Three monocyte-related determinants of atherosclerosis in haemodialysis.

BACKGROUND: It has been suggested that monocyte-related inflammatory mediators play a role in atherosclerosis. Haemodialysis induces phenotypic changes in adhesion molecule expression on monocytes. Soluble vascular cell adhesion molecule-1 (sVCAM-1), an adhesion molecule involved in monocyte recruitment, has been proposed to correlate with the extent of atherosclerosis in humans. Monocyte chemotactic protein-1 (MCP-1) functions as a monocyte-specific chemoattractant. METHODS: We studied monocyte count, CD11b/CD18 expression on monocytes, MCP-1, and sVCAM-1 in nine patients on either cuprophane or polysulphone haemodialysis (n=18 treatments) at times 0 (before haemodialysis), 3 h (end of haemodialysis), 4, 6, 8 and 24 h after start of treatment, as well as in 18 healthy subjects. RESULTS: Monocyte CD11b/CD18 expression increased with both membranes (P:<0.001) during and after dialysis compared to before treatment. The concentrations of sVCAM-1 and MCP-1 were higher in patients compared to those in controls both before, during and after haemodialysis (P:<0.001 at all time points). There were correlations between the expression of CD11b/CD18 on monocytes and the interdialytic concentrations of sVCAM-1 (r=0.76, P:<0.001) and MCP-1 (r=0.54, P:<0.05) and between MCP-1 and sVCAM-1 before and after haemodialysis (P:<0.05). CONCLUSION: Patients on haemodialysis have an increased systemic chemotactic activity for monocytes, unphysiological phenotypic alterations in CD11b/ CD18 expression during and after dialysis, and increased sVCAM-1 and MCP-1 concentrations. Prospective studies are needed to establish the role of these abnormalities in the pathogenesis of atherosclerosis in haemodialysis patients.     

Monocyte adhesion molecule expression in interstitial inflammation in patients with renal failure.

BACKGROUND: Patients with renal failure have an increased susceptibility to infections. We therefore studied the recruitment of monocytes and their expression of adhesion molecules CD11b and CD62L at the site of interstitial inflammation in patients with renal failure. Furthermore, we studied if the capacity of monocytes to up-regulate CD11b in interstitial inflammation was determined by the interstitial concentration of chemotactic factors. METHODS: Three intensities of interstitial inflammation (0, intermediate and intense) were established in skin blister chambers. Leukocyte count, CD11b/CD62L expression, monocyte chemotactic protein-1 (MCP-1) and blister activity in terms of CD11b mobilization were determined. RESULTS: The CD62L expression on monocytes was lower in the peripheral circulation in patients with renal failure compared with healthy subjects (P<0.005 and P<0.001). At the site of interstitial inflammation patients had a higher expression of CD62L (intermediate, P<0.05; intense, P<0.005). Furthermore, monocytes from patients had an impaired capacity to mobilize CD11b both in the peripheral circulation (P<0.005) and at the intermediate and intense sites of interstitial inflammation (P<0.005 and P<0.001, respectively) compared with cells collected from healthy subjects. We incubated monocytes in blister exudates, in order to explore whether this phenomenon is caused by cellular factors and/or to the interstitial concentration of chemotactic mediators. The expression of CD11b on monocytes from healthy blood donors incubated in blister exudates from either patients or healthy subjects in vitro was similar. The interstitial concentration of MCP-1 at the site of intermediate inflammation was significantly lower in patients with renal failure compared with the corresponding blister exudate collected from healthy subjects (P<0.05), but no differences were observed at the site of intense inflammation. Furthermore, neutralizing the action of MCP-1 in blister exudates with monoclonal antibodies did not have any impact on monocyte CD11b expression following incubation in blister exudates. CONCLUSION: These studies indicate that the impaired capacity of monocytes to mobilize CD11b at the site of inflammation in patients with renal failure is more dependent on constitutive cellular factors than the concentration of CD11b mobilizing factors in the interstitium.     

Impaired monocyte CD11b expression in interstitial inflammation in hemodialysis patients

