Tumor necrosis factor-α regulates glucocorticoid synthesis in the adrenal glands of Trypanosoma cruzi acutely-infected mice. the role of TNF-R1

Hypocholesterolemic, Antioxidative, and Anti-Inflammatory Effects of Dietary Spirulina platensisis Supplementation on Laying Hens Exposed to Cyclic Heat Stress

This study aimed to investigate the role of dietary Spirulina platensis (SP) supplementation in relieving the negative impacts of heat stress (HS) on the productive performance, cholesterol profile, redox status, and inflammatory cytokines of laying hens. A total of 288, 45-wk-old and 1550.7 ± 2.3 g initial body weight, HY-Line W-36 laying hens were housed in two environmental-controlled compartments. Layers were allotted to eight treatments of a two × four factorial design, with six replicates containing six birds per treatment. The temperature in one of the compartments was kept at a thermoneutral condition (24 °C group), while the temperature in the other compartment was raised to a cyclic heat stress of 35 °C from 9:00 a.m. to 5.00 p.m. (35 °C group). Layers in each compartment were fed on one of four experimental diets, containing 0%, 3%, 6%, or 9% SP (SP groups). The trial continued for five weeks. As a result of this study, exposure of laying hens to cyclic HS resulted in a significant (p < 0.05) increase in the total cholesterol (CH), low-density lipoprotein-CH, liver- and egg yolk-CH, ceruloplasmin, malondialdehyde, interleukins (IL-1β and IL-6), and tumor necrosis factor-α, and a significant (p < 0.05) decrease in the high-density lipoprotein-CH, total antioxidant capacity, and reduced glutathione levels. HS negatively (p < 0.05) affected the hen−day egg production (EP, 90.5% vs. 77.0%), egg weight (EW, 61.8 g vs. 56.8 g), feed intake (FI, 111.6 g vs. 101.5 g) and feed conversion ratio (FCR, 2.00 vs. 2.37). As SP levels increased in layer diets, a linear (p < 0.05) improvement response in most of the parameters was obtained in both HS and non-HS layers, recording the best results with 9% SP (e.g., 78.8% vs. 87.6% EP, 56.7 g vs. 61.9 g EW, 103.3 g vs. 110.2 g FI, and 2.38 vs. 2.04 FCR, in 0% vs. 9% SP, respectively). When incorporating SP into the diets of HS-layers, the negative impacts of HS were remarkably relieved (p < 0.05). Therefore, diets containing 9% SP could be used as a promising approach to improve the productive and physiological performance of laying hens, particularly under heat stress conditions.

Intermittent Lighting Program Relieves the Deleterious Effect of Heat Stress on Growth, Stress Biomarkers, Physiological Status, and Immune Response of Broiler Chickens

Simple Summary

Chronic heat stress remains the most detrimental factor for broiler productivity in hot and desert regions. The manipulation of the lighting program is a useful and inexpensive tool to alleviate the negative effects of heat stress on broiler performance. The present study aimed to investigate the beneficial effects of an intermittent lighting (I.L.) program consisting of repeated periods of 1 h light to 3 h dark during a day on broiler performance under chronic heat-stress conditions. The results indicate that applying the I.L. program to heat-stressed broilers relieved the stress indicators and improved the immune response, physiological status, and growth performance of broilers. Therefore, the application of the I.L. program could be used as a beneficial strategy to recover broiler performance during heat-stress conditions.

Abstract

The effects of heat stress on broiler performance and immunological response were explored using lighting-program manipulation as a potential tool. The study included 200 Cobb500 broiler chicks that were one day old at the time of recruitment. The birds were divided into four-compartment groups with similar environments (five cages per compartment, ten chicks per cage). Starting from the fourth day of age, birds of two compartments received a continuous lighting program (23L:1D a day; C.L. groups) while birds of the other two compartments received an intermittent lighting program (1L:3D 6 times per day; I.L. groups). Within each lighting program during 22–42 d of age, one group was subjected either to a thermoneutral temperature at 24 °C or heat stress at 35 °C. The results reveal that stress biomarkers, especially the plasma concentrations of corticosterone (CORT), tumor necrosis factor-alpha (TNF-α), and malondialdehyde (MDA) were relieved by 46%, 27%, and 51%, respectively, in the I.L. treatment groups compared to the C.L. program in broiler chicks subjected to heat stress. The liver function was also improved by 24% and 32% in AST and ALT levels, respectively, in the I.L. program compared to the C.L. program in stressed birds. Furthermore, the I.L. program positively influenced the immune response of the heat-stressed broilers. Eventually, the I.L. program increased the heat-stressed broilers’ body weight gain and feed conversion ratio. It can be concluded that applying the I.L. program to broiler chickens can effectively improve their physiological balance and growth performance under heat-stress conditions.

