Zhou Wenshuo, Tahir Faizan, Wang Joseph Che-Yen, Woodson Michael, Sherman Michael B, Karim Shahid, Neelakanta Girish, Sultana Hameeda
Department of Biological Sciences, Old Dominion University, Norfolk, VA, United States.
Center for Molecular and Cellular Biosciences, School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States.
Front Cell Dev Biol. 2020 Jul 16;8:554. doi: 10.3389/fcell.2020.00554. eCollection 2020.
Ticks secrete various anti-coagulatory, anti-vasoconstrictory, anti-inflammatory, and anti-platelet aggregation factors in their saliva at the bite site during feeding to evade host immunological surveillance and responses. For the first time, we report successful isolation of exosomes (small membrane-bound extracellular signaling vesicles) from saliva and salivary glands of partially fed or unfed ixodid ticks. Our data showed a novel role of these exosomes in the inhibition of wound healing downregulation of C-X-C motif chemokine ligand 12 (CXCL12) and upregulation of interleukin-8 (IL-8). Cryo-electron microscopy (cryo-EM) analysis revealed that tick saliva and salivary glands are composed of heterogeneous populations of exosomes with sizes ranging from 30 to 200 nm. Enriched amounts of tick CD63 ortholog protein and heat shock protein 70 (HSP70) were evident in these exosomes. Treatment of human skin keratinocytes (HaCaT cells) with exosomes derived from tick saliva/salivary glands or ISE6 cells dramatically delayed cell migration, wound healing, and repair process. Wound healing is a highly dynamic process with several individualized processes including secretion of cytokines. Cytokine array profiling followed by immunoblotting and quantitative-PCR analysis revealed that HaCaT cells treated with exosomes derived from tick saliva/salivary glands or ISE6 cells showed enhanced IL-8 levels and reduced CXCL12 loads. Inhibition of IL-8 or CXCL12 further delayed exosome-mediated cell migration, wound healing, and repair process, suggesting a skin barrier protection role for these chemokines at the tick bite site. In contrast, exogenous treatment of CXCL12 protein completely restored this delay and enhanced the repair process. Taken together, our study provides novel insights on how tick salivary exosomes secreted in saliva can delay wound healing at the bite site to facilitate successful blood feeding.
蜱虫在进食时会在叮咬部位的唾液中分泌各种抗凝、抗血管收缩、抗炎和抗血小板聚集因子，以逃避宿主的免疫监视和反应。我们首次报告成功从部分进食或未进食的硬蜱的唾液和唾液腺中分离出外泌体（小的膜结合细胞外信号囊泡）。我们的数据显示这些外泌体在抑制伤口愈合、下调C-X-C基序趋化因子配体12（CXCL12）和上调白细胞介素-8（IL-8）方面具有新的作用。冷冻电子显微镜（cryo-EM）分析表明，蜱虫唾液和唾液腺由大小在30至200纳米之间的异质外泌体群体组成。在这些外泌体中明显富含蜱虫CD63直系同源蛋白和热休克蛋白70（HSP70）。用来自蜱虫唾液/唾液腺或ISE6细胞的外泌体处理人皮肤角质形成细胞（HaCaT细胞），显著延迟了细胞迁移、伤口愈合和修复过程。伤口愈合是一个高度动态的过程，包括几个个体化过程，包括细胞因子的分泌。细胞因子阵列分析，随后进行免疫印迹和定量PCR分析，结果显示，用来自蜱虫唾液/唾液腺或ISE6细胞的外泌体处理的HaCaT细胞显示IL-8水平升高，CXCL12含量降低。抑制IL-8或CXCL12进一步延迟了外泌体介导的细胞迁移、伤口愈合和修复过程，表明这些趋化因子在蜱虫叮咬部位具有皮肤屏障保护作用。相反，外源性处理CXCL12蛋白完全恢复了这种延迟并增强了修复过程。综上所述，我们的研究为蜱虫唾液中分泌的唾液外泌体如何延迟叮咬部位的伤口愈合以促进成功吸血提供了新的见解。
