Table 1.
Thermal responses in Mutant and Wild-type mice subjected to heat stress.
Figure 1.
Core body temperature response of mutant and wild mice type to environmental heat stress.
Mice implanted intraperitoneally with radiotelemetric transmitters (Data Science International were allowed to recover for 2 weeks after surgery before subjected to heat stress or sham heat stress. (A) Core body temperature recorded in mutant and wild type mice at baseline (BL), and during sham heat exposure. (B) Core body temperature recorded in mutant and wild type mice at baseline, during cooling and recovery after heatstroke. Values represent median and IQR. *P<0.05 at T0+4 hours between the two groups tested by the generalized estimating equations model.
Figure 2.
Comparison of heatstroke-induced lethality in mutant and wild type mice.
Survival rates (%) of wild type and mutant mice after heatstroke are shown over 72 hours from the onset of heatstroke. Heatstroke was induced by passive exposure to environmental heat until the core temperature reached 42.7°C. **P<0.001 between the two groups analyzed by the Kaplan-Meier log-rank test.
Figure 3.
Histopathological comparison of heatstroke-induced liver injury in mutant and wild type mice.
Heatstroke was induced in mice by passive exposure to environmental heat until the core temperature reached 42.7°C. Sham-heated mice were used as control. Liver sections from mutant (A–D) and wild type (E–H) mice either sham-heated (A and E) or after induction of heatstroke (B–D and F–H, respectively) were stained with Hematoxylin & Eosin. In both mice strains, no morbid changes were observed after sham-heat stress (A and E). Heatstroke-induced in mutant mice resulted in hepato-cellular necrosis (arrows) and inflammatory cell infiltration (broken arrow) at onset (B), and massive perilobular necrosis with severe sinusoidal congestion (*) were observed at follow-up (C, D) time points. Minimal histopathological changes were noted in wild type subjected to heatstroke (F–H).
Figure 4.
Comparison of plasma IL-6, IL-1β and HMGB1 levels in mutant and wild type mice.
(A) Plasma levels (mean ± SD) of IL-6, (B) IL-1β and (C) HMGB1 are compared with mutant and wild type mice at the onset of heatstroke (T0) and at T0+0.5, +1, +4 and +24 hours post heatstroke. Plasma levels from sham-heated animals’ represent baseline. *P<0.05; **P<0.001; and ***P<0.0001 statistical significance at given time points between the two groups tested by the generalized estimating equations model.
Figure 5.
Inhibition of HMGB1 activity protects mutant mice against the lethal effects of heatstroke.
(A) SDS-PAGE analysis of the recombinant A-Box and GST control proteins expressed and purified from E. coli is shown. Increasing amounts of purified proteins were resolved by SDS-PAGE and stained with Coomassie blue; (B) Mutant mice were pretreated (i.p. injection) with A Box 600 µg/mouse; or GST control and heatstroke was induced by passive exposure to environmental heat until the core temperature reached 42.7°C. Pretreatment with A Box before heat stress protected the mutant mice against the lethal effects of heatstroke. *P = 0.04 Kaplan-Meier log-rank testing between the two groups.