scholarly journals Fracture, aging, and disease in bone

2006 ◽  
Vol 21 (8) ◽  
pp. 1878-1892 ◽  
Author(s):  
J.W. Ager ◽  
G. Balooch ◽  
R.O. Ritchie
Keyword(s):  
Fracture Mechanics ◽  
Crack Growth ◽  
Materials Science ◽  
Transforming Growth Factor ◽  
Ex Vivo ◽  
Transforming Growth Factor Β ◽  
Bone Fragility ◽  
Initiation Toughness ◽  
Public Health Perspective ◽  
Multiple Length Scales

From a public health perspective, developing a detailed mechanistic understanding of the well-known increase with age in fracture risk of human bone is essential. This also represents a challenge from materials science and fracture mechanics viewpoints. Bone has a complex, hierarchical structure with characteristic features ranging from nanometer to macroscopic dimensions; it is therefore significantly more complex than most engineering materials. Nevertheless, by examining the micro-/nanostructural changes accompanying the process of aging using appropriate multiscale experimental methods and relating them to fracture mechanics data, it is possible to obtain a quantitative picture of how bone resists fracture. As human cortical bone exhibits rising ex vivo crack-growth resistance with crack extension, its fracture toughness must be evaluated in terms of resistance-curve (R-curve) behavior. While the crack initiation toughness declines with age, the more striking finding is that the crack-growth toughness declines even more significantly and is essentially absent in bone from donors exceeding 85 years in age. To explain such an age-induced deterioration in the toughness of bone, we evaluate its fracture properties at multiple length scales, specifically at the molecular and nano dimensions using vibrational spectroscopies, at the microscale using electron microscopy and hard/soft x-ray computed tomography, and at the macroscale using R-curve measurements. We show that the reduction in crack-growth toughness is associated primarily with a degradation in the degree of extrinsic toughening, in particular involving crack bridging, and that this occurs at relatively coarse size scales in the range of tens to hundreds of micrometers. Finally, we briefly describe how specific clinical treatments, e.g., with steroid hormones to treat various inflammatory conditions, can prematurely damage bone, thereby reducing its fracture resistance, whereas regulating the level of the cytokine Transforming Growth Factor-β can offer significant improvements in the stiffness, strength, and toughness of bone and as such may be considered a therapeutic target to treat increased bone fragility induced by aging, drugs, and disease.

scholarly journals Granulosal and thecal expression of bone morphogenetic protein- and activin-binding protein mRNA transcripts during bovine follicle development and factors modulating their expression in vitro

Reproduction ◽  
2011 ◽  
Vol 142 (4) ◽  
pp. 581-591 ◽  
Author(s):  
Claire Glister ◽  
Leanne Satchell ◽  
Phil G Knight
Keyword(s):  
Bone Morphogenetic Proteins ◽  
Transforming Growth Factor ◽  
Ex Vivo ◽  
Mrna Level ◽  
Transcript Abundance ◽  
Transforming Growth Factor Β ◽  
Follicle Development ◽  
Mrna Levels ◽  
Theca Interna

Evidence supports local roles for transforming growth factor β superfamily members including activins and bone morphogenetic proteins (BMP) in follicle development. Access of these ligands to signalling receptors is likely modulated by extracellular binding proteins (BP). In this study, we comparedex vivoexpression of four BPs (chordin, gremlin, noggin and follistatin) in granulosal (GC) and theca interna (TC) compartments of developing bovine antral follicles (1–18 mm). Effects of FSH and IGF on BMP and BP expression by cultured GC, and effects of LH and BMPs on BP expression by cultured TC were also examined. Follicular expression of all four BP transcripts was higher in GC than TC compartments (P<0.001) a finding confirmed by immunohistochemistry. Follicle category affected (P<0.01) gremlin and follistatin mRNA abundance, with a significant cell-type×follicle category interaction for chordin, follistatin and noggin. Noggin transcript abundance was lower (P<0.05) in GC of large ‘E-active’ than ‘E-inactive’ follicles while follistatin mRNA level was higher (P<0.01). FSH enhanced CYP19, FSHR, INHBA and follistatin by GC without affecting BMP or BMP–BP expression. IGF increased CYP19 and follistatin, reduced BMP4, noggin and gremlin but did not affect chordin orFSHRmRNA levels. LH increased TC androgen secretion but had no effect on BMP or BP expression. BMPs uniformly suppressed TC androgen production whilst increasing chordin, noggin and gremlin mRNA levels up to 20-fold (P<0.01). These findings support the hypothesis that extracellular BP, mostly from GC, contribute to the regulation of intrafollicular BMP/activin signalling. Enhancement of thecal BP expression by BMP implies an autoregulatory feedback role to prevent excessive signalling.

