Increased Serum and Musculotendinous Fibrogenic Proteins following Persistent Low-Grade Inflammation in a Rat Model of Long-Term Upper Extremity Overuse

Authors

Helen G. L. Gao, Paul W. Fisher, Alex G. Lambi, Christine K. Wade, Ann E. Barr-Gillespie, Steven N. Popoff, Mary F. Barbe

Abstract

We examined the relationship between grip strength declines and muscle-tendon responses induced by long-term performance of a high-repetition, low-force (HRLF) reaching task in rats. We hypothesized that grip strength declines would correlate with inflammation, fibrosis and degradation in flexor digitorum muscles and tendons. Grip strength declined after training, and further in weeks 18 and 24, in reach limbs of HRLF rats. Flexor digitorum tissues of reach limbs showed low-grade increases in inflammatory cytokines: IL-1β after training and in week 18, IL-1α in week 18, TNF-α and IL-6 after training and in week 24, and IL-10 in week 24, with greater increases in tendons than muscles. Similar cytokine increases were detected in serum with HRLF: IL-1α and IL-10 in week 18, and TNF-α and IL-6 in week 24. Grip strength correlated inversely with IL-6 in muscles, tendons and serum, and TNF-α in muscles and serum. Four fibrogenic proteins, TGFB1, CTGF, PDGFab and PDGFbb, and hydroxyproline, a marker of collagen synthesis, increased in serum in HRLF weeks 18 or 24, concomitant with epitendon thickening, increased muscle and tendon TGFB1 and CTGF. A collagenolytic gelatinase, MMP2, increased by week 18 in serum, tendons and muscles of HRLF rats. Grip strength correlated inversely with TGFB1 in muscles, tendons and serum; with CTGF-immunoreactive fibroblasts in tendons; and with MMP2 in tendons and serum. Thus, motor declines correlated with low-grade systemic and musculotendinous inflammation throughout task performance, and increased fibrogenic and degradative proteins with prolonged task performance. Serum TNF-α, IL-6, TGFB1, CTGF and MMP2 may serve as serum biomarkers of work-related musculoskeletal disorders, although further studies in humans are needed.

Link to Article

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0071875

Impact of Maternal Prenatal Stress on Growth of the Offspring

Authors

Sarah K. Amugongo, Leslea J. Hlusko

Abstract

Unperturbed fetal development is essential for future health of an individual. Previous studies have linked diseases of aging to harmful alterations that happen during fetal development. Given the significant long-term impact that intrauterine environment has on an individual’s life, it was hypothesized that maternal stress during pregnancy will have negative effects on the offspring’s prenatal and postnatal growth. To test this, twenty-eight female and seven male Wistar rats (Rattus norvegicus) were purchased and bred to produce 176 offspring. During pregnancy, dams were randomly divided into four groups (n=7, per group) and immobilization stress induced as follows; Group 1 (GW1): immobilization stress on days 1-7 of pregnancy, Group 2 (GW2): on days 8-14, Group 3 (GW3): on days 15-21, Group 4 (Controls): left undisturbed. Maternal cortisol hormone, food intake, and weight gain were monitored during pregnancy. Pups were raised under normal laboratory conditions and sacrificed at ages: 4, 8, 12, and 16 weeks to determine the effect of prenatal stress. At necropsy, the tibia was removed and processed for histology. Differences among groups were determined by T-test or analysis of variance (ANOVA). Linear regression analysis was performed to establish the relationship between stress in utero and indicators of bone development in offspring. P values ≤ 0.05 were considered significant. Cortisol hormone levels in controls were lower than those of stressed animals. Stressed dams consumed 12.5% less food per day compared to controls. Animals in GW1 and GW2 gained less weight during pregnancy but had larger litters than did GW3 or the control group. Offspring born to GW3 were heavier compared to all other groups. GW3 offspring had a higher rate of bone formation. In conclusion, stress during pregnancy resulted in increased cortisol and reduced food intake in mothers, but faster growth and higher weight gain in offspring compared to controls.

