Three-Dimensional Computed Tomography Reconstructions May Detect Pincer Lesions With Higher Sensitivity Than Radiographs in Patients With Femoroacetabular Impingement Syndrome.

Purpose: To assess the diagnostic capability of radiographs (XRs) to detect pincer lesions compared with 3-dimensional (3D) computed tomography scans in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS). Methods: We performed a retrospective review of all patients who underwent hip arthroscopy for FAIS between September 1, 2020, and October 2, 2022. Preoperative imaging was reviewed. Pincer lesions were defined as a lateral center-edge angle greater than 40°; a Tönnis angle greater than 0°; the presence of the ischial spine, crossover, or posterior wall sign; and the presence of overcoverage greater than 80%. Under "select criteria," patients were classified as having a pincer lesion on XRs and 3D computed tomography reconstructions (CTRs) based on the lateral center-edge angle or Tönnis angle alone, whereas "all criteria" added the presence of the crossover sign and coverage percentage. Statistical analysis was performed to determine the diagnostic accuracy of XRs compared with 3D CTRs. Results: A total of 69 patients met the inclusion criteria. There were 21 male patients (30.4%) and 48 female patients (69.6%). The mean age was 33 ± 13.5 years. χ2 Analysis for select criteria found that 3D CTR was more likely than XRs to detect a pincer lesion. χ2 Analysis for all criteria found that 3D CTR was more likely than XRs to detect a pincer lesion. χ2 Analysis further showed that when using XRs, a pincer lesion was more likely to be detected under all criteria than under select criteria. Likewise, when using 3D CTR, a pincer lesion was more likely to be detected under all criteria than under select criteria. Conclusions: In this study, we found that 3D CTR detected pincer lesions in patients undergoing hip arthroscopy for FAIS with significantly higher sensitivity than XRs alone. Level of Evidence: Level III, retrospective cohort study.

Preoperative corticosteroid injections are associated with a higher periprosthetic infection rate following primary total shoulder arthroplasty: a systematic review and meta-analysis.

BACKGROUND: Corticosteroid injections (CSIs) are commonly used for the treatment of shoulder pain in patients with osteoarthritis and rotator cuff arthropathy. These injections may increase the risk of infection following eventual shoulder arthroplasty. The purpose of this study was to perform a systematic review and meta-analysis of existing data to explore the relationship between preoperative CSI's and postoperative periprosthetic joint infection (PJI) following shoulder arthroplasty. METHODS: A literature search was performed on PubMed, Embase, and Web of Science databases through September 29, 2023. Of the 4221 retrieved, 7 studies including 136,233 patients were included for qualitative analysis. Studies describing patients receiving CSI prior to shoulder arthroplasty and the effect on postoperative infection risk were included in the systematic review and subsequent meta-analysis. Assessment of risk of bias was performed using the Methodological Index for Non-Randomized Studies (MINORS) criteria. RESULTS: Receiving a CSI prior to shoulder arthroplasty was found to have a statistically significant association with increased risk for PJI (odds ratio [OR]: 1.13; 95% confidence interval [CI]: 1.06-1.19; P < .0001). The rate of PJI increased when injections were given closer to the time of surgery. Patients who received an injection at any time point before surgery had a 5.4% risk of PJI compared to 7.9% and 9.0% in patients receiving an injection within 3 months and 1 month of surgery, respectively. This time dependent association however did not reach statistical significance: 1 month OR 1.48; 95% Cl: 0.86-2.53; P = .16, 3 months OR 1.95; 95% Cl: 0.95-4.00; P = .07. CONCLUSION: The results of this systematic review and meta-analysis demonstrate that patients receiving corticosteroid shoulder injections prior to shoulder arthroplasty may be at an increased risk for PJI postoperatively. While time dependent stratification did not reach statistical significance, our findings indicate a clear trend of increased risk for patients receiving injections closer to surgery.

Development and validation of a surgical planning tool for bone-conduction implants.