scholarly journals Intercellular coupling between peripheral circadian oscillators by TGF-β signaling

2021 ◽  
Vol 7 (30) ◽  
pp. eabg5174
Author(s):  
Anna-Marie Finger ◽  
Sebastian Jäschke ◽  
Marta del Olmo ◽  
Robert Hurwitz ◽  
Adrián E. Granada ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Transforming Growth Factor ◽  
Clock Genes ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Transforming Growth Factor Β ◽  
Molecular Clocks ◽  
Peripheral Oscillators ◽  
Circadian Oscillators

Coupling between cell-autonomous circadian oscillators is crucial to prevent desynchronization of cellular networks and disruption of circadian tissue functions. While neuronal oscillators within the mammalian central clock, the suprachiasmatic nucleus, couple intercellularly, coupling among peripheral oscillators is controversial and the molecular mechanisms are unknown. Using two- and three-dimensional mammalian culture models in vitro (mainly human U-2 OS cells) and ex vivo, we show that peripheral oscillators couple via paracrine pathways. We identify transforming growth factor–β (TGF-β) as peripheral coupling factor that mediates paracrine phase adjustment of molecular clocks through transcriptional regulation of core-clock genes. Disruption of TGF-β signaling causes desynchronization of oscillator networks resulting in reduced amplitude and increased sensitivity toward external zeitgebers. Our findings reveal an unknown mechanism for peripheral clock synchrony with implications for rhythmic organ functions and circadian health.

scholarly journals Interleukin-10- and Transforming Growth Factor β-Independent Regulation of CD8+T Cells Expressing Type 1 and Type 2 Cytokines in Human Lymphatic Filariasis

2014 ◽  
Vol 21 (12) ◽  
pp. 1620-1627 ◽  
Author(s):  
Rajamanickam Anuradha ◽  
Parakkal Jovvian George ◽  
Paul Kumaran ◽  
Thomas B. Nutman ◽  
Subash Babu
Keyword(s):  
T Cells ◽  
Growth Factor ◽  
Lymphatic Filariasis ◽  
Transforming Growth Factor ◽  
Ex Vivo ◽  
Transforming Growth Factor Β ◽  
Necrosis Factor Alpha ◽  
Type 2 Cytokines

ABSTRACTLymphatic filariasis is known to be associated with diminished CD4+Th1 and elevated CD4+Th2 responses to parasite-specific antigens. The roles of cytokine-expressing CD8+T cells in immune responses to filarial infections are not well defined. To study the roles of CD8+T cells expressing type 1, type 2, and type 17 cytokines in filarial infections, we examined the frequencies of these cells in clinically asymptomatic, patently infected (INF) individuals, directlyex vivoand in response to parasite or nonparasite antigens; these frequencies were compared with the results for individuals with filarial lymphedema (i.e., clinical pathology [CP]) and those without active infection or pathology (i.e., endemic normal [EN]). INF individuals exhibited significant decreases in the frequencies of CD8+T cells expressing tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), and interleukin-22 (IL-22) at baseline and/or in response to filarial antigens, compared with CP and EN individuals. In contrast, the same individuals exhibited significant increases in the frequencies of CD8+T cells expressing IL-4, IL-5, IL-9, IL-13, and IL-21, compared with CP and/or EN individuals. Curative treatment resulted in significantly increased frequencies of CD8+T cells expressing IL-2 and significantly decreased frequencies of CD8+T cells expressing type 2 cytokines. Finally, the regulation of these responses appears to be independent of IL-10 and transforming growth factor β (TGF-β), since blockade of IL-10 or TGF-β signaling did not significantly alter the frequencies of type 1 or type 2 cytokine-expressing CD8+T cells. Our findings suggest that alterations in the frequencies of cytokine-expressing CD8+T cells are characteristic features of lymphatic filarial infections.

scholarly journals Efficient Human Cytomegalovirus Reactivation Is Maturation Dependent in the Langerhans Dendritic Cell Lineage and Can Be Studied using a CD14+Experimental Latency Model

2012 ◽  
Vol 86 (16) ◽  
pp. 8507-8515 ◽  
Author(s):  
Margaret M. Huang ◽  
Verity G. Kew ◽  
Kevin Jestice ◽  
Mark R. Wills ◽  
Matthew B. Reeves
Keyword(s):  
Dendritic Cell ◽  
Human Cytomegalovirus ◽  
Healthy Donor ◽  
Transforming Growth Factor ◽  
Ex Vivo ◽  
Cell Lineage ◽  
Transforming Growth Factor Β ◽  
Dependent Manner ◽  
Mediated Effects ◽  
Cytomegalovirus Reactivation

