Pituitary Growth Research Articles

Combination of macro-TSH and macroprolactinemia phenomena in a patient with autoimmune thyroiditis and vitiligo

Laboratory diagnostic methods are the main tools in the practice of a doctor of any specialty, including an endocrinologist. Factors were identified that could change the concentration of the biologically active fraction of the test substance, subsequently complicating the interpretation of laboratory results and making the right clinical decision. The literature describes a variety of circulating autoantibodies involved in binding to pituitary hormones (prolactin (PRL), thyroid-stimulating hormone (TSH), growth hormone, luteinizing, follicle-stimulating, and adrenocorticotropic hormones), hypothalamus (vasopressin and oxytocin), pancreas (insulin and glucagon) , parathyroid glands (parathyroid hormone), as well as with thyroid hormones. As a rule, the resulting macromolecules lead to an increase in laboratory parameters, in which the prevailing fraction of the hormone does not have biological activity, which determines the main problem of this phenomenon. The most common variants include immune complexes with PRL and TSH, causing the phenomena of macroprolactinemia and macrothyrotropinemia (macro-TSH-emia/macro-TSH), respectively. Most laboratory test systems used in clinical practice are capable of determining only the total amount of PRL and TSH. The presented clinical observation describes a combination of the phenomena of macro-TSH and macroprolactinemia in a patient with autoimmune thyroiditis (AIT) and vitiligo.

6469 Supplement Misadventures: A Case Of Acute Heart Failure, Cardiogenic Shock, And Hormonal Dysregulation Secondary To Surreptitious Use Of Multiple Hormonal Supplements

Abstract Disclosure: K.N. Grennan: None. S. Thota-Kammili: None. A.L. McKenna: None. C.G. Coyle: None. S.L. Samson: None. Introduction: Supplement misuse in the bodybuilding community is prevalent. With the availability of internet ordering and purchasing, patients have access to hormonal supplements without prescription or regulation. Here we present the case of a patient on self-administered hormonal supplements who presented in acute heart failure leading to cardiogenic shock in the setting of concurrent thyroid, adrenal, and gonadal axis dysfunction. Case Description: A 28-year-old male with no significant medical history was transferred to our hospital after presenting to an outside emergency room with dyspnea, cough, nausea, and a subjective fever. He developed acute hypoxic respiratory failure requiring intubation. Echocardiogram performed showed an ejection fraction (EF) of 10%. He was started on two vasopressors and methylprednisolone 1 g daily for two days, due to concern for myocarditis versus giant cell arteritis. Hormonal work-up showed TSH 0.02 mIU/L (normal range 0.3-4.2), free T4 0.4 ng/dL (0.9-1.7), total T3 48 ng/dL (80-200), FSH <0.3 IU/L (1.2-15.8), LH <0.2 IU/L (1.3-9.6), ACTH <5.0 pg/mL (7.2-63), cortisol 1.7 mcg/dL (2.5-12), estradiol 171 pg/mL (8.0-35), total testosterone 1730 ng/dL (240-950), and prolactin 47 ng/mL (4.0-15.2). He received 10 mg dexamethasone at the outside facility. A medication bag found by his family included online purchases of non-prescribed testosterone cypionate and enanthate, liothyronine, anastrozole, and clomiphene. None were medical grade. He was also taking the anabolic steroid clenbuterol for 3 days prior. Echocardiogram on day 3 of admission showed an improved EF of 36%. Cardiac magnetic resonance imaging (MRI) showed a papillary fibroelastoma and myocarditis. Patient was weaned off vasopressors and the ventilator. He was discharged on levothyroxine 50 mcg daily and hydrocortisone 10 mg twice daily for outpatient reassessment. Transesophageal echocardiogram confirmed diagnosis of papillary fibroelastoma. One month Endocrinology clinic follow-up showed no evidence of posterior pituitary, thyroid, or adrenal axis dysfunction or growth hormone excess, but he continued to have gonadal axis suppression with elevated prolactin and estradiol, the latter thought to be secondary to conversion from testosterone. Pituitary MRI showed no micro or macroadenoma. His EF recovered to 50%. He is pending surgical removal of the aortic valve fibroelastoma. Discussion: With hormonal supplements easily accessible online, it is important for physicians to counsel patients about the dangers of misuse. This case highlights a previously healthy 28-year-old man who presented in critical condition with cardiogenic shock and hypothalamic-pituitary axis dysfunction from supplements he purchased online. There should be targeted educational interventions regarding the harm of supplements aimed at the bodybuilding community to prevent similar cases. Presentation: 6/2/2024

