Roles of prolactin and gonadotropin-releasing hormone in rheumatic diseases

Unraveling the hormonal approaches for the treatment of rheumatoid arthritis and its complementary interventions

Rheumatoid Arthritis (RA) is an autoimmune, chronic, systemic inflammatory disease that causes redness, swelling, stiffness, and joint pain. It is a long-lasting disease that can have a widespread impact on the body, often affecting the hands, feet, and wrists. The immune cells, such as dendritic cells, T cells, B cells, macrophages, and neutrophils, play a significant role in bone degradation and inflammation. Several cytokines, including TNF-α and IL-17A, play a significant role in causing bone erosion, cartilage deterioration, and joint inflammation. Progesterone and estrogen have a crucial impact on the pathophysiology of RA, influencing the immune system. Research has demonstrated that hormone replacement therapy (HRT) can effectively reduce inflammation, improve disease activity, enhance joint health, alleviate pain, and promote bone strength. Treatments such as tamoxifen and raloxifene, known as selective estrogen receptor modulators (SERMs), are effective against chronic inflammatory illnesses like RA. The treatment with Gonadotropin-releasing hormone (GnRH) has an impact on the hypothalamic-pituitary-gonadal axis, which in turn affects the activity of RA illness. These alternative treatments hold promise in enhancing well-being and alleviating joint pain for individuals with RA.

Circulating prolactin level in Juvenile Systemic Lupus Erythematosus and its correlation with disease activity: a case control study

BACKGROUND

The linkage between prolactin (PRL) and systemic lupus erythematosus (SLE) is still vague. Determination of serum levels of prolactin to reveal its role in patients with SLE is the aim of the study.

METHODS

This is a case-control study performed on 40 children with SLE and 40 age- and sex-matched controls. Cases were further subdivided according to disease activity into mild, moderate, and severe groups using the SLEDAI (Systemic Lupus Erythematosus Disease Activity Index) score. Serum prolactin levels were assayed by ELISA (enzyme-linked immunosorbent assay).

RESULTS

prolactin level was significantly higher in SLE patients (17.3 ± 6.6 µg/L) than in controls (13.5 ± 5.3 µg/L) (P value = 0.005). Although the prolactin level was highest in severe cases (19.3 ± 7.7 µg/L), followed by moderate cases (17.0 ± 5.3 µg/L), and lowest in mild cases (14.0 ± 6.2 µg/L), the variance between the 3 groups was not statistically significant (P value = 0.212). A significant positive correlation between prolactin level and SLEDAI score was detected (r = 0.368) (P value = 0.019). Hyperprolactinemia was found in 8 patients (20%) but not in controls; 4 out of 8 patients with hyperprolactinemia (50%) showed neurological manifestations compared to only 3 out of 32 patients with a normal prolactin level (9.4%) (P value = 0.007).

CONCLUSION

A relationship between serum prolactin levels and juvenile SLE disease was detected. Neurological manifestations were more prevalent among SLE patients with hyperprolactinemia.

Dopaminergic neuronal death in the substantia nigra associates with change in serum levels of TNF-α and IL-1β; evidence from early experimental model of Parkinson's disease

PURPOSE

Studies have shown that inflammation plays a key role in etiology of Parkinson's disease (PD). However, human studies which have evaluated association between PD and serum levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) have reported conflicting results. In this study, serum and striatum levels of these cytokines were evaluated in 6-hydroxydopamine (6-OHDA) animal model of PD.

METHOD

The neurotoxin of 6-OHDA was injected into medial forebrain bundle of right hemisphere and behavioral tests were carried out to eight weeks thereafter to evaluate severity of PD and its progress. Blood was collected before the toxin and in second and eight weeks after that. Survival of dopaminergic (DAergic) neurons in substantia nigra was assessed by immunohistochemistry. TNF-α and IL-1β levels were determined using ELISA kits.

RESULT

Severity of behavioral symptoms was gradually increased in 6-OHDA-treated rats. They showed a decrease in serum TNF-α level in the eight week and increase in IL-1β both in the second and eight weeks. They were divided into two subgroups, symptomatic and asymptomatic with severe and moderate degrees in DAergic neuronal death. Significant decrease in serum TNF-α was only observed in the symptomatic subgroup but IL-1β increased in both subgroups. Also, striatal levels of both cytokines were higher in the lesioned hemisphere.

CONCLUSION

Increase in serum IL-1β level can reflect moderate degree of lesion in substantia nigra and thereby is used for prognosis of PD before its clinical symptoms are appeared. On the other hand, an increase in serum TNF-α is appeared in advanced stage of PD.

Updated advances of linking psychosocial factors and sex hormones with systemic lupus erythematosus susceptibility and development

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that primarily affects women, especially those of reproductive age. Genetics, environment, and gene-environment interactions play key roles in the development of SLE. Despite the numerous susceptibility genes of SLE identified to date, gene therapy is far from a clinical reality. Thus, more attention should be paid to the risk factors and underlying mechanisms of SLE. Currently, it is reported that psychosocial factors and sex hormones play vital roles in patients with SLE, which still need further investigated. The purpose of this review is to update the roles and mechanisms of psychosocial factors and sex hormones in the susceptibility and development of SLE. Based on review articles and reports in reputable peer-reviewed journals and government websites, this paper summarized psychosocial factors (e.g., alexithymia, depression, anxiety, negative emotions, and perceived stress) and sex hormones (e.g., estrogens, progesterone, androgens, and prolactin) involved in SLE. We further explore the mechanisms linking these factors with SLE susceptibility and development, which can guide the establishment of practical measures to benefit SLE patients and offer new ideas for therapeutic strategies.

