Prevention of ischemia/reperfusion-induced accumulation of matrix metalloproteinases in rat lung by preconditioning with nitric oxide

Regulation and involvement of matrix metalloproteinases in vascular diseases

Matrix metalloproteinases (MMPs) are a family of zinc dependent endopeptidases whose main function is to degrade and deposit structural proteins within the extracellular matrix (ECM). A dysregulation of MMPs is linked to vascular diseases. MMPs are classified into collagenases, gelatinases, membrane-type, metalloelastase, stromelysins, matrilysins, enamelysins, and unclassified subgroups. The production of MMPs is stimulated by factors such as oxidative stress, growth factors and inflammation which lead to its up- or down-regulation with subsequent ECM remodeling. Normally, excess activation of MMPs is controlled by their endogenous inhibitors, tissue inhibitors of metalloproteinases (TIMPs). An imbalance of MMPs and TIMPs has been implicated in hypertension, atherosclerotic plaque formation and instability, aortic aneurysms and varicose vein wall remodeling. Also, recent evidence suggests epigenetic regulation of some MMPs in angiogenesis and atherosclerosis. Over the years, pharmacological inhibitors of MMPs have been used to modify or prevent the development of the disease with some success. In this review, we discuss recent advances in MMP biology, and their involvement in the manifestation of vascular disease.

Association Study between an SNP in CD147 and Its Expression With Acute Coronary Syndrome in a Jiangsu Chinese Population

CD147 is an important molecule in the inflammation and proteolysis process. This molecule crucially contributes to the initial and progression of atherosclerotic lesions. A single nucleotide polymorphism in CD147 gene, the rs8259 T/A in the 3'-untranslated region, is responsible for its expression in various cells. This study assessed whether the genetic variation rs8259 is associated with acute coronary syndrome (ACS) and CD147. A total of 943 ACS subjects and 439 stable angina subjects, and 851 controls were genotyped for rs8259 polymorphism by polymerase chain reaction restriction fragment length polymorphism and DNA-sequencing method. Plasma soluble CD147 (sCD147) level was measured by enzyme-linked immunosorbent assay. CD147 mRNA and protein expression in peripheral blood mononuclear cells were tested by real-time quantitative polymerase chain reaction and western blot, respectively. We found that TT genotype and T-allele frequency of CD147 rs8259 in ACS patients were much lower than the other patient groups. Significant difference was not observed between stable angina and controls. CD147 T allele was negatively related to ACS. ACS patients exhibited the highest CD147 expression in peripheral blood mononuclear cells and plasma sCD147 level. The plasma sCD147 levels in the culprit vessel were higher than those in the radial artery. In ACS patients, AA gene carriers had the highest CD147 levels, whereas TT gene carriers had the lowest CD147 levels. Linear regression analysis showed that genotypes and disease conditions contributed 49% to the change of the plasma CD147 level. These results suggested that the single nucleotide polymorphism of CD147 gene rs8259 T/A was associated with ACS susceptibility. Allele T gene may decrease the relative risk of suffering from ACS through downregulation of CD147 expression.

Apolipoprotein D Internalization Is a Basigin-dependent Mechanism

Apolipoprotein D (apoD), a member of the lipocalin family, is a 29-kDa secreted glycoprotein that binds and transports small lipophilic molecules. Expressed in several tissues, apoD is up-regulated under different stress stimuli and in a variety of pathologies. Numerous studies have revealed that overexpression of apoD led to neuroprotection in various mouse models of acute stress and neurodegeneration. This multifunctional protein is internalized in several cells types, but the specific internalization mechanism remains unknown. In this study, we demonstrate that the internalization of apoD involves a specific cell surface receptor in 293T cells, identified as the transmembrane glycoprotein basigin (BSG, CD147); more particularly, its low glycosylated form. Our results show that internalized apoD colocalizes with BSG into vesicular compartments. Down-regulation of BSG disrupted the internalization of apoD in cells. In contrast, overexpression of basigin in SH-5YSY cells, which poorly express BSG, restored the uptake of apoD. Cyclophilin A, a known ligand of BSG, competitively reduced apoD internalization, confirming that BSG is a key player in the apoD internalization process. In summary, our results demonstrate that basigin is very likely the apoD receptor and provide additional clues on the mechanisms involved in apoD-mediated functions, including neuroprotection.

