ABSTRACT
We investigated the effects of IFN-γ on Chlamydia psittaci (Cps) infection.HeLa cells were treated with different concentrations of recombinant human IFN-γ (5 ng/mL,25 ng/mL,50 ng/mL) after infecting with C.psittaci 6BC,then the number and morphology of C.psittaci inclusion bodies were examined after 48 hours.C57BL/6J mice were intranasally infected with 2 × 106 IFUs C.psittaci 6BC,and intraperitoneally administrated with 10 μg recombinant murine interferon-γ 24 hours prior or post infection,then body weight,activity and survival rate were recorded.The histopathology of mice livers and lungs was analyzed by HE staining on day 5 or day10 post infection.And the chlamydial inclusion bodies were titrated in the lung homogenates of mice sacrificed on day 5 after infection.The inclusion body numbers of recombinant human IFN-γ treated groups (by 5ng/mL,25ng/mL,50ng/mL) were significantly less than that in the control group (23.8±5.1)× 106,(10± 3.58) × 106,(8.0±2.22) × 106,(43.3±11.05)× 106,respectively).And the morphology of inclusion bodies in IFN-γ treated HeLa cells was irregular and much smaller.We also found that IFN-γ could significantly improve the survival rate,reduce acute clinical manifestations and pathological injurery of lung and liver in C.psittaci respiratory tract infected mice model.So we summarized that IFN-γ can mediate strong immunological protection during acute C.psittaci early infection.
ABSTRACT
Objective To express and purify Chlamydial protease-like activity factor(CPAF)from Chlamydophila pneumoniae,for investigating the effect of its recombinant protein GST-CPAF in inducing human monocytic cells to secrete proinflammatory cytokines and cell apoptosis.Methods The recom-bination expression plasmid pGEX6p-2/CPAF from Chlamydophila pneumoniae was transformed into E.coli.The recombination GST-CPAF was expressed after induction by IPTG,and purified by a agarose gel FF.Human monocytic cells were stimulated by the GST-CPAF to test the production of tumor necrosis factor a(TNF-α)and interleukin-6(IL- 6)by ELISA.Inhibition of cells proliferation with GST-CPAF was assessed by MTT.The THP-1 cell apoptosis stimulated by GST-CPAF was detected by Hoechst33258 fluorescence staining,DNA fragmentation analysis and cell apeptosis was detested bv Annexin V-FITC-propidiuum iodide (PI)staining.Results The recombination protein GST-CPAF was successfully expressed with high level in E.coli,and stimulated human monocytic cells to produce proinflammatory cytokines including TNF-α and IL-6 in a dose-and time-dependent manner.Otherwise,the GST-CPAF inhibited the growth of human monocytic cell in a dose-dependent manner.Apoptosis with nuclear chromatin fragmentation as well as cell shrinkage was observed by fluorescent staining and microscopy,DNA ladders in apoptosis cells were detected after 24 h with the GST-CPAF.Conclusion The GST-CPAF from Chlamydophila pneumoniae can induce the secretion of proinflammatory cytokines TNF-α and IL-6 by human monocytic cells,and inhibited the proliferation of THP-1 cell and apoptosis in vitro.