Serum Prolactin Levels and Behçet Disease

PURPOSE

To evaluate serum prolactin levels in Behçet disease (BD) and correlate with phenotypic expression of the disease.

METHODS

This was a prospective, nonrandomized comparative trial. Twenty-two patients fulfilling BD Research Committee criteria and 21 healthy control subjects were included. Patients were classified in complete-type or incomplete-type BD subgroups according to clinical characteristics such as recurrent oral ulcers, genital ulcers, skin lesions, and ocular disease. Age, sex, HLA phenotyping, and therapy were recorded for comparative analysis between groups. Serum prolactin levels were determined by electrochemiluminescence immunoassay on a Modular Analytics E170 analyzer.

RESULTS

Prolactinemia was significantly higher (mean=19.34 ng/mL) in BD patients vs controls (mean=9.83 ng/mL) (p=0.009). This value was also statistically higher in complete-type BD sub-group vs controls (p=0.02). Younger patients (<30 y) required corticosteroids plus immunosuppressives more often (75%), suggesting an association between age and disease severity, al-though not statistically significant.

CONCLUSIONS

Results suggest the role of prolactin in BD pathogenesis and its association with disease expression, especially in complete-type BD.

Clinical spectrum of males with primary antiphospholipid syndrome and systemic lupus erythematosus: a comparative study of 73 patients

The objective of this study was to compare the clinical findings, laboratory data, functional outcome and chronic damage in male patients with primary antiphospholipid syndrome (PAPS) and systemic lupus erythematosus (SLE). We studied 29 male patients with PAPS and 44 with SLE. Clinical findings, laboratory data, lupus damage index (SLICC/ACR DI), and functional outcome in PAPS, were analysed in each group. The mean age at diagnosiswas 29.8 + 10.4 years in patientswith PAPS and 26 + 10.1 years in SLE patients. The duration of disease was 4.5 + 2.6 versus 5.2 + 3.8 years in patients with PAPS and SLE, respectively(P NS). In patients with PAPS the most frequent clinical manifestations were venous thrombosis, thrombocytopenia, and pulmonary thromboembolism. Patients with SLE had joint, skin and renal involvement more frequently than those with PAPS (P 0.0001). All PAPS patients had anticardiolipin antibodies (aCL), and 14 patients (48%) had lupus anticoagulant (LA). All SLE patients had antinuclear antibodies (ANAs). Anti-dsDNA antibodies were positive in 39% of SLE patients. Five patients died: one with ‘catastrophic’ APS and four with SLE. SLICC/ACR-DI score in SLE patients was 1.9 (SD 1). In PAPS patients poor functional outcome was due to myocardial infarction, pulmonary thromboembolism, stroke and mesenteric thrombosis. Lupus nephritis was the principal organ damage in SLE. In conclusion, in male patients with PAPS and SLE, the clinical manifestations were significantly different. Arterial thrombosis was the major cause of functional impairment and permanent organ damage in PAPS. Renal involvement was the major cause of chronic damage in SLE.

Endocrinologic Manifestations of the Antiphospholipid Syndrome

Our objective was to study the endocrinologic manifestations of the antiphospholipid syndrome (APS). We reviewed the medical literature from 1968 until 2005 using MEDLINE and the key words: APS, anticardiolipin antibodies, lupus anticoagulant, antiphospholipid antibodies, adrenal, thyroid, parathyroid, pituitary, diabetes, ovaries and testes. Adrenal insufficiency is the most common endocrinologic manifestation and can be the presenting symptom of APS. In patients with autoimmune thyroid disease circulating aPL have been detected. However, no clinical manifestations of APS have been described. A few cases of hypopituitarism have been reported, including a case of Sheehan’s syndrome. aPL has been detected in the sera of diabetic patients, probably associated with some macroangiopathic complications. Finally only very few cases of ovarian and testicular involvement have been reported. The adrenals are the most commonly involved glands in the APS. Clinicians should keep a high index of suspicion for adrenal insufficiency in patients with APS.

