Department of Food & Pharmaceutical Engineering, Hoseo University, Asan, Chungnam, 336-795, South Korea.
Department of Biofood & Medical Sciences, Hanseo University, 360 Daegok-ri, Haemi-myen, Seosan, Chungnam, 356-706, South Korea.
Insect Biochem Mol Biol. 2019 Nov;114:103231. doi: 10.1016/j.ibmb.2019.103231. Epub 2019 Aug 31.
Mycoplasmas, the smallest self-replicating organisms, are unique in that they lack cell walls but possess distinctive plasma membranes containing sterol acquired from their growth environment. Although mycoplasmas are known to be successful pathogens in a wide range of animal hosts, including humans, the molecular basis for their virulence and interaction with the host immune systems remains largely unknown. This study was conducted to elucidate the biochemical relationship between mycoplasma and the insect immune system. We investigated defense reactions of Tenebrio molitor that were activated in response to infection with Mycoplasma pulmonis. The results revealed that T. molitor larvae were more resistant to mycoplasma infection than normal bacteria equipped with cell walls. Intruding M. pulmonis cells were effectively killed by toxins generated from activation of the proPO cascade in hemolymph, but not by cellular reactions or antimicrobial peptides. It was determined that these different anti-mycoplasma effects of T. molitor immune components were primarily attributable to surface molecules of M. pulmonis such as phospholipids occurring in the outer leaflet of the membrane lipid bilayer. While phosphatidylcholine, a phospholipid derived from the growth environment, contributed to the resistance of M. pulmonis against antimicrobial peptides produced by T. molitor, phosphatidylglycerol was responsible for triggering activation of the proPO cascade.
支原体是最小的自我复制生物，它们的独特之处在于缺乏细胞壁，但拥有独特的质膜，其中固醇是从生长环境中获得的。虽然支原体被认为是广泛的动物宿主（包括人类）中的成功病原体，但它们的毒力和与宿主免疫系统相互作用的分子基础在很大程度上仍然未知。本研究旨在阐明支原体与昆虫免疫系统之间的生化关系。我们研究了对感染肺炎支原体的反应而被激活的黄粉虫（Tenebrio molitor）的防御反应。结果表明，与具有细胞壁的正常细菌相比，黄粉虫幼虫对支原体感染的抵抗力更强。侵入的肺炎支原体细胞被来自血淋巴中 proPO 级联激活产生的毒素有效杀死，但不会被细胞反应或抗菌肽杀死。确定了黄粉虫免疫成分对支原体的不同抗微生物作用主要归因于质膜外层的膜脂双层中的肺炎支原体表面分子，如磷脂。虽然来自生长环境的磷脂酰胆碱有助于肺炎支原体抵抗黄粉虫产生的抗菌肽，但磷脂酰甘油负责触发 proPO 级联的激活。
