Details

Autor(en) / Beteiligte

• Li, Jun-ming
• Li, Na
• Zhu, Dao-yin
• Wan, La-gen
• He, Yong-lin
• Yang, Chun

Titel

Isocitrate lyase from Mycobacterium tuberculosis promotes survival of Mycobacterium smegmatis within macrophage by suppressing cell apoptosis

Ist Teil von

• Chinese medical journal, 2008-06, Vol.121 (12), p.1114-1119

Ort / Verlag

China: Department of Clinical Laboratory,First Affiliated Hospital of Nanchang University,Nanchang 330006,China%Department of Immunology,Chongqing University of Medical Sciences,Chongqing 400016,China

Erscheinungsjahr

2008

Quelle

MEDLINE

Beschreibungen/Notizen

• Background Isocitrate lyase （ICL） was previously demonstrated to play a pivotal role in the intracellular metabolism of Mycobacterium tuberculosis （MTB）. Presently several lines of evidence suggest that ICL from MTB （MTB-ICL） may play some roles in the interaction between MTB and host macrophage. However, there has been no research on the interaction between MTB-ICL and host macrophage. Methods MTB-icl and M. smegmatis （MS）-icl genes were amplified by polymerase chain reaction （PCR） and cloned into the E. coli-mycobacterium shuttle plasmid pUV15 to obtain recombinant shuttle plasmids pMTB-icl and pMS-icl. Following transformation into MS by electroporation, the expression of pMTB-icl and pMS-icl was verified by reverse transcriptase （RT）-PCR. The expression of recombinant plasmids derived from pUV15 when rMS was phagocytized by macrophage was also verified via fluorescence microscope. Ms 1-2c, rMS-pUV15, rMS-pMS-icl and rMS-pMTB-icl were used to infect RAW264.7 cells and the survival of intracellular MS was monitored by bacterial culture at 0, 24 and 48 hours after infection. The culture supernatants from macrophage infected by Ms 1-2c, rMS-pUV15, rMS-pMS-icl and rMS-pMTB-icl were collected and the interferon （IFN）-y and nitric oxide （NO） concentrations were measured by ELISA or by Griess assay, respectively. The apoptosis of macrophage was assayed by the in situ TUNEL technique. Results RT-PCR showed that both pMTB-icl and pMS-icl could be expressed in MS. Fluorescence microscopic observation showed that recombinant plasmids derived from pUV15 （pUV15-iG） could also be expressed in MS when MS were phagocytized by macrophage. Bacterial culture data demonstrated that rMS-pMTB-icl exhibited significantly increased intracellular survival in the murine macrophage cell line RAW264.7 compared with Ms 1-2c, rMS-pUV15 and rMS-pMS-icl. This increased intracellular survival was not accompanied by the upregulation of IFN-y and NO in host macrophage. But a lower apoptosis rate of macrophages infected with rMS-pMTB-icl was observed when compared with macrophages infected with other strains of MS. Conclusions MTB-ICL could promote the intracellular survival of MS. Suppressing the apoptosis of host macrophage may be one of the important mechanisms involved in this increased intracellular survival.