Comparison of recombinant human thyrotropin receptors versus porcine thyrotropin receptors in the thyrotropin binding inhibition assay for thyrotropin receptor autoantibodies

Thyrotropin receptor autoantibodies (TRAb) are most commonly measured in a thyrotropin-binding inhibition (TBI) assay using solubilized porcine thyrotropin receptors (pTSHR). Recently, we reported modifications in recombinant human thyrotropin receptor (hTSHR) production and extraction that made substitution of this antigen for the pTSHR practical. We now report the first comparison of the behavior in a TBI assay of the recombinant, solubilized hTSHR with the pTSHR in a large series of clinically characterized patients with autoimmune thyroid disease. We studied 227 patients with Graves' disease (32 untreated patients, 156 patients receiving antithyroid medications, 24 patients in remission, 9 patients with recurrence of disease, and 6 thyroidectomized patients), as well as 32 patients with Hashimoto's thyroiditis and 28 normal individuals. In patients with untreated Graves' disease, 29 of 32 (90.6%) were TBI positive with either antigen, although two sera gave discrepant data in the two assay. Of the patients receiving antithyroid drugs, 94 of 156 (60.3%) were positive with the pTSHR and 106 of 156 (67.9%) were positive with the hTSHR TBI assay (p < 0.05%). In all other respects, however, there was no difference between the two TBI assays. Neither assay performed well in providing clinical guidance in the remission or relapse of disease. Of the 24 Graves' patients in remission, 75.0% and 79.2% were TBI negative with the hTSHR and pTSHR assays, respectively. The TBI assay at the time of relapse was even less informative; 6 of 9 (66.7%) being TBI negative in the pTSHR assay and 3/9 (33.3%) being negative in the hTSHR assay. In TBI assays with both species of TSHR, 3 of 32 hypothyroid patients with Hashimoto's thyroiditis were TBI positive. In summary, production of the recombinant hTSHR is now a practical reality and this antigen can clearly substitute at least as well for the pTSHR in the imperfect, although most commonly used, TBI assay. It is, therefore, likely that the hTSHR will supplant the pTSHR in this important assay. However, the use of the hTSHR rather than pTSHR does not appear to provide a major advantage, at least in terms of TBI assay sensitivity, specificity and predictive value.

Centrally administered murine leptin stimulates plasma arginine-vasopressin secretion and increases the level of mRNA expression in the supraoptic nucleus of conscious rats

The product of the ob gene protein, leptin, has been suggested to function as an endogenous mediator of the cardiovascular system via sympathetic nerve activity. Moreover, extensive distribution of leptin receptor-like immunoreactivity has been demonstrated in the choroid plexus, cerebral cortex, hippocampus, thalamus and hypothalamus, especially in the paraventricular nucleus (PVN) and supraoptic nucleus (SON). In this study, we have investigated the in vivo effects of leptin on plasma arginine-vasopressin (AVP) secretion and the level of AVP messenger ribonucleotic acid (AVP mRNA) in the SON of conscious rats. Intracerebroventricularly administered leptin increased plasma AVP concentration in a dose-dependent manner (0-400 pmol/rat). The maximal effect was obtained at 15 min after the administration of leptin. Furthermore, in Northern blot analyses, the levels of AVP mRNa in the SON increased approximately 2-fold from the basal level after the administration of leptin. AVP mRNA expression in the PVN was also increased by leptin. However, leptin had no effects on plasma oxytocin (OXT) secretion and OXT gene expression in the SON. In conclusion, leptin is involved in AVP secretion via the central nervous system, however, its physiological role is unknown.

[Hashimoto disease]

Hashimoto disease is a representative organ-specific autoimmune disease. It occurs very frequently in middle-aged women. Generally, the symptom is only diffuse and elastic hard goiters detected by careful plpation. Immunological tests frequently reveal anti-thyroglobulin antibody and anti-TPO antibody. Hypothyroidism develops in some patient along with progression of the disease. In some patient, on the other hand, a condition called destructive thyroiditis may develop during the course of the disease, in which the thyroid gland is transiently destroyed, accompanied by thyrotoxic state. In this state, namely painless thyroiditis, 123I-uptake ratio is extremely low and TSH-receptor antibody is generally not observed. The thyroid hormone is administered to patient with large goiter or hypothyroidism, and antiphlogistic analgesics or adrenocortical hormone with beta-blockers in case of destructive thyroiditis.

