Immunotherapeutic Effects of Different Doses of Mycobacterium tuberculosis ag85a/b DNA Vaccine Delivered by Electroporation.

Background: Tuberculosis (TB) is a major global public health problem. New treatment methods on TB are urgently demanded. Methods: Ninety-six female BALB/c mice were challenged with 2×104 colony-forming units (CFUs) of MTB H37Rv through tail vein injection, then was treated with 10µg, 50µg, 100µg, and 200µg of Mycobacterium tuberculosis (MTB) ag85a/b chimeric DNA vaccine delivered by intramuscular injection (IM) and electroporation (EP), respectively. The immunotherapeutic effects were evaluated immunologically, bacteriologically, and pathologically. Results: Compared with the phosphate-buffered saline (PBS) group, the CD4+IFN-γ+ T cells% in whole blood from 200 µg DNA IM group and four DNA EP groups increased significantly (P<0.05), CD8+IFN-γ+ T cells% (in 200 µg DNA EP group), CD4+IL-4+ T cells% (50 µg DNA IM group) and CD8+IL-4+ T cells% (50 µg and 100 µg DNA IM group, 100 µg and 200 µg DNA EP group) increased significantly only in a few DNA groups (P< 0.05). The CD4+CD25+ Treg cells% decreased significantly in all DNA vaccine groups (P<0.01). Except for the 10 µg DNA IM group, the lung and spleen colony-forming units (CFUs) of the other seven DNA immunization groups decreased significantly (P<0.001, P<0.01), especially the 100 µg DNA IM group and 50 µg DNA EP group significantly reduced the pulmonary bacterial loads and lung lesions than the other DNA groups. Conclusions: An MTB ag85a/b chimeric DNA vaccine could induce Th1-type cellular immune reactions. DNA immunization by EP could improve the immunogenicity of the low-dose DNA vaccine, reduce DNA dose, and produce good immunotherapeutic effects on the mouse TB model, to provide the basis for the future human clinical trial of MTB ag85a/b chimeric DNA vaccine.

Chinese Traditional Medicine NiuBeiXiaoHe (NBXH) Extracts Have the Function of Antituberculosis and Immune Recovery in BALB/c Mice.

BACKGROUND: The Traditional Chinese Medicine NiuBeiXiaoHe (NBXH) is a valid antituberculosis (TB) prescription from the experience of clinical practice. However, the mechanism of NBXH extracts' immunotherapy has been poorly understood. Herein, the immunotherapeutic efficacy and the differentially expressed (DE) genes of NBXH extracts were evaluated and identified in BALB/c mice. METHODS: The total RNA was extracted from peripheral blood mononuclear cells, and the DE genes were identified by gene chip. The enrichment and signaling pathway analyses were performed using Gene Ontology (GO) and KEGG database. RESULTS: It was shown that the treatment of NBXH extracts (high dose) significantly reduced mycobacteria loads and histopathological lesions in mice infected by Mycobacterium tuberculosis and resulted in 3,454 DE upregulated genes and 3,594 downregulated DE genes. Furthermore, NBXH extracts killed mycobacteria by inhibiting the supply of necessary ingredients for their growth and proliferation. They restored the disordered immune microenvironments by up- or downregulating immune and inflammation-related pathways. CONCLUSIONS: Taken together, NBXH extracts not only efficiently decreased the mycobacteria loads but also balanced the immune disorders in mice. These new findings provide a fresh perspective for elucidating the immunotherapeutic mechanism of NBXH extracts and pointed out the direction for improving the treatment efficacy of NBXH extracts.

Effects of Mycobacterium vaccae vaccine in a mouse model of tuberculosis: protective action and differentially expressed genes.

BACKGROUND: Tuberculosis is a leading cause of death worldwide. BCG is an effective vaccine, but not widely used in many parts of the world due to a variety of issues. Mycobacterium vaccae (M. vaccae) is another vaccine used in human subjects to prevent tuberculosis. In the current study, we investigated the potential mechanisms of M. vaccae vaccination by determining differentially expressed genes in mice infected with M. tuberculosis before and after M. vaccae vaccination. METHODS: Three days after exposure to M. tuberculosis H37Rv strain (5 × 105 CFU), adult BALB/c mice randomly received either M. vaccae vaccine (22.5 µg) or vehicle via intramuscular injection (n = 8). Booster immunization was conducted 14 and 28 days after the primary immunization. Differentially expressed genes were identified by microarray followed by standard bioinformatics analysis. RESULTS: M. vaccae vaccination provided protection against M. tuberculosis infection (most prominent in the lungs). We identified 2326 upregulated and 2221 downregulated genes in vaccinated mice. These changes could be mapped to a total of 123 signaling pathways (68 upregulated and 55 downregulated). Further analysis pinpointed to the MyD88-dependent TLR signaling pathway and PI3K-Akt signaling pathway as most likely to be functional. CONCLUSIONS: M. vaccae vaccine provided good protection in mice against M. tuberculosis infection, via a highly complex set of molecular changes. Our findings may provide clue to guide development of more effective vaccine against tuberculosis.

