Central intracrine DHEA synthesis in ageing-related neuroinflammation and neurodegeneration: therapeutic potential?

The potential of zebrafish as drug discovery research tool in immune-mediated inflammatory disease

Immune-mediated inflammatory disease (IMID) prevalence is estimated at 3-7% for Westernised populations, with annual incidence reported at almost 1 in 100 people globally. More recently, drug discovery approaches have been evolving towards more targeted therapies with an improved long-term safety profile, while the requirement for individualisation of medicine in complex conditions such as IMIDs, is acknowledged. However, existing preclinical models-such as cellular and in vivo mammalian models-are not ideal for modern drug discovery model requirements, such as real-time in vivo visualisation of drug effects, logistically feasible safety assessment over the course of a lifetime, or dynamic assessment of physiological changes during disease development. Zebrafish share high homology with humans in terms of proteins and disease-causing genes, with high conservation of physiological processes at organ, tissue, cellular and molecular level. These and other unique attributes, such as high fecundity, relative transparency and ease of genetic manipulation, positions zebrafish as the next major role player in IMID drug discovery. This review provides a brief overview of the suitability of this organism as model for human inflammatory disease and summarises the range of approaches used in zebrafish-based drug discovery research. Strengths and limitations of zebrafish as model organism, as well as important considerations in research study design, are discussed. Finally, under-utilised avenues for investigation in the IMID context are highlighted.

Common and distinct metabolomic markers related to immune aging in Western European and East African populations

In old age, impaired immunity causes high susceptibility to infections and cancer, higher morbidity and mortality, and poorer vaccination efficiency. Many factors, such as genetics, diet, and lifestyle, impact aging. This study aimed to investigate how immune responses change with age in healthy Dutch and Tanzanian individuals and identify common metabolites associated with an aged immune profile. We performed untargeted metabolomics from plasma to identify age-associated metabolites, and we correlated their concentrations with ex-vivo cytokine production by immune cells, DNA methylation-based epigenetic aging, and telomere length. Innate immune responses were impacted differently by age in Dutch and Tanzanian cohorts. Age-related decline in steroid hormone precursors common in both populations was associated with higher systemic inflammation and lower cytokine responses. Hippurate and 2-phenylacetamide, commonly more abundant in older individuals, were negatively correlated with cytokine responses and telomere length and positively correlated with epigenetic aging. Lastly, we identified several metabolites that might contribute to the stronger decline in innate immunity with age in Tanzanians. The shared metabolomic signatures of the two cohorts suggest common mechanisms of immune aging, revealing metabolites with potential contributions. These findings also reflect genetic or environmental effects on circulating metabolites that modulate immune responses.

The Multienzyme Complex Nature of Dehydroepiandrosterone Sulfate Biosynthesis

Dehydroepiandrosterone (DHEA), a precursor of steroid sex hormones, is synthesized by steroid 17-alpha-hydroxylase/17,20-lyase (CYP17A1) with the participation of microsomal cytochrome b5 (CYB5A) and cytochrome P450 reductase (CPR), followed by sulfation by two cytosolic sulfotransferases, SULT1E1 and SULT2A1, for storage and transport to tissues in which its synthesis is not available. The involvement of CYP17A1 and SULTs in these successive reactions led us to consider the possible interaction of SULTs with DHEA-producing CYP17A1 and its redox partners. Text mining analysis, protein-protein network analysis, and gene co-expression analysis were performed to determine the relationships between SULTs and microsomal CYP isoforms. For the first time, using surface plasmon resonance, we detected interactions between CYP17A1 and SULT2A1 or SULT1E1. SULTs also interacted with CYB5A and CPR. The interaction parameters of SULT2A1/CYP17A1 and SULT2A1/CYB5A complexes seemed to be modulated by 3'-phosphoadenosine-5'-phosphosulfate (PAPS). Affinity purification, combined with mass spectrometry (AP-MS), allowed us to identify a spectrum of SULT1E1 potential protein partners, including CYB5A. We showed that the enzymatic activity of SULTs increased in the presence of only CYP17A1 or CYP17A1 and CYB5A mixture. The structures of CYP17A1/SULT1E1 and CYB5A/SULT1E1 complexes were predicted. Our data provide novel fundamental information about the organization of microsomal CYP-dependent macromolecular complexes.

