Increased expression of CD25 and HLA-DR on lymphocytes recruited into the peritoneal cavity in non-infected CAPD patients

Transmigration of Blood Leukocytes into the Peritoneal Cavity is Related to the Upregulation of ICAM-1 (CD54) and MAC-1 (CD11b/CD18) Adhesion Molecules

Background

Migration of blood leukocytes into the peritoneal cavity of patients treated with peritoneal dialysis appears to be an important mechanism to prevent and fight peritonitis. To study the role of adhesion molecules in the process of leukocyte transmigration, we compared the expression of several adhesion receptors between peripheral blood monocytes and macrophages isolated from overnight dwell effluents.

Methods

The study was performed in 12, stable, infection-free patients treated with continuous ambulatory peritoneal dialysis (CAPD) and in 9 patients during peritonitis. In another set of experiments, we analyzed the expression of these molecules on blood leukocytes in 10 predialysis chronic renal failure (CRF) patients and 9 healthy controls. Peritoneal cells from an 8-hour dwell were isolated by centrifugation. Expression of adhesion receptors CD11a, CD11b, CD18, CD49d, and CD54 on blood and peritoneal leukocytes was measured using flow cytometry.

Results

In macrophages from the uninfected effluents, expression of both subunits of Mac-1 integrin receptor (CD11b and CD18) and intercellular adhesion molecule (ICAM)-1 receptor (CD54) was upregulated compared to peripheral blood monocytes from the same patients. The median value of mean fluorescence intensity in blood and effluent was 760.3 versus 1085.8 for CD11b ( p = 0.013), 288.8 versus 448.6 for CD18 ( p = 0.003), and 186.1 versus 365.7 for CD54 ( p = 0.001). The same adhesion receptors were also significantly upregulated on peritoneal macrophages and neutrophils during peritonitis compared to blood leukocytes. Blood leukocytes from CAPD and CRF patients showed higher expression of CD54 and CD49d molecules compared to leukocytes from healthy controls.

Conclusions

These data suggest that transmigration of blood leukocytes into the peritoneal cavity during uncomplicated dialysis and in peritonitis is related to selective upregulation of ICAM-1 (CD54) and Mac-1 (CD18/CD11b) receptors.

Short-Term Effects of a New Bicarbonate/Lactate-Buffered and Conventional Peritoneal Dialysis Fluid on Peritoneal and Systemic Inflammation in CAPD Patients: A Randomized Controlled Study

Objectives

This study was designed to compare the local peritoneal and systemic inflammatory effects of a conventional lactate-based (Lac) peritoneal dialysis (PD) solution and a new biocompatible bicarbonate/lactate-based (Bic/ Lac) solution having low concentration of glucose degradation products.

Methods

26 stable, prevalent PD patients were enrolled in this prospective study. They sequentially underwent 3 months of therapy with the Lac solution and 3 months with the Bic/Lac solution in a randomized order. Flow cytometry was used to measure the expression of inflammatory molecules on peritoneal cells in overnight effluent collected at the end of each study period.

Results

21 patients successfully completed the study. Mean fluorescence intensity of human leukocyte antigen (HLA)-DR and CD14 expression by macrophages were not different between Lac and Bic/Lac. The peritoneal appearance rate of cancer antigen 125 (kU/minute) was 68 ± 37 with Lac and 133 ± 66 with Bic/Lac ( p < 0.001), and of interleukin (IL)-6 (ng/minute), 0.28 ± 0.2 with Lac and 0.18 ± 0.16 with Bic/Lac ( p = 0.014). HLA-DR macrophage expression and IL-6 peritoneal appearance rates did not correlate. Serum concentrations with Lac and Bic/Lac were, for IL-6, 3.49 ± 2.28 and 3.72 ± 2.46 ng/L ( p = 0.17), and for high-sensitivity C-reactive protein, 2.31 ± 2.98 and 2.71 ± 3.31 mg/L ( p = 0.32) respectively. The concentration of effluent macrophages (x106/L) with Lac was 1.6 ± 1.6 and with Bic/Lac 2.6 ± 3.3 ( p = 0.07).

Conclusions

We conclude that, although there was a significant reduction in peritoneal IL-6 in patients using Bic/ Lac solution, systemic levels of inflammatory markers did not differ between the two solutions and no changes were present in macrophage surface activation markers, suggesting perhaps a less important role of peritoneal macrophages in the intraperitoneal chronic inflammatory process. The number of effluent macrophages tended to be higher in patients using the Bic/Lac solution, possibly contributing to improved intraperitoneal defense.

