GnRH and GnRH receptors in the pathophysiology of the human female reproductive system

BACKGROUND

Human reproduction depends on an intact hypothalamic-pituitary-gonadal (HPG) axis. Hypothalamic gonadotrophin-releasing hormone (GnRH) has been recognized, since its identification in 1971, as the central regulator of the production and release of the pituitary gonadotrophins that, in turn, regulate the gonadal functions and the production of sex steroids. The characteristic peculiar development, distribution and episodic activity of GnRH-producing neurons have solicited an interdisciplinary interest on the etiopathogenesis of several reproductive diseases. The more recent identification of a GnRH/GnRH receptor (GnRHR) system in both the human endometrium and ovary has widened the spectrum of action of the peptide and of its analogues beyond its hypothalamic function.

METHODS

An analysis of research and review articles published in international journals until June 2015 has been carried out to comprehensively summarize both the well established and the most recent knowledge on the physiopathology of the GnRH system in the central and peripheral control of female reproductive functions and diseases.

RESULTS

This review focuses on the role of GnRH neurons in the control of the reproductive axis. New knowledge is accumulating on the genetic programme that drives GnRH neuron development to ameliorate the diagnosis and treatment of GnRH deficiency and consequent delayed or absent puberty. Moreover, a better understanding of the mechanisms controlling the episodic release of GnRH during the onset of puberty and the ovulatory cycle has enabled the pharmacological use of GnRH itself or its synthetic analogues (agonists and antagonists) to either stimulate or to block the gonadotrophin secretion and modulate the functions of the reproductive axis in several reproductive diseases and in assisted reproduction technology. Several inputs from other neuronal populations, as well as metabolic, somatic and age-related signals, may greatly affect the functions of the GnRH pulse generator during the female lifespan; their modulation may offer new possible strategies for diagnostic and therapeutic interventions. A GnRH/GnRHR system is also expressed in female reproductive tissues (e.g. endometrium and ovary), both in normal and pathological conditions. The expression of this system in the human endometrium and ovary supports its physiological regulatory role in the processes of trophoblast invasion of the maternal endometrium and embryo implantation as well as of follicular development and corpus luteum functions. The GnRH/GnRHR system that is expressed in diseased tissues of the female reproductive tract (both benign and malignant) is at present considered an effective molecular target for the development of novel therapeutic approaches for these pathologies. GnRH agonists are also considered as a promising therapeutic approach to counteract ovarian failure in young female patients undergoing chemotherapy.

CONCLUSIONS

Increasing knowledge about the regulation of GnRH pulsatile release, as well as the therapeutic use of its analogues, offers interesting new perspectives in the diagnosis, treatment and outcome of female reproductive disorders, including tumoral and iatrogenic diseases.

Targeting hormonal signaling pathways in castration resistant prostate cancer

It is now well established that hormonal pathways are involved in the development of prostate cancer towards the castration resistant (CRPC) stage and can be effective molecular targets for novel treatment strategies. Most CRPC are sensitive to androgens and this can be due to the intratumoral production of androgens, androgen receptor (AR) amplification/ mutations and epigenetic modifications of AR expression/signaling. Based on these observations, potent agents targeting the AR axis were developed: 1) inhibitors of CYP17 (a key enzyme in the production of androgens), such as abiraterone and orteronel; 2) AR antagonists that bind to AR and impair AR activation, such as enzalutamide and ARN-509. Moreover, gonadotropin-releasing hormone receptors (GnRH-R), associated with a strong antitumor activity, are expressed in CRPC cells, indicating that they might represent an important target for GnRH analog-based therapeutic strategies. In addition to GnRH agonists and antagonists (i.e., degarelix), cytotoxic GnRH-based bioconjugates, delivering chemotherapeutic drugs to cancer cells expressing the GnRH-R, were developed and reported to exert antitumor effects on CRPC cells; some of them (i.e., AN-152) have already entered clinical trials. This review discusses the most relevant patents and recent observations on the anti-cancer efficacy of novel drugs targeting the AR and the GnRH-R pathways in CRPC.

