Adiponectin is a candidate biomarker of lower extremity bone density in men with chronic spinal cord injury

Factors Associated With Regular Dental Care in People With Spinal Cord Injury: A Secondary Analysis of Data From the FRASCI Study

Background

Oral health and regular dental care are critical to overall health. Research has found associations between oral health and infections, respiratory disease, and poor quality of life in the general population. While risks for all are increased in people with spinal cord injury (SCI), there is limited information on dental care after SCI.

Objectives

The purpose of this analysis was to examine factors associated with regular dental care in people with SCI.

Methods

We analyzed data from 348 individuals with traumatic and nontraumatic SCI who were enrolled in the Fracture Risk after SCI (FRASCI) study. The dataset included two variables on dental care, as well as demographics, injury-related characteristics, and secondary conditions. Bivariate relationships were determined using two-sided t tests and chi-square tests.

Results

Over 60% of the sample received regular dental care twice per year, and 71% reported seeing a dentist within the past year. Those participants receiving regular dental care twice a year were more likely to be female, be working, have more than a high school diploma, have private insurance, and need a caregiver compared to those who do not receive regular dental care. In addition, these participants were more likely to have had pneumonia since their SCI and have had a urinary tract infection in the past year and since injury.

Conclusion

More data on oral health are needed to make conclusions about the impact of oral health on secondary conditions and quality of life in people with SCI.

Nutrition Education to Reduce Metabolic Dysfunction for Spinal Cord Injury: A Module-Based Nutrition Education Guide for Healthcare Providers and Consumers

Spinal cord injury (SCI) results in a high prevalence of neurogenic obesity and metabolic dysfunction. The increased risk for neurogenic obesity and metabolic dysfunction is mainly due to the loss of energy balance because of significantly reduced energy expenditure following SCI. Consequently, excessive energy intake (positive energy balance) leads to adipose tissue accumulation at a rapid rate, resulting in neurogenic obesity, systemic inflammation, and metabolic dysfunction. The purpose of this article is to review the existing literature on nutrition, dietary intake, and nutrition education in persons with SCI as it relates to metabolic dysfunction. The review will highlight the poor dietary intakes of persons with SCI according to authoritative guidelines and the need for nutrition education for health care professionals and consumers. Nutrition education topics are presented in a module-based format with supporting literature. The authors emphasize the role of a diet consisting of low-energy, nutrient-dense, anti-inflammatory foods consistent with the Dietary Guidelines for Americans' MyPlate to effectively achieve energy balance and reduce the risk for neurogenic obesity and metabolic dysfunction in individuals with SCI.

Biomarkers from Secondary Complications in Spinal Cord Injury

PURPOSE OF REVIEW

In the USA, spinal cord injury (SCI) occurs in 40 people per million every year due to events such as car accidents, falls, violence, or sports injury. Secondary complications that arise from SCI are life-threatening and should be treated as early as possible. In some cases, it is not completely obvious what complication a patient may have until it is too late. Therefore, biomarkers are required to assess the levels of secondary complications after SCI. As there are several complications that pose different warning signs, different biomarkers may be beneficial in early detection, maintenance, and long-term care for patients with SCI.

RECENT FINDINGS

Numerous studies have been conducted on biomarkers in various SCI and its related complications, such as neuropathic pain and deep vein thrombosis. In recent years, research has expanded with biomarkers discovered by cellular and molecular, genome-wide transcriptomic analysis, bioinformatics, and clinical studies. Biomarkers have allowed early prediction of the severity of secondary complications due to SCI.

SUMMARY

In this review, we summarize recent studies on the common biomarkers for the secondary complications related to SCI. We highlight the reliable biomarkers that have been tested, e.g., sclerostin, NGF, D-dimer, oncostatin M (OSM), microbiota, and C-reactive protein, which are valuable and with clinical importance. This review also emphasizes continuing research in biomarkers as they can provide valuable cellular and molecular insight into secondary complications after SCI.

