Genetic dissection of MPO-ANCA related systemic vasculitis-prone SCG/Kj mice.

为了明确自发性新月体肾炎/Kinjoh（SCG/Kj）小鼠血管炎、新月体肾炎和MPOANCA产生的遗传因素，我们利用雌性（B6×SCG/Kj）F_2互交小鼠进行了全基因组QTL定位。确定了14个非Fas QTL：肾小球肾炎的QTL位于1、10、13、16和17号染色体上，血管炎的QTL位于1和17号染色体上，异常MPOANCA产生的QTL位于1和10号染色体上。将来自SCG/Kj的统计学显著性QTL指定为Scg-1至Scg-5，将来自B6的统计学显著性QTL指定为Sxb-1至Sxb-4。将与异常MPO-ANCA连锁的两个QTL命名为Man-1和Man-2。我们还通过流式细胞术研究了自发性血管炎、新月体肾炎和异常MPOANCA产生的免疫病理机制。统计分析外周血白细胞计数（包括粒细胞、单核细胞、T淋巴细胞、B淋巴细胞和树突状细胞）与自身免疫表型的相关性。结果表明，粒细胞、单核细胞、CD 4-CD 8双阴性T细胞和DC的增加与包括MPO-ANCA和自身抗体水平在内的所有自身免疫表型、肾小球肾炎、血管炎和脾肿大显著相关。树突状细胞亚群研究显示，经典的DC，而不是浆细胞样DC，与自身免疫表型相关。因此，经典DC被认为在疾病发病机制中发挥一定作用。QTL分析发现了三到四个显著的基因座增加cDC和这些基因座是独立的先前已知的QTL的自身免疫SCG/Kj。这些结果表明，DCs的QTL在自身免疫性疾病的多步骤发病机制中作为早期易感基因，引起免疫系统的初始激活。

To define genetic factors for vasculitis, crescentic glomerulonephritis and MPOANCA production in the spontaneous crescentic glomerulonephritis-forming/Kinjoh (SCG/Kj) mouse, we performed genome-wide QTL mapping using female (B6×SCG/Kj) F_2 intercross mice. Fourteen non-Fas QTLs were identified: QTLs for glomerulonephritis were located on chromosomes 1, 10, 13, 16,and 17, those for vasculitis on chromosomes 1 and 17, and those for aberrant MPOANCA production on chromosomes 1 and 10. Statistically significant QTLs from SCG/Kj were designated Scg-1 to Scg-5 and those from B6 were designated Sxb-1 to Sxb-4. Two QTLs linked to aberrant MPO-ANCA were designated Man-1 and Man-2.We also investigated the immunopathological mechanism of spontaneous vasculitis, crescentic glomerulonephritis and abnormal MPOANCA production by flow cytometry. Correlation between values of leukocyte count including granulocytes, monocytes, T lymphocytes, B lymphocytes and dendritic cells (DCs) in peripheral blood and autoimmune phenotypes were statistically examined. As a result, increase of granulocytes, monocytes, CD4-CD8-double negative T cells and DCs were significantly associated with all of autoimmune phenotypes including MPO-ANCA and autoantibody levels, glomerulonephritis, vasculitis and splenomegaly. Subset study of dendritic cells revealed classical DCs, but not plasmacytoid DCs, were correlated with autoimmune phenotypes. Classical DCs were thus supposed to play some role in the disease pathogenesis. QTL analyses found out three to four significant loci for increase in cDCs and such loci were independent of previously known QTLs for autoimmunity in SCG/Kj. These facts suggested that QTLs for DCs acted as early susceptibility genes and caused initial activation of immune system in multistep pathogenesis of autoimmune diseases.