BACKGROUND: It is not known to what extent intravascular phenotypic alterations in adhesion molecule expression induced by hemodialysis influence the recruitment of monocytes and their ability to up-regulate CD11b at the local site of inflammation in the interstitium. Using a skin suction chamber technique, we addressed these issues in eight hemodialysis patients and in eight healthy subjects. METHODS: Two skin blisters were raised on the forearm of each individual and blister exudate collected. The blisters were then stimulated with autologous serum (active blister, intense inflammation) or buffer (control blister, intermediate inflammation), respectively. Thereafter the patients were treated with Cuprophan hemodialysis for four hours. After 10 hours, the exudate was aspirated from each chamber in all subjects. Monocyte count and expression of CD11b were analyzed in serum and blister fluid by flow cytometry. Then, monocytes from healthy blood donors were incubated in blister fluid from patients and healthy subjects in order to determine the local chemotactic activity in terms of CD11b up-regulation. Monocyte chemotactic protein-1 (MCP-1), a marker of systemic monocyte chemotactic activity, was also analyzed in serum at 0 and 10 hours in all individuals. RESULTS: The number of monocytes at the site of inflammation in the interstitium in hemodialysis patients correlated with the expression of CD11b on transmigrated cells (r = 0.78, P < 0.001). Monocytes collected in the active blister fluid of dialysis patients expressed equal levels of CD11b as cells collected from healthy subjects. By contrast, monocytes collected from the control blisters of patients expressed lower levels of CD11b than cells from healthy subjects (P < 0.01), despite equal interstitial biological activity of CD11b-mobilizing factors in blister fluid from patients and healthy subjects and the fact that patients had higher systemic chemotactic activity in terms of MCP-1 concentration in serum (P < 0.001). CONCLUSION: Monocytes from hemodialysis patients have the capacity to mobilize CD11b to the same extent as cells from healthy individuals at the inflammatory spot, but more intense stimuli are required for such actions, probably because of a transient refractoriness.     

Monocyte activation and relationship to anti-proteinase 3 in acute vasculitis.

BACKGROUND: Monocytes have been suggested to play a role in antineutrophil cytoplasmic antibody (ANCA)-positive vasculitis, but their state of activation in vivo in patients is still unknown. METHODS: Twelve consecutive patients with acute anti-proteinase 3 (PR3)-positive vasculitis were included prospectively, and blood samples were drawn at diagnosis. As controls, peripheral blood was obtained from a group of patients with acute infection (n = 12) and from healthy controls (n = 12). Monocyte activation was estimated from the expression of adhesion molecules (CD62L and CD11b), production of oxygen radicals and serum concentrations of soluble inflammation markers and adhesion molecules [intercellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1)]. RESULTS: Compared with monocytes from healthy subjects, monocytes from patients with acute vasculitis expressed upregulated CD11b (P < 0.05) but had reduced production of oxygen radicals (P < 0.01). A high concentration of anti-PR3 correlated with decreased expression of CD62L (r = 0.71, P = 0.009) and increased expression of CD11b (r = 0.63, P = 0.02). The serum concentrations of soluble inflammation markers [soluble CD14, interleukin (IL)-6, tumour necrosis factor receptor 1 (TNFR1), IL-10 and IL-8] as well as soluble adhesion molecules (sVCAM-1 and sICAM-1) were increased. Monocytes in patients with acute vasculitis displayed a reduced production of oxygen free radicals (P < 0.01) but similar serum concentrations of soluble inflammation markers and adhesion molecules, as compared with the control group of patients with acute infection and negative PR3-ANCA. CONCLUSIONS: High anti-PR3 concentration in patients with acute vasculitis correlated with an activated adhesion molecule phenotype (CD62L(low)/CD11b(high)) in circulating monocytes, indicating a potential pathophysiological role for anti-PR3. An impaired production of oxygen radicals in monocytes in patients with vasculitis compared with those with acute infection may mirror the longer time interval from onset of first symptoms to admission, in patients with vasculitis.     

Correlation between soluble markers of endothelial dysfunction in patients with renal failure

AIM: Damage to the endothelium is an important component of atherosclerosis. It has been suggested to be quantified by measuring plasma markers, such as von Willebrand factor and thrombomodulin and soluble adhesion molecules. We hypothesized there may exist a correlation between the plasma levels of von Willebrand factor and thrombomodulin as markers of endothelial cell dysfunction and the serum concentrations of soluble adhesion molecules and monocyte chemoattractant protein-1 (MCP-1) in patients with renal insufficiency, and in patients on peritoneal dialysis or hemodialysis since these three groups of kidney patients are highly prone to develop cardiovascular diseases. RESULTS: The concentrations of von Willebrand factor and thrombomodulin in plasma were significantly higher in patients with kidney diseases as compared to healthy subjects (p = 0.017 and p < 0.001, respectively). The patients also had significantly higher concentrations of soluble vascular cell adhesion molecule-1 (sVCAM-1) and MCP-1 compared to healthy controls (p < 0.001 for both comparisons). There were strong correlations between the concentration of soluble intercellular adhesion molecule-1 (sICAM-1) and von Willebrand factor in patients with kidney failure (r = 0.63, p < 0.001) and between the concentration of thrombomodulin and sVCAM-1 (r = 0.61, p < 0.001). Furthermore, a negative correlation was observed between the concentration of thrombomodulin and the cell surface expression of CD11b on monocytes and granulocytes in the peripheral circulation (p < 0.01 in both cases). CONCLUSION: The strong correlation between markers of endothelial dysfunction and soluble adhesion molecules in patients with renal insufficiency and on dialysis strengthen the view that an ongoing stress on endothelial cells is present in this group of patients. This may play a pathophysiological role in the development of cardiovascular disease.     

