Macrophage migration inhibitory factor facilitates astrocytic production of the CCL2 chemokine following spinal cord injury.

Spinal cord injury causes accumulation of a large number of leukocytes at the lesion site where they contribute to excessive inflammation. Overproduced chemokines are responsible for the migratory process of the leukocytes, but the regulatory mechanism underlying the production of chemokines from resident cells of the spinal cord has not been fully elucidated. We examined the protein levels of macrophage migration inhibitory factor and chemokine C-C motif chemokine ligand 2 in a spinal cord contusion model at different time points following spinal cord injury. The elevation of macrophage migration inhibitory factor at the lesion site coincided with the increase of chemokine C-C motif chemokine ligand 2 abundance in astrocytes. Stimulation of primary cultured astrocytes with different concentrations of macrophage migration inhibitory factor recombinant protein induced chemokine C-C motif chemokine ligand 2 production from the cells, and the macrophage migration inhibitory factor inhibitor 4-iodo-6-phenylpyrimidine attenuated the stimulatory effect. Further investigation into the underlying mechanism on macrophage migration inhibitory factor-mediated astrocytic production of chemokine C-C motif chemokine ligand 2 revealed that macrophage migration inhibitory factor activated intracellular JNK signaling through binding with CD74 receptor. Administration of the macrophage migration inhibitory factor inhibitor 4-iodo-6-phenylpyrimidine following spinal cord injury resulted in the reduction of chemokine C-C motif chemokine ligand 2-recruited microglia/macrophages at the lesion site and remarkably improved the hindlimb locomotor function of rats. Our results have provided insights into the functions of astrocyte-activated chemokines in the recruitment of leukocytes and may be beneficial to develop interventions targeting chemokine C-C motif chemokine ligand 2 for neuroinflammation after spinal cord injury.

Targeting Senescent Tendon Stem/Progenitor Cells to Prevent or Treat Age-Related Tendon Disorders.

Age-related tendon disorder, a primary motor system disease, is characterized by biological changes in the tendon tissue due to senescence and seriously affects the quality of life of the elderly. The pathogenesis of this disease is not well-understood. Tendon stem/progenitor cells (TSPCs) exhibit multi-differentiation capacity. These cells are important cellular components of the tendon because of their roles in tendon tissue homeostasis, remodeling, and repair. Previous studies revealed alterations in the biological characteristics and tenogenic differentiation potential of TSPCs in senescent tendon tissue, in turn contributing to insufficient differentiation of TSPCs into tenocytes. Poor tendon repair can result in age-related tendinopathies. Therefore, targeting of senescent TSPCs may restore the tenogenic differentiation potential of these cells and achieve homeostasis of the tendon tissue to prevent or treat age-related tendinopathy. In this review, we summarize the biological characteristics of TSPCs and histopathological changes in age-related tendinopathy, as well as the potential mechanisms through which TSPCs contribute to senescence. This information may promote further exploration of innovative treatment strategies to rescue TSPCs from senescence.

Prevalence, Characteristics, and Associated Risk Factors of the Elderly with Hip Fractures: A Cross-Sectional Analysis of NHANES 2005-2010.

OBJECTIVE: This cross-sectional study was aimed to update the assessment of prevalence, characteristics, and risk factors of the elderly with hip fractures in a non-institutionalized American population. METHODS: This current study included a total of 31,034 participants from the existing National Health and Nutritional Examination Survey (NHANES) database from 2005 to 2010, and 4,265 participants aged 65 years and older were ultimately identified. Their condition of hip fractures was determined by method of questionnaires according to the orthopedic surgeons' diagnosis, and related epidemiological and demographic data were further collected. The univariate analysis was used to screen the risk factors of hip fractures in the elderly, and the logistic regression model was established to conduct the multivariate analysis. RESULTS: Of the total 4,265 participants with clear information of hip fractures in elderly, 127 individuals with hip fractures were identified according to results of questionnaires, exhibiting a prevalence of 28.49 per 1,000 (95% confidence interval [CI]=21.38-35.60) for males and 31.03 per 1,000 (95% CI=23.72-38.35) for females. The mean age of the elderly with hip fractures was 77.12±5.88 years and tumble (48.0%) was the primary factor. In univariate analysis, age, race, smoking, drinking alcohol, and combined with osteoporosis were regarded as risk factors. Multivariate analysis showed that age (80 years and older), living alone, smoking, combined with diabetes and osteoporosis were the independent risk factors. CONCLUSION: Our nationwide data indicate the prevalence of hip fractures in the elderly is generally on the rise, and the female occupies a higher proportion. Age (especially aged 80 years and older), race (mainly Non-Hispanic white), smoking, drinking alcohol, living alone, combined with diabetes and osteoporosis may be closely linked to the occurrence of hip fractures in the elderly, although these variables still need to be verified in further prospective investigations.

Understanding cellular and molecular mechanisms of pathogenesis of diabetic tendinopathy.

