Targeting versican as a therapeutic strategy in Duchenne muscular dystrophy

Fibrosis drives muscle degeneration and weakness in Duchenne muscular dystrophy. This thesis identified versican as an important fibrosis-associated protein overexpressed in dystrophic muscles, with cellular expression reduced by glucocorticoids. Using novel mouse models, the importance of versican reduction in improving the contractile function of dystrophic muscles was also established

Glucocorticoids improve myogenic differentiation in vitro by suppressing the synthesis of versican, a transitional matrix protein overexpressed in dystrophic skeletal muscles

In Duchenne muscular dystrophy (DMD), a dysregulated extracellular matrix (ECM) directly exacerbates pathology. Glucocorticoids are beneficial therapeutics in DMD, and have pleiotropic effects on the composition and processing of ECM proteins in other biological contexts. The synthesis and remodelling of a transitional versican-rich matrix is necessary for myogenesis; whether glucocorticoids modulate this transitional matrix is not known. Here, versican expression and processing were examined in hindlimb and diaphragm muscles from mdx dystrophin-deficient mice and C57BL/10 wild type mice. V0/V1 versican (Vcan) mRNA transcripts and protein levels were upregulated in dystrophic compared to wild type muscles, especially in the more severely affected mdx diaphragm. Processed versican (versikine) was detected in wild type and dystrophic muscles, and immunoreactivity was highly associated with newly regenerated myofibres. Glucocorticoids enhanced C2C12 myoblast fusion by modulating the expression of genes regulating transitional matrix synthesis and processing. Specifically, Tgfβ1, Vcan and hyaluronan synthase-2 (Has2) mRNA transcripts were decreased by 50% and Adamts1 mRNA transcripts were increased three-fold by glucocorticoid treatment. The addition of exogenous versican impaired myoblast fusion, whilst glucocorticoids alleviated this inhibition in fusion. In dystrophic mdx muscles, versican upregulation correlated with pathology. We propose that versican is a novel and relevant target gene in DMD, given its suppression by glucocorticoids and that in excess it impairs myoblast fusion, a process key for muscle regeneration

A reduction in selenoprotein S amplifies the inflammatory profile of fast-twitch skeletal muscle in the mdx dystrophic mouse

Excessive inflammation is a hallmark of muscle myopathies, including Duchenne muscular dystrophy (DMD). There is interest in characterising novel genes that regulate inflammation due to their potential to modify disease progression. Gene polymorphisms in Selenoprotein S (Seps1) are associated with elevated proinflammatory cytokines, and in vitro SEPS1 is protective against inflammatory stress. Given that SEPS1 is highly expressed in skeletal muscle, we investigated whether the genetic reduction of Seps1 exacerbated inflammation in the mdx mouse. F1 male mdx mice with a heterozygous Seps1 deletion (mdx:Seps1−/+) were generated. The mdx:Seps1−/+ mice had a 50% reduction in SEPS1 protein expression in hindlimb muscles. In the extensor digitorum longus (EDL) muscles, mRNA expression of monocyte chemoattractant protein 1 (Mcp-1) (), macrophage marker F4/80 (), and transforming growth factor-β1 (Tgf-β1) () were increased in mdx:Seps1−/+ mice. This was associated with a reduction in muscle fibre size; however, ex vivo EDL muscle strength and endurance were unaltered. In dystrophic slow twitch soleus muscles, SEPS1 reduction had no effect on the inflammatory profile nor function. In conclusion, the genetic reduction of Seps1 appears to specifically exacerbate the inflammatory profile of fast-twitch muscle fibres, which are typically more vulnerable to degeneration in dystrophy

Differential production of type I IFN determines the reciprocal levels of IL-10 and proinflammatory cytokines produced by C57BL/6 and BALB/c macrophages

