Renal fibrosis and the origin of the renal fibroblast.
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Animals↗
Biomedical subjects
Gerhard A Müller
Publications and source records attributed to Gerhard A Müller.
Regulation of steroid hormone biosynthesis enzymes and organic anion transporters by forskolin and DHEA-S treatment in adrenocortical cells.
Several important physiological functions are regulated by cortisol. Previously, we demonstrated the involvement of human organic anion transporter 3 (hOAT3) in cortisol release. In the present study, we investigated the influence of dehydroepiandrosterone sulfate (DHEA-S) and estrone sulfate on cortisol release in a human adrenocortical cell line (NCI-H295R) compared with forskolin stimulation. Additionally, we examined the impact of forskolin and DHEA-S on the expression of key enzymes in steroid biosynthesis and expression of hOAT3 and -4 in NCI-H295R cells. The cortisol release was increased 10-fold after 24-h incubation with DHEA-S, but incubation with estrone sulfate did not show any significant change in cortisol release. When cells were incubated with DHEA-S in the presence of forskolin, an additive influence of DHEA-S stimulation of cortisol was recorded over forskolin alone. The 24-h stimulation of NCI-H295R cells with forskolin increased the expression of steroidogenic acute regulatory protein (StAR), CYP17, CYP21A2, and CYP11A1, whereas only StAR mRNA expression was increased significantly by incubation with DHEA-S. Immunofluorescence analyses revealed strongly elevated expression of hOAT3 by forskolin as well as by DHEA-S stimulation. We conclude that the increased cortisol release of adrenocortical cells by DHEA-S and forskolin stimulation is probably due to high expression of the key enzymes of steroid biosynthesis and hOAT3.
Adrenal Cortex↗
Decrease in expression of bone morphogenetic proteins 4 and 5 in synovial tissue of patients with osteoarthritis and rheumatoid arthritis.
Bone morphogenetic proteins (BMPs) have been identified as important morphogens with pleiotropic functions in regulating the development, homeostasis and repair of various tissues. The aim of this study was to characterize the expression of BMPs in synovial tissues under normal and arthritic conditions. Synovial tissue from normal donors (ND) and from patients with osteoarthritis (OA) and rheumatoid arthritis (RA) were analyzed for BMP expression by using microarray hybridization. Differential expression of BMP-4 and BMP-5 was validated by semiquantitative RT-PCR, in situ hybridization and immunohistochemistry. Activity of arthritis was determined by routine parameters for systemic inflammation, by histological scoring of synovitis and by semiquantitative RT-PCR of IL-1beta, TNF-alpha, stromelysin and collagenase I in synovial tissue. Expression of BMP-4 and BMP-5 mRNA was found to be significantly decreased in synovial tissue of patients with RA in comparison with ND by microarray analysis (p < 0.0083 and p < 0.0091). Validation by PCR confirmed these data in RA (p < 0.002) and also revealed a significant decrease in BMP-4 and BMP-5 expression in OA compared with ND (p < 0.015). Furthermore, histomorphological distribution of both morphogens as determined by in situ hybridization and immunohistochemistry showed a dominance in the lining layer of normal tissues, whereas chronically inflamed tissue from patients with RA revealed BMP expression mainly scattered across deeper layers. In OA, these changes were less pronounced with variable distribution of BMPs in the lining and sublining layer. BMP-4 and BMP-5 are expressed in normal synovial tissue and were found decreased in OA and RA. This may suggest a role of distinct BMPs in joint homeostasis that is disturbed in inflammatory and degenerative joint diseases. In comparison with previous reports, these data underline the complex impact of these factors on homeostasis and remodeling in joint physiology and pathology.
Adult↗
Visualization of xenotransplanted human rhabdomyosarcoma after transfection with red fluorescent protein.
