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.

Autoimmune Fibrotic Adverse Reactions in One-Year Treatment with Cabergoline for Women with Prolactinoma.

AIM: Cabergoline is related to an elevated risk of fibrotic adverse reactions including cardiac valvular and pleuropulmonary fibrosis. We investigated pulmonary and cardiac valve fibrosis and immunological markers before and after 3 and 12 months of treatment with cabergoline in women with prolactinoma. MATERIAL-METHODS: The study included thirty-two women with newly diagnosed prolactinoma and 28 healthy women. CAB cumulative dose was 7.8±5.5 mg after 3-month therapy, and 31±22 mg after 12-month follow-up. The risk of autoimmune adverse fibrotic reactions related to CAB treatment including cardiac valvulopathy and pulmonary fibrosis were assessed by a transthoracic echocardiography and pulmonary function tests, respectively. Immunological markers including Antistreptolysin O, Rheumatoid factor, Immunglobuline E, Antinuchlear antibody were also evaluated. RESULTS: Before the start of CAB therapy, the total prevalence of trace grade of mitral, aortic, pulmonic, and tricuspid valve regurgitations were found as 34%, 3%, 6.3%, and 39 % respectively in women with prolactinoma. After improving of prolactin levels with CAB treatment, no change was found in the prevalence of the all valve regurgitations. There was no deterioration in pulmonary function tests. Rheumatoid factor was found higher in newly diagnosed women with prolactinoma than in healthy women (p=0.01), and this was improved by CAB therapy (p=0.005). CONCLUSION: The prospective study indicated that sufficient cabergoline doses for a period of one year treatment of prolactinoma were not found to be related to fibrotic adverse reactions including cardiac valvular and pulmonary fibrosis or increased levels of immunological marker, apart from rheumatoid factor. For the first time Rf was found higher in newly diagnosed women with prolactinoma and was improved after cabergoline therapy.

High prevalence of autoimmune thyroid diseases in patients with prolactinomas: A cross-sectional retrospective study in a single tertiary referral centre.

BACKGROUND: Prolactin has been shown to exert potent immunomodulatory activities. DESIGN: Retrospective cross-sectional study examining the prevalence of autoimmune thyroid diseases (AITD) in patients with prolactinomas. The medical files of 462 patients (367 women and 95 men) followed up at a single tertiary referral centre were analyzed. RESULTS: The prevalence of AITD among prolactinoma patients was estimated at 21.0% (23.2% in females and 12.6% in males). In 51.5% of the patients, diagnosis of prolactinoma preceded the development of AITD; in 37.2%, both diseases were simultaneously diagnosed and 11.3% of patients were diagnosed first with AITD. Hyperthyroidism was observed in 1.24% of the investigated subjects. Primary hypothyroidism was detected in 15.6% of all patients (16.4% in women; 10.7% in men) with a mean incidence of 24 cases/1000/year. CONCLUSIONS: Our results demonstrate the high frequency of AITD in patients with prolactinomas. The prevalence rate of hyperthyroidism is comparable with the literature data from community-based studies. In contrast, the prevalence of the spontaneous hypothyroidism due to autoimmune thyroiditis is significantly higher in female and male subgroups of patients with prolactinomas in comparison with the general population. A possible role of supraphysiologically increased prolactin levels in the pathogenesis and the clinical course of AITD in patients with prolactinomas can be suggested. Based on these findings we recommend routine screening for AITD with simple thyroid tests (TSH, TPO-Abs and ultrasound examination) in all patients diagnosed with prolactinoma.

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.

The soluble major histocompatibility complex class I-related chain A protein reduced NKG2D expression on natural killer and T cells from patients with prolactinoma and non-secreting pituitary adenoma.

This study analyses aspects of the immune system in prolactinoma and non-secreting pituitary adenoma. Serum soluble major histocompatibility complex class I-related chain A protein (sMICA) concentrations were measured by enzyme-linked immunosorbent assay. NKG2D-expressing natural killer and T cells were analyzed by flow cytometry. A correlation analysis was also performed to associate sMICA levels with NKG2D expression. The expression of MICA was examined in specific tissues by use of the reverse transcription-polymerase chain reaction. A significant amount of sMICA was detected in the serum of nearly all patients. We found decreased percentage and mean fluorescence intensity of NKG2D-expressing natural killer and T cells from patients with prolactinoma and non-secreting pituitary adenoma compared to those from healthy donors. Pearson analysis showed a negative correlation between sMICA and NKG2D-expressing cells. The immune-escape of pituitary adenoma is related to the down-regulation of NKG2D and the up-regulation of its ligand MICA.