Neurodevelopmental origin and adult neurogenesis of the neuroendocrine hypothalamus

The adult hypothalamus regulates many physiological functions and homeostatic loops, including growth, feeding and reproduction. In mammals, the hypothalamus derives from the ventral diencephalon where two distinct ventricular proliferative zones have been described. Although a set of transcription factors regulating the hypothalamic development has been identified, the exact molecular mechanisms that drive the differentiation of hypothalamic neural precursor cells (NPCs) toward specific neuroendocrine neuronal subtypes is yet not fully disclosed. Neurogenesis has been also reported in the adult hypothalamus at the level of specific niches located in the ventrolateral region of ventricle wall, where NPCs have been identified as radial glia-like tanycytes. Here we review the molecular and cellular systems proposed to support the neurogenic potential of developing and adult hypothalamic NPCs. We also report new insights on the mechanisms by which adult hypothalamic neurogenesis modulates key functions of this brain region. Finally, we discuss how environmental factors may modulate the adult hypothalamic neurogenic cascade.

Altered expression of 3-betahydroxysterol delta-24-reductase/selective Alzheimer's disease indicator-1 gene in Huntington's disease models

INTRODUCTION

3-betahydroxysterol delta-24-reductase (DHCR24), also called selective Alzheimer's disease indicator-1, is a crucial enzyme in cholesterol biosynthesis with neuroprotective properties that is downregulated in brain areas affected by Alzheimer's disease.

AIM

In the present study, we investigated modifications of DHCR24 expression in models of Huntington's disease (HD), a neurodegenerative disorder caused by a polyglutamine expansion in huntingtin (Htt) protein that induces degeneration of cerebral cortex and striatum as well as lateral hypothalamic abnormality.

METHODS

Basal expression of DHCR24 and its modulation after oxidative stress were evaluated in rat striatal precursors cells (ST14A) transfected with wild-type (Htt) or mutant Htt (mHtt) and in brain tissue of an HD mouse model (R6/2).

RESULTS

The results showed that DHCR24 transcript levels were decreased in ST14A cells expressing mHtt and in the brain of symptomatic R6/2 mice, but were significantly increased in ST14A cells overexpressing wild-type Htt. In addition, we demonstrated that, in the striatal precursors, the decrease of DHCR24 expression in response to oxidative stress was modified according to the presence of Htt or of its mutant form. Preliminary results indicated a modification of DHCR24 expression in post-mortem brain samples of HD patients.

CONCLUSIONS

In conclusion, these results support the hypothesis of a possible role of DHCR24 in HD.

Establishment of a radial glia-like mouse fetal hypothalamic neural stem cell line (AC1) able to differentiate into neuroendocrine cells

The present study describes the generation and the characterization of a stable cell line of neural stem cells derived from embryonic mouse hypothalamus. These cells (AC1) grow as an adherent culture in defined serum-free medium and express typical markers of neurogenic radial glia and of hypothalamic precursors. After prolonged expansion, AC1 cells may be efficiently induced to differentiate into neurons and astroglial cells in vitro and start to express some hormonal neuropeptides, like TRH, CRH, and POMC. Based on the capabilities of AC1 cells to be stably expanded and to develop neuroendocrine lineages in vitro, these cells might represent a novel tool to elucidate the mechanisms involved in the development of the hypothalamus and in the specific differentiation of neuroendocrine neurons.

New insight on the molecular aspects of glucocorticoid effects in nervous system development

Adrenal glucocorticoids (Gc) are among the most significant hormones in the mammalian organisms; these steroids may reach and penetrate all tissues where they interact with cytoplasmic/nuclear receptors, through which they exert multiple and very multifaceted actions. The effects of physiological concentrations of Gc on brain functions have not been completely clarified, even though Gc are recognized to influence behavioral responses, emotions, cognitive processes and to take part in the neuroendocrine control of body homeostasis. Developmental programming effects of Gc in animal models and humans have been proposed. Actually, pre-natal stress, or exposure to high Gc levels, would somehow affect neuronal developmental events in some structure and this can lead to central nervous system altered functions, as the impairment of neuroendocrine activities, cognitive processes, sleep and mood disorders. Interestingly, it has been observed that these abnormalities may not be limited to the first directly exposed individuals but transmissible across generations. The establishment of animal models with localized pre-natal glucocorticoid receptors deficiency led to the accumulation of data on the possible roles of these hormones on development of the central and peripheral nervous system. The most recent findings on the effects of Gc on neuroblast development, with particular attention to neuronal migration, will be presented.