Analysis of molecular heterogeneity of prolactin in human systemic lupus erythematosus

Hyperprolactinemia without clinical manifestations has been reported in some patients with systemic lupus erythematosus (SLE) because an increase of prolactin (PRL) is produced due to the BIG/BIG molecular variant (molecular variant, 150 kD). This research project aimed to determine levels of PRL: its bioactive form, the little nonglycosylated form (NGPRL) and variants with decreased bioactivity such as the BIG/BIG and the little glycosylated (GPRL), in 29 women and five men with SLE. PRL was assayed by IRMA with a kit from Immunotech Laboratory, the BIG/BIG form by precipitation with polyethyleneglycol 6000, and the NGPRL and GPRL by chromatography on Concanavalin-A-Sepharose. Increased PRL was detected in seven patients (20.6%) of whom three had increased BIG/BIG, six had increased GPRL and only four had increased NGPRL. The three cases with increased BIG/BIG were contrasted by chromatography on Sephadex G-100. No increased PRL or any of the other variants assayed were found in men. Results were similar when PRL was evaluated in the same blood samples by a different IRMA (DPC Laboratory). The etiology of the hyperprolactinemia in some of these patients is unknown, but their lack of symptoms (galactorrhea or amenorrhea) could be due to the BIG/BIG forms and basically to the glycosylation of the hormone. As for the relation between PRL and SLE activity, we found that hyperprolactinemic patients were younger, had a shorter history of illness, although it was not statistically significant, and a higher SLEDAI score. This would indicate a relation between hyperprolactinemia and lupus activity. The patients with increased BIG/BIG form also had a very active illness at the time of the study.

Risk factors of systemic lupus erythematosus flares during pregnancy

This review examines the risk factors for the development of systemic lupus erythematosus (SLE) flares during pregnancy. In preconception, anti-DNA, hypocomplementemia, previous thrombosis, triple antiphospholipid (aPL) antibody positivity, active lupus nephritis and discontinuation of medications such as hydroxychloroquine and azathioprine are factors associated with pregnancy failure. During pregnancy, SLE flares are associated with aPL antibodies, synergic changes of pregnancy on Th1 and TH2 cytokines, other cytokines and chemokines that interact with hormones such as estrogen and prolactin that amplify the inflammatory effect. From the clinical point of view, SLE activity at pregnancy onset, thrombocytopenia, lupus nephritis, arterial hypertension, aPL syndromes, preeclampsia is associated with lupus flares and fetal complications. In puerperium, the risk factors of flares are similar to pregnancy. Hyperactivity of immune system, autoantibodies, hyperprolactinemia, active lupus nephritis, decrease in TH2 cytokines with increase in TH1 cytokines probably participate in SLE flare. The SLE flares during pregnancy make the difference between an uncomplicated pregnancy and pregnancy with maternal and fetal complications. Therefore, the knowledge of risk factors leads the best treatment strategies to reduce flares and fetal complications in SLE patients.

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.

Neuroendocrine immunoregulation in multiple sclerosis

Currently, it is generally accepted that multiple sclerosis (MS) is a complex multifactorial disease involving genetic and environmental factors affecting the autoreactive immune responses that lead to damage of myelin. In this respect, intrinsic or extrinsic factors such as emotional, psychological, traumatic, or inflammatory stress as well as a variety of other lifestyle interventions can influence the neuroendocrine system. On its turn, it has been demonstrated that the neuroendocrine system has immunomodulatory potential. Moreover, the neuroendocrine and immune systems communicate bidirectionally via shared receptors and shared messenger molecules, variously called hormones, neurotransmitters, or cytokines. Discrepancies at any level can therefore lead to changes in susceptibility and to severity of several autoimmune and inflammatory diseases. Here we provide an overview of the complex system of crosstalk between the neuroendocrine and immune system as well as reported dysfunctions involved in the pathogenesis of autoimmunity, including MS. Finally, possible strategies to intervene with the neuroendocrine-immune system for MS patient management will be discussed. Ultimately, a better understanding of the interactions between the neuroendocrine system and the immune system can open up new therapeutic approaches for the treatment of MS as well as other autoimmune diseases.

Role of neuroendocrine and neuroimmune mechanisms in chronic inflammatory rheumatic diseases--the 10-year update

BACKGROUND

Neuroendocrine immunology in musculoskeletal diseases is an emerging scientific field. It deals with the aspects of efferent neuronal and neurohormonal bearing on the peripheral immune and musculoskeletal systems. This review aims to add new information that appeared since 2001.

SEARCH STRATEGY

The following PubMed search sentence was used to find a total of 15,462 references between 2001 and March 2013: "(rheum* OR SLE OR vasculitis) AND (nerve OR hormone OR neurotransmitter OR neuropeptide OR steroid)." In a continuous process, year by year, this search strategy yielded relevant papers that were screened and collected in a database, which build the platform of this review.

RESULTS

The main findings are the anti-inflammatory role of androgens, the loss of androgens (androgen drain), the bimodal role of estrogens (support B cells and inhibit macrophages and T cells), increased conversion of androgens to estrogens in inflammation (androgen drain), disturbances of the gonadal axis, inadequate amount of HPA axis hormones relative to inflammation (disproportion principle), biologics partly improve neuroendocrine axes, anti-corticotropin-releasing hormone therapies improve inflammation (antalarmin), bimodal role of the sympathetic nervous system (proinflammatory early, anti-inflammatory late-most probably due to catecholamine-producing local cells), anti-inflammatory role of alpha melanocyte-stimulating hormone, vasoactive intestinal peptide, and the Vagus nerve via α7 nicotinergic receptors. Circadian rhythms of hypothalamic origin are responsible for circadian rhythms of symptoms (neuroimmune link revealed). Important new pain-sensitizing immunological pathways were found in the last decade.