Background: The BONEBRIDGE® (Med-El GmbH) is a bone-conduction device comprising an external audio processor and an internal Bone Conduction-Floating Mass Transducer (BC-FMT) surgically anchored to the temporal bone. Due to the implant's size, its placement may be challenging in certain anatomies, necessitating thorough surgical planning. Manual planning methods are laborious, time-intensive, and prone to errors. This study aimed to develop and validate an automated algorithm for determining skull thickness, aiding in the surgical planning of the BONEBRIDGE and other devices requiring similar bone thickness estimations. Materials and methods: Twelve cadaveric temporal bones underwent clinical computed tomography (CT). A custom Python algorithm was developed to automatically segment bone from soft tissue, generate 3D models, and perform ray-tracing to estimate bone thickness. Two thickness colormaps were generated for each sample: the cortical thickness to the first air cell and the total thickness down to the dura. The algorithm was validated against expert manual measurements to achieve consensus interpretation. Results: The algorithm estimated bone-to-air thicknesses (mean = 4.7 mm, 95% Confidence Interval [CI] of 4.3-5.0 mm) that closely matched the expert measurements (mean = 4.7 mm, CI of 4.4-5.0 mm), with a mean absolute difference (MAD) of 0.3 mm. Similarly, the algorithm's estimations to the dura (6.0 mm, CI of 5.4-6.5 mm) were comparable to the expert markings (5.9 mm, CI of 5.4-6.5 mm), with a MAD of 0.3 mm. Conclusions: The first automated algorithm to calculate skull thickness to both the air cells and dura in the temporal bone was developed. Colormaps were optimized to aid with the surgical planning of BONEBRIDGE implantation, however the tool can be generalized to aid in the surgical planning of any bone thickness application. The tool was published as a freely available extension to the open-source 3D Slicer software program (www.slicer.org).

Healthcare provider perspectives on delivering next generation rotavirus vaccines in five low-to-middle-income countries.

BACKGROUND: Live oral rotavirus vaccines (LORVs) have significantly reduced rotavirus hospitalizations and deaths worldwide. However, LORVs are less effective in low- and middle-income countries (LMICs). Next-generation rotavirus vaccines (NGRVs) may be more effective but require administration by injection or a neonatal oral dose, adding operational complexity. Healthcare providers (HPs) were interviewed to assess rotavirus vaccine preferences and identify delivery issues as part of an NGRV value proposition. OBJECTIVE: Determine HP vaccine preferences about delivering LORVs compared to injectable (iNGRV) and neonatal oral (oNGRV) NGRVs. METHODS: 64 HPs from Ghana, Kenya, Malawi, Peru, and Senegal were interviewed following a mixed-method guide centered on three vaccine comparisons: LORV vs. iNGRV; LORV vs. oNGRV; oNGRV vs. iNGRV. HPs reviewed attributes for each vaccine in the comparisons, then indicated and explained their preference. Additional questions elicited views about co-administering iNGRV+LORV for greater public health impact, a possible iNGRV-DTP-containing combination vaccine, and delivering neonatal doses. RESULTS: Almost all HPs preferred oral vaccine options over iNGRV, with many emphasizing an aversion to additional injections. Despite this strong preference, HPs described challenges delivering oral doses. Preferences for LORV vs. oNGRV were split, marked by disparate views on rotavirus disease epidemiology and the safety, need, and feasibility of delivering neonatal vaccines. Although overwhelmingly enthusiastic about an iNGRV-DTP-containing combination option, several HPs had concerns. HP views were divided on the feasibility of co-administering iNGRV+LORV, citing challenges around logistics and caregiver sensitization. CONCLUSION: Our findings provide valuable insights on delivering NGRVs in routine immunization. Despite opposition to injectables, openness to co-administering LORV+iNGRV to improve efficacy suggests future HP support of iNGRV if adequately informed of its advantages. Rationales for LORV vs. oNGRV underscore needs for training on rotavirus epidemiology and stronger service integration. Expressed challenges delivering existing LORVs merit further examination and indicate need for improved delivery.

