title: Role of leptin in modulation of Porphyromonas gingivalis lipopolysaccharide-induced up-regulation of endothelin-1 in salivary gland acinar cells.
abstract: Leptin, a pleiotropic cytokine that regulates food intake and metabolic and endocrine responses, has emerged recently as an important regulator of mucosal inflammatory responses to bacterial infection. In this study, we report that in sublingual salivary gland acinar cells leptin plays a role in the suppression of up-regulation in endothelin-1 (ET-1), induced by the LPS of a periodontopathic bacterium P. gingivalis. We show that P. gingivalisLPS detrimental effect on salivary mucin synthesis, associated with up-regulation (3.9-fold) in ET-1 generation and the enhancement (3.2-fold) in endothelin-converting enzyme-1 (ECE-1) activity, was subject to a dose-dependent suppression by leptin. The impedance by leptin of the LPS inhibitory effect on mucin synthesis was blocked by wortmannin, an inhibitor of PI3K, as well as by ERK inhibitor, PD98059. However, while the blockade of ERK led also to amplification in the impedance by leptin of the LPS-induced expression of ECE-1 and ET-1, the effect was not observed in the presence of wortmannin. The findings are the first to demonstrate that leptin counters the pathological consequences of P. gingivalisinfection on the synthesis of salivary mucin through the involvement in signaling events of PI3K and ERK pathways. We also show that the ERK cascade represents a critical signaling target for leptin in the LPS-induced up-regulation in ET-1.
authors.affiliation: Research Center, University of Medicine and Dentistry of New Jersey, Newark 07103-2400, USA. slomiabr@umdnj.edu
authors.forename: Bronislaw L
authors.initials: BL
authors.lastname: Slomiany
authors.forename: Amalia
authors.initials: A
authors.lastname: Slomiany
mesh_terms: D000704:Analysis of Variance; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D020738:Leptin / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000633:toxicity*; D009077:Mucins / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D016966:Porphyromonas gingivalis / Q000737:chemistry*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013361:Sublingual Gland / Q000166:cytology / Q000378:metabolism*; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D019332:Endothelin-1; D005419:Flavonoids; D020738:Leptin; D008070:Lipopolysaccharides; D009077:Mucins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D048049:Extracellular Signal-Regulated MAP Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000077191:Wortmannin