Analysis of CD34+ cell subsets in stem cell harvests can more reliably predict rapidity and durability of engraftment than total CD34+ cell dose, but steady state levels do not correlate with bone marrow reserve

In peripheral blood stem cell transplantation (PBSCT), the number of CD34+ cells transplanted has been shown to correlate well with both rapidity and durability of engraftment. However, it is clear that engraftment does not necessarily correlate with total CD34+ cell numbers in some patients. Consequently, there is increasing interest in evaluating the role of CD34+ subsets in haemopoietic recovery as a more accurate marker of harvest quality. We analysed the numbers of CD34+ cell subsets, namely Thy-1+, L-Selectin+ and CD38-, and correlated this with engraftment in 86 patients undergoing PBSCT. Adequate engraftment was defined as being a platelet count greater than 50 x 10(9)/l and a neutrophil count greater than 1.0 x 10(9)/l. CD34+L-Selectin+ provided the best prediction of engraftment rapidity, although the improvement over total CD34+ cell dose was minor. Only the dose of CD34+Thy-1+ cells transplanted correlated with durable engraftment. The probability of adequate 3-month engraftment increased with the dose of CD34+ cells transplanted, but 10% of patients receiving > 5 x 10(6)/kg still showed poor engraftment at 3 months. However, all patients receiving > 2.5 x 10(5)/kg CD34+Thy-1+ showed adequate engraftment at this time point. We also demonstrated that CD34+Thy-1+ progenitors were restricted to the bone marrow under normal conditions and, during stem cell mobilization, their kinetics generally paralleled total CD34+ numbers.

Role for lipid rafts in regulating interleukin-2 receptor signaling

Lipid rafts are plasma membrane microdomains characterized by a unique lipid environment enriched in gangliosides and cholesterol, leading to their insolubility in nonionic detergents. Many receptors are constitutively or inducibly localized in lipid rafts, which have been shown to function as platforms coordinating the induction of signaling pathways. In this report, the first evidence is provided for a role of these lipid microdomains in regulating interleukin-2 receptor (IL-2R) signaling. It is demonstrated that antibody- or ligand-mediated immobilization of components of lipid rafts, glycosyl-phosphatidyl-inositol-anchored proteins, and the GM1 ganglioside, respectively, inhibit IL-2-induced proliferation in T cells. IL-2Ralpha is shown to be constitutively enriched in rafts and further enriched in the presence of immobilized anti-Thy-1. In contrast, IL-2Rbeta and IL-2Rgamma, as well as JAK1 and JAK3, are found in soluble membrane fractions, and their localization is not altered by anti-Thy-1. IL-2-mediated heterotrimerization of IL-2R chains is shown to occur within soluble membrane fractions, exclusively, as is the activation of JAK1 and JAK3. As predicted by these results, the disruption of lipid raft integrity did not impair IL-2-induced signaling. Thus, the sequestration of IL-2Ralpha within lipid microdomains restricts its intermolecular interactions and regulates IL-2R signaling through impeding its association with IL-2Rbeta and IL-2Rgamma.

Cloning of rodent megsin revealed its up-regulation in mesangioproliferative nephritis

BACKGROUND

We recently cloned a new human mesangium-predominant gene, megsin. Megsin is a novel member of the serine protease inhibitor (serpin) superfamily. To elucidate functional roles of this gene, we cloned megsin in rodents and investigated its role in a rat nephritis model.

METHODS

Megsin homologues were cloned from cultured rat and mouse mesangial cDNAs utilizing polymerase chain reaction (PCR) with degenerative primers. Expression of megsin in three different types of resident glomerular cells was investigated by PCR. Levels of megsin mRNA expression at various time points in the anti-Thy1 rat nephritis model were studied by semiquantitative PCR and Northern blotting analysis. In order to investigate megsin protein expression in anti-Thy1 nephritis rats, we raised antibody against rat megsin-specific synthetic peptide, with which immunohistochemical studies were performed.

RESULTS

Rat and mouse megsins were composed of 380 amino acids, which revealed 75.3 and 73.9% identity, respectively, with human megsin at the amino acid level. Characteristic features as an inhibitory serpin were conserved in both rat and megsin megsins. PCR analysis revealed expression of megsin in cultured mesangial cells but not in glomerular epithelial or endothelial cells. In anti-Thy1 nephritis rats, semiquantitative PCR and Northern blotting showed that expression of megsin mRNA was up-regulated in glomeruli at day 8. Immunohistochemical studies demonstrated the prominent accumulation of megsin in glomeruli at the same time point. Megsin was mainly localized in mesangial area. The megsin expression level returned to the basal level at day 28.

CONCLUSION

Sequences of megsin were well conserved among different species. Rat megsin was also predominantly expressed in mesangial cells. Expression of megsin was up-regulated at the peak of hypercellularity and matrix accumulation in the mesangioproliferative glomerulonephritis model, suggesting that megsin may participate in the process of glomerulosclerosis by modulating extracellular matrix deposition or cell survival.

