Prolactin, dendritic cells, and systemic lupus erythematosus

The immune microenviroment in somatotropinomas: from biology to personalized and target therapy

Pituitary tumors are rare neoplasms, with a heterogeneous biological and clinical behavior, due to their clinical course, local invasive growth, resistance to conventional therapies and the risk of disease progression. Recent studies on tumor microenvironment (TME) provided new knowledge on the biology of these neoplasia, that may explain the different phenotypes of these tumors and suggest new biomarkers able to predict the prognosis and the treatment outcome. The identification of molecular markers that act as targets for biological therapies may open new perspectives in the medical treatments of aggressive pituitary tumors.In this paper, we will review data of TME and target therapies in somatotropinomas.

Prolactin and autoimmunity: The hormone as an inflammatory cytokine

Nowadays, more than 80 autoimmune disorders are recognized, in which an aberrant immune response against different organs and tissues plays a crucial role. Hormonal homeostasis has great influence in achieving competent and healthy immune system function. Prolactin has a bioactive function acting as a hormone and a cytokine. It influences the immune system modulation, mainly inhibiting the negative selection of autoreactive B lymphocytes. Hyperprolactinemia has been detected in many patients with different autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, Sjögren syndrome, multiple sclerosis, autoimmune thyroid disease, systemic sclerosis, among others, and its believed to play a crucial role in disease pathogenesis. A direct correlation between prolactin levels and disease activity was not clear. Genetic factors may have a role in humans as in animal models. Dopamine agonists have proven to offer clinical benefits among autoimmune patients and represent a promising therapy to be explored. In this review, the authors attempt to provide a critical overview on the role of prolactin in the immune system, exploring its contribution to the development of autoimmune diseases.

Serum prolactin level in chronic urticaria: Is bromocriptine inducing remission in chronic urticaria?

BACKGROUND

Chronic urticaria (CU) is a disturbing disease with a negative impact on quality of life. Despite of several clinical studies on CU patients, its pathogenesis is poorly understood. Prolactin (PRL) is peptide hormone has immunomodulatory effects in some immune inflammatory skin diseases.

AIM

To elucidate any possible relationship between the immunomodulatory effects of PRL and CU. Besides, the study aims to investigate the crucial role of antiprolactin drugs in the management of CU patients.

PATIENTS AND METHODS

The serum PRL level of 40 female patients with CU was measured using the electrochemiluminescence immunoassay. The activity of CU was assessed by European Academy of Allergology and Clinical Immunology; Global Allergy and Asthma European Network; European Dermatology Forum (EAACI/GA2LEN/EDF) activity score. Patients with high PRL level had been given anti prolactin therapy to normalize their PRL levels. Then, the disease activity was reassessed in these patients.

RESULTS

The serum PRL level was high in 8 of 40 (20%) patients (43.18 ± 12.81). Half of patients with high PRL level had remission after treatment of hyperprolactinemia (p = .001).

CONCLUSIONS

Serum PRL levels could not be considered as a marker of the disease activity in CU patients.

Prolactin and Autoimmunity

The great asymmetry of autoimmune diseases between genders represents one of the most enigmatic observations among the mosaic of autoimmunity. Sex hormones are believed to play a crucial role on this dimorphism. The higher prevalence of autoimmunity among women at childbearing ages, disease onset/relapses during pregnancy, and post-partum are some of the arguments that support this hypothesis. Certainly, motherhood represents one of the most remarkable challenges for the immune system, which not only has to allow for the conceptus, but also has to deal with complex endocrine alterations. Hormonal homeostasis is known to exert a crucial influence in achieving a competent and healthy immune system. Prolactin (PRL) has a bioactive function acting as a hormone and a cytokine. It interferes with immune system modulation, mainly inhibiting the negative selection of autoreactive B lymphocytes. Likewise, hyperprolactinemia has been described in relation to the pathogenesis and activity of several autoimmune disorders. Dopamine is an effective inhibitor of PRL secretion due to either a direct influence on the hypophysis or stimulation of postsynaptic dopamine receptors in the hypothalamus, arousing the release of the PRL inhibitory factor. Hence, dopamine agonists have proven to offer clinical benefits among autoimmune patients and represent a promising therapy to be explored. In this review, we attempt to provide a critical overview of the link between PRL, autoimmune diseases, and motherhood.

