High level of IFN-γ released from whole blood of human tuberculosis infections following stimulation with Rv2073c of Mycobacterium tuberculosis

Cell-mediated and serology-based tests for Mycobacterium ulcerans disease: A systematic review and meta-analysis

Buruli ulcer (BU) is a subcutaneous necrotic infection of the skin caused by Mycobacterium ulcerans. It is the third most common human mycobacterial disease after tuberculosis (TB) and leprosy. The available methods for detection of the bacilli in lesions are microscopic detection, isolation and cultivation of the bacterium, histopathology, and polymerase chain reaction (PCR). These methods, although approved by the World Health Organization (WHO), have infrastructural and resource challenges in medical centres and cell-mediated immunity (CMI) and/or serology-based tests have been suggested as easier and more appropriate for accurate assessment of the disease, especially in remote or underdeveloped areas. This study systematically reviewed and conducted a meta-analysis for all research aimed at developing cell-mediated immunity (CMI) and/or serology-based tests for M. ulcerans disease. Information for this review was searched through PubMed and Web of Science databases and identified up to June 2019. References from relevant articles and reports from the WHO Annual Meeting of the Global Buruli Ulcer Initiative were also used. Twelve studies beginning in 1952, that attempted to develop CMI and/or serology-based tests for the disease were identified. These studies addressed issues of specificity and sensitivity in context of antigen composition as well as study heterogeneity and bias. The two main types of antigenic preparations considered were pathogen-derived and recombinant protein preparations. There was slight difference in test performance when M. ulcerans recombinant proteins [positivity: 67.5%; 32.5%] or pathogen-derived [positivity: 76.0%; 24.0%] preparations were used as test antigens among BU patients. However, pathogen-derived preparations were better at differentiating between patients and control groups [odds ratio (OR) of 27.92, 95%CI: 5.05-154.28]. This was followed by tests with the recombinant proteins [OR = 1.23, 95%CI: 0.27-5.62]. Overall, study heterogeneity index, I2 was 92.4% (p = 0.000). It is apparent from this review that standardisation is needed in any future CMI and/or serology-based tests used for M. ulcerans disease.

Dynamic Changes of Th1 Cytokines and the Clinical Significance of the IFN-γ/TNF-α Ratio in Acute Brucellosis

Background

T-helper type 1 (Th1) cells and Th1-produced cytokines play essential roles in the immune response to foreign pathogens, such as Brucella spp. The aim of this study was to evaluate the dynamic changes of Th1 cells and Th1-produced cytokines in patients with acute brucellosis and their impact on clinical decision-making.

Methods

Fifty-one individuals with acute brucellosis and 17 healthy subjects were enrolled in this study. The brucellosis patients were diagnosed based on clinical symptoms, laboratory tests, and clinical examination. The levels of serum gamma-interferon (IFN-γ) and tumor necrosis factor-alpha (TNF-α), along with the percentage of Th1 cells, were determined by flow cytometry bead arrays (CBA).

Results

The frequency of Th1 cells, along with the levels of IFN-γ and TNF-α, was negatively correlated with the clinical parameters. The mean serum levels of IFN-γ and TNF-α and the frequency of Th1 cells were significantly higher in the brucellosis patients in comparison with the healthy subjects (p < 0.05). Besides, the cytokine levels were not significantly different between the positive and negative blood culture groups. IFN-γ levels significantly decreased from 6 months to 12 months post treatment (p < 0.05). However, the IFN-γ levels remained higher than those of the healthy subjects by 12 months post treatment (p < 0.05). The IFN-γ/TNF-α ratio was significantly higher in severe cases than in nonsevere cases (p < 0.05).

Conclusions

The IFN-γ levels secreted by Th1 cells remain significantly higher than those of healthy subjects more than 12 months after treatment with antibiotics. This finding is different from similar studies. The IFN-γ/TNF-α ratio may be a feasible parameter for assessing clinical severity, yet further longitudinal studies of the immunization and inflammatory reaction of brucellosis are needed in larger patient populations.

Formulation in DDA-MPLA-TDB Liposome Enhances the Immunogenicity and Protective Efficacy of a DNA Vaccine against Mycobacterium tuberculosis Infection