Monocyte activation in peripheral blood and dialyser eluates: phenotypic profile and cytokine release

BACKGROUND/AIMS: Monocyte activation and subsequent cytokine generation is presumed to be involved in haemodialysis (HD)-related morbidity. The present study was designed to investigate HD-induced changes in monocytes, with respect to their phenotypic profile and cytokine release, both in peripheral blood (PB) and dialyser eluates (DE). In addition, the effect of the type of dialyser on monocyte activation was assessed. METHODS: Dialyser elution was performed in 8 patients after 3 h of HD, using cuprammonium (CU) and polysulfon (PS) dialysers in a randomised cross-over design. PB samples and DE were analysed for both the expression of a variety of monocyte cell surface markers (CD62L, CD11b, CD25, HLA-DR, CD64 and CD14) by flow cytometry and IL-1beta levels. Monocytes were identified by dual labelling with antibodies against CD14. RESULTS: In PB, the expression of CD11b increased during HD with both devices, but was more pronounced with CU (CU versus PS: p < 0.05). CD62L decreased during HD, but only significantly for PS (p < 0.02). HLA-DR was downregulated during HD with CU (p = 0.056). The expression of CD64 was higher during HD with CU (p = 0.02). Finally, CD14 increased during HD with both dialysers (p < 0.03). DE yielded a mean cell count of 51 x 10(6) cells. The proportion of monocytes in DE was 3% for CU and 4% for PS. In eluted monocytes, a significant upregulation of CD11b, CD25, and HLA-DR was observed. CD62L was downregulated when compared to PB at t(180) (p < 0.001). In DE, no correlation was found between the type of dialyser and the phenotypic changes. In 10 of 16 DE supernatants, 6 CU and 4 PS, IL-1beta release could be demonstrated, CU yielding significantly more of this cytokine than PS (p = 0.03). CONCLUSIONS: According to both their phenotypic profile and cytokine release, monocytes sticking to the dialyser membrane after HD are considerably more activated than circulating monocytes. Activation of eluted monocytes appeared independent of the type of dialyser, suggesting an effect of mechanical stress rather than bioincompatibility. In contrast, phenotypic activation of peripheral blood monocytes and cytokine release in the DE supernatant were mainly dialyser-dependent.     

Peripheral blood monocyte activation during coronary artery bypass grafting with or without cardiopulmonary bypass

OBJECTIVE: The aim of this prospective, randomized study was to investigate the impact of coronary artery bypass grafting (CABG) on peripheral monocytes and to evaluate the additional effect of cardiopulmonary bypass (CPB). DESIGN: Twenty patients admitted for elective CABG were randomized to either on-pump (ONCAB, n = 9) or off-pump (OFFCAB, n = 11) surgery and blood samples were drawn before, during and 24 h after the operation. The total number of monocytes and the proportion of the more mature CD16+/CD14+ monocytes were measured. Expression of activation markers (CD11b, CD35 and CD62L) and oxidative burst were determined using flow cytometry on both resting and in vitro stimulated cells. Serum concentrations of soluble CD14 and monocytes/macrophage chemotactic protein 1 (MCP-1) were analysed. RESULTS: During surgery there was a selective decrease in the proportion of CD16+/CD14+ monocytes compared to total monocytes. These had returned to preoperative values 24 h after surgery while the total number of monocytes had increased more than 100%. Intracellular production of oxygen free radical H2O2 was increased in the ONCAB group during surgery compared to OFFCAB. Monocyte expression and in vitro mobilization of complement receptors, CD11b and CD35, were similar in both study groups during and after surgery as was the expression of CD62L. Serum levels of MCP-1 decreased during surgery as did soluble CD14, both with increased levels again the day after surgery. CONCLUSION: It is concluded that the circulating monocyte population is activated during and as a consequence of CABG. There were few apparent additional effects of CPB found in this study. In this setting the inflammation caused by the surgery procedure per se probably surpasses the impact of the CPB on circulating blood monocytes.     

