The differential induction of two immediate early genes, c-fos and c-jun, after systemic hypovolemic shock/resuscitation in the rat liver and kidney

Age-related differences in hepatic ischemia/reperfusion: gene activation, liver injury, and protective effect of melatonin

BACKGROUND

Ischemia/reperfusion (I/R) causes functional and structural damage to liver cells, this being more pronounced with increasing age of the tissue. Melatonin is a pineal indole that has been shown to play an important role as a free radical scavenger and anti-inflammatory molecule.

MATERIAL AND METHODS

The age-dependent responses to I/R were compared in 2-mo-old and 14-mo-old male Wistar rats. After 35 min of hepatic ischemia followed by 36 h of reperfusion, rats were sacrificed. Sham-operated control rats underwent the same protocol without real vascular occlusion. Animals were intraperitoneally injected with 10 mg/kg melatonin 24 h before the operation, at the time of surgery, and 12 and 24 h after it. The tissues were submitted to histopathologic evaluation. The levels of ALT and AST were analyzed in plasma. The expression of TNF-α, IL-1β, IL-10, MCP-1, IFN-γ, iNOS, eNOS, Bad, Bax, Bcl2, AIF, PCNA, and NFKB1 genes were detected by RT-PCR in hepatic tissue.

RESULTS

I/R was associated with significant increases in the expression of pro-inflammatory and pro-apoptotic genes in liver. Older rats submitted to I/R were found to respond with increased liver damage as compared with young rats, with serum ALT and AST levels significantly higher than in young animals. Mature rats also showed more evident increases in expression of pro-inflammatory cytokines (IL-1β, MCP-1, and IFN-γ) as well as a decrease in the mRNA expression of IL-10 as compared with young animals. Pro-apoptotic genes (Bax, Bad, and AIF) were significantly enhanced in liver after I/R, without differences between young and mature animals. However, the expression of Bcl2 gene did not show any change. Melatonin treatment was able to lower the expression of pro-inflammatory cytokines and pro-apoptotic genes and to improve liver function, as indicated by normalization of plasma AST and ALT levels and by reduction of necrosis and microsteatosis areas.

CONCLUSIONS

Melatonin treatment was able to reduce the I/R-stimulated pro-inflammatory and pro-apoptotic genes in the rat liver. Since older animals showed a more marked increase in inflammation and in liver injury, the treatment was more effective in those subjects.

Increased activation of the transcription factor c-Jun by MAP kinases in monocytes of multiple trauma patients is associated with adverse outcome and mass transfusion

BACKGROUND

Post-traumatic dysfunction of the immune system is a major source of morbidity and mortality in patients with multiple trauma. The underlying intracellular mechanisms are still incompletely understood. Previous mRNA expression studies in monocytes suggested an involvement of the MAP kinases p38 and JNK and of the transcription factor c-Jun. Therefore, it was the aim of this study to elucidate whether alterations in the protein expression p38 MAPK, JNK, and c-Jun could be linked to PRBC substitution and survival.

MATERIALS AND METHODS

Thirty-seven patients with blunt multiple injuries and an ISS > 16 points were enrolled in our study. Blood was drawn on admission and 6, 12, 24, 48, and 72 h after the traumatic event. Monocytes were isolated immediately after sample collection and nuclear protein was extracted and phosphoprotein concentrations were measured. The resulting data were statistically analyzed.

RESULTS

An increased activation of MAP kinases and c-Jun could be shown in patients who died from their injuries. Additionally, patients who received PRBC substitution ≥10 units exhibited increased expression of activated MAP kinases and c-Jun.

CONCLUSIONS

We present a serial, sequential investigation in human monocytes of major trauma patients evaluating the activation of p38 MAPK, JNK and c-Jun in the post-traumatic period. We show that death after trauma and massive PRBC substitution are associated with activation of this pathway. The p38 MAPK, JNK, and c-Jun have well established proinflammatory properties. Therefore, it appears likely that this pathway is involved in the systemic hyperinflammatory states seen after massive PRBC transfusion and multiple trauma.