7559 TRIM21 Regulates Activation of ERK1/2 to Promote Growth and Drug Resistance in Pituitary Neuroendocrine Tumors

Abstract Disclosure: Y. Liu: None. F. Liu: None. C. Li: None. T. Zhang: None. L. Xue: None. Z. Wu: None. Objective: To investigate the role of the TRIM family genes in pituitary neuroendocrine tumors (PitNETs) and provide new targets and strategies for the clinical treatment of these tumors. Methods: A CRISPR screening system targeting the TRIM family was constructed and validated using next-generation sequencing. Stable cell lines overexpressing or knocking out TRIM21 were generated, and functional validation was performed using assays such as CCK-8, colony formation, and xenograft tumor growth in nude mice. RNA-seq, mass spectrometry, immunohistochemistry, and immunoblotting were employed to explore the signaling pathways and mechanisms underlying TRIM21's actions. Immunoprecipitation, immunofluorescence, GST-pulldown, NanoBiT assays, and ubiquitination experiments were conducted to investigate the effects of TRIM21 on ERK1/2. Immunohistochemistry and immunoblotting were used to explore the role of TRIM21 in drug- resistant prolactinomas and the correlation between TRIM21 and p-ERK. Results: Through screening the proliferative and drug-resistant effects of the TRIM family in MMQ and GH3 cells, we found that knocking out TRIM21 may inhibit cell growth and enhance drug sensitivity. Subsequently, stable cell lines overexpressing or knocking out TRIM21 were generated in MMQ and GH3 cells, revealing that TRIM21 overexpression promotes pituitary tumor cell growth and resistance to drug treatment, while TRIM21 knockout inhibits cell growth and enhances drug sensitivity. Cell-derived xenograft models showed that TRIM21 overexpression promoted growth of GH3 cells in vivo and resistance to cabergoline (CAB), while TRIM21 knockout suppressed growth of MMQ cells in vivo. Further exploration of the signaling pathways influenced by TRIM21 revealed that TRIM21 knockout downregulates the MAPK signaling pathway, while TRIM21 overexpression upregulates it. TRIM21 overexpression upregulates p-ERK1/2 in the MAPK pathway, while TRIM21 knockout decreases p-ERK. However, there is no significant influence on ERK1/2, JNK, p-JNK, p38, or p-p38. Mechanically, TRIM21 interacted with ERK1/2, enhancing the K27-linked ubiquitination of ERK1/2 and promoting their interaction with MEK1/2. In addition, the TRIM21 with D-docking mutant or ERK1/2 with CD-domain mutant resulted in the loss of their interaction. Furthermore, TRIM21 and p-ERK levels were significantly elevated in drug-resistant prolactinomas and immunohistochemical semi-quantitative analysis demonstrated a positive correlation between TRIM21 and p-ERK. Conclusion: The ubiquitin ligase TRIM21 catalyzes K27-linked ubiquitination of ERK1/2, enhancing its interaction with MEK1/2 and activation, thereby promoting growth and drug resistance in pituitary neuroendocrine tumors. TRIM21 may serve as a potential target for the treatment of pituitary neuroendocrine tumors. Presentation: 6/3/2024

Paracrine FGF1 signaling directs pituitary architecture and size

Organ architecture is established during development through intricate cell-cell communication mechanisms, yet the specific signals mediating these communications often remain elusive. Here, we used the anterior pituitary gland that harbors different interdigitated hormone-secreting homotypic cell networks to dissect cell-cell communication mechanisms operating during late development. We show that blocking differentiation of corticotrope cells leads to pituitary hypoplasia with a major effect on somatotrope cells that directly contact corticotropes. Gene knockout of the corticotrope-restricted transcription factor Tpit results in fewer somatotropes, with less secretory granules and a loss of cell polarity, resulting in systemic growth retardation. Single-cell transcriptomic analyses identified FGF1 as a corticotrope-specific Tpit dosage-dependent target gene responsible for these phenotypes. Consistently, genetic ablation of FGF1 in mice phenocopies pituitary hypoplasia and growth impairment observed in Tpit-deficient mice. These findings reveal FGF1 produced by the corticotrope cell network as an essential paracrine signaling molecule participating in pituitary architecture and size.

Targeting HTR2B suppresses nonfunctioning pituitary adenoma growth and sensitizes cabergoline treatment via inhibiting Gαq/PLC/PKCγ/STAT3 axis.

