The relationship between host defense peptides and adrenal steroids. An account of reciprocal influences.

AIM: ß-defensins 2 and -3 (HBD-2 and HBD-3) and cathelicidin LL-37 are host defense peptides (HDPs) that play a crucial role in the immune response against mycobacteria. Given our former studies in tuberculosis patients wherein their plasma levels of such peptides correlated with steroid hormone concentrations, we now studied the reciprocal influence of cortisol and/or dehydroepiandrosterone (DHEA) on HDPs biosynthesis and LL-37 on adrenal steroidogenesis. MAIN METHODS: Cultures of macrophages derived from the THP-1 line were treated with cortisol (10-6M) and/or DHEA (10-6M and 10-7M) and stimulated with irradiated M. tuberculosis (Mi) or infected M. tuberculosis strain H37Rv to assess cytokine production, HDPs, reactive oxygen species (ROS) and colony forming units. Cultures of NCI-H295-R adrenal line were treated with LL37 (5, 10, and 15 µg/ml) for 24 h to further measure cortisol and DHEA levels together with steroidogenic enzyme transcripts. KEY FINDINGS: In macrophages, M. tuberculosis produced an increase of IL-1ß, TNFα, IL-6, IL-10, LL-37, HBD-2, and HBD-3 levels, irrespective of DHEA treatment. Adding cortisol to M. tuberculosis-stimulated cultures (with or without DHEA) decreased the amounts of these mediators, compared to only stimulated cultures. Although M. tuberculosis reduced ROS levels, DHEA increased these values in addition to diminishing intracellular mycobacterial growth (no matter cortisol treatment). In turn, studies on adrenal cells showed that LL-37 reduced the production of cortisol and DHEA besides modifying transcripts for some steroidogenic enzymes. SIGNIFICANCE: while adrenal steroids seem to influence the production of HDPs, the former compounds are also likely to modulate adrenal biogenesis.

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, ß-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 ß-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 ß-defensin-2 in presence of increased amounts of ß-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 ß-defensin-3 in plasma from untreated severe patients as did their dehydroepiandrosterone and LL-37 values. Increased presence of ß-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 ß-defensin-2 but increased ß-defensin-3 and LL-37 levels, suggests a differential role of these HDPs in a situation characterized for its better protective response.

Immune response triggered by Trypanosoma cruzi infection strikes adipose tissue homeostasis altering lipid storage, enzyme profile and adipokine expression.

Adipose tissue is a target of Trypanosoma cruzi infection being a parasite reservoir during the chronic phase in mice and humans. Previously, we reported that acute Trypanosoma cruzi infection in mice is linked to a severe adipose tissue loss, probably triggered by inflammation, as well as by the parasite itself. Here, we evaluated how infection affects adipose tissue homeostasis, considering adipocyte anabolic and catabolic pathways, the immune-endocrine pattern and the possible repercussion upon adipogenesis. During in vivo infection, both lipolytic and lipogenic pathways are profoundly affected, since the expression of lipolytic enzymes and lipogenic enzymes was intensely downregulated. A similar pattern was observed in isolated adipocytes from infected animals and in 3T3-L1 adipocytes infected in vitro with Trypanosoma cruzi. Moreover, 3T3-L1 adipocytes exposed to plasmas derived from infected animals also tend to downregulate lipolytic enzyme expression which was less evident regarding lipogenic enzymes. Moreover, in vivo-infected adipose tissue reveals a pro-inflammatory profile, with increased leucocyte infiltration accompanied by TNF and IL-6 overexpression, and adiponectin downregulation. Strikingly, the nuclear factor PPAR-γ is strongly decreased in adipocytes during in vivo infection. Attempts to favor PPAR-γ-mediated actions in the adipose tissue of infected animals using agonists failed, indicating that inflammation or parasite-derived factors are strongly involved in PPAR-γ inhibition. Here, we report that experimental acute Trypanosoma cruzi infection disrupts both adipocyte catabolic and anabolic metabolism secondary to PPAR-γ robust downregulation, tipping the balance towards to an adverse status compatible with the adipose tissue atrophy and the acquisition of an inflammatory phenotype.