CONCLUSIONS

The last decade brought much new information that gave birth to the first therapies of chronic inflammatory diseases on the basis of neuroendocrine immune targets. In addition, a new theory linked evolutionary medicine, neuroendocrine regulation of distribution of energy-rich fuels, and volume regulation that can explain many disease sequelae in patients with chronic inflammatory diseases.

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.

Dual effects of hyperprolactinemia on carrageenan-induced inflammatory paw edema in rats

OBJECTIVES

The effects of short-term 5-day and long-term 30-day hyperprolactinemia induced by domperidone (1.7 mg/kg/day, s.c.) or ectopic pituitary graft on the acute inflammatory response induced by carrageenan were evaluated in male rats. Both models of hyperprolactinemia effectively increased serum prolactin (PRL) levels.

METHODS

The volume in milliliters of inflammatory edema was measured by plethysmography 1, 2, 3, 4, 6, 8 and 24 h after carrageenan injection. The areas under the inflammatory time-response curves were compared. Additionally, the effects of hyperprolactinemia on body weight and serum corticosterone levels were evaluated.

RESULTS

In both domperidone-treated and pituitary graft-implanted animals, short-term 5-day hyperprolactinemia increased the inflammatory response, while long-term 30-day hyperprolactinemia had anti-inflammatory effects. Body weight was not affected by either short- or long-term hyperprolactinemia.

CONCLUSION

These results show that PRL has biphasic effects on the carrageenan-induced inflammatory response.

Peripheral cytokines profile in Parkinson's disease

Higher levels of proinflammatory cytokines are found in Parkinson's disease (PD) patient's brains and inflammation is thought to be a major contributor to the neurodegeneration. During the inflammatory process, microglial release of proinflammatory cytokines act on the endothelium of blood-brain barrier (BBB) cells to stimulate upregulation of adhesion molecules. Consequently, this upregulation leads to the recruitment of passing T cells and monocytes, which express the counter receptors, that then go on to release more cytokines [Whitton, P.S., 2007. Inflammation as a causative factor in the aetiology of Parkinson's disease, Br. J. Pharmacol. 50, 963-976; Kortekaas, R., Leenders, K.L., Van Oostrom, J.C., Vaalburg, W., Bart, J., Willemsen, A.T., Hendrikse, N.H., 2005. Blood-brain barrier dysfunction in parkinsonian midbrain in vivo, Ann. Neurol. 57, 176-179]. In addition, a systemic inflammatory response results in the production of cytokines which circulate in the blood and communicate with neurons within the brain. Thus, a central inflammatory reaction interacts with peripheral blood mononuclear cells (PBMCs) modulating immune activity. The present study investigates levels of production and expression of cyto/chemokines by PBMCs in PD patients. Basal and LPS-induced levels of MCP-1, RANTES, MIP-1alpha, IL-8, IFNgamma, IL-1beta and TNFalpha were significantly higher in PD patients than in HC subjects (p<0.001), as determined by RT-PCR and Elisa methods. Cyto/chemokine levels were significantly correlated with UPDRS III and H/Y stage (p<0.001). The Pearson's correlation coefficient (R) was also used to assess the strength of the relationship between NF-kappaBp65 levels and all studied cyto/chemokines and between NF-kappaBp65, UPDRS III and H/Y score in PD patients. The overall results strengthen and extend the knowledge of the peripheral dysregulation in the cytokine network associated with PD.

Bromocriptine during pregnancy in systemic lupus erythematosus: a pilot clinical trial

Bromocriptine (BRC) prevents postpartum flare in lupus patients. However, its potential role in protecting lupus pregnancy from maternal-fetal complications has not been studied. The objective of the study was to explore the role of oral BRC during pregnancy in patients with systemic lupus erythematosus (SLE). Pregnant SLE patients were randomized into two groups: group 1 received BRC 2.5 mg/day and prednisone 10 mg/day; group 2 received prednisone 10 mg/day. These treatments were administered from 25 to 35 weeks of gestation. Prolactin (PRL) levels were determined at 25, 30, and 35 weeks. The SLE Pregnancy Disease Activity Index, maternal-fetal outcome including preterm birth, fetal loss, premature rupture of membrane (PRM), low birth weight, and preeclampsia/eclampsia were evaluated. We studied 20 patients (10 in each group). A significant decrease of PRL levels in group 1 compared to group 2 at week 30 and at week 35 was found. No patients in the BRC group had flares and three from group 2 had SLE activity. None of the patients in group 1 had PRM but three patients in group 2 did. Eighty percent of pregnancies ended in birth at term in group 1 and 50% in group 2. There was no fetal loss in both groups. Mean birth weight was higher in group 1 than in group 2 (P < NS). BRC was well tolerated. This is the first clinical trial of BRC in SLE pregnancy. Our pilot study suggests that BRC may play a role in the prevention of maternal-fetal complications, such as PRM, preterm birth, and active disease.

