New insights into Nod-like receptors (NLRs) in liver diseases.

Activation of inflammatory signaling pathways is of central importance in the pathogenesis of alcoholic liver disease (ALD) and nonalcoholic steatohepatitis (NASH). Nod-like receptors (NLRs) are intracellular innate immune sensors of microbes and danger signals that control multiple aspects of inflammatory responses. Recent studies demonstrated that NLRs are expressed and activated in innate immune cells as well as in parenchymal cells in the liver. For example, NLRP3 signaling is involved in liver ischemia-reperfusion (I/R) injury and silencing of NLRP3 can protect the liver from I/R injury. In this article, we review the evidence that highlights the critical importance of NLRs in the prevalent liver diseases. The significance of NLR-induced intracellular signaling pathways and cytokine production is also evaluated.

Effects of Contrast-Enhanced Ultrasonography in Monitoring Hepatic Microcirculation After Rat Liver Ischemia-Reperfusion Injury.

OBJECTIVES: Our objective was to evaluate the effects of contrast-enhanced ultrasonography in monitoring microcirculation after rat liver ischemia-reperfusion injury. MATERIALS AND METHODS: Male Wistar rats (n = 36) were divided into sham-operated and ischemia-reperfusion groups. Rats in the ischemia-reperfusion groups underwent normothermic liver ischemia for 15 minutes followed by 1, 6, or 24 hours of reperfusion. At different time points, contrast-enhanced ultrasonography was performed to determine peak intensity in monitoring hepatic microcirculation. In addition, serum levels of alanine aminotransferase, aspartate aminotransferase, tumor necrosis factor α, and interleukin 1ß levels were measured. Histopathologic changes were also observed. RESULTS: One hour after reperfusion, peak intensity values decreased, and serum levels of alanine aminotransferase, tumor necrosis factor α, and interleukin 1ß increased significantly in the ischemia-reperfusion group compared with the sham-operated group. Histology results showed mild injury. Six hours after reperfusion, peak intensity values decreased continuously, serum levels of alanine aminotransferase, tumor necrosis factor α, and interleukin 1ß decreased, and aspartate aminotransferase levels increased. Histology results showed severe injury compared with 1 hour after reperfusion. Twenty-four hours after reperfusion, peak intensity values increased, alanine aminotransferase and aspartate aminotransferase levels decreased, and histology results showed moderate injury compared with 6 hours after reperfusion. Peak intensity values were negatively correlated to alanine aminotransferase (P < .05; γ = -0.38) and aspartate aminotransferase (P < .01; γ = -0.78) levels. CONCLUSIONS: Microcirculation dysfunction after liver ischemia-reperfusion injury can be monitored by contrast-enhanced ultrasonography. The perfusion of contrast agents negatively correlates to the severity of injuries.

Calcitonin gene-related peptide enhances CREB phosphorylation and attenuates tau protein phosphorylation in rat brain during focal cerebral ischemia/reperfusion.

Calcitonin gene-related peptide (CGRP) is a potent vasodilator and immune cell modulator. Exogenous CGRP could increase the cerebral blood flow significantly and protect the ischemic neurons, but its mechanism is not entirely clear. The effect of CGRP on the expressions of CREB and tau in the ipsilateral parietal cortex were detected in focal cerebral ischemia/reperfusion model. The expression of CREB mRNA decreased in ischemia/reperfusion group (I/R group) compared with that of the sham operation group, and it got highest in CGRP group. CREB expression was lesser in I/R group than sham group, but it became more in CGRP group than I/R group. Phospho-CREB became more in I/R group, and it got most in CGRP group in the cortex. No significant difference was observed on Tau mRNA expression in all the groups. The level of tau hyperphosphorylation at Ser199/202 site and total tau in rat parietal cortex were significantly higher in I/R group than sham group. CGRP significantly inhibited tau hyperphosphorylation and the level of total tau also significantly reduced in CGRP group than that in I/R group. CGRP can upregulate the expression of CREB and phospho-CREB and attenuate the level of tau hyperphosphorylation in the ischemic neurons of the parietal cortex during focal cerebral ischemia/reperfusion. Phosphorylating CREB and inhibiting tau phosphorylation are probably involved in the mechanism of protective effect of CGRP to ischemic neurons.