Anti-prolactin (PRL) autoantibodies suppress PRL bioactivity in patients with macroprolactinaemia.

OBJECTIVE: Macroprolactinaemia, mainly caused by anti-prolactin (PRL) autoantibodies, is frequently found in patients with hyperprolactinaemia. Characteristically, these patients lack clinical symptoms of hyperprolactinaemia, but the serum bioactive PRL concentrations in vitro measured by the Nb2 bioassay are usually high. In this study, we investigated the causes of the discrepancy and the true biological features of macroprolactin. SUBJECTS AND METHODS: Sixteen patients with macroprolactinaemia due to anti-PRL autoantibodies were studied. PRL bioactivity was determined by the phosphorylation of signal transducer and activator of transcription (Stat)5 in T47D human breast cancer cells and the proliferation of Nb2 rat lymphoma cells. RESULTS: PRL bioactivity by the T47D bioassay, expressed as the density of the band of phosphorylated Stat5/immunoreactive PRL, was significantly lower in sera containing anti-PRL autoantibodies (2.4 +/- 1.1) than in control sera (7.2 +/- 3.1). Dissociation of PRL from the autoantibodies by acidification resulted in an increase in phosphorylated Stat5. PRL bioactivity by the Nb2 bioassay was not significantly different between sera with and without anti-PRL autoantibodies, and free PRL in the medium gradually increased during the incubation in a time-dependent manner in sera containing anti-PRL autoantibodies. CONCLUSIONS: We conclude that the level of bioactivity of macroprolactin in the Nb2 bioassay is normal due to dissociation of PRL from the autoantibodies as a result of the longer incubation and more dilute assay conditions than in the T47D bioassay. The bioactivity of macroprolactin is low in vivo due to anti-PRL autoantibodies, but monomeric PRL dissociated from the autoantibodies retains full biological activity in patients with macroprolactinaemia.

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.

Immunotherapy of prolactinoma with a T helper 1 activator adjuvant and autoantigens: a case report.

OBJECTIVE: To date, efforts to reliably manipulate the immune system to promote tumor regression in the brain have been disappointing. We report a unique experience of successful immunotherapy to treat a pituitary macroprolactinoma. METHODS: A 31-year-old woman with an established history of pituitary macroprolactinoma who had undergone tumor resection followed by radiation was admitted to our clinic. The diagnosis had been made due to the patient's symptoms, a serum prolactin (PRL) level of 29,600 mIU/l, a brain MRI revealing a 23 x 19 x 18 mm pituitary mass and a positive PRL immunohistochemistry of the mass. Six months following surgery, she reexperienced headache, excessive sweating and a serum PRL concentration of 2,960 mIU/l despite receiving 30 mg/day bromocriptine. Brain MRI revealed a pituitary mass (3 x 6 x 8 mm) compatible with a pituitary adenoma. Twenty micrograms per milliliter of G2 (as a T helper 1 activator adjuvant) was inoculated intradermally once per week for 24 consecutive weeks (each injection contained 10 mug of G2). The autoantigens were inoculated at the same time with G2. RESULTS: After immunotherapy, serum PRL concentration decreased to 82 mIU/l, the patient's symptoms disappeared, skin thickness increased to normal and bromocriptine dosage was tapered to 20 mg per week. A follow-up brain MRI revealed almost complete disappearance of the tumor. The patient does not complain of any problems at 1-year follow-up. CONCLUSION: Activation of both nonspecific (natural killer cells) and specific (cytotoxic T lymphocytes) immunity in relation to the T helper 1 cytokine network is a promising strategy for the treatment of tumors of the central nervous system in humans, especially pituitary macroprolactinomas.

Bacterial endotoxin (lipopolysaccharide) stimulates interleukin-6 production and inhibits growth of pituitary tumour cells expressing the toll-like receptor 4.

