Roberto Salvatori

Clinical characteristics and therapeutic responses in patients with Germ-line AIP mutations and pituitary adenomas : An international collaborative study

CONTEXT AIP mutations (AIPmut) give rise to a pituitary adenoma predisposition that occurs in familial isolated pituitary adenomas and less often in sporadic cases. The clinical and therapeutic features of AIPmut-associated pituitary adenomas have not been studied comprehensively. OBJECTIVE The objective of the study was to assess clinical/therapeutic characteristics of AIPmut pituitary adenomas. DESIGN This study was an international, multicenter, retrospective case collection/database analysis. SETTING The study was conducted at 36 tertiary referral endocrine and clinical genetics departments. PATIENTS Patients included 96 patients with germline AIPmut and pituitary adenomas and 232 matched AIPmut-negative acromegaly controls. RESULTS The AIPmut population was predominantly young and male (63.5%); first symptoms occurred as children/adolescents in 50%. At diagnosis, most tumors were macroadenomas (93.3%); extension and invasion was common. Somatotropinomas comprised 78.1% of the cohort; there were also prolactinomas (n = 13), nonsecreting adenomas (n = 7), and a TSH-secreting adenoma. AIPmut somatotropinomas were larger (P = 0.00026), with higher GH levels (P = 0.00068), more frequent extension (P = 0.018) and prolactin cosecretion (P = 0.00023), and occurred 2 decades before controls (P < 0.000001). Gigantism was more common in the AIPmut group (P < 0.000001). AIPmut somatotropinoma patients underwent more surgical interventions (P = 0.00069) and had lower decreases in GH (P = 0.00037) and IGF-I (P = 0.028) and less tumor shrinkage with somatostatin analogs (P < 0.00001) vs. controls. AIPmut prolactinomas occurred generally in young males and frequently required surgery or radiotherapy. CONCLUSIONS AIPmut pituitary adenomas have clinical features that may negatively impact treatment efficacy. Predisposition for aggressive disease in young patients, often in a familial setting, suggests that earlier diagnosis of AIPmut pituitary adenomas may have clinical utility.

The role of germline AIP, MEN1, PRKAR1A, CDKN1B and CDKN2C mutations in causing pituitary adenomas in a large cohort of children, adolescents, and patients with genetic syndromes.

Stratakis CA, Tichomirowa MA, Boikos S, Azevedo MF, Lodish M, Martari M, Verma S, Daly AF, Raygada M, Keil MF, Papademetriou J, Drori‐Herishanu L, Horvath A, Tsang KM, Nesterova M, Franklin S, Vanbellinghen J‐F, Bours V, Salvatori R, Beckers A. The role of germline AIP, MEN1, PRKAR1A, CDKN1B and CDKN2C mutations in causing pituitary adenomas in a large cohort of children, adolescents, and patients with genetic syndromes.

Effects of an oral growth hormone secretagogue in older adults

CONTEXT GH secretion declines with age, possibly contributing to reduced muscle mass, strength, and function. GH secretagogues (GHS) may increase muscle mass and physical performance. OBJECTIVES/DESIGN We conducted a randomized, double-masked, placebo-controlled, multicenter study to investigate the hormonal, body composition, and physical performance effects and the safety of the orally active GHS capromorelin in older adults with mild functional limitation. INTERVENTION/PARTICIPANTS: A total of 395 men and women aged 65-84 yr were randomized for an intended 2 yr of treatment to four dosing groups (10 mg three times/week, 3 mg twice a day, 10 mg each night, and 10 mg twice a day) or placebo. Although the study was terminated early according to predetermined treatment effect criteria, 315 subjects completed 6 months of treatment, and 284 completed 12 months. RESULTS A sustained dose-related rise in IGF-I concentrations occurred in all active treatment groups. Each capromorelin dose prompted a rise in peak nocturnal GH, which was greatest with the least frequent dosing. At 6 months, body weight increased 1.4 kg in subjects receiving capromorelin and decreased 0.2 kg in those receiving placebo (P = 0.006). Lean body mass increased 1.4 vs. 0.3 kg (P = 0.001), and tandem walk improved by 0.9 sec (P = 0.02) in the pooled treatment vs. placebo groups. By 12 months, stair climb also improved (P = 0.04). Adverse events included fatigue, insomnia, and small increases in fasting glucose, glycosylated hemoglobin, and indices of insulin resistance. CONCLUSIONS In healthy older adults at risk for functional decline, administration of the oral GHS capromorelin may improve body composition and physical function.