Dysregulated Network of Immune, Endocrine and Metabolic Markers is Associated to More Severe Human Chronic Chagas Cardiomyopathy.

Individuals who are infected with Trypanosoma cruzi develop chronic Chagas cardiomyopathy (CCC), which is a complication involving a series of immune pathogenetic mechanisms, although an association between immune and metabolic alterations was more recently proposed. Accordingly, we investigated the immuno-metabolic response in chagasic patients and their possible influence on CCC pathogenesis. To this end, T. cruzi-seropositive (asymptomatic or with CCC) and sero-negative individuals were studied. Serum tumour necrosis factor (TNF)-α, interleukin (IL)-6, adipocytokines and the expression of their receptors in peripheral blood mononuclear cell (PBMC) were evaluated, together with other factors influencing the immune response. CCC patients showed major metabolic and hormonal abnormalities, in parallel with increased IL-6 and leptin serum levels. TNF-α receptor s, leptin and adiponectin receptors (ObR and Adipo-Rs respectively), as well as PPAR-γ expression in PBMCs from CCC patients were compatible with a counteracting response leading to an unfavourable immune-metabolic profile. These results suggest that persistently increased levels of immune-metabolic pro-inflammatory mediators along with the adverse endocrine anti-inflammatory response of CCC individuals, may contribute to the underlying mechanisms dealing with myocardial tissue damage.

The impact of IFN-γ receptor on SLPI expression in active tuberculosis: association with disease severity.

Interferon (IFN)-γ displays a critical role in tuberculosis (TB), modulating the innate and adaptive immune responses. Previously, we reported that secretory leukocyte protease inhibitor (SLPI) is a pattern recognition receptor with anti-mycobacterial activity against Mycobacterium tuberculosis (Mtb). Herein, we determined whether IFN-γ modulated the levels of SLPI in TB patients. Plasma levels of SLPI and IFN-γ were studied in healthy donors (HDs) and TB patients. Peripheral blood mononuclear cells from HDs and patients with TB or defective IFN-γ receptor 1* were stimulated with Mtb antigen and SLPI, and IFN-γR expression levels were measured. Both SLPI and IFN-γ were significantly enhanced in plasma from those with TB compared with HDs. A direct association between SLPI levels and the severity of TB was detected. In addition, Mtb antigen stimulation decreased the SLPI produced by peripheral blood mononuclear cells from HDs, but not from TB or IFN-γR patients. Neutralization of IFN-γ reversed the inhibition of SLPI induced by Mtb antigen in HDs, but not in TB patients. Furthermore, recombinant IFN-γ was unable to modify the expression of SLPI in TB patients. Finally, IFN-γR expression was lower in TB compared with HD peripheral blood mononuclear cells. These results show that Mtb-induced IFN-γ down-modulated SLPI levels by signaling through the IFN-γR in HDs. This inhibitory mechanism was not observed in TB, probably because of the low expression of IFN-γR detected in these individuals.

Studies on the contribution of PPAR Gamma to tuberculosis physiopathology.

Introduction: Tuberculosis (TB) is a major health problem characterized by an immuno-endocrine imbalance: elevated plasma levels of cortisol and pro- and anti-inflammatory mediators, as well as reduced levels of dehydroepiandrosterone. The etiological agent, Mycobacterium tuberculosis (Mtb), is captured by pulmonary macrophages (Mf), whose activation is necessary to cope with the control of Mtb, however, excessive activation of the inflammatory response also leads to tissue damage. Glucocorticoids (GC) are critical elements to counteract the immunoinflammatory reaction, and peroxisome proliferator-activated receptors (PPARs) are also involved in this regard. The primary forms of these receptors are PPARϒ, PPARα, and PPARß/δ, the former being the most involved in anti-inflammatory responses. In this work, we seek to gain some insight into the contribution of PPARϒ in immuno-endocrine-metabolic interactions by focusing on clinical studies in pulmonary TB patients and in vitro experiments on a Mf cell line. Methods and results: We found that TB patients, at the time of diagnosis, showed increased expression of the PPARϒ transcript in their peripheral blood mononuclear cells, positively associated with circulating cortisol and related to disease severity. Given this background, we investigated the expression of PPARϒ (RT-qPCR) in radiation-killed Mtb-stimulated human Mf. The Mtb stimulation of Mf derived from the human line THP1 significantly increased the expression of PPARϒ, while the activation of this receptor by a specific agonist decreased the expression of pro- and anti-inflammatory cytokines (IL-1ß and IL-10). As expected, the addition of GC to stimulated cultures reduced IL-1ß production, while cortisol treatment together with the PPARϒ agonist lowered the levels of this proinflammatory cytokine in stimulated cultures. The addition of RU486, a glucocorticoid receptor antagonist, only reversed the inhibition produced by the addition of GC. Conclusion: The current results provide a stimulating background for further analysis of the interconnection between PPARs and steroid hormones in the context of Mtb infection.

