The assessment of cytokines in Quantiferon supernatants for the diagnosis of latent TB infection in a tribal population of Melghat, India

The prevalence of tuberculosis infection in India: A systematic review and meta-analysis

Background & objectives

The National Prevalence Survey of India (2019-2021) estimated 31 per cent tuberculosis infection (TBI) burden among individuals above 15 years of age. However, so far little is known about the TBI burden among the different risk groups in India. Thus, this systematic review and meta-analysis, aimed to estimate the prevalence of TBI in India based on geographies, sociodemographic profile, and risk groups.

Methods

To identify the prevalence of TBI in India, data sources such as MEDLINE, EMBASE, CINAHL, and Scopus were searched for articles reporting data between 2013-2022, irrespective of the language and study setting. TBI data were extracted from 77 publications and pooled prevalence was estimated from the 15 community-based cohort studies. Articles were reviewed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines and were sourced using a predefined search strategy from different databases.

Results

Out of 10,521 records, 77 studies (46 cross-sectional and 31 cohort studies) were included. The pooled TBI prevalence for India based on the community-based cohort studies was estimated as 41 per cent [95% confidence interval (CI) 29.5-52.6%] irrespective of the risk of acquiring it, while the estimation was 36 per cent (95% CI 28-45%) prevalence observed among the general population excluding high-risk groups. Regions with high active TB burden were found to have a high TBI prevalence such as Delhi and Tamil Nadu. An increasing trend of TBI was observed with increasing age in India.

Interpretation & conclusions

This review demonstrated a high prevalence of TBI in India. The burden of TBI was commensurate with active TB prevalence suggesting possible conversion of TBI to active TB. A high burden was recorded among people residing in the northern and southern regions of the country. Such local epidemiologic variation need to be considered to reprioritize and implement-tailored strategies for managing TBI in India.

Challenges and the Way forward in Diagnosis and Treatment of Tuberculosis Infection

Globally, it is estimated that one-quarter of the world's population is latently infected with Mycobacterium tuberculosis (Mtb), also known as latent tuberculosis infection (LTBI). Recently, this condition has been referred to as tuberculosis infection (TBI), considering the dynamic spectrum of the infection, as 5-10% of the latently infected population will develop active TB (ATB). The chances of TBI development increase due to close contact with index TB patients. The emergence of multidrug-resistant TB (MDR-TB) and the risk of development of latent MDR-TB has further complicated the situation. Detection of TBI is challenging as the infected individual does not present symptoms. Currently, there is no gold standard for TBI diagnosis, and the only screening tests are tuberculin skin test (TST) and interferon gamma release assays (IGRAs). However, these tests have several limitations, including the inability to differentiate between ATB and TBI, false-positive results in BCG-vaccinated individuals (only for TST), false-negative results in children, elderly, and immunocompromised patients, and the inability to predict the progression to ATB, among others. Thus, new host markers and Mtb-specific antigens are being tested to develop new diagnostic methods. Besides screening, TBI therapy is a key intervention for TB control. However, the long-course treatment and associated side effects result in non-adherence to the treatment. Additionally, the latent MDR strains are not susceptible to the current TBI treatments, which add an additional challenge. This review discusses the current situation of TBI, as well as the challenges and efforts involved in its control.

Evidence, Challenges, and Knowledge Gaps Regarding Latent Tuberculosis in Animals

Mycobacterium bovis and other Mycobacterium tuberculosis complex (MTBC) pathogens that cause domestic animal and wildlife tuberculosis have received considerably less attention than M. tuberculosis, the primary cause of human tuberculosis (TB). Human TB studies have shown that different stages of infection can exist, driven by host–pathogen interactions. This results in the emergence of heterogeneous subpopulations of mycobacteria in different phenotypic states, which range from actively replicating (AR) cells to viable but slowly or non-replicating (VBNR), viable but non-culturable (VBNC), and dormant mycobacteria. The VBNR, VBNC, and dormant subpopulations are believed to underlie latent tuberculosis (LTB) in humans; however, it is unclear if a similar phenomenon could be happening in animals. This review discusses the evidence, challenges, and knowledge gaps regarding LTB in animals, and possible host–pathogen differences in the MTBC strains M. tuberculosis and M. bovis during infection. We further consider models that might be adapted from human TB research to investigate how the different phenotypic states of bacteria could influence TB stages in animals. In addition, we explore potential host biomarkers and mycobacterial changes in the DosR regulon, transcriptional sigma factors, and resuscitation-promoting factors that may influence the development of LTB.