BACKGROUND/AIMS: Discosoma sp red fluorescent protein (DsRed2) is a newly developed marker for in vivo labeling studies in different biologic systems. After vector transfection, DsRed2 is expressed in mammalian cells and can be detected by fluorescence microscopy. The aims of this study were to establish a DsRed2-transfected human rhabdomyosarcoma (RMS) cell line and to perform a xenotransplantation on nude mice to use imaging as a tool for further basic research studies on this neoplasm. PROCEDURE: The human alveolar RMS cell line Rh30 was transfected with the pDsRed2-N1 vector by lipofection. The DsRed2-positive cells were sorted out by fluorescence-activated cell sorting analysis 96 hours after transfection and selected in culture with G418. Expression of DsRed2 messenger RNA was assessed using single-cell reverse transcriptase polymerase chain reaction after laser microdissection. Transfected and parental cells were characterized cytologically, cytogenetically, immunohistochemically, and in vivo after subcutaneous injection in NMRI (nu/nu) nude mice. RESULTS: After vector transfection, a pure and stable DsRed2-positive cell line was established by monoclonal growth of the cells. Reverse transcriptase polymerase chain reaction revealed constant expression of DsRed2 messenger RNA in fluorescencing cells. There was no difference between transfected and parental cells by means of cell morphology and desmin expression. Clonal cells (1 x 10(6)) were used for xenotransplantation. Tumors were visualized noninvasively through the skin of the mice using specific emission and excitation filters. Tumor vascularization and vessel growth could be discriminated from tumor tissue using this imaging system. CONCLUSION: This is the first report on successful transfection of an RMS cell line with red fluorescent protein followed by xenotransplantation into nude mice. This model can serve as an imaging tool for in vivo studies investigating tumor biology and metastases of human RMS.
Animals↗
Apolipoprotein A-IV predicts progression of chronic kidney disease: the mild to moderate kidney disease study.
It has not been established firmly whether dyslipidemia contributes independently to the progression of kidney disease. Lipid and lipoprotein parameters, including levels of total, HDL, and LDL cholesterol; triglycerides; lipoprotein(a); apolipoprotein A-IV; and the apolipoprotein E and A-IV polymorphisms, were assessed in 177 patients who had mostly mild to moderate renal insufficiency and were followed prospectively for up to 7 yr. Progression of kidney disease was defined as doubling of baseline serum creatinine and/or terminal renal failure necessitating renal replacement therapy. In univariate analysis, patients who reached a progression end point (n = 65) were significantly older and had higher serum creatinine and proteinuria as well as lower GFR and hemoglobin levels. In addition, baseline apolipoprotein A-IV and triglyceride concentrations were higher and HDL cholesterol levels were lower. Multivariate Cox regression analysis revealed that baseline GFR (hazard ratio 0.714; 95% confidence interval [CI] 0.627 to 0.814 for an increment of 10 ml/min per 1.73 m(2); P < 0.0001) and serum apolipoprotein A-IV concentrations (hazard ratio 1.062; 95% CI 1.018 to 1.108 for an increment of 1 mg/dl; P = 0.006) were significant predictors of disease progression. Patients with apolipoprotein A-IV levels above the median had a significantly faster progression (P < 0.0001), and their mean follow-up time to a progression end point was 53.7 mo (95% CI 47.6 to 59.8) as compared with 70.0 mo (95% CI 64.6 to 75.4) in patients with apolipoprotein A-IV levels below the median. For the apolipoprotein E polymorphism, only the genotype epsilon2/epsilon4 was associated with an increased risk for progression. In summary, this prospective study in patients with nondiabetic primary kidney disease demonstrated that apolipoprotein A-IV concentration is a novel independent predictor of progression.
Adult↗
Proteomic analysis of cellular response to osmotic stress in thick ascending limb of Henle's loop (TALH) cells.