Managing nonfunctioning pituitary adenomas (NFPAs) is difficult due to limited drug treatments. Cabergoline's (CAB) effectiveness for NFPAs is debated. This study explores the role of HTR2B in NFPAs and its therapeutic potential. We conducted screening of bulk RNA-sequencing data to analyze HTR2B expression levels in NFPA samples. In vitro and in vivo experiments were performed to evaluate the effects of HTR2B modulation on tumor growth and cell cycle regulation. Mechanistic insights into the HTR2B-mediated signaling pathway were elucidated using pharmacological inhibitors and molecular interaction assays. Elevated HTR2B expression was detected in NFPA samples, which was associated with increased tumor survival. Inhibition of HTR2B activity resulted in the suppression of tumor growth through modulation of the G2M cell cycle. The inhibition of HTR2B with PRX-08066 was found to block STAT3 phosphorylation and nuclear translocation by interfering with the Gαq/PLC/PKC pathway. A direct interaction between PKC-γ and STAT3 was critical for STAT3 activation. CAB was shown to activate pSTAT3 via HTR2B, reducing its therapeutic potential. However, the combination of an HTR2B antagonist with CAB significantly inhibited tumor cell proliferation in HTR2B-expressing pituitary tumor cell lines, a xenografted pituitary tumor model, and patient-derived samples. Analysis of patient-derived data indicated that a distinct molecular pattern characterized by upregulated HTR2B/PKC-γ and downregulated BTG2/GADD45A may benefit from combination treatment with CAB and PRX-08066. HTR2B is a potential therapeutic target for NFPAs, and its inhibition could improve CAB efficacy. A dual therapy approach may be beneficial for NFPA patients with high HTR2B expression.

Skin assessment in congenital untreated isolated GH deficiency.

The separation between the inside and outside through the skin was fundamental for the evolution of prevertebrates, which grow through extrapituitary circuits, to vertebrates, which grow through the somatotrophic axis, namely pituitary growth hormone (GH). and circulating IGF1.Individuals with untreated isolated growth hormone (GH) deficiency (IGHD) due to a mutation in the GH-releasing hormone receptor (GHRH) gene, residing in Itabaianinha, Brazil, are vulnerable to skin cancer and have reduced sweating. However other aspects of their skin physiology are still unknown. Our objectives were to evaluate the number of skin cancers, skin aging, and functional aspects of the skin in this IGHD cohort. Twenty-six IGHD individuals and 26 controls matched by age, sex, ethnicity, and occupation were submitted to a biochemical, dermatological and a functional skin assessment by the Multi Probe Adapter Cutometer® MPA 580. There was no difference in the number of skin cancers and in the degrees of photodamage between the groups. The melanin content in the forearm was similar between the groups but was lower in the buttocks (p = 0.005), as well as skin resistance (p < 0.0001) and elasticity (p = 0.003), lower in the IGHD. There was no difference in hydration and sebum content between the two groups. IGHD is apparently associated with a neutral profile in terms of skin cancer and photodamage, with similar melanin on the forearm and lower buttocks, lower skin resistance and elasticity, with hydration and sebum similar to controls.

Multigrade brain tumor classification in MRI images using Fine tuned efficientnet

Medical imaging plays a vital role in detecting and treating brain tumors. Malignant or non-malignant brain tissue’s abnormal growth causes long-term brain damage. It is crucial to detect and properly categorize the kind of brain tumor. Specialists normally use MRI to create high-contrast grayscale brain images to segment them. Convolutional neural networks (CNN) driven by deep learning (DL) have transformed computer-assisted testing systems by producing good results in a wide range of medical imaging analytics applications, including tumor diagnosis in the brain. The paper introduces a lightweight fine-tuned Convolutional Neural Network EfficientNet ’ECNN’ to detect brain tumors. In this study, we provide a transfer learning-based measurement strategy for grouping cerebrum growths in three distinct datasets with different classifications, such as meningioma, glioma, and pituitary growth, using fine-tuned EfficientNets. The findings of this research rely on Efficient Nets to classify brain tumors in three different types of datasets utilizing a fine-tuned transfer learning mechanism. With EfficientNetV2S as the system’s foundation, our proposed way of fine-tunned pre-trained EfficientNetV2S model outperformed for all datasets over state of the art methods. The effectiveness of the suggested model has been assessed using performance metrics, and outcomes were compared to those produced using state-of-the-art approaches. The average test accuracy, recall, precision, and sensitivity score are 98.48%, 98%, 98.5%, and 98.71%, respectively.

IGFBP1a is a nutrient deficient response factor that can inhibit fish reproduction through the hypothalamus-pituitary-ovary axis†.

Reproduction is a high energy consuming process, so long-term malnutrition can significantly inhibit gonadal development. However, little is known about the molecular mechanism by which fasting inhibits reproduction. Our present study found that fasting could dramatically induce insulin-like growth factor binding protein 1 (IGFBP1) expression in the liver, hypothalamus, pituitary and ovaries of grass carp. In addition, IGFBP1a in the hypothalamus-pituitary-gonad axis could inhibit the development of gonads. These results indicated that fasting may participate in the regulation of fish gonadal development through the mediation of IGFBP1a. Further studies found that IGFBP1a could markedly inhibit gonadotropin-releasing hormone 3 expressions in hypothalamus cells. At the pituitary level, IGFBP1a could significantly reduce the gonadotropin hormones (LH and FSH) expression by blocking the action of pituitary insulin-like growth factor 1. Interestingly, IGFBP1a could also directly inhibit the expression of lhr, fshr, and sex steroid hormone synthase genes (cyp11a, cyp17a, and cyp19a1) in the ovary. These results indicated that IGFBP1a should be a nutrient deficient response factor that could inhibit fish reproduction through the hypothalamus-pituitary-ovary axis.