Effect of Organic Selenium-Enriched Yeast on Relieving the Deterioration of Layer Performance, Immune Function, and Physiological Indicators Induced by Heat Stress

Heat stress (HS) induces deleterious effects on the performance of laying hens and causes economic losses for poultry industry. This study was carried out to investigate the organic effect of selenium-enriched yeast (SY) on relieving the performance, immunity and physiological deterioration induced by heat stress in laying hens. A total of 324, 28-week-old, Hy-Line Brown commercial chicken layers were randomly distributed into 4 treatments according to a 2 × 2 factorial design, with 9 hens × 9 replicates per treatment (n = 81). From 30 to 34 weeks of age, layers were exposed to 2 temperature treatments (the HS treatment groups): a thermoneutral temperature at 24°C and a heat stress at 35°C. Layers were further assigned into the 2 subgroups according to dietary supplementation with organic selenium-enriched yeast (the SY treatment groups) at either 0 or 0.4 mg/kg diet. Results indicated that all the aspects of the layer performance during the experimental period were impaired by exposure to HS, while SY supplementation improved the layer performance in both the HS and non-HS layers. Intestinal villi disruptions and liver necrotic hepatocytes were observed in the layers exposed to HS, while villi integrity and hepatocytic normality were enhanced by SY treatment. A significant (P < 0.05) decrease in the total leukocyte count, sheep red blood cell (SRBC) antibody titer, and T- and B-lymphocyte proliferation along with an increase in the heterophils/lymphocytes (H/L) ratio were observed in the HS layers compared to non-HS layers. On the contrary, SY treatment significantly (P < 0.05) improved the immune function traits in both the HS layers and non-HS layers. Furthermore, the SY treatment plays an important role in mitigating the oxidative stress and inflammation induced by HS, displaying lower levels of plasma corticosterone, lipid peroxidation, interleukin-1β, and tumor necrosis factor-α in HS layers supplemented with SY compared to HS layers without SY supplementation. These results conclude that addition of SY to the diet of laying hens could be applied as a potential nutritional approach to relieve the deterioration effects of heat stress on the immunity, physiological status, and productive performance of laying hens.

A Cocoa Diet Can Partially Attenuate the Alterations in Microbiota and Mucosal Immunity Induced by a Single Session of Intensive Exercise in Rats

Background

Following intensive sports events, a higher rate of upper respiratory tract infections and the appearance of gastrointestinal symptomatology have been reported. We aimed to evaluate the effect of a cocoa-enriched diet on the cecal microbiota and mucosal immune system of rats submitted to high-intensity acute exercise, as well as to elucidate the involvement of cocoa fiber in such effects.

Methods

Wistar rats were fed either a standard diet, a diet containing 10% cocoa providing 5% fiber and a diet containing only 5% cocoa fiber. After 25 days, half of the rats of each diet performed an exhaustion running test. Sixteen hours later, samples were obtained to assess, among others, the cecal microbiota and short chain fatty acids (SCFAs) composition, mesenteric lymph nodes (MLNs) and Peyer’s patches (PPs) lymphocyte composition, and immunoglobulin (Ig) content in salivary glands.

Results

The intake of cocoa, partially due to its fiber content, improved the SCFA production, prevented some changes in PPs and in MLNs lymphocyte composition and also decreased the production of proinflammatory cytokines. Cocoa diet, contrary to cocoa fiber, did not prevent the lower salivary IgM induced by exercise.

Conclusion

A cocoa dietary intake can partially attenuate the alterations in microbiota and mucosal immunity induced by a single session of intensive exercise.

Adrenal Gland Irradiation Causes Fatigue Accompanied by Reactive Changes in Cortisol Levels

BACKGROUND

Incidental radiotherapy (RT) to the adrenal gland may have systemic effects. This study aimed to investigate the effects of adrenal RT on fatigue.

METHODS

BALB/c mice were surgically explored to identify the left adrenal gland and delivered intra-operative RT. The swimming endurance test was used for endurance assessment to represent fatigue. Plasma levels of stress hormones and histopathological features were examined. Three patients with inevitable RT to the adrenal gland were enrolled for the preliminary study. Serum levels of cortisol, aldosterone, and adrenocorticotropic hormone (ACTH) were measured before and after RT. Fatigue score by using the fatigue severity scale and RT dosimetric parameters were collected.

