title: TNF-alpha mediates eosinophil cationic protein-induced apoptosis in BEAS-2B cells.
abstract: BACKGROUND
  Eosinophilic granulocytes are important for the human immune system. Many cationic proteins with cytotoxic activities, such as eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN), are released from activated eosinophils. ECP, with low RNase activity, is widely used as a biomarker for asthma. ECP inhibits cell viability and induces apoptosis to cells. However, the specific pathway underlying the mechanisms of ECP-induced cytotoxicity remains unclear. This study investigated ECP-induced apoptosis in bronchial epithelial BEAS-2B cells and elucidated the specific pathway during apoptosis.
  
  
  RESULTS
  To address the mechanisms involved in ECP-induced apoptosis in human BEAS-2B cells, investigation was carried out using chromatin condensation, cleavage of poly (ADP-ribose) polymerase (PARP), sub-G1 distribution in cell cycle, annexin V labeling, and general or specific caspase inhibitors. Caspase-8-dependent apoptosis was demonstrated by cleavage of caspase-8 after recombinant ECP treatment, accompanied with elevated level of tumor necrosis factor alpha (TNF-alpha). Moreover, ECP-induced apoptosis was effectively inhibited in the presence of neutralizing anti-TNF-alpha antibody.
  
  
  CONCLUSIONS
  In conclusion, our results have demonstrated that ECP increased TNF-alpha production in BEAS-2B cells and triggered apoptosis by caspase-8 activation through mitochondria-independent pathway.
authors.affiliation: Department of Life Science, Institute of Biotechnology, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Kun-Che
authors.initials: KC
authors.lastname: Chang
authors.forename: Chih-Wei
authors.initials: CW
authors.lastname: Lo
authors.forename: Tan-Chi
authors.initials: TC
authors.lastname: Fan
authors.forename: Margaret Dah-Tsyr
authors.initials: MD
authors.lastname: Chang
authors.forename: Chih-Wen
authors.initials: CW
authors.lastname: Shu
authors.forename: Chuan-Hsin
authors.initials: CH
authors.lastname: Chang
authors.forename: Cheng-Ta
authors.initials: CT
authors.lastname: Chung
authors.forename: Shun-Lung
authors.initials: SL
authors.lastname: Fang
authors.forename: Chih-Chung
authors.initials: CC
authors.lastname: Chao
authors.forename: Jaw-Ji
authors.initials: JJ
authors.lastname: Tsai
authors.forename: Yiu-Kay
authors.initials: YK
authors.lastname: Lai
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D000906:Antibodies / Q000378:metabolism; D017209:Apoptosis; D053181:Caspase 8 / Q000378:metabolism; D045744:Cell Line, Tumor; D047150:Eosinophil Cationic Protein / Q000235:genetics / Q000378:metabolism*; D047208:Eosinophil-Derived Neurotoxin / Q000378:metabolism; D004804:Eosinophils / Q000276:immunology / Q000378:metabolism*; D016193:G1 Phase; D006801:Humans; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000378:metabolism*
chemical_list: D017304:Annexin A5; D000906:Antibodies; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D011065:Poly(ADP-ribose) Polymerases; D047208:Eosinophil-Derived Neurotoxin; D047150:Eosinophil Cationic Protein; D053181:Caspase 8