Fumio Tsuji

Effects of bucillamine and N-acetyl-l-cysteine on cytokine production and collagen-induced arthritis (CIA)

We investigated the effects of bucillamine and N‐acetyl‐ L‐cysteine (NAC) on cytokine production and CIA. Bucillamine and NAC inhibited NF‐κB activation and tumour necrosis factor‐alpha (TNF‐α) mRNA expression in human monocytic leukaemia cell line THP‐1, and cytokine production from monocyte cell lines at concentrations >10−3 M. They also inhibited cytokine production and CIA in mice at a dose of 500 mg/kg. These results suggest that NF‐κB inhibitors such as bucillamine and NAC may inhibit cytokine‐related diseases, including arthritis.

Preventive Effect of TRPV1 Agonists Capsaicin and Resiniferatoxin on Ischemia/Reperfusion-induced Renal Injury in Rats

We evaluated the effect of capsaicin, one of the transient receptor potential vanilloid receptor 1 (TRPV1) agonists, on ischemic acute renal failure (ARF) in rats. Ischemic ARF was induced by occlusion of the left renal artery and vein for 45 minutes followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function in vehicle-treated ARF rats markedly decreased at 24 hours after reperfusion. Treatment with capsaicin (3, 10, and 30 mg/kg, orally) 30 minutes before ischemia dose-dependently attenuated ischemia/reperfusion-induced renal dysfunction. In renal tissues exposed to ischemia/reperfusion, neutrophil infiltration, renal superoxide production, and renal tumor necrosis factor (TNF)-α mRNA expression were augmented, but these alterations were attenuated by the treatment with capsaicin. On the other hand, ischemia/reperfusion-enhanced renal interleukin (IL)-10 mRNA expression and plasma concentrations of IL-10 were augmented by treatment with capsaicin in ARF rats. In addition, resiniferatoxin (20 μg/kg, subcutaneous), a more selective and potent TRPV1 agonist, showed a renoprotective effect on ischemia/reperfusion-induced renal injury, in a qualitatively similar way to cases seen with capsaicin. These results demonstrate that TRPV1 agonists prevent ischemia/reperfusion-induced renal dysfunction. These renoprotective effects seem to be closely related to the inhibition of inflammatory response via TRPV1.

Transient receptor potential vanilloid 1 agonists as candidates for anti-inflammatory and immunomodulatory agents

We recently demonstrated that SA13353 [1-[2-(1-adamantyl)ethyl]-1-pentyl-3-[3-(4-pyridyl)propyl]urea], a novel transient receptor potential vanilloid 1 (TRPV1) agonist, inhibits TNF-alpha production through the activation of capsaicin-sensitive afferent neurons. In the present study, we investigated the effects of SA13353 on lipopolysaccharide (LPS)-induced cytokine production and a murine model of experimental autoimmune encephalomyelitis (EAE). SA13353 inhibited LPS-induced TNF-alpha and interleukin (IL)-1beta production while augmenting IL-10 production in mice. It also inhibited TNF-alpha and IL-1beta mRNA expression, and increased IL-10 mRNA expression in LPS-treated murine liver. These effects were not observed in TRPV1 KO and sensory denervated mice. Capsaicin and SA13353 increased serum neuropeptide levels, and calcitonin gene-related peptide fragment 8-37 (CGRP(8)(-)(37)), a CGRP antagonist, partially blocked the inhibitory effects of capsaicin and SA13353 on LPS-induced TNF-alpha production. These results suggest that the TPPV1 agonistic effects inhibit TNF-alpha production, at least partially, via neuropeptide release. SA13353 did not directly affect LPS-induced cytokine production in vitro using RAW264.7 macrophages, which do not express TRPV1. Therefore, we consider SA13353 to be a good tool for the investigation of the value of TRPV1 agonists for the treatment of chronic inflammation. In a murine EAE model, SA13353 attenuated clinical signs and histopathological changes. SA13353 attenuated cytokine levels, including TNF-alpha, IL-1beta, IL-12p40, IL-17, and interferon (IFN)-gamma, after proteolipid protein (PLP) immunization. In addition, SA13353 attenuated the increase of IL-17-producing cells. These results suggest that TRPV1 agonists may act as anti-inflammatory and immunomodulatory agents in vivo in certain inflammatory diseases.

Involvement of leukotriene B4 in arthritis models.

We investigated the role of leukotriene B4 (LTB4) in murine arthritis models using a leukotriene A4 (LTA4) hydrolase inhibitor, SA6541. SA6541 inhibited the severity of collagen-induced arthritis and muramyl dipeptide (MDP)-induced hyperproliferation of synovial cells in vivo. SA6541 also inhibited LTA4-induced hyperproliferation of synovial stromal cells in vitro. These results suggest that LTB4 may play an important role in arthritis models.

