Microglial phagolysosome dysfunction and altered neural communication amplify phenotypic severity in Prader-Willi Syndrome with larger deletion.

Prader-Willi Syndrome (PWS) is a rare neurodevelopmental disorder of genetic etiology, characterized by paternal deletion of genes located at chromosome 15 in 70% of cases. Two distinct genetic subtypes of PWS deletions are characterized, where type I (PWS T1) carries four extra haploinsufficient genes compared to type II (PWS T2). PWS T1 individuals display more pronounced physiological and cognitive abnormalities than PWS T2, yet the exact neuropathological mechanisms behind these differences remain unclear. Our study employed postmortem hypothalamic tissues from PWS T1 and T2 individuals, conducting transcriptomic analyses and cell-specific protein profiling in white matter, neurons, and glial cells to unravel the cellular and molecular basis of phenotypic severity in PWS sub-genotypes. In PWS T1, key pathways for cell structure, integrity, and neuronal communication are notably diminished, while glymphatic system activity is heightened compared to PWS T2. The microglial defect in PWS T1 appears to stem from gene haploinsufficiency, as global and myeloid-specific Cyfip1 haploinsufficiency in murine models demonstrated. Our findings emphasize microglial phagolysosome dysfunction and altered neural communication as crucial contributors to the severity of PWS T1's phenotype.

Patients' Persistent Symptoms, Clinician Demographics, and Geo-Economic Factors Are Associated with Choice of Therapy for Hypothyroidism by European Thyroid Specialists: The "THESIS" Collaboration.

Background: Hypothyroidism is common, however, aspects of its treatment remain controversial. Our survey aimed at documenting treatment choices of European thyroid specialists and exploring how patients' persistent symptoms, clinician demographics, and geo-economic factors relate to treatment choices. Methods: Seventeen thousand two hundred forty-seven thyroid specialists from 28 countries were invited to participate in an online questionnaire survey. The survey included respondent demographic data and treatment choices for hypothyroid patients with persistent symptoms. Geo-economic data for each country were included in the analyses. Results: The response rate was 32.9% (6058 respondents out of 17,247 invitees). Levothyroxine (LT4) was the initial treatment preferred by the majority (98.3%). Persistent symptoms despite normal serum thyrotropin (TSH) while receiving LT4 treatment were reported to affect up to 10.0% of patients by 75.4% of respondents, while 28.4% reported an increasing such trend in the past 5 years. The principal explanations offered for patients' persistent symptoms were psychosocial factors (77.1%), comorbidities (69.2%), and unrealistic patient expectations (61.0%). Combination treatment with LT4+liothyronine (LT3) was chosen by 40.0% of respondents for patients who complained of persistent symptoms despite a normal TSH. This option was selected more frequently by female thyroid specialists, with high-volume practice, working in countries with high gross national income per capita. Conclusions: The perception of patients' dissatisfaction reported by physicians seems lower than that described by hypothyroid patients in previous surveys. LT4+LT3 treatment is used frequently by thyroid specialists in Europe for persistent hypothyroid-like symptoms even if they generally attribute such symptoms to nonendocrine causes and despite the evidence of nonsuperiority of the combined over the LT4 therapy. Pressure by dissatisfied patients on their physicians for LT3-containing treatments is a likely explanation. The association of the therapeutic choices with the clinician demographic characteristics and geo-economic factors in Europe is a novel information and requires further investigation.

Quality of life, daily functioning, and symptoms in hypothyroid patients on thyroid replacement therapy: A Dutch survey.