Licit and illicit drugs in a wastewater treatment plant in Verona, Italy

The occurrence of 12 active substances among licit and illicit drugs was investigated over a 2 week period inflowing and outflowing in an activated sludge wastewater treatment plant in the city of Verona, Northern Italy. Chemical analyses were performed by means of on-line solid phase extraction coupled to high performance liquid chromatography-tandem mass spectrometry in order to minimize sample pre-treatment. Quantifiable concentrations, up to hundreds of ng/L, were detected in influent and in effluent only for carbamazepine, codeine and benzoylecgonine. Such values are in accordance with literature data, so as removal efficiencies: it was observed that there was pretty much no abatement for carbamazepine, while average removal percentages of about 60% and 90% were calculated for codeine and benzoylecgonine, respectively. These results provide useful information (also concerning some active principles never or rarely detected, up to now, such as lormetazepam) for integrated water cycle managing, also taking into account the specific characteristics of the receiving water basin.

Abstract P3-10-03: Bartonella henselae Infection Detected in Patients with Inflammatory Breast Cancer

Inflammatory breast cancer (IBC) is a very aggressive type of advanced breast cancer with a poor prognosis. Clinical symptoms involve a rapid onset of changes in the skin overlying the breast, including edema, redness and swelling including a wrinkled and orange peel appearance in the skin. This particular presentation is due to the invasion of the skin dermal lymphatics by breast cancer cells that obstructed the lymph channels producing the characteristic skin changes that mimic an inflammatory process. Mouse Mammary Tumor-associated Virus (MMTV) and other infectious agents have been consider as possible etiological agents of IBC particularly related to the initial description of higher incidence in women living in rural areas in North Africa. Although, the etiopathological role of bacteria in this disease has never been explored in spite of the evidence that chronic infections with certain bacteria can facilitate tumors development.

Several bacterial infections promote cell proliferation and could increase the rate of cell transformation. Bartonella spp. is an emerging pathogen that can cause conditions which are characterized by the development of proliferative lesions. Bartonella might cause vasculoproliferative disorders by triggering the proliferation of endothelial cells and inducing the secretion of proliferative cytokines from infected host cells. It cause persistent infection of erythrocytes and endothelial cells in their mammalian hosts and their transmission occur mainly by blood-sucking arthropods. Bartonella are Gram-negative bacteria usually associated with cat-scratch disease, urban trench fever, bacillary angiomatosis-peliosis and endocarditis. Some reports have showed some similarities between cat scratch disease and inflammatory breast cancer (Povoski et al., Breast J 9: 497–500, 2003).

Methods and Results: In the present work, we report the identification of Bartonella henselae in the pleural effusions of two patients with IBC. These patients had both estrogen-receptor negative (ER−) and progesterone-receptor negative (PR−) disease and have failed a number of previous chemotherapy regimens. Furthermore, they had metastatic disease to the pleura, skin, lymph nodes and lung. Cells from the pleural fluids of these patients stained positive for Bartonella sp. using the Warthin-Starry staining kit. Moreover, we used PCR and sequencing of the 16S–23S intergenic spacer (ITS) region to identify the etiological agent as Bartonella henselae. By immunofluorescence using an antibody that specifically recognized Bartonella henselae, the bacteria were found in the nucleus of IBC tumor cells confirming the infection and their intracellular localization.

Conclusions: These results suggested that bacteria infections such as the one produced by Bartonella henselae might contribute to the clinical and pathological characteristics of IBC, associated with rapid spread of the breast tumor cells through the lymphatic system. The infection and activation of endothelial lymphatics by Bartonella might contribute to the highly metastatic process observed in IBC patients. An acute inflammatory reaction triggered by the Bartonella infected endothelium may be crucial for initiating the chronic inflammation in IBC patients and the rapid spread of tumor cells.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-10-03.

