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M R Daha

Publications and source records attributed to M R Daha.

At least 19 recordsLinked to original sources
PubMed2000

The effect of calcineurin inhibitors and corticosteroids on the differentiation of human dendritic cells.

Corticosteroids and the calcineurin inhibitors cyclosporin A (CsA) and FK506 have been studied extensively regarding their effects on T lymphocytes, but their effects on dendritic cells (DC) are relatively unknown. Monocytes are one of the precursors of DC that differentiate into CD14-CD1a+ immature DC upon culture with IL-4 and GM-CSF. The presence of CsA or FK506 during differentiation did not affect DC development. In contrast, the presence of corticosteroids, either dexamethasone (Dex) or prednisolone (Pred), for as little as the first 48 h of culture blocked the generation of immature DC. Dex-DC were unresponsive to signals inducing maturation (CD40 ligand, lipopolysaccharide), as demonstrated by the absence of CD83, CD80/CD86 and HLA-DR up-regulation and their strongly reduced T cell stimulatory capacity. Furthermore, Dex-DC showed a decreased CD40 ligand-induced IL-6 and TNF-alpha production, a complete block in IL-12p40 production, while IL-10 production was unaffected. CsA-DC and FK506-DC showed a partial reduction in the production of TNF-alpha, whereas all other functional activities appeared to be similar to control DC. These data show that, when compared to calcineurin inhibitors, corticosteroids have a unique and profound inhibitory effect on the generation and function of DC.

Antigens, CD↗
PubMed2000

Distinctive roles of neutrophils and monocytes in anti-thy-1 nephritis.

Anti-Thy-1.1 glomerulonephritis as an experimental model for mesangial proliferative glomerulonephritis was induced in Wistar rats by a single injection of monoclonal IgG2a-anti-Thy-1.1 antibody (ER4G). This transient model is complement-mediated and leads to mesangial-cell (MC) lysis followed by MC proliferation, glomerular microaneurysm formation, glomerular influx of polymorphonuclear leukocytes (PMNs) and macrophages, proteinuria, and hematuria. In this study we investigated the distinctive roles of infiltrating PMNs or monocytes/macrophages by treating rats with an antibody against rat integrin CD11b/CD18 (ED7) or by depletion of monocytes with multilamellar clodronate liposomes, respectively. ED7 administration resulted in reduction of the influx of PMNs in glomeruli during the first 6 days after induction of Thy-1.1 nephritis, whereas treatment with an isotype-matched irrelevant antibody (PEN9) or with phosphate-buffered saline had no effect on macrophage influx. Increased glomerular C3 and C6 deposition on days 1 and 3 was seen in the ED7-treated rats but not seen in the control groups. In addition, the ED7-treated group showed an increased number of aneurysmatic glomeruli and more severe hematuria. Monocyte/macrophage depletion led to a significant reduction of mesangial matrix expansion, although mesangial proliferation, proteinuria, and hematuria remained unaltered. These results, together with the known effects of PMN-derived enzymes on C3 cleavage, suggest that a reduction in the influx of PMNs results in sparing of C3 and consequently of more complement activation in the glomerulus with increased complement-mediated damage. Our data indicate that infiltrating PMNs and monocytes/macrophages play distinctive roles during inflammation in this model of MC glomerulonephritis.

Animals↗
PubMed2000

A possible role of CD46 for the protection in vivo of human renal tumor cells from complement-mediated damage.

