Thrombin stimulates production of transforming growth factor-beta by cultured human mesangial cells

Fibrin formation within the glomeruli occurs in various forms of human and experimental glomerulonephritis and it may play an important role in progressive glomerular injury. Transforming growth factor-beta (TGF-beta) has been shown to participate in the glomerular accumulation of extracellular matrix in glomerulonephritis. We investigated whether thrombin, an important coagulation factor, could modulate the production of TGF-beta by cultured human mesangial cells (HMC). TGF-beta levels in the culture supernatants were measured by ELISA using a specific antibody. The TGF-beta concentration was significantly increased by incubation of HMC with thrombin in a time-dependent manner. The stimulating effect of thrombin on TGF-beta was inhibited by addition of hirudin (a natural thrombin inhibitor) and argatroban (a synthetic thrombin inhibitor). In addition DFP-inactivated thrombin, which has no enzymatic activity, did not stimulate TGF-beta production. A protein kinase C inhibitor (H7) and a tyrosine kinase inhibitor (herbimycin A) also inhibited thrombin induced TGF-beta production. These findings suggested that thrombin may modulate the synthesis of TGF-beta via protein kinase C- and tyrosine kinase-dependent mechanisms in cultured HMC. Thus thrombin may participate in the accumulation of extracellular matrix in glomeruli through the augmentation of TGF-beta production.

Type 2 helper T cell-type cytokines and the development of "infectious" tolerance in rat cardiac allograft recipients

CD4-targeted therapy with a nondepleting RIB-5/2 mAb abrogates accelerated (< 36 h) rejection in presensitized LEW rats and results in permanent acceptance of LBNF1 cardiac allografts in conjunction with the features of infectious tolerance. This study examined the role and functional significance of the Th1 and Th2 cytokine network and systemic host allospecific Ab (allo-Ab) responses in the development of the infectious tolerance pathway in this model. Long term survival of cardiac transplants in rats treated with the tolerizing RIB-5/2 mAb regimen was accompanied by profound depression of Th1 (IL-2 and IFN-gamma) and Th2 (IL-4, IL-10) cytokines at the graft site, as shown by competitive template reverse transcription-PCR and immunohistochemistry. In contrast, the expression of Th2-type cytokines was selectively up-regulated after transfer of infectious tolerance by spleen cells into new generations of primary and secondary test recipients. Donor-specific circulating IgM allo-Ab responses were diminished throughout, and the switch from IgM to IgG allo-Ab was completely prevented in tolerant hosts, as shown by flow cytometry. The demonstration that treatment with cytolytic anti-CD4, but not anti-CD8, mAb recreated rejection of test cardiac allografts with simultaneous down-regulation of IL-4 mRNA/protein expression underlines the importance of this cytokine in the development of infectious tolerance. Hence, this report documents distinct cytokine elaboration patterns in animals tolerized by CD4-targeted therapy compared with those rendered tolerant by putative regulatory Th2-like cells. The mechanism of tolerance in anti-CD4 mAb-treated hosts appears distinct from that operating in the absence of mAb, when the tolerant state is being transferred in an infectious manner to new cohorts of test recipients.

Type 2 helper T cell-type cytokines and the development of "infectious" tolerance in rat cardiac allograft recipients

CD4-targeted therapy with a nondepleting RIB-5/2 mAb abrogates accelerated (< 36 h) rejection in presensitized LEW rats and results in permanent acceptance of LBNF1 cardiac allografts in conjunction with the features of infectious tolerance. This study examined the role and functional significance of the Th1 and Th2 cytokine network and systemic host allospecific Ab (allo-Ab) responses in the development of the infectious tolerance pathway in this model. Long term survival of cardiac transplants in rats treated with the tolerizing RIB-5/2 mAb regimen was accompanied by profound depression of Th1 (IL-2 and IFN-gamma) and Th2 (IL-4, IL-10) cytokines at the graft site, as shown by competitive template reverse transcription-PCR and immunohistochemistry. In contrast, the expression of Th2-type cytokines was selectively up-regulated after transfer of infectious tolerance by spleen cells into new generations of primary and secondary test recipients. Donor-specific circulating IgM allo-Ab responses were diminished throughout, and the switch from IgM to IgG allo-Ab was completely prevented in tolerant hosts, as shown by flow cytometry. The demonstration that treatment with cytolytic anti-CD4, but not anti-CD8, mAb recreated rejection of test cardiac allografts with simultaneous down-regulation of IL-4 mRNA/protein expression underlines the importance of this cytokine in the development of infectious tolerance. Hence, this report documents distinct cytokine elaboration patterns in animals tolerized by CD4-targeted therapy compared with those rendered tolerant by putative regulatory Th2-like cells. The mechanism of tolerance in anti-CD4 mAb-treated hosts appears distinct from that operating in the absence of mAb, when the tolerant state is being transferred in an infectious manner to new cohorts of test recipients.