Harnessing the power of nutritional antioxidants against adrenal hormone imbalance-associated oxidative stress

Oxidative stress, resulting from dysregulation in the secretion of adrenal hormones, represents a major concern in human health. The present review comprehensively examines various categories of endocrine dysregulation within the adrenal glands, encompassing glucocorticoids, mineralocorticoids, and androgens. Additionally, a comprehensive account of adrenal hormone disorders, including adrenal insufficiency, Cushing's syndrome, and adrenal tumors, is presented, with particular emphasis on their intricate association with oxidative stress. The review also delves into an examination of various nutritional antioxidants, namely vitamin C, vitamin E, carotenoids, selenium, zinc, polyphenols, coenzyme Q10, and probiotics, and elucidates their role in mitigating the adverse effects of oxidative stress arising from imbalances in adrenal hormone levels. In conclusion, harnessing the power of nutritional antioxidants has the potential to help with oxidative stress caused by an imbalance in adrenal hormones. This could lead to new research and therapeutic interventions.

Longitudinal evaluation of dehydroepiandrosterone (DHEA), its sulfated form and estradiol with cancer-related cognitive impairment in early-stage breast cancer patients receiving chemotherapy

The purpose of this study is to elucidate how patient-reported cognitive symptoms manifest from variations in hormone levels or precursors such as dehydroepiandrosterone (DHEA) and its sulfated form [collectively termed as DHEA(S)] and to investigate their association in breast cancer survivors. Levels of estradiol and DHEA(S) were compared between early-stage breast cancer patients with and without cancer-related cognitive impairment (CRCI) during adjuvant chemotherapy. Data were analyzed from 242 patients (mean age ± SD = 50.8 ± 9.2 years) who had completed FACT-Cog v.3.0, blood draws and questionnaires. Regression model was used to fit the magnitude of change in each respective biomarker levels against overall cognitive impairment status while adjusting for clinically important covariates. There was reduction in mean plasma levels of estradiol and DHEAS during and towards the end of chemotherapy (p-values < 0.001). Compared to non-impaired patients, smaller magnitude of decline was observed in DHEA(S) levels in patients reporting CRCI, with significant association between decline in DHEAS levels and acute onset of CRCI at 6 weeks from baseline (adjusted β of 0.40, p-value of 0.02). In contrast, patients reporting CRCI showed greater magnitude of decline in estradiol compared to non-impaired patients, although this was not found to be statistically significant. There was an association between magnitude of change in biomarker levels with self-reported CRCI which suggests that the hormonal pathway related to DHEAS may be implicated in acute CRCI for breast cancer survivors. Our findings help to improve biological understanding of the pathway from which DHEAS may correlate with cognitive dysfunction and its impact on cancer survivors.

An update in toxicology of ageing

The field of ageing research has been rapidly advancing in recent decades and it had provided insight into the complexity of ageing phenomenon. However, as the organism-environment interaction appears to significantly affect the organismal pace of ageing, the systematic approach for gerontogenic risk assessment of environmental factors has yet to be established. This puts demand on development of effective biomarker of ageing, as a relevant tool to quantify effects of gerontogenic exposures, contingent on multidisciplinary research approach. Here we review the current knowledge regarding the main endogenous gerontogenic pathways involved in acceleration of ageing through environmental exposures. These include inflammatory and oxidative stress-triggered processes, dysregulation of maintenance of cellular anabolism and catabolism and loss of protein homeostasis. The most effective biomarkers showing specificity and relevancy to ageing phenotypes are summarized, as well. The crucial part of this review was dedicated to the comprehensive overview of environmental gerontogens including various types of radiation, certain types of pesticides, heavy metals, drugs and addictive substances, unhealthy dietary patterns, and sedentary life as well as psychosocial stress. The reported effects in vitro and in vivo of both recognized and potential gerontogens are described with respect to the up-to-date knowledge in geroscience. Finally, hormetic and ageing decelerating effects of environmental factors are briefly discussed, as well.

