Gradual development of organ damage in the murine zymosan-induced multiple organ dysfunction syndrome

A well defined animal model is a prerequisite to test intervention strategies aimed at preventing the development of the multiple organ dysfunction syndrome. This study compares changes in clinical parameters to histopathologic changes in tissues, observed over a 12 day period after a single intraperitoneal injection of zymosan in C57BL/6 mice. Administration of zymosan induced gradual and progressive changes in wet and dry organ weight of the liver, kidneys, and particularly, lungs and spleen that correlated with increasing histopathology. From 6 days after zymosan injection onwards, hemorrhagic spots were found in the lungs evolving into massive hemorrhages at 12 days, when thickened interstitial walls and loss of the honey comb-like structures were observed. The liver displayed progressive accumulation of macrophage-like and mononuclear cells. After 12 days, numerous granuloma-like structures were disseminated throughout the liver parenchyma. The spleen displayed great changes in red and white pulp with increasing numbers of megakaryocytes and plasma-like cells. In the kidneys, necrosis of the tubular epithelium adjacent to granulomas on the ventral (peritoneal) side was found. In mice, a single intraperitoneal challenge with zymosan leads to progressive multiple organ damage, which becomes apparent at some time after the insult. This animal model displays a number of features encountered in human multiple organ dysfunction syndrome and appears suitable to conduct intervention studies.