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Paget's disease (PD) is characterized by increased numbers of abnormal osteoclasts (OCLs) that drive exuberant bone formation, but the mechanisms responsible for the increased bone formation remain unclear. We previously reported that OCLs from 70% of PD patients express measles virus nucleocapsid protein (MVNP), and that transgenic mice with targeted expression of MVNP in OCLs (MVNP mice) develop bone lesions and abnormal OCLs characteristic of PD. In this report, we examined if OCL‐derived sphingosine‐1‐phosphate (S1P) contributed to the abnormal bone formation in PD, since OCL‐derived S1P can act as a coupling factor to increase normal bone formation via binding S1P‐receptor‐3 (S1PR3) on osteoblasts (OBs). We report that OCLs from MVNP mice and PD patients expressed high levels of sphingosine kinase‐1 (SphK‐1) compared with wild‐type (WT) mouse and normal donor OCLs. SphK‐1 production by MVNP‐OCLs was interleukin‐6 (IL‐6)‐dependent since OCLs from MVNP/IL‐6 −/− mice expressed lower levels of SphK‐1. Immunohistochemistry of bone biopsies from a normal donor, a PD patient, WT and MVNP mice confirmed increased expression levels of SphK‐1 in OCLs and S1PR3 in OBs of the PD patient and MVNP mice compared with normal donor and WT mice. Further, MVNP‐OCLs cocultured with OBs from MVNP or WT mice increased OB‐S1PR3 expression and enhanced expression of OB differentiation markers in MVNP‐OBs precursors compared with WT‐OBs, which was mediated by IL‐6 and insulin‐like growth factor 1 secreted by MVNP‐OCLs. Finally, the addition of an S1PR3 antagonist (VPC23019) to WT or MVNP‐OBs treated with WT and MVNP‐OCL‐conditioned media (CM) blocked enhanced OB differentiation of MVNP‐OBs treated with MVNP‐OCL‐CM. In contrast, the addition of the SIPR3 agonist, VPC24191, to the cultures enhanced osterix and Col‐1A expression in MVNP‐OBs treated with MVNP‐OCL‐CM compared with WT‐OBs treated with WT‐OCL‐CM. These results suggest that IL‐6 produced by PD‐OCLs increases S1P in OCLs and S1PR3 on OBs, to increase bone formation in PD., Model for the effects of sphingosine kinase‐1/sphingosine‐1‐phosphate/S1P‐receptor‐3 (SphK‐1/S1P/S1PR3) in abnormal bone remodeling in Paget's disease (PD). Measles virus nucleocapsid protein (MVNP) in PD‐osteoclasts (OCLs) induces interleukin‐6 (IL‐6), which upregulates insulin‐like growth factor 1 (IGF‐1) and Sphk1. SphK‐1 enhances S1P levels in OCLs, and IL‐6 and IGF‐1 increase S1PR3 on osteoblast (OBs). S1P then increases OB differentiation and bone formation via enhanced S1PR3 expression on OBs.

Introduction: Globally, 300 million adults have clinical obesity. Heightened adiposity and inadequate musculature secondary to obesity alter bipedal stance and gait, diminish musculoskeletal tissue quality, and compromise neuromuscular feedback; these physiological changes alter stability and increase injury risk from falls. Studies in the field focus on obese patients across a broad range of body mass indices (BMI >30 kg/m2) but without isolating the most morbidly obese subset (BMI ≥40 kg/m2). We investigated the impact of obesity in perturbing postural stability in morbidly obese subjects elected for bariatric intervention, harboring a higher-spectrum BMI. Subjects and Methods: Traditional force plate measurements and stabilograms are gold standards employed when measuring center of pressure (COP) and postural sway. To quantify the extent of postural instability in subjects with obesity before bariatric surgery, we assessed 17 obese subjects with an average BMI of 40 kg/m2 in contrast to 13 nonobese subjects with an average BMI of 30 kg/m2. COP and postural sway were measured from static and dynamic tasks. Involuntary movements were measured when patients performed static stances, with eyes either opened or closed. Two additional voluntary movements were measured when subjects performed dynamic, upper torso tasks with eyes opened. Results: Mean body weight was 85% (p < 0.001) greater in obese than nonobese subjects. Following static balance assessments, we observed greater sway displacement in the anteroposterior (AP) direction in obese subjects with eyes open (87%, p < 0.002) and eyes closed (76%, p = 0.04) versus nonobese subjects. Obese subjects also exhibited a higher COP velocity in static tests when subjects’ eyes were open (47%, p = 0.04). Dynamic tests demonstrated no differences between groups in sway displacement in either direction; however, COP velocity in the mediolateral (ML) direction was reduced (31%, p < 0.02) in obese subjects while voluntarily swaying in the AP direction, but increased in the same cohort when swaying in the ML direction (40%, p < 0.04). Discussion and Conclusion: Importantly, these data highlight obesity’s contribution towards increased postural instability. Obese subjects exhibited greater COP displacement at higher AP velocities versus nonobese subjects, suggesting that clinically obese individuals show greater instability than nonobese subjects. Identifying factors contributory to instability could encourage patient-specific physical therapies and presurgical measures to mitigate instability and monitor postsurgical balance improvements.

