Dual bronchodilatory and pulmonary anti-inflammatory activity of RO5024118, a novel agonist at vasoactive intestinal peptide VPAC2 receptors

Abstract

Background and purpose: Vasoactive intestinal peptide is expressed in the respiratory tract and induces its effects via its receptors, VPAC(1) and VPAC(2). RO5024118 is a selective VPAC(2) receptor agonist derived via chemical modification of an earlier VPAC(2) agonist, RO0251553. In the present studies, we characterized the pharmacological activity of RO5024118.

Experimental approach: Stability of RO5024118 to human neutrophil elastase was assessed. Bronchodilatory activity of RO5024118 was investigated in guinea pig and human isolated airway smooth muscle preparations and in a guinea pig bronchoconstriction model. Pulmonary anti-inflammatory activity of RO5024118 was investigated in a lipopolysaccharide mouse model and in a porcine pancreatic elastase (PPE) rat model.

Key results: RO5024118 demonstrated increased stability to neutrophil elastase compared with RO0251553. In human and guinea pig isolated airway preparations, RO5024118 induced bronchodilatory effects comparable with RO0251553 and the long-acting β-agonist salmeterol and was significantly more potent than native vasoactive intestinal peptide and the short-acting β-agonist salbutamol. In 5-HT-induced bronchoconstriction in guinea pigs, RO5024118 exhibited inhibitory activity with similar efficacy as, and longer duration than, RO0251553. In a lipopolysaccharide-mouse model, RO5024118 inhibited neutrophil and CD8(+) cells and myeloperoxidase levels. In rats, intratracheal instillation of PPE induced airway neutrophilia that was resistant to dexamethasone. Pretreatment with RO5024118 significantly inhibited PPE-induced neutrophil accumulation.

Conclusions and implications: These results demonstrate that RO5024118 induces dual bronchodilatory and pulmonary anti-inflammatory activity and may be beneficial in treating airway obstructive and inflammatory diseases.

Linked articles: This article is part of a themed section on Analytical Receptor Pharmacology in Drug Discovery. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2010.161.issue-6.

Figure 1

The amino acid sequence for RO5024118. This structure differs from that of RO 0251553 by the CαMeVal residue at position 5. The line from Lys21 to Asp25 represents a lactam link between the side chains.

Figure 2

Effects of RO5024118, RO0251553, native vasoactive intestinal peptide (VIP) and RO4983407 on cAMP levels in Sup-T1 cells, expressing the VPAC₂ receptor (A) and HT-29 cells, expressing the VPAC₁ receptor (B). In the absence of ligands, the basal cytoplasmic cAMP levels were 67.5 ± 7.5 fmol per 100 µL of Sup-T1 lysate and 62 ± 26 fmol per 20 µL of HT-29 lysate. Data are mean ± SEM of 3–4 experiments.

Figure 3

Comparison of the stability of RO5024118 to human neutrophil elastase with vasoactive intestinal peptide (VIP) and RO0251553. Stability of the substrates was evaluated by HPLC followed by mass spectrometry. Survival of each peptide is shown as % relative abundance of the unchanged substrate.

Figure 4

Effects of RO5024118, RO0251553, salbutamol and native vasoactive intestinal peptide (VIP) on guinea pig tracheal rings, pre-contracted with carbachol. Data are mean ± SEM of 6–7 tissues per group. **P < 0.01, ***P < 0.001 for test compounds versus vehicle; ##P < 0.01, ###P < 0.001 for RO5024118 versus VIP.; ++P < 0.01 RO5024118 versus salbutamol.

Figure 5

Effects of cumulative concentrations of RO5024118, RO0251553 and native vasoactive intestinal peptide (A) and salbutamol and salmeterol (B) on human bronchial rings, pre-contracted with histamine. Data are mean ± SEM of 6 rings per group. **P < 0.01, ***P < 0.001 for test compounds versus vehicle; ##P < 0.01, ###P < 0.001 RO5024118 versus VIP; ++P < 0.01 RO5024118 versus salbutamol.

Figure 6

Effects of immediate pretreatment with RO5024118 (0.001–0.03% w/v, A) on 5-HT-induced bronchoconstriction in conscious guinea pigs and in comparison with RO0251553 at 0.1% immediately (B) and 2 h prior to (C) 5-HT. Data are mean ± SEM of 4–12 animals per group. *P < 0.05, **P < 0.01 versus vehicle.

Figure 7

Effects of immediate pretreatment of RO5024118 (0.003–0.03% w/v, A) on 5-HT-induced changes in lung resistance (A) and dynamic compliance (B) in anaesthetized, mechanically ventilated guinea pigs. Data are mean ± SEM of 5–7 animals per group. **P < 0.01, ***P < 0.001 versus vehicle.

Figure 10

Effects of RO5024118 (0.01–0.1% w/v) on MPO levels in the bronchoalveolar lavage fluid of mice 24 h after exposure to lipopolysaccharide. Data are mean ± SEM of eight animals per group. **P < 0.01 versus vehicle.

Figure 9

Effects of RO5024118 (0.01–0.1%) on % of CD4+ T cells (A) and CD8+ T cells (B) in the bronchoalveolar lavage fluid of mice 24 h after exposure to lipopolysaccharide. Data are mean ± SEM of eight animals per group. *P < 0.05 versus vehicle.

Figure 8

Effects of RO5024118 (0.00003–0.1% w/v) on total cells (A), neutrophils (B), macrophages (C) and lymphocytes (D) in the bronchoalveolar lavage (BAL) fluid of mice 24 h after exposure to LPS. Data are mean ± SEM of five experiments. **P < 0.01 versus vehicle; ###P < 0.001 versus sham.

Figure 11

Effects of RO5024118 (0.0003–0.001% w/v) on inflammatory cells in the bronchoalveolar lavage (BAL) fluid of rats 24 h after intratracheal instillation of porcine pancreatic elastase. Data are mean ± SEM of four experiments. *P < 0.05, **P < 0.01 versus vehicle.