Breastfeeding and autoimmunity: Programing health from the beginning

Breast milk is not only a completely adapted nutrition source for the newborn but also an impressive array of immune-active molecules that afford protection against infections and shape mucosal immune responses. Decisive imprinting events might be modulated during the first months of life with potential health long-term effects, enhancing the importance of breastfeeding as a major influence on the immune system correct development and modifying disease susceptibility. The aim of this review was to clarify the link between breastfeeding and autoimmune diseases, inquiring the related mechanisms, based on data available in the literature. Being breastfed was associated with a lower incidence of diabetes, celiac disease, multiple sclerosis and asthma, explained by the protection against early infections, anti-inflammatory properties, antigen-specific tolerance induction, and regulation of infant's microbiome. The protective role of human milk in idiopathic juvenile arthritis, rheumatoid arthritis, and inflammatory bowel diseases remains controversial. On the other hand, the breastfeeding mother faces a health-challenging period in life. High levels of prolactin may lead either to the development of autoimmune diseases in susceptible mothers or exacerbations of current immune-mediated disorders. These features raise the question if mothers with autoimmune diseases, mainly systemic lupus erythematosus, should avoid breastfeeding.

Increased plasma/serum levels of prolactin in systemic lupus erythematosus: a systematic review and meta-analysis

BACKGROUND

Prolactin (PRL), a polypeptide hormone produced by the pituitary gland, is involved in the regulation of humoral and cell mediated immune responses. PRL levels have been investigated in several autoimmune diseases including systemic lupus erythematosus (SLE), however, yielded different and inconsistent results. This study aims to derive a more precise evaluation on plasma/serum PRL levels in SLE patients, as well as the potential influential factors.

METHODS

Studies published from 1 January 1987 to 31 December 2015 in English, which comparing plasma/serum PRL levels between SLE group and control group were searched in PubMed, EMBASE and The Cochrane Library databases. Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by fixed-effects or random-effect model analysis. Heterogeneity test was performed by the Q statistic and quantified using I², publication bias was evaluated using a funnel plot and Egger's linear regression test.

RESULTS

Five-hundred and forty-seven articles were obtained after searching databases, and 12 studies with 429 SLE patients and 326 controls were finally included. Meta-analysis revealed that, compared with the control group, the SLE group had significantly higher plasma/serum PRL levels (P < 0.001), with the SMD of 1.26 and 95%CI (0.70，1.82). Subgroup analyses showed that SLE patients from Asia and Europe had higher plasma/serum PRL levels. However, no significant change in plasma/serum PRL levels was observed in SLE patients from America (P > 0.05).

CONCLUSIONS

Overall, our study suggests that SLE patients have higher plasma/serum PRL level, but with a regional difference.

Increased serum level of prolactin is related to autoantibody production in systemic lupus erythematosus

OBJECTIVE

Prolactin (PRL) is known to aid effector B cells and augment autoimmunity, but the role of PRL in systemic lupus erythematosus (SLE) is not fully elucidated. The aim of this study was to determine the correlation between the serum levels of PRL and autoantibody production in SLE.

METHODS

Blood levels of PRL, anti-double-stranded DNA (ds-DNA) antibody, immunoglobulin M (IgM) and immunoglobulin G (IgG) were determined in samples from 30 adult patients with SLE and 25 healthy controls. The relationships between the serum level of PRL and SLE disease activity, as well as the titres of the ds-DNA antibody, IgM and IgG were determined.

RESULTS

The serum level of PRL was higher in the SLE patients than in the healthy controls. PRL concentration increased during SLE flares-ups and decreased following disease remission. There was a positive correlation between the PRL concentration and serum levels of IgM, IgG and ds-DNA antibody titre.

