Functional folate receptor beta-expressing macrophages in osteoarthritis synovium and their M1/M2 expression profiles.

OBJECTIVE: The distribution of folate receptor (FR)-ß+ macrophages and their M1/M2 expression profiles were examined in osteoarthritis (OA) synovial tissues, and compared to those in rheumatoid arthritis (RA) synovial tissues and CD163+ macrophages in both OA and RA synovial tissues. METHOD: The phenotypes and fluorescein isothiocyanate (FITC)-folate uptake of FR-ß+ synovial macrophages were analysed by flow cytometry. The distribution of FR-ß+ macrophages in OA and RA synovial tissues was examined by immunofluorescent microscopy. Tumour necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS), interleukin (IL)-10, and transforming growth factor (TGF)-ß expression in FR-ß+ macrophages was detected by double-immunostaining in both OA and RA synovial tissues. RESULTS: FR-ß+ macrophages were predominantly present in the synovial lining layer in OA patients. The proportion of CD163-FR-ß+ cells in synovial mononuclear cells (MNCs) was increased in OA compared to RA synovial tissues. FR-ß(high) macrophages from OA synovial tissues represented the majority of folic acid-binding cells. Although FR-ß+ or CD163+ macrophages in the synovial tissues of OA and RA patients expressed a mixed pattern of M1 and M2 macrophage markers, there were more M2 markers expressing synovial macrophages in OA than in RA patients. CONCLUSIONS: The distribution and M1/M2 expression profiles of FR-ß+ synovial macrophages were different between OA and RA synovial tissues. Thus, the findings underscore that the M1/M2 paradigm using surface markers FR-ß and CD163 is an oversimplification of macrophage subsets. Functional FR-ß present on OA synovial macrophages provides a potential tool for the diagnosis and treatment of OA.

Intracerebroventricular injection of L-proline and D-proline induces sedative and hypnotic effects by different mechanisms under an acute stressful condition in chicks.

The central effects of L-proline, D-proline and trans-4-hydroxy-L-proline were investigated by using the acute stressful model with neonatal chicks in Experiment 1. Sedative and hypnotic effects were induced by all compounds, while plasma corticosterone release under isolation stress was only attenuated by L-proline. To clarify the mechanism by which L-proline and D-proline induce sedative and hypnotic effects, the contribution of the strychnine-sensitive glycine receptor (glycine receptor) and N-methyl-D-aspartate glutamate receptor (NMDA receptor) were further investigated. In Experiments 2-3, the glycine receptor antagonist strychnine was co-injected intracerebroventricular (i.c.v.) with L-proline or D-proline. The suppression of isolation-induced stress behavior by D-proline was attenuated by strychnine. However, the suppression of stress behavior by L-proline was not attenuated. In Experiment 4, the NMDA receptor antagonist (+)-MK-801 was co-injected i.c.v. with L-proline. The suppression of stress behavior by L-proline was attenuated by (+)-MK-801. These results indicate that L-proline and D-proline differentially induce sedative and hypnotic effects through NMDA and glycine receptors, respectively.

N-Methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors involved in the induction of sedative effects under an acute stress in neonatal chicks.

Glutamate, an excitatory amino acid, acts at several glutamate receptor subtypes. Recently, we reported that central administration of glutathione induced hypnosis under stressful conditions in neonatal chicks. Glutathione appears to bind to the N-methyl-D-aspartate (NMDA) receptor. To clarify the involvement of each glutamate receptor subtype during stressful conditions, intracerebroventricular (i.c.v.) injection of several glutamate receptor agonists was given to chicks under social separation stress. Glutamate dose-dependently induced a hypnotic effect. NMDA, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) and kainate are characterized as ionotropic glutamate receptors (iGluRs). Although NMDA also induced a sedative effect, [corrected] the potency of NMDA for sleep-like behavior [corrected] was less than that of glutamate. AMPA tended to decrease distress vocalizations induced by acute stress and brought about a sedative effect. Kainate and (S)-3, 5-dehydroxyphenylglycine, which is a metabotropic glutamate receptor agonist, had no influence on chick behavior. Thus, it is suggested that the iGluRs, NMDA and AMPA, are important in inducing hypnosis and sedation under acute stress in chicks.

Expansion of a unique macrophage subset in rheumatoid arthritis synovial lining layer.

