Mac-1 Expression Research Articles

Beneficial effects of hydrocortisone in induced acute pancreatitis of rats

Little is known of the effects of hydrocortisone on cell adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) and its counterreceptors (LFA-1, Mac-1) in acute pancreatitis (AP). We investigated the effects of prior treatment with hydrocortisone on the production of ICAM-1 and its counterreceptors (LFA-1 and Mac-1) in AP of rats to clarify the effect of hydrocortisone on induced acute pancreatitis. Acute pancreatitis was induced by infusion of 5% chenodeoxycholic acid into the pancreatic duct, followed by ligation of pancreatic duct. Before induction of acute pancreatitis, rats were treated with hydrocortisone (n = 20) or 0.9% saline (n = 20). Blood and specimens from pancreas and lung were obtained from 5 rats from each treatment euthanized at 1 hour or 3 hours, 6 hours, 12 hours. Expression of ICAM-1 was assessed by immunohistochemistry and Western blot analysis of pancreas and lungs. The expression of LFA-1 and Mac-1 on neutrophils was detected by flow cytometer. The therapeutic effect of hydrocortisone was assessed from injuries to pancreas and lung. ICAM-1 expression in the pancreas of hydrocortisone group was significantly less than in control group at 3 hours and 6 hours. In the lungs of hydrocortisone group, ICAM-1 expression was significantly less than in control group at 3 hours, 6 hours and 12 hours. The expression of LFA-1 and Mac-1 on neutrophils in blood increased significantly in control group over hydrocortisone group. Increased expression of ICAM-1, LFA-1 and Mac-1 preceded leukocyte infiltration. Compared to untreated animals with acute pancreatitis, rats pretreated with hydrocortisone had significantly reduced histological lung injury and output of ascitic fluid. Prior treatment with hydrocortisone before the induction of acute pancreatitis ameliorates pulmonary injury and the output of ascitic fluid and reduces the expression of ICAM-1 and its counterreceptors (LFA-1, Mac-1) in acute pancreatitis.

Modification of neutrophil adhesion to human endothelial cell line in acute ischemic stroke by dipyridamole and candesartan

Ischemic stroke is a leading cause of disability. Inflammation of the vessel wall following neutrophil adhesion to vascular endothelium may contribute to ischemic damage. We studied the effect of a platelet inhibitor and an angiotensin II receptor antagonist: alone or in combination, on the adhesion of neutrophils to endothelial cell line in stroke patients. Neutrophils were collected from 12 patients with ischemic stroke within 48 h. Six patients with previous stroke and six healthy volunteers served as control. Neutrophils were incubated with dipyridamole, candesartan or both and allowed to adhere to human endothelial cell line (ECV-304). Adhesion and expression of adhesion molecules (AM) were determined using fluorescence-activated cell-sorting (FACS). Dipyridamole and the combination of dipyridamole and candesartan inhibited significantly the adhesion of neutrophils from ischemic stroke patients as compared to controls with a prominent additive effect. No inhibition was seen in the control groups. These drugs also reduced significantly the expression of the AM Mac-1. Both candesartan and dipyridamole inhibited the adhesion of neutrophils to vascular endothelium in ischemic stroke patients but not in chronic stroke patients or healthy persons. This effect may be related to specific downregulation of Mac-1 by these drugs or other intracellular events.

Bone marrow subpopulations contain distinct types of endothelial progenitor cells and angiogenic cytokine-producing cells