It is still unclear which membrane-bound regulatory proteins (mCRP) are important in vivo to protect tumor cells from complement-mediated damage. To address this question, the expression levels of CD46, CD55, and CD59 were measured semi-quantitatively in situ on renal cell carcinomas and compared with the expression level and cellular distribution of these mCRP in proximal tubuli within each patient (n = 31). It was also determined whether the expression of mCRP on tumor cells is associated with deposition of C3d and C5b-9. CD46 expression was decreased on tumor cells; in contrast, CD55 was expressed on tumor cells (12 out of 31 samples), while it was not detected on proximal tubular epithelial cells (PTEC). Also, expression of CD59 on tumor cells was increased as compared with its expression on PTEC. Furthermore, the localization on the cell surface of mCRP as observed on PTEC was altered on tumor cells. Because expression of mCRP may limit a complement-mediated anti-tumor response, we determined whether complement deposition was associated with the expression level of CD46, CD55, and CD59. The presence of C3d on tumor cells was associated with a low expression level of CD46 (p < 0.02). The expression level of CD46 was also associated with a low tumor stage (p < 0.04). The results suggest that in vivo CD46 plays a role in the protection of human renal tumor cells from complement-mediated injury.

Antigens, CD↗
PubMed2000

The role of Fcgamma receptor polymorphisms and C3 in the immune defence against Neisseria meningitidis in complement-deficient individuals.

Individuals with either a late (C5-9) complement component deficiency (LCCD) or properdin deficiency are at increased risk to develop meningococcal disease, often due to serogroups W135 and Y. Anti-meningococcal defence in both LCCD persons and properdin-deficient individuals without bactericidal antibodies depends mainly on phagocytosis. Three types of opsonin receptors are involved in phagocytosis by polymorphonuclear cells (PMN). These represent the polymorphic FcgammaRIIa (CD32) and FcgammaRIIIb (CD16b) receptors, and the C3 receptor CR3 (CD11b/CD18). When the distribution of FcgammaRIIa and FcgammaRIIIb allotypes was assessed in 15 LCCD and in 15 properdin-deficient patients with/without previous meningococcal disease, we found the combination of FcgammaRIIa-R/R131 with FcgammaRIIIb-NA2/NA2 allotypes to be associated with previous meningococcal disease (odds ratio 13.9, Fisher's test P = 0.036). No such relation was observed in the properdin-deficient patients. The importance of FcgammaRIIa allotypes was also demonstrated using in vitro phagocytosis assays. PMN from FcgammaRIIa-R/R131 homozygous donors internalized IgG2 opsonized meningococci W135 significantly (P < 0.05) less than PMN from FcgammaRIIa-H/H131 donors. When properdin-deficient serum was tested, it was observed that reconstitution with properdin resulted in enhanced PMN phagocytosis of the W135 meningococci (P = 0.001). This enhanced phagocytosis was parallelled by an increase in C3 deposition onto the opsonized meningococci W135 (r = 0.6568, P = 0. 01). We conclude that the occurrence of meningococcal disease in LCCD patients is associated with certain FcgammaR allotypes. Properdin-deficient individuals are susceptible to meningococcal disease because of an insufficient C3 deposition on the surface of meningococci, resulting in insufficient phagocytosis.

Adolescent↗
PubMed2000

Synthesis of complement components C3 and factor B in human keratinocytes is differentially regulated by cytokines.

The complement system plays an important part in host defense and inflammation. Locally synthesized complement may perform these functions at tissue and organ level. In skin the keratinocyte is the major cell type, it is known to produce two soluble complement components, C3 and factor B. In this study we investigated the regulation of synthesis of these components in foreskin keratinocytes by cytokines. Human keratinocytes were cultured in the presence of supernatant of activated peripheral blood mononuclear cells, interleukin-1alpha, interleukin-2, interleukin-6, transforming growth factor-beta1, tumor necrosis factor-alpha, or interferon-gamma. C3 and factor B proteins were measured in culture supernatant by enzyme-linked immunosorbent assay and C3 and factor B transcripts in harvested cells by reverse transcriptase-polymerase chain reaction. Cultured keratinocytes constitutively produced C3 and factor B. Supernatant of activated mononuclear cells upregulated C3 and factor B production by 27- and 15-fold, respectively. interleukin-1alpha, interferon-gamma, and tumor necrosis factor-alpha upregulated C3 synthesis by 7-, 8-, and 22-fold, and interleukin-1alpha, interleukin-6, and interferon-gamma upregulated factor B synthesis by 3-, 3-, and 34-fold, respectively. Tumor necrosis factor-alpha induced production of C3 and interferon-gamma induced production of factor B were inhibited by cycloheximide. Cytokine induced upregulation of C3 and factor B proteins was always associated with the upregulation of levels of C3 and factor B mRNA. This indicated that, as expected, cytokine-induced enhancement in C3 and factor B levels was due to an increase in synthesis rather than their possible release from intracellular stores. In conclusion, synthesis of C3 and factor B in keratinocytes is regulated by some cytokines, known to be produced by inflammatory cells and keratinocytes.

