University of Alabama at Birmingham.
University of Alabama at Birmingham and Birmingham VA Medical Center.
Arthritis Rheumatol. 2022 Apr;74(4):634-640. doi: 10.1002/art.42008. Epub 2022 Feb 10.
To determine the extent to which the gut microbiome influences systemic autoimmunity in a mouse model of lupus.
We generated germ-free (GF) lupus-prone BXD2 mice, which under normal conditions develop spontaneous germinal centers (GCs) and high titers of serum autoantibodies. GF status was confirmed by gut bacterial culture. The autoimmune phenotypes of 6- and 12-month-old gnotobiotic GF BXD2 mice and specific pathogen-free (SPF) BXD2 mice were compared. Serum levels of autoantibodies were measured by enzyme-linked immunosorbent assay. Histologic sections of the mouse kidney and joints were evaluated. Flow cytometry was used to analyze GCs and age-associated B cells. CD4+ T cells were analyzed for PD-1+ICOS+ activated T cells, T follicular regulatory (Tfr) cells (Foxp3+CD25+ PD-1+CXCR5+), and PD-1+ICOS+ T cells expressing interleukin-17A (IL-17A) or interferon-γ (IFNγ) after stimulation with phorbol myristate acetate (PMA)/ionomycin.
In 6-month-old mice, GF status did not affect splenomegaly, GC B cells, age-associated B cells, or serum autoantibody levels, except for IgG antihistone. GF BXD2 mice exhibited a significantly higher percentage of Tfr cells compared to their SPF counterparts (P < 0.05). At 12 months of age, however, GF BXD2 mice had significantly diminished IgG autoantibody levels and a lower percentage of GC B cells and age-associated B cells (P < 0.05). Following stimulation with PMA/ionomycin, PD-1+ICOS+ CD4+ T cells expressed significantly lower IL-17A, but not IFNγ, levels in GF BXD2 mice compared to SPF BXD2 mice (P < 0.01). SPF BXD2 mice and GF BXD2 mice developed equivalent renal and joint disease with no significant differences in severity.
Our results suggest a model in which genetics plays a dominant role in determining the initial development of autoimmunity. In contrast, gut microbiomes may regulate the persistence of certain aspects of systemic autoimmunity.
确定肠道微生物组在狼疮小鼠模型中对系统性自身免疫的影响程度。
我们生成无菌（GF）狼疮易感 BXD2 小鼠，这些小鼠在正常情况下会自发形成生发中心（GC）并产生高滴度的血清自身抗体。通过肠道细菌培养来确认无菌状态。比较 6 月龄和 12 月龄无菌 BXD2 小鼠和特定病原体无菌（SPF）BXD2 小鼠的自身免疫表型。通过酶联免疫吸附试验测量血清自身抗体水平。评估小鼠肾脏和关节的组织学切片。使用流式细胞术分析 GC 和年龄相关的 B 细胞。用佛波醇肉豆蔻酸酯（PMA）/离子霉素刺激后，分析 CD4+T 细胞中的 PD-1+ICOS+活化 T 细胞、滤泡调节性 T 细胞（Foxp3+CD25+PD-1+CXCR5+）和表达白细胞介素-17A（IL-17A）或干扰素-γ（IFNγ）的 PD-1+ICOS+T 细胞。
在 6 月龄小鼠中，GF 状态不影响脾肿大、GC B 细胞、年龄相关 B 细胞或血清自身抗体水平，但 IgG 抗组蛋白除外。与 SPF 相比，GF BXD2 小鼠的 Tfr 细胞比例显著更高（P < 0.05）。然而，在 12 月龄时，GF BXD2 小鼠的 IgG 自身抗体水平显著降低，GC B 细胞和年龄相关 B 细胞的比例也较低（P < 0.05）。与 SPF BXD2 小鼠相比，PMA/离子霉素刺激后，GF BXD2 小鼠的 PD-1+ICOS+CD4+T 细胞表达的 IL-17A 水平显著降低，但 IFNγ水平无显著差异（P < 0.01）。SPF BXD2 小鼠和 GF BXD2 小鼠出现了等效的肾脏和关节疾病，严重程度无显著差异。
我们的结果表明，在决定自身免疫的初始发展方面，遗传起主导作用。相比之下，肠道微生物组可能调节系统性自身免疫的某些方面的持续存在。