Objective: To explore the nature and extent of possible residual complaints among Dutch hypothyroid patients using thyroid replacement therapy, we initiated a comprehensive study measuring health-related quality of life (QoL), daily functioning, and hypothyroidism-associated symptoms in patients and control persons. Methods: An online survey measuring thyroid-specific QoL (ThyPRO), daily functioning, and hypothyroidism-associated symptoms (ThySHI) was distributed among treated hypothyroid patients and control individuals. The advertising text was formulated in an open-ended manner. Patients also provided their most recent thyroid blood values and their thyroid medication. Results: There was a large-sized impairment of QoL (Cohen's d = 1.04, +93 % ThyPRO score) in hypothyroid patients on thyroid replacement therapy (n = 1195) as compared to controls (n = 236). Daily functioning was significantly reduced i.e., general health (-38 %), problems with vigorous- (+64 %) and moderate activities (+77 %). Almost 80 % of patients reported having complaints despite thyroid medication and in-range thyroid blood values, with 75 % expressing a desire for improved treatment options for hypothyroidism (total n = 1194). Hypothyroid patients experienced 2.8 times more intense hypothyroidism-associated symptoms than controls (n = 865, n = 203 resp). Patients' median reported serum concentrations were: TSH 0.90 mU/L, FT4 17.0 pmol/L, and FT3 2.67 pmol/L, with 52 % having low T3 levels (<3.1 pmol/L). The QoL was not found to be related to age, sex, BMI, menopausal status, stress, serum thyroid parameters, the origin and duration of hypothyroidism, the type of thyroid medication, or the LT4 dose used. Conclusions: Our study revealed major reductions in quality of life and daily functioning, and nearly three times more intense hypothyroidism-associated symptoms in treated hypothyroid patients as compared to controls, despite treatment and largely in-range serum TSH/FT4 concentrations. The QoL was not associated with serum thyroid parameters. We recommend future research into the origin of persisting complaints and the development of improved treatment modalities for hypothyroidism.

Mutant Tbl1x male mice have a short life span and do not breed: unexpected findings.

Humans with the mutation Y509C in transducin beta like 1 X-linked (TBL1X HGNC ID HGNC:11585) have been reported to present with the combination of central congenital hypothyroidism and impaired hearing. TBL1X belongs to the WD40 repeat-containing protein family, is part of NCoR and SMRT corepressor complexes, and thereby involved in thyroid hormone signaling. In order to investigate the effects of the Y509C mutation in TBL1X on cellular thyroid hormone action, we aimed to generate a hemizygous male mouse cohort carrying the Tbl1x Y459C mutation which is equivalent to the human TBL1X Y509C mutation using CRISPR/Cas9 technology. Hemizygous male mice were small at birth and inactive. Their life span (median life span 93 days) was very short compared with heterozygous female mice (survived to >200 days with no welfare issues). About 52% of mice did not survive to weaning (133 mice). Of the remaining 118 mice, only 8 were hemizygous males who were unable to mate whereby it was impossible to generate homozygous female mice. In conclusion, the Tbl1x Y459C mutation in male mice has a marked negative effect on birth weight, survival, and fertility of male mice. The present findings are unexpected as they are in contrast to the mild phenotype in human males carrying the equivalent TBL1X Y509C mutation.

Comparative Analysis of Taxonomic and Functional Gut Microbiota Profiles in Relation to Seroconversion of Thyroid Peroxidase Antibodies in Euthyroid Participants.

Background: Previous studies have reported gut microbiome alterations in Hashimoto's autoimmune thyroiditis (HT) patients. Yet, it is unknown whether an aberrant microbiome is present before clinical disease onset in participants susceptible to HT or whether it reflects the effects of the disease itself. In this study, we report for the first time a comprehensive characterization of the taxonomic and functional profiles of the gut microbiota in euthyroid seropositive and seronegative participants. Our primary goal was to determine taxonomic and functional signatures of the intestinal microbiota associated with serum thyroid peroxidase antibodies (TPOAb). A secondary aim was to determine whether different ethnicities warrant distinct reference intervals for accurate interpretation of serum thyroid biomarkers. Methods: In this cross-sectional study, euthyroid participants with (N = 159) and without (N = 1309) TPOAb were selected from the multiethnic (European Dutch, Moroccan, and Turkish) HEalthy Life In an Urban Setting (HELIUS) cohort. Fecal microbiota composition was profiled using 16S rRNA sequencing. Differences between the groups were analyzed based on the overall composition (alpha and beta diversity), as well as differential abundance (DA) of microbial taxa and functional pathways using multiple DA tools. Results: Overall composition showed a substantial overlap between the two groups (p > 0.05 for alpha-diversity; p = 0.39 for beta-diversity), indicating that TPOAb-seropositivity does not significantly differentiate gut microbiota composition and diversity. Interestingly, TPOAb status accounted for only a minor fraction (0.07%) of microbiome variance (p = 0.545). Further exploration of taxonomic differences identified 138 taxa nominally associated with TPOAb status. Among these, 13 taxa consistently demonstrated nominal significance across three additional DA methods, alongside notable associations within various functional pathways. Furthermore, we showed that ethnicity-specific reference intervals for serum thyroid biomarkers are not required, as no significant disparities in serum thyroid markers were found among the three ethnic groups residing in an iodine-replete area (p > 0.05 for thyrotropin, free thyroxine, and TPOAb). Conclusion: These findings suggest that there is no robust difference in gut microbiome between individuals with or without TPOAb in terms of alpha and beta-diversity. Nonetheless, several taxa were identified with nominal significance related to TPOAb presence. Further research is required to determine whether these changes indeed imply a higher risk of overt HT.

