Manabu Shirato

Antipruritic effect of the topical phosphodiesterase 4 inhibitor E6005 ameliorates skin lesions in a mouse atopic dermatitis model.

Phosphodiesterase (PDE) 4 inhibition is a well-known anti-inflammatory mechanism, but the development of PDE4 inhibitors has been hampered by side effects such as nausea and emesis. Local delivery of a PDE4 inhibitor to the site of inflammation may overcome these issues. The purpose of this study was to assess the therapeutic potential of E6005 (methyl 4-[({3-[6,7-dimethoxy-2-(methylamino)quinazolin-4-yl]phenyl}amino)carbonyl]benzoate), a novel PDE4 inhibitor developed as a topical agent for atopic dermatitis (AD). E6005 potently and selectively inhibited human PDE4 activity with an IC50 of 2.8 nM and suppressed the production of various cytokines from human lymphocytes and monocytes with IC50 values ranging from 0.49 to 3.1 nM. In mice models, the topical application of E6005 produced an immediate antipruritic effect as well as an anti-inflammatory effect with reduced expression of cytokines/adhesion molecules. On the basis of these observed effects, topical E6005 ameliorated the appearance of atopic dermatitis-like skin lesions in two types of AD models, hapten- and mite-elicited models, exhibiting inhibitory effects comparable to that of tacrolimus. The use of 14C-labeled E6005 showed rapid clearance from the blood and low distribution to the brain, contributing to the low emetic potential of this compound. These results suggest that E6005 may be a promising novel therapeutic agent with antipruritic activity for the treatment of AD.

A putative antipruritic mechanism of the phosphodiesterase-4 inhibitor E6005 by attenuating capsaicin-induced depolarization of C-fibre nerves.

E6005, a potent, selective phosphodiesterase (PDE) 4 inhibitor, has been developed as a novel topical agent of atopic dermatitis (AD). It has been shown to inhibit itching in patients with AD as well in mouse models. To study the mechanism underlying the anti‐pruritic effect of E6005, we examined its effect on the activation of dorsal root ganglion (DRG) neurons associated with the itch sensation. Depolarization of DRG neurons by a transient receptor potential vanilloid 1 (TRPV 1) activator, capsaicin was attenuated by E6005 as well as by a 3′,5′‐cyclic adenosine monophosphate (cAMP) elevator, forskolin. E6005 elevated intracellular levels of cAMP in DRG cells. Taken together, these results suggest that E6005 suppresses TRPV1‐mediated C‐fibre depolarization through elevation of cAMP levels, thereby exerting an anti‐pruritic effect. Thus, E6005 shows the potential to be a new agent for managing pruritus in various skin disorders, including AD.

An inhaled phosphodiesterase 4 inhibitor E6005 suppresses pulmonary inflammation in mice.

Chronic obstructive pulmonary disease (COPD) is a progressive lung disease associated with significant morbidity and mortality. Although several oral phosphodiesterase 4 (PDE4) inhibitors have been developed for the treatment of COPD, their use has been restricted because of side effects including nausea and emesis. We hypothesized that delivery of a dry powdered PDE4 inhibitor by inhalation would minimize systemic absorption and enable local PDE4 inhibition to suppress inflammation within the lung. Neutrophilic pulmonary inflammation was induced in mice by intratracheal administration of lipopolysaccharide. Mice were treated intratracheally with a new dry powder PDE4 inhibitor, E6005 (methyl 4-[({3-[6,7-dimethoxy-2-(methylamino)quinazolin-4-yl]phenyl}amino) carbonyl] benzoate). The pharmacokinetics, cell profiles and levels of cytokines, chemokines, and lipid mediators in bronchoalveolar lavage fluid (BALF), and lung histology were assessed. Intratracheal administration of E6005 to mice resulted in high concentrations of the compound in the lungs. Histological analysis of E6005-treated mice demonstrated reduced inflammation of lung tissue that correlated with a decrease in BALF levels of neutrophils, proinflammatory cytokines, chemokines, and cysteinyl leukotrienes. Thus, intratracheal administration of E6005 effectively suppresses neutrophilic pulmonary inflammation, suggesting that the new inhaled dry powder PDE4 inhibitor represents an alternative to the conventional oral formulation for treating COPD.

