Prolactin induced reversal of glucocorticoid mediated apoptosis of immature cortical thymocytes is abrogated by induction of tumor

Infection-Associated Thymic Atrophy

The thymus is a vital organ of the immune system that plays an essential role in thymocyte development and maturation. Thymic atrophy occurs with age (physiological thymic atrophy) or as a result of viral, bacterial, parasitic or fungal infection (pathological thymic atrophy). Thymic atrophy directly results in loss of thymocytes and/or destruction of the thymic architecture, and indirectly leads to a decrease in naïve T cells and limited T cell receptor diversity. Thus, it is important to recognize the causes and mechanisms that induce thymic atrophy. In this review, we highlight current progress in infection-associated pathogenic thymic atrophy and discuss its possible mechanisms. In addition, we discuss whether extracellular vesicles/exosomes could be potential carriers of pathogenic substances to the thymus, and potential drugs for the treatment of thymic atrophy. Having acknowledged that most current research is limited to serological aspects, we look forward to the possibility of extending future work regarding the impact of neural modulation on thymic atrophy.

Do Prolactin and its Receptor Play a Role in Alopecia Areata?

Context:

Studying the link between prolactin and autoimmunity has gained much ground over the past years. Its role played in alopecia areata (AA) is not clear yet, as previous reports yielded controversial results.

Aims:

This study aimed to measure the serum level of prolactin and to detect the expression of its receptor in AA, in an attempt to highlight its possible role in the pathogenesis of this disease.

Subjects and Methods:

A case-control study of 30 AA patients and 20 controls from outpatient clinic were undertaken. Every patient was subjected to history taking and clinical examination to determine the severity of alopecia tool (SALT) score. Blood samples were taken from patients and controls to determine the serum prolactin level. Scalp biopsies were obtained from the lesional skin of patients and normal skin of controls for assessment of the prolactin receptor.

Statistical Analysis:

Depending upon the type of data, t-test, analysis of variance test, Chi-square, receiver operator characteristic curve were undertaken.

Results:

On comparing the serum prolactin level between patients and controls, no significant difference was found, while the mean tissue level of prolactin receptor was significantly higher in patients than in controls. In patients, a significant positive correlation was found between the prolactin receptor and the SALT score.

Conclusions:

Prolactin plays a role in AA, and this role is probably through the prolactin receptors rather than the serum prolactin level.

Serum prolactin levels in psoriasis and its association with disease activity: a case-control study

Background:

Psoriasis is a T-cell-mediated autoimmune chronic skin disorder in which an environmental factor, perhaps a viral antigen, induces T cells to produce cytokines. These cytokines stimulate keratinocyte proliferation and production of antigenic adhesion molecules in the dermal blood vessels. Several mediators and hormones have been implicated in keratinocyte hyperproliferation and among these hormones, prolactin (PRL) has been found to have an effect on epithelial cells, lymphocytes and keratinocytes, thus an effect on the etiopathogenesis of psoriasis.

Aim:

The present study was designed to compare serum PRL levels in psoriatic patients with a control group.

Settings and Design:

This study was a hospital-based case control study, conducted in the department of Dermatology, STD and Leprosy, SMHS Hospital (Associated teaching hospital of Government Medical College Srinagar) over a period of 1 year, from September 2012 to 2013.

Materials and Methods:

The present study included 60 patients of psoriasis (42 males and 18 females) and 60 controls matched for age and sex. Serum PRL levels of patients and controls were measured by ECLIA and inferences were drawn.

Statistical Analysis Used:

Statistical significance of the results was carried out by the Chi-square test and the independent samples t-test. Statistical significance was determined at a level of P < 0.05.

Results:

Serum PRL levels were significantly increased in patients as compared to the control group (P value: 0.002). There was a positive correlation between pretreatment serum PRL levels and PASI score (r value: 0.379; P value: 0.003). An insignificant association was found between the pretreatment PRL level and serum PRL level after treatment (P value: 0.22). Also, a negative correlation between the duration of psoriasis and serum PRL was seen (r value: -0.008; P value: 0.954).

Conclusion:

PRL may have a role to play in the etiopathogenesis of psoriasis. However, further studies with large sample size should be carried out so as to validate this hypothesis.

Association of increased circulating catecholamine and glucocorticoid levels with risk of psychological problems in oral neoplasm patients

Background

Noradrenergic pathways and glucocorticoid-mediated signal pathways have been implicated in the growth and progression of oral cancer. Patients with oral neoplasms can have high psychological distress levels, but the effects of stress-related hormones on oral neoplasm growth are unknown.

Methods

We have investigated the relationships between pre-surgical measurements of psychological problems with Symptom Checklist-90-revised Inventory (SCL90-R), tumor histology, circulating blood catecholamine and glucocorticoid levels among 75 oral neoplasm patients, including 40 oral cancer patients and 35 benign oral tumor patients.

