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[The Role of PPE25 in Mycobacterial Infections of Polymorphonuclear Neutrophils]
You-Jun Mi1, Li-Juan Liang2, Cai-Hong Ci1
1Medical College of Northwest Minzu University, Lanzhou 730000, China.
Objective:
To determine the role of PPE25 in the infection of M. smegmatis (MS) in polymorphonuclear neutrophils (PMNs).
Methods:
In MS-ppe25 group, PPE25 was expressed in non-pathogenic fast-growing M. tuberculosis (Mtb) that infected PMNs. The empty vector MS (MS-vec group) was served as control. Their colony formation was observed, including the size and growth curves of single colonies. The colony forming unit (CFU) indicated bacterial vitality. The percentage of lactate dehydrogenase (LDH) release measured PMN death. The role of PPE25 protein in MS infections was analyzed by reactive oxygen species (ROS) detected by flow cytometry, nitric oxide (NO) level detected by nitrate reductase, cytokine interleukin (IL) and tumor necrosis factor-α (TNF-α) detected by ELISA.
Results:
PPE25 protein had no effect on MS growth, colony formation and the size of single colonies. MS-infected PMN had higher percentages of CFU and LDH release 2, 6, and 12 h after infections compared with the MS-vec group (P<0.05). MS-infected PMN also had lower levels of ROS and NO levels 2 h after infections (P<0.01), consistently higher levels of TNF-α (P<0.01), and higher levels of IL-1β infusion 6 h after MS infections (P<0.01).
Conclusions:
PPE25 protein increases the survival of MS in PMN, induces cell necrosis, inhibits the expressions of ROS and NO, and changes the secretion of cytokines, which helps spread of the pathogen by evading host immunity.
Insights
The PPE25 protein enhances Mycobacterium smegmatis (MS) survival within polymorphonuclear neutrophils (PMNs). This protein promotes bacterial evasion of host immunity by inducing cell necrosis and altering immune signaling molecules.
Area of Science:
- Microbiology
- Immunology
- Bacterial Pathogenesis
Context:
- Mycobacterium smegmatis (MS) is a non-pathogenic bacterium.
- Polymorphonuclear neutrophils (PMNs) are crucial immune cells.
- The PPE25 protein's role in MS infection is not well understood.
Purpose:
- To investigate the function of the PPE25 protein during MS infection of PMNs.
- To analyze how PPE25 affects bacterial survival and host immune responses.
Summary:
- PPE25 expression in MS did not impact bacterial growth or colony formation.
- MS-infected PMNs showed increased bacterial survival (CFU) and cell death (LDH release).
- PPE25 inhibited reactive oxygen species (ROS) and nitric oxide (NO) production, while increasing TNF-α and IL-1β levels.
Impact:
- PPE25 facilitates MS survival within PMNs by evading host immune defenses.
- The protein's modulation of immune responses aids pathogen dissemination.
- Findings provide insights into bacterial immune evasion strategies.
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