Cytokine Biosignature of Active and Latent Mycobacterium Tuberculosis Infection in Children

None of the currently used diagnostic tools are efficient enough in diagnosing Mycobacterium tuberculosis (M.tb) infection in children. The study was aimed to identify cytokine biosignatures characterizing active and latent tuberculosis (TB) in children. Using a multiplex bead-based technology, we analyzed the levels of 53 Th17-related cytokines and inflammatory mediators in sera from 216 BCG-vaccinated children diagnosed with active TB (TB) or latent TB (LTBI) as well as uninfected controls (HC). Children with active TB, compared to HC children, showed reduced serum levels of IL-17A, MMP-2, OPN, PTX-3, and markedly elevated concentrations of APRIL/TNFSF13. IL-21, sCD40L, MMP-2, and IL-8 were significantly differentially expressed in the comparisons between groups: (1) HC versus TB and LTBI (jointly), and (2) TB versus LTBI. The panel consisting of APRIL/TNFSF13, sCD30/TNFRSF8, IFN-α2, IFN-γ, IL-2, sIL-6Rα, IL-8, IL-11, IL-29/IFN-λ1, LIGHT/TNFSF14, MMP-1, MMP-2, MMP-3, osteocalcin, osteopontin, TSLP, and TWEAK/TNFSF12 possessed a discriminatory potential for the differentiation between TB and LTBI children. Serum-based host biosignatures carry the potential to aid the diagnosis of childhood M.tb infections. The proposed panels of markers allow distinguishing not only children infected with M.tb from uninfected individuals but also children with active TB from those with latent TB.

Interleukin-6 and Mycobacterium tuberculosis dormancy antigens improve diagnosis of tuberculosis

OBJECTIVES

IFNγ-release assays (IGRAs) used for diagnosis of Mycobacterium (M.) tuberculosis infection have limited sensitivity. Alternative cytokines and M. tuberculosis latency-associated antigens may improve immune-based tests.

METHODS

Multiplex cytokine analyses was done in culture supernatants after 6-day in vitro restimulation with M. tuberculosis IGRA and latency-associated antigens (i.e. Rv2628, Rv1733) in tuberculosis patients (n = 22) and asymptomatic contacts (AC)s (n = 20) from Ghana.

RESULTS

Four cytokines (i.e. IFNγ, IP-10, IL-22 and IL-6) were significantly increased after IGRA-antigen specific restimulation. IFNγ, IP-10, and IL-22 correlated positively and showed no differences between the study groups whereas IGRA-antigen induced IL-6 was significantly higher in tuberculosis patients. Using adjusted IGRA criteria, IL-6 showed the highest sensitivity for detection of tuberculosis patients (91%) and ACs (85%) as compared to IFNγ, IP-10, and IL-22. Rv2628 and Rv1733 restimulation induced significantly higher IFNγ, IP-10, and IL-22 concentrations in ACs. Combined antigen/cytokine analyses identified study group specific patterns and a combination of Rv2628/Rv1733 induced IFNγ with IGRA-antigen induced IL-6 was optimal for classification of tuberculosis patients and ACs (AUC: 0.92, p<0.0001).

CONCLUSIONS

We demonstrate the potency of alternative cytokines, especially IL-6, and latency-associated antigens Rv1733/Rv2628 to improve detection of M. tuberculosis infection and to classify tuberculosis patients and healthy contacts.

Gaps in Study Design for Immune Parameter Research for Latent Tuberculosis Infection: A Systematic Review

Background

Immune parameters (IP) have been extensively studied to distinguish between latent tuberculosis (LTBI) and active tuberculosis (TB).

Objective

To determine the IP associated with LTBI, compared to active TB and individuals not infected by M. tuberculosis published in literature.

