Prolactin and Autoimmunity: Hyperprolactinemia Correlates with Serositis and Anemia in SLE Patients

Circulating prolactin levels and the effect of dopaminergic agonists in systemic lupus erythematosus: a systematic review and meta-analysis

This systematic review of clinical studies investigated whether circulating PRL levels differed between subjects with systemic lupus erythematosus (SLE) and healthy controls, the correlation between circulating PRL and SLE activity, and the effect of dopaminergic agonists as adjuvant therapy for SLE. We searched PubMed, Scopus, Web of Science, Cochrane, Embase, and Google Scholar for case-control and cross-sectional studies investigating circulating PRL levels in subjects with SLE and/or its correlation with disease activity, and clinical trials examining the effect of dopaminergic agonists on SLE activity assessed by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score. Forty-five studies addressing circulating PRL levels in SLE met our inclusion criteria. SLE was associated with an increased odds of hyperprolactinemia (OR 11.69, 95%CI 5.64-24.22) and circulating PRL levels were significantly higher in subjects with SLE than in controls (standardized mean difference of 1.62, 95%CI 1.14-2.09). Circulating PRL was positively correlated with SLE activity assessed by the SLEDAI (correlation coefficient 0.38, 95% CI 0.26-0.48). Two randomized clinical trials with bromocriptine and three prospective open-label trials with quinagolide reported that treatment with dopaminergic agonists was associated with reduced frequency of disease flares and decreased SLEDAI score. Circulating PRL levels were higher in subjects with SLE than in healthy controls and were significantly associated with disease activity. In addition, treatment with the dopaminergic agonists bromocriptine and quinagolide reduced SLE disease activity in small studies and may be a beneficial adjuvant therapy for the disease if larger trials confirm these findings. This review was registered in PROSPERO (CRD42021237156).

Prolactin's paradox: Friend, foe, or both in immune regulation?

Over 100 diseases have been recognized as autoimmune in nature, collectively affecting ∼20 % of the population in industrialized countries. These conditions are more prevalent among women of childbearing age, reflecting the potential association between alterations in the immune-neuroendocrine network, on the one hand, and autoimmune conditions, on the other. Prolactin (PRL), a polypeptide hormone that is primarily (but not only) secreted by the lactotrophic cells of the pituitary gland, is a critical element of the immune-neuroendocrine network. Although this hormone has several nonimmune functions, its role in regulating immune responses and affecting autoimmune inflammation is particularly enigmatic and controversial. Indeed, PRL interacts with various immune cells to bolster the body defenses, but also potentially to exacerbate autoimmune conditions. Understanding how and when PRL acts as a 'friend or foe' is crucial for unraveling its role as a potential therapeutic target in the management of autoimmune diseases (AIDs). This review therefore provides a critical overview of PRL's role in the immune system, and of the influence of this pleiotropic hormone in the development of autoimmunity.

Twenty shades of the mosaic of autoimmunity

Accelerated, inflammatory atherosclerosis and cardiovascular disease have been associated with several autoimmune diseases including RA, AS, SLE, APS and SSc. Non-invasive, ultrasound- based techniques are suitable for the assessment of preclinical vascular pathophysiology. Multiple vascular and other biomarkers including vitamin D, ferritin, prolactin, suPAR, BNP fragments, oxLDL/β2GPI complexes, anti-Hsp60 and others have been associated with cardiometabolic comorbidities. The control of the underlying inflammatory disease is crucial for minimising cardiovascular risk in autoimmune diseases.

Prolactin: A Mammalian Stress Hormone and Its Role in Cutaneous Pathophysiology

The hormone prolactin (PRL) is best recognised for its indispensable role in mammalian biology, specifically the regulation of lactation. Bearing in mind that the mammary gland is a modified sweat gland, it is perhaps unsurprising to discover that PRL also plays a significant role in cutaneous biology and is implicated in the pathogenesis of a range of skin diseases, often those reportedly triggered and/or exacerbated by psychological stress. Given that PRL has been implicated in over 300 biological processes, spanning reproduction and hair growth and thermo- to immunoregulation, a comprehensive understanding of the relationship between PRL and the skin remains frustratingly elusive. In an historical curiosity, the first hint that PRL could affect skin biology came from the observation of seborrhoea in patients with post-encephalitic Parkinsonism as a result of another global pandemic, encephalitis lethargica, at the beginning of the last century. As PRL is now being postulated as a potential immunomodulator for COVID-19 infection, it is perhaps timeous to re-examine this pluripotent hormone with cytokine-like properties in the cutaneous context, drawing together our understanding of the role of PRL in skin disease to illustrate how targeting PRL-mediated signalling may represent a novel strategy to treat a range of skin diseases and hair disorders.

Anti-prolactin treatment alleviates lupus conditions by regulating the JAK2-STAT3 pathway

OBJECTIVES

We previously revealed the role of prolactin (PRL) in antibody production and disease activity in patients with systemic lupus erythematosus. In this study, we sought to determine whether inhibition of PRL could improve lupus-like disease in MRL/lpr mice.

METHODS

The expression levels of PRL in various cell types of lupus patients were measured by flow cytometry. The effects of anti-PRL on animal survival, renal histopathology, creatinine, proteinuria, anti-dsDNA antibody, cytokine production, splenomegaly and lymphadenopathy were assessed. The effect of anti-PRL on the Jak2-Stat3 signalling pathway was detected by western blotting.

RESULTS

Prolactin was upregulated in B cells, neutrophils, CD4+ T cells, and monocytes isolated from patients with lupus. Furthermore, inhibition of PRL by anti-PRL treatment around the time of onset prolonged the survival of MRL/lpr mice, significantly reduced anti-dsDNA antibody production, and alleviated symptoms of lupus nephritis, splenomegaly, and lymphadenopathy. In addition, anti-PRL-treated mice showed a decrease in the levels of pathogenic cytokines such as IL-21 and IL-6. Furthermore, mechanistically, anti-PRL treatment significantly reduced the levels of p-Jak2 and p-Stat3 in MRL/lpr mice.