CONCLUSION

These data suggest that the serum level of PRL was closely related to the antibody production and disease activity of SLE patients. PRL concentration was dramatically reduced upon the remission of disease activity, indicating that PRL levels might be a promising predictor of SLE disease severity.

Concomitant myasthenia gravis and macroprolactinoma: the immunomodulatory role of prolactin and its potential therapeutic use

Considerable evidence attests to the role of the hypothalamic-pituitary endocrine axis (HPA) in the maintenance of normal immunocompetence. The immune and neuroendocrine systems are integrally linked and coordinated with bidirectional communication maintaining immune balance. Any disturbance of the normal function of the HPA may significantly alter native immunocompetence and therefore be associated with the development of disorders which have a clearly established autoimmune basis. Molecular and functional evidence shows prolactin, produced by the anterior pituitary, to be a cytokine, exerting its effect via both paracrine and endocrine mechanisms [1]. Its involvement in the activation of multiple immune responses may adversely upregulate certain autoimmune diseases. Myasthenia gravis (MG) has long been recognized as an autoimmune disorder. In this mini review, we present the coterminous presentation of MG and prolactin-secreting macroadenoma. We review published cases in the world literature, discuss pathological mechanism, and consider future targeted therapies.

Serum IL-10 from systemic lupus erythematosus patients suppresses the differentiation and function of monocyte-derived dendritic cells

The role played by cytokines, other than interferon (IFN)-α, in the differentiation and function of dendritic cells (DCs) in systemic lupus erythematosus (SLE), remains unclear. Serum interleukin-10 (IL-10) levels are generally elevated in SLE patients, which might modulate the differentiation of DCs. In this study, DCs were induced from monocytes either by transendothelial trafficking or by culture with granulocyte-macrophage colony-stimulating factor (GM-CSF) + IL-4 + tumor necrosis factor (TNF)-α. Both systems were used to investigate the effects of elevated serum IL-10 level on DC differentiation in SLE patients. The results showed that monocyte-derived DCs induced by either SLE serum or exogenous IL-10 reduced the expression of human leukocyte antigen (HLA)-DR and CD80, decreased IL-12p40 level, and increased IL-10 level, and exhibited an impaired capacity to stimulate allogenic T-cell proliferation. These results indicate that serum IL-10 may be involved in the pathogenesis of SLE by modulating the differentiation and function of DCs.

Increased levels of prolactin receptor expression correlate with the early onset of lupus symptoms and increased numbers of transitional-1 B cells after prolactin treatment

Background

Prolactin is secreted from the pituitary gland and other organs, as well as by cells such as lymphocytes. Prolactin has an immunostimulatory effect and is associated with autoimmune diseases that are characterised by abnormal B cell activation, such as systemic lupus erythematosus (SLE). Our aim was to determine if different splenic B cell subsets express the prolactin receptor and if the presence of prolactin influences these B cell subsets and correlates with development of lupus.

Results

Using real-time PCR and flow cytometry, we found that different subsets of immature (transitional) and mature (follicular, marginal zone) B cells express different levels of the prolactin receptor and are differentially affected by hyperprolactinaemia. We found that transitional B cells express the prolactin receptor at higher levels compared to mature B cells in C57BL/6 mice and the lupus-prone MRL/lpr and MRL mouse strains. Transitional-1 (T1) B cells showed a higher level of prolactin receptor expression in both MRL/lpr and MRL mice compared to C57BL/6 mice. Hyperprolactinaemia was induced using metoclopramide, which resulted in the development of early symptoms of SLE. We found that T1 B cells are the main targets of prolactin and that prolactin augments the absolute number of T1 B cells, which reflects the finding that this B cell subpopulation expresses the highest level of the prolactin receptor.

Conclusions

We found that all B cell subsets express the prolactin receptor but that transitional B cells showed the highest prolactin receptor expression levels. Hyperprolactinaemia in mice susceptible to lupus accelerated the disease and increased the absolute numbers of T1 and T3 B cells but not of mature B cells, suggesting a primary effect of prolactin on the early stages of B cell maturation in the spleen and a role of prolactin in B cell differentiation, contributing to SLE onset.