Anti-Thy-1 monoclonal antibody with specific reactivity with vascular endothelial cells in rat glomeruli

Inoculation with anti-Thy-1 antibodies (Abs) in rats induces glomerulonephritis resembling human mesangiolytic and/or mesangioproliferative diseases. Some anti-Thy-1 monoclonal Abs (mAbs) react with both mesangial and glomerular endothelial cells, whereas others react solely with mesangial cells in rat kidney. These findings suggest that the rat Thy-1 molecule possesses at least 2 variant forms, including a mesangial and a vascular endothelial isoform. However, anti-Thy-1 mAbs with specific reactivity with glomerular endothelial cells have not been available. We describe here a unique anti-rat Thy-1 mAb, TM78-8. The epitope for TM78-8 is closely related, but not identical, to that for OX-7, a commercially available anti-rat Thy-1 mAb. Immunoblotting, immunohistochemistry and immunoelectron microscopy confirm that TM78-8 reacts exclusively with Thy-1 antigens on the surface of vascular endothelial cells in rat glomeruli. TM78-8 may be a suitable marker for rat glomerular endothelial cells as well as for the vascular endothelial isoform of the rat Thy-1 molecule. Intravenous injection of TM78-8 did not induce glomerulonephritis in rats, whereas OX-7 did, indicating that TM78-8 is not nephritogenic. This finding also corresponds with the current consensus that Thy-1 antigens expressed on mesangial cells play an essential role in the development of Thy-1 nephritis.

New method of purification for establishing primary cultures of ensheathing cells from the adult olfactory bulb

Ensheathing cells exclusively enfold olfactory axons. The ability of olfactory axons to reinnervate the adult mammalian olfactory bulb throughout the lifetime of an organism is believed to result from the presence of this unique glial cell in the olfactory system. This theory has been substantiated by research demonstrating the ability of transplanted ensheathing cells to promote axonal regrowth in areas of the central nervous system that are normally nonpermissive. A simple method for purifying ensheathing cells resulting in a large yield of cells is therefore invaluable for transplantation studies. We have developed such a method based on the differing rates of attachment of the various harvested cell types. The greatest percentage of cells (70.4%) that attached during the first step of the separation was determined to be fibroblasts. The remainder of the cells were classified as astrocytes (20.8%) and ensheathing cells (6.8%). The percentage of attached astrocytes (67.6%) was greatly increased during the second purification step while the percentage of fibroblasts decreased greatly (27.9%) and the percentage of ensheathing cells (5.3%) slightly decreased. In the final cultures, 93.2 % of the attached cells were ensheathing cells, while astrocytes (5.9%) and fibroblasts (1.4%) were only minor components. This simple, inexpensive method of purifying ensheathing cells will facilitate their use in central nervous system regeneration research.

CD4 and CD8 monoclonal antibody therapy in canine renal allografts

Therapy with CD4 and CD8 monoclonal antibodies was evaluated in dogs which received double-haplotype MHC-mismatched renal allografts. Neither CD4 nor CD8 monoclonal antibodies given alone prolonged allografts survival (creatinine > or = 300 micromol/l) beyond 7 days. However, combined therapy with CD4 and CD8 antibodies given up to day 10 did prolong allograft survival to a median of 14 days. A longer (21 day) course of CD4 and CD8 antibodies did not extend allograft survival further. The effect of prolonged antibody therapy was restricted by the occurrence of both an antiglobulin response and an anaphylactoid reaction to the monoclonal antibody preparation. When the CD4 and CD8 antibodies were combined with a pan-T-cell-depleting Thy-1 antibody, the survival of double-haplotype mismatched allografts was further prolonged (median 16 days). The median survival of single-haplotype mismatched renal allografts on this triple therapy was 21 days, with one surviving to day 36.

PDGF signal transduction inhibition ameliorates experimental mesangial proliferative glomerulonephritis

BACKGROUND

Platelet-derived growth factor (PDGF) has been consistently implicated in the cell proliferation and extracellular matrix accumulation, which characterize progressive glomerular disease. In the present study, the effects of a potent and selective inhibitor of PDGF receptor tyrosine kinase, STI 571, were examined in vitro and in vivo.

METHODS

Cultured mesangial cells were incubated with PDGF (50 ng/mL) and fibroblast growth factor-2 (FGF-2; 50 ng/mL) and treated with STI 571 (0.13 to 2.0 micromol/L). Experimental mesangial proliferative glomerulonephritis was induced in male Wistar rats with monoclonal OX-7, anti-rat Thy-1.1 antibody with rats randomized to receive either STI 571 (50 mg/kg intraperitoneally daily) or vehicle. Animals were examined six days later.