Upstream and downstream of erythroid transcription factor GATA-1

All mature blood lineages in the peripheral circulation are derived from pluripotent haematopoietic stem cell. Progressive lineage-restriction of this stem cell is executed, in part, by the interplay and cross-talk between a host of lineage-restricted as well as ubiquitous transcription factors. To elucidate the regulatory mechanisms underlying the erythroid gene regulation, it is essential to understand how individual transcription factors contribute to the regulation of specific target genes, and how these erythroid transcription factor genes are regulated in turn. These key issues of mammalian development have been addressed by examining the activities controlling the prototype transcription factor, GATA-1. The transcriptional regulation of GATA-1 has been intensively investigated, thereby leading to the identification of its developmental stage-specific regulatory sequences. Loss-of-function mutant animals, combined with specific marking of the primitive and definitive erythroid lineages have also shed new insight into how GATA-1 activity is required in vivo at specific developmental stages. Procedures have also been developed for ascertaining whether or not the GATA-1 protein actually binds in vivo to regulatory GATA motifs in candidate target genes. Application of a similar multifaceted approach should enable investigators to examine the physiological roles that any transcription factor might play in vivo during the differentiation of any well defined cell lineage.

Conserved structure, regulatory elements, and transcriptional regulation from the GATA-1 gene testis promoter

Transcription factor GATA-1 was first identified in erythroid cells, but was later shown to also be expressed in Sertoli cells of the mouse testis. GATA-1 transcription in testis initiates from a different first exon (exon IT) than the erythroid mRNA (transcribed from exon IE). To begin to address the question of how expression of GATA-1 might be differentially regulated in Sertoli and erythroid cells, we have cloned and determined the structure of the IT promoters of both the rat and mouse GATA-1 genes. The transcription regulatory mechanism(s) controlling the synthesis of exon IT-derived mRNA was investigated by transfection of wild-type and mutant reporter genes, with and without co-transfected GATA factor expression plasmids, into either fibroblasts or Sertoli cell lines. Two GATA binding sites in the IT promoter were found to be required for GATA factor-mediated activation in fibroblasts: GATA-IT-directed reporter gene expression was activated only after co-transfection with GATA-1, implying that transcriptional activation of GATA-1 in the testis might be at least partially mediated through these GATA regulatory elements. We also found that the endogenous GATA-1 gene was silent in primary culture and two different Sertoli cell lines, and that the repression of co-transfected GATA-1 reporter genes could not be relieved by forced expression of GATA-1 in Sertoli cells. Thus the GATA-IT promoter may be under the control of a regulatory network in Sertoli cells which involves both positive and negative regulation of transcription, and conserved GATA motifs found in the IT promoter may be required for transducing these effects.

A case of Sjögren's syndrome associated with Sweet's syndrome

We report a case of Sjögren's syndrome whose clinical course had been indolent until the patient presented with Sweet's syndrome (acute febrile neutrophilic dermatosis). This patient showed renal failure and renal tubular acidosis. Sweet's syndrome resolved within 3 weeks without corticosteroid therapy. Renal biopsy findings were consistent with interstitial nephritis. His renal manifestations responded to corticosteroid therapy and the renal function remained stable during 6 years follow-up without recurrence of Sweet's syndrome. Although close association of both syndromes is already known, in our case Sjögren's syndrome may have been exacerbated by occurrence of Sweet's syndrome.