Metabolic regulation of ghrelin O-acyl transferase (GOAT) expression in the mouse hypothalamus, pituitary, and stomach

Ghrelin acts as an endocrine link connecting physiological processes regulating food intake, body composition, growth, and energy balance. Ghrelin is the only peptide known to undergo octanoylation. The enzyme mediating this process, ghrelin O-acyltransferase (GOAT), is expressed in the gastrointestinal tract (GI; primary source of circulating ghrelin) as well as other tissues. The present study demonstrates that stomach GOAT mRNA levels correlate with circulating acylated-ghrelin levels in fasted and diet-induced obese mice. In addition, GOAT was found to be expressed in both the pituitary and hypothalamus (two target tissues of ghrelins actions), and regulated in response to metabolic status. Using primary pituitary cell cultures as a model system to study the regulation of GOAT expression, we found that acylated-ghrelin, but not desacyl-ghrelin, increased GOAT expression. In addition, growth-hormone-releasing hormone (GHRH) and leptin increased, while somatostatin (SST) decreased GOAT expression. The physiologic relevance of these later results is supported by the observation that pituitary GOAT expression in mice lacking GHRH, SST and leptin showed opposite changes to those observed after in vitro treatment with the corresponding peptides. Therefore, it seems plausible that these hormones directly contribute to the regulation of pituitary GOAT. Interestingly, in all the models studied, pituitary GOAT expression paralleled changes in the expression of a dominant spliced-variant of ghrelin (In2-ghrelin) and therefore this transcript may be a primary substrate for pituitary GOAT. Collectively, these observations support the notion that the GI tract is not the only source of acylated-ghrelin, but in fact locally produced des-acylated-ghrelin could be converted to acylated-ghrelin within target tissues by locally active GOAT, to mediate its tissue-specific effects.

Recurrence of Hyperprolactinemia after Withdrawal of Long-Term Cabergoline Therapy

CONTEXT Recurrence of hyperprolactinemia after cabergoline withdrawal ranges widely from 36 to 80%. The Pituitary Society recommends withdrawal of cabergoline in selected patients. OBJECTIVE Our aim was to evaluate recurrence of hyperprolactinemia in patients meeting The Pituitary Society guidelines. DESIGN Patients were followed from the date of discontinuation to either relapse of hyperprolactinemia or the day of last prolactin test. SETTING We conducted the study at an academic medical center. PATIENTS Forty-six patients meeting Pituitary Society criteria (normoprolactinemic and with tumor volume reduction after 2 or more years of treatment) participated in the study. INTERVENTIONS After withdrawal, if prolactin returned above reference range, another measurement was obtained within 1 month, symptoms were assessed by questionnaire, and magnetic resonance imaging was performed. MAIN OUTCOME MEASURES We measured risk of and time to recurrence estimates as well as clinical predictors of recurrence. RESULTS Mean age of patients was 50 +/- 13 yr, and 70% were women. Thirty-one patients had microprolactinomas, 11 had macroprolactinomas, and four had nontumoral hyperprolactinemia. The overall recurrence was 54%, and the estimated risk of recurrence by 18 months was 63%. The median time to recurrence was 3 months (range, 1-18 months), with 91% of recurrences occurring within 1 yr after discontinuation. Size of tumor remnant prior to withdrawal predicted recurrence [18% increase in risk for each millimeter (95% confidence interval, 3-35; P = 0.017)]. None of the tumors enlarged in the patients experiencing recurrence, and 28% had symptoms of hypogonadism. CONCLUSIONS Cabergoline withdrawal is practical and safe in a subset of patients as defined by The Pituitary Society guidelines; however, the average risk of long-term recurrence in our study was over 60%. Close follow-up remains important, especially within the first year.