Cells, Cultured↗
PubMed2000

Combined glomerular deposition of polymeric rat IgA and IgG aggravates renal inflammation.

BACKGROUND: IgA nephropathy (IgAN) is characterized by deposition in the glomerular mesangium of IgA together with C3, C5b-9, and properdin. IgG deposition as a risk factor in IgAN was recently confirmed by a long-term follow-up of patients with IgAN. We previously reported on an acute model of IgA-mediated glomerular inflammation in Wistar rats. METHODS: To investigate the effect of the combination of IgA and IgG on glomerular injury, Wistar rats were injected with a minimum dose of rat IgG in the presence or absence of a subnephritogenic dose of polymeric rat IgA. Subsequently, glomerular complement activation, influx of inflammatory cells, proteinuria, and hematuria were assessed. RESULTS: Administration of IgG to the rats resulted in maximal proteinuria of 20.3 +/- 12.1 mg/24 h on day 2 and an absence of overt glomerular inflammation. Administration of polymeric rat IgA antibodies to rats resulted in hematuria with a moderate mesangial complement deposition. In the combination group, however, glomerular deposition of C5b-9 was dramatically increased. This was accompanied by increased proteinuria as compared with rats receiving IgA or IgG antibody injections alone on day 7. Microhematuria occurred in rats receiving either polymeric rat IgA or IgG alone or the combination. While both rat IgG and polymeric IgA induced minor mesangial cell (MC) proliferation and MC lysis, the combination resulted in a pronounced, significant increased percentage of aneurysm formation on day 7 after injection. CONCLUSIONS: We conclude that in this model of IgA-induced glomerulopathy, a selective, complement-dependent glomerular inflammation is induced in Wistar rats by glomerular codeposition of rat isotypic monoclonal antibodies.

Animals↗
PubMed2000

Xenotransplantation: in vitro analysis of synthetic alpha-galactosyl inhibitors of human anti-Galalpha1-->3Gal IgM and IgG antibodies.

Pig-to-human xenotransplantation might be an option to overcome the increasing shortage of human donor organs. However, naturally occurring antibodies in human blood against the Galalpha1-->3Gal antigen on pig endothelial cells lead to hyperacute or, if prevented, acute or delayed vascular rejection of the pig graft. The purpose of this study was therefore to evaluate synthetic oligosaccharides with terminal Galalpha1-->3Gal to inhibit antigen-binding and cytotoxicity of anti-alphaGal antibodies against pig cells. Different oligosaccharides were synthesized chemically and by a combined chemico-enzymatic approach. These included monomeric di-, tri-, and pentasaccharides, a polyacrylamide-conjugate (PAA-Bdi), as well as di-, tetra-, and octamers of Galalpha1-->3Gal. All were tested for inhibitory activity by anti-alphaGal ELISA and complement-dependent cytotoxicity tests. PAA-Bdi was the best inhibitor of binding as well as cytotoxicity of anti-alphaGal antibodies. Monomeric oligosaccharides efficiently prevented binding of anti-alphaGal IgG, but less well that of anti-alphaGal IgM, with tri- and pentasaccharides showing a better efficacy than the disaccharide. The two trisaccharides Galalpha1-->3Galbeta1-->4GlcNAc and Galalpha1-->3Galbeta1-->3GlcNAc were equally effective. Oligomers of Galalpha1-->3Gal were more effective than monomers in blocking the binding of anti-alphaGal IgG. However, they could not block IgM binding, nor could they match the efficacy of PAA-Bdi. We conclude that oligosaccharides with terminal Galalpha1-->3Gal, most effectively as PAA-conjugates, can prevent binding and cytotoxicity of human anti-alphaGal in vitro. The PAA-Bdi conjugate might be most suited for use as a Sepharose-bound immunoabsorption material.

