Lipopolysaccharides (LPS) are known to be involved in the pathogenesis of septic shock and multiorgan failure. It has been demonstrated that LPS may cause changes in monocyte cytoskeleton and directly influence assemblation of isolated microtubuli. As liver failure is increasingly observed during septic shock we estimated the influence of LPS on microtubule cytoskeleton of cultivated hepatocytes and human blood monocytes.
HepG2 cells, murine hepatocytes, or human monocytes (positive control) were incubated with LPS FITC labelled or unlabelled (0.1–200 μg/ml) up to 48 h. After staining with antibodies to tubulin and tau proteins cells were analysed by fluorescence and laser scan confocal microscopy. Activation of MAP-kinases was investigated by Western Blot using phosphospecific antibodies.
Immunofluorescence revealed that the cytoskeleton of hepatocytes was not affected by LPS. Furthermore, no phosphorylation of MAP-kinases was found after LPS-incubation. Mouse hepatocytes and HepG2 cells did not accumulate FITC labelled LPS. In contrast, human blood monocytes showed an accumulation of FITC-LPS, an activation of MAP-kinases and changes in microtubule cytoskeleton.
Our results might explain the frequently observed late onset of liver failure during sepsis-syndrom. Further studies on possible protective factors in hepatocytes and the complex co-operation between LPS and cytokines leading to hepatocellular damage are necessary.
Supported by Deutsche Forschungsgemeinschaft Re 653/5-1 and Thuringian Ministry of Science, Research and Culture F 3.1-908/7-143.