Epithelial cells of the thick ascending limb of Henle's loop (TALH cells) play a major role in the urinary concentrating mechanism. They are normally exposed to variable and often very high osmotic stress, which is particularly due to high sodium and chloride reabsorption and very low water permeability of the luminal membrane. It is already established that elevation of the activity of aldose reductase and hence an increase in intracellular sorbitol are indispensable for the osmotic adaptation and stability of the TALH cells. To identify new molecular factors potentially associated with the osmotic stress-resistant phenotype in kidney cells, TALH cells exhibiting low or high levels of resistance to osmotic stress were characterized using proteomic tools. Two-dimensional gel analysis showed a total number of 40 proteins that were differentially expressed in TALH cells under osmotic stress. Twenty-five proteins were overexpressed, whereas 15 proteins showed a down-regulation. Besides the sorbitol pathway enzyme aldose reductase, whose expression was 15 times increased, many other metabolic enzymes like glutathione S-transferase, malate dehydrogenase, lactate dehydrogenase, alpha enolase, glyceraldehyde-3-phosphate dehydrogenase, and triose-phosphate isomerase were up-regulated. Among the cytoskeleton proteins and cytoskeleton-associated proteins vimentin, cytokeratin, tropomyosin 4, and annexins I, II, and V were up-regulated, whereas tubulin and tropomyosins 1, 2, and 3 were down-regulated. The heat shock proteins alpha-crystallin chain B, HSP70, and HSP90 were found to be overexpressed. In contrast to the results in oxidative stress the endoplasmic reticulum stress proteins like glucose-regulated proteins (GRP78, GRP94, and GRP96), calreticulin, and protein-disulfide isomerase were down-regulated under hypertonic stress.
Animals↗
A novel ultrasonographic synovitis scoring system suitable for analyzing finger joint inflammation in rheumatoid arthritis.
OBJECTIVE: To develop an ultrasonographic (US) synovitis scoring system suitable for evaluation of finger joint inflammation in patients with active rheumatoid arthritis (RA) and to compare semiquantitative US scoring with quantitative US measurements. METHODS: US was performed at the palmar and dorsal sides of the second through fifth metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints in 10 healthy subjects and in the clinically more affected hand in 46 RA patients. Ten patients additionally underwent magnetic resonance imaging (MRI). Synovitis was measured, standardized, and scored according to a semiquantitative method. The 2 methods (semiquantitative US scoring, quantitative US) were compared and statistical cutoffs were identified using receiver operating characteristic (ROC) curve analysis. MRI results were compared with semiquantitative US scoring and quantitative US results. The optimal US scoring method from 6 joint combinations was identified (ROC curve analysis). RESULTS: Synovitis was most frequently detected in the palmar proximal area (86% of affected joints). We found no significant differences between individual PIP joints or between individual MCP joints, indicating that all fingers within each of these joint groups should be treated equally for statistical calculations, although each joint group as a whole should be treated separately. The optimal cutoff point to distinguish between "health" and "pathology" was 0.6 mm both for MCP joints (sensitivity 94%, specificity 89%) and for PIP joints (sensitivity 90%, specificity 88%). There was no significant difference between semiquantitative US scores and quantitative US measurements. The best results for joint combinations were achieved using the "sum of 4 fingers" (second through fifth MCP and PIP joints) and "sum of 3 fingers" (second through fourth MCP and PIP joints) methods. Comparison of MRI results with semiquantitative US scores revealed high concordance. CONCLUSION: US evaluation of finger joint synovitis can be considerably simplified by focusing on the palmar side and by applying semiquantitative grading instead of quantitative measurements. For evaluation of treatment efficacy based on synovitis in RA patients, we recommend using the "sum of 3 fingers" method in longitudinal trials.
Adolescent↗
New trends in tumor biology: transfection of a human hepatoblastoma cell line with green fluorescent protein.
BACKGROUND/PURPOSE: Enhanced green fluorescent protein (eGFP) is widely used as a marker in different biologic systems. After vector transfection, eGFP is expressed by eukaryotic cells and can be visualized using fluorescent microscopy. The aim of this study was to establish an eGFP-transfected human hepatoblastoma (HB) cell line as tool for further basic research studies. METHODS: The HB cell line HUH6 was transfected with the pEGFP-N1 vector by liposomal transfection. Enhanced green fluorescent protein-positive cells were sorted out by fluorescence-activated cell sort and selected using G418 resistance. Expression of eGFP-messenger RNA was assessed by single-cell reverse transcriptase polymerase chain reaction after laser microdissection. Original and transfected cells were compared biologically and cytomorphologically. RESULTS: Vector transfection produced up to 15% eGFP-positive cells. After fluorescence-activated cell sort and G418 selection, a pure cell line was established with 100% eGFP-positive cells. Reverse transcriptase polymerase chain reaction revealed constant expression of eGFP-messenger RNA in fluorescending cells. Analysis of cell characteristics revealed no differences between transfected and original cells. CONCLUSIONS: For the first time, the authors established an eGFP-transfected HB cell line. This cell line can serve as a promising tool for further studies investigating HB in vitro and in vivo. Our model might also be a basis for similar work on other pediatric solid tumors.
