Monocyte-related determinants of inflammation in patients on peritoneal dialysis.

AIMS: We studied markers of monocyte activation, i.e., the cell surface expression of CD11b and CD62L, and the serum concentrations of monocyte chemotactic protein 1 (MCP-1; a monocyte-specific chemoattractant) and soluble vascular cell adhesion molecule 1 (sVCAM-1; an adhesion molecule involved in monocyte recruitment) in 20 patients on peritoneal dialysis (PD), in 25 patients with chronic renal insufficiency, and in 27 healthy subjects. RESULTS: Monocytes obtained from the peripheral blood of PD patients had a significantly higher expression of CD62L (p = 0.02) as compared with monocytes from healthy subjects and a lower CD11b/CD18 expression as compared with monocytes collected from healthy subjects (p < 0.001) and from patients with renal insufficiency (p < 0.001). Monocytes from PD patients had, however, the capacity to increase the expression of CD11b following stimulation with a potent chemotactic factor. The serum concentrations of MCP-1 and sVCAM-1 were higher in PD patients (575 +/- 51 and 1,517 +/- 89 ng/ml) than in healthy subjects (225 +/- 17 and 668 +/- 64 ng/ml, respectively; p < 0.001 for both comparisons). There was a correlation between the levels of sVCAM-1 and MCP-1 (r = 0.48, p < 0.05) in patients on PD, but neither correlated with the monocyte expression of CD11b/CD18 or CD62L. The concentration of C-reactive protein was higher in patients on PD as compared with healthy subjects and correlated significantly with the concentration of sVCAM-1 (r = 0.63, p < 0.01). CONCLUSIONS: Monocytes in the peripheral circulation of patients on PD have a CD62L(high)/CD11b(low) phenotype, indicating that they have not undergone complete differentiation. Patients also have an increase in the systemic chemotactic activity for monocytes in combination with increased levels of sVCAM-1 and C-reactive protein. These inflammatory aberrations may play a pathophysiological role in the response to inflammatory and infectious diseases in patients on PD.

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.

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.

Dialysis-induced serum factors inhibit adherence of monocytes and granulocytes to adult human endothelial cells.

In patients on hemodialysis, the sequences of events required for adhesion molecule-mediated adherence of monocytes and granulocytes to endothelial cells are pathophysiologically disrupted because activation of the cells with subsequent alterations in adhesion molecule phenotypes takes place in the extracorporeal circuit far away from the respective endothelial cell ligand. As a consequence, the host defense to infections may be affected. We analyzed the expression of CD62L and CD11b/CD18 on monocytes and granulocytes and the adherence of these cells, collected before, during, and after cuprophan hemodialysis, to resting and interleukin-1 beta (IL-1 beta)-stimulated adult human saphenous vein endothelial cells (HSVECs). Monocytes collected before dialysis adhered more avidly to HSVECs than did granulocytes. Adherence of both cell types increased to IL-1 beta-stimulated HSVECs (P < 0.05). Granulocytes obtained at 180 minutes adhered less to resting HSVECs than granulocytes harvested before hemodialysis (P < 0.05), despite an increase in CD11b/CD18 expression. To study if serum factors inhibiting adherence accumulate during hemodialysis, we incubated leukocytes harvested before hemodialysis in the same patients' serum collected before, during, and after dialysis. Serum collected at 180 minutes of cuprophan hemodialysis exerted inhibitory effects on both monocyte and granulocyte adhesion to HSVECs (P < 0.05). By contrast, serum collected during polysulfone hemodialysis of the same patients did not have any significant impact on the adherence of inflammatory cells to HSVECs. These findings contribute to an increased understanding of the factors involved in the impaired immune response observed in dialysis patients.

Modulation of CD11b/CD18 on monocytes and granulocytes following hemodialysis membrane interaction in vitro.

