Immune Biomarker Combinations for Diagnosis Monitoring of Latent Tuberculosis Infection

Research Article

J Dis Markers. 2023; 8(1): 1050.

Immune Biomarker Combinations for Diagnosis Monitoring of Latent Tuberculosis Infection

Araujo Zaida2, Lopez-Ramos Juan Ernesto1, Enciso-Moreno Jose Antonio3, de Waard Jacobus Henri4, Rivas-Santiago Bruno5, Vanegas Magnolia6 and Patarroyo Manuel Alfonso6,7,8

1Laboratorio de Inmunologia de Enfermedades Infecciosas, Instituto de Biomedicina Dr, Jacinto Convit, Universidad Central de Venezuela, San Jose, Apartado 4043, Caracas 1010A, Caracas DC - Venezuela

2Centro de Estudios Cientiificos y Tecnologicos No. 18, Instituto Politecnico Nacional, Zacatecas, 98160 Zacatecas - Mexico

3Facultad de Química, Universidad Autónoma de Querétaro, México

4Laboratorio de Tuberculosis, Instituto de Biomedicina “Dr. Jacinto Convit”, Universidad Central de Venezuela, Venezuela

5Unidad de Investigación Biomédica de Zacatecas, Instituto Mexicano del Seguro Social, México

6Department of Molecular Biology and Immunology, Fundación Instituto de Inmunología de Colombia (FIDIC), Colombia

7Faculty of Medicine, Universidad Nacional de Colombia, Colombia

8Health Sciences Division, Main Campus, Universidad Santo Tomás, Colombia

*Corresponding author: Araujo Zaida Laboratorio de Inmunología de Enfermedades Infecciosas, Instituto de Biomedicina “Dr. Jacinto Convit”, Universidad Central de Venezuela, San José, Apartado 4043, Caracas 1010A, Caracas DC - Venezuela

Received: December 30, 2022; Accepted: February 03, 2023; Published: February 10, 2023

Abstract

Objective: Global Tuberculosis (TB) eradication efforts must also focus on detecting and treating cases of Latent TB Infection (LTBI); persons with LTBI can progress to active TB at any time, often many years or even decades after the initial infection, thereby serving as a source of new infections.

Methods: The aim was evaluated the diagnostic accuracy of the combination of serological host biomarkers that may support the differentiation between LTBI and Non-Infected (NI) individuals. A total of 182 adult Warao Amerindians were included; cases with LTBI (n=103) and Non-Infected (NI) individuals (n=79). The Real-time quantitative PCR (qPCR) was performed on all peripheral blood samples from Warao Amerindians and analyzed transcriptional immune biomarkers (i.e., IFN-γ, CD14, MMP-9, CCR5, CCL11, CXCL9/MIG, and uPAR/PLAUR proteins) under stimulation condition with ESAT-6, CFP10, and TB7.7 Mycobacterium Tuberculosis (Mtb)-antigens. Additionally, Enzyme-Linked Immunosorbent Assays (ELISA) were performed for evaluating host biomarker anti-synthetic peptides (5 ESAT-6 and 17 Ag85A synthetic peptides) covering Mtb antigen sequences.

Results: The approach’s diagnostic information was compared using Receiver Operating Characteristic (ROC) curves. The ROC analysis revealed high biosignature discriminative ability for the relative gene expression of MMP-9 high levels (AUC=0.799 ± 0.071: 0.640 - 0.917, 95% CI), p < 0.002) between LTBI and NI; additionally IgG anti-synthetic peptide; ESAT-6 P-12037 (AUC=0.640; 0.545-0.735 95% CI, p<0.007) allowed differentiation between LTBI and NI or healthy ones.

Conclusion: The accuracy of the MMP-9/IgG anti-P-12037 combination could have a high discriminative ability for diagnosing LTBI; such an approach holds promise for further validation.

