechanisms that lead to progressive glomerulosclerosis with an irreversible course. We designed a model of irreversible glomerulosclerosis, using anti-Thy-1.1 injection followed by uninephrectomy, and examined the role of glomerular endothelial cell responses in the process of progressive sclerotic changes.

METHOD

Rats were injected with anti-Thy-1.1 monoclonal antibody, 1-22-3, and 30 minutes later, unilateral nephrectomy (one-kidney group) or sham operation (two-kidney group) was performed. Rats were sacrificed for histological examination on days 3, 14, 56, and 84 after injection. The density of the glomerular capillary tuft was assessed by immunofluorescent staining for endothelial specific antigens. The mRNA expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), platelet-endothelial cell adhesion molecule-1 (PECAM-1), and vascular endothelial growth factor (VEGF) also was followed up by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Semiquantitative analysis revealed that the capillary density and mRNA expression of PECAM-1, VCAM-1 and VEGF were significantly lower in the one-kidney group compared to the two-kidney group on day 14. On day 84, progressive glomerulosclerotic lesions were found, followed by a decrease of the capillary density in the one-kidney group, while the glomerular architecture recovered to an almost normal state in the two-kidney group.

CONCLUSIONS

Progressive glomerulosclerosis can be induced in the rat by a one shot injection of anti-Thy 1.1 monoclonal antibody followed by unilateral nephrectomy. This model shows that there is a positive association between impairment of vascular regeneration and the development of glomerulosclerosis.

Crescent-forming mechanism in an irreversible Thy-1 model in rats

BACKGROUND

The crescent-forming mechanism has not yet been fully clarified and a cell which constitutes a crescent still remains controversial. This study was undertaken to analyze the crescent-forming mechanism in an irreversible Thy-1 model by applying a new marker-recognizing monoclonal antibody (mAb) OS-3.

METHODS

An irreversible Thy-1 model was induced by an intravenous injection of 500 microg of anti-Thy-1 mAb 1-22-3 to unilaterally nephrectomized Wistar rats. Seven rats were sacrificed 3, 7 and 14 days after the mAb injection respectively and the renal tissues were examined histologically and immunohistochemically.

RESULTS

Inflammatory cells were demonstrated mostly in the interstitium, but they were located within advanced cellular crescents in later stages. OS-3, which stained parietal glomerular epithelial cell (PGEC) only partly in a normal rat kidney section, reacted to PGEC more extensively at day 3 and also with cellular crescents at day 7. During the course of this model the podocytes lost their characteristic to be stained by anti-podocalyxcin Ab and obtained a new marker of a diseased state, i.e. to be positively stained by OS-3.

CONCLUSION

Glomerular epithelial cells, but not inflammatory cells, are suggested to directly participate in the crescent formation in early stages, and podocytes with phenotypic changes might be partly involved in the formation of the crescents.

Cloning and characterization of a novel subunit of protein serine/threonine phosphatase 4 from mesangial cells

Mesangial cells play an important role in maintaining glomeruli structure and function and in the pathogenesis of glomerular diseases. With a novel approach using a rapid large-scale DNA sequencing strategy and computerized data processing, a new human gene, PP4(Rmeg) was cloned. The full-length cDNA clone of human PP4(Rmeg) coded for a novel 950-amino acid protein, which was similar to a subunit of protein serine/threonine phosphatase 4 (PP4). Recombinant PP4(Rmeg) produced in COS-7 cells bound to the catalytic subunit of PP4. PP4(Rmeg) is therefore structurally and functionally related to the recently reported regulatory subunit of PP4, PP4(R1). Amino acid sequence analysis of rat PP4(Rmeg) homologue revealed that the sequences were well conserved between human and rat (86.3% identity). Northern blot analyses of human tissues and cultured cells demonstrated that the regulatory subunits were expressed abundantly in human cultured mesangial cells, although their expression was relatively ubiquitous. In situ hybridization studies in normal human renal tissues confirmed their expression in glomeruli in vivo. The expression was upregulated in glomeruli of anti-Thy1 glomerulonephritis rats before mesangial proliferation. These data demonstrate that PP4(Rmeg) is a novel regulatory subunit of PP4, which is expressed ubiquitously but abundantly in mesangial cells. Its pathophysiologic role in mesangial cells and glomerulus remains unknown. As PP4 is an essential protein for nucleation, growth, and stabilization of microtubules at centrosomes/spindle pole bodies during cell division, PP4(Rmeg) may play a role in regulation of mitosis in mesangial cells.

Podocyte injuries exacerbate mesangial proliferative glomerulonephritis

BACKGROUND

From the observations of morphology seen in early phases of the experimental models of the irreversible mesangial proliferative glomerulonephritis, we hypothesized that podocyte injury is one of the important factors in bringing upon irreversible glomerular alterations. To verify this hypothesis, we investigated whether podocyte injury induced by puromycin aminonucleoside (PAN) injection affects the mesangial alterations of anti-Thy 1.1 glomerulonephritis.