Effect of acute thromboxane A2 inhibition on the renal hemodynamics in a spontaneously non-insulin-dependent diabetic rat, Otsuka Long-Evans Tokushima Fatty rat

Thromboxane (TX) A2 plays important roles on renal injuries in streptozotocin (STZ)-induced diabetic rats, whereas its role on the renal injuries in non-insulin-dependent diabetic (NIDDM) rats remains unknown. We evaluated the effects of an intravenous infusion of TXA2 synthetase inhibitor (OKY-046, 6 mg/kg/h) on the clearances on inulin and para-aminohippurate (Cin, C(PAH)) in a spontaneously NIDDM rats, Otsuka Long-Evans Tokushima Fatty (OLETF) rats (n = 8), and Long-Evans Tokushima Otsuka (LETO) rats (n = 7), served as control rats, at the age of 40-44 weeks. OLETF rats showed obesity, moderate hyperglycemia, and hyperinsulinemia. Urinary excretion of TXB2 was slightly higher and the ratio of TXB2 to 6-keto prostaglandin F1alpha (6-kPG) was significantly higher in OLETF rats (TXB2/6-kPG: 0.22 +/- 0.04 versus 0.12 +/- 0.02, P < 0.05). Both Cin and C(PAH) were significantly higher in OLETF rats than in LETO rats (Cin: 1.1 +/- 0.1 versus 0.7 +/- 0.1 mL/min/100 g BW, C(PAH): 3.1 +/- 0.2 versus 2.3 +/- 0.3 mL/min/100gBW, P < 0.01). OKY-046 did not restore Cin and C(PAH) in OLETF rats although it significantly decreased urinary excretion of TXB2, and thus ameliorated TXB2/6-kPG in OLETF rats. These data suggested that TXA2 was not involved in the renal hyperfiltration in OLETF rats at the age of 40-44 weeks, and that TXA2 might contribute to renal injuries in OLETF rats through mechanisms other than hemodynamic injury.

Effect of long-term ethanol consumption on ability to produce cytokine-induced neutrophil chemoattractant-1 in the rat liver and its gender difference

Gut-derived lipopolysaccharide (LPS) may contribute to hepatocellular necrosis in alcoholic hepatitis through neutrophil sequestration in hepatic sinusoids. It is well known that the female has a greater susceptibility to alcoholic liver injury than the male. The aim of the present study was to investigate the effect of long-term ethanol consumption on ability of the liver to produce cytokine-induced neutrophil chemoattractant-1 (CINC-1), the most potent neutrophil-chemokine in rats, after LPS administration. Furthermore, we aimed to evaluate the gender difference in this ability. Male and female rats were pair-fed a liquid diet containing 36% of the total calories as ethanol or dextrose for 6 to 8 weeks. They were given LPS intravenously, and chemokine mRNA expression in the liver was evaluated after 2 and 6 hr. To study the organ or chemokine specificity, CINC-1 mRNA expression in the spleen and monocyte chemoattractant protein (MCP)-1 mRNA level were also determined. Serum ALT activity started to increase between 2 and 6 hr. Female rats fed an ethanol diet showed significantly higher ALT activity 6 hr after LPS injection than the male rats. CINC-1 mRNA expressions in the liver after 2 and 6 hr were significantly higher in the ethanol-fed group, compared with the pair-fed control. Female rats fed an ethanol diet showed a significantly higher level of CINC-1 mRNA in the liver than the male rats 2 hr after LPS injection. CINC-1 levels in the liver homogenates paralleled closely its mRNA expression, whereas its concentrations in sera did not correlate with those in the liver. Neither CINC-1 mRNA expression in the spleen nor MCP-1 mRNA expression in the liver was affected by ethanol feeding or gender. An additional experiment using the gonadectomized rats fed an ethanol diet showed that gonadectomy totally abolished the gender difference in CINC-1 mRNA of the liver. We conclude that CINC-1 induction in the liver may be responsible for LPS-induced hepatitis in the ethanol-fed rats, and that the difference in ability to produce CINC-1 between males and females is one important factor that may partly account for the gender difference of alcoholic liver disease.

Cross-linking of CD44 on rheumatoid synovial cells up-regulates VCAM-1

CD44 is a ubiquitous molecule also known as hyaluronic acid or homing receptor. However, the cellular functions and its role in inflammation, for example, rheumatoid synovitis, are currently unknown. In this study, we propose a novel function for CD44. Using synovial cells from rheumatoid arthritis (RA) patients, we demonstrated that CD44 cross-linking and binding to hyaluronan augmented VCAM-1 expression and subsequently VCAM-1-mediated cell adhesion. Briefly, we found that 1) rheumatoid synovial cells highly expressed CD44; 2) cross-linking of CD44 markedly but transiently augmented VCAM-1 expression and its mRNA transcription much more than did IL-1beta and TNF-alpha; 3) hyaluronan, especially when fragmented, also up-regulated VCAM-1; 4) CD44 activated the transcription factor AP-1; and 5) the integrin-dependent adhesive function of RA synovial cells to T cells was also amplified by CD44 cross-linking. These results indicate that the adhesion of RA synovial cells to matrices such as hyaluronic acid through CD44 could up-regulate VCAM-1 expression and VCAM-1-mediated adhesion to T cells, which might in turn cause activation of T cells and synovial cells in RA synovitis. We therefore propose that such cross-talking among distinct adhesion molecules may be involved in the pathogenesis of inflammation, including RA synovitis.