RESULTS

In the experimental mouse model, adrenal RT decreased baseline cortisol from 274.6 ± 37.8 to 193.6 ± 29.4 ng/mL (p = 0.007) and swimming endurance time from 3.7 ± 0.3 to 1.7 ± 0.6 min (p = 0.02). In histopathological assessment, the irradiated adrenal glands showed RT injury features in the adrenal cortex. In the enrolled patients, baseline cortisol significantly declined after RT. There were no significant differences in the levels of morning cortisol, aldosterone, and ACTH before and after RT.

CONCLUSIONS

The RT dose distributed to the adrenal gland may correlate with unwanted adverse effects, including fatigue and adrenal hormone alterations.

Is a negative correlation between sTNFR1 and TNF in patients with chronic Chagas disease the key to clinical progression?

Soluble TNF receptors (sTNFR1 and sTNFR2) are natural endogenous inhibitors of TNF and are elevated in inflammatory, autoimmune, and chronic degenerative diseases. In Chagas disease, pleiotropic cytokine TNF is considered key in immunopathology. Thus, we aimed to evaluate the levels of TNF, sTNFR1, and sTNFR2 in the serum of patients with chronic Chagas disease. TNF and its soluble receptors were quantified using Cytometric Bead Array in the serum of 132 patients, of which 51 had the indeterminate form (IND), 39 the mild cardiac form (CARD 1), 42 the severe cardiac form (CARD 2), and 20 non-infected individuals (NI). The results indicate that the soluble receptors may regulate TNF in Chagas disease, as their leves were higher in T. cruzi-infected individuals when compared to non-infected individuals. We found a moderate negative correlation between sTNFR1 and TNF in individuals with the IND form, suggesting a relationship with non-progression to more severe forms, such as heart disease. sTNFR1 and sTNFR2 were increased in all clinical forms, but with a moderate positive correlation in more severe patients (r = 0.50 and p = 0.0005). TNF levels showed no statistical differences in the groups of patients. These findings suggest the importance of the endogenous balance of the levels of soluble TNF receptors in the protection and balance in patients with chronic Chagas disease, besides revealing the immunological complexity in chronic T. cruzi-infected individuals.

Pro-arrhythmogenic effects of Trypanosoma cruzi conditioned medium proteins in a model of bovine chromaffin cells

Asymptomatic sudden death is the principal cause of mortality in Chagas disease. There is little information about molecular mechanisms involved in the pathophysiology of malignant arrhythmias in Chagasic patients. Previous studies have involved Trypanosoma cruzi secretion proteins in the genesis of arrhythmias ex vivo, but the molecular mechanisms involved are still unresolved. Thus, the aim was to determine the effect of these secreted proteins on the cellular excitability throughout to test its effects on catecholamine secretion, sodium-, calcium-, and potassium-conductance and action potential (AP) firing. Conditioned medium was obtained from the co-culture of T. cruzi and Vero cells (African green monkey kidney cells) and ultra-filtered for concentrating immunogenic high molecular weight parasite proteins. Chromaffin cells were assessed with the parasite and Vero cells control medium. Parasite-secreted proteins induce catecholamine secretion in a dose-dependent manner. Additionally, T. cruzi conditioned medium induced depression of both calcium conductance and calcium and voltage-dependent potassium current. Interestingly, this fact was related to the abolishment of the hyperpolarization phase of the AP produced by the parasite medium. Taken together, these results suggest that T. cruzi proteins may be involved in the genesis of pro-arrhythmic conditions that could influence the appearance of malignant arrhythmias in Chagasic patients.

Melatonin down-regulates steroidal hormones, thymocyte apoptosis and inflammatory cytokines in middle-aged T. cruzi infected rats

