Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA.
Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA.
Nat Commun. 2024 Mar 8;15(1):2117. doi: 10.1038/s41467-024-46494-3.
Uncovering the complexity of systems in non-model organisms is critical for understanding arthropod immunology. Prior efforts have mostly focused on Dipteran insects, which only account for a subset of existing arthropod species in nature. Here we use and develop advanced techniques to describe immune cells (hemocytes) from the clinically relevant tick Ixodes scapularis at a single-cell resolution. We observe molecular alterations in hemocytes upon feeding and infection with either the Lyme disease spirochete Borrelia burgdorferi or the rickettsial agent Anaplasma phagocytophilum. We reveal hemocyte clusters exhibiting defined signatures related to immunity, metabolism, and proliferation. Depletion of phagocytic hemocytes affects hemocytin and astakine levels, two I. scapularis hemocyte markers, impacting blood-feeding, molting behavior, and bacterial acquisition. Mechanistically, astakine alters hemocyte proliferation, whereas hemocytin affects the c-Jun N-terminal kinase (JNK) signaling pathway in I. scapularis. Altogether, we discover a role for tick hemocytes in immunophysiology and provide a valuable resource for comparative biology in arthropods.
揭示非模式生物系统的复杂性对于理解节肢动物免疫学至关重要。先前的研究主要集中在双翅目昆虫上，而这些昆虫仅占自然界中现存节肢动物物种的一部分。在这里，我们使用和开发了先进的技术，以单细胞分辨率描述临床上相关的蜱虫Ixodes scapularis 的免疫细胞（血细胞）。我们观察到在喂食和感染莱姆病螺旋体Borrelia burgdorferi 或立克次体病原体 Anaplasma phagocytophilum 时血细胞发生的分子变化。我们揭示了表现出与免疫、代谢和增殖相关的明确特征的血细胞簇。吞噬性血细胞的耗竭会影响血细胞素和 astakine 的水平，这两种 I. scapularis 血细胞标志物会影响吸血、蜕皮行为和细菌获取。从机制上讲，astakine 改变了血细胞的增殖，而血细胞素影响了 I. scapularis 中的 c-Jun N-末端激酶 (JNK) 信号通路。总的来说，我们发现了蜱血细胞在免疫生理学中的作用，并为节肢动物的比较生物学提供了有价值的资源。