Methods

We conducted a systematic search using Google Scholar and PubMed databases, combining the MeSH terms latent tuberculosis, Mycobacterium tuberculosis, cytokines, and biological markers, with the free terms, biomarkers and cytokines. Spanish, English, and Portuguese articles comparing the concentration of IP associated with LTBI, either in plasma/serum or in vitro, in adults and nonimmunocompromised versus individuals with TB or without M. tuberculosis infection between 2006 July and 2018 July were included. Two blinded reviewers carried out the searches, read the abstracts, and selected the articles for analysis. Participants' information, diagnostic criteria, IP, detection methods, and biases were collected.

Results

We analyzed 36 articles (of 637 abstracts) with 93 different biomarkers in different samples. We found 24 parameters that were increased only in active TB (TGF-α, CSF3, CSF2, CCL1 [I-309], IL-7, TGF-β1, CCL3 [MIP-1α], sIL-2R, TNF-β, CCL7 [MCP-3], IFN-α, fractalkine, I-TAG, CCL8 [MCP-2], CCL21 [6Ckine], PDGF, IL-22, VEGF-A, LXA4, PGE2, PGF2α, sCD163, sCD14, and 15-Epi-LXA4), five were elevated in LTBI (IL-5, IL-17F, IL-1, CCL20 [MIP-3α], and ICAM-1), and two substances were increased among uninfected individuals (IL-23 and basic FGF). We found high heterogeneity between studies including failure to account for the time/illness of the individuals studied; varied samples and protocols; different clinical classification of TB; different laboratory methods for IP detection, which in turn leads to variable units of measurement and assay sensitivities; and selection bias regarding TST and booster effect. None of the studies adjusted the analysis for the effect of ethnicity.

Conclusions

It is mandatory to harmonize the study of immune parameters for LTBI diagnosis. This systematic review is registered with PROSPERO CRD42017073289.

Clinical characteristics and managements of severe hand, foot and mouth disease caused by enterovirus A71 and coxsackievirus A16 in Shanghai, China

Background

Hand, foot and mouth disease (HFMD) is a transmissible infectious disease caused by human enteroviruses (EV). Here, we described features of children with severe HFMD caused by EV-A71 or coxsackievirus A16 (CV-A16) in Shanghai, China.

Methods

Severe EV-A71 or CV-A16 caused HFMD children admitted to the Xinhua Hospital from January 2014 and December 2016, were recruited retrospectively to the study. Symptoms and findings at the time of hospitalization, laboratory tests, treatments, length of stay and residual findings at discharge were systematically recorded and analyzed.

Results

Of 19,995 children visited clinic service with probable HFMD, 574 children (2.87%) were admitted, 234 children (40.76%) were confirmed with EV-A71 (90/574) or CV-A16 (144/574) disease. Most (91.02%) of the patients were under 5 years. Initial clinical symptoms of EV-A71 and CV-A16 cases were: fever > 39 °C in 81 (90%) and 119 (82.63%), vomiting in 31 (34.44%) and 28 (19.44%), myoclonic twitching in 19 (21.11%) and 11(7.64%), startle in 21 (23.33%) and 20 (13.69%), respectively. Serum levels of interleukin-1β (IL-1β), IL-2, IL-6, IL-8, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) were significantly upregulated in severe HFMD subjects. Forty-seven children (20.08%) treated with intravenous gamma globulin (IVIG) showed decreased duration of illness episodes. All children were discharged without complications.

Conclusions

EV-A71 and CV-A16 accounted 40.76% of admitted HFMD during 2014 to 2016 in Xinhua Hospital. IVIG appeared to be beneficial in shortening the duration of illness episodes of severe HFMD.

Application of ImmunoScore Model for the Differentiation between Active Tuberculosis and Latent Tuberculosis Infection as Well as Monitoring Anti-tuberculosis Therapy