Flow Cytometry↗
The antifibrotic effects of relaxin in human renal fibroblasts are mediated in part by inhibition of the Smad2 pathway.
BACKGROUND: The peptide hormone relaxin has been demonstrated to exert antifibrotic effects in renal and extrarenal tissues. The aims of this study were to identify potential anti-fibrotic effects of relaxin on human renal fibroblasts in vitro and to analyze their mechanisms. METHODS: All experiments were performed in established renal fibroblast cell lines and in primary cortical fibroblasts. Effects of relaxin were analyzed on cell proliferation, apoptosis, activation of renal fibroblasts, synthesis and secretion of collagen type I and fibronectin, as well as on the secretion of matrix metalloproteinases (MMPs). Effects on transforming growth factor-beta1 (TGF-beta1) receptor binding were analyzed by flow cytometry and on TGF-beta1 signal transduction by immunoblot analyses for Smad4 and 7, translocation from cytosol to nucleus for Smad2 and 3 as well as for phosphorylated and unphosphorylated forms of p38, c-Jun NH2 terminal kinase (JNK) and extracellular-regulated protein kinase (ERK). Finally, specific siRNAs for Smad2 and 3 were applied to assess the signal transduction pathway. RESULTS: After stimulation with relaxin, tyrosine phosphorylation of a 220 kD protein was demonstrated, indicating interaction with the receptor. Relaxin had only modest inhibitory effects on cell proliferation, and no effects on apoptosis. Conversely, relaxin exerted robust effects on TGF-beta1-induced fibroblast to myofibroblast transformation as well as on matrix synthesis and secretion even at the smallest dose tested. The secretion of MMP-2 and MMP-9 was induced noticeably by all investigated relaxin concentrations. TGF-beta1 receptor binding was not influenced by relaxin; however, it prevented Smad2 phosphorylation, translocation to nucleus, and complex formation between Smad2 and 3 indicating a possible interaction with TGF-beta1 signaling. These findings were corroborated by studies using siRNAs to Smad2 and 3 where siRNA to Smad2 but not to Smad3 inhibited the TGF-beta1 induction of fibronectin synthesis. There was no influence of relaxin on intracellular Smad3, Smad4, and Smad7 translocation or phosphorylation of mitogen-activated protein (MAP) kinases. CONCLUSION: Relaxin is a potent inhibitor of TGF-beta1-induced extracellular matrix (ECM) synthesis and secretion as well as fibroblast activation. Furthermore, it induces ECM degradation by induction of MMP-2 and MMP-9. These effects are mediated, at least in part, by inhibition of TGF-beta1 signaling.
Apoptosis↗
Contact activation in low-density lipoprotein apheresis systems.
BACKGROUND: Anaphylactoid reactions due to contact activation have been observed in patients on ACE inhibitor therapy and hemodialysis with negatively charged dialysis membranes. Negatively charged surfaces are functional constituents of different LDL apheresis systems. Therefore, contact activation was investigated during LDL apheresis with three different systems: (i) heparin-induced extracorporeal LDL precipitation (HELP); (ii) dextran sulfate cellulose (DSC) columns; and (iii) modified polyacrylate gels (DALI) in a clinical setting. METHODS: 24 prevalent patients on regular LDL apheresis treatment were included in the study. Bradykinin, prekallikrein, and HMW kininogen were measured during a single LDL apheresis at different sites of the systems. RESULTS: LDL apheresis with DSC and DALI was associated with an extreme release of bradykinin after the passage of plasma or blood through the LDL adsorbers as well as with a decrease of prekallikrein and HMW kininogen during the course of the treatment. Bradykinin release exceeded the degradation capacity of the kininase II, since markedly elevated bradykinin concentrations were observed in the arterial line of the extracorporeal circuits of both systems. This was not associated with anaphylactoid reactions. In contrast to the treatments with DSC and DALI, the HELP system did not lead to any activation of the kallikrein-kinin system. CONCLUSION: From our data we conclude that angiotensin converting enzyme (ACE) inhibitors are contraindicated in patients on LDL apheresis with the DSC and the DALI system. Because the HELP system does not activate the kallikrein-kinin system, patients who need ACE inhibitors are predisposed for this LDL apheresis procedure.
