Pharmacological characterization of abediterol, a novel inhaled ß(2)-adrenoceptor agonist with long duration of action and a favorable safety profile in preclinical models.

Abediterol is a novel potent, long-acting inhaled ß(2)-adrenoceptor agonist in development for the treatment of asthma and chronic obstructive pulmonary disease. Abediterol shows subnanomolar affinity for the human ß(2)-adrenoceptor and a functional selectivity over ß(1)-adrenoceptors higher than that of formoterol and indacaterol in both a cellular model with overexpressed human receptors and isolated guinea pig tissue. Abediterol is a full agonist at the human ß(2)-adrenoceptor (E(max) = 91 ± 5% of the maximal effect of isoprenaline). The potency and onset of action that abediterol shows in isolated human bronchi (EC(50) = 1.9 ± 0.4 nM; t½ onset = 7-10 min) is not significantly different from that of formoterol, but its duration of action (t½ ∼ 690 min) is similar to that of indacaterol. Nebulized abediterol inhibits acetylcholine-induced bronchoconstriction in guinea pigs in a concentration-dependent manner, with higher potency and longer duration of action (t½ = 36 h) than salmeterol (t½ = 6 h) and formoterol (t½ = 4 h) and similar duration of action to indacaterol up to 48 h. In dogs, the bronchoprotective effect of abediterol is more sustained than that of salmeterol and indacaterol at doses without effects on heart rate, thus showing a greater safety margin (defined as the ratio of dose increasing heart rate by 5% and dose inhibiting bronchospasm by 50%) than salmeterol, formoterol, and indacaterol (5.6 versus 3.3, 2.2, and 0.3, respectively). In conclusion, our results suggest that abediterol has a preclinical profile for once-daily dosing in humans together with a fast onset of action and a favorable cardiovascular safety profile.

Characterization of aclidinium bromide, a novel inhaled muscarinic antagonist, with long duration of action and a favorable pharmacological profile.

Aclidinium bromide is a novel potent, long-acting inhaled muscarinic antagonist in development for the treatment of chronic obstructive pulmonary disease. Aclidinium showed subnanomolar affinity for the five human muscarinic receptors (M(1)-M(5)). [(3)H]Aclidinium dissociated slightly faster from M(2) and M(3) receptors than [(3)H]tiotropium but much more slowly than [(3)H]ipratropium. Its association rate for the M(3) receptor was similar to [(3)H]ipratropium and 2.6 times faster than [(3)H]tiotropium. Residence half-life of [(3)H]aclidinium at the M(2) receptor was shorter than at the M(3) receptor, demonstrating kinetic selectivity for the M(3) receptor. In isolated guinea pig trachea, aclidinium showed comparable potency to ipratropium and tiotropium, faster onset of action than tiotropium, and duration of action similar to tiotropium and significantly longer than ipratropium. Nebulized aclidinium inhibited bronchoconstriction induced by acetylcholine in guinea pigs in a concentration-dependent manner with an onset of action faster than tiotropium. Duration of action of aclidinium (t(1/2) = 29 h) was much longer than ipratropium (8 h) but shorter than tiotropium (64 h). In dogs, aclidinium induced a smaller and more transient increase in heart rate than tiotropium at comparable supratherapeutic doses. Therefore, under these conditions, aclidinium showed a greater therapeutic index than tiotropium (4.2 versus 1.6). These results indicate that aclidinium is a potent muscarinic antagonist with a fast onset of action, a long duration of effect, and a favorable cardiovascular safety profile.

Aspirin increases CD36, SR-BI, and ABCA1 expression in human THP-1 macrophages.

OBJECTIVE: CD36 is a receptor, whose expression increases during the differentiation of monocytes to macrophages, playing a key role in the phagocytosis of apoptotic cells and in the formation of foam cells during atherosclerosis. Recently, it has been described that ligands of PPARgamma induce CD36 expression and inhibit cyclooxygenase expression in macrophages. Our aim was to study whether the reduction of endogenous prostaglandin production could modify CD36 expression in macrophages and to outline the potential mechanism. METHODS AND RESULTS: CD36 expression was measured by flow cytometry in THP-1 cells differentiated to macrophages that had been incubated with aspirin (ASA) alone or in combination with PGE(2), sulprostone (EP1/EP3 agonist), butaprost (EP2 agonist,) and PGE1 alcohol (EP2/EP4 agonist). Aspirin induced CD36 expression. Only PGE(2) and PGE1 alcohol completely abolished CD36 induction by aspirin, whereas butaprost strongly reduced it. BADGE (a PPARgamma antagonist) or diclofenac (a PPARgamma antagonist and a cyclooxygenase inhibitor) in aspirin-incubated cells did not reduce CD36 induction. On the other hand, aspirin also induced the expression of SR-BI and ABCA1, an HDL receptor and an HDL formation-related protein, respectively. CONCLUSIONS: Aspirin produces an increase of CD36 expression in THP-1 macrophages by a PGE(2)-dependent mechanism. The PGE(2) receptors implicated in CD36 modulation by ASA are the EP2/EP4 subtypes. Further, we provide evidence of SR-BI and ABCA1 induction by aspirin treatment.

