Glowczyk Izabela, Wong Alicia, Potempa Barbara, Babyak Olena, Lech Maciej, Lamont Richard J, Potempa Jan, Koziel Joanna
Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian UniversityKrakow, Poland.
Center for Oral Health and Systemic Disease, University of Louisville School of Dentistry, University of LouisvilleLouisville, KY, USA.
Front Cell Infect Microbiol. 2017 Apr 27;7:140. doi: 10.3389/fcimb.2017.00140. eCollection 2017.
Gingipain cysteine proteases are considered key virulence factors of . They significantly influence antibacterial and homeostatic functions of macrophages, neutrophils, the complement system, and cytokine networks. Recent data indicate the role of in T cell differentiation; however, the involvement of gingipains in this process remains elusive. Therefore, the aim of this study was to investigate the contribution of danger signals triggered by the gingipains on the generation of Th17 cells, which play a key role in protection against bacterial diseases but may cause chronic inflammation and bone resorption. To this end we compared the effects of the wild-type strain of (W83) with its isogenic mutant devoid of gingipain activity (ΔKΔRAB), and bacterial cells pretreated with a highly-specific inhibitor of gingipains activity (KYTs). Antigen presenting cells (APCs), both professional (dendritic cells), and non-professional (gingival keratinocytes), exposed to viable bacteria expressed high amounts of cytokines (IL-6, IL-21, IL-23). These cytokines are reported to either stimulate or balance the Th17-dependent immune response. Surprisingly, cells infected with devoid of gingipain activity showed increased levels of all tested cytokines compared to bacteria with fully active enzymes. The effect was dependent on both the reduction of cytokine proteolysis and the lack of cross-talk with other bacterial virulence factors, including LPS and fimbriae that induce synthesis of cytokines. The profile of lymphocyte T differentiation from naive T cells showed enhanced generation of Th17 in response to bacteria with inactive gingipains. Moreover, we found that gingipain-dependent induction of Th17 cells was highly specific, since other T cell-subsets remained unchanged. Finally, inhibition of IL-6 signaling in dendritic cells led to a significant depletion of the Th17 population. Cumulatively, this study revealed a previously undisclosed role of gingipain activity in the process of Th17 differentiation reliant on blocking signaling through IL-6. Since inactivation of gingipains accelerates the skewing of T cells toward Th17 cells, which are detrimental in periodontitis, IL-6 signaling may serve as an attractive target for treatment of the disease.
牙龈蛋白酶半胱氨酸蛋白酶被认为是……的关键毒力因子。它们显著影响巨噬细胞、中性粒细胞、补体系统和细胞因子网络的抗菌和稳态功能。最近的数据表明……在T细胞分化中的作用；然而，牙龈蛋白酶在这一过程中的参与情况仍不明确。因此，本研究的目的是调查牙龈蛋白酶触发的危险信号对Th17细胞生成的影响，Th17细胞在抵御细菌疾病中起关键作用，但可能导致慢性炎症和骨吸收。为此，我们比较了……野生型菌株（W83）与其缺乏牙龈蛋白酶活性的同基因突变体（ΔKΔRAB），以及用牙龈蛋白酶活性高度特异性抑制剂（KYTs）预处理的细菌细胞的效果。暴露于活细菌的抗原呈递细胞（APC），包括专业的（树突状细胞）和非专业的（牙龈角质形成细胞），表达大量细胞因子（IL-6、IL-21、IL-23）。据报道，这些细胞因子要么刺激要么平衡Th17依赖性免疫反应。令人惊讶的是，与具有完全活性酶的细菌相比，感染缺乏牙龈蛋白酶活性的……的细胞显示所有测试细胞因子的水平都有所增加。这种效应既取决于细胞因子蛋白水解的减少，也取决于与其他细菌毒力因子（包括诱导细胞因子合成的LPS和菌毛）缺乏相互作用。从初始T细胞分化而来的淋巴细胞T谱显示，对缺乏活性牙龈蛋白酶的细菌，Th17的生成增强。此外，我们发现牙龈蛋白酶依赖性诱导Th17细胞具有高度特异性，因为其他T细胞亚群保持不变。最后，抑制树突状细胞中的IL-6信号导致Th17群体显著减少。累积来看，本研究揭示了牙龈蛋白酶活性在依赖于阻断IL-6信号的Th17分化过程中以前未被揭示的作用。由于牙龈蛋白酶的失活加速了T细胞向Th17细胞的倾斜，而Th17细胞在牙周炎中是有害的，IL-6信号可能是治疗该疾病的一个有吸引力的靶点。
