[The relationship between cyclic adenosine monophosphate response element-binding protein and interferon-γ gene promoter in tuberculosis patients].

OBJECTIVE: To study the relationship between cAMP response element binding protein (CREB) and the interferon-γ (IFN-γ) proximal promoter in patients with tuberculosis. METHODS: CD3(+) T cells were isolated from 25 pulmonary tuberculosis patients, who had been treated in Beijing Chest Hospital from January to December 2007, and 18 PPD-positive healthy donors. After extraction of nuclear proteins, electrophoretic mobility shift assay (EMSA) was performed to determine nuclear protein binding to the IFN-γ proximal promoter in vitro, and the specificity of binding complex was tested by competitive EMSA. Chromatin immunoprecipitation (ChIP) with anti-CREB Ab was used to determine whether CREB binded to the IFN-γ proximal promoter in vivo in live T cells exposed to microbial Ags. Western blotting with anti-CREB Ab was performed to compare the expression level of CREB in tuberculosis patients and PPD-positive healthy donors. Western blotting with Abs specific for serine 133-phosphorylated CREB was performed to determine whether M.tuberculosis Ags elicited phosphorylation of CREB. RESULTS: The results of EMSA showed a low-mobility complex binding to the IFN-γ promoter, and the binding pattern observed was similar for T cells from all 18 PPD-positive healthy donors. However, for T cells from 18 of 25 tuberculosis patients, the low-mobility complex was absent. The results of competitive EMSA showed that these nuclear proteins specifically bound to the IFN-γ promoter region and contained CREB. The results of ChIP showed a 204 bp band yielded in CD3(+) T cells from 10 PPD-positive healthy donors, but 12 tuberculosis patients didn't yield the band. CREB expression markedly decreased in tuberculosis patients compared with healthy donors detected by Western blotting. Furthermore, M. tuberculosis Ags also elicited phosphorylation of CREB in CD3(+) T cells from PPD-positive healthy donors, but not in CD3(+) T cells from tuberculosis patients. CONCLUSIONS: CREB protein binding to IFN-γ proximal promoter was reduced in tuberculosis patients compared with healthy donors. Tuberculosis patients had diminished CREB protein levels, and reduced ability of binding to the IFN-γ promoter.

[Prokaryotic expression, purification, and immunogenicity analysis of Mycobacterium tuberculosis specific excretive proteins].

OBJECTIVE: To obtain the recombinant rv1837c and rv3803c of Mycobacterium tuberculosis using gene engineering technology and explore their prokaryotic expression, purification, and immunogenicity. METHODS: The Mycobacterium tuberculosis rv1837c and rv3803c genes were amplified by polymerase chain reaction, and then cloned into the vector pTA2, followed by the subclone into the expression vector pET30a (+). The resulting plasmids, named pET30a (+): rv1837c and pET30a (+): rv3803c, encode recombinant protein containing a hexa-histidine tag on its N-terminus. pET30a (+): rv1837c and pET30a (+): rv3803c were introduced into E. coli BL21 (DE3) by transformation respectively, and the recombinant gene was induced with 0.4 mmol/L isopropyl-D-thiogalactopyranoside. The expressed products were identified by Western blot with hexa-histidine tag antibody and serum from tuberculotic patients. The histidine tagged protein was purified by nickel nitrilotriacetic acid His-Bind resin. Rabbits were immunized with purified recombinant Rv1837c and Rv3803c proteins. Then the purified recombinant Rv1837c and Rv3803c proteins were used to detect antibody in rabbit serum, which had been immunized by Western blot. RESULTS: After transformation of the E. coli and induction with 0.4 mmol/L of isopropyl-D-thiogalactopyranoside, recombinant target proteins Rv1837c (relative molecular mass: 92000) and Rv3803c (relative molecular mass: 38 000) were expressed in pET30a (+): rv1837c and pET30a (+): rv3803c system. The expressed protein existed in cytoplasm in an unsoluble form and amounted to 30% and 50% of the total proteins of E. coli. The purity of the purified protein reached 90%. The immunogenicity of the recombinant proteins Rv1837c and Rv3803c was strong, as identified by Western blot. CONCLUSION: The prokaryotic expression recombinant plasmids pET30a (+): rv1837c and pET30a (+): rv3803c was successfully constructed and the recombinant proteins Rv1837c and Rv3803c were obtained, which laid a basis for the optimized diagnosis of active tuberculosis.

Carrier screening for alpha- and beta-thalassemia in pregnancy: the results of an 11-year prospective program in Guangzhou Maternal and Neonatal hospital.

OBJECTIVES: To evaluate the first prospective screening program in China for control of alpha and beta-thalassemia in the population of pregnant couples. METHODS: During the period between January 1993 and December 2003, a hospital-based preventive program was conducted at the biggest birth center in Guangzhou, with 1/17 of all deliveries in this city referred annually by use of conventional heterozygote screening strategy in combination with the system of regular healthcare examination in pregnancy. RESULTS: The screened records included 49 221 pregnant women, and 4503 husbands of the pregnant women showed positive on the screening test. Of the at-risk couples, there were 198 for alpha-thal (4.4%) and 83 for beta-thal (1.8%), respectively. Genetic counseling was offered to all at-risk couples and a successful prenatal diagnosis was performed for 269 out of 281 (95.7%) for alpha- or beta-thal major, with the remaining 12 couples refusing to accept prenatal diagnosis. Out of 187 pregnancies at risk for homozygous alpha0-thal and 82 at risk for beta-thal major, 51 hydrops fetalis with Hb Bart's and 18 beta-thal major were identified. All pregnancies with affected fetuses were voluntarily terminated, leading to a marked reduction of severe alpha- and beta-thal births at this hospital since the program has been launched. CONCLUSIONS: Our hospital-based program proved to be highly effective in reducing severe thals in pregnant populations.