Ibuprofen use is associated with reduced C-reactive protein and interleukin-6 levels in chronic spinal cord injury

Objective: To assess the association between ibuprofen use and the systemic inflammatory biomarkers C-reactive protein (CRP) and interleukin-6 (IL-6) in chronic Spinal Cord Injury (SCI).Study design: Prospective cohort study.Setting: Community dwelling individuals with SCI.Participants: 338 (278 male, 60 female) community dwelling individuals with chronic SCI (≥1-year post-injury).Interventions: None.Main outcome measures: CRP and IL-6 levels were quantified by ultra-sensitive ELISA assay. General linear models were used to assess associations between various clinical and demographic factors and CRP and IL-6 levels.Results: There were 50 active ibuprofen users and 288 non-users. After adjusting for clinical and demographic factors, ibuprofen users had significantly lower CRP levels (2.3 mg/L versus 3.5 mg/L, P = 0.04) and IL-6 levels (3.2 pg/ml versus 4.0 pg/ml, P = 0.04) compared to nonusers.Conclusions: Our study suggests that self-reported ibuprofen use may be negatively associated with CRP and IL-6 levels in chronic SCI after adjusting for known confounding factors, and suggests ibuprofen use may be an important, potential variable to consider in future studies focused on systemic inflammation in SCI. Future prospective studies require assessing frequency, duration, and dosage-dependent effects of ibuprofen on systemic markers of inflammation in chronic SCI. These findings may support future clinical trials to determine safety and efficacy of ibuprofen treatment for various outcomes in chronic SCI.

Proliferation rate and expression of stem cells markers during expansion in primary culture of pulp cells

The aim of the present study was to evaluate the proliferation rate and the expression of stem cells markers during expansion in primary culture of dental pulp stem cells (DPSCs), comparing different techniques (explant and enzymatic digestion), subject ages (up to 40 and over 40) and cell passages (#2, #5 and #8). DPSCs were isolated using either the enzymatic digestion (ED) or explant (EX) technique. The number of days needed for the cells to reach confluence was determined. Immunophenotyping was performed by immunofluorescence and flow cytometry analysis using antibodies specific for nestin, vimentin, CD44, CD146, Oct3/4 and CD34. Data were subjected to three-way analysis of variance (n = 6/group). The ANOVA tests were complemented by Tukey's or t-tests (p < 0.05). The variables "donor age" and "technique" were analyzed to define the optimal desirability value using a response optimization. DPSCs presented a high proliferation rate from passages 2 to 5 while cells from passage 8 proliferated at a slower rate. For all markers, no significant difference was observed among passages, irrespective of the technique used or the donor's age. The mean fraction of specific antibodies was 73.7% (± 11.5), 49.0% (± 18.7), 80.1% (± 8.0), 45.2% (± 13.7), 64.7% (± 5.3) and 2.0% (± 1.5) for CD44, OCT, vimentin, nestin, CD146 and CD34, respectively. The highest optimal desirability value was obtained using the ED technique and cells from younger patients (d = 0.92). However, it was concluded that neither the isolation technique nor the donor age or cell passage significantly interfered with the stem cell phenotype and proliferation rate during cell expansion.

Disease-Modifying Potential of Metformin and Alendronate in an Experimental Mouse Model of Osteoarthritis

Osteoarthritis (OA) is the most common degenerative joint disease causing progressive damages of the cartilage and subchondral bone, synovial inflammation, and severe pain. Despite the complex pathomorphological changes that occur in OA, the approach to different forms of OA is standardized. The global results from pharmacological treatment are not satisfactory. Hence, this study aimed to explore the effects of metformin, alendronate, and their combination on OA development and progression in mice with collagenase-induced osteoarthritis (CIOA). Female ICR (CD-2) mice were randomized to five groups: control group, CIOA untreated, CIOA + metformin, CIOA + alendronate, and CIOA + metformin + alendronate. OA was induced by the intra-articular (i.a.) injection of collagenase. OA phenotype was analyzed by flow cytometry (bone marrow cell differentiation), ELISA (serum levels of the adipokines leptin and resistin), and histology (pathological changes of the knee joint). Treatment with metformin, alendronate, or their combination inhibited the expression of RANK and RANKL on osteoblasts and osteoclasts obtained by ex vivo cultivation of bone marrow cells in mineralization or osteoclastogenic media. In addition, metformin treatment was effective for the attenuation of fibroblast differentiation, but not of mesenchymal stem cells (MSCs), while alendronate had an opposite effect. The combination of metformin and alendronate had a suppressive effect on both MSCs and fibroblasts differentiation. Treatment with metformin, alendronate, and their combination decreased serum concentrations of leptin and resistin in the chronic phase of arthritis. The histopathological examination showed that compared with the untreated CIOA group (OA score 9), the groups treated with metformin (OA score 4) or alendronate (OA score 6) had lower scores for cartilage changes. Metformin combined with alendronate significantly decreased the degree of cartilage degeneration (OA score 2), suggesting that this combination might be a useful approach for the treatment of OA patients.

