Neuroendocrine dopaminergic regulation of prolactin release in systemic lupus erythematosus: a possible role of lymphocyte-derived prolactin

The role of the ovarian cycle and the effects of mitogen-induced cytokines on human prolactin gene expression in peripheral blood mononuclear cells

BACKGROUND

little is known on the influences of normal menstrual cycle on prolactin gene expression in immune cells.

AIM OF THE STUDY

to determine the effects of the ovarian cycle on prolactin and its receptor expression.

METHODS

peripheral blood mononuclear cells (PBMC) were obtained from twenty-six normal menstruating women at different intervals of their menstrual cycle. The PBMC were incubated during 24 h in the presence or absence of Concanavalin-A (Con-A) and the gene expression of PRL, PRLR and cytokines was evaluated by qPCR. Prolactin, IL-2 and cAMP were determined in each culture by specific immunoassays.

RESULTS

neither PRL nor its receptor expression in PBMC changed significantly among groups, including the cytokines (IL-2, IL-10, and IFNG) studied. Similar results, among groups, were obtained, when PRL expression was stimulated by PGE2 or 8-Br-cAMP. Concanavalin A-stimulated PBMC expressed significantly less prolactin and a significant negative correlation between secreted IL-2 and PRL expression was found. The presence of anti-IL-2 antibodies in Con-A stimulated-cultures significantly increased PRL expression when compared to control cells regardless the hormonal status.

CONCLUSIONS

these data suggest that the menstrual cycle does not significantly modulate or influence prolactin and cytokines gene expression in PBMC, and indicate that IL-2 may be involved in the Con-A regulation of PRL expression in immune cells.

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.

Hormones in the immune system and their possible role. A critical review

Immune cells synthesize, store and secrete hormones, which are identical with the hormones of the endocrine glands. These are: the POMC hormones (ACTH, endorphin), the thyroid system hormones (TRH, TSH, T3), growth hormone (GH), prolactin, melatonin, histamine, serotonin, catecholamines, GnRH, LHRH, hCG, renin, VIP, ANG II. This means that the immune cells contain all of the hormones, which were searched at all and they also have receptors for these hormones. From this point of view the immune cells are similar to the unicells (Tetrahymena), so it can be supposed that these cells retained the properties characteristic at a low level of phylogeny while other cells during the evolution accumulated to form endocrine glands. In contrast to the glandular endocrine cells, immune cells are polyproducers and polyreceivers. As they are mobile cells, they are able to transport the stored hormone to different places (packed transport) or attracted by local factors, accumulate in the neighborhood of the target, synthesizing and secreting hormones locally. This is taking place, e.g. in the case of endorphin, where the accumulating immune cells calms pain caused by the inflammation. The targeted packed transport is more economical than the hormone-pouring to the blood circulation of glandular endocrines and the targeting also cares the other receptor-bearing cells timely not needed the effect. Mostly the immune-effects of immune-cell derived hormones were studied (except endorphin), however, it is not exactly cleared, while the system could have scarcely studied important roles in other cases. The evolutionary aspects and the known as well, as possible roles of immune-endocrine system and their hormones are listed and discussed.

Maternal protein restriction during pregnancy and/or lactation negatively affects follicular ovarian development and steroidogenesis in the prepubertal rat offspring

BACKGROUND AND AIMS

Maternal protein restriction during rat pregnancy and lactation is associated with alterations in reproductive function of female offspring including delayed onset of puberty, decreased fertility and premature reproductive aging. These alterations may be related to ovarian prepubertal development, distribution of follicle populations and their steroidogenic capacities. We undertook this study to evaluate the ovarian function of prepubertal female offspring exposed to maternal protein restriction during pregnancy and/or lactation.

METHODS

Adult female Wistar rats were fed a control (C-20% casein diet) or restricted isocaloric diet (R-10% casein) during pregnancy--first letter--and lactation--second letter, to form four groups, CC, RR, CR, RC. Ovaries were collected from 21-day-old female offspring. Preantral and antral follicles were quantified and mRNA expression of key genes involved in follicular development and steroidogenesis (gonadotropin receptors, StAR, P450scc and P450 aromatase) was evaluated. Serum gonadotropin levels were measured.

