Amelogenin Downregulates Interferon Gamma-Induced Major Histocompatibility Complex Class II Expression Through Suppression of Euchromatin Formation in the Class II Transactivator Promoter IV Region in Macrophages
Amelogenin Downregulates Interferon Gamma-Induced Major Histocompatibility Complex Class II Expression Through Suppression of Euchromatin Formation in the Class II Transactivator Promoter IV Region in Macrophages
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DOI：
10.3389/fimmu.2020.00709
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发表时间：
2020-04
影响因子：
7.3
通讯作者：
Karen Yotsumoto;T. Sanui;Urara Tanaka;Hiroaki Yamato;Rehab Alshargabi;T. Shinjo;Yukihiro Nakao;Yukari Watanabe;Chikako Hayashi;Takaharu Taketomi;T. Fukuda;F. Nishimura
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作者：
Karen Yotsumoto;T. Sanui;Urara Tanaka;Hiroaki Yamato;Rehab Alshargabi;T. Shinjo;Yukihiro Nakao;Yukari Watanabe;Chikako Hayashi;Takaharu Taketomi;T. Fukuda;F. Nishimura
牙釉质基质衍生物（EMD）为基础的牙周组织再生治疗是众所周知的，以促进愈合与最小的炎症反应后，牙周手术，即。例如，它促进伤口愈合，减轻疼痛和肿胀。据报道，巨噬细胞刺激釉原蛋白，EMD的主要成分，产生各种抗炎细胞因子和生长因子。我们以前发现，刺激单核细胞与鼠重组M180（rM 180）釉原蛋白抑制主要组织相容性复合物II类（MHC II）基因表达，使用微阵列分析。然而，这一过程的详细分子机制仍不清楚。在本研究中，我们证明了rM 180釉原蛋白选择性下调干扰素γ（IFNγ）诱导的巨噬细胞表面MHC II分子的表达，并且这种由rM 180介导的机制似乎在物种间广泛保守。rM 180在刺激后15 min即在巨噬细胞核内聚集，并抑制IFNγ对MHC Ⅱ类分子转录的调控因子CIITA的表达。此外，rM 180预处理后巨噬细胞MHC Ⅱ类分子表达降低，抑制了T细胞活化标志物CD 25和CD 69的表达，抑制了T细胞增殖能力，抑制了同种异体CD 4 + T淋巴细胞产生IL-2的能力。染色质免疫沉淀试验表明，IFNγ刺激增加了组蛋白H3赖氨酸27的乙酰化，这对转化为常染色质很重要，以及CIITA启动子IV（p-IV）区域中组蛋白H3赖氨酸4水平的三甲基化，但在rM 180处理后用IFNγ刺激的组中，两者都受到抑制。总之，本研究表明，釉原蛋白通过改变染色质结构和抑制CIITA p-IV转录活性来抑制MHC II表达，并减弱随后的T细胞活化。临床观察到的加速牙周手术后的伤口愈合的釉原蛋白可能部分介导的机制阐明在这项研究中。此外，使用重组釉原蛋白是安全的，因为它是生物衍生蛋白。因此，釉原蛋白也可能在未来用作免疫抑制剂，对器官移植或MHC II相关的自身免疫性疾病如I型糖尿病、多发性硬化症和类风湿性关节炎等具有最小的副作用。
Enamel matrix derivatives (EMDs)-based periodontal tissue regenerative therapy is known to promote healing with minimal inflammatory response after periodontal surgery, i. e., it promotes wound healing with reduced pain and swelling. It has also been reported that macrophages stimulated with amelogenin, a major component of EMD, produce various anti-inflammatory cytokines and growth factors. We previously found that stimulation of monocytes with murine recombinant M180 (rM180) amelogenin suppresses major histocompatibility complex class II (MHC II) gene expression using microarray analysis. However, the detailed molecular mechanisms for this process remain unclear. In the present study, we demonstrated that rM180 amelogenin selectively downmodulates the interferon gamma (IFNγ)-induced cell surface expression of MHC II molecules in macrophages and this mechanism mediated by rM180 appeared to be widely conserved across species. Furthermore, rM180 accumulated in the nucleus of macrophages at 15 min after stimulation and inhibited the protein expression of class II transactivator (CIITA) which controls the transcription of MHC II by IFNγ. In addition, reduced MHC II expression on macrophages pretreated with rM180 impaired the expression of T cell activation markers CD25 and CD69, T cell proliferation ability, and IL-2 production by allogenic CD4+ T lymphocytes in mixed lymphocyte reaction assay. The chromatin immunoprecipitation assay showed that IFNγ stimulation increased the acetylation of histone H3 lysine 27, which is important for conversion to euchromatin, as well as the trimethylation of histone H3 lysine 4 levels in the CIITA promoter IV (p-IV) region, but both were suppressed in the group stimulated with IFNγ after rM180 treatment. In conclusion, the present study shows that amelogenin suppresses MHC II expression by altering chromatin structure and inhibiting CIITA p-IV transcription activity, and attenuates subsequent T cell activation. Clinically observed acceleration of wound healing after periodontal surgery by amelogenin may be partially mediated by the mechanism elucidated in this study. In addition, the use of recombinant amelogenin is safe because it is biologically derived protein. Therefore, amelogenin may also be used in future as an immunosuppressant with minimal side effects for organ transplantation or MHC II-linked autoimmune diseases such as type I diabetes, multiple sclerosis, and rheumatoid arthritis, among others.