Granulocyte extravasation and recruitment to sites of interstitial inflammation in patients with renal failure

BACKGROUND: We have shown that leukocytes collected from sites of interstitial inflammation in patients on hemodialysis have a disturbed expression of CD11b compared to cells from healthy subjects. The aim of the present study was to study adhesion molecule expression on granulocytes in the peripheral circulation and at sites of interstitial inflammation in patients with renal failure. METHODS: Two skin blisters were raised in 10 patients and 19 healthy subjects and interstitial exudates collected (0 h). Skin chambers were applied and exposed to buffer or serum for 10 h in order to induce an intermediate and an intense interstitial inflammation. Cells and blister fluid were collected for determination of leukocyte count, CD11b/CD62L expression, interleukin-8 (IL-8) concentration in the interstitium and blister activity in terms of CD11b up-regulation. RESULTS: At the sites of intermediate and intense inflammation, granulocytes from patients with renal failure showed significantly higher expression of CD62L (p < 0.01 and p < 0.001, respectively) and significantly lower expression of CD11b (p < 0.0001 and p < 0.0001, respectively) compared to corresponding cells from healthy subjects. The interstitial concentration of IL-8 was significantly lower at the sites of intermediate (p < 0.005) and intense inflammation (p < 0.05) in patients with renal failure compared to in healthy subjects. In order to explore whether the decreased CD11b expression observed in patients is due to the interstitial milieu, blister exudates from patients and healthy subjects were incubated with leukocytes from healthy blood donors. Blister exudates from patients had a similar capacity to mobilize CD11b on granulocytes in vitro compared with blister exudates from healthy subjects. There was no consistent correlation between the expression of adhesion molecules on granulocytes in the interstitium and the concentration of IL-8 or the total interstitial concentration of chemotactic mediators. CONCLUSION: Constitutive cellular determinants are probably involved in the disturbed expression of adhesion molecules on granulocytes at sites of interstitial inflammation in patients with renal failure.     

Peripheral blood monocyte activation during coronary artery bypass grafting with or without cardiopulmonary bypass

Objective. The aim of this prospective, randomized study was to investigate the impact of coronary artery bypass grafting (CABG) on peripheral monocytes and to evaluate the additional effect of cardiopulmonary bypass (CPB).

Design. Twenty patients admitted for elective CABG were randomized to either on-pump (ONCAB, n=9) or off-pump (OFFCAB, n=11) surgery and blood samples were drawn before, during and 24 h after the operation. The total number of monocytes and the proportion of the more mature CD16⁺/CD14⁺ monocytes were measured. Expression of activation markers (CD11b, CD35 and CD62L) and oxidative burst were determined using flow cytometry on both resting and in vitro stimulated cells. Serum concentrations of soluble CD14 and monocytes/macrophage chemotactic protein 1 (MCP-1) were analysed.

Results. During surgery there was a selective decrease in the proportion of CD16⁺/CD14⁺ monocytes compared to total monocytes. These had returned to preoperative values 24 h after surgery while the total number of monocytes had increased more than 100%. Intracellular production of oxygen free radical H₂O₂ was increased in the ONCAB group during surgery compared to OFFCAB. Monocyte expression and in vitro mobilization of complement receptors, CD11b and CD35, were similar in both study groups during and after surgery as was the expression of CD62L. Serum levels of MCP-1 decreased during surgery as did soluble CD14, both with increased levels again the day after surgery.

Conclusion. It is concluded that the circulating monocyte population is activated during and as a consequence of CABG. There were few apparent additional effects of CPB found in this study. In this setting the inflammation caused by the surgery procedure per se probably surpasses the impact of the CPB on circulating blood monocytes.     

Increased serum levels of MRP-8/14 in type 1 diabetes induce an increased expression of CD11b and an enhanced adhesion of circulating monocytes to fibronectin

The recruitment of monocytes from the bloodstream is crucial in the accumulation of macrophages and dendritic cells in type 1 diabetic pancreases. Adhesion via integrins to endothelium and extracellular matrix proteins, such as fibronectin (FN), and the production of myeloid-related protein (MRP)-8, -14, and -8/14 by recently transmigrated monocytes are thought to be instrumental in such recruitment. We determined the FN-adhesive capacity and integrin expression of monocytes of type 1 and type 2 diabetic patients and related them to the subjects' serum levels of MRP-8, -14 and -8/14. Monocytes of type 1 diabetic patients displayed an increased adhesion to fibronectin in comparison with type 2 patients and healthy control subjects but had a normal expression of the FN binding integrins CD29, CD49a, CD49d, and CD49e (although CD11b and CD18 expression was increased). MRP-8/14, which was increased in the sera of type 1 diabetic patients, induced healthy donor monocytes to adhere to FN and upregulate CD11b expression in a dosage-dependent manner. The observed MRP-induced increased adhesion of monocytes to FN and upregulation of CD11b most likely contributed to a facilitated accumulation of monocytes and monocyte-derived cells at the site of inflammation, in this case the pancreatic islets.     

