The expression of heat shock protein 70 in kidneys in cases of death due to hypothermia

Background: There exist only a few "typical" morphological signs of death due to hypothermia. For forensic practice, the identification of other reliable markers to determine hypothermia as cause of death is important. In the literature hypothermia is discussed as a stress factor for cells. It was the aim of this study to clarify wether an increased HSP 70 expression in the kidneys of fatal hypothermia victims can be observed. Material and methods: Kidney tissue samples of 100 fatal cases of hypothermia and 50 control cases without hypothermia and burning were investigated. The expression of HSP 70 in both study and control group was graded after immunohistochemical staining using a 4° scale from 0 up to +3. Results: Altogether, in the study group 89.0% in the tubule epithelium cells and 80.0% in the glomerula presented a HSP 70 expression of different grades. In the control group, 33 out of 50 cases were diagnosed completely without any HSP 70 expression in renal tubules, 17 cases showed a slight (+1) HSP 70 expression in the tubuli. In the glomeruli 42 cases of the control group were completely negative for HSP 70 expression, 8 cases showed a slight (+1) expression in the glomeruli. Conclusion: Our results show, that hypothermia is a stress factor inducing HSP 70 expression in the renal tubular epithelial cells and in the glomerular podocytes. Although HSP 70 expression was increased in the kidneys in cases of hypothermia, there was no strong correlation to Wischnewski's spots.