Association of adipokines and joint biomarkers with cartilage-modifying effects of weight loss in obese subjects

SummaryObjectivesTo determine (1) the effects of weight loss in obese subjects on six adipokines and joint biomarkers; and (2) the relationship between changes in these markers with changes in cartilage outcomes.DesignPlasma levels of adiponectin, leptin, IL-6, COMP, MMP-3 and urine levels of CTX-II were measured at baseline and 12 months from 75 obese subjects enrolled in two weight-loss programs. Magnetic resonance imaging (MRI) was used to assess cartilage volume and thickness. Associations between weight loss, cartilage outcomes and markers were adjusted for age, gender, baseline BMI, presence of clinical knee OA, with and without weight loss percent.ResultsMean weight loss was 13.0 ± 9.5%. Greater weight loss percentage was associated with an increase in adiponectin (β = 0.019, 95% CI 0.012 to 0.026,) and a decrease in leptin (β = −1.09, 95% CI −1.37 to −0.82). Multiple regression analysis saw an increase in adiponectin associated with reduced loss of medial tibial cartilage volume (β = 14.4, CI 2.6 to 26.3) and medial femoral cartilage volume (β = 18.1, 95% CI 4.4 to 31.8). Decrease in leptin was associated with reduced loss of medial femoral volume (β = −4.1, 95% CI −6.8 to −1.4) and lateral femoral volume (β = −1.8, 95% CI −3.7 to 0.0). When weight loss percent was included in the model, only the relationships between COMP and cartilage volume remained statistically significant.ConclusionsAdiponectin and leptin may be associated with cartilage loss. Further work will determine the relative contributions of metabolic and mechanical factors in the obesity-related joint changes

Peripheral Nerve Ultrasound for the Differentiation between ALS, Inflammatory, and Hereditary Polyneuropathies

Background and Objectives: Ultrasound (US) is a non-invasive tool for the in vivo detection of peripheral nerve alterations. Materials and Methods: In this study, we applied nerve US to assist the discrimination between the spectrum of amyotrophic lateral sclerosis (ALS, n = 11), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP, n = 5), and genetically confirmed Charcot–Marie–Tooth disease (CMT, n = 5). All participants and n = 15 controls without neurological diseases underwent high-resolution US of the bilateral tibial nerve. The nerve cross-sectional area (CSA) and nerve microvascular blood flow were compared between the groups and related to cerebrospinal fluid (CSF) measures, clinical symptoms, and nerve conduction studies. The analyses are part of a larger multimodal study on the comparison between US and 7 Tesla (7T) magnetic resonance neurography (MRN). Results: The patients and controls were matched with respect to their demographical data. CMT had the longest disease duration, followed by CIDP and ALS. CSA was related to age, weight, and disease duration. CSA was larger in CMT and CIDP compared to ALS and controls. The blood flow was greatest in CIDP, and higher than in CMT, ALS, and controls. In ALS, greater CSA was correlated with greater CSF total protein and higher albumin quotient. The US measures did not correlate with clinical scores or nerve conduction studies in any of the subgroups. Conclusion: Our results point towards the feasibility of CSA and blood flow to discriminate between ALS, CIDP, and CMT, even in groups of small sample size. In ALS, larger CSA could indicate an inflammatory disease subtype characterized by reduced blood–nerve barrier integrity. Our upcoming analysis will focus on the additive value of 7T MRN in combination with US to disentangle the spectrum between more inflammatory or more degenerative disease variants among the disease groups

Osteoblasts mediate the adverse effects of glucocorticoids on fuel metabolism

Long-term glucocorticoid treatment is associated with numerous adverse outcomes, including weight gain, insulin resistance, and diabetes; however, the pathogenesis of these side effects remains obscure. Glucocorticoids also suppress osteoblast function, including osteocalcin synthesis. Osteocalcin is an osteoblast-specific peptide that is reported to be involved in normal murine fuel metabolism. We now demonstrate that osteoblasts play a pivotal role in the pathogenesis of glucocorticoid-induced dysmetabolism. Osteoblast-targeted disruption of glucocorticoid signaling significantly attenuated the suppression of osteocalcin synthesis and prevented the development of insulin resistance, glucose intolerance, and abnormal weight gain in corticosterone-treated mice. Nearly identical effects were observed in glucocorticoid-treated animals following heterotopic (hepatic) expression of both carboxylated and uncarboxylated osteocalcin through gene therapy, which additionally led to a reduction in hepatic lipid deposition and improved phosphorylation of the insulin receptor. These data suggest that the effects of exogenous high-dose glucocorticoids on insulin target tissues and systemic energy metabolism are mediated, at least in part, through the skeleton.NHMRC Grants 402462 and 63281

