MMP-2 and MMP-9 are prominent matrix metalloproteinases during atherosclerosis development in the Ldlr(-/-)Apob(100/100) mouse

Matrix-degrading proteases capable of degrading components of the extracellular matrix may play an important role in development and progression of atherosclerotic lesions. In the present study, we used the Ldlr(-/-)Apob(100/100) mouse model, which has a plasma lipoprotein profile similar to that of humans with atherosclerosis, to study the expression of matrix metalloproteinases (MMPs) during early stages of atherosclerosis development. We analyzed the expression of 11 proteases and three protease inhibitors in 5- to 40-week-old Ldlr(-/-)Apob(100/100) mice. Expression and activity of MMP-2 and MMP-9 was increased in advanced atherosclerotic lesions followed by macrophage infiltration as shown by real-time PCR, gel-based and in situ zymography and immunohistochemistry. Expression of other investigated MMPs did not increase during disease progression. However, the mRNA expression of MMP-8 and MMP-13 was down-regulated, which could explain the relatively high amount of collagen observed in the vessels in this model. In conclusion, low proteolytic expression at early stages of atherogenesis and a limited repertoire of proteolytic enzymes were associated with the progression of atherosclerosis in Ldlr(-/-)Apob(100/100) mice. The study suggests that MMP-2 and MMP-9 are the main proteases involved in atherogenesis in this mouse model.

Impaired splicing of fibronectin is associated with thoracic aortic aneurysm formation in patients with bicuspid aortic valve

OBJECTIVE

Thoracic aortic aneurysm is a common complication in patients with bicuspid aortic valve (BAV). Alternatively spliced extra domain A (EDA) of fibronectin (FN) has an essential role in tissue repair. Here we analyze the expression of FN spliceforms in dilated and nondilated ascending aorta of tricuspid aortic valve (TAV) and BAV patients.

METHODS AND RESULTS

The mRNA expression was analyzed in the ascending aorta by Affymetrix Exon arrays in patients with TAV (n=40) and BAV (n=69). EDA and extra domain B (EDB) expression was increased in dilated aorta from TAV patients compared with nondilated aorta (P<0.001 and P<0.05, respectively). In contrast, EDA expression was not increased in dilated aorta from BAV patients (P=0.25), whereas EDB expression was upregulated (P<0.01). The expression of EDA correlated with maximum aortic diameter in TAV (ρ=0.58) but not in BAV (ρ=0.15) patients. Protein analyses of EDA-FN showed concordant results. Transforming growth factor-β treatment influenced the splicing of FN and enhanced the formation of EDA-containing FN in cultured medial cells from TAV patients but not in cells derived from BAV patients. Gene set enrichment analysis together with multivariate and univariate data analyses of mRNA expression suggested that differences in the transforming growth factor-β signaling pathway may explain the impaired EDA inclusion in BAV patients.

CONCLUSIONS

Decreased EDA expression may contribute to increased aneurysm susceptibility of BAV patients.

Pigment epithelium-derived factor expression in colorectal cancer patients

Pigment epithelium-derived factor (PEDF) is a potent inhibitor of angiogenesis and has been proposed to be a tumor suppressor in a variety of tumors. Limited reports exist of PEDF in colorectal cancer (CRC). We noted a 55% lower plasma level (p < .001) of PEDF in the CRC patient group (1.6 μg/mL) than in of a healthy control group (3.6 μg/mL). A single nucleotide polymorphism (rs1136287, T>C) was screened. In the control group, the CC genotype showed 30% lower PEDF plasma levels compared with the TT genotype (p < .01), whereas the CRC patients failed to show any association regarding these genotypes.

Gene expression and immunohistochemistry in adipose tissue of HIV type 1-infected patients with nucleoside analogue reverse-transcriptase inhibitor-associated lipoatrophy

BACKGROUND

Long-term use of both zidovudine (AZT) and stavudine (d4T) is associated with lipoatrophy, but it occurs possibly through different mechanisms.

METHODS

Surgical biopsy specimens of subcutaneous adipose tissue were obtained from 18 human immunodeficiency virus type 1 (HIV-1)-infected lipoatrophic patients (the LA+ group) who were treated with either zidovudine (the AZT+LA+ group; n = 10) or stavudine (the d4T+LA+ group; n = 8) and from 10 nonlipoatrophic HIV-1-infected patients (the LA- group) who received antiretroviral therapy. Mitochondrial DNA (mtDNA) copy numbers, gene expression, and immunohistochemistry data were analyzed.

RESULTS

mtDNA copy numbers were significantly reduced in the LA+ group, compared with the LA- group, and in the d4T+LA+ group, compared with the AZT+LA+ group. The ratio of mtDNA-encoded cytochrome COX3 to nuclear DNA-encoded COX4 expression was significantly lower in the LA+ group than in the LA- group. Compared with the LA- group, the LA+ group had significantly lower expression of genes involved in adipogenesis (SREBP1c and CEBPB), lipid (fatty acid synthase), and glucose (GLUT4) metabolism. Expression of genes involved in mitochondrial biogenesis (PGC1B), apoptosis (FAS), inflammation (IL1B), oxidative stress (PCNA and SOD1), and lamin B was significantly higher in the LA+ group than in the LA- group. The d4T+LA+ group had significantly lower expression of genes involved in mitochondrial biogenesis (POLG1), energy metabolism (the COX3/COX4 ratio), adipogenesis (SREBP1c and CEBPA), perilipin, and hexokinase than did the AZT+LA+ group. There were 7-fold more macrophages in adipose tissue specimens obtained from patients in the LA+ group, compared with the LA- group.

