Autoimmune lymphocytic hypophysitis in association with autoimmune eye disease and sequential treatment with infliximab and rituximab.

INTRODUCTION: Autoimmune lymphocytic hypophysitis associates predominantly with other autoimmune endocrinopathies and is most commonly treated with glucocorticoids and/or decompressive pituitary surgery. Here we report a new association and treatment modality for lymphocytic hypophysitis. METHODS: A 52-year-old woman presented with scleritis, uveitis, facial palsy, and central diabetes insipidus, accompanied by thickened pituitary stalk and enlarged pituitary on cranial MRI. Neurosarcoidosis was suspected and treatment with glucocorticoids and methotrexate initiated. Since symptoms persisted, infliximab (a monoclonal antibody that antagonizes tumor necrosis factor alpha) was added to her regimen. The patient initially improved but after 6 months developed recurrent pituitary enlargement, bilateral optic neuritis, and panhypopituitarism. To ascertain the nature of the pituitary lesion, she underwent transsphenoidal biopsy, which revealed lymphocytic hypophysitis with numerous CD20 positive B lymphocytes. The pathological finding suggested to us that administration of rituximab (a monoclonal antibody that lyzes B cells expressing CD20) could be useful. Following two courses of rituximab, the pituitary mass resolved and the corticotroph axis partially recovered. The patient has remained in remission during 3 years of follow up. CONCLUSION: This is the first report of hypophysitis occurring with the triad of scleritis, uveitis, and optic neuritis, as well as the first immunotherapy based on the sequential use of infliximab and rituximab.

A Subset of Men With Age-Related Decline in Testosterone Have Gonadotroph Autoantibodies.

CONTEXT: Age-related decline in serum testosterone (T) is being increasingly diagnosed. In most men, it associates with low or inappropriately normal gonadotropin levels, which suggests a hypothalamic-pituitary etiology. Autoantibodies against adenohypophyseal cells have been associated with pituitary dysfunction; however, the prevalence of pituitary autoimmunity in this age-related T decline has not been assessed. OBJECTIVES: This is a proof-of-concept study with the objective of determining the prevalence of antibodies to gonadotrophs in older men with age-related low T and compare it with healthy young and older eugonadal men. STUDY DESIGN: This is a cross-sectional case-control study of 182 men. Cases included 100 older men (≥65 years) with age-related low T levels; the control groups were composed of 50 young and 32 older healthy eugonadal men. Serum antibodies against the anterior pituitary gland were measured using a two-step approach: 1) single indirect immunofluorescence (ie, participant serum only) to determine the pattern of cytosolic staining; and 2) double indirect immunofluorescence (ie, participant serum plus a commercial adenohypophyseal hormone antibody) to identify the anterior pituitary cell type recognized by the patient's antibodies). RESULTS: In participants with positive antipituitary antibodies, the granular cytosolic pattern (highly predictive of pituitary autoimmunity) was only seen in older men with age-related low T (4%) and none in control groups (0%, P = .001). Double indirect immunofluorescence confirmed that pituitary antibodies were exclusively directed against the gonadotrophs. CONCLUSION: A subset of older men with age-related low T levels have specific antibodies against the gonadotrophs. Whether these antibodies are pathogenic and contributory to the age-related decline in T remains to be established.

Central inhibitory effects on feeding induced by the adipo-myokine irisin.

Irisin, the soluble secreted form of fibronectin type III domain containing 5 (FNDC5)-cleaved product, is a recently identified adipo-myokine that has been indicated as a possible link between physical exercise and energetic homeostasis. The co-localization of irisin with neuropeptide Y in hypothalamic sections of paraventricular nucleus, which receives NPY/AgRP projections from the arcuate nucleus, suggests a possible role of irisin in the central regulation of energy balance. In this context, in the present work we studied the effects of intra-hypothalamic irisin (1µl, 50-200nmol/l) administration on feeding and orexigenic [agouti-related peptide (AgRP), neuropeptide Y (NPY) and orexin-A] and anorexigenic [cocaine and amphetamine-regulated transcript (CART) and proopiomelanocortin (POMC)] peptides in male Sprague-Dawley rats. Furthermore, we evaluated the effects of irisin on hypothalamic dopamine (DA), norepinephrine (NE) and serotonin (5-hydroxytryptamine, 5-HT) concentrations and plasma NE levels. Compared to vehicle, irisin injected rats showed decreased food intake, possibly mediated by stimulated CART and POMC and inhibited DA, NE and orexin-A, in the hypothalamus. We also found increased plasma NE levels, supporting a role for sympathetic nervous system stimulation in mediating increased oxygen consumption by irisin.

Increased locomotor and thermogenic activity in mice with targeted ablation of the GHRH gene.

