Role of ICAM-1 in chronic ethanol consumption-enhanced liver injury after gut ischemia-reperfusion in rats

Alcohol abuse and the injured host: dysregulation of counterregulatory mechanisms review

Traumatic injury ranks as the number one cause of death for the younger than 44 years age group and fifth leading cause of death overall (www.nationaltraumainstitute.org/home/trauma_statistics.html). Although improved resuscitation of trauma patients has dramatically reduced immediate mortality from hemorrhagic shock, long-term morbidity and mortality continue to be unacceptably high during the postresuscitation period particularly as a result of impaired host immune responses to subsequent challenges such as surgery or infection. Acute alcohol intoxication (AAI) is a significant risk factor for traumatic injury, with intoxicating blood alcohol levels present in more than 40% of injured patients. Severity of trauma, hemorrhagic shock, and injury is higher in intoxicated individuals than that of sober victims, resulting in higher mortality rates in this patient population. Necessary invasive procedures (surgery, anesthesia) and subsequent challenges (infection) that intoxicated trauma victims are frequently subjected to are additional stresses to an already compromised inflammatory and neuroendocrine milieu and further contribute to their morbidity and mortality. Thus, dissecting the dynamic imbalance produced by AAI during trauma is of critical relevance for a significant proportion of injured victims. This review outlines how AAI at the time of hemorrhagic shock not only prevents adequate responses to fluid resuscitation but also impairs the ability of the host to overcome a secondary infection. Moreover, it discusses the neuroendocrine mechanisms underlying alcohol-induced hemodynamic dysregulation and its relevance to host defense restoration of homeostasis after injury.

Artemisia asiatica extracts protect against ethanol-induced injury in gastric mucosa of rats

BACKGROUND AND AIM

Based on our previous studies that Artemisia asiatica extracts exert either antioxidative or cytoprotective actions against non-steroidal anti-inflammatory drugs or Helicobacter pylori-induced gastric mucosal injury, or imposes qualified ulcer healing in an acetic acid-induced gastric ulcer model, we investigated the protective effects of Artemisia asiatica extracts against ethanol-induced gastric mucosal injury.

METHODS

Sprague-Dawley rats received 4 g/kg body weight (BW) of absolute ethanol intragastrically, which produced visible hemorrhagic gastric lesions 60 min later.

RESULTS

In this animal setting, the pretreatment of Artemisia extracts (30 or 100 mg/kg BW), 1 h before ethanol administration, significantly attenuated the source of gastric injury, which was assessed with gross and microscopic analysis (P < 0.01). Protection from alcohol-induced damage with Artemisia pretreatment was associated with significantly decreased lipid peroxidation, protecting gastric mucosa from glutathione depletion, as well as the inhibition of the cytochrome 2E1 ethanol-metabolizing enzyme. It attenuated the expressions of ethanol-induced pro-inflammatory cytokines, including interleukin (IL)-1beta and interferon-gamma, a weak activation of IL-10, the inhibition of the alcohol-induced overexpression of intercellular adhesion molecule-1, and the considerable induction of heat shock protein-72 expression in gastric mucosal homogenates.

CONCLUSION

The data suggest that the ethanol extracts of Artemisia asiatica exerted significant protection from alcohol-induced gastric mucosal injury through bio-regulation, which is essential for cytoprotection and anti-inflammation.

Effect of notoginsenoside R1 on hepatic microcirculation disturbance induced by gut ischemia and reperfusion

AIM: To assess the effect of notoginsenoside R1 on hepatic microcirculatory disturbance induced by gut ischemia/reperfusion (I/R) in mice.

