Differential expression of genes regulated by the glucocorticoid receptor pathway in patients with pulmonary tuberculosis

AIMS

Previous studies in TB patients showed an immuno-endocrine imbalance characterized by a disease-severity associated increase in plasma levels of proinflammatory cytokines and glucocorticoids (GCs). To analyze the potential immunomodulatory effect of circulating GCs over peripheral blood mononuclear cells (PBMC) from TB patients, we investigated the expression of positively (anti-inflammatory-related genes ANXA1; FKBP51; GILZ, NFKBIA, and NFKBIB) and negatively (inflammatory genes: IL-6, IL-1β, and IFN-γ) Glucocorticoids Receptors (GR)-regulated genes. Plasma concentrations of cytokines and hormones, together with specific lymphoproliferation were also assessed.

MATERIALS AND METHODS

Gene expression was quantified by RT-qPCR, specific lymphoproliferation by ³H-thymidine incorporation, whereas plasma cytokines and hormones levels by ELISA.

KEY FINDINGS

Transcripts of ANXA1, GILZ, NFKBIB, and NFKBIA appeared significantly increased in patients, whereas FKBP51, IL-6, IL-1β, and NF-κB remained unchanged. Upon analyzing according to disease severity, mRNA levels for ANXA1 and NFKBIB were even higher in moderate and severe patients. GILZ was increased in moderate cases, with NFKBIA and IL-1 β being higher in severe ones, who also displayed increased GRβ transcripts. TB patients had reduced plasma DHEA concentrations together with increased pro and anti-inflammatory cytokines (IFN-γ, IL-6, and IL-10) cortisol and cortisol/DHEA ratio, more evident in progressive cases, in whom their PBMC also showed a decreased mycobacterial-driven proliferation. The cortisol/DHEA ratio and GRα expression were positively correlated with GR-regulated genes mainly in moderate patients.

SIGNIFICANCE

The increased expression of cortisol-regulated anti-inflammatory genes in TB patients-PBMC, predominantly in progressive disease, seems compatible with a relatively insufficient attempt to downregulate the accompanying inflammation.

Increased levels of circulating LPS during Tuberculosis prevails in patients with advanced pulmonary involvement

Our earlier studies in tuberculosis (TB) patients indicate that in those where the process evolves to a larger pulmonary involvement, the immune endocrine response may promote an unfavorable environment. Chronic infectious diseases, and their persistent proinflammatory response, may affect mucosal barriers integrity favoring the translocation of gastrointestinal bacteria, leading to an increase of circulating lipopolysaccharides (LPS). Consequently, we quantified LPS levels in TB patients, with different degrees of pulmonary involvement, and controls (Co) and analyzed the possible relationship between LPS and inflammatory mediators i.e., C reactive protein (CRP), interleukin 6 (IL-6) and Interferon-gamma (IFN-γ), Erythrocyte Sedimentation Rate (ESR), steroid hormones (Cortisol and Dehydroepiandrosterone, DHEA), and inflammatory transcripts from peripheral blood mononuclear cells (IL-1β, IL-6, IFN-γ). LPS was assessed by the Limulus amoebocyte lysate assay and the ELISA technique was used to quantify hormones and cytokines in the plasma samples. Cytokine transcripts from PBMC were evaluated by qRT-PCR. Non-parametric tests were used. LPS levels were increased in TB patients, as did levels of CRP, IL-6, IFN-γ, cortisol and ESR. Severe patients had the highest amounts of circulating LPS; with moderate and severe cases showing much higher levels of CRP, ESR, IL-6, IFN-γ and cortisol/DHEA ratio, as an endocrine imbalance. Only in PBMC from severe cases was mRNA for IL-1β increased. Correlation analysis showed that levels of LPS from severe patients were positively associated with IL-6 and IFN-γ plasma concentrations and with IL-1β transcripts, while IL-6 had a positive correlation with the cortisol/DHEA ratio. The higher levels of circulating LPS during progressive TB may emerge as a contributing factor for the persistence of the greater immune endocrine imbalance distinctive of advanced disease, which might suggest a vicious cycle among LPS, inflammation and endocrine imbalance.