Keywords: Tuberculosis (TB); Latent Tuberculosis Infection (LTBI); Warao Indigenous; Biomarker

Abbreviations: TB: Tuberculosis; ROC: Receiver Operating Characteristic; AUC: Area Under Curve; CI: Confidence Interval; WHO: World Health Organization; Mtb: Mycobacterium Tuberculosis; TST: Tuberculin Skin Test; ELISA: Enzyme-Linked ImmunoSorbent Assay; IgG: Immunoglobulin G; OD: Optical Density

Introduction

Tuberculosis (TB) is one of the top 10 causes of death worldwide [1]. The World Health Organization (WHO) report 2021 stated that reduced access to Active TB (ATB) diagnosis and treatment has resulted in an increase in TB deaths [1]. One third of the world’s population is latently infected with Mycobacterium Tuberculosis (Mtb) or Latent TB Infection (LTBI) and up to 10% of infected individuals develop active TB in their lifetime [2,3]. In Amerindian population (indigenous) tend to have much higher rates of TB in comparison with the general (non-indigenous) population [4]. Recently, it has been reported that in the admixed population of the Brazilian Amazon region; Amerindian ancestry in the 20–60% range was found to be the principal risk factor for increased susceptibility to TB [5].

Actually, the incidence of ATB by Mtb in Venezuela is increasing; [1] between 2014 and 2019 there was a rebound in cases (Creole or non-indigenous and indigenous individuals) that raised the rate to 39 per 100,000 inhabitants (39/100,000); the indigenous people (5.6%) being the most affected; so registering an abrupt increase in incidence in the last five years, going to exceed the levels reported three decades ago [1]. The National Integrated TB Control Program of Venezuela records the variables “indigenous” and “ethnicity” among the patient data; this has allowed the program to know the detailed statistics of the cases registered in indigenous patients. The Warao indigenous population is the second most important ethnic of the country with 48.771 inhabitants (6.7% of indigenous people), they mainly live in wooden houses raised on stilts along the Orinoco river’s banks (Delta’s rural areas). Data from the Coordination of the Regional Tuberculosis Control Program of the Delta Amacuro state reported that the incidence in the Warao population is 13 times higher than in the non-indigenous population and 19 times higher than the national rate [6-9]. Among the main factors that maintain the TB endemic are poverty, social inequality and inequity, migration, the impact of the HIV pandemic, and the lack of operational capacity for the detection of LTBI and ATB cases [10-12].

There are no diagnostic gold standards for LTBI, and all existing tests for LTBI are indirect approaches that provide immunological evidence of host sensitization to TB antigens [13,14]. Two tests currently used to diagnose LTBI, which are the Tuberculin Skin Test (TST) and the blood Interferon Gamma Release Assay (IGRA´s), both of which do not distinguish between ATB and LTBI. Positive response to IGRAs otherwise seem to confer only a small risk of reactivation (10–20 per 1000 person-years), which is similar to that of a positive TST [14]; however, the search for diagnostic and prognostic elements for LTBI continues. Clinical TB manifestations are closely related to the host immune response against Mtb. In individuals with different stages of Mtb infections, IgG antibody responses to Mtb antigens like ESAT-6 and Ag85 are frequently detected [15]. Additionally, biomarkers of innate and (Th1-) cell-mediated immunity are also observed [13,14]. Thus detection of multiple biomarkers non specific and specific for humoral as well as cellular immunity is necessary. Recently, we identified host biomarkers associated with LTBI in M. tuberculosis antigen-stimulated whole blood assays and IgG antibody serum from a TB endemic population in Delta’s Orinoco. A host biomarker signature of IgG anti-P-12037, MMP-9, CCR5 and CCL11 was identified; high IgG anti-P-12037 and MMP-9 and low CCR5 and CCL11 levels, relative to controls, were associated with LTBI [15,16].

Biomarkers are urgently needed to indicate progression from latent infection to clinical disease, to predict the risk of reactivation after cure, and to provide accurate end points for drug and vaccine trials [17-24]. Forty-eight analytes were evaluated by Luminex Assay in plasma obtained from whole blood stimulated cells. ROC curve analysis revealed that the combinations of 7 biomarkers resulted in the accurate prediction of 88.89% of ATB patients, 82.35% of subjects with LTBI and 90% of non-TB individuals [25]. These studies highlighted the importance of assessing multiple biomarkers for providing better understanding of protective biomarker profiles associated with resolution of clinical and subclinical infections in TB. The research proposal was evaluated the diagnostic accuracy of the combination of serological host biomarkers for identifying LTBI among Warao Amerindian communities, which would improve early diagnosis and allow a focus on detecting and treating cases of LTBI for improving TB control in Venezuela.