CONCLUSIONS

In summary, these data suggest that PRL inhibition alleviates lupus-like disease in MRL/lpr mice by modulating the Jak2-Stat3 signalling cascade. More importantly, our results imply the potential of PRL inhibitors and may provide a novel therapeutic approach for lupus.

Knowledge Gaps and Current Evidence Regarding Breastfeeding Issues in Mothers with Chronic Diseases

The prevalence of chronic maternal disease is rising in the last decades in the developed world. Recent evidence indicated that the incidence of chronic maternal disease ranges from 10 to 30% of pregnancies worldwide. Several epidemiological studies in mothers with chronic diseases have mainly focused on the risk for adverse obstetric outcomes. Evidence from these studies supports a correlation between maternal chronic conditions and adverse perinatal outcomes, including increased risk for preeclampsia, cesarean section, preterm birth, and admission in the Neonatal Intensive Care Unit (NICU). However, there is a knowledge gap pertaining to the management of these women during lactation. This review aimed at summarizing the available research literature regarding breastfeeding in mothers with chronic diseases. Adjusted and evidence-based support may be required to promote breastfeeding in women with chronic diseases; however, our comprehension of breastfeeding in this subpopulation is still unclear. The literature related to breastfeeding extends in various scientific areas and multidisciplinary effort is necessary to compile an overview of current evidence and knowledge regarding breastfeeding issues in mothers with chronic diseases.

Clinical course of autoimmune thyroid diseases in women with prolactinomas: Results from a prospective study in a single tertiary centre

INTRODUCTION

Several retrospective and cross-sectional studies have revealed a higher prevalence of autoimmune thyroid diseases (AITD) with a predominance of autoimmune hypothyroidism in prolactinoma patients compared to the general population. To date, we have no data on the clinical course of AITD in these patients. The aim of this prospective study was to assess the clinical course of AITD in female patients with prolactinomas compared to an age- and thyroid-risk factors-matched control group.

MATERIALS AND METHODS

The study population consisted of 144 females (71 patients/73 controls) who underwent approximately a 6-year follow-up. Physical examination, thyroid ultrasound and laboratory testing (measurement of antibodies to thyroglobulin, thyroid peroxidase, TSH-receptor; serum TSH and FT4 levels) were performed twice - at the baseline and at the follow-up visits.

RESULTS

AITD were diagnosed in 26.8% (n=19) of the patients and 9.6% (n=7) of the controls (p=0.007) at baseline visit. At the end of the follow-up (FU), these percentages increased to 33.8% (n=24) among the patients versus 12.3% (n=9) in the control group (p=0.002). Hypothyroidism was significantly more frequent in prolactinoma patients than in controls at the end of the study (19.7% vs. 4.1%; p=0.003). Two prolactinoma patients had hyperthyroidism at the baseline visit and restored euthyroid state with negative TSH-receptor antibodies during the follow-up. We did not observe hyperthyroidism in the control group. Among the hypothyroid subsets, the average daily levothyroxine dose at FU visit varied from 25 to 200mcg in the prolactinoma group compared to 25 to 50mcg in the control group.

CONCLUSIONS

Female patients with prolactinomas seem to be prone to autoimmune hypothyroidism. As a pathogenetic mechanism, we could suggest the selective immunomodulatory action of PRL predominantly on cell autoimmunity, complement activation and antibody-dependent cytotoxicity, resulting in earlier and more rapid progression of Hashimoto's thyroiditis towards hypothyroid state in genetically predisposed individuals.

Prolactin Increases the Frequency of Follicular T Helper Cells with Enhanced IL21 Secretion and OX40 Expression in Lupus-Prone MRL/lpr Mice

Systemic lupus erythematosus is characterized by high levels of IgG class autoantibodies that contribute to the pathophysiology of the disease. The formation of these autoantibodies occurs in the germinal centers, where there is cooperation between follicular T helper cells (T_FH) and autoreactive B cells. Prolactin has been reported to exacerbate the clinical manifestations of lupus by increasing autoantibody concentrations. The objective of this study was to characterize the participation of prolactin in the differentiation and activation of T_FH cells, by performing in vivo and in vitro tests with lupus-prone mice, using flow cytometry and real-time PCR. We found that T_FH cells express the long isoform of the prolactin receptor and promoted STAT3 phosphorylation. Receptor expression was higher in MRL/lpr mice and correlative with the manifestations of the disease. Although prolactin does not intervene in the differentiation of T_FH cells, it does favor their activation by increasing the percentage of T_FH OX40⁺ and T_FH IL21⁺ cells, as well as leading to high serum concentrations of IL21. These results support a mechanism in which prolactin participates in the emergence of lupus by inducing overactive T_FH cells and perhaps promoting dysfunctional germinal centers.

Prolactin, a potential biomarker for chronic GVHD activity

INTRODUCTION

The polypeptide prolactin (PRL) is a peptide hormone and a cytokine mostly secreted from the anterior pituitary gland. PRL is also synthesized in extra pituitary tissues including thymocytes and T lymphocytes. Considering the need for chronic GVHD (cGVHD) biomarkers, we explored the relationship between hyperprolactinemia and active cGVHD in a cohort of long-term post-alloHCT survivors.

METHODS

Three-hundred sixteen adults underwent alloHCT between 2010 and 2016, survived more than 1 year and were included. All patients underwent a regular annual assessment that includes a hormone profile with serum PRL levels.

RESULTS

Overall, 236 (74.7%) patients had cGVHD, and in 199 (63%), the grade was moderate or severe. Sixty-five (21%) recipients had active cGVHD at the time of the annual evaluation, and hyperprolactinemia was documented in 63 (19.9%) patients. Hyperprolactinemia correlated with cGVHD activity (Odds Ratio 6.9 (95% CI; 3.6-13.1); P < .001) in the multivariate analysis. In conclusion, patients with hyperprolactinemia were 6.4 times more likely to have active cGVHD in comparison with those patients with normal levels of PRL (P < .001).

