5-羟基-四氢萘酮抑制鼠伤寒沙门菌入侵及体内保护效果研究OA

To investigate the inhibitory effects and underlying mechanisms of 5-hydroxy-1-tetralone on Salmonella pathogenicity island-1(SPI-1)and its type III secretion system(T3SS-1),this study systematically evaluated the anti-virulence activity of 5-hydroxy-1-tetralone both in vitro and in vivo.The experimental approaches included pharmacokinetic and toxicity prediction,growth curve analysis,cell invasion assays,immunofluorescence imaging,detection of effector protein secretion and expression,assessment of bacterial motility,observation of host cell membrane ruffling at invasion sites,real-time fluorescence quantitative polymerase chain reaction(qPCR),cytotoxicity and cell protection assays,together with a mouse infection model.The results indicated that 5-hydroxy-1-tetralone exhibited favorable drug-likeness properties.Compared with the Control group(0 µg/mL),64 µg/mL 5-hydroxy-1-tetralone had no significant effect on the growth rate of S.typhimurium(P>0.05).Treatment with 16 and 4 µg/mL 5-hydroxy-1-tetralone significantly inhibited bacterial invasion into human cervical carcinoma HeLa cells(P<0.01)and human colon carcinoma Caco-2 cells(P<0.05),respectively.At 8 µg/mL,5-hydroxy-1-tetralone significantly suppressed the secretion of the effector proteins SipA and SipB in S.typhimurium(P<0.05).Moreover,16 and 32 µg/mL 5-hydroxy-1-tetralone significantly reduced the relative expression levels of SipA and HilA proteins,respectively(P<0.05).Treatment with 64 and 32 µg/mL 5-hydroxy-1-tetralone significantly inhibited swimming(P<0.05)and swarming motility of S.typhimurium(P<0.01).In addition,32 µg/mL 5-hydroxy-1-tetralone markedly reduced the ability of S.typhimurium to induce host cell membrane ruffling(P<0.001)and significantly downregulated the transcription of SPI-1-associated transcriptional regulators and downstream genes(P<0.01 or P<0.001).Furthermore,64 µg/mL 5-hydroxy-1-tetralone showed no obvious cytotoxicity to HeLa cells(P>0.05),while 32 µg/mL 5-hydroxy-1-tetralone significantly increased the protection rate of infected cells(P<0.001).In the mouse infection model,bacterial loads in the cecum,liver,and spleen were significantly reduced in the 5-hydroxy-1-tetralone treatment group compared with the Model group(P<0.05 or P<0.01),accompanied by marked improvement in inflammatory pathological damage.These findings demonstrate that 5-hydroxy-1-tetralone acts as an efficient inhibitor of the S.typhimurium T3SS-1 and represents a promising lead compound with a relatively well-defined mechanism for the development of anti-virulence therapeutics targeting S.typhimurium.