Chagas disease, triggered by the flagellate protozoan Trypanosoma cruzi (T. cruzi) plays a potentially threat to historically non-endemic areas. Considerable evidence established that the immuno-endocrine balance could deeply influence the experimental T. cruzi progression inside the host's body. A high-resolution multiple reaction monitoring approach (MRM^HR) was used to study the influence of melatonin on adrenal and plasma steroidal hormones profile of T. cruzi infected Wistar rats. Young (5 weeks) and middle-aged (18 months) male Wistar rats received melatonin (5 mg/Kg, orally) during the acute Chagas disease. Corticosterone, 11-dehydrocorticosterone (11-DHC), cortisol, cortisone, aldosterone, progesterone and melatonin concentration were evaluated. Interleukin-1 alpha and β (IL-1α and β), IL-6 and transforming growth factor beta (TGF-β) were also analyzed. Our results revealed an increased production of corticosterone, cortisone, cortisol and aldosterone in middle-aged control animals, thus confirming the aging effects on the steroidal hormone profile. Serum melatonin levels were reduced with age and predominantly higher in young and middle-aged infected rats. Melatonin treatment reduced the corticosterone, 11-DHC, cortisol, cortisone, aldosterone and progesterone in response to T. cruzi infection. Decreased IL-1 α and β concentrations were also found in melatonin treated middle-aged infected animals. Melatonin treated middle-aged control rats displayed reduced concentrations of TGF-β. Melatonin levels were significantly higher in all middle-aged rats treated animals. Reduced percentages of early and late thymocyte apoptosis was found for young and middle-aged melatonin supplemented rats. Finally, our results show a link between the therapeutic and biological effects of melatonin controlling steroidal hormones pathways as well as inflammatory mediators.

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Melatonin acts on the regulation of steroid hormones, apoptosis and cytokine signaling during acute T. cruzi infection;

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Middle-aged control rats have higher production of corticosterone, cortisone, cortisol and aldosterone;

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Melatonin treated middle-aged infected rats displayed reduced concentrations of IL-1 α and β;

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Melatonin levels were significantly higher in all middle-aged rats treated animals;

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Reduced percentages of early and late thymocyte apoptosis was found for young and middle-aged melatonin supplemented rats.

Recombinant Mycobacterium bovis BCG is a promising platform to develop vaccines against Trypansoma cruzi infection

Chagas disease, caused by the hemoflagelate parasite Trypanosoma cruzi, is one of the most prevalent endemic parasitoses, affecting 7-8 million people. Due to the complexity of the infection, no vaccines are available at present. The extraordinary adjuvant capacity of bacille Calmette-Guérin (BCG) was explored in this work to develop a vaccine candidate to protect against T. cruzi infection using the recombinant BCG (rBCG) vaccine platform. Three antigens of the parasite corresponding to the N and C terminal fragments of the enzyme trans-sialidase (NT-TS and CT-TS, respectively) and a fragment of the cruzipain enzyme (CZf) were cloned into the vectors pUS997 and pUS2000 and transformed into the BCG Pasteur strain. In vaccinated mice, rBCG expressing NT-TS in pUS2000 plasmid provided the highest protection and the lowest parasitemia after challenging BALB/c mice with a 50% lethal dose of parasites. When mice vaccinated with pUS2000-NT-TS were challenged with a 100% lethal dose of parasite, high levels of protection were also obtained, together with a low degree of cardiac lesions 120 days after infection. In immunized mice with pUS2000-NT-TS/rBCG clone, the proliferation of CD4⁺ cells from splenocytes stimulated with the TS antigen was significant; this stimulation increased interferon (IFN)-γ and interleukin (IL)-17 within CD4⁺ T lymphocytes (LTCD4⁺ ) cells and IFN-γ and CD107 expression within LTCD8⁺ cells. Therefore, pUS2000-NT-TS/rBCG conferred high levels of protection, which correlated with an immune response orientated towards a T helper type 1 (Th1)/Th17 profile, together with an LTC-specific response, indicating that rBCG is a promising platform to develop vaccines against T. cruzi.

Immune-neuroendocrine and metabolic disorders in human and experimental T. cruzi infection: New clues for understanding Chagas disease pathology

Studies in mice undergoing acute Trypanosoma cruzi infection and patients with Chagas disease, led to identify several immune-neuroendocrine disturbances and metabolic disorders. Here, we review relevant findings concerning such abnormalities and discuss their possible influence on disease physiopathology.

Capsaicin inhibits lipopolysaccharide-induced adrenal steroidogenesis by raising intracellular calcium levels

INTRODUCTION

Glucocorticoid release by adrenals has been described as significant to survive sepsis. The activation of transient receptor potential vanilloid type 1 (TRPV1) inhibited ACTH-induced glucocorticoid release by adrenal glands in vitro.

OBJECTIVE

The aim of this study was to investigate if capsaicin, an activator of TRPV1, would prevent LPS-induced glucocorticoid production by adrenals.

METHODS

Male Swiss-Webster mice were treated with capsaicin intraperitoneally (0.2 or 2 mg/kg) 30 min before LPS injection. All analyses were performed 2 h after the LPS stimulation, including plasma corticosterone and peritoneal IL-1β and TNF-α levels. Furthermore, murine adrenocortical Y1 cells were used to assess the effects of capsaicin on LPS-induced corticosterone production in vitro.

