The absence of mrp4 has no effect on the recruitment of neutrophils and eosinophils into the lung after LPS, cigarette smoke or allergen challenge

• Published in: PloS one Vol. 8; no. 4; p. e61193
• Main Authors: Schymeinsky, Jürgen, Mayer, Hannah, Tomsic, Christopher, Tilp, Cornelia, Schuetz, John D, Cui, Yunhai, Wollin, Lutz, Gantner, Florian, Erb, Klaus J
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 22-04-2013; Public Library of Science (PLoS)
• Subjects: Adenosine; Adenosine - analogs & derivatives; Adenosine - pharmacology; Allergens; Allergens - immunology; Allergy; Alum; Aluminum sulfate; Alveoli; Analysis; Animal models; Animals; Asthma; Asthma - immunology; Asthma - metabolism; ATP Binding Cassette Transporter, Sub-Family G, Member 2; ATP-Binding Cassette Transporters - metabolism; Biology; Blood; Breast cancer; Bronchoalveolar lavage; Bronchoalveolar Lavage Fluid; Bronchus; Chronic obstructive pulmonary disease; Cigarette smoke; Cyclic adenosine monophosphate; Cyclic AMP; Cyclic AMP - blood; Cytokines; Cytokines - metabolism; Diketopiperazines; Eosinophils; Eosinophils - drug effects; Eosinophils - immunology; Exposure; Heterocyclic Compounds, 4 or More Rings; Inflammation; Inhibitors; Interleukin 4; Interleukin 5; Kinases; Leukocytes (eosinophilic); Leukocytes (neutrophilic); Lipopolysaccharides; Lipopolysaccharides - pharmacology; Lung - drug effects; Lung - immunology; Lung - metabolism; Lungs; Medicine; Mice; Microbial drug resistance; Multidrug resistance; Multidrug Resistance-Associated Proteins - deficiency; Multidrug Resistance-Associated Proteins - metabolism; Neutrophils; Neutrophils - drug effects; Neutrophils - immunology; Ovalbumin - immunology; Phosphodiesterase; Phosphodiesterase 4 Inhibitors - pharmacology; Plasma; Propionates - pharmacology; Proteins; Pulmonary Disease, Chronic Obstructive - immunology; Pulmonary Disease, Chronic Obstructive - metabolism; Quinolines - pharmacology; Recruitment; Respiratory diseases; Respiratory tract; Rodents; Rolipram - pharmacology; Smoke; Smoking; Smoking - adverse effects; Smooth muscle; Th2 Cells - drug effects; Th2 Cells - immunology; Time Factors; Transporter; Tumor necrosis factor-TNF; Tumor necrosis factor-α
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0061193

The multidrug resistance protein 4 (Mrp4) is an ATP-binding cassette transporter that is capable of exporting the second messenger cAMP from cells, a process that might regulate cAMP-mediated anti-inflammatory processes. However, using LPS- or cigarette smoke (CS)-inflammation models, we found that neutrophil numbers in the bronchoalveolar lavage fluid (BALF) were similar in Mrp4(-/-) and Mrp4(+/+) mice treated with LPS or CS. Similarly, neutrophil numbers were not reduced in the BALF of LPS-challenged wt mice after treatment with 10 or 30 mg/kg of the Mrp1/4 inhibitor MK571. The absence of Mrp4 also had no impact on the influx of eosinophils or IL-4 and IL-5 levels in the BALF after OVA airway challenge in mice sensitized with OVA/alum. LPS-induced cytokine release in whole blood ex vivo was also not affected by the absence of Mrp4. These data clearly suggest that Mrp4 deficiency alone is not sufficient to reduce inflammatory processes in vivo. We hypothesized that in combination with PDE4 inhibitors, used at suboptimal concentrations, the anti-inflammatory effect would be more pronounced. However, LPS-induced neutrophil recruitment into the lung was no different between Mrp4(-/-) and Mrp4(+/+) mice treated with 3 mg/kg Roflumilast. Finally, the single and combined administration of 10 and 30 mg/kg MK571 and the specific breast cancer resistance protein (BCRP) inhibitor KO143 showed no reduction of LPS-induced TNFα release into the BALF compared to vehicle treated control animals. Similarly, LPS-induced TNFα release in murine whole blood of Mrp4(+/+) or Mrp4(-/-) mice was not reduced by KO143 (1, 10 µM). Thus, BCRP seems not to be able to compensate for the absence or inhibition of Mrp4 in the used models. Taken together, our data suggest that Mrp4 is not essential for the recruitment of neutrophils into the lung after LPS or CS exposure or of eosinophils after allergen exposure.