Stress, glucocorticoids and bone: A review from mammals and fish

Glucocorticoids (GCs) are the final effector products of a neuroendocrine HPA/HPI axis governing energy balance and stress response in vertebrates. From a physiological point of view, basal GC levels are essential for intermediary metabolism and participate in the development and homeostasis of a wide range of body tissues, including the skeleton. Numerous mammalian studies have demonstrated that GC hormones exert a positive role during bone modeling and remodeling as they promote osteoblastogenesis to maintain the bone architecture. Although the pharmacological effect of the so-called stress hormones has been widely reported, the role of endogenous GCs on bone mineral metabolism as result of the endocrine stress response has been largely overlooked across vertebrates. In addition, stress responses are variable depending on the stressor (e.g., starvation, predation, and environmental change), life cycle events (e.g., migration and aging), and differ among vertebrate lineages, which react differently according to their biological, social and cognitive complexity (e.g., mineral demands, physical, and psychological stress). This review intends to summarize the endogenous GCs action on bone metabolism of mammals and fish under a variety of challenging circumstances. Particular emphasis will be given to the regulatory loop between GCs and the parathyroid hormone (PTH) family peptides, and other key regulators of mineral homeostasis and bone remodeling in vertebrates.Spanish Economy and Competitiveness Ministry projects [AGL2014-52473R, AGL2017-89648P]; Portuguese Foundation for Science and Technology [PTDC/BIA-ANM/4225/2012]info:eu-repo/semantics/publishedVersio