RESULTS

In vitro, both PDGF and FGF-2 induced a threefold increase in mesangial cell 3H-thymidine incorporation. STI 571 reduced PDGF but not FGF-2-stimulated mesangial cell proliferation in a dose-dependent manner, with complete abolition at 0.4 micromol/L. In animals with Thy-1.1 glomerulonephritis, PDGF receptor tyrosine kinase blockade was associated with significant reductions in mesangial cell proliferation (P < 0.001), the number of activated (alpha-smooth muscle positive) mesangial cells, and glomerular type IV collagen deposition (P < 0.001).

CONCLUSION

The amelioration of the pathological findings of experimental mesangial proliferative glomerulonephritis by blockade of PDGF receptor activity suggests the potential clinical utility of this approach as a therapeutic strategy in glomerular disease.

Participation of endothelial cells and transformed mesangial cells in remodeling of glomerular capillary loops in Thy-1 nephritis

The relationship between mesangial cells (MC) and endothelial cells (EC) in the remodeling of glomerular capillary loops was investigated in a rat model of anti-Thy-1 antibody (Ab)-induced glomerulonephritis. Immunohistochemical analysis showed that cells positive for alpha-smooth muscle actin (alpha-SMA) appeared in the mesangial stalks at day three, and had increased in number at day seven, after injection of Thy-1 Ab. Double staining for alpha-SMA and proliferating cell nuclear antigen (PCNA) showed that some MC expressing PCNA were negative for alpha-SMA at day three, but by day seven almost all PCNA-positive MC expressed alpha-SMA. Western blotting for alpha-SMA from isolated glomeruli was negative at day one after injection of Thy-1 Ab, but positive at day seven. Type III collagen appeared at day seven, followed by an increase of EC in the capillary loops, as determined by double immunofluorescent staining for rat endothelial cell antigen-1 (RECA-1) and type III collagen. RECA-1-positive cells increased rapidly in number after day seven and eventually showed the same distribution pattern as that in control rats. Both type I and type III collagens were expressed in the mesangial and the ballooning area of the glomerulus at day seven. Electron microscopy revealed that immature MC and EC forming small capillary lumina appeared in the enlarged mesangial area at day seven. In accordance with the increase of capillaries and the enlargement of the lumina, the number of MC and the amount of mesangial matrix decreased gradually, and most of the glomeruli returned to a normal structure by week 4. These data show that type I and type III collagen produced by transformed MC may be of benefit to proliferation of EC and remodeling of the capillary in Thy-1-induced nephritis.

Induction of renal cell apoptosis by antibodies and complement

Renal diseases are in many cases associated with the presence of increased numbers of apoptotic cells in the kidney. Apoptosis has been proposed as an important mechanism involved in the resolution of a proliferative response. Furthermore, recent studies indicate its possible involvement in progression of renal disease, leading to sclerosis. Moreover, in an experimental model of acute mesangioproliferative glomerulonephritis in the rat, induced via antibodies directed to Thy-1, evidence was obtained for the occurrence of apoptosis coinciding with the very early induction of mesangial injury. The present review is focused on apoptosis in relation to this model, and discusses recent findings concerning direct involvement of triggering of Thy-1 as well as deposition of terminal complement complexes in the induction of mesangial cell apoptosis.

Characterization of a transformed rat retinal ganglion cell line

The purpose of the present study was to establish a rat retinal ganglion cell line by transformation of rat retinal cells. For this investigation, retinal cells were isolated from postnatal day 1 (PN1) rats and transformed with the psi2 E1A virus. In order to isolate retinal ganglion cells (RGC), single cell clones were chosen at random from the transformed cells. Expression of Thy-1 (a marker for RGC), glial fibrillary acidic protein (GFAP, a positive marker for Muller cells), HPC-1/syntaxin (a marker for amacrine cells), 8A1 (a marker for horizontal and ganglion cells) and neurotrophins was studied using reverse transcriptase-polymerase chain reaction (RT-PCR), immunoblotting and immunocytochemistry. One of the retinal cell clones, designated RGC-5, was positive for Thy-1, Brn-3C, Neuritin, NMDA receptor, GABA-B receptor, and synaptophysin expression and negative for GFAP, HPC-1, and 8A1, suggesting that it represented a putative RGC clone. The results of RT-PCR analysis were confirmed by immunocytochemistry for Thy-1 and GFAP. Upon further characterization by immunoblotting, the RGC-5 clone was positive for Thy-1, negative for GFAP, 8A1 and syntaxin. RGC 5 cells were also positive for the expression of neurotrophins and their cognate receptors. To establish the physiological relevance of RGC-5, the effects of serum/trophic factor deprivation and glutamate toxicity were analyzed to determine if these cells would undergo apoptosis. The protective effects of neurotrophins on RGC-5 after serum deprivation was also investigated. Apoptosis was studied by terminal deoxynucleotidyl transferase-mediated fluoresceinated dUTP nick end labeling (TUNEL). Serum deprivation resulted in apoptosis and supplementation with both BDNF and NT-4 in the growth media, protected the RGC-5 cells from undergoing apoptosis. On differentiation with succinyl concanavalin A (sConA), RGC-5 cells became sensitive to glutamate toxicity, which could be reversed by inclusion of ciplizone (MK801). In conclusion, a transformed rat retinal cell line, RGC-5, has certain characteristics of retinal ganglion cells based on Thy-1 and Brn-3C expression and its sensitivity to glutamate excitotoxicity and neurotrophin withdrawal. These cells may be valuable in understanding of retinal ganglion cell biology and physiology including in vitro manipulations in experimental models of glaucoma.

