Adrenal hormone modulation of type 1 and type 2 cytokine production by spleen cells: dexamethasone and dehydroepiandrosterone suppress interleukin-2, interleukin-4, and interferon-gamma production in vitro

Comparative study on the impacts of visnagin and its methoxy derivative khellin on human lymphocyte proliferation and Th1/Th2 balance

BACKGROUND

Visnagin is a phenolic and natural compound in turmeric and fenugreek, and its anti-inflammatory effect has been indicated. Therefore, this study aimed to investigate and compare the anti-inflammatory properties of visnagin and its methoxy derivative khellin on human lymphocytes.

METHODS

Human lymphocytes were treated with khellin, visnagin (10, 30, and 100 µM), and dexamethasone (0.1 mM) in the presence of phytohemagglutinin (PHA). The levels of cell proliferation, nitric oxide (NO), glutathione (GSH), malondialdehyde (MDA), and MDA/GSH ratio were measured using biochemistry methods. Furthermore, the mRNA levels of interferon-γ (IFN-γ), interleukin (IL)-4, and IL-10 were assessed using real-time PCR, while IFN-γ/IL-4(Th₁/Th₂), IFN-γ/IL-10(Th₁/T_reg), and IL-4/IL-10(Th₂/T_reg) ratios were made by dividing their exact values.

RESULTS

In the PHA-stimulated group, GSH and IFN-γ/IL-4 levels were markedly diminished, but other variables were significantly elevated compared to the control group. Khellin and visnagin significantly declined the levels of cell proliferation, MDA, MDA/GSH ratio, and NO production. Khellin and visnagin concentration-dependently diminished IFN-γ and IL-4 levels and increased IL-10 levels compared to the PHA-stimulated group. Two higher concentrations of khellin and visnagin (30 and 100 μM) considerably diminished the IFN-γ, IFN-γ/IL-10, and IL-4/IL-10 values compared to the PHA-stimulated group. However, 100 µM of khellin and visnagin significantly increased GSH level compared to the PHA-stimulated group.

CONCLUSIONS

In PHA-stimulated lymphocytes, representing Th₂ dominant allergic diseases, khellin and visnagin provides more specific anti-oxidant, anti-inflammatory, and immunomodulatory functions than dexamethasone. In addition, the effects of khellin were more prominent than visnagin.

Inflammatory Basis of Atherosclerosis: Modulation by Sex Hormones

Atherosclerosis-related cardiovascular diseases (CVDs) are the leading cause of death globally. Several lines of evidence are supportive of the contributory role of vascular inflammation in atherosclerosis. Diverse immune cell types, including monocytes/macrophages, T-cells and neutrophils, as well as specialized proresolving lipid mediators, have been successfully characterized as key players in vascular inflammation. The increased prevalence of atherosclerotic CVD in men in comparison to age-matched premenopausal women and the abolition of sex differences in prevalence during menopause strongly suggest a pivotal role of sex hormones in the development of CVD. Indeed, many animal and human studies conclusively implicate sex hormones as a crucial component in driving the immune response. This is further corroborated by the effective identification of sex hormone receptors in vascular endothelial cells, vascular smooth muscle cells and immune cells. Collectively, these findings suggest a cellular communication between sex hormones and vascular or immune cells underlying the vascular inflammation in atherosclerosis. The aim of this review is to provide an overview of vascular inflammation as a causal cue underlying atherosclerotic CVDs within the context of the modulatory effects of sex hormones. Moreover, the cellular and molecular signaling pathways underlying the sex hormones- immune system interactions as potential culprits for vascular inflammation are highlighted with detailed and critical discussion. Finally, the review concludes by speculations on the potential sex-related efficacy of currently available immunotherapies in mitigating vascular inflammation. Conceivably, a deeper understanding of the immunoregulatory influence of sex hormones on vascular inflammation-mediated atherosclerosis permits sex-based management of atherosclerosis-related CVDs.

Resiniferatoxin promotes adult worm expulsion in Trichinella spiralis-infected rats by Th2 immune response modulation

BACKGROUND

The immune response during T spiralis infection is characterized by an increase in eosinophils and mast cells, as well as Th2 cytokine production, such as interleukin (IL)-4, IL-10 and IL-13, promoting T spiralis expulsion from the host. However, this response damages the host, favouring the parasite survival. In the search for new pharmacological strategies that protect against T spiralis infection, a recent study showed that treatment with resiniferatoxin (RTX) modulates the Th1 cytokines production, reducing muscle parasite burden.

OBJECTIVE

To evaluate the effect of RTX treatment on the Th2 cytokines production, the number of eosinophils, mast cells and the intestinal expulsion of T spiralis.

METHODS

Serum levels of IL-4, IL-10 and IL-13 were quantified by ELISA; the number of eosinophils, mast cells and the adult worms of T spiralis in the small intestine was quantified.

RESULTS

RTX treatment increased serum levels of IL-4, IL-10 and IL-13, and it decreases intestinal eosinophilia, however, favours the mastocytosis, promoting T spiralis intestinal expulsion.

CONCLUSIONS

These findings suggest that RTX is capable to modulate the Th2 immune response, promoting T spiralis expulsion, which contributes to the defence against T spiralis infection, placing the RTX as a potential immunomodulatory drug.

Quantification of Cytokines in Lip Tissue from Infants Affected by Congenital Cleft Lip and Palate

Cleft lip and palate are amongst the most common congenital malformations worldwide presenting with variable manifestations. Previous research has been primarily focused on the genetical aspects of its complex and multifactorial etiology. In the present study, we investigated the role of cytokines as mediators of epithelial–mesenchymal crosstalk and local site inflammation in cleft affected infants. Lip material was obtained from 12 children aged before primary dentition who suffered from orofacial clefting. The quantification of 12 cytokines (Interleukin-2,4,5,6,10,12,13,17A, Tumor Necrosis Factor-α, Interferon-γ, Transforming Growth Factor beta-1 and Granulocyte-Colony Stimulating Factor) was done using ELISA. Nonparametric Spearman Rho was used to ascertain the correlation between the expression levels of different cytokines. A significantly strong positive correlation was found between IL-2 and IFN-γ coupled with an IL4/IFN-γ ratio favoring IFN-γ. These findings indicate a shift towards the preferential activation of the Th1 differentiation pathway. Further, a pathological reduction in TGFβ-1 levels was noted, which may contribute to mucosal damage. IL-6 was more highly correlated to IFN-γ and IL-12 indicating its potential proinflammatory role in cleft affected tissues. This preferential activation of Th1 cell differentiation and consistent expression of IL-2,6,13 and TNF-α in cleft patients may indicate certain underlying mechanisms for inflammation mediation at the site of clefting.