Interleukin-1alpha regulates G1 cell cycle progression and arrest in thyroid carcinoma cell lines NIM1 and NPA

This study provides the first report that the same cytokine (interleukin-1 (IL-1)) can induce opposite effects on cyclin-dependent kinases (Cdks) and Cdk inhibitors (Cdkis) in the G1 phase even in the same type of cancer cells (papillary thyroid carcinoma cells). Cell cycle analysis revealed an increase in NIM1 cells and a decrease in NPA cells in the S and G2+M phases after treatment with IL-1alpha. The addition of IL-1alpha to NIM1 cells reduced the expression of p16 and p21 protein and induced the expression of Cdk2 and Cdk4 protein, which leads to the phosphorylation of retinoblastoma protein. The addition of IL-1alpha to NPA cells induced the expression of p27 protein and reduced the expression of Cdk2 protein, which leads to induction of p107 protein expression. It is of interest that p21 protein expression was not observed in NPA cells. These results suggest that several Cdks and Cdkis play a regulatory role in the G1 cell cycle progression and arrest induced by IL-1alpha in thyroid carcinoma cell lines.

Hepatocyte growth factor is a potent trigger of neutrophil adhesion through rapid activation of lymphocyte function-associated antigen-1

Recruitment of neutrophils into tissue occurs in several pathologic processes such as inflammation, atherosclerosis, thrombosis, and ischemia. In inflammation, the adherence of neutrophils to the endothelium depends on neutrophil integrins. Integrin-mediated adhesion is tightly regulated, ie, integrins do not function if neutrophils are not triggered by certain activation stimuli. We investigated the role of hepatocyte growth factor (HGF) in the adhesion of neutrophils to endothelial cells in inflammation. Our results showed that (a) HGF induced not only lymphocyte function-associated antigen-1 (LFA-1)-mediated adhesion of neutrophils to endothelial cells but also transmigration of neutrophils in a concentration-dependent manner; (b) HGF functionally transformed neutrophil integrin LFA-1 to active form and reduced surface L-selectin expression level; (c) HGF induced F-actin polymerization and cytoskeletal rearrangement within seconds; (d) genistein, a tyrosine kinase inhibitor, as well as wortmannin, a phosphoinositide 3 (PI 3)-kinase inhibitor, inhibited both F-actin polymerization and LFA-1-mediated adhesion of neutrophils to endothelial cells; and (e) neutrophils in cutaneous inflamed tissue highly expressed HGF and serum levels of HGF were elevated in patients with Behçet's disease, which is associated with neutrophilic vasculitis and marked neutrophil accumulation. Our results indicate that HGF plays a pivotal role in integrin-mediated adhesion and transmigration of neutrophils to sites of acute inflammation through cytoskeletal rearrangement activated by tyrosine kinase and PI 3-kinase signaling.

Constitutive up-regulation of integrin-mediated adhesion of tumor-infiltrating lymphocytes to osteoblasts and bone marrow-derived stromal cells

Tumor-reactive T cells, known as tumor-infiltrating lymphocyte(TIL)s are known to infiltrate various tumors. Although TILs exert cytotoxic activities against tumor cells, only a small percentage of tumors usually contain TILs that specifically react to tumor antigens. Because the exact role of these lymphocytes is unclear, we investigated the mechanisms of migration and adhesion of TILs to bone metastatic tumors, particularly to osteoblasts and bone marrow-derived stromal cell(BMSC)s. Histopathological examination showed that most TILs in secondary bone metastatic tumors (from primary tumors in the lung or breast) were found in the supporting tissue stroma between the bone and tumor mass. Cultured TILs (obtained from breast tumors) adhered spontaneously to osteoblasts and BMSCs (obtained from patients with osteoarthritis) without exogenous stimulation. Adhesion was further enhanced by chemokines macrophage inflammatory protein (MIP)-1alpha and MIP-1beta. TILs highly expressed activation antigens CD25 and CD69. A spontaneous activation of an integrin, lymphocyte function-associated antigen-1 (LFA-1), was also detected on TILs. TILs produced high concentrations of MIP-1alpha and MIP-1beta and spontaneous polymerization of cytoskeletal F-actin was observed in these cells. Adhesion of TILs to osteoblasts and BMSCs via LFA-1 and very late antigen-4 was associated with the production of osteoclastogen interleukin 6 by the latter cells. Our results indicate that integrins on TILs are activated in an autocrine manner by MIP-1alpha and MIP-1beta, and that treatment with the chemokines increases the binding of TILs on osteoblasts and stromal cells via a mechanism involving intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 as targets for the integrin. Our data also indicated that interactions between TILs and osteoblasts/stromal cells lead to the secretion by the latter of the osteoclastogenic cytokine interleukin 6.