Therapeutic angiogenesis can be induced by the implantation of bone marrow cells (BMCs). However, the mechanism of BMC-mediated neovascularization remains to be clarified. We investigated the differential activities of bone marrow subpopulations in angiogenesis and cytokine production. BMCs were separated into positive and negative fractions by surface expression of Mac-1, Gr-1, CD19, and c-kit, respectively. After 7 days of culture in the presence of vascular endothelial growth factor (VEGF), the cells produced adherent cells which incorporate acetylated low-density lipoprotein (acLDL). Mac-1(+) and Mac-1(−) cells produced almost equal numbers of acLDL(+) cells, but only Mac-1(−) cells expressed endothelial markers, including Flk-1, vWF, and CD31. Similarly, the expression of endothelial markers was detected in Gr-1(−), CD19(−), and c-kit(+) BMC fractions at 7-day cultures, but not in Gr-1(+), CD19(+), or c-kit(−) cells. In contrast, freshly isolated Mac-1(+) and Gr-1(+) BMCs expressed higher levels of mRNAs for angiogenic cytokines (including VEGF-A, FGF-2, and HGF) than Mac-1(−) and Gr-1(−) cells, respectively. Moreover, Mac-1(+)/c-kit(+) BMC subpopulation expressed higher levels of VEGF-A and SDF-1 mRNAs than other subpopulations. These data demonstrate that a relatively small proportion of VEGF-cultured adherent cells are true endothelial cells with a Flk-1(+)/vWF(+)/CD31(+) phenotype. Moreover, endothelial stem/progenitor cells (EPCs) are limited primarily to Mac-1(−), Gr-1(−), and c-kit(+) BMC populations. In contrast, angiogenic cytokine mRNAs were also produced by Mac-1(+), Gr-1(+), and c-kit(−) BMCs, suggesting the heterogeneity of effector cell types for neovasculatization therapy.

Conformational activation of CD11b without shedding of L-selectin on circulating human neutrophils

Membrane-activated complex 1 (Mac-1; CD11b/CD18) is a beta(2) integrin implicated in the pathophysiology of neutrophil-mediated tissue injury whose functional capacity is determined by stimulus-induced conformational activation rather than up-regulation. Mac-1 up-regulation and conformational activation, together with shedding of L-selectin, are reported after in vitro neutrophil activation. However, their regulation on circulating human neutrophils during acute inflammation is unclear. Using flow cytometry, we investigated neutrophil expression of Mac-1, its activation-reporter neo-epitope CBRM1/5, and L-selectin during the inflammatory stimulus of cardiac surgery. A subpopulation of circulating neutrophils expressed CBRM1/5 (CBRM1/5+) under basal conditions (6.28+/-2.59%) and was persistently expanded (9.95+/-4.0%-15.2+/-4.2%; P<0.0001) peri-operatively, whereas total CD11b expression increased only transiently, intra-operatively. L-selectin expression was unchanged on CBRM1/5+ neutrophils, and soluble L-selectin levels decreased intra-operatively (P<0.01), indicating that L-selectin was not shed. Increased CBRM1/5 expression without L-selectin loss or CD11b up-regulation was replicated in vitro by neutrophil stimulation with IL-8, C3a, and platelet-activating factor. Heparin, a known CD11b ligand, which is administered during cardiac surgery, markedly reduced neutrophil expression of conformationally active CD11b in vivo and in vitro, identifying a potential mechanism for its anti-inflammatory properties. We conclude that conformational activation of CD11b occurs on circulating neutrophils in vivo and can occur in the absence of CD11b up-regulation and L-selectin shedding.

CD11b of Ovis canadensis and Ovis aries: Molecular cloning and characterization

Leukotoxin (Lkt) is the primary virulence factor secreted by Mannheimia haemolytica which causes pneumonia in ruminants. Previously, we have shown that CD18, the β subunit of β 2 integrins, mediates Lkt-induced cytolysis of ruminant leukocytes. CD18 associates with four distinct α subunits giving rise to four β 2 integrins, CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1), CD11c/CD18 (CR4), and CD11d/CD18. It is not known whether all the β 2 integrins serve as a receptor for Lkt. Since PMNs are the leukocyte subset that is most susceptible to Lkt, and Mac-1 expression on PMNs exceeds that of other β 2 integrins, it is of interest to determine whether Mac-1 serves as a receptor for Lkt which necessitates the cloning of CD11b and CD18. In this study, we cloned and sequenced the cDNA encoding CD11b of Ovis canadensis (bighorn sheep) and Ovis aries (domestic sheep). CD11b cDNA is 3455 nucleotides long encoding a polypeptide of 1152 amino acids. CD11b polypeptides from these two species exhibit 99% identity with each other, and 92% with that of cattle, and 70–80% with that of the non-ruminants analyzed.