Sex differences in pain and opioid mediated antinociception: Modulatory role of gonadal hormones

Sex-related differences in pain and opioids has been the focus of many researches. It is demonstrated that women experience greater clinical pain, lower pain threshold and tolerance, more sensitivity and distress to experimentally induced pain compared to men. Sex differences in response to opioid treatment revealed inconsistent results. However, the etiology of these disparities is not fully elucidated. It is, therefore, conceivable now that this literature merits to be revisited comprehensively. Possible multifaceted factors seem to be associated. These include neuroanatomical, hormonal, neuroimmunological, psychological, social and cultural aspects and comorbidities. This review aims at providing an overview of the substantial literature documenting the sex differences in pain and analgesic response to opioids from animal and human studies within the context of the modulatory effects of the aforementioned factors. A detailed and critical discussion of the cellular and molecular signaling pathways underlying the modulatory actions of gonadal hormones in the sexual dimorphism in pain processing and opioid analgesia is extensively presented. It is indicated that sexual dimorphic activation of certain brain regions contributes to differential pain sensitivity between females and males. Plausible crosstalk between sex hormones and neuroimmunological signaling pertinent to toll-like and purinergic receptors is uncovered as causal cues underlying sexually dimorphic pain and opioid analgesia. Conceivably, a thorough understanding of these factors may aid in sex-related advancement in pain therapeutic management.

Evaluating the efficacy of cannabidiol to manage surgically induced neuropathic pain in a preclinical rat model: Are T cells a sexually dimorphic target?

Background: Considering the poorly understood etiology and complex symptoms of chronic neuropathic pain (NP), the lack of effective treatments, and sex-dependent differences in the neuroimmune system as well as in antinociceptive responses to existing pharmacological agents, the potential to therapeutically target the endocannabinoid system as a means of treating this type of intractable pain is clinically relevant and timely. Chronic NP may involve the utilization of distinct immune cell populations in males and females that differentially affect supraspinal and spinal neuromodulation. It is therefore important to investigate the effects of cannabidiol (CBD) on chronic NP-induced nociceptive responses in both sexes.

Aims: Evaluating whether the expression of markers associated with CD4⁺ T cells are affected by CBD in a sexually dimorphic manner will provide key insights into the contribution of these adaptive immune cells to the onset and progression of NP.

Methods: Future research will be directed toward examining the potential sex-dependent effects of this nonpsychotropic cannabinoid relative to vehicle in a preclinical model of chronic postsurgical NP. Specifically, (1) differences in nociceptive behavior, (2) chronic changes in neural firing patterns, and (3) up- or downregulation of markers associated with CD4⁺ T cells in relevant tissues will be evaluated to better understand CBD-mediated neuroimmune modulatory effects in males and females.

Conclusions: Chronic postsurgical pain is a growing clinical problem. Current treatment strategies rely on opioid-based therapeutics, which affect patient quality of life and are associated with addiction and withdrawal. Treatment of nerve injuries with CBD could provide an effective alternative to manage NP. Understanding its mechanisms of action will provide important insights into the sex-dependent application of this nonpsychoactive cannabinoid, setting the groundwork for large-scale Canadian clinical trials in women and men presenting with chronic pain.

Auraptene regulates Th1/Th2/TReg balances, NF-κB nuclear localization and nitric oxide production in normal and Th2 provoked situations in human isolated lymphocytes

BACKGROUND

Auraptene as member of dietary coumarins, is found in citrus fruits. Former studies have demonstrated its anti-inflammatory and anti-cancer activity.

PURPOSE

The mechanism of action and immune-modulatory property of this compound on human lymphocytes are greatly unknown.

STUDY DESIGN/METHODS

The effect of three concentrations (10, 30 and 90 µM) of auraptene or dexamethasone (0.1 mM) were evaluated on percentage of cell proliferation and nitric oxide (NO) production as well as secretion and gene expression of cytokines, and NF-κB level in PHA-stimulated and non-stimulated lymphocytes.

RESULTS

In non-stimulated cells, all three concentrations of auraptene significantly increased the gene expression index of IL-10 (P < 0.05-0.001). The IFN-γ gene expression index, IFN-γ/IL-4 and IL-10/IL-4 gene expression ratio were significantly increased due to the high concentration (90 µM) of auraptene treatment compared to control group (P < 0.05-0.001). In PHA stimulation, all three concentrations of the extract significantly decreased proliferation, cytokines (IL-4, IL-10 and IFN-γ) and NF-κB level as well as NO production, but IFN-γ/IL-4 and IL-10/IL-4 ratio were significantly increased compared control group (P < 0.05-0.001). Gene expression of IL-10 and IL-4 was decreased but that of IFN-γ as well as FN-γ/IL-4 and IL-10/IL-4 ratio were significantly increased due to all three concentrations of auraptene.

CONCLUSION

The results showed promoting effects of auraptene on T cell subsets toward Th1 (IFN-γ) and Treg (IL-10), which suggest its therapeutic value for treatment of Th2 cells predominant diseases including allergic disease such as asthma and atopic dermatitis as well as cancers.

The influence of hydro-ethanolic extract of Portulaca oleracea L. on Th1/Th2 balance in isolated human lymphocytes

ETHNOPHARMACOLOGICAL RELEVANCE

The anti-inflammatory and anti-oxidants activity of Portulaca oleracea L. (P. oleracea) were mentioned in traditional texts. In previous studies, different anti-inflammatory and anti-oxidant effects of P. oleracea were demonstrated. However, the mechanism of action and immunomodulatory property of this plant are greatly unknown. In the present study, the effect of the extract of this plant on IL-4, IL10, IFN-γ and T helper (h)1/Th2 balance in non-stimulated and stimulated human lymphocytes was examined.

MATERIALS AND METHODS

The effect of three concentrations (160, 40 and 10µg/ml) of P. oleracea or dexamethasone were evaluated on percentage of cell proliferation and nitric oxide (NO) production as well as secretion of cytokines (IL-4, IL10 and IFN-γ) in PHA-stimulated and non-stimulated lymphocytes, and compared to control and dexamethasone as positive control (n=15 for each group).

RESULTS

In stimulated cells, dexamethasone significantly inhibited the percentage of cell proliferation, NO production, and secretion of cytokines in comparison to control group (P<0.001 for all cases). The percentage of cell proliferation, NO production, and secretion of cytokines were significantly decreased while Th1/Th2 (IFN-γ/IL-4) and Treg/Th2 (IL-10/IL-4) balances significantly enhanced in treated groups with all three concentrations of extract compared to control group (P<0.001 for all cases). The effect of all concentrations of the extract on cell proliferation, NO production and secretion of cytokines as well as Treg/Th2 balance were significantly lower than dexamethasone (P<0.001 for all cases), but Th1/Th2 ratio obtained in the presence of only low extract concentration was lower than dexamethasone (P<0.01).

CONCLUSION

Different concentrations of extract promoted Th1/Th2 and Treg/Th2 balances which may suggest the therapeutic value of the plant in inflammatory disease associated with decreased Th1/Th2 balance such as asthma or cancers.