Effects of clobenpropit (VUF-9153), a histamine H3-receptor antagonist, on learning and memory, and on cholinergic and monoaminergic systems in mice

The effects of clobenpropit (VUF-9153), a potent histamine H3-receptor antagonist, on a scopolamine-induced learning deficit in the step-through passive avoidance test was studied in mice. Clobenpropit (10 and 20 mg/kg) alone showed a tendency to ameliorate the scopolamine-induced learning deficit, and clobenpropit (10 mg/kg) in combination with zolantidine (20 mg/kg), a histamine H2-receptor antagonist, ameliorated the scopolamine-induced effect. This ameliorating effect was antagonized by (R)-alpha-methylhistamine (20 mg/kg), a histamine H3-receptor agonist and pyrilamine (20 mg/kg), a histamine H1-receptor antagonist, suggesting that clobenpropit in combination with zolantidine showed the ameliorating effect via histamine H3 receptors and/or histamine H1 receptors. We also studied the effects of clobenpropit on cholinergic and monoaminergic systems. Clobenpropit did not show any significant effect on these neuronal systems except the activation of noradrenergic system. The present results suggest that the effect of clobenpropit might be partially involved with the activation of noradrenergic system, and the histaminergic system may play certain important roles in learning and memory.

Presynaptic calcium current modulation by a metabotropic glutamate receptor

Metabotropic glutamate receptors (mGluRs) regulate transmitter release at mammalian central synapses. However, because of the difficulty of recording from mammalian presynaptic terminals, the mechanism underlying mGluR-mediated presynaptic inhibition is not known. Here, simultaneous recordings from a giant presynaptic terminal, the calyx of Held, and its postsynaptic target in the medial nucleus of the trapezoid body were obtained in rat brainstem slices. Agonists of mGluRs suppressed a high voltage-activated P/Q-type calcium conductance in the presynaptic terminal, thereby inhibiting transmitter release at this glutamatergic synapse. Because several forms of presynaptic modulation and plasticity are mediated by mGluRs, this identification of a target ion channel is a first step toward elucidation of their molecular mechanism.

Centrally acting histamine H1 antagonists promote the development of amygdala kindling in rats

We studied the effect of histamine H1 antagonists on the development of amygdala kindling, an experimental model of epilepsy, in rats. The centrally acting histamine H1 antagonists including pyrilamine (mepyramine) and ketotifen showed an acceleration in the rate of electrical stimulation to develop fully kindled convulsive seizures. On the contrary, epinastine, a histamine H1 antagonist which scarcely enters the brain, showed no acceleration. These findings suggest that the central histaminergic neuron system plays an inhibitory role on the seizure development through central histamine H1 receptors.

Effects of dopamine antagonists on neuronal histamine release in the striatum of rats subjected to acute and chronic treatments with methamphetamine

In this study, we examined the changes in neuronal histamine (HA) release in the rat striatum after acute and repeated administration of methamphetamine (METH). We studied the regulation of METH-induced HA release by dopamine receptors and the relationship between METH-induced HA release and stereotyped behavior. Acute administration of METH (1 mg/kg) significantly increased HA release 60 min later. Pretreatments with the dopamine D2 antagonists sulpiride and haloperidol blocked the METH-induced increase of HA release, whereas pretreatment with a dopamine D1 antagonist, SCH23390, did not. Moreover, repeated administration of METH (3 mg/kg) greatly enhanced the METH-induced increase of HA release 60, 80, 100, 120 and 180 min after rechallenge of METH (1 mg/kg). Repeated treatment with haloperidol and METH blocked the increase of HA release induced by the rechallenge of METH. The METH-induced increase of HA release was still found after the METH-induced stereotyped behavior decreased in both acute and repeated administrations of METH. These findings suggest that the METH-induced HA release in the striatum is controlled by dopamine D2 receptors and may play an important inhibitory role in the METH-induced stereotyped behavior. Furthermore, a persistent change in the HA neuron system through DA neurotransmission may be partially responsible for the METH-induced behavioral sensitization.