RESULTS

Significantly decreased numbers of preantral and antral follicles were observed in CR and RC ovaries compared with CC. LH levels were lower and FSH higher in CR pups. mRNA expression of LH receptor (LH-R) was decreased in RR in comparison with the other groups. CR and RC expressed higher StAR, RC increased and RR decreased P450scc, whereas RR and CR decreased aromatase expression in comparison with CC.

CONCLUSIONS

Maternal protein restriction influences prepubertal ovarian follicular number and steroidogenic function in the rat offspring, although RR and CR nutritional schemes have similar outcomes, the mechanisms affecting ovarian function are at different levels of the hypothalamic-pituitary-ovarian axis.

Extrapituitary production of anterior pituitary hormones: an overview

Protein hormones from the anterior pituitary gland have well-established endocrine roles in their peripheral target glands. It is, however, now known that these proteins are also produced within many of their target tissues, in which they act as local autocrine or paracrine factors, with physiological and/or pathophysiological significance. This emerging concept is the focus of this brief review.

Calcitriol stimulates prolactin expression in non-activated human peripheral blood mononuclear cells: breaking paradigms

Calcitriol, the hormonal form of vitamin D(3), exerts immunomodulatory effects through the vitamin D(3) receptor (VDR) and increases prolactin (PRL) expression in the pituitary and decidua. Nevertheless, the effects of calcitriol upon lymphocyte PRL have not been evaluated. Therefore, we investigated calcitriol effects upon PRL in resting and phytohemagglutinin-activated human peripheral blood mononuclear cells (PBMNC) and Jurkat T lymphoma cells. Immunoblots showed constitutive expression of the 50-kDa VDR species in activated PBMNC and Jurkat cells, while a 75-kDa species was recognized in both resting and activated-PBMNC. Only in resting PBMNC calcitriol significantly stimulated PRL expression in a dose-dependent manner. The positive control CYP24A1, a highly VDR-responsive gene, was stimulated by calcitriol, effect that was stronger in resting than in activated-PBMNC (P<0.05), and without effect in Jurkat cells. Calcitriol upregulation of PRL and CYP24A1 was significantly inhibited by the VDR antagonist TEI-9647. EMSA showed that resting PBMNC contain a protein that binds to DR3-type VDRE. Cell activation reduced basal CYP24A1 while induced CYP27B1, VDR and pregnane X receptor (PXR) expression. In summary, calcitriol stimulated PRL and CYP24A1 gene expression in quiescent lymphocytes through a VDR-mediated mechanism. Our results suggest that the 75-kDa VDR species could be participating in calcitriol-mediated effects, and that activation induces factors such as PXR that restrain VDR transcriptional processes. This study supports the presence of a functional VDR in quiescent lymphocytes, providing evidence to reevaluate the VDR paradigm that assumes that lymphocytes respond to calcitriol only after activation. Altogether, our results offer new insights into the mechanisms whereby PRL is regulated in immune cells.

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.

Galactorrhea associated with juvenile systemic lupus erythematosus: a review of the role of prolactin

This case report is based on the clinical observation of a patient with juvenile systemic lupus erythematosus (SLE) who developed transient galactorrhea. The subsequent literature review documented an interesting association between prolactin and rheumatic diseases and in particular, hyperprolactinemia and SLE. The discussion that follows the case report explores this relationship and proposes a hypothesis regarding why this patient with juvenile SLE developed galactorrhea.

Immune-neuroendocrine interactions and autoimmune diseases

The relationship between immune-neuroendocrine system is firmly established. The messengers of this connection are hormones, neuropeptides, neurotransmitters and cytokines. The immune-neuroendocrine system have the capacity to synthesize and release these molecules, which, in turn, can stimulate or suppress the activity of immune or neuroendocrine cells by binding to receptors. In fact, hormones, neuropeptides and neurotransmitters participate in innate and adaptive immune response.