Involvement of Leukotriene B4 in Murine Dermatitis Models

Leukotriene B4 (LTB4) is a product of the 5-lipoxygenase pathway of arachidonic acid (AA) metabolism. LTB4 is a potent chemotactic factor for neutrophils and has been postulated to play an important role in a variety of pathological conditions including rheumatoid arthritis, psoriasis, and inflammatory bowel disease. To investigate the role of LTB4 in dermatitis, we used S-(4-dimethylaminobenzyl)-N-[(2S)-3-mercapto-2-methylpropionyl]-L- cysteine (SA6541), a potent leukotriene A4 (LTA4) hydrolase inhibitor. SA6541 inhibited LTB4 production with an IC50 value of 270 nM in vitro. 5-Hydroperoxyeicosatetraenoic acid (5-HPETE) or AA injection induced LTB4 production and neutrophil influx in mouse ear. SA6541 inhibited 5-HPETE- and AA-induced LTB4 production and neutrophil influx in mouse ear when administered orally at a dose of 50 mg/kg. SA6541 also inhibited 5-HPETE-induced prostaglandin E2 (PGE2) production, probably by an indirect effect through the inhibition of LTB4 production. These results suggest that LTB4 may be important in the pathogenesis of dermatitides such as psoriasis.

SA13353 (1-[2-(1-Adamantyl)ethyl]-1-pentyl-3-[3-(4-pyridyl)propyl]urea) inhibits TNF-α production through the activation of capsaicin-sensitive afferent neurons mediated via transient receptor potential vanilloid 1 in vivo

Tumor necrosis factor-alpha (TNF-alpha) is known to play a crucial role in the pathogenesis of rheumatoid arthritis. In the present study, we demonstrate the effects of SA13353 (1-[2-(1-Adamantyl)ethyl]-1-pentyl-3-[3-(4-pyridyl)propyl]urea), a novel orally active inhibitor of TNF-alpha production, in animal models, and its mechanism of action on TNF-alpha production. SA13353 significantly inhibited lipopolysaccharide (LPS)-induced TNF-alpha production in a dose-dependent manner in rats. Moreover, SA13353 exhibited a binding affinity for the rat vanilloid receptor and increased neuropeptide release from the rat dorsal root ganglion neurons. However, its effects were blocked by pretreatment with the transient receptor potential vanilloid 1 (TRPV1) antagonist capsazepine. The ability of SA13353 and capsaicin to inhibit LPS-induced TNF-alpha production was eliminated by sensory denervation or capsazepine pretreatment in vivo. Although they inhibited LPS-induced TNF-alpha production in mice, these effects were not observed in TRPV1 knockout mice. SA13353 provoked the release of neuropeptides without nerve inactivation, even when chronically administered to rats. These results suggest that SA13353 inhibits TNF-alpha production through activation of capsaicin-sensitive afferent neurons mediated via TRPV1 in vivo. Post-onset treatment of SA13353 strongly reduced the hindpaw swelling and joint destruction associated with collagen-induced arthritis in rats. Thus, SA13353 is expected to be a novel anti-arthritic agent with a unique mechanism of action.

Effects of mitogen-activated protein kinase inhibitors or phosphodiesterase inhibitors on interleukin-1-induced cytokines production in synovium-derived cells

The effects of mitogen-activated protein (MAP) kinase inhibitors or phosphodiesterase (PDE) inhibitors on interleukin (IL)-1-induced cytokines production in synovium-derived cells were investigated. Human synoviocyte (HS) or synovial sarcoma (SW982) stimulated by IL-1beta (100 ng/ml) produced various cytokines including IL-6, IL-8, GROalpha, VEGF, basic FGF and tumor necrosis factor alpha (TNFalpha) in vitro. SB202190 or SB203580, an inhibitor of p38 MAP kinase, inhibited all cytokines production in both cells. PD98059, an inhibitor of MAP kinase kinase (MEK), inhibited IL-6, IL-8 and basic FGF production in HS and all cytokines production except basic FGF in SW982. However, many of its effects were weaker than those of SB202190 or SB203580. Quazinone, an inhibitor of cyclic GMP-inhibited PDE, scarcely affected cytokines production in both cells. Rolipram or R0201724, an inhibitor of cyclic AMP-specific PDE, inhibited IL-8 and basic FGF production in HS and TNFalpha production in SW982, however, it enhanced the other cytokines production in SW982. These results suggest that the activation of MAP kinase cascade may be important for IL-1-induced cytokines production in synovium-derived cells. On the other hand, the role of cyclic AMP may be dependent on cell and cytokine types.