The Treatment of Growth Disorders in Childhood and Adolescence.

3% of all children are unusually short, and 3% are unusually tall. New approaches have broadened the range of therapeutic options in treating growth disorders. This review is based on publications retrieved by a selective review of the literature and on the authors' clinical experience. Pituitary growth hormone deficiency is treated with recombinant growth hormone. Long-acting preparations of this type became available recently, but their long-term safety and efficacy are still unknown. Vosoritide, a CNP analogue, has also been approved for the treatment of achondroplasia, and severe primary deficiency of insulin-like growth factor 1 (IGF-1) can be treated with recombinant IGF-1. In the treatment of excessively tall stature, new information on the safety of growth-attenuating treatment and an altered perception of above-average height in society have led to a change in management. There are new options for the treatment of rare causes of short stature, while new information on the safety of treatment strategies for excessive tallness have led to a reconsideration of surgical intervention. There is insufficient evidence on the benefits and risks of supraphysiological GH therapy and of newer treatment options for which there are as yet no robust data on adult height. Therefore, before any treatment is provided, physicians should give patients and their families detailed information and discuss their expectations from treatment and the goals that treatment can be expected to achieve.

Clinical Characteristics and Management of Cosecreting Thyroid Stimulating Hormone or Prolactin Pituitary Growth Hormone Adenomas: A Case-Control Study

ObjectiveCosecreting thyroid stimulating hormone (TSH) or prolactin (PRL) in patients with pituitary growth hormone (GH) adenomas has been rarely reported. Our study aimed to elucidate their clinical characteristics. MethodsWe retrospectively collected data of 22 cases of cosecreting GH and TSH pituitary adenomas [(GH+TSH)oma] and 10 cases of cosecreting GH and PRL pituitary adenomas [(GH+PRL)oma] from Beijing Tiantan Hospital, Capital Medical University between January 2009 and January 2023. The clinical manifestation, preoperative hormone levels, imaging features, pathologic characteristics, and biochemical remission rates were compared among 335 patients with solo-secreting GH adenomas (GHoma) and 49 patients with solo-secreting TSH adenoma (TSHoma). Patients with (GH+TSH)oma and (GH+PRL)oma were grouped according to biochemical remission to explore the risk factors leading to biochemical nonremission. ResultsCosecreting pituitary GH adenomas had various clinical manifestations and a larger tumor volume and were more likely to invade the cavernous sinus bilaterally and compress the optic chiasm. GH and TSH levels were lower in (GH+TSH)oma than in GHoma or TSHoma. Solo part remission was observed both in (GH+TSH)oma and (GH+PRL)oma. Cavernous sinus invasion was an independent risk factor for biochemical nonremission in patients with (GH+TSH)oma and (GH+PRL)oma. ConclusionsThe clinical manifestation of (GH+TSH)oma and (GH+PRL)oma may be atypical. When screening for pituitary adenomas, a comprehensive evaluation of all pituitary target gland hormones is needed. Cosecreting pituitary GH adenomas are more aggressive and surgery is often unable to completely remove the tumor, requiring pharmacologic or radiological treatment if necessary. Clinicians should give high priority to biochemical remission, although solo part remission may occur.

Iatrogenic Alzheimer’s disease in recipients of cadaveric pituitary-derived growth hormone

Alzheimer’s disease (AD) is characterized pathologically by amyloid-beta (Aβ) deposition in brain parenchyma and blood vessels (as cerebral amyloid angiopathy (CAA)) and by neurofibrillary tangles of hyperphosphorylated tau. Compelling genetic and biomarker evidence supports Aβ as the root cause of AD. We previously reported human transmission of Aβ pathology and CAA in relatively young adults who had died of iatrogenic Creutzfeldt–Jakob disease (iCJD) after childhood treatment with cadaver-derived pituitary growth hormone (c-hGH) contaminated with both CJD prions and Aβ seeds. This raised the possibility that c-hGH recipients who did not die from iCJD may eventually develop AD. Here we describe recipients who developed dementia and biomarker changes within the phenotypic spectrum of AD, suggesting that AD, like CJD, has environmentally acquired (iatrogenic) forms as well as late-onset sporadic and early-onset inherited forms. Although iatrogenic AD may be rare, and there is no suggestion that Aβ can be transmitted between individuals in activities of daily life, its recognition emphasizes the need to review measures to prevent accidental transmissions via other medical and surgical procedures. As propagating Aβ assemblies may exhibit structural diversity akin to conventional prions, it is possible that therapeutic strategies targeting disease-related assemblies may lead to selection of minor components and development of resistance.