Sex Differences in Pain

Females greatly outnumber males as sufferers of chronic pain. Although social and psychological factors certainly play a role in the differences in prevalence and incidence, biological differences in the functioning of the immune system likely underlie these observed effects. This Review examines the current literature on biological sex differences in the functioning of the innate and adaptive immune systems as they relate to pain experience. With rodent models, we and others have observed that male mice utilize microglia in the spinal cord to mediate pain, whereas females preferentially use T cells in a similar manner. The difference can be traced to differences in cell populations, differences in suppression by hormones, and disparate cellular responses in males and females. These sex differences also translate into human cellular responses and may be the mechanism by which the disproportionate chronic pain experience is based. Recognition of the evidence underlying sex differences in pain will guide development of treatments and provide better options for patients that are tailored to their physiology. © 2016 Wiley Periodicals, Inc.

Blood immune function parameters in response to combined aerobic dance exercise and honey supplementation in adult women

To date, information on the effectiveness of combined aerobic dance exercise with honey supplementation on immune function in women is lacking. The present study investigated the effects of 8 weeks of combined aerobic dance exercise and honey supplementation on blood immune function parameters in adult women. In this study, forty four healthy sedentary women (25-40 year-old) were assigned into four groups with n = 11 per group: sedentary without supplementation control (Con), honey supplementation (H), aerobic dance exercise (D) and combined aerobic dance exercise with honey supplementation (HD) groups. Aerobic dance exercise was carried out for one hour per session, three sessions per week for eight weeks. Honey drink was consumed by H and HD groups, in a dosage of 20 g of honey diluted in 300 ml of plain water, consumed 7 days a week for 8 weeks. In HD group, the participants were required to consume honey drink 30 min before performing exercise. Before and after 8 weeks of experimental period, blood samples were taken to determine the concentrations of immune parameters which include full blood counts and immunophenotyping measurements. It was found that after 8 weeks of experimental period, there were statistically significant increases in T cytotoxic (CD8) (p < 0.05) in HD group. Additionally, the percentages increase in total lymphocyte counts, T helper (CD4), and T cytotoxic (CD8) counts after 8 weeks were the highest in HD group among all the groups. As conclusion, combined aerobic dance and honey supplementation may have potential to enhance immune functions in women.

Effect of a single finnish sauna session on white blood cell profile and cortisol levels in athletes and non-athletes

The aim of the present study was to investigate the effect of Finnish sauna bathing on a white blood cell profile, cortisol levels and selected physiological indices in athletes and non-athletes. The study evaluated 9 trained middle-distance runners and 9 male non-athletes. The subjects from both groups participated in 15-minute sauna sessions until their core temperature rose by 1.2°C (mean temperature in the sauna room was 96° ± 2°C; relative humidity was 15 ± 3%) with a 2 minute cool down with water at a temperature of 19–20°C. Body mass was measured before and after the session and blood samples were taken for tests. Rectal temperature was monitored at five-minute intervals during the whole session. Serum total protein, haematological indices and cortisol levels were determined. Sauna bathing caused higher body mass loss and plasma volume in the athletes compared to the group of non-athletes. After the sauna session, an increased number of white blood cells, lymphocyte, neutrophil and basophil counts was reported in the white blood cell profile. Higher increments in leukocyte and monocyte after the sauna bathing session were recorded in the group of athletes compared to untrained subjects. The obtained results indicated that sauna bathing stimulated the immune system to a higher degree in the group of athletes compared to the untrained subjects.

Differences in plasma cytokine levels between elite kayakers and nonathletes

Regular moderate exercise has been shown to have anti-inflammatory effects that help prevent several chronic diseases. However, the effects of chronic training an elite athletes have not been the focus of much research. This study aimed to determine whether there were differences in cytokine levels (IL-1β, IL-1ra, IL-6, IL-10, IL-18, IFN-γ, and TNF-α) in circulating peripheral blood (PB) between elite kayakers and nonathletes. Subjects were 13 elite male kayakers, aged 20.0 ± 3 years, with average body mass of 75.0 ± 7.9 kg and 177.3 ± 7.1 cm height and with a VO_2max of 58.3 ± 7.8 mL·kg⁻¹·min⁻¹. The nonathletes were 7 men, aged 18.2 ± 1.1 years, body mass of 81.3 ± 13.8 kg, and 171.9 ± 4.5 cm height. Blood samples were collected after six weeks of offtraining and before the start of a new training season. PB leukocyte populations were determined by flow cytometry. Cytokine levels were quantified by ELISA. When nonathletes were compared with the kayakers, the latter exhibited lower plasma concentrations of IL-1β, IL-18, and IFN-γ as well as a lower concentration of IL-1ra. Positive correlations between IL-18 and B cells in the athletes were also found. These results seem to reinforce the anti-inflammatory role of regular training.

Fish oil supplementation augments post-exercise immune function in young males

PURPOSE

Fish oils and related fatty acid components have anti-inflammatory properties, with beneficial effects against various disorders such as cardiovascular disease. A single bout of exercise can alter immune function. However, the effects of fish oil on immune function after a single bout of exercise are currently unknown. This study investigated the effect of supplementation with fish oil on the immune response to an acute bout of endurance exercise.

METHODS

Sixteen male subjects underwent a six week double blind randomised placebo controlled supplementation trial involving two groups (fish oil or placebo oil, 3g/day). They attended for two visits, the first involving a maximal exercise test and the second involving a 1-h bout of endurance exercise on a cycle ergometer at 70% (V)O(2peak). Blood samples were taken pre-supplementation, pre-exercise (post-supplementation), immediately, 1 and 3h post-exercise. Samples were analysed for plasma IL-6, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and cortisol; peripheral blood mononuclear cell (PBMC) IL-2, IL-4 and IFN-γ production; neutrophil phagocytosis/oxidative burst; and natural killer (NK) cell cytotoxic activity.

RESULTS

Post-supplementation EPA concentration was increased (P=0.0127) in the fish oil group. At 3h post-exercise PBMC IL-2 (P=0.0067) and NK cell activity (P=0.0163) was greater in the fish oil compared with the control group. However, PBMC IL-4 and IFN-γ productions, plasma IL-6 and cortisol concentrations, as well as neutrophil activity were unaffected by fish oil supplementation.

CONCLUSION

The current study demonstrates that fish oil supplementation reduces increases PBMC IL-2 production and NK cell cytotoxic activity in the recovery period after exercise.

