Involvement of resistin-like molecule ß in the development of methionine-choline deficient diet-induced non-alcoholic steatohepatitis in mice.

Resistin-like molecule ß (RELMß) reportedly has multiple functions including local immune responses in the gut. In this study, we investigated the possible contribution of RELMß to non-alcoholic steatohepatitis (NASH) development. First, RELMß knock-out (KO) mice were shown to be resistant to methionine-choline deficient (MCD) diet-induced NASH development. Since it was newly revealed that Kupffer cells in the liver express RELMß and that RELMß expression levels in the colon and the numbers of RELMß-positive Kupffer cells were both increased in this model, we carried out further experiments using radiation chimeras between wild-type and RELMß-KO mice to distinguish between the contributions of RELMß in these two organs. These experiments revealed the requirement of RELMß in both organs for full manifestation of NASH, while deletion of each one alone attenuated the development of NASH with reduced serum lipopolysaccharide (LPS) levels. The higher proportion of lactic acid bacteria in the gut microbiota of RELMß-KO than in that of wild-type mice may be one of the mechanisms underlying the lower serum LPS level the former. These data suggest the contribution of increases in RELMß in the gut and Kupffer cells to NASH development, raising the possibility of RELMß being a novel therapeutic target for NASH.

Resistin-like molecule ß is abundantly expressed in foam cells and is involved in atherosclerosis development.

OBJECTIVE: Resistin-like molecule (RELM) ß is a secretory protein homologous to resistin and reportedly contributes to local immune response regulation in gut and bronchial epithelial cells. However, we found that activated macrophages also express RELMß and thus investigated the role of RELMß in the development of atherosclerosis. APPROACH AND RESULTS: It was demonstrated that foam cells in atherosclerotic lesions of the human coronary artery abundantly express RELMß. RELMß knockout ((-/-)) and wild-type mice were mated with apolipoprotein E-deficient background mice. RELMß(-/-) apolipoprotein E-deficient mice exhibited less lipid accumulation in the aortic root and wall than RELMß(+/+) apolipoprotein E-deficient mice, without significant changes in serum lipid parameters. In vitro, RELMß(-/-) primary cultured peritoneal macrophages (PCPMs) exhibited weaker lipopolysaccharide-induced nuclear factor-κB classical pathway activation and inflammatory cytokine secretion than RELMß(+/+), whereas stimulation with RELMß upregulated inflammatory cytokine expressions and increased expressions of many lipid transporters and scavenger receptors in PCPMs. Flow cytometric analysis revealed inflammatory stimulation-induced RELMß in F4/80(+) CD11c(+) PCPMs. In contrast, the expressions of CD11c and tumor necrosis factor were lower in RELMß(-/-) PCPMs, but both were restored by stimulation with recombinant RELMß. CONCLUSIONS: RELMß is abundantly expressed in foam cells within plaques and contributes to atherosclerosis development via lipid accumulation and inflammatory facilitation.

Deconstruction of sulfonamide inhibitors of the urotensin receptor (UT) and design and synthesis of benzylamine and benzylsulfone antagonists.

Potent small molecule antagonists of the urotensin receptor are described. These inhibitors were derived via systematically deconstructing a literature inhibitor to understand the basic pharmacophore and key molecular features required to inhibit the protein receptor. The series of benzylamine and benzylsulfone antagonists herein reported display a combination of nanomolar molecular and cellular potency as well as acceptable in vitro permeability and metabolic stability.

Alpha-1D adrenoceptors are involved in reserpine-induced supersensitivity of rat tail artery.

