Background: Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important infectious disease pathogen. Recently, there are increasing researches about the relationship between apoptosis and glycolysis of cells. Previous studies have identified that S. Typhimurium secreted effector K3 (SseK3) is a novel translated and secreted protein. However, there is no study about the role of sseK3 in the relationship between apoptosis and glycolysis of cells infected with S. Typhimurium. It is unclear whether this protein exerts a significant role in the progress of apoptosis and glycolysis in macrophages. Results: The S. Typhimurium SL1344 wild-type (WT) group, ΔsseK3 mutant group and sseK3-complemented group were used to infect macrophages and the effects of sseK3 on apoptosis and glycolysis of macrophages were investigated. The adherence and invasion of ΔsseK3 mutant group for macrophages were similar to WT group and sseK3-complemented group, indicating that SseK3 did not play an important role in the adherence and invasion of S. Typhimurium for macrophages. However, the apoptosis percentage of the ΔsseK3 mutant group was much lower than WT group and sseK3-complemented group using flow cytometry. The caspase-3, caspase-8 and caspase-9 enzyme activity of the ΔsseK3 mutant group were decreased significantly compared with WT group and sseK3-complemented group, which suggested that sseK3 could improve the activities of caspase-3, caspase-8 and caspase-9 enzyme. We also found that the pyruvic acid level did not significantly change among ΔsseK3 mutant group, WT group and sseK3-complemented group, but the lactic acid level of ΔsseK3 mutant group was much lower than WT group and sseK3-complemented group. The ATP level of ΔsseK3 mutant group was remarkably higher than WT group and sseK3-complemented group. These indicated that the sseK3 enhanced the level of glycolysis of macrophages infected by S. Typhimurium. Conclusions: Our data showed that the sseK3 of S. Typhimurium involved in promoting macrophages apoptosis and influencing glycolysis levels of macrophages. These results may give a better clue about the relationship between apoptosis and glycolysis in macrophages induced by S. Typhimurium sseK3.

Background: Salmonella enterica serovar Typhimurium ( S. Typhimurium) is an important infectious disease pathogen that can survive and replicate in macrophages. Glycolysis is essential for immune responses against S. Typhimurium infection in macrophages, and is also associated with apoptosis. S. Typhimurium secreted effector K3 (SseK3) was recently identified as a novel translated and secreted protein. However, there is no study about the role of sseK3 in the relationship between apoptosis and glycolysis in cells infected with S. Typhimurium. It is unclear whether this protein exerts a significant role in the progress of apoptosis and glycolysis in S. Typhimurium-infected macrophages. Results: Macrophages were infected with S. Typhimurium SL1344 wild-type (WT), Δ sseK3 mutant or sseK3 -complemented strain, and the effects of sseK3 on apoptosis and glycolysis were determined. The adherence and invasion in the Δ sseK3 mutant group were similar to that in the WT and sseK3 -complemented groups, indicating that SseK3 was not essential for the adherence and invasion of S. Typhimurium in macrophages. However, the percentage of apoptosis in the Δ sseK3 mutant group was much lower than that in the WT and sseK3 -complemented groups. Caspase-3, caspase-8, and caspase-9 enzyme activity in the Δ sseK3 mutant group were significantly lower than in the WT group and sseK3 -complemented groups, indicating that sseK3 could improve the caspase-3, caspase-8, and caspase-9 enzyme activity. We also found that there were no significant differences in pyruvic acid levels between the three groups, but the lactic acid level in the Δ sseK3 mutant group was much lower than that in the WT and sseK3 -complemented groups. The ATP levels in the Δ sseK3 mutant group were remarkably higher than those in the WT and sseK3 -complemented groups. These indicated that the sseK3 enhanced the level of glycolysis in macrophages infected by S. Typhimurium. Conclusions: S. Typhimurium sseK3 is likely involved in promoting macrophage apoptosis and modulating glycolysis in macrophages. Our results could improve our understanding of the relationship between apoptosis and glycolysis in macrophages induced by S. Typhimurium sseK3 .