METHODS: The superior mesenteric artery (SMA) of C57/BL mice was ligated for 15 min to induce gut ischemia followed by 30-min reperfusion. In another set of experiments, R1 was continuously infused (10 mg/kg per hour) from 10 min before I/R until the end of the investigation to study the influence of R1 on hepatic microcirculatory disturbance induced by gut I/R. Hepatic microcirculation was observed by inverted microscopy, and the vascular diameter, red blood cell (RBC) velocity and sinusoid perfusion were estimated. Leukocyte rolling and adhesion were observed under a laser confocal microscope. Thirty and 60 min after reperfusion, lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and aspartate transaminase (AST) in peripheral blood were determined. The expression of adhesion molecules CD11b/CD18 in neutrophils and tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and monocyte chemotactic protein-1 (MCP-1) in plasma were evaluated by flow cytometry. E-selectin and intercellular adhesion molecule-1 (ICAM-1) in hepatic tissue were examined by immunofluorescence.

RESULTS: After gut I/R, the diameters of terminal portal venules and central veins, RBC velocity and the number of perfused sinusoids were decreased, while the leukocyte rolling and adhesion, the expression of E-selectin in hepatic vessels and CD18 in neutrophils, IL-6, MCP-1, LDH, ALT and AST were increased. R1 treatment attenuated these alterations except for IL-6 and MCP-1.

CONCLUSION: R1 prevents I/R-induced hepatic microcirculation disturbance and hepatocyte injury. The effect of R1 is related to its inhibition of leukocyte rolling and adhesion by inhibiting the expression of E-selectin in endothelium and CD18 in neutrophils.

Proteasome inhibitor lactacystin ablates liver injury induced by intestinal ischaemia-reperfusion

1. The aim of the present study was to investigate the role of proteasome in the pathogenesis of liver injury induced by intestinal ischaemia-reperfusion (I/R) and the effect of the proteasome inhibitor lactacystin on neutrophil infiltration, intracellular adhesion molecule (ICAM)-1 and nuclear factor (NF)-kappaB expression in the liver tissues of rats. 2. Thirty-two Wistar rats were randomly divided into four groups (n = 8 in each group) as follows: (i) a control, sham-operated group; (ii) an I/R group subjected to 1 h intestinal ischaemia and 4 h reperfusion; (iii) a group pretreated with 0.2 mg/kg lactacystin 1 h before intestinal I/R; and (iv) a group pretreated with 0.6 mg/kg lactacystin 1 h before intestinal I/R. Liver and intestine histology were observed. Serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH), as well as 20S proteasome activity in circulating white blood cells, were measured. Myeloperoxidase (MPO) activity in liver tissues and the immunohistochemical expression of liver NF-kappaB and ICAM-1 were assayed. In addition, a western blot of liver NF-kappaB was performed. 3. Compared with the sham-operated control group, liver and intestine injury was induced by intestinal I/R, characterized as histological damage including oedema, haemorrhage and infiltration by inflammatory cells, as well as a significant increase in serum AST (365 +/- 121 vs 546 +/- 297 IU/L, respectively; P < 0.05), ALT (65 +/- 23 vs 175 +/- 54 IU/L, respectively; P < 0.01) and LDH levels (733 +/- 383 vs 1434 +/- 890 IU/L, respectively; P < 0.05). Compared with the control group, MPO activity in the liver tissues increased significantly in the I/R group (2.05 +/- 0.69 vs 3.42 +/- 1.11 U/g, respectively; P < 0.05). Strong positive expression of liver ICAM-1 and NF-kappaB p65 was observed. 4. Compared with the intestinal I/R group, administration of 0.6 mg/kg lactacystin markedly reduced 20S proteasome activity in circulating white blood cells (15.47 +/- 4.00 vs 2.07 +/- 2.00 pmol 7-amino-4-methylcoumarin (AMC)/s per mg, respectively; P < 0.01) and ameliorated liver injury, which was demonstrated by decreased levels of serum AST (546 +/- 297 vs 367 +/- 86 IU/L, respectively; P < 0.05), ALT (175 +/- 54 vs 135 +/- 26 IU/L, respectively; P < 0.05) and LDH (1434 +/- 890 vs 742 +/- 218 IU/L, respectively; P < 0.05) and a reduced liver pathological score (2.13 +/- 0.64 vs 1.25 +/- 0.46, respectively; P < 0.01). Compared with the intestinal I/R group, MPO activity in liver tissues decreased significantly following lactacystin pretreatment (3.42 +/- 1.11 vs 2.58 +/- 0.61 U/g, respectively; P < 0.05) and the expression of liver NF-kappaB and ICAM-1 was markedly ameliorated. 5. The present study reveals that the proteasome inhibitor lactacystin ablates liver injury induced by intestinal I/R. One possible mechanism responsible for this effect is the inhibition of enhanced ICAM-1 and neutrophil infiltration by inhibition of NF-kappaB activity. The results suggest the feasibility of using proteasome inhibitor clinically in the treatment of intestinal I/R.