High, but not moderate frequency and duration of exercise training induces downregulation of the expression of inflammatory and atherogenic adhesion molecules

Lifestyle changes which include daily exercise training have been shown to slow the progression of coronary artery disease. We designed a study to examine the effects of a multifactorial intervention on atherogenic adhesion molecules on the surface of monocytes in patients with coronary artery disease. We randomized 39 patients with coronary artery disease to (i) an intervention program which consisted of 4 weeks of daily 6x15 min ergometer training at submaximal intensity in addition to a 1 h/week group exercise session, followed by 5 months of home-based ergometer training of 30 min/day again in addition to a 1 h/week group exercise session or (ii) conventional therapy. All patients received a statin. Monocyte-bound cellular adhesion molecules LFA-1 (CD11a), MAC-1 (CD11b), VLA-4 (CD49d) and L-selectin (CD62L) were assessed by fluorescence activated cell sorting analysis. After 4 weeks the multifactorial intervention led to a significant improvement of maximal work capacity, lipid profile, body mass index, blood pressure, fasting glucose and hemoglobin A1c. This was associated with a reduced expression of MAC-1 and VLA-4. After 5 months of a home-based intervention the beneficial effects of the cardiovascular risk profile were still apparent, whereas the effects on the expression of adhesion molecules were blunted. In patients treated with statins, 4 weeks of high frequency and long duration exercise training led to a diminished expression of atherogenic adhesion molecules MAC-1 und VLA-4. After 5 months of home-based exercise training of moderate frequency and duration, these effects were blunted. Our data suggest that our patients in cardiac rehabilitation programs might further benefit from the antiatherogenic effects of an even higher amount of exercise training.

Loss of Mac-1 expression in mice leads to more severe forms of inflammatory disease in both the MRL/MpJ-Faslpr and CIA Models (97.1)

Abstract Mac-1 plays key roles in innate immune responses, and has also been implicated in the pathogenesis of diseases such as SLE and RA. Previously, we observed that Mac-1 deficiency in MRL/MpJ-Faslprmice, a model for SLE, resulted in a more severe inflammatory phenotype. To further examine mechanisms by which this adhesion molecule regulates inflammation in this model, we investigated whether loss of Mac-1 specifically altered T cell activation. We found that both Mac-1 deficient CD4+ and CD8+ T cells showed a hyperproliferative response following stimulation with low doses of anti-CD3 compared to control cells. We also analyzed T cell proliferation kinetics in Mac-1 deficient DO11.10 TCR transgenic T cells in response to Ova-peptide challenge and observed a similar hyperproliferation phenotype, suggesting that this adhesion molecule can negatively regulate T cell proliferation, independent of Faslpr gene expression. Finally, we analyzed Mac-1 deficient mice in the CIA model of RA to determine whether loss of expression of this adhesion molecule would also lead to a more severe inflammatory phenotype. We observed that Mac-1 deficient mice showed an accelerated onset of joint inflammation compared to wild type controls. Thus, these results suggest that Mac-1 can act as a negative regulator in the development of inflammatory diseases, possibly through controlling T cell activation and proliferation.

Synthetic inotropes inhibit the expression of adhesion molecules and augment the expression of l-selectin in polymorphonuclear neutrophils

To elucidate differential functional and phenotypic changes in response to clinically relevant synthetic inotropes plus the generation of oxidative free radicals by polymorphonuclear neutrophils (PMN), and changes in the expression of L-selectin and Mac-1 on the surface of PMN were examined in the presence of dobutamine and dopexamine in pharmacological concentrations. Prospective, in vitro study. Research laboratory. Human PMN obtained from healthy donors. PMN were pretreated with dobutamine 147.99 nM or 147,990 nM, or dopexamine 100 nM or 100,000 nM, followed by stimulation with FMLP. Stimulated neutrophils were incubated with antibiodies against CD11b or CD62l and assessed by flow cytometry. Additional probes were assessed by flow cytometry for the generation of oxidative free radicals. Low concentrations of both synthetic inotropes significantly inhibit the suppression of CD62l expression following stimulation with N-formyl-l-methionyl-l-leucyl-l-phenylalanine; high concentrations antagonize this effect. High concentrations of both synthetic inotropes suppresses the expression of CD11b. Neither dobutamine nor dopexamine modified the generation of oxidative free radicals. While the upregulation of Mac-1 expression is inhibited in a dose-dependent manner, the expression of L-selectin is enhanced at low concentrations of dobutamine and dopexamine and partly counter-regulated at high concentrations. It seems that synthetic inotropes can modulate the immunomodulatory ability by inhibition of PMN rolling and modification of PMN adherence and diapedese.