RESULTS

Capsaicin (2 mg/kg, i.p.) significantly reduced plasma corticosterone levels and adrenal hypertrophy induced by LPS without alter the levels of pro-steroidogenic cytokines IL-1β and TNF-α in peritoneal cavity of mice, while the dose of 0.2 mg/kg of capsaicin did not interfere with adrenal steroidogenesis, attested by RIA and ELISA, respectively. Y1 cells express TRPV1, measured by immunofluorescence and western blot, and capsaicin decreased LPS-induced corticosterone production by these cells in vitro. Capsaicin also induces calcium mobilization in Y1 cells in vitro.

CONCLUSIONS

These findings suggest that capsaicin inhibits corticosterone production induced by LPS by acting directly on adrenal cells producing glucocorticoids, in a mechanism probably associated with induction of a cytoplasmic calcium increase in these cells.

Melatonin prevents early pituitary dysfunction induced by sucrose-rich diets

While physiological levels of glucocorticoids are required to ensure proper functions of the body, consistently high levels may engender several deleterious consequences. We have previously shown an increase in the activity of the hypothalamic-pituitary-adrenal (HPA) axis in rats fed sucrose-rich diets (SRD). The main goal of this study was to analyze the processes involved in the modulation of the pituitary production of ACTH by SRD, and to test melatonin as a possible therapeutic agent for the prevention of the HPA axis dysfunction. Male Wistar rats were fed standard chow and either SRD (30% sucrose in the drinking water) or plain water for three weeks. Melatonin was administered as subcutaneous pellets. Results showed that SRD treatment induced an increase in systemic ACTH and corticosterone levels and a decrease in melatonin levels. In the pituitary gland, we also detected an increase in the expression levels of proopiomelanocortin (POMC) that was accompanied by increased levels of: lipoperoxides, nitro-tyrosine modified proteins, catalase, heme oxygenase-1, interleukin-1β mRNA, and by an increase in the tissue number of inflammatory cells (F4/80 and Iba-1 positive cells). Melatonin treatment prevented all these systemic and pituitary changes as well as the increase in POMC expression induced by incubation of AtT-20 corticotrophs with conditioned media obtained from stimulated macrophages. In conclusion, stimulation of POMC/ACTH production in rats fed a SRD could involve the generation of oxidative stress and inflammation in the pituitary gland. Melatonin treatment prevented these effects and normalized the activity of the HPA axis.

Evidence in Favor of an Alternative Glucocorticoid Synthesis Pathway During Acute Experimental Chagas Disease

It is well-established that infectious stress activates the hypothalamus-pituitary-adrenal axis leading to the production of pituitary adrenocorticotropin (ACTH) and adrenal glucocorticoids (GCs). Usually, GC synthesis is mediated by protein kinase A (PKA) signaling pathway triggered by ACTH. We previously demonstrated that acute murine Chagas disease courses with a marked increase of GC, with some data suggesting that GC synthesis may be ACTH-dissociated in the late phase of this parasitic infection. Alternative pathways of GC synthesis have been reported in sepsis or mental diseases, in which interleukin (IL)-1β, prostaglandin E2 (PGE2), and/or cAMP-activated guanine nucleotide exchange factor 2 (EPAC2) are likely to play a role in this regard. Accordingly, we have searched for the existence of an ACTH-independent pathway in an experimental model of a major parasitic disease like Chagas disease, in addition to characterizing potential alternative pathways of GC synthesis. To this end, C57BL/6 male mice were infected with T. cruzi (Tc), and evaluated throughout the acute phase for several parameters, including the kinetic of GC and ACTH release, the adrenal level of MC2R (ACTH receptor) expression, the p-PKA/PKA ratio as ACTH-dependent mechanism of signal transduction, as well as adrenal expression of IL-1β and its receptor, EPAC2 and PGE2 synthase. Our results reveal the existence of two phases involved in GC synthesis during Tc infection in mice, an initial one dealing with the well-known ACTH-dependent pathway, followed by a further ACTH-hyporesponsive phase. Furthermore, inflamed adrenal microenvironment may tune the production of intracellular mediators that also operate upon GC synthesis, like PGE2 synthase and EPAC2, as emerging driving forces for GC production in the advanced course of Tc infection. In essence, GC production seems to be associated with a biphasic action of PGE2, suggesting that the effect of PGE2/cAMP in the ACTH-independent second phase may be mediated by EPAC2.

