Inhibition of LPS-induced airway neutrophilic inflammation in healthy volunteers with an oral CXCR2 antagonist

Abstract

Background: Inhaled lipopolysaccharide (LPS) induces a dose-dependent, acute neutrophilic response in the airways of healthy volunteers that can be quantified in induced sputum. Chemokines, such as CXCL1 and CXCL8, play an important role in neutrophilic inflammation in the lung through the activation of CXCR2 and small molecule antagonists of these receptors have now been developed. We investigated the effect of AZD8309, a CXCR2 antagonist, compared with placebo on LPS-induced inflammation measured in sputum of healthy volunteers.

Methods: Twenty healthy subjects were randomized in a double-blind placebo-controlled, cross-over study. AZD8309 (300 mg) or placebo was dosed twice daily orally for 3 days prior to challenge with inhaled LPS and induced sputum was collected 6 h later.

Results: Treatment with AZD8309 showed a mean 77% reduction in total sputum cells (p < 0.001) and 79% reduction in sputum neutrophils (p < 0.05) compared with placebo after LPS challenge. There was also a reduction in neutrophil elastase activity (p < 0.05) and CXCL1 (p < 0.05) and trends for reductions in sputum macrophages (47%), leukotriene B4 (39%) and CXCL8 (52%).

Conclusions: AZD8309 inhibited LPS-induced inflammation measured in induced sputum of normal volunteers, indicating that this treatment may be useful in the treatment of neutrophilic diseases of the airways, such as COPD, severe asthma and cystic fibrosis.

Trial registration: NCT00860821.

Figures

Figure 1

Study design. After a screening visit (visit 1) treatment period 1 was comprised of visits 2 and 3 and treatment period 2 was comprised of visits 4 and 5. Eligible randomized subjects returned to the clinic (visit 2) 7–21 days following visit 1 and were dosed with either 300 mg AZD8309 or placebo at 09:00 hours and were discharged with instructions for continued dosing at home. Subjects returned for LPS challenge the following morning (visit 3). Six hours post-completion of the LPS inhalation, subjects produced an induced sputum sample. There was a washout period between visits 3 and 4 of at least 21 days. Treatment period 2 was structured the same as treatment period 1.

Figure 2

Effect of AZD8309 on cell counts in sputum post LPS challenge. Total cell counts (top left plot) were performed by trypan blue exclusion with a hemocytometer. Differential cell counts for neutrophils (top right plot) and macrophages (bottom centre plot) were performed with cytospin preparations. Bars show the mean values of 15–16 patients. Open bars represent placebo and solid bars AZD8309. Results are expressed as geometric mean. CVs are shown in Table 2. Statistics by ANOVA, ** = P < 0.001 and * = P < 0.05.

Figure 3

Effect of AZ8309 on mediator concentrations in sputum supernatant. Sputum samples were collected 6 hours post challenge with LPS. There was a reduction in concentrations of CXCL8 (top left plot), CXCL1 (top right plot), neutrophil elastase activity (NEA) (bottom left plot) and leukotriene B4 (LTB4) (Bottom right plot); mean values of 13–16 patients are shown. Open bars represent placebo and solid bars AZD8309. Results are expressed as geometric mean. CVs are shown in Table 3. Statistics by ANOVA, * = P < 0.05.

Figure 4

Effect of AZD8309 on circulating blood neutrophils pre and post challenge with lipopolysaccharide. Blood neutrophils numbers were measured at predose (t = 0) and at 7 hours post dosing on day 1 and at trough (t = 0) and at 1, 3, 7, 12 and 25 hours post dosing on day 3. The solid black circles show the effects on placebo treatment and the open grey circles show effects after treatment with AZD8309. The arrow indicates the point at which subjects were challenged with LPS on day 3. Each point is presented as mean with s.e.m.

Figure 5

Effect of AZD8309 on FEV1 after inhaled lipopolysaccharide (LPS). There was a similar peak fall in FEV1 at 1 h after challenge, then a more rapid recovery after AZD8309 compared to placebo, with a significant reduction in area under the curve (P < 0.05). The average values for the coefficient of variances were 14.4% and 15% for AZD8309 and placebo respectively. Mean values of 16 patients are shown.