Host-Based Biomarkers in Saliva for the Diagnosis of Pulmonary Tuberculosis in Children: A Mini-Review

Non-invasive diagnosis of pulmonary tuberculosis and predictive potential for treatment outcomes via miR-146a and miR-155 levels

Use of microRNAs is a promising area for non-invasive diagnosis of pulmonary tuberculosis (TB). Herein, we aimed to investigate the diagnostic potential of miR-146a and miR-155 in pulmonary TB and their predictive potential for patient treatment outcomes. The study included 60 patients with active TB, 50 patients with latent TB, and 50 individuals without TB infection. The patients with active TB were given standard treatment regimens and followed up for treatment outcomes. The serum and sputum expression levels of miR-146a and miR-155 were quantified by qRT-PCR. The patients presenting active TB had highest relative expressions of miR-146a and miR-155 in the serum and sputum compared to patients presenting latent TB and healthy volunteers (p  <  0.0001). When miR-146a and miR-155 levels in the serum and sputum as tools to diagnose TB, all values of area under the receiver operating characteristics curve (AUROC) were beyond 0.9. The patients with active TB and presenting unfavorable treatment outcomes were demonstrated with higher relative expressions of miR-146a and miR-155 in the serum and sputum than those presenting favorable treatment outcomes (p < 0.0001). When these two miRNAs as tools to predict treatment outcomes, values of AUROC were beyond 0.85. The study unveils detections of miR-146a and miR-155 in the serum and sputum may be a promising non-invasive method to diagnose TB and further to predict treatment outcomes following anti-TB treatment.

Overview of mucosal immunity and respiratory infections in children: a focus on Africa

PURPOSE OF REVIEW

Given the substantial burden of respiratory tract infections (RTIs) on global paediatric health, enhancing our understanding of mucosal immunity can help us advance mucosal biomarkers for diagnosis, prognosis and possible interventions in order to improve health outcomes. This review highlights the critical role of mucosal immunity in paediatric RTIs and recent advances in mucosal interventions, which offer promising strategies to improve outcomes.

RECENT FINDINGS

The significant burden of paediatric RTIs and growing interest in mucosal immunity advanced our understanding of the role of the respiratory mucosal immune system in protective immunity against RTIs. Studies show that sub-Saharan Africa is disproportionately affected by paediatric RTIs with poverty-associated factors such as human immunodeficiency virus (HIV) and malnutrition as risk factors. Emerging evidence highlights the important role of the respiratory microbiome and mucosal innate and adaptive immune responses in protective immunity against RTIs.

SUMMARY

The growing interest in mucosal immunity in RTIs has not only advanced our understanding of the overall immune responses in RTIs but also created opportunities to improve RTI care through translation of knowledge from these studies into diagnostics, therapeutics, and vaccines.

A DNA Methylation Signature From Buccal Swabs to Identify Tuberculosis Infection

BACKGROUND

Tuberculosis (TB) is among the largest infectious causes of death worldwide, and there is a need for a time- and resource-effective diagnostic methods. In this novel and exploratory study, we show the potential of using buccal swabs to collect human DNA and investigate the DNA methylation (DNAm) signatures as a diagnostic tool for TB.

METHODS

Buccal swabs were collected from patients with pulmonary TB (n = 7), TB-exposed persons (n = 7), and controls (n = 9) in Sweden. Using Illumina MethylationEPIC array, the DNAm status was determined.

RESULTS

We identified 5644 significant differentially methylated CpG sites between the patients and controls. Performing the analysis on a validation cohort of samples collected in Kenya and Peru (patients, n = 26; exposed, n = 9; control, n = 10) confirmed the DNAm signature. We identified a TB consensus disease module, significantly enriched in TB-associated genes. Last, we used machine learning to identify a panel of 7 CpG sites discriminative for TB and developed a TB classifier. In the validation cohort, the classifier performed with an area under the curve of 0.94, sensitivity of 0.92, and specificity of 1.

CONCLUSIONS

In summary, the result from this study shows clinical implications of using DNAm signatures from buccal swabs to explore new diagnostic strategies for TB.

Non-sputum-based samples and biomarkers for detection of Mycobacterium tuberculosis: the hope to improve childhood and HIV-associated tuberculosis diagnosis

In 2014, the World Health Organisation (WHO) published target product profiles (TPP) for development of novel tuberculosis (TB) diagnostics. One of the key highlights is the need for point-of-care non-sputum-based tests capable of detecting all forms of TB through identification of characteristic biomarkers or biosignatures. Compared to the limitations associated with sputum-based TB tests, non-sputum samples are easy to collect, non-invasive, with potential to improve TB diagnosis among children and among people living with HIV/AIDS (PLHIV). This review gives an overview of the existing evidence on TB diagnostic studies of non-sputum-based samples collected non-invasively from or through the oral-gastrointestinal tract (GI) and nasal pharynx regions of humans and the biomarkers detected. We further summarized evidence of these biomarkers and sample types from research done in paediatric and PLHIV. The review identified; saliva, cough aerosols, oral swabs, oral wash, dental plaque, tongue swabs, face mask sampling, exhaled breath, and stool, as the non-sputum samples investigated. These biomarkers can be categorized into Deoxyribose Nucleic Acid (DNA), Ribonucleic Acid (RNA), inflammatory, antigen-antibody, volatile and non-volatile compounds, microbiome and microbiota. The biomarkers identified were derived both from the host and pathogen. Similar biomarkers were identified in the general population, children and among PLHIV. These biomarkers have been detected by either already approved simple point of care or sophisticated devices. Differences in methodology and sample types investigated, small sample size of children and PLHIV populations, bias due to confounding factors, were some of the identified challenges in these studies. There is need to conduct larger and standardized multi centre studies to evaluate non-sputum-based biomarker-based tests in children and PLHIV.

