Immunosuppressive activity of FTY720, sphingosine 1-phosphate receptor agonist: I. Prevention of allograft rejection in rats and dogs by FTY720 and FTY720-phosphate.

FTY720, a new class of immunomodulator, induces lymphopenia by sequestration of circulating lymphocytes into secondary lymphoid tissues. FTY720 at 0.1 to 1 mg/kg significantly prolonged the allograft survival in a dose-dependent manner and showed a marked synergistic effect in combination with cyclosporine (CsA) in rat skin and cardiac allograft models. In addition, the canine renal allograft survival was significantly prolonged by combination therapy with FTY720 at 0.03 to 1 mg/kg and CsA at 10 mg/kg as compared with monotherapy of FTY720 or CsA. By contrast, the combination therapy with CsA and azathioprine or CsA and mycophenolate mofetil resulted in only an additive effect in rat skin allograft. When FTY720 was administered to rats, FTY720 was metabolized by omega-oxidation of the octyl side chain, and beta-oxidation subsequently, or phosphorylated by sphingosine kinase. Omega- and beta-oxidized 4 metabolities of FTY720 at 10 mg/kg i.v. showed neither lymphopenia nor immunosuppressive activity in rat skin allograft. On the other hand, (S)-enantiomer of FTY720-phosphate at 0.1 and 1 mg/kg intravenously induced a marked lymphopenia and significantly prolonged the allograft survival in the rat allotransplantation. From these results, it is suggested the lymphopenia and the immunosuppression induced by FTY720 administration is due to the agonistic activity against SIP receptors of the active metabolite, (S)-FTY720-phosphate.

Y-24180, an antagonist of platelet-activating factor, suppresses interleukin 5 production in cultured murine th(2)cells and human peripheral blood mononuclear cells.

Interleukin (IL)-5 has been shown to play an essential role in the pathogenesis of airway inflammation. We investigated the effect of 4-(2-chlorophenyl)-2-[2-(4-isobutylphenyl)ethyl]-6, 9-dimethyl-6 H -thieno[3,2- f ][1,2,4]triazolo[4,3- a][1,4]diazepine (Y-24180), an antagonist of platelet-activating factor (PAF), on the production of IL-5 in cultured D10.G4.1 cells, a murine Th(2)clone, and human peripheral blood mononuclear cells (PBMC). As a result, Y-24180 was found to suppress both the mRNA expression of IL-5 and the subsequent secretion of this cytokine in antigen-stimulated D10.G4.1 cells. Y-24180 also suppressed the production of IL-4, another Th(2)type cytokine, at the level of mRNA expression, however, it hardly affected the mRNA expression for IL-6 or IL-10, thus indicating it to have a selective action against IL-5 and IL-4. The suppressive effect of Y-24180 on the secretion of IL-5 by human PBMC was more potent than that of WEB2086, which is another PAF-antagonist. These results suggest that Y-24180 suppresses IL-5 production through a common pathway which also affects the production of IL-4, even though the mechanism remains to be elucidated as to whether the PAF-antagonistic actions are involved or not.

Induction of apoptotic DNA fragmentation by nonsteroidal anti-inflammatory drugs in cultured rat gastric mucosal cells.