Neurogenic Obesity and Skeletal Pathology in Spinal Cord Injury

Spinal cord injury (SCI) results in dramatic changes in body composition, with lean mass decreasing and fat mass increasing in specific regions that have important cardiometabolic implications. Accordingly, the recent Consortium for Spinal Cord Medicine (CSCM) released clinical practice guidelines for cardiometabolic disease (CMD) in SCI recommending the use of compartmental modeling of body composition to determine obesity in adults with SCI. This recommendation is guided by the fact that fat depots impact metabolic health differently, and in SCI adiposity increases around the viscera, skeletal muscle, and bone marrow. The contribution of skeletal muscle atrophy to decreased lean mass is self-evident, but the profound loss of bone is often less appreciated due to methodological considerations. General-population protocols for dual-energy x-ray absorptiometry (DXA) disregard assessment of the sites of greatest bone loss in SCI, but the International Society for Clinical Densitometry (ISCD) recently released an official position on the use of DXA to diagnose skeletal pathology in SCI. In this review, we discuss the recent guidelines regarding the evaluation and monitoring of obesity and bone loss in SCI. Then we consider the possible interactions of obesity and bone, including emerging evidence suggesting the possible influence of metabolic, autonomic, and endocrine function on bone health in SCI.

Prevention and management of osteoporosis and osteoporotic fractures in persons with a spinal cord injury or disorder: A systematic scoping review

Objectives: The primary objective was to review the literature regarding methodologies to assess fracture risk, to prevent and treat osteoporosis and to manage osteoporotic fractures in SCI/D.Study Design: Scoping review.Settings/Participants: Human adult subjects with a SCI/D.Outcome measures: Strategies to identify persons with SCI/D at risk for osteoporotic fractures, nonpharmacological and pharmacological therapies for osteoporosis and management of appendicular fractures.Results: 226 articles were included in the scoping review. Risk of osteoporotic fractures in SCI is predicted by a combination of DXA-defined low BMD plus clinical and demographic characteristics. Screening for secondary causes of osteoporosis, in particular hyperparathyroidism, hyperthyroidism, vitamin D insufficiency and hypogonadism, should be considered. Current antiresorptive therapies for treatment of osteoporosis have limited efficacy. Use of surgery to treat fractures has increased and outcomes are good and comparable to conservative treatment in most cases. A common adverse event following fracture was delayed healing.Conclusions: Most of the research in this area is limited by small sample sizes, weak study designs, and significant variation in populations studied. Future research needs to address cohort definition and study design issues.

The Adipokine Network in Rheumatic Joint Diseases

Rheumatic diseases encompass a diverse group of chronic disorders that commonly affect musculoskeletal structures. Osteoarthritis (OA) and rheumatoid arthritis (RA) are the two most common, leading to considerable functional limitations and irreversible disability when patients are unsuccessfully treated. Although the specific causes of many rheumatic conditions remain unknown, it is generally accepted that immune mechanisms and/or uncontrolled inflammatory responses are involved in their etiology and symptomatology. In this regard, the bidirectional communication between neuroendocrine and immune system has been demonstrated to provide a homeostatic network that is involved in several pathological conditions. Adipokines represent a wide variety of bioactive, immune and inflammatory mediators mainly released by adipocytes that act as signal molecules in the neuroendocrine-immune interactions. Adipokines can also be synthesized by synoviocytes, osteoclasts, osteoblasts, chondrocytes and inflammatory cells in the joint microenvironment, showing potent modulatory properties on different effector cells in OA and RA pathogenesis. Effects of adiponectin, leptin, resistin and visfatin on local and systemic inflammation are broadly described. However, more recently, other adipokines, such as progranulin, chemerin, lipocalin-2, vaspin, omentin-1 and nesfatin, have been recognized to display immunomodulatory actions in rheumatic diseases. This review highlights the latest relevant findings on the role of the adipokine network in the pathophysiology of OA and RA.

Progressive Sublesional Bone Loss Extends into the Second Decade After Spinal Cord Injury

OBJECTIVE

The rate of areal bone mineral density (aBMD) loss at the knee (distal femur (DF) and proximal tibia ) and hip (femoral neck (FN) and total hip (TH)) was determined in persons with traumatic spinal cord injury (SCI) who were stratified into subgroups based on time since injury (TSI).