Biomarker research to improve clinical outcomes of peritoneal dialysis: consensus of the European Training and Research in Peritoneal Dialysis (EuTRiPD) network

Peritoneal dialysis (PD) therapy substantially requires biomarkers as tools to identify patients who are at the highest risk for PD-related complications and to guide personalized interventions that may improve clinical outcome in the individual patient. In this consensus article, members of the European Training and Research in Peritoneal Dialysis Network (EuTRiPD) review the current status of biomarker research in PD and suggest a selection of biomarkers that can be relevant to the care of PD patients and that are directly accessible in PD effluents. Currently used biomarkers such as interleukin-6, interleukin-8, ex vivo-stimulated interleukin-6 release, cancer antigen-125, and advanced oxidation protein products that were collected through a Delphi procedure were first triaged for inclusion as surrogate endpoints in a clinical trial. Next, novel biomarkers were selected as promising candidates for proof-of-concept studies and were differentiated into inflammation signatures (including interleukin-17, M₁/M₂ macrophages, and regulatory T cell/T helper 17), mesothelial-to-mesenchymal transition signatures (including microRNA-21 and microRNA-31), and signatures for senescence and inadequate cellular stress responses. Finally, the need for defining pathogen-specific immune fingerprints and phenotype-associated molecular signatures utilizing effluents from the clinical cohorts of PD patients and "omics" technologies and bioinformatics-biostatistics in future joint-research efforts was expressed. Biomarker research in PD offers the potential to develop valuable tools for improving patient management. However, for all biomarkers discussed in this consensus article, the association of biological rationales with relevant clinical outcomes remains to be rigorously validated in adequately powered, prospective, independent clinical studies.

Functional and Transcriptomic Characterization of Peritoneal Immune-Modulation by Addition of Alanyl-Glutamine to Dialysis Fluid

Peritonitis remains a major cause of morbidity and mortality during chronic peritoneal dialysis (PD). Glucose-based PD fluids reduce immunological defenses in the peritoneal cavity. Low concentrations of peritoneal extracellular glutamine during PD may contribute to this immune deficit. For these reasons we have developed a clinical assay to measure the function of the immune-competent cells in PD effluent from PD patients. We then applied this assay to test the impact on peritoneal immune-competence of PD fluid supplementation with alanyl-glutamine (AlaGln) in 6 patients in an open-label, randomized, crossover pilot trial (EudraCT 2012-004004-36), and related the functional results to transcriptome changes in PD effluent cells. Ex-vivo stimulation of PD effluent peritoneal cells increased release of interleukin (IL) 6 and tumor necrosis factor (TNF) α. Both IL-6 and TNF-α were lower at 1 h than at 4 h of the peritoneal equilibration test but the reductions in cytokine release were attenuated in AlaGln-supplemented samples. AlaGln-supplemented samples exhibited priming of IL-6-related pathways and downregulation of TNF-α upstream elements. Results from measurement of cytokine release and transcriptome analysis in this pilot clinical study support the conclusion that suppression of PD effluent cell immune function in human subjects by standard PD fluid is attenuated by AlaGln supplementation.

Functional effector memory T cells enrich the peritoneal cavity of patients treated with peritoneal dialysis

The frequency and severity of episodes of peritonitis adversely affect the structure and function of the peritoneal membrane in patients treated with peritoneal dialysis (PD), but the underlying mechanisms are not well understood. Alterations in the phenotype and function of resident peritoneal cells may contribute. Because effector memory T cells play a pivotal role in maintaining peripheral tissue immunity, we hypothesized that these cells may initiate or perpetuate the peritoneal inflammatory response. Here, we characterized the phenotype and effector function of peritoneal memory T cells. We found that functional effector memory T cells capable of mounting long-term recall responses enrich the peritoneal cavity of PD patients. Peritoneal T cells were able to mount a Th1-polarized response to recall antigens, and these responses were greater in peritoneal T cells compared with T cells in the peripheral blood. We also observed that the peritoneal T cells had altered telomeres; some cells had ultrashort telomeres, suggesting a highly differentiated local population. In summary, we describe a resident population of memory T cells in the peritoneum of PD patients and speculate that these cells form part of the first line of defense against invading pathogens.

HLA-DR expression and apoptosis: a cross-sectional controlled study in hemodialysis and peritoneal dialysis patients

BACKGROUND

Altered HLA-DR expression and apoptosis have been described to reflect a state of immunological dysfunction in uremia. Here, we performed a cross-sectional, controlled study to evaluate monocyte HLA-DR expression and apoptosis in dialyzed chronic kidney disease patients.

METHODS

Monocyte HLA-DR expression was determined in 81 hemodialysis (HD) and 51 peritoneal dialysis (PD) patients and 40 healthy controls. By triple-color flow cytometry, we analyzed the percentage of monocytes in whole blood, the percentage of HLA-DR+ monocytes and the mean fluorescence intensity. Using U937 cell line incubated with the patients' plasma, we analyzed the percentage of apoptosis induced after 96 h.

RESULTS

Both HD and PD patients had lower, but statistically not significant, monocyte HLA-DR expression compared to controls (96.47 +/- 3.83% and 96.64 +/- 3.29% respectively, versus 98.42 +/- 1.05%). However, mean fluorescence intensity of HLA-DR was significantly higher in PD (149.35 +/- 80.96) than in HD (99.20 +/- 40.46), and controls (73.25 +/- 27.78, p < 0.001). Apoptosis was higher in both HD and PD (35.14 +/- 6.77 and 14.37 +/- 5.03%) compared to controls (11.30 +/- 2.03%, p < 0.001), and significantly higher in HD compared to PD.

CONCLUSION

A reduced inflammatory state and the continuous solute removal in PD may attenuate immune dysfunction in uremia. In HD but not in PD patients, there was a significant correlation between the percentage of HLA-DR+ monocytes with apoptosis (R = 0.230, p = 0.04).