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Host transcriptional response to TB preventive therapy differentiates two sub-groups of IGRA-positive individuals: in vitro (Quantiferon tube)-stimulated blood

ABSTRACT: We hypothesized that individuals with immunological sensitization to Mycobacterium tuberculosis (Mtb), conventionally regarded as evidence of latent tuberculosis infection (LTBI), would demonstrate binary responses to preventive therapy. This would reflect the differential immunological consequences of the sterilization of viable infection in those with an active Mtb infection versus no Mtb killing in those who, despite T cell recognition of Mtb antigens, did not harbor viable Mtb bacilli. We investigated the blood transcriptional profiles of 18 individuals with a positive IGRA result and known recent exposure to an index person with isoniazid and rifampicin susceptible pulmonary tuberculosis, at baseline, 2 weeks after initiating combined rifampicin/isoniazid (RH) preventive therapy and at treatment completion. Healthy control volunteers with no history of TB exposure and negative IGRA results were also included. RNA from unstimulated and M. tuberculosis peptide stimulated whole blood (from QuantiFERON TB1 and TB2 tubes) was measured using Agilent microarrays. A set of 474 genes showed the greatest interpersonal and temporal expression variability in antigen-stimulated blood. By performing longitudinal unsupervised clustering analysis with the subset of most variable genes, the IGRA+ participants were separated into two distinct groups. The IGRA-negative controls clustered within one of these groups suggesting that, in contrast to the other subgroup of IGRA+ individuals, RH had no discernible effect in this subgroup. 117 genes were significantly differentially expressed over time between these two groups, with the majority of them associated with immunological pathways known to be important in mycobacterial control. We contend that the different host RNA response reflects lack of Mtb viability in the group that clustered with the IGRA- unexposed healthy controls, and Mtb viability in the one that clustered away. Gene expression patterns in the blood of IGRA+ individuals emerging during the course of RH treatment which reflect Mtb viability could have major implications in the identification of risk of progression/reactivation, treatment stratification and clinical trials for LTBI therapy.

ORGANISM(S): Homo sapiens

PROVIDER: GSE153340 | GEO | 2021/01/19

REPOSITORIES: GEO

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Project description:We hypothesized that individuals with immunological sensitization to Mycobacterium tuberculosis (Mtb), conventionally regarded as evidence of latent tuberculosis infection (LTBI), would demonstrate binary responses to preventive therapy. This would reflect the differential immunological consequences of the sterilization of viable infection in those with an active Mtb infection versus no Mtb killing in those who, despite T cell recognition of Mtb antigens, did not harbor viable Mtb bacilli. We investigated the blood transcriptional profiles of 18 individuals with a positive IGRA result and known recent exposure to an index person with isoniazid and rifampicin susceptible pulmonary tuberculosis, at baseline, 2 weeks after initiating combined rifampicin/isoniazid (RH) preventive therapy and at treatment completion. Healthy control volunteers with no history of TB exposure and negative IGRA results were also included. RNA from unstimulated and M. tuberculosis peptide stimulated whole blood (from QuantiFERON TB1 and TB2 tubes) was measured using Agilent microarrays. A set of 474 genes showed the greatest interpersonal and temporal expression variability in antigen-stimulated blood. By performing longitudinal unsupervised clustering analysis with the subset of most variable genes, the IGRA+ participants were separated into two distinct groups. The IGRA-negative controls clustered within one of these groups suggesting that, in contrast to the other subgroup of IGRA+ individuals, RH had no discernible effect in this subgroup. 117 genes were significantly differentially expressed over time between these two groups, with the majority of them associated with immunological pathways known to be important in mycobacterial control. We contend that the different host RNA response reflects lack of Mtb viability in the group that clustered with the IGRA- unexposed healthy controls, and Mtb viability in the one that clustered away. Gene expression patterns in the blood of IGRA+ individuals emerging during the course of RH treatment which reflect Mtb viability could have major implications in the identification of risk of progression/reactivation, treatment stratification and clinical trials for LTBI therapy.