Studies from a number of laboratories have shown that the myeloid lineage is prominent in human cytomegalovirus (HCMV) latency, reactivation, dissemination, and pathogenesis. Existing as a latent infection in CD34+progenitors and circulating CD14+monocytes, reactivation is observed upon differentiation to mature macrophage or dendritic cell (DC) phenotypes. Langerhans' cells (LCs) are a subset of periphery resident DCs that represent a DC population likely to encounter HCMV early during primary infection. Furthermore, we have previously shown that CD34+derived LCs are a site of HCMV reactivationex vivo. Accordingly, we have utilized healthy-donor CD34+cells to study latency and reactivation of HCMV in LCs. However, the increasing difficulty acquiring healthy-donor CD34+cells—particularly from seropositive donors due to the screening regimens used—led us to investigate the use of CD14+monocytes to generate LCs. We show here that CD14+monocytes cultured with transforming growth factor β generate Langerin-positive DCs (MoLCs). Consistent with observations using CD34+derived LCs, only mature MoLCs were permissive for HCMV infection. The lytic infection of mature MoLCs is productive and results in a marked inhibition in the capacity of these cells to promote T cell proliferation. Pertinently, differentiation of experimentally latent monocytes to the MoLC phenotype promotes reactivation in a maturation and interleukin-6 (IL-6)-dependent manner. Intriguingly, however, IL-6-mediated effects were restricted to mature LCs, in contrast to observations with classical CD14+derived DCs. Consequently, elucidation of the molecular basis behind the differential response of the two DC subsets should further our understanding of the fundamental mechanisms important for reactivation.

scholarly journals Regional variation in arterial stiffening and dysfunction in Western diet-induced obesity

2015 ◽  
Vol 309 (4) ◽  
pp. H574-H582 ◽  
Author(s):  
Shawn B. Bender ◽  
Jorge A. Castorena-Gonzalez ◽  
Mona Garro ◽  
Constantino C. Reyes-Aldasoro ◽  
James R. Sowers ◽  
...  
Keyword(s):  
Coronary Arteries ◽  
Regional Variation ◽  
Transforming Growth Factor ◽  
Ex Vivo ◽  
Transforming Growth Factor Β ◽  
Western Diet ◽  
Internal Elastic Lamina ◽  
Arterial Stiffening ◽  
Femoral Arteries

Increased central vascular stiffening, assessed in vivo by determination of pulse wave velocity (PWV), is an independent predictor of cardiovascular event risk. Recent evidence demonstrates that accelerated aortic stiffening occurs in obesity; however, little is known regarding stiffening of other disease-relevant arteries or whether regional variation in arterial stiffening occurs in this setting. We addressed this gap in knowledge by assessing femoral PWV in vivo in conjunction with ex vivo analyses of femoral and coronary structure and function in a mouse model of Western diet (WD; high-fat/high-sugar)-induced obesity and insulin resistance. WD feeding resulted in increased femoral PWV in vivo. Ex vivo analysis of femoral arteries revealed a leftward shift in the strain-stress relationship, increased modulus of elasticity, and decreased compliance indicative of increased stiffness following WD feeding. Confocal and multiphoton fluorescence microscopy revealed increased femoral stiffness involving decreased elastin/collagen ratio in conjunction with increased femoral transforming growth factor-β (TGF-β) content in WD-fed mice. Further analysis of the femoral internal elastic lamina (IEL) revealed a significant reduction in the number and size of fenestrae with WD feeding. Coronary artery stiffness and structure was unchanged by WD feeding. Functionally, femoral, but not coronary, arteries exhibited endothelial dysfunction, whereas coronary arteries exhibited increased vasoconstrictor responsiveness not present in femoral arteries. Taken together, our data highlight important regional variations in the development of arterial stiffness and dysfunction associated with WD feeding. Furthermore, our results suggest TGF-β signaling and IEL fenestrae remodeling as potential contributors to femoral artery stiffening in obesity.

scholarly journals Tracking a TGF-β activator in vivo: sensitive PET imaging of αvβ8-integrin with the Ga-68-labeled cyclic RGD octapeptide trimer Ga-68-Triveoctin

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Neil Gerard Quigley ◽  
Katja Steiger ◽  
Frauke Richter ◽  
Wilko Weichert ◽  
Sebastian Hoberück ◽  
...  
Keyword(s):  
Human Subject ◽  
Transforming Growth Factor ◽  
Epithelial Mesenchymal Transition ◽  
Ex Vivo ◽  
Transforming Growth Factor Β ◽  
Integrin Expression ◽  
Target Tissue ◽  
Mesenchymal Transition ◽  
Positron Emission