Cyclic-AMP response element binding protein and tau are involved in the neuroprotective mechanisms of nerve growth factor during focal cerebral ischemia/reperfusion in rats.

Nerve growth factor (NGF) has protective and therapeutic effects after cerebral ischemic injury. However, its mechanism of action is not clear. We explored the protective mechanism of exogenous NGF on rat hippocampal neurons after focal cerebral ischemia/reperfusion. Changes were detected in the expression of cyclic-adenosine monophosphate (AMP) response element binding protein (CREB) messenger ribonucleic acid (mRNA), CREB protein, phosphorylated CREB, tau mRNA, total tau protein and the state of phosphorylation of tau protein at the serine 199/202 site. NGF treatment significantly increased the expression of CREB mRNA, CREB and phosphorylated CREB in the hippocampal CA1 region. NGF alleviated the level of phosphorylation of tau and the expression level of total tau. It is possible that the protective effect of NGF on the ischemic neuron was due to the activation of transcription and translation of CREB, the reduction in the level of phosphorylation of tau protein, and the activation of a series of signal pathways.

[Effect of adrenomedullin on neuron apoptosis and early growth response gene-1 after focal ischemia/ reperfusion in rats].

OBJECTIVE: To explore the influence of adrenomedullin (ADM) on apoptosis of neuron, volume of infarction and the expression of early growth response gene-1 (Egr-1) mRNA in the rat with focal ischemia/reperfusion (I/R) injury. METHODS: Fifty-four SD rats were randomly divided into sham operation group, ADM femoral vein group, internal carotid artery group and lateral cerebral ventricle group. The model was reproduced by ligating the middle cerebral artery (MCA) with a ligature for 2 hours followed by injection of ADM through femoral artery, internal carotid artery and lateral cerebral ventricle before reperfusion for 22 hours. The volume of infarction was estimated with tetrazolium chloride (TTC) staining, apoptosis of the neuron was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method, the positive expression of Egr-1 mRNA was detected by in-situ hybridization. RESULTS: The volume of infarction were smaller after the injection of ADM through different ways than that of I/R group. The result was better when the internal carotid artery and the lateral cerebral ventricle were used than that after injection by the way of the femoral vein (both P<0.05). There were few positive cells with TUNEL staining in the cerebral cortex and hippocampus CA1 zone in the sham operation group, and more apoptotic cells were seen in the group with focal brain I/R injury (both P<0.01). After the administration of ADM, especially through the internal carotid artery and the lateral cerebral ventricle, the number of the positive cells with TUNEL staining was decreased obviously compared with I/R group (both P<0.01). There was a little positive expression of Egr-1 mRNA in the cerebral cortex and hippocampus CA1 zone in sham operation group. The expression was enhanced in the group with focal brain I/R injury (both P<0.01). With the injection of ADM, the expression was much more enhanced, especially when internal carotid artery and the lateral cerebral ventricle were used for injection compared with those in I/R group (both P<0.01). CONCLUSION: The injection of ADM through different ways can reduce the neural injury, decrease the apoptosis of the neurons and the volume of the infarction, and increase the expression of Egr-1 mRNA. Therefore, it is efficacious in the treatment of cerebral ischemia.

Effect of adrenomedullin on neuron apoptosis, infarction volume and expression of Egr-1 mRNA after focal ischemia-reperfusion in rats.