Targeting Stem Cells in Chronic Inflammatory Diseases

Mesenchymal stem cell (MSC) dysfunction is a serious complication in ageing and age-related inflammatory diseases such as type 2 diabetes mellitus. Inflammation and oxidative stress-induced cellular senescence alter the immunomodulatory ability of MSCs and hamper their pro-regenerative function, which in turn leads to an increase in disease severity, maladaptive tissue damage and the development of comorbidities. Targeting stem/progenitor cells to restore their function and/or protect them against impairment could thus improve healing outcomes and significantly enhance the quality of life for diabetic patients. This review discusses the dysregulation of MSCs' immunomodulatory capacity in the context of diabetes mellitus and focuses on intervention strategies aimed at MSC rejuvenation. Research pertaining to the potential therapeutic use of either pharmacological agents (NFкB antagonists), natural products (phytomedicine) or biological agents (exosomes, probiotics) to improve MSC function is discussed and an overview of the most pertinent methodological considerations given. Based on in vitro studies, numerous anti-inflammatory agents, antioxidants and biological agents show tremendous potential to revitalise MSCs. An integrated systems approach and a thorough understanding of complete disease pathology are however required to identify feasible candidates for in vivo targeting of MSCs.

The therapeutic effect of dehydroepiandrosterone (DHEA) on vulvovaginal atrophy

Vulvovaginal atrophy (VVA) is a chronic disease that mostly occurs in postmenopausal women. After menopause, insufficient sex hormones affect the anatomy of the vagina and cause drastic physiological changes. The main histopathological studies of VVA show that postmenopausal estrogen deficiency can lead to the increase of intermediate/parabasal cells, resulting in the loss of lactobacillus, elasticity and lubricity, vaginal epithelial atrophy, pain, dryness. Although the role of estrogen hormones in the treatment of VVA has always been in the past, it is now widely accepted that it also depends on androgens. Estrogen drugs have many side effects. So, Dehydroepiandrosterone（DHEA）is promising for the treatment of VVA, especially when women with contraindications to estrogen have symptoms. This review is expected to understand the latest developments in VVA and the efficacy of DHEA.

Psychoactive properties of BNN27, a novel neurosteroid derivate, in male and female rats

RATIONALE

Νeurosteroids, like dehydroepiandrosterone (DHEA), play an important role in neurodegeneration and neural protection, but they are metabolized in androgens, estrogens, or other active metabolites. A newly developed synthetic DHEA analog, BNN27 ((20R)-3β,21-dihydroxy-17R,20-epoxy-5-pregnene), exerts neurotrophic and neuroprotective actions without estrogenic or androgenic effects.

OBJECTIVES

This study aimed to investigate potential anxiolytic or antidepressant properties of BNN27.

METHODS

Male and female adult Wistar rats were treated with BNN27 (10, 30, or 90 mg/kg, i.p.) and subjected to behavioral tests measuring locomotion, exploration, and "depressive-like" behavior (open field, light/dark box, hole-board, and forced swim tests). The hippocampus and prefrontal cortex were collected for glutamate and GABA measurements, and trunk blood was collected for gonadal hormone analysis.

RESULTS

Acute high-dose BNN27 reduced locomotion and exploratory behavior in both sexes. Intermediate acute doses (30 mg/kg) of BNN27 reduced exploration and testosterone levels only in males, and enhanced progesterone levels in both sexes. Notably, with the present design, BNN27 had neither anxiolytic nor antidepressant effects and did not affect estrogen levels. Interestingly, acute administration of a low BNN27 dose (10 mg/kg) increased glutamate turnover, GABA, and glutamine levels in the hippocampus. The same dose also enhanced glutamate levels in the prefrontal cortex of males only. Sex differences were apparent in the basal levels of behavioral, hormonal, and neurochemical parameters, as expected.

CONCLUSIONS

BNN27 affects locomotion, progesterone, and testosterone levels, as well as the glutamatergic and GABAergic systems of the hippocampus and prefrontal cortex in a sex-dependent way.

