Immunosuppression Induced by Perioperative Peritonitis Promotes Lung Metastasis.

Abstract

Perioperative intra-abdominal infection has been reported as a risk factor for metastasis. The aim of this study was to investigate the mechanism by which peritonitis induces immunosuppression in the lung, which in turn promotes lung metastasis. C57BL/6 mice were intravenously administered B16F10 melanoma cells to induce lung metastasis and subsequently subjected to cecal ligation and puncture (CLP) to induce peritonitis or sham surgery. The number of lung metastatic nodules was evaluated. Cell fractions in lungs and serum cytokines after CLP were investigated. CLP mice showed an increased number of lung metastases compared to sham-treated mice. The fraction and number of natural killer (NK) cells in lungs of CLP mice were significantly reduced in early post-CLP phase. Myeloid-derived suppressor cells (MDSCs) in lungs were significantly decreased in CLP mice. Serum IL-6 and TNF levels were significantly elevated in CLP mice. Peritonitis promoted lung metastasis in a murine model, which may be attributable to the impact of NK cells and MDSCs in the lungs.