Immunogenicity and Therapeutic Effects of Latency-Associated Genes in a Mycobacterium Tuberculosis Reactivation Mouse Model.

In this study, the Mycobacterium tuberculosis (MTB) latency-associated antigens Rv2660c, Rv1733c, Rv1813c, Rv2628, Rv2029c, and Rv2659c were compared regarding their immunogenicity and potential therapeutic effects in an MTB reactivation mouse model. Normal mice or MTB reactivation mice were immunized intramuscularly three times at 2-week intervals with saline, plasmid vector pVAX1, Mycobacterium vaccae vaccine (a commercial inactivated vaccine), rv1813c DNA, rv2628 DNA, rv2029c DNA, rv2659c DNA, rv1733c DNA, or rv2660c DNA. The normal mice immunized with rv2628 DNA or rv2659c DNA had low numbers of Th1 cells and a lower ratio of Th1:Th2 immune cells in whole blood (p < 0.05). Compared to the saline group, Tc1 cells in the rv2029c DNA group and Tc1:Tc2 cell ratio in the rv1813c DNA, rv2628 DNA, and rv2029c DNA groups were significantly decreased (p < 0.05). The proportion of Foxp3+CD4+ T cells in the rv2628 DNA and rv2659c DNA groups and the proportion of CD4+CD25+ T cells in the rv2029c DNA group were significantly increased (p < 0.05). The level of anti-Rv1813c-immunoglobulin G (IgG) in the rv1813c DNA group was significantly increased (p < 0.01). The levels of specific IgG, IgG1, and IgG2a in the rv2628 DNA, rv2029c DNA, and rv2659c DNA groups were significantly increased (p < 0.05). Lung colony-forming units in M. vaccae and the six DNA groups decreased to different degrees in the MTB reactivation mouse model, but only the lung colony-forming units in the rv2628 DNA group (4.38 ± 0.70 log10) significantly decreased compared to the vector group (5.90 ± 0.42 log10; p < 0.05). The MTB rv1813c DNA, rv2628 DNA, rv2029c DNA, and rv2659c DNA could elicit a strong humoral immune response and a higher proportion of CD4+CD25+or CD4+Foxp3+ T cells but could not increase the proportions of Th1 and Tc1 cells. These results suggest that latency-associated DNA vaccines, especially rv2628 DNA, had some therapeutic effect on the endogenous resurgence mouse tuberculosis model.

Diagnostic performance and problem analysis of commercial tuberculosis antibody detection kits in China.

BACKGROUND: The diagnosis of bacterium-negative pulmonary tuberculosis (TB) and extra-pulmonary TB is challenging clinically. The detection of the anti-TB antibody has an important, auxiliary, clinical diagnostic value. Therefore, TB antibody detection kits should be screened and evaluated, and the reagents with the highest sensitivity and specificity should be chosen and used clinically. METHODS: The diagnostic performance of 7 commercially available TB antibody detection kits (kits A, B, C, D, E, F and G) based on the gold immunoassay detection of immunoglobulin (Ig) G or IgM antibodies were simultaneously evaluated and compared in 62 TB cases and 56 non-TB cases in a laboratory. A retrospective analysis including 2549 cases was carried out to assess the clinical diagnosis values of bacteriological examinations and TB antibody tests (kits B and H used in the clinic). RESULTS: The sensitivities of TB antibody kits A, B, C, D, E, F and G in the sera from 62 TB patients were 50.0%, 83.9%, 38.7%, 9.7%, 48.4%, 69.4% and 79.0%, respectively; the sensitivities in the sera from 24 smear-negative TB patients were 29.2%, 79.2%, 29.2%, 12.5%, 29.2%, 54.2% and 79.2%, respectively; the specificities in the sera from 56 non-TB patients were 73.2%, 25.0%, 85.7%, 96.4%, 78.6%, 78.6% and 50.0%, respectively. Of the 2549 clinically diagnosed cases, there were 1752 pulmonary TB cases, 505 extra-pulmonary TB cases, 87 old pulmonary TB cases and 205 non-TB cases. The positive results for smear, culture, TB antibody kit B and kit H in pulmonary TB cases were 39.8% (543/1365), 48.6% (372/765), 45.8% (802/1752) and 25.2% (442/1752), respectively; the results in extra-pulmonary TB cases were 3.4% (6/178), 5.8% (4/69), 35.4% (179/505), and 11.3% (57/505), respectively; the results in old pulmonary TB cases were 0% (0/64), 0% (0/30), 32.2% (28/87), and 9.2% (8/87), respectively; and the results in non-TB cases were 0% (0/121), 0% (0/56), 21.5% (44/205), and 2.4% (5/205), respectively. Of 624 smear-positive and/or culture-positive pulmonary TB cases, the sensitivities of antibody test kits B and H were 53.0% and 36.4%, respectively. Of 901 smear-negative and/or culture-negative pulmonary TB cases, the sensitivities of antibody test kits B and H were 42.5% and 19.0%, respectively. The positive rate of antibody detection in the bacterium-positive pulmonary TB cases was significantly higher than that in the bacterium-negative pulmonary TB cases (P < 0.05). CONCLUSIONS: The colloidal gold-labeled TB antibody IgG detection assay is a simple, rapid and economical method that provides a better clinical auxiliary diagnosis value on TB, especially in smear-negative pulmonary TB and extra-pulmonary TB. The production, quality control, screening and evaluation of antibody detection kits are very important for its clinical application.

