Pretreatment with heat decreases mortality and acute lung injury in the rat
septic shock model, presumably by the production of heat shock proteins (H
SP). However, endotoxin, a severe cell stresser, has not been shown to indu
ce HSP 70. We investigated the effects of severe endotoxemia on the express
ion of specific protective stress proteins, including HSP 72 (inducible HSP
70), HSP 32 (heme oxygenase-1), and HSP 90. Fifteen rats received intraven
ously either 3 mg/kg of endotoxin (E. coli O 127:B8 lipopolysaccharide, LPS
) (n=9) or saline (n=6). Two hr later the spleen was removed and splenocyte
s were separated into three groups and analyzed for specific HSP by Western
blot. In Group 1, both endotoxin-treated and saline-treated splenocytes we
re incubated for 3 hr at 37 degrees C. In Group 2, the splenocytes were was
hed twice, then heat shocked for 30 min at 42 degrees C and subsequently in
cubated for 2.5 hr at 37 degrees C. Tn Group 3, splenocytes were washed twi
ce, then incubated for 3.0 hr at 37 degrees C. HSP 30 & HSP 70c (constituti
ve) were present in all groups. Consistent with observations by others, HSP
72 was not induced in Group 1. HSP 72 was induced in both the saline-treat
ed and endotoxin-treated splenocytes after heating (Group 2). However, in t
he absence of heat stress, HSP 72 was present in endotoxin-treated but nor
in saline-treated splenocytes after incubation (Croup 3). Conversely, HSP 3
2, while present in Group 1 splenocytes, was not detected in the endotoxin-
treated splenocytes of Group 2 and Group 3, but was present in the saline-t
reated cells. In conclusion, endotoxemic shock results in induction of HSP
72 and depletion of HSP 32, but only after the cells have been washed and f
urther incubated.