The impact of water-floating and high-intensity exercise on rat's HPA axis and interleukins concentrations

Our studies explore the changes of blood corticosterone (CORT), adrenocorticotropic hormone (ACTH), interleukin (IL)-1β, IL-2, IL-6 concentrations and the pituitary ACTH expression in rats after water floating in the presence or absence of following high-intensity exercise. The rats were randomly assigned into three groups. Group A served as control; Group B received 180 minutes water floating and psychological (fear) stimulation; Group C received the same treatment as Group B in addition and 120-minutes non-stop running. Compared to Group A, Group B showed a significant increase of IL-2 (19.91 ± 2.52 vs. 13.09 ± 3.13 ng/ml, P < 0.05), and IL-6 (0.18 ± 0.08 vs. 0.12 ± 0.05 ng/ml, P < 0.05); Group C demonstrated a significant increase of CORT (977.22 ± 207.36 ng/ml vs. 434.58 ± 110.45 ng/ml, P <0.01) and IL-1β (0.21 ± 0.04 vs. 0.16 ± 0.06 ng/ml, P < 0.05), IL-2 (20.29 ± 4.23 vs. 13.09 ± 3.13 ng/ml, P < 0.05), and IL-6 (0.19 ± 0.03 vs. 0.12 ± 0.05 ng/ml, P < 0.05) levels, and a significant decrease of ACTH (16.95 ± 5.46 vs. 22.96 ± 7.32 pg/ml, P = 0.03). Immunohistochemical staining showed the decreased number of pituitary ACTH-positive cells in both Groups B and C (P < 0.05) as compared to Group A. These results have lead us to believe that acute psychological stress can activate the pituitary-adrenal axis and lead to elevation of serum IL-2, IL-6 concentrations. Combined with high-intensity exercise, it can result in the increase of serum CORT, IL-1β, IL-2, IL-6 levels, and the suppression of ACTH.

Asthma and dehydroepiandrosterone (DHEA): facts and hypotheses

Dehydroepiandrosterone (DHEA) is considered as an important immunomodulating and anti-inflammatory hormone. Despite the continuing interest in DHEA replacement therapy, our knowledge of its effects upon asthma is very limited. DHEA is able to reverse cytokine imbalances associated with asthma, may prevent and attenuate allergic inflammation in airways, and does not possess the undesirable side effects of glucocorticoids; therefore, it may be potentially applied in the treatment of asthma. The steroid-sparing effect observed with DHEA clinically could appear especially favorable in asthmatic patients receiving oral treatment and those inhaling high doses of glucocorticoids. In addition, DHEA and its analogs might prove useful in reversing relative glucocorticoids insensitivity in patients with corticosteroid-resistant asthma. In this review we have focused specifically on DHEA's role in asthma.

Dehydroepiandrosterone as a regulator of immune cell function

Dehydroepiandrosterone (DHEA) is a C19 steroid of adrenal origin. Notably, its secretion declines with age, a phenomenon referred to as the "adrenopause". For many years, the physiological significance of DHEA remained elusive. However, many studies have now shown that DHEA has significant immune modulatory function, exhibiting both immune stimulatory and anti-glucocorticoid effects. Although several of these studies are limited by the fact that they were carried out in rodents, who are incapable of adrenal DHEA production, and therefore have very low circulating levels of this steroid, evidence from the study of immune cells is now accumulating to suggest a role for DHEA in regulating human immunity. This ability to regulate immune function has raised interest in the therapeutic potential of DHEA as a treatment for the immunological abnormalities that arise in subjects with low circulating levels of this hormone. This has included attempts at reversing the impaired immune response of older individuals to vaccination and restoring immune regulation in patients with chronic autoimmune disease. This review summarises the reported effects of DHEA on immune function and discusses the therapeutic potential of this steroid in geriatric medicine and particularly in age-related disease with an immune component.

Effect of Glucocorticoid and Melatonin on Immune Function of an Indian Tropical Bird, Perdicula Asiatica: An in Vivo and in Vitro Study

Inverse relationship between circulatory levels of glucocorticoids and melatonin has been reported for most of the vertebrates including human beings. We report the importance of glucocorticoid along with melatonin in avian immune regulation in an Indian tropical bird, Perdicula asiatica with in vivo and in vitro approach. Dexamethasone (30μg/bird/day) treatment of the male birds suppressed the immune activity as judged by the spleen activity (mass, anatomy), circulating total leukocyte, and lymphocyte count, blastogenic response, increased % apoptosis and cytokine (IL-2) production by splenocytes. Melatonin (25μg/100g B.wt./day) treatment increased the above-mentioned immune parameters whereas melatonin together with dexamethasone restored the suppressed immune parameters by dexamethasone to control level. In vitro melatonin (2.5 pM) supplementation to splenocyte cultures restored the dexamethasone (2 μM) suppressed splenocyte proliferation, % apoptosis and IL-2 production. Therefore, melatonin antagonized the suppressive effect of synthetic glucocorticoid on all immune parameters studied in vivo as well as in vitro. Furthermore, exogenous administration of dexamethasone and melatonin treatment altered the circulatory level of corticosterone and melatonin in an inverse manner. It is therefore, suggested that a hormonal trade-off between glucocorticoid and melatonin exists under in vivo and in vitro conditions, being involved in maintenance of the immune function of P. asiatica probably by involving cytokines i.e. IL-2 mediated pathway.

Imunoglobulina A salivar (IgA-s) e exercício: relevância do controle em atletas e implicações metodológicas

O objetivo do presente estudo é realizar uma análise e discussão dos principais achados envolvendo o comportamento da imunoglobulina A salivar (IgA-s) em relação ao estímulo do exercício e evidenciar a importância de seu controle em atletas. O exercício físico é um importante modulador das características do sistema imune, sobretudo do comportamento da IgA-s, componente fundamental na proteção de infecções do trato respiratório superior (ITRS). No entanto, a relação direta entre baixas concentrações de IgA-s e ITRS precisa de mais evidências para ser confirmada. As concentrações de IgA-s durante e logo após um exercício intenso diminuem, deixando o indivíduo mais suscetível à infecção, porém, atletas envolvidos em atividades extenuantes não são clinicamente imunodeficientes, comparados com indivíduos sedentários. Essas modificações são transitórias, com retorno aos valores normais após aproximadamente 48 horas de repouso. A razão dessas alterações não é clara, mas se apresenta multifatorial: elevação de hormônios estressores; fatores nutricionais; ação de espécies reativas de oxigênio; e estresse psicológico. Apesar do efeito transitório das alterações provocadas nos elementos do sistema imune frente ao exercício, observa-se diferença na variabilidade da IgA-s em populações com diferentes níveis de condicionamento. Diferenças metodológicas - como o protocolo de exercício, o método de coleta, armazenamento e manipulação da saliva, a forma de expressão da IgA-s, o nível de hidratação, o controle da dieta, a sazonalidade do período de competição, a aclimatação entre outros fatores - devem ser levadas em consideração para comparação entre os estudos. Além disso, ajudam a explicar, em parte, os resultados adversos envolvendo exercício moderado e os intermitentes, em que se encontram aumento, redução e até ausência de alteração nos níveis de IgA-s. Investigações de elementos inovadores, como os toll-like receptors, e o avanço tecnológico podem colaborar para aumentar as evidências sobre o tema.

Inhibitory effect of rapamycin and dexamethasone on production of IL-17 and IFN-gamma in Vogt-Koyanagi-Harada patients

AIMS

To evaluate the effect of rapamycin (RAPA) and dexamethasone (DEX) on the production of IL-17 and IFN-gamma by peripheral blood mononuclear cells (PBMCs) from Vogt-Koyanagi-Harada (VKH) patients and healthy individuals.