Impact of resuscitation strategies on the acetylation status of cardiac histones in a swine model of hemorrhage

BACKGROUND

Chromatin remodeling through histone acetylation is a key control mechanism in gene transcription. We have shown previously that fluid resuscitation in rodents is coupled with highly structured post-translational modifications of cardiac histones. The current experiment was performed to validate this concept in a clinically relevant large animal model of hemorrhage and resuscitation, and to correlate the changes in histone acetylation with altered expression of immediate-early response genes.

STUDY DESIGN

Yorkshire swine (n=49, 7/group, weight=40-58kg) were subjected to combined uncontrolled and controlled hemorrhage (40% of estimated blood volume) and randomly assigned to the following resuscitation groups: (1) 0.9% saline (NS), (2) racemic lactated Ringer's (dl-LR), (3) l-isomer lactated Ringer's (l-LR), (4) Ketone Ringer's (KR), (5) 6% hetastarch in saline (Hespan). KR contained an equimolar substitution of lactate with beta-hydroxybutyrate. No hemorrhage (NH) and no resuscitation (NR) groups were included as controls. Cardiac protein was used in Western blotting to analyze total protein acetylation and histone acetylation specifically. Lysine residue-specific acetylation of histone subunits H3 and H4 was further evaluated. In addition, Chromatin Immunoprecipitation (ChIP) technique was used to separate the DNA bound to acetylated histones (H3 and H4 subunits), followed by measurement of genes that are altered by hemorrhage/resuscitation, including immediate-early response genes (c-fos and c-myc), and heat shock protein (HSP) 70.

RESULTS

The type of fluid used for resuscitation influenced the patterns of cardiac histone acetylation. Resuscitation with dl-LR and KR induced hyperacetylation on H3K9. KR resuscitation was also associated with increased acetylation on H3K14 and H4K5, and hypoacetylation on H3K18. The expression of genes was also fluid specific, with the largest number of changes following KR resuscitation (increased c-fos and c-myc, HSP 70 linked with H3; and increased c-myc linked with H4). Among the histone subunits studied, altered H3 acetylations were associated with the majority of changes in immediate-early gene expression.

CONCLUSIONS

Acetylation status of cardiac histones, affected by hemorrhage, is further modulated by resuscitation producing a fluid-specific code that is preserved in different species. Resuscitation with KR causes histone acetylation at the largest number of lysine sites (predominately H3 subunit), and has the most pronounced impact on the transcriptional regulation of selected (immediate-early response) genes.

Hemorrhagic shock induces differential gene expression and apoptosis in mouse liver

Comprehensive knowledge of the gene expression changes induced by hemorrhage in vital organs will greatly improve prognosis and therapy. Therefore, we used a mouse model of non-resuscitated hemorrhagic shock to study the pattern of stress-induced genes in liver at 1, 4, and 24 h following surgery. Hepatic injury was confirmed by assessment of liver injury markers and apoptotic cell death. We found that a variety of stress-regulated genes were differentially expressed, including seven genes that have not been reported previously as being regulated by hemorrhagic shock: ATF-2, alphaB-crystallin, GADD45, GADD45beta, Mdm2, p21Waf1, and TRPM-2. The changes in mRNA levels of the transcription factors AP-1, Egr-1, HSF-1, and NF-kappaB were transient but protein expression was noticeable at later time points. Our findings show that oxidative stress causes immediate upregulation of genes involved in a variety of cellular defense pathways. Complex interactions among them might determine the ultimate fate of the cell.

Differential regulation of cytokines and transcription factors in liver by curcumin following hemorrhage/resuscitation