Project description:We report a study about differentially expressed small non-coding RNAs in the blood of humans harboring a latent (LTBI) or active tuberculosis (TB) infection in comparison with exposed controls (ExC) and treated LTBI (LTBItt). All non-TB subjects enrolled in this study were recent close contacts (rCt) of a newly diagnosed contagious TB cases enrolled in Rio de Janeiro, Brazil. The detailed methodology is described below. According to Brazilian Ministry of Health (BMH) guidelines, the screen to detect LTBI among recent contacts comprises a clinical evaluation by a physician specializing in pulmonary diseases, a chest X-ray (CXR), and a tuberculin skin test (TST, cut-off 5mm). Additionally, as part of this study, blood was collected for short- (st) and long-term (lt) IGRA. St-IGRA was performed by stimulating whole blood with the Mtb antigen ESAT6:CFP10 (expressed as a fusion protein) for 22h (cut-off 10pg/mL). Lt-IGRA involved stimulating peripheral blood mononuclear cells (PBMC) with this same antigen for 5 days (cut-off 100 pg/mL). Cases were defined as follows: ExC were recent close contacts of a TB index case and had a negative response to both TST and in house interferon-gamma release assay (IGRA) by stimulating blood-derived specimens with ESAT6:CFP10 indicating absence of Mycobacterium tuberculosis (Mtb) infection. LTBI was defined as (1) a TST induration >5 mm measured 72 h after intradermal injection of Mtb purified protein derivative (PPD) and (2) a positive IGRA response (to either st-IGRA or lt-IGRA, or both); if indicators of active disease were observed on CXR, (3) the absence of acid-fast bacilli (AFB) and negative Lowenstein-Jensen (LJ) culture of clinical specimens were also required. LTBItt consisted of LTBI cases (TST+/IGRA+ at enrollment) who completed a 6-month course of IPT. Their blood samples were collected >2 months after the end of isoniazid (INH) preventive treatment (IPT). Active TB was defined as (1) respiratory symptoms suggestive of TB, and/or (2) detection of AFB and/or positive LJ culture in sputum, bronchoalveolar lavage or biopsy, followed by (3) remission of symptoms upon anti-TB chemotherapy. Their blood samples were obtained before initiation of treatment. Whole blood was collected in PAXgene RNA tubes (PreAnalytiX, SWZ) and was stored at -80°C for <2 years before RNA extraction. sncRNA libraries. Total RNA (including small RNA) was isolated using the PAXgene Blood miRNA Kit (PreAnalytiX, SWZ), which is indicated for the isolation and purification of total RNA longer than 18 nucleotides. The manufacturer’s instructions were followed at both stages. Total RNA was quantified with a Nanodrop ND-1000 spectrophotometer (Thermo Scientific, EUA) and RNA integrity was assessed via agarose gel electrophoresis. One microgram RNA was used for cDNA library preparation (TruSeq Small RNA Sample Preparation® Kit, Illumina, San Diego, CA) following the manufacturer’s protocols. RNAseq was performed on an Illumina HiSeq® 2500 Sequencing System (Illumina, San Diego, CA), generating 50 bp single reads and ≈16 million reads passing filter for each sample. Pre-processing and differential expression. The FASTQ files were preprocessed (FastQC 0.11.2), adaptors trimmed (Cutadapt 1.7.1), aligned to the human genome (STAR 2.4.1d), counted (featureCounts 1.4.6) on the Oasis 2.0 web platform. Transcripts with <5 reads in at least one sample were excluded. Then, normalized and evaluated for differentially expressed (DE) transcripts using DESeq2 (v. 1.16) on the Oasis 2.0 web platform (https://oasis.dzne.de/).

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Host transcriptional response to TB preventive therapy differentiates two sub-groups of IGRA-positive individuals: in vitro (Quantiferon tube)-stimulated blood

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