Conditional Loss of Ikkα in Sp7/osterix+ Cells Has No Effect on Bone, but Leads to Cell Autonomous, Age-related Loss of Peripheral Fat

NF-κB has been reported to both promote and inhibit bone formation. To further explore its role in osteolineage cells, we conditionally deleted IKKα, an upstream kinase required for non-canonical NF-κB activation, using Sp7/Osterix (Osx)-Cre. Surprisingly, we found no effect on either cancellous or cortical bone, even following mechanical loading. However, we noted that IKKα conditional knockout (cKO) mice began to lose body weight after 6 months of age with severe reductions in fat mass in geriatric animals. Low levels of recombination at the IKKα locus were detected in fat pads isolated from 15 month old cKO mice. To determine if these effects were mediated by unexpected deletion of IKKα in peripheral adipocytes, we looked for Osx-Cre-mediated recombination in fat using reporter mice, which showed increasing degrees of reporter activation in adipocytes with age up to 18 months. Since Osx-Cre-driven recombination in peripheral adipocytes increases over time, we conclude that loss of fat in aged cKO mice is most likely caused by progressive deficits of IKKα in adipocytes. To further explore the effect of IKKα loss on fat metabolism, we challenged mice with a high fat diet at 2 months of age, finding that cKO mice gained less weight and showed improved glucose metabolism, compared to littermate controls. Thus, Osx-Cre mediated recombination beyond bone, including within adipocytes, should be considered as a possible explanation for extraskeletal phenotypes, especially in aging and metabolic studies.

Fat Chance for Hidden Lesions: Pictorial Review of Hoffa's Fat Pad Lesions

Hoffa's fat pad (HFP) is the most commonly afflicted among all the knee fat pads. Anterior knee pain is common in various pathologies of HFP, as it is richly innervated. A potpourri of the intrinsic and extrinsic pathologies and the tumors and tumor-like conditions affect HFP, and MRI remains the fundamental modality to assess them and provide a specific diagnosis.

Presence of adipose tissue along the posteromedial tibial border

Purpose The flexor digitorum longus and posterior tibial tendon as well as the perforating veins are located along the distal posteromedial tibial border. Adipose tissue may surround these structures and possibly play a role in reducing mechanical stress. This study aimed to examine the adipose tissue along the posteromedial tibial border via magnetic resonance imaging (MRI), ultrasound, and gross anatomical examination. Methods The lower legs of 11 healthy individuals were examined every 3 cm from the medial malleolus using MRI and ultrasound. The fat fraction was calculated using fat fraction images. In addition, the gross anatomy of the flexor digitorum longus origin and adipose tissue along the posteromedial tibial border was examined in seven fresh cadavers. The fat fraction was compared at different heights along the posteromedial tibial border and in Kager’s fat pads; we also compared the height of the flexor digitorum longus origin and adipose tissue. Results In vivo, the adipose tissue was identified along the entire posteromedial tibial border using MRI and ultrasound. There was no significant difference in fat fraction between Kager’s fat pads and the adipose tissue along the posteromedial tibial border, except at the 6 cm mark. All seven cadavers presented adipose tissue along the posteromedial tibial border, significantly more distal than the flexor digitorum longus origin. Conclusion The adipose tissue was identified along the posteromedial tibial border via MRI, ultrasound, and gross anatomical examination; thus, this tissue may play a role in reducing friction and compressive stress in tendons.

Abstract T6: Adipocyte Bardet-Biedl Syndrome 1 Gene Is Critical For Blood Pressure Regulation

