Host immune responses to antigens derived from a predominant strain of Mycobacterium tuberculosis

Association between Mycobacterium tuberculosis genotype and diabetes mellitus/hypertension: a molecular study

Background

A paucity of studies focused on the genetic association that tuberculosis (TB) patients with non-communicable diseases (NCDs) are more likely to be infected with Mycobacterium tuberculosis (MTB) with more potent virulence on anti-TB drug resistance than those without NCDs. The study aimed to document the predominant genotype, determine the association between MTB genotypes and NCD status and drug resistance.

Methods

We conducted a molecular study in 105 TB patients based on a cross-sectional study focused on the comorbid relationship between chronic conditions and TB among 1773 subjects from September 1, 2019 to August 30, 2020 in Guizhou, China. The participants were investigated through face-to-face interviews, followed by NCDs screening. The DNA of MTB isolates was extracted prior to genotyping using 24 loci MIRU-VNTR. The subsequent evaluations were performed by phylogenetic trees, combined with tests of statistical power, Chi-square or Fisher and multivariate logistic regression analysis.

Results

The Beijing family of Lineage 2 (East Asia) was the predominant genotype accounting for 43.8% (46/105), followed by Lineage 4 (Euro-America) strains, including Uganda I (34.3%, 36/105), and the NEW-1 (9.5%, 10/105). The proportion of Beijing strain in patients with and without NCDS was 28.6% (8/28) and 49.4% (38/77), respectively, with a statistical power test value of 24.3%. No significant association was detected between MTB genotype and NCD status. A low clustering rate (2.9%) was identified, consisting of two clusters. The rates of global, mono-, poly- and multi-drug resistance were 16.2% (17/105), 14.3% (15/105), 1.0% (1/105) and 4.8% (5/105), respectively. The drug-resistant rates of rifampicin, isoniazid, and streptomycin, were 6.7% (7/105), 11.4% (12/105) and 5.7% (6/105), respectively. Isoniazid resistance was significantly associated with the Beijing genotype of Lineage 2 (19.6% versus 5.1%).

Conclusions

The Lineage 2 East Asia/Beijing genotype is the dominant genotype of the local MTB with endogenous infection preponderating. Not enough evidence is detected to support the association between the MTB genotype and diabetes/hypertension. Isoniazid resistance is associated with the Lineage 2 East Asia/Beijing strain.

Supplementary information

The online version contains supplementary material available at 10.1186/s12879-022-07344-z.

Gradient association between pulmonary tuberculosis and diabetes mellitus among households with a tuberculosis case: a contact tracing-based study

Pulmonary tuberculosis (PTB) and diabetes mellitus (DM) remain high morbidity and mortality, especially when they are comorbid with each other. Screening for diabetes mellitus in tuberculosis is essential as the incidence and mortality of DM in the population with PTB are higher than in the general people. We aimed to examine the gradient association of tuberculosis on developing DM, the additional yield and the number needed to screen (NNS) to find a new diabetes case. A cross-sectional study was conducted on 801 tuberculosis cases and 972 household contacts in Guizhou, China, from April 2019 to October 2020. After screening for PTB among contacts, all participants were screened for DM and interviewed. Kendall's tau-b test and proportional odds logistic regression analysis were applied to identify the gradient associations. Among the 1773 subjects, the additional yield of screening was 21.8%. The NNSs of the non-PTB group, the sputum-culture negative and positive groups were 50, 60 and 113, respectively. The gradient incremental establishment of DM and PTB were positively correlated. The general trend on the gradient of DM significantly increased with the gradient increase of PTB. Age 35 years and over, excessive edible oil intake and DM family history were identified as significant predictors of diabetes. Integrated screening for DM targeted to different gradients of PTB combined with associated factors is necessitated to achieve a higher additional yield.

Practical approach to detection and surveillance of emerging highly resistant Mycobacterium tuberculosis Beijing 1071-32-cluster

Ancient sublineage of the Mycobacterium tuberculosis Beijing genotype is endemic and prevalent in East Asia and rare in other world regions. While these strains are mainly drug susceptible, we recently identified a novel clonal group Beijing 1071-32 within this sublineage emerging in Siberia, Russia and present in other Russian regions. This cluster included only multi/extensive drug resistant (MDR/XDR) isolates. Based on the phylogenetic analysis of the available WGS data, we identified three synonymous SNPs in the genes Rv0144, Rv0373c, and Rv0334 that were specific for the Beijing 1071-32-cluster and developed a real-time PCR assay for their detection. Analysis of the 2375 genetically diverse M. tuberculosis isolates collected between 1996 and 2020 in different locations (European and Asian parts of Russia, former Soviet Union countries, Albania, Greece, China, Vietnam, Japan and Brazil), confirmed 100% specificity and sensitivity of this real-time PCR assay. Moreover, the epidemiological importance of this strain and the newly developed screening assay is further stressed by the fact that all identified Beijing 1071-32 isolates were found to exhibit MDR genotypic profiles with concomitant resistance to additional first-line drugs due to a characteristic signature of six mutations in rpoB450, rpoC485, katG315, katG335, rpsL43 and embB497. In conclusion, this study provides a set of three concordant SNPs for the detection and screening of Beijing 1071-32 isolates along with a validated real-time PCR assay easily deployable across multiple settings for the epidemiological tracking of this significant MDR cluster.