Impact of MK886 on Eosinophil Counts and Phenotypic Features in Toxocariasis

Experimental toxocariasis was used as a model of eosinophil migration. Mice inoculated with 200 Toxocara canis eggs were treated with the leukotriene inhibitor MK886 (1 mg/kg/day). Eosinophils were counted in peripheral blood (PB), peritoneal cavity (PC) and bronchoalveolar lavage fluid (BALF) samples on post-infection days 3, 6, 12, 18, 24 and 36. Eosinophil expression of Mac-1 and VLA-4 was analysed in PB and PC samples. We found that T. canis infection induced systemic eosinophilia from post-infection day 3, peaking on days 6, 12 and 24 in PB, PC and BALF samples respectively. Eosinophilia was more pronounced in PB and PC samples than in BALF samples, and MK886 downregulated eosinophilia to varying degrees in the different sample types. In PB and PC samples, T. canis infection caused early upregulation of Mac-1 with late changes in the VLA-4 profile, whereas MK886 had opposite effects. The distinct time-dependent eosinophilia peaks and differential involvement of leukotrienes in integrin expression demonstrate that, despite the systemic eosinophilia triggered by T. canis infection, inflammatory responses vary by compartment.

Increased platelet, leukocyte, and endothelial cell activity are associated with increased coagulability in patients after total knee arthroplasty.

Orthopedic surgery, especially total knee and total hip arthroplasty, is considered a risk factor for peri-operative venous thromboembolism. This study evaluates how accelerated inflammatogenic cellular interactions and the subsequent production of tissue factor and CD40 ligand play an important role in the pathogenesis of venous thromboembolism. Twenty-four patients undergoing total knee arthroplasty were randomly assigned to groups with (Ti; n = 12) and without (Tn; n = 12) pneumatic tourniquet inflation. Numbers of leukocyte-platelet aggregates, especially those comprising monocytes-platelets in central venous blood from the Ti group, were increased during the peri-operative period (P < 0.01), and returned to the baseline level at 24 h after starting surgery. Levels of PAC-1, P-selectin, CD40 ligand, tissue factor, Mac-1 expression on monocytes including monocyte-platelet aggregates, and the number of microparticles including those of endothelial cell origin were noticeably increased in central venous blood from the Ti group (P < 0.01). Whole blood coagulability was also obviously increased in central venous blood from the Ti group (P < 0.01). Furthermore, the concentrations of venous plasma tissue factor antigen, CD40 ligand, platelet factor 4, beta-thromboglobulin, the soluble fibrin monomer complex and prothrombin fragment 1+2 were also increased (P < 0.05). This study showed that platelet, leukocyte and endothelium activities as well as their interactions are enhanced during the peri-operative period of total knee arthroplasty, particularly in venous blood from the lower half of the body, which consequently augments blood coagulability. Further, tourniquet inflation during surgery exaggerates these responses.

AGEs and methylglyoxal induce apoptosis and expression of Mac-1 on neutrophils resulting in platelet—neutrophil aggregation

Introduction Diabetes mellitus is characterised by hyperglycaemia that plays an important role in the pathogenesis of diabetic complications including accumulation of methylglyoxal (MG), a highly reactive α-dicarbonyl metabolite of glucose degradation pathways and increased generation of advanced glycation end products (AGEs). The aim of this study was to investigate the impact of AGE-BSA, the model substance for AGEs, and MG on cellular haemostasis. Materials and methods Isolated peripheral blood mononuclear cells (PBMCs) or whole blood was incubated with AGE-BSA and MG. Markers of cellular haemostasis were monitored by flow cytometry. Results Exposure of PBMCs to AGE-BSA and MG resulted in a dose- and time-dependent increase of TF-expression by monocytes. AGE-BSA and MG induced enhanced platelet-neutrophil aggregation. Examination of platelet activation showed that AGE-BSA induces no direct effect on the expression of P-selectin. However, stimulation with MG resulted in a dose-dependent expression of P-selectin by platelets. Stimulation with AGE-BSA or MG markedly increased dose-dependent expression of Apo2.7 on the neutrophil mitochondria. In addition the analysis demonstrated for the first time that both AGE-BSA and MG induce a dose-dependent expression of the adhesion molecule Mac-1 on the surface of neutrophils. Conclusions AGE-BSA as well as MG induced apoptosis of neutrophils and enhanced expression of the adhesion molecule Mac-1 resulting in increased formation of platelet-neutrophil aggregates. These findings may contribute to better understand the mechanism of diabetic thrombosis and the associated high cardiovascular risk of diabetic patients.

