T cells are involved in the development of arthritis induced by anti-type II collagen antibody.

T cells play an important role in initiating autoimmune responses and maintaining synovial inflammation in rheumatoid arthritis. Although, anti-type II collagen antibody-induced arthritis (CAIA) is generally believed to be a T cell- and B cell-independent model, the detailed pathogenesis of CAIA remains unclear. In the present study, to elucidate the contribution of T cells to the pathogenesis of CAIA, we evaluated the effects of CTLA4 Ig and cyclosporin (CsA). Arthritis was induced in mice by intravenous injection of anti-type II collagen antibody followed by intraperitoneal injection of lipopolysaccharide. CTLA4 Ig was intraperitoneally administered and CsA was subcutaneously administered; then the severity of arthritis was evaluated by scoring the edema and erythema of paws and by measuring hind paw thickness. Paw samples were collected 12 days after the antibody injection, and the mRNA expression levels were analyzed by real-time quantitative polymerase chain reaction. Administration of CTLA4 Ig ameliorated the increases in arthritic score and paw thickness in the later phase, but not in the early phase of arthritis. CsA suppressed the increases in arthritic score and paw thickness in both the early and later phases of arthritis. CTLA4 Ig and CsA suppressed mRNA up-regulation of T-cell markers, CD3 and CD25, and immune response-related mediators, IFN-gamma and IL-12. They also suppressed the up-regulation of macrophage marker, F4/80, and proinflammatory cytokines, TNF-alpha, IL-1beta and IL-6. The results provide direct evidence that arthritis in this model is T-cell activation dependent.

Analysis of change patterns of microcomputed tomography 3-dimensional bone parameters as a high-throughput tool to evaluate antiosteoporotic effects of agents at an early stage of ovariectomy-induced osteoporosis in mice.

OBJECTIVES: The purposes of this study were to develop an osteoporosis model in a short period of 2 weeks after ovariectomy in mice and to investigate whether analysis of microcomputed tomography (muCT) 3-dimensional bone parameters could provide useful information on the mechanism of action of antiosteoporotic agents. MATERIALS AND METHODS: Mice were ovariectomized (OVX) or sham-operated, and the OVX mice were treated daily with 17beta-estradiol (E2), parathyroid hormone (PTH[1-34]), raloxifene, rolipram, or vehicle for 2 weeks. On day 14 post-OVX, the left femur bones were removed and then the distal metaphyseal bone was analyzed by both muCT and histomorphometry. RESULTS: The trabecular bone volume, thickness, number, and connectivity significantly decreased and the number of osteoclasts increased in OVX mice. Treatment of OVX animals with each of the 4 antiosteoporotic agents significantly increased the bone volume and improved the bone architecture. However, the improvement of trabecular thickness in the rolipram-treated group and that of cortical thickness in the PTH(1-34)-treated group were the most marked, whereas the improvement of connectivity in the rolipram-treated group was the least among the drug-treated groups. These different improving effects of agents on the bone parameters reflect the differential effects of these agents on bone formation and bone resorption. CONCLUSIONS: This study demonstrated the feasibility of evaluating the effect of the antiosteoporotic agents within 2 weeks after ovariectomy in mice. The muCT analysis may serve as a valuable tool, specifically in a high-throughput pharmacological screening test, offering useful information regarding the effects of test compounds on both bone resorption and formation.

Mesaconitine-induced relaxation in rat aorta: role of Na+/Ca2+ exchangers in endothelial cells.