Animals↗
PubMed1999

Crosslinking of the human Fc receptor for IgA (FcalphaRI/CD89) triggers FcR gamma-chain-dependent shedding of soluble CD89.

CD89/FcalphaRI is a 55- to 75-kDa type I receptor glycoprotein, expressed on myeloid cells, with important immune effector functions. At present, no information is available on the existence of soluble forms of this receptor. We developed an ELISA for the detection of soluble CD89 (sCD89) forms and investigated the regulation of sCD89 production. PMA/ionomycin stimulation of monocytic cell lines (U937, THP-1, and MM6), but not of neutrophils, resulted in release of sCD89. Crosslinking of CD89 either via its ligand IgA or with anti-CD89 mAbs similarly resulted in sCD89 release. Using CD89-transfected cells, we showed ligand-induced shedding to be dependent on coexpression of the FcR gamma-chain subunit. Shedding of sCD89 was dependent on signaling via the gamma-chain and prevented by addition of inhibitors of protein kinase C (staurosporine) or protein tyrosine kinases (genistein). Western blotting revealed sCD89 to have an apparent molecular mass of 30 kDa and to bind IgA in a dose-dependent fashion. In conclusion, the present data document a ligand-binding soluble form of CD89 that is released upon activation of CD89-expressing cells. Shedding of CD89 may play a role in fine-tuning CD89 immune effector functions.

Antigens, CD↗
PubMed1999

Immunoglobulin M-enriched human intravenous immunoglobulin prevents complement activation in vitro and in vivo in a rat model of acute inflammation.

An important antiinflammatory mechanism of intravenous immunoglobulin preparations (IVIG) is their ability to block complement activation. The purpose of this study was to compare the complement-inhibitory activity of four IVIG preparations differing in isotype composition. The preparations were: (1) IVIgG (48 g/L IgG, 2 g/L IgA; Intraglobin F); (2) Pentaglobin (38 g/L IgG, 6 g/L IgM, 6 g/L IgA); (3) IVIgM (35 g/L IgM, 12 g/L IgA, 3 g/L IgG); and (4) IVIgA (41 g/L IgA, 9 g/L IgG), all from Biotest Pharma GmbH, Dreieich, Germany. Their complement inhibitory activity was assessed in vitro by measurement of the blocking of C1q-, C4-, and C3 deposition on solid-phase aggregated rabbit IgG by enzyme-linked immunosorbent assay (ELISA). Complement inhibition in this ELISA was best for IVIgM, followed by Pentaglobin and IVIgG; IVIgA did not exhibit an inhibitory effect. Control experiments with excess concentrations of C1q as well as with C1q-depleted serum showed that the inhibitory effects of IVIG were not caused by complement activation and thus, consumption, but that C4 and C3 were scavenged by IgM and to a lesser extent by IgG. These results were confirmed in vivo in the rat anti-Thy 1 nephritis model, in which a single dose of 500 mg/kg of IVIgM prevented C3-, C6-, and C5b-9 deposition in the rat glomeruli, whereas the effect of IVIgG was much less pronounced. Reduction of complement deposition was paralleled by a diminished albuminuria, which was completely absent in the IVIgM-treated rats. IVIgM and to a lesser extent IVIgG also prevented rat C3 deposition on cultured rat glomerular mesangial cells in vitro, but did not influence anti-Thy 1 binding. Neither IVIgM nor Pentaglobin nor IVIgG negatively affected in vitro phagocytosis of Escherichia coli (E coli) by human granulocytes. In conclusion, we have shown that IgM enrichment of IVIG preparations enhances their effect to prevent the inflammatory effects of complement activation.

