Data of sadA role in Staph pathogenicity

Aromatic amino acid decarboxylase is prevalent in bacteria associated with food fermentation and human commensal. This enzyme, called SadA, is reported to be found in various staphylococcal species and might contribute to colonization and host-bacteria interactions. However, the role of SadA in staphylococcal pathogenicity related to infection is understudied. This study aims to evaluate the role of sadA in the pathogenicity of Staphylococcus pseudintermedius ED99 and Staphylococcus aureus USA300 LAC using invertebrate and mammalian infection models. We performed a Galleria mellonella survival assay, a mouse infection model, and analysis of trace amine levels using high-performance liquid chromatography (HPLC). In addition, cytokine production in human monocyte cells (Monomac-6) exposed to trace amines was also measured. The results showed that sadA expression increased the virulence of S. pseudintermedius ED99 on G. mellonella when supplemented with aromatic amino acids, but in a mouse model, no significant differences were found in infection rates, bacterial burdens, or trace amine production between strains with and without sadA. Moreover, tryptamine only induced IL-10 production in Monomac-6 cells at high concentration (50 μg/ml). In conclusion, sadA does not play a significant role in staphylococcal pathogenicity in mammalian models due to substrate limitations in the host.芳香族氨基酸脱羧酶（aromatic amino acid decarboxylase）广泛分布于与食品发酵相关的细菌及人体共生菌中。该酶被命名为SadA，据报道可在多种葡萄球菌属物种中发现，可能参与细菌定植与宿主-细菌互作过程。然而，目前对于SadA在葡萄球菌感染相关致病性中的作用研究尚显不足。本研究旨在借助无脊椎动物与哺乳动物感染模型，评估sadA基因在假中间葡萄球菌（Staphylococcus pseudintermedius）ED99及金黄色葡萄球菌（Staphylococcus aureus）USA300 LAC致病性中的作用。我们开展了大蜡螟（Galleria mellonella）存活试验、小鼠感染模型实验，并采用高效液相色谱法（HPLC）分析痕胺水平。此外，我们还检测了暴露于痕胺的人单核细胞系（Monomac-6）的细胞因子产生情况。结果显示，在添加芳香族氨基酸的条件下，sadA表达可增强假中间葡萄球菌ED99对大蜡螟的毒力；但在小鼠感染模型中，携带与不携带sadA的菌株在感染率、细菌载量及痕胺生成方面均无显著差异。此外，仅在高浓度（50 μg/ml）条件下，色胺才可诱导人单核细胞系Monomac-6产生IL-10（白细胞介素10）。综上，由于宿主体内存在底物限制，sadA在哺乳动物感染模型中对葡萄球菌致病性无显著影响。