Results

The results showed that most dimension scores of SCL90-R did not show a significant difference between the two groups except depression (p = 0.0201) and obsessive-compulsion (p = 0.0093), with the scores for these symptoms being higher among oral cancer group versus the benign oral tumor group. The differences of total score, average score and other monomial factor scores were not statistically significant. The mean concentrations of catecholamine and glucocorticoid in peripheral blood of the oral cancer group were higher than those in benign oral tumor group (p<0.01). We also examined whether associations observed between biobehavioral measures and circulating blood catecholamine and glucocorticoid levels extended to other compartments in the oral cancer group.

Conclusions

These findings suggest that stress hormones may affect oral cancer behavior by influencing the tumor micro-environment though the circulating blood.

Trypanosoma cruzi disrupts thymic homeostasis by altering intrathymic and systemic stress-related endocrine circuitries

We have previously shown that experimental infection caused by Trypanosoma cruzi is associated with changes in the hypothalamus-pituitary-adrenal axis. Increased glucocorticoid (GC) levels are believed to be protective against the effects of acute stress during infection but result in depletion of CD4⁺CD8⁺ thymocytes by apoptosis, driving to thymic atrophy. However, very few data are available concerning prolactin (PRL), another stress-related hormone, which seems to be decreased during T. cruzi infection. Considering the immunomodulatory role of PRL upon the effects caused by GC, we investigated if intrathymic cross-talk between GC and PRL receptors (GR and PRLR, respectively) might influence T. cruzi-induced thymic atrophy. Using an acute experimental model, we observed changes in GR/PRLR cross-activation related with the survival of CD4⁺CD8⁺ thymocytes during infection. These alterations were closely related with systemic changes, characterized by a stress hormone imbalance, with progressive GC augmentation simultaneously to PRL reduction. The intrathymic hormone circuitry exhibited an inverse modulation that seemed to counteract the GC-related systemic deleterious effects. During infection, adrenalectomy protected the thymus from the increase in apoptosis ratio without changing PRL levels, whereas an additional inhibition of circulating PRL accelerated the thymic atrophy and led to an increase in corticosterone systemic levels. These results demonstrate that the PRL impairment during infection is not caused by the increase of corticosterone levels, but the opposite seems to occur. Accordingly, metoclopramide (MET)-induced enhancement of PRL secretion protected thymic atrophy in acutely infected animals as well as the abnormal export of immature and potentially autoreactive CD4⁺CD8⁺ thymocytes to the periphery. In conclusion, our findings clearly show that Trypanosoma cruzi subverts mouse thymus homeostasis by altering intrathymic and systemic stress-related endocrine circuitries with major consequences upon the normal process of intrathymic T cell development.

It is currently estimated that 90 million people in America are exposed to T. cruzi infection, the causative agent of Chagas disease. Despite the mortality and morbidity, this infection is yet considered a neglected disease, due to the lack of effective, safe, and affordable pharmaceuticals for controlling it. T. cruzi leads to immunosuppression of the T cell compartment and to chronic cardiac inflammation, which seems to be associated with the disruption of thymic homeostasis. Thymus atrophy, characteristic of acute infection, is mainly associated with the loss of immature CD4⁺CD8⁺ thymocytes, which in turn is associated with increased corticosterone systemic levels, together with their premature export to the periphery as potential autorreactive cells. Although being deleterious to the thymus, GCs are protective during this infection, for avoiding an exacerbated pro-inflammatory response. Here we demonstrate that the increase of GCs in plasma is related to the impairment of PRL systemic levels. The intrathymic hormonal circuitry is also altered during infection and an imbalance of the cross-talk involving GR and PRL is related with CD4⁺CD8⁺ depletion. The partial restoration of PRL levels prevented thymus atrophy of infected mice, thus partially reverting the T. cruzi-induced subversion of the organ, ultimately reestablishing thymus homeostasis.

The effect of dexamethasone on lentiviral vector infection is associated with importin α

Importin α (Imα) plays an important role during the shuttling of the HIV-1 preintegration complex (PIC) from the cytoplasm to the nucleus. Imα may bind to the glucocorticoid receptor (GR), which is localized to nucleus following hormone binding. However, it remains unclear whether the binding of dexamethasone (Dex) to GR affects the Imα redistribution and, thus, alters PIC import. In our study, 293T cells were transfected with the lentiviral vector (LV) carrying the luciferase (Luci) gene following Dex or RU486 pretreatment. The Luci activity (LucA) in the Dex or RU486 group was significantly higher compared to that in the control group (P≤0.01). The effects of Dex and RU486 were inhibited by the Imα inhibitor Bimax1 (P≤0.01), although the inhibitory effect of Bimax1 was alleviated by increasing the Dex dose. Furthermore, it was observed that the LucA in the 30-min Dex treatment group was lower compared to that in the 30-min Dex pretreatment group (P≤0.01). These results suggested that Dex may improve PIC import via increasing the cytoplasmic Imα levels. Kunming mice were transfected in vivo with the LV, either 30 min or 15 h following an intraperitoneal injection of Dex. The LucA in the liver of the 30-min group mice was significantly lower compared to that of the 15-h group mice (P≤0.01), suggesting that the effect of Dex on LV infection depends mainly on the suppression of immune and inflammatory responses in vivo. Taken together, our data indicated that the effect of Dex on LV infection may be associated with Imα, constituting a novel signaling pathway mediating the effects of Dex on HIV-1 infection.