Production of interferon-gamma by influenza hemagglutinin-specific CD8 effector T cells influences the development of pulmonary immunopathology

This study examined the inflammation, lung function impairment, and immune protection associated with either wild-type or interferon (IFN)-gamma-deficient Tc1- or Tc2-CD8 effector cells responding to influenza pneumonia. The adoptive transfer of influenza hemagglutinin-specific Tc1 effectors afforded protection and elicited only minimal impairment of lung function. IFN-gamma-deficient Tc1 effector cells were equally protective, but were associated with an eosinophil influx and slightly more lung function impairment early in the response. Relative to Tc1, Tc2 effector cells were less protective, elicited an eosinophil influx and a greater impairment of lung functions. IFN-gamma-deficient Tc2 effector cells were not protective and were associated with the severest impairment of lung function throughout the response, an accumulation of neutrophils, and extensive pulmonary vasculitis and alveolar hemorrhaging. Deletion of IFN-gamma was associated with a delay in effector cell recruitment and the elicitation of a more intense inflammatory response that resulted in more severe lung function impairment in the recipients of either Tc1 or Tc2 IFN-gamma-deficient effector cells. Thus, during influenza infections, IFN-gamma production by the responding CD8 T cells is associated with effector cell recruitment and mitigation of the associated inflammation and of the resulting impairment in lung functions but is not necessary for optimal protection.

Anti-Thy-1 monoclonal antibody-induced glomerulonephritis in Mongolian gerbils

Two novel murine monoclonal antibodies (mAbs) were produced to the Thy-1 molecule of Mongolian gerbils (Meriones unguiculatus). These mAbs, HUSM-M.g.27 of IgG1 isotype and HUSM-M.g.40 of IgG2a isotype, immunohistochemically reacted with the thymus, nervous system, and glomerular mesangium in partially different manners, suggesting that they recognize distinct epitopes, although they reacted with Thy-1 antigen, with apparent molecular weight of about 25 kDa, on gerbil thymocytes. Mild and severe forms of mesangioproliferative nephritis after glomerular deposition of the antibody was observed in gerbils administered mAbs HUSM-M.g.27 and HUSM-M.g.40, respectively, intraperitoneally, with or without guinea-pig serum as supplementary complement. Distinct pathogenicity and requirement of guinea pig serum for pathologic sequels are discussed as they relate to the rat model of anti-Thy-1-induced glomerulonephritis.

Agmatine inhibits cell proliferation and improves renal function in anti-thy-1 glomerulonephritis

Changes in the expression of alternate arginine metabolic pathways have been implicated in the pathogenesis of experimental glomerulonephritis. Agmatine, decarboxylated arginine, has been shown in vitro to suppress both inducible nitric oxide synthase and the rate-limiting enzyme of polyamine biosynthesis, ornithine decarboxylase (ODC). This study was undertaken to determine whether agmatine administration could reduce tissue injury by decreasing nitric oxide, and reduce cell proliferation, by diminishing ODC activity, in experimental mesangial proliferative glomerulonephritis (Thy-1 nephritis). Agmatine treatment (50 mg/kg per d intraperitoneally) in Thy-1 nephritis rats prevented a reduction in GFR at day 1. Agmatine treatment decreased nitric oxide production in Thy-1 nephritis rats by 23% and 41% at days 1 and 4, respectively. Agmatine treatment also reduced ODC activity and glomerular (3)H-thymidine incorporation on days 1, 4, and 7. Histologic evaluation revealed a decline in mesangial cell proliferation and extracellular matrix accumulation associated with agmatine treatment administered before or 24 h after Thy-1 antibody, and this was confirmed by a reduction in the number of cells expressing proliferating cell nuclear antigen on days 4 and 7. These studies provide the first in vivo evidence that agmatine administration can reduce cellular proliferation in Thy-1 nephritis and attenuate the initial reduction in renal function associated with this model.

Requirement of heat shock protein 90 in mesangial cell mitogenesis

BACKGROUND

Hyperplasia of mesangial cells (MCs) is a frequent finding in glomerulonephritis. Heat shock protein 90 (HSP90) is a major cellular chaperone that assists protein folding under physiological and stress conditions.

METHODS

To identify genes that are potentially involved in the pathogenesis of glomerulonephritis, we analyzed glomerular gene expression in mesangioproliferative rat anti-Thy1.1 nephritis by representational difference analysis (RDA). Expression of HSP90beta in anti-Thy1.1 nephritis was studied by Northern and Western blot analyses and immunohistochemistry. In cultured rat MCs, the requirement of HSP90 for mitogenic signaling steps and MC replication was studied by incubation with the specific HSP90 inhibitor geldanamycin.

