Factor(s) present in sera from patients on long-term hemodialysis increase(s) mRNAs for collagenase and stromelysin in synovial cells

Tumor necrosis factor alpha induces expression of genes for matrix degradation in human chondrocyte-like HCS-2/8 cells through activation of NF-kappaB: abrogation of the tumor necrosis factor alpha effect by proteasome inhibitors

Tumor necrosis factor alpha (TNF-alpha) has been suggested to induce chondrocytic chondrolysis in both inflammatory and degenerative joint diseases. However, its intracellular signaling pathway leading to the chondrolysis has not been studied in detail. Thus, we investigated whether TNF-alpha activates a transcription factor nuclear factor kappaB (NF-kappaB) in human chondrocyte-like cells (HCS-2/8) and induces the expression of genes involved in the degradation of cartilage matrix. Treatment of the cells with TNF-alpha markedly increased the levels of matrix metalloproteinase 1 (MMP-1), MMP-3, intercellular adhesion molecule 1 (ICAM-1), and cyclo-oxygenase 2 (COX-2) messenger RNAs (mRNAs). The increase in the mRNAs was associated with the activation of p65/p50 heterodimer NF-kappaB. IkappaB-alpha and IkappaB-beta, cytoplasmic molecules preventing the nuclear translocation of NF-kappaB, were degraded rapidly by TNF-alpha followed by their synthesis to the basal level. Treatment with proteasome inhibitors inhibited the degradation of both IkappaB-alpha and IkappaB-beta and prevented the TNF-alpha-dependent nuclear translocation of p65. Furthermore, the inhibitors completely prevented the TNF-alpha-dependent induction of MMP-1, MMP-3, ICAM-1, and COX-2 mRNAs. Thus, it is shown that the activation of p65/p50 NF-kappaB by TNF-alpha plays a cardinal role in inducing the expression of MMP-1, MMP-3, ICAM-1, and COX-2 genes, which are involved in matrix degradation and inflammatory reaction in chondrocytes, leading to chondrocytic chondrolysis.

Messenger ribonucleic acid expression of 16 matrix metalloproteinases in bone-implant interface tissues of loose artificial hip joints

Matrix metalloproteinases (MMPs) have been reported to be the major factors responsible for aseptic loosening of artificial hip joints. So far, messenger ribonucleic acid (mRNA) expression patterns of seven MMPs have been reported, but that of many other MMPs which have been newly discovered or recently considered to be responsible for prosthetic loosening is still unknown. In this study, mRNA expression pattern of 16 different types of MMPs were analyzed to evaluate which MMPs were locally produced and contributed to prosthetic loosening. Synovium-like interface tissues between bone and prosthesis were collected from 18 cases of aseptic loose artificial hip joint at revision surgery. Six cases of normal synovium were used as controls. Total RNA was extracted by single-step acid guanidinium-thiocyanate-phenol-chloroform procedure. mRNA expression of MMPs was analyzed by semiquantitative reverse transcription-polymerase chain reaction. Based on local expression pattern of MMPs at the mRNA level, aseptic loose artificial hip joint was characterized by elevated expression of MMP-1, MMP-9, MMP-10, MMP-12, and MMP-13; moderate expression of MMP-2, MMP-7, MMP-8, MMP-11, membrane type (MT)1-MMP (MMP-14), MT2-MMP (MMP-15), MT3-MMP (MMP-16), MT4-MMP (MMP-17), and MMP-19; lower expression of MMP-3; and little significance of MMP-20. The MMPs detected in this study can potentially degrade almost all components of the periprosthetic extracellular matrix. Thus, many MMP type enzymes possibly contribute to prosthetic loosening and osteolysis through pathologic extracellular matrix degradation and connective tissue/bone remodeling around prostheses.