METHODS

Blood samples were drawn from 10 active VKH patients and 10 healthy individuals. PBMCs were cultured with or without anti-CD3 and anti-CD28 antibodies in the presence or absence of different concentrations of RAPA or DEX for 72 h. IL-17 and IFN-gamma concentrations in the supernatants were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The expression of IL-17 and IFN-gamma was significantly increased in active VKH patients compared with that in healthy controls. Both RAPA and DEX were able to significantly inhibit the production of IL-17 and IFN-gamma by PBMCs from patients and healthy controls. RAPA was able to completely inhibit IL-17 production at a dosage of 10 ng/ml but only partially suppressed IFN-gamma production even at a much higher concentration (1000 ng/ml). DEX inhibited the production of both IL-17 and IFN-gamma by approximately 70%.

CONCLUSIONS

This study indicates that both RAPA and DEX inhibit the production of IL-17 and IFN-gamma by PBMCs. RAPA is much stronger in inhibiting the production of IL-17 than DEX.

Dehydroepiandrosterone increases resistance to experimental infection by Trypanosoma cruzi

Dehydroepiandrosterone (DHEA) enhances immune responses against a wide range of viral, bacterial, and parasitic pathogens. In a previous study, we reported that administration of DHEA significantly decreased the numbers of blood parasites in Trypanosoma cruzi experimental infection. The present study was undertaken to determine the effectiveness of DHEA in reducing the severity of acute phase T. cruzi infection of male and female Wistar rats. Animals were treated subcutaneously with 40 mg/kg body weight/day of DHEA. The concentration of nitric oxide (NO) was determined in spleen peritoneal cavity. Interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) were determined in the sera of uninfected and infected animals. DHEA treatment augments NO production for both sexes after in vitro LPS treatment for uninfected animals. Infection triggered enhanced NO levels although not significant. IL-2 and IFN-gamma were detectable in higher concentrations in treated and infected rats of both genders when compared to untreated controls. These data suggest that DHEA may have a potent immunoregulatory function that can affect the course of T. cruzi infection.

Markers to measure immunomodulation in human nutrition intervention studies

Normal functioning of the immune system is crucial to the health of man, and diet is one of the major exogenous factors modulating individual immunocompetence. Recently, nutrition research has focused on the role of foods or specific food components in enhancing immune system responsiveness to challenges and thereby improving health and reducing disease risks. Assessing diet-induced changes of immune function, however, requires a thorough methodological approach targeting a large spectrum of immune system parameters. Currently, no single marker is available to predict the outcome of a dietary intervention on the resistance to infection or to other immune system-related diseases. The present review summarises the immune function assays commonly used as markers in human intervention studies and evaluates their biological relevance (e.g. known correlation with clinically relevant endpoints), sensitivity (e.g. within- and between-subject variation), and practical feasibility. Based on these criteria markers were classified into three categories with high, medium or low suitability. Vaccine-specific serum antibody production, delayed-type hypersensitivity response, vaccine-specific or total secretory IgA in saliva and the response to attenuated pathogens, were classified as markers with high suitability. Markers with medium suitability include natural killer cell cytotoxicity, oxidative burst of phagocytes, lymphocyte proliferation and the cytokine pattern produced by activated immune cells. Since no single marker allows conclusions to be drawn about the modulation of the whole immune system, except for the clinical outcome of infection itself, combining markers with high and medium suitability is currently the best approach to measure immunomodulation in human nutrition intervention studies. It would be valuable to include several immune markers in addition to clinical outcome in future clinical trials in this area, as there is too little evidence that correlates markers with global health improvement.

Immune function in sport and exercise

Regular moderate exercise is associated with a reduced incidence of infection compared with a completely sedentary state. However, prolonged bouts of strenuous exercise cause a temporary depression of various aspects of immune function (e.g., neutrophil respiratory burst, lymphocyte proliferation, monocyte antigen presentation) that usually lasts approximately 3-24 h after exercise, depending on the intensity and duration of the exercise bout. Postexercise immune function dysfunction is most pronounced when the exercise is continuous, prolonged (>1.5 h), of moderate to high intensity (55-75% maximum O(2) uptake), and performed without food intake. Periods of intensified training (overreaching) lasting 1 wk or more may result in longer lasting immune dysfunction. Although elite athletes are not clinically immune deficient, it is possible that the combined effects of small changes in several immune parameters may compromise resistance to common minor illnesses, such as upper respiratory tract infection. However, this may be a small price to pay as the anti-inflammatory effects of exercise mediated through cytokines and/or downregulation of toll-like receptor expression are likely mediators of many of the long-term health benefits of regular exercise.

Immune system adaptation in elite athletes

PURPOSE OF REVIEW

To evaluate the effects of exercise on immune function in relation to infection susceptibility.

RECENT FINDINGS

Postexercise immune function depression is most pronounced when exercise is continuous, prolonged, of moderate to high intensity and performed without food intake. Periods of intensified training that result in overreaching have been shown to chronically depress immune function, with leukocyte functions measured at rest still depressed 24 h after the last exercise bout. Several studies indicate that the incidence of symptoms of upper respiratory tract illness is increased in the days following prolonged strenuous endurance events and it has been generally assumed that this is due to the temporary exercise-induced depression of immune function. More recently it has been proposed that at least some of these symptoms are attributable to inflammation of the upper respiratory tract rather than to infectious episodes.

SUMMARY

Although elite athletes are not clinically immune deficient, it is possible that the combined effects of small changes in several immune parameters may compromise resistance to common minor illnesses. Although it is possible that immune depression linked with prolonged intensive training may determine susceptibility to infection, convincing evidence of a cause and effect relationship remains elusive.

Xenobiotic-induced alterations in thymocyte development

The thymus is a very sensitive target for environmental pollutants, which can affect this organ as well as thymocyte differentiation. A failure in thymocyte development can be due to the exacerbation of apoptosis, arrest of thymocyte maturation, generation of autoreactive T cells, and inhibition or stimulation of the output of recent thymic emigrants to the periphery. Recent data demonstrate that the immune system has the potential to maintain homeostasis under conditions of elevated risk, and the thymus plays a crucial role in this process. Environmental xenobiotics can exert their effects through receptor-mediated interactions or independently on receptor involvement. Under natural conditions organisms are exposed to a variety of xenobiotics. The final effect of such exposure is not related to the action of a single chemical, but to the action of a mixture of chemicals. The toxic effect of environmental xenobiotics on the generation and functions of immune cells may result in suppression or stimulation of the immune response. The most intensive studies have been done on halogenated aromatic hydrocarbons, heavy metals and various chemicals acting as endocrine disrupters. Recently, special interest has focused on the action of air particulate matter.

