Expression of Interleukin-6 (IL-6) and IL-6 receptor mRNA in human bone samples from pre- and postmenopausal women

Cross-talk between primary osteocytes and bone marrow macrophages for osteoclastogenesis upon collagen treatment

Homeostasis of osteoclast formation from bone marrow macrophages (BMM) is regulated by paracrine signals of the neighbourhood bone cells particularly mesenchymal stem cells (MSC), osteoblasts and osteocytes (OC). Besides paracrine cues, collagen and glycosaminoglycan are involved in controlling bone homeostasis. Towards this approach, different molecular weight collagens were reacted with MSC, OC and BMM to understand the bone homeostasis activity of collagen. The up-regulating effect of collagens on osteogenic cell growth was confirmed by the presence of mineralized nodules in the osteoblastogenic lineage cells and increased osteogenic stimulatory gene expression. The decreased BMM-derived TRAP+ osteoclasts number and osteoclastogenic regulatory gene expression of OC could demonstrate the exploitive osteoclastogenic activity of collagens. Osteoclastogenesis from BMM was triggered by paracrine cues of OC in some extend, but it was down-regulated by collagen. Overall, the effect of collagen on osteoclastogenesis and osteoblastogenesis may depend on the molecular weight of collagens, and collagen suppresses osteoclastogenesis, at least in part by downregulating the secretion of cytokines in OC.

The effects of 6-gingerol on proliferation, differentiation, and maturation of osteoblast-like MG-63 cells

We investigated whether 6-gingerol affects the maturation and proliferation of osteoblast-like MG63 cells in vitro. Osteoblast-like MG63 cells were treated with 6-gingerol under control conditions, and experimental inflammation was induced by tumor necrosis factor-α (TNF-α). Expression of different osteogenic markers and cytokines was analyzed by real-time PCR, Western blotting, and enzyme-linked immunosorbent assay. In addition, alkaline phosphatase (ALP) enzyme activity and biomineralization as markers for differentiation were measured. Treatment with 6-gingerol resulted in insignificant effects on the proliferation rate. 6-Gingerol induced the differentiation of osteoblast-like cells with increased transcription levels of osteogenic markers, upregulated ALP enzyme activity, and enhanced mineralized nodule formation. Stimulation with TNF-α led to enhanced interleukin-6 and nuclear factor-κB expression and downregulated markers of osteoblastic differentiation. 6-Gingerol reduced the degree of inflammation in TNF-α-treated MG-63 cells. In conclusion, 6-gingerol stimulated osteoblast differentiation in normal physiological and inflammatory settings, and therefore, 6-gingerol represents a promising agent for treating osteoporosis or bone inflammation.

Interleukin-6 maintains bone marrow-derived mesenchymal stem cell stemness by an ERK1/2-dependent mechanism

Adult human mesenchymal stem cells (MSCs) hold promise for an increasing list of therapeutic uses due to their ease of isolation, expansion, and multi-lineage differentiation potential. To maximize the clinical potential of MSCs, the underlying mechanisms by which MSC functionality is controlled must be understood. We have taken a deconstructive approach to understand the individual components in vitro, namely the role of candidate "stemness" genes. Our recent microarray gene expression profiling data suggest that interleukin-6 (IL-6) may contribute to the maintenance of MSCs in their undifferentiated state. In this study, we showed that IL-6 gene expression is significantly higher in undifferentiated MSCs as compared to their chondrogenic, osteogenic, and adipogenic derivatives. Moreover, we found that MSCs secrete copious amounts of IL-6 protein, which decreases dramatically during osteogenic differentiation. We further evaluated the role of IL-6 for maintenance of MSC "stemness," using a series of functional assays. The data showed that IL-6 is both necessary and sufficient for enhanced MSC proliferation, protects MSCs from apoptosis, inhibits adipogenic and chondrogenic differentiation of MSCs, and increases the rate of in vitro wound healing of MSCs. We further identified ERK1/2 activation as the key pathway through which IL-6 regulates both MSC proliferation and inhibition of differentiation. Taken together, these findings show for the first time that IL-6 maintains the proliferative and undifferentiated state of bone marrow-derived MSCs, an important parameter for the optimization of both in vitro and in vivo manipulation of MSCs.