Bardet-Biedl syndrome (BBS) proteins have emerged as critical regulators of various physiological functions including blood pressure. The presence of hypertension in BBS patients is consistent with the finding that BBS knockout mice exhibit increased renal sympathetic nerve activity and arterial pressure. However, the role and contribution of Bbs genes in various tissues such as adipose tissue to blood pressure regulation remains unclear. To address this, we generated a novel conditional knockout mouse that lacks the Bbs1 gene in adipocytes by breeding mice bearing floxed alleles of the Bbs1 gene (Bbs1 flox/flox ) with mice expressing Cre specifically in adipocytes (Adiponectin Cre mice). Cre-mediated recombination was verified by loss of Bbs1 expression in fat pads, but not in other tissues such as the kidneys, liver and skeletal muscle. Next, we assessed whether adipocyte Bbs1 gene deletion affects body weight and glucose homeostasis. Interestingly, no body weight phenotype was observed in both male and female Adipo Cre /Bbs1 flox/flox mice compared to their control littermates (males: 40.5±2.9 g vs 37.4±5.1 g; female: 27.7±4.0 g vs 27.5±3.6 g; 16 weeks old). However, insulin tolerance test uncovered impaired insulin-induced glucose clearance in both male and female Adipo Cre /Bbs1 flox/flox mice. Subsequently, we measured blood pressure and found that Adipo Cre /Bbs1 flox/flox mice have a remarkable increase in systolic blood pressure (130.4±11.2 mmHg) compared to the control littermates (119.1±4.5 mmHg, p <0.05). Finally, measurement of the expression of the renin-angiotensin system components revealed significantly elevated angiotensinogen mRNA (2.43±1.31 AU vs 1±0.72 AU, p <0.01) and angiotensin-converting enzyme mRNA (2.96±2.51 AU vs 1±0.95 AU, p <0.05) in peri-renal adipose tissue, but not in other fat pads such as brown and inguinal adipose tissues. Interestingly, gene expression of angiotensin receptor 1a was not significantly altered by Bbs1 gene deletion. Taken together, our findings demonstrate that Bbs1 gene in adipose tissue play an important role in the control of insulin sensitivity and blood pressure.

Periorbital, lower face, and neck

Facial ageing occurs as a consequence of multifactorial changes in both the external skin and underlying tissues. The ageing process may vary dramatically between individual patients and is thus influenced by genetic factors. When assessing the ageing face it is important to consider the skeletal architecture, the soft tissue layers including the anterior fat pads, the osseocutaneous ligament anchors, and finally the overlying skin. Assessment of the external skin incorporates factors such as dermal thinning, solar damage, lifestyle effects such as smoking, and Fitzpatrick skin type. Surgical correction of facial ageing attempts to reverse both gravitational change of soft tissues and also to restore volume loss. There are a variety of methods used to divide the face into regions, but for the purpose of this chapter, the surgical management of facial ageing will be separated into three anatomical areas: (1) upper face, including the upper eyelids, eyebrows, and forehead; (2) midface, including the lower eyelid/anterior cheek continuum; and (3) lower and lateral cheek, neck, and perioral region

Chronic Isolation Stress Affects Central Neuroendocrine Signaling Leading to a Metabolically Active Microenvironment in a Mouse Model of Breast Cancer

Social isolation is a powerful stressor capable of affecting brain plasticity and function. In the case of breast cancer, previous data indicate that stressful experiences may contribute to a worse prognosis, activating neuroendocrine and metabolism pathways, although the mechanisms underlying these effects are still poorly understood. In this study, we tested the hypothesis that chronic isolation stress (IS) may boost hypothalamic–pituitary–adrenal (HPA) axis activity, leading to changes in the hypothalamic expression of genes modulating both mood and metabolism in an animal model of breast cancer. This centrally activated signaling cascade would, in turn, affect the mammary gland microenvironment specifically targeting fat metabolism, leading to accelerated tumor onset. MMTVNeuTg female mice (a model of breast cancer developing mammary hyperplasia at 5 months of age) were either group-housed (GH) or subjected to IS from weaning until 5 months of age. At this time, half of these subjects underwent acute restraint stress to assess corticosterone (CORT) levels, while the remaining subjects were characterized for their emotional profile in the forced swimming and saccharin preference tests. At the end of the procedures, all the mice were sacrificed to assess hypothalamic expression levels of Brain-derived neurotrophic factor (Bdnf), Neuropeptide Y (NpY), Agouti-Related Peptide (AgRP), and Serum/Glucocorticoid-Regulated Protein Kinase 1 (SgK1). Leptin and adiponectin expression levels, as well as the presence of brown adipose tissue (BAT), were assessed in mammary fat pads. The IS mice showed higher CORT levels following acute stress and decreased expression of NpY, AgRP, and SgK1, associated with greater behavioral despair in the forced swimming test. Furthermore, they were characterized by increased consumption of saccharin in a preference test, suggesting an enhanced hedonic profile. The IS mice also showed an earlier onset of breast lumps (assessed by palpation) accompanied by elevated levels of adipokines (leptin and adiponectin) and BAT in the mammary fat pads. Overall, these data point to IS as a pervasive stressor that is able to specifically target neuronal circuits, mastered by the hypothalamus, modulating mood, stress reactivity and energy homeostasis. The activation of such IS-driven machinery may hold main implications for the onset and maintenance of pro-tumorigenic environments.