CONCLUSIONS

Lipoatrophy is characterized by mtDNA depletion, inflammation, and signs of apoptosis. Changes were more profound in the d4T+LA+ group than in the AZT+LA+ group.

Endurance exercise activates matrix metalloproteinases in human skeletal muscle

In the present study, the effect of exercise training on the expression and activity of matrix metalloproteinases (MMPs) in the human skeletal muscle was investigated. Ten subjects exercised one leg for 45 min with restricted blood flow and then exercised the other leg at the same absolute workload with unrestricted blood flow. The exercises were conducted four times per week for 5 wk. Biopsies were taken from the vastus lateralis muscles of both legs at rest before the training period, after 10 days and 5 wk of training, and 2 h after the first exercise bout for analysis of MMP and tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA, enzyme activity, and protein expression. Levels of MMP-2, MMP-14, and TIMP-1 mRNA in muscle tissue increased after 10 days of training regardless of blood flow condition. MMP-2 mRNA level in laser-dissected myofibers and MMP-2 activity in whole muscle increased with training. The level of MMP-9 mRNA and activity increased after the first bout of exercise. Although MMP-9 mRNA levels appeared to be very low, the activity of MMP-9 after a single bout of exercise was similar to that of MMP-2 after 10 days of exercise. MMP-2 and MMP-9 protein was both present throughout the extracellular matrix of the muscle, both around fibers and capillaries, but MMP-2 was also present within the skeletal muscle fibers. These results show that MMPs are activated in skeletal muscle in nonpathological conditions such as voluntary exercise. The expression and time pattern indicate differences between the MMPs in regards of production sites as well as in the regulating mechanism.

T-cell activation leads to reduced collagen maturation in atherosclerotic plaques of Apoe(-/-) mice

Rupture of the collagenous, fibrous cap of an atherosclerotic plaque commonly causes thrombosis. Activated immune cells can secrete mediators that jeopardize the integrity of the fibrous cap. This study aimed to determine the relationship between T-cell-mediated inflammation and collagen turnover in a mouse model of experimental atherosclerosis. Both Apoe(-/-) x CD4dnTbetaRII mice with defective transforming growth factor-beta receptors in T cells (and hence released from tonic suppression of T-cell activation) and lesion size-matched Apoe(-/-) mice were used. Picrosirius red staining showed a lower content of thick mature collagen fibers in lesions of Apoe(-/-) x CD4dnTbetaRII mice, although both groups had similar levels of procollagen type I or III mRNA and total collagen content in lesions. Analysis of both gene expression and protein content showed a significant decrease of lysyl oxidase, the extracellular enzyme needed for collagen cross-linking, in aortas of Apoe(-/-)--CD4dnTbetaRII mice. T-cell-driven inflammation provoked a selective and limited increase in the expression of proteinases that catabolize the extracellular matrix. Atheromata of Apoe(-/-)--CD4dnTbetaRII mice had increased levels of matrix metalloproteinase-13 and cathepsin S mRNAs and of the active form of cathepsin S protein but no increase was detected in collagen fragmentation. Our results suggest that exaggerated T-cell-driven inflammation limits collagen maturation in the atherosclerotic plaque while having little effect on collagen degradation.

Decreased expression of the chemokine CCL21 in human colorectal adenocarcinomas

Recent studies have revealed participation of chemokines in cancer by regulating leukocyte movement to modify local immunoresponse. The chemokine CCL21 has been identified to play a pivotal role in homing and localization of immune cells to lymphoid tissue and into organ of non-lymphoid origin. In the cancer biology CCL21 seems to have multifaceted roles. CCL21 attracts CCR7 bearing cells especially T and dendritic cells but also various cancer cells. Besides the antitumour role as leukocyte recruiting, CCL21 has been shown to facilitate dendritic cell functions and to exert an angiostatic effect. To gain insight into the possible influence of CCL21 on colorectal cancer (CRC) we determined whether the CCL21 is altered in CRC tissue. Collectively, by using ELISA we noted a significant lower CCL21 level in cancer tissue compared with paired normal tissue. Patients with a tumour localized in the rectum revealed significantly lower level of CCL21 than patients with a tumour localized in the colon both compared with paired normal tissue. We used immunohistochemistry and found heterogeneous immunoreactivity predominantly within areas of stromal cells mainly in macrophages. We also used a TaqMan system to investigate two single-nucleotide polymorphisms rs 11574915 and rs 2812377 with supposed effect on CRC. No significant difference was observed between CRC and control subjects regarding genotype and allelic distributions or associations to clinical characteristics or CCL21 tissue levels. Our study implied that lower level of CCL21 in CRC tissue supports the idea that cancer is related to immunodeficiency probably depending on regulatory factors produced by tumour cells and that the different levels of CCL21 in rectum and colon may reflect divergent mechanisms in colorectal carcinogenesis. Further studies are needed to clarify whether the CCL21 level has an impact on CRC progression and survival rate.