Characteristics of specialists treating hypothyroid patients: the "THESIS" collaborative.

Introduction: Thyroid specialists influence how hypothyroid patients are treated, including patients managed in primary care. Given that physician characteristics influence patient care, this study aimed to explore thyroid specialist profiles and associations with geo-economic factors. Methods: Thyroid specialists from 28 countries were invited to respond to a questionnaire, Treatment of Hypothyroidism in Europe by Specialists: an International Survey (THESIS). Geographic regions were defined according to the United Nations Statistics Division. The national economic status was estimated using World Bank data on the gross national income per capita (GNI per capita). Results: 5,695 valid responses were received (response rate 33·0%). The mean age was 49 years, and 65·0% were female. The proportion of female respondents was lowest in Northern (45·6%) and highest in Eastern Europe (77·2%) (p <0·001). Respondent work volume, university affiliation and private practice differed significantly between countries (p<0·001). Age and GNI per capita were correlated inversely with the proportion of female respondents (p<0·01). GNI per capita was inversely related to the proportion of respondents working exclusively in private practice (p<0·011) and the proportion of respondents who treated >100 patients annually (p<0·01). Discussion: THESIS has demonstrated differences in characteristics of thyroid specialists at national and regional levels, strongly associated with GNI per capita. Hypothyroid patients in middle-income countries are more likely to encounter female thyroid specialists working in private practice, with a high workload, compared to high-income countries. Whether these differences influence the quality of care and patient satisfaction is unknown, but merits further study.

Case Report: Multiple prolactinomas in a young man with Kallmann syndrome and familial hypocalciuric hypercalcemia.

Introduction: The occurrence of prolactinomas in sex hormone treated patients with central hypogonadism is extremely rare. Case presentation: We present a Caucasian male patient who was diagnosed with Kallmann syndrome (KS) at age 15 years. Testosterone treatment was started. At age 26 the patient presented with mild headache. MRI revealed two separate pituitary adenomas along with the absence of the olfactory bulbs. Given the presence of marked hyperprolactinemia (17x upper limit of the reference range) the diagnosis prolactinoma was made and treatment with cabergoline was started which resulted in a complete biochemical response and in marked reduction of both adenomas in size. Hypogonadism persisted and testosterone replacement therapy was continued. Genetic testing of genes associated with pituitary tumors, Kallmann syndrome and idiopathic hypogonadotropic hypogonadism was negative. Mild concomitant hypercalcemia in accordance with familial hypocalciuric hypercalcemia (FHH) prompted mutation analysis of the calcium receptor (CASR) gene which yielded a pathogenic inactivating variant. Discussion/conclusion: The presence of two separate prolactinomas in a patient with KS has not yet been reported in the literature. The effect of sex hormone treatment of KS patients on the possible development of prolactinoma is unknown at present. The occurance of multiple prolactinomas in our patient suggests increased susceptibility. Although CaSR is expressed in GnRH neurons in mouse brain and CaSR deficient mice have a reduced hypothalamic GnRH neuronal population, the relevance of the CASR gene variant in our patient for the KS phenotype is unclear at present.