Calreticulin and integrin alpha dissociation induces anti-inflammatory programming in animal models of inflammatory bowel disease

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease, is a chronic intestinal inflammatory condition initiated by integrins-mediated leukocyte adhesion to the activated colonic microvascular endothelium. Calreticulin (CRT), a calcium-binding chaperone, is known as a partner in the activation of integrin α subunits (ITGAs). The relationship between their interaction and the pathogenesis of IBD is largely unknown. Here we show that a small molecule, orally active ER-464195-01, inhibits the CRT binding to ITGAs, which suppresses the adhesiveness of both T cells and neutrophils. Transcriptome analysis on colon samples from dextran sodium sulfate-induced colitis mice reveals that the increased expression of pro-inflammatory genes is downregulated by ER-464195-01. Its prophylactic and therapeutic administration to IBD mouse models ameliorates the severity of their diseases. We propose that leukocytes infiltration via the binding of CRT to ITGAs is necessary for the onset and development of the colitis and the inhibition of this interaction may be a novel therapeutic strategy for the treatment of IBD.Inflammatory bowel disease (IBD) is initiated by integrins-mediated leukocyte adhesion to the activated colonic microvascular endothelium. Here, the authors show that inhibition of the calreticulin binding to integrin α subunits ameliorates the severity of IBD in animal models.

Application of phosphodiesterase 4 inhibitor for atopic dermatitis.

キーワード:アトピー性皮膚炎,痒み,phosphodiesterase 4,E6005 エーザイ株式会社 筑波研究所(〒300 -2635 茨城県つくば市東光台 5 -1 -3) E-mail: n3 ishii@hhc.eisai.co.jp 原稿受領日:2014 年 7 月 2 日,依頼原稿 Title: Application of phosphodiesterase 4 inhibitor for atopic dermatitis Author: Naoto Ishii, Hisatsugu Wakita, Kazuki Miyazaki, Yasutaka Takase, Osamu Asano, Kazutomi Kusano, Manabu Shirato 要約:日本皮膚科学会によるとアトピー性皮膚炎 (AD)の定義は「増悪と寛解を繰り返す,痒みを伴う 湿疹を主病変とする慢性に経過する疾患」とされてお り,今なお患者数が増大する傾向にある.ADでは重 度な痒みを伴うことが特徴であり,既存薬では十分な 痒み抑制作用が得られているとは言えず,痒みのコン トロールが治療の課題の一つと考えられている.そこ で改めて AD病態を振り返り,治療薬開発の現状を纏 めた.その中で phosphodiesterase 4(PDE4)阻害薬 に注目し,E6005 を題材として PDE4 阻害薬の AD適 応を目指した取り組みを紹介する.E6005 は無細胞 PDE活性測定系において選択的な PDE4 阻害作用を 示し,ヒト末梢血リンパ球・単球からのサイトカイン 産生を抑制したことから,PDE4 阻害に基づく E6005 の抗炎症作用を確認できた.ハプテン誘発接触皮膚炎 型マウスモデルにおいて,E6005 を連続塗布すると有 意な皮膚炎抑制効果が得られ,かつ皮疹部におけるサ イトカイン・接着分子の発現抑制効果が認められた. さらに ADマウスモデルである NC/Ngaマウスに E6005 を連続塗布すると AD様皮膚炎抑制効果が得ら れたほか,単回塗布による即時的な掻破行動抑制効果 も認められた.PDE4 阻害作用に基づく嘔吐誘発に関 してキシラジン・ケタミン麻酔覚醒モデルを用いて検 討したところ,E6005 は第一世代 PDE4 阻害薬シロミ ラストと比較して嘔吐誘発性が低いことが分かり,治 療濃度域の広さが認められた.E6005 は血液中で速や かに代謝され,中枢神経系への分布が非常に少ないこ とから嘔吐誘発性の低下に繋がった可能性がある.こ れらの結果より,E6005 は全身的暴露を最小限に抑え た局所投与型薬剤として,抗炎症作用のみならず痒み 抑制作用を併せ持つアトピー性皮膚炎治療薬として期 待される.