title: Involvement of TNF-α and MAPK pathway in the intramammary MMP-9 release via degranulation of cow neutrophils during acute mammary gland involution.
abstract: Neutrophil-derived MMP-9 activity is regulated more promptly and efficiently at the level of degranulation than at other levels of regulation. In human neutrophils, degranulation is one of the earliest responses to TNF-α stimulation, which involves protein kinase C and mitogen-activating protein kinase (MAPK) pathways. The level of MMP-9 in mammary secretion of cows increases drastically following milk-stasis, which is partially explained by increases of both neutrophil infiltration and neutrophil degranulation per se. Since MMP-9 represents one of the major remodeling capacities in the mammary gland of cows during early dry period, the current study attempted to explore the involved intracellular mechanisms in the up-regulated MMP-9 secretion. We repeatedly measured on the somatic cells of mammary secretion along the early dry period of cows the expression of TNF-α protein and the phosphorylation of p38 MAPK, ERK, and JNK. Also, cultures of bovine peripheral neutrophils were conducted to examine the mode of short-term MMP-9 secretion in response to TNF-α stimulation and the blocking effects of TNF-α antibody and inhibitors of MAPK pathways. Ex vivo measurements show that conventional cow milk has fully transformed into a neutrophil-abundant, lactoferrin-rich, and high-MMP-9 mammary secretion by d 7 in milk-stasis. No significant (P>0.05) change, however, was found in the expression of TNF-α or the phosphorylation extent of MAPK pathway intermediates on the somatic cells of mammary secretion during the first 3 weeks in milk-stasis. In vitro studies indicate linear increase of short-term MMP-9 release in response to TNF-α stimulation in dosages between 0.1 and 10 ng/ml. In the presence of preparations of d 7-dry secretion of cows, the short-term release of MMP-9 from bovine peripheral neutrophils was significantly (P<0.05) blocked by inhibitor of p38 MAPK but was significantly (P<0.05) promoted by ERK inhibitor while TNF-α antibody or JNK inhibitor exerted no effect. In conclusion, the current ex vivo measurements suggest no apparent association of TNF-α and MAPK pathway with long term intramammary accumulation of MMP-9 during the early dry period of cows, whereas cultures of bovine peripheral neutrophils under a simulated acute involution intramammary environment of cows suggest a role played by TNF-α and MAPK pathways in the short-term MMP-9 release via degranulation.
authors.affiliation: Department of Animal Science, National Chung Hsing University, Taichung 402, Taiwan, ROC.
authors.forename: Ting-Chieh
authors.initials: TC
authors.lastname: Yu
authors.forename: Shuen-Ei
authors.initials: SE
authors.lastname: Chen
authors.forename: Tsung-Hua
authors.initials: TH
authors.lastname: Ho
authors.forename: Huo-Cheng
authors.initials: HC
authors.lastname: Peh
authors.forename: Wen-Bor
authors.initials: WB
authors.lastname: Liu
authors.forename: Attapol
authors.initials: A
authors.lastname: Tiantong
authors.forename: Hajime
authors.initials: H
authors.lastname: Nagahata
authors.forename: Chai-Ju
authors.initials: CJ
authors.lastname: Chang
mesh_terms: D000818:Animals; D002417:Cattle / Q000033:anatomy & histology / Q000276:immunology* / Q000502:physiology*; D015550:Cell Degranulation / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007774:Lactation / Q000276:immunology / Q000502:physiology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008321:Mammary Glands, Animal / Q000033:anatomy & histology / Q000276:immunology / Q000502:physiology*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D008892:Milk / Q000201:enzymology / Q000276:immunology; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D047428:Protein Kinase Inhibitors; D014409:Tumor Necrosis Factor-alpha; D020780:Matrix Metalloproteinase 9