CONCLUSION

Prolactin may serve as a biomarker for cGVHD activity. Further studies are required to confirm these findings, and to explore if hyperprolactinemia has an impact on cGVHD severity and prognosis.

Hypothesis: Rheumatoid arthritis and periodontitis: A new possible link via prolactin hormone

Rheumatoid arthritis and periodontitis are two common chronic inflammatory diseases affecting human population worldwide. The association between the two conditions have been the focus of many researches, trying to explore the possible mechanisms underlying this association. Prolactin hormone, besides its known lactogenic effects acts as a cytokine secreted from various tissues other than the pituitary gland with multiple pleotropic actions in immunity and inflammation. Several data showed that prolactin levels are increased significantly in the synovial and periodontal tissues, and this increase is correlated with disease activity and tissue destruction. Our hypothesis suggests that local prolactin can represent a link between the two conditions. In this work, we suggest a possible mechanistic interactions, hypothesized to form a common path linking between rheumatoid arthritis, periodontitis and prolactin. This is because of the need to develop new treatment strategies for the most effective long term control of inflammation in both conditions.

Prolactin peptide (pPRL) induces anti-prolactin antibodies, ROS and cortisol but suppresses specific immune responses in rainbow trout

Prolactin has several immune functions in fish however, the effects on innate and specific components of rainbow trout immunity are currently unknown. Therefore in this study, prolactin peptide (pPRL) injection in rainbow trout generated anti-PRL antibodies that were confirmed through Western blot assays of fish brain tissue extract. At the same time, this group of fish was immunized with a viral antigen (VP2) and the specific antibody titer generated by the rainbow trout was subsequently determined, as well as the sero-neutralizing capacity of the antibodies. Interestingly, this group of fish (pPRL-VP2) generated approximately 150% less antibodies compared with fish immunized only with the viral antigen (VP2), and pPRL-VP2 fish increased their cortisol level by 4 times compared to the control. Additionally, through qPCR assay, we determined that the pPRL-VP2 fish group decreased pro-inflammatory transcript expression, and the serum of these (pPRL-VP2) fish stimulated ROS production in untreated fish leukocytes, a phenomenon that was blocked by the pharmacological cortisol receptor inhibitor (RU486). Collectively, this is the first report that indicates that pPRL could modulate both components of immunity in rainbow trout.

Hyperprolactinaemia

Hyperprolactinaemia is one of the most common problems in clinical endocrinology. It relates with various aetiologies (physiological, pharmacological, pathological), the clarification of which requires careful history taking and clinical assessment. Analytical issues (presence of macroprolactin or of the hook effect) need to be taken into account when interpreting the prolactin values. Medications and sellar/parasellar masses (prolactin secreting or acting through “stalk effect”) are the most common causes of pathological hyperprolactinaemia. Hypogonadism and galactorrhoea are well-recognized manifestations of prolactin excess, although its implications on bone health, metabolism and immune system are also expanding. Treatment mainly aims at restoration and maintenance of normal gonadal function/fertility, and prevention of osteoporosis; further specific management strategies depend on the underlying cause. In this review, we provide an update on the diagnostic and management approaches for the patient with hyperprolactinaemia and on the current data looking at the impact of high prolactin on metabolism, cardiovascular and immune systems.

Exacerbations of autoimmune diseases during pregnancy and postpartum

Autoimmune diseases represent a complex heterogeneous group of disorders that occur as a results of immune homeostasis dysregulation and loss of self-tolerance. Interestingly, more than 80% of the cases are found among women at reproductive age. Normal pregnancy is associated with remarkable changes in the immune and endocrine signaling required to tolerate and support the development and survival of the placenta and the semi-allogenic fetus in the hostile maternal immune system environment. Gravidity and postpartum represent an extremely challenge period, and likewise the general population, women suffering from autoimmune disorders attempt pregnancy. Effective preconception counseling and subsequent gestation and postpartum follow-up are crucial for improving mother and child outcomes. This comprehensive review provides information about the different pathways modulating autoimmune diseases activity and severity, such as the influence hormones, microbiome, infections, vaccines, among others, as well as updated recommendations were needed, in order to offer those women better medical care and life quality.

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.

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.

Prolactin activates IRF1 and leads to altered balance of histone acetylation: Implications for systemic lupus erythematosus

Objectives: Prolactin is known to be associated with autoimmune disease; however, the mechanisms are incompletely understood. Previous studies have highlighted the effects on B-cell tolerance and monocyte/macrophage activation. One study found that prolactin could activate IRF1, a transcription factor implicated in SLE and interferon responses. We hypothesized that prolactin elicited transcriptional regulation though an epigenetic process related to IRF1 activation in monocytes. This study examined IRF1 activation and downstream epigenetic effects.Methods: Protein analysis, qRT-PCR, and ChIP assays were used in a human monocytic cell line and primary monocytes to define changes related to acute and chronic prolactin exposure.Results: We found that prolactin acutely induced both expression and activation of IRF1. Prolactin induced interactions of IRF1 with the histone acetyltransferase co-activators CBP and p300. Chronic prolactin induced expression of multiple histone modifying proteins and genes within the interferon signature suggesting that the prolonged exposure to prolactin resets the landscape and balance of chromatin modifying enzymes.Conclusion: These data provide insight into the mechanism of the association of prolactin with autoimmunity. We found effects at the level of epigenetics, an area not previously explored. Our data support a role for chronic prolactin regulating the expression of genes setting the landscape of chromatin modifying enzymes and driving the interferon signature. This novel finding is of relevance in systemic lupus erythematosus, where clinical effects of hyperprolactinemia have been recognized.

Autoimmune thyroid diseases are more common in patients with prolactinomas: a retrospective case-control study in an Italian cohort

BACKGROUND

Prolactin may exert immunological effects. Over the years, a higher prevalence of autoimmune thyroid diseases (ATD) has been reported in patients with prolactinomas (PRLs) in areas with sufficient iodine intake.