Link to Article

http://www.aginganddisease.org/AD-2013-Amugongo.pdf

F-fluoride Positron Emission Tomography Measurements of Regional Bone Formation in Hemodialysis Patients with Suspected Adynamic Bone Disease

Authors

Michelle L. Frost, Juliet E. Compston, David Goldsmith, Amelia E. Moore, Glen M. Blake, Musib Siddique, Linda Skingle, Ignac Fogelman

Abstract

18F-fluoride positron emission tomography (18F-PET) allows the assessment of regional bone formation and could have a role in the diagnosis of adynamic bone disease (ABD) in patients with chronic kidney disease (CKD). The purpose of this study was to examine bone formation at multiple sites of the skeleton in hemodialysis patients (CKD5D) and assess the correlation with bone biopsy. Seven CKD5D patients with suspected ABD and 12 osteoporotic postmenopausal women underwent an 18F-PET scan, and bone plasma clearance, K i, was measured at ten skeletal regions of interest (ROI). Fifteen subjects had a transiliac bone biopsy following double tetracycline labeling. Two CKD5D patients had ABD confirmed by biopsy. There was significant heterogeneity in K i between skeletal sites, ranging from 0.008 at the forearm to 0.028 mL/min/mL at the spine in the CKD5D group. There were no significant differences in K i between the two study groups or between the two subjects with ABD and the other CKD5D subjects at any skeletal ROI. Five biopsies from the CKD5D patients had single tetracycline labels only, including the two with ABD. Using an imputed value of 0.3 μm/day for mineral apposition rate (MAR) for biopsies with single labels, no significant correlations were observed between lumbar spine K i corrected for BMAD (K i/BMAD) and bone formation rate (BFR/BS), or MAR. When biopsies with single labels were excluded, a significant correlation was observed between K i/BMAD and MAR (r = 0.81, p = 0.008) but not BFR/BS. Further studies are required to establish the sensitivity of 18F-PET as a diagnostic tool for identifying CKD patients with ABD.

Link to Article

http://dx.doi.org/10.1007/s00223-013-9778-7

Extracellular Norepinephrine Clearance by the Norepinephrine Transporter Is Required for Skeletal Homeostasis

Authors

Yun Ma, Jessica J. Krueger, Sara N. Redmon, Sasidhar Uppuganti, Jeffry S. Nyman, Maureen K. Hahn, and Florent Elefteriou

Abstract

Changes in bone remodeling induced by pharmacological and genetic manipulation of β-adrenergic receptor (βAR) signaling in osteoblasts support a role of sympathetic nerves in the regulation of bone remodeling. However, the contribution of endogenous sympathetic outflow and nerve-derived norepinephrine (NE) to bone remodeling under pathophysiological conditions remains unclear. We show here that differentiated osteoblasts, like neurons, express the norepinephrine transporter (NET), exhibit specific NE uptake activity via NET and can catabolize, but not generate, NE. Pharmacological blockade of NE transport by reboxetine induced bone loss in WT mice. Similarly, lack of NE reuptake in norepinephrine transporter (Net)-deficient mice led to reduced bone formation and increased bone resorption, resulting in suboptimal peak bone mass and mechanical properties associated with low sympathetic outflow and high plasma NE levels. Last, daily sympathetic activation induced by mild chronic stress was unable to induce bone loss, unless NET activity was blocked. These findings indicate that the control of endogenous NE release and reuptake by presynaptic neurons and osteoblasts is an important component of the complex homeostatic machinery by which the sympathetic nervous system controls bone remodeling. These findings also suggest that drugs antagonizing NET activity, used for the treatment of hyperactivity disorders, may have deleterious effects on bone accrual.