Bone marrow derived mast cells injected into the osteoarthritic knee joints of mice induced by sodium monoiodoacetate enhanced spontaneous pain through activation of PAR2 and action of extracellular ATP

Conditions that resemble osteoarthritis (OA) were produced by injection of sodium monoiodoacetate (MIA) into the knee joints of mice. Bone marrow derived mast cells (BMMCs) injected into the OA knee joints enhanced spontaneous pain. Since no spontaneous pain was observed when BMMCs were injected into the knee joints of control mice that had not been treated with MIA, BMMCs should be activated within the OA knee joints and release some pain-inducible factors. Protease activated receptor-2 (PAR2) antagonist (FSLLRY-NH2) almost abolished the pain-enhancing effects of BMMCs injected into the OA knee joints, suggesting that tryptase, a mast cell protease that is capable of activating PAR2, should be released from the injected BMMCs and enhance pain through activation of PAR2. When PAR2 agonist (SLIGKV-NH2) instead of BMMCs was injected into the OA knee joints, it was also enhanced pain. Apyrase, an ATP degrading enzyme, injected into the OA knee joints before BMMCs suppressed the pain enhanced by BMMCs. We showed that purinoceptors (P2X4 and P2X7) were expressed in BMMCs and that extracellular ATP stimulated the release of tryptase from BMMCs. These observations suggest that ATP may stimulate degranulation of BMMCs and thereby enhanced pain. BMMCs injected into the OA knee joints stimulated expression of IL-1β, IL-6, TNF-α, CCL2, and MMP9 genes in the infrapatellar fat pads, and PAR2 antagonist suppressed the stimulatory effects of BMMCs. Our study suggests that intermittent pain frequently observed in OA knee joints may be due, at least partly, to mast cells through activation of PAR2 and action of ATP, and that intraarticular injection of BMMCs into the OA knee joints may provide a useful experimental system for investigating molecular mechanisms by which pain is induced in OA knee joints.

Inhibition of Col6a5 Improve Lipid Metabolism Disorder in Dihydrotestosterone-Induced Hyperandrogenic Mice

Hyperandrogenism is a key pathological feature of polycystic ovarian syndrome (PCOS). Excess androgen can lead to PCOS-like cell hypertrophy in the ovaries and adipose tissue of rodents. Here, we established a dihydrotestosterone (DHT)-induced hyperandrogenic mouse model to analyze the differences in gene expression and signaling pathways of the ovaries and gonad fat pads of mice treated with or without DHT by RNA microarray analysis. From the results, we focused on the overlapping differentially expressed gene—Col6a5—and the major differentially enriched signaling pathway—lipid metabolism. We employed DHT-induced mouse ovarian stromal cell, adipogenic 3T3-L1 cell and hepatic cell line NCTC1469 models to investigate whether androgens directly mediate lipid accumulation and hypertrophy. We found that DHT increased lipid droplet accumulation in ovarian stromal cells and adipogenic 3T3-L1 cells but not NCTC1469 cells. DHT significantly altered stromal cell cholesterol metabolism and steroidogenesis, as indicated by changes in cholesterol levels and the expression of related genes, but these effects were not observed in 3T3-L1 cells. Moreover, Col6a5 expression was significantly increased in ovaries and gonadal fat pads of DHT-treated mice, and Col6a5 inhibition alleviated DHT-induced excess lipid accumulation and hypertrophy of ovarian stromal cells and adipogenic 3T3-L1 cells, even improved lipid metabolism in overnourished NCTC1469 cells. Our results indicate that Col6a5 plays important roles in the pathogenesis of DHT-induced lipid metabolism disorder and the hypertrophy of ovarian stromal cells and adipocytes.