Ruiz-Gaspà Silvia, Guañabens Núria, Jurado Susana, Combalia Andreu, Peris Pilar, Monegal Ana, Parés Albert
Centro de Investigación Biomédica en Red en Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain.
Metabolic Bone Diseases Unit, Department of Rheumatology, Hospital Clínic, University of Barcelona, Barcelona, Spain.
Liver Int. 2020 Nov;40(11):2767-2775. doi: 10.1111/liv.14630. Epub 2020 Oct 13.
Osteoporosis is a common complication in patients with primary biliary cholangitis. Both bilirubin and lithocholic acid (LCA) result in detrimental effects on osteoblastic cells, and ursodeoxycholic acid (UDCA) counteracts these outcomes. However, there is no information on the consequences of these retained substances of cholestasis and sera from cholestatic patients in osteocytes.
The impact of bilirubin, LCA, UDCA and serum from jaundiced patients on viability, differentiation, mineralization and apoptosis has been assessed in MLO-Y4 and MLO-A5 osteocyte cell lines. Effects on gene expression were assessed in these cells and in human bone fragments.
Lithocholic acid 10 μmol/L and bilirubin 50 μmol/L decreased viability in MLO-Y4 and MLO-A5 cells (11% and 53% respectively; P ≤ .01). UDCA alone or combined with LCA or bilirubin increased cell viability. Jaundiced sera decreased cell viability (56%), an effect which was reverted by UDCA. Bilirubin decreased differentiation by 47% in MLO-Y4 (P ≤ .01) and mineralization (87%) after 21 days in MLO-A5 (P ≤ .03). Both bilirubin and LCA increased apoptosis in MLO-Y4, and UDCA diminished the apoptotic effect. Moreover, bilirubin down-regulated RUNX2 and up-regulated RANKL gene expression in bone tissue, MLO-Y4 and MLO-A5 cells, and LCA up-regulated RANKL expression in bone tissue. UDCA 100 μmol/L increased the gene expression of all these genes in bone tissue and MLO-Y4 cells and neutralized the decreased RUNX2 expression induced by bilirubin.
Bilirubin and LCA have damaging consequences in osteocytes by decreasing viability, differentiation and mineralization, increasing apoptosis and modifying gene expression, effects that are neutralized by UDCA.
骨质疏松是原发性胆汁性胆管炎患者的常见并发症。胆红素和石胆酸（LCA）均对成骨细胞产生有害影响，而熊去氧胆酸（UDCA）可抵消这些影响。然而，目前尚无关于胆汁淤积的这些潴留物质及胆汁淤积患者血清对骨细胞影响的相关信息。
已在MLO - Y4和MLO - A5骨细胞系中评估了胆红素、LCA、UDCA及黄疸患者血清对细胞活力、分化、矿化和凋亡的影响。并在这些细胞及人骨碎片中评估了对基因表达的影响。
10 μmol/L的石胆酸和50 μmol/L的胆红素降低了MLO - Y4和MLO - A5细胞的活力（分别降低11%和53%；P≤0.01）。单独使用UDCA或与LCA或胆红素联合使用均可提高细胞活力。黄疸血清降低了细胞活力（56%），而UDCA可逆转这一效应。胆红素使MLO - Y4细胞的分化降低47%（P≤0.01），并使MLO - A5细胞在21天后的矿化降低87%（P≤0.03）。胆红素和LCA均增加了MLO - Y4细胞的凋亡，而UDCA可减弱凋亡效应。此外，胆红素下调了骨组织、MLO - Y4和MLO - A5细胞中RUNX2的表达并上调了RANKL基因的表达，LCA上调了骨组织中RANKL的表达。100 μmol/L的UDCA增加了骨组织和MLO - Y4细胞中所有这些基因的表达，并中和了胆红素诱导的RUNX2表达降低。
胆红素和LCA通过降低活力、分化和矿化、增加凋亡及改变基因表达对骨细胞产生损害作用，而UDCA可抵消这些作用。