Connexin 36 Mediated Intercellular Endoplasmic Reticulum Stress Transmission Induces SSTA Resistance in Growth Hormone Pituitary Adenoma.

Somatostatin analogues (SSTA) are first-line pharmacological treatment choice for acromegaly, which received satisfying tumor shrinkage and normalization of growth hormone. However, there are still patients unresponsive to SSTA, and the underline mechanism remains unknown. Besides, there is no evidence regarding the role of endoplasmic reticulum stress (ERS) and its transmission in SSTA resistance, which also require investigation. Primary growth hormone adenoma cells and cell lines were treated with SSTA; autophagy double-labeled LC3 (mRFP-GFP) adenovirus transfection, flow cytometry sorting, western blotting, calcium imaging as well as immunofluorescence staining were used to determine ERS and autophagy signal transmission; xenograft and syngeneic tumor in vivo model were exploited to confirm the ERS signal transmission mediated effect. Our results revealed that SSTA induces ERS in pituitary growth hormone (GH) adenoma cells. The ERS signals can be intercellularly transmitted, leading to less responsible to SSTA treatment. Moreover, SSTA stimulates inositol triphosphate (IP3) elevation, mediating ERS intercellular transfer. In addition, connexin 36 tunnels ERS transmission, and its blocker, Quinine, exhibits a synergistic effect with SSTA treating GH adenoma. Our study provided insight into ERS intercellular transmission mediated SSTA resistance, which could be translated into clinical usage to improve SSTA efficiency in GH adenoma treatment.

Corticosteroid-Binding Globulin (SERPINA6) Consolidates Sexual Dimorphism of Adult Rat Liver.

Produced by the liver, corticosteroid-binding globulin (CBG) regulates the plasma distribution and actions of glucocorticoids. A sex difference in pituitary growth hormone secretion patterns established during puberty in rats results in increased hepatic CBG production and 2-fold higher plasma corticosterone levels in females. Glucocorticoids control hepatic development and metabolic activities, and we have therefore examined how disrupting the SerpinA6 gene encoding CBG influences plasma corticosterone dynamics, as well as liver gene expression in male and female rats before and after puberty. Comparisons of corticosterone plasma clearance and hepatic uptake in adult rats, with or without CBG, indicated that CBG limits corticosterone clearance by reducing its hepatic uptake. Hepatic transcriptomic profiling revealed minor sex differences (207 differentially expressed genes) and minimal effect of CBG deficiency in 30-day-old rats before puberty. While liver transcriptomes in 60-day-old males lacking CBG remained essentially unchanged, 2710 genes were differentially expressed in wild-type female vs male livers at this age. Importantly, ∼10% of these genes lost their sexually dimorphic expression in adult females lacking CBG, including those related to cholesterol biosynthesis, inflammation, and lipid and amino acid catabolism. Another 203 genes were altered by the loss of CBG specifically in adult females, including those related to xenobiotic metabolism, circadian rhythm, and gluconeogenesis. Our findings reveal that CBG consolidates the sexual dimorphism of the rat liver initiated by sex differences in growth hormone secretion patterns and provide insight into how CBG deficiencies are linked to glucocorticoid-dependent diseases.

Anomalies du récepteur de l’hormone de croissance hypophysaire et de son effecteur de l’axe somatotrope, l’Insulin-Like Growth Factor I

Postnatal statural growth is under the hormonal control of the somatotropic axis: hypothalamus-pituitary-liver-bone. Numerous gene abnormalities have been described, located at the hypothalamus and especially at the pituitary levels. Rarer damages are located downstream at the level of the pituitary growth hormone (GH) receptor, as in Laron's syndrome or in post-receptor signaling, Stat5b or the terminal effector of growth, the Insulin-Like Growth Factor I (IGF I). For several decades now, these severe statural growth retardations can benefit from recombinant IGF I treatment, with variable efficacy depending on the genetic abnormality.

THU044 The Subcellular Localization Of β-Catenin Is Associated With Tumor Size And The Surgical Remission Rate In Growth Hormone-producing Pituitary Adenomas