National stakeholder preferences for next-generation rotavirus vaccines: Results from a six-country study.

BACKGROUND: Currently available live, oral rotavirus vaccines (LORVs) have significantly reduced severe rotavirus hospitalizations and deaths worldwide. However, LORVs are not as effective in low- and middle-income countries (LMIC) where rotavirus disease burden is highest. Next-generation rotavirus vaccine (NGRV) candidates in development may have a greater public health impact where they are needed most. The feasibility and acceptability of possible new rotavirus vaccines were explored as part of a larger public health value proposition for injectable NGRVs in LMICs. OBJECTIVE: To assess national stakeholder preferences for currently available LORVs and hypothetical NGRVs and understand rationales and drivers for stated preferences. METHODS: Interviews were conducted with 71 national stakeholders who influence vaccine policy and national programming. Stakeholders from Ghana, Kenya, Malawi, Peru, Senegal, and Sri Lanka were interviewed using a mixed-method guide. Vaccine preferences were elicited on seven vaccine comparisons involving LORVs and hypothetical NGRVs based on information presented comparing the vaccines' attributes. Reasons for vaccine preference were elicited in open-ended questions, and the qualitative data were analyzed on key preference drivers. RESULTS: Nearly half of the national stakeholders interviewed preferred a highly effective standalone, injectable NGRV over current LORVs. When presented as having similar efficacy to the LORV, however, very few stakeholders preferred the injectable NGRV, even at substantially lower cost. Similarly, a highly effective standalone injectable NGRV was generally not favored over an equally effective oral NGRV following a neonatal-infant schedule, despite higher cost of the neonatal option. An NGRV-DTP-containing combination vaccine was strongly preferred over all other options, whether delivered alone with efficacy similar to current LORVs or co-administered alongside an LORV (LORV + NGRV-DTP) to increase efficacy. CONCLUSION: Results from these national stakeholder interviews provide valuable insights to inform ongoing and future NGRV research and development.

Impact of Estrogens on the Regulation of White, Beige, and Brown Adipose Tissue Depots.

As adipose tissue depots are active endocrine organs, they secrete a variety of hormones (including estrogens from white adipose) and inflammatory mediators, which have important implications in numerous obesity-associated diseases. Adipose tissues are broadly characterized as consisting of white, beige, and brown depot types. The endocrine, metabolic, and inflammatory profiles of adipose are depot dependent and influenced by the estrogenic and androgenic status of the adipose tissue. Estrogen receptors mediate both the genomic and nongenomic actions of estrogens and are expressed in the brain, heart, and other peripheral tissues. All three known estrogen receptor α (ERα) and estrogen receptor ß (ERß), and the G-protein coupled estrogen receptor (GPER/GPR30) are expressed in white adipose and can modulate adipose mass. Expression of each receptor is dependent on depot location, adipose cell type, and estrogen levels. Estrogen receptor expression profiles in beige and brown adipocytes are less well established. This review will discuss the effects of estrogens on the differential deposition of the major adipose tissues and the impact of estrogens within white adipose depots. © 2019 American Physiological Society. Compr Physiol 9:457-475, 2019.

Lessons learned from the Advancing Maternal Immunization collaboration: identifying evidence gaps for informed respiratory syncytial virus maternal immunization decision-making.

In an increasingly crowded vaccine landscape, global and country decision-makers will require evidence-based and disease-specific information when prioritizing new public health interventions. The Advancing Maternal Immunization collaboration (AMI) was designed to develop a cross-program strategy to advance respiratory syncytial virus (RSV) maternal immunization (MI) availability and accessibility in low- and middle-income countries by completing a comprehensive RSV MI gap analysis and developing an actionable roadmap report. By engaging and coordinating key stakeholders using a web-based communication platform and developing standardized tools, AMI was able to facilitate interaction and consensus between members. This paper describes the methodology used to create and manage AMI's work. We share lessons learned from our approach to inform other groups conducting similar work requiring cross-sectoral engagement. This approach could be adapted to efficiently conduct gap analyses for other health interventions that require input and coordination across a variety of topic areas, disciplines, geographies, and stakeholders.