Prolactin levels are associated with lupus activity, lupus anticoagulant, and poor outcome in pregnancy

High prolactin (PRL) levels seem to be associated with active systemic lupus erythematosus (SLE) during pregnancy. However, the association of activity, lupus anticoagulant (LA), and pregnancy outcome has not been analyzed. The objective of this study was to analyze the association among SLE activity, LA, and maternal-fetal outcome. We studied 15 pregnant SLE patients (ACR criteria), 4 of them with associated antiphospholipid syndrome (APS), and 9 healthy pregnant women. All patients were evaluated monthly with the following determinations: (a) SLE activity using modified-systemic lupus activity measurement (m-SLAM), (b) LA, and (c) PRL serum levels. Healthy controls were evaluated each trimester. Prematurity, fetal loss, low birth weight, and preeclampsia were evaluated. Chi-square test, Fisher's exact test, Student's t-test, Pearson correlation, and ANOVA were performed. The mean age of SLE patients was 30 +/- 4.9 years and 27.1 +/- 3.7 years in controls. High PRL levels were found during the second and third trimester in SLE patients in comparison with controls (186.2 +/- 54.02 ng/mL versus 119.6 +/- 31.1 ng/mL (P < 0.01) and 177.4 +/- 48.6 ng/mL versus 158.3 +/- 31.5 ng/mL. A significant linear correlation between PRL, m-SLAM, and LA in association with poor maternal-fetal outcome was observed. LA and PRL conferred risk for poor pregnancy outcome. Our study indicates for the first time a strong association among PRL, LA, SLE activity, and poor pregnancy outcome. Close rheumatologic and obstetric monitoring is mandatory in SLE pregnancy in order to avoid obstetric complications.

Stress and prolactin effects on bone marrow myeloid cells, serum chemokine and serum glucocorticoid levels in mice

OBJECTIVE

Current evidence supports the conclusion that prolactin (PRL) is not an obligate immunoregulatory hormone and influences the immune system predominantly during stress conditions. In this study, we examined the impact of PRL on the psychogenic stress-induced responses of myeloid cells.

METHODS

Seven-week-old PRL+/- (normal) and PRL-/- (deficient) mice were exposed to a predator for 1 h/day on 3 consecutive days. Another group of PRL-deficient mice received either 1 pituitary graft (hyperprolactinemic) or sham surgery at 5 weeks of age, while PRL-normal mice only received sham surgery. Two weeks later, these mice were also subjected to predator exposure. One day after the last predator exposure session, all mice were killed and the bone marrow and blood harvested.

RESULTS

Significant differences in the myeloid cells between PRL-normal and PRL-deficient mice only occurred in stressed conditions. The median serum corticosterone levels were consistently higher in PRL-deficient mice. The implantation of a pituitary graft lowered the corticosterone levels to those observed in PRL-normal mice. The absolute number of immature neutrophils as well as the numbers of granulocyte macrophage, monocyte/macrophage and granulocyte colonies were significantly higher in the stressed PRL-deficient mice; however, only the increased number of immature neutrophils was reversed by pituitary grafting.

CONCLUSIONS

Our findings support previous observations that PRL influences myeloid cells of the bone marrow most profoundly in stressed conditions. However, the mechanism by which PRL influences bone marrow myeloid cells during stress cannot be explained solely by its effect on serum corticosterone.

Raised prolactin levels in myasthenia gravis: two case reports and a study of two patient populations

OBJECTIVES

To describe two patients with myasthenia gravis (MG) and prolactinoma and analyze the associations between MG and prolactin (PRL) levels.

DESIGN

Two case reports and a case-control study of PRL levels in 192 patients with MG.

PARTICIPANTS

The Immunological Research Laboratory, Center for Molecular Medicine, Department of Medicine and the Department of Neurology, Karolinska Institutet, Stockholm, Sweden; St Petersburg Medical Academy for Postgraduate Studies, and St Petersburg State Medical Pediatric Academy, Russia.

RESULTS

Two women with MG and thymic hyperplasia accompanied by prolactinomas are described. The levels of plasma PRL were raised in 101 women with MG, but not in 91 men. There was an association between high PRL levels and high levels of autoantibodies against the acetylcholine receptor.

CONCLUSIONS

There is an association of MG with raised levels of PRL in women. PRL has stimulating effects on immune activation and the increased levels might thus be implied in the pathophysiology of MG.

Prolactin and Growth Hormone Responses to Hypoglycemia in Patients with Systemic Sclerosis and Psoriatic Arthritis

This study compared prolactin (PRL) and growth hormone (GH) responses to hypoglycemia in premenopausal females with systemic sclerosis (SSc) and psoriatic arthritis (PsA) with those in matched healthy controls. No differences were found in glucose and GH responses to hypoglycemia in both groups of patients compared to controls. SSc patients had lower PRL response (P < 0.05) to hypoglycemia compared to controls. PRL response tended to be lower also in PsA patients, however the difference did not reach level of statistical significance (P = 0.11). The present study showed decreased PRL response to hypoglycemia in premenopausal females with SSc.