RESULTS

By RDA, a cDNA fragment homologous to HSP90beta was identified. Glomerular mRNA and protein expression of HSP90beta was markedly and transiently up-regulated during the course of anti-Thy1.1 nephritis, with a maximum at day 6, coinciding with the peak of MC proliferation. By immunohistochemistry, HSP90beta expression in normal glomeruli was detected in podocytes. However, in anti-Thy1.1 nephritis, glomerular HSP90beta protein expression was strongly and transiently increased in mesangial localization. In vitro, mitogenic stimulation of rat MCs led to the induction of HSP90beta mRNA and protein. Incubation of MCs with geldanamycin dose-dependently inhibited DNA synthesis and replication. Moreover, geldanamycin interfered with mitogen-induced phosphorylation of extracellular signal-regulated kinase and transcription of c-fos and Egr-1, but not with transactivation of STAT1 transcription factor. Cell cycle analysis of serum-stimulated MCs revealed that geldanamycin inhibited kinase activity of cyclin D1/CDK4 complexes and blocked progression in the G0/G1 phase and at the S/G2 phase transition.

CONCLUSIONS

The up-regulation of HSP90beta in anti-Thy1.1 nephritis may reflect its functional involvement in phenotypical alterations of MCs in mesangioproliferative glomerulonephritis. Our in vitro studies indicate that HSP90 governs the capacity of MCs to respond to proliferative stimuli by regulating critical mitogenic signaling steps necessary for G1 entry and S-phase progression.

Effects of chitosan-coated dialdehyde cellulose, a newly developed oral adsorbent, on glomerulonephritis induced by anti-Thy-1 antibody in rats

The effects of chitosan-coated dialdehyde cellulose (chitosan DAC), a newly developed oral adsorbent for urea and ammonia, were examined in a glomerulonephritis model in rats. Mesangial proliferative glomerulonephritis accompanied with proteinuria was induced by an intravenous injection of anti-rat Thy-1.1 monoclonal antibody (OX-7). The proliferation of mesangial cells and an accumulation of extracellular matrix components such as type I collagen and fibronectin were observed in the glomeruli 9 days after OX-7 injection; these were improved in rats fed a diet containing chitosan DAC (10% content) for 9 days compared with those in rats fed a normal diet. Chitosan DAC treatment decreased the elevated urinary protein and blood urea nitrogen at days 8-9 to the normal levels; the increased fecal excretion of nitrogen might participate in this phenomenon. In addition, chitosan DAC treatment showed an increase in fecal water content associated with a decrease in urinary volume. These therapeutic effects may be due to the reduction of proteinic factor expression and the compensational function of chitosan DAC for kidney. These results suggest that chitosan DAC treatment may be useful for ameliorating mesangial proliferative glomerulonephritis.

Comparative nephritogenicity of two monoclonal antibodies that recognize different epitopes of rat Thy-1.1 molecule

The pathophysiological role of the Thy-1.1 molecule expressed on rat mesangial cells with regard to mesangial cell dysfunction and injury remains unknown. The mechanism of Thy-1.1-associated injury has now been investigated with two monoclonal antibodies, 1-22-3 and OX7, that recognize different epitopes of Thy-1.1. Mesangiolysis and mesangial cell proliferation were more marked in rats injected with 1-22-3 than in those treated with OX7. Immunostaining for rat complement component C3 and also C9 was similar in the kidneys of rats 1 h after injection of either antibody. Alpha smooth muscle actin was first detected 3 days after injection of 1-22-3 and peaked on day 5; type I collagen staining showed a mesangial pattern on days 5 and 10. The staining for alpha smooth muscle actin and type I collagen was less intense in OX7-treated rats than in the 1-22-3-injected rats. The amounts of mRNAs encoding collagen types I and III peaked 5 days after injection of 1-22-3 and 10 days after injection of OX7. Rats injected with 1-22-3 developed proteinuria that was already marked on day 1 and peaked at 150 mg/day on day 3, whereas OX7 induced a low grade of proteinuria with large interindividual variability on day 3. Immunostaining for rat C3 in the normal rat kidneys, incubated in vitro with 1-22-3 or OX7 followed by incubation with normal rat fresh serum as a complement source, as well as the levels of serum complement activity, CH50, 30 min after injection of 1-22-3 or OX7 were similar, suggesting that the difference in the nephritogenicity of these two antibodies is not attributable to a difference in their complement-fixing activities, but rather may result from the difference in epitope specificities. The epitope recognized by 1-22-3 thus appears to be important in the initiation and progression of antibody-induced nephritis.