Prolactin down-regulates CD4+CD25hiCD127low/- regulatory T cell function in humans

Among its many functions, prolactin (PRL) participates in immune responses and promotes the activation, differentiation and proliferation of T cells. However, the mechanisms by which PRL regulates regulatory T (T(reg)) cells are still unknown. Our goal was to determine whether PRL plays a role in T(reg) function. We measured the expression of PRL and its receptor in T(reg) and effector T (T(eff)) cells from 15 healthy individuals. We also evaluated the functional activity of T(reg) cells by examining proliferation and cytokine secretion in cells activated with anti-CD3/CD28 in the presence or absence of PRL. We report that T(reg) cells constitutively expressed PRL receptor, whereas T(eff) cells required stimulation with anti-CD3/CD28 to induce PRL receptor expression. Expression of PRL was constitutive in both populations. We found that the addition of PRL inhibited the suppressor effect (proliferation) mediated by T(reg) cells in vitro, reducing suppression from 37.4 to 13% when PRL was added to co-cultures of T(reg) and T(eff) cells (P<0.05). Cultures treated with PRL favoured a Th1 cytokine profile, with increased production of TNF and IFNγ. We report for the first time that PRL receptor expression was constitutive in T(reg) cells but not in T(eff) cells, which require stimulation to induce PRL receptor expression. PRL inhibited the suppressive function of T(reg) cells, apparently through the induced secretion of Th1 cytokines.

Prolactin and autoimmunity

Sex hormones, especially estrogen and prolactin (PRL), have an important role in modulating the immune response. PRL is secreted from the pituitary gland as well as other organs and cells particularly lymphocytes. PRL has an immune stimulatory effect and promotes autoimmunity. PRL interferes specifically with B cell tolerance induction, enhances proliferative response to antigens and mitogens and increases the production of immune globulins, cytokines and autoantibodies. Hyperprolactinemia (HPRL) in women present with clinical manifestations of galactorrhea, primary or secondary amenorrhea, delayed menarche or a change in the menses either in the amount or in the regularity. Furthermore in the last 2 decades multi-organ and organ specific autoimmune diseases like systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjogren's syndrome (SS), Hashimoto's thyroiditis (HT), multiple sclerosis (MS), psoriasis, hepatitis C patients, Behçet's disease, peripartum cardiomyopathy (PPCM) and active celiac disease were discussed to be associated with HPRL. There is data showing correlation between PRL level and diseases activity in few diseases. Genetic factors may have a role in humans as in animal models. The PRL isoforms based on the differences in the amino acid sequence and size of the cytoplasmic domain have an important effect on the bioactivity on prolactin receptors (PRL-Rs).

Prolactin and autoimmunity

The relationship between prolactin and the immune system has been demonstrated in the last two decades, opening new windows in the field of the immunoendocrinology. Prolactin has an important role in the innate and adaptive immune response. Increased prolactin levels have been described in autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, Sjögren syndrome, and systemic sclerosis among others. Hyperprolactinemia is associated with active disease and organ involvement in systemic lupus erythematosus. Therefore, prolactin is an integral member of the immunoneuroendocrinology network and seems to have a role in pathogenesis of autoimmune diseases. Few controlled studies of dopamine agonist treatment in humans with autoimmune disease have been conducted only in systemic lupus erythematosus patients, which support the potential efficacy of such agents even during pregnancy and postpartum. Further studies are necessary to elucidate the mechanisms by which prolactin affects autoimmune disease activity, increase the inflammatory mechanism, and determine the role of anti-prolactinemic drugs to regulate the immune/inflammatory process.