We studied the generation of CD11b/CD18 mobilizing factors in serum after incubation with dialysis membrane fragments of different chemical composition. We also evaluated the relative importance of the alternative and classical pathways of the complement system in the generation of such factors. Monocytes and granulocytes from healthy blood donors were incubated in normal human serum (NHS) and in NHS that had been preincubated with Cuprophan (CU) membrane (NHS-CU), Hemophan (HE) (NHS-HE) or polysulfone (PS) (NHS-PS). NHS-CU caused the highest up-regulation of the CD11b/CD18 receptor on monocytes and granulocytes. The rank in capacity to mobilize CD11b/CD18 on granulocytes was CU > HE > PS (p < 0.001), CU > HE (p < 0.05) and HE > PS (p < 0.001). The rank in capacity to mobilize CD11b/CD18 on monocytes was CU > HE > PS (p < 0.001), CU > HE (p < 0.05) and HE > PS (p < 0.01). NHS-PS induced a lower up-regulation of CD11b/CD18 compared to NHS which indicates that serum factors with the ability to mobilize the CD11b/CD18 receptor on monocytes and granulocytes are deposited on or absorbed by PS. In order to study the relative contribution of the alternative and classical pathways of the complement system in the generation of CD11b/CD18 mobilizing factors in serum, three different serum preparations (1. both pathways intact. 2. only the alternative intact and 3. only the classical pathway intact) were used. The CU membrane activated the classical pathway to a larger extent than the PS membrane (p < 0.01). When only the alternative pathway was intact no difference in the generation of CD11b/CD18 mobilizing factors between the CU and PS membranes was observed. These studies show that CD11b/CD18 mobilizing serum factors are generated after incubation with CU membranes and that such factors are probably adsorbed by PS. The classical pathway of complement activation seems to contribute to the generation of CD11b/CD18 mobilizing factors in serum.

Monocyte and granulocyte CD11b/CD18, CD62L expression and sICAM-1 concentration in the interdialytic period.

We studied cell surface modulation of CD11b/CD18 and CD62L on monocytes and granulocytes, sICAM-1 concentrations and the responsiveness of cells to exogenous fMLP in patients in the intra- (0-4 h Cuprophan dialysis) and interdialytic period (5-28 h) and in healthy subjects (0-24 h). The high CD11b/CD18, low CD62L granulocyte phenotype occurred rapidly during dialysis. By contrast, CD62L increased on the subpopulation of monocytes in circulation initially during dialysis and CD11b/CD18 was mobilized much slower. In the interdialytic period, the CD62L/(CD11b/CD18) ratio was reduced up to 12 h after start of treatment on both monocytes and granulocytes. This ratio was significantly lower than in healthy subjects up to 8 h after start of treatment. The responsiveness of granulocytes to exogenous fMLP, in terms of CD11b/CD18 mobilization, was significantly reduced in patients during and after hemodialysis as compared to that on granulocytes obtained from healthy controls. Monocytes were more refractory to fMLP up to 4 h after dialysis. sICAM-1 was significantly increased in patients before dialysis as compared to controls and remained elevated and fairly stable throughout treatment and in the interdialytic period. The variation in the expression of adhesion molecules on monocytes and on granulocytes in the interdialytic period was not related to the presence of activating serum factors remaining in the circulation after treatment. Our findings emphasize the importance of including the interdialytic period in the evaluation of dialysis membrane biocompatibility, especially when effects on monocytes are of interest.

Cell surface receptor modulation on monocytes and granulocytes during clinical and experimental hemodialysis.