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to cause apoptosis in several cell lines including transformed chicken embryo fibroblasts and human colon cancer cells. We herein report the apoptotic effect of NSAIDs in a non-transformed cell line derived from the rat gastric mucosa, RGMI (rat gastric mucosa cell first). 1-[p-Chlorobenzoyl]-5-methoxy-2-methylindole-3-acetic acid (indomethacin) and sodium 2-(2,6-dichloroanilino)phenylacetate (sodium diclofenac), potent and non-selective inhibitors of cyclooxygenase, were found to induce DNA fragmentation in RGM1 cells in a time- and concentration-dependent manner. The expression of mRNA for cyclooxygenase-2 was hardly detected in the intact cells but was clearly enhanced when the cells were incubated with the two NSAIDs. In contrast, the expression of mRNA for cyclooxygenase-1 was constitutive and was never affected by NSAIDs. The effect of [3,4-di(4-methoxyphenyl)-5-isoxazolyl] acetic acid (mofezolac), a potent and highly preferential inhibitor of cyclooxygenase-1, and N-[2-(cyclohexyloxy)-4-nitrophenyl]methanesulphonamide (NS-398), a selective inhibitor of cyclooxygenase-2, on DNA fragmentation and cyclooxygenase-2 mRNA expression was weak compared to the effect of indomethacin or sodium diclofenac. The DNA fragmentation induced by sodium diclofenac was hardly affected by the exogenous addition of 16,16-dimethyl prostaglandin E2 but was inhibited by caspase inhibitors such as Ac-YVAD-CHO and Ac-DEVD-CHO. The present data provide the first evidence that NSAIDs, such as indomethacin and sodium diclofenac, cause apoptotic DNA fragmentation in cultured gastric mucosal cells, and also indicate the involvement of caspases rather than the inhibition of cellular prostaglandin synthesis in the apoptotic process.

Analgesic effect of mofezolac, a non-steroidal anti-inflammatory drug, against phenylquinone-induced acute pain in mice.

The oral administration of mofezolac, [3,4-di(4-methoxyphenyl)-5-isoxazolyl]acetic acid, resulted in the suppression of writhing induced by the intraperitoneal injection of phenyl-p-benzoquinone (phenylquinone, PQ) in mice. The analgesic activity of mofezolac was almost as potent as that of indomethacin, and more potent than that of sodium diclofenac, zaltoprofen, NS-398, and etodolac when their 50% effective doses were compared. The in vitro inhibitory activity of mofezolac against ovine cyclooxygenase (COX)-1 was also more potent than that of any other non-steroidal anti-inflammatory drugs (NSAIDs) tested, whereas the activity of mofezolac against COX-2 was relatively weak. A Western analysis revealed COX-1 to be constitutively expressed, whereas COX-2 was hardly expressed until 30 min after the PQ-injection in the peritoneal cells. Because the writhing terminated within 30 min after PQ-injection, the prostaglandins involved in the induction of writhing seem to be derived from COX-1. These data thus indicate that potent analgesic activity of mofezolac against the present model to be more closely related to its potent inhibitory activity against COX-1 but not against COX-2.

Involvement of prostaglandins produced by cyclooxygenase-1 in murine visceronociception induced by phenylquinone.

Intraperitoneal injection of phenyl-p-benzoquinone (phenylquinone, PQ) induced writhing in mice for up to 30 min. During this time, the peritoneal content of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), a stable degradation product of PG12, was highest in the 15-min. sample. In the peritoneal cells, the mRNA expression for the constitutive cyclooxygenase-1 (COX-1) was unchanged by PQ administration. In contrast, little mRNA for COX-2 was detected in the peritoneal cells from unstimulated animals, and was induced 60-120 min. after PQ administration. PGs involved in the induction of writhing thus seem to be derived from a COX-1 reaction. Oral administration of mofezolac, a non-steroidal anti-inflammatory drug which potently inhibits COX-1, suppressed the PQ-induced writhing and peritoneal accumulation of PGs without affecting mRNA expression for both COX isoforms in mice.

Evaluation of combined antibiotic-omeprazole therapies in Helicobacter pylori-infected Mongolian gerbils.

Mongolian gerbils are a laboratory host for gastric colonization with Helicobacter pylori, showing gastritis followed by typical gastric ulcer after infection with H. pylori. In such gerbils, we evaluated combined therapies of amoxicillin (AMPC) and clarithromycin (CAM) as antibiotics, and omeprazole (OPZ) as a H+/K+ adenosine triphosphatase (ATPase) inhibitor. The gerbils were orally inoculated with 2 x 10(8) bacilli of H. pylori ATCC 43504. Four weeks after inoculation, the infected gerbils were orally treated singly with OPZ, AMPC, and CAM, and their insufficient efficacy on bacterial clearance was confirmed by a polymerase chain reaction technique, and by a culture method. In contrast, combined therapy of OPZ plus either AMPC or CAM showed significant bacterial clearance, demonstrating the efficacy of this combined therapy in the gerbil model. Mongolian gerbils are suggested to be useful for the pharmacological evaluation of anti-H. pylori compounds.