Longevity in Untreated Congenital Growth Hormone Deficiency Due to a Homozygous Mutation in the GHRH Receptor Gene

CONTEXT Reduced longevity observed in hypopituitarism has been attributed to GH deficiency (GHD). It is, however, unclear whether GHD or other confounding factors cause this early mortality. OBJECTIVE The aim was to study longevity in subjects from a large kindred with untreated, lifetime isolated GHD (IGHD) due to a homozygous mutation in the GHRH receptor gene and in heterozygous carriers of the mutation. DESIGN, SETTING, AND PARTICIPANTS We carried out a retrospective cohort study on three groups. We first compared mortality risk of 65 IGHD individuals and their 128 unaffected siblings from 34 families. We then compared mean age of death of the IGHD to the general population. A transversal study was carried out to compare the rate of heterozygosity for the mutation in two groups of young (20-40 yr old) and old (60-80 yr old) normal-appearing subjects from the same county. MAIN OUTCOME MEASURE We measured longevity. RESULTS The risk of death of IGHD subjects was not different from their siblings. Life span in IGHD individuals was shorter than the general population. When stratified by sex, this difference persisted only in females, due to a high frequency of IGHD deaths in females aged 4-20. There was no significant difference in life span between IGHD subjects and siblings or the general population when analyzing subjects who reached age 20. The prevalence of heterozygosity did not differ in young and old groups, suggesting no survival advantage or disadvantage. CONCLUSIONS In a selected genetic background, lifelong untreated IGHD does not affect longevity.

Glucocorticoid-induced loss of DNA methylation in non-neuronal cells and potential involvement of DNMT1 in epigenetic regulation of Fkbp5

Glucocorticoids may play a significant role in the etiology of neuropsychiatric illnesses. Abnormalities in plasma cortisol levels, glucocorticoid sensitivity, and HPA-axis function often accompany clinical symptoms of stress-related illnesses such as PTSD and depression. Of particular interest are genetic association studies that link single nucleotide polymorphisms of HPA-axis genes with illnesses only in the context of an early-life trauma exposure such as child abuse. These studies suggest that dysregulation of HPA-axis function can have lasting repercussions in shaping mood and anxiety, long after termination of the traumatic experience. As persistent glucocorticoid-induced loss of DNA methylation in FK506 binding protein 5 (Fkbp5) was previously observed in the hippocampus and blood and in the neuronal cell line HT-22, we asked whether these epigenetic alterations occur in non-neuronal, HPA-axis relevant cells. We used the pituitary adenoma cell line AtT-20 to demonstrate that the intronic enhancer region of Fkbp5 undergoes loss of DNA methylation in response to dexamethasone treatment in a dose-dependent manner. We also focused on the mouse hippocampal dentate gyrus to test whether these changes would be enriched in a region implicated in the HPA-axis stress response, neurogenesis, and synaptic plasticity. We observed an increase in enrichment of DNA methylation loss in the dentate gyrus, as compared to whole hippocampal tissues that were similarly treated with glucocorticoids. We then asked whether DNA methyltransferase 1 (Dnmt1), a methyltransferase enzyme involved in maintaining DNA methylation following cell division, is involved in the observed epigenetic alterations. We found a dose-dependent decrease of Dnmt1 expression in the AtT-20 cells following dexamethasone treatment, and a similar decrease in corticosterone-treated mouse hippocampus. Taken together, we provide evidence that these glucocorticoid-induced epigenetic alterations have a broader validity in non-neuronal cells and that they may involve the DNA methylation machinery.

X-linked acrogigantism syndrome: clinical profile and therapeutic responses.