Screening for Mycobacterium tuberculosis Infection Using Beijing/K Strain-Specific Peptides in a School Outbreak Cohort

Background

The Beijing strain of Mycobacterium tuberculosis (M. tb) has been most frequently isolated from TB patients in South Korea, and the hyper-virulent Beijing/K genotype is associated with TB outbreaks. To examine the diagnostic potential of Beijing/K-specific peptides, we performed IFN-γ release assays (IGRA) using a MTBK antigen tube containing Beijing/K MTBK_24800, ESAT-6, and CFP-10 peptides in a cohort studied during a school TB outbreak.

Methods

A total of 758 contacts were investigated for M. tb infection, and 43 contacts with latent TB infection (LTBI) and 25 active TB patients were enrolled based on serial screening with QuantiFERON-TB Gold In-Tube tests followed by clinical examinations. Blood collected in MTBK antigen tubes was utilized for IGRA and multiplex cytokine bead arrays. Immune responses were retested in 24 patients after TB treatment, and disease progression was investigated in subjects with LTBI.

Results

Total proportions of active disease and LTBI during the outbreak were 3.7% (28/758) and 9.2% (70/758), respectively. All clinical isolates had a Beijing/K M. tb genotype. IFN-γ responses to the MTBK antigen identified M. tb infection and distinguished between active disease and LTBI. After anti-TB treatment, IFN-γ responses to the MTBK antigen were significantly reduced, and strong TNF-α responses at diagnosis were dramatically decreased.

Conclusions

MTBK antigen-specific IFN-γ has diagnostic potential for differentiating M. tb infection from healthy controls, and between active TB and LTBI as well. In addition, TNF-α is a promising marker for monitoring therapeutic responses. These data provide informative readouts for TB diagnostics and vaccine studies in regions where the Beijing/K strain is endemic.

Evaluation of cytokines as a biomarker to distinguish active tuberculosis from latent tuberculosis infection: a diagnostic meta-analysis

OBJECTIVES

With a marginally effective vaccine and no significant breakthroughs in new treatments, a sensitive and specific method to distinguish active tuberculosis from latent tuberculosis infection (LTBI) would allow for early diagnosis and limit the spread of the pathogen. The analysis of multiple cytokine profiles provides the possibility to differentiate the two diseases.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Cochrane Library, Clinical Key and EMBASE databases were searched on 31 December 2019.

ELIGIBILITY CRITERIA

We included case-control studies, cohort studies and randomised controlled trials considering IFN-γ, TNF-α, IP-10, IL-2, IL-10, IL-12 and VEGF as biomarkers to distinguish active tuberculosis and LTBI.

DATA EXTRACTION AND SYNTHESIS

Two students independently extracted data and assessed the risk of bias. Diagnostic OR, sensitivity, specificity, positive and negative likelihood ratios and area under the curve (AUC) together with 95% CI were used to estimate the diagnostic value.

RESULTS

Of 1315 records identified, 14 studies were considered eligible. IL-2 had the highest sensitivity (0.84, 95% CI: 0.72 to 0.92), while VEGF had the highest specificity (0.87, 95% CI: 0.73 to 0.94). The highest AUC was observed for VEGF (0.85, 95% CI: 0.81 to 0.88), followed by IFN-γ (0.84, 95% CI: 0.80 to 0.87) and IL-2 (0.84, 95% CI: 0.81 to 0.87).

CONCLUSION

Cytokines, such as IL-2, IFN-γ and VEGF, can be utilised as promising biomarkers to distinguish active tuberculosis from LTBI.

PROSPERO REGISTRATION NUMBER

CRD42020170725.

Diagnostic Potential of a PPE Protein Derived from Mycobacterium tuberculosis Beijing/K Strain

PURPOSE

The prevalence of Mycobacterium tuberculosis (M. tb) and the status of M. bovis BCG vaccination may affect host immune responses to M. tb antigens. Understanding of the predominant local M. tb strain and immune signatures induced by its strain-specific antigens may contribute to an improved diagnosis of tuberculosis (TB). The aim of this study was to determine immune responses to M. tb antigen which was identified from the hyper-virulent Beijing/K strain in South Korea.