Quantification of the chemokines CCL17 and CCL22 in human colorectal adenocarcinomas

Chemokines are believed to play a crucial role in local immunoresponse by regulating leukocyte movement in various tissues, including the intestinal mucosa. It has been suggested that they are key players in cancer biology, and several studies have identified leukocyte infiltration as a hallmark of most cancers. The chemokines CCL17 and CCL22 attract CCR4-bearing cells, which are especially polarised to Th2-type cells and regulatory T cells (Treg). Recent studies have revealed the participation of the CCL17 and CCL22 proteins in diseases such as atopic dermatitis and lymphoma. The purpose of this study was to assess the role of CCL17 and CCL22 protein expression in colorectal cancer (CRC) and to ascertain whether an association exists between promoter -431C>T CCL17 and -961G>A CCL22 gene polymorphisms in CRC versus non-CRC subjects. Using the ELISA assay, we noted a significantly higher expression of CCL22 in tumour tissue with a 2.3-fold up-regulation (tumour vs. paired normal tissue, n=78) but no significant difference in CCL17 protein expression. Immunohistochemistry revealed protein expression of CCL22 and CCL17 in the epithelial compartment of cancer tissue, in epithelial cells at the resection border that reflects normal tissue, and in some stromal cells such as lymphocytes, macrophages, and fibroblasts. Using a TaqMan system we screened for -431C>T CCL17 and -961G>A CCL22 gene variants in 245 CRC patients and 256 controls, but could not find any significant difference in genotype distribution or in allelic frequencies between the two groups. The genotype and allelic distributions of CRC patients were not related to tissue levels of CCL17 and CCL22 protein, and none of the variables were associated with plasma levels or clinical characteristics. To ascertain whether the tissue expression of CCL17 and CCL22 exerts an influence on the pathogenesis of CRC, a forthcoming study on the 5-year survival rate of CRC patients will be conducted.

ADAMTS-4 and -8 are inflammatory regulated enzymes expressed in macrophage-rich areas of human atherosclerotic plaques

OBJECTIVES

Remodeling of extracellular matrix (ECM) plays an important role in inflammatory disorders such as atherosclerosis. ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) is a recently described family of proteinases that is able to degrade the ECM proteins aggrecan and versican expressed in blood vessels. The purpose of the present study was to analyze the expression and regulation of several ADAMTSs before and after macrophage differentiation and after stimulation with IFN-gamma, IL-1beta and TNF-alpha. ADAMTS expression was also examined during atherosclerosis development in mice and in human atherosclerotic plaques.

METHODS AND RESULTS

Real time RTPCR showed that, of the nine different ADAMTS members examined, only ADAMTS-4 and -8 were induced during monocyte to macrophage differentiation, which was also seen at protein level. Macrophage expression of ADAMTS-4, -7, -8 and -9 mRNA were enhanced upon stimulation with IFN-gamma or TNF-alpha. Furthermore, immunohistochemical analyses revealed that ADAMTS-4 and -8 were expressed in macrophage rich areas of human atherosclerotic carotid plaques and coronary unstable plaques. In addition, ADAMTS-4 expression was upregulated during the development of atherosclerosis in LDLR(-/-)ApoB(100/100) mice. Whereas ADAMTS-4 expression was low in non-atherosclerotic aortas, it was significantly higher in aortas from 30-40-week old atherosclerotic animals.

CONCLUSION

The present study suggests that ADAMTS-4 and -8 are inflammatory regulated enzymes expressed in macrophage-rich areas of atherosclerotic plaques. This is the first study associating ADAMTS-4 and -8 expression with atherosclerosis. However, further experiments are required to understand the physiological and pathological functions of ADAMTS in the vascular wall, and tools to measure ADAMTS activity need to be developed.

Polymorphisms of Fractalkine receptor CX3CR1 and plasma levels of its ligand CX3CL1 in colorectal cancer patients

BACKGROUND AND AIMS

The chemokine Fractalkine/CX3CL1, which is expressed by epithelial cells within normal colorectal mucosa and in colorectal cancer (CRC), is thought to have a crucial role in colorectal mucosal immunity by recruiting leucocytes via the receptor CX3CR1. The purpose of this study was to investigate two single-nucleotide polymorphisms of the Fractalkine receptor/CX3CR1 gene, V249I and T280M, in CRC to find out whether they occur more often in patients with CRC than in non-CRC individuals. In the search for tumour markers, we also intended to determine whether plasma levels of Fractalkine were correlated with parameters such as Dukes' stage, tumour localisation, gender and age in CRC patients.

MATERIALS AND METHODS

Genomic deoxyribonucleic acid from 223 CRC patients and 229 controls was amplified by polymerase chain reaction, and the polymorphisms were detected by the restriction fragment length polymorphism analysis. Fractalkine/CX3CL1 was analysed in plasma from 62 CRC patients and 78 controls using enzyme-linked immunosorbent assay.

RESULTS

The variant V249I was significantly different in genotype and allelic distribution between CRC patients and control subjects, P = 0.028 and P = 0.048, respectively. We also found that individuals with the I249 allele in homozygote state were less frequent in the CRC group (3.1%) compared with controls (9.2%; P = 0.008). No significant difference was observed regarding Fractalkine/CX3CL1 levels in plasma between patients and the control group.

CONCLUSION

Our results suggest that the lack of the allele I249 of the CX3CR1 gene may play a partial or minor role in CRC and that plasma Fractalkine/CX3CL1 does not seem to be a useful tumour marker that reflects the disease outcome of CRC.

Adipose tissue inflammation and increased ceramide content characterize subjects with high liver fat content independent of obesity

OBJECTIVE

We sought to determine whether adipose tissue is inflamed in individuals with increased liver fat (LFAT) independently of obesity.