Members of the Toll receptor (Tlr) family have a crucial role in the innate immune response following bacterial infection. The effects of Gram-negative bacteria-derived endotoxins (lipopolysaccharide, LPS) are predominantly mediated by Tlr4, and we have recently shown that pituitary folliculostellate cells express functional Tlr4. In the present study, we investigated whether Tlr4 is also present in normal and transformed endocrine epithelial pituitary cell types. By reverse transcriptase-polymerase chain reaction, Tlr4 mRNA expression was found in some pituitary epithelial tumour cell lines (AtT20, HP75), whereas others were negative (GH3, alphaT3-1). Tlr4 protein was detected by immunohistochemistry in a few epithelial cells in normal human anterior pituitaries and in 26 out of 67 human pituitary tumours analysed. LPS had no effect on adrenocorticotropic hormone secretion in Tlr4-positive AtT20 cells, but it suppressed the growth of these cells in a dose-dependent manner. As expected, neither hormone secretion, nor growth of Tlr4-negative GH3 cells was affected by LPS. In cell cultures of Tlr4-positive pituitary adenomas, LPS dose-dependently stimulated the production of interleukin (IL)-6, which is known to induce growth and hormone production in pituitary tumours. The LPS-induced IL-6 production was blocked by the specific p38alphaMAP kinase inhibitor, SB203580, and by the synthetic glucocorticoid, dexamethasone. The data suggest that, during Gram-negative bacteria-induced infections or inflammatory processes, LPS could affect pituitary tumour pathophysiology and progression in the subset of Tlr4-expressing pituitary adenomas.

Expression of Ki-67 antigen in nonfunctioning pituitary adenomas: correlation with growth velocity and invasiveness.

OBJECT: The cell cycle-dependent nuclear antigen Ki-67 is related to growth potential in a variety of tumors. Elevated expression of Ki-67 was previously shown in recurrent pituitary adenomas; however, it has remained unclear whether this expression is related to the growth velocity or invasive behavior of these tumors. The aim of this study was to determine the correlation of Ki-67 antigen expression, growth velocity, and invasiveness in nonfunctioning pituitary adenomas. METHODS: Between April 1998 and April 2002, 23 patients with nonfunctioning pituitary adenomas who had participated in an observation period in which multiple computerized tomography and magnetic resonance imaging studies had been performed were surgically treated in our department. Tumor volumes were assessed using a stereological method based on the Cavalieri principle. The growth rate was calculated for each patient. Expression of Ki-67 antigen was examined using the monoclonal antibody MIB-1. The assessed growth velocity of the adenomas was best described by a linear growth model. The correlation between Ki-67 expression and growth rate was highly significant. Rapidly growing adenomas (> 0.07% daily increase in size) were found to have a Ki-67 labeling index (LI) exceeding 1.5%, whereas all five adenomas with a very slow growth rate (< 0.02% daily increase in size) had a Ki-67 LI lower than 1.5%. No correlation was found between the growth rate and the invasive character of the adenomas. CONCLUSIONS: Expression of Ki-67 antigen is significantly correlated to the growth velocity of pituitary adenomas. Invasive behavior is a feature independent of proliferative activity. The extent of Ki-67 expression is helpful for clinical decision making and routine assessment of Ki-67 is recommended during the histopathological workup of pituitary adenomas.

Integrating systemic information at the molecular level: cross-talk between steroid receptors and cytokine signaling on different target cells.

An essential event in immune activation is the increase of cytokines in both plasma and immune tissues. Steroid hormones influence several adaptive responses in both health and disease. Cytokines and steroids have an intimate cross-communication in many systems, making possible a satisfactory adaptive response to environmental changes. The ultimate level of integration of the cytokine-steroids cross-talk is the molecular level. We have demonstrated this in four types of cross-talk mechanisms on different cells in which steroids have major roles: (1) The tumor necrosis factor (TNF)-glucocorticoid receptor (GR) transcriptional interaction in cellular targets of TNF-induced cytotoxicity. TNF potentiates the transactivation activity of GR and the priming with TNF increases the protective action of GR on TNF-induced cytotoxicity. (2) The GR-T cell receptor (TCR) antagonism in GR-TCR-induced T cell apoptosis and its modulation by cAMP. cAMP inhibits the TCR-induced apoptosis through a PKA-CREB-dependent mechanism and potentiates glucocorticoid-induced apoptosis by means of a CREB-independent mechanism. (3) The GR influence on Th1-Th2 cytokine expression and differentiation. Glucocorticoids inhibit the induction of GATA-3 and T-bet transcription factors. (4) The influence of ER/Smad-4 signaling cross-communication on prolactinoma pathogenesis. Physical and functional interactions between Smad-4 and estrogen receptors take place in prolactinoma cells, providing a molecular explanation to link the tumorigenic action of these two important players of prolactinoma pathogenesis. The molecular cross-talk between steroids and transcription factors is the mechanism that provides the basis for the outcome of adaptive responses integrating the systemic information provided by hormones and cytokines.