We studied the modulation of cell surface receptors related to cell adhesion (L-selectin and Mac-1) on monocytes and granulocytes during clinical (7 patients treated with cuprophan, Cu, and polysulfone, PS, membranes, n = 14) and experimental Cu and PS hemodialysis (n = 14). The objective was to compare cell surface receptor modulation in vivo when large subpopulations of cells are withdrawn from the circulating pool with the experimental model when cells are not sequestrated. The expression of Mac-1 and L-selectin on monocytes increased during clinical Cu dialysis (p = 0.024 and p = 0.0096, respectively) but remained stable during PS dialysis. On granulocytes, an inverse receptor modulation of Mac-1 and L-selectin was observed during clinical Cu dialysis but not during PS dialysis. Mac-1 was significantly higher and L-selectin lower on granulocytes after 15 min of clinical Cu as compared to PS dialysis (p = 0.001 and p = 0.0093, respectively). During experimental Cu dialysis, Mac-1 expression increased and L-selectin decreased markedly and continuously on both monocytes and granulocytes. The L-selectin/Mac-1 ratio on monocytes and granulocytes may be used as an index of the ability of leukocytes to adhere and to be recruited to an inflammatory focus. This ratio was significantly lower during clinical Cu as compared to PS dialysis (p = 0.0008 and p = 0.0015 respectively) indicating that the recruitment of leukocytes to infection foci may be precluded in patients on Cu membranes. Both monocytes and granulocytes showed significantly lower L-selectin/Mac-1 ratio during and after experimental Cu as compared to PS dialysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Mobilization of an intracellular glycoprotein (Mac-1) on monocytes and granulocytes during hemodialysis.

We studied the upregulation of the intracellular glycoprotein Mac-1 (CD11b/CD18, CR3) on monocytes and granulocytes during 36 bicarbonate hemodialyses in 12 patients who were randomly treated with Cuprophan (Cu), Hemophan (He) or Polysulfone (PS; low-flux) membranes. The degree of mobilization of this adhesion protein was related to changes in granulocyte and monocyte count, generation of C3a and production of interleukin-1 beta in plasma. Mac-1 expression on granulocytes was significantly higher after 5 and 15 min of Cu hemodialysis as compared to He or PS dialyses (p < 0.001) and correlated to changes in granulocyte count at 15 min (r = 0.62 and r = 0.76, p < 0.001). No differences in early Mac-1 mobilization on circulating monocytes was observed despite a decrease in cell count. Mac-1 expression on monocytes and granulocytes in the venous blood line at 180 min of treatment was significantly higher during Cu dialysis as compared to He and PS dialyses (p < 0.02 and p < 0.001, respectively). Early generation of C3a was higher in patients on Cu dialysis than in He or PS dialysis (p < 0.001) and correlated both to granulocytopenia (r = 0.45, p < 0.01) and to the subsequent increase in Mac-1 expression on granulocytes (r = 0.63, p < 0.001). An early increase in Mac-1 expression on monocytes was accompanied by an increase in plasma interleukin-1 beta later during dialysis (p < 0.05). Studies of Mac-1 expression during hemodialysis increased the sensitivity of biocompatibility measurements and correlated better than complement generation to changes in granulocyte count as it mediates adhesion to endothelial cells.

Hypertension profiling by total body water (TBW) determinations in patients on chronic hemodialysis.

Hypertension is an important risk factor in hemodialysis patients. Fluid overload and increased peripheral resistance are considered the two main causes. We studied the relation between volume state and blood pressure in 18 hemodialysis patients. Actual total body water (aTBW) was measured as tritium space and "ideal" total body water (iTBW) by an anthropometric method. The difference between aTBW and iTBW was considered a measure of fluid excess or deficit. Twelve patients were overhydrated, 5%-23%. Their predialysis blood pressure was significantly correlated to their degree of fluid excess; systolic BP:r = 0.71, p = 0.03, diastolic BP:r = 0.73, p = 0.02, mean arterial BP:r = 0.76, p = 0.03. Five of these patients had multiple antihypertensive drugs instead of adequate ultrafiltration. Five patients had a fluid deficit of -3 to -13% and hypertension due to vasoconstriction. Four of these were adequately treated with antihypertensive drugs but had exaggerated ultrafiltration. TBW determination with tritium is simple to perform and gives information on the volume state and thereby on the cause of hypertension in hemodialysis patients. Based on this, appropriate treatment can be chosen.