Increasing ornithine decarboxylase activity is another way of prolactin preventing methotrexate-induced apoptosis: Crosstalk between ODC and BCL-2

Prolactin has more than 300 separate functions including affecting mammary growth, differentiation, secretion and anti-apoptosis. In the previous studies, prolactin induced Bcl-2 expression to prevent apoptosis and also provoked the activity of ornithine decarboxylase (ODC). Our previous data showed that ODC overexpression upregulates Bcl-2 and prevents tumor necrosis factor alpha (TNF-alpha)- and methotrexate (MTX)-induced apoptosis. Here, we further investigate whether prolactin prevents MTX-induced apoptosis through inducing ODC activity and the relationship between ODC and Bcl-2 upon prolactin stimulation. Prolactin prevented MTX-induced apoptosis in a dose-dependent manner in HL-60 cells. Following prolactin stimulation, ODC enzyme activity also shows an increase in a dose-dependent manner, expressing its maximum level at 3 h, and rapidly declining thereafter. Prolactin-induced ODC activity is completely blocked by a protein kinase C delta (PKCdelta) inhibitor, rottlerin. However, there are no changes in the expressions of ODC mRNA and protein level after prolactin stimulus. It indicates that prolactin may induce ODC activity through the PCKdelta pathway. Besides, Bcl-2 expresses within 1 h of prolactin treatment and this initiating effect of prolactin is not inhibited by alpha-difluoromethylornithine (DFMO). However, Bcl-2 is further enhanced following prolactin stimulation for 4 h and this enhancement is blocked by DFMO. Bcl-2 has no effect on ODC activity and protein levels, but ODC upregulates Bcl-2, which is inhibited by DFMO. Overall, there are two different forms of prolactin effect, it induces Bcl-2 primarily, and following this it stimulates ODC activity. Consequently induced ODC activity further enhances the expression of Bcl-2. The anti-apoptotic effect of prolactin is diminished by DFMO and recovered by putrescine. Obviously, ODC activity is one basis for the anti-apoptotic mechanisms of prolactin. A Bcl-2 inhibitor, HA14-1, together with DFMO, completely blocks the anti-apoptotic effects of prolactin. These results suggest that increasing ODC activity is another way of prolactin preventing MTX-induced apoptosis and that this induction of ODC activity enhances the expression of Bcl-2 strongly enough to bring about the anti-apoptotic function.

The relationship between serum prolactin levels and disease activity in patients with Behcet's disease

The aim of this study was to determine the serum levels of prolactin in patients with Behcet's disease and to evaluate its correlation with disease activity. Serum prolactin levels were measured by a chemiluminescence method in 32 patients with Behcet's disease and compared with 20 age-and sex-matched healthy controls. The patients with Behcet's disease were subdivided into two groups according to disease activity: active (18 patients; 13 men and five women, average age 34.0 +/- 6.5 (28-48) years), and inactive (14 patients; 10 men and four women, average age 32.7 +/- 3.1 (22-49 years). Patients with active Behcet's disease had higher serum prolactin levels than the inactive and control groups. Prolactin levels in patients with active Behcet's disease differed significantly from the healthy control subjects (p < 0.05) only, but not the inactive group. Four patients out of 32 (12.5%) Behcet's disease patients showed mild hyperprolactinemia. All four of these cases were from the active Behcet's disease group. Prolactin levels were correlated with ESR (p < 0.05) and CRP (p < 0.05) levels in the active BD group, but not in the inactive BD and control groups. Our results suggest a possible role for this immunoregulatory hormone in the disease expression and pathogenesis of Behcet's disease.

Spotlight on the role of hormonal factors in the emergence of autoreactive B-lymphocytes

Pathogenic autoimmunity requires a combination of inherited and acquired factors. In as much as hormones influence the sexual dimorphism of the immune system, it is possible that they can initiate or accelerate an autoimmune process, and contribute to gender-biased autoimmune disorders. Not only natural hormones, but also endocrine disruptors, such as environmental estrogens, may act in conjunction with other factors to override immune tolerance to self-antigens. In lupus, murine and human studies demonstrate that female sex hormones are implicated in disease pathogenesis. In the B cell compartment, both prolactin and estrogen are immunomodulators that affect maturation, selection and antibody secretion. Their impact may be based on their capacity to allow autoreactive B cells to escape the normal mechanisms of tolerance and to accumulate in sufficient numbers to cause clinically apparent disease. Both hormones lead to the survival and activation of autoreactive B cells, but they skew B cell maturation towards different directions, with prolactin inducing T cell-dependent autoreactive follicular B cells and estrogen eliciting T cell-independent autoreactive marginal zone B cells. Differential modulation of the cytokine milieu by hormones may also affect the development and activation of specific mature B cell subsets. This novel insight suggests that targeted manipulation of these pathways may represent a promising avenue in the treatment of lupus and other gender-biased autoimmune diseases.

