title: Dying blood mononuclear cell secretome exerts antimicrobial activity.
abstract: BACKGROUND
  Several activities are attributed to antimicrobial peptides (AMPs), including bacterial killing, leucocyte recruitment and angiogenesis. Despite promises of advanced cellular therapies for treatment of diabetic foot ulcer, it is currently accepted that paracrine factors rather than cellular components are causative for the observed effects. Whether AMPs are present in the mononuclear cell (MNC) secretome (MNC-sec) of white blood cells that are beneficial in experimental wound healing is not known.
  
  
  METHODS
  Antimicrobial activity of the secretomes of nonirradiated (MNC-sec) and γ-irradiated MNCs (MNC-sec rad) was analysed by microdilution assay. AMPs were determined by quantitative real-time PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). Whether human MNC-sec rad causes AMP secretion in vivo was examined in an experimental rat model. Image flow cytometry was used to determine the type of cell death induced in MNCs after exposure to γ-radiation.
  
  
  RESULTS
  The antimicrobial activity assay revealed a bactericidal activity of MNC-sec rad and to a lesser degree also of MNC-sec. Image flow cytometry showed that γ-irradiation of MNCs induced early apoptosis followed mainly by necroptosis. RT-PCR and ELISA revealed a high abundance of different AMPs in the secretome of MNCs. In addition, human MNC-sec elicited an increase in de novo endogenous AMP production in rats in vivo.
  
  
  CONCLUSIONS
  We provide evidence that the secretome of MNCs has direct and indirect positive effects on the immune defence system, including augmentation of antibacterial properties. Our data further suggest that necroptosis could play a key role for the release of paracrine factors and the therapeutic action of MNC-sec rad.
authors: Christian Doppler Laboratory for Cardiac and Thoracic Diagnosis and Regeneration, Vienna, Austria.
authors: Mohammad Mahdi
authors: MM
authors: Kasiri
authors: Christian Doppler Laboratory for Cardiac and Thoracic Diagnosis and Regeneration, Vienna, Austria.|Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.
authors: Lucian
authors: L
authors: Beer
authors: Division of Thoracic Surgery, Medical University of Vienna, Vienna, Austria.
authors: Lucas
authors: L
authors: Nemec
authors: Department of Dermatology, Medical University of Vienna, Vienna, Austria.|Christian Doppler Laboratory for Biotechnology of Skin Aging, Vienna, Austria.
authors: Florian
authors: F
authors: Gruber
authors: Translational Inflammation Research, Otto von Guericke University, Magdeburg, Germany.
authors: Sabine
authors: S
authors: Pietkiewicz
authors: Christian Doppler Laboratory for Cardiac and Thoracic Diagnosis and Regeneration, Vienna, Austria.
authors: Thomas
authors: T
authors: Haider
authors: Christian Doppler Laboratory for Cardiac and Thoracic Diagnosis and Regeneration, Vienna, Austria.
authors: Elisabeth Maria
authors: EM
authors: Simader
authors: Christian Doppler Laboratory for Cardiac and Thoracic Diagnosis and Regeneration, Vienna, Austria.
authors: Denise
authors: D
authors: Traxler
authors: Division of Thoracic Surgery, Medical University of Vienna, Vienna, Austria.
authors: Thomas
authors: T
authors: Schweiger
authors: Christian Doppler Laboratory for Cardiac and Thoracic Diagnosis and Regeneration, Vienna, Austria.
authors: Stefan
authors: S
authors: Janik
authors: Division of Thoracic Surgery, Medical University of Vienna, Vienna, Austria.
authors: Shahrokh
authors: S
authors: Taghavi
authors: Red Cross Blood Transfusion Service of Upper Austria, Linz, Austria.
authors: Christian
authors: C
authors: Gabriel
authors: Department of Dermatology, Medical University of Vienna, Vienna, Austria. michael.mildner@meduniwien.ac.at.
authors: Michael
authors: M
authors: Mildner
authors: Christian Doppler Laboratory for Cardiac and Thoracic Diagnosis and Regeneration, Vienna, Austria. hendrik.ankersmit@meduniwien.ac.at.|Division of Thoracic Surgery, Medical University of Vienna, Vienna, Austria. hendrik.ankersmit@meduniwien.ac.at.|Head FFG Project 852748 'APOSEC', Medical University of Vienna, Vienna, Austria. hendrik.ankersmit@meduniwien.ac.at.
authors: Hendrik Jan
authors: HJ
authors: Ankersmit
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000890:Anti-Infective Agents / Q000493:pharmacokinetics*; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism / Q000494:pharmacology*; D017209:Apoptosis / Q000528:radiation effects; D016923:Cell Death; D005720:Gamma Rays; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy*; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism* / Q000502:physiology; D008297:Male; D017207:Rats, Sprague-Dawley; D055815:Young Adult
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides
keywords: Antimicrobial peptides; MNC secretome; diabetic foot ulcer; mononuclear cell; peripheral blood mononuclear cells