Objective To observe the influence of adrenomedullin (ADM) on neuron apoptosis, infarction volume of brain, and the expression of early growth response 1 (Egr-1) mRNA in ischemia-reperfusion rats. Methods The arteria cerebri media was tied for 2 h to construct the ischemia model. Infarction volume was detected by triphenltetrazolium chloride (TTC) staining, neuronal apoptosis and necrosis was detected with terminal deoxynucleotidyl transferase nick labeling (TUNEL) method, and the Egr-1 mRNA expression was examined by in situ hybridization (ISH). Results Infarction volume after ischemia-reperfusion is (269 +/- 20) mm(3). Infarction volume after injection of ADM through different ways are femoral vein (239 +/- 17) mm(3) (decreased by 11.2%), arteria carotis (214 +/- 14) mm(3) (by 20.4%) and lateral cerebral ventricle (209 +/- 13) mm(3) (by 22.3%), respectively. The results indicate that injecting ADM through arteria carotis and lateral cerebral ventricle is much more effective than it through femoral vein (P < 0.05). The TUNEL-positive cells in cerebral cortex or hippocampus are few in the sham operation group, but much more in the ischemia-reperfusion group. After being supplied with ADM, especially through arteria carotis interna or lateral cerebral ventricle way, the TUNEL-positive cells decreased obviously. Expression of Egr-1 mRNA was low in the cerebral cortex of the sham operation group rats, enhanced in the ischemia and reperfusion group rats, and enhanced markedly after treatment with ADM, especially through arteria carotis interna or lateral cerebral ventricle way (P < 0.01). Conclusion Injection of ADM through different ways could alleviate neural dysfunction, decrease neuron apoptosis and brain infarction volume, and increase the expression of Egr-1 mRNA.

[The expression of protein kinase C and the regulatory effect of nerve growth factor in the lung and the visceral sensory afferent system of asthmatic guinea pigs].

OBJECTIVE: To explore the expression of protein kinase C (PKC) and the regulatory effect of nerve growth factor (NGF) in the lung and the visceral sensory afferent system (C(7)-T(5) spinal ganglia and the corresponding posterior horn of the spinal cord) of asthmatic guinea pigs. METHODS: Forty guinea pigs were divided to four groups, a saline control group (group A, n = 8), a provocation alone control group (group B, n = 8), an asthmatic group (group C, n = 12) and an anti-NGF group (group D, n = 12). The alterations of PKC immunoreactivity were investigated by means of immunohistochemistry in the C(7)-T(5) spinal ganglia and the corresponding posterior horn of the spinal cord of all groups. The expressions of NGF and PKC were investigated by Western blot in the lung, C(7)-T(5) spinal ganglia and the corresponding posterior horn of the spinal cord of all groups. The results were analyzed by the Luzex-F real time image analysis system and the gel imaging analysis system respectively. RESULTS: (1) Immunohistochemistry results: The absorbency (A) values of PKC were 0.102 +/- 0.009, 0.113 +/- 0.009, 0.106 +/- 0.005 and 0.116 +/- 0.007 in the C(7)-T(5) spinal ganglia and the corresponding posterior horn of the spinal cord of group A and group B respectively. There was no significant difference between group A and group B (P > 0.05). The A values of PKC were 0.215 +/- 0.014 and 0.176 +/- 0.010 respectively in the C(7)-T(5) spinal ganglia and the corresponding posterior horn of the spinal cord of group C, which were significantly different compared with group A (P < 0.01). The A values of PKC were 0.140 +/- 0.008 and 0.130 +/- 0.011 respectively in the C(7)-T(5) spinal ganglia and the corresponding posterior horn of the spinal cord of group D, which were significantly different compared with group C (P < 0.01). (2) Western blot results: Compared with group A (the relative A values were 0.51 +/- 0.02, 0.43 +/- 0.01 and 0.92 +/- 0.02 respectively) and group B, the expression of PKC (the relative A values were 1.51 +/- 0.01, 1.40 +/- 0.03 and 2.22 +/- 0.02 respectively) increased markedly in the lung, C(7)-T(5) spinal ganglia and the corresponding posterior horn of the spinal cord of group C; however, the expression of PKC of group D (the relative A values were 0.80 +/- 0.03, 0.83 +/- 0.01 and 1.12 +/- 0.02 respectively) decreased markedly in comparison with group C. CONCLUSION: The present results indicate that PKC might be involved in the pathogenesis of bronchial asthma, and NGF can upregulate the expression of PKC.