An oral sorbent reduces overload of indoxyl sulphate and gene expression of TGF-beta1 in uraemic rat kidneys

BACKGROUND

An oral adsorbent (AST-120) delays the progression of chronic renal failure (CRF). The aims of the present study are to determine the effects of AST-120 on the localization of indoxyl sulphate in uraemic rat kidneys, and to examine whether AST-120 reduces the renal cortical gene expression of transforming growth factor (TGF)-beta1, tissue inhibitor of metalloproteinase (TIMP)-1 and pro-alpha1(I)collagen, and ameliorates glomerular and tubulointerstitial injuries in uraemic rats.

METHODS

Two weeks after 5/6-nephrectomy, 10 rats were divided into pairs such that both rats in each pair exhibited almost the same levels of serum creatinine, blood urea nitrogen and creatinine clearance. One rat from each pair was assigned to a control uraemic group, the other to a uraemic group which received AST-120 everyday for 11 weeks. The localization of indoxyl sulphate was studied by immunohistochemistry using a monoclonal anti-indoxyl sulphate antibody we had developed. The renal cortical gene expression was studied by using northern blotting.

RESULTS

Rats treated with AST-120 showed decreased levels of serum creatinine, blood urea nitrogen and urinary protein as well as increased levels of creatinine clearance as compared with control uraemic rats. AST-120 markedly decreased indoxyl sulphate levels in both serum and urine. Immunohistochemistry demonstrated that indoxyl sulphate was localized in the renal proximal tubular epithelial cells, especially of dilated tubules, and that AST-120 markedly reduced the tubular staining of indoxyl sulphate. AST-120 attenuated interstitial fibrosis, tubular injury as well as glomerular sclerosis, and reduced the renal gene expression of TGF-beta1, TIMP-1 and pro-alpha1(I)collagen.

CONCLUSIONS

AST-120 reduces the gene expression of TGF-beta1, TIMP-1 and pro-alpha1(I)collagen in the kidneys, and delays the progression of CRF, at least in part, by alleviating the overload of indoxyl sulphate on remnant proximal tubular epithelial cells.

Expression of E16/CD98LC/hLAT1 is responsive to 2,3,7,8-tetrachlorodibenzo-p-dioxin

We employed cDNA representational difference analysis to identify new genes that are upregulated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in a human hepatoblastoma cell line HepG2. We isolated several TCDD-responsive cDNAs. Sequence analysis revealed that one of them encodes E16/CD98LC/hLAT1, an integral membrane protein involved in multiple cellular functions including cellular transport of L-type amino acids. Northern blot analysis confirmed the TCDD-dependent upregulation of the mRNA. Induction of E16/CD98LC/hLAT1 mRNA by TCDD did not require de novo protein synthesis as revealed by the experiment using cycloheximide. Consistent with the changes at mRNA level, the transport of 3H-leucine into HepG2 cells was significantly increased by TCDD treatment. These findings provide a novel aspect of biological effects of TCDD on human hepatocytes.

TNF-alpha increases expression of IL-6 and ICAM-1 genes through activation of NF-kappaB in osteoblast-like ROS17/2.8 cells