History of Estrogen: Its Purification, Structure, Synthesis, Biologic Actions, and Clinical Implications.

This mini-review summarizes key points from the Clark Sawin Memorial Lecture on the History of Estrogen delivered at Endo 2018 and focuses on the rationales and motivation leading to various discoveries and their clinical applications. During the classical period of antiquity, incisive clinical observations uncovered important findings; however, extensive anatomical dissections to solidify proof were generally lacking. Initiation of the experimental approach followed later, influenced by Claude Bernard's treatise "An Introduction to the Study of Experimental Medicine." With this approach, investigators began to explore the function of the ovaries and their "internal secretions" and, after intensive investigations for several years, purified various estrogens. Clinical therapies for hot flashes, osteoporosis, and dysmenorrhea were quickly developed and, later, methods of hormonal contraception. Sophisticated biochemical methods revealed the mechanisms of estrogen synthesis through the enzyme aromatase and, after discovery of the estrogen receptors, their specific biologic actions. Molecular techniques facilitated understanding of the specific transcriptional and translational events requiring estrogen. This body of knowledge led to methods to prevent and treat hormone-dependent neoplasms as well as a variety of other estrogen-related conditions. More recently, the role of estrogen in men was uncovered by prismatic examples of estrogen deficiency in male patients and by knockout of the estrogen receptor and aromatase in animals. As studies became more extensive, the effects of estrogen on nearly every organ were described. We conclude that the history of estrogen illustrates the role of intellectual reasoning, motivation, and serendipity in advancing knowledge about this important sex steroid.

SCA-1 Labels a Subset of Estrogen-Responsive Bipotential Repopulating Cells within the CD24+ CD49fhi Mammary Stem Cell-Enriched Compartment.

Estrogen stimulates breast development during puberty and mammary tumors in adulthood through estrogen receptor-α (ERα). These effects are proposed to occur via ERα+ luminal cells and not the mammary stem cells (MaSCs) that are ERαneg. Since ERα+ luminal cells express stem cell antigen-1 (SCA-1), we sought to determine if SCA-1 could define an ERα+ subset of EpCAM+/CD24+/CD49fhi MaSCs. We show that the MaSC population has a distinct SCA-1+ population that is abundant in pre-pubertal mammary glands. The SCA-1+ MaSCs have less stem cell markers and less in vivo repopulating activity than their SCA-1neg counterparts. However, they express ERα and specifically enter the cell cycle at puberty. Using estrogen-deficient aromatase knockouts (ArKO), we showed that the SCA-1+ MaSC could be directly modulated by estrogen supplementation. Thus, SCA-1 enriches for an ERα+, estrogen-sensitive subpopulation within the CD24+/CD49fhi MaSC population that may be responsible for the hormonal sensitivity of the developing mammary gland.

Sexual dimorphism in the glucose homeostasis phenotype of the Aromatase Knockout (ArKO) mice.

We investigated the effects of estrogens on glucose homeostasis using the Aromatase Knockout (ArKO) mouse, which is unable to convert androgens into estrogens. The ArKO mouse is a model of total estrogen ablation which develops symptoms of metabolic syndrome. To determine the development and progression of whole body state of insulin resistance of ArKO mice, comprehensive whole body tolerance tests were performed on WT, ArKO and estrogen administrated mice at 3 and 12 months of age. The absence of estrogens in the male ArKO mice leads to hepatic insulin resistance, glucose and pyruvate intolerance from 3 to 12 months with consistent improvement upon estrogen treatment. Estrogen absence in the female ArKO mice leads to glucose intolerance without pyruvate intolerance or insulin resistance. The replacement of estrogens in the female WT and ArKO mice exhibited both insulin sensitizing and resistance effects depending on age and dosage. In conclusion, this study presents information on the sexually dimorphic roles of estrogens on glucose homeostasis regulation.

Suppression of Sertoli cell tumour development during the first wave of spermatogenesis in inhibin α-deficient mice.

