DNA damage focus analysis in blood samples of minipigs reveals acute partial body irradiation

PLoS One. 2014 Feb 3;9(2):e87458. doi: 10.1371/journal.pone.0087458. eCollection 2014.

Abstract

Radiation accidents frequently involve acute high dose partial body irradiation leading to victims with radiation sickness and cutaneous radiation syndrome that implements radiation-induced cell death. Cells that are not lethally hit seek to repair ionizing radiation (IR) induced damage, albeit at the expense of an increased risk of mutation and tumor formation due to misrepair of IR-induced DNA double strand breaks (DSBs). The response to DNA damage includes phosphorylation of histone H2AX in the vicinity of DSBs, creating foci in the nucleus whose enumeration can serve as a radiation biodosimeter. Here, we investigated γH2AX and DNA repair foci in peripheral blood lymphocytes of Göttingen minipigs that experienced acute partial body irradiation (PBI) with 49 Gy (± 6%) Co-60 γ-rays of the upper lumbar region. Blood samples taken 4, 24 and 168 hours post PBI were subjected to γ-H2AX, 53BP1 and MRE11 focus enumeration. Peripheral blood lymphocytes (PBL) of 49 Gy partial body irradiated minipigs were found to display 1-8 DNA damage foci/cell. These PBL values significantly deceed the high foci numbers observed in keratinocyte nuclei of the directly γ-irradiated minipig skin regions, indicating a limited resident time of PBL in the exposed tissue volume. Nonetheless, PBL samples obtained 4 h post IR in average contained 2.2% of cells displaying a pan-γH2AX signal, suggesting that these received a higher IR dose. Moreover, dispersion analysis indicated partial body irradiation for all 13 minipigs at 4 h post IR. While dose reconstruction using γH2AX DNA repair foci in lymphocytes after in vivo PBI represents a challenge, the DNA damage focus assay may serve as a rapid, first line indicator of radiation exposure. The occurrence of PBLs with pan-γH2AX staining and of cells with relatively high foci numbers that skew a Poisson distribution may be taken as indicator of acute high dose partial body irradiation, particularly when samples are available early after IR exposure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Nucleus / genetics
  • Cell Nucleus / metabolism
  • Cell Nucleus / radiation effects
  • DNA Breaks, Double-Stranded / radiation effects*
  • DNA Damage*
  • DNA Repair Enzymes / metabolism
  • DNA-Binding Proteins / metabolism
  • Dose-Response Relationship, Radiation
  • Female
  • Histones / metabolism*
  • Immunohistochemistry
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Lymphocytes / metabolism
  • Lymphocytes / radiation effects
  • Microscopy, Fluorescence
  • Phosphorylation / radiation effects
  • Radiation, Ionizing*
  • Radiometry / methods
  • Reproducibility of Results
  • Swine
  • Swine, Miniature

Substances

  • DNA-Binding Proteins
  • Histones
  • Intracellular Signaling Peptides and Proteins
  • DNA Repair Enzymes

Grant support

The work was supported by the German Ministry of Defense and the French Ministry of Defense. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.