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Lipopolysaccharide preconditioning protects hepatocytes from ischemia/reperfusion injury (IRI) through inhibiting ATF4-CHOP pathway in mice.

Rao J, Qin J, Qian X, Lu L, Wang P, Wu Z, Zhai Y, Zhang F, Li G, Wang X - PLoS ONE (2013)

Bottom Line: As demonstrated by in vitro experiments, LPS preconditioning significantly reduced the upregulation of the ATF4-CHOP pathway and inhibited Caspase-12 and Caspase-3 activation after IRI.Importantly, ATF4 siRNA is consistent with results of LPS preconditioning in macrophages.This work is the first time to provide evidence for LPS preconditioning protects hepatocytes from IRI through inhibiting ATF4-CHOP pathway, which may be critical to reducing related apoptosis molecules and modulating innate inflammation.

View Article: PubMed Central - PubMed

Affiliation: Liver Transplantation Center, The First Affiliated Hospital of Nanjing Medical University, Key Laboratory of Living Donor Liver Transplantation of Ministry of Public Health, Nanjing, PR China.

ABSTRACT

Background: Low-dose lipopolysaccharide (LPS) preconditioning-induced liver protection has been demonstrated during ischemia-reperfusion injury (IRI) in several organs but has not been sufficiently elucidated underlying causal mechanism. This study investigated the role of low-dose LPS preconditioning on ATF4-CHOP pathway as well as the effects of the pathway on tissue injury and inflammation in a mouse model of liver partial-warm IRI.

Methods: LPS (100 µg/kg/d) was injected intraperitoneally two days before ischemia. Hepatic injury was evaluated based on serum alanine aminotransferase levels, histopathology, and caspase-3 activity. The ATF4-CHOP pathway and its related apoptotic molecules were investigated after reperfusion. The role of LPS preconditioning on apoptosis and ATF4-CHOP pathway was examined in vitro. Moreover, the effects of the ATF4-CHOP pathway on apoptosis, Caspase-12, and Caspase-3 were determined with ATF4 small interfering RNA (siRNA). Inflammatory cytokine expression was also checked after reperfusion. Inflammatory cytokines and related signaling pathways were analyzed in vitro in macrophages treated by LPS preconditioning or ATF4 siRNA.

Results: LPS preconditioning significantly attenuated liver injury after IRI. As demonstrated by in vitro experiments, LPS preconditioning significantly reduced the upregulation of the ATF4-CHOP pathway and inhibited Caspase-12 and Caspase-3 activation after IRI. Later experiments showed that ATF4 knockdown significantly suppressed CHOP, cleaved caspase-12 and caspase-3 expression, as well as inhibited hepatocellular apoptosis. In addition, in mice pretreated with LPS, TNF-α and IL-6 were inhibited after reperfusion, whereas IL-10 was upregulated. Similarly, low-dose LPS significantly inhibited TNF-α, IL-6, ATF4-CHOP pathway, NF-κB pathway, and ERK1/2 in high-dose LPS-stimulated macrophages, whereas IL-10 and cytokine signaling (SOCS)-3 suppressor were induced. Importantly, ATF4 siRNA is consistent with results of LPS preconditioning in macrophages.

Conclusions: This work is the first time to provide evidence for LPS preconditioning protects hepatocytes from IRI through inhibiting ATF4-CHOP pathway, which may be critical to reducing related apoptosis molecules and modulating innate inflammation.

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Related in: MedlinePlus

Attenuating liver IRI through low-dosage LPS preconditioning.Mice were subjected to 90 mim of partial liver ischemia, followed by 6 h and 24 h reperfusion. (A) and (B) Hepatocellular function evaluated by ALT (U/L) and LDH (U/L). Mean±SD, **P<0.001 versus sham group; ##P<0.001 versus IR group. (C) Histopathalogic analysis of livers harvested 6 hours after reperfusion: (a) Sham group: Normal hepatic architecture; (b) IR group: severe hepatic lobule distortion, sinusoidal congestion, apparent edema, vacuolization and massive necrosis; (c) LPS PC+IR group: mild vacuolization, punctate necrosis and edeman. (D) The severity of liver IRI by Suzuki’s histological grading.
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pone-0065568-g001: Attenuating liver IRI through low-dosage LPS preconditioning.Mice were subjected to 90 mim of partial liver ischemia, followed by 6 h and 24 h reperfusion. (A) and (B) Hepatocellular function evaluated by ALT (U/L) and LDH (U/L). Mean±SD, **P<0.001 versus sham group; ##P<0.001 versus IR group. (C) Histopathalogic analysis of livers harvested 6 hours after reperfusion: (a) Sham group: Normal hepatic architecture; (b) IR group: severe hepatic lobule distortion, sinusoidal congestion, apparent edema, vacuolization and massive necrosis; (c) LPS PC+IR group: mild vacuolization, punctate necrosis and edeman. (D) The severity of liver IRI by Suzuki’s histological grading.

Mentions: Mice livers were subjected to 90 min of warm ischemia 6 or 24 h after reperfusion. Serum ALT and LDH levels in each group were analyzed (Figs. 1A and B). ALT and LDH levels increased markedly in the I/R group compared with those in the sham group (P<0.001). Conversely, when mice were pretreated with LPS intraperitoneally, ALT and LDH levels were significantly decreased compared with those in the I/R control (P<0.001). Liver serum enzyme data were consistent with liver pathological analysis (Fig. 1C). The histological parameters observed in the sham, I/R, and LPS preconditioning were according to Suzuki et al [26], and each group was scored as 1.40±0.24, 7.40±0.51, and 3.6±0.40, respectively. These data indicated that LPS preconditioning significantly attenuates IR-induced liver injury.