Abstract Disclosure: S. Kuwabara: None. H. Kameda: None. H. Nomoto: None. K. Cho: None. A. Nakamura: None. Y. Ishi: None. H. Motegi: None. F. Miki: None. H. Miyoshi: None. T. Atsumi: None. The Wnt/β-catenin pathway is the best understood Wnt signaling pathway and controls cell proliferation. In the presence of Wnt, the translocation of β-catenin from the cytoplasm to the nucleus leads to pathway activation. It has been reported that the nuclear accumulation of β-catenin is associated with Ki-67 expression in pituitary adenomas and that the invasiveness of growth hormone (GH)-producing pituitary adenomas is associated with β-catenin expression. We aimed to clarify the effects of the Wnt/β-catenin pathway in GH-producing pituitary adenomas. We performed immunofluorescence staining using antibodies against GH and β-catenin in pathological samples of pituitary adenoma from 62 patients with acromegaly who underwent pituitary surgery at our hospital between January 2008 and December 2021. We also obtained clinical data for the patients, including the results of endocrine testing, and evaluated the relationships of key indices with the intracellular localization of β-catenin. Samples from 26 cases (42%) showed strong punctate expression of β-catenin in the nuclei (dot pattern (DP) group), and samples from 36 cases (58%) showed β-catenin expression in the cytoplasm or cell membrane (non-DP group). There were no differences in the sex, age, GH concentration, or insulin-like growth factor I (IGF-1) SD scores of the two groups, but the DP group had larger tumors (diameters 18±8 vs. 13±7 mm) and a higher prevalence of macroadenomas (77% vs. 53%). In the DP group, a paradoxical preoperative GH response (an increase of ≥30% of the basal concentration) to 75-g oral glucose tolerance testing was more frequent (46 vs. 22%, p&amp;lt;0.05) and postoperative remission was less frequent (23% vs. 50%, p&amp;lt;0.05). Accordingly, the Wnt/β-catenin pathway appears to be more active in the DP group. The larger tumors and lower postoperative remission rate of the DP group suggest that the Wnt/β-catenin pathway may influence tumor growth. Wnt/β-catenin pathway could play a major role in GH-producing pituitary tumor growth, therefore this pathway would be a potential therapeutic target in the affected patients. Presentation: Thursday, June 15, 2023

FRI291 Musashi1 And Musashi2 Mark Distinct Pituitary Stem Cell Populations

Abstract Disclosure: Y. Rahmatallah: None. J. Banik: None. K. Bronson: None. M.C. MacNicol: None. The cell plastic state of the pituitary is required to meet the changing demands upon pituitary function and may also result in these cells being more vulnerable to malignant transformation. The mechanisms that control pituitary cell plasticity are unknown. The RNA binding protein Musashi (MSI) is expressed in embryonic stem cells, and in cancer stem cells, where MSI functions to promote stem cell plasticity and to oppose premature cell maturation. MSI is also expressed at high levels in adult gonad and adult pituitary. The function of MSI in adult tissues is not fully understood, and the mechanisms that control the pro-proliferative and pro-malignant aspects of MSI function in adult tissues are not known. The two evolutionarily conserved MSI proteins, Musashi1 (MSI1) and Musashi2 (MSI2), are predicted to function redundantly, however, regulatory distinctions have been reported for MSI1 and MSI2. Towards a characterization of MSI1 and MSI2 in pituitary, we analyzed transcriptomics data from public datasets of single-nucleus and single-cell and bulk-tissue gene expression data from physiological and pathophysiological human pituitary tissue. We performed bioinformatics analysis utilizing the single-cell genomics analysis tool, Seurat in R and the pseudotime trajectory analysis tool Monocle and additional genomics and statistics analyses tools in R. We identify the MSI1-expressing pituitary cell population as immature stem cells and the distinct MSI2-expressing pituitary cell population as more mature, committed progenitor cells. Pituitary from human fetal tissue contains multiple distinct MSI1-expressing cell populations while, in contrast, pituitary from human adult tissue contains multiple distinct MSI2-expressing cell populations. Pituitary from human pediatric tissue demonstrates an intermediate state with both distinct MSI1-expressing and distinct MSI2-expressing cell populations. We identify increased MSI1 expression but not increased MSI2 expression in adult pituitary adenoma, and a high level of variation in the MSI1 to MSI2 expression ratio between distinct pituitary adenomas. Based upon this re-analysis of reposited datasets from other pituitary investigators, we hypothesize that the increase that we observe, in MSI1 to MSI2 expression ratio in adult pituitary tumors is consistent with a reversion of mature cells to an earlier immature state. Adult pituitary may contain the mechanisms that regulate MSI2 function but may not be equipped to properly control high levels of re-expressed MSI1. An understanding of the physiological functions and mechanisms of regulation of the distinct MSI proteins in pituitary may provide insight into potential mechanisms that could be recruited to increase physiological pituitary cell growth and differentiation in regenerative therapy and to oppose pathological cell growth in pituitary tumor. Presentation: Friday, June 16, 2023

THU043 Single-cell Transcriptomics Show Sex-specific Responses To A High Fat Diet, Under Thermoneutral Conditions, Pointing To Reduced Pituitary Plasticity