Splenic cytotoxic cells recognize surface HSP70 on culture-adapted EL-4 mouse lymphoma cells

Heat shock proteins (HSPs) are intracellular proteins which function as molecular chaperones. At the same time, translocation of HSPs to the cell surface has been observed in stressed, infected and transformed cells. It seems plausible that surface HSPs may represent molecular targets for recognition and elimination of 'altered' cells by cytotoxic lymphocytes. Previously we demonstrated that EL-4 mouse lymphoma cells growing in vitro express HSPs on their plasma membrane. In this study, we tested the hypothesis that surface HSPs present on EL-4 cells may mediate their recognition and killing by cytotoxic lymphocytes. We have found that susceptibility of culture-adapted EL-4 cells to in vitro lysis by syngeneic and allogeneic splenocytes correlated with the expression of HSP70 on EL-4 cells. Moreover, cytotoxicity was blocked by pretreatment of EL-4 target cells with anti-HSP70 antibody, whereas antibodies to MHC class I molecules and Thy1 did not have such effect. Cytotoxicity against EL-4 lymphoma was not MHC class I-restricted, and was not decreased after depletion of CD8(+) cells from the effector cell population. We conclude that in vitro killing of EL-4 cells is mediated, at least in part, by NK cells via recognition of HSPs present on the surface of tumor cells. Thus, cytotoxic response against EL-4 lymphoma should serve as a good model to study the role of HSPs in anti-tumor immunity.

Synergism of Pseudomonas aeruginosa exotoxin A with endotoxin, superantigen, or TNF results in TNFR1- and TNFR2-dependent liver toxicity in mice

Pseudomonas aeruginosa is a potentially dangerous Gram-negative nosocomial pathogen, causing bacteremia in debilitated patients, and a prominent cause of bacterial cholangitis. Opportunistic infections with other nosocomial pathogens, e.g. Staphylococcus aureus, are common. Hence, multi-intoxication with P. aeruginosa exotoxin A (PEA) and other bacterial toxins, including endotoxin (LPS) and the superantigen S. aureus enterotoxin B (SEB), is very likely. Here we show that PEA synergistically interacted with LPS, SEB, or recombinant murine tumor necrosis factor alpha (rmuTNF) in mice, resulting in severe liver injury. Enhanced and prolonged circulation of cytokines, including TNF, which depended on the presence of T cells, was a remarkable feature of synergistic PEA/LPS- or PEA/SEB-induced hepatotoxicity. PEA/LPS-, PEA/SEB- or PEA/rmuTNF-induced liver injury was mediated by both TNF receptors (TNFRs), i.e. TNFR1 and TNFR2. In view of the fact that TNFR1, but not TNFR2, signaling is unequivocally required for host defense, our results suggest that anti-TNFR2 strategies might be beneficial to protect the liver from inflammatory damage caused by synergistic interactions of PEA with other TNF-inducing bacterial toxins.

Complement-mediated killing of mesangial cells in experimental glomerulonephritis: cell death by a combination of apoptosis and necrosis

Immune system mediated, particularly antibody- and complement-mediated, glomerular injury triggers glomerulonephritis (GN). To characterize complement-mediated cytotoxicity in GN, we assessed the process of mesangial cell death induced by C5b-9 attack in Thy-1 GN. Cell injury was recognized morphologically, and nuclear DNA breaks were confirmed by the DNA nick end labeling (TUNEL) method as well as DNA gel electrophoresis. Thy-1 GN was induced in rats with anti-Thy-1.1 antibody injection. Mouse IgG (administered antibody) and rat C3 were detected in all glomeruli within 5 min after antibody injection. Damaged mesangial cells with condensed as well as TUNEL-positive nuclei could be observed at 20 min and became prominent at 40-60 min. Ultrastructurally, damaged mesangial cells contained condensed apoptotic nuclei from 40 to 60 min, whereas the cytoplasm showed necrotic degeneration. This was followed by progressive lysis of both nuclei and cytoplasm. The DNA 'ladder' pattern was observed by gel electrophoresis of extracted DNA between 40 and 60 min and correlated with the increased number of TUNEL-positive damaged mesangial cells. To examine the role of complement in this form of cell death, complement depletion was induced in rats by cobra venom factor. Complement-depleted rats showed no rat C3 deposition, rare TUNEL-positive mesangial cells, rare ultrastructural degenerated mesangial cells with apoptotic nuclei and necrotic cytoplasm, and no DNA 'ladder' pattern on gel electrophoresis at 40 min, although prominent mouse IgG was seen in glomeruli. To analyze milder forms of complement injury, a low dose of the antibody was administered to rats with a normal complement level. A few TUNEL-positive mesangial cells were detected in the glomeruli which contained apoptotic nuclei and necrotic cytoplasm. Our results indicate that an apoptotic death mechanism accompanies cell necrosis in complement-mediated mesangial cell destruction in GN and that this unusual form of cell death may represent a combination of apoptosis-necrosis within the same cell. Complement injury activates a 'death program' which in turn leads to irreversible damage of mesangial cells and which may contribute to initiation and development of GN.