Antibodies to pituitary surface antigens during various pituitary disease states.

Autoantibodies to cell surface antigens of human somatotropinoma (ASAS), human prolactinoma (ASAP) and rat adenohypophysis (ASARA) were assayed in the serum of patients with pituitary diseases associated with GH deficiency (GHD), such as pituitary dwarfism and primary empty sella syndrome (ESS), and in the serum of patients with hyperprolactinaemia of different etiologies: idiopathic hyperprolactinaemia, prolactinoma and ESS. The investigation was carried out with a cellular variant of an ELISA. Among children with GHD, the highest percentage of antibody-positive patients was found in the group with idiopathic isolated GHD (89% of ASAS(+) patients and 30% of ASARA(+) patients vs 33.3% and 0% respectively in the group with idiopathic combined pituitary hormone deficiency, and 33.3% and 9% in patients with pituitary hypoplasia associated with isolated GHD or combined pituitary hormone deficiency). Among hyperprolactinaemic patients, the highest ASAP and ASARA frequency was observed in patients with idiopathic hyperprolactinaemia (67.7% and 41.9% respectively) where it was twice as high as in the group of patients with prolactinoma. The proportion of ASAS(+) and ASARA(+) did not differ significantly between the groups of patients with ess with or without GHD. Similarly, there was no significant difference between the number of ESS ASAP(+) and ASARA(+) patients with or without hyperprolactinaemia. The data obtained suggested that autoimmune disorders may be primary, and responsible, at least in part, for pituitary dysfunction in the cases of idiopathic isolated GHD and idiopathic hyperprolactinaemia. At the same time, the autoimmune disorders in the patients with prolactinoma or ESS are probably secondary to the organic pituitary lesion and their significance in the development of the pituitary dysfunction is obscure.

Secretory granules of pituitary adenomas: quantitative study of hormonal antigenicity.

Ultrastructurally, the antigenicity of major pituitary hormones in secretory granules was quantitatively investigated in five growth hormone (GH)-secreting adenomas, five prolactin (PRL)-secreting adenomas and eight clinically non-functioning (CN-F) adenomas. Sparsely granulated cells with a few or several small secretory granules (60-100 nm) exhibiting little or only weak antigenicity of various biochemically unrelated hormones were commonly observed in CN-F adenomas and occasionally in GH- and PRL-secreting adenomas. GH- or PRL-secreting adenomas consisted of many densely granulated cells with medium-sized (200-250 nm) or large (over 250 nm) secretory granules and a few or several sparsely granulated cells with small secretory granules. The densely granulated cells showed intense GH or PRL antigenicity and slight to moderate antigenicity for other hormones in large secretory granules and little or only weak antigenicity for various hormones including GH or PRL in small secretory granules. Their secretory granules larger than 160 nm or 140 nm significantly exhibited intense GH or PRL antigenicity (Fisher's exact test; P < 0.05 and < 0.01, respectively). Two CN-F adenomas showed sparsely and densely granulated cells as well as intermediate cells. The densely granulated cells closely resembled GH-secreting cells. The intermediate cells simultaneously included small and medium-sized or large secretory granules exhibiting little/slight and intense GH-antigenicity, respectively. This study indicates that sparsely granulated cells of different categories showing slight antigenicity for various hormones, antigenically share the same origin, and that their hormonality, single or multiple, may be selectively activated in the developmental course of secretory granules.

Effect of elevated serum prolactin concentrations on the immunophenotype of human lymphocytes, mitogen-induced proliferation and phagocytic activity of polymorphonuclear cells.