Preventive effect of SA13353 [1-[2-(1-adamantyl)ethyl]-1-pentyl-3-[3-(4-pyridyl)propyl]urea], a novel transient receptor potential vanilloid 1 agonist, on ischemia/reperfusion-induced renal injury in rats.

Tumor necrosis factor (TNF)-α plays a crucial role in the pathogenesis of ischemia/reperfusion-induced renal injury. We demonstrated recently that the preischemic treatment with resiniferatoxin, a transient receptor potential vanilloid 1 (TRPV1) agonist, attenuates renal TNF-α mRNA expression and improves ischemia/reperfusion-induced renal injury in rats. In addition, we found that SA13353 [1-[2-(1-adamantyl)ethyl]-1-pentyl-3-[3-(4-pyridyl)propyl]urea], a novel orally active TRPV1 agonist, inhibits TNF-α production through the activation of capsaicin-sensitive afferent neurons and reduces the severity of symptoms in established rat collagen-induced arthritis. In the present study, we investigated effects of treatment with SA13353 on ischemia/reperfusion-induced renal injury in rats. Ischemic acute kidney injury (AKI) was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function in vehicle-treated AKI rats markedly decreased at 24 h after reperfusion. Treatment with SA13353 (3, 10, and 30 mg/kg p.o.) 30 min before ischemia dose-dependently attenuated the ischemia/reperfusion-induced renal dysfunction. Histopathological examination of the kidney of AKI rats revealed severe renal damage, which were significantly suppressed by the SA13353 treatment. In renal tissues exposed to ischemia/reperfusion, neutrophil infiltration, superoxide production, TNF-α mRNA expression, and cytokine-induced neutrophil chemoattractant-1 mRNA expression were augmented, but these alterations were attenuated by the treatment with SA13353. On the other hand, ischemia/reperfusion-enhanced renal interleukin-10 mRNA expression and its plasma concentration were further augmented by SA13353 treatment. These results demonstrate that the orally active TRPV1 agonist SA13353 prevents the ischemia/reperfusion-induced AKI. This renoprotective effects seem to be closely related to the inhibition of inflammatory response via TRPV1 activation.

Effects of SA6541, a leukotriene A4 hydrolase inhibitor, and indomethacin on carrageenan-induced murine dermatitis

We investigated the effects of S-(4-dimethylaminobenzyl)-N-[(2S)-3-mercapto-2-methylpropionyl]-L- cysteine (SA6541), a potent leukotriene A4 hydrolase inhibitor. on early phase of carrageenan-induced dermatitis model. Carrageenan injection induced edema and neutrophil influx in the mouse ear. SA6541 inhibited edema formation and neutrophil influx. SA6541 also inhibited leukotriene B4 production but not prostaglandin E2 production in the mouse ear. On the other hand, indomethacin inhibited edema formation but not neutrophil influx. Indomethacin also inhibited prostaglandin E2 production but not leukotriene B4 production. Combination therapy with SA6541 and indomethacin strongly inhibited edema formation in comparison with treatment with either agent alone. These results suggest that leukotriene B4 may be important in the pathogenesis of dermatitis.

The effect of ONO-3705, a novel TxA2 receptor antagonist, on U-46619-induced contraction of guinea pig and human tracheal strips in vitro and on bronchoconstriction in guinea pigs in vivo

The effect of (9, 11), (11, 12)-didedoxa-9 alpha, 11-alpha-dimethylmethano-11,12-methano-13,14-dihydro-13-aza-14-oxo -15-cyclo-pentyl-16, 17, 18, 19, 20-pentanor-15-epi-TxA2 (ONO-3708) on 9,11-methanoepoxy-prostaglandin H2 (U-46619)-induced contraction of airway smooth muscle in the guinea pigs and human in vitro and bronchoconstriction in guinea pigs in vivo was investigated. In in vitro experiments, ONO-3708 inhibited the U-46619-induced contraction of isolated guinea pig and human tracheal smooth muscle in a dose related fashion (guinea pig; pA2=7.78, human; pA2 = 7.43). The contractions of guinea pig tracheal muscle caused by histamine and leukotriene D4 (LTD4) were not inhibited by ONO-3708. In in vivo experiments, intravenous injection of ONO-3708 at doses between 1 and 20 mg/kg inhibited the U-46619-induced increase of airway insufflation pressure as measured by Konzett-Rössler method. In addition, ONO-3708 inhibited the U-46619-induced increase in airway reactivity to acetylcholine. These data suggest that ONO-3708 has possible therapeutic utility for asthma in which TxA2 participates.