title: Staphylococcal Panton-Valentine leukocidin induces pro-inflammatory cytokine production and nuclear factor-kappa B activation in neutrophils.
abstract: Panton-Valentine leukocidin (PVL) is a cytotoxin secreted by Staphylococcus aureus and associated with severe necrotizing infections. PVL targets polymorphonuclear leukocytes, especially neutrophils, which are the first line of defense against infections. Although PVL can induce neutrophil death by necrosis or apoptosis, the specific inflammatory responses of neutrophils to this toxin are unclear. In this study, both in vivo and in vitro studies demonstrated that recombinant PVL has an important cytotoxic role in human neutrophils, leading to apoptosis at low concentrations and necrosis at high concentrations. Recombinant PVL also increased the levels of pro-inflammatory cytokine secretion from neutrophils. The up-regulation of pro-inflammatory cytokines was due to nuclear factor-kappa B (NF-κB) activation induced by PVL. Moreover, blocking NF-κB inhibited the production of inflammatory cytokines. To test the role of neutrophil immune responses during the pathogenesis of PVL-induced acute lung injury, we used immunocompetent or neutropenic rabbits to develop a model of necrotizing pneumonia. Immunocompetent rabbits challenged with PVL demonstrated increased inflammation containing neutrophilic infiltrates. In addition, there were elevated levels of inflammatory cytokines (IL-6, IL-8, TNF-α and IL-10) and NF-κB in the lung homogenate. In contrast, the lung tissues from neutropenic rabbits contained mild or moderate inflammation, and the levels of inflammatory cytokines and NF-κB increased only slightly. Data from the current study support growing evidence that neutrophils play an important role in the pathogenesis of PVL-induced tissue injury and inflammation. PVL can stimulate neutrophils to release pro-inflammatory mediators, thereby causing an acute inflammatory response. The ability of PVL to induce inflammatory cytokine release may be associated with the activation of NF-κB or its pore-forming properties.
authors.affiliation: Department of Laboratory Medicine, Anhui Provincial Hospital, Anhui Medical University, Hefei, China. xiaolingma@126.com
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Ma
authors.forename: Wenjiao
authors.initials: W
authors.lastname: Chang
authors.forename: Cuiping
authors.initials: C
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
authors.forename: Fangyou
authors.initials: F
authors.lastname: Yu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001427:Bacterial Toxins / Q000276:immunology / Q000494:pharmacology*; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis / Q000378:metabolism*; D005098:Exotoxins / Q000276:immunology / Q000494:pharmacology*; D006801:Humans; D007249:Inflammation / Q000276:immunology; D018836:Inflammation Mediators / Q000378:metabolism*; D007956:Leukocidins / Q000276:immunology / Q000494:pharmacology*; D008168:Lung / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D011994:Recombinant Proteins / Q000276:immunology / Q000494:pharmacology
chemical_list: D001427:Bacterial Toxins; D016207:Cytokines; D005098:Exotoxins; D018836:Inflammation Mediators; D007956:Leukocidins; D016328:NF-kappa B; C078284:Panton-Valentine leukocidin; D012333:RNA, Messenger; D011994:Recombinant Proteins