Autoimmune rheumatic diseases (ARD) are characterized by aberrant production of pro-inflammatory cytokines, which are a potent activator of the HPA axis. In consequence, high levels of pro-inflammatory hormones such as estrogens and prolactin, and low levels of glucocorticoids, an anti-inflammatory hormone, have been described in the active phase of ARD. In addition, high levels of pro-inflammatory hormones and cytokines have also been frequently detected in organ involvement of patients with ARD, suggesting an abnormal local neuroendocrine immune interaction. There is evidence that hormonal changes may appear before the symptomatic phase of the disease. Therefore, it is possible that a pro-inflammatory hormone favors the rupture of tolerance, which is a key feature of autoimmune diseases. The interactions between the immune-neuroendocrine system have a major impact on our understanding of the pathogenic mechanisms, diagnosis and therapy of ARD.

Delusional parasitosis and the dopamine transporter. A new insight of etiology?

Delusional parasitosis (DP) is a psychotic condition in which a person has the unshakeable and mistaken belief (delusion) and/or aberrant perception (hallucination) of being infested with parasites. The disorder will be usually classified in a primary DP-group without a detectable cause (so-called pure forms), while secondary DP-groups are associated with general organic conditions, psychiatric illnesses and drugs (substance induced). Etiology and pathophysiology of DP remain however unknown. In the present paper we hypothesize for the first time a decreased striatal dopamine transporter (DAT)-functioning (corresponding with an increased extracellular dopamine-level) as etiologic condition for DP (primary and secondary groups). The DAT as key regulator of the dopamine-reuptake in the human brain is well known (regulation of the extracellular dopamine concentration). It is a presynaptic plasma membrane protein highly dense represented in the striatum. The hypothesis of a decreased DAT-functioning as etiologic condition by DP is revealed in case reports which show that DAT-inhibitors, such as cocaine, pemoline, methylphenidate and other amphetamine-derivatives can induce the clinical expression of DP. Several other associated causes of secondary DP-groups (medications, parkinson, chorea huntington, multiple system atrophy, diabetes, cerebrovascular diseases, alcoholism, traumatic brain injury, hyperuricemia, human immunodeficiency virus, iron deficiency, schizophrenia, depression) suggest that the clinical expression of DP may be related to a decreased striatal DAT-functioning (blocking, reduced ligand binding, reduced density, reduced activity). Our examined DP-cases (2-females) show means of magnetic resonance imaging a structurally damaged striatum. Furthermore, we presume that by the primary DP-group, the physiologically age-related decline of the DAT-density is pathologically elevated. Based on this hypothesis we show in the present paper the relation between DP and decreased striatal DAT-functioning, trying to give a new insight into the pathophysiologically mechanism involved. The hypothesis provides supporting evidence that increased levels of extracellular dopamine in the striatum of DP-patients is likely to be the result of decreased DAT-functioning and not increased rates of release. The hypothesis can be investigated simply by dopamine transporter imaging in patients with DP.

Prolactin modulates TRPV1 in female rat trigeminal sensory neurons

Sex dependency in pain perception is well documented and is thought to be attributable to the effect of reproductive hormones on nociceptive processing. In the present study, we evaluated whether estradiol alters gene transcription in the trigeminal ganglia (TG) of ovariectomized rats (OVX). These experiments demonstrated a dramatic (40-fold) upregulation of prolactin (PRL) expression in TG by 17-beta-estradiol (E2). PRL expression was restricted to TG neurons and was highly overlapped with transient potential receptor vanilloid type 1 (TRPV1) (approximately 90%) in TG. Additionally, PRL is released from neurons during stimulation. Both forms of PRL receptors (PRLRs), short and long, were also present in TG neurons. Moreover, expression of the long PRLRs was under control of estradiol. We next evaluated the novel hypothesis that PRL acts as a neuromodulator of sensory neurons. PRL pretreatment significantly enhanced capsaicin-evoked inward currents, calcium influx, and immunoreactive calcitonin gene-related peptide release from cultured TG neurons. This PRL modulation of capsaicin responses was abolished by withdrawal of E2 from TG cultures. Biochemical analysis demonstrated that PRL increased (>50%) phosphorylation levels of TRPV1 in TG. In a behavioral test, PRL pretreatment significantly potentiated capsaicin-evoked nocifensive behavior in female rats at proestrous and in OVX rats after E2 treatment. The in vivo potentiating effect of PRL on capsaicin responses was also dependent on E2. Collectively, these data demonstrate that PRL is a novel modulator of sensory neurons tightly regulated by E2. These findings are consistent with the hypothesis that PRL could contribute to the development of certain pain disorders, possibly including those modulated by estrogen.