RESEARCH DESIGN AND METHODS

A total of 20 nondiabetic, healthy, obese women were divided into normal and high LFAT groups based on their median LFAT level (2.3 +/- 0.3 vs. 14.4 +/- 2.9%). Surgical subcutaneous adipose tissue biopsies were studied using quantitative PCR, immunohistochemistry, and a lipidomics approach to search for putative mediators of insulin resistance and inflammation. The groups were matched for age and BMI. The high LFAT group had increased insulin (P = 0.0025) and lower HDL cholesterol (P = 0.02) concentrations.

RESULTS

Expression levels of the macrophage marker CD68, the chemokines monocyte chemoattractant protein-1 and macrophage inflammatory protein-1alpha, and plasminogen activator inhibitor-1 were significantly increased, and those of peroxisome proliferator-activated receptor-gamma and adiponectin decreased in the high LFAT group. CD68 expression correlated with the number of macrophages and crown-like structures (multiple macrophages fused around dead adipocytes). Concentrations of 154 lipid species in adipose tissue revealed several differences between the groups, with the most striking being increased concentrations of triacylglycerols, particularly long chain, and ceramides, specifically Cer(d18:1/24:1) (P = 0.01), in the high LFAT group. Expression of sphingomyelinases SMPD1 and SMPD3 were also significantly increased in the high compared with normal LFAT group.

CONCLUSIONS

Adipose tissue is infiltrated with macrophages, and its content of long-chain triacylglycerols and ceramides is increased in subjects with increased LFAT compared with equally obese subjects with normal LFAT content. Ceramides or their metabolites could contribute to adverse effects of long-chain fatty acids on insulin resistance and inflammation.

Analysis of single nucleotide polymorphism in the promoter and protein expression of the chemokine eotaxin-1 in colorectal cancer patients

BACKGROUND

Previous studies suggest that chemokines (chemotactic cytokines) promote and regulate neoplastic progression including metastasis and angiogenesis. The chemokine eotaxin-1 is a powerful eosinophil attractant but also exerts chemotaxis of other leukocytes. Eotaxin-1 has been implicated in gastrointestinal disorders and may play an important role in colorectal mucosal immunity.

PATIENTS AND METHODS

The objective of this study was to assess the role of eotaxin-1 in colorectal cancer (CRC). Levels of eotaxin-1 protein in CRC tissues (n = 86) and paired normal mucosa were compared after determination by ELISA. Plasma eotaxin-1 levels from CRC patients (n = 67) were also compared with controls (n = 103) using the same method. Moreover, a TaqMan system was used to evaluate the -384A>G eotaxin-1 gene variant in CRC patients (n = 241) and in a control group (n = 253).

RESULTS

Eotaxin-1 protein levels in colorectal tumours were significantly (P < 0.0001) higher than in normal tissue. Immunohistochemistry revealed eotaxin-1 expression in stromal cells such as fibroblasts and leukocytes of the CRC tissue. The plasma eotaxin-1 level in CRC patients was lower compared with controls (P < 0.0001). Patients with tumours classified as Dukes' stage B and C had lower levels than patients with tumours in Dukes' stage A. We found no difference in genotype distribution but noted a difference regarding allele distribution (P = 0.036) and a dominance of allele G in rectal cancer patients.

CONCLUSION

The up-regulated eotaxin-1 protein expression in cancer tissue may reflect an eotaxin-1 mediated angiogenesis and/or a recruitment of leukocytes with potential antitumourigenic role. We noticed a dominance of the G allele in rectal cancer patients compared with colon cancer patients that was independent of eotaxin-1 expression.

Expression and gene polymorphisms of the chemokine CXCL5 in colorectal cancer patients

Several studies indicate that chemokines play important roles in colorectal mucosal immunity by recruiting leukocytes into and out of the lamina propria adjacent to the epithelium. The chemokine CXCL5 which is expressed by epithelial cells within colorectal mucosa is a chemoattractant for neutrophils and has been implicated in Crohn's disease and ulcerative colitis. In addition, CXCL5 is one chemokine which promote angiogenesis related to cancer. The objective of this study was to determine by ELISA assay whether CXCL5 protein level is altered in colorectal cancer (CRC) tissues (n=80) compared with paired normal mucosa. Furthermore, the plasma CXCL5 levels from CRC patients (n=62) compared with controls (n=71) were also examined. Using a TaqMan system we screened for -156G--> C and +398G-->A CXCL5 gene variants in CRC patients (n=228) and a control group (n=231) to assess the role of CXCL5 genotype in CRC. The analyses showed that CXCL5 protein level in colorectal tumours was significantly (P<0.0001) higher than in normal tissue and was lower in plasma in CRC patients compared with controls (P=0.026). Immunohistochemistry revealed CXCL5 immunoreactivity mainly in epithelial cells of the colorectal carcinoma and in normal epithelial cells. Furthermore, patients who were -156C carriers had higher CXCL5 protein concentration compared with -156G carriers in normal tissue (P=0.027) and CXCL5 protein levels in cancerous tissue tended to be higher for the patient -156C carriers (P=0.059). To our knowledge this is the first report on the influence of CXCL5 gene variants and their relation to expression of CXCL5 protein in human CRC.