Bartonella spp. DNA in cardiac tissues from dogs in Colorado and Wyoming

BACKGROUND

Several Bartonella species (spp.) have been identified in dogs diagnosed with infectious endocarditis (IE) or myocarditis.

OBJECTIVE

To interrogate cardiac tissues of dogs with suspected IE for the presence of Bartonella spp. DNA of dogs in the Rocky Mountain states.

ANIMALS

Nine dogs with a clinical diagnosis of endocarditis from January 1990 to June 2008 were included.

METHODS

In this retrospective study, medical records at the Veterinary Teaching Hospital were searched. Animals were excluded if there was no diagnosis of IE in the original necropsy report. Paraffin embedded tissue blocks and medical records were available from 9 dogs. Total DNA was extracted from the cardiac tissues and assessed for Bartonella spp. DNA by 3 polymerase chain reaction (PCR) methods. For positive samples, the Bartonella spp. were determined by genetic sequencing or fluorogenic real-time PCR.

RESULTS

Bartonella henselae DNA was amplified from the tissues of 7 dogs; Bartonella vinsonii subsp berkhoffii DNA was amplified concurrently from 3 dogs. Six dogs were from Colorado and 1 was from Wyoming. Flea or tick infestations were reported in 2 dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Bartonella spp. should be on the differential list for dogs in the Rocky Mountain states. The results emphasize the need for routine use of external parasite control products even in regions perceived to have low risk for flea and tick infestations.

Effect of clinical triggers on positive responses to tilt-table testing potentiated with nitroglycerin or clomipramine

The effect of clinical triggers on tilt-table testing (TTT) responses has not been systematically evaluated. In the present study, we evaluated the effect of clinical triggers on positive responses to TTT potentiated with nitroglycerin (which acts mainly through peripheral dilation) or clomipramine (which acts mainly through a central serotoninergic mechanism). We enrolled 380 consecutive adult patients. In 66 patients, syncope was triggered by emotional distress (central trigger), in 161 by specific situations or prolonged standing (peripheral trigger), and in 153 syncope occurred in the absence of any detectable trigger. Nitroglycerin TTT, performed in 252 patients, consisted of a passive phase of 20 minutes followed, if negative, by sublingual administration of 400 μg nitroglycerin spray and continuation of tilting for 15 minutes. Clomipramine TTT, performed in 128 patients, consisted of 20 minutes of tilting with intravenous administration of 5 mg clomipramine during the first 5 minutes. The positivity of nitroglycerin TTT was greater in patients with clinical triggers (71% central and 75% peripheral) than in those without (36%). With clomipramine TTT, the positivity rate was greater in patients with central triggers (92%) than in those with peripheral triggers (45%) or no triggers (30%). The cardioinhibitory form was more frequent in patients with a central trigger than in the other 2 groups (34% vs 12% and 7%) and with clomipramine TTT than with nitroglycerin TTT (19% vs 11%, respectively). In contrast, mixed or vasodepressor forms were more frequently induced by nitroglycerin TTT (41% vs 24%). In conclusion, the presence of clinical triggers increased the positivity of TTT and influenced the type of response. We found some specificity of nitroglycerin and clomipramine for peripheral and central mechanisms.

Discrepancy between clinical practice and standardized indications for an implantable loop recorder in patients with unexplained syncope

Aim

An implantable loop recorder (ILR) is indicated in patients with unexplained syncope after complete conventional work-up. Data from the literature imply that, in clinical practice, the ILR is underused. The aim of the study was to verify if there is any discrepancy between the use of ILRs in clinical practice and the potential indications based on the most potentially appropriate guideline indications.

Method and results

We compared the prevalence of ILRs actually implanted in patients with unexplained syncope in the Syncope Unit Project (SUP) study and the potential one using the standard given by the guidelines. In the SUP study, 28 (18%) out of 159 patients with unexplained syncope received an ILR. Appropriate criteria for implantation of ILRs according to guidelines were present in 110 (69%) patients. Moreover, 7 (25%) of ILRs actually implanted did not satisfy the guideline standards. During the follow-up, 32% of patients who had received an ILR had a diagnosis compared with 5% of those who did not (P= 0.001).