Herbal cardiotonic pills prevent gut ischemia/reperfusion-induced hepatic microvascular dysfunction in rats fed ethanol chronically

AIM: Cardiotonic Pill (CP), an oral herbal medicine that includes Danshen (Salviae Miltiorrhizae), Panax notoginseny and Dyroblanops aromatica gaertn, has been clinically used for vascular diseases such as occlusive vasculitis, coronary diseases, atherosclerosis, and cerebral infarction. The main component, Salviae Miltiorrhizae, has been reported to prevent cerebral and intestinal reperfusion injury. However, little is known about the effect of CP on hepatic microcirculation. Thus, this study aimed to determine whether CP could affect hepatic microvascular dysfunction elicited by gut ischemia/reperfusion (I/R) in rats fed ethanol chronically.

METHODS: Male Wistar rats were pair-fed with a liquid diet containing ethanol or isocaloric control diet for 6 wk. After laparotomy, one lobe of the liver was examined through an inverted intravital microscope. The rats were exposed to 30 min of gut ischemia followed by 60 min of reperfusion. Rhodamine-6G-labeled leukocytes in the sinusoids were observed 90 min after the onset of superior mesenteric artery occlusion. Plasma tumor necrosis factor (TNF)-α and endotoxin levels were measured 1 h after the onset of reperfusion. Plasma alanine aminotransferase (ALT) activities were measured 6 h after the onset of reperfusion. In another set of experiments, CP (0.8 g/kg, intragastrically) was administered 1 and 24 h before the onset of ischemia.

RESULTS: In control rats, gut I/R elicited increases in the number of stationary leukocytes, and plasma TNF-α and endotoxin levels and plasma ALT activities. These changes were mitigated by pretreatment with CP. In ethanol-fed rats, the gut I/R-induced increases in the number of stationary leukocytes, plasma endotoxin levels and ALT activities were enhanced. Pretreatment with CP attenuated the enhancement of gut I/R-induced responses by chronic ethanol consumption.

CONCLUSION: These results suggest that CP prevents the gut I/R-induced hepatic microvascular dysfunction and hepatocellular injury. A reduction of inflammatory responses such as TNF-α production via reduction of blood endotoxin levels appears to be involved in the mechanisms. Chronic ethanol consumption enhances gut I/R-induced hepatic microvascular and hepatocellular injury. CP also attenuates an enhancement of gut I/R-induced responses by chronic ethanol consumption via the reduction of blood endotoxin levels.

Effect of tetramethylpyrazine on P-selectin and hepatic/renal ischemia and reperfusion injury in rats

AIM: To investigate the effect of tetramethylpyrazine on hepatic/renal ischemia and reperfusion injury in rats.

METHODS: Hepatic/renal function, histopathological changes, and hepatic/renal P-selectin expression were studied with biochemical measurement and immunohistochemistry in hepatic/renal ischemia and reperfusion injury in rat models.

RESULTS: Hepatic/renal insufficiency and histopathological damage were much less in the tetramethylpyrazine-treated group than those in the saline-treated groups. Hepatic/renal P-selectin expression was down regulated in the tetramethylpyrazine-treated group.

CONCLUSION: P-selectin might mediate neutrophil infiltration and contribute to hepatic/renal ischemia and reperfusion injury. Tetramethylpyrazine might prevent hepatic/renal damage induced by ischemia and reperfusion injury through inhibition of P-selectin.