Previously, we reported that mesaconitine, an aconite alkaloid, increased intracellular Ca(2+) concentration ([Ca(2+)](i)) level in endothelium and caused relaxation in rat aorta via nitric oxide production. In the present study, we investigated the mechanisms of increase in the [Ca(2+)](i) level induced by mesaconitine in rat aorta and in human umbilical vein endothelial cells (HUVECs). Treatment with the low Na(+) buffer delayed the 30 microM mesaconitine-, but not 10 microM acetylcholine-, induced relaxation in rat aorta. Treatments with an inhibitor of Na(+)/Ca(2+) exchangers (20 microM 3',4'-dichlorobenzamil) and a reversed mode (Ca(2+) influx) inhibitor of the exchangers (30 microM 2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methanesulfonate, KBR7943) showed similar effects. In HUVECs, 30 microM mesaconitine increased the [Ca(2+)](i) level in the presence of extracellular CaCl(2) and NaCl, and the response was inhibited by KBR7943. Mesaconitine increased intracellular Na(+) concentration level in HUVECs. The [Ca(2+)](i) response by mesaconitine was inhibited by 100 microM D-tubocurarine (an inhibitor of nicotinic acetylcholine receptors), but was not inhibited in the glucose-free buffer and by inhibitors of Na(+)/H(+) exchangers. These findings suggest that mesaconitine stimulated Ca(2+) influx via the Na(+)/Ca(2+) exchangers in endothelial cells and caused relaxation in the aorta. The possibility of D-tubocurarine-sensitive Na(+) channels as target(s) of mesaconitine is discussed.

Vasorelaxing effect of mesaconitine, an alkaloid from Aconitum japonicum, on rat small gastric artery: possible involvement of endothelium-derived hyperpolarizing factor.

Aconiti tuber, roots of aconite (Aconitum japonicum), has been used for centuries in Japan and China to increase peripheral body temperature. We previously reported that mesaconitine, an alkaloid from Aconitum japonicum, elicits endothelium-dependent and nitric oxide-mediated relaxation in isolated rat aorta. In the present study, we investigated the effect of mesaconitine on isolated rat small gastric arteries. Mesaconitine elicited a concentration-dependent (10, 30, 100 microM) vasorelaxation in isolated rat gastric artery precontracted with norepinephrine, which was resistant to N(omega)-nitro-L-arginine (L-NNA) (an inhibitor of nitric oxide synthase) and indomethacin (an inhibitor of cyclooxygenase). The L-NNA- and indomethacin-resistant relaxation by mesaconitine was mainly endothelium-dependent, inhibited by high K+ (30 mM), and inhibited by a combination of Ca2+-dependent K channel blockers, charybdotoxin and apamin. The relaxation by mesaconitine was proportional to the external Ca2+ concentration. These results suggest that mesaconitine elicits vasorelaxation of isolated rat small gastric artery mainly via release of endothelium-derived hyperpolarizing factor.

Mesaconitine-induced relaxation in rat aorta: involvement of Ca2+ influx and nitric-oxide synthase in the endothelium.

Aconiti tuber, roots of aconite (Aconitum japonicum), is an oriental herbal medicine used for centuries in Japan and China to improve the health of persons with a weak constitution and poor metabolism. We investigated the effects of mesaconitine, one of the aconite alkaloids in Aconiti tuber, on the contraction and free intracellular Ca2+ concentration ([Ca2+]i) level in isolated rat thoracic aorta. Mesaconitine at 30 microM inhibited 3 microM phenylephrine-induced contraction in the endothelium-intact, but not endothelium-denuded, aortic rings. The effect of mesaconitine was dependent on external Ca2+ concentrations. The relaxation induced by mesaconitine was abolished by N(omega)-nitro-L-arginine methyl ester (0.1 mM, an inhibitor of nitric-oxide synthase), as well as the relaxation induced by acetylcholine. Acetylcholine induced relaxation in two phases in our conditions; the initial phase was transient and external Ca2+ -independent, and the second phase was sustained and external Ca2+ -dependent. Treatment with 100 nM thapsigargin, which depleted intracellular Ca2+ stores, inhibited acetylcholine-induced, but not mesaconitine-induced, relaxation. Mesaconitine increased the [Ca2+]i level in endothelial cells by influx of Ca2+ from extracellular spaces. These findings suggest that mesaconitine-induced Ca2+ influx and activation of nitric-oxide synthase in endothelial cells and, thus, induced vasorelaxation in rat aorta.