Tuberculosis (TB) is a leading global public health problem. To achieve the end TB strategy, non-invasive markers for diagnosis and treatment monitoring of TB disease are urgently needed, especially in high-endemic countries such as China. Interferon-gamma release assays (IGRAs) and tuberculin skin test (TST), frequently used immunological methods for TB detection, are intrinsically unable to discriminate active tuberculosis (ATB) from latent tuberculosis infection (LTBI). Thus, the specificity of these methods in the diagnosis of ATB is dependent upon the local prevalence of LTBI. The pathogen-detecting methods such as acid-fast staining and culture, all have limitations in clinical application. ImmunoScore (IS) is a new promising prognostic tool which was commonly used in tumor. However, the importance of host immunity has also been demonstrated in TB pathogenesis, which implies the possibility of using IS model for ATB diagnosis and therapy monitoring. In the present study, we focused on the performance of IS model in the differentiation between ATB and LTBI and in treatment monitoring of TB disease. We have totally screened five immunological markers (four non-specific markers and one TB-specific marker) and successfully established IS model by using Lasso logistic regression analysis. As expected, the IS model can effectively distinguish ATB from LTBI (with a sensitivity of 95.7% and a specificity of 92.1%) and also has potential value in the treatment monitoring of TB disease.

Research on tuberculosis in tribal areas in India: A systematic review

BACKGROUND

Tuberculosis (TB) remains a major public health problem in resource-poor countries including India. Scientific knowledge is used to guide policy and practice. There is however, a limited, systematically collected data required for guiding the scale-up of interventions particularly amongst vulnerable populations including tribal groups in the country. In view of this, a systematic review of the TB research studies carried out in tribal areas of different parts of the country was undertaken.

OBJECTIVE

To undertake a systematic review of the TB research studies carried out in tribal areas of India between 1996 and 2016.

METHODS

A systematic review of English articles published between 1996 and 2016 on any aspect of TB was done through internet searches using Literature search EndNote programme. The words used for searching were tuberculosis, India, tribal, indigenous, disadvantaged, adivasi. The most common topics classified as annual risk of tuberculosis infection (ARTI), prevalence of TB, laboratory studies, clinical symptoms of TB, risk factors for TB, knowledge attitude practice, community Directly Observed Treatment (DOT) providers, performance of Revised National Tuberculosis Control Programme (RNTCP), and drug resistant TB. Classification was also done on the basis of the type of tribe studied and place of study conducted. A total of 47 studies identified through the search were included in the review.

RESULTS

Of the 47 studies reviewed, 12 were on TB prevalence, 7 were laboratory studies, four on ARTI and 5 on performance of RNTCP in tribal areas. Among these, majority (23 studies) of the tribal studies did not mention the type of tribe. Ten studies were conducted among Saharia, a particularly vulnerable tribal group in the Indian state of Madhya Pradesh mainly by the National Institute for Research on Tribal Health, five were among the mixed tribes and very few on other tribes.

CONCLUSION

The systematic review indicates that the research studies on TB among tribal population are very few. There is a need to invest and encourage researcher to work on the research plans for the control of TB in tribal areas.

Alternative Quantiferon cytokines for diagnosis of children with active tuberculosis and HIV co-infection in Ghana

IFN-γ release assays (IGRAs) often present false-negative or indeterminate results in children with tuberculosis. HIV co-infection may contribute to decreased sensitivity of IGRAs by impairing T-cell IFN-γ expression. Measurement of alternative cytokines in QuantiFERON^® (QFT) supernatants can circumvent the IFN-γ-dependency and may improve QFT sensitivity. We aimed to identify additional cytokines from QFT supernatants for detection of Mycobacterium tuberculosis infection in children with tuberculosis and HIV co-infection from Ghana. Concentrations of 18 cytokines in QFT supernatants from children (0-16 years) with tuberculosis concomitantly infected with HIV (n = 25) or without HIV (n = 24) from Ghana were measured using cytometric bead array (CBA). 29% of the children showed positive IFN-γ test results, and five cytokines, i.e., IL-6, IL-21, TNF-α, IL-1α and IP-10, detected M. tuberculosis infection with comparable or, for IL-6, with significantly higher sensitivity (59%). Increased age and HIV co-infection were associated with decreased cytokine induction, and especially IL-21 and IP-10 were less prevalent in HIV co-infected children with tuberculosis. Combined cytokine analyses increased proportions of positive tests, and a four-cytokine subset (i.e., IL-6, IL-21, IFN-γ, IL-1α) predicted 78% of the children with tuberculosis correctly. Combined evaluation of IFN-γ and alternative cytokines improved IGRA-sensitivity in children with tuberculosis.