DESIGN

Cross-sectional retrospective review.

SETTING

Department of Veterans Affairs Medical Center and Private Rehabilitation Hospital.

PARTICIPANTS

Data on 105 individuals with SCI (TSI ≤12 months, n = 19; TSI 1-5 years, n = 35; 6-10 years, n = 19; TSI 11-20 years, n = 16; TSI >20 years, n = 15) and 17 able-bodied reference (AB_ref) controls.

INTERVENTIONS

NA Main Outcome Measures: The knee and hip aBMD values were obtained by dual energy X-ray absorptiometry (GE Lunar iDXA) using standard clinical software for the proximal femur employed in conjunction with proprietary research orthopedic knee software applications. Young-normal (T-score) and age-matched (Z-scores) standardized scores for the FN and TH were obtained using the combined GE Lunar/National Health and Nutrition Examination Survey (NHANES III) combined reference database.

RESULTS

When groups were stratified and compared as epochs of TSI, significantly lower mean aBMD and reference scores were observed as TSI increased, despite similar mean ages of participants among the majority of TSI epoch subgroups. Loss in aBMD occurred at the distal femur (DF), proximal tibia (PT), FN, and TH with 46%, 49%, 32%, and 43% of the variance in loss, respectively, described by the exponential decay curves with a time to steady state (t_ss) occurring at 14.6, 11.3, 14, and 6.2 years, respectively, after SCI.

CONCLUSIONS

Sublesional bone loss after SCI was marked and occurred as an inverse function of TSI. For aBMD at the hip and knee, t_ss extended into the second decade after SCI.

Associations between lean mass and leptin in men with chronic spinal cord injury: Results from the FRASCI-muscle study

Leptin is an adipo-myokine that regulates appetite and energy expenditure by a neuroendocrine feedback loop. Leptin levels are positively correlated with BMI in the spinal cord injury population and leptin levels are greater in individuals with spinal cord injury compared to uninjured controls. Leptin is produced in multiple tissues, including fat, bone, and skeletal muscle and is a putative biomarker of sedentary behavior in older adults. We assessed body composition leptin, adiponectin, and IL-6 levels in 205 men with chronic spinal cord injury. We found no association between age, injury duration, injury level, injury completeness, or walking status and leptin. There was a significant positive association between lean mass and leptin in men with SCI that was independent of fat. Adjusting for body composition, leptin levels were positively associated with IL-6 and negatively associated with adiponectin levels. When considering men with SCI and sarcopenic obesity, only fat mass remained positively associated with leptin. We found no association between IL-6, adiponectin, or lean mass and leptin in the sarcopenic obesity group. Our findings suggest that lean mass is an under recognized, but substantial, source of circulating leptin. Furthermore, SCI-related sarcopenic obesity may result in dysregulated adipo-myokine metabolism with local and systemic physiologic effects.

Biomechanics, obesity, and osteoarthritis. The role of adipokines: When the levee breaks

Osteoarthritis is a high-incidence painful and debilitating disease characterized by progressive degeneration of articular joints, which indicates a breakdown in joint homeostasis favoring catabolic processes. Biomechanical loading, associated with inflammatory and metabolic imbalances of joint, strongly contributes to the initiation and progression of the disease. Obesity is a primary risk factor for disease onset, and mechanical factors increased the risk for disease progression. Moreover, inflammatory mediators, in particular, adipose tissue-derived cytokines (better known as adipokines) play a critical role linking obesity and osteoarthritis. The present article summarizes the knowledge about the role of adipokines in cartilage and bone function, highlighting their contribution to the imbalance of joint homeostasis and, consequently, pathogenesis of osteoarthritis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:594-604, 2018.

Bone loss at the distal femur and proximal tibia in persons with spinal cord injury: imaging approaches, risk of fracture, and potential treatment options

Persons with spinal cord injury (SCI) undergo immediate unloading of the skeleton and, as a result, have severe bone loss below the level of lesion associated with increased risk of long-bone fractures. The pattern of bone loss in individuals with SCI differs from other forms of secondary osteoporosis because the skeleton above the level of lesion remains unaffected, while marked bone loss occurs in the regions of neurological impairment. Striking demineralization of the trabecular epiphyses of the distal femur (supracondylar) and proximal tibia occurs, with the knee region being highly vulnerable to fracture because many accidents occur while sitting in a wheelchair, making the knee region the first point of contact to any applied force. To quantify bone mineral density (BMD) at the knee, dual energy x-ray absorptiometry (DXA) and/or computed tomography (CT) bone densitometry are routinely employed in the clinical and research settings. A detailed review of imaging methods to acquire and quantify BMD at the distal femur and proximal tibia has not been performed to date but, if available, would serve as a reference for clinicians and researchers. This article will discuss the risk of fracture at the knee in persons with SCI, imaging methods to acquire and quantify BMD at the distal femur and proximal tibia, and treatment options available for prophylaxis against or reversal of osteoporosis in individuals with SCI.