Tumor necrosis factor-alpha (TNF-alpha) plays a key role in inflammatory diseases such as rheumatoid arthritis and in postmenopausal osteoporosis. In various tissues, TNF-alpha action is mediated by a transcription factor, nuclear factor-kappa B (NF-kappaB). However, little is known about how TNF-alpha exerts its action in osteoblasts. We thus examined the effect of TNF-alpha on the activation of NF-kappaB in rat osteoblast-like osteosarcoma cells (ROS17/2.8). Electrophoretic mobility shift assay revealed that the activation of the p50-p65 heterodimer NF-kappaB was induced by TNF-alpha as early as 15 minutes followed by a persistent activation for 48 h. When the binding activity of NF-kappaB in cytosol was examined using detergents that dissociate NF-kappaB from an inhibitory protein IkappaB, it decreased during the initial 30 minutes and then increased to the unstimulated level. Northern blot analysis revealed a marked increase in the mRNA levels of p105, a precursor of p50, 6 h after TNF-alpha and a gradual increase in p65 mRNA levels during the initial 1 h. Significant increase in both mRNA levels continued until 24 h after TNF-alpha. These results suggest that the rapid activation of NF-kappaB by TNF-alpha is mainly due to the nuclear translocation of NF-kappaB pre-existing in cytosol, and that the subsequent increase in the expression of p50 and p65 may result in the persistent activation of NF-kappaB during TNF-alpha stimulation. TNF-alpha also increased the mRNA levels of interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1). An antioxidant, N-acetyl-L-cysteine, significantly attenuated the TNF-alpha-dependent increase in these mRNAs, and simultaneously reduced the activation of NF-kappaB by TNF-alpha, indicating that NF-kappaB mediates the TNF-alpha-dependent expression of IL-6 and ICAM-1 in ROS17/2.8 cells. These results suggest that the activation of NF-kappaB by TNF-alpha may play an important role in the production of cytokines and cell adhesion molecules from osteoblasts, leading to the promotion of bone resorption and inflammation.

Up-regulation of COX2 expression by uni-axial cyclic stretch in human lung fibroblast cells

The effect of uni-axial cyclic mechanical stretch on the expression of cyclooxygenases (COX) was investigated in a human lung fibroblast cell line (TIG-1). In response to uni-axial cyclic stretch, the level of COX2 mRNA significantly increased and peaked at 3 h (9.09 +/- 3.82-fold, mean +/- standard error, n = 6, compared with that at 1 h). The level of the expression of COX2 protein peaked at 6 h, whereas the level of COX1 protein was not significantly changed. The involvement of stretch-activated (SA) channel was investigated in the stretch-induced COX2 production. The application of Gd3-, a blocker for SA channel, or the removal of extracellular Ca2+ inhibited the production of COX2 mRNA without any effect on the production of COX1 or GAPDH mRNA. These data strongly suggest that COX2 expression is up-regulated by uni-axial cyclic stretch via the activation of SA channel in human lung fibroblasts.

Up-regulation of integrin beta 3 expression by cyclic stretch in human umbilical endothelial cells

The effect of uni-axial cyclic mechanical stretch on the expression of the adhesion protein integrin was investigated. Human umbilical endothelial cells (HUVECs) cultured on fibronectin coated silicon membranes were subjected to uni-axial cyclic stretch. The level of expression of integrin beta 3 mRNA was found to be increased and peaked at 4 hours in response to cyclic stretch using a semiquantitative RT-PCR method. The increased level of the integrin mRNA from stretched HUVECs remained higher than that from non-stretched controls. The amount of integrin beta 3 also increased and peaked at 12 hr. Immuno-fluorescent microscopy revealed that the amount of integrin beta 3 adhesions increased in stretched HUVECs compared with that in non-stretched HUVECs. These results suggest that uni-axial cyclic stretch up-regulates the expression of integrin beta 3. This increase in integrin beta 3 may enhance the adhesiveness to the substratum and contribute to the protection of HUVECs against being peeled off from the vessel wall.

Effects of thyroid and glucocorticoid hormones on Kv1.5 potassium channel gene expression in the rat left ventricle

The effects of thyroid and glucocorticoid hormones on the expression of the Kv1.5 potassium channel gene were studied in the rat left ventricle. Rats were rendered hypothyroid by oral administration of methimazole (MMI). Hyperthyroidism was induced in the MMI-treated rats by administration of L-thyroxine (T4). Kv1.5 mRNA levels decreased markedly in the hypothyroid rats, whereas they increased in the hyperthyroid rats. Propranolol, a beta-adrenergic blocker, did not inhibit the T4-dependent increase in Kv1.5 mRNA, indicating that the increase is not due to the increased beta-adrenergic stimuli under hyperthyroidism. Accordingly, treatment of the MMI-treated hypothyroid rats with isoproterenol, a beta-adrenergic receptor agonist, did not increase the mRNA. The Kv1.5 mRNA levels positively correlated with the thyroid hormone levels in sera. When rats were adrenalectomized and rendered hypothyroid, Kv1.5 mRNA become undetectable. Administration of 3,3',5-triiodothyronine (T3) at a dose to induce hyperthyroidism did not restore the mRNA level. However, T3 significantly increased the mRNA level when dexamethasone was co-administered at a physiological dose. These results for the first time demonstrate that thyroid hormone up-regulates Kv1.5 mRNA levels in the rat left ventricle and they demonstrate that glucocorticoid is required for this induction.