Glucocorticoid effects in the skeleton and the prostate

Die Wirkmechanismen von Glucocorticoiden (GC) im Knochen sowie in der Prostata sind bis dato nicht vollständig verstanden. Das Ziel der vorliegenden Arbeit war – neben der Validierung verschiedener Methoden zur Applikation von GC im Tiermodell – die Bestimmung des Einflusses des Osteoblasten auf die GC Wirkung im Knochen. Darüber hinaus wurde der Einfluss von GC auf Stroma- und Epithelzellen der Prostata charakterisiert. Methoden: Zunächst wurden die technischen Grundlagen zur chronischen Applikation von GC im Mausmodell untersucht. Hierzu wurden repetitive subkutane Injektionen, die Implantation subkutaner osmotischer Pumpen sowie die subkutane Implantation von slow- release Pellets verglichen. Nach Etablierung der optimalen Methodik (slow- release Pellet) folgte eine Serie von in-vivo Experimenten, mittels derer der Effekt von GC auf spezifische Knochenzellen untersucht wurde. Hierbei kamen sog. Col2.3-11ß-HSD2 transgene Mäuse zum Einsatz, bei denen GC auf Prä- Rezeptor-Ebene durch die selektive Überexpression des Enzyms 11ß–Hydroxysteroid–Dehydrogenase Typ 2 (11ß-HSD2) ausschließlich im Osteoblasten inaktiviert werden. Insgesamt wurden 44 Wildtyp und 42 transgene Tiere entweder mit 1,5mg/Woche Corticosteron oder Placebo für 4 Wochen behandelt. Anschließend wurden Tibia und Wirbelsäule mittels Micro-CT, Histologie, Histomorphometrie und Immunohistochemie analysiert. In einem zweiten Ansatz wurden außerdem Prostata, Testes und Vesiculae seminales auf histologischer Ebene untersucht. Ergebnisse: Die Implantation subkutaner slow- release Pellets führte zu einer chronischen und signifikanten Hypercorticosteronaemie in der Maus, wobei zum Erreichen prolongierter Effekte eine wöchentliche Re-Implantation der Pellets notwendig wurde. Wiederholte Injektionen oder die Implantationen GC-haltiger osmotischer Pumpen hatten dagegen keinen nachhaltigen Effekt auf die GC Serum Konzentration der Versuchstiere. Nach 4-wöchiger Behandlung mit GC Pellets konnte in der Tibia von WT Mäusen ein endocorticaler Verlust von Knochen beobachtet werden, jedoch kam es gleichzeitig zu einem pericorticalen Anbau von Knochensubstanz. In den Wirbelkörpern dieser Mäuse wurde dagegen ein Verlust corticaler Knochenmasse festgestellt. Interessanterweise führte die gleiche GC-Behandlung weder in der Tibia noch in der Wirbelsäule von transgenen Tieren zu einem signifikanten Verlust von trabekulärer Knochensubstanz. Nach der GC-Exposition imponierte in der anterioren Prostata (AP) der Maus eine deutliche Dysplasie des Epithels. Gleichzeitig konnte eine deutliche Induktion des GC-Rezeptors im Stroma - nicht aber im Epithel der AP - festgestellt werden. Weiterhin wurde im Stroma der AP eine deutlich erhöhte Expression von potentiell mutagenem Fibroblast Growth Factor (FGF) 2 und 10 als Folge der GC-Behandlung beobachtet. Im Gegensatz hierzu blieben ventrale sowie dorsolaterale Bereiche der Prostata von der Behandlung mit GC weitgehend unbeeinflusst. Fazit: 1\. Unter den getesteten Verfahren ist die wöchentliche Implantation subkutaner slow-release Pellets die beste Methode zur längerfristigen Induktion einer Hypercorticosteronaemie im Mausmodell. 2\. Osteoblasten sind das primäre Ziel von GC im Knochen. Im corticalen Knochen können exogenen GC in Abhängigkeit von der Lokalisation (Endo- vs. Pericortex) sowohl katabole als auch anabole Wirkungen entfalten. 3\. In der anterioren Prostata verursachen erhöhte Konzentrationen von GC eine selektive Epitheldysplasie, der möglicherweise ein FGF-vermitteltes, parakrines Signal des Stromas zugrunde liegt.Background: Glucocorticoid (GC) effects in bone and in the prostate are ill defined and the underlying molecular mechanisms of GC action in both tissues are not fully understood. The aim if this thesis is to (i) validate the in vivo application of GCs in a mouse model (ii) determine the effects of exogenous GCs on the skeleton as well as bone cells and (iii) characterise the GC effects on stromal and epithelial cells in the prostate. Methods: To validate the continuous administration of GC in mice the effectiveness of subcutaneous (s.c.) GC injections, GC pumps and slow-release GC pellets were compared. In order to examine the osteoblast specific effects of GC within the skeletal system, the GC-inactivating enzyme 11βHSD2 was transgenically overexpressed specifically in the osteoblast using the 2.3kb Col1A1-promoter. Employing the optimal method of GC delivery (s.c. slow-release pellets), eight week-old male transgenic (tg) and wild-type (WT) mice (n = 20–23/group) were treated with either 1.5 mg corticosterone (CS) or placebo for 4 weeks. At endpoint, bone quality of the tibia and the L3 vertebra was assessed via histomorphometry and micro-CT analysis. Prostate morphology was determined by histomorphometry and immunohistochemistry. Results: While both CS injections and pumps consistently failed to alter serum concentration of CS effectively, the weekly replacement of CS pellets induced a prolonged hypercorticosteronemia as well as continuous suppression of serum osteocalcin concentrations in mice. After 4 weeks of CS treatment WT mice revealed a loss of endocortical bone in the tibia along with an enlargement of the bone marrow cavity. In contrast, pericortical bone formation was increased resulting in an expansion of the pericortical area and maintenance of overall cortical bone mass in the tibia. In the spine GC exposure led to a significant reduction of cortical bone area and cortical thickness in WT mice, compromising bone quality at this site. In tg mice CS treatment did not affect structure and geometry of the vertebral or tibial cortex. Histological analysis of the anterior prostate showed an abnormal and highly disorganised luminal epithelium following CS treatment compared to placebo. Molecular analysis at this site revealed a CS-induced increase in the expression of fibroblastic growth factor (FGF) 10 and 2, together with prominent stromal GC receptor expression. While these CS-induced pathologies were prominent in the anterior prostate, the dorsolateral and ventral prostate remained largely unaffected. Conclusions: (i) Weekly replacement of s.c. slow-release GC pellets induces significant hypercorticosteronemia and – among the methods tested – was the most suitable technique for long-term delivery of GC in mice. (ii) Exogenous GCs at lower doses exert catabolic (endocortex) as well as anabolic (pericortex) effects in the cortical bone compartment via an osteoblast- dependent mechanism. (iii) In the anterior prostate, exposure to exogenous GCs induces significant epithelial dysplasia potentially mediated via aberrant stromal-to-epithelial FGF signalling