The Z39Ig protein (complement receptor for C3b and iC3b) is expressed on resident tissue macrophages in various tissues. This study was undertaken to examine the distribution of Z39Ig+cells and their phenotypic features in rheumatoid arthritis (RA) synovium, in comparison with those of osteoarthritis (OA) and psoriatic arthritis (PsA) synovium. Monoclonal anti-Z39Ig antibody was produced by immunizing Z39Ig transfected murine pre B cells and used for the identification of Z39Ig+cells. Z39Ig+cells were further stained with antibodies to macrophages, fibroblast-like synoviocytes, complement receptors and dendritic cells by using the double immunostaining method in normal, RA, OA and PsA synovium. RA synovial mononuclear cells were double-stained using anti-Z39Ig and anti-CD11c antibodies and sorted into Z39Ig+CD11c+cells and Z39Ig+CD11c-cells. These cell populations were then analysed by electron microscopy. The expression of the Z39Ig protein was limited to intimal macrophages in normal, RA, OA and PsA synovium. The numbers of Z39Ig+CD11c+cells and the ratios of Z39Ig+CD11c+cells to Z39Ig+cells were increased in the synovial lining layer of RA as compared with those of OA and PsA. The ultrastructural analysis of Z39Ig+CD11c+cells showed the character of macrophages with many secondary lysosomes and swelling of mitochondria. Z39Ig+ cells appeared to be useful for identification of resident tissue macrophages in normal synovium and the corresponding macrophages in the synovial lining layer of inflammatory arthritis. Expansion of Z39Ig+CD11c+cells was characteristic of RA synovial lining layer.

Central L-arginine reduced stress responses are mediated by L-ornithine in neonatal chicks.

Recently, we observed that central administration of L-arginine attenuated stress responses in neonatal chicks, but the contribution of nitric oxide (NO) to this response was minimal. The sedative and hypnotic effects of L-arginine may be due to L-arginine itself and/or its metabolites, excluding NO. To clarify the mechanism, the effect of intracerebroventricular (i.c.v.) injection of L-arginine metabolites on behavior under social separation stress was investigated. The i.c.v. injection of agmatine, a guanidino metabolite of L-arginine, had no effect during a 10 min behavioral test. In contrast, the i.c.v. injection of L-ornithine clearly attenuated the stress response in a dose-dependent manner, and induced sleep-like behavior. The L-ornithine concentration in the telencephalon and diencephalon increased following the i.c.v. injection of L-arginine. In addition, several free amino acids including L-alanine, glycine, L-proline and L-glutamic acid concentrations increased in the telencephalon. In conclusion, it appears that L-ornithine, produced by arginase from L-arginine in the brain, plays an important role in the sedative and hypnotic effects of L-arginine observed during a stress response. In addition, several other amino acids having a sedative effect might partly participate in the sedative and hypnotic effects of L-arginine.

Intracerebroventricular injection of L-arginine induces sedative and hypnotic effects under an acute stress in neonatal chicks.

L-arginine participates in many important and diverse biochemical reactions associated with the normal physiology of the organism. In the present study, we investigated the effect of central administration of L-arginine on the stress response and its mechanism in neonatal chicks. Intracerebroventricular (i.c.v.) injection of L-arginine clearly attenuated the stress response in a dose-dependent manner, and induced sleep-like behavior during 10 min. To clarify the mechanism by which L-arginine induces sedative and hypnotic effects in chicks, we investigated the effects of nitric oxide (NO) synthase (NOS) inhibitors on L-arginine-induced sedative and hypnotic effects, and as well as the effects of a NO donor. L-Arginine-induced (1.9 micromol) sedative and hypnotic effects were attenuated by i.c.v. co-injection with a non-selective NOS inhibitor N(G)-nitro-L-arginine methyl ester HCl (400 nmol). In addition, the effects of L-arginine were slightly attenuated by the inactive isomer of the NOS inhibitor N(G)-nitro-D-arginine methyl ester HCl (400 nmol). The i.c.v. injection of 3-morpholinosylnomine hydrochloride, a spontaneous NO donor, had little effect on postures. The i.c.v. injection of L-arginine had no effect on NOx concentration at various brain sites. These results suggested that the contribution of NO generation via NOS may be low in the sedative and hypnotic actions of L-arginine. Therefore, L-arginine and/or its metabolites, excluding NO, may be necessary for these actions.

Relationships between the sedative and hypnotic effects of intracerebroventricular administration of L-serine and its metabolites, pyruvate and the derivative amino acids contents in the neonatal chicks under acute stressful conditions.

Intracerebroventricular (i.c.v.) injection of L-serine was shown to have sedative and hypnotic effects on neonatal chicks under acute stressful conditions. To clarify the central mechanism of these effects of L-serine, two experiments were done. First, we focused on the glycogenic pathway in which L-serine is converted into pyruvate and finally glucose. I.c.v. administration of pyruvate (0.84 micromol) did not induce any behavioral and endocrinological changes, while L-serine and glucose triggered sedative and hypnotic effects. Secondly, the relationship between the sedation by L-serine and the metabolism into other amino acids which have sedative effects was investigated in the telencephalon and diencephalon. In both brain areas, a dose-dependent increase was seen in L-serine, although other amino acids were not changed. In the present study, it was concluded that the sedative action of L-serine was not due to the action of its metabolite pyruvate, or to the action of other amino acids.