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

AIM

β-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-1β, 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.

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.

Circulating DHEA-S levels and major cardiovascular outcomes in chronic Chagas cardiomyopathy: A prospective cohort study

OBJECTIVE

To analyze the association of circulating dehydroepiandrosterone sulfate (DHEA-S) levels with cardiovascular outcomes in patients with chronic Chagas cardiomyopathy (CCM) diagnosis.

BACKGROUND

DHEA-S is among the main endogenous steroid hormones. Some studies have suggested a relevant role of this hormone in infections and the setting of CCM. Nevertheless, no study has evaluated the prognostic role of DHEA-S in CCM patients.

METHODS

Prospective cohort study. Patients with CCM and reduced ejection fraction were included. We explored the association of DHEA-S levels with NT-proBNP levels and echocardiographic variables using linear regression models. Next, by using Cox Proportional Hazard models, we examined whether levels of DHEA-S could predict a composite outcome (CO) including all-cause mortality, cardiac transplantation, and implantation of a left ventricular assist device (LVAD).

RESULTS

Seventy-four patients were included (59% males, median age: 64 years). After adjustment for confounding factors, high DHEA-S levels were associated with better LVEF, lower left atrium volume, end-systolic volume of the left ventricle and lower NT-proBNP levels. 43% of patients experienced the CO during a median follow-up of 40 months. Increased levels of DHEA-S were associated with a lower risk of developing the CO (HR 0.43; 95%CI 0.21-0.86). Finally, adding DHEA-S to the multivariate model did not improve the prediction of the CO, but substituting NT-proBNP in the model with DHEA-S showed similar performance.

CONCLUSIONS

In patients with CCM, higher DHEA-S levels were associated with lower mortality, heart transplantation, and LVAD implantation. Further larger studies are required to confirm our results and assess causality.

Exploring immunomodulation by endocrine changes in Lady Windermere syndrome

Lung disease due to nontuberculous mycobacteria (NTM) occurs with disproportionate frequency in postmenopausal women with a unique phenotype and without clinically apparent predisposing factors. Dubbed 'Lady Windermere syndrome', the phenotype includes low body mass index (BMI), tall stature and higher than normal prevalence of scoliosis, pectus excavatum and mitral valve prolapse. Although the pathomechanism for susceptibility to NTM lung disease in these patients remains uncertain, it is likely to be multi-factorial. A role for the immunomodulatory consequences of oestrogen deficiency and altered adipokine production has been postulated. Altered levels of adipokines and dehydroepiandrosterone have been demonstrated in patients with NTM lung disease. Case reports of NTM lung disease in patients with hypopituitarism support the possibility that altered endocrine function influences disease susceptibility. This paper catalogues the evidence for immunomodulatory consequences of predicted endocrine changes in Lady Windermere syndrome, with emphasis on the immune response to NTM. Collectively, the data warrant further exploration of an endocrine link to disease susceptibility in Lady Windermere syndrome.

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.

Immunoendocrine interactions during HIV-TB coinfection: implications for the design of new adjuvant therapies

Worldwide, around 14 million individuals are coinfected with both tuberculosis (TB) and human immunodeficiency virus (HIV). In coinfected individuals, both pathogens weaken immunological system synergistically through mechanisms that are not fully understood. During both HIV and TB infections, there is a chronic state of inflammation associated to dramatic changes in immune cytokine and endocrine hormone levels. Despite this, the relevance of immunoendocrine interaction on both the orchestration of an effective immune response against both pathogens and the control of the chronic inflammation induced during HIV, TB, or both infections is still controversial. The present study reviews immunoendocrine interactions occurring during HIV and TB infections. We also expose our own findings on immunoendocrine cross talk in HIV-TB coinfection. Finally, we evaluate the use of adrenal hormones and their derivatives in immune-therapy and discuss the use of some of these compounds like the adjuvant for the prevention and treatment of TB in HIV patients.

Normal estrogen, but low dehydroepiandrosterone levels, in women with pulmonary Mycobacterium avium complex. A preliminary study

RATIONALE

For unclear reasons, the phenotypical hosts for nontuberculous mycobacterial lung infection are often thin, elderly, white women without underlying lung disease. As these women are usually postmenopausal, we hypothesized that a state of relative hormone deficiency may predispose some women to pulmonary nontuberculous mycobacterial infection.

OBJECTIVES

To conduct a prospective cross-sectional study to assess for alterations in systemic levels of sex hormones in patients with confirmed pulmonary Mycobacterium avium complex infection compared with healthy control subjects.

METHODS

Female patients with pulmonary M. avium complex infection (n = 35) were recruited along with similar-aged control subjects (n = 27) without lung disease from the general population of our institution. Levels of dehydroepiandrosterone-sulfate (DHEA-S), estrone, and ultrasensitive estradiol were measured from sampled blood.

MEASUREMENTS AND MAIN RESULTS

DHEA-S levels of patients with M. avium complex infection were significantly lower than control subjects (mean 33 μg/dl vs. 59 μg/dl, P = 0.001). No significant difference was found in the levels of estrone (mean, 27 pg/ml vs. 28 pg/ml, P = 0.665) or ultrasensitive estradiol (mean, 9 pg/ml vs. 9 pg/ml, P = 0.364). Patients with M. avium complex had a lower body mass index (BMI) than control subjects (mean, 22 vs. 26, P = 0.001). There was no association between levels of DHEA-S, estrone, or estradiol, and BMI or age.

CONCLUSIONS

Women with M. avium complex infection had lower DHEA-S levels, but not lower estrogen levels, compared with control subjects. There was no relationship between BMI and hormone levels in the study population. Further study of these hormonal effects on immune function in nontuberculous mycobacterial infection is warranted.

Adverse neuro-immune-endocrine interactions in patients with active tuberculosis

The nervous, endocrine and immune systems play a crucial role in maintaining homeostasis and interact with each other for a successful defensive strategy against injurious agents. However, the situation is different in long-term diseases with marked inflammation, in which defensive mechanisms become altered. In the case of tuberculosis (TB), this is highlighted by several facts: an imbalance of plasma immune and endocrine mediators, that results in an adverse environment for mounting an adequate response against mycobacteria and controlling inflammation; the demonstration that dehidroepiandrosterone (DHEA) secretion by a human adrenal cell line can be inhibited by culture supernatants from Mycobacterium tuberculosis-stimulated peripheral blood mononuclear cells - PBMC - of TB patients, with this effect being partly reverted when neutralizing transforming growth factor-β in such supernantants; the in vitro effects of adrenal steroids on the specific immune response of PBMC from TB patients, that is a cortisol inhibition of mycobacterial antigen-driven lymphoproliferation and interferon-γ production as well as a suppression of TGF-β production in DHEA-treated PBMC; and lastly the demonstration that immune and endocrine compounds participating in the regulation of energy sources and immune activity correlated with the consumption state of TB patients. Collectively, immune-endocrine disturbances of TB patients are involved in critical components of disease pathology with implications in the impaired clinical status and unfavorable disease outcome. This article is part of a Special Issue entitled 'Neuroinflammation in neurodegeneration and neurodysfunction'.