A single bout of exercise activates matrix metalloproteinase in human skeletal muscle

The aims of this study were 1) to characterize changes in matrix metalloproteinase (MMP), endostatin, and vascular endothelial growth factor (VEGF)-A expression in skeletal muscle in response to a single bout of exercise in humans; and 2) to determine if any exchange of endostatin and VEGF-A between circulation and the exercising leg is associated with a change in the tissue expression or plasma concentration of these factors. Ten healthy males performed 65 min of cycle exercise, and muscle biopsies were obtained from the vastus lateralis muscle at rest and immediately and 120 min after exercise. In the muscle biopsies, measurements of mRNA expression levels of MMP-2, MMP-9, MMP-14, and tissue inhibitor of metalloproteinase; VEGF and endostatin protein levels; and MMP activities were performed. Femoral arterial and venous concentrations of VEGF-A and endostatin were determined before, during, and 120 min after exercise. A single bout of exercise increased MMP-9 mRNA and activated MMP-9 protein in skeletal muscle. No measurable increase of endostatin was observed in the skeletal muscle or in plasma following exercise. A concurrent increase in skeletal muscle VEGF-A mRNA and protein levels was induced by exercise, with no signs of peripheral uptake from the circulation. However, a decrease in plasma VEGF-A concentration occurred following exercise. Thus 1) a single bout of exercise activated the MMP system without any resulting change in tissue endostatin protein levels, and 2) the increased VEGF-A protein levels are due to changes in the skeletal muscle tissue itself. Other mechanisms are responsible for the observed exercise-induced decrease in VEGF-A in plasma.

Polymorphism and circulating levels of the chemokine CXCL12 in colorectal cancer patients

The chemokine CXCL12, also known as stromal cell-derived factor-1 (SDF-1), is a small protein that regulates leukocyte trafficking and is variably expressed in a number of normal and cancer tissues. CXCL12 as ligand and its receptor CXCR4 have been implicated in colorectal cancer (CRC) progression including angiogenesis and metastasis. A CXCL12 gene variant CXCL12-A (CXCL12-G801A, a single nucleotide polymorphism in the 3' untranslated region) is associated with increased susceptibility to breast cancer. Based on the suggested role of CXCL12 in the pathogenesis of cancer we examined the association of the gene variant CXCL12-A with CRC. The polymorphism was analysed with PCR and RFLP methods. Furthermore, the plasma CXCL12 levels from patients with CRC were also examined. There was no significant difference in genotype distribution and allelic frequencies between CRC patients (n=151) and controls (n=141). On the other hand, we found that the carrying rate of allele CXCL12-A was higher in colon cancer patients compared with rectal cancer patients (P=0.017). Analyses by ELISA showed that CRC patients (n=63) had a lower CXCL12 plasma level compared with controls (P<0.0001). Moreover, patients with tumours classified as Dukes' stage B and C revealed lower levels than patients with tumours in Dukes' stage A. Further studies with larger samples of patients are necessary to determine whether the CXCL12 polymorphism and plasma level reflect the clinical outcome of CRC and have an impact on CRC progression.

Expression of CD137 and CD137 ligand in colorectal cancer patients

The cytokine CD137, a member of the TNF receptor family, is expressed by T cells and regulates activation and proliferation of these cells. The CD137 ligand (CD137L) is expressed by antigen-presenting cells including macrophages, but also on various carcinoma cells. CD137/CD137L interaction plays a central role in sustaining T cell and macrophage activation, i.e. in antitumour immunity. The present study was designed to investigate whether CD137 and CD137L protein levels are altered in colorectal tumours compared with paired normal tissues. The CD137 and CD137L plasma levels from patients with colorectal cancer were also examined. Collectively, we noted a significantly lower CD137L level in cancerous tissue compared with paired normal tissue, and the difference in CD137L protein level was significantly lower in the colon cancer subgroup compared with paired normal colon tissue. On the other hand, we found an elevated CD137 protein level in the rectal cancer subgroup compared with paired normal rectal tissue. Patients with a tumour localised in the colon revealed significantly higher soluble CD137 protein concentration in the plasma than patients with a tumour localised in the rectum, and there was a tendency toward a higher concentration of CD137L protein in the plasma from patients with tumour localised in the colon. Moreover, the plasma concentrations of CD137 and CD137L proteins were strongly and significantly correlated. The different expression levels of CD137 and CD137L in the colon and rectum may reflect divergent mechanisms involved in the pathogenesis of colorectal cancer and lead to dissimilar protective immunity.

Interleukin-1 receptor antagonist gene polymorphism in human colorectal cancer

Several studies indicate that local immunoregulation and associated cytokines have a putative role in the development of cancer. There is evidence that pro-inflammatory cytokines such as interleukin-1 (IL-1) are critically involved with tumour progression. IL-1 receptor antagonist (IL-1Ra) is known to down-regulate and limit the inflammatory response. Therefore we attempted to examine the influence of the known polymorphism of the IL-1Ra gene on the development of human colorectal cancer (CRC). The study included 125 patients with CRC and 134 controls. Variable number tandem repeat (VNTR) polymorphism in intron 2 of the IL-Ra gene was analysed by the polymerase chain reaction method. There was a significant difference in genotype distribution between CRC patients and controls (P=0.025) and also in allelic frequencies (P=0.012). In detail the carriage rate of allele 3 in CRC patients was significantly increased compared with controls (P=0.007). We also found that the allelic distribution differs significantly between colon and rectum (P=0.041) and that allele 3 was overabundant in colon. The frequency of allele 1 in CRC patients with localized disease (Dukes A+B) was higher compared with disseminated disease (Dukes C+D), (P=0.035). These findings therefore suggest that the IL-1Ra polymorphism is associated with colorectal carcinogenesis.