Thymic atrophy in acute experimental Chagas disease is associated with an imbalance of stress hormones

Disorders in the hypothalamic-pituitary-adrenal axis are associated with the pathogenesis of Trypanosoma cruzi infection. During the acute phase of this disease, increased levels of circulating glucocorticoids (GCs) correlate with thymic atrophy. Recently, we demonstrated that this phenomenon is paralleled by a decrease of prolactin (PRL) secretion, another stress hormone that seems to counteract many immunosuppressive effects of GCs. Both GCs and PRL are intrathymically produced and exhibit mutual antagonism through the activation of their respective receptors, GR, and PRLR. Considering that GCs induce apoptosis and inhibit double-positive (DP) thymocyte proliferation and that PRL administration prevents these effects, it seems plausible that a local imbalance of GR-PRLR crosstalk underlies the thymic involution occurring in acute T. cruzi infection. In this respect, preserving PRLR signaling seems to be crucial for protecting DP from GC-induced apoptosis.

Tumor associated release of interleukin-10 alters the prolactin receptor and down-regulates prolactin responsiveness of immature cortical thymocytes

The soluble factors produced either by Ehrlich's ascites carcinoma (EAC) or thymic adherent cells (TAC) of tumor-bearing mice comprising of CD11b(+) and CD11c(+) antigen-presenting cells caused a sharp decrease in prolactin (PRL)-induced ConA-mediated effect on survival of PNA(+) thymocytes. Similar suppression of PRL-induced effect was observed when the cells were cocultured with TAC of EAC-bearing mice. Anti-IL-10 antibody could reverse the PRL inability to induce ConA-mediated effect on PNA(+) thymocyte survival, indicating the presence of IL-10 in EAC culture supernatant (EAC sup) and thymic microenvironment. IL-10 could block PRL-induced proliferation of PNA(+) thymocytes without affecting spontaneous apoptosis. IL-10 altered the expression of the long-form (LF) of PRL-R and reduced the PRL binding of the cells, suggesting down-regulation of the PRL effect on PNA(+) thymocyte by the cytokine. Induction of tumor, which was found to increase the IL-10 secretion by TAC, also modified the PRL-R (LF) to PRL-R (SF). Since PRL plays a role in survival, proliferation and differentiation of lymphoid progenitor cells, the tuning of PRL action by IL-10 may be a possible mechanism of depletion of immature cortical thymocytes and thymic atrophy in tumor-bearing mice.

Influence of Stress and Nutrition on Cattle Immunity

Today, the scientific community readily embraces the fact that stress and nutrition impact every physiologic process in the body. At last, the specific mechanisms by which stress and nutrition affect the immune function are being elucidated. The debate among animal scientists concerning the definition and quantification of stress as it relates to animal productivity and well-being is ongoing. However, an increased appreciation and understanding of the effects of stress on livestock production has emerged throughout the scientific community and with livestock producers. The intent of this article is to provide an overview of the general concepts of stress and immunology, and to review the effects of stress and nutrition on the immune system of cattle.

Prolactin modulates the functions of murine spleen CD11c-positive dendritic cells

Prolactin (PRL), an anterior pituitary polypeptide hormone, has been shown to have a role in the immunomodulation. Some reports have shown the importance of PRL in activating lymphocytes and macrophages. To further investigate the effect of PRL on the immune system in vitro, murine spleen CD11c-positive dendritic cells (SDCs) were treated with various concentrations of PRL for 24 h, then their viability, phenotype, nuclear factor kappa B p65 (NF-kappaBp65), endocytosis, stimulatory capacity, and cytokine expression were analyzed. The results showed that PRL increased the viability and stimulatory capacity of SDCs, up-regulated the expressions of MHC-11 and CD40 while decreased the level of CD54 on SDCs. Furthermore, PRL decreased the level of NF-kappaBp65 and the endocytosis of SDCs. In addition, PRL increased the expressions of IL-6, IL-10, IL-12 and TNF-alpha in SDCs. These data suggested that PRL might regulate the physiological and pathological immune responses by changing the viability, phenotype, NF-kappaBp65, endocytosis, stimulatory capacity, and cytokine expression of SDCs.