OBJECTIVE: Growth hormone (GH) deficiency (GHD) leads to growth failure and changes in body composition, including increased fat accumulation and reduced lean body mass in both humans and rodents. The aim of this study was to examine the factors that contribute to energy imbalance in the GH releasing hormone knock out (GHRHKO) mice, a well established model of GHD. DESIGN: We evaluated food intake (of standard laboratory chow), total body weight (TBW), locomotor activity, body temperature and interscapular brown adipose tissue (BAT) weight in 8 adult male mice homozygous for the GHRHKO allele (-/-) and 8 heterozygous (+/-) animals as controls. The gene expression of uncoupling protein-1 (UCP-1) in BAT and the levels of norepinephrine (NE), dopamine (DA), and serotonin (5-hydroxytryptamine, 5-HT) in the ventral striatum were measured by real-time reverse transcription polymerase chain reaction (RT-PCR) and high performance liquid chromatography (HPLC) analysis, respectively. RESULTS: Throughout 2 months of observation -/- mice consumed approximately 40% more food (normalized to TBW; P<0.001), and showed increased locomotor activity in 24h time compared to controls (P<0.05). Moreover, -/- animals showed increased body temperature (P<0.001), BAT weight (P<0.001), and UCP-1 gene expression (P<0.001), while NE levels in the striatum area were lower (P<0.05) than controls. CONCLUSIONS: The present study demonstrates that the increased food intake observed in GHRH ablated animals is associated with increased locomotor and thermogenic activity.

Hypotensive effects of omentin-1 related to increased adiponectin and decreased interleukin-6 in intra-thoracic pericardial adipose tissue.

BACKGROUND: Omentin is an adipokine expressed in visceral adipose tissue (VAT). In vitro studies demonstrated that omentin induces vasorelaxation in isolated rat mesenteric arteries, and in vivo studies showed inhibition of agonist-induced increases in blood pressure, possibly mediated by nitric oxide (NO)-dependent mechanisms. METHODS: We investigated, in normotensive rats, the effects of subacute omentin-1 administration [8µg/kg, intraperitoneally (ip), once daily for 14 days] on cardiac activity, blood pressure, plasma concentration of l-citrulline (as a marker of NO production from l-arginine), and the gene expression of adiponectin, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in intra-thoracic pericardial adipose tissue (PAT). Electrocardiography (ECG), heart rate (HR), mean blood pressure (MBP), pulse pressure (PP) were monitored before and after treatment with omentin-1 or vehicle. RESULTS: With respect to baseline and vehicle, we found a significant decrease of MBP (p<0.005) and PP (p<0.05) after treatment with omentin-1, while ECG and HR were not modified. Omentin-1 significantly increased l-citrulline levels in plasma (p<0.05), and the gene expression of adiponectin in PAT (p<0.05). On the other hand, we found decreased gene expression of IL-6 (p<0.005), while TNF-α mRNA in PAT was not affected. CONCLUSION: We conclude that the hypotensive effects of omentin-1 could be driven by stimulated production of NO in the vascular system, possibly related to increased adiponectin and decreased IL-6 mRNA in PAT.

Detection of pituitary antibodies by immunofluorescence: approach and results in patients with pituitary diseases.

CONTEXT: Pituitary antibodies have been measured mainly to identify patients whose disease is caused or sustained by pituitary-specific autoimmunity. Although reported in over 100 publications, they have yielded variable results and are thus considered of limited clinical utility. OBJECTIVES: Our objectives were to analyze all publications reporting pituitary antibodies by immunofluorescence for detecting the major sources of variability, to experimentally test these sources and devise an optimized immunofluorescence protocol, and to assess prevalence and significance of pituitary antibodies in patients with pituitary diseases. STUDY DESIGN AND OUTCOME MEASURES: We first evaluated the effect of pituitary gland species, section fixation, autofluorescence quenching, blockade of unwanted antibody binding, and use of purified IgG on the performance of this antibody assay. We then measured cross-sectionally the prevalence of pituitary antibodies in 390 pituitary cases and 60 healthy controls, expressing results as present or absent and according to the (granular, diffuse, perinuclear, or mixed) staining pattern. RESULTS: Human pituitary was the best substrate to detect pituitary antibodies and yielded an optimal signal-to-noise ratio when treated with Sudan black B to reduce autofluorescence. Pituitary antibodies were more common in cases (95 of 390, 24%) than controls (3 of 60, 5%, P = .001) but did not discriminate among pituitary diseases when reported dichotomously. However, when expressed according to their cytosolic staining, a granular pattern was highly predictive of pituitary autoimmunity (P < .0001). CONCLUSION: We report a comprehensive study of pituitary antibodies by immunofluorescence and provide a method and an interpretation scheme that should be useful for identifying and monitoring patients with pituitary autoimmunity.

Peripheral chemerin administration modulates hypothalamic control of feeding.