Prolactin and autoimmunity

The relationship between prolactin and the immune system has been demonstrated in the last two decades, opening new windows in the field of the immunoendocrinology. Prolactin has an important role in the innate and adaptive immune response. Increased prolactin levels have been described in autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, Sjögren syndrome, and systemic sclerosis among others. Hyperprolactinemia is associated with active disease and organ involvement in systemic lupus erythematosus. Therefore, prolactin is an integral member of the immunoneuroendocrinology network and seems to have a role in pathogenesis of autoimmune diseases. Few controlled studies of dopamine agonist treatment in humans with autoimmune disease have been conducted only in systemic lupus erythematosus patients, which support the potential efficacy of such agents even during pregnancy and postpartum. Further studies are necessary to elucidate the mechanisms by which prolactin affects autoimmune disease activity, increase the inflammatory mechanism, and determine the role of anti-prolactinemic drugs to regulate the immune/inflammatory process.

Prolactin, systemic lupus erythematosus, and autoreactive B cells: lessons learnt from murine models

The predominant prevalence of autoimmune diseases in women of reproductive age has led to the investigation of the effects of sex hormones on immune regulation and in autoimmune diseases, in particular the prototypic systemic autoimmune disease lupus. The female hormone prolactin has receptors beyond the reproductive axis including immune cells, and it is thought to promote autoimmunity in human and murine lupus. Induced hyperprolactinemia in experimental lupus models, regardless of gender, exacerbates disease activity and leads to premature death. Prolactin treatment in mice that are not prone to develop lupus leads to the development of a lupus-like phenotype. Persistent mild-moderate hyperprolactinemia alters the selection of the naïve B cell repertoire. Recent studies demonstrate that prolactin impairs all three mechanisms of B cell tolerance induction (negative selection, receptor editing, and anergy) and thereby contributes to the pathogenesis of autoimmunity. The effects of prolactin are genetically determined as shown by the differential response to the hormone in the different mice strains. Bromocriptine, a drug that inhibits prolactin secretion, abrogates some of the immune effects of this hormone. Further research is required to elucidate molecular mechanisms involved in immune effects of prolactin and to develop novel targeted treatments for SLE patients with prolactin-responsive disease.

Dexamethasone inhibits immunoreactivity of dendritic cells in patients with chronic idiopathic thrombocytopenic purpura

The objective of this study was to investigate the possible effects of dexamethasone treatment on the immunoreactivity of dendritic cells in patients with chronic idiopathic thrombocytopenic purpura (ITP). Thirty-six newly diagnosed patients with chronic ITP received an oral high dose of dexamethasone (HD-DXM) at single daily doses of 40 mg for 4 consecutive days. The CD14 leukocytes isolated from the 21 remission patients and 10 normal controls were stimulated by recombinant human granulocyte-macrophage colony-stimulating factor and rhIL-4. The surface antigens of the dendritic cells were analyzed by flow cytometry and the level of IL-12p70 in the supernatant was detected by enzyme-linked immunosorbent assay. In ITP patients, the expression of both CD80 and CD86 in dendritic cells were significantly increased compared with those of the normal controls (51.60 +/- 13.47 vs. 36.03 +/- 15.43%, 61.50 +/- 15.93 vs. 40.28 +/- 11.49%, respectively; P < 0.05). After HD-DXM treatment, both CD80 and CD86 were decreased to levels comparable to normal controls (P > 0.05). The level of IL-12p70 in ITP patients was significantly higher (67.52 +/- 14.43 pg/ml) than the controls (39.78 +/- 10.03 pg/ml, P < 0.05). After treatment, IL-12p70 was reduced to 43.90 +/- 8.49 pg/ml with no significant differences between ITP group and control (P > 0.05). Dendritic cells and their cytokine secretion play important roles in ITP, and DXM may achieve its therapeutic effect on ITP by inhibiting immune responses through suppressing the function of dendritic cells.

Autoimmunity in hepatitis C virus carriers: involvement of ferritin and prolactin

BACKGROUND

Ferritin and prolactin have been associated with active autoimmune diseases as systemic lupus erythematosus and autoantibody production, but have been little studied in viral infections that present autoimmunity.

OBJECTIVE

To investigate the association of these two autoimmune mediators with the presence of cryoglobulinaemia and non-organ-specific autoantibodies (RF, SMA, β2GPI IgA antibody and ANA) in Brazilian individuals chronically infected with hepatitis C virus (HCV).