Protocol for a double-blinded randomised controlled trial to assess the effect of faecal microbiota transplantations on thyroid reserve in patients with subclinical autoimmune hypothyroidism in the Netherlands: the IMITHOT trial.

BACKGROUND: Hashimoto's thyroiditis (HT) is a common endocrine autoimmune disease affecting roughly 5% of the general population and involves life-long treatment with levothyroxine, as no curative treatment yet exists. Over the past decade, the crosstalk between gut microbiota and the host immune system has been well-recognised, identifying the gut microbiome as an important factor in host health and disease, including susceptibility to autoimmune diseases. Previous observational studies yielded a link between disruption of the gut microbiome composition and HT. This is the first study that investigates the potential of restoring a disrupted gut microbiome with faecal microbiota transplantations (FMTs) to halt disease progression and dampen autoimmunity. METHODS AND ANALYSIS: The IMITHOT trial is a randomised, double-blinded, placebo-controlled study evaluating either autologous or allogenic FMTs in medication-naïve patients with subclinical autoimmune hypothyroidism. In total, 34 patients will be enrolled to receive either three allogenic or autologous FMTs. FMT will be made of fresh stool and directly administered into the duodenum. Patients will be evaluated at baseline before the first FMT is administered and at 6, 12 and 24 months post-intervention to assess efficacy and adverse events. The primary outcome measure will be the net incremental increase (incremental area under the curve) on thyrotropin-stimulated free thyroxine and free triiodothyronine release at 6 and 12 months compared with baseline. Results will be disseminated via peer-reviewed journals and international conferences. The recruitment of the first patient and donor occurred on 18 December 2019. ETHICS AND DISSEMINATION: Ethics approval was obtained from the hospital Ethics Committee (Medical Ethics Committee) at Amsterdam University Medical Center. The trial's outcomes offer high-quality evidence that aids in unveiling distinct patterns within the gut microbiota potentially associated with improved thyroid function. Consequently, this may open avenues for the future clinical applications of microbial-targeted therapy in individuals at risk of developing overt HT. TRIAL REGISTRATION NUMBER: NL7931.

Reduction of oxytocin-containing neurons and enhanced glymphatic activity in the hypothalamic paraventricular nucleus of patients with type 2 diabetes mellitus.

Evidence from animal experiments has shown that the hypothalamic paraventricular nucleus (PVN) plays a key role in regulating body weight and blood glucose levels. However, it is unclear whether neuron populations in the human PVN are involved in the development of type 2 diabetes mellitus (T2DM). To address this, we investigated the neuronal and glial populations in the PVN of 26 T2DM patients and 20 matched controls. Our findings revealed a significant reduction in oxytocin (Oxt) neuron density in the PVN of T2DM patients compared to controls, while other neuronal populations remained unchanged. This suggests that Oxt neurons may play a specific role in the pathophysiology of T2DM. Interestingly, the reduction in Oxt neurons was accompanied by a decreased melanocortinergic input in to the PVN as reflected by a reduction in alpha-MSH immunoreactivity. We also analysed two glial cell populations, as they are important for maintaining a healthy neural microenvironment. We found that microglial density, phagocytic capacity, and their proximity to neurons were not altered in T2DM patients, indicating that the loss of Oxt neurons is independent of changes in microglial immunity. However, we did observe a reduction in the number of astrocytes, which are crucial for providing trophic support to local neurons. Moreover, a specific subpopulation of astrocytes characterized by aquaporin 4 expression was overrepresented in T2DM patients. Since this subset of astrocytes is linked to the glymphatic system, their overrepresentation might point to alterations in the hypothalamic waste clearance system in T2DM. Our study shows selective loss of Oxt neurons in the PVN of T2DM individuals in association with astrocytic reduction and gliovascular remodelling. Therefore, hypothalamic Oxt neurons may represent a potential target for T2DM treatment modalities.

The role of transducin ß-like 1 X-linked receptor 1 (TBL1XR1) in thyroid hormone metabolism and action in mice.