Wheelchair use and lipophilic statin medications may influence bone loss in chronic spinal cord injury: findings from the FRASCI-bone loss study

We identified a protective bone effect at the knee with lipophilic statin use in individuals with chronic spinal cord injury. Lipophilic statin users gained bone at the knee compared to non-users and wheelchair users lost bone compared to walkers. Ambulation and or statins may be effective osteogenic interventions in chronic spinal cord injury (SCI).

INTRODUCTION

SCI increases the risk of osteoporosis and low-impact fractures, particularly at the knee. However, during the chronic phase of SCI, the natural history and factors associated with longitudinal change in bone density remain poorly characterized. In this study, we prospectively assessed factors associated with change in bone density over a mean of 21 months in 152 men and women with chronic SCI.

METHODS

A mixed model procedure with repeated measures was used to assess predictors of change in bone mineral density (PROC MIXED) at the distal femur and proximal tibia. Factors with a p value of <0.10 in the univariate mixed models, as well as factors that were deemed clinically significant (gender, age, and walking status), were assessed in multivariable models. Factors with a p value of ≤0.05 were included in the final model.

RESULTS

We found no association between bone loss and traditional osteoporosis risk factors, including age, gender, body composition, or vitamin D level or status (normal or deficient). In both crude and fully adjusted models, wheelchair users lost bone compared to walkers. Similarly, statin users gained bone compared to nonusers.

CONCLUSIONS

The statin finding is supported by reports in the general population where statin use has been associated with a reduction in bone loss and fracture risk. Our results suggest that both walking and statins may be effective osteogenic therapies to mitigate bone loss and prevent osteoporosis in chronic SCI. Our findings also suggest that loss of mechanical loading and/or neuronal factors contribute more to disuse osteoporosis than traditional osteoporosis risk factors.

Bone morphology of the femur and tibia captured by statistical shape modelling predicts rapid bone loss in acute spinal cord injury patients

After spinal cord injury (SCI), bone loss in the paralysed limbs progresses at variable rates. Decreases in bone mineral density (BMD) in the first year range from 1% (slow) to 40% (rapid). In chronic SCI, fragility fractures commonly occur around the knee, with significant associated morbidity. Osteoporosis treatments await full evaluation in SCI, but should be initiated early and targeted towards patients exhibiting rapid bone loss. The potential to predict rapid bone loss from a single bone scan within weeks of a SCI was investigated using statistical shape modelling (SSM) of bone morphology, hypothesis: baseline bone shape predicts bone loss at 12-months post-injury at fracture-prone sites. In this retrospective cohort study 25 SCI patients (median age, 33 years) were scanned at the distal femur and proximal tibia using peripheral Quantitative Computed Tomography at <5 weeks (baseline), 4, 8 and 12 months post-injury. An SSM was made for each bone. Links between the baseline shape-modes and 12-month total and trabecular BMD loss were analysed using multiple linear regression. One mode from each SSM significantly predicted bone loss (age-adjusted P<0.05 R(2)=0.37-0.61) at baseline. An elongated intercondylar femoral notch (femur mode 4, +1 SD from the mean) was associated with 8.2% additional loss of femoral trabecular BMD at 12-months. A more concave posterior tibial fossa (tibia mode 3, +1 SD) was associated with 9.4% additional 12-month tibial trabecular BMD loss. Baseline bone shape determined from a single bone scan is a valid imaging biomarker for the prediction of 12-month bone loss in SCI patients.

Measurement of Bone: Diagnosis of SCI-Induced Osteoporosis and Fracture Risk Prediction

BACKGROUND

Spinal cord injury (SCI) is associated with a rapid loss of bone mass, resulting in severe osteoporosis and a 5- to 23-fold increase in fracture risk. Despite the seriousness of fractures in SCI, there are multiple barriers to osteoporosis diagnosis and wide variations in treatment practices for SCI-induced osteoporosis.