Despite the vaccine Mycobacterium bovis Bacillus Calmette–Guérin is used worldwide, tuberculosis (TB) remains the first killer among infectious diseases. An effective vaccine is urgently required. DNA vaccine has shown prophylactic as well as therapeutic effects against TB, while its weak immunogenicity hinders the application. As a strong inducer of Th1-biased immune response, DMT, consisting of dimethyldioctadecylammonium (DDA) and two pattern recognition receptor agonists monophosphoryl lipid A and trehalose 6,6′-dibehenate (TDB), was a newly developed liposomal adjuvant. To elucidate the action mechanism of DMT and improve immunological effects induced by DNA vaccine, a new recombinant eukaryotic expression plasmid pCMFO that secretes the fusion of four multistage antigens (Rv2875, Rv3044, Rv2073c, and Rv0577) of Mycobacterium tuberculosis was constructed. pCMFO/DDA and pCMFO/DMT complexes were then prepared and their physicochemical properties were analyzed. The immunogenicity and protection against M. tuberculosis infection in vaccinated C57BL/6 mice were compared. Formulation of DNA and two agonists into the DDA liposome decreased zeta potential but increased the stability of storage, which resulted in a slower and longer-lasting release of DNA from the DNA–DMT complex than the DNA–DDA liposome. Besides Th1-biased responses, pCMFO/DMT vaccinated mice elicited more significantly CFMO-specific IL2⁺ T_CM cell responses in the spleen and provided an enhanced and persistent protection against M. tuberculosis aerosol infection, compared to pCMFO/DDA and pCMFO groups. Therefore, the adjuvant DMT can release DNA and agonists slowly, which might attribute to the improved protection of DMT adjuvanted vaccines. pCMFO/DMT, a very promising TB vaccine, warrants for further preclinical and clinical trials.

Differential gene expression in Mycobacterium bovis challenged monocyte-derived macrophages of cattle

A functional genomics approach was used to examine the immune response for transcriptional profiling of PBMC M. bovis infected cattle and healthy control cattle to stimulation with bovine tuberculin (purified protein derivative PPD-b). Total cellular RNA was extracted from non-challenged control and M. bovis challenged MDM for all animals at intervals of 6 h post-challenge, in response to in-vitro challenge with M. bovis (multiplicity of infection 2:1) and prepared for global gene expression analysis using the Agilent Bovine (V2) Gene Expression Microarray, 8 × 60 K. The pattern of expression of these genes in PPD bovine stimulated PBMC provides the first description of an M. bovis specific signature of infection that may provide insights into the molecular basis of the host response to infection. Analysis of these mapped reads showed 2450 genes (1291 up regulated and 1158 down regulated) 462 putative natural antisense transcripts (354 up-regulated and 108 down regulated) that were differentially expressed based on sense and antisense strand data, respectively (adjusted P-value ≤ 0.05). The results provided enrichment for genes involved top ten up regulated and down regulated panel of genes, including transcription factors proliferation of T and B lymphocytes. The highest differentially-expressed genes were associated to immune and inflammatory responses, immunity, differentiation, cell growth, apoptosis, cellular trafficking and regulation of lipolysis and thermogenesis. Microarray results were confirmed in infected cattle by RT qPCR to identify potential biomarkers TLR2, CD80, NFKB1, IL8, CXCL6 and ADORA3 of bovine tuberculosis.

A Multistage Subunit Vaccine Effectively Protects Mice Against Primary Progressive Tuberculosis, Latency and Reactivation

Adult tuberculosis (TB) is the main cause of TB epidemic and death. The infection results mainly by endogenous reactivation of latent TB infection and secondarily transmitted by exogenous infection. There is no vaccine for adult TB. To this end, we first chose antigens from a potential antigenic reservoir. The antigens strongly recognized T cells from latent and active TB infections that responded to antigens expressed by Mycobacterium tuberculosis cultured under different metabolic states. Fusions of single-stage polyprotein CTT3H, two-stage polyprotein A1D4, and multistage CMFO were constructed. C57BL/6 mice vaccinated with DMT adjuvant ed CMFO (CMFO-DMT) were protected more significantly than by CTT3H-DMT, and efficacy was similar to that of the only licensed vaccine, Bacillus Calmette–Guérin (BCG) and A1D4-DMT in the M. tuberculosis primary infection model. In the setting of BCG priming and latent TB infection, M. tuberculosis in the lung and spleen was eliminated more effectively in mice boosted with CMFO-DMT rather than with BCG, A1D4-DMT, or CTT3H-DMT. In particular, sterile immunity was only conferred by CMFO-DMT, which was associated with expedited homing of interferon-gamma⁺ CD4⁺ T_EM and interleukin-2⁺ T_CM cells from the spleen to the infected lung. CMFO-DMT represents a promising candidate to prevent the occurrence of adult TB through both prophylactic and therapeutic methods, and warrants assessment in preclinical and clinical trials.

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CMFO-DMT provides the comparable protection against primary infection with M. tuberculosis as BCG vaccine does.

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CMFO-DMT boosts an effective protection of BCG primed mice to eliminate latent infection and thwart reactivation.

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CMFO-DMT is a promising vaccine candidate for the prevention of adult TB disease.

Adult pulmonary TB is the main clinical form of the disease and the main component of TB epidemics. There is no effective vaccine to protect adults from primary and secondary TB. Vaccine candidates were constructed using combinations of one-, two- or multi-stage antigens of M. tuberculosis representing different stages of the infection. The antigen combinations directed at different stages of TB may help control adult TB.