1. We examined reserpine-induced chemical denervation supersensitivity with special reference to alpha-1 adrenoceptor (AR) subtypes. 2. Chronic treatment with reserpine for 2 weeks depleted noradrenaline in the tail artery and spleen of rats. Noradrenaline in the thoracic aorta was negligible before and after reserpine treatment. 3. The treatment with reserpine produced supersensitivity in the contractile responses of the rat tail artery to phenylephrine, 5-HT and KCl, resulting in leftward shift of concentration-response curves (11.6-, 2.5- and 1.1-fold at EC(50) value, respectively). These results suggest a predominant sensitization of the alpha-1 AR-mediated response by reserpine treatment. 4. BMY 7378 at a concentration (30 nm) specific for blocking the alpha-1D AR subtype, but not KMD-3213 at a concentration (10 nm) selective for blocking the alpha-1A AR subtype, inhibited the supersensitivity of the phenylephrine-induced response in the reserpine-treated artery. On the other hand, the response to phenylephrine in reserpine-untreated artery was selectively inhibited by the same concentration of KMD-3213, but not by BMY 7378. Prazosin, a subtype-nonselective antagonist, blocked the responses to phenylephrine with the same potency, regardless of reserpine treatment. 5. In the thoracic aorta and spleen, no supersensitivity was produced in the responses to phenylephrine by reserpine treatment. 6. In a tissue segment-binding study using [(3)H]-prazosin, the total density and affinity of alpha-1 ARs in the rat tail artery were not changed by treatment with reserpine. However, alpha-1D AR with high affinity for BMY 7378 was significantly detected in reserpine-treated tail artery, in contrast to untreated artery. Decreases in alpha-1A AR with high affinity for KMD-3213 and alpha-1B AR with low affinities for KMD-3213 and BMY 7378 were also estimated in reserpine-treated tail artery. 7. Alpha-1D AR mRNA in rat tail artery increased to three-folds by reserpine treatment, whereas the levels of alpha-1A and 1B mRNAs were not significantly changed. 8. The present results suggest that chronic treatment with reserpine affects the expression of alpha-1 AR subtypes of rat tail artery and that the induction of alpha-1D ARs with high affinity for catecholamines is in part associated with reserpine-induced supersensitivity.

Characterization of sabiporide, a new specific NHE-1 inhibitor exhibiting slow dissociation kinetics and cardioprotective effects.

Sabiporide, a new benzoguanidine, was characterized on fibroblasts stably expressing the Na(+)/H(+) exchanger isoforms NHE-1, NHE-2 and NHE-3. 22Na(+) uptake experiments show that this compound possesses a K(i) of 5+/-1.2 x 10(-8) M for NHE-1, and discriminates efficiently between the NHE-1, -2 and -3 isoforms (K(i) for NHE-2: 3+/-0.9 x 10(-6) M, and K(i)>1 mM for NHE-3). Similar K(i) values are obtained on rat cardiomyocytes and human platelets expressing NHE-1 (K(i)'s of 7+/-1 x 10(-9) and 2.7+/-0.4 x 10(-8) M respectively). Interestingly, when compared with amiloride and cariporide, sabiporide inhibition persists even after this molecule had been rinsed out (half time of 7 h for sabiporide, and of 1 and 2.5 min for amiloride and cariporide, respectively), the decay of all these molecules exhibiting a complex multiexponential behavior. Thus, sabiporide, which possesses remarkable cardioprotective properties, is a specific NHE-1 inhibitor possessing unique binding kinetics.

[Reserpine-induced supersensitivity and alpha 1-adrenoceptor subtypes].

Supersensitivity is one of classical and pharmacological phenomena, and may be caused by a variety of procedures, including surgical and chemical denervation and chronic treatment with antagonists. We examined reserpine-induced chemical denervation supersensitivity with special reference to arterial alpha 1-adrenoceptor (alpha 1-AR) subtypes. Chronic treatment with reserpine for 2 weeks produced supersensitivity in the contractile response to phenylephrine of isolated rat tail artery, resulting a leftward shift of concentration-response curve (10 fold shift at EC50 value). This supersensitivity in reserpine-treated artery was selectively inhibited by BMY7378 (alpha 1D-AR selective antagonist) but not by KMD-3213 (alpha 1A-AR selective antagonist). On the other hand, the response to phenylephrine in reserpine-untreated artery was inhibited by KMD-3213 but not by BMY7378. Tissue segment binding study with 3H-prazosin revealed that high affinity binding sites for BMY7378 were detected with a proportion of 32% in reserpine-treated tail artery but absent in untreated artery, although total density of alpha 1-ARs was not changed by reserpine-treatment. The present results strongly suggest that reserpine-induced supersensitivity of rat tail artery is caused by a selective induction of alpha 1D-AR subtype.