Induction of heat-shock proteins by bacterial toxins, lipid mediators and cytokines in human leukocytes

Abstract

We studied the influence of a lipid mediator (12-hydroxyeicosatetraenoic acid, 12-HETE), cytokines (IL-6 and TNF-alpha) and different bacterial toxins (alveolysin; exfoliative toxin; toxic shock syndrome toxin 1, TSST-1 and erythrogenic toxin A, ETA) on the expression of heat shock proteins (hsps) in isolated human leucocytes. 12-HETE induces the expression of individual heat shock proteins (65- and 83 kDa) protein in human leukocytes (lymphocytes, monocytes, basophilic granulocytes; LMBs). As was shown by Western blotting (anti-hsp72), IL-6 or TNF-alpha induced hsps preferentially in human LMBs and PMNs, respectively. Among the toxins, ETA and TSST-1 were potent inducers of hsps at low toxin concentrations (10 ng/ml). Alveolysin led to the expression of hsps at hemolytic concentrations (1 HU; 700 ng/ml) whereas at subhemolytic concentrations (7 ng/ml), no heat shock response was observed. The induction of heat shock proteins was also accompanied by increased mRNA levels for hsp70 as determined by PCR analysis. In contrast, exfoliative toxin led to a reduction of the hsp signal in PMNs as determined by Western blotting. Finally, it was demonstrated that PMNs which had been pretreated with TNF-alpha and therefore expressed intracellular hsps were more resistant to cytolytic attack by leukocidin than untreated cells.