Monocyte apoptosis in dialysis patients is Fas ligand-mediated

BACKGROUND: The mononuclear phagocyte system plays an important role in host defense. Since dialysis patients have been reported to show enhanced leukocytes apoptosis, we evaluated the mechanism of increased apoptosis of monocytes in dialysis patients. METHODS: Apoptotic studies were carried out on monocytes isolated from dialysis patients as well as healthy subjects. The effect of dialysis sera and membranes was evaluated on monocyte apoptosis as well as monocyte expression of proapoptotic proteins such as Fas and FasL. To confirm the role of FasL, we evaluated the effect of activated secretory products on T cell apoptosis. In addition, we studied FasL content of dialysis sera and supernatants of activated monocytes. RESULTS: Monocytes isolated from dialysis patients (MDP) showed a greater magnitude of apoptosis when compared to monocytes isolated from healthy subjects (MHS) (MHS, 3.6 +/- 1.1% vs. MDP, 24.3 +/-1.4%). Sera of hemodialysis patients (SHD) promoted (p < 0.001) apoptosis of MHS when compared to pooled control sera (HPS) (HPS, 0.8 +/- 0.5% vs. SHD, 11.5 +/- 0.5% apoptotic cells/field). Dialysis membranes, cellulose acetate membranes in particular, promoted monocyte apoptosis. Interestingly, anti-FasL antibodies partly inhibited dialysis sera-induced monocyte apoptosis. Dialysis membranes also modulated monocyte expression of both Fas and FasL. Secretory products of activated monocytes also promoted T cell apoptosis. Dialysis sera and activated monocyte secretory products showed increased FasL content. CONCLUSIONS: These results suggest that dialysis patients have an increased rate of monocyte apoptosis, which is mediated through a uremic milieu (serum factors). One of these serum factors seems to be FasL. In addition, dialysis membranes seem to promote apoptosis independent of the uremic milieu. The present study provides a mechanistical insight into the enhanced apoptosis of monocytes in dialysis patients.     

The role of monocyte chemotactic and activating factor (MCAF)/monocyte chemoattractant protein (MCP)-1 in subgroups of rapidly progressive glomerulonephritis

To elucidate the role of monocyte chemotactic and activating factor (MCAF)/monocyte chemoattractant protein(MCP)-1 in the pathogenesis of rapidly progressive glomerulonephritis (RPGN), we determined the urinary levels of MCAF/MCP-1 in 20 healthy subjects, 30 patients showing RPGN with crescents, and 39 patients with various types of renal diseases without crescents. We divided RPGN into two subgroups, the acute type and the insidious type, with regard to the declination rate of reciprocals of serum creatinine with time as previously reported. In addition, we divided the patients with RPGN into anti-neutrophil cytoplasmic antibody(ANCA)-related diseases and immune complex(IC)-mediated diseases with regard to etiology. Urinary levels of MCAF/MCP-1 were significantly higher in patients with RPGN as compared with those of other renal diseases and healthy volunteers(21.8 +/- 4.5 vs. 11.6 +/- 3.5, 1.0 +/- 0.1 pg/ml creatinine, respectively, p < 0.01, mean +/- SEM). There was no difference in the urinary levels of MCAF/MCP-1 between the acute and insidious types of RPGN patients. In addition, there was no difference in the urinary levels of MCAF/MCP-1 between the patients with ANCA-related and IC-mediated diseases. Urinary levels of MCAF/MCP-1 in patients with RPGN were correlated well with the percentage of both total crescents and fibrocellular/fibrous crescents and the number of CD68-positive infiltrating cells in the interstitium. Immunohistochemical examinations revealed that MCAF/MCP-1 positive cells were detected in tubular epithelial and endothelial cells and mononuclear infiltrated cells in the interstitium. Moreover, elevated urinary MCAF/MCP-1 levels in patients with RPGN, regardless of subgroups, were dramatically decreased during methylprednisolone pulse therapy induced convalescence. These results suggest that MCAF/MCP-1 may be involved in the pathogenesis of RPGN via macrophage recruitment and activation.     

