Peroxisome proliferator-activated receptor (PPAR)-c is expressed in alveolar macrophages. The anti-inflammatory potential of the PPAR-c ligands rosiglitazone and pioglitazone were investigated using in vitro alveolar macrophage models and in vivo animal models relevant to chronic obstructive pulmonary disease (COPD).PPAR-c protein and gene expression in COPD alveolar macrophages was compared with control smokers and never-smokers. COPD macrophages were used to investigate the effects of PPAR-c ligands and corticosteroids on lipopolysaccharide-induced cytokine production, alternative macrophage activation (M2) gene expression and efferocytosis. The effects of PPAR-c ligands in a subchronic tobacco smoke model in mice were investigated.PPAR-c protein expression was similar in COPD patients compared to controls, although increased gene expression levels were observed in COPD patients and control smokers compared to never-smokers. PPAR-c ligands reduced tumour necrosis factor-a and CC chemokine ligand-5, but not CXC chemokine ligand-8, in COPD alveolar macrophages; these effects were generally less than those of the corticosteroid dexamethasone. Rosiglitazone increased M2 gene expression and enhanced efferocytosis of apoptotic neutrophils. Rosiglitazone and pioglitazone attenuated airway neutrophilia in a corticosteroid-resistant mouse model of pulmonary inflammation.We show biological actions of PPAR-c agonists on corticosteroid-resistant disease, tobacco smokeinduced pulmonary inflammation, skewing of macrophage phenotype and clearance of apoptotic neutrophils.@ERSpublications Biological actions of a PPAR-c agonist shown in COPD-relevant models may affect progression and side-effects in patients

Chronic obstructive pulmonary disease (COPD) is characterized by pulmonary inflammation, which is relatively insensitive to inhaled corticosteroids. The extent of the pulmonary inflammation in COPD correlates with disease severity, and it is thought to play a significant role in disease progression. We have evaluated a selective p38␣-selective mitogen-activated protein kinase (MAPK) inhibitor, indole-5-carboxamide (ATPcompetitive inhibitor of p38 kinase) (SD-282), in an 11-day model of tobacco smoke (TS)-induced pulmonary inflammation in A/J mice, by using dexamethasone as a reference steroid. Two oral treatment paradigms were evaluated in this TS model: prophylactic with daily pretreatment before each daily exposure, and therapeutic with daily treatment for 6 days commencing after 5 days of smoke exposure. Bronchoalveolar lavage and histological evaluation of lung sections taken after exposure to TS revealed an inflammatory response composed of increased numbers of macrophages and neutrophils and enhanced mucin staining. Phospho-p38 staining in macrophages and type II epithelial cells after TS exposure was also observed. Given prophylactically or therapeutically, dexamethasone failed to inhibit any of the TS-induced inflammatory changes. By contrast, SD-282 inhibited TS-induced increases in macrophages and neutrophils. Furthermore, SD 282 reduced TS-induced increases in cyclooxygenase-2 and interleukin-6 levels, and phospho-p38 expression in the lungs. In conclusion, SD-282 markedly reduced TS-induced inflammatory responses when given prophylactically or therapeutically whereas dexamethasone was ineffective. This is the first evidence that a p38␣-selective MAPK inhibitor can exert pulmonary anti-inflammatory activity in a TS exposure model when given in a therapeutic mode, establishing the potential of p38 MAPK inhibitors as a therapy for COPD.

Using a semimicromethod with washed whole blood, in vitro lymphocyte responses of rabbits to intradermal infection with vaccinia virus was studied. Peritoneal exudate macrophages were infected with vaccinia in vitro to determine the time of appearance of activated macrophages. After primary infection, an increase in spontaneous incorporation of thymidine by blood cultures was found as early as 2 days postinfection. This effect was at a maximum at 7 to 10 days, with counts up to 100-fold higher than before infection. Incubation of these cultures with concanavalin A showed a marked decrease in stimulation index as compared with normals. Although only a transient stimulation with vaccinia was found during the acute infection, stimulation indexes of 2 to 3 were obtained during convalescence. Macrophages from rabbits early after infection supported vaccinia replication, whereas those at day 6 or later resisted infection. Macrophage resistance persisted for 2 to 3 weeks. The response of lymphocytes from rabbits reinfected with vaccinia after 15 weeks differed, with a small increase in spontaneous thymidine uptake, a smaller depression in concanavalin A stimulation, and a greater specific response to vaccinia. Macrophage activation occurred earlier and persisted for a longer time after secondary infection.

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