Glucocorticoids and sympathetic neurotransmitters modulate the acute immune response to Trypanosoma cruzi

Evidence suggests that natural and adaptive immune responses can trigger neuroendocrine responses. Here, we discuss changes in the activity of the hypothalamus-pituitary-adrenal axis and in autonomic nerves, predominantly of the sympathetic nervous system, in a mouse model of acute infection with Trypanosoma cruzi. The endocrine response includes a marked increased release of glucocorticoid and a decrease of immune-stimulatory hormones, such as dehydroepiandrosterone sulfate, prolactin, and growth hormone during infection. These endocrine changes result in reduced proinflammatory cytokine production, increased regulatory/effector T cell ratio, and thymus atrophy. The sympathetic activity in the spleen of infected mice is also markedly reduced. However, the residual sympathetic activity can modulate the immune response to the parasite, as shown by increased mortality and production of proinflammatory cytokines in sympathetically denervated, infected mice. The outcome of the neuroendocrine response is the moderation of the intensity of the immune response to the parasite, an effect that results in delayed mortality in susceptible mice, and favors the course toward chronicity in more resistant animals.

Tumor necrosis factor-α, interleukin-8 and eosinophil cationic protein as serum markers of glucocorticoid efficacy in the treatment of bronchial asthma

BACKGROUND

Bronchial asthma (BA) is a common chronic respiratory disease that has exhibited a rising global incidence in recent years. Glucocorticoids are used for the treatment of BA. Emerging evidence has demonstrated the roles of tumor necrosis factor (TNF-α), interleukin-8 (IL-8) and eosinophil cationic protein (ECP) in BA. The present study investigated whether TNF-α, IL-8 and ECP were associated with the clinical stages and severity of BA and the efficacy of glucocorticoids in the treatment of BA.

METHODS

A total of 199 patients with BA and 174 healthy individuals were included in this study. Patients with BA underwent glucocorticoid treatment, and the TNF-α, IL-8 and ECP levels and lung functions of the subjects were measured. The correlations of the TNF-α, IL-8 and ECP levels with BA severity, clinical staging and lung functions were assessed. We investigated whether the TNF-α, IL-8 and ECP levels aided in evaluating the efficacy of using glucocorticoids for the treatment of BA.

RESULTS

TNF-α, IL-8 and ECP exhibited high levels in patients with BA, and glucocorticoid treatment notably decreased these levels. The TNF-α, IL-8 and ECP levels were positively correlated with the clinical stages and severity of BA and negatively correlated with lung function. TNF-α, IL-8 and ECP can be used as serum markers to predict the efficacy of glucocorticoids in the treatment of BA.

CONCLUSION

The key findings of this study collectively support a role for TNF-α, IL-8 and ECP in BA development, and TNF-α, IL-8 and ECP can be used as serum markers of glucocorticoid efficacy in BA.

Role of Hormonal Circuitry Upon T Cell Development in Chagas Disease: Possible Implications on T Cell Dysfunctions

T cell response plays an essential role in the host resistance to infection by the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas disease. This infection is often associated with multiple manifestations of T cell dysfunction, both during the acute and the chronic phases of disease. Additionally, the normal development of T cells is affected. As seen in animal models of Chagas disease, there is a strong thymic atrophy due to massive death of CD4⁺CD8⁺ double-positive cells by apoptosis and an abnormal escape of immature and potentially autoreactive thymocytes from the organ. Furthermore, an increase in the release of corticosterone triggered by T. cruzi-driven systemic inflammation is strongly associated with the alterations seen in the thymus of infected animals. Moreover, changes in the levels of other hormones, including growth hormone, prolactin, and testosterone are also able to contribute to the disruption of thymic homeostasis secondary to T. cruzi infection. In this review, we discuss the role of hormonal circuits involved in the normal T cell development and trafficking, as well as their role on the thymic alterations likely related to the peripheral T cell disturbances largely reported in both chagasic patients and animal models of Chagas disease.