Transducin ß-like 1 X-linked receptor 1 (TBL1XR1) is a WD40 repeat-containing protein and part of the corepressor complex SMRT/NCoR that binds to the thyroid hormone receptor (TR). We recently described a mutation in TBL1XR1 in patients with Pierpont syndrome. A mouse model bearing this Tbl1xr1 mutation (Tbl1xr1Y446C/Y446C ) displays several aspects of the Pierpont phenotype. Although serum thyroid hormone (TH) concentrations were unremarkable in these mice, tissue TH action might be affected due to the role of TBL1XR1 in the SMRT/NCoR corepressor complex. The aim of the present study was to evaluate tissue TH metabolism and action in a variety of tissues of Tbl1xr1Y446C/Y446C mice. We studied the expression of genes involved in TH metabolism and action in tissues of naïve Tbl1xr1Y446C/Y446C mice and wild type (WT) mice. In addition, we measured deiodinase activity in liver (Dio1 and Dio3), kidney (Dio1 and Dio3) and BAT (Dio2). No striking differences were observed in the liver, hypothalamus, muscle and BAT between Tbl1xr1Y446C/Y446C and WT mice. Pituitary TRα1 mRNA expression was lower in Tbl1xr1Y446C/Y446C mice compared to WT, while the mRNA expression of Tshß and the positively T3-regulated gene Nmb were significantly increased in mutant mice. Interestingly, Mct8 expression was markedly higher in WAT and kidney of mutants, resulting in (subtle) changes in T3-regulated gene expression in both WAT and kidney. In conclusion, mice harboring a mutation in TBL1XR1 display minor changes in cellular TH metabolism and action. TH transport via MCT8 might be affected as the expression is increased in WAT and kidney. The mechanisms involved need to be clarified.

Nasal oxytocin administration does not influence eye gaze or perceived relationship of male volunteers with physicians in a simulated online consultation: a randomized, placebo-controlled trial.

The patient-physician relationship is a critical determinant of patient health outcomes. Verbal and non-verbal communication, such as eye gaze, are vital aspects of this bond. Neurobiological studies indicate that oxytocin may serve as a link between increased eye gaze and social bonding. Therefore, oxytocin signaling could serve as a key factor influencing eye gaze as well as the patient-physician relationship. We aimed to test the effects of oxytocin on gaze to the eyes of the physician and the patient-physician relationship by conducting a randomized placebo-controlled crossover trial in healthy volunteers with intranasally administered oxytocin (with a previously effective single dose of 24 IU, EudraCT number 2018-004081-34). The eye gaze of 68 male volunteers was studied using eye tracking during a simulated video call consultation with a physician, who provided information about vaccination against the human papillomavirus. Relationship outcomes, including trust, satisfaction, and perceived physician communication style, were measured using questionnaires and corrected for possible confounds (social anxiety and attachment orientation). Additional secondary outcome measures for the effect of oxytocin were recall of information and pupil diameter and exploratory outcomes included mood and anxiety measures. Oxytocin did not affect the eye-tracking parameters of volunteers' gaze toward the eyes of the physician. Moreover, oxytocin did not affect the parameters of bonding between volunteers and the physician nor other secondary and exploratory outcomes in this setting. Bayesian hypothesis testing provided evidence for the absence of effects. These results contradict the notion that oxytocin affects eye gaze patterns or bonding.

The role of WD40 repeat-containing proteins in endocrine (dys)function.

WD40 repeat-containing proteins play a key role in many cellular functions including signal transduction, protein degradation, and apoptosis. The WD40 domain is highly conserved, and its typical structure is a ß-propeller consisting of 4-8 blades which probably serves as a scaffold for protein-protein interaction. Some WD40 repeat-containing proteins form part of the corepressor complex of nuclear hormone receptors, a family of ligand-dependent transcription factors that play a central role in the regulation of gene transcription. This explains their involvement in endocrine physiology and pathology. In the present review, we first touch upon the structure of WD40 repeat-containing proteins. Next, we describe our current understanding of the role of WD40 domain-containing proteins in nuclear receptor signaling, e.g., as corepressor or coactivator. In the final part of this review, we focus on WD40 domain-containing proteins that are associated with endocrine pathologies. These pathologies vary from isolated dysfunction of one endocrine axis, e.g., congenital isolated central hypothyroidism, to more complex congenital syndromes comprising endocrine phenotypes, such as the Triple-A syndrome.