Lipopolysaccharide preconditioning protects hepatocytes from ischemia/reperfusion injury (IRI) through inhibiting ATF4-CHOP pathway in mice.

Rao J, Qin J, Qian X, Lu L, Wang P, Wu Z, Zhai Y, Zhang F, Li G, Wang X - PLoS ONE (2013)

Attenuating liver IRI through low-dosage LPS preconditioning.Mice were subjected to 90 mim of partial liver ischemia, followed by 6 h and 24 h reperfusion. (A) and (B) Hepatocellular function evaluated by ALT (U/L) and LDH (U/L). Mean±SD, **P<0.001 versus sham group; ##P<0.001 versus IR group. (C) Histopathalogic analysis of livers harvested 6 hours after reperfusion: (a) Sham group: Normal hepatic architecture; (b) IR group: severe hepatic lobule distortion, sinusoidal congestion, apparent edema, vacuolization and massive necrosis; (c) LPS PC+IR group: mild vacuolization, punctate necrosis and edeman. (D) The severity of liver IRI by Suzuki’s histological grading.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3672158&req=5

pone-0065568-g001: Attenuating liver IRI through low-dosage LPS preconditioning.Mice were subjected to 90 mim of partial liver ischemia, followed by 6 h and 24 h reperfusion. (A) and (B) Hepatocellular function evaluated by ALT (U/L) and LDH (U/L). Mean±SD, **P<0.001 versus sham group; ##P<0.001 versus IR group. (C) Histopathalogic analysis of livers harvested 6 hours after reperfusion: (a) Sham group: Normal hepatic architecture; (b) IR group: severe hepatic lobule distortion, sinusoidal congestion, apparent edema, vacuolization and massive necrosis; (c) LPS PC+IR group: mild vacuolization, punctate necrosis and edeman. (D) The severity of liver IRI by Suzuki’s histological grading.
Mentions: Mice livers were subjected to 90 min of warm ischemia 6 or 24 h after reperfusion. Serum ALT and LDH levels in each group were analyzed (Figs. 1A and B). ALT and LDH levels increased markedly in the I/R group compared with those in the sham group (P<0.001). Conversely, when mice were pretreated with LPS intraperitoneally, ALT and LDH levels were significantly decreased compared with those in the I/R control (P<0.001). Liver serum enzyme data were consistent with liver pathological analysis (Fig. 1C). The histological parameters observed in the sham, I/R, and LPS preconditioning were according to Suzuki et al [26], and each group was scored as 1.40±0.24, 7.40±0.51, and 3.6±0.40, respectively. These data indicated that LPS preconditioning significantly attenuates IR-induced liver injury.

Bottom Line: As demonstrated by in vitro experiments, LPS preconditioning significantly reduced the upregulation of the ATF4-CHOP pathway and inhibited Caspase-12 and Caspase-3 activation after IRI.Importantly, ATF4 siRNA is consistent with results of LPS preconditioning in macrophages.This work is the first time to provide evidence for LPS preconditioning protects hepatocytes from IRI through inhibiting ATF4-CHOP pathway, which may be critical to reducing related apoptosis molecules and modulating innate inflammation.

View Article: PubMed Central - PubMed

Affiliation: Liver Transplantation Center, The First Affiliated Hospital of Nanjing Medical University, Key Laboratory of Living Donor Liver Transplantation of Ministry of Public Health, Nanjing, PR China.

ABSTRACT

Background: Low-dose lipopolysaccharide (LPS) preconditioning-induced liver protection has been demonstrated during ischemia-reperfusion injury (IRI) in several organs but has not been sufficiently elucidated underlying causal mechanism. This study investigated the role of low-dose LPS preconditioning on ATF4-CHOP pathway as well as the effects of the pathway on tissue injury and inflammation in a mouse model of liver partial-warm IRI.

Methods: LPS (100 µg/kg/d) was injected intraperitoneally two days before ischemia. Hepatic injury was evaluated based on serum alanine aminotransferase levels, histopathology, and caspase-3 activity. The ATF4-CHOP pathway and its related apoptotic molecules were investigated after reperfusion. The role of LPS preconditioning on apoptosis and ATF4-CHOP pathway was examined in vitro. Moreover, the effects of the ATF4-CHOP pathway on apoptosis, Caspase-12, and Caspase-3 were determined with ATF4 small interfering RNA (siRNA). Inflammatory cytokine expression was also checked after reperfusion. Inflammatory cytokines and related signaling pathways were analyzed in vitro in macrophages treated by LPS preconditioning or ATF4 siRNA.

Results: LPS preconditioning significantly attenuated liver injury after IRI. As demonstrated by in vitro experiments, LPS preconditioning significantly reduced the upregulation of the ATF4-CHOP pathway and inhibited Caspase-12 and Caspase-3 activation after IRI. Later experiments showed that ATF4 knockdown significantly suppressed CHOP, cleaved caspase-12 and caspase-3 expression, as well as inhibited hepatocellular apoptosis. In addition, in mice pretreated with LPS, TNF-α and IL-6 were inhibited after reperfusion, whereas IL-10 was upregulated. Similarly, low-dose LPS significantly inhibited TNF-α, IL-6, ATF4-CHOP pathway, NF-κB pathway, and ERK1/2 in high-dose LPS-stimulated macrophages, whereas IL-10 and cytokine signaling (SOCS)-3 suppressor were induced. Importantly, ATF4 siRNA is consistent with results of LPS preconditioning in macrophages.

Conclusions: This work is the first time to provide evidence for LPS preconditioning protects hepatocytes from IRI through inhibiting ATF4-CHOP pathway, which may be critical to reducing related apoptosis molecules and modulating innate inflammation.

Show MeSH
Related in: MedlinePlus