METHODS

We review the biological and structural changes that are known to occur in bone after SCI in the context of promoting future research to prevent or reduce risk of fracture in this population. We also review the most commonly used methods for assessing bone after SCI and discuss the strengths, limitations, and clinical applications of each method.

CONCLUSIONS

Although dual-energy x-ray absorptiometry assessments of bone mineral density may be used clinically to detect changes in bone after SCI, 3-dimensional methods such as quantitative CT analysis are recommended for research applications and are explained in detail.

Serum leptin, bone mineral density and the healing of long bone fractures in men with spinal cord injury

Previously reported fracture rates in patients with spinal cord injury range from 1% to 20%. However, the exact role of spinal cord injury in bone metabolism has not yet been clarified. In order to investigate the effects of serum leptin and bone mineral density on the healing of long bone fractures in men with spinal cord injury, 15 male SCI patients and 15 matched controls were involved in our study. The outcome indicated that at 4 and 8 weeks after bone fracture, callus production in patients with spinal cord injury was lower than that in controls. Besides, bone mineral density was significantly reduced at 2, 4 and 8 weeks. In addition, it was found that at each time point, patients with spinal cord injury had significantly higher serum leptin levels than controls and no association was found between serum leptin level and bone mineral density of lumbar vertebrae. Moreover, bone mineral density was positively correlated with bone formation in both of the groups. These findings suggest that in early phases i.e. week 4 and 8, fracture healing was impaired in patients with spinal cord injury and that various factors participated in the complicated healing process, such as hormonal and mechanical factors.

Impact of Wheelchair Rugby on Body Composition of Subjects With Tetraplegia: A Pilot Study

OBJECTIVE

To investigate the longitudinal effects of wheelchair rugby (WR) training on body composition of subjects with tetraplegia.

DESIGN

Subjects were evaluated at baseline and after WR training.

SETTING

Faculty of physical education settings.

PARTICIPANTS

Individuals with tetraplegia (N=13; age, 26.6±6.0y).

INTERVENTIONS

Four sessions per week of WR training composed by aerobic and anaerobic activities and technical and tactical aspects of WR. The average time of intervention was 8.1±2.5 months.

MAIN OUTCOME MEASURES

Body composition assessed by dual-energy x-ray absorptiometry.

RESULTS

After training, fat mass was significantly reduced in the whole body (15,191±4603 vs 13,212±3318 g, P=.016), trunk (7058±2639 vs 5693±1498 g, P=.012), and legs (2847±817 vs 2534±742 g, P=.003). Conversely, increased bone mineral content (183±35 vs 195±32 g, P=.01) and fat-free mass (2991±549 vs 3332±602 g, P=.016) in the arms and reduced bone mineral content in the trunk (553±82 vs 521±86 g, P=.034) were observed after training. Furthermore, no significant correlation between the duration of training and changes in body composition was detected.

CONCLUSIONS

Regular WR training increased lean mass and bone mineral content in the arms and decreased total body fat mass. Conversely, WR training was associated with decreased bone mineral content in the trunk. These results suggest that regular WR training improves body composition in subjects with tetraplegia.

Influences of nutrition and adiposity on bone mineral density in individuals with chronic spinal cord injury: A cross-sectional, observational study

BACKGROUND

Dietary inadequacy and adiposity, both prevalent in the chronic spinal cord injury (SCI) population, are known to influence bone turnover and may be potential modifiable risk factors for the development of sublesional osteoporosis following SCI. This pilot study in an SCI cohort aimed to assess measures of nutrition and obesity, to determine if these measures were associated with bone mineral density (BMD), and to compare these measures to a non-SCI control cohort.

METHODS

In a cross-sectional observational study, volunteers with chronic SCI (> 1 year post-injury, lesions from C1 to T12 and severity category A-D by the American Spinal Injury Association Impairment Scale) were assessed, and 8 non-SCI individuals were recruited as a comparison group. BMD at the femoral neck (FN) and lumbar spine (LS), and an estimate of visceral adipose tissue (VAT) from lumbar vertebrae 1 through 4 were measured using dual energy X-ray absorptiometry (DXA); nutrient intake of calcium, vitamins D & K, and protein were estimated using a food frequency questionnaire; plasma 25-hydroxyvitamin D (25(OH)D) was analyzed using ultra-high performance liquid chromatography/tandem mass spectroscopy; and serum leptin, adiponectin and insulin were analyzed using a multiplex assay.

