Influence of bicarbonate/low-GDP peritoneal dialysis fluid (BicaVera) on in vitro and ex vivo epithelial-to-mesenchymal transition of mesothelial cells.

BACKGROUND: Peritoneal membrane damage induced by peritoneal dialysis (PD) is largely associated with epithelial-to-mesenchymal transition (EMT) of mesothelial cells (MCs), which is believed to be a result mainly of the glucose degradation products (GDPs) present in PD solutions. OBJECTIVES: This study investigated the impact of bicarbonate-buffered, low-GDP PD solution (BicaVera: Fresenius Medical Care, Bad Homburg, Germany) on EMT of MCs in vitro and ex vivo. IN VITRO STUDIES: Omentum-derived MCs were incubated with lactate-buffered standard PD fluid or BicaVera fluid diluted 1:1 with culture medium. Ex vivo studies: From 31 patients randomly distributed to either standard or BicaVera solution and followed for 24 months, effluents were collected every 6 months for determination of EMT markers in effluent MCs. RESULTS: Culturing of MCs with standard fluid in vitro resulted in morphology change to a non-epithelioid shape, with downregulation of E-cadherin (indicative of EMT) and strong induction of vascular endothelial growth factor (VEGF) expression. By contrast, in vitro exposure of MCs to bicarbonate/low-GDP solution had less impact on both EMT parameters. Ex vivo studies partially confirmed the foregoing results. The BicaVera group, with a higher prevalence of the non-epithelioid MC phenotype at baseline (for unknown reasons), showed a clear and significant trend to gain and maintain an epithelioid phenotype at medium- and longer-term and to show fewer fibrogenic characteristics. By contrast, the standard solution group demonstrated a progressive and significantly higher presence of the non-epithelioid phenotype. Compared with effluent MCs having an epithelioid phenotype, MCs with non-epithelioid morphology showed significantly lower levels of E-cadherin and greater levels of fibronectin and VEGF. In comparing the BicaVera and standard solution groups, MCs from the standard solution group showed significantly higher secretion of interleukin 8 and lower secretion of collagen I, but no differences in the levels of other EMT-associated molecules, including fibronectin, VEGF, E-cadherin, and transforming growth factor ß1. Peritonitis incidence was similar in both groups. Functionally, the use of BicaVera fluid was associated with higher transport of small molecules and lower ultrafiltration capacity. CONCLUSIONS: Effluent MCs grown ex vivo from patients treated with bicarbonate/low-GDP BicaVera fluid showed a trend to acquire an epithelial phenotype, with lower production of proinflammatory cytokines and chemokines (such as interleukin 8) than was seen with MCs from patients treated with a lactate-buffered standard PD solution.

Analysis of expression and function of the inhibitory receptor ILT2 in lymphocytes from patients with autoimmune thyroid disease.

OBJECTIVE: Autoimmune thyroid disease (AITD) is characterized by different defects in immunoregulatory mechanisms. The immunoglobulin-like transcript receptor 2 (ILT2) or leukocyte Ig-like receptor 1 (LIRB1/CD85j) exerts an important immunoregulatory role. We hypothesized that the lymphocytes from AITD patients have a diminished expression and function of ILT2. The aim of this study was to investigate the expression and function of ILT2 in lymphocytes from patients with AITD. DESIGN AND METHODS: In this study, 18 patients with Hashimoto's thyroiditis (HT), 20 with Graves' disease, and 26 healthy controls were studied. ILT2 expression was analyzed by flow cytometry and immunohistochemistry in peripheral blood mononuclear cells (PBMC) and thyroid tissue. The regulatory function of ILT2 was assessed by an assay of inhibition of lymphocyte proliferation and by an analysis of cell cycle progression. The effect of ILT2 on cytokine synthesis was also evaluated. RESULTS: We found a significant increased expression of ILT2 by lymphocytes in AITD patients. ILT2 was also detected in the leukocyte infiltrate of thyroid tissue from HT patients. On the contrary, a significant diminished inhibitory activity of ILT2 on cell proliferation was observed in AITD patients. In addition, PBMC from AITD patients showed a diminished synthesis of interleukin 10 on ILT2 engagement. CONCLUSIONS: The abnormal expression and function of ILT2 detected in AITD suggests that this receptor may participate in the pathogenesis of this condition.