Acrylic Resins↗
Lysine 3 acetylation regulates the phosphorylation of yeast 6-phosphofructo-2-kinase under hypo-osmotic stress.
N-terminal acetylation in the yeast Saccharomyces cerevisiae is catalysed by any of three N-terminal acetyltransferases (NAT), NatA, NatB, and NatC, which contain the catalytic subunits Ard1p, Nat3p and Mak3p, respectively. Yeast 6-phosphofructo-2-kinase (PFK2) was found to be acetylated at the amino acid lysine 3. The Lys3-Arg mutant was not acetylated and the mutation causes a slight decrease in enzyme activity. PFK2 from yeast cells exposed to hypo-osmotic stress is known to be phosphorylated at Ser8 and Ser652 (Dihazi et al., 2001a). We have taken a mass spectrometric approach to investigate the influence of PFK2 acetylation on its phosphorylation. Wild-type PFK2 and the Lys3-Arg mutant were purified from hypo-osmotically stressed cells and analysed with MALDI-TOF MS for phosphorylation. Wild-type PFK2 without any tag sequence was found to be acetylated and two times phosphorylated at the N-terminal peptide T(1-40) carrying the acetylation. The same results were observed with C-terminally His-tagged PFK2. When the His-tag was added to the N-terminus of the protein PFK2, acetylation was found to be incomplete and only one phosphate was incorporated in the peptide T(1-41). The Lys3-Arg mutant of PFK2 was not at all post-translationally modified at the N-terminal peptide. Our data indicate that Lys3 acetylation affects the N-terminal phosphorylation of PFK2 under hypo-osmotic stress.
Acetylation↗
Presence of organic anion transporters 3 (OAT3) and 4 (OAT4) in human adrenocortical cells.
Since the organic anion transporter-1 (OAT1) has been implicated in cortisol release from bovine and rat adrenal zona fasciculata cells, we addressed the question of whether OATs are present in human adrenal cortical cells. In the human adrenal cell line NCI-H295R, 24-h cortisol secretion increased up to 30-fold on exposure to forskolin. Incubation of forskolin-treated cells for 24 h with the OAT substrates probenecid, p-aminohippurate (PAH), glutarate or cimetidine inhibited cortisol release partly. RT-PCR did not reveal expression of human OAT1 and OAT2, but OAT3 and OAT4 mRNAs were detected in both NCI-H295R cells and human adrenal tissue. When human OAT3 (hOAT3) and hOAT4 were expressed in Xenopus laevis oocytes, only hOAT3 showed [3H]cortisol uptake in excess of that of water-injected control oocytes. Cortisol uptake via OAT3 was saturable with an apparent Kt of 2.4 microM. In NCI-H295R cells, [3H]estrone sulphate uptake was saturable, cis-inhibited by OAT substrates and trans-stimulated by preloading with glutarate or cortisol. Likewise, [3H]PAH uptake was cis-inhibited by estrone sulphate and trans-stimulated by preloading the cells with PAH, glutarate or cortisol, indicating functional expression of OATs in the plasma membrane of NCI-H295R cells.
Adrenal Cortex↗
Transforming growth factor-beta1 stimulates collagen matrix remodeling through increased adhesive and contractive potential by human renal fibroblasts.