Hypothyroidism: The difficulty in attributing symptoms to their underlying cause.

Common symptoms of overt hypothyroidism are non-specific and include fatigue, lethargy, and dry skin. Although the diagnosis is considered to be straightforward, no single symptom can be used to identify patients with overt hypothyroidism, while many patients with subclinical hypothyroidism are asymptomatic. A large population-based study on the spectrum of symptoms in subclinical hypothyroidism showed similar rates of thyroid disease-related symptoms compared with euthyroid subjects, while the TSH concentration had no impact on symptom score. Together, these findings make it challenging to attribute symptoms to their underlying cause. This is also true in the case of unexplained persistent symptoms in levothyroxine-treated patients. Although generally considered a life-long replacement therapy, successful thyroid hormone discontinuation resulting in euthyroidism has been reported in approximately one third of patients. Thus, we overtreat patients with (subclinical) hypothyroidism, highlighting the importance of reliable diagnostic criteria. The diagnostic process, including the implementation of robust TSH and FT4 reference intervals, is especially challenging in specific situations including aging, pregnancy, non-thyroidal illness, and central hypothyroidism. There is a clear need for improved adherence to current guidelines from scientific societies and for willingness to manage symptoms without a clear pathological correlate, especially in the case of mild TSH elevations. This review will highlight recent literature on this topic and offers some practice points.

Compression of the optic chiasm is associated with reduced photoentrainment of the central biological clock.

Objective: Pituitary tumours that compress the optic chiasm are associated with long-term alterations in sleep-wake rhythm. This may result from damage to intrinsically photosensitive retinal ganglion cells (ipRGCs) projecting from the retina to the hypothalamic suprachiasmatic nucleus via the optic chiasm to ensure photoentrainment (i.e. synchronisation to the 24-h solar cycle through light). To test this hypothesis, we compared the post-illumination pupil response (PIPR), a direct indicator of ipRGC function, between hypopituitarism patients with and without a history of optic chiasm compression. Design: Observational study, comparing two predefined groups. Methods: We studied 49 patients with adequately substituted hypopituitarism: 25 patients with previous optic chiasm compression causing visual disturbances (CC+ group) and 24 patients without (CC- group). The PIPR was assessed by chromatic pupillometry and expressed as the relative change between baseline and post-blue-light stimulus pupil diameter. Objective and subjective sleep parameters were obtained using polysomnography, actigraphy, and questionnaires. Results: Post-blue-light stimulus pupillary constriction was less sustained in CC+ patients compared with CC- patients, resulting in a significantly smaller extended PIPR (mean difference: 8.1%, 95% CI: 2.2-13.9%, P = 0.008, Cohen's d = 0.78). Sleep-wake timing was consistently later in CC+ patients, without differences in sleep duration, efficiency, or other rest-activity rhythm features. Subjective sleep did not differ between groups. Conclusion: Previous optic chiasm compression due to a pituitary tumour in patients with hypopituitarism is associated with an attenuated PIPR and delayed sleep timing. Together, these data suggest that ipRGC function and consequently photoentrainment of the central biological clock is impaired in patients with a history of optic chiasm compression.

An animal model for Pierpont syndrome: a mouse bearing the Tbl1xr1Y446C/Y446C mutation.

Pierpont syndrome is a rare disorder characterized mainly by global developmental delay, unusual facial features, altered fat distribution in the limbs and hearing loss. A specific mutation (p.Tyr446Cys) in TBL1XR1, encoding a WD40 repeat-containing protein, which is a component of the SMRT/NCoR (silencing mediator retinoid and thyroid hormone receptors/nuclear receptor corepressors), has been reported as the genetic cause of Pierpont syndrome. Here, we used CRISPR-cas9 technology to generate a mutant mouse with the Y446C mutation in Tbl1xr1, which is also present in Pierpont syndrome. Several aspects of the phenotype were studied in the mutant mice: growth, body composition, hearing, motor behavior, thyroid hormone state and lipid and glucose metabolism. The mutant mice (Tbl1xr1Y446C/Y446C) displayed delayed growth, altered body composition with increased relative lean mass and impaired hearing. Expression of several genes involved in fatty acid metabolism differed in white adipose tissue, but not in liver or muscle of mutant mice compared to wild-type mice (Tbl1xr1+/+). No difference in thyroid hormone plasma concentrations was observed. Tbl1xr1Y446C/Y446C mice can be used as a model for distinct features of Pierpont syndrome, which will enable future studies on the pathogenic mechanisms underlying the various phenotypic characteristics.