Heparan sulfate proteoglycan on endothelium efficiently induces integrin-mediated T cell adhesion by immobilizing chemokines in patients with rheumatoid synovitis

OBJECTIVE

To clarify the role of heparan sulfate proteoglycan (HSPG) and chemokines in integrin-mediated T cell adhesion to endothelial cells in the synovium of patients with rheumatoid arthritis (RA).

METHODS

Endothelial cells were purified from RA synovium. Expression of heparan sulfate, chemokines, and adhesion molecules on the endothelium was assessed by immunohistochemical analysis or flow cytometry. The effects of chemokines and heparan sulfate on T cell adhesion to RA endothelium were estimated with relevant antibodies and signaling inhibitors. Production of chemokines from synovial T cells was detected by Northern blotting and enzyme-linked immunosorbent assay.

RESULTS

The endothelium in RA synovium highly expressed HSPG. The soluble form of chemokines, macrophage inflammatory protein 1beta (MIP-1beta), induced T cell adhesion to the endothelial cells. When MIP-lalpha and MIP-1beta were immobilized on RA endothelial cells, a more efficient integrin-mediated adhesion of T cells was induced compared with their soluble form. The induced T cell adhesion was reduced by pretreatment with either heparitinase, anti-MIP-lalpha antibody, or anti-MIP-lbeta antibody, indicating that these chemokines were bound to heparan sulfate on the cells. T cell adhesion was also inhibited by pertussis toxin, wortmannin, and cytochalasin B. MIP-lalpha and MIP-1beta were found on vessels in RA synovium in vivo, which were spontaneously produced from T cells purified from RA synovium.

CONCLUSION

Endothelial cells in RA synovium characteristically express HSPG, which is involved in T cell integrin triggering by "posting" chemokines, which are produced by synovial T cells, and by "relaying" them to their receptors on T cells, which activate G protein-dependent phosphoinositide 3-kinase and actin-dependent integrin triggering.

Constitutive chemokine production results in activation of leukocyte function-associated antigen-1 on adult T-cell leukemia cells

Adult T-cell leukemia (ATL) is characterized by massive infiltration of circulating ATL cells into a variety of tissues, a finding often associated with poor prognosis. Leukocyte migration from circulation into tissue depends on integrin-mediated adhesion to endothelium, and integrins are tightly regulated by several stimuli, such as inflammatory chemokines. However, the exact mechanisms that enhance adherence of leukemic cells to the endothelium and infiltration into tissues remain to be fully understood. We investigated the mechanisms of extravasation of leukemic cells using ATL cells and report the following novel features of endogenous chemokine-induced adhesion of ATL cells to the endothelium. ATL cells spontaneously adhered to endothelial cells without exogenous stimulation. Integrin leukocyte function-associated antigen-1 (LFA-1) on ATL cells was spontaneously activated. ATL cells produced high amounts of chemokines, macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta. Adhesion of ATL cells to endothelial cells and the expression of activated form of LFA-1 were reduced by pretreatment with pertussis toxin, wortmannin, or anti-MIP-1alpha and MIP-1beta antibodies or transfection with antisense of MIP-1alpha or MIP-1beta. Spontaneous polymerization of cytoskeletal F-actin was observed in ATL cells, which was also inhibited by pertussis toxin and wortmannin. We propose that ATL cells adhere to endothelial cells through an adhesion cascade similar to normal leukocytes and that the chemokines produced by ATL cells are involved in triggering integrin LFA-1 through cytoskeletal rearrangement induced by G-protein-dependent activation of phosphoinositide 3-kinases in an autocrine manner. These events result in a strong adhesion of ATL cells to the endothelium and spontaneous transendothelial migration.

Renal hemodynamics in rats with cadmium-induced nephropathy

Glomerular filtration rate (GFR) is known to decline in patients with cadmium (Cd)-induced nephropathy. However renal hemodynamics in Cd-induced nephropathy remain unknown. We investigated renal hemodynamics in experimental Cd-induced nephropathy. Male Sprague-Dawley rats were given 0.18 mg/rat of cadmium chloride i.p. three times a week for 3 and 16 months. Age-matched control rats were given physiological saline. Mean arterial pressures after 3 and 16 months were identical among the groups. In comparison with age-matched control rats, significant decreases in GFR associated with a significantly lower filtration fraction (FF) were demonstrated in both groups of Cd-treated rats, but the changes were more prominent in the 16-month Cd-treated rats. Renal plasma flow was significantly decreased in the 3-month Cd-treated rats whereas it was preserved in the 16-month Cd-treated rats because of anemia. Urinary sodium excretions in both groups of Cd-treated rats were significantly greater than those in the respective control rats. On light microscopic examination, only mild degeneration of tubular cells and interstitial edema in limited areas of the proximal tubules were observed in the 3-month Cd-treated rats. In the 16-month Cd-treated rats multifocal tubular atrophy and interstitial fibrosis in the outer cortex were noted. Electron microscopic examinations revealed conspicuous degenerative changes in the proximal tubular epithelial cells, diffuse thickening of glomerular basement membranes, and foot process fusions in 16-month Cd-treated rats. These data suggested that the decline in GFR in the Cd-treated rats resulted mainly from the decline in FF, which might be functional rather than structural in origin and might be associated with proximal tubular dysfunctions.

