Claytor Sieara C, Gummer Joel P A, Grogan Laura F, Skerratt Lee F, Webb Rebecca J, Brannelly Laura A, Berger Lee, Roberts Alexandra A
College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia.
Separation Science and Metabolomics Laboratory, Murdoch University, Perth, Australia.
Cell Microbiol. 2019 Oct;21(10):e13089. doi: 10.1111/cmi.13089. Epub 2019 Aug 1.
Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a skin disease responsible for the global decline of amphibians. Frog species and populations can vary in susceptibility, but this phenomenon remains poorly understood. Here, we investigated serotonin in the skin of infected and uninfected frogs. In more susceptible frog populations, skin serotonin rose with increasing infection intensity, but decreased in later stages of the disease. The more resistant population maintained a basal level of skin serotonin. Serotonin inhibited both Bd sporangial growth and Jurkat lymphocyte proliferation in vitro. However, serotonin accumulates in skin granular glands, and this compartmentalisation may prevent inhibition of Bd growth in vivo. We suggest that skin serotonin increases in susceptible frogs due to pathogen excretion of precursor tryptophan, but that resistant frogs are able to control the levels of serotonin. Overall, the immunosuppressive effects of serotonin may contribute to the susceptibility of frogs to chytridiomycosis.
由真菌蛙壶菌（Batrachochytrium dendrobatidis，简称Bd）引起的壶菌病是一种导致全球两栖动物数量减少的皮肤病。蛙类物种和种群的易感性可能存在差异，但这种现象仍未得到充分了解。在此，我们研究了感染和未感染青蛙皮肤中的血清素。在更易感的青蛙种群中，皮肤血清素水平随着感染强度的增加而升高，但在疾病后期会下降。抗性更强的种群则维持皮肤血清素的基础水平。血清素在体外既能抑制Bd孢子囊生长，也能抑制Jurkat淋巴细胞增殖。然而，血清素会在皮肤颗粒腺中积累，这种区室化可能会阻止其在体内抑制Bd生长。我们认为，易感青蛙皮肤中的血清素增加是由于病原体排泄前体色氨酸所致，但抗性青蛙能够控制血清素水平。总体而言，血清素的免疫抑制作用可能导致青蛙对壶菌病易感。