Conclusions

The estimated indications were four times higher than those observed. Moreover, in about one quarter of the cases, the use of ILRs proved to be potentially inappropriate according to guideline indications. Two-thirds of patients with unexplained syncope had indications potentially appropriate for ILRs.

Defective gonadotropin-releasing hormone neuron migration in mice lacking SEMA3A signalling through NRP1 and NRP2: implications for the aetiology of hypogonadotropic hypogonadism

Kallmann syndrome (KS) is a genetic disease characterized by hypogonadotropic hypogonadism and impaired sense of smell. The genetic causes underlying this syndrome are still largely unknown, but are thought to be due to a developmental defect in the migration of gonadotropin-releasing hormone (GnRH) neurons. Understanding the causes of the disease is hampered by lack of appropriate mouse models. GnRH neurons are hypothalamic cells that centrally control reproduction in mammals by secreting the GnRH decapeptide into the portal blood vessels of the pituitary to stimulate the production of gonadotropins. During development, these cells are born in the nasal placode outside the brain and migrate in association with olfactory/vomeronasal axons to reach the forebrain and position themselves in the hypothalamus. By combining the analysis of genetically altered mice with in vitro models, we demonstrate here that a secreted guidance cue of the class 3 semaphorin family, SEMA3A, is essential for the development of the GnRH neuron system: loss of SEMA3A signalling alters the targeting of vomeronasal nerves and the migration of GnRH neurons into the brain, resulting in reduced gonadal size. We found that SEMA3A signals redundantly through both its classical receptors neuropilin (NRP) 1 and, unconventionally, NRP2, while the usual NRP2 ligand SEMA3F is dispensable for this process. Strikingly, mice lacking SEMA3A or semaphorin signalling through both NRP1 and NRP2 recapitulate the anatomical features of a single case of KS analysed so far, and may therefore be used as genetic models to elucidate the pathogenesis of KS.

Radiographic findings among children hospitalized with severe community-acquired pneumonia

BACKGROUND

Community-acquired pneumonia (CAP) is a leading cause of childhood death. There are few published reports of radiographic findings among children with severe CAP.

OBJECTIVE

To describe chest X-ray (CXR) findings and assess association between these radiographic findings and pneumococcal isolation in children with severe CAP.

METHODS

A prospective, multicenter, observational study was conducted in 12 centers in Argentina, Brazil, and the Dominican Republic. Children aged 3-59 months, hospitalized with severe pneumonia, were included. On admission, blood and pleural effusion cultures were performed. Streptococcus pneumoniae was identified according to standard procedures in the respective national reference laboratory. Chest X-rays were taken on admission and read before the culture results were reported.

RESULTS

Out of 2,536 enrolled patients, 283 (11.2%) had S. pneumoniae isolated, in 181 cases (7.1%) from blood. The follow radiographic patterns were observed: alveolar infiltrate (75.2%), pleural effusion (15.6%), and interstitial infiltrate (9.2%). Overall, pleural effusion was associated with pneumococcal isolation and pneumococcal bacteremia (P < 0.001). Infiltrates were unilateral (78.7%) or bilateral (21.3%), right-sided (76%) or left-sided (24%), in the lower lobe (53.6%) or the upper lobe (46.4%). Multivariate analysis including patients with affection of only one lobe showed that upper lobe affection and pleural effusion were associated with pneumococcal isolation (OR 1.8, 95% CI, 1.3-2.7; OR 11.0, 95% CI, 4.6-26.8, respectively) and with pneumococcal bacteremia (OR 1.7, 95% CI, 1.2-2.6; OR 3.1, 95% CI, 1.2-8.0, respectively).

CONCLUSIONS

Three-quarters of the patients studied had alveolar infiltrates. Upper lobe compromising and pleural effusion were associated with pneumococcal invasive disease.