Chemerin is a recently identified adipokine that is involved in the regulation of adipogenesis, energy metabolism, and inflammation. The aim of the present study was to investigate the role of chemerin on food intake, body weight and hypothalamic peptidergic and aminergic modulators which play a pivotal role in feeding regulation in rats. Male adult Wistar rats were intraperitoneally injected, daily for 17 days at 9.00am, with either vehicle (saline; N=12) or chemerin (8µg/kg; N=12) and (16µg/kg; N=12). Food intake was recorded 24h after each administration. Animals were sacrificed 24h after the last injection. Total RNA was extracted from hypothalami and reverse transcribed to evaluate gene expression of agouti-related peptide (AgRP), neuropeptide Y (NPY), orexin-A, corticotrophin releasing hormone (CRH), pro-opiomelanocortin (POMC) and cocaine and amphetamine-regulated transcript (CART). Furthermore, we evaluated the effect of chemerin on dopamine, norepinephrine and serotonin steady state concentrations in rat hypothalamus homogenate, and monoamine release from rat hypothalamic synaptosomes. Chemerin administration (8 and 16µg/kg) decreased both food intake and body weight compared to vehicle, possibly associated with a significant increase in serotonin synthesis and release, in the hypothalamus. On the other hand, the pattern of gene expression following chemerin administration indicates a minor role played by chemerin as a peripheral appetite-regulating signal.

Orexigenic effects of omentin-1 related to decreased CART and CRH gene expression and increased norepinephrine synthesis and release in the hypothalamus.

Omentin-1, a visceral fat depot-specific secretory protein, is inversely correlated with obesity and insulin resistance. We investigated, in rats, the effects of chronic omentin-1 administration (8 µg/kg, intraperitoneally, once daily for 14-days) on feeding behavior and related hypothalamic peptides and neurotransmitters. Food intake and body weight were recorded daily throughout the study. We found a significantly increased food intake compared to controls, but only in days 10-14, while body weight significantly increased since day 12 (P<0.05). Compared with vehicle, omentin-1 treatment led to a significant reduction in both cocaine and amphetamine-regulated transcript (CART) (P<0.05) and corticotrophin releasing hormone (CRH) (P<0.05) gene expression, while pro-opiomelanocortin (POMC), agouti-related peptide (AgRP), neuropeptide Y (NPY) and orexin-A gene expression were not modified with respect to vehicle-treated rats. We also found an increase in hypothalamic levodopa (l-dopa) (P<0.05) and norepinephrine (NE) (P<0.01) synthesis, without any effect on dopamine (DA) and serotonin (5-hydroxytryptamine, 5-HT) metabolism. Furthermore, in hypothalamic synaptosomes, omentin-1 (10-100 ng/ml) stimulated basal NE release (ANOVA, P<0.0001; post hoc, P<0.001 vs. vehicle), in a dose-dependent manner, leaving unaffected both basal and depolarization-induced DA and 5-HT release. Finally, when synaptosomes were co-perfused with leptin and omentin-1, we observed that leptin was able to reverse omentin-1-induced stimulation of NE. In conclusion, the orexigenic effects of omentin-1 could be related, at least in part, to decreased CART and CRH gene expression and increased NE synthesis and release in the hypothalamus.

Orexigenic effects of endomorphin-2 (EM-2) related to decreased CRH gene expression and increased dopamine and norepinephrine activity in the hypothalamus.

Endomorphin-1 (EM-1) and endomorphin-2 (EM-2) are opioid peptides which are selective partial agonists of µ-opioid receptor. We studied the effects of EM-2 injected into the arcuate nucleus (ARC) of the hypothalamus on feeding behavior and gene expression of orexigenic [agouti-related peptide (AgRP), neuropeptide Y (NPY) and orexin-A] and anorexigenic [cocaine and amphetamine-regulated transcript (CART), corticotrophin releasing hormone (CRH) and proopiomelanocortin (POMC)] peptides in male Wistar rats fed a standard laboratory diet. Furthermore, we evaluated the effects of EM-2 on dopamine (DA), norepinephrine (NE) and serotonin (5-hydroxytryptamine, 5-HT) steady state concentrations, in the hypothalamus. 64 rats (16 for each group of treatment) were injected into the ARC, at 9.00 am, with either vehicle or EM-2 (0.50-0.75 µmol/kg) or EM-2 (0.50 µmol/kg) plus ß-funaltrexamine (0.20 µmol/kg). Food intake was recorded through 24h following injection, and hypothalamic DA, NE, 5-HT levels and neuropeptide gene expression were evaluated 24h after EM-2 administration. Compared to vehicle, EM-2 significantly increased food intake, throughout 24h post-injection. Furthermore, EM-2 treatment led to a significant increase of DA and NE concentrations and a decrease of CRH mRNA levels. On the other hand, ß-funaltrexamine administration reverted both feeding stimulatory and neuromodulatory effects induced by EM-2. We can conclude that the orexigenic effect of µ-opioid receptor activation by EM-2 could be related to both inhibition of CRH and stimulation of dopamine and norepinephrine levels, in the hypothalamus.