Animals↗
PubMed1999

Transforming growth factor-beta isoforms regulate the surface expression of membrane cofactor protein (CD46) and CD59 on human keratinocytes [corrected].

We studied the regulation of the expression of complement regulatory proteins, membrane cofactor protein (MCP), decay accelerating factor (DAF) and CD59, on human keratinocytes by supernatant of activated mononuclear cells and by some individual cytokines present therein. Cultured keratinocytes expressed MCP, DAF and CD59. Supernatant of activated mononuclear cells and recombinant forms of transforming growth factor (TGF)-beta variants (beta1, beta2 and beta3) up-regulated MCP and CD59 but not DAF. Recombinant IL-1alpha, IL-2, IL-6, TNF-alpha and IFN-gamma had no influence. TGF-beta present in the supernatant was likely responsible for up-regulation of MCP and CD59. A monoclonal anti-TGF-beta antibody, which neutralized TGF-beta1, -beta2 and -beta3, did not inhibit the up-regulation of MCP and CD59 by the supernatant. These results indicated that TGF-beta and an additional factor(s) present in the supernatant may be responsible for up-regulating the expression of MCP and CD59 on keratinocytes; both may be acting non-synergistically.

Antigens, CD↗
PubMed1999

Miller Fisher anti-GQ1b antibodies: alpha-latrotoxin-like effects on motor end plates.

In the Miller Fisher syndrome (MFS) variant of the Guillain-Barré syndrome, weakness is restricted to extraocular muscles and occasionally other craniobulbar muscles. Most MFS patients have serum antibodies against ganglioside type GQ1b of which the pathophysiological relevance is unclear. We examined the in vitro effects of MFS sera, MFS IgG, and a human monoclonal anti-GQ1b IgM antibody on mouse neuromuscular junctions (NMJs). It was found that anti-GQ1b antibodies bind at NMJs where they induce massive quantal release of acetylcholine from nerve terminals and eventually block neuromuscular transmission. This effect closely resembled the effect of the paralytic neurotoxin alpha-latrotoxin at the mouse NMJs, implying possible involvement of alpha-latrotoxin receptors or associated downstream pathways. By using complement-deficient sera, the effect of anti-GQ1b antibodies on NMJs was shown to be entirely dependent on activation of complement components. However, neither classical pathway activation nor the formation of membrane attack complex was required, indicating the effects could be due to involvement of the alternative pathway and intermediate complement cascade products. Our findings strongly suggest that anti-GQ1b antibodies in conjunction with activated complement components are the principal pathophysiological mediators of motor symptoms in MFS and that the NMJ is an important site of their action.

Animals↗
PubMed1999

C1q autoantibodies in HIV infection: correlation to elevated levels of autoantibodies against 60-kDa heat-shock proteins.

Antibodies to solid phase C1q (C1qAb) were determined in 295 serum samples from 132 HIV-infected subjects and in sera from 140 HIV-seronegative healthy individuals as control. An ELISA method applied for the determination of C1qAb in other diseases was used. In part of these sera, other autoantibodies (antibodies reacting with 60-kDa human heat shock protein (hsp60) or mycobacterial hsp65; IgA and IgG class antibodies against the Fab and F(ab')2 moieties of IgG) as well as complement-mediated antibody-dependent enhancement/neutralization (C'-ADE) were also determined. Increased amount of C1qAb was found in HIV-infected subjects as compared with HIV-seronegative controls (P = 0.0138). In 17 of 132 (13.0%) seropositive individuals but only in 7/140 (5.0%) samples from the controls, the amount of C1qAb exceeded the upper limit (95th percentile) of the normal values (P = 0.031). The amount of C1qAb significantly decreased during a follow-up period of 65 months. C1qAb levels were found to strongly correlate to hsp60/65 autoantibodies but did not correlate or only weakly correlated to the amount of anti-Fab or anti-F(ab')2 autoantibodies measured in the same serum samples. Anti-C1q antibodies recognized the solid phase hsp60/65. Three predicted epitope regions of M. paratuberculosis hsp65 were able to bind efficiently C1q antibodies. An inverse correlation was found between C1qAb and C'-ADE, neutralization was more frequent in the sera with detectable C1qAb, whereas sera without C1qAb more likely enhanced HIV infection in vitro.

