Immunoregulatory Effects Of Cefodizime On Klebsiella Pneumoniae Stimulated Neutrophil In Mice And Its Mechanism

Many antibiotics showed immunomodulatory effects in ways directly or indirectly. Indirect ways are mainly based on the antibacterial characterization of antibiotics, such as killing of bacteria, changing the intestinal flora and preventing bacteria making virulence factors to immune system. Some antibiotics have intrinsic antigenicity, such as beta-lactams and Rifampicin, and some of them may cause allergic reactions. Direct actions of antibiotics are mainly upon phagocytic functions including phagocytosis and killing, chemotaxis and lymphocyte activities. Among Cephalosporins, Cefodizime has been studied a lot. In rats and mice, Cefodizme was found to increase delayed hypersensitivity reactions, phagocytosis, lymphocytic responses to B cell mitogens and specific antigens and production of lysosomal enzymes and cytokines. However, the immunomodulating effects of CDZ and its mechanism on Klebsiella pneumoniae (Kle.p) stimulated neutrophils, the key cells in the non-specific (innate) defense in human and animal, were seldom investigated. This study was to explore the imrnunomodulating effects of CDZ on mice neutrophil and the influence of CDZ on the activity of LPS-TLR-NF-KB signal transduction pathway.METHODSMice were stimulated with Kle.p intranasally. CDZ was administrated subcutaneously at 30 mg/kg of body weight at 12-hour intervals, starting 96 hours before the inhalation of bacteria. Cytokine gene expression detected by DNA micro-array analysis after Kle.p stimulation. Effects of CDZ on the expression of TNF-a and IL-1 P of neutrophil evaluated by RT-PCR, ELISA and Western blot respectively. To elucidate the influence of CDZ on NF-KB signal transduction pathway, the expression of inhibitor of NF-KBa (I-KBa) was assayed by western blot. The transduction activity of NF-KB assayed by Electrophoretic Mobility Shift Assay (EMSA), the mRNA expression of toll like receptor 4 (TLR4), one of the most important receptor on LPS signal transduction pathway, detected by RT-PCR.RESULTSDNA micro-array analysis shows that neutrophil can express many cytokines and chemokines, such as TNF- a, IL-1 a, IL-1 P , IL-20, INF a, INF P , I K B, Fgf 16 and Fgf 17 etc. Kle. p stimulation increased cytokines expression in neutrophil, such as TNF- a , IL-1 P and IFN etc. The production and mRNA expression of TNF-a and IL-lp of neutrophils was enhanced by Kle.p stimulation in mice. CDZ treatment increased the production of cytokines and the degradation of I-KB in neutrophil during the first 3-6 hours after Kle.p stimulation. At the same time, NF-KBtransduction activity and TLR4 mRNA expression was promoted too. The production of cytokines and NF-KB DNA-binding activity were attenuated by CDZ 12-24 hours after Kle.p stimulation. The oxidative products of neutrophils in Kle.p stimulated mice was also enhanced by CDZ in the first 6 hours and attenuated 12 hours after Kle.p stimulation, which was also possibly related to the change of NF-KB activity.CONCLUSIONSCDZ shows dual immunomodulating effects on Kle.p stimulated neutrophil in mice. These effects may be due to the regulation on expression of TNF-a and IL-lp by affecting TLR4 mRNA expression and DNA binding activities of NF-KB through LPS-TLR4-NF-KB pathway.