There is accumulating evidence of an increased incidence of tendon disorders in people with diabetes mellitus. Diabetic tendinopathy is an important cause of chronic pain, restricted activity, and even tendon rupture in individuals. Tenocytes and tendon stem/progenitor cells (TSPCs) are the dominant cellular components associated with tendon homeostasis, maintenance, remodeling, and repair. Some previous studies have shown alterations in tenocytes and TSPCs in high glucose or diabetic conditions that might cause structural and functional variations in diabetic tendons and even accelerate the development and progression of diabetic tendinopathy. In this review, the biomechanical properties and histopathological changes in diabetic tendons are described. Then, the cellular and molecular alterations in both tenocytes and TSPCs are summarized, and the underlying mechanisms involved are also analyzed. A better understanding of the underlying cellular and molecular pathogenesis of diabetic tendinopathy would provide new insight for the exploration and development of effective therapeutics.

CTGF Attenuates Tendon-Derived Stem/Progenitor Cell Aging.

Aged tendon-derived stem/progenitor cells (TSPCs) lead to age-related tendon disorders and impair tendon healing. However, the underlying molecular mechanisms of TSPC aging remain largely unknown. Here, we investigated the role of connective tissue growth factor (CTGF) in TSPC aging. CTGF protein and mRNA levels were markedly decreased in the aged TSPCs. Moreover, recombinant CTGF attenuates TSPC aging and restores the age-associated reduction of self-renewal and differentiation of TSPCs. In addition, cell cycle distribution of aged TSPCs was arrested in the G1/S phase while recombinant CTGF treatment promoted G1/S transition. Recombinant CTGF also rescued decreased levels of cyclin D1 and CDK4 and reduced p27kip1 expression in aged TSPCs. Our results demonstrated that CTGF plays a vital role in TSPC aging and might be a potential target for molecular therapy of age-related tendon disorders.

Tendon stem/progenitor cell ageing: Modulation and rejuvenation.

Tendon ageing is a complicated process caused by multifaceted pathways and ageing plays a critical role in the occurrence and severity of tendon injury. The role of tendon stem/progenitor cells (TSPCs) in tendon maintenance and regeneration has received increasing attention in recent years. The decreased capacity of TSPCs in seniors contributes to impaired tendon functions and raises questions as to what extent these cells either affect, or cause ageing, and whether these age-related cellular alterations are caused by intrinsic factors or the cellular environment. In this review, recent discoveries concerning the biological characteristics of TSPCs and age-related changes in TSPCs, including the effects of cellular epigenetic alterations and the mechanisms involved in the ageing process, are analyzed. During the ageing process, TSPCs ageing might occur as a natural part of the tendon ageing, but could also result from decreased levels of growth factor, hormone deficits and changes in other related factors. Here, we discuss methods that might induce the rejuvenation of TSPC functions that are impaired during ageing, including moderate exercise, cell extracellular matrix condition, growth factors and hormones; these methods aim to rejuvenate the features of youthfulness with the ultimate goal of improving human health during ageing.

[Quantitative assessment of urban ecosystem services flow based on entropy theory: A case study of Beijing, China]. / 基于熵理论的城市生态系统服务流定量评估­­ä»¥åŒ—京市为例.

Quantitative evaluation of ecosystem service is a primary premise for rational resources exploitation and sustainable development. Examining ecosystem services flow provides a scientific method to quantity ecosystem services. We built an assessment indicator system based on land cover/land use under the framework of four types of ecosystem services. The types of ecosystem services flow were reclassified. Using entropy theory, disorder degree and developing trend of indicators and urban ecosystem were quantitatively assessed. Beijing was chosen as the study area, and twenty-four indicators were selected for evaluation. The results showed that the entropy value of Beijing urban ecosystem during 2004 to 2015 was 0.794 and the entropy flow was -0.024, suggesting a large disordered degree and near verge of non-health. The system got maximum values for three times, while the mean annual variation of the system entropy value increased gradually in three periods, indicating that human activities had negative effects on urban ecosystem. Entropy flow reached minimum value in 2007, implying the environmental quality was the best in 2007. The determination coefficient for the fitting function of total permanent population in Beijing and urban ecosystem entropy flow was 0.921, indicating that urban ecosystem health was highly correlated with total permanent population.

Lentiviral Vector-Mediated p27kip1 Expression Facilitates Recovery After Spinal Cord Injury.

Traumatic spinal cord injury (SCI) causes tissue loss and associated neurological dysfunction attributable to both mechanical damage and secondary biochemical and physiological responses. Upregulation of cell cycle proteins occurs in both neurons and glia after SCI and may contribute to these changes. Increased cell cycle protein is associated with neuronal and oligodendroglial apoptosis, reactive astrogliosis, glial scar formation, and microglial activation. Here, using lentiviral vectors (LV), we induced the expression of the cyclin-dependent kinase (CDK) inhibitor p27kip1 in the lesioned spinal cord of adult rat. Treatment with LV-p27kip1 significantly reduced the expression of cell cycle proteins and improved functional recovery. In addition, p27kip1 overexpression also reduced lesion volume, decreased astrocytic reactivity, attenuated microglial activation, reduced cell death, and improved the local microenvironment. We suggest that these effects reflect the ability of p27kip1 to inhibit cell cycle pathways. Thus, the present study provides further support for the therapeutic potential of cell cycle inhibitors in the treatment of SCI.