Renal tubulointerstitial fibrosis is the common final pathway leading to end-stage renal failure. Tubulointerstitial fibrosis is characterized by fibroblast proliferation and excessive matrix accumulation. Transforming growth factor-beta1 (TGF-beta1) has been implicated in the development of renal fibrosis accompanied by alpha-smooth muscle actin (alpha-SMA) expression in renal fibroblasts. To investigate the molecular and cellular mechanisms involved in tubulointerstitial fibrosis, we examined the effect of TGF-beta1 on collagen type I (collagen) gel contraction, an in vitro model of scar collagen remodeling. TGF-beta1 enhanced collagen gel contraction by human renal fibroblasts in a dose- and time-dependent manner. Function-blocking anti-alpha1 or anti-alpha2 integrin subunit antibodies significantly suppressed TGF-beta1-stimulated collagen gel contraction. Scanning electron microscopy showed that TGF-beta1 enhanced the formation of the collagen fibrils by cell attachment to collagen via alpha1beta1 and alpha2beta1 integrins. Flow cytometry and cell adhesion analyses revealed that the stimulation of renal fibroblasts with TGF-beta1 enhanced cell adhesion to collagen via the increased expression of alpha1 and alpha2 integrin subunits within collagen gels. Fibroblast migration to collagen was not up-regulated by TGF-beta1. Furthermore, TGF-beta1 increased the expression of a putative contractile protein, alpha-SMA, by human renal fibroblasts in collagen gels. These results suggest that TGF-beta1 stimulates fibroblast-collagen matrix remodeling by increasing both integrin-mediated cell attachment to collagen and alpha-SMA expression, thereby contributing to pathological tubulointerstitial collagen matrix reorganization in renal fibrosis.
Actinin↗
Impact of chronic LDL-apheresis treatment on Achilles tendon affection in patients with severe familial hypercholesterolemia: a clinical and ultrasonographic 3-year follow-up study.
OBJECTIVE: Pain of Achilles tendon (AT) is a common symptom in patients with severe familial hypercholesterolemia (FH) and often associated with AT xanthomas. It is unknown if these changes are potentially reversible during lipid lowering treatment. LDL-apheresis (LA) represents the most effective lipid lowering regimen. Aim of this investigation was to determine clinical and ultrasonographic reduction of AT xanthomas in patients with severe FH undergoing regular LA. METHODS: At baseline, patient history of 22 patients with FH undergoing LA was obtained and their 44 ATs were evaluated clinically and with ultrasound for the presence of xanthomas. Three years later, both examinations of ATs could be repeated at follow-up visits in 16 patients. AT thickness and changes in echo structure were assessed at both points of time and compared to each other as well as to a healthy control group (n = 21). ROC analysis was performed to identify the optimal cut-off in AT thickness between healthy and affected ATs. RESULTS: Twelve of 22 FH patients suffered from AT pain at least once during their life-time. At baseline, AT thickness was significantly increased compared to the healthy control group (mean sagittal diameter 10.1 +/- 3.6 mm). At follow-up, AT thickness was significantly reduced to 8.2 +/- 3.3 mm (mean) under LA, whereas changes in echo structure were less distinct between both visits. Conversely, in the control group, mean AT thickness was 5.2 +/- 0.6 mm. The optimal cut-off between healthy and affected ATs was determined to be 6mm. CONCLUSIONS: Ultrasonographic changes of the AT (thickening and changes in echo structure) are frequent in patients with severe FH, even if xanthomas are not clinically evident. LA treatment has the capability to reduce AT xanthomas and thickness. Ultrasound may give information about diagnosis and follow-up of AT affection in patients with FH.
Achilles Tendon↗
Are there endogenous molecules that protect kidneys from injury? The case for bone morphogenic protein-7 (BMP-7).
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Animals↗
Bone morphogenic protein-7 inhibits progression of chronic renal fibrosis associated with two genetic mouse models.
Tubulointerstitial fibrosis is a hallmark feature of chronic renal injury. Specific therapies to control the progression of renal fibrosis toward end-stage renal failure are limited. Previous studies have demonstrated that expression of endogenous bone morphogenic protein-7 (BMP-7) is reduced in the kidneys of several inducible mouse models of acute and chronic renal disease and that administration of exogenous recombinant human BMP-7 (rhBMP-7) has a beneficial effect on kidney function. Here we report that treatment with rhBMP-7 leads to improved renal function, histology, and survival in mice deficient in the alpha3-chain of type IV collagen and MRL/MpJlpr/lpr lupus mice, two genetic models for chronic renal injury and fibrosis. Such therapeutic benefit is also associated with a significant decrease in the expression of profibrotic molecules, such as type I collagen and fibronectin, in renal fibroblasts. Additionally, rhBMP-7 induces expression of active matrix metalloproteinase-2, which is potentially important for removal of fibrotic matrix. Collectively, these studies provide further evidence for rhBMP-7 as an important bone-associated protein with protective function against renal pathology.