Increased Severity of Murine Lupus in Female Mice Is Due to Enhanced Expansion of Pathogenic T Cells

A strong female predominance is a well-recognized feature of human lupus. The mechanism by which sex influences disease expression and severity is not fully understood. To address this question, we used the parent-into-F(1) (p-->F(1)) model of chronic graft-vs-host disease (cGVHD) in which lupus-like humoral autoimmunity and renal disease are induced in normal F(1) mice. An advantage of this model is that the pathogenic T cells driving disease (donor strain) can be studied separately from nonspecifically activated T cells (host strain). We observed that lupus-like disease using female donor and host mice (f-->F cGVHD) is characterized by more severe long-term disease (glomerulonephritis) than with male donor and host (m-->M cGVHD). Interestingly, differences in disease parameters could be seen at 2 wk after parental cell transfer, as evidenced by a 2- to 3-fold greater engraftment of donor CD4(+) T cells in f-->F cGVHD mice, which persisted throughout disease course. Enhanced engraftment of donor CD4(+) T cells in f-->F cGVHD mice was not due to differences in splenic homing, alloreactive precursor frequency, initial proliferation rates, or apoptotic rates, but rather to sustained high proliferation rates during wk 2 of disease compared with m-->M cGVHD mice. Crossover studies (m-->F, f-->M) demonstrated that enhanced donor CD4(+) T cell proliferation and engraftment segregate with the sex of the host. These results demonstrate that the sex of the recipient can influence the expansion of pathogenic T cells, thus increasing long-term the burden of autoreactive T cells and resulting in greater disease severity.

Prolactin and autoimmunity

Prolactin (PRL) is a versatile hormone that is produced by the anterior pituitary gland and various extrapituitary sites including immune cells. Furthermore, PRL has widespread influences on proliferation and differentiation of a variety of cells in the immune system and is, in effect, a cytokine. PRL-receptors (PRL-R) are distributed throughout the immune system and are included as members of the cytokine receptor superfamily. PRL-R signal transduction is mediated by a complex array of signaling molecules of which JAK2, Stat1 and Stat5 pathway have been well studied. In PRL-stimulated T cells, the transcription factor gene, interferon regulatory factor-1 provides a mechanism whereby PRL can regulate the immune response. The human PRL gene is situated on the short arm of chromosome 6 close to the major histocompatibility complex. Polymorphisms of the human PRL gene have implications for production of lymphocyte PRL in SLE. Mild and moderate hyperprolactinemia (HPRL) has been demonstrated in 20-30% of SLE patients and is associated with active disease. HPRL may have a role in lupus nephritis and central nervous system involvement of SLE patients. HPRL stimulated the production of autoantibodies. These evidences support the important role of PRL in autoimmunity and autoimmune diseases, mainly SLE.

Altered neurotransmission in brains of autoimmune mice: pharmacological and neurochemical evidence

Depressive-like behavior is the most profound manifestation of autoimmunity-associated behavioral syndrome in lupus-prone MRL-lpr mice. This led to the hypothesis that chronic autoimmunity and inflammation alter the activity of central serotonergic and dopaminergic systems. Three drugs with a selective mode of action were used to probe the functional status of these two systems in vivo. The behavioral effects of single and repeated intraperitoneal (i.p.) injections of sertraline, quinpirole (QNP) and risperidone were measured in the forced swim and brief sucrose preference tests. In comparison to MRL +/+ controls, autoimmune MRL-lpr mice did not show a reduction in sucrose intake after the administration of sertraline. Acute injection of quinpirole increased floating more in the MRL-lpr than in the control group, while intermittent administration induced self-injurious behavior in both groups. Acute injection of risperidone significantly increased floating in MRL-lpr mice, while repeated administration abolished the difference between the substrains in sucrose intake. These discrepancies in responsiveness implied that the central neurotransmitter activity is dissimilar in the two MRL substrains. This notion was confirmed in a cohort of untreated MRL-lpr and MRL +/+ mice by comparing their neurotransmitter/metabolite levels in several brain regions. In particular, MRL-lpr brains showed increased dopamine (DA) levels in the paraventricular nucleus (PVN) and median eminence (ME), decreased concentrations of serotonin in the PVN and enhanced levels in the hippocampus, as well as decreased norepinephrine (NE) levels in the prefrontal cortex. Behavioral deficits correlated with the changes in PVN and median eminence. These results are consistent with the hypothesis that imbalanced neurotransmitter regulation of the hypothalamus-pituitary axis plays an important role in the etiology of behavioral dysfunction induced by systemic autoimmune disease.

Somatotropic, lactotropic and adrenocortical responses to insulin-induced hypoglycemia in patients with rheumatoid arthritis

Neuroendocrine mechanisms have been suggested to play an important role in the onset and progression of rheumatoid arthritis (RA). The aim of this study was to evaluate hypothalamic-pituitary functions in RA patients by measurement of hormone responses to insulin-induced hypoglycemia. Insulin-hypoglycemia (Actrapid HM 0.1 IU/kg, i.v. as a bolus) was induced in 17 male patients and in 11 age-, gender-, and weight-matched healthy subjects. Concentrations of growth hormone (GH), prolactin (PRL) and cortisol were analyzed in plasma. PRL release after thyreoliberin stimulation (TRH, 200 g, i.v.) was determined in 21 patients with active forms of RA and in 12 control subjects to evaluate pituitary lactotropic response. In RA patients, basal concentrations of glucose, GH, PRL, and cortisol were in the normal range and they were comparable to those in the control group. Stress of hypoglycemia induced significant elevation of GH, PRL, and cortisol concentrations in all groups. Cortisol responses to hypoglycemia were comparable in patients and in control subjects. GH release during hypoglycemia was increased (p < 0.05) and PRL response was attenuated (p < 0.05) in RA patients versus control subjects. After TRH administration, PRL response was the same in patients as in healthy subjects. In conclusion, the present study revealed an altered hypothalamic-pituitary function in patients with RA, namely, an enhanced somatotropic and reduced lactotropic activation in response to insulin-induced hypoglycemia. Basal hormone levels and cortisol release during hypoglycemia were similar to those in healthy subjects.