Gender differences in mortality after mitral valve operation: evidence for higher mortality in perimenopausal women

BACKGROUND

Hormonal status is a potentially important cause for gender differences in outcomes after cardiovascular operations. Estrogen withdrawal states may potentiate ischemia-reperfusion injury by impairing endothelial cell function and increasing inflammatory cytokine levels. We hypothesized that gender influences mortality after mitral valve operations and that it varies with age, especially during periods of declining ovarian function.

METHODS

We studied 24,977 patients (49% women) in The Society of Thoracic Surgeons National Database who underwent isolated mitral valve repair or replacement from 2002 to 2005. Age-related gender differences in mortality after mitral valve operation were compared by risk-adjusted analysis.

RESULTS

Gender and age had a pronounced impact on hospital mortality. Women aged 40 to 49 and 50 to 59 had significantly greater hospital mortality than risk-matched men. The adjusted female/male odds ratio for hospital mortality in the group aged 40 to 49 was 2.56 (95% confidence interval, 1.31 to 5.01) but progressively decreased in the four subsequent age groups. This pattern was statistically significant (p = 0.028 and p = 0.018 for 40 to 49 vs 70 to 79 and 80 to 89, respectively) and represents a declining relative mortality risk for women of advanced age.

CONCLUSIONS

In patients aged 40 to 59 years, the mortality of mitral valve operation is approximately 2.5 times higher in women compared with men with similar risk factors. This survival disadvantage diminishes with further aging. Changes in ovarian function may be an important cause for this gender-age interaction and are a potential target for novel hormone-based therapies.

Inflammatory biomarkers increase with severity of upper-extremity overuse disorders

MSDs (musculoskeletal disorders) from overuse are common occupational health problems that cause pain, functional loss and loss of work time. The aim of the present study was to determine whether a relationship exists between the severity of early-onset overuse-related MSDs of the upper extremity and serum levels of IL-1beta (interleukin-1beta), TNF-alpha (tumour necrosis factor-alpha), IL-6 (interleukin-6) and CRP (C-reactive protein). Twenty-two subjects with upper-extremity MSDs due to overuse for no longer that 12 weeks were stratified according to the severity of upper-extremity signs and symptoms as determined by a UBMA (upper-body musculoskeletal assessment). Nine asymptomatic subjects also participated. Serum cytokines were analysed using ELISA, and CRP was analysed using a laser nephelometry technique. CRP was strongly correlated, and TNF-alpha, IL-1beta and IL-6 were moderately correlated, with UBMA scores. Only CRP and TNFalpha were significantly associated with UBMA scores in an ordinal logistic regression analysis in which age and BMI (body mass index) were covariates. These results are of clinical importance as they suggest that early-onset overuse-related MSDs may have an inflammatory component. The possibility of using a combination of serum biomarkers to follow the progression of overuse-related MSDs or their response to therapeutic intervention may be of interest to clinical practitioners and should be the focus of future research.

Age-related changes in cortical bone content of insulin-like growth factor binding protein (IGFBP)-3, IGFBP-5, osteoprotegerin, and calcium in postmenopausal osteoporosis: a cross-sectional study

Serum GH and IGF-I levels decline with increasing age, whereas osteoprotegerin (OPG) increases. IGFs as well as OPG are present in bone matrix and mediate the effects of many upstream hormones (e.g. estrogen). To evaluate whether changes in these proteins may to some extent explain the decrease in bone mass in postmenopausal or senile osteoporosis, we measured bone contents of IGF-I, IGF-II, IGF binding protein (IGFBP)-3, IGFBP-5, and OPG in combined extracts obtained after EDTA and guanidine hydrochloride extraction in 60 postmenopausal women aged 47-74 (mean, 63) yr with a previous distal forearm fracture and a hip or spine Z-score less than 0. We found age-related increases in IGFBP-3 (r = 0.35; P < 0.01), IGFBP-5 (r = 0.59; P < 0.001), and OPG (r = 0.36; P < 0.01) in cortical bone, significantly inversely correlated with femoral neck and lumbar spine BMD. A correlation between age and OPG was also detected in trabecular bone (r = 0.27; P < 0.05). A pronounced age-related decrease in cortical calcium contents (r = -0.60; P < 0.001), positively correlated with femoral neck and lumbar spine BMD, was also found. No age-related changes were detected for IGF-I or IGF-II. The present study demonstrates age-related changes in cortical bone contents of IGFBPs, calcium, and OPG, possibly related to the pathophysiology of postmenopausal osteoporosis. As for OPG, our findings probably represent compensatory responses to increased osteoclastic resorption.