D-galactose: a model of accelerated ageing sufficiently sensitive to reflect preventative efficacy of an antioxidant treatment

Considering that the phenomenon of accelerated ageing contributes to early onset of various chronic diseases, modelling of the relevant dysregulated systems or responses is vital for research aimed at identification of potential therapeutic targets. Here, we aimed to establish a model capable of simulating the redox and inflammatory changes of accelerated ageing-specifically, the aim was early phase accelerated ageing, which would allow therapeutic intervention in a preventative approach prior to clinical disease manifestation. A secondary aim was to evaluate the sensitivity of the model to reflect preventative treatment efficacy. Daily D-galactose injections (250 mg/kg body mass/day) for 8 weeks in 9-week-old male Wistar rats induced a model of early accelerated ageing (decreased plasma FRAP; P < 0.05 and altered inflammatory signalling) and an aged profile in lymph node ultrastructure, but did not yet result in telomere shortening. Preventative daily oral antioxidant administration (grape seed-derived polyphenol, 100 mg/kg body mass) prevented tissue ageing, beneficially modulated the inflammatory response, including neutrophil chemokinetic capacity, and tended to increase absolute telomere length. Data suggests that using a mild model of D-galactose administration than those employed to induce neurodegeneration, simulated the point where oxidative stress starts to overwhelm the endogenous antioxidant response and where a pro-inflammatory phenotype switch manifests. Furthermore, despite the expected small effect size, the model was sufficiently sensitive to reflect benefits of preventative antioxidant treatment in the context of ageing. This model presents a practical model for use in drug discovery, particularly in the context of preventative medicine aimed at limiting oxidative stress-associated ageing. Since this starting point of accelerated ageing as illustrated by current data, is not expected to reflect major ageing-associated changes yet, we recommend that future preventative drug discovery studies employ a longitudinal study design in order to clearly demonstrate the delay of this starting point by preventative strategies.

Environmental enrichment modulates inflammation during development in long-evans rats (Rattus norvegicus)

It is unknown whether increased production of pro-inflammatory mediators during the life span is caused by aging per se or via the combination of a cumulative allostatic load due to life challenges. This study aimed to investigate the long-term effects of stress and environmental enrichment on the inflammatory status associated with aging in rats. Animals were assigned to the following five treatment groups: chronic stress with and without environmental enrichment; acute stress with and without environmental enrichment; control animals. Enrichment was provided as an open field containing novel objects (30 min three times per week). Animals assigned to chronic stress groups were exposed to predator sound stressors (e.g., hawk sound) for 30 min daily, while animals assigned to acute stress groups were exposed once a week for 30 min. The interaction between the hypothalamic-pituitary-adrenal axis and the immune system was investigated by measuring metabolized dehydroepiandrosterone (DHEA) levels and peripheral levels of the cytokines IL-6 and IL-10. Results suggested that inflamm-aging was more pronounced in animals with low DHEA levels, which in turn were affected by exposure to environmental enrichment and acute stress. This study showed that environmental enrichment and acute stress can significantly attenuate disruptions in DHEA production, consequently contributing to improved neuroimmune function of aging animals.

Impact of dehydroepianrosterone (DHEA) supplementation on serum levels of insulin-like growth factor 1 (IGF-1): A dose-response meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Inconsistencies exist with regard to the influence of dehydroepiandrosterone (DHEA) supplementation on insulin-like growth factor 1 (IGF-1) levels. The inconsistencies could be attributed to several factors, such as dosage, gender, and duration of intervention, among others. To address these inconsistencies, we conducted a systematic review and meta-analysis to combine findings from randomized controlled trials (RCTs) on this topic.

METHODS

Electronic databases (Scopus, PubMed/Medline, Web of Science, Embase and Google Scholar) were searched for relevant literature published up to February 2020.

