Neovascularization of transplanted central nervous tissue suspensions: an immunohistochemical study with laminin

Neovascularization of the dissociated central nervous tissue transplanted into the lateral ventricle of the rat was studied using laminin immunohistochemistry. A very high immunoreactive response to laminin was demonstrated in the presumably newly formed vessels within the transplants and the graft-host borders. The growing tips and fine spike-like sprouts called 'streamers' were also highly stained with laminin immunoreactivity. In contrast, laminin immunoreactivity was negligible in the vessels in the host brain. Therefore, these results indicate that laminin may be utilized as a marker for the newly formed vessels in neural transplantations.     

ABC proteins: key molecules for lipid homeostasis

Forty-nine ABC protein genes exist on human chromosomes. Eukaryotic ABC proteins were originally recognized as drug efflux pumps involved in the multidrug resistance of cancer cells. However, it is now realized that one of their major physiological roles is cellular lipid transport and homeostasis, and their dysfunction is often associated with human diseases. ABCA1 and ABCA7 mediate the apolipoprotein-dependent formation of a high-density lipoprotein–cholesterol complex. ABCA3 is indispensable for pulmonary surfactant secretion. ABCG5 and ABCG8 are involved in the secretion of plant sterols and cholesterol into bile. However, the primary substrates and mechanism of action of these ABC proteins have not been precisely defined. In this review article, we first describe the general structure and functions of eukaryotic ABC proteins. The current model of ABCA1 functionality is then explained based on studies on a topological model, subcellular localization, apoA-I dependence of HDL formation, functional defects of Tangier disease mutants, and ATP hydrolysis of purified ABCA1. ABCA1 is supposed to function as a transporter of lipids as well as a receptor for apoA-I. ABCA3 is likely involved in accumulating phospholipids and cholesterol in lamellar bodies and in generating multivesicular structures.     

α2-Macroglobulin secretion enhanced in rat hepatocytes by partially characterized factor from Kupffer cells

Isolated rat Kupffer cells produced a factor which stimulated the synthesis of ₂-macroglobulin (2M) in primary cultured rat hepatocytes. Although Kupffer cells placed in culture produced the factor without stimulation by lipopolysaccharide (LPS), the LPS-stimulated cells produced larger amounts of the factor. On the other hand, the production of the factor was inhibited by addition of actinomycin D. The induction of2M synthesis by cultured hepatocytes was enhanced in the presence of dexamethasone (Dex), in that hepatic synthesis of2M increased by addition of the factor alone and with Dex 1.5 and three- to four-fold, respectively. The factor was nondialyzable and stable at 60°C for 30 min. When the factor was fractionated using the molecular sieve method, the activity recovered in the fraction had a molecular weight of over 30,000.     

Regulation of Th2 cell differentiation by mel-18, a mammalian polycomb group gene

Polycomb group (PcG) gene products regulate homeobox gene expression in Drosophila and vertebrates and also cell cycle progression of immature lymphocytes. In a gene-disrupted mouse for polycomb group gene mel-18, mature peripheral T cells exhibited normal anti-TCR-induced proliferation; however, the production of Th2 cytokines (IL-4, IL-5, and IL-13) was significantly reduced, whereas production of IFNgamma was modestly enhanced. Th2 cell differentiation was impaired, and the defect was associated with decreased levels in demethylation of the IL-4 gene. Significantly, reduced GATA3 induction was demonstrated. In vivo antigen-induced IgG1 production and Nippostrongylus brasiliensis-induced eosinophilia were significantly affected, reflecting the deficit in Th2 cell differentiation. Thus, the PcG gene products play a critical role in the control of Th2 cell differentiation and Th2-dependent immune responses.     

Increase in the number of detectable preoptic glutamic acid decarboxylase 67-immunoreactive cells in immature male rats

Gonadotropin-releasing hormone (GnRH) neurons are mainly located in the anterior preoptic area (aPOA) and gamma-aminobutyric acid (GABA) is known as a potent regulator of the GnRH neurons. To examine the development of the GABAergic system in the aPOA, immunocytochemistry of glutamic acid decarboxylase 67 (GAD(67)) was performed in immature (postnatal d16, d25 and d30) and mature (postnatal 10 weeks) male rats. All immunocytochemical procedures were simultaneously performed. In the lateral part of the aPOA, the detectable number of GAD(67)-immunoreactive cells was small in the d16 group, but significantly increased in the d25, d30 and mature groups, up to 2.7, 4.8 and 5.7 times the number in the d16 group, respectively. In the diagonal band of Broca (DBB), the number was also small in the d16 group, and significantly increased in the d25, d30 and mature groups upto 1.8, 2.2 and 2.8 times the number in the d16 group, respectively. However, in the cingulate cortex, no significant developmental change was observed. These results suggest that the development of the GABAergic system in the lateral aPOA and the DBB occurs before sexual maturation of male rats.     