Principal involvement of cyclooxygenase-1-derived prostaglandins in the c-fos expression of the rat hind brain following visceral stimulation with acetic acid.

We investigated the relationship between c-fos expression in the hind brain and peritoneal prostaglandin (PG) synthesis after visceronociceptive stimulation with acetic acid in rats. Time-course studies on the mRNA expression for c-fos in the hind brain and cyclooxygenase (COX) isoforms in the peritoneal cells, as well as on the peritoneal 6-keto-PGF1alpha accumulation, after stimulation indicated that COX-1 but not COX-2 was responsible for the peritoneal synthesis of PGs which were suggested to evoke c-fos expression in the hind brain. Pharmacological experiments using mofezolac, a preferential inhibitor against COX-1, and NS-398, a selective inhibitor against COX-2, confirmed the involvement of COX-1 derived PGs in the induction of c-fos expression in the hind brain following the noxious stimulation.

Effects of nonsteroidal anti-inflammatory drugs on interleukin-1 receptor antagonist production in cultured human peripheral blood mononuclear cells.

The effects of nonsteroidal anti-inflammatory drugs (NSAIDs), mofezolac, indomethacin, sodium diclofenac, and zaltoprofen, on the production of interleukin-1 receptor antagonist (IL-1ra) were examined in cultured human peripheral blood mononuclear cells (PBMC). Among the NSAIDs tested, mofezolac and sodium diclofenac were found to stimulate the mRNA expression for IL-1ra without affecting the mRNA expression for IL-1 beta. These two drugs also stimulated the secretion of IL-1ra by PBMC in the absence of bacterial lipopolysaccharide (LPS), however, the stimulatory effect of sodium diclofenac diminished in the presence of LPS. Mofezolac suppressed the mRNA expression for IL-1 beta in PBMC stimulated with exogenous IL-1 beta, indicating the secreted IL-1ra in the presence of mofezolac to be biologically active. Since IL-1ra suppresses the function of IL-1, a pro-inflammatory cytokine, the stimulatory effect of such NSAIDs as mofezolac on IL-1ra production could also be one of the mechanisms involved in its anti-inflammatory and antinociceptive actions.

Enhancement of in vivo production of IL-1 alpha and IL-6 in mice by Y-25510, a 1H-pyrazolo[3,4-b]pyridine-1 acetic acid derivative.

The serum concentrations of interleukin(IL)-1 alpha and IL-6 in C57BL/6 and C3H/HeN mice reached the maximum at 12-16 h after the intravenous treatment with (+/-)-3-[4-(2-dimethylamino-1-methylethoxy)- phenyl]-1H-pyrazolo[3,4-b]pyridine-1-acetic acid (Y-25510) at a dose of 3 mg/kg, and the concentration of IL-10 did at 20 h after the treatment. By repeated treatments with Y-25510 to C57BL/6 mice for 14 days, the maximal values of IL-1 alpha and IL-6 at day 14 were respectively 6.6 times and 5.7 times relative to those on day 1. Neither the counts of peripheral leukocytes nor those of platelets were, however, increased until day 15. The repeated treatment with Y-25510 followed by anti-IL-10 antibody for 14 days was significantly more effective than that with Y-25510 alone in increasing the concentrations of IL-1 alpha and IL-6 in C3H/HeN mice. In addition, both the counts of peripheral leukocytes and platelets were significantly increased at day 18. In conclusion, Y-25510 enhanced not only the production of endogenous IL-1 alpha and IL-6 but also that of IL-10 in healthy mice. As a result, in normal conditions, both the counts of peripheral leukocytes and platelets were never increased because of the inhibitory effect of endogenously produced IL-10.