Abstract Disclosure: T.K. Miles: None. A.N. Lagasse: None. A.K. Odle: None. S.S. Lira: None. M.M. Syed: None. N. Akhter: None. M.C. MacNicol: None. A.M. MacNicol: None. G.V. Childs: None. Hyperinsulinemia caused by a high fat diet (HFD) directly suppressed pituitary growth hormone (Gh) and growth hormone releasing hormone receptor (Ghrhr) mRNAs (Luque and Kineman, 2006). To study the broader impact of a HFD, we exposed 3 groups of FVB.129P mice to 60% HFD for 10 or 15 wks at thermoneutrality (TN) (30 C), or 15 wks at room temperature (RT). Pituitary transcript expression was analyzed with single-cell RNA-seq. HFD-fed mice gained &amp;gt;20 g by 12 wks, showing increased serum leptin (1.8-2X), insulin (2-8X) and IL-6 (4-6X), decreased glucose clearance after a glucose challenge and decreased respiratory quotient indicating fat burning. Activity was unaffected by HFD. Rank plot analyses showed reduced amplitude GH pulses in HFD females fed at RT (15 wks), but not in mice fed at TN. Serum levels of other pituitary hormones were unaffected in HFD females. In HFD males, only serum TSH was elevated significantly (1.8X, 15 wks, TN). Analysis of the scRNA-seq data detected separate clusters representing each cell type. Two multihormonal cell clusters evident in control females mostly disappeared following HFD (15 wks, RT). At the threshold cutoff of avg Log2FC±0.5 with adj p&amp;lt;0.05, female somatotrope clusters showed reduced Pomc, Cga, and ribosomal proteins. Female lactotrope clusters exhibited decreased Gh mRNA (avg Log2FC -1.8 or -2.5) and galanin at 10 wks (TN). At 15 wks (TN), lactotrope clusters showed significant changes in 46 transcripts including reductions in Prl, 29 ribosomal proteins, galanin, and 3 transcriptional regulators. Notably, this cluster showed an increase in synaptotagmin-4 (Syt4), which is also elevated in oxytocin neurons following a HFD. Stem cell clusters in females were strongly impacted by HFD after 15 weeks (TN) with 94 reduced transcripts of which 48 were involved in cytoplasmic translation and ribosome biogenesis and &amp;gt;20 were involved with signaling and cell differentiation. In males, whereas changes in most clusters fell below the threshold cutoffs, stem cell clusters had 13 reduced transcripts after 10 or 15 weeks, most of which involved immune system processes including defense responses and antigen processing and presentation. The GH deficiency in mice fed under thermoneutral conditions was not as severe as that reported by Luque and Kineman, perhaps due to differences in strain, sex, and/or the environmental temperature. The reduced expression of multihormonal clusters, Gh by lactotropes and corticotropes, and Cga and Pomc by somatotropes suggests that HFD may reduce plasticity and activity of progenitor cells in the pituitary. The changes in lactotropes and somatotropes also indicate that HFD may compromise ribosome function and cytoplasmic translation. The reduced transcriptome in stem cells in both males and females suggests HFD interference with cell differentiation and pituitary plasticity as well as dysfunctional immune defense responses. Presentation: Thursday, June 15, 2023

THU046 Repeated Treatment With AZP-3813, A Bicyclic, 16-Amino Acid Peptide Antagonist Of The Human Growth Hormone Receptor, Induces Enhanced Suppression Of IGF1 In Beagle Dogs

Abstract Disclosure: G. Ravel: None. C. Chalmey: None. C. Berardet: None. D. Duracher: None. H. Kurasaki: None. T. Tomiyama: None. P. Reid: None. M.D. Culler: None. Medical treatment of acromegaly is based on either suppressing pituitary growth hormone (GH) secretion or inhibiting GH action by preventing interaction with its receptor in order to suppress the elevated levels of insulin-like growth factor 1 (IGF1). AZP-3813 is a 16-amino acid, bicyclic peptide antagonist of the GH receptor (GHR) derived from peptide sequences discovered using a unique, cell-free in vitro transcription-translation system screened against the human GHR, and optimized by rational design to increase binding affinity, solubility and half-life. The KD of AZP-3813 for the human GHR is 1.9nM. In previous studies, AZP-3813 was demonstrated to suppress IGF1 secretion in juvenile rats in a dose-related manner, and to maintain IGF1 suppression when given daily for extended periods. Recently, we demonstrated that AZP-3813 is also very effective in suppressing IGF1 in normal Beagle dogs. Dogs receiving a single 0.1, 1 and 10 mg/kg subcutaneous injection of AZP-3813 responded with a dose-related 2.2 + 7.1, 21.4 + 2.7 and 27.8 + 1.5% decrease in IGF1 after 24 hours, respectively, and the decrease in IGF1 attained with a single 10 mg/kg dose was maintained for over 72 hours. The relatively small further increase in IGF1 suppression with 10 versus 1 mg/kg suggests that 10 mg/kg AZP-3813 may induce near maximal GHR antagonism. To examine the effect of repeated and higher dose treatment of dogs with AZP-3813, young adult, non-fasted, Beagle dogs were injected subcutaneously at rotated dorsal sites with AZP-3813 at doses of 10, 30 or 60 mg/kg (n=2, one male and one female) daily for seven days. Blood samples, collected prior to dosing to establish baseline IGF1 levels and 24 hour after the final, seventh AZP-3813 injection, were assayed for total IGF1 content by radioimmunoassay. Baseline IGF1 levels were lower in the female dogs (136.7 + 36.1 ng/ml) than in the male dogs (197.0 + 11.3 ng/ml); however, the percent IGF1 suppression resulting from AZP-3813 treatment was similar for both sexes. AZP-3813, injected for seven days at 10, 30 and 60 mg/kg, induced highly significant 69.0 + 4.0, 70.5 + 9.5 and 75.0 + 1.0% decreases in IGF1, respectively. The similar magnitude of IGF1 suppression attained with the three doses of AZP-3813 implies that maximal GH antagonism is essentially achieved with the 10 mg/kg dose. The substantial increase in IGF1 suppression achieved by repeated 10 mg/kg injection of AZP-3813, compared to the previously observed suppression after a single 10 mg/kg injection, likely represents compound accumulation (under investigation) as well as a progressive effect of maximal GH antagonism on IGF1 production. These results demonstrate that the potent GHR antagonist activity of AZP-3813 translates to a highly effective suppression of IGF1 in normal dogs and further support the development of AZP-3813 as a potential therapy for acromegaly. Presentation: Thursday, June 15, 2023