CD69-null mice protected from arthritis induced with anti-type II collagen antibodies

CD69, known as an early activation marker antigen on T and B cells, is also expressed on platelets and activated neutrophils, suggesting certain roles in inflammatory diseases. In order to address the role of CD69 in the pathogenesis of arthritis, we established CD69-null mice. CD69-null mice displayed a markedly attenuated arthritic inflammatory response when injected with anti-type II collagen antibodies. Cell transfer experiments with neutrophils, but not T cells or spleen cells, from wild-type mice into CD69-null mice restored the induction of arthritis. These results indicate a critical role for CD69 in neutrophil function in arthritis induction during the effector phase. Thus, CD69 would be a possible therapeutic target for arthritis in human patients.     

Effects of estrogen and progesterone on the expression of connexin-36 mRNA in the suprachiasmatic nucleus of female rats

In rat, helium pressures induce locomotor and motor activity which requires dopaminergic and N-methyl-D-aspartate (NMDA) receptor activities at striatal level. However, biochemical studies have suggested that pressure exposure may increase striatal glutamate level. We used microdialysis technique to study the effects of pressure on glutamate level in the striatum and the effects of local administration of D1 (SCH23390) or D2 (sulpiride) on these changes. Pressures increase both glutamate and glutamine levels in striatal microdialysates. Administration of sulpiride (1 microM) or SCH23390 (1 microM) by reverse microdialysis did not affect significantly pressure induced glutamate increase. So, protective effects of D1 and D2 antagonists against locomotor and motor hyperactivity (LMA) are probably independent of the processes involved in the striatal glutamate increase evoked by pressure.     

Myelin Degeneration in Multiple System Atrophy Detected by Unique Antibodies

A rabbit antiserum (anti-EP), induced against a synthetic peptide corresponding to residues 68 to 86 of guinea pig myelin basic protein, powerfully immunostained abnormal-appearing oligodendrocytic processes and cell bodies in demyelinating areas associated with multiple system atrophy (MSA). However, as we reported previously, the antiserum, which is highly specific for the sequence QDENPVV corresponding to human myelin basic protein residues 82 to 88, failed to recognize any structures in normal human brain. QD-9, a mouse monoclonal antibody raised against human myelin basic protein residues 69 to 88, which also recognizes specifically the epitope QDENPVV, gave the same results as did anti-EP. The unusual epitope recognized by anti-EP/QD-9 antibodies appears to be accessible in areas of myelin degeneration, and the antibodies have been shown to detect such areas in multiple sclerosis and infarcted brains. These antibodies detect myelin degeneration more widely than previous conventional methods. The present study emphasizes the importance of myelin degeneration in the pathogenesis of multiple system atrophy.     

Effects of hypoxia and tumor necrosis factor-alpha on production of plasminogen activator inhibitor-1 in human proximal renal tubular cells

Chronic hypoxia has been newly proposed as a common mechanism of tubulointerstitial fibrosis in the progression of various chronic inflammatory renal diseases, where PAI-1 plays an important role in the accumulation of extracellular matrix (ECM) through inhibition of plasmin-dependent ECM degradation. In the present study, we investigated the presence of PAI-1 in renal tubular cells by immunostaining renal biopsy samples. We also closely examined the effects of hypoxia and TNF-alpha on PAI-1 expression in cultured human proximal renal tubular cells (HRCs). Confluent cells growth-arrested in DMEM for 24h were exposed to hypoxia (1% O2) and/or TNF-alpha at 10 ng/ml for 24 hours. Amounts of PAI-1 protein and mRNA after stimulation were measured by ELISA and TaqMan quantitative PCR, respectively and compared to those in cells incubated under control conditions (18% O2 without TNF-alpha). HIF-1alpha was demonstrated by immunoblot analysis. In crescentic glomerulonephritis, clusters of proximal tubules were specifically stained for PAI-1. Treatment of 24 hours with hypoxia, TNF-alpha and their combination induced a 2.7-fold, a 1.8-fold, and a 4.6-fold increase in PAI-1 protein secretion, and produced a 3.6-fold, a 3.3-fold, and a 12.1-fold increase at the PAI-1 mRNA level, respectively. Immunoblot analysis revealed that hypoxia-inducible factor-1alpha (HIF-1alpha) was markedly accumulated in the nuclear fraction after 16-hours exposure of HPTECs to hypoxia but not to TNF-alpha. In conclusion, hypoxia induces PAI-1 expression via remarkable nuclear accumulation of HIF-1alpha in HRCs. TNF-alpha can enhance this hypoxia-induced PAI-1 expression.