Lipopolysaccharide-induced acute lung injury in mice chronically infected by Schistosoma mansoni.

We used a murine model of Schistosoma mansoni (SM) infection and lipopolysaccharide (LPS)-induced endotoxicity to investigate if these conditions can interact to modify the pathological manifestations typically observed in each condition. Swiss mice were randomized into four groups: SAL, uninfected; SM, infected; LPS, uninfected + LPS; and SM + LPS, infected + LPS. S. mansoni infection developed over 120 days, after which blood samples and lungs were collected, peritoneal leukocytes were isolated and cultivated for 6 and 24 h after LPS inoculation (1 mL/kg). Infected animals presented marked granulomatous inflammation. LPS exposure transiently modified the profile of leucocyte migration into the lung tissue and increased NO production by isolated leukocytes, without inducing any acute effect on the structure of schistosomiasis granulomas. Beyond modifying lung morphology, S. mansoni and LPS interacted to modulate the circulating levels of cytokines. S. mansoni infection restricted INF-γ upregulation 6 and 24 h after LPS administration. Conversely, 24 h after inoculation, LPS increased IL-2 and IL-5 levels. Our findings indicate that LPS impaired the lung microenvironment by acutely disrupting inflammatory homeostatic mechanisms that control lung schistosomiasis. As schistosomiasis develops as a chronic condition, long-term exposure to endotoxins could aggravate the granulomatous process, an issue that requires further investigation.