[Therapeutic effects of granulysin/interleukin-12 recombinant M. smegmatis in a murine model of M. tuberculosis infection].
OBJECTIVE
To study the effects and mechanisms of recombinant Mycobacterium smegmatis (M. smegmatis) encoding human granulysin and murine interleukin-12 (IL-12) on murine M. tuberculosis infection.


METHODS
Balb/c mice infected with M. tuberculosis were treated with normal saline, M. smegmatis, pZM03, recombinant M. smegmatis respectively. The numbers of viable bacteria in the lung and the spleen were counted. The levels of IL-12, IgG(2a) in serum and interferon-gamma (IFN-gamma) released from spleen lymphocytes stimulated with purified protein derivative (PPD) were detected with enzyme linked immunosorbent assay (ELISA). The expression of granulysin in tissue was detected with immunohistochemistry. Lungs and spleens were prepared for pathological analysis.


RESULTS
The recombinant M. smegmatis group [(4.57 +/- 0.28) in lung, (3.47 +/- 0.25) in spleen] showed significantly reduced number of colony forming units (log CFU/g) compared with the control [(5.77 +/- 0.12) in lung, (4.66 +/- 0.18) in spleen], M. smegmatis [(5.62 +/- 0.14) in lung, (4.65 +/- 0.26) in spleen] and pZM03 [(5.04 +/- 0.22) in lung, (4.25 +/- 0.48) in spleen] group. The expression of granulysin in tissue, and increased level of IL-12 and IgG(2a) in serum were found in recombinant M. smegmatis group. IFN-gamma released from spleen lymphocytes stimulated with PPD in recombinant M. smegmatis group and pZM03 group was higher than that of other groups, but the difference between recombinant M. smegmatis group and pZM03 group was not significant. The pathological changes in lungs of the recombinant M. smegmatis group were localized, while those in the control group were extensive. Significant pathological changes were not found in the spleens of all groups.


CONCLUSIONS
The recombinant M. smegmatis had immunotherapeutic effects, which were associated with a switch to Th1 response and the antibacterial activity of granulysin.
Yang
Chun
C
Department of Immunology and Microbiology, Chongqing University of Medical Sciences, Chongqing 400016, China.
Wang
Yu-wei
YW
Yi
Zheng-jun
ZJ
He
Yong-lin
YL
Li
Na
N
Xu
Lei
L
Zhang
Li
L
Zhu
Dao-yin
DY
D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics*; D005260:Female; D006801:Humans; D018664:Interleukin-12 / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D020102:Mycobacterium smegmatis / Q000235:genetics*; D009169:Mycobacterium tuberculosis; D011994:Recombinant Proteins / Q000627:therapeutic use*; D014376:Tuberculosis / Q000628:therapy*
D000945:Antigens, Differentiation, T-Lymphocyte; C075005:GNLY protein, human; D011994:Recombinant Proteins; D018664:Interleukin-12