A dynamic partnership between follicle-stimulating hormone (FSH) and activin is required for normal Sertoli cell development and fertility. Disruptions to this partnership trigger Sertoli cells to deviate from their normal developmental pathway, as observed in inhibin α-knockout (Inha-KO) mice, which feature Sertoli cell tumours in adulthood. Here, we identified the developmental windows by which adult Sertoli cell tumourigenesis is most FSH sensitive. FSH was suppressed for 7 days in Inha-KO mice and wild-type littermates during the 1st, 2nd or 4th week after birth and culled in the 5th week to assess the effect on adult Sertoli cell development. Tumour growth was profoundly reduced in adult Inha-KO mice in response to FSH suppression during Weeks 1 and 2, but not Week 4. Proliferative Sertoli cells were markedly reduced in adult Inha-KO mice following FSH suppression during Weeks 1, 2 or 4, resulting in levels similar to those in wild-type mice, with greatest effect observed at the 2 week time point. Apoptotic Sertoli cells increased in adult Inha-KO mice after FSH suppression during Week 4. In conclusion, acute FSH suppression during the 1st or 2nd week after birth in Inha-KO mice profoundly suppresses Sertoli cell tumour progression, probably by inhibiting proliferation in the adult, with early postnatal Sertoli cells being most sensitive to FSH action.

Inflammation, dysregulated metabolism and aromatase in obesity and breast cancer.

Obesity is associated with an increased risk of estrogen-dependent breast cancer after menopause. Adipose tissue undergoes important changes in obesity due to excess storage of lipids, leading to adipocyte cell death and the recruitment of macrophages. The resultant state of chronic low-grade inflammation is associated with the activation of NFkB signaling and elevated levels of aromatase, the rate-limiting enzyme in estrogen biosynthesis. This occurs not only in the visceral and subcutaneous fat, but also in the breast fat. The regulation of aromatase in the breast adipose stromal cell in response to inflammatory mediators is under the control of complex signaling pathways, including metabolic pathways involving LKB1/AMPK, p53, HIF1α and PKM2. Interventions aimed at modifying weight, including diet and exercise, are associated with changes in adipose tissue inflammation and estrogen production that are likely to impact breast cancer risk. This review will present an overview of these topics.

Caregiver perceptions and utilization of oral rehydration solution and other treatments for diarrhea among young children in Burkina Faso.

BACKGROUND: More than 500 000 young children die from dehydration caused by severe diarrhea each year, globally. Although routine use of oral rehydration solution (ORS) could prevent almost all of these deaths, ORS utilization remains low in many low-income countries. Previous research has suggested that misperceptions among caregivers may be an obstacle to wider use of ORS. METHODS: To better understand the extent of ORS utilization and the reasons for use or non-use in low-resource settings, the project team conducted a semi-structured, quantitative survey of 400 caregivers in Burkina Faso in 2014. All caregivers had a child below the age of five who had diarrhea lasting 2 days or more in the previous 2 months. RESULTS: Although more than 80% of caregivers were aware of ORS, less than half reported using it to treat their child's diarrhea. Replacing fluids lost due to diarrhea was considered a low priority by most caregivers, and many said they considered antibiotics more effective for treating diarrhea. Users and non-users of ORS held substantially different perceptions of the product, though all caregivers tended to follow recommendations of health care workers. A significant proportion of users reported difficulty in getting a child to drink ORS. Costs and access to ORS were not found to be significant barriers to use. CONCLUSIONS: Misperceptions among caregivers and health workers contribute to low utilization of ORS. Better caregiver understanding of diarrheal disease and the importance of rehydration, as well as increased recommendation by health workers, will help to increase ORS utilization. Improving product presentation and taste will also help to increase use.

Estrogens do not protect, but androgens exacerbate, collagen accumulation in the female mouse kidney after ureteric obstruction.