Osteoporosis, a condition of skeletal decline that undermines quality of life, is treated with pharmacological interventions that are associated with poor adherence and adverse effects. Complicating efforts to improve clinical outcomes, the incidence of obesity is increasing, predisposing the population to a range of musculoskeletal complications and metabolic disorders. Pharmacological management of obesity has yet to deliver notable reductions in weight and debilitating complications are rarely avoided. By contrast, exercise shows promise as a non-invasive and non-pharmacological method of regulating both osteoporosis and obesity. The principal components of exercise - mechanical signals - promote bone and muscle anabolism while limiting formation and expansion of fat mass. Mechanical regulation of bone and marrow fat might be achieved by regulating functions of differentiated cells in the skeletal tissue while biasing lineage selection of their common progenitors - mesenchymal stem cells. An inverse relationship between adipocyte versus osteoblast fate selection from stem cells is implicated in clinical conditions such as childhood obesity and increased marrow adiposity in type 2 diabetes mellitus, as well as contributing to skeletal frailty. Understanding how exercise-induced mechanical signals can be used to improve bone quality while decreasing fat mass and metabolic dysfunction should lead to new strategies to treat chronic diseases such as osteoporosis and obesity.

PURPOSE OF REVIEW: To highlight recent basic, translational, and clinical work demonstrating exercise and diet regulation of marrow adipose tissue (MAT) and bone, and how this informs current understanding of the relationship between marrow adiposity and musculoskeletal health. RECENT FINDINGS: Marrow adipocytes accumulate in bone in the setting of hypercaloric intake (calorie excess; e.g. diet-induced obesity), but also with hypocaloric intake (calorie restriction; e.g. anorexia), despite the fact that these states affect bone differently. With hypercaloric intake, bone quantity is largely unaffected whereas with hypocaloric intake, bone quantity and quality are greatly diminished. Voluntary running exercise in rodents was found to lower MAT and promote bone in eucaloric and hypercaloric states, while degrading bone in hypocaloric states, suggesting differential modulation of MAT and bone, dependent upon whole body energy status. Energy status alters bone metabolism and bioenergetics via substrate availability or excess, which plays a key role in the response of bone and MAT to mechanical stimuli. SUMMARY: Marrow adipose tissue (MAT) is a fat depot with a potential role in – as well as responsivity to – whole body energy metabolism. Understanding the localized function of this depot in bone cell bioenergetics and substrate storage, principally in the exercised state, will aid to uncover putative therapeutic targets for skeletal fragility.

Patients afflicted with or being treated for cancer constitute a distinct and alarming subpopulation who exhibit elevated fracture risk and heightened susceptibility to developing secondary osteoporosis. Cancer cells uncouple the regulatory processes central for the adequate regulation of musculoskeletal tissue. Systemically taxing treatments to target tumors or disrupt the molecular elements driving tumor growth place considerable strain on recovery efforts. Skeletal tissue is inherently sensitive to mechanical forces, therefore attention to exercise and mechanical loading as non-pharmacological means to preserve bone during treatment and in post-treatment rehabilitative efforts have been topics of recent focus. This review discusses the dysregulation that cancers and the ensuing metabolic dysfunction that confer adverse effects on musculoskeletal tissues. Additionally, we describe foundational mechanotransduction pathways and the mechanisms by which they influence both musculoskeletal and cancerous cells. Functional and biological implications of mechanical loading at the tissue and cellular levels will be discussed, highlighting the current understanding in the field. Herein, in vitro, translational, and clinical data are summarized to consider the positive impact of exercise and low magnitude mechanical loading on tumor-bearing skeletal tissue.