Differential effect of DHEA on mitogen-induced proliferation of T and B lymphocytes

Dehydroepiandrosterone (DHEA) is the predominant steroid hormone secreted by adrenal gland, and it has been proposed in recent years that DHEA has significant effects on immune function. We investigated the effect of DHEA (1 x 10(-5) - 1 x 10(-8)M) on proliferation of human T cells and B cells and on immunoglobulin production, a representative function of B cells. High doses of DHEA (1 x 10(-5)) significantly inhibited proliferation of peripheral blood mononuclear cells (PBMCs) and T cells induced by T cell mitogens hemagglutinin (PHA) and concanavalin A (Con A). Proliferation of PBMCs induced by B cell mitogens pokeweed mitogen (PWM) was increased by 1 x 10(-7) - 1 x 10(-6)M DHEA. Proliferation of PBMCs and B cells induced by Staphylococcus aureus Cowan strain I (SAC) was not significantly changed at any concentrations of DHEA. However, a concentration of 1 x 10(-7)M DHEA tended to potentiate their proliferation. This study suggested that DHEA acted on T and B lymphocytes differentially in immune system.

The effects of dehydroepiandrosterone (DHEA) on in vitro spleen cell proliferation and cytokine production

Dehydroepiandrosterone (DHEA), a weak androgenic steroid, has been associated with enhancing immune responses and upregulating resistance against viral, parasitic, and bacterial infections. The objective of this study was to assess the effects of DHEA on murine spleen cell viability, proliferation, and cytokine production following in vitro stimulation with the mitogens concanavalin A (ConA) and lipopolysaccharide (LPS). Results showed that exposure to 6 microM DHEA significantly decreased the viability and proliferation of murine spleen cells stimulated with LPS, whereas no effect was seen on murine spleen cells stimulated with ConA. DHEA did influence the production of both ConA-induced and LPS-induced cytokines. DHEA also significantly reduced the mitogen-induced production of the proinflammatory cytokine interleukin-1 (IL-1) as well as the Th1 cytokines IL-2 and interferon-gamma (IFN-gamma). Increasing concentrations of DHEA significantly increased the production of the Th2 cytokine IL-10 but had no effect on the production of the Th2 cytokine IL-4, the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha), or IL-6. These results suggest that DHEA may be an important factor for increasing Th2 cytokine production and decreasing Th1 and proinflammatory cytokine production. This study provides a more comprehensive understanding of the effects of DHEA on the rates of cell proliferation, cell viability, and cytokine production.

Sleep-like concentrations of growth hormone and cortisol modulate type1 and type2 in-vitro cytokine production in human T cells

Slow wave sleep (SWS) is characterized by maximum release of growth hormone (GH) and minimum release of cortisol. We hypothesized that this hormonal pattern during SWS leads, in addition to generally increased T cell cytokine production, to a shift towards type1 cytokines. To test this hypothesis, blood was sampled from 8 humans during SWS, and whole blood cultures were activated in-vitro with ionomycin and phorbol-myrestate-acetate (PMA) in the absence and presence of GH neutralizing antibody (Ab) or physiological concentrations of cortisol. Production of interferon-gamma (IFN-gamma), interleukin-2 (IL-2), IL-4, and tumor necrosis factor-alpha (TNF-alpha) was measured using multiparametric flow cytometry. GH Ab decreased IFN-gamma+CD4+ cells but had no effect on other cytokines. Cortisol alone and in combination with GH Ab decreased CD4+ and CD8+ cells producing IFN-gamma, TNF-alpha and IL-2. Simultaneously, these two reactants reduced IL-4+CD4+ cells, so that the ratio of IFN-gamma/IL4 producing CD4+ cells indicated an unexpected shift towards type1 dominance. Results support the view that release of GH by increasing particularly production of IFN-gamma can contribute to the shift in type1/type2 balance towards type1 activity characterizing SWS. Suppression of cortisol during this sleep period enhances both type1 and type2 activity. Yet, our finding of predominant type1 activity after cortisol administration, rules out any relevance of this suppression for the shift towards type1 activity during SWS.

Pregnancy associated hormones modulate the cytokine production but not the phenotype of PBMC-derived human dendritic cells

OBJECTIVE

Dendritic cells (DC) play a central role in initiating and polarizing immune responses. As effects of pregnancy associated hormones on phenotype and function of DC are unknown, our objective was to test the influence of progesterone, beta-estradiol and betaHCG on immature (iDC) and mature (mDC) DC.

STUDY DESIGN

DC generated from peripheral-blood-monocytes were exposed to different doses of hormones. DC phenotype was determined by FACS-analysis of surface marker expression (CD40, CD86, CD83 and HLA-DR). Modifications in the secretion of cytokines (IL12p70, IL-18, IL-10, IL-6, TNFalpha) and chemokines (MDC, IL-8) were analysed by ELISA. T cell stimulatory capacity of mDC was assessed by mixed lymphocyte reaction.

RESULTS

Incubation with progesterone or estradiol resulted in a significant upregulation of IL-10 production by iDC and mDC. Combinations of progesterone and betaHCG or estradiol respectively induced a significant decrease in production of IL-18 by mDC. No significant changes could be observed in surface marker expression or T cell stimulatory capacity, neither in cultures of DC matured under influence of progesterone, estradiol nor betaHCG.

CONCLUSIONS

PBMC-derived DC seem to be relatively stable against the influence of pregnancy associated hormones apart from particular effects on cytokine production which partly could contribute to the modification of immune responses observed in normal early pregnancy.

Effect of foot shock stress on the interferon-gamma production of murine intestinal intraepithelial lymphocytes

To investigate the effect of stress on interferon (IFN)-gamma production by intestinal intraepithelial lymphocytes (IEL), we exposed male C3H/HeN mice to electric foot shock for 30 min a day for 5 consecutive days. Immediately after the final foot shock stress, IEL from small intestine were isolated by Percoll density gradient. The stress induced a marked suppression of IFN-gamma production by IEL stimulated with immobilized anti-CD3 mAb and a marked decrease in the proportion of IFN-gamma-producing CD3+ IEL or alphabetaTCR+ IEL stimulated with PMA+ionomycin. The alphabetaTCR+ subset was the major cause of stress-induced suppression of IFN-gamma production by IEL. Glucocorticoid induced the suppression of IFN-gamma production by IEL in vitro, which was reversed by mifepristone (RU486), a glucocorticoid receptor antagonist. In vivo administration of RU486 reversed the stress-induced suppression of IFN-gamma production by IEL. In conclusion, repeated foot shock stress suppressed IFN-gamma production of IEL by stress-induced elevation of endogenous glucocorticoid. Substantial suppression of the alphabetaTCR+ subset was the major cause of the suppression.

The Neuroendocrine–Immune Interactions in Systemic Lupus Erythematosus: A Basis for Understanding Disease Pathogenesis and Complexity

Much progress has been made in the understanding of the impact of the neuroendocrine immune interactions and the pathogenic role in systemic lupus erythematosus, clinically and at the molecular level. This article focuses on the intertwining networks that involve the hypothalamic-pituitary-adrenal axis, cytokines within the central nervous system, and the sympathetic system. Hormones (estrogen, prolactin, gonadotropin-releasing hormone, and leptin) play an important role as immunomodulatory agents.