AIMS: Controversy surrounds the gender basis of progression in chronic kidney disease. Unfortunately, most experimental studies addressing this question do not distinguish between direct effects of estrogen and indirect activation of estrogen receptors through conversion of testosterone to 17ß-estradiol by aromatase. We examined the pathogenesis of renal fibrosis in female aromatase knockout (ArKO) mice, which lack circulating and stored estrogens, while having normal levels of testosterone. MAIN METHODS: ArKO mice and their wild-type (ArWT) counterparts were subjected to unilateral ureteric obstruction (UUO), with kidney tissue collected at day(D) 0, 3 and 9 post-UUO. Effects of 5α-dihydrotestosterone (DHT) administration on each genotype were also studied. Tissue was assessed biochemically and histochemically for fibrosis. Western blot analysis was used to measure α-smooth muscle actin (α-SMA) expression and TGF-ß1 signalling. Matrix metalloproteinase-2 (MMP-2) activity was measured by zymography. KEY FINDINGS: UUO increased collagen content over time (p<0.05 (D3) and p<0.01 (D9) vs day 0), with no difference between genotypes in qualitative (collagen IV staining) and quantitative (hydroxyproline concentration) analyses. Systemic administration of non-aromatizable DHT increased collagen content after 3days of UUO in both genotypes. This was not paralleled by any change in α-SMA (myofibroblast burden) or TGF-ß1 signalling but was commensurate with DHT reducing MMP2 activity in both genotypes (p<0.05 vs genotype controls). SIGNIFICANCE: Physiological concentrations of estrogens do not protect the injured kidney from fibrosis progression. Androgens rather than estrogens are the relevant factor involved in regulating disease-related renal scarring in this model.

Immunolocalisation of aromatase regulators liver kinase B1, phosphorylated AMP-activated protein kinase and cAMP response element-binding protein-regulated transcription co-activators in the human testis.

Although oestrogens are essential for spermatogenesis and their biosynthesis is dependent on aromatase expression, the molecular mechanism of aromatase regulation is poorly understood. Our laboratory has demonstrated that liver kinase B1 (LKB1) is a negative regulator of aromatase in the breast by phosphorylating AMP-activated protein kinase (AMPK) and inhibiting the nuclear translocation of the cAMP response element-binding protein-regulated transcription co-activator (CRTC) 2. The aim of this study was to determine the location of testis-associated proteins in the LKB1-CRTC pathway. Aromatase, LKB1, phosphorylated AMPK (pAMPK) and CRTC1-3 were examined by selected immunofluorescent antibodies in testis samples from a prepubertal boy and three fertile men. Aromatase, pAMPK and LKB1 proteins were present in the seminiferous epithelium and interstitium of the testis and were expressed in a differential and developmental manner in particular cell types. The expression pattern of LKB1 was similar to that of pAMPK and inversely related to aromatase expression. CRTC1 and CRTC3 were localised in the seminiferous epithelium, whereas CRTC2 was barely detectable in testis. These results lead to the conclusion that LKB1 is involved in the molecular pathway that underpins aromatase regulation in the testis via CRTC1 and CRTC3 and may be important for the oestrogen-mediated development of germ cells.

p53: Protection against Tumor Growth beyond Effects on Cell Cycle and Apoptosis.

The tumor suppressor p53 has established functions in cancer. Specifically, it has been shown to cause cell-cycle arrest and apoptosis in response to DNA damage. It is also one of the most commonly mutated or silenced genes in cancer and for this reason has been extensively studied. Recently, the role of p53 has been shown to go beyond its effects on cell cycle and apoptosis, with effects on metabolism emerging as a key contributor to cancer growth in situations where p53 is lost. Beyond this, the role of p53 in the tumor microenvironment is poorly understood. The publication by Wang and colleagues demonstrates for the first time that p53 is a key negative regulator of aromatase and, hence, estrogen production in the breast tumor microenvironment. It goes further by demonstrating that an important regulator of aromatase, the obesity-associated and tumor-derived factor prostaglandin E2, inhibits p53 in the breast adipose stroma. This review presents these findings in the context of established and emerging roles of p53 and discusses possible implications for the treatment of breast cancer.