The role of anti immune response on adenosine stimulated macrophages

Macrophages are essential for controlling the majority of infections, and are mediators of natural immunity. Namely, macrophages are the main cells that secrete anti-inflammatory cytokines, such as IL-10. IL-10 is an important suppressive cytokine, produced by many kinds of immune cells, which plays a key role in the anti-inflammatory immune responses. Adenosine mediates many of its effects through one or more of four receptors, the adenosine A 1 , A 2A , A 2B , and A 3 receptors, and it has been shown that A 2A adenosine receptor (A 2A R) is a critical part of the physiological negative feedback mechanism for limitation and termination of tissue-specific and systemic inflammatory responses. Mac-1 is an adhesion molecule required for apoptosis induced by other cell surface receptors, and is expressed on the surface of macrophages. Mac-1 expression is also necessary for the termination of an inflammatory reaction. To demonstrate how adenosine has its affects on macrophages to control inflammation, we evaluated the effects of adenosine in the RAW264 and THP-1 macrophage cell lines. Adenosine did not affect the proliferation in RAW264 cells regardless of the concentration. On the other hand, adenosine increased IL-10 production in RAW264 cells. Moreover, adenosine markedly increased the expression of CD11b, which is a Mac-1 alpha integrin. These results indicate that adenosine may affect the anti-inflammatory reactions in macrophages by enhancing the production of IL-10, and influence apoptosis by expression of CD11b.

Functional and phenotypic changes in polymorphonuclear neutrophils induced by catecholamines

Purpose. To elucidate differential functional and phenotypic changes in response to relevant catecholamines, the generation of oxidative free radicals by PMN, and changes in the expression of L-selectin and Mac-1 on the surface of PMN were examined in the presence of epinephrine, norepinephrine and dopamine in physiological and pharmacological concentrations. Materials and methods. Human polymorphonuclear neutrophils were obtained from healthy donors and pretreated with 0.5 nM or 500 nM epinephrine; 1.18 nM or 1 180 nM norepinephrine; or 0.26 nM or 261 nM dopamine, followed by stimulation with FMLP. Stimulated neutrophils were incubated with antibiodies against CD 11 b or CD 62 l and assessed by flow cytometry. Additional probes were assessed by flow cytometry for the generation of oxidative free radicals. Results. All catecholamines in high concentration inhibited the suppression of CD 62 l expression and CD 11 b upregulation following stimulation with FMLP. A high concentration of epinephrine suppresses generation of oxidative free radicals. Conclusions. The effect of catecholamines on the expression of CD 62 l explains the increased expression of L-selection on PMN observed after trauma. The suppression of CD 11 b reduces leukocyte adherence and consecutive abnormalities in microvascular flow. Epinephrine inhibits the generation of oxidative free radicals by PMN with potentially detrimental effects with respect to bacterial clearance.

Spontaneous leukocyte activation and oxygen-free radical generation in end-stage renal disease

Oxidative stress and inflammation are common features and major mediators of atherosclerosis in end-stage renal disease (ESRD). Available evidence for oxidative stress in ESRD is indirect and based on accumulation of byproducts of interactions of reactive oxygen species (ROS) with various molecules. Inflammation is a major cause of oxidative stress. To explore the direct link between oxidative stress and inflammation in ESRD, we studied leukocyte integrin expression and ROS production in 18 ESRD patients and 18 controls. ESRD patients showed elevated plasma malondialdehyde (MDA) and increased superoxide and hydrogen peroxide (H(2)O(2)) production by granulocytes and monocytes before dialysis. Hemodialysis resulted in a further rise in plasma MDA and H(2)O(2) production by granulocytes and monocytes. Surface expression of Mac-1 (CD11b and CD18) on granulocytes and monocytes was significantly increased (denoting cell activation) in ESRD patients. Granularity of granulocytes was significantly reduced before dialysis and declined further after dialysis. The magnitude of ROS production by granulocytes and monocytes was directly related with CD11b expression as well as plasma ferritin and parathyroid hormone levels and was inversely related to protein catabolic rate. Thus, this study provides direct evidence of spontaneous leukocyte activation and increased ROS generation (hence the link between oxidative stress and inflammation) in ESRD patients.