Loss of Microglial Insulin Receptor Leads to Sex-Dependent Metabolic Disorders in Obese Mice.

Obesity and type 2 diabetes mellitus (T2DM) are highly prevalent disorders, associated with insulin resistance and chronic inflammation. The brain is key for energy homeostasis and contains many insulin receptors. Microglia, the resident brain immune cells, are known to express insulin receptors (InsR) and to be activated by a hypercaloric environment. The aim of this study was to evaluate whether microglial insulin signaling is involved in the control of systemic energy homeostasis and whether this function is sex-dependent. We generated a microglia-specific knockout of the InsR gene in male and female mice and exposed them to control or obesogenic dietary conditions. Following 10 weeks of diet exposure, we evaluated insulin tolerance, energy metabolism, microglial morphology and phagocytic function, and neuronal populations. Lack of microglial InsR resulted in increased plasma insulin levels and insulin resistance in obese female mice. In the brain, loss of microglial InsR led to a decrease in microglial primary projections in both male and female mice, irrespective of the diet. In addition, in obese male mice lacking microglial InsR the number of proopiomelanocortin neurons was decreased, compared to control diet, while no differences were observed in female mice. Our results demonstrate a sex-dependent effect of microglial InsR-signaling in physiology and obesity, and stress the importance of a heterogeneous approach in the study of diseases such as obesity and T2DM.

Levothyroxine in euthyroid thyroid peroxidase antibody positive women with recurrent pregnancy loss (T4LIFE trial): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial.

BACKGROUND: Women positive for thyroid peroxidase antibodies (TPO-Ab) have a higher risk of recurrent pregnancy loss. Evidence on whether levothyroxine treatment improves pregnancy outcomes in women who are TPO-Ab positive women with recurrent pregnancy loss is scarce. The aim of this study was to determine if levothyroxine increases live birth rates in women who were TPO-Ab positive with recurrent pregnancy loss and normal thyroid function. METHODS: The T4LIFE trial was an international, double-blind, placebo-controlled, phase 3 study done in 13 secondary and tertiary hospitals in the Netherlands, one tertiary hospital in Belgium, and one tertiary hospital in Denmark. Women (18-42 years) who were TPO-Ab positive, had two or more pregnancy losses, and had a thyroid stimulating hormone (TSH) concentration within the institutional reference range were eligible for inclusion. Women were excluded if they had antiphospholipid syndrome (lupus anticoagulant, anticardiolipin IgG or IgM antibodies, or ß2-glycoprotein-I IgG or IgM antibodies), other autoimmune diseases, thyroid disease, previous enrolment in this trial, or contraindications for levothyroxine use. Before conception, women were randomly assigned (1:1) to receive either levothyroxine or placebo orally once daily. The daily dose of levothyroxine was based on preconception TSH concentration and ranged from 0·5-1·0 µg/kg bodyweight. Levothyroxine or placebo was continued until the end of pregnancy. The primary outcome was live birth, defined as the birth of a living child beyond 24 weeks of gestation measured in the intention-to-treat population. The trial was registered within the Netherlands Trial Register, NTR3364 and with EudraCT, 2011-001820-39. RESULTS: Between Jan 1, 2013, and Sept 19, 2019, 187 women were included in the study: 94 (50%) were assigned to the levothyroxine group and 93 (50%) were assigned to the placebo group. The trial was prematurely stopped when 187 (78%) of the 240 predefined patients had been included because of slow recruitment. 47 (50%) women in the levothyroxine group and 45 (48%) women in the placebo group had live births (risk ratio 1·03 [95% CI 0·77 to 1·38]; absolute risk difference 1·6% [95% CI -12·7 to 15·9]). Seven (7%) women in the levothyroxine group and seven (8%) in the placebo group reported adverse events, none of them were directly related to the study procedure. INTERPRETATION: Compared with placebo, levothyroxine treatment did not result in higher live birth rates in euthyroid women with recurrent pregnancy loss who were positive for TPO-Ab. On the basis of our findings, we do not advise routine use of levothyroxine in women who are TPO-Ab positive with recurrent pregnancy loss and normal thyroid function. FUNDING: Dutch Organization for Health Research and Development, Fonds NutsOhra, Dutch Patient Organization of Thyroid Disorders, the Jan Dekkerstichting and Dr Ludgardine Bouwmanstichting, and a personal donation through the Dutch Patient Organization of Thyroid Disorders.