Macrophage activation and migration in interface tissue around loosening total hip arthroplasty components

The bone-cement interface tissue of failed total hip arthroplasty (THA) has inflammatory characteristics, such as the presence of prostaglandin E2 and interleukin 1 (IL-1). We considered that the bone-cement interface tissue could be the site of granulomatous inflammation caused by a foreign-body reaction. It has been demonstrated that inflammatory cytokines and chemokines have an important role in granulomatous inflammation. Bone-cement interface tissue was obtained at revision from nine patients with failed cemented THA, and the role of macrophages was assessed by immunohistochemistry, electron microscopy, and molecular biological techniques. We used the reverse-transcriptional polymerase chain reaction to examine the expression of mRNA for IL-1 alpha, IL-1 beta, tumor necrosis factor alpha (TNF alpha), macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, IL-8, and monocyte chemoattractant protein. Polyethylene debris surrounded by macrophages and phagocytosis of debris by macrophages was frequently observed in the interface tissue. Macrophage activation and the production of inflammatory cytokines such as IL-1 and TNF alpha might induce the development of interface tissue. Expression of chemokine mRNAs was also commonly seen, suggesting that this led to recruitment of macrophages into the bone-cement interface tissue. Debris released from implants appears to cause activation of macrophages and the production of inflammatory cytokines and chemokines that induce cellular recruitment into interface tissue. This mechanism might form a vicious cycle that aggravates THA loosening.

mRNA expression of matrix metalloproteinases and tissue inhibitors of metalloproteinase in interface tissue around implants in loosening total hip arthroplasty

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinase (TIMPs) play an important role in tissue destruction and remodeling. Nine samples of cement interface tissues from nine patients who had failed cemented total hip arthroplasty (THA) were obtained for revision of THA and analyzed on mRNA expression of MMPs and TIMPs. The preoperative serial radiographic examinations revealed an apparent clear zone around all implants. We excluded septic loosening as one of the factors affecting THA. Three samples were obtained from three different sites of the acetabular interface tissue in each patient. After extraction of total RNA from 27 samples, we used the reverse-transcriptional polymerase chain reaction (RT-PCR). mRNA of MMP-1, -2, -3, -9, and TIMP-1 and -2 was detected in the interface tissue. MMP-10 mRNA was not detected, yet MMP-1 and MMP-3 mRNA were commonly observed. TIMP-2 mRNA was also strongly expressed compared to TIMP-1. It was thus demonstrated that MMPs and TIMPs were produced locally in the cemented tissue of THA loosening. These findings may suggest that MMPs and TIMPs expressed around the implants play a critical role in the progression of aseptic loosening of THA.

Molecular cloning of a novel thyroid hormone-responsive gene, ZAKI-4, in human skin fibroblasts