Serum Monocyte Chemoattractant Protein-1 and Monocyte Adhesion Molecules in Type 1 Diabetic Patients with Nephropathy

Monocyte chemoattractant protein (MCP)-1 is suggested to be implicated in the pathogenesis of diabetic nephropathy by activating and recruiting monocytes to the glomerulus via regulation of adhesion molecule expressions. The aim of this study was to test potential associations between serum concentrations of MCP-1, monocyte expression of Mac-1 and LFA-1 and nephropathy in type 1 diabetes mellitus. Serum MCP-1 levels and expression of monocyte adhesion molecules in 51 type 1 diabetic patients with and without diabetic nephropathy were compared with matched 15 healthy control subjects. Concentrations of serum MCP-1 were determined by enzyme-linked immunosorbent assays whereas monocyte expression of adhesion molecules Mac-1 and LFA-1 was measured by flow cytometry. Serum MCP-1 levels and expression of Mac-1, but not LFA-1, were significantly higher in diabetic patients compared with controls. The mean serum MCP-1 level was 137.2 +/- 71.4 pg/mL in control patients, whereas it was 246.2 +/- 114.9 pg/ml in diabetic patients (p = 0.002). Serum MCP-1 levels were positively correlated with HbA1c and plasma fasting glucose levels. There was no difference in serum levels of MCP-1 and expression of monocyte adhesion molecules between type 1 diabetic patients with and without diabetic nephropathy. In type 1 diabetic patients, the levels of circulating MCP-1 concentration and expression of Mac-1 is mostly influenced by glycemic control rather than the existence of diabetic nephropathy.

Type I IFN Modulates Host Defense and Late Hyperinflammation in Septic Peritonitis

TLRs are considered important for the control of immune responses during endotoxic shock or polymicrobial sepsis. Signaling by TLRs may proceed through the adapter proteins MyD88 or TIR domain-containing adaptor inducinng IFN-beta. Both pathways can lead to the production of type I IFNs (IFN-alphabeta). In the present study, the role of the type I IFN pathway for host defense and immune pathology in sepsis was investigated using a model of mixed bacterial peritonitis. Systemic levels of IFN-alphabeta protein were markedly elevated during septic peritonitis. More detailed analyses revealed production of IFN-beta, but not IFN-alpha subtypes, and identified CD11b+ CD11c- macrophage-like cells as major producers of IFN-beta. The results further demonstrate that in IFN-alphabeta receptor I chain (IFNARI)-deficient mice, the early recruitment of neutrophils to the infected peritoneal cavity was augmented, most likely due to an increased local production of MCP-1 and leukotriene B4. In the absence of IFNARI, peritoneal neutrophils also exhibited enhanced production of reactive oxygen intermediates and elevated expression of Mac-1. Conversely, administration of recombinant IFN-beta resulted in reduced leukotriene B4 levels and decreased peritoneal neutrophil recruitment and activation. Analysis of the cytokine response to septic peritonitis revealed that IFNARI deficiency strongly attenuated late, but not early, hyperinflammation. In accordance with these findings, bacterial clearance and overall survival of IFNARI(-/-) mice were improved. Therefore, the present study reveals critical functions of the type I IFN pathway during severe mixed bacterial infections leading to sepsis. The results suggest that type I IFN exerts predominantly adverse effects under these conditions.