METHODS

Ninety-nine patients were evaluated. Ferritin and prolactin levels were determined by chemiluminescent immunoassays.

RESULTS

Hyperprolactinemia was found in 10 (six men and four women) out of 99 (10.1%) hepatitis C patients. Thirty-eight out of 99 (38.4%) HCV carriers had hyperferritinemia (median level 385ng/mL). Neither hyperprolactinemia nor hyperferritinemia was associated with cryoglobulinaemia or non-organ-specific autoantibodies (p>.05). There was an association between hyperprolactinemia and the infection with HCV genotype 3 (p<.01). Ferritin and ALT levels were correlated (p<.05).

CONCLUSION

Our results suggest that neither prolactin nor ferritin is involved with the extra-hepatic manifestation of autoimmunity observed in HCV carriers.

Tolerogenic dendritic cells in autoimmune diseases: crucial players in induction and prevention of autoimmunity

The immune system has evolved to coordinate responses against numerous invading pathogens and simultaneously remain silent facing self-antigens and those derived from commensal organisms. But, if both processes are not maintained in strict balance, a potential threat can emerge due to the risk of chronic inflammation and/or autoimmunity development. Therefore, there is a negative immune regulation where tolerogenic dendritic cells (tDCs) participate actively. Under steady-state conditions, tDC are notably involved in the elimination of autoreactive T cells at the thymus, and in the control of T cells specific to self and harmless antigens in the periphery. But in the presence of foreign antigens in an inflammatory milieu, dendritic cells (DCs) mature and induce T cells activation and their migration to B cell areas to assist in antibody production. Additionally, there are other factors such as infections, anti tumoral immune responses, trauma-mediated disruption, etc. that may induce alterations in the balance between tolerogenic and immunogenic functions of DCs and instigate the development of autoimmune diseases (ADs). Therefore, in recent years, DCs have emerged as therapeutic targets to control of ADs. Diverse strategies in vitro and/or in animal models of ADs have explored the tolerogenic functions of DCs and demonstrated their feasibility to prevent or control an autoimmune process, but still leaving a void in their application in clinical assays. The purpose of this paper is to give a general overview of the current literature on the significance of tDCs in tolerance maintenance to self and innocuous antigens, the most relevant alterations involved in the pathophysiology of ADs, the cellular and molecular mechanisms involved in their tolerogenic function and the current strategies used to exploit their tolerogenic potential.

Dendritic cell function in lupus: Independent contributors or victims of aberrant immune regulation

Dendritic cells (DCs) represent an important component of the immune system connecting the innate and adaptive immune responses. They are able to trigger strong immunity as well as tolerance against certain antigens, and therefore it is obvious that they have a central role in the expression of immunological diseases. However, because DCs are sparse, heterogeneous and plastic, their exact role in complex autoimmune diseases, such as systemic lupus erythematosus (SLE) remains not well defined. In this review, we make an attempt to summarize critically recent knowledge on the role of conventional DCs in the expression of autoimmunity and pathology in SLE.

Risk of autoimmune disease: challenges for immunotoxicity testing

Autoimmunity represents a potentially diverse and complex category among the range of adverse outcomes for detection with immunotoxicity testing. For this reason, the risk of autoimmune disease is discussed in this overview chapter with additional mention among the later specific protocol chapters. Improvements in clinical diagnostic capabilities and disease recognition have led to a more accurate picture of the extent of autoimmune diseases across different human populations. While the risk of any single autoimmune disease remains modest when compared with that of lung or heart disease, the cumulative prevalence of autoimmune diseases is both significant and increasing. Autoimmune diseases are usually viewed in the context of the damaged tissue or organ (e.g., as a thyroid, gastrointestinal, cardiovascular or neurological disease). But improved recognition that underlying immune dysfunction can connect the risks for these as well as other diseases is critical for optimizing risk assessment. Since autoimmune diseases are chronic in nature with many first appearing in children or in young adults, these diseases exert a serious impact on both health care costs and quality of life. This chapter provides a discussion of the issues that should be considered with immunotoxicity testing for risk of autoimmunity.