RESULTS

A total of 34 individuals with SCI (n = 22 tetraplegic; n = 12 paraplegic; 94% male) who averaged 12.7 (9.0) years post-injury, age 40.0 (10.9) years and % body fat of 28.4 (7.3) were assessed. Multiple linear regression analyses in the SCI cohort showed significant associations between BMD at the FN and LS with leptin (FN: r = 0.529, p = 0.005; LS: r = 0.392, p = 0.05), insulin (FN: r = 0.544, p = 0.003; LS: r = 0.388, p = 0.05), and VAT percent (FN: r = 0.444, p = 0.02; LS: r = 0.381, p = 0.05). Adiponectin was only correlated with LS BMD (r = 0.429, p = 0.03). No significant relationships were found between BMD and serum 25(OH)D, or intakes of calcium, vitamins D & K, and protein. Intake of vitamin D was adequate in 69% of participants with SCI, where 91% of those persons consumed either vitamin D and/or multivitamin supplements. Vitamin D status was similar between SCI and non-SCI groups as was sub-optimal status (25(OH)D < 75 nmol/L) (60% of SCI compared to 50% of non-SCI). Participants with SCI had significantly lower FN BMD in comparison to non-SCI controls (p = 0.001).

CONCLUSIONS

Compromised BMD among individuals with SCI was not associated with a deficiency of vitamin D or other bone nutrients. The observed positive associations between BMD and leptin, insulin, adiponectin and VAT provide a framework to evaluate links between adiposity and bone health in a larger SCI cohort.

Adiponectin is associated with bone strength and fracture history in paralyzed men with spinal cord injury

We explored the association between adiponectin levels and bone strength in paralyzed men with spinal cord injury. We found that bone strength was inversely associated with circulating adiponectin levels. Thus, strength estimates and adiponectin levels may improve fracture risk prediction and detection of response to osteogenic therapies following spinal cord injury.

PURPOSE

Previous research has demonstrated an inverse relationship between circulating adiponectin and bone mineral density, suggesting that adiponectin may be used as a biomarker for bone health. However, this relationship may reflect indirect effects on bone metabolism via adipose-mediated mechanical pathways rather than the direct effects of adipokines on bone metabolism. Thus, we explored the association between circulating adiponectin levels and bone strength in 27 men with spinal cord injury.

METHODS

Plasma adiponectin levels were quantified by ELISA assay. Axial stiffness and maximal load to fracture of the distal femur were quantified via finite element analysis using reconstructed 3D models of volumetric CT scans. We also collected information on timing, location, and cause of previous fractures.

RESULTS

Axial stiffness and maximal load were inversely associated with circulating adiponectin levels (R (2) = 0.44, p = 0.01; R (2) = 0.58, p = 0.05) after adjusting for injury duration and lower extremity lean mass. In individuals with post-SCI osteoporotic fractures, distal femur stiffness (p = 0.01) and maximal load (p = 0.005) were lower, and adiponectin was higher (p = 0.04) than those with no fracture history.

CONCLUSIONS

Based on these findings, strength estimates may improve fracture risk prediction and detection of response to osteogenic therapies following spinal cord injury. Furthermore, our findings suggest that circulating adiponectin may indeed be a feasible biomarker for bone health and osteoporotic fracture risk in paralyzed individuals with spinal cord injury.

A Rehabilomics framework for personalized and translational rehabilitation research and care for individuals with disabilities: Perspectives and considerations for spinal cord injury

Despite many people having similar clinical presentation, demographic factors, and clinical care, outcome can differ for those sustaining significant injury such as spinal cord injury (SCI) and traumatic brain injury (TBI). In addition to traditional demographic, social, and clinical factors, variability also may be attributable to innate (including genetic, transcriptomic proteomic, epigenetic) biological variation that individuals bring to recovery and their unique response to their care and environment. Technologies collectively called "-omics" enable simultaneous measurement of an enormous number of biomolecules that can capture many potential biological contributors to heterogeneity of injury/disease course and outcome. Due to the nature of injury and complex disease, and its associations with impairment, disability, and recovery, rehabilitation does not lend itself to a singular "protocolized" plan of therapy. Yet, by nature and by necessity, rehabilitation medicine operates as a functional model of "Personalized Care". Thus, the challenge for successful programs of translational rehabilitation care and research is to identify viable approaches to examine broad populations, with varied impairments and functional limitations, and to identify effective treatment responses that incorporate personalized protocols to optimize functional recovery. The Rehabilomics framework is a translational model that provides an "-omics" overlay to the scientific study of rehabilitation processes and multidimensional outcomes. Rehabilomics research provides novel opportunities to evaluate the neurobiology of complex injury or chronic disease and can be used to examine methods and treatments for person-centered care among populations with disabilities. Exemplars for application in SCI and other neurorehabilitation populations are discussed.

