The role of heat shock proteins in inflammatory injury induced by cold stress in chicken hearts

Abstract

The aim of this study was to investigate the effects of cold stress on the expression levels of heat shock proteins (Hsps90, 70, 60, 40, and 27) and inflammatory factors (iNOS, COX-2, NF-κB, TNF-α, and PTGEs) and oxidative indexes in hearts of chickens. Two hundred forty 15-day-old male chickens were randomly divided into 12 groups and kept at the temperature of 12 ± 1 °C for acute and chronic cold stress. There were one control group and five treatment groups for acute cold stress, three control groups, and three treatment groups for chronic cold stress. After cold stress, malondialdehyde level increased in chicken heart; the activity of superoxide dismutase and glutathione peroxidase in the heart first increased and then decreased. The inflammatory factors mRNA levels were increased in cold stress groups relative to control groups. The histopathological analysis showed that heart tissues were seriously injured in the cold stress group. Additionally, the mRNA levels of Hsps (70, 60, 40, and 27) increased significantly (P < 0.05) in the cold stress groups relative to the corresponding control group. Meanwhile, the mRNA level and protein expression of Hsp90 decreased significantly (P < 0.05) in the stress group, and showed a gradually decreasing tendency. These results suggested that the levels of inflammatory factors and Hsps expression levels in heart tissues can be influenced by cold stress. Hsps commonly played an important role in the protection of the heart after cold stress.

Fig. 1

H&E stained heart tissue sections of chicken: (a) heart of chicken from control group (H&E, ×400), (b) heart of chicken from 1-h stress group (H&E, ×400), (c) heart of chicken from 3-h group exposed to cold stress (H&E, ×400), (d) heart of chicken from 24-h group exposed to cold stress (H&E, ×400), (e) heart of chicken from 5-day group exposed to cold stress (H&E, ×400), and (f) heart of chicken from 20-day group exposed to cold stress (H&E, ×400)

Fig. 2

Effects of acute cold stress on the expression of iNOS, COX-2, NF-κB, TNF-α, and PTGEs genes in hearts of chickens. a–e The mRNA expression of iNOS, COX-2, NF-κB, TNF-α, and PTGEs genes in acute cold stress, respectively. Relative mRNA levels of the inflammatory genes were detected by qPCR, and the different letters over the bars in a–e indicate that there are significant differences (P < 0.05) between groups

Fig. 3

Effects of chronic cold stress on the mRNA expression of iNOS, COX-2, NF-κB, TNF-α, and PTGEs genes in heart of chickens. a–e The mRNA expression of iNOS, COX-2, NF-κB, TNF-α, and PTGEs genes in chronic cold stress, respectively. Relative mRNA levels of the iNOS, COX-2, NF-κB, TNF-α, and PTGEs genes were detected by qPCR. Asterisk, significant differences (P < 0.05) between the control group and the stress group at the same time point; each value represented the mean ± SD of six individuals

Fig. 4

Effects of acute cold stress on the hsp90, hsp70, hsp60, hsp40, and hsp27 genes mRNA expression in hearts of chickens. a–e The mRNA expression of hsp90, hsp70, hsp60, hsp40, and hsp27 genes, respectively. Relative mRNA levels of the hsps genes were detected by qPCR. In the acute cold stress experiment, the relative mRNA levels from the 0-h control group were used as the reference values in a–e. The different letters over the bars in a–e indicate that there are significant differences (P < 0.05) between groups. Each value represented the mean ± SD of six individuals

Fig. 5

Effects of chronic cold stress on the hsp90, hsp70, hsp60, hsp40, and hsp27 genes mRNA expression in hearts of chickens. a–e The mRNA expression of hsp90, hsp70, hsp60, hsp40, and hsp27 genes, respectively. In the chronic cold stress experiment, relative mRNA levels of the hsps genes were detected by qPCR; the relative mRNA levels from the 5-, 10-, and 20-day control group were used as the reference values in a–e. Each value represented the mean ± SD of six individuals. Asterisk, significant differences (P < 0.05) between the control group and the stress group at the same time point

Fig. 6

Effects of acute and chronic cold stress on the Hsp90, Hsp70, and Hsp60 protein expression in heart of chickens. a, b Acute and chronic cold stress groups, respectively. Acute cold stress groups (1, 3, 6, 12, and 24 h), 0 h = acute cold stress control group, chronic cold stress groups (5s, 10s, and 20s), and chronic corresponding control groups (5c, 10c, and 20c)