Animals↗
Direct contact between human peripheral blood mononuclear cells and renal fibroblasts facilitates the expression of monocyte chemoattractant protein-1.
BACKGROUND: Cell-to-cell interaction is thought to be an important feature of a variety of biological processes. As far as the proinflammatory process is concerned, the interaction between mesangial cells and monocytes/macrophages induces the expression of monocyte chemoattractant protein-1 (MCP-1), and this may play a role in glomerulonephritis. In this study, we investigated whether the cell-to-cell interaction between immune cells and renal fibroblasts induces MCP-1 gene expression, which may be involved in interstitial inflammation in the kidney. METHODS: Human renal fibroblast cell lines, tNKF (from a normal kidney) and tFKIF (from a kidney with fibrosis), and peripheral blood mononuclear cells (PBMC) were used to assess the effect of cell-to-cell contact on the expression of MCP-1 mRNA in the fibroblasts. The expression of the MCP-1 gene in the fibroblasts was also examined after stimulation with tumor necrosis factor-alpha (TNF-alpha) and the culture supernatant from PBMC. RT-PCR was used to detect MCP-1 mRNA expression. Neutralizing antibodies to intercellular adhesion molecule-1 (ICAM-1) and vascular endothelial adhesion molecule-1 (VCAM-1) were used to block the cell-to-cell contact between the fibroblasts and PBMC. RESULTS: TNF-alpha and the culture supernatant from PBMC increased MCP-1 gene expression in tNKF cells. Contact culture with PBMC also significantly increased MCP-1 gene expression in tNKF cells. Although the basal level of MCP-1 mRNA was higher in tFKIF than tNKF cells, tFKIF cells did not respond significantly to any stimulation in this study. Following pretreatment with anti-ICAM-1 antibody, MCP-1 gene expression in tNKF cells was significantly suppressed in contact culture with PBMC. Anti-VCAM-1 antibody treatment had no effects. CONCLUSION: It is suggested that the interaction between renal fibroblasts and PBMC was mediated through direct contact and by secreted humoral factors. ICAM-1 on renal fibroblasts may be involved in the direct cell-to-cell interaction inducing MCP-1 gene expression, which seems to be involved in renal interstitial inflammation.
Antibodies↗
Expression of activation-induced, T cell-derived, and chemokine-related cytokine/lymphotactin and its functional role in rheumatoid arthritis.
OBJECTIVE: To evaluate the possible role of activation-induced, T cell-derived, and chemokine-related cytokine (ATAC)/lymphotactin (Lptn) in the pathogenesis of rheumatoid arthritis (RA). METHODS: ATAC/Lptn levels in serum and synovial fluid samples were measured by sandwich enzyme-linked immunosorbent assay. Expression of messenger RNA for ATAC/Lptn in synovial tissues was analyzed by reverse transcription-polymerase chain reaction (PCR) and by in situ hybridization, and was quantitated by real-time PCR. The phenotype of peripheral blood mononuclear cells (PBMCs) expressing ATAC/Lptn was analyzed by intracellular cytokine staining and flow cytometry. RESULTS: Levels of ATAC/Lptn were similar in sera and synovial fluids from RA patients (n = 20) and osteoarthritis controls (n = 15). In phorbol myristate acetate/ionomycin-stimulated PBMCs, ATAC/Lptn expression was detected in CD8+ T cells and in a significantly increased proportion of CD4+,CD28- T cells from RA patients as compared with healthy controls. In synovial tissues, ATAC/Lptn was predominantly localized in CD3+ T cells in the sublining layer. Lymphocytes, synovial macrophages, and, unexpectedly, fibroblast-like synoviocytes (FLS) were identified as major target cells for ATAC/Lptn in RA synovium, as determined by analysis of the ATAC/Lptn receptor XCR1. In vitro, ATAC/Lptn stimulation of FLS resulted in a marked down-regulation of matrix metalloproteinase 2 production. CONCLUSION: These data indicate that in RA synovium, ATAC/Lptn is mainly produced by T cells. Considering its function as a lymphocyte-specific chemoattractant, ATAC/Lptn might be a key modulator for T cell trafficking in the pathogenesis of RA. In addition, functional studies suggest that ATAC/Lptn may exert additional immunomodulatory effects in RA.
Adult↗