Association of adiponectin protein and ADIPOQ gene variants with lumbar disc degeneration

Lumbar disc degeneration (LDD) is a widespread public health problem that may lead to disability and loss of productivity. Adiponectin is an adipokine secreted by adipose tissue and has been shown to be involved in cartilage homeostasis. In the present study, the association between the rs266729 (−11377C/G) and rs2241766 (45T/G) single nucleotide polymorphisms (SNPs) in the adiponectin gene (ADIPOQ) and LDD was investigated. In addition, the correlation between the plasma adiponectin level and LDD was examined. A total of 289 subjects, 168 patients with LDD and 122 healthy individuals, were recruited in the study. All subjects were genotyped for rs266729 and rs2241766 SNPs using polymerase chain reaction-restriction fragment length polymorphism. Circulating levels of adiponectin protein were measured using the ELISA technique. A strong association was found between adiponectin level and LDD (P<0.01), where high levels of adiponectin were found in patients compared with healthy controls. The increase in adiponectin level was not affected by gender. However, no significant differences were found in the genotype distribution or allelic frequency of the two examined polymorphisms between patients with LDD and healthy controls (P>0.05). In conclusion, adiponectin appears to be elevated in patients with LDD. The rs266729 and rs2241766 SNPs in the ADIPOQ gene are not associated with LDD.

Lentiviral delivery of PPARγ shRNA alters the balance of osteogenesis and adipogenesis, improving bone microarchitecture

INTRODUCTION

Skeletal aging is associated not only with alterations in osteoblast (OB) and osteoclast (OC) number and activity within the basic metabolic unit, but also with increased marrow adiposity. Peroxisome proliferator-activated receptor gamma (PPARγ) is commonly considered the master transcriptional regulator of adipogenesis, however, it has known roles in osteoblast and osteoclast function as well. Here, we designed a lentiviral delivery system for PPARγ shRNA, and examined its effects in vitro on bone marrow stromal cells (BMSC) and in a mouse intramedullary injection model.

METHODS

PPARγ shRNA was delivered by a replication-deficient lentiviral vector, after in vitro testing to confirm purity, concentration, and efficacy for Pparg transcript reduction. Next, control green fluorescent protein lentivirus or PPARγ shRNA expressing lentivirus were delivered by intramedullary injection into the femoral bone marrow of male SCID mice. Analyses included daily monitoring of animal health, and postmortem analysis at 4 weeks. Postmortem analyses included high resolution microcomputed tomography (microCT) reconstructions and analysis, routine histology and histomorphometric analysis, quantitative real time polymerase chain reaction analysis of Pparg transcript levels, and immunohistochemical analysis for markers of adipocytes (PPARγ, fatty acid binding protein 4 [FABP4]), osteoblasts (alkaline phosphatase [ALP], osteocalcin [OCN]), and osteoclasts (tartrate-resistant acid phosphatase [TRAP], Cathepsin K).

RESULTS

In vitro, PPARγ shRNA delivery significantly reduced Pparg expression in mouse BMSC, accompanied by a significant reduction in lipid droplet accumulation. In vivo, a near total reduction in mature marrow adipocytes was observed at 4 weeks postinjection. This was accompanied by significant reductions in adipocyte-specific markers. Parameters of trabecular bone were significantly increased by both microCT and histomorphometric analysis. By immunohistochemical staining and semi-quantification, a significant increase in OCN+osteoblasts and decrease in TRAP+multinucleated osteoclasts was observed with PPARγ shRNA treatment.

DISCUSSION

These findings suggest that acute loss of PPARγ in the bone marrow compartment has a significant role beyond anti-adipose effects. Specifically, we found pro-osteoblastogenic, anti-osteoclastic effects after PPARγ shRNA treatment, resulting in improved trabecular bone architecture. Future studies will examine the isolated and direct effects of PPARγ shRNA on OB and OC cell types, and it may help determine whether PPARγ antagonists are potential therapeutic agents for osteoporotic bone loss.