A novel Toll-like receptor 7/8-specific antagonist E6742 ameliorates clinically relevant disease parameters in murine models of lupus.

The sensing of self RNA by the endosomal Toll-like receptors (TLRs) 7 and 8 initiates pathogenic mechanisms underlying the autoimmune disease lupus. A blockade of the TLR7/8 signals may, therefore, be a novel therapeutic intervention for lupus. To test the hypothesis, a novel compound E6742 that blocks TLR7/8 activation was identified. The mode of action of E6742 was investigated by analysis of the tertiary structure of TLR7 and 8 in complex with E6742. The in vitro activities of the compound were examined in cellular systems and its therapeutic potential was evaluated in murine lupus models. Tertiary structures of the extracellular domain of TLR7 and 8 in complex with E6742 showed that E6742 binds specifically and non-covalently to the hydrophobic pocket located at the interface of TLR7 or TLR8 homodimers. E6742 potently and selectively inhibited several TLR7/8-mediated cytokine responses in human PBMC. In two mouse models of lupus, oral dosing of E6742 after the onset of disease suppressed increase in autoantibodies and blocked the advance of organ damage. Collectively, the data show that TLR7/8 activation contributes to disease progression and its blocking by E6742 has potential as a therapeutic intervention for lupus.

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.

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.

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.

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.