MATERIALS AND METHODS

Pulmonary TB patients (n=52) and healthy subjects (n=92) including individuals with latent TB infection (n=31) were recruited, and QuantiFERON-TB Gold In-Tube tests were performed. The Beijing/K-antigen specific immune signatures were examined by diluted whole blood assays and multiplex bead arrays in a setting where nationwide BCG vaccination is employed.

RESULTS

Statistical analyses demonstrated that three [C-X-C motif chemokine (CXCL10), interleukin (IL)-6, interferon (IFN)-α] of 17 cytokines/chemokines distinguished active cases from healthy controls following stimulation with the Beijing/K-specific antigen. IFN-α also differentiated between active diseases and latent TB infection (p<0.01), and the detection rate of TB was dramatically increased in combination with IL-6 and CXCL10 at the highest levels of specificity (95-100%).

CONCLUSION

Our data indicate that immune signatures to the M. tb Beijing/K-specific antigen can provide useful information for improved TB diagnostics. The antigen may be developed as a diagnostic marker or a vaccine candidate, particularly in regions where the M. tb Beijing/K strain is endemic.

Immunogenicity and Vaccine Potential of InsB, an ESAT-6-Like Antigen Identified in the Highly Virulent Mycobacterium tuberculosis Beijing K Strain

Our group recently identified InsB, an ESAT-6-like antigen belonging to the Mtb9.9 subfamily within the Esx family, in the Mycobacterium tuberculosis Korean Beijing strain (Mtb K) via a comparative genomic analysis with that of the reference Mtb H37Rv and characterized its immunogenicity and its induced immune response in patients with tuberculosis (TB). However, the vaccine potential of InsB has not been fully elucidated. In the present study, InsB was evaluated as a subunit vaccine in comparison with the most well-known ESAT-6 against the hypervirulent Mtb K. Mice immunized with InsB/MPL-DDA exhibited an antigen-specific IFN-γ response along with antigen-specific effector/memory T cell expansion in the lungs and spleen upon antigen restimulation. In addition, InsB immunization markedly induced multifunctional Th1-type CD4⁺ T cells coexpressing TNF-α, IL-2, and IFN-γ in the lungs following Mtb K challenge. Finally, we found that InsB immunization conferred long-term protection against Mtb K comparable to that conferred by ESAT-6 immunization, as evidenced by a similar level of CFU reduction in the lung and spleen and reduced lung inflammation. These results suggest that InsB may be an excellent vaccine antigen component for developing a multiantigenic Mtb subunit vaccine by generating Th1-biased memory T cells with a multifunctional capacity and may confer durable protection against the highly virulent Mtb K.

Protective Vaccine Efficacy of the Complete Form of PPE39 Protein from Mycobacterium tuberculosis Beijing/K Strain in Mice

The aim of this study was to evaluate the protective efficacy of MTBK_24820, a complete form of PPE39 protein derived from a predominant Beijing/K strain of Mycobacterium tuberculosis in South Korea. Mice were immunized with MTKB_24820, M. bovis Bacilli Calmette-Guérin (BCG), or adjuvant prior to a high-dosed Beijing/K strain aerosol infection. After 4 and 9 weeks, bacterial loads were determined and histopathologic and immunologic features in the lungs and spleens of the M. tuberculosis-infected mice were analyzed. Putative immunogenic T-cell epitopes were examined using synthetic overlapping peptides. Successful immunization of MTBK_24820 in mice was confirmed by increased IgG responses (P < 0.05) and recalled gamma interferon (IFN-γ), interleukin-2 (IL-2), IL-6, and IL-17 responses (P < 0.05 or P < 0.01) to MTBK_24820. After challenge with the Beijing/K strain, an approximately 0.5 to 1.0 log₁₀ reduction in CFU in lungs and fewer lung inflammation lesions were observed in MTBK_24820-immunized mice compared to those for control mice. Moreover, MTBK_24820 immunization elicited significantly higher numbers of CD4⁺ T cells producing protective cytokines, such as IFN-γ and IL-17, in lungs and spleens (P < 0.01) and CD4⁺ multifunctional T cells producing IFN-γ, tumor necrosis factor alpha (TNF-α), and/or IL-17 (P < 0.01) than in control mice, suggesting protection comparable to that of BCG against the hypervirulent Beijing/K strain. The dominant immunogenic T-cell epitopes that induced IFN-γ production were at the N terminus (amino acids 85 to 102 and 217 to 234). Its vaccine potential, along with protective immune responses in vivo, may be informative for vaccine development, particularly in regions where the M. tuberculosis Beijing/K-strain is frequently isolated from TB patients.