Short-term treatment of recombinant murine interleukin-4 rapidly inhibits bone formation in normal and ovariectomized mice

Estrogen deficiency contributes to an increase in bone resorption and bone formation characterized by a high rate of bone turnover. Interleukin-4 (IL-4) is a rapid and potent inhibitor of bone resorption. We examined the short term in vivo effects of recombinant murine IL-4 (rmIL-4) on bone remodeling in normal and ovariectomized mice. Eight-week-old mice were randomized into the following five groups: (1) sham-operated mice (sham); (2) sham-operated mice infused with rmIL-4; (3) ovariectomized mice (ovx); (4) ovx infused with rmIL-4; and (5) ovx replaced by 10 or 20 microg of 17beta-estradiol (E2) for 14 or 28 days after ovariectomy, respectively. rmIL-4 at a dose of 5 microg/day was infused into ovx and sham for 3 days prior to sacrifice. Analyses were performed 14 and 28 days after operation. An increase in serum alkaline phosphatase and urinary deoxypyridinoline levels induced by ovariectomy was inhibited by the 3-day infusion of rmIL-4. In ovx, serum and urinary IL-6 levels were also increased significantly 14 days after ovariectomy, which were restored by E2 but not by rmIL-4. Histomorphometrical analysis of trabecular bone revealed that the 3-day infusion of rmIL-4 inhibited the high rate of bone turnover induced by ovariectomy, such as an increase in the osteoclastic surface (Oc.S/BS), number of osteoclasts per mm bone surface (N.Oc/BS), mineralized surface per mm bone surface (MS/BS), and bone mineral apposition rate (MAR). A significant decrease in the bone volume (BV/TV) observed in ovx was not modulated by a 3-day infusion of rmIL-4 prior to sacrifice. In sham, rmIL-4 also caused a significant decrease in the Oc.S/BS, N.Oc/BS, MS/BS, and MAR, but the BV/TV was not modulated by rmIL-4. We conclude that short term infusion of rmIL-4 in vivo rapidly inhibits not only bone resorption but also its formation in both sham-operated and ovariectomized growing mice, resulting in a low rate of bone turnover without modulating bone volume.

Modulation of cytokine function by heparan sulfate proteoglycans: sophisticated models for the regulation of cellular responses to cytokines

Cytokines are diffusible, soluble factors with pleiotropic actions. The ability of some cytokines to blind to and be immobilized by heparan sulfate proteoglycan (HS-PG) on either the surface of cells or within the extracellular matrix accentuates their action by 1) promoting the accumulation of cytokines at high concentrations in the appropriate location to encounter their target cells; 2) activating cytokines by inducing conformational changes in the bound cytokine; 3) promoting conformation-dependent association or polymerization of cytokines and their cell-surface receptors and facilitating the assembly of the appropriate molecular complex to initiate signal transduction; and 4) protecting cytokines from both chemical and physiological degradation. Furthermore, many interactions between HS-PG and cytokines are highly specific. Thus, variations in the HS-PG, core protein, or carbohydrate sequences that are seen at different sites or that occur with inflammation will determine which cytokines bind to a particular HS-PG, providing multiple options for cytokine binding and regulation. HS-PG therefore plays a pivotal role in regulating the function of the large number of heparin-binding cytokines. The involvement of HS-PG in promoting paracrine, autocrine, juxtacrine, and matricrine functions provides a powerful and sophisticated model for regulating cytokine-mediated cellular interactions. These functions of HS-PG have direct relevance for the control of cell growth as well as for the pathogenesis of leukocyte trafficking and inflammation, cell infiltration, and tumor metastasis. Therapies aimed at modulating HS-PG/cytokine binding may provide powerful tools for inhibiting unwanted cytokine effects in several disease processes.