Inflammatory cytokines interleukin 1 (IL-1), IL-2, IL-6, and tumor necrosis factor-alpha (TNF-alpha) have been recognized as important mediators of pathophysiological and immunological events associated with shock. These inflammatory events after hemorrhage and resuscitation are characterized by the activation of transcription regulators such as nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1). Curcumin, an anti-inflammatory remedy used in Indian medicine, is known to suppress NF-kappaB and AP-1 activation and also to reduce ischemia-reperfusion injuries in animal models. Therefore, the aim of this study was to determine whether administration of curcumin before hemorrhagic shock has any salutary effects on cytokines and the redox-sensitive transcription factors NF-kappaB and AP-1. mRNA levels of IL-1alpha, IL-1beta, IL-2, IL-6, IL-10, and TNF-alpha were determined by reverse transcriptase-polymerase chain reaction in rat livers collected at 2 and 24 h after hemorrhage/resuscitation. The effect of curcumin on the activation of NF-kappaB and AP-1 was determined by electrophoretic mobility shift assays. Significant increases in the levels of liver cytokines IL-1alpha, IL-1beta, IL-2, IL-6, and IL-10 were observed in the 2-h posthemorrhage/resuscitation group compared with sham animals. In contrast, oral administration of curcumin for 7 days followed by hemorrhage/resuscitation regimen resulted in significant restoration of these cytokines to depleted levels, and, in fact, IL-1beta levels were lower than sham levels. Also, the 24-h postresuscitation group showed similar patterns with some exceptions. NF-kappaB and AP-1 were differentially activated at 2 and 24 h posthemorrhage and were inhibited by curcumin pretreatment. Serum aspartate transaminase estimates indicate decreased liver injury in curcumin-pretreated hemorrhage animals. These results suggest that protection against hemorrhage/resuscitation injury by curcumin pretreatment may result from the inactivation of transcription factors involved and regulation of cytokines to beneficial levels.

Picroliv modulates antioxidant status and down-regulates AP1 transcription factor after hemorrhage and resuscitation

Resuscitation from hemorrhagic shock initiates profound changes in the liver that are likely to contribute to end organ damage and resultant dysfunction after shock. Extensive research in this area has indicated the potential of free radical scavenging strategy for better management of the pathophysiology following hemorrhage-resuscitation (H/R) injury. We studied the effect of a novel pharmacological agent, picroliv, on hepatocellular injury and redox status, as well as its possible mechanism of action in a H/R model in adult rats. Anesthetized rats were subjected to hemorrhagic shock by bleeding 30 mL/kg body weight. After 60 min of shock, rats were resuscitated with twice the shed blood volume of lactated Ringer's solution and were sacrificed 2 h after resuscitation. We observed that picroliv (12 mg/kg) pretreatment, given orally for 7 days, resulted in a significant decrease in serum aspartate transaminase and gamma-glutamyl transpeptidase levels. Picroliv also inhibited the lipid peroxidation and nitric oxide release that occurred after H/R and altered the activity of glutathione reductase in a favorable manner, thereby suggesting better antioxidant status. Picroliv significantly down-regulated the stress-sensitive transcription factor AP1 and decreased the level of c-fos mRNA as well as c-jun and c-fos proteins in liver tissue, indicating that its actions could be mediated through AP1 and associated signal transduction pathways. These findings suggest that picroliv has the potential to be developed as a protective agent against H/R injury.

The residual effects of hemorrhagic shock on pain reaction and c-fos expression in rats

To investigate the residual effects of hemorrhagic shock on pain reaction and c-fos expression, we performed formalin tests after hemorrhage and reinfusion in rats. Twenty adult male Sprague-Dawley rats were divided into Control (n = 10) and Postshock (n = 10) groups. The mean blood pressure of the Control group was 100-120 mm Hg, and that of the Postshock group was kept at 50-60 mm Hg for 30 min by draining blood. After 15 min of returning mean blood pressure to normal levels in the Postshock group, 10% formalin (3.7% formaldehyde solution, 100 microL) was injected into the left rear paw of both groups. Nociceptive behaviors were observed for 1 h after the formalin injection. The rats were killed at 2 h after the formalin injection, and the lumbar spinal cord was then stained for c-fos immunohistochemistry by using the avidin-biotin-peroxidase method. Animals in the Postshock group showed considerably less nociceptive behavior than those in the Control group. C-fos expression in the deep layer (IV-VI) of the spinal cord was significantly less in the Postshock group. In conclusion, decreases of nociceptive behaviors and c-fos expression were observed under normotensive conditions after hemorrhagic shock. The mechanisms governing these reactions remain unclear.

IMPLICATIONS

Formalin tests were performed after hemorrhage and reinfusion in rats. A stress-induced analgesia was observed under normotensive conditions after hemorrhagic shock. The mechanisms remain unclear.