PURPOSE

The aim of our study was to evaluate the prevalence of ATD [Graves' disease (GD) and chronic autoimmune thyroiditis (AIT)] in a retrospective cohort of Italian patients with PRLs compared to a sex-matched control group, represented by subjects with non-functioning pituitary adenoma (NFPA) or empty sella (ES).

MATERIALS AND METHODS

We enrolled 149 patients (108 F/41 M) with PRLs (110 micro/39 macro) and 143 subjects (100 F/43 M) with NFPA (n = 96, 56 micro/40 macro) or ES (n = 47), with normal serum prolactin. Neck ultrasound and thyroid function tests (anti-thyroid antibodies, TSH, FT3 and FT4) were performed in all patients.

RESULTS

In PRLs, median serum prolactin was significantly higher (98.3 vs. 8.9 ng/ml, p ≤ 0.0001), while age was lower (34 vs. 46 years, p ≤ 0.001) compared to controls. The prevalence of ATD was 13.4% (20/149) in PRLs (1 GD and 19 AIT) compared to 6.3% (9/143) in the controls (p = 0.042). At the multivariate analysis, serum prolactin was the only independent factor predicting ATD. Thyroid volume (12.5 ± 5.9 ml vs. 12.8 ± 10 ml, p = 0.47) and the presence of uni- or multinodular goiter (29.5% vs. 35%, p = 0.35) did not differ between PRLs and control groups.

CONCLUSIONS

Our data in an area with mild iodine deficiency confirm a higher prevalence of ATD in patients with prolactinomas.

Prolactin, autoimmunity, and motherhood: when should women avoid breastfeeding?

The sexual dimorphic prevalence of autoimmunity represents one of the most alluring observations among the mosaic of autoimmunity. Sex hormones are believed to be a mainstay of this asymmetry. The greater prevalence of autoimmunity among fertile women, disease onset/relapses during pregnancy, and postpartum are some of the points that support this theory. Undeniably, motherhood represents one of the most remarkable challenges for the immune system that not only has to allow for the conceptus but also deal with extraordinary hormonal alterations. Prolactin has a recognized immune-stimulatory effect, mainly inhibiting the negative selection of autoreactive B lymphocytes. In accordance, hyperprolactinemia has been associated with several autoimmune diseases, interfering with its pathogenesis and activity. During the pregnancy and lactation period, assorted autoimmune patients experience relapses, suggesting an active interference from increased levels of prolactin. This association was found to be significant in systemic lupus erythematosus, rheumatoid arthritis, and peripartum cardiomyopathy. Furthermore, treatment with bromocriptine has shown beneficial effects specially among systemic lupus erythematosus patients. In this review, we attempt to provide a critical overview of the link between prolactin, autoimmune diseases, and motherhood, emphasizing whether breastfeeding should be avoided among women, both with diagnosed disease or high risk for its development.

Association of extrapituitary prolactin promoter polymorphism with disease susceptibility and anti-RNP antibodies in Mexican patients with systemic lupus erythematosus

INTRODUCTION

Prolactin (PRL) is a 23-kDa protein that can be synthesized and secreted by pituitary and extrapituitary tissues such as immune cells due to its expression being regulated by two independent promoter regions. The promoter which is responsible for extrapituitary expression contains the single nucleotide polymorphism (SNP) -1149 G/T previously associated with autoimmune diseases in various populations. This study evaluates the relationship of PRL -1149 G/T polymorphism with PRL serum levels and clinical characteristics in systemic lupus erythematosus (SLE) patients from western Mexico.

MATERIAL AND METHODS

One hundred and sixty-three SLE patients classified according to the 1982 American College of Rheumatology (ACR) SLE classification criteria and 326 unrelated control subjects (CS), both from western Mexico, were included. The PRL -1149 G/T polymorphism was genotyped using the polymerase chain reaction restriction fragment length polymorphism technique, and both PRL serum levels and autoantibodies were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

We found an association between the PRL -1149 TT genotype and SLE according to the recessive genetic model (OR = 2.26, 95% CI: 1.01-5.08, p = 0.04). The TT genotype was associated with anti-RNP antibodies (p = 0.04) and with higher scores of the Mex-SLEDAI (p = 0.02). Moreover, SLE patients showed elevated PRL serum levels (12.4 ng/ml; p < 0.01), and this condition was associated with renal activity and the presence of anti-RNP antibodies.

CONCLUSIONS

PRL -1149 TT genotype is associated with susceptibility to SLE in a Mexican-Mestizo population, and high PRL serum levels are associated with anti-RNP antibodies and renal activity.

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.

Short-Term Hyperprolactinemia Reduces the Expression of Purinergic P2X7 Receptors during Allergic Inflammatory Response of the Lungs

PURPOSE

We have previously shown that domperidone-induced short-term hyperprolactinemia reduces the lung's allergic inflammatory response in an ovalbumin antigenic challenge model. Since purinergic receptor P2X7R activity leads to proinflammatory cytokine release and is possibly related to the pathogenesis of allergic respiratory conditions, the present study was designed to investigate a possible involvement of purinergic and prolactin receptors in this phenomenon.

METHODS

To induce hyperprolactinemia, domperidone was injected intraperitoneally in rats at a dose of 5.1 mg × kg-1 per day for 5 days. P2X7 expression was evaluated by lung immunohistochemistry while prolactin receptor expression in bronchoalveolar lavage leukocytes was analyzed through flow cytometry.

RESULTS

Previous reports demonstrated that rats subjected to short-term hyperprolactinemia exhibited a decrease in leukocyte counts in bronchoalveolar lavage, especially granulocytes. Here, it is revealed that hyperprolactinemia promotes an increased expression of prolactin receptors in granulocytes. Also, increased expression of purinergic P2X7R observed in allergic animals was significantly reduced by hyperprolactinemia.

CONCLUSIONS

Both purinergic and prolactin receptor expression changes occur during the anti-asthmatic effect of hyperprolactinemia.