Background: Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important infectious disease pathogen. Previous studies have identified that S. Typhimurium secreted effector K3 (SseK3) is a novel translated and secreted protein, but it is unclear whether this protein exerts a significant role in the progress of apoptosis and glycolysis in macrophages. Results: The S. Typhimurium SL1344 wild-type (WT) group, ΔsseK3 mutant group and sseK3-complemented group were used to infect macrophages and the effects of sseK3 on apoptosis and glycolysis of macrophages were investigated. The adherence and invasion of ΔsseK3 mutant group for macrophages were similar to WT group and sseK3-complemented group, indicating that SseK3 did not play an important role in the adherence and invasion of S. Typhimurium for macrophages. However, the apoptosis percentage of the ΔsseK3 mutant group was much lower than WT group and sseK3-complemented group using flow cytometry. The caspase-3, caspase-8 and caspase-9 enzyme activity of the ΔsseK3 mutant group were decreased significantly compared with WT group and sseK3-complemented group, which suggested that sseK3 could improve the activities of caspase-3, caspase-8 and caspase-9 enzyme. We also found that the pyruvic acid level did not significantly change among ΔsseK3 mutant group, WT group and sseK3-complemented group, but the lactic acid level of ΔsseK3 mutant group was much lower than WT group and sseK3-complemented group. The ATP level of ΔsseK3 mutant group was remarkably higher than WT group and sseK3-complemented group. These indicated that the sseK3 enhanced the level of glycolysis of macrophages infected by S. Typhimurium. Conclusions: Our data showed that the sseK3 of S. Typhimurium can promote macrophages apoptosis and influence glycolysis levels of macrophages. These results may give a better clue about the relationship between apoptosis and glycolysis in macrophages induced by S. Typhimurium sseK3. Keywords: S. Typhimurium, sseK3, macrophages apoptosis, glycolysis

Background: Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important infectious disease pathogen that can survive and replicate in macrophages. Glycolysis is essential for immune responses against S. Typhimurium infection in macrophages, and is also associated with apoptosis. S. Typhimurium secreted effector K3 (SseK3) was recently identified as a novel translated and secreted protein. However, there is no study about the role of sseK3 in the relationship between apoptosis and glycolysis in cells infected with S. Typhimurium. It is unclear whether this protein exerts a significant role in the progress of apoptosis and glycolysis in S. Typhimurium-infected macrophages.Results: Macrophages were infected with S. Typhimurium SL1344 wild-type (WT), ΔsseK3 mutant or sseK3-complemented strain, and the effects of sseK3 on apoptosis and glycolysis were determined. The adherence and invasion in the ΔsseK3 mutant group were similar to that in the WT and sseK3-complemented groups, indicating that SseK3 was not essential for the adherence and invasion of S. Typhimurium in macrophages. However, the percentage of apoptosis in the ΔsseK3 mutant group was much lower than that in the WT and sseK3-complemented groups. Caspase-3, caspase-8, and caspase-9 enzyme activity in the ΔsseK3 mutant group were significantly lower than in the WT group and sseK3-complemented groups, indicating that sseK3 could improve the caspase-3, caspase-8, and caspase-9 enzyme activity. We also found that there were no significant differences in pyruvic acid levels between the three groups, but the lactic acid level in the ΔsseK3 mutant group was much lower than that in the WT and sseK3-complemented groups. The ATP levels in the ΔsseK3 mutant group were remarkably higher than those in the WT and sseK3-complemented groups. These indicated that the sseK3 enhanced the level of glycolysis in macrophages infected by S. Typhimurium.Conclusions: S. Typhimurium sseK3 is likely involved in promoting macrophage apoptosis and modulating glycolysis in macrophages. Our results could improve our understanding of the relationship between apoptosis and glycolysis in macrophages induced by S. Typhimurium sseK3.