RESULTS

Twenty-four qualified trials were included in this meta-analysis. It was found that serum IGF-1 levels were significantly increased in the DHEA group compared to the control (weighted mean differences (WMD): 16.36 ng/ml, 95% CI: 8.99, 23.74; p = .000). Subgroup analysis revealed that a statistically significant increase in serum IGF-1 levels was found only in women (WMD: 23.30 ng/ml, 95% CI: 13.75, 32.87); in participants who supplemented 50 mg/d DHEA (WMD: 15.75 ng/ml, 95% CI: 7.61, 23.89); in participants undergoing DHEA intervention for >12 weeks (WMD: 17.2 ng/ml, 95% CI: 8.02, 26.22); in participants without an underlying comorbidity (WMD: 19.11 ng/ml, 95% CI: 10.69, 27.53); and in participants over the age of 60 years (WMD: 19.79 ng/ml, 95% CI: 9.86, 29.72).

CONCLUSION

DHEA supplementation may increase serum IGF-I levels especially in women and older subjects. However, further studies are warranted before DHEA can be recommended for clinical use.

Dehydroepiandrosterone (DHEA) and its Sulphate (DHEAS) in Alzheimer's Disease

BACKGROUND

Neurosteroids Dehydroepiandrosterone (DHEA) and Dehydroepiandrosterone Sulphate (DHEAS) are involved in many important brain functions, including neuronal plasticity and survival, cognition and behavior, demonstrating preventive and therapeutic potential in different neuropsychiatric and neurodegenerative disorders, including Alzheimer's disease.

OBJECTIVE

The aim of the article was to provide a comprehensive overview of the literature on the involvement of DHEA and DHEAS in Alzheimer's disease.

METHODS

PubMed and MEDLINE databases were searched for relevant literature. The articles were selected considering their titles and abstracts. In the selected full texts, lists of references were searched manually for additional articles.

RESULTS

We performed a systematic review of the studies investigating the role of DHEA and DHEAS in various in vitro and animal models, as well as in patients with Alzheimer's disease, and provided a comprehensive discussion on their potential preventive and therapeutic applications.

CONCLUSION

Despite mixed results, the findings of various preclinical studies are generally supportive of the involvement of DHEA and DHEAS in the pathophysiology of Alzheimer's disease, showing some promise for potential benefits of these neurosteroids in the prevention and treatment. However, so far small clinical trials brought little evidence to support their therapy in AD. Therefore, large-scale human studies are needed to elucidate the specific effects of DHEA and DHEAS and their mechanisms of action, prior to their applications in clinical practice.

Development of new treatments for Alzheimer's disease based on the modulation of translocator protein (TSPO)

The increase in life expectancy of the world population is associated with a higher prevalence of neurodegenerative diseases. Alzheimer's Disease (AD) is the most common neurodegenerative disease, affecting currently 43 million people over the world. To date, most of the pharmacological interventions in AD are intended for the alleviation of some of its symptoms, and there are no effective treatments to inhibit the progression of the disease. Translocator protein (TSPO) is present in contact points between the outer and the inner mitochondrial membranes and is involved in the control of steroidogenesis, inflammation and apoptosis. In the last decade, studies have shown that TSPO ligands present neuroprotective effects in different experimental models of AD, both in vitro and in vivo. The aim of this review is to analyze the data provided by these studies and to discuss if TSPO could be a viable therapeutic target for the development of new treatments for AD.

Sex Differences in Aging and Associated Biomarkers

Aging is a natural process defined by the gradual, time-dependent decline of biological and behavioural functions, for which individuals of the same chronological age show variability. The capacity of biological systems to continuously adjust for optimal functioning despite ever changing environments is essential for healthy aging, and variability in these adaptive homeostatic mechanisms may reflect such heterogeneity in the aging process. With an ever-increasing aging population, interest in biomarkers of aging is growing. Although no universally accepted definition of biomarkers of healthy aging exists, mediators of homeostasis are consistently used as measures of the aging process. As important sex differences are known to underlie many of these systems, it is imperative to consider that this may reflect, to some extent, the sex differences observed in aging and age-related disease states. This chapter aims to outline sex differences in key homeostatic domains thought to be associated with the pathophysiology of aging, often proposed as biomarkers of aging and age-related disease states. This includes considering sex-based differences and hormonal status with regards to the gonadal and adrenal endocrine systems and immune function.