Protein expression of the chemokine, CCL28, in human colorectal cancer

Accumulating evidence points out that chemokines play important roles in colorectal mucosal immunity by recruiting leukocytes into and out of the lamina propria adjacent to the epithelium. The chemokine, CCL28, which is expressed by epithelial cells within colorectal mucosa is thought to have dual roles as a chemoattractant for leukocytes expressing CCR10 and/or CCR3 and a mediator of antimicrobial activity. To date, there is little known about the presence of CCL28 in colorectal cancer. The objective of this study was to determine whether the CCL28 protein level is altered in colorectal tumours (n=76) compared with paired normal mucosa. Further, the plasma CCL28 levels from patients with colon and rectal cancer were also examined. Immunohistochemistry revealed heterogeneous CCL28 protein expression in tumour and normal epithelial cells. Analyses by ELISA showed that the CCL28 protein level in colon tumours was significantly (P<0.001) lower than in normal tissue and that the difference in CCL28 protein level between rectal tumour and normal tissue was not significant. Patients with a tumour localized in the colon had significantly (P<0.05) higher plasma CCL28 protein levels than patients with a tumour localized in the rectum. These discrepancies may suggest that there are different mechanisms and signalling pathways involved in the pathogenesis of cancer in the colon and rectum and thereby differentially promote the expression and secretion of CCL28 protein. Further studies on CCL28 protein in colorectal cancer with an extended number of patients are necessary to conclude whether tissue levels and plasma concentrations carry significant clinical relevance.

All-trans retinoic acid regulates CXCL16/SR-PSOX expression

Several studies have shown the ability of retinoids to modulate inflammatory response. CXCL16/SR-PSOX is a novel protein functioning as a chemokine and a scavenger receptor. We investigated effects of all-trans retinoic acid (atRA) on CXCL16/SR-PSOX expression in several cell types. Real-time PCR showed that atRA increased CXCL16/SR-PSOX mRNA expression in THP-1 and endothelial cells, which corresponded to increased release of CXCL16 protein from the cells, measured by ELISA. In THP-1 cells this effect was reduced by retinoic acid receptor (RAR) antagonist, which indicates receptor-mediated inhibition. RAR-alpha and RAR-gamma agonists increased CXCL16 release, which suggests RAR-mediated effect of atRA, which is not selective for a particular RAR subtype. In smooth muscle cells, up-regulation of CXCL16 mRNA was observed only after 96 h of treatment, while protein expression did not change. These findings suggest that retinoid signaling might be a pathway modulating inflammatory response by regulating CXCL16 expression in a cell-specific manner.

Interleukin-1 receptor antagonist gene polymorphism in human colorectal cancer

Several studies indicate that local immunoregulation and associated cytokines have a putative role in the development of cancer. There is evidence that pro-inflammatory cytokines such as interleukin-1 (IL-1) are critically involved with tumour progression. IL-1 receptor antagonist (IL-1Ra) is known to down-regulate and limit the inflammatory response. Therefore we attempted to examine the influence of the known polymorphism of the IL-1Ra gene on the development of human colorectal cancer (CRC). The study included 125 patients with CRC and 134 controls. Variable number tandem repeat (VNTR) polymorphism in intron 2 of the IL-Ra gene was analysed by the polymerase chain reaction method. There was a significant difference in genotype distribution between CRC patients and controls (P=0.025) and also in allelic frequencies (P=0.012). In detail the carriage rate of allele 3 in CRC patients was significantly increased compared with controls (P=0.007). We also found that the allelic distribution differs significantly between colon and rectum (P=0.041) and that allele 3 was overabundant in colon. The frequency of allele 1 in CRC patients with localized disease (Dukes A+B) was higher compared with disseminated disease (Dukes C+D), (P=0.035). These findings therefore suggest that the IL-1Ra polymorphism is associated with colorectal carcinogenesis.

Lipopolysaccharide-Induced Cytokine and Chemokine Expression in Human Carotid Lesions

The release of cytokines and chemokines from activated immune-competent cells plays a crucial role in determining the pathology of the atherogenic progress. We investigated the effect of bacterial lipopolysaccharide (LPS) on cytokine/chemokine expression in carotid lesions and normal renal arteries. The lesions or renal arteries were incubated for 6 h at 37 degrees C in serum-free media treated with or without LPS. After LPS treatment, increased protein levels of IL-1beta, IL-6, IL-8, IL-10, TNF-alpha and MCP-1 were observed in the culture medium from the lesions measured with cytometric bead array. We were able to detect the induction of IL-1beta, IL-6, IL-8, IL-10, TNF-alpha and MCP-1 mRNA in the lesions after stimulation with LPS using real-time PCR. In renal arteries, LPS also induces mRNA expression of all chemokines and cytokines investigated with the exception of IL-6. However, LPS induces significantly higher levels of TNF-alpha, IL-1beta and IL-10 mRNA in lesions compared to renal arteries. The results suggest that infectious agents are capable of enhancing the production of cytokines/chemokines in an already ongoing inflammatory process such as in atherosclerosis, and that low levels of circulating LPS may affect the levels of pro-inflammatory cytokines much more in atherosclerotic vessels than in normal vessels and may contribute to the development of the atherosclerotic lesion.