Levothyroxine use and the risk of colorectal cancer: a large population-based case-control study.

Objective: Whether an association between oral levothyroxine use, leading to supraphysiological exposure of the colon to thyroid hormones, and risk of colorectal cancer exists in humans is unclear. We therefore aimed to assess whether the use of levothyroxine is associated with a reduced risk of colorectal cancer in a linked cohort of pharmacy and cancer data. Design: Population-based matched case-control study. Methods: A total of 28,121 patients diagnosed with colorectal cancer between 1998 and 2014 were matched to 106,086 controls. Multivariable logistic regression was used to estimate the association between levothyroxine use and occurrence of colorectal cancer, adjusted for potential confounders. Results were stratified by gender, age, tumour subtype, and staging, as well as treatment duration and dosing. Results: A total of 1066 colorectal cancer patients (4%) and 4024 (4%) controls had used levothyroxine at any point before index date (adjusted odds ratio 0.95 (0.88-1.01)). Long-term use of levothyroxine was seen in 323 (30%) colorectal cancer patients and 1111 (28%) controls (adjusted odds ratio 1.00 (0.88-1.13)). Stratification by tumour subsite showed a borderline significant risk reduction of rectal cancer, while this was not seen for proximal colon cancer or distal colon cancer. There was no relationship with treatment duration or with levothyroxine dose. Conclusions: In this study, no reduced risk of colorectal cancer was seen in levothyroxine users. When stratifying by tumour subsite, a borderline significant risk reduction of rectal cancer was found and may warrant further research.

Congenital isolated central hypothyroidism: Novel mutations and their functional implications.

Congenital hypothyroidism is the most frequent endocrine disorder in newborns, occurring in 1 per 3000-4000 newborns. In the Netherlands, the neonatal screening program is based primarily on heel prick thyroxine (T4). In contrast to thyroid-stimulating hormone-based programs, this approach allows for the detection of both primary and central congenital hypothyroidism. Over the past decade, the identification of families with isolated congenital central hypothyroidism enabled the identification of novel genetic causes of this condition, in addition to mutations in the TSHß-subunit gene and thyrotropin-releasing hormone receptor gene reported earlier. In 2012, loss-of-function mutations in the immunoglobulin superfamily, member 1 (IGSF1) gene, were reported as a genetic cause of a syndrome including X-linked congenital central hypothyroidism and adult macroorchidism. IGSF1 encodes a hypothalamic plasma membrane glycoprotein. Mutations in IGSF1 represent the most prevalent genetic cause of isolated central hypothyroidism to date. In 2016, mutations in the transducin ß-like 1X (TBL1X) gene were identified in patients with a combination of mild central hypothyroidism and sensorineural hearing loss. TBL1X is an essential subunit of the NCoR/SMRT corepressor complex and expressed in many tissues including the human hypothalamus and pituitary. In 2018, mutations in the insulin receptor substrate 4 (IRS4) gene were reported in cases of familial isolated central hypothyroidism. IRS4 encodes a hypothalamic protein that is part of the insulin and leptin signaling cascade. These recent developments will broaden our understanding of the role of the hypothalamus in hypothalamus-pituitary-thyroid axis regulation and will help to improve diagnosis and treatment of isolated central hypothyroidism.