Objective The aim of this study was to determine whether inclusion of a refractory period between bouts of low-magnitude mechanical stimulation (LMMS) can curb obesity-induced adipose tissue dysfunction and sequelae in adult mice. Methods A diet-induced obesity model that included a diet with 45% of kilocalories from fat was employed with intention to treat. C57BL/6J mice were weight matched into four groups: low-fat diet (LFD, n = 8), high-fat diet (HFD, n = 8), HFD with one bout of 30-minute LMMS (HFDv, n = 9), and HFD with two bouts of 15-minute LMMS with a 5-hour separation (refractory period, RHFDv, n = 9). Two weeks of diet was followed by 6 weeks of diet plus LMMS. Results HFD and HFDv mice continued gaining body weight and visceral adiposity throughout the experiment, which was mitigated in RHFDv mice. Compared with LFD mice, HFD and HFDv mice had increased rates of adipocyte hypertrophy, increased immune cell infiltration (B cells, T cells, and macrophages) into adipose tissue, increased adipose tissue inflammation (tumor necrosis factor alpha gene expression), and a decreased proportion of mesenchymal stem cells in adipose tissue, all of which were rescued in RHFDv mice. Glucose intolerance and insulin resistance were elevated in HFD and HFDv mice, but not in RHFDv mice, as compared with LFD mice. Conclusions Incorporating a 5-hour refractory period between bouts of LMMS attenuates obesity-induced adipose tissue dysfunction and improves glucose metabolism.

The relationship between marrow adipose tissue (MAT) and bone health is poorly understood. We used running exercise to ask whether obesity-associated MAT can be attenuated via exercise and whether this correlates with gains in bone quantity and quality. C57BL/6 mice were divided into diet-induced obesity (DIO, n = 14) versus low-fat diet (LFD, n = 14). After 3 months, 16-week-old mice were allocated to an exercise intervention (LFD-E, DIO-E) or a control group (LFD, DIO) for 6 weeks (4 groups, n = 7/group). Marrow adipocyte area was 44% higher with obesity (p

Autologus augmentation of wound remodeling with platelet concentrate is a burgeoning field with promising results. We hypothesized that the addition of filtered platelet concentrate (fPC) to an acellular biologic graft would improve crural healing and tissue integrity in hiatal hernia repair. Sixteen healthy Yorkshire female pigs were divided into three groups: hiatus repair (HR) (n = 7), HR with biologic graft (HRM; n = 8, and HR with biologic graft and fPC (fPC; n = 9). Surgeries were performed by a single surgeon. Animals were euthanized at 8 weeks, and the distal esophagus with hiatus was harvested en-block. Tissue was graded by a histopathologist on collagen deposition, vascularization, and inflammation at the graft–hiatal interface. Tensile strength testing was performed using the Teststar IIs (MTS), coupled with a strain extensometer (Epsilon). Samples of equal dimensions were preloaded to 1 N and deformed at a constant rate of 0.2 mm/s. Statistical analysis was performed via Kruskal–Wallis one-way analysis of variance. Aspirate analysis revealed a mean platelet count of 3 million platelets/1 mL of aspirate. Animals in the fPC group had significantly increased mean chronic inflammation (3.1 ± 1.1 vs. 1.8 ± 1.6, 1.2 ± 1.2, p = 0.04) compared to HR alone and HR + biologic graft. Vascular deposition did not differ between groups (p = 0.8). A trend toward increased collagen deposition was demonstrated for the fPC group (1.4 ± 1.1 vs. 2.0 ± 0.6 in HR group and 3.0 ± 1.2 in HRM group, p = 0.06). There was a statistically significant increase in tensile strength, yield force, and Young’s modulus in the fPC group compared with HR and HR + biologic mesh (p

B7-H4, a tumor-associated cell surface protein, is expressed in endometrioid (EM), serous (SE), and clear cell (CC) ovarian carcinomas. Prior in vitro studies from other groups indicated that elevated B7-H4 expression by tumor cells blocks T-cell activation; therefore, it had been postulated to play a role in shielding cancer cells from immune surveillance and averting apoptotic programs. To test the validity of these hypotheses, the present study was designed to compare the immunohistochemical staining intensity of B7-H4 in tumor cells of ovarian cancers with the number of tumor-infiltrating T cells and macrophages and with the levels of caspase-3 staining in apoptotic debris. Serial tissue sections from EM, SE, and CC carcinomas were analyzed across representative cross-sections of tumor resection specimens, demonstrating different levels of B7-H4 expression, highest in CC cancers. B7-H4 staining in CC tissue sections was significantly correlated with the number of CD3, CD4, and CD8 tumor-infiltrating T cells and with the number of CD14 tumor-infiltrating macrophages, but was not significantly related to caspase-3 staining. These results support the concept that high levels of B7-H4 expression are inversely correlated with tumor T-cell infiltration and with CD14-labeled macrophages but not caspase-3 expression in CC carcinomas. We did not, however, find clear evidence of a relationship between the lower levels of B7-H4 seen in EM and SE carcinomas and T cell or macrophage infiltration. Thus, high levels of B7-H4, as seen in CC carcinomas, is associated with decreased tumor infiltration by T cells and macrophages but the lower levels of expression, as observed in EM and SE carcinomas, appear less likely to play an effective role in protection from immune surveillance. Furthermore, we found no evidence of a correlation between B7-H4 expression and apoptosis. These findings highlight the importance of further investigation of B7-H4 as an immunomodulatory protein, to support the development of novel therapeutic interventions for improved efficacy of treatments for CC carcinoma.