Antiproliferative effect of a lectin- and anti-Thy-1.2 antibody-targeted HPMA copolymer-bound doxorubicin on primary and metastatic human colorectal carcinoma and on human colorectal carcinoma transfected with the mouse Thy-1.2 gene

The aim of this study was to compare the potential of two plant lectins [peanut agglutinin (PNA) and wheat germ agglutinin (WGA)], monoclonal antibody (anti-Thy-1.2), its F(ab')(2) fragments, and galactosamine as targeting moieties bound to the polymer drug carrier to deliver a xenobiotic, doxorubicin, to selected cancer cell lines. We have used primary (SW 480, HT 29) and metastatic (SW 620) human colorectal cancer cell lines and a transfectant, genetically engineered SW 620 cell line with mouse gene Thy-1.2 (SW 620/T) to test the possibility of marking human cancer with xenogeneic mouse gene and use it for effective site-specific targeting. The targeting moieties and doxorubicin were conjugated to a water-soluble copolymer based on N-(2-hydroxypropyl)methacrylamide (HPMA) acting as a carrier responsible for controlled intracellular release of the targeted drug. FACS analysis showed a strong binding of WGA-FITC to all tested cell lines. Binding of PNA-FITC was considerably weaker. The in vitro antiproliferative effect of lectin-targeted HPMA carrier-bound doxorubicin evaluated as [(3)H]TdR incorporation reflected both the intensity of the binding and the different sensitivity of the tested cancer cells lines to doxorubicin. The antiproliferative effect of conjugates targeted with WGA was comparable to that with the conjugates targeted with the anti-Thy-1.2 monoclonal antibody or their F(ab')(2) fragments. The magnitude of the cytotoxic effect of HPMA-doxorubicin targeted with PNA was lower in all tested cell lines. While the conjugates with WGA were more cytotoxic, the conjugates with PNA were more specific as their binding is limited to cancer cells and to the sites of inflammation. Noncytotoxic conjugates with a very low concentration of doxorubicin and targeted with PNA, anti-Thy-1.2, or their F(ab')(2) fragments exerted in some lines (SW 480, SW 620) low mitogenic activity. The Thy-1.2 gene-transfected SW 620 metastatic colorectal cancer cell line was sensitive to the antiproliferative effect of Thy-1.2-targeted doxorubicin as was shown for the Thy-1. 2(+) EL4 cell line and for Thy-1.2(+) concanavalin A-stimulated mouse T lymphocytes. These results represent the first indication of the suitability of transfection of human cancer cells with selected targeting genes for site-specific therapy of malignancies.

Sublytic complement injury does not activate NF-kappa B, or induce mitogenesis in rat mesangial cells

Sublytic complement injury to glomerular mesangial cells, mediated by the terminal membrane attack complex of complement (C5b-9), is a potential initiating mechanism in IgA nephropathy. Sublytic complement injury has been reported to result in the production of a variety of pro-inflammatory molecules and growth factors, including many regulated by the transcription factor NF-kappa B. To determine the importance of complement injury in the pro-inflammatory signalling which occurs in IgA nephropathy, we investigated NF-kappa B activation following sublytic complement injury to cultured rat glomerular mesangial cells (RMCs). A sublytic dose of rabbit anti-Thy 1.1 (THY) serum and normal human serum was selected based upon flow cytometry, chromium-release assay, and induction of superoxide production. No significant C5b-9-induced NF-kappa B activation was detected by electrophoretic mobility shift assays, luciferase activity of RMCs transfected with a NF-kappa B-driven luciferase reporter construct, nor by Northern blots for the NF-kappa B-responsive mRNA species monocyte chemoattractant protein-1 or I kappa B alpha. Furthermore, measurements of (3)H incorporation following sublytic complement injury showed inhibition of mesangial cell mitogenesis in comparison to the heat-inactivated serum treatment and to THY alone. The results of this study suggest that sublytic complement injury to RMC does not directly activate NF-kappa B nor induce mesangial cell proliferation in mesangial cells. Other mechanisms such as IgA immune complex formation must be required to produce these events in IgA nephropathy.

Upregulation of cyclooxygenase-1 and the PGE2 receptor EP2 in rat and human mesangioproliferative glomerulonephritis

OBJECTIVE AND DESIGN

Glomerular expression and localization of the two cyclooxygenase isoforms, Cox-1 and Cox-2, and the prostaglandin E2 receptor EP2 were investigated in a rat model of transient mesangioproliferative glomerulonephritis. Cox expression was also studied in biopsies from patients with IgA nephropathy.

MATERIALS AND TREATMENT

After induction of glomerulonephritis by i.v. injection of a monoclonal anti-Thy1.1 antibody, rats were sacrificed at day 2, 6, 12 and 56. Changes in protein expression were detected by immunohistochemistry. Glomerular mRNA levels were analyzed by real time polymerase chain reaction (PCR).

