IZKF Research Group 2, Nikolaus Fiebiger Centre of Molecular Medicine, Department of Internal Medicine 3 and Institute for Clinical Immunology, Friedrich-Alexander-University Erlangen-Nuremberg, 91054 Erlangen, Germany.
Rheumatology (Oxford). 2010 Dec;49(12):2255-63. doi: 10.1093/rheumatology/keq272. Epub 2010 Aug 17.
To investigate the presence of autoantibodies against mammalian chaperones of the endoplasmic reticulum (ER) in patients with RA and other immune-mediated diseases.
Sera from healthy donors, from early RA patients with two follow-up samples, patients with SLE, SSc and IBD were collected and analysed for anti-ER chaperone antibodies. Detection of serum IgG antibodies against immunoglobulin heavy chain binding protein (BiP), glucose-regulated protein 94 (Grp94) and calnexin was carried out using ELISA. The specificity of sera positive for individual ER chaperones was confirmed by immunoblotting. Statistical analysis was performed using Welch's t-test, Mann-Whitney U-test, partial correlation and Pearson's correlation.
In patients with RA and SLE, autoantibody titres against BiP, Grp94 and calnexin were significantly higher than those in healthy controls. These autoantibodies were detectable in patients with early RA and titres remained stable for at least 6-12 months. Also several SSc and IBD patients exhibited autoantibodies against these ER chaperones; however, titres and frequencies were lower than in RA or SLE patients. Furthermore, anti-calnexin antibodies correlated significantly with the presence of BiP and Grp94 autoantibodies in patients with RA and SLE.
Calnexin and Grp94 were identified as novel autoantigens in RA and calnexin in SLE. Since calnexin, Grp94 and BiP are ER-resident proteins of eukaryotic cells, our data suggest that autoantibody generation against ER chaperones is independent of initial exposure to the corresponding bacterial chaperones; rather, ER chaperones may represent genuine autoantigens.
研究哺乳动物内质网（ER）伴侣蛋白自身抗体在类风湿关节炎（RA）和其他免疫介导性疾病患者中的存在情况。
收集健康供体、早期 RA 患者的两份随访样本、SLE、SSc 和 IBD 患者的血清，并分析其抗 ER 伴侣蛋白抗体。采用 ELISA 法检测血清 IgG 抗体针对免疫球蛋白重链结合蛋白（BiP）、葡萄糖调节蛋白 94（Grp94）和钙网蛋白的反应性。通过免疫印迹法确认针对单个 ER 伴侣蛋白阳性血清的特异性。采用 Welch 检验、Mann-Whitney U 检验、偏相关和 Pearson 相关进行统计学分析。
RA 和 SLE 患者的 BiP、Grp94 和钙网蛋白自身抗体滴度明显高于健康对照组。这些自身抗体在早期 RA 患者中可检测到，且至少在 6-12 个月内保持稳定。此外，一些 SSc 和 IBD 患者也表现出针对这些 ER 伴侣蛋白的自身抗体，但滴度和频率均低于 RA 或 SLE 患者。此外，RA 和 SLE 患者的抗钙网蛋白抗体与 BiP 和 Grp94 自身抗体的存在显著相关。
钙网蛋白和 Grp94 被鉴定为 RA 的新自身抗原，钙网蛋白在 SLE 中被鉴定为新自身抗原。由于钙网蛋白、Grp94 和 BiP 是真核细胞 ER 驻留蛋白，我们的数据表明，针对 ER 伴侣蛋白的自身抗体的产生与最初暴露于相应的细菌伴侣蛋白无关，而 ER 伴侣蛋白可能代表真正的自身抗原。