Exploring the Role of Extracellular Vesicles in the Pathogenesis of Tuberculosis

Tuberculosis (TB) remains a significant global health concern, necessitating accurate diagnosis and treatment monitoring. Extracellular vesicles (EVs), including exosomes, play crucial roles in disease progression, with their associated genes serving as potential biomarkers and therapeutic targets. Leveraging publicly available RNA-Seq datasets of TB patients and healthy controls (HCs), to identify differentially expressed genes (DEGs) and their associated protein-protein interaction networks and immune cell profiles, the common EV-related DEGs were identified and validated in the GSE42830 and GSE40553 datasets. We have identified nine common EV-related DEGs (SERPINA1, TNFAIP6, MAPK14, STAT1, ITGA2B, VAMP5, CTSL, CEACAM1, and PLAUR) upregulated in TB patients. Immune cell infiltration analysis revealed significant differences between TB patients and HCs, highlighting increased proportions of various immune cells in TB patients. These DEGs are involved in crucial cellular processes and pathways related to exocytosis and immune response regulation. Notably, VAMP5 exhibited excellent diagnostic performance (AUC-0.993, sensitivity-93.8%, specificity-100%), with potential as a novel biomarker for TB. The EV-related genes can serve as novel potential biomarkers that can distinguish between TB and HCs. VAMP5, which functions in exosome biogenesis and showed significant upregulation in TB, can be targeted for therapeutic interventions and treatment outcomes.

A united model for diagnosing pulmonary tuberculosis with random forest and artificial neural network

Background: Pulmonary tuberculosis (PTB) is a chronic infectious disease and is the most common type of TB. Although the sputum smear test is a gold standard for diagnosing PTB, the method has numerous limitations, including low sensitivity, low specificity, and insufficient samples.

Methods: The present study aimed to identify specific biomarkers of PTB and construct a model for diagnosing PTB by combining random forest (RF) and artificial neural network (ANN) algorithms. Two publicly available cohorts of TB, namely, the GSE83456 (training) and GSE42834 (validation) cohorts, were retrieved from the Gene Expression Omnibus (GEO) database. A total of 45 and 61 differentially expressed genes (DEGs) were identified between the PTB and control samples, respectively, by screening the GSE83456 cohort. An RF classifier was used for identifying specific biomarkers, following which an ANN-based classification model was constructed for identifying PTB samples. The accuracy of the ANN model was validated using the receiver operating characteristic (ROC) curve. The proportion of 22 types of immunocytes in the PTB samples was measured using the CIBERSORT algorithm, and the correlations between the immunocytes were determined.

Results: Differential analysis revealed that 11 and 22 DEGs were upregulated and downregulated, respectively, and 11 biomarkers specific to PTB were identified by the RF classifier. The weights of these biomarkers were determined and an ANN-based classification model was subsequently constructed. The model exhibited outstanding performance, as revealed by the area under the curve (AUC), which was 1.000 for the training cohort. The AUC of the validation cohort was 0.946, which further confirmed the accuracy of the model.

Conclusion: Altogether, the present study successfully identified specific genetic biomarkers of PTB and constructed a highly accurate model for the diagnosis of PTB based on blood samples. The model developed herein can serve as a reliable reference for the early detection of PTB and provide novel perspectives into the pathogenesis of PTB.

Pediatric Tuberculosis Diagnostics: Present and Future

The current diagnostic abilities for the detection of pediatric tuberculosis are suboptimal. Multiple factors contribute to the under-diagnosis of intrathoracic tuberculosis in children, namely the absence of pathognomonic features of the disease, low bacillary loads in respiratory specimens, challenges in sample collection, and inadequate access to diagnostic tools in high-burden settings. Nonetheless, the 2020s have witnessed encouraging progress in the area of novel diagnostics. Recent WHO-endorsed rapid molecular assays hold promise for use in service decentralization strategies, and new policy recommendations include stools as an alternative, child-friendly specimen for testing with the GeneXpert assay. The pipeline of promising assays in mid/late-stage development is expanding, and novel pediatric candidate biomarkers based on the host immune response are being identified for use in diagnostic and triage tests. For a new test to meet the pediatric target product profiles prioritized by the WHO, it is key that the peculiarities and needs of the hard-to-reach pediatric population are considered in the early planning phases of discovery, validation, and implementation studies.

Fetuin as a potential serum biomarker to detect subclinical shedder of bovine paratuberculosis

Paratuberculosis (PTB) is a chronic contagious granulomatous enteritis of wild and domestic ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). PTB causes considerable economic losses to the dairy industry through decreased milk production and premature culling. PTB-affected cattle undergo a subclinical stage without clinical signs and initiate fecal shedding of MAP into the environment. Current diagnostic tools have low sensitivity for the detection of subclinical PTB infection. Therefore, alternative diagnostic tools are required to improve the diagnostic sensitivity of subclinical PTB infection. In this study, we performed ELISA for three previously identified host biomarkers (fetuin, alpha-1-acid glycoprotein, and apolipoprotein) and analyzed their diagnostic performance with conventional PTB diagnostic methods. We observed that serum fetuin levels were significantly lowered in the subclinical shedder and clinical shedder groups than in the healthy control group, indicating its potential utility as a diagnostic biomarker for bovine PTB. Also, fetuin showed an excellent discriminatory power with an AUC = 0.949, a sensitivity of 92.6%, and a specificity of 94.4% for the detection of subclinical MAP infection. In conclusion, our results demonstrated that fetuin could be used as a diagnostic biomarker for enhancing the diagnostic sensitivity for the detection of subclinical MAP infections that are difficult to detect based on current diagnostic methods.