The Immunoregulatory Actions of DHEA in Tuberculosis, A Tool for Therapeutic Intervention?

Dehydroepiandrosterone (DHEA) is an androgen synthesized by the adrenal cortex, which is an intermediary in the biosynthesis of sex hormones, such as testosterone and estradiol. DHEA mostly circulates as a conjugated ester, in the form of sulfate (DHEA-S). There exist several endogenous factors able to influence its synthesis, the most common ones being the corticotrophin-releasing hormone (CRH), adrenocorticotrophin (ACTH), growth factors, and proinflammatory cytokines, among others. Like other steroid hormones, DHEA, can alter the functioning of immune cells and therefore the course of diseases exhibiting an immune-inflammatory component, mostly from autoimmune or infectious nature. We herein review the role played by DHEA during a major infectious disease like tuberculosis (TB). Data recorded from TB patients, mouse models, or in vitro studies show that DHEA is likely to be implied in better disease control. This provides a stimulating background for carrying out clinical studies aimed at assessing the usefulness of DHEA as an adjuvant in TB patients.

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-1ß, 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-1ß, 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 ß being higher in severe ones, who also displayed increased GRß 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.

mRNA expression of alpha and beta isoforms of glucocorticoid receptor in peripheral blood mononuclear cells of patients with tuberculosis and its relation with components of the immunoendocrine response.

We have analyzed the expression of glucocorticoid receptor (GR) isoforms by real time RT-qPCR in PBMCs from 19 controls (HCo) and 28 TB patients (8 mild; 12 moderate; 8 severe), HIV(-) and similar sex and age distribution. mRNA hGRα/ß ratios were found higher in TB patients respect to those in HCo. However, when analyzing for disease severity such overall trend was at the expense of mild and moderate patients, with severe cases showing a lower mRNA hGRα/ß ratio with respect to the other patient groups. This suggested some degree of resistance to endogenous glucocorticoids in patients with severe TB, since hGRαα dimer mediates the biological functions of GC, with the GRß isoform acting as an inhibitor of GC activity. Levels of IL-6, IL-18, IFN-γ and Cortisol were significantly increased in severe and moderate cases, whereas DHEA values were found decreased in them (p<0.05 respect to HCo). Analysis on the relationship between plasma levels of these immuno-endocrine mediators with the mRNA expression of hGRα and hGRß showed that IL-6 was positively associated with hGRα in mild TB patients (p<0.01), whereas a negative correlation between IFN-γ and hGRß was observed in severe cases (p<0.01). As regard to hormones, DHEA was positively associated with hGRα in moderate and severe cases (p<0.01). This group also showed a negative correlation between hGRα and Cortisol/DHEA ratios (p<0.05). Changes in the systemic levels of cytokine and adrenal hormones are likely to affect GR expression in a differential fashion and according to the amount of pulmonary involvement.

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-1ß, 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-1ß 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-1ß 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.

A clinical correlate of the dysregulated immunoendocrine response in human tuberculosis.