Cell-associated adhesion molecules as early markers of bioincompatibility

BACKGROUND.: Transient nature of adhesive interactions occurring during cellmargination is mainly dependent on expression of selectins whichare shed by activated cells. This shedding in the circulationmay play an important role as anti-inflammatory mediator. Haemodialysisis also associated with P-selectin (CD62P)/sialyl-Lewisx (CD15s)interactions which mediate platelet-leukocyte coaggregation.We further investigated the mechanisms underlying leukocytemargination during haemodialysis. METHODS.: CD15s, CD11b and CD61 expression on circulating leukocytes frompatients dialysed on synthetic membranes (modified polyacrylonitrile(SPAN), polysulphone (PS), and polyacrylonitrile (AN69) wasassessed by cytofluorometry in a prospective crossover trial.We measured plasma levels C3a/C3a desArg, soluble CD62P, andCD62E molecules obtained from patients and healthy individuals. RESULTS.: Expression of CD11b and CD15s was upregulated on neutrophilsfrom patients dialysed with SPAN and PS membranes during thedialysis session. A significant negative correlation was foundbetween the expression of CD11b or CD15s molecules and neutrophilcounts as well as between CD15s expression and monocyte countsduring haemodialysis. As assessed by CD61 expression on leukocytes,we observed that platelets bound significantly onto both neutrophilsand monocytes during dialysis with both membranes. A significantpositive correlation was found between the expression of CD11bmolecules and the percentage of CD61 ⁺ monocytes counts duringSPAN and PS dialysis. We found a significant increase of solubleCD62P in plasma samples obtained from haemodialysed patientsbefore the dialysis session as compared to the levels detectedin plasma from healthy individuals. CONCLUSIONS.: This study documents a major role of CD15s, CD11b, CD61, CD62Pmolecules in the transient leukocytes activation and marginationduring haemodialysis on synthetic membranes despite their lowcomplement-activating properties.     

HMG-CoA reductase inhibitors deplete circulating classical and non-classical monocytes following human heart transplantation

BACKGROUND: Monocytes mediate immune responses following solid organ transplantation via cytokine secretion and differentiation to macrophage/dendritic cell lineages. To date, the pleiotropic immunomodulatory effect of statins on human monocytes following human heart transplantation has yet to be elucidated. This study was designed to assess the effects of statin administration on the monocyte repertoire. METHODS: 108 patients were recruited into the study. Clinical data were collected from patients' notes. Peripheral blood immunophenotype was determined via flow cytometry (using CD11c, CD14, CD16, CD49d, CD64, CD80 and CD195). RESULTS: There were fewer circulating classical (p=0.0001) and non-classical (p=0.0013) monocytes in patients treated with a statin. CD64 expression was down-regulated (p=0.011 and p=0.049) whereas CD49d expression was up-regulated (p=0.004 and p=0.022) on classical and non-classical monocytes in this group. Patients receiving Atorvastatin had fewer circulating classical monocytes (p=0.001) compared to patients administered Pravastatin. Patients receiving Pravastatin had fewer circulating non-classical monocytes (p=0.029) compared to patients administered Atorvastatin. DISCUSSION: Statin administration alters the circulating monocyte repertoire following heart transplantation, including population size, FcgammaRI and VLA-4 adhesion molecule expression. Furthermore, different statin treatments are associated with a selective depletion of macrophage or DC (re)generating monocytes.     

Injury induces increased monocyte expression of tissue factor: factors associated with head injury attenuate the injury-related monocyte expression of tissue factor

BACKGROUND: Activated monocytes are able to express tissue factor (TF), a potent procoagulant. The effect of injury on monocyte TF expression is not known. We have found that patients with head injury (HI) have increased antithrombin activity and decreased platelet function compared with non-head-injured trauma patients. Our objective was to determine whether injury increases TF expression by monocytes and whether this increased TF expression is attenuated in patients with HI. METHODS: We prospectively enrolled 37 trauma patients (meeting the entry criterion of an Injury Severity Score [ISS] > or = 9) and 11 healthy control subjects. We sampled blood on arrival and then at 24, 48, and 72 hours. We performed flow cytometry with antibody markers for monocytes (CD14), platelets (CD42a), and TF. We compared results of patients with HI (Glasgow Coma Scale score < or = 9 and Abbreviated Injury Scale Head/Neck score > or = 3) with patients without HI and with controls. RESULTS: Patients had a mean ISS of 23.9 +/- 2.3 (+/- SEM), mean age of 45 +/- 3 years, and mean length of stay of 17.9 +/- 3.2 days. Seventy-six percent were men, and 97% had blunt trauma. The overall mortality rate was 11%. Trauma patients had greater monocyte TF expression than controls for all time periods (p < 0.05). Trauma patients with HI had elevated monocyte TF expression compared with controls for the initial and 24-hour time periods, but they subsequently had more rapid return of monocyte TF expression to baseline (despite a higher ISS) than trauma patients without HI. Trauma patients both with and without HI had increased platelet-monocyte binding at each time versus controls. CONCLUSION: Trauma induces TF expression on monocytes. Patients with HI have attenuation of this expression by 24 hours after injury. The attenuation of TF expression by monocytes in HI parallels the increase in AT and the decrease in platelet function seen after HI. The correlation of TF expression with platelet-monocyte binding suggests that platelet binding may lead to monocyte activation.     

