Research Unit, Hospital Universitario La Paz-FIBHULP, Madrid, Spain.
Nephrol Dial Transplant. 2011 Sep;26(9):2995-3005. doi: 10.1093/ndt/gfq771. Epub 2011 Feb 15.
Depending on the cytokine microenvironment, macrophages (Mϕ) can adopt a proinflammatory (M1) or a profibrotic (M2) phenotype characterized by the expression of cell surface proteins such as CD206 and CD163 and soluble factors such as CC chemokine ligand 18 (CCL18). A key role for Mϕ in fibrosis has been observed in diverse organ settings. We studied the Mϕ population in a human model of peritoneal dialysis in which continuous stress due to dialysis fluids and recurrent peritonitis represent a risk for peritoneal membrane dysfunction reflected as ultrafiltration failure (UFF) and peritoneal fibrosis.
We used flow cytometry and quantitative reverse transcription-polymerase chain reaction to analyse the phenotype of peritoneal effluent Mϕ and tested their ability to stimulate the proliferation of human fibroblasts. Mϕ from non-infected patients were compared with those from patients with active peritonitis. Cytokine production was evaluated by enzyme-linked immunosorbent assay (ELISA) in spent dialysates and cell culture supernatants.
CD206(+) and CD163(+) M2 were found within peritoneal effluents by flow cytometry analysis, with increased frequencies of CD163(+) cells during peritonitis (P = 0.003). TGFB1, MMP9 and CCL18 messenger RNA (mRNA) levels in peritoneal macrophages (pMϕ) were similar to those found in M2 cells differentiated in vitro. The ability of pMϕ to stimulate fibroblast proliferation correlated with CCL18 mRNA levels (r = 0.924, P = 0.016). CCL18 production by pMϕ was confirmed by immunostaining of cytospin samples and ELISA. Moreover, CCL18 effluent concentrations correlated with decreased peritoneal function, which was evaluated as dialysate to plasma ratio of creatinine (r = 0.724, P < 0.0001), and were significantly higher in patients with UFF (P = 0.0025) and in those who later developed sclerosing peritonitis (P = 0.024).
M2 may participate in human peritoneal fibrosis through the stimulation of fibroblast cell growth and CCL18 production as high concentrations of CCL18 are associated with functional deficiency and fibrosis of the peritoneal membrane.
根据细胞因子微环境的不同，巨噬细胞（Mϕ）可以表现出促炎（M1）或促纤维化（M2）表型，其特征是细胞表面蛋白如 CD206 和 CD163 的表达以及趋化因子 CC 配体 18（CCL18）等可溶性因子的表达。在多种器官中观察到 Mϕ 在纤维化中起着关键作用。我们在腹膜透析的人类模型中研究了 Mϕ 群体，在该模型中，由于透析液的持续压力和复发性腹膜炎，腹膜功能障碍表现为超滤衰竭（UFF）和腹膜纤维化的风险增加。
我们使用流式细胞术和定量逆转录聚合酶链反应分析腹膜灌流液中 Mϕ 的表型，并测试它们刺激人成纤维细胞增殖的能力。将非感染患者的 Mϕ 与患有活动性腹膜炎的患者的 Mϕ 进行比较。通过酶联免疫吸附试验（ELISA）在耗竭的透析液和细胞培养上清液中评估细胞因子的产生。
通过流式细胞术分析在腹膜灌流液中发现 CD206(+)和 CD163(+)M2，在腹膜炎期间 CD163(+)细胞的频率增加（P = 0.003）。腹膜巨噬细胞（pMϕ）中的 TGFB1、MMP9 和 CCL18 信使 RNA（mRNA）水平与体外分化的 M2 细胞相似。pMϕ 刺激成纤维细胞增殖的能力与 CCL18 mRNA 水平相关（r = 0.924，P = 0.016）。通过免疫细胞化学染色和 ELISA 对 pMϕ 分泌的 CCL18 进行了验证。此外，CCL18 流出浓度与腹膜功能下降相关，以肌酐的透析液到血浆比（r = 0.724，P < 0.0001）评估，在 UFF 患者（P = 0.0025）和随后发生硬化性腹膜炎的患者（P = 0.024）中明显更高。
M2 可能通过刺激成纤维细胞的生长和 CCL18 的产生而参与人类腹膜纤维化，因为 CCL18 的高浓度与腹膜功能障碍和腹膜纤维化有关。