Morbidity and mortality in patients with hyperprolactinaemia: the PROLEARS study

PURPOSE

High serum prolactin concentrations have been associated with adverse health outcomes in some but not all studies. This study aimed to examine the morbidity and all-cause mortality associated with hyperprolactinaemia.

METHODS

A population-based matched cohort study in Tayside (Scotland, UK) from 1988 to 2014 was performed. Record-linkage technology was used to identify patients with hyperprolactinaemia that were compared to an age-sex-matched cohort of patients free of hyperprolactinaemia. The number of deaths and incident admissions with diabetes mellitus, cardiovascular disease, cancer, breast cancer, bone fractures and infectious conditions were compared by the survival analysis.

RESULTS

Patients with hyperprolactinaemia related to pituitary tumours had no increased risk of diabetes, cardiovascular disease, bone fractures, all-cause cancer or breast cancer. Whilst no increased mortality was observed in patients with pituitary microadenomas (HR = 1.65, 95% CI: 0.79-3.44), other subgroups including those with pituitary macroadenomas and drug-induced and idiopathic hyperprolactinaemia demonstrated an increased risk of death. Individuals with drug-induced hyperprolactinaemia also demonstrated increased risks of diabetes, cardiovascular disease, infectious disease and bone fracture. However, these increased risks were not associated with the degree of serum prolactin elevation (P_trend > 0.3). No increased risk of cancer was observed in any subgroup.

CONCLUSIONS

No excess morbidity was observed in patients with raised prolactin due to pituitary tumours. Although the increased morbidity and mortality associated with defined patient subgroups are unlikely to be directly related to the elevation in serum prolactin, hyperprolactinaemia might act as a biomarker for the presence of some increased disease risk in these patients.

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.

Autoimmune hypothyroidism is three times more frequent in female prolactinoma patients compared to healthy women: data from a cross-sectional case-control study

BACKGROUND

The potent immunomodulatory action of prolactin has been demonstrated in many experimental in vitro studies. In accordance with these data, our retrospective analyses revealed higher prevalence of autoimmune thyroid diseases in prolactinoma patients compared to general population.

PURPOSE

A cross-sectional case-control study was carried out in a single tertiary referral centre. The main aim was to assess the frequency of newly diagnosed autoimmune thyroid diseases in female patients with prolactinomas.

METHODS

The study population consisted of 260 females (154 patients and 106 sex-matched, ethnicity-matched, and age-matched healthy controls) enroled in a prospective manner. Physical exam, thyroid ultrasound, and laboratory testing (measurement of antibodies to thyroglobulin, thyroid peroxidase, TSH-receptor, serum TSH and FT4 levels) were performed in all study participants.

RESULTS

Autoimmune thyroid diseases were diagnosed in 29.9% of the patients and 10.4% of the healthy subjects (p  = 0.0002). Subclinical hypothyroidism was found in 9.7% of the patients versus 2.8% of the controls (p  = 0.044). Autoimmune hyperthyroidism was observed in 1.3% of all patients.

CONCLUSIONS

The prevalence of newly diagnosed autoimmune thyroid diseases, and especially the subclinical hypothyroidism, was significantly higher in our female prolactinoma patients in comparison to age-matched healthy women. Based on our results, we suggest routine screening for autoimmune thyroid diseases (thyroid function, immunology and ultrasound examination) in all female patients with prolactinoma at the time of diagnosis. We also recommend a close follow-up of thyroid function in these women in case of pregnancy and after delivery.

Do serum prolactin levels correlate with antibodies against desmoglein in pemphigus vulgaris?

Background:

Pemphigus vulgaris is a chronic inflammatory disease of skin, the etiology of which is not completely known. Despite the latter, anti-desmoglein antibodies play a proven role in the pathogenesis. Recent studies showed an etiologic effect for prolactin in the pemphigus vulgaris. This study aimed to quantify the correlation between serum prolactin levels and anti-desmoglein antibodies in patients with pemphigus vulgaris.

Materials and Methods:

Prolactin and antibodies against desmoglein 1 and 3 measured with ELISA in 14 new subjects of pemphigus vulgaris.

Results:

There was no statistically significant relation between both serum prolactin and anti-desmoglein1 levels (r = 0.02, P = 0.47) and serum prolactin and anti-desmoglein 3 levels (r= -0.09, P = 0.38).

Conclusion:

This study indicates that no correlation was found between serum prolactin levels and anti-desmoglein 1 levels and serum prolactin and anti-desmoglein 3 levels. However, other studies should be initiated regarding exact molecular and cellular effects of prolactin in the pathogenesis of pemphigus vulgaris.

The epidemiology of hyperprolactinaemia over 20 years in the Tayside region of Scotland: the Prolactin Epidemiology, Audit and Research Study (PROLEARS)

OBJECTIVE

To estimate the prevalence and incidence of hyperprolactinaemia. Hyperprolactinaemia is a common problem in endocrine practice, but its epidemiology has not been accurately established.

STUDY DESIGN

A population-based retrospective follow-up study in Tayside, Scotland (population 400,000), from 1993 to 2013.

PATIENTS

Record linkage technology (biochemistry, prescribing, hospital admissions, radiology, mortality and maternity data) was used to identify all patients with a serum prolactin measurement. From these, cases were defined as those with a prolactin greater than 1000 mU/L (47·2 ng/ml) or at least three prescriptions for a dopamine agonist.

MEASUREMENTS

Number of prevalent and incident cases of hyperprolactinaemia per calendar year by age, sex and cause of hyperprolactinaemia.

RESULTS

A total of 32289 patients had a serum prolactin assay undertaken, of which 1301 had hyperprolactinaemia not related to pregnancy: 25·6% patients had pituitary disorder, 45·9% were drug-induced, 7·5% had macroprolactin and 6·1% had hypothyroidism, leaving 15·0% idiopathic. Over the 20 years, there was a fourfold increase in the number of prolactin assays performed, and prevalence of hyperprolactinaemia was initially 0·02%, but rose to 0·23% by 2013. Overall incidence was 13·8 cases per 100000 person-years (20·6 in 2008-13) and was 3·5 times higher in women than in men. The highest rates were found in women aged 25-44 years. Drug-induced causes tripled during the 20 years.