Monocyte function-associated antigen expression during and after pediatric cardiac surgery

OBJECTIVE: Systemic inflammatory response syndrome and infectious complications are major causes of morbidity and mortality after cardiopulmonary bypass. Recent work in adult patients suggests that the balance between proinflammatory and anti-inflammatory mediators is important. We hypothesized that the expression of different function-related receptors on circulating monocytes might reflect the net response of the inflammatory reaction. METHODS: We performed a prospective and observational study in a tertiary pediatric cardiac center in a population of children (n = 40) undergoing elective cardiac surgery. Expression of receptors on the surface of monocytes was assessed before, during, and after surgical intervention. RESULTS: Early monocyte activation was demonstrated by changes of the expression of the chemokine receptor CCR2, which was inversely correlated with plasma levels of monocyte chemotactic protein 1 (rho = -0.54, P = .002). High levels of monocyte chemotactic protein 1 were found in children with high expression of the adhesion receptor CD11b/CD18 on circulating monocytes. The intensity of human leukocyte antigen DR expression rapidly decreased in all children after the onset of cardiopulmonary bypass ( P < .001). Low human leukocyte antigen DR expression was correlated with increased plasma levels of interleukin 10 postoperatively. Children who had signs of bacterial pneumonia postoperatively had lower levels of human leukocyte antigen DR expression before surgical intervention (relative risk, 13.3; P = .007). CONCLUSIONS: The expression of monocyte function-related receptors is altered after cardiac surgery. Early activation of monocytes by monocyte chemotactic protein 1 possibly released from the heart is followed by an anti-inflammatory response with suppression of monocyte human leukocyte antigen DR expression. The increased risk of bacterial infection after pediatric cardiac surgery can be anticipated by surveillance of monocyte function before surgical intervention.     

Effect of Surgically-Induced Weight Loss on Leukocyte Indicators of Chronic Inflammation in Morbid Obesity

Background: Recent evidence suggests that morbid obesity is a chronic inflammatory condition that may be associated with immune dysfunction.To test this hypothesis, we investigated several leukocyte cell surface markers of chronic inflammation and followed their response to surgically-induced weight loss. Methods: 26 patients having Roux-en-Y gastric bypass (RYGBP) for morbid obesity (BMI>40) were compared to 10 normal controls (BMI<25). Relative monocyte and neutrophil frequencies and expression of the activation antigens CD11b (adhesion molecule), CD16 (Fc receptor), and CD62L (Lselectin), were evaluated by flow cytometry preoperatively and at 1, 3, 6 and 12 months after RYGBP. Cases served as their own controls but were also compared to non-obese controls. The results were statistically analyzed using Student's t-test and ANOVA for parametric values and Mann-Whitney along with Kruskal-Wallis ANOVA for nonparametric values Results: The control group had mean age 37 ± 7.6 with mean 23 ± 2.5 and no comorbidities. The mean age of the sample group was 40.36 ± 13.7 with mean BMI 52 ± 8.2. The neutrophil and monocyte relative frequencies of CD11b (monocytes and neutrophils), and CD16 (neutrophils only) were comparable to controls at baseline and did not change significantly with weight loss throughout the study period. However, a significant reduction of CD62L (Lselectin) expression was noted in monocytes and neutrophils at baseline (neutrophils 103 vs 240 gmf, p<0.001) (monocytes104 vs 246 gmf, P<0.001) when compared to normal controls. Levels of L-selectin normalized by 6 months in both monocytes and neutrophils, and by 12 months had become abnormally elevated in monocytes (monocytes 391 gmf, P=0.007); in neutrophils, there was an upward trend that did not reach significance.The expression of the LPS receptor CD14 in the study group was elevated significantly compared to controls at baseline (1129 vs 719 gmf, P=0.004); this marker appeared to return to normal by 3 months. Monocyte CD14+/CD16+ subset percentage were also elevated significantly at baseline (14.3% vs 5.25%, P <0.001), declined throughout the time period but was still significant at 1 year (8.8%, P<0.001). Eosinophil percentages were elevated at baseline (3.3% obese vs 1.8% controls, P=0.003) and remained so throughout the time period. Conclusion: Deficiencies in the immune system of morbidly obese individuals include elevated levels of eosinophils, monocyte CD14, and monocyte CD14+/CD16+ subsets, with depression of monocyte and neutrophil CD62L. These abnormal levels reverse rapidly with surgically-induced weight loss. RYGBP is not only a weight loss operation but also appears to be an immune restorative procedure.     