Telmisartan inhibits β2-integrin MAC-1 expression in human T-lymphocytes

The pathogenesis of atherosclerosis, a chronic inflammatory disease, is influenced by the renin-angiotensin system and especially by angiotensin II subtype 1 (AT1) receptor activation. Although pro-inflammatory properties of angiotensin II as well as anti-inflammatory effects of AT1 receptor antagonists are well known, the underlying mechanisms are poorly understood. In a prospective double-blind study, patients with hypertension and coronary artery disease were treated with either 40 mg telmisartan (n = 21) or placebo (n = 21) for 12 weeks. General markers of inflammation, such as high-sensitivity C-reactive protein (hs-CRP) and interleukin-6 (IL-6), and cell adhesion molecules, such as soluble intercellular adhesion molecule (s-ICAM-1) and the leucocyte adhesion molecule soluble-L-selectin (sL-selectin), as well as the lymphocytic expression of the beta2 integrin MAC-1, were assessed before and after treatment. Telmisartan therapy significantly decreased the lymphocyte beta2 integrin MAC-1 expression, whereas hs-CRP, IL-6, s-ICAM and sL-selectin remained unaltered. In-vitro experiments were conducted to clarify the mode of action. Cultured human lymphocytes were stimulated with either angiotensin II or phorbol-12-myristate-13-acetate (PMA)/ionomycin, alone or after pretreatment with telmisartan. Whereas angiotensin II exerted no effect on beta2-integrin MAC-1 expression in lymphocytes, telmisartan dose-dependently inhibited beta2-integrin expression in lymphocytes in the absence or presence of angiotensin II. The AT1 receptor antagonist telmisartan inhibits the expression of the pro-inflammatory beta2-integrin MAC-1 expression in lymphocytes independently of angiotensin II, suggesting an AT1 receptor-independent atheroprotective effect of this AT1 receptor antagonist.

Vasculoprotective effects of angiotensin receptor blockers: beyond the renin–angiotensin–aldosterone system?

Vasculoprotective effects of angiotensin receptor blockers: beyond the renin–angiotensin–aldosterone system?

Hydroxytyrosol Administration Enhances Atherosclerotic Lesion Development in Apo E Deficient Mice

Hydroxytyrosol is a phenol found in olive oil. To verify the effect of hydroxytyrosol on the development of atherosclerosis, two groups of apo E deficient male mice on a standard chow diet were used: the control group receiving only water, and the second group an aqueous solution of hydroxytyrosol in order to provide a dose of 10 mg/kg/day to each mouse. This treatment was maintained for 10 weeks. At the moment of sacrifice, blood was drawn and heart removed. Plasma lipids, apolipoproteins and monocyte Mac-1 expression were assayed as well as aortic atherosclerotic areas in both groups. Data showed no significant changes in HDL cholesterol, paraoxonase, apolipoprotein B or triglyceride levels. However, hydroxytyrosol administration decreased apolipoprotein A-I and increased total cholesterol, atherosclerotic lesion areas and circulating monocytes expressing Mac-1. The latter was highly correlated with lesion areas (r = 0.65, P < 0.01). These results indicate that administration of hydroxytyrosol in low cholesterol diets increases atherosclerotic lesion associated with the degree of monocyte activation and remodelling of plasma lipoproteins. Our data supports the concept that phenolic-enriched products, out of the original matrix, could be not only non useful but also harmful. Our results suggest that the formulation of possible functional foods should approximate as much as possible the natural environment in which active molecules are found.

Granulocyte and Monocyte Adsorption Apheresis (GCAP) for Refractory Skin Diseases Caused by Activated Neutrophils and Psoriatic Arthritis: Evidence that GCAP Removes Mac‐1‐Expressing Neutrophils

In the present study, we have shown that granulocyte and monocyte adsorption apheresis (GCAP), an extracorporeal apheresis instrument whose column contains cellulose acetate (CA) beads, is useful for skin diseases attributable to activated granulocytes and psoriatic arthritis (PsA). We assessed the clinical effectiveness of GCAP and investigated the mechanisms underlying the adsorption of pathogenic granulocytes. The effect of GCAP was assessed in 14 patients with neutrophilic dermatoses and 16 with PsA. The mechanisms by which the instrument adsorbs activated granulocytes were investigated using an in vitro mini-column system that mimics the GCAP. Skin lesions and arthropathy improved in 22 of 29 patients (75.9%) and 14 of 18 (77.8%), respectively. Mac-1 (CD11b/CD18) expression on the peripheral neutrophils, increased compared with normal subjects, was reduced by GCAP. In the mini-column system, CA beads adsorbed 50% neutrophils; and adsorption was inhibited significantly by treating plasma with EDTA and blood cells with antihuman CD11b monoclonal antibody. GCAP was useful for treating neutrophilic dermatoses and PsA. GCAP adsorbs Mac-1-expressing neutrophils to the CA beads by the binding of complement component (iC3b) on CA beads and CD11b expressed on activated neutrophils.