CONCLUSIONS

Rising prevalence of hyperprolactinaemia is probably due to an increased ascertainment and increased incidence of psychoactive drug-related causes. Rates are higher in women than in men but only before the age of 65 years.

Prevalence of autoimmune disease in patients with prolactinomas and non-functioning pituitary adenomas

PURPOSE

Prolactin can affect autoimmune response and evidence suggests that hyperprolactinemia can primarily precipitate autoimmunity. We postulate that patients with prolactinomas are more prone to autoimmune disease (AID).

METHODS

We conducted a retrospective case-control study comparing prevalence of AID in 100 prolactinoma patients (PRL-P, cases) and 100 age- and gender-matched non-functioning pituitary adenoma patients (NFPA-P, controls) assessed at the Neuroendocrine Clinics of the McGill University Health Centre between January 2005 and December 2014. Comparisons were done using a conditional logistic regression (CLR) analysis. Multiple imputation was used to account for missing data values.

RESULTS

Sixty-eight women and 32 men were in each group. Median age was 37 years for PRL-P and 46 years for NFPA-P. AID was diagnosed in 28/100 cases and 16/100 controls. Autoimmune thyroid disease was the most common AID reported in both groups, representing 70 and 61% of the AID diagnoses respectively. CLR analysis revealed a multiplicative interaction effect between AID prevalence and age (p 0.004). Odds ratios for AID in PRL-P compared to NFPA-P increase with age and become significant at age 43, reaching 4.17 (95% CI 1.26, 13.82) at age 45 and 8.09 (95% CI 1.96, 33.43) at age 50 (p 0.05).

CONCLUSION

Our data showed a higher prevalence of AID in both PRL-P and NFPA-P than in a reference population. In both groups, prevalence of AID increased with age, given a multiplicative interaction effect. A significant higher prevalence of autoimmunity in PRL-P compared with NFPA-P occurs after age 43. These associations may have significant implications for the management of prolactinoma patients.

Attenuated allergic inflammatory response in the lungs during lactation

AIMS

To evaluate the influence of lactation on lung immune function during allergic inflammation.

MAIN METHODS

Female rats, 60-90days old, were divided into three groups: no lung allergy virgins (N group), ovalbumin (OVA)-immunized and sensitized virgins (V group), and OVA-immunized and sensitized lactating females (L group). On gestation day (GD) 10, all animals in L group received a subcutaneous injection of 0.1mg·kg(-1) OVA plus aluminum hydroxide. On GD17, the L group received a subcutaneous booster injection of 10μg OVA plus 10mg aluminum hydroxide. After 7days, an inhalatory challenge with 1% OVA was given in 15min sessions for 3 consecutive days. Animals from the V group received the same treatment, meaning both tests and time intervals between OVA treatment and inhalatory challenge were the same as in the L group. Twenty-four hours after the last inhalation session, the animals were euthanized, and the following tests were performed: total and differential bronchoalveolar lavage (BAL) and femoral marrow lavage (FML) leukocyte counts, quantification of tumor necrosis factor α (TNF-α) and interferon γ (IFN-γ) levels in BAL fluid, and quantification of plasma corticosterone and catecholamine levels.

KEY FINDINGS

The L group presented lower BAL total leukocyte counts and decreases in the number of eosinophils and macrophages compared with the V group. They also expressed higher BAL IFN-γ and lower plasma corticosterone levels. Plasma norepinephrine levels were higher in the L group than in the N and V groups.

SIGNIFICANCE

Lactating female rats presented less intense allergic lung inflammation. Our findings suggest that lactation may protect females from asthmatic crises.

The challenge of treating orphan disease

Uncommon or orphan diseases are less frequently addressed in mainstream medical journals and, as a consequence, their understanding and clinical recognition may rely on case series or anecdotal data with limited guidelines and management directions. The study of selected underrepresented autoimmune and allergy conditions is the subject of the present issue of Clinical Reviews in Allergy and Immunology to provide peculiar perspectives on common and rare themes. First, allergy remains a major concern for physicians worldwide despite the limited developments over the past years, particularly for antigens such as mite or Alternaria alternata, and due to the increasing incidence of drug hypersensitivity. Second, the female predominance of autoimmune diseases such as systemic sclerosis is well recognized but enigmatic, and a unifying hypothesis remains elusive. Third, the management of conditions triggered by infectious agents as in Guillain-Barre syndrome or mixed cryoglobulinemia is challenging, and clinical guidelines are needed in the setting of infections and autoimmunity. Fourth, gamma-delta T cells represent major players in innate immunity and are the subject of extensive studies in autoimmune diseases to provide new therapeutic targets for disease prevention or modulation in the near future. Ultimately, we acknowledge the major developments in the broad fields of rheumatology and immunology and expect that microbiota definition, epigenetics studies, and microRNA analysis will provide new exciting avenues toward the understanding and treatment of chronic and acute inflammation.

Serum macroprolactin levels in pregnancy and association with thyroid autoimmunity

BACGROUND

To assess the contribution of macroprolactin to high serum prolactin levels and their association with thyroid status and thyroid autoimmunity during pregnancy.

METHODS

138 pregnant women who suspected of having thyroid dysfunction were studied and divided into three groups according to the thyroid status; group 1; euthyroidism (n 40), group 2; hypothyroidism (n 54), and group 3; hyperthyroid (n 44). Polyethylene glycol (PEG) precipitation method was used for detection of macroprolactin. A percentage recovery of 40 % or less is considered as macroprolactinemia. If macroprolactin was negative, the percentage of monomeric prolactin recovery (monoPRL %) after PEG precipitation was used for comparison between the groups.

RESULTS

Macroprolactinemia was found in two patients (1.4 %) one from hypothyroid and other from euthyroid group. Basal prolactin levels in these patients were 400 and 403 ng/mL respectively. Referring to all patients, there was no correlation between PRL, macroPRL or monoPRL % with thyroid hormone status and also with the serum levels of thyroid antibodies (p > 0.05). A positive correlation was observed between the serum levels of PRL with TSH (p = 0.014 and r = 0.219), while a negative correlation was found with FT4 (p = 0.011 and r = -0.227).