Evidence for a More Disrupted Immune-Endocrine Relation and Cortisol Immunologic Influences in the Context of Tuberculosis and Type 2 Diabetes Comorbidity

Pulmonary tuberculosis (PTB), caused by Mycobacterium tuberculosis (Mtb), is a major health problem worldwide, further aggravated by the convergence of type 2 diabetes mellitus (DM) which constitutes an important risk factor for TB development. The worse scenario of patients with PTB and DM may be partly related to a more unbalanced defensive response. As such, newly diagnosed PTB patients with DM (TB+DM, n = 11) or not (TB, n = 21), as well as DM (n = 18) patients and pair matched controls (Co, n = 22), were investigated for the circulating immuno-endocrine-metabolic profile (ELISA), along with studies in peripheral blood mononuclear cells (PBMC) analyzing transcript expression (RT-qPCR) of mediators involved in glucocorticoid functionality. Given the hyperglycemic/hypercortisolemic scenario of TB+DM patients, PBMC were also exposed to stress-related cortisol concentrations (0.1 and 1 μM) and supraphysiologic glucose doses (10, 20, and 40 mM) and assessed for the specific response against Mtb stimulation (lymphoproliferation, -thymidine incorporation-, and cytokine production -bead-cytometry). All TB patients displayed increased plasma amounts of cortisol, growth hormone -hGH-, and proinflammatory mediators. In turn, TB+DM showed even higher levels of interferon gamma -IFN-γ- and hGH (vs. TB), or IL-6, C reactive protein, cortisol and hGH (vs. DM). Both DM groups had equally augmented values of IL-10. All TB patients showed decreased dehydroepiandrosterone- sulfate concentrations, even more in TB+DM cases. Leptin was also decreased in both TB cases, particularly in the TB group, revealing a lower body mass index, as well. Unlike PBMC from TB cases showing a decreased relationship between the glucocorticoids receptor (GR) isoforms (GRα/GRβ; functional isoform/negative isoform), cells from TB+DM patients had no changes in this regard, along with an increased expression of 11-beta hydroxysteroid dehydrogenase type-1, the enzyme facilitating intracellular cortisone to cortisol conversion. TB+DM patients also showed an increased Mtb antigen-driven lymphoproliferation. Compared to TB, DM and HCo counterparts, PBMC from TB+DM patients had a biased Th1 response to Mtb stimulation (increased IL-2 and IFN-γ production), even when exposed to inhibitory cortisol doses. TB+DM patients show a more unbalanced immuno-endocrine relationship, respect the non-diabetic counterparts, with a relative deficiency of cortisol immunomodulatory influences, despite their more favorable microenvironment for cortisol-mediated immune effects.

Evidence that changes in antimicrobial peptides during tuberculosis are related to disease severity, clinical presentation, specific therapy and levels of immune-endocrine mediators

Given the role of host defense peptides (HDPs) in the defensive response against mycobacteria, we analyzed the circulating levels of LL-37, β-defensin-2 and -3 in newly diagnosed patients with pulmonary (PTB) or pleural tuberculosis (PLTB) in whom measurements of pleural fluids were also performed. Severe PTB patients displayed higher circulating amounts of β-defensin-3, statistically different from controls, further decreasing upon antimycobacterial treatment. LL-37 concentrations appeared within the normal range at diagnosis, but tended to increase during treatment, becoming statistically upon its completion in moderate cases. PLTB patients revealed decreased levels of β-defensin-2 in presence of increased amounts of β-defensin-3 and LL-37; in their plasma or pleural fluids. Considering the immune-endocrine dysregulation of tuberculosis, we also performed correlation analysis detecting positive associations between levels of cortisol, IL-6 and β-defensin-3 in plasma from untreated severe patients as did their dehydroepiandrosterone and LL-37 values. Increased presence of β-defensins, may represent an attempt to improve defensive mechanisms; which also take part in the inflammatory reaction accompanying TB, reinforced by the association with immune-endocrine mediators. The divergent profile of PLTB patients, decreased β-defensin-2 but increased β-defensin-3 and LL-37 levels, suggests a differential role of these HDPs in a situation characterized for its better protective response.