The antiviral cytomegalovirus inducible gene 5/viperin is expressed in atherosclerosis and regulated by proinflammatory agents

OBJECTIVE

Inflammatory processes play an important role in atherosclerosis, and increasing evidence implies that microbial pathogens and proinflammatory cytokines are involved in the development and activation of atherosclerotic lesions. To find new inflammatory genes, we explored the vascular transcriptional response to an activator of innate immunity bacterial lipopolysaccharides (LPSs).

METHODS AND RESULTS

Gene arrays identified the cytomegalovirus-inducible gene 5 (cig5)/viperin among the genes most potently induced by LPS in human vascular biopsies. Viperin was expressed by endothelial cells in atherosclerotic arteries and significantly elevated in atherosclerotic compared with normal arteries. In culture, cytomegalovirus infection, interferon-gamma, and LPS induced viperin expression.

CONCLUSIONS

Viperin is expressed in atherosclerosis and induced in vascular cells by inflammatory stimuli and cytomegalovirus infection. The putative functions of viperin in atherosclerosis may relate to disease-associated microbes.

BCRP mRNA expression v. clinical outcome in 40 adult AML patients

Efflux pumps are considered being mechanisms behind drug resistance in acute myeloid leukaemia (AML). A recently described efflux pump, breast cancer resistance protein (BCRP), can be expressed in AML, but its clinical importance is uncertain. In this study BCRP mRNA expression was determined in samples from 40 AML patients by real-time RT-PCR. The expression varied from negative to 76 times that of control cells. There was no difference in BCRP mRNA expression between patients responding to induction treatment and non-responders. However, in the group of responders, the 14 patients with the highest expression had significantly shorter overall survival (mean 38 months, SEM 15 months) than the 14 patients with the lowest (74 months, SEM 16 months) (P = 0.047). This suggests a possible role of BCRP in drug resistance in AML.

The chemokine and scavenger receptor CXCL16/SR-PSOX is expressed in human vascular smooth muscle cells and is induced by interferon gamma

Atherosclerosis is an inflammatory disease that is characterised by the involvement of chemokines that are important for the recruitment of leukocytes and scavenger receptors that mediate foam cell formation. Several cytokines are involved in the regulation of chemokines and scavenger receptors in atherosclerosis. CXCL16 is a chemokine and scavenger receptor and found in macrophages in human atherosclerotic lesions. Using double-labelled immunohistochemistry, we identified that smooth muscle cells in human lesions express CXCL16. We then analysed the effects of IFN-gamma, TNF-alpha, IL-12, IL-15, IL-18, and LPS on CXCL16 expression in cultured aortic smooth muscle cells. IFN-gamma was the most potent CXCL16 inducer and increased mRNA, soluble form, membrane form, and total cellular levels of CXCL16. The IFN-gamma induction of CXCL16 was also associated with increased uptake of oxLDL into these cells. Taken together, smooth muscle cells express CXCL16 in atherosclerotic lesions, which may play a role in the attraction of T cells to atherosclerotic lesions and contribute to the cellular internalisation of modified LDL.

Expression of chemokine receptor CXCR6 in human colorectal adenocarcinomas

Infiltration of inflammatory cells into colorectal adenocarcinomas is considered of importance for tumour progression. Tumour-associated macrophages and T cells are predominant components of the chemokine-guided filtrate of most colorectal tumours. CXCR6 is a chemokine receptor expressed by Th1, Tc, NKT cells and smooth muscle cells. To determine whether CXCR6 is expressed in human colorectal cancer and corresponding normal tissue, we analysed CXCR6 protein expression in 32 surgical specimens. Immunohistochemistry revealed CXCR6 protein predominantly localised in normal epithelial cells and some scattered stromal cells. No or weak expression was found in cancerous tissue. Western blot analysis showed, in 41% of the cases, a notable suppression of CXCR6 protein (p < 0.05) in cancerous tissue compared with non-cancerous tissue. Up-regulation was found in 9% of the cases. CXCR6 protein expression, in 25% of the cases, showed no difference between tumour and adjacent normal tissue. Furthermore, 25% of the cases revealed undetectable levels of CXCR6 protein in tumour as well as corresponding normal tissue. The results may reflect one of the immunological features of normal and cancerous colorectal tissue and studies on regulation of CXCR6 are necessary in order to determine its role in colorectal carcinogenesis.

Expression of CXCL16 in human rectal cancer

Local immunoregulation mediated by infiltration of inflammatory cells into colorectal adenocarcinomas is important for tumour progression. Tumour-associated macrophages and T cells are predominant components of chemokine-guided infiltrate of most colorectal tumours. CXCL16 is a newly discovered CXC chemokine expressed by antigen presenting cells attracting Th1, Tc and NK T cells. In this study, which is the first report on expression of the chemokine CXCL16 in human rectal cancer, CXCL16 gene and protein expression were analysed in cancer and normal adjacent tissue. Immunohistochemistry revealed CXCL16 expression in macrophages in normal tissue. The CXCL16 was found to a very limited extent in tumour-associated macrophages. Western blot analysis showed a suppression of CXCL16 protein in rectal cancer compared to non-cancer tissue in 83% of the patients (n=23, P=0.003). However, with real-time PCR mRNA was not down-regulated in the cancer compared to normal tissue, which may depend on regulated factor(s) at the level of translation and/or post-translation. The results may reflect one of the immunological mechanisms underlying carcinogenesis.