CONCLUSIONS

Despite the fact that serum prolactin levels were found to be high during pregnancy, the contribution of macroprolactin was found to be insignificant in our study. Unlike other auto immune diseases, we could not find any relationship between thyroid autoimmunity and PRL, macroPRL or monoPRL %. These results confirmed that measured prolactin was quite homogeneous during pregnancy.

The prolactin receptor as a therapeutic target in human diseases: browsing new potential indications

INTRODUCTION

Prolactin (PRL) signaling has emerged as a relevant target in breast and prostate cancers. This has encouraged various laboratories to develop compounds targeting the PRL receptor (PRLR). As the latter is widely distributed, it is timely to address whether other conditions could also benefit from such inhibitors.

AREAS COVERED

The authors briefly overview the two classes of PRLR blockers, which involve: i) PRL-core based analogs that have been validated as competitive antagonists in various preclinical models, and ii) anti-PRLR neutralizing antibodies that are currently in clinical Phase I for advanced breast and prostate cancers. The main purpose of this review is to discuss the multiple organs/diseases that may be considered as potential targets/indications for such inhibitors. This is done in light of reports suggesting that PRLR expression/signaling is increased in disease, and/or that systemic or locally elevated PRL levels correlate with (or promote) organ pathogenesis.

EXPERT OPINION

The two immediate challenges in the field are i) to provide the scientific community with potent anti-prolactin receptor antibodies to map prolactin receptor expression in target organs, and ii) to take advantage of the availability of functionally validated PRLR blockers to establish the relevance of these potential indications in humans.

The effects of bromocriptine on preventing postpartum flare in systemic lupus erythematosus patients from South China

Objective. Prolactin plays an important role on the disease flare of postpartum SLE patients. 76 pregnant SLE patients were enrolled in this study to evaluate the efficacy of bromocriptine (an inhibitor of prolactin secretion) on preventing the postpartum disease relapse. Methods. Patients were randomly divided into the treatment group (bromocriptine, 2.5 mg oral, twice a day for 14 days after delivery) and the control group. All the patients were followed up for 12 months. Clinical features were recorded every 4 weeks. Serum prolactin and estradiol levels were measured at the second week and the second month after delivery. The endpoint of the study was disease relapse and defined when SLEDAI score increased by ≥3 points from the antenatal baseline. Results. (1) Serum levels of prolactin and estradiol decreased significantly in bromocriptine treatment group at the second week (P < 0.001) and second month (P < 0.05) after delivery compared to control group. (2) The relapse rate of the treatment group was lower than the control group (χ² = 4.68, P = 0.0305). Conclusions. Two weeks of oral bromocriptine treatment in postpartum SLE patients may relieve the disease from hyperprolactinemia and hyperestrogenemia and may be beneficial in preventing the patients from disease relapse.

Prolactin variations during risperidone therapy in a sample of drug-naive children and adolescents

The aim of this prospective observational study was to investigate the variations of serum prolactin hormone (PRL) in a sample of 34 drug-naive patients (mean age 13 years) who started risperidone therapy assuming that several factors may favor the increase in serum PRL. Serum PRL and hyperprolactinemia clinical signs were examined at baseline (T0) and after almost 3 months of treatment (T1). We considered sex, pubertal status, risperidone dosage, psychiatric diagnosis, and any personal/family history of autoimmune diseases. The mean serum PRL value increased between T0 and T1 (P=0.004). The mean serum PRL was higher in females in the pubertal/postpubertal stage and for risperidone dosage up 1 mg/day. Hyperprolactinemia was found in 20% of patients at T0 and in 38% of patients at T1 (P=0.03). The mean serum PRL increase was greater in early-onset schizophrenia spectrum psychosis patients compared with no-early-onset schizophrenia spectrum psychosis patients (P=0.04). The increase in PRL was higher in patients with a personal and a family history of autoimmune diseases. This study suggests that the increase in serum PRL in patients treated with risperidone may be linked not only to the drug and its dosage but also to several risk factors such as sex, pubertal stage, psychiatric disease, and autoimmune disorders.

Gender differences in autoimmune disease

Autoimmune diseases are a range of diseases in which the immune response to self-antigens results in damage or dysfunction of tissues. Autoimmune diseases can be systemic or can affect specific organs or body systems. For most autoimmune diseases there is a clear sex difference in prevalence, whereby females are generally more frequently affected than males. In this review, we consider gender differences in systemic and organ-specific autoimmune diseases, and we summarize human data that outlines the prevalence of common autoimmune diseases specific to adult males and females in countries commonly surveyed. We discuss possible mechanisms for sex specific differences including gender differences in immune response and organ vulnerability, reproductive capacity including pregnancy, sex hormones, genetic predisposition, parental inheritance, and epigenetics. Evidence demonstrates that gender has a significant influence on the development of autoimmune disease. Thus, considerations of gender should be at the forefront of all studies that attempt to define mechanisms that underpin autoimmune disease.

Autoimmunity in 2012

The initiation and perpetuation of autoimmunity recognize numerous checkpoints, from the genomic susceptibility to the breakdown of tolerance. This latter phenomenon includes the loss of B cell anergy and T regulatory cell failure, as well as the production of autoantibodies and autoreactive T cells. These mechanisms ultimately lead to tissue injury via different mechanisms that span from the production of proinflammatory cytokines to the chemotaxis of immune cells to the target sites. The pathways to autoimmunity have been widely investigated over the past year and resulted in a number of articles in peer-reviewed journals that has increased by nearly 10 % compared to 2011. We herein follow on the attempt to provide a brief discussion of the majority of articles on autoimmune diseases that were published in the major immunology journals in the previous solar year. The selection is necessarily arbitrary and may thus not be seen as comprehensive but reflects current research trends. Indeed, 2012 articles were mostly dedicated to define new and old mechanisms with potential therapeutic implications in autoimmunity in general, though based on specific clinical conditions or animal models. As paradigmatic examples, the environmental influence on autoimmunity, Th17 changes modulating the autoimmune response, serum autoantibodies and B cell changes as biomarkers and therapeutic targets were major issues addressed by experimental articles in 2012. Further, a growing number of studies investigated the sex bias of autoimmunity and supported different working hypotheses to explain the female predominance, including sex chromosome changes and reproductive life factors. In conclusion, the resulting scenario illustrates that common factors may underlie different autoimmune diseases and this is well represented by the observed alterations in interferon-α and TGFβ or by the shared signaling pathways.