Link to Article

http://dx.doi.org/10.1074/jbc.M113.481309

Effects of Vitamin E on Bone Biomechanical and Histomorphometric Parameters in Ovariectomized Rats

Authors

Rafaela G. Feresin, Sarah A. Johnson, Marcus L. Elam, Jeong-Su Kim, Dania A. Khalil, Edralin A. Lucas, Brenda J. Smith, Mark E. Payton, Mohammed P. Akhter, and Bahram H. Arjmandi

Abstract

The present study examined the dose-dependent effect of vitamin E in reversing bone loss in ovariectomized (Ovx) rats. Sprague-Dawley rats were either Sham-operated (Sham) or Ovx and fed control diet for 120 days to lose bone. Subsequently, rats were divided into 5 groups (/group): Sham, Ovx-control, low dose (Ovx + 300 mg/kg diet; LD), medium dose (Ovx + 525 mg/kg diet; MD), and high dose (Ovx + 750 mg/kg diet; HD) of vitamin E and sacrificed after 100 days. Animals receiving MD and HD of vitamin E had increased serum alkaline phosphatase compared to the Ovx-control group. Bone histomorphometry analysis indicated a decrease in bone resorption as well as increased bone formation and mineralization in the Ovx groups supplemented with MD and HD of vitamin E. Microcomputed tomography findings indicated no effects of vitamin E on trabecular bone of fifth lumbar vertebrae. Animals receiving HD of vitamin E had enhanced fourth lumbar vertebra quality as evidenced by improved ultimate and yield load and stress when compared to Ovx-control group. These findings demonstrate that vitamin E improves bone quality, attenuates bone resorption, and enhances the rate of bone formation while being unable to restore bone density and trabecular bone structure.

Link to Article

http://dx.doi.org/10.1155/2013/825985

Co-expression of Arabidopsis transcription factor, AtMYB12, and soybean isoflavone synthase, GmIFS1, genes in tobacco leads to enhanced...

Title

Co-expression of Arabidopsis transcription factor, AtMYB12, and soybean isoflavone synthase, GmIFS1, genes in tobacco leads to enhanced biosynthesis of isoflavones and flavonols resulting in osteoprotective activity

Authors

Ashutosh Pandey, Prashant Misra, Mohd P. Khan, Gaurav Swarnkar, Mahesh C. Tewari, Sweta Bhambhani, Ritu Trivedi, Naibedya Chattopadhyay, Prabodh K. Trivedi

Abstract

Isoflavones, a group of flavonoids, restricted almost exclusively to family Leguminosae are known to exhibit anticancerous and anti-osteoporotic activities in animal systems and have been a target for metabolic engineering in commonly consumed food crops. Earlier efforts based on the expression of legume isoflavone synthase (IFS) genes in nonlegume plant species led to the limited success in terms of isoflavone content in transgenic tissue due to the limitation of substrate for IFS enzyme. In this work to overcome this limitation, the activation of multiple genes of flavonoid pathway using Arabidopsis transcription factor AtMYB12 has been carried out. We developed transgenic tobacco lines constitutively co-expressing AtMYB12 and GmIFS1 (soybean IFS) genes or independently and carried out their phytochemical and molecular analyses. The leaves of co-expressing transgenic lines were found to have elevated flavonol content along with the accumulation of substantial amount of genistein glycoconjugates being at the highest levels that could be engineered in tobacco leaves till date. Oestrogen-deficient (ovariectomized, Ovx) mice fed with leaf extract from transgenic plant co-expressing AtMYB12 and GmIFS1 but not wild-type extract exhibited significant conservation of trabecular microarchitecture, reduced osteoclast number and expression of osteoclastogenic genes, higher total serum antioxidant levels and increased uterine oestrogenicity compared with Ovx mice treated with vehicle (control). The skeletal effect of the transgenic extract was comparable to oestrogen-treated Ovx mice. Together, our results establish an efficient strategy for successful pathway engineering of isoflavones and other flavonoids in crop plants and provide a direct evidence of improved osteoprotective effect of transgenic plant extract.

Link to Article

http://dx.doi.org/10.1111/pbi.12118