Effects of theophylline in p-chlorophenylalanine-treated mice in a light/dark test

The effects of theophylline were examined in a light/dark test in p-chlorophenylalanine (PCPA)-treated mice to investigate serotonergic contribution to its effects. Three consecutive treatments with PCPA (200 mg/kg once daily) barely affected parameters in the light/ dark test. In vehicle- and PCPA-treated mice, theophylline (100 mg/kg) significantly decreased time spent in the light zone, which suggested its anxiogenic-like activity. In PCPA-treated mice, theophylline (50 mg/kg) also tended to decrease the time spent in the light zone. The effects of theophylline on the contents of monoamines and their metabolites in the brains of vehicle- and PCPA-treated mice were also investigated. Treatment with PCPA significantly decreased the contents of serotonin (5-HT) and its metabolite, as well as the contents of the metabolites of noradrenaline (NA) and dopamine (DA). Theophylline increased the metabolites of 5-HT, NA and DA in the brains of vehicle-treated mice. The increases produced by theophylline in the metabolites of NA and 5-HT were extinguished in PCPA-treated mice. Behavioral and biochemical data in the present study demonstrate that theophylline-induced anxiogenic-like activity was not mediated by serotonergic neuronal systems and that NAergic neuronal systems also might not contribute to the activity.

The effect of methamphetamine on histamine level and histidine decarboxylase activity in the rat brain

To examine biochemical changes in the brain histamine (HA) neuron system after acute and chronic administrations of methamphetamine (MAP), HA levels and histidine decarboxylase (HDC) activities in the rat cortex, striatum, diencephalon, midbrain, pons-medulla and cerebellum were measured. In the cortex and striatum, acute administration of MAP (1 and 3 mg/kg) increased HA levels 1 h later. Acute administration of MAP (10 mg/kg) and chronic administration of MAP (3 mg/kg) for 21 days also increased HA levels and HDC activities in the cortex and striatum I h after the last injection. In the diencephalon, acute administration of MAP (3 and 10 mg/kg) and chronic administration of MAP (3 mg/kg) decreased HA level 1 h after the last injection, but chronic administration of MAP (3 mg/kg) increased HDC activity 1 h after the last injection. There were no significant changes in HA levels and HDC activities in other regions after acute and chronic administrations of MAP. These findings suggest that MAP may activate the brain HA neuron system, although MAP acts more strongly on the cortex and striatum than on the diencephalon.

Induction of "infectious" tolerance to MHC-incompatible cardiac allografts in CD4 monoclonal antibody-treated sensitized rat recipients

LBNF1 heart grafts are rejected in an accelerated manner within 36 h by LEW rats that have been sensitized with Brown Norway rat skin grafts on day -7. Treatment with RIB-5/2, a CD4-nondepleting mAb (10 doses of 5 mg/rat/day, i.v., from day -7 to day +21) abrogated rejection at &lt;36 h and produced indefinite (&gt;200 days) cardiac allograft survival. Transplantation tolerance in this model developed within several weeks, and during the maintenance phase (&gt;100 days) it was associated with diminished host circulating allo-Ab responses and induction of peripheral allospecific T cell unresponsiveness both in vitro and in vivo. Tolerant cells in mAb-treated hosts could disable naive or alloimmune cells, so that they failed to trigger graft rejection. Moreover, donor-specific and organ-nonspecific tolerance could be adoptively transferred by spleen cells alone into new sets of primary (100%) and secondary (&gt;40%) test recipients. CD4+ T cells were instrumental for the induction of such readily transferable tolerance. The first and second generation suppressive regulatory cells were also critical for the inhibition of allograft recognition by normal or even alloimmune cells. Hence, the features of an "infectious" tolerance pathway to minor histocompatibility-mismatched skin grafts, originally described in thymectomized mice, may be applied to the euthymic primed rats rendered tolerant to fully MHC-incompatible vascularized organ allografts. Such reprogramming of host cell-mediated regulatory mechanisms following CD4-targeted therapy adds to our appreciation of the potential utility and applicability of infectious tolerance in transplant recipients treated with a perioperative course of CD4-targeted monotherapy.