Induction of expression of MHC-class-II antigen on human thyroid carcinoma by wild-type p53

Mutation of the tumor-suppressor gene p53 is involved in carcinogenetics. We investigated the role of p53 in the induction of anti-tumor immune responses by establishing a thyroid carcinoma cell line (1F3) prepared by transfection of wild-type human p53 gene into a p53-deficient cell line (FRO). Our results showed for the first time the involvement of p53 in the induction of anti-tumor immune responses, as demonstrated by: (i) expression of the major-histocompatibility-complex(MHC)-class-II antigen on 1F3, but not FRO; (ii) mRNA of class-II gene was expressed both in 1F3 and in FRO, but was stable at post-transcriptional level in FRO, which restrained protein synthesis; (iii) 1F3 induced MHC-class-II-specific CD4+ cytotoxic-T-cell activity through allo-antigen presentation and co-stimulation. Although our novel results are limited to the wild-type-p53-expressing clone from a p53-deficient cell line, we suggest that the absence of p53 in carcinoma cells may reduce the induction of CD4+ cytotoxic-T-cell activity against carcinoma cells by diminishing the expression of class-II antigen.

Centrally administered parathyroid hormone (PTH)-related protein(1-34) but not PTH(1-34) stimulates arginine-vasopressin secretion and its messenger ribonucleic acid expression in supraoptic nucleus of the conscious rats

It has been suggested that PTH-related protein (PTHrP) is an endogenous modulator of cardiovascular systems. We have reported that PTHrP(1-34), but not PTH(1-34), causes the release of arginine-vasopressin (AVP) from the supraoptic nucleus (SON) of the hypothalamus in vitro through a novel receptor distinct from the PTH/PTHrP receptors (type I or type II) described previously. In this study, we have investigated the in vivo effects of PTHrP(1-34) on AVP secretion and its, messenger RNA (mRNA) expression in the SON in conscious rats. Intracerebroventricular (i.c.v.) administration of PTHrP(1-34) resulted in an increase in plasma AVP concentration in a dose-dependent manner (0-400 pmol/rat). The maximal effect was obtained at 15 min after i.c.v. administration of PTHrP(1-34). Neither PTHrP(7-34) nor PTH(1-34) had any effect on plasma AVP levels. PTHrP(1-34)-induced AVP secretion was antagonized by pretreatment with PTHrP(7-34) but not by that with PTH(1-34). In addition, in situ hybridization study revealed that AVP mRNA expression in the SON and paraventricular nucleus was significantly increased 30 min after i.c.v. administration of PTHrP(1-34) and reached a maximum at 180 min. Furthermore, in Northern blot analyses, AVP mRNA expression in the SON was increased to approximately a 2-fold of basal level by PTHrP(1-34). On the other hand, neither PTHrP(7-34) or PTH(1-34) had any effect on the mRNA expression. The PTHrP(1-34)-stimulated AVP mRNA expression was eliminated by pretreatment with PTHrP(7-34) but not with PTH(1-34). These results suggest that, in the central nervous system, PTHrP(1-34) is involved in AVP secretion through a novel receptor distinct from the PTH/PTHrP receptors reported previously, playing a role in the body water and electrolyte homeostasis.

Human T-cell leukemia virus type I Tax transactivates the promoter of human prointerleukin-1beta gene through association with two transcription factors, nuclear factor-interleukin-6 and Spi-1

The human T-cell leukemia virus type I (HTLV-I), which infects a wide variety of mammalian cells including monocytes and macrophages, encodes a transactivating protein designated as Tax. We now report that Tax induces the human prointerleukin-1beta (IL1B) gene promoter in monocytic cells. In our transient transfection assays using human THP-1 monocytic cells, a chloramphenicol acetyltransferase (CAT) construct containing the IL1B promoter sequence between positions -131 and +12 showed an approximately 90-fold increase in activity following cotransfection of a Tax expression vector. Moreover, Tax synergized with lipopolysaccharide (LPS) to induce the IL1B promoter activity. Analyses of specific nucleotide substitutions further indicated that the Tax-induced transcriptional activation requires two transcription factor binding motifs within the IL1B promoter; one is a binding site for nuclear factor (NF)-IL6 (CCAAT/enhancer binding protein beta, C/EBP beta), which belongs to the basic region-leucine zipper (bZIP) family and the other for Spi-1 (PU.1), which is an Ets family protein found principally in monocytes, macrophages, and B lymphocytes. In electrophoretic mobility shift assays (EMSA) using in vivo THP-1 nuclear extracts, Tax expression in THP-1 monocytic cells significantly increased binding of the two factors to their target IL1B promoter sequences. However, in contrast to NF-IL6 and Spi-1, DNA binding activity of Oct-1, an ubiquitously expressed octamer-binding protein was not affected by Tax. Additional EMSA using in vitro translated proteins also showed that recombinant Tax enhances DNA binding of both of recombinant NF-IL6 and Spi-1 proteins. These data were supported by our glutathione S-transferase (GST)-pull-down data, which indicated that Tax physically interacts with the two proteins. Based on the results obtained from the present study, we conclude that the IL1B promoter is a Tax-responsive sequence as a result of ability of Tax to induce binding of NF-IL6 and Spi-1 to the IL1B promoter sequence through protein-protein interaction.