Death of adrenocortical cells during murine acute T. cruzi infection is not associated with TNF-R1 signaling but mostly with the type II pathway of Fas-mediated apoptosis

Earlier studies from our laboratory demonstrated that acute experimental Trypanosoma cruzi infection promotes an intense inflammation along with a sepsis-like dysregulated adrenal response characterized by normal levels of ACTH with raised glucocorticoid secretion. Inflammation was also known to result in adrenal cell apoptosis, which in turn may influence HPA axis uncoupling. To explore factors and pathways which may be involved in the apoptosis of adrenal cells, together with its impact on the functionality of the gland, we carried out a series of studies in mice lacking death receptors, such as TNF-R1 (C57BL/6-^{Tnfrsf1a tm1Imx} or TNF-R1^-/-) or Fas ligand (C57BL/6 Fas-deficient lpr mice), undergoing acute T. cruzi infection. Here we demonstrate that the late hypercorticosterolism seen in C57BL/6 mice during acute T. cruzi infection coexists with and hyperplasia and hypertrophy of zona fasciculata, paralleled by increased number of apoptotic cells. Apoptosis seems to be mediated mainly by the type II pathway of Fas-mediated apoptosis, which engages the mitochondrial pathway of apoptosis triggering the cytochrome c release to increase caspase-3 activation. Fas-induced apoptosis of adrenocortical cells is also related with an exacerbated production of intra-adrenal cytokines that probably maintain the late supply of adrenal hormones during host response. Present results shed light on the molecular mechanisms dealing with these phenomena which are crucial not only for the development of interventions attempting to avoid adrenal dysfunction, but also for its wide occurrence in other infectious-based critical illnesses.

Does the degree of endocrine dyscrasia post-reproduction dictate post-reproductive lifespan? Lessons from semelparous and iteroparous species

Post-reproductive lifespan varies greatly among species; human post-reproductive lifespan comprises ~30-50% of their total longevity, while semelparous salmon and dasyurid marsupials post-reproductive lifespan comprises <4% of their total longevity. To examine if the magnitude of hypothalamic-pituitary-gonadal (HPG) axis dyscrasia at the time of reproductive senescence determines post-reproductive lifespan, we examined the difference between pre- and post-reproductive (1) circulating sex hormones and (2) the ratio of sex steroids to gonadotropins (e.g., 17β-estradiol/follicle-stimulating hormone (FSH)), an index of the dysregulation of the HPG axis and the level of dyotic (death) signaling post-reproduction. Animals with a shorter post-reproductive lifespan (<4% total longevity) had a more marked decline in circulating sex steroids and corresponding elevation in gonadotropins compared to animals with a longer post-reproductive lifespan (30-60% total longevity). In semelparous female salmon of short post-reproductive lifespan (1%), these divergent changes in circulating hormone concentration post-reproduction equated to a 711-fold decrease in the ratio of 17β-estradiol/FSH between the reproductive and post-reproductive periods. In contrast, the decrease in the ratio of 17β-estradiol/FSH in iteroparous female mammals with long post-reproductive lifespan was significantly less (1.7-34-fold) post-reproduction. Likewise, in male semelparous salmon, the decrease in the ratio of testosterone/FSH (82-fold) was considerably larger than for iteroparous species (1.3-11-fold). These results suggest that (1) organisms with greater reproductive endocrine dyscrasia more rapidly undergo senescence and die, and (2) the contribution post-reproduction by non-gonadal (and perhaps gonadal) tissues to circulating sex hormones dictates post-reproductive tissue health and longevity. In this way, reproduction and longevity are coupled, with the degree of non-gonadal tissue hormone production dictating the rate of somatic tissue demise post-reproduction and the differences in post-reproductive lifespans between species.

Immunity and stroke, the hurdles of stroke research translation

Immunomodulatory therapies after stroke have the potential to provide clinical benefit to a subset of patients, but risk subverting the protective, healing aspects of the innate immune response. Neutrophils clear necrotic cerebral tissue and are important in immunomodulation, but can also contribute to tissue injury. Human trials for immunomodulatory stroke treatments in the sub-acute time frame have attempted to prevent peripheral neutrophil infiltration, but none have been successful and one trial demonstrated harm. These unselected trials had broad inclusion criteria and appear to not have had a specific treatment target. Unfortunately, due to the heterogeneous nature of brain ischemia in humans resulting in variation in clinical severity, the negative effect of thrombolytic drugs on the blood-brain barrier, and the heterogeneity of immune response, it may only be a subset of stroke patients who can realistically benefit from immunomodulation therapies. Translational research strategies require both an understanding of lab practices which create highly controlled environments in contrast to clinical practice where the diagnosis of stroke does not require the identification of a vessel occlusion. These differences between lab and clinical practices can be resolved through the integration of appropriate patient selection criteria and use of advanced imaging and ridged patient selection practices in clinical trials which will be an important part to the success of any future trials of translational research such as immunomodulation.