METHODS

Female Wistar rats were injected with 0.5 mg monoclonal antibody (mAb) 1-22-3 five days after the injection of 10 mg or 5 mg/100 g body weight (BW) of puromycin aminonucleoside (PAN), and sacrificed at 7 days or 8 weeks after the mAb 1-22-3 injection.

RESULTS

Consecutive injections of 10 mg/100 g BW of PAN and mAb 1-22-3 caused the irreversible mesangial alteration with persistent proteinuria (at week 8, proteinuria 100.3 +/- 57.8 mg/24 h, matrix score 1.13 +/- 0.52, collagen type I score 2.04 +/- 0.53, mRNA for collagen type I 227 +/- 79% to the group with a single injection of 1-22-3). Although single injection of 5 mg/100 g BW of PAN was not capable of inducing abnormal proteinuria, consecutive injections of 5 mg/100 g BW of PAN and mAb 1-22-3 also caused irreversible mesangial alteration and persistent proteinuria.

CONCLUSIONS

Podocyte injury might be an important factor that exacerbates mesangial proliferation and mesangial matrix expansion. The irreversible mesangial alterations caused by consecutive injections of PAN and mAb 1-22-3 may be a novel model that could be used to analyze the mechanism of progressive mesangial alteration.

Selective CC chemokine receptor expression by central nervous system-infiltrating encephalitogenic T cells during experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a CD4(+) T cell disease of the central nervous system (CNS) characterized by mononuclear cell infiltration, demyelination, and paralysis. Recent studies describing the relationship of chemokine expression with development of clinical disease have led to the hypothesis that distinct chemokine receptors corresponding to specific ligands are expressed by CNS-infiltrating antigen-specific encephalitogenic T cells as well as host-derived bystander T cells and monocytes. In an effort to study encephalitogenic T cell chemokine receptor expression, we examined CC chemokine receptor expression from resting, activated, and CNS-isolated CD4(+) T cells. CCR1, CCR2, CCR3, CCR5, CCR6, CCR7, and CCR8 mRNA is expressed by normal CD4(+) T cells. In vitro activated T cells expressed CCR1, CCR2, CCR3, CCR5, CCR6, CCR7, and CCR8 mRNA as well as CCR4. After EAE induction, CCR1 mRNA was expressed by donor-derived encephalitogenic and host-derived CD4(+) T cells isolated only from CNS and not from spleen. In vivo neutralization of the CCR1 ligand, macrophage inflammatory protein-1alpha (CCL3), resulted in less encephalitogenic CD4(+) T cell CNS infiltration. These results demonstrate the importance of CC chemokine receptor expression by CD4(+) encephalitogenic T cells for CNS infiltration and subsequent disease development.

Effects of retinoids on the TGF-beta system and extracellular matrix in experimental glomerulonephritis

Transforming growth factor-beta1 (TGF-beta 1) overexpression plays a key role in the glomerular accumulation of extracellular matrix proteins in renal disease. Retinoids have previously been shown to significantly limit glomerular damage in rat experimental glomerulonephritis. Therefore, the effects of all-trans retinoic acid and isotretinoin on the components of the TGF-beta system and extracellular matrix proteins in anti-Thy1.1-nephritis (Thy-GN) were investigated. Vehicle-injected control rats were compared with rats treated with daily subcutaneous injections of 10 mg/kg body wt all-trans retinoic acid or 40 mg/kg body wt isotretinoin (n = 9 per group) either with a pretreatment (day -2 through 8) or posttreatment protocol (day +3 through 8), i.e., starting before or after induction of Thy-GN, respectively. Urinary TGF-beta 1 excretion was 60% lower in all-trans retinoic acid-treated animals with Thy-GN (P < 0.025). The increase of cortical TGF-beta 1 gene expression in Thy-GN rats was significantly attenuated with all-trans retinoic acid and even more with isotretinoin treatment as compared with untreated animals (P < 0.025). Cortical expression of TGF receptor II, but not receptor I gene expression, was significantly lower in animals treated with all-trans retinoic acid or isotretinoin (P < 0.05). In all-trans retinoic acid-treated animals with Thy-GN, the increase of glomerular TGF-beta 1 protein (P < 0.008) and TGF-beta 1 (P < 0.025) and TGF receptor II mRNA (P < 0.015) was significantly less. Immunohistochemistry revealed less glomerular staining for TGF-beta 1 and TGF receptor II in the presence of all-trans retinoic acid. TGF-beta 1 immunostaining was not restricted to monocytes and macrophages, as indicated by double-staining. Glomerular staining for collagen IV and collagen III was less in animals treated with isotretinoin (P < 0.02 for both) in contrast to all-trans retinoic acid, whereas fibronectin remained unchanged. It was concluded that the beneficial effects of retinoids on glomerular damage are presumably due to a marked reduction in renal TGF-beta 1 and TGF receptor II expression.