Altered Functional Status of the Hypothalamic Dopaminergic Tone in Patients with Chronic Graft-versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation: A Pilot Study

We compared the functional status of the hypothalamic dopaminergic tone in patients given an allogeneic hematopoietic stem cell transplantation (allo-HSCT) with chronic graft-versus-host disease (GVHD) with that observed in patients with allo-HSCT without chronic GVHD and in healthy controls. The effect of acute dopaminergic blockade with intravenous metoclopramide on serum prolactin (PRL) concentrations was evaluated. Twenty volunteers, 20 to 52 years of age, seronegative for both hepatitis C virus and the human immunodeficiency virus, were studied: (1) 10 clinically healthy men (group 1), and (2) 9 patients with leukemia, and 1 patient with refractory aplastic anemia who underwent allo-HSCT, 5 of whom (3 men and 2 women) developed chronic GVHD (group 2), and 5 (3 men and 2 women) who did not develop chronic GVHD (group 3). Serum PRL concentrations were measured both fasting and after intravenous administration of metoclopramide (10-mg bolus). The area under the PRL curve was calculated. Patients in group 2 were older than those in groups 1 and 3 (P<.018), but their body mass index was similar. Fasting serum PRL concentrations were similar among the 3 groups; however, group 2 had higher PRL concentrations throughout the test (P<.001) and a greater area under the PRL curve than groups 1 and 3 (P<.001), without differences between the last 2 groups. The differences remained significant after adjustment for age (P<.01). Our results in a small group of patients with chronic GVHD after allo-HSCT suggest the existence of an increased functional level of their hypothalamic dopamine tone, which would favor a tendency toward a diminished endogenous production, release of pituitary PRL, or both. This could represent an adaptive mechanism aiming to maintain circulating PRL concentrations within a physiological range.

Correlation between serum prolactin levels and lupus activity

To assess the frequency of hyperprolactinemia and evaluate its possible clinical significance in patients with systemic lupus erythematosus (SLE). We determined serum prolactin (PRL) levels in 30 patients with SLE by a radioimmunometric assay. For each patient, the clinical disease activity was assessed using the Systemic Lupus Activity Measure. Antinuclear antibodies were determined by standard techniques. Correlation between PRL concentrations and SLE clinical and serological activity were evaluated. Elevated serum concentrations of PRL (>25 ng/ml in female and >16 ng/ml in male) were found in 10 of the 30 (33.3%) patients (7-85 ng/ml, mean 33.8, SD 19.8). A significant correlation was found between the PRL levels and the clinical disease activity of SLE (P < 0.001, r = 0.675). In addition, hyperprolactinemia was associated with serological activity. Hyperprolactinemia was frequently detected in patients with SLE. There is a significant correlation between hyperprolactinemia and lupus activity.

First reported pediatric case of systemic lupus erythematosus associated with prolactinoma

There is much interest in the possibility that prolactin influences disease activity in systemic lupus erythematosus (SLE). We present the first reported pediatric case of prolactinoma associated with SLE, in a 13-year-old white female. The diagnosis of SLE was based on the presence of arthritis, antinuclear antibodies, and double-stranded DNA, and a chest radiograph showing pleural fluid. The diagnosis of pituitary prolactinoma was based on the histologic features and the presence of amenorrhea, galactorrhea, and an elevated serum prolactin level. Neurosurgical resection and medical therapy with bromocriptine mesylate were independently associated with decreased prolactin levels, loss of arthritis, and reduced levels of inflammatory mediators.