RESULTS

In normal rat kidney, immunoreactivity of Cox-1 was detected predominantly in collecting duct cells and that of Cox-2 in the macula densa. Cox-1 staining showed a massive transient increase in diseased glomeruli at day 6, localized mainly to mesangial cells coinciding with cell proliferation, which also peaked at day 6. Upregulation of Cox-1 was also evident at the mRNA level (4 fold). Cox-2 expression in the macula densa region transiently increased at day 6, but no significant upregulation of Cox-2 was observed in glomerular cells at any time point. Prostaglandin E2 receptor EP2 mRNA and protein were detected in rat glomeruli. EP2 immunoreactivity was prominent on podocytes in normal rats while at day 6 of the disease also mesangial cells stained positive. In biopsies of patients with IgA nephritis, predominant expression of Cox-1, but not Cox-2, was found in glomeruli, whereas Cox-2 was strongly expressed in infiltrating interstitial cells.

CONCLUSIONS

The upregulation of glomerular Cox-1 but not Cox-2 and the parallel induction of the EP-2 receptor, which was shown to mediate cAMP accumulation in mesangial cells, suggest that induction of prostaglandin formation may contribute to the resolution rather than to the progression of anti-Thy1.1 nephritis. The expression pattern of Cox-1 and Cox-2 in human IgA nephritis points to a role for both Cox isoforms in human glomerular inflammation.

An anti-CD5 monoclonal antibody ameliorates proteinuria and glomerular lesions in rat mesangioproliferative glomerulonephritis

BACKGROUND

Increased numbers of lymphocytes have been identified in biopsy specimens of human mesangial proliferative glomerulonephritis (GN). However, the causal relationship between infiltrating T lymphocytes and mesangial changes in mesangial proliferative GN has not been previously evaluated. In this study, we elucidated the role of lymphocytes in the development of mesangial proliferative GN.

METHOD

Immunohistological and flow cytometric analyses as well as a reverse transcription-polymerase chain reaction (RT-PCR) studies were performed in monoclonal antibody (mAb) 1-22-3-induced Thy 1.1 GN. To elucidate the role of these lymphocytes, depletion studies were carried out using anti-CD8 mAb (OX-8), which depletes both CD8+ T lymphocytes and natural killer (NK) cells and anti-CD5 mAb (OX-19), which depletes both CD4+ and CD8+ T lymphocytes.

RESULTS

Immunofluorescence (IF) studies revealed that NK cells and CD4+ T lymphocytes were recruited into glomeruli. Glomerular mRNA expression for interferon-gamma, interleukin-2 (IL-2), IL-10, and perforin increased after induction of GN. Increased expressions of several chemokines, which have the potential to attract lymphocytes, were also detected. Anti-CD8 mAb treatment completely prevented the recruitment of NK cells; however, it had no protective effect on proteinuria and mesangial injury. By contrast, anti-CD5 mAb treatment suppressed the recruitment of CD4+ T lymphocytes into glomeruli and reduced proteinuria (60.4 +/- 25.7 vs. 120.0 +/- 32.3 mg/day, P < 0.05) and mesangial changes evaluated by total number of cells in glomeruli (63.2 +/- 6.0 vs. 81.4 +/- 5.9, P < 0.01) and alpha-smooth muscle actin staining score (1.4 +/- 0.2 vs. 2.2 +/- 0. 4, cf2eth P < 0.01) on day 14 after induction of GN. mRNA expression for IL-2 was significantly reduced by OX-19 treatment.

CONCLUSION

T lymphocytes participate in the development of mesangial proliferative GN.

Stimulation of thymocyte proliferation by phosphorothioate DNA oligonucleotides

DNA is a complex macromolecule the immunological properties of which depend on short sequence motifs called CpG motifs or immunostimulatory sequences (ISS). These sequences are mitogenic for B cells and can stimulate macrophage cytokine production. While these sequences do not directly activate T cells, they can augment effects of stimulation via the TCR. Furthermore, ISS can affect T cells because of macrophage production of IL-12 and IFN-alpha/beta. In these studies, we further evaluated the immune effects of DNA on T cells, testing the possibility that certain T cell populations can respond directly to this stimulus. We therefore tested the in vitro responses of thymocytes to a series of phosphodiester (Po) and phosphorothioate (Ps) oligonucleotides (ODNs) varying in sequence. In in vitro cultures, phosphorothioate ODNs (sODNs) containing CpG motifs induced significant proliferation of murine thymocytes, although phosphodiester compounds lacked activity. The magnitude of stimulation varied with sequences flanking the CpG motifs, as both dA and dT sequences enhanced the stimulatory capacity of the CpG motif. Furthermore, CpG sODNs were strong costimulators of anti-CD3-mediated thymocyte activation, increasing proliferation compared to anti-CD3 in the absence of DNA. This activation was only partially inhibited by cyclosporine A and was not dependent on a calcium influx. Together, these results indicate that phosphorothioate oligonucleotides containing CpG motifs can directly induce thymocyte proliferation as well as augment TCR activation. These observations thus extend the range of actions of CpG DNA and suggest additional mechanisms for its function as an immunomodulatory agent or adjuvant.