Antigens, Bacterial↗
PubMed1999

Sequential development of anti-GBM nephritis and ANCA-associated Pauci-immune glomerulonephritis.

The medical history is presented of a 23-year-old man experiencing three episodes of pulmonary-renal syndrome. On the first occasion, a diagnosis of anti-glomerular basement membrane (GBM) disease (with linear deposition of immunoglobulin G [IgG] along the GBM) was made, whereas anti-neutrophil cytoplasmic autoantibodies were also present in serum. On the third occasion, 5 years later, p-ANCA-associated vasculitis (with pauci-immune crescentic glomerulonephritis) was diagnosed, whereas anti-GBM antibodies were absent. The current literature on ANCA-positive anti-GBM disease is briefly reviewed. A substantial proportion (20% to 30%) of patients with histologically and serologically proven anti-GBM nephritis display the presence of ANCA as well. In this group of patients with dual antibodies, clinical and histological findings suggest that ANCA are not merely epiphenomena, but are of pathogenetic importance and might be responsible for an initial vasculitic insult to the kidney with resultant secondary anti-GBM nephritis. The clinical course in our patient lends further support to this concept. Histological demonstration of anti-GBM nephritis followed by ANCA-associated pauci-immune glomerulonephritis in a single patient has not been reported before.

Adult↗
PubMed1999

Hyperacute rejection in the guinea pig-to-rat model without formation of the membrane attack complex.

The guinea pig (GP)-to-rat transplantation model has been widely used to study hyperacute rejection (HAR) of xenografts. In this model heart graft survival beyond 8 days has never been reported. In contrast, survival times of kidney and heart grafts up to 62 days have been reported in the discordant pig-to-primate model. It is not clear why it is so much more difficult to obtain long-term graft survival in the GP-to-rat model as compared to the pig-to-primate model. We hypothesized that mechanisms other than activation of complement may be involved in the rejection of guinea pig grafts by rat recipients. Therefore, we have studied in detail the rejection of GP aortic grafts by rat recipients, either PVG/c+ (complement competent, group 1), or PVG/c- (complement C6 deficient, group 2). PVG/c- rats are not able to form the membrane attack complex (MAC) of complement. Forty-four GP-to-rat aortic transplantations were performed successfully. Recipient rats were sacrificed at various intervals after transplantation (4, 24 and 48 h, and 7 and 28 days, three to six animals per time point per group). Twenty-four hours after transplantation the number of cells in the media was significantly decreased from 11.1 +/- 0.9 cells/mm2 to 3.1 +/- 2.8 cells/mm2 in group 1, whereas the number of medial cells in group 2 remained the same. The number of medial cells was significantly decreased in both groups at 48 h post-transplantation (group 1: 1.8 +/- 2.2 cells/mm2; group 2: 5.5 +/- 3.0 cells/mm2). At that time no infiltrating cells were apparent in the grafts of either two groups. Seven days after transplantation, the number of medial cells remained low in group 1 (1.8 +/- 2.9 cells/mm2) but was increased in group 2 (10.7 +/- 2.6 cells/mm2) as a consequence of infiltrating immune cells. These infiltrating cells consisted mainly of macrophages, but also T cells and NK cells. At 28 days after transplantation the grafts in both groups were completely reorganized and no distinction could be made between media and adventitia. These results show that rejection of GP grafts by rat recipients can occur in the absence of both MAC of complement and immune competent cells. This MAC and immune cells independent type of rejection has not been described before and may explain the difficulty in obtaining long-term graft survival in the GP-to-rat xenotransplantation model.