Function of CD147 in atherosclerosis and atherothrombosis

CD147, a member of the immunoglobulin super family, is a well-known potent inducer of extracellular matrix metalloproteinases. Studies show that CD147 is upregulated in inflammatory diseases. Atherosclerosis is a chronic inflammatory disease of the artery wall. Further understanding of the functions of CD147 in atherosclerosis and atherothrombosis may provide a new strategy for preventing and treating cardiovascular disease. In this review, we discuss how CD147 contributes to atherosclerosis and atherothrombosis.

Expression and clinical implications of HAb18G/CD147 in hepatocellular carcinoma

AIM

HAb18G/CD147 is an important factor in invasion and metastasis of hepatocellular carcinoma (HCC). However, the clinical implications of HAb18G/CD147 expression in HCC are still unclear. In this study, we clarify the clinical significance of HAb18G/CD147. We characterize the association between HAb18G/CD147 expression and presentation of fibrosis or chronic hepatitis B, as well as its effect on HCC development.

METHODS

The expression of HAb18G/CD147 in human hepatocarcinoma cell lines was analyzed by reverse transcription polymerase chain reaction and western blotting. Tumor tissues were obtained from HCC patients who underwent surgical resection between 2002 and 2006. All patients who had received previous therapy were excluded. HCC tissues were analyzed by immunohistochemistry using anti-HAb18G/CD147.

RESULTS

HAb18G/CD147 was widely expressed in Hep-G2, SMCC-7721 and BEL7402 cell lines, but not expressed in L-02, a human normal hepatic cell line. HAb18G/CD147 was mainly localized to the membrane of tumor cells in 74.0% (37/50) HCC patients. We found that higher HAb18G/CD147 expression and poor tumor differentiation were correlated with patient survival (P = 0.026 and P = 0.014, respectively). Furthermore, the distribution of HAb18G/CD147 was similar to that of hepatitis B virus (HBV) infection, but negatively related to hepatic cirrhosis.

CONCLUSION

HAb18G/CD147 has shown its potentials in HCC development and patient survival. Moreover, it may also cooperate with chronic HBV infection and cirrhosis during HCC development. Its functions in the two factors may be different. Therefore, HAb18G/CD147 may be a marker for poor prognosis in HCC patients and could be a useful therapeutic target for interfering with or reversing HCC progression.

Short-term inhalation of nitric oxide inhibits activations of toll-like receptor 2 and 4 in the lung after ischemia-reperfusion injury in mice

In order to investigate the effects of different terms of inhaled nitric oxide (NO) preconditioning with low concentration on the activations of Toll-like receptor 2 and 4 (TLR2/4) in the lung ischemia-reperfusion (IR) injury in mice, we divided the male C57BL mice into five groups: sham (S) group, IR group, NO 1-min preconditioning group (15 ppm NO inhalation for 1 min before ischemia, NO 1-min), NO 10-min preconditioning group (15 ppm NO inhalation for 10 min before ischemia, NO 10-min), NO 60-min preconditioning group (15 ppm NO inhalation for 60 min before ischemia, NO 60-min). The changes of partial pressure of oxygen in artery (PaO2), left lung wet-to-dry weight ratio (W/D), and myeloperoxidase (MPO) in the injured lung were measured in every group at 6th h of reperfusion after 60 min of left lung ischemia. The changes of TLR2/4 activations and plasma TNF-α were measured in this procedure in additional mice. As compared with IR group, PaO2 increased, MPO and W/D decreased evidently after reperfusion in NO 10-min group. The changes in NO 60-min group were similar to those in NO 10-min group. There was no difference between NO 1-min and IR group. In NO inhalation group, the expressions levels of TLR2/4 mRNA and proteins were diminished, TNF-α concentrations were decreased, and the lung injuries were ameliorated effectively. We concluded that short term inhalation of NO protected lung IR injury. But the protective effect of NO was not increased with extension of inhaled NO. Inhaled NO could inhibit the activations of TLR2/4 in the lung after IR injury. TLR signal pathway might contribute to the effect of protection with NO in this model.

When is injury potentially reversible in a lung ischemia-reperfusion model?

OBJECTIVE

To verify the impact of ischemic time on lung cell viability in an experimental model of lung ischemia-reperfusion (IR) injury and its repercussion on lung performance after reperfusion.