Reduction of intracellular cholesterol accumulation in THP-1 macrophages by a combination of rosiglitazone and atorvastatin.

Rosiglitazone and atorvastatin combination therapy has beneficial effects on both glycemic control and plasma lipid levels in type 2 diabetic patients. In the present study, we sought to determine whether this combination can also exert direct antiatherosclerotic effects in macrophages. Our results show that 2 microM rosiglitazone, alone or combined with 5 microM atorvastatin, significantly upregulated the expression of the ATP-binding cassette transporter ABCA1 and of the class B scavenger receptor CLA-1 (CD36 and LIMPII analog), both involved in cholesterol efflux from macrophages. On the other hand, the combination with atorvastatin attenuated the inductive response elicited by rosiglitazone alone on CD36 mRNA (34%, P < 0.05) and protein (16%, P < 0.05), while the uptake of oxidized low density lipoprotein (LDL) remained unaffected. When we examined the effects of the drugs on acetyl-LDL-induced cholesterol accumulation, we found that only the combination of atorvastatin with rosiglitazone caused a net depletion in the cholesteryl ester content of macrophages (35%, P < 0.05). Our data suggest that this reduction was not mediated by effects on proteins that regulate cholesterol flux, but it may be related to the inhibition of cholesteryl ester formation elicited by the statin.

Drosophila host defense after oral infection by an entomopathogenic Pseudomonas species.

Drosophila has been shown to be a valuable model for the investigation of host-pathogen interactions. Study of the Drosophila immune response has been hampered, however, by the lack of true Drosophila pathogens. In nearly all studies reported, the bacteria used were directly injected within the body cavity of the insect, bypassing the initial steps of a natural interaction. Here, we report the identification of a previously uncharacterized bacterial species, Pseudomonas entomophila (Pe), which has the capacity to induce the systemic expression of antimicrobial peptide genes in Drosophila after ingestion. In contrast to previously identified bacteria, Pe is highly pathogenic to both Drosophila larvae and adults, and its persistence in larvae leads to a massive destruction of gut cells. Using this strain, we have analyzed the modulation of the larval transcriptome upon bacterial infection. We found that natural infection by Pe induces a dramatic change in larval gene expression. In addition to immunity genes, our study identifies many genes associated with Pe pathogenesis that have been previously unreported.

Identification of the N-linked glycosylation sites on the high density lipoprotein (HDL) receptor SR-BI and assessment of their effects on HDL binding and selective lipid uptake.

The murine class B, type I scavenger receptor mSR-BI, a high density lipoprotein (HDL) receptor that mediates selective uptake of HDL lipids, contains 11 potential N-linked glycosylation sites and unknown numbers of both endoglycosidase H-sensitive and -resistant oligosaccharides. We have examined the consequences of mutating each of these sites (Asn --> Gln or Thr --> Ala) on post-translational processing of mSR-BI, cell surface expression, and HDL binding and lipid transport activities. All 11 sites were glycosylated; however, disruption of only two (Asn-108 and Asn-173) substantially altered expression and function. There was very little detectable post-translational processing of these two mutants to endoglycosidase H resistance and very low cell surface expression, suggesting that oligosaccharide modification at these sites apparently plays an important role in endoplasmic reticulum folding and/or intracellular transport. Strikingly, although the low levels of the 108 and 173 mutants that were expressed on the cell surface exhibited a marked reduction in their ability to transfer lipids from HDL to cells, they nevertheless bound nearly normal amounts of HDL. Indeed, the affinity of (125)I-HDL binding to the 173 mutant was similar to that of the wild-type receptor. Thus, N-linked glycosylation can influence both the intracellular transport and lipid-transporter activity of SR-BI. The ability to uncouple the HDL binding and lipid transport activities of mSR-BI by in vitro mutagenesis should provide a powerful tool for further analysis of the mechanism of SR-BI-mediated selective lipid uptake.