Chondrocytes are regulated by cellular adhesion through CD44 and hyaluronic acid pathway

The articular cartilage consists of resident chondrocytes embedded within the extracellular matrix which contains several components such as collagen and hyaluronic acids (HA). CD44 is a major cell surface receptor for HA and is homologous to cartilage-link proteins. Although CD44 is present in cartilage, it is not clear if chondrocytes adhere to HA through CD44 or whether such adhesion changes the function of chondrocytes. We studied the molecular mechanisms of CD44-related chondrocyte adhesion to HA and the effects of such adhesion on chondrocyte function. Experiments were performed using the human chondrosarcoma-derived chondrocyte-like cell line HCS-2/8. Our results showed that (a) HCS-2/8 cells highly expressed CD44; (b) HCS-2/8 cells efficiently adhered to HA without any stimuli; (c) monoclonal antibody (mAb)-blocking studies indicated that adhesion of HCS-2/8 cells to HA was mainly mediated by the CD44/HA pathway; (d) cellular adhesion to HA increased the proliferation of HCS-2/8 cells, independent of transforming growth factor-beta (TGF-beta), but this was inhibited by CD44 mAb; (e) the adhesion of chondrocytes to HA also induced c-myc mRNA expression and this was also inhibited by CD44 mAb; and (f) the adhesion of cells to HA augmented TGF-beta mRNA expression, a process also reduced by CD44 mAb. Thus, HCS-2/8 cells effectively adhered to HA through cell surface CD44. The adhesion was also involved in cellular signaling which induced cellular proliferation and expression of c-myc mRNA as well as TGF-beta mRNA expression within the cells. Our results indicate that CD44 on chondrocytes plays an important role in normal and abnormal functions of cartilage through its adhesion to HA, which induces a variety of stimulatory signals to regulate chondrocyte proliferation as well as matrix synthesis in cartilage microenvironment.

C-type natriuretic peptide suppresses arginine-vasopressin secretion from dissociated magnocellular neurons in newborn rat supraoptic nucleus

Central administration of C-type natriuretic peptide (CNP) affects various neuroendocrine systems. In the present study, we examined whether CNP acts directly on arginine-vasopressin (AVP) secretion from rat supraoptic nucleus (SON) neurons, using acute dissociated cell preparations. CNP inhibited the basal secretion of AVP in a dose-dependent manner (10(-11)-10(-6) M). A- type natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) also suppressed the basal secretion of AVP, however, the effects were two-orders of magnitude less potent than CNP. CNP also suppressed All-induced AVP secretion, however, the inhibitory effect of CNP was less than that of ANP or BNP. These findings suggest that CNP inhibits the basal secretion of AVP through natriuretic peptide receptor (NPR)-B and has a role in the body water and electrolyte homeostasis in the central nervous system.

Parathyroid hormone-related peptide-(1-34) [PTHrP-(1-34)] induces vasopressin release from the rat supraoptic nucleus in vitro through a novel receptor distinct from a type I or type II PTH/PTHrP receptor

PTH and PTH-related peptide (PTHrP) bind to a type I PTH/PTHrP receptor expressed in bone and kidney or a type II receptor in nonclassical target tissue with equal affinity and similar bioactivities. PTHrP is abundant in the central nervous system, but its physiological role remains unknown. Herein, we examined the role of PTHrP-(1-34) on arginine vasopressin (AVP) release from the rat supraoptic nucleus (SON). Application of PTHrP-(1-34) to SON slices caused an increase in AVP release in a concentration-dependent manner. Neither PTHrP-(7-34) nor PTH-(1-34) had any effect on AVP release from the SON. PTHrP-(1-34)-induced AVP release was antagonized by a large excess of PTHrP-(7-34) and by H89, an inhibitor of cAMP-dependent protein kinase (A kinase), but not by PTH-(1-34) or PTH-(13-34). PTHrP-(1-34), but not PTH-(1-34), also dose-dependently increased the levels of cAMP in the SON. 125I-Labeled PTHrP-(1-34) bound specifically to crude membranes isolated from the SON. Scatchard analysis showed a single class of binding sites for PTHrP-(1-34) with a Kd of 36.4 nM and a maximum binding capacity of 3.94 pmol/mg protein. No specific binding for 125I-labeled PTH-(1-34) was noted. The binding of 125I-labeled PTHrP-(1-34) was displaced by unlabeled PTHrP-(1-34) and unlabeled PTHrP-(7-34), but not by unlabeled PTH-(1-34). These findings suggest that PTHrP-(1-34), but not PTH-(1-34), causes the release of AVP from the SON through a novel receptor distinct from type I or II PTH/PTHrP receptors.