Prolactin (PRL) up-regulates Indoleamine 2,3-dioxygenase (IDO) expression in CD14+ cells

Indoleamine 2,3-dioxygenase (IDO), one of the enzymes of tryptophan catabolism, has been shown to play an essential role for successful pregnancy through the inhibition of allogenic fetus-induced T-cell proliferation, and interferon-gamma (IFN-gamma) induces the expression of IDO in CD14-positive (CD14(+)) cells. On the other hand, prolactin (PRL) is the hormone whose serum levels drastically elevate during pregnant period and is shown to play an important role in the early stages of pregnancy including implantation. However little is known about the physiological significance of the elevation of PRL from second trimester except for its fundamental role in lactation. Since receptors of PRL and IFN-gamma share their structure and the signal transduction pathway, we hypothesized the potential crosstalk between two substances. To test this idea, we examined the effect of PRL on IFN-gamma-induced IDO expression in CD14(+) cells. CD14(+) cells were prepared from peripheral blood of 12 healthy controls who had informed consent, and IDO expression and transcriptions were analyzed by flow cytometry and RT-PCR. The results showed that although PRL by itself had little effect on IDO expression, PRL significantly enhanced the IFN-gamma-induced IDO expression at comparable to those seen in a pregnant period. In contrast, no such effect was observed with PRL at lower concentrations comparable to those seen in a non-pregnant period. These findings suggest that PRL may contribute to the maintenance of pregnancy by augmenting IFN-gamma induction of IDO expression.

Repeated Stress Suppresses Interferon-.GAMMA. Production by Murine Intestinal Intraepithelial Lymphocytes

Intestinal intraepithelial lymphocytes (IEL), one of the major effector components in the mucosal immune system, are phenotypically and functionally distinct from thymic and peripheral T cells. To investigate the effect of repeated stress on the number and function of IEL, we exposed male C3H/HeN mice to mild electric foot shock for 30 min/day for 5 consecutive days. Immediately after the final foot shock stress, the blood, spleen, thymus and small intestine of each of the mice were obtained. As a functional measure, we evaluated interferon (IFN)- gamma production by IEL, since IFN-gamma is a key immunomodulating cytokine in mucosal immune responses. Serum corticosterone level was elevated immediately after foot shock stress. There were no significant changes in the number of whole IEL and CD3+ IEL subsets after the stress. In contrast, the stress led to a significant decrease in the total number of thymocytes, particularly the reduction in the number of CD4+CD8+ thymocytes. Thymocytes expressed the highest level of intracellular glucocorticoid receptor (GR), followed by splenocytes and IEL. The foot shock stress induced a marked suppression of IFN-gamma production by IEL, when stimulated with immobilized anti-CD3 monoclonal antibody. Furthermore, corticosterone suppressed the IFN-gamma production by cultured IEL, which was prevented by Mifepristone (RU486), a GR antagonist. In summary, repeated foot shock stress did not alter the numbers of IEL and CD3+ IEL subsets, but suppressed IFN-gamma production by IEL, which was probably mediated by the elevated corticosterone. We therefore propose that stress influences host defense by suppressing the production of IFN-gamma in IEL.

Hormonal and immunological mechanisms mediating sex differences in parasite infection

The prevalence and intensity of infections caused by protozoa, nematodes, trematodes, cestodes, and arthropods is higher in males than females. The primary thesis of this review is that immunological differences exist between the sexes that may underlie increased parasitism in males compared to females. Several field and laboratory studies link sex differences in immune function with circulating steroid hormones; thus, the roles of sex steroids, including testosterone, oestradiol, and progesterone, as well as glucocorticoids will be discussed. Not only can host hormones affect responses to infection, but parasites can both produce and alter hormone concentrations in their hosts. The extent to which changes in endocrine-immune interactions following infection are mediated by the host or the parasite will be considered. Although males are more susceptible than females to many parasites, there are parasites for which males are more resistant than females and endocrine-immune interactions may underlie this sex reversal. Finally, although immunological differences exist between the sexes, genetic and behavioural differences may explain some variability in response to infection and will be explored as alternative hypotheses for how differences between the sexes contribute to dimorphic responses to parasites.

Severity of murine collagen-induced arthritis correlates with increased CYP7B activity: enhancement of dehydroepiandrosterone metabolism by interleukin-1beta

OBJECTIVE

The endogenous steroid dehydroepiandrosterone (DHEA) has been reported to play a role in rheumatoid arthritis (RA). DHEA is metabolized by the P450 enzyme CYP7B into 7alpha-OH-DHEA, which has immunostimulating properties. This study was undertaken to investigate the putative role of CYP7B in arthritis using murine collagen-induced arthritis (CIA), an interleukin-1beta (IL-1beta)-dependent model.

METHODS

DBA/1J mice were immunized and administered a booster with type II collagen. The presence of 7alpha-OH-DHEA was determined in both arthritic and nonarthritic joints and the serum of CIA mice by radioimmunoassay. CYP7B messenger RNA (mRNA) expression was analyzed in synovial biopsy samples, and in fibroblast-like synoviocytes (FLS) isolated from these synovial biopsy samples, by reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, the regulatory role of IL-1beta on CYP7B activity in FLS was determined using RT-PCR, Western blotting, and high-performance liquid chromatography.

RESULTS

In knee joint synovial biopsy samples from arthritic mice, 7alpha-OH-DHEA levels were 5-fold higher than in nonarthritic mice. Elevated levels of 7alpha-OH-DHEA were accompanied by an increase in CYP7B mRNA expression and were positively correlated with disease severity. In serum, no differences in 7alpha-OH-DHEA levels were observed between arthritic and nonarthritic mice. Incubation of FLS with IL-1beta resulted in a dose-dependent increase in 7alpha-OH-DHEA formation. In addition, IL-1beta enhanced CYP7B mRNA and CYP7B protein levels in FLS.

CONCLUSION

Disease progression in CIA is correlated with enhanced CYP7B activity, which leads to locally enhanced 7alpha-OH-DHEA levels. Elevated IL-1beta levels within the arthritic joint may regulate this increase in CYP7B activity.

Effect of prolonged exercise and carbohydrate ingestion on type 1 and type 2 T lymphocyte distribution and intracellular cytokine production in humans

The present study was undertaken to examine the role of the exercise-induced stress hormone response on the regulation of type 1 and type 2 T lymphocyte intracellular cytokine production. Subjects performed 2.5 h of cycling exercise at 65% maximal O2 uptake while ingesting a 6.4% carbohydrate (CHO) solution, 12.8% CHO solution, or a placebo. Peripheral whole blood samples were stimulated and stained for T lymphocyte surface antigens (CD4 and CD8). Cells were then permeabilized, stained for intracellular cytokines, and analyzed using flow cytometry. Exercise resulted in a decrease (P < 0.05) in the number and percentage of IFN-gamma positive CD4+ and CD8+ T lymphocytes. These stimulated cells produced less IFN-gamma immediately postexercise (P < 0.05) and 2-h postexercise (P < 0.05) compared with preexercise. However, CHO ingestion, which attenuated the exercise-induced stress hormone response compared with placebo (P < 0.05), prevented both the decrease in the number and percentage of IFN-gamma-positive CD4+ and CD8+ T lymphocytes and the suppression of IFN-gamma production from stimulated CD4+ and CD8+ T lymphocytes. There was no effect of exercise on the number of, or cytokine production from, IL-4-positive CD4+ or CD8+ T lymphocytes. These data provide support for the role of exercise-induced elevations in stress hormones in the regulation of type 1 T lymphocyte cytokine production and distribution.