Glucocorticoid Signalling in Osteoblasts during Ageing and Chronic Stress

Glucocorticoid signalling in osteoblasts not only governs osteoblast differentiation and activity but also modulates the osteoblast’s endocrine function by modifying the synthesis and release of osteocalcin – a novel, bone-derived metabolic hormone. While glucocorticoid signalling in osteoblasts is generally well characterised, its role in the pathophysiology of chronic stress and ageing remains unexamined. In order to address this question I utilised a transgenic mouse model, in which glucocorticoid signalling was genetically disrupted specifically in osteoblasts and osteocytes via the overexpression of the glucocorticoid-inactivating enzyme 11-βHSD2. In two experiments the skeletal and metabolic phenotypes of transgenic mice and their wild-type littermates were examined either following the exposure to chronic stress (i) or during the physiological ageing process (ii). (i) Following exposure to chronic stress wild-type mice displayed a loss of trabecular bone mass in the L3-vetebra as well as a loss of cortical bone in the tibia. Interestingly, in transgenic mice, the disruption of glucocorticoid signalling in osteoblasts was sufficient to protect both the spine as well as the tibia from stress-induced bone loss. (ii) At old age, wild-type mice displayed an increase in the local activation of glucocorticoids in the skeleton and developed hyperphagia, obesity, leptin resistance and a loss of sympathetic tone. In contrast, transgenic mice only developed mild obesity during ageing and displayed normal food intake, leptin signalling as well as sympathetic tone; indicating an improved metabolic performance compared to their age-matched wild-type littermates. Conclusion: The dysregulation of glucocorticoid signalling in osteoblasts has high functional relevance in the pathophysiology of stress-induced bone loss. Furthermore, the increase in glucocorticoid signalling in bone during ageing contributes to age-related metabolic decline

Bad to the Bone: The Effects of Therapeutic Glucocorticoids on Osteoblasts and Osteocytes

Despite the continued development of specialized immunosuppressive therapies in the form of monoclonal antibodies, glucocorticoids remain a mainstay in the treatment of rheumatological and auto-inflammatory disorders. Therapeutic glucocorticoids are unmatched in the breadth of their immunosuppressive properties and deliver their anti-inflammatory effects at unparalleled speed. However, long-term exposure to therapeutic doses of glucocorticoids decreases bone mass and increases the risk of fractures – particularly in the spine – thus limiting their clinical use. Due to the abundant expression of glucocorticoid receptors across all skeletal cell populations and their respective progenitors, therapeutic glucocorticoids affect skeletal quality through a plethora of cellular targets and molecular mechanisms. However, recent evidence from rodent studies, supported by clinical data, highlights the considerable role of cells of the osteoblast lineage in the pathogenesis of glucocorticoid-induced osteoporosis: it is now appreciated that cells of the osteoblast lineage are key targets of therapeutic glucocorticoids and have an outsized role in mediating their undesirable skeletal effects. As part of this article, we review the molecular mechanisms underpinning the detrimental effects of supraphysiological levels of glucocorticoids on cells of the osteoblast lineage including osteocytes and highlight the clinical implications of recent discoveries in the field