Bone metastases cause significant morbidity and mortality in late-stage breast cancer patients and are currently considered incurable. Investigators rely on translational models to better understand the pathogenesis of skeletal complications of malignancy in order to identify therapeutic targets that may ultimately prevent and treat solid tumor metastasis to bone. Many experimental models of breast cancer bone metastases are in use today, each with its own caveats. In this methods review, we characterize the bone phenotype of commonly utilized human- and murine-derived breast cell lines that elicit osteoblastic and/or osteolytic destruction of bone in mice and report methods for optimizing tumor-take in murine models of bone metastasis. We then provide protocols for four of the most common xenograft and syngeneic inoculation routes for modeling breast cancer metastasis to the skeleton in mice, including the intra-cardiac, intra-arterial, orthotopic and intra-tibial methods of tumor cell injection. Recommendations for in vivo and ex vivo assessment of tumor progression and bone destruction are provided, followed by discussion of the strengths and limitations of the available tools and translational models that aid investigators in the study of breast cancer metastasis to bone.

Despite association with low bone density and skeletal fractures, marrow adipose tissue (MAT) remains poorly understood. The marrow adipocyte originates from the mesenchymal stem cell (MSC) pool that also gives rise to osteoblasts, chondrocytes, and myocytes, among other cell types. To date, the presence of MAT has been attributed to preferential biasing of MSC into the adipocyte rather than osteoblast lineage, thus negatively impacting bone formation. Here, we focus on understanding the physiology of MAT in the setting of exercise, dietary interventions, and pharmacologic agents that alter fat metabolism. The beneficial effect of exercise on musculoskeletal strength is known: exercise induces bone formation, encourages growth of skeletally supportive tissues, inhibits bone resorption, and alters skeletal architecture through direct and indirect effects on a multiplicity of cells involved in skeletal adaptation. MAT is less well studied due to the lack of reproducible quantification techniques. In recent work, osmium-based 3D quantification shows a robust response of MAT to both dietary and exercise intervention in that MAT is elevated in response to high-fat diet and can be suppressed following daily exercise. Exercise-induced bone formation correlates with suppression of MAT, such that exercise effects might be due to either calorie expenditure from this depot or from mechanical biasing of MSC lineage away from fat and toward bone, or a combination thereof. Following treatment with the anti-diabetes drug rosiglitazone – a PPARγ-agonist known to increase MAT and fracture risk – mice demonstrate a fivefold higher femur MAT volume compared to the controls. In addition to preventing MAT accumulation in control mice, exercise intervention significantly lowers MAT accumulation in rosiglitazone-treated mice. Importantly, exercise induction of trabecular bone volume is unhindered by rosiglitazone. Thus, despite rosiglitazone augmentation of MAT, exercise significantly suppresses MAT volume and induces bone formation. That exercise can both suppress MAT volume and increase bone quantity, notwithstanding the skeletal harm induced by rosiglitazone, underscores exercise as a powerful regulator of bone remodeling, encouraging marrow stem cells toward the osteogenic lineage to fulfill an adaptive need for bone formation. Thus, exercise represents an effective strategy to mitigate the deleterious effects of overeating and iatrogenic etiologies on bone and fat.

The bone marrow (BM) niche is the primary site of hematopoiesis, and cues from this microenvironment are critical to maintain hematopoiesis. Obesity increases lifetime susceptibility to a host of chronic diseases, and has been linked to defective leukogenesis. The pressures obesity exerts on hematopoietic tissues led us to study the effects of a high fat diet (HFD: 60% Kcal from fat) on B cell development in BM. Seven week old male C57Bl/6J mice were fed either a high fat (HFD) or regular chow (RD) diet for periods of 2 days, 1 week and 6 weeks. B-cell populations (B220+) were not altered after 2 d of HFD, within 1 w B-cell proportions were reduced by −10%, and by 6 w by −25% as compared to RD (p