METHODS

Twenty-four animals were subjected to selective clamping of the left pulmonary artery and divided into four groups (n = 6) according to ischemic time: 15 (IR15), 30 (IR30), 45 (IR45), and 60 min (IR60). All animals were observed for 120 min after reperfusion. The hemodynamics, arterial blood gases measurements, and histologic changes were analyzed. Immunofluorescence assays for caspase 3 and annexin V were performed. Lipid peroxidation was assessed by thiobarbituric acid-reactive substances, and caspase 3 activity was assessed by colorimetric extract.

RESULTS

The partial pressure of arterial oxygen significantly decreased at the end of the observation period in the IR30, IR45, and IR60 groups (P < 0.05). The final mean arterial pressure significantly decreased in the IR60 group (P < 0.05). We observed a significant increase in caspase 3 activity and caspase 3-positive cells by immunofluorescence in the IR45 group compared with the other groups (P < 0.05). Additionally, there was an increase in necrotic cells assessed by annexin V in the IR60 group. The histologic score did not show differences among the different groups.

CONCLUSIONS

The degree of cell damage had a negative impact on lung performance. Sixty minutes of lung ischemia and posterior reperfusion resulted in an increased number of necrotic cells, suggesting that these cells may not be able to reverse the effects of the IR injury because of the lack of viable cells.

Protease activity increases in plasma, peritoneal fluid, and vital organs after hemorrhagic shock in rats

Hemorrhagic shock (HS) is associated with high mortality. A severe decrease in blood pressure causes the intestine, a major site of digestive enzymes, to become permeable - possibly releasing those enzymes into the circulation and peritoneal space, where they may in turn activate other enzymes, e.g. matrix metalloproteinases (MMPs). If uncontrolled, these enzymes may result in pathophysiologic cleavage of receptors or plasma proteins. Our first objective was to determine, in compartments outside of the intestine (plasma, peritoneal fluid, brain, heart, liver, and lung) protease activities and select protease concentrations after hemorrhagic shock (2 hours ischemia, 2 hours reperfusion). Our second objective was to determine whether inhibition of proteases in the intestinal lumen with a serine protease inhibitor (ANGD), a process that improves survival after shock in rats, reduces the protease activities distant from the intestine. To determine the protease activity, plasma and peritoneal fluid were incubated with small peptide substrates for trypsin-, chymotrypsin-, and elastase-like activities or with casein, a substrate cleaved by multiple proteases. Gelatinase activities were determined by gelatin gel zymography and a specific MMP-9 substrate. Immunoblotting was used to confirm elevated pancreatic trypsin in plasma, peritoneal fluid, and lung and MMP-9 concentrations in all samples after hemorrhagic shock. Caseinolytic, trypsin-, chymotrypsin-, elastase-like, and MMP-9 activities were all significantly (p<0.05) upregulated after hemorrhagic shock regardless of enteral pretreatment with ANGD. Pancreatic trypsin was detected by immunoblot in the plasma, peritoneal space, and lungs after hemorrhagic shock. MMP-9 concentrations and activities were significantly upregulated after hemorrhagic shock in plasma, peritoneal fluid, heart, liver, and lung. These results indicate that protease activities, including that of trypsin, increase in sites distant from the intestine after hemorrhagic shock. Proteases, including pancreatic proteases, may be shock mediators and potential targets for therapy in shock.

Cyclophilin-CD147 interactions: a new target for anti-inflammatory therapeutics

CD147 is a widely expressed plasma membrane protein that has been implicated in a variety of physiological and pathological activities. It is best known for its ability to function as extracellular matrix metalloproteinase inducer (hence the other name for this protein, EMMPRIN), but has also been shown to regulate lymphocyte responsiveness, monocarboxylate transporter expression and spermatogenesis. These functions reflect multiple interacting partners of CD147. Among these CD147-interacting proteins cyclophilins represent a particularly interesting class, both in terms of structural considerations and potential medical implications. CD147 has been shown to function as a signalling receptor for extracellular cyclophilins A and B and to mediate chemotactic activity of cyclophilins towards a variety of immune cells. Recent studies using in vitro and in vivo models have demonstrated a role for cyclophilin-CD147 interactions in the regulation of inflammatory responses in a number of diseases, including acute lung inflammation, rheumatoid arthritis and cardiovascular disease. Agents targeting either CD147 or cyclophilin activity showed significant anti-inflammatory effects in experimental models, suggesting CD147-cyclophilin interactions may be a good target for new anti-inflammatory therapeutics. Here, we review the recent literature on different aspects of cyclophilin-CD147 interactions and their role in inflammatory diseases.