Wasting is a prominent feature in tuberculosis (TB), but its underlying mechanisms are incompletely understood. Immunoendocrine disturbances may be linked to the consumption state of TB patients, since hormones and cytokines can affect energy expenditure and metabolism. To approach this possibility, we have determined leptin, IL-18, and adrenal steroid plasma levels and body mass index (BMI) in newly diagnosed patients with mild, moderate and severe pulmonary TB, household contacts (HHC), and healthy controls (HCO). HHC displayed higher levels of leptin than HCO and TB patients. TB patients showed a gradual decrease in BMI and leptin concentrations with increasing disease severity, whereas a positive correlation between this hormone and BMI was found in the HCO group. Cortisol concentrations tended to be higher in TB patients. DHEA levels were decreased in TB patients and to a lesser extent in HHC, whereas IL-18 concentration was significantly increased in patients with severe disease. Since HHC are known to cause a latent subclinical infection, it seems clear that controlled tuberculous infection and manifested TB disease are accompanied by a dissimilar profile of immunoendocrine markers.

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/GRß; 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.

Tuberculosis, the Disrupted Immune-Endocrine Response and the Potential Thymic Repercussion As a Contributing Factor to Disease Physiopathology.

Upon the pathogen encounter, the host seeks to ensure an adequate inflammatory reaction to combat infection but at the same time tries to prevent collateral damage, through several regulatory mechanisms, like an endocrine response involving the production of adrenal steroid hormones. Our studies show that active tuberculosis (TB) patients present an immune-endocrine imbalance characterized by an impaired cellular immunity together with increased plasma levels of cortisol, pro-inflammatory cytokines, and decreased amounts of dehydroepiandrosterone. Studies in patients undergoing specific treatment revealed that cortisol levels remained increased even after several months of initiating therapy. In addition to the well-known metabolic and immunological effects, glucocorticoids are involved in thymic cortical depletion with immature thymocytes being quite sensitive to such an effect. The thymus is a central lymphoid organ supporting thymocyte T-cell development, i.e., lineage commitment, selection events and thymic emigration. While thymic TB is an infrequent manifestation of the disease, several pieces of experimental and clinical evidence point out that the thymus can be infected by mycobacteria. Beyond this, the thymic microenvironment during TB may be also altered because of the immune-hormonal alterations. The thymus may be then an additional target of organ involvement further contributing to a deficient control of infection and disease immunopathology.

The clinical recovery of tuberculosis patients undergoing specific treatment is associated with changes in the immune and neuroendocrine responses.

Tuberculosis (TB) caused by Mycobacterium tuberculosis is a health problem worldwide. Patients with pulmonary TB show a neuro-immune-endocrine imbalance characterized by an impaired cellular immunity together with increased plasma levels of cortisol, pro- and anti-inflammatory cytokines and markedly decreased dehydroepiandrosterone (DHEA) levels. Extending these findings, we now investigated the immune-endocrine profile of TB patients undergoing specific treatment. Patients (n = 24) were bled at diagnosis (T0), 2, 4, 6 months after treatment initiation and 3 months following its completion. At T0, TB patients showed increased plasma levels of interleukin-6 (IL-6), C reactive protein, interferon-gamma (IFN-γ) and transforming growth factor beta (TGF-ß). These mediators decreased during treatment, reaching levels similar to those from healthy controls (n = 26). Specific treatment led to an increased lymphoproliferative response along with clinical improvement. Newly diagnosed patients had low levels of DHEA, with increased cortisol amounts and cortisol/DHEA ratio, which normalized upon specific treatment. As regards glucocorticoid receptors (GR), TB patients at diagnosis presented a reduced mRNA GRα/GRß ratio in their peripheral blood mononuclear cells. Furthermore, multivariate analysis showed that cortisol/DHEA ratio was positively associated with inflammatory mediators for which this ratio may constitute a disease biomarker. Anti-mycobacterial treatment results in a better immune-endocrine scenario for the control of physiopathological processes accompanying disease development and hence implied in clinical recovery.

miR-30c is specifically repressed in patients with active pulmonary tuberculosis.