Abstract Purpose As a major activator of transforming growth factor β (TGF-β), the RGD receptor αvβ8-integrin is involved in pathogenic processes related to TGF-β dysregulation, such as tumor growth, invasion, and radiochemoresistance, metastasis and tumor cell stemness, as well as epithelial-mesenchymal transition. The novel positron emission tomography (PET) radiopharmaceutical Ga-68-Triveoctin for in vivo mapping of αvβ8-integrin expression might enhance the prognosis of certain tumor entities, as well as support and augment TGF-β-targeted therapeutic approaches. Methods Monomeric and trimeric conjugates of cyclo(GLRGDLp(NMe)K(pent-4-ynoic amide)) were synthesized by click chemistry (CuAAC), labeled with Ga-68, and evaluated in MeWo (human melanoma) xenografted SCID mice by means of PET and ex-vivo biodistribution. αvβ8-integrin expression in murine tissues was determined by β8-IHC. A human subject received a single injection of 173 MBq of Ga-68-Triveoctin and underwent 3 subsequent PET/CT scans at 25, 45, and 90 min p.i.. Results The trimer Ga-68-Triveoctin exhibits a 6.7-fold higher αvβ8-integrin affinity than the monomer (IC50 of 5.7 vs. 38 nM, respectively). Accordingly, biodistribution showed a higher tumor uptake (1.9 vs. 1.0%IA/g, respectively) but a similar baseline upon blockade (0.25%IA/g for both). IHC showed an intermediate β8-expression in the tumor while most organs and tissues were found β8-negative. Low non-target tissue uptakes (< 0.4%IA/g) confirmed a low degree of unspecific binding. Due to its hydrophilicity (log D = − 3.1), Ga-68-Triveoctin is excreted renally and shows favorable tumor/tissue ratios in mice (t/blood: 6.7; t/liver: 6.8; t/muscle: 29). A high kidney uptake in mice (kidney-to-blood and -to-muscle ratios of 126 and 505, respectively) is not reflected by human PET (corresponding values are 15 and 30, respectively), which furthermore showed notable uptakes in coeliac and choroid plexus (SUVmean 6.1 and 9.7, respectively, 90 min p.i.). Conclusion Ga-68-Triveoctin enables sensitive in-vivo imaging αvβ8-integrin expression in murine tumor xenografts. PET in a human subject confirmed a favorable biodistribution, underscoring the potential of Ga-68-Triveoctin for mapping of αvβ8-integrin expression in a clinical setting.

scholarly journals Wet-dry-wet drug screen leads to the synthesis of TS1, a novel compound reversing lung fibrosis through inhibition of myofibroblast differentiation

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Nadja Anneliese Ruth Ring ◽  
Maria Concetta Volpe ◽  
Tomaž Stepišnik ◽  
Maria Grazia Mamolo ◽  
Panče Panov ◽  
...  
Keyword(s):  
Dopamine Receptor ◽  
High Throughput ◽  
Lung Fibrosis ◽  
Transforming Growth Factor ◽  
Ex Vivo ◽  
Interdisciplinary Approach ◽  
Transforming Growth Factor Β ◽  
Lung Fibroblasts ◽  
Myofibroblast Differentiation ◽  
Primary Fibroblasts

SummaryTherapies halting the progression of fibrosis are ineffective and limited. Activated myofibroblasts are emerging as important targets in the progression of fibrotic diseases. Previously, we performed a high-throughput screen on lung fibroblasts and subsequently demonstrated that the inhibition of myofibroblast activation is able to prevent lung fibrosis in bleomycin-treated mice. High-throughput screens are an ideal method of repurposing drugs, yet they contain an intrinsic limitation, which is the size of the library itself. Here, we exploited the data from our “wet” screen and used “dry” machine learning analysis to virtually screen millions of compounds, identifying novel anti-fibrotic hits which target myofibroblast differentiation, many of which were structurally related to dopamine. We synthesized and validated several compounds ex vivo (“wet”) and confirmed that both dopamine and its derivative TS1 are powerful inhibitors of myofibroblast activation. We further used RNAi-mediated knock-down and demonstrated that both molecules act through the dopamine receptor 3 and exert their anti-fibrotic effect by inhibiting the canonical transforming growth factor β pathway. Furthermore, molecular modelling confirmed the capability of TS1 to bind both human and mouse dopamine receptor 3. The anti-fibrotic effect on human cells was confirmed using primary fibroblasts from idiopathic pulmonary fibrosis patients. Finally, TS1 prevented and reversed disease progression in a murine model of lung fibrosis. Both our interdisciplinary approach and our novel compound TS1 are promising tools for understanding and combating lung fibrosis.

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