Utilizing a method called "differential display of mRNAs by means of polymerase chain reaction", the cDNA fragment of a thyroid hormone-responsive gene ZAKI-4 was cloned from cultured human skin fibroblasts. Northern blot analysis revealed that there were two ZAKI-4 mRNA species (3.4 and 1.4 kilobases (kb)), and they were up-regulated by a physiological concentration of triiodothyronine (T3). This T3 effect was abolished by the treatment with cycloheximide, indicating the possibility that gene ZAKI-4 is regulated by T3 in an indirect fashion, through an intermediate product of T3, rather directly by T3 itself. No effect of T3 on ZAKI-4 mRNA stability suggested that T3 induces the mRNA at the transcriptional level. Rapid amplification of cDNA ends confirmed the presence of two mRNA species. ZAKI-4 mRNA was detected in heart, brain, liver, and skeletal muscle but not in placenta, lung, kidney and pancreas. In skin fibroblasts and skeletal muscle, 3.4-kb mRNA was the major species, whereas 1.4-kb mRNA was dominant in heart, brain, and liver. The sequence analysis suggested that the two mRNA species arise from alternative polyadenylation and code a single protein of 192 amino acids. No homologous protein sequence was found in a data base. Elucidation of the function of ZAKI-4 gene product will provide new insights into an important role of T3 in various organs.

Increase of vascular endothelial growth factor mRNA expression by 1,25-dihydroxyvitamin D3 in human osteoblast-like cells

Vascular endothelial growth factor (VEGF), a secreted endothelial cell-specific mitogen, is produced in endocrine organs and regulated by trophic hormones. Because angiogenesis and osteogenesis are closely regulated, we studied whether human osteoblast-like cells produce VEGF, and if so, what factors regulate VEGF mRNA expression. Human osteoblast-like cells (HObLC) derived from trabecular bone explants were cultured in alpha-MEM supplemented with 10% fetal calf serum. Northern blot analysis revealed that HObLC expressed VEGF mRNA, as did several human osteosarcoma cells. 1,25-(OH)2D3 increased the steady-state levels of VEGF mRNA in a time- and concentration-dependent manner in HObLC and one of the osteosarcoma cell lines, SaOS-2, accompanied by an increase in the concentration of immunoreactive VEGF in the conditioned medium. PTH and IGF-I also increased the level of VEGF mRNA in HObLC and SaOS-2 cells. Furthermore, 12-O-tetradecanoylphorbol ester stimulated VEGF mRNA in a time-and concentration-dependent manner. The VEGF mRNA expression induced by 1,25-(OH)2D3 was completely inhibited by H-7, but only partially by staurosporine. We have demonstrated that PTH, IGF-I, and most potently 1,25-(OH)2D3 stimulate the mRNA expression and secretion of VEGF in human osteoblast-like cells, suggesting that one of the anabolic effects of 1,25-(OH)2D3 on skeletal tissue may be mediated by VEGF produced by osteoblasts.

Stimulation by thyroid-stimulating hormone and Grave's immunoglobulin G of vascular endothelial growth factor mRNA expression in human thyroid follicles in vitro and flt mRNA expression in the rat thyroid in vivo

To elucidate the pathogenesis of thyroid gland hypervascularity in patients with Graves' disease, we studied the expression of mRNAs for vascular endothelial growth factor (VEGF) and its receptor, Flt family, using human thyroid follicles in vitro and thiouracil-fed rats in vivo. Human thyroid follicles, cultured in the absence of endothelial cells, secreted de novo-synthesized thyroid hormone in response to thyroid-stimulating hormone (TSH) and Graves' IgG. The thyroid follicles produced VEGF mRNA but not flt-1 mRNA. The expression of VEGF mRNA was enhanced by insulin, tumor-promoting phorbol ester, calcium ionophore, dibutyryl cAMP, TSH, and Graves' IgG. When rats were fed thiouracil for 4 wk, their serum levels of TSH were increased at day 3. VEGF mRNA was also increased on day 3, accompanied by an increase in flt family (flt-1 and KDR/ flk-1) mRNA expression. These in vitro and in vivo findings suggest that VEGF is produced by thyroid follicles in response to stimulators of TSH receptors, via the protein kinase A and C pathways. VEGF, a secretable angiogenesis factor, subsequently stimulates Flt receptors on endothelial cells in a paracrine manner, leading to their proliferation and producing hypervascularity of the thyroid gland, as seen in patients with Graves' disease.