CXCL16/SR-PSOX is an interferon-gamma-regulated chemokine and scavenger receptor expressed in atherosclerotic lesions

OBJECTIVE

Atherosclerosis is an inflammatory disease. Several chemokines are important for monocyte/macrophage and T-cell recruitment to the lesion. CXCL16 is a recently discovered chemokine that is expressed in soluble and transmembrane forms, ligates CXCR6 chemokine receptor, and guides migration of activated Th1 and Tc1 cells. It is identical to scavenger receptor SR-PSOX, which mediates uptake of oxidized low-density lipoprotein. We investigated whether CXCL16 expression is controlled by interferon-gamma (IFN-gamma)-cytokine abundant in atherosclerotic lesions.

METHODS AND RESULTS

CXCL16 and CXCR6 expression was identified by polymerase chain reaction and histochemistry in atherosclerotic lesions from humans and apolipoprotein-E-deficient mice. In vitro IFN-gamma induced CXCL16 in human monocytic THP-1 cells and primary human monocytes, which led to increased uptake of oxidized low-density lipoprotein in THP-1 cells, which could be blocked by peptide antibodies against CXCL16. In vivo IFN-gamma induced CXCL16 expression in murine atherosclerotic lesions.

CONCLUSIONS

We demonstrate a novel role of IFN-gamma in foam cell formation through upregulation of CXCL16/SR-PSOX. CXCR6 expression in the plaque confirms the presence of cells able to respond to CXCL16. Therefore, this chemokine/scavenger receptor could serve as a molecular link between lipid metabolism and immune activity in the atherosclerotic lesion.

Down-regulation of ID2 by all-trans retinoic acid in monocytic leukemia cells (THP-1)

Accumulated evidence supports that both Id helix-loop-helix proteins and derivatives of vitamin A, retinoids, play a pivotal role in the regulation of cell growth and differentiation. We analyzed the effects of all-trans retinoic acid (atRA) on the gene and protein expression of Id2 in THP-1 cells and found a suppression of the levels of Id2. The down-regulation was abolished towards a constitutively expressed level of Id2 mRNA. The decreased level of Id2 was associated with growth suppression and does support the prevalent conception of the action of Id2 as a stimulator of cell growth.

Deficiency of nitric oxide synthase 2 results in increased neointima formation in a mouse model of vascular injury

Restenosis frequently occurs after arterial interventions. The inducible form of nitric oxide synthase (NOS2) may both promote and inhibit neointima formation. This study investigated the role of NOS2 for neointima formation in a mouse model of carotid artery injury. The common carotid artery was ligated in anesthetized mice. Homozygous NOS2 knockout mice were compared with wild-type B6/129 mice or wild-type mice treated with the pharmacologic NOS2 inhibitor aminoguanidine given orally daily after ligation (n = 6-8 in each group). Vessels were harvested for quantification of lesion size 4 weeks later, or serially after ligation for tissue analysis. mRNA for NOS2 increased 1-4 days after ligation of the carotid artery. Cell proliferation could be visualized with an antibody against proliferating cell nuclear antigen. An intimal smooth muscle cell layer, confirmed by an alpha-actin antibody, was observed in the lumen 4 weeks after injury. Inhibition of NOS2 by either pharmacologic or genetic approaches tended to increase the area of intima formation (P = 0.13 or P < 0.05, respectively) and increased the intima/media ratio (P = 0.14 and P < 0.01, respectively). Inhibition of NOS2 by two different approaches increased neointima formation in a mouse model of mechanical vessel injury, indicating that the NOS2 expressed in the injured vessel wall is beneficial.

Analysis of MICA gene transcripts in human rectal cancers

The human MHC class I chain-related gene A (MICA) encodes a protein which is an activator ligand for the NKG2D receptor on NK cells, CD8+ alpha beta T cells and gamma delta T cells. MICA expression is up-regulated upon cellular stress and its expression is correlated to infiltration of human NKG2D-bearing T cells into the tumors. It is assumed that the interaction of MICA-NKG2D ligand-receptor could play a significant role in induction of innate and adaptive responses against epithelial tumors, specifically those from the gastrointestinal tract. In this study MICA messenger RNA levels in human rectal carcinoma (Duke's stage B-D) and its normal adjacent tissue was analyzed in samples donated by 18 patients undergoing rectal tumor resection. Quantitative RT-PCR analysis from rectal tumors revealed that the overall expression of MICA at mRNA level differs extensively among individual tumors. In addition, invasive rectal tumors tend to up-regulate MICA whereas MICA mRNA levels were lower in early tumors. Differential transcription levels of MICA gene expression in rectal carcinomas at different stages is probably a strategy by tumors to escape confrontation with intraepithelial tumor-infiltrating T cells.

Induction of ATP-binding cassette A1 by all-trans retinoic acid: possible role of liver X receptor-alpha

ATP binding cassette A1 (ABCA1) is involved in the lipid metabolism of macrophages and has been suggested to play an important role in the development of foam cells and in the pathogenesis of atherosclerosis. We have investigated the effects of all-trans retinoic acid (atRA) on the mRNA and protein levels of ABCA1 in THP-1 cells. Our results show that both mRNA and protein levels of ABCA1 were significantly increased upon treatment with atRA. Since ABCA1 is highly regulated by liver X receptor (LXR) we also analysed the mRNA and protein expressions of LXR-alpha and LXR-beta in the THP-1 cells after treatment with atRA. Also the levels of LXR-alpha were increased by atRA. In conclusion, our results show that LXR-alpha and ABCA1 are simultaneously induced by atRA. The results also imply that the induction of ABCA1 by atRA may in part depend on the induction of LXR.