Tulathromycin Exerts Proresolving Effects in Bovine Neutrophils by Inhibiting Phospholipases and Altering Leukotriene B4, Prostaglandin E2, and Lipoxin A4 Production

• Published in: Antimicrobial agents and chemotherapy Vol. 58; no. 8; pp. 4298 - 4307
• Main Authors: FISCHER, Carrie D, DUQUETTE, Stephanie C, RENAUX, Bernard S, FEENER, Troy D, MORCK, Douglas W, HOLLENBERG, Morley D, LUCAS, Merlyn J, BURET, Andre G
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01-08-2014
• Subjects: Animals; Anti-Inflammatory Agents, Non-Steroidal; Anti-Inflammatory Agents, Non-Steroidal - pharmacology; Antibiotics. Antiinfectious agents. Antiparasitic agents; Biological and medical sciences; Bronchoalveolar Lavage Fluid - chemistry; Calcimycin - pharmacology; Cattle; Dinoprostone; Dinoprostone - antagonists & inhibitors; Dinoprostone - biosynthesis; Disaccharides; Disaccharides - pharmacology; Heterocyclic Compounds; Heterocyclic Compounds - pharmacology; Hydroxyeicosatetraenoic Acids - metabolism; Leukotriene B4; Leukotriene B4 - antagonists & inhibitors; Leukotriene B4 - biosynthesis; Lipoxins; Lipoxins - agonists; Lipoxins - biosynthesis; Lung - drug effects; Lung - metabolism; Lung - pathology; Male; Mannheimia; Mechanisms of Action: Physiological Effects; Medical sciences; Neutrophils - drug effects; Neutrophils - metabolism; Neutrophils - pathology; Particulate Matter; Pharmacology. Drug treatments; Phospholipases A2; Phospholipases A2 - metabolism; Pneumonia; Pneumonia - chemically induced; Pneumonia - drug therapy; Pneumonia - metabolism; Pneumonia - pathology; Primary Cell Culture; Zymosan; Bovine; Enzyme; Arachidonic acid derivatives; Granulocyte; Prostaglandin E2; Ox; Esterases; Biosynthesis; Macrolide; Phospholipase; Vertebrata; Mammalia; Leukotriene B4; Animal; Tulathromycin; Production; Hydrolases; Artiodactyla; Protein synthesis inhibitor; Neutrophil; Antibacterial agent; Veterinary; Ungulata
• ISSN: 0066-4804; 1098-6596
• DOI: 10.1128/AAC.02813-14

The accumulation of neutrophils and proinflammatory mediators, such as leukotriene B4 (LTB4), is a classic marker of inflammatory disease. The clearance of apoptotic neutrophils, inhibition of proinflammatory signaling, and production of proresolving lipids (including lipoxins, such as lipoxin A4 [LXA4]) are imperative for resolving inflammation. Tulathromycin (TUL), a macrolide used to treat bovine respiratory disease, confers immunomodulatory benefits via mechanisms that remain unclear. We recently reported the anti-inflammatory properties of TUL in bovine phagocytes in vitro and in Mannheimia haemolytica-challenged calves. The findings demonstrated that this system offers a powerful model for investigating novel mechanisms of pharmacological immunomodulation. In the present study, we examined the effects of TUL in a nonbacterial model of pulmonary inflammation in vivo and characterized its effects on lipid signaling. In bronchoalveolar lavage (BAL) fluid samples from calves challenged with zymosan particles (50 mg), treatment with TUL (2.5 mg/kg of body weight) significantly reduced pulmonary levels of LTB4 and prostaglandin E2 (PGE2). In calcium ionophore (A23187)-stimulated bovine neutrophils, TUL inhibited phospholipase D (PLD), cytosolic phospholipase A2 (PLA2) activity, and the release of LTB4. In contrast, TUL promoted the secretion of LXA4 in resting and A23187-stimulated neutrophils, while levels of its precursor, 15(S)-hydroxyeicosatetraenoic acid [15(S)-HETE], were significantly lower. These findings indicate that TUL directly modulates lipid signaling by inhibiting the production of proinflammatory eicosanoids and promoting the production of proresolving lipoxins.