Tuberculous pleurisy (PLTB) is a common form of extrapulmonary tuberculosis. It often resolves without chemotherapy being hence considered a rather benign manifestation of the disease. Patients with PLTB mount an effective anti-mycobacterial response, unlike those with active pulmonary TB (pTB) that were shown to present an imbalance in plasma immune and endocrine mediators. In this work, we explored whether expression of the active isoform of the glucocorticoid receptor (hGRα) in the context of the inflammatory-anti-inflammatory responses of TB patients may be associated to microRNA levels. As expected, the inflammatory response triggered in patients coexists with increased circulating cortisol and altered hGRα levels in the peripheral blood mononuclear cells. However, while hGRα expression is significantly downregulated in PLTB, its levels in pTB patients are higher within the control values. These results point out to the existence of an additional mechanism tending to preserve hGRα levels probably to deal with the chronic inflammation observed in pTB. In this regard, we found that miR-30c is strongly downregulated in mononuclear cells of pTB patients compared to PLTB cases, showing an expression profile opposite to that seen with hGRα. Interestingly, low levels of miR-30c are specific for this active form of TB, as its expression is not altered in mononuclear cells from either healthy controls or patients with tuberculous or non-tuberculous pleurisy. Moreover, miR-30c and hGRα also showed an inverse expression pattern in M. tuberculosis-stimulated THP-1 macrophage cultures. In sum, our studies identify miR-30c as a specific correlate of pulmonary manifestations of TB, potentially involved in the altered glucocorticoid sensitivity observed in these patients.

Trypanosoma cruzi Experimental Infection Impacts on the Thymic Regulatory T Cell Compartment.

The dynamics of regulatory T cells in the course of Trypanosoma cruzi infection is still debated. We previously demonstrated that acute murine T. cruzi infection results in an impaired peripheral CD4+Foxp3+ T cell differentiation due to the acquisition of an abnormal Th1-like phenotype and altered functional features, negatively impacting on the course of infection. Moreover, T. cruzi infection induces an intense thymic atrophy. As known, the thymus is the primary lymphoid organ in which thymic-derived regulatory T cells, known as tTregs, differentiate. Considering the lack of available data about the effect of T. cruzi infection upon tTregs, we examined tTreg dynamics during the course of disease. We confirmed that T. cruzi infection induces a marked loss of tTreg cell number associated to cell precursor exhaustion, partially avoided by glucocorticoid ablation- and IL-2 survival factor depletion. At the same time, tTregs accumulate within the CD4 single-positive compartment, exhibiting an increased Ki-67/Annexin V ratio compared to controls. Moreover, tTregs enhance after the infection the expression of signature markers (CD25, CD62L and GITR) and they also display alterations in the expression of migration-associated molecules (α chains of VLAs and chemokine receptors) such as functional fibronectin-driven migratory disturbance. Taken together, we provide data demonstrating profound alterations in tTreg compartment during acute murine T. cruzi infection, denoting that their homeostasis is significantly affected. The evident loss of tTreg cell number may compromise the composition of tTreg peripheral pool, and such sustained alteration over time may be partially related to the immune dysregulation observed in the chronic phase of the disease.

Effect of cortisol and/or DHEA on THP1-derived macrophages infected with Mycobacterium tuberculosis.

Tuberculosis (TB) is a major health problem requiring an appropriate cell immune response to be controlled. Macrophages play a central role in the response against Mycobacterium tuberculosis (Mtb). Given our prior studies in which adrenal steroids were found to modify the cellular immune responses from TB patients, it was sensible to analyze the immunomodulatory capability of cortisol and DHEA on macrophages infected with Mtb. The human macrophage-like THP-1 cells were infected with the H37Rv strain of Mtb and treated with Cortisol and DHEA at different doses. We monitored phagocytosis, intracellular-bacterial growth, autophagosoma formation, as well as cytokine gene expression and production. Cultures exposed to cortisol showed a decreased production of IL-1ß, TNF-α, with DHEA being unable to modify the pattern of cytokine production or to reverse the cortisol inhibitory effects. Interestingly the intra-macrophagic bacterial burden was found reduced by DHEA treatment. While this effect was not related to a different cytokine pattern, in terms their production or mRNA expression, DHEA treatment did promote autophagy in Mtb-infected macrophages, irrespective of Cortisol presence. In essence, the better control of Mtb load by DHEA-treated macrophages seems to be dependent on an autophagic mechanism. The present results are relevant for two reasons as autophagy is not only important for clearance of mycobacteria but also for the prevention of tissue damage.