Precisely Designed Isopeptide Bridge-Crosslinking Endows Artificial Hydrolases with High Stability and Catalytic Activity under Extreme Denaturing Conditions.

Enzymes normally lose their activities under extreme conditions due to the dissociation of their active tertiary structure. If an enzyme could maintain its catalytic activity under non-physiological or denaturing conditions, it might be used in more applications in the pharmaceutical and chemical industries. Recently, we reported a coiled-coil six-helical bundle (6HB) structure as a scaffold for designing artificial hydrolytic enzymes. Here, intermolecular isopeptide bonds were incorporated to enhance the stability and activity of such biomolecules under denaturing conditions. These isopeptide bridge-tethered 6HB enzymes showed exceptional stability against unfolding and retained or even had increased catalytic activity for a model hydrolysis reaction under thermal and chemical denaturing conditions. Thus, isopeptide bond-tethering represents an efficient route to construct ultrastable artificial hydrolases, with promising potential to maintain biocatalysis under extreme conditions.

Increase of anti-HIV activity of C-peptide fusion inhibitors using a bivalent drug design approach.

We reported the design of fusion inhibitors with improved activity using a multivalent inhibitor design strategy. First, we chose C29 as the template sequence, which is a 29-mer peptide derived from HIV-1 gp41 CHR domain and has anti-HIV activity of IC50 118 nM in a cell-cell fusion assay. We optimized the crosslink sites and linkers of the template peptide. We found that N-terminal crosslink caused activity improvement based on the multivalent co-operative effect. Especially, the IC50 of peptide (CAcaC29)2 was improved from 49.02 (monomeric form) to 5.71 nM. Compared with long peptides, short peptides may be more suitable to analyze the co-operative effect. So we selected a shorter peptide C22 to synthesize the bivalent inhibitors. Due its weak helicity, no co-operative effect appeared. Therefore, we chose SC22EK, which were introduced salt bridges to consolidate the helicity based on the natural sequence C22. The cross-linked (CAcaSC22EK)2 was four times more potent than the monomer SC22EK in anti-HIV activity, with an IC50 value of 4.92 nM close to the high active peptide fusion inhibitor C34. The strategy used in this study may be used to design new fusion inhibitors to interfere similar processes.

Inter-chain acyl transfer reaction in a peptide six-helical bundle: a chemical method for regulating the interaction between peptides or proteins.

An inter-helical acyl transfer specifically occurred between the C-and N-peptides of HIV gp41 after assembly of the six-helical bundle (6HB), forming an inter-helical covalent bond that greatly enhanced 6HB stability. In the reaction, the C-peptide was modified as an acyl donor, and the N-peptide served as an acyl acceptor.

Heteromeric assembled polypeptidic artificial hydrolases with a six-helical bundle scaffold.

Enzyme efficiency results from the cooperation of functional groups in the catalytic site. In order to mimic a natural enzyme, a definite 3D scaffold must be carefully designed so that the functional groups can work cooperatively. During the HIV-1 fusion process, the gp41 N- and C-terminal heptad repeat regions form a coiled-coil six-helical bundle (6HB) that brings the viral and target cell membranes into close proximity for fusion. We used 6HB as the molecular model for a novel scaffold for the design of an artificial enzyme, in which the modified C34 and N36 peptides formed a unique 6HB structure through specific molecular recognition, and the position and orientation of the side-chain groups on this scaffold were predictable. The histidine modified 6HB C34(H13/20)/N36(H15/22) showed enzyme-like hydrolytic activity towards p-nitrophenyl acetate (PNPA; k(cat)/K(M) =3.66 M(-1) s(-1)) through the cooperation of several inter- or intrahelical imidazole groups. Since the catalytic activity of 6HB depends on the C- and N-peptide assembly, either HIV fusion inhibitors that can compete with the formation of catalytic 6HB or denaturants that can destroy the ordered structure were able to modulate its activity. Further engineering of the solvent-exposing face with Glu(-)-Lys(+) salt bridges enhanced the helicity and the stability of 6HB. As a result, the population and stability of cooperative catalytic units increased. In addition, the Glu(-)-Lys(+) -stabilized 6HB SC35(H13/20)/N36(H15/22) had increased catalytic efficiency (k(cat)/K(M) =6.30 M(-1) s(-1)). A unique 6HB system was specifically assembled and provided a scaffold sufficiently stable to mimic the function of enzymes or other biomolecules.