GHRH Neurons from the Ventromedial Hypothalamic Nucleus Provide Dynamic and Sex-Specific Input to the Brain Glucose-Regulatory Network.

The ventromedial hypothalamic nucleus (VMN) controls glucose counter-regulation, including pituitary growth hormone (GH) secretion. VMN neurons that express the transcription factor steroidogenic factor-1/NR5A1 (SF-1) participate in glucose homeostasis. Research utilized in vivo gene knockdown tools to determine if VMN growth hormone-releasing hormone (Ghrh) regulates hypoglycemic patterns of glucagon, corticosterone, and GH outflow according to sex. Intra-VMN Ghrh siRNA administration blunted hypoglycemic hypercorticosteronemia in each sex, but abolished elevated GH release in males only. Single-cell multiplex qPCR showed that dorsomedial VMN (VMNdm) Ghrh neurons express mRNAs encoding Ghrh, SF-1, and protein markers for glucose-inhibitory (γ-aminobutyric acid) or -stimulatory (nitric oxide; glutamate) neurotransmitters. Hypoglycemia decreased glutamate decarboxylase67 (GAD67) transcripts in male, not female VMNdm Ghrh/SF-1 neurons, a response that was refractory to Ghrh siRNA. Ghrh gene knockdown prevented, in each sex, hypoglycemic down-regulation of Ghrh/SF-1 nerve cell GAD65 transcription. Ghrh siRNA amplified hypoglycemia-associated up-regulation of Ghrh/SF-1 neuron nitric oxide synthase mRNA in male and female, without affecting glutaminase gene expression. Ghrh gene knockdown altered Ghrh/SF-1 neuron estrogen receptor-alpha (ERα) and ER-beta transcripts in hypoglycemic male, not female rats, but up-regulated GPR81 lactate receptor mRNA in both sexes. Outcomes infer that VMNdm Ghrh/SF-1 neurons may be an effector of SF-1 control of counter-regulation, and document Ghrh modulation of hypoglycemic patterns of glucose-regulatory neurotransmitter along with estradiol and lactate receptor gene transcription in these cells. Co-transmission of glucose-inhibitory and -stimulatory neurochemicals of diverse chemical structure, spatial, and temporal profiles may enable VMNdm Ghrh neurons to provide complex dynamic, sex-specific input to the brain glucose-regulatory network.

Long acting growth hormone (LAGH), an update.

In 1957, Maurice Raben at Yale was able to isolate and purify growth hormone from cadaveric pituitary glands. Pituitary growth hormone was the only way to treat children with growth hormone (GH) deficiency, until 1985 when recombinant GH became available for daily subcutaneous injection. For many years, the pediatric endocrine community longed for a long-acting recombinant GH formulation that would decrease the inconvenience of daily injections. Several mechanisms were employed to develop a GH that is rapidly absorbed into the blood stream after subcutaneous injection, but provides slow removal from the circulatory system to potentially optimize patient adherence to GH therapy. Four long-acting growth hormones are currently available in the world, or are close to regulatory approval. They are: (1) Pegylated formulations, (2) Prodrug formulations which are converted into active drug, (3) Nonvalent transient albumin binding GH compounds and (4) GH fusion proteins where a protein si fused with GH. All four formulations have undergone detailed phase 3 studies and were found to show non-inferiority in these clinical studies. All four demonstrate a safety and tolerability profile that is comparable to that of daily somatropin with an excellent adherence profile.