X-linked acrogigantism (X-LAG) is a new syndrome of pituitary gigantism, caused by microduplications on chromosome Xq26.3, encompassing the gene GPR101, which is highly upregulated in pituitary tumors. We conducted this study to explore the clinical, radiological, and hormonal phenotype and responses to therapy in patients with X-LAG syndrome. The study included 18 patients (13 sporadic) with X-LAG and microduplication of chromosome Xq26.3. All sporadic cases had unique duplications and the inheritance pattern in two families was dominant, with all Xq26.3 duplication carriers being affected. Patients began to grow rapidly as early as 2-3 months of age (median 12 months). At diagnosis (median delay 27 months), patients had a median height and weight standard deviation scores (SDS) of >+3.9 SDS. Apart from the increased overall body size, the children had acromegalic symptoms including acral enlargement and facial coarsening. More than a third of cases had increased appetite. Patients had marked hypersecretion of GH/IGF1 and usually prolactin, due to a pituitary macroadenoma or hyperplasia. Primary neurosurgical control was achieved with extensive anterior pituitary resection, but postoperative hypopituitarism was frequent. Control with somatostatin analogs was not readily achieved despite moderate to high levels of expression of somatostatin receptor subtype-2 in tumor tissue. Postoperative use of adjuvant pegvisomant resulted in control of IGF1 in all five cases where it was employed. X-LAG is a new infant-onset gigantism syndrome that has a severe clinical phenotype leading to challenging disease management.

Clinical and genetic characterization of pituitary gigantism: an international collaborative study in 208 patients

Despite being a classical growth disorder, pituitary gigantism has not been studied previously in a standardized way. We performed a retrospective, multicenter, international study to characterize a large series of pituitary gigantism patients. We included 208 patients (163 males; 78.4%) with growth hormone excess and a current/previous abnormal growth velocity for age or final height >2 s.d. above country normal means. The median onset of rapid growth was 13 years and occurred significantly earlier in females than in males; pituitary adenomas were diagnosed earlier in females than males (15.8 vs 21.5 years respectively). Adenomas were ≥10 mm (i.e., macroadenomas) in 84%, of which extrasellar extension occurred in 77% and invasion in 54%. GH/IGF1 control was achieved in 39% during long-term follow-up. Final height was greater in younger onset patients, with larger tumors and higher GH levels. Later disease control was associated with a greater difference from mid-parental height (r=0.23, P=0.02). AIP mutations occurred in 29%; microduplication at Xq26.3 - X-linked acrogigantism (X-LAG) - occurred in two familial isolated pituitary adenoma kindreds and in ten sporadic patients. Tumor size was not different in X-LAG, AIP mutated and genetically negative patient groups. AIP-mutated and X-LAG patients were significantly younger at onset and diagnosis, but disease control was worse in genetically negative cases. Pituitary gigantism patients are characterized by male predominance and large tumors that are difficult to control. Treatment delay increases final height and symptom burden. AIP mutations and X-LAG explain many cases, but no genetic etiology is seen in >50% of cases.

Growth hormone-releasing hormone disruption extends lifespan and regulates response to caloric restriction in mice

We examine the impact of targeted disruption of growth hormone-releasing hormone (GHRH) in mice on longevity and the putative mechanisms of delayed aging. GHRH knockout mice are remarkably long-lived, exhibiting major shifts in the expression of genes related to xenobiotic detoxification, stress resistance, and insulin signaling. These mutant mice also have increased adiponectin levels and alterations in glucose homeostasis consistent with the removal of the counter-insulin effects of growth hormone. While these effects overlap with those of caloric restriction, we show that the effects of caloric restriction (CR) and the GHRH mutation are additive, with lifespan of GHRH-KO mutants further increased by CR. We conclude that GHRH-KO mice feature perturbations in a network of signaling pathways related to stress resistance, metabolic control and inflammation, and therefore provide a new model that can be used to explore links between GHRH repression, downregulation of the somatotropic axis, and extended longevity. DOI: http://dx.doi.org/10.7554/eLife.01098.001