Methods

Study Population

A transversal study was carried out among individuals of both sexes from the Warao indigenous communities. A total of 182 adult Warao indigenous were included; cases with latent TB infection or LTBI (n=103) and non-infected (NI) individuals (n=79). The group of Warao indigenous in contact with active TB patients and the Tuberculin Skin Test (TST) positive, according to the WHO and the National Tuberculosis Control Program of Venezuela indigenous positive having ≥10 mm indurations were classified as LTBI; NI indigenous were also subjected to TST. Peripheral blood samples from both groups were drawn for QuantiFERON–TB Gold In-Tube (QFT-IT) testing (Commercial test QuantiFERON–TB Gold In-Tube, Cellestis, Victoria, Australia). Inclusion criteria took into account the recommendation previously reported [16].

Ethical Approval and Consent to Participate

This study was approved by the Institute of Biomedicine Central University of Venezuela Research Ethics Committee (protocol number FONACIT-2013002319/2013). All participating individuals signed voluntary informed consent forms.

Clinical Features, Microscopy, the Tuberculin Skin Test and Chest Radiograph

Individuals who had evidence of clinical symptoms suggesting pulmonary TB infection were excluded after having been diagnosed as having pulmonary TB using at least one of the following previously applied criteria published [16,26-28]. Individuals who had been prescribed immunosuppressive drugs (i.e., corticosteroids, azathioprine, and cyclophosphamide) were also excluded, as were participants who did not sign an informed consent agreement.

Isolated Blood Cells and Gene Biomarker Amplifications

Blood samples under non-stimulation conditions and stimulation conditions with M. tuberculosis antigens, Early Secretory Antigenic Target-6 (ESAT-6), Culture Filtrate Protein-10 (CFP10), and TB antigen 7.7 (TB7.7) were studied. A real-time reverse transcription polymerase chain reaction (RT-qPCR) assay was performed as previously reported [16].

Synthetic Peptides and Serological Assays

The solid-phase multiple peptide system was used for synthesising 22 peptides based on M. tuberculosis ESAT-6 and Ag85A amino acid (aa) sequences as previously reported [29,30]. The IgG levels against ESAT-6 and Ag85A peptides were determined in serum by ELISA assay as previously reported [15].

Statistical Analysis

Receiver Operating Characteristic (ROC) curves analysis, Student’s t-test, Fisher’s exact test, Mann Whitney test, Kruskal-Wallis and Dunn’s multiple comparison tests were performed as previously reported [15,16]. A scattergram was plotted using GraphPad Prism software version 5.02 (Trial version, GraphPadSofware, Inc., San Diego, USA). Statistically significant differences were those having a ≤0.05 p-value.

Results

The baseline characteristics of the participants are summarized in (Table 1). The TST+ status was significantly different between LTBI (78.0%) and NI (0.0%) groups, p< 0.0001; also for QuantiFERON–TB Gold In-Tube (QFT-IT) between LTBI (QFT-IT positive, 22.0%) and NI (QFT-IT negative, 0.0%) groups, p<0.001 (Table 1), and for CXRs, it was significantly different between LTBI (100.0%) and NI (0.0%) groups, p<0.0001 (Table 1).

Figure 1 shows the Optical Density (OD) distribution for the three best IgG anti-peptides between Warao indigenous LTBI and NI individuals; the IgG reactivity against the peptide is shown as values of the mean ± standard deviation (X ± SD). Mann Whitney test was used for comparing isotype reactivity differences between LTBI and NI groups. The LTBI’s IgG reactivity was high against 2 Ag85A peptides; P-10997 (0.538 ± 0.358) and P-11006 (0.493 ± 0.251) as compared with NI individuals (0.501 ± 0.327) (Figure 1B) and (0.461 ± 0.261) (Figure 1C), respectively; however, was no found significant difference. A significant difference was only found between LTBI (0.616 ± 0.244) and NI (0.512 ± 0.229) p<0.001 (Figure 1A) against M. tuberculosis ESAT-6 P-12037 amino acid (76-95 aa; ISEAGQAMASTEGNVTGMFA), (Figure 2), and ATB against M. tuberculosis ESAT-6 P-12035 amino acid (data not shown) (41-60 aa; AAWGGSGSEAYQGVQQKWDA), (Figure 2).