Effects of all-trans retinoic acid on renin-angiotensin system in rats with experimental nephritis

We previously demonstrated that all-trans retinoic acid (RA) preserves glomerular structure and function in anti-Thy1.1 nephritis (Wagner J, Dechow C, Morath C, Lehrke I, Amann K, Floege J, and Ritz E. J Am Soc Nephrol 11: 1479-1489, 2000). Because the renin-angiotensin system (RAS) contributes to renal damage, we 1) studied retinoid-specific effects on its components and 2) compared the effects of all-trans-RA with those of the AT(1)-receptor blocker candesartan. Rats were pretreated for 3 days before injection of the OX-7 antibody and continued with treatment with either vehicle or daily injections of 10 mg/kg all-trans-RA only (study 1) or 10 mg/kg body wt all-trans-RA, 1 mg/kg candesartan, or both (study 2) for an additional 7 days. The blood pressure increase observed in anti-Thy1.1 nephritic rats was equally normalized by all-trans-RA and candesartan (P < 0.05). In nephritic rats, mRNAs of angiotensinogen and angiotensin-converting enzyme (ACE) in the kidney were unchanged, but renin mRNA was lower (P < 0.01). Renal and glomerular AT(1)-receptor gene and protein expression levels were higher in anti-Thy1.1 nephritic rats (P < 0.05). In the renal cortex of nephritic rats, pretreatment with all-trans-RA significantly reduced mRNAs of all the examined RAS components, but in the glomeruli it increased ACE gene and protein expression (P < 0.01). In nephritic rats, candesartan reduced the number of glomerular cells and mitoses (P < 0.05) less efficiently than all-trans-RA (P < 0.01). Both substances reduced cellular proliferation (proliferating cell nuclear antigen) significantly (P < 0.05). No additive effects were noted when both compounds were combined. In conclusion, all-trans-RA influences the renal RAS in anti-Thy1.1 nephritis by decreasing ANG II synthesis and receptor expression. The beneficial effect of retinoids may be explained, at least in part, by reduction of RAS activity.

Isolation, characterization, and transplantation of bone marrow-derived hepatocyte stem cells

Recently it was shown that a population of cells in the bone marrow-expressing hematopoietic stem cell antigens could differentiate into hepatocytes. However, explicitly committed hepatocyte progenitors, which exhibit highly differentiated liver functions, immediately upon isolation, have not yet been isolated from bone marrow. After studying common antigens on blast-like cells in fetal and adult regenerating cholestatic rat livers and human regenerating and malignant livers, we hypothesized that beta-2-microglobulin-negative (beta(2)m(-)) cells might represent dedifferentiated hepatocytes and/or their progenitors. Utilizing a two-step magnetic bead cell-sorting procedure, we show that in bone marrow from rat and human, beta(2)m(-)/Thy-1(+) cells consistently express liver-specific genes and functions. After intraportal infusion into rat livers, bone marrow-derived hepatocyte stem cells (BDHSC) integrated with hepatic cell plates and differentiated into mature hepatocytes. In a culture system simulating liver regeneration and containing cholestatic serum, these cells differentiated into mature hepatocytes and metabolized ammonia into urea. This differentiation was dependent on a yet nondescript humoral signal existing in the cholestatic serum. Transmission electron microscopy and three-dimensional digital reconstruction confirmed hepatocyte ultrastructure of cultured BDHSC.

Nutrition disorders and immunologic parameters: study of the thymus in growing rats

OBJECTIVES

We studied the effect of a low-quality dietary protein on cellular proliferation and maturation in the thymus of growing rats over time.

METHODS

After weaning Wistar rats were fed a diet containing 6.5 g/100 g of corn flour for 6, 10, 18, and 45 d (M groups). For comparison, other rats were fed a diet containing 6.5 g/100 g of casein (Cas groups), and well-nourished age-matched control rats were fed a commercial laboratory diet (C groups). Food intake, body weight, thymus weight, total number of thymocytes, and the percentages of CD43(+) and Thy1(+) thymocyte phenotypic antigen determinants were measured.

RESULTS

M versus Cas and C groups showed significant differences (P < 0.01) in body and thymus weights after 6 d of feeding, and the total number of thymocytes and the percentages of CD43(+) and Thy1(+) were significantly lower after 10 d of feeding. The results indicated that consuming a cereal diet for short or long periods causes thymus atrophy in growing rats, with significant reductions in the total number of T-cells concomitant with increases in the number of immature thymocytes.

CONCLUSIONS

The data showed that, in addition to low-protein concentration, low-quality dietary protein is a limiting factor in certain steps of cellular intrathymic pathways, probably related to the requirement of specific amino acids for optimal immune response.