Ingestion of a Dietary Supplement Containing Dehydroepiandrosterone (DHEA) and Androstenedione Has Minimal Effect on Immune Function in Middle-Aged Men

OBJECTIVE

This study investigated the effects of four weeks of intake of a supplement containing dehydroepiandrosterone (DHEA), androstenedione and herbal extracts on immune function in middle-aged men.

DESIGN

Subjects consumed either an oral placebo or an oral supplement for four weeks. The supplement contained a total daily dose of 150 mg DHEA, 300 mg androstenedione, 750 mg Tribulus terrestris, 625 mg chrysin, 300 mg indole-3-carbinol and 540 mg saw palmetto.

MEASUREMENTS

Peripheral blood mononuclear cells were used to assess phytohemagglutinin(PHA)-induced lymphocyte proliferation and cytokine production. The cytokines measured were interleukin (IL)-2, IL-4, IL-10, IL-1beta, and interferon (IFN)-gamma. Serum free testosterone, androstenedione, estradiol, dihydrotestosterone (DHT) were also measured.

RESULTS

The supplement significantly increased serum levels of androstenedione, free testosterone, estradiol and DHT during week 1 to week 4. Supplement intake did not affect LPS or ConA proliferation and had minimal effect on PHA-induced proliferation. LPS-induced production of IL-1beta, and PHA-induced IL-2, IL-4, IL-10, or IFN-gamma production was not altered by the supplement. The addition of the same supplement, DHEA or androstenedione alone to lymphocyte cultures in vitro did not alter lymphocyte proliferation, IL-2, IL-10, or IFN-gamma, but did increase IL-4. In addition, serum HDL-C concentration significantly declined.

CONCLUSION

These findings suggest that, although chronic intake of a complex dietary supplement containing DHEA, androstenedione and herbal extracts increases serum androgen levels, it has minimal effect on immune function in middle-aged men.

Stress and the immune system

Stressors can positively or adversely affect immune and inflammatory responses. However, the current understanding of these effects at the cellular and molecular levels is not sufficient to allow prediction of the effects of a particular stressor on a particular immune or inflammatory function. Three complementary conceptual frameworks are presented that may prove useful in developing such an understanding. In addition, specific examples of the action of particular stress mediators on particular immune or inflammatory end points are discussed, and the relationship of these observations to the conceptual frameworks is indicated. Several of the effects discussed are relevant clinically, and the prospects for pharmacological intervention to prevent adverse effects of stressors on the immune system are discussed. Finally, some of the factors that can (sometimes unexpectedly) influence the outcome of stress-immunology studies and some of the pitfalls that continue to make this area of research controversial in some circles are discussed.

Dehydroepiandrosterone therapy ameliorates experimental autoimmune myasthenia gravis in Lewis rats

To detect a possible effect of dehydroepiandrosterone (DHEA) in the pathogenesis of experimental autoimmune myasthenia gravis (EAMG), DHEA (0.5 mg/rat) was administrated intraperitoneally to Lewis rats every other day from day 4 postimmunization (p.i.) to day 35 p.i. with Torpedo acetylcholine receptor (AChR) and Freund's complete adjuvant. Rats treated with DHEA had a lower clinical score (mean clinic score, 2 versus 0.5 on day 37 p.i.) and a lower body weight loss (mean body weight, 169 versus 142 g on day 37 p.i.) compared with control EAMG rats. DHEA treatment decreased serum anti-AChR IgG and IgG2b antibody titers on days 7, 14, and 21 p.i. and inhibited the levels of anti-AChR IgG antibody secreting cells (60%), accompanied by decreased IL-4 (33%) and augmented TGF-beta1-positive cells (41%) among lymph node mononuclear cells. These results obtained from EAMG in Lewis rats further encourage us to study DHEA treatment in human MG.

Contrasting pattern of cytokines in antigen- versus mitogen-stimulated splenocyte cultures from chemically denervated mice

Sympathetic nervous system (SNS) regulation of immune function has been studied by ablating the SNS with a peripheral injection of the neurotoxin 6-hydroxydopamine (6-OHDA). Our previous data indicate that sympathectomy of mice results in enhanced antibody production and in vitro levels of antigen-specific IL-2 and IFN-gamma. Other investigators have observed either increased or decreased immune function following sympathectomy. Here we present data showing that culture supernatants from spleen cells from the same denervated animals contain increased IL-2 and IFN-gamma levels in response to antigen-specific (keyhole limpet hemocyanin (KLH)) stimulation, but decreased cytokines levels in response to the T cell mitogen Con A compared to vehicle control mice. KLH-induced type 2 cytokines were also increased; no decrease in Con A-stimulated type 2 cytokines was observed. We evaluated whether the antigen presenting cell (APC) or the T cell might be the main target of the observed sympathectomy effects. Cell separation and mixing experiments suggest that the sympathectomy-induced alterations of antigen-specific and mitogen-induced type 1 cytokines are mediated primarily via the T cell. These data directly address some apparent discrepancies in the literature, and highlight potential regulatory sites to be further investigated in pathways of neural-immune communication.

Radioprotective efficacy and acute toxicity of 5-androstenediol after subcutaneous or oral administration in mice

We previously showed that one subcutaneous (sc) injection of 5-androstene-3beta,17beta-diol (AED) stimulated the innate immune system in mice and prevented mortality due to hemopoietic suppression after whole-body ionizing irradiation with gamma rays. In the present study, we tested whether there was any significant toxicity in mice that might hinder development of this steroid for human use. There were no indications of toxicity in chemical analyses of serum after sc doses as high as 4000 mg/kg. At this dose, 2 of 54 mice died when given AED alone. When 4800 mg/kg was given orally, no deaths resulted. The only adverse findings attributed to AED administration were 1) a moderate elevation of granulocytes in abdominal organs and fat after sc injections of 320 mg/kg; and 2) occasional wasting of skin over the injection site in female B6D2F1 but not male C3H/HeN mice. Significant weight loss (6%) was observed after sc injections of 320 mg/kg but not 160 or 80 mg/kg. When male C3H/HeN mice were injected sc with AED at doses of 0-200 mg/kg 24 h before whole body gamma-irradiation (9 Gy), a significant improvement in survival was observed at doses as low as 5 mg/kg. Oral administration of AED produced significant survival enhancement at a dose of 1600 mg/kg. We conclude that the radioprotective efficacy of AED is accompanied by low toxicity.