Developmental expression of cytochrome P450S within intrasplenically transplanted fetal hepatocytes

Fetal hepatocytes were harvested at day 20 of gestation from spontaneously hypertensive rats (SHR) and then transplanted into recipient adult SHR spleens. Morphological examination of the recipient spleens revealed that, after 4 and 10 wk, large masses of hepatocytes were present in the red pulp with apparent cord-like structures. Larger batches of hepatocytes were observed in the spleens at 10 wk after than at 4 wk after transplantation. Of major significance was the fact that hepatocyte transplanted spleens were able to express several families of cytochrome P450 (cyto P450) proteins 2-10 wk after transplantation. Immunochemical determinations revealed that cytos P450 IA1, P450 IIB1, P450 p, P450 HLp, and P450 LA omega could be detected without any prior induction. All were intensely expressed 6 wk after transplantation; however, P450 IA1 and P450 IIB1 did not appear to be expressed by 2 wk after transplantation. Although cytos P450 p and P450 HLp did not appear to be expressed by 10 wk after transplantation, they were induced with dexamethasone at that time. Cyto P450 LA omega and peroxisomal acyl CoA oxidase were expressed 6 wk after transplantation in a 70% hepatectomized host. These results demonstrate that fetal hepatocytes can be successfully transplanted into the spleens of recipients and that the fetal hepatocytes appear to grow and develop cyto P450 metabolizing systems.

Effect of inferior vena cava occlusion on left ventricular end-systolic pressure-volume relations in intact canine hearts--modulation by the autonomic nervous system

The effect of inferior vena cava occlusion (IVCO) on end-systolic pressure-volume relations (ESPVR) of the left ventricle was studied in intact canine hearts. In 12 anesthetized open-chest dogs, left ventricular (LV) pressure and volume were measured simultaneously using a microtip catheter and a conductance catheter, respectively. ESPVR was constructed from LV pressure-volume loops during IVCO (10 sec) and subsequent IVCO release under 5 conditions: control, after righ or left cardiac sympathetic nerve (CSN) stimulation, bilateral vagotomy (VAT), and both VAT and bilateral CSN resection. Emax in IVCO release was significantly greater than that in IVCO in the control state. Following right or left CSN stimulation, Emax was increased increased in both IVCO and IVCO release, with the same hysteretic change in Emax. With VAT, however, no hysteretic change was observed because Emax was the same in IVCO and IVCO release. After VAT and CSN resection, Emax was decreased in both IVCO and IVCO release, and again no hysteretic change was observed. These data imply that a sudden decrease in venous return into the heart induces a decrease in afferent vagal nerve activity, and thus increases efferent CSN activity, resulting in enhanced myocardial contractility.

Multilocational hepatocyte transplantation for treatment of congenital ascorbic acid deficiency rats

We attempted multilocational hepatocyte transplantation (HCTx) including hepatocyte-bearing polyurethane foam (PUF) to treat congenitally ascorbic acid (AsA) biosynthetic enzyme-deficient (ODS-od/od) rats. Hepatocytes isolated from the liver of congeneic rats were transplanted into the portal vein (Pv), spleen (Sp), omentum (Om), and mesentery (Ms). Hepatocyte-bearing PUF was transplanted into the Om and Ms. Experimental groups were divided into four groups (group I; Pv + Sp, group II; Pv + Sp + Om + Ms, group III; Pv + Sp + hepatocyte-bearing PUF, group IV; control). The average serum AsA level of the surviving rats in group II and III was significantly higher than that in group I 3 mo after HCTx. Histological examination showed small foci of surviving hepatocytes in the Om and Ms tissues and in the connective tissue in the PUF. ODS-od/od rats survived for a long time by multilocational HCTx.

