Identification of Mycobacterium tuberculosis Peptides in Serum Extracellular Vesicles from Persons with Latent Tuberculosis Infection

Abstract

Identification of biomarkers for latent Mycobacterium tuberculosis infection and risk of progression to tuberculosis (TB) disease are needed to better identify individuals to target for preventive therapy, predict disease risk, and potentially predict preventive therapy efficacy. Our group developed multiple reaction monitoring mass spectrometry (MRM-MS) assays that detected M. tuberculosis peptides in serum extracellular vesicles from TB patients. We subsequently optimized this MRM-MS assay to selectively identify 40 M. tuberculosis peptides from 19 proteins that most commonly copurify with serum vesicles of patients with TB. Here, we used this technology to evaluate if M. tuberculosis peptides can also be detected in individuals with latent TB infection (LTBI). Serum extracellular vesicles from 74 individuals presumed to have latent M. tuberculosis infection (LTBI) based on close contact with a household member with TB or a recent tuberculin skin test (TST) conversion were included in this study. Twenty-nine samples from individuals with no evidence of TB infection by TST and no known exposure to TB were used as controls to establish a threshold to account for nonspecific/background signal. We identified at least one of the 40 M. tuberculosis peptides in 70 (95%) individuals with LTBI. A single peptide from the glutamine synthetase (GlnA1) enzyme was identified in 61/74 (82%) individuals with LTBI, suggesting peptides from M. tuberculosis proteins involved in nitrogen metabolism might be candidates for pathogen-specific biomarkers for detection of LTBI. The detection of M. tuberculosis peptides in serum extracellular vesicles from persons with LTBI represents a potential advance in the diagnosis of LTBI.

New Biomarker in Chagas Disease: Extracellular Vesicles Isolated from Peripheral Blood in Chronic Chagas Disease Patients Modulate the Human Immune Response

“…Once referred to as “platelet dust” by Wolf in 1967, extracellular vesicles (EVs) have now been extensively studied due to their role in intercellular communication and physiological and pathological conditions [ 11 – 13 ]. Their role in assessing disease progression as well as in establishing a prognosis suggests a potential use for them as biomarkers in noncommunicable diseases, such as cancer, but also in infectious diseases such as latent tuberculosis infection [ 14 – 16 ].…”

Composition and Clinical Significance of Exosomes in Tuberculosis: A Systematic Literature Review

“…Exosomes have been suggested to be applicable in TB diagnostics and vaccine innovation [ 4 , 47 , 50 , 62 , 63 , 71 , 73 , 82 , 84 , 85 , 86 , 87 , 88 , 89 ]. Proteomics analysis of exosomes released by Mycobacterium -infected cells have indicated the presence of lipoproteins [ 39 ], some of which were reported as a virulence factors.…”

“…Studies suggests that TB bacteria may use exosomes as a mechanism of releasing molecules into host cells [ 88 , 89 , 91 ], which could be therefore, considered as potential virulence factors involved in the pathogenesis of TB. Another proteomic analysis of exosomes revealed broad range of proteins within the mycobacterial exosomes [ 63 , 86 ].…”

“…A study by Castro-Garza and colleagues detected HSPx protein in sera of TB patients, suggesting the identification of recent latent TB infection for TB prevention and control strategy [ 98 ]. Furthermore, Mehaffy C et al in 2020 detected HSPx in sera of latent TB infection [ 88 ]. Another study reported Mtb H37Rv culture filtrate proteins including the most components of immunologically important ESAT-6 family [ 84 ].…”

The genetic proteome: Using genetics to inform the proteome of mycobacterial pathogens

“…Although numerous MS instruments are capable of performing targeted proteomics, triple quadrupoles are the most common, sensitive, and precise platform for performing these experiments, and they are extensively applied to study mycobacterial pathogenesis [18,79,80,82]. Targeted proteomics is the dominant form of LC-MS/MS in clinical proteomics used for diagnostic, drug, and detection [85][86][87].…”