Less travelled roads in clinical immunology and allergy: drug reactions and the environmental influence

Allergy and clinical immunology are examples of areas of knowledge in which working hypotheses are dominant over mechanistic understanding. As such, sometimes scientific efforts follow major streams and overlook some epidemiologically prevalent conditions that thus become underestimated by the research community. For this reason, we welcome the present issue of Clinical Reviews in Allergy and Immunology that is dedicated to uncommon themes in clinical immunology and allergy. First, comprehensive discussions are provided for allergy phenomena of large potential impact in clinical practice such as reactions to cephalosporins or aspirin-induced asthma and in everyday life such as allergies to food additives or legumes. Further, the issue addresses other uncommon themes such as urticaria and angioedema, cercarial dermatitis, or late-onset inflammation to soft tissue fillers. Last, there will be discussion on transversal issues such as olfactory defects in autoimmunity, interleukin 1 beta pathway, and the search for new serological markers in chronic inflammation. As a result, we are convinced that this issue will be of help to clinicians involved in internal medicine as well as to allergists and clinical immunologists. More importantly, we are convinced that these discussions will be of interest also to basic scientists for the numerous translational implications.

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.

Prolactin levels correlate with abnormal B cell maturation in MRL and MRL/lpr mouse models of systemic lupus erythematosus-like disease

Prolactin (PRL) plays an important role in modulating the immune response. In B cells, PRL enhances antibody production, including antibodies with self-specificity. In this study, our aims were to determine the level of PRL receptor expression during bone-marrow B-cell development and to assess whether the presence of high PRL serum concentrations influences absolute numbers of developing populations and disease outcome in lupus-prone murine models. We observed that the PRL-receptor is expressed in early bone-marrow B-cell; the expression in lupus-prone mice, which had the highest level of expression in pro-B cells and immature cells, differed from that in wild-type mice. These expression levels did not significantly change in response to hyperprolactinemia; however, populations of pro-B and immature cells from lupus-prone strains showed a decrease in the absolute numbers of cells with high PRL-receptor expression in response to PRL. Because immature self-reactive B cells are constantly being eliminated, we assessed the expression of survival factor BIRC5, which is more highly expressed in both pro-B and immature B-cells in response to PRL and correlates with the onset of disease. These results identify an important role of PRL in the early stages of the B-cell maturation process: PRL may promote the survival of self-reactive clones.

Prolactin rescues and primes autoreactive B cells directly and indirectly through dendritic cells in B6.Sle3 mice

The lupus susceptibility interval Sle3/5 confers responsiveness to prolactin in C57BL/6 (B6) mice and hyperprolactinaemia induces a lupus-like phenotype in B6.Sel3/5 mice. In this study, the immunostimulatory effects of prolactin in B6 mice containing the Sle3 portion of the Sel3/5 interval (B6.Sle3 mice) were dissected. Because of the Sle3 interval's involvement in activation of myeloid cells, the effect of dendritic cells (DCs) from prolactin-treated B6.Sle3 mice on the phenotype of B6 mice was also evaluated. B cells from prolactin-treated B6 and B6.Sle3 mice and from B6 recipients of prolactin-modulated DCs from B6.Sle3 mice were tested for DNA-reactivity and resistance to B cell receptor (BCR)-mediated apoptosis. The expression of co-stimulatory molecules on lymphocytes and myeloid cells was also evaluated. In prolactin-treated B6.Sle3 mice, transitional type 2 B cells increased while type 1 B cells decreased as a consequence of prolactin-induced resistance to BCR-mediated apoptosis leading to the survival of DNA-reactive B cells. Follicular B cells from prolactin-treated mice expressed increased levels of CD40, B7·2 and IA(b), and DCs and monocytes had higher levels of CD44 and B7·2 than placebo-treated mice. Adoptive transfer of DCs from prolactin-treated B6.Sle3 mice to B6 recipients demonstrated the intrinsic ability of prolactin-modulated DCs to induce a development of lupus-like characteristics in B6 mice. Based on these results, prolactin accelerates the breakdown of immune tolerance in B6.Sle3 mice by promoting the survival, maturation and activation of autoreactive B cells, DCs and macrophages.

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.

Systemic lupus erythematosus with a non functioning pituitary macroadenoma

Background:

Malignancies are more common in patients with systemic lupus erythematosus (SLE) than the general population. SLE patients are recognized to have higher prolactin levels. However, there are very few reported cases of SLE with pituitary adenomas.

Case Report:

We report the second case of a pituitary adenoma in a patient with underlying SLE. A 51 year old lady presented with blurred vision and magnetic resonance imaging of the brain demonstrated a pituitary macroadenoma with mildly elevated serum prolactin levels. The diagnosis of a non functioning pituitary macroadenoma was confirmed histologically. The diagnosis of SLE was made on the basis of thrombocytopenia, antinuclear antibodies, anti double stranded DNA antibodies and lupus nephritis (confirmed on renal biopsy). The patient initially received medical therapy with carbegoline, followed by transsphenoidal neurosurgery for the pituitary macroadenoma. SLE with lupus nephritis was treated with steroids and low dose intravenous cyclophosphamide.

Conclusions:

Hyperprolactinaemia is prevalent in twenty to thirty percent of SLE patients but it is rarely due to a prolactinoma. The source of excessive circulating prolactin in SLE patients has not been fully determined.