Induction of "infectious" tolerance to MHC-incompatible cardiac allografts in CD4 monoclonal antibody-treated sensitized rat recipients

LBNF1 heart grafts are rejected in an accelerated manner within 36 h by LEW rats that have been sensitized with Brown Norway rat skin grafts on day -7. Treatment with RIB-5/2, a CD4-nondepleting mAb (10 doses of 5 mg/rat/day, i.v., from day -7 to day +21) abrogated rejection at <36 h and produced indefinite (>200 days) cardiac allograft survival. Transplantation tolerance in this model developed within several weeks, and during the maintenance phase (>100 days) it was associated with diminished host circulating allo-Ab responses and induction of peripheral allospecific T cell unresponsiveness both in vitro and in vivo. Tolerant cells in mAb-treated hosts could disable naive or alloimmune cells, so that they failed to trigger graft rejection. Moreover, donor-specific and organ-nonspecific tolerance could be adoptively transferred by spleen cells alone into new sets of primary (100%) and secondary (>40%) test recipients. CD4+ T cells were instrumental for the induction of such readily transferable tolerance. The first and second generation suppressive regulatory cells were also critical for the inhibition of allograft recognition by normal or even alloimmune cells. Hence, the features of an "infectious" tolerance pathway to minor histocompatibility-mismatched skin grafts, originally described in thymectomized mice, may be applied to the euthymic primed rats rendered tolerant to fully MHC-incompatible vascularized organ allografts. Such reprogramming of host cell-mediated regulatory mechanisms following CD4-targeted therapy adds to our appreciation of the potential utility and applicability of infectious tolerance in transplant recipients treated with a perioperative course of CD4-targeted monotherapy.

Tissue factor pathway inhibitor production by human mesangial cells in culture

Fibrin formation within the glomeruli has been observed in various forms of human and experimental glomerulonephritis and it may play an important role in progressive glomerular injury. Furthermore it has been hypothesized that glomerular fibrin deposition may occur through activation of either the intrinsic or extrinsic coagulation pathway. It has been demonstrated that a procoagulant activity (PCA) which is compatible with tissue factor is present in the glomeruli and becomes increased in human proliferative glomerulonephritis and in animal models of nephritis. Tissue factor pathway inhibitor (TFPI) regulates the extrinsic pathway of blood coagulation through its ability to inhibit tissue factor activity. TFPI is present in plasma and in platelets, and it is now thought to be produced mainly by endothelial cells. We examined whether human mesangial cells (HMC) could produce TFPI and attempted to clarify regulatory factors which affect TFPI production. Cultured HMC were used and TFPI in the cell supernatants was measured by ELISA using a specific antibody. Cultured HMC showed the production of TFPI. Immunoblot analysis revealed 40 kD protein of TFPI. The concentration of TFPI was significantly increased following the incubation with thrombin and heparin, including low molecular weight heparin, in a dose- and time-dependent manner. However, fetal calf serum, phorbol myristate acetate, lipopolysaccharide, IL-1 beta and tissue factor did not stimulate TFPI synthesis. Our data show that cultured HMC have the ability to produce TFPI which inhibits fibrin formation. It is possible that thrombin-induced enhancement of TFPI synthesis may be caused by the autoregulatory system of blood coagulation and that with heparin it may represent another anticoagulatory effect of heparin.

Functional correlation of NMDA receptor epsilon subunits expression with the properties of single-channel and synaptic currents in the developing cerebellum

NMDA receptor (NMDAR) subunits epsilon 1-epsilon 4 are expressed differentially with respect to brain region and ontogenic period, but their functional roles still are unclear. We have compared an epsilon 1 subunit-ablated mutant mouse with the wild-type to characterize the effect of epsilon subunit expression on NMDAR-mediated single-channel currents and synaptic currents of granule cells in cerebellar slices. Single-channel and Western blot analyses indicated that the epsilon 2 subunit disappeared gradually during the first postnatal month in both wild-type and mutant mice. Concomitantly, the voltage-dependent Mg2+ block of NMDAR-mediated EPSCs (NMDA-EPSCs) was decreased. Throughout the developmental period studied, postnatal day 7-24 (P7-P24), the decay time course of NMDA-EPSCs in epsilon 1 mutant (-/-) mice was slower than in wild-type mice. We suggest that the expression of the epsilon 3 subunit late in development is responsible for a reduction in the sensitivity of NMDA-EPSCs to block by extracellular Mg2+ and that receptors containing the epsilon 1 subunit determine the fast kinetics of the NMDA-EPSCs.