Kyushu University, Fukuoka, Japan.
Udayan Dental College, Rajpara, Bangladesh.
Arthritis Rheumatol. 2022 May;74(5):892-901. doi: 10.1002/art.42043. Epub 2022 Apr 10.
IgG4-related disease (IgG4-RD) is a fibro-inflammatory condition that can affect multiple organs. We previously demonstrated that TLR7-transgenic C57BL/6 mice showed elevated serum IgG1 levels and inflammation with fibrosis in the salivary glands (SGs), lungs, and pancreas. Moreover, we observed extensive Toll-like receptor 7 (TLR-7)-positive CD163+ M2 macrophage infiltration in SGs from IgG4-RD patients. We undertook this study to examine the fibrotic mechanism via the TLR-7 pathway.
Gene expression in SGs from human TLR7-transgenic mice and IgG4-RD patients was analyzed using DNA microarrays. We extracted the common up-regulated TLR-7-related genes in SGs from TLR7-transgenic mice and IgG4-RD patients. Finally, we investigated the interaction between CD163+ M2 macrophages and fibroblasts before and after stimulation with the TLR-7 agonist loxoribine.
In TLR7-transgenic mice and IgG4-RD patients, IRAK3 and IRAK4 were significantly overexpressed. Real-time polymerase chain reaction validated the up-regulation of only IRAK4 in IgG4-RD patients compared with the other groups (P < 0.05). Interleukin-1 receptor-associated kinase 4 (IRAK4) was strongly detected in and around germinal centers in SGs from patients with IgG4-related dacryoadenitis and sialadenitis alone. Double immunofluorescence staining showed that IRAK4-positive cells were mainly colocalized with CD163+ M2 macrophages in SGs (P < 0.05). After stimulation with loxoribine, CD163+ M2 macrophages exhibited significantly enhanced expression of IRAK4 and NF-κB and increased supernatant concentrations of fibrotic cytokines. Finally, we confirmed that the number of fibroblasts was increased by culture with the supernatant of CD163+ M2 macrophages following stimulation with loxoribine (P < 0.05).
CD163+ M2 macrophages promote fibrosis in IgG4-RD by increasing the production of fibrotic cytokines via TLR-7/IRAK4/NF-κB signaling.
IgG4 相关疾病（IgG4-RD）是一种纤维炎症性疾病，可影响多个器官。我们之前的研究表明，TLR7 转基因 C57BL/6 小鼠表现出血清 IgG1 水平升高和唾液腺（SGs）、肺和胰腺纤维化。此外，我们观察到 IgG4-RD 患者的 SGs 中有广泛的 Toll 样受体 7（TLR-7）阳性 CD163+M2 巨噬细胞浸润。我们进行了这项研究，以通过 TLR-7 途径研究纤维化机制。
使用 DNA 微阵列分析来自人 TLR7 转基因小鼠和 IgG4-RD 患者的 SG 中的基因表达。我们提取了 TLR7 转基因小鼠和 IgG4-RD 患者 SG 中常见的上调 TLR-7 相关基因。最后，我们研究了 TLR-7 激动剂洛索利巴刺激前后 CD163+M2 巨噬细胞与成纤维细胞之间的相互作用。
在 TLR7 转基因小鼠和 IgG4-RD 患者中，IRAK3 和 IRAK4 明显过表达。实时聚合酶链反应验证了与其他组相比，仅在 IgG4-RD 患者中 IRAK4 的上调（P<0.05）。在单独的 IgG4 相关泪腺炎和唾液腺炎患者的 SG 中，强烈检测到白细胞介素 1 受体相关激酶 4（IRAK4）在生发中心及其周围。双免疫荧光染色显示，IRAK4 阳性细胞主要与 SG 中的 CD163+M2 巨噬细胞共定位（P<0.05）。用洛索利巴刺激后，CD163+M2 巨噬细胞表现出 IRAK4 和 NF-κB 的表达明显增强，以及纤维化细胞因子的上清液浓度增加。最后，我们通过用洛索利巴刺激后的 CD163+M2 巨噬细胞的上清液培养证实了成纤维细胞数量增加（P<0.05）。
CD163+M2 巨噬细胞通过 TLR-7/IRAK4/NF-κB 信号通路增加纤维化细胞因子的产生，促进 IgG4-RD 中的纤维化。