Distinct phenotype of leukemic T cells with various tissue tropisms

There is an emerging concept, the validity of which remains to be proven, that preferential expression of selective adhesion molecules on particular T cell subsets may result in tissue-specific migration. L-selectin, cutaneous lymphocyte-associated Ag (CLA), and integrin alpha4beta7 are proposed to be involved in selective migration of T cell subsets into peripheral lymph nodes, skin, and gastrointestinal mucosa, respectively. Adult T cell leukemia (ATL) is associated with lymphoid infiltration of tissues and secondary lymphoid organs. To clarify the role of these putative homing molecules in vivo, we assessed their expression on circulating ATL cells from patients with lymph node, skin, and gut involvement. L-selectin expression was significantly higher on peripheral ATL cells in patients with lymphadenopathy than in patients without it. CLA was highly expressed on peripheral ATL cells compared with normal T cells: its expression was also significantly higher on peripheral ATL cells from patients with skin involvement compared with cells from patients without it. beta7 was particularly highly expressed on peripheral ATL cells from patients with gastrointestinal involvement. In summary, the differential expression of beta7 and beta1 on peripheral ATL cells correlates with the presence of gastrointestinal involvement. Similarly, the presence of skin involvement is associated with the expression of CLA(high)beta7low on peripheral ATL cells. These results, which are consistent with the molecules CLA and alpha4beta7 mediating preferential T cell migration to the skin and gastrointestinal mucosa, respectively, may allow for a refinement of the classification of lymphoid neoplasms on the basis of differential expression of homing molecules.

Regulation of interleukin (IL)-1beta gene transcription induced by IL-1beta in rheumatoid synovial fibroblast-like cells, E11, transformed with simian virus 40 large T antigen

OBJECTIVE

To investigate the process involved in the production of and responsiveness to interleukin 1beta (IL-1beta) in synovial fibroblast-like cells, we analyzed the enhancer region of pro-IL-1beta gene in a cell clone, E11, established from a patient with rheumatoid arthritis (RA).

METHODS

A cell clone, E11, was derived from rheumatoid synovial fibroblast-like cells transformed with simian virus 40 large T antigen expression vector by electroporation. Responsiveness of E11 to IL-1beta was analyzed by [3H] thymidine incorporation and Northern blotting. IL-1beta responsive elements on pro-IL-1beta gene were analyzed by chloramphenicol acetyltransferase analysis.

RESULTS

E11 resembled synovial fibroblasts based on morphological characteristics and phenotypic analysis. It also demonstrated marked enhancement of proliferation and rapid induction of IL-1beta mRNA expression by IL-1beta. We also identified IL-1beta responsive elements on the pro-IL-1beta gene at a position between -3134 and -3092 that contains the AP-1 binding site and between -2782 and -2729, which includes both AP-1 and nuclear factor-kappaB (NF-kappaB) binding sites.

CONCLUSION

AP-1 and NF-kappaB binding elements were required for transcriptional regulation of the IL-1beta gene in the autocrine growth system of RA synovial cells.

Rheumatoid synovial fibroblasts are stimulated by the cellular adhesion to T cells through lymphocyte function associated antigen-1/intercellular adhesion molecule-1

OBJECTIVE

To determine if T cells stimulate synovial fibroblasts to produce inflammatory cytokines through cellular adhesion in synovitis of rheumatoid arthritis (RA).

METHODS

Immunohistochemical staining, flow microfluorometry, adhesion assay, ELISA, and Northern blot analysis to determine production of interleukin-1beta (IL-1beta) from RA synovium and RA synovial fibroblast-like cell line.

RESULTS

We observed the following novel features of cellular adhesion of T cells to synovial fibroblasts, which suggest a role for induction of cytokine production in synovial fibroblasts: (a) CD11a (lymphocyte function associated antigen-1 alpha) positive T cells accumulated around CD54 [intercellular adhesion molecule (ICAM-1)] positive synoviocytes in active RA synovium, shown by immunohistochemical studies: (b) synovial fibroblastic cell line E11 expressed a single adhesion molecule ICAM-1, the expression of which was not affected by IL-1beta; (c) E11 adhered to phorbol myristate acetate (PMA) activated T cells within 30 min, not resting T cells, and its adhesion was completely inhibited by anti-LFA-1 monoclonal antibody (Mab); (d) pretreatment of E11 with IL-1beta did not affect the adhesion of E11 to PMA activated T cells; (e) IL-1beta production and IL-1beta mRNA transcription from E11 were induced by the addition of T cells in a cell number dependent manner and the induced production and transcription were inhibited by anti-LFA-1 Mab.

CONCLUSION

T cells infiltrating the synovium may play a pivotal role in the pathogenesis of RA, by inducing IL-1beta production of synovial fibroblasts by sequential events, namely, T cell-synoviocyte cellular adhesion through LFA-1/ICAM-1, signal transduction, and production of IL-1beta induced by the cellular adhesion.