Platelet activity and serum homocysteine levels in patients with end-stage renal failure with regard to dialysis modality

BACKGROUND: Recent evidence suggests that the activation of platelets and their interaction with circulating cells are important independent risk factors for atherosclerosis. In non-uremic patients with symptomatic peripheral vascular disease, a relationship between serum homocysteine (Hcy) levels and platelet activity had been reported. The purposes of this study were to evaluate of effects of dialysis modality on platelet activity in patients with end-stage renal failure and to investigate the relationship between platelet activity, Hcy, and left ventricular hypertrophy (LVH). MATERIAL AND METHODS: In age and sex matched 19 healthy subjects, 20 hemodialysis (HD) patients, and 18 continuous ambulatory peritoneal dialysis (CAPD) patients, the expression of platelet surface receptors CD41, CD61, CD42a, and CD62P were investigated. CD62P expression was statistically significantly increased in HD patients compared with CAPD patients and controls (34.4 +/- 22.5%; 17.3 +/- 19.6%, 12.0 +/- 15.6%, respectively, p < 0.05), but not in CAPD patients compared with controls. There was a positive correlation between CD62 expression and duration of dialysis in HD patients (r = 0.498, p = 0.026). Mean plasma Hcy levels in dialysis patients were higher than reference levels. However, we could not find any relationship between CD62 expression, Hcy, and LVH in both groups (p > 0.05). CONCLUSIONS: Hemodialysis and peritoneal dialysis (PD) have a different impact on the expression of CD62: peritoneal dialysis seems to have a more favorable effect. It may be possible that the differences in biocompatibility between PD and HD potentially contribute to differences in CD62 expression.     

Activation of peripheral blood CD14+ monocytes occurs in diabetes

Blood levels of inflammatory markers associated with endothelial dysfunction and atherosclerosis are increased in diabetic patients; the highest levels occur in poorly controlled diabetes. We investigated the activation state of peripheral blood monocytes in diabetes with respect to scavenger receptor (CD36) expression and monocyte chemoattractant protein-1, intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and peroxisome proliferator-activated receptors mRNA expression. CD14(+) monocytes were isolated from peripheral blood of type 1 and type 2 diabetic patients with good (HbA(1c) <7.0%) or poor (>9.4%) glycemic control and a group of nondiabetic subjects. Monocytes from diabetic subjects displayed increased CD36 cell surface expression (P < 0.0005) and increased uptake of oxidized LDL (P < 0.05). Monocyte chemoattractant protein-1 gene expression was increased in monocytes from both groups of diabetic subjects (P < 0.05). Both CD68 and peroxisome proliferator-activated receptor-gamma gene expression were increased in the poorly controlled diabetic group (P < 0.05 for each), whose monocytes also displayed increased attachment to endothelial monolayers (P < 0.0005 vs. nondiabetic control subjects). In poorly controlled diabetes, CD14(+) monocytes are functionally activated and show some of the differentiation markers associated with macrophages. These monocytes also demonstrate an increased ability for attachment to normal endothelial cells, one of the early stages in atherogenesis.     

Functional antibodies to leukocyte adhesion molecules in antithymocyte globulins

BACKGROUND: Polyclonal antithymocyte globulins (ATG) induce T-cell depletion and functional impairment of nondeleted lymphocytes. Interference of ATG with the main leukocyte surface molecules involved in cellular adhesion and leukocyte-endothelium interaction was investigated in the present study. METHODS: In three rabbit ATG, the authors measured antibodies to integrins, beta2-integrin ligands, and chemokine receptors by flow cytometry; chemotactic responses; and down-modulation of cell surface expression on lymphocytes, monocytes, and neutrophils. RESULTS: Antibodies to CD11a/CD18 (leukocyte function-associated antigen-1 [LFA-1]) present in ATG induced a dose-dependent down-modulation of cell surface expression of this beta2 integrin on lymphocytes, monocytes, and neutrophils. In contrast, anti-LFA-1 monoclonal antibodies did not induce LFA-1 modulation unless cross-linked by a second antibody. ATG also contained functional antibodies to the beta1 integrin CD49d/CD29 (VLA-4), the alpha4beta7 integrin, CD50, CD54, and CD102 but not to CD62L. ATG were shown to bind to CXCR4 and CCR7 on lymphocytes, CXCR4, and CCR5 on monocytes; to down-modulate cell surface expression of CCR7; and to decrease monocyte chemotactic response to CCL5 (RANTES) and lymphocyte chemotactic response to CCL19 (MIP-3beta). CONCLUSION: These results show that ATG may interfere with leukocyte responses to chemotactic signals but mostly inhibit the expression of integrins required for firm cellular adhesion. The latter property of inhibition is not shared by monoclonal antibodies, and it may contribute to decreasing graft cellular infiltration during acute rejection and possibly after postischemic reperfusion.