Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Department of Endocrinology, Severance Hospital, Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Korea.
Invest Ophthalmol Vis Sci. 2023 Aug 1;64(11):13. doi: 10.1167/iovs.64.11.13.
Graves' orbitopathy (GO) is an orbital manifestation of autoimmune Graves' disease, and orbital fibroblast is considered a target cell, producing pro-inflammatory cytokines and/or differentiating into adipocytes. Adipose tissue has been focused on as an endocrine and inflammatory organ secreting adipokines. We investigated the pathogenic role of a specific adipokine, adipsin, known as complement factor D in Graves' orbital fibroblasts.
The messenger RNA (mRNA) expression of multiple adipokines was investigated in adipose tissues harvested from GO and healthy subjects. Adipsin protein production was analyzed in primary cultured orbital fibroblasts under insulin growth factor (IGF)-1, CD40 ligand (CD40L) stimulation, and adipogenesis. The effect of blocking adipsin with small interfering RNA (siRNA) on pro-inflammatory cytokine production and adipogenesis was evaluated using quantitative real-time PCR, Western blot, and ELISA. Adipogenic differentiation was identified using Oil Red O staining.
Adipsin gene expression was significantly elevated in GO tissue and increased after the stimulation of IGF-1 and CD40L, as well as adipocyte differentiation in GO cells. Silencing of adipsin suppressed IGF-1-induced IL-6, IL-8, COX2, ICAM-1, CCL2 gene expression, and IL-6 protein secretion. Adipsin suppression also attenuated adipocyte differentiation. Exogenous treatment of recombinant adipsin resulted in the activation of the Akt, ERK, p-38, and JNK signaling pathways.
Adipsin, secreted by orbital fibroblasts, may play a distinct role in the pathogenesis of GO. Inhibition of adipsin ameliorated the production of pro-inflammatory cytokines and adipogenesis in orbital fibroblasts. Our study provides an in vitro basis suggesting adipsin as a potential therapeutic target for GO treatment.
Graves 眼病（GO）是自身免疫性 Graves 病的眼眶表现，眼眶成纤维细胞被认为是靶细胞，产生促炎细胞因子和/或分化为脂肪细胞。脂肪组织已被作为一种分泌脂肪因子的内分泌和炎症器官而受到关注。我们研究了一种特定的脂肪因子，即补体因子 D 已知的 adipsin，在 Graves 眼眶成纤维细胞中的致病作用。
研究了取自 GO 和健康受试者的脂肪组织中多种脂肪因子的信使 RNA（mRNA）表达。在胰岛素生长因子（IGF）-1、CD40 配体（CD40L）刺激和脂肪生成下，分析原代培养的眼眶成纤维细胞中 adipsin 蛋白的产生。使用定量实时 PCR、Western blot 和 ELISA 评估用小干扰 RNA（siRNA）阻断 adipsin 对促炎细胞因子产生和脂肪生成的影响。通过油红 O 染色鉴定脂肪生成分化。
adipsin 基因表达在 GO 组织中显著升高，并在 IGF-1 和 CD40L 刺激以及 GO 细胞的脂肪细胞分化后增加。沉默 adipsin 抑制 IGF-1 诱导的 IL-6、IL-8、COX2、ICAM-1、CCL2 基因表达和 IL-6 蛋白分泌。adipsin 抑制也减弱了脂肪细胞分化。外源性重组 adipsin 处理导致 Akt、ERK、p-38 和 JNK 信号通路的激活。
眼眶成纤维细胞分泌的 adipsin 可能在 GO 的发病机制中发挥独特作用。抑制 adipsin 可改善眼眶成纤维细胞中促炎细胞因子的产生和脂肪生成。我们的研究提供了体外基础，表明 adipsin 可能是 GO 治疗的潜在治疗靶点。