Acute Disease↗
PubMed1999

Combined administration of IgA and IgG anti-Thy-1 antibodies enhances renal inflammation in rats.

BACKGROUND: IgA nephropathy (IgAN) is the most common type of immunologically mediated glomerulonephritis (GN) and is characterized by deposition in the glomerular mesangium of IgA together with C3, C5b-9, and properdin. In patients, the codeposition of IgA together with IgG and/or IgM can lead to a more progressive course of disease. In Wistar rats, mesangial proliferative GN can be induced by the injection of mouse IgG anti-Thy-1 antibodies (ER4G). In contrast, the administration of mouse IgA anti-Thy-1 antibodies (ER4A) to rats results in isolated hematuria without detectable albuminuria and without detectable complement deposition. METHODS: To investigate the effect of the combination of IgA and IgG on glomerular injury, Wistar rats were injected with a limiting dose of ER4G in the presence or absence of ER4A in a dose able to induce hematuria. RESULTS: Although the limiting dose of ER4G or the dose of ER4A used did not induce significant albuminuria, the combination of ER4G and ER4A resulted in a synergistic increase in albuminuria. Microhematuria occurred in rats receiving either ER4A or ER4G alone or in combination. Although both ER4A or a limiting dose of ER4G induced minor increases in extracellular matrix expansion, the combination resulted in a pronounced, additive increased matrix expansion. CONCLUSION: We conclude that in this model of IgA-mediated glomerulopathy, a selective complement-dependent synergistic renal injury is induced in Wistar rats by glomerular codeposition of mouse anti-Thy-1 monoclonal isotypes.

Animals↗
PubMed1999

Synergistic effect of interleukin-1 and CD40L on the activation of human renal tubular epithelial cells.

BACKGROUND: Renal tubular epithelial cells are a central cell type in tubulointerstitial inflammation because they can produce inflammatory mediators such as cytokines and chemokines. Several signals derived from either monocytes or activated T cells have been reported to regulate the activation of tubular epithelial cells. We studied this regulation in more detail by combined treatment with CD40 ligand and the proinflammatory cytokine interleukin-1 (IL-1) in vitro. METHODS: The regulation of cytokine and chemokine production was studied in primary cultures of human proximal tubular epithelial cells (PTECs). PTECs were activated by coculture with CD40L-transfected murine fibroblasts in combination with recombinant human cytokines. The production of IL-6, IL-8, monocyte chemoattractant protein-1 (MCP-1), and RANTES were measured by specific enzyme-linked immunosorbent assay. RESULTS: The combined activation of PTECs with CD40L and IL-1 resulted in strong synergistic effects on the production of IL-6, IL-8, and RANTES, whereas only an additive stimulation of MCP-1 production was observed. The effects were specific for IL-1 and could be neutralized by the addition of the IL-1R antagonist. Both IL-1alpha and IL-1beta showed similar effects on cytokine production by PTECs. The effects of IL-1 were dose dependent, and kinetic experiments showed that synergistic effects were observed after 24 hours of activation and remained present for at least five days. Reverse transcription-polymerase chain reaction analysis showed that human PTECs could express both IL-1alpha and IL-1beta. The activation of PTECs with IL-1 resulted in an up-regulation of CD40 expression on these cells. CONCLUSIONS: A complex network of regulation exists for the production of cytokines and chemokines by PTECs. The combined treatment results in strong synergistic effects on IL-6, IL-8, and RANTES production. This strengthens the potential role of tubular epithelial cells in inflammatory responses within the kidney.

Animals↗