Celebrating 75 years of oestradiol.

Oestrogens exert important effects on the reproductive as well as many other organ systems in both men and women. The history of the discovery of oestrogens, the mechanisms of their synthesis, and their therapeutic applications are very important components of the fabric of endocrinology. These aspects provide the rationale for highlighting several key components of this story. Two investigators, Edward Doisy and Alfred Butenandt, purified and crystalized oestrone nearly simultaneously in 1929, and Doisy later discovered oestriol and oestradiol. Butenandt won the Nobel Prize for this work and Doisy's had to await his purification of vitamin K. Early investigators quickly recognized that oestrogens must be synthesized from androgens and later investigators called this process aromatization. The aromatase enzyme was then characterized, its mechanism determined, and its structure identified after successful crystallization. With the development of knock-out methodology, the precise effects of oestrogen in males and females were defined and clinical syndromes of deficiency and excess described. Their discovery ultimately led to the development of oral contraceptives, treatment of menopausal symptoms, therapies for breast cancer, and induction of fertility, among others. The history of the use of oestrogens for postmenopausal women to relieve symptoms has been characterized by cyclic periods of enthusiasm and concern. The individuals involved in these studies, the innovative thinking required, and the detailed understanding made possible by evolving biologic and molecular techniques provide many lessons for current endocrinologists.

Effects of Estrogens on Adipokines and Glucose Homeostasis in Female Aromatase Knockout Mice.

The maintenance of glucose homeostasis within the body is crucial for constant and precise performance of energy balance and is sustained by a number of peripheral organs. Estrogens are known to play a role in the maintenance of glucose homeostasis. Aromatase knockout (ArKO) mice are estrogen-deficient and display symptoms of dysregulated glucose metabolism. We aim to investigate the effects of estrogen ablation and exogenous estrogen administration on glucose homeostasis regulation. Six month-old female wildtype, ArKO, and 17ß-estradiol (E2) treated ArKO mice were subjected to whole body tolerance tests, serum examination of estrogen, glucose and insulin, ex-vivo muscle glucose uptake, and insulin signaling pathway analyses. Female ArKO mice display increased body weight, gonadal (omental) adiposity, hyperinsulinemia, and liver triglycerides, which were ameliorated upon estrogen treatment. Tolerance tests revealed that estrogen-deficient ArKO mice were pyruvate intolerant hence reflecting dysregulated hepatic gluconeogenesis. Analyses of skeletal muscle, liver, and adipose tissues supported a hepatic-based glucose dysregulation, with a down-regulation of Akt phosphorylation (a key insulin signaling pathway molecule) in the ArKO liver, which was improved with E2 treatment. Concurrently, estrogen treatment lowered ArKO serum leptin and adiponectin levels and increased inflammatory adipokines such as tumour necrosis factor alpha (TNFα) and interleukin 6 (IL6). Furthermore, estrogen deficiency resulted in the infiltration of CD45 macrophages into gonadal adipose tissues, which cannot be reversed by E2 treatment. This study describes the effects of estrogens on glucose homeostasis in female ArKO mice and highlights a primary phenotype of hepatic glucose dysregulation and a parallel estrogen modified adipokine profile.

Aromatase overexpression in dysfunctional adipose tissue links obesity to postmenopausal breast cancer.

The number of breast cancer cases has increased in the last a few decades and this is believed to be associated with the increased prevalence of obesity worldwide. The risk of breast cancer increases with age beyond menopause and the relationship between obesity and the risk of breast cancer in postmenopausal women is well established. The majority of postmenopausal breast cancers are estrogen receptor (ER) positive and estrogens produced in the adipose tissue promotes tumor formation. Obesity results in the secretion of inflammatory factors that stimulate the expression of the aromatase enzyme, which converts androgens into estrogens in the adipose tissue. Evidence demonstrating a link between obesity and breast cancer has led to the investigation of metabolic pathways as novel regulators of estrogen production, including pathways that can be targeted to inhibit aromatase specifically within the breast. This review aims to present some of the key findings in this regard.