Activation of PPAR-γ reduces HPA axis activity in diabetic rats by up-regulating PI3K expression

Increased hypothalamus-pituitary-adrenal axis (HPA) activity in diabetes is strongly associated with several morbidities noted in patients with the disease. We previously demonstrated that hyperactivity of HPA axis under diabetic conditions is associated with up-regulation of adrenocorticotrophic hormone (ACTH) receptors (MC2R) in adrenal and down-regulation of glucocorticoid receptors (GR and MR) in pituitary. This study investigates the role of peroxisome proliferator-activated receptor (PPAR)-γ in HPA axis hyperactivity in diabetic rats. Diabetes was induced by intravenous injection of alloxan into fasted rats. The PPAR-γ agonist rosiglitazone and/or PI3K inhibitor wortmannin were administered daily for 18 consecutive days, starting 3days after diabetes induction. Plasma ACTH and corticosterone were evaluated by radioimmunoassay, while intensities of MC2R, proopiomelanocortin (POMC), GR, MR, PI3K p110α and PPAR-γ were assessed using immunohistochemistry. Rosiglitazone treatment inhibited adrenal hypertrophy and hypercorticoidism observed in diabetic rats. Rosiglitazone also significantly reversed the diabetes-induced increase in the MC2R expression in adrenal cortex. We noted that rosiglitazone reduced the number of corticotroph cells and inhibited both anterior pituitary POMC expression and plasma ACTH levels. Furthermore, rosiglitazone treatment was unable to restore the reduced expression of GR and MR in the anterior pituitary of diabetic rats. Rosiglitazone increased the number of PPAR-γ⁺ cells and expression of PI3K p110α in both anterior pituitary and adrenal cortex of diabetic rats. In addition, wortmannin blocked the ability of rosiglitazone to restore corticotroph cell numbers, adrenal hypertrophy and plasma corticosterone levels in diabetic rats. In conclusion, our findings revealed that rosiglitazone down-regulates HPA axis hyperactivity in diabetic rats via a mechanism dependent on PI3K activation in pituitary and adrenal glands.

Imidacloprid induced histomorphological changes and expression of TLR-4 and TNFα in lung

The imidacloprid is used worldwide as a pesticide and has been linked with endocrine disturbances and reduced pulmonary function. However, effects of imidacloprid alone or in combination with microbial molecules on lungs are not fully understood. Because the pulmonary effects of interactions of endotoxins with imidacloprid are unknown, we designed a study to investigate that in a mouse model. Mice (N=14) were given imidacloprid orally @ 1/20(th) of LD50 dissolved in corn oil for 30days. After the treatments, six animals from each group were challenged with E. coli lipopolysaccharide (LPS) @ 80μg/animal via intranasal route and remaining animals were challenged with normal saline solution @ 80μl/animal via same route. Imidacloprid in combination with LPS led to significant increase in total cell and neutrophil counts in BAL and peripheral blood. Semi-quantitative histopathology revealed lung injury in imidacloprid treatment group and injury was more marked in animal receiving both imidacloprid and LPS. There was no change (p<0.05) in the expression of TLR-4 and TNF-α both at mRNA and protein levels following exposure to imidacloprid alone or in combination with LPS. The data show that imidacloprid alone or in combination with LPS resulted changes in lung morphology without altering the expression of TLR-4 and TNF-α. Furthermore, pre-treatment with imidacloprid didn't affect response to LPS.

Evasion and Immuno-Endocrine Regulation in Parasite Infection: Two Sides of the Same Coin in Chagas Disease?

Chagas disease is a serious illness caused by the protozoan parasite Trypanosoma cruzi. Nearly 30% of chronically infected people develop cardiac, digestive, or mixed alterations, suggesting a broad range of host-parasite interactions that finally impact upon chronic disease outcome. The ability of T. cruzi to persist and cause pathology seems to depend on diverse factors like T. cruzi strains, the infective load and the route of infection, presence of virulence factors, the parasite capacity to avoid protective immune response, the strength and type of host defense mechanisms and the genetic background of the host. The host-parasite interaction is subject to a constant neuro-endocrine regulation that is thought to influence the adaptive immune system, and as the infection proceeds it can lead to a broad range of outcomes, ranging from pathogen elimination to its continued persistence in the host. In this context, T. cruzi evasion strategies and host defense mechanisms can be envisioned as two sides of the same coin, influencing parasite persistence and different outcomes observed in Chagas disease. Understanding how T. cruzi evade host's innate and adaptive immune response will provide important clues to better dissect mechanisms underlying the pathophysiology of Chagas disease.