It has been suggested that the immune system is an important target tissue of prolactin (PRL). We therefore investigated several immune parameters in nine patients with chronically elevated serum prolactin concentrations. The immunophenotype of lymphocytes, mitogen-induced lymphocyte proliferation and phagocytic activity of polymorphonuclear cells were determined under high serum prolactin levels and 2 weeks after treatment with dopamine agonists. An increased CD4/CD8 ratio in the hyperprolactinaemic patients could be detected compared with healthy control subjects, which remained high after treatment and did not seem to correlate with serum prolactin concentrations. Peripheral blood B lymphocytes showed an increased expression of CD69 in the treated group but not in untreated patients compared with healthy control subjects. Interleukin 2 receptor, CD45RO, transferrin receptor or HLA-DR expression of CD4 or CD8 cells, as well as oxidative burst and phagocytic activity of granulocytes, were not affected in the patients with prolactinomas. Lymphocyte transformation response to phytohaemagglutinin in vitro was found not to be influenced by elevated prolactin levels except at the highest mitogen concentration tested. These data together with previous reports suggest that, although PRL is required for lymphocyte maturation to achieve normal immune function, elevated PRL levels do not lead to an 'overstimulation' of the immune system in men.

Effects of bromocriptine and terguride on cell proliferation and apoptosis in the estrogen-stimulated anterior pituitary gland of the rat.

The effects of bromocriptine and terguride on the estrogen-stimulated anterior pituitary gland of the female Wistar rat were investigated. Pituitary weight and serum prolactin (PRL) levels were reduced by treatment with bromocriptine or terguride. Immunohistological staining for proliferating cell nuclear antigen (PCNA) revealed that the PCNA labeling index of PRL-producing cells was significantly decreased by treatment with bromocriptine or terguride compared with untreated cells. The number of apoptotic cells analyzed by the terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate-biotin nick end labeling method was significantly increased in rats treated with bromocriptine or terguride. Suppression of cell proliferation and induction of apoptosis are important effects of bromocriptine and terguride in the treatment of prolactinomas and other hyperprolactinemias.

Circulating fibroblast growth factor-like autoantibodies in two patients with multiple endocrine neoplasia type 1 and prolactinoma.

Basic fibroblast growth factor (bFGF) is a potent endothelial cell mitogen found in a variety of normal and tumor tissues. bFGF lacks a classical amino-terminal signal sequence and is not readily detectable in plasma from normal subjects. In earlier studies we showed increased bFGF-like mitogenic activity for parathyroid-derived endothelial cells and (increased) bFGF immunoreactivity (0.24-1.28 ng/mL) in plasma of subjects with multiple endocrine neoplasia type 1 (MEN-1). In the present study we examined the proliferative activity of MEN-1 and normal plasmas (applied to protein-A columns) in calf pulmonary artery endothelial cells. Protein-A-eluted activity in plasma from MEN-1 prolactinoma plasma exceeded activity from normal and MEN-1 nonprolactinoma plasma in three of eight MEN-1 subjects with untreated or recurrent prolactinoma. Protein-A-eluted active fractions from MEN-1 prolactinoma plasma had several properties of an immunoglobulin G, including affinity for antihuman immunoglobulin G (IgG) agarose, sensitivity to thiols, and (prepared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions) apparent mol wt corresponding to those of the heavy and light chains of IgG. The IgG fraction of MEN-1 prolactinoma plasma had far more activity in endothelial cells than did optimal concentrations of known growth factors or conditioned medium from prolactinoma cells. Endothelial cell bioactivity in protein-A-eluted fractions from MEN-1 prolactinoma plasma was neutralized 70% by rabbit antibodies to intact bFGF. These results imply novel growth stimulatory bFGF-like autoantibodies in a subset of MEN-1 patients with prolactinoma.

Effect of elevated serum prolactin concentrations on cytokine production and natural killer cell activity.

In vitro and in vivo studies in rodents and human suggested an immunostimulatory effect of prolactin. The aim of the present study was to determine the impact of chronically elevated serum prolactin concentrations on the immune system in patients with prolactinomas. For this purpose parameters of the humoral and cellular immune system were studied in seven patients with prolactinomas on two occasions (1) when their serum prolactin concentration had been normalized through treatment with dopamine agonists and (2) when their serum prolactin concentration was high. Serum concentrations of immunoglobulines, interleukin 1, 3 and 6, TNF-alpha, interferon-gamma and the soluble interleukin 2 receptor, leukocyte subsets and the natural killer cell activity were found to be within the normal range on both occasions, i.e. at normal and at high serum prolactin concentrations. The assumption could be made that long-lasting elevation of serum prolactin concentration induces adaptive changes when the acute stimulatory effects of prolactin on several parameters of the immune system have subsided.