Prolactin in human systemic lupus erythematosus

In the last decade, evidence has accumulated to support the hypothesis that both mild and moderate elevations of serum prolactin (PRL) participate in the clinical expression and pathogenesis of systemic lupus erythematosus (SLE). Hyperprolactinemia (HPRL) has been found in 20-30% of patients with SLE. HPRL seems to be associated with clinical activity of SLE during pregnancy. Although the relationship between HPRL and active SLE in non-pregnant patients is controversial, recent clinical and experimental studies support the potential role of prolactin (PRL) as a promoter of clinical activity and severity of SLE. Mild elevations of serum PRL secondary to microadenoma could trigger the onset of SLE in a subset of patients. Elevated PRL and interleukin (IL)-6 have been found in the urine of patients with active lupus nephritis and in cerebrospinal fluid (CSF) of patients with active central nervous system (CNS) SLE. PRL may therefore participate in the pathogenesis of lupus nephritis and cerebritis, and the presence of PRL may reflect an abnormal communication between the immune system and the neuroendocrine system in active SLE. Lymphocytes from patients with active SLE produce increased amounts of PRL, and this extrapituitary PRL may participate in aberrant immune processes in SLE. There is exciting new evidence that HPRL in SLE may be explained by stimulation of pituitary PRL secretion by cytokines. In addition, defects in peptidergic modulators and dopamine metabolism have been described in patients with SLE. The interactions between PRL, cytoquines, autoantibodies and organ involvement suggest that PRL participates in local and generalized immune and inflammatory processes and acts as a bridge between the neuroendocrine and immune systems in SLE. Understanding the interactions between these systems in SLE will help us to understand and treat this important autoimmune disease.

Bromocriptine treatment of systemic lupus erythematosus

Prolactin, a peptide hormone, acts as a cytokine. It has been hypothesized that bromocriptine, a dopamine analog that suppresses pituitary secretion of prolactin, suppresses circulating prolactin and, through this mechanism, has the potential to suppress autoimmune disease. This rationale has been applied to the treatment of systemic lupus erythematosus (SLE), a prototype autoimmune illness that occurs spontaneously in animal models such as the F1 hybrid NZBxNZW mouse, and in humans. Treatment with bromocriptine was effective in treating some induced and spontaneous autoimmune disease in experimental models. Bromocriptine did slow the course of SLE in NZBxNZW mice when treatment was started before the appearance of clinical disease. In addition, bromocriptine was effective in treating established disease in this model. In three separate clinical trials, bromocriptine showed evidence that it had a therapeutic effect in treating human lupus. Bromocriptine is currently considered an unproven therapy for SLE. Its use is entirely experimental. The fact that bromocriptine was effective in treating NZBxNZW mice, the beneficial therapeutic effects in human trials, and the low toxicity of the drug form a solid rationale for undertaking further therapeutic trials.

New therapies in systemic lupus erythematosus

A new understanding of the pathogenesis of autoimmunity, the mechanisms of action of older drugs, the advent of target-specific biological therapies and pharmacogenomics has created multiple treatment options for the patient with systemic lupus erythematosus. These include topical therapies, more selective non-steroidal anti-inflammatory agents, hormonal interventions and a new generation of immune suppressives. Currently available strategies also include the use of intravenous gamma globulin, apheresis, stem-cell transplantation and antileprosy preparations alone or in combination with immune suppressives. A handful of biologicals have been studied in clinical trials. After two decades without new options for lupus patients practitioners now have a full menu of improved therapeutic options.

Treatment of systemic lupus erythematosus with bromocriptine

Prolactin, a lactogenic hormone, is a cytokine and an important link between the immune and endocrine systems. Prolactin stimulated disease in autoimmune NZB/NZW mice. Treatment of the mice with the prolactin-lowering dopamine agonist, bromocriptine, suppressed anti-DNA and prolonged life spans. These findings have been applied to humans with systemic lupus erythematosus (SLE). An open-label study, a double blind study, and a study comparing bromocriptine to hydroxychloroquine provided evidence that bromocriptine therapy reduced flares and suppressed disease activity in SLE.

Neuroendocrine immune mechanisms in rheumatic diseases. An overview and future implications

A new physiopathogenetic paradigm may be proposed for RA and possibly its related systemic rheumatic diseases (i.e., mechanisms whereby multiple risk factors initially perturb the homeostasis of core physiologic components over an extended premorbid phase, which may progress to clinical disease in later decompensated stages). These complex interactive processes are likely to be individualized according to genetic, nongenomic somatic, developmental, behavioral, and environmental influences. Future research promises to further elucidate the roles of neuroendocrine mechanisms in the rheumatic diseases and offers promise for enhanced therapies and possible avenues for disease modification if not eventual prevention.