Increased frequency of CD4+ CD25+ FoxP3+ T regulatory cells in pulmonary tuberculosis patients undergoing specific treatment and its relationship with their immune-endocrine profile.

Tuberculosis (TB) is a major health problem requiring an appropriate cell immune response (IR) to be controlled. Since regulatory T cells (Tregs) are relevant in IR regulation, we analyzed Tregs variations throughout the course of TB treatment and its relationship with changes in immune-endocrine mediators dealing with disease immunopathology. The cohort was composed of 41 adult patients, 20 of them completing treatment and follow-up. Patients were bled at diagnosis (T0) and at 2 (T2), 4 (T4), 6 (T6), and 9 months following treatment initiation. Twenty-four age- and sex-matched healthy controls (HCo) were also included. Tregs (flow cytometry) from TB patients were increased at T0 (versus HCo P < 0.05), showing even higher values at T2 (versus T0 P < 0.01) and T4 (versus T0 P < 0.001). While IL-6, IFN-γ, TGF-ß (ELISA), and Cortisol (electrochemiluminescence, EQ) were augmented, DHEA-S (EQ) levels were diminished at T0 with respect to HCo, with cytokines and Cortisol returning to normal values at T9. Tregs correlated positively with IFN-γ (R = 0.868, P < 0.05) at T2 and negatively at T4 (R = -0.795, P < 0.05). Lowered levels of proinflammatory cytokines together with an increased frequency of Tregs of patients undergoing specific treatment might reflect a downmodulatory effect of these cells on the accompanying inflammation.

The implication of pro-inflammatory cytokines in the impaired production of gonadal androgens by patients with pulmonary tuberculosis.

BACKGROUND: The chronic nature of tuberculosis and the protracted immuno-inflammatory reactions are implied in a series of metabolic and immune-endocrine changes accompanying the disease. We explored components from the hypothalamous-pituitary-gonadal axis and their relationship with cytokines involved in disease immunopathology, in male TB patients. METHODS: Plasma samples from 36 active untreated pulmonary TB male patients were used to determine TNF-α, IFN-γ, TGF-ß, IL-6, cortisol, dehydroepiandrosterone, testosterone, progesterone, estradiol, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by ELISA. Healthy controls corresponded to 21 volunteers without contact with TB patients and similar age (40 ± 16,8 years). Testicular histological samples from necropsies of patients dying from TB were immune-stained for IL-1ß, TNF-α, IL-6 and IFN-γ. The TM3 mouse Leydig cell line was incubated with recombinants TNF-α, IFN-γ and TGF-ß, supernatants were collected and used to measure testosterone by ELISA. RESULTS: Patients showed decreased levels of testosterone in presence of high amounts of LH, together with augmented IFN-γ, IL-6 and TGF-ß levels. Testicular histological sections showed abundant presence of IL-1ß, TNF-α, IL-6 and IFN-γ in interstitial macrophages, Sertoli cells and some spermatogonia. In vitro treatment of Leydig cells with these cytokines led to a remarkable reduction of testosterone production.

Altered microRNA expression levels in mononuclear cells of patients with pulmonary and pleural tuberculosis and their relation with components of the immune response.

Different lines of evidence demonstrate that microRNAs (miRNAs) play an important role in host-pathogen interactions. In this study we investigated the expression patterns of several miRNAs, most of them involved in regulating inflammatory responses, in patients with tuberculosis (TB). In order to understand the events occurring at the site of infection, we employed mononuclear cells obtained from both peripheral blood (PBMC) and pleural fluids (PFMC) of patients. Interestingly, we found that the miRNA signature of each compartment is different, with a strong down-regulation in PFMCs of miR-223, miR-144* and miR-421. In addition, we observed that miR-146a expression is also down-regulated in tuberculosis patients, both in PBMCs and PFMCs while miR-424 levels are elevated only in the peripheral compartments. We also showed that systemic expression of these miRNAs changes upon specific treatment and is associated with IL-6 levels, a cytokine playing a substantial role in TB immunopathology. Present results contribute to a better knowledge of the host responses in TB pathogenesis, pointing out the role of miRNAs in this disease.