Pattern recognition receptors detect microbial products and induce cytokines, which shape the immunological response. IL-12, TNF-alpha, and IL-1 beta are proinflammatory cytokines, which are essential for resistance against infection, but when produced at high levels they may contribute to immunopathology. In contrast, IL-10 is an immunosuppressive cytokine, which dampens proinflammatory responses, but it can also lead to defective pathogen clearance. The regulation of these cytokines is therefore central to the generation of an effective but balanced immune response. In this study, we show that macrophages derived from C57BL/6 mice produce low levels of IL-12, TNF-alpha, and IL-1 beta, but high levels of IL-10, in response to TLR4 and TLR2 ligands LPS and Pam3CSK4, as well as Burkholderia pseudomallei, a Gram-negative bacterium that activates TLR2/4. In contrast, macrophages derived from BALB/c mice show a reciprocal pattern of cytokine production. Differential production of IL-10 in B. pseudomallei and LPS-stimulated C57BL/6 and BALB/c macrophages was due to a type I IFN and ERK1/2-dependent, but IL-27-independent, mechanism. Enhanced type I IFN expression in LPS-stimulated C57BL/6 macrophages was accompanied by increased STAT1 and IFN regulatory factor 3 activation. Furthermore, type I IFN contributed to differential IL-1 beta and IL-12 production in B. pseudomallei and LPS-stimulated C57BL/6 and BALB/c macrophages via both IL-10-dependent and -independent mechanisms. These findings highlight key pathways responsible for the regulation of pro- and anti-inflammatory cytokines in macrophages and reveal how they may differ according to the genetic background of the host.his work was supported by The Francis Crick Institute, which receives its core funding from Cancer Research UK (FC001126), the U.K. Medical Research Council (FC001126), and the Wellcome Trust (FC001126) since April 1, 2015 and before that by U.K. Medical Research Council Grant MRC U117565642 and also by European Research Council Grant 294682-TB-PATH (Crick 10127). A.H. was additionally funded by a U.K. Medical Research Council Centenary Award. M.S. was funded by Fundação para a Ciência e Tecnologia, Portugal Grant FCT-ANR/BIM-MEC/ 0007/2013. M.S. is an associate Fundação para a Ciência e Tecnologia, Portugal investigator.info:eu-repo/semantics/publishedVersio

Indonesia: balancing the United States and China, aiming for independence

This study provides an assessment of Indonesia’s relations with the United States and China, with a particular focus on security-related ties. Executive summary A country on the rise, Indonesia upholds a flexible foreign policy that allows it to productively engage with both the United States and China. Indonesian strategic thinking is dominated by the rise of China, the response to that rise, and how the rise will affect regional security architecture. Though Indonesia shares, and has historically shared, positive ties with the United States, Indonesia will avoid entering into an alliance and will continue to enmesh with both the United States and China. Indonesia places great importance on strong regional infrastructure, with ASEAN at the core, to maintain regional stability and to facilitate cooperation. By cementing regional institutions, Indonesia hopes to “engage and constrain” both China and the United States, especially in the face of increased Chinese assertiveness from 2010 onwards.   In a recent visit to the United States, Joko Widodo and Barack Obama committed to establishing a Strategic Partnership as well as an annual ministerial strategic dialogue — the next steps in the positive relationship between these two countries. Members of the Indonesian foreign policy community mostly view the United States as a fundamentally benign and trustworthy power, whereas Sino–Indonesian ties are tethered by an inherent wariness of Chinese intentions. Indonesia will continue to enjoy its middle-power status and largely benign external strategic environment. Time will tell if the changing South-East Asian security environment will deliver Indonesia, as Jokowi describes, “big country” status. Key points: Indonesia maintains a strong commitment to the foundational principle that the country should adopt a “free and active” foreign policy. This commitment means that Indonesia will not enter into a formal alliance, but will actively pursue enhanced bilateral ties with both the United States and China. Since independence, Indonesia has maintained a relatively cooperative and mutually supportive relationship with the United States. The current security partnership is limited by Indonesia’s current operating and strategic capacities, and a desire to maintain a diverse range of cooperative relationships. Indonesia’s relationship with China has been subject to sharp shifts, and while Indonesia seeks to benefit from closer economic relations with an economically rising China, the rise also underscores a persistent wariness in Indonesia that is likely to remain a limiting factor in the bilateral relationship

Finding a Voice/Reaching an Audience

Barry Hannah, moderato

Large and small assembly: combining functional macromolecules with small peptides to control the morphology of skeletal muscle progenitor cells

The material properties of natural tissues, such as skeletal muscle, are highly sophisticated and are synthetically challenging to mimic. Using natural biomacromolecules to functionalize self-assembled peptide (SAP) hydrogels has the potential to increase the utility of these materials by more closely reproducing the natural cellular environment. Here, to demonstrate that a conserved co-assembly pathway can retain distinct function, the biocompatible peptide derivative Fmoc-FRGDF was co-assembled with either a sulfated polysaccharide, fucoidan, or the provisional matrix proteoglycan, versican. Our results demonstrate that thermodynamically driven co-assembly with biologically active macromolecules is facile, stable, and does not affect the final assembled nanostructure. Biologically, the incorporation of these functionally distinct molecules had no effect on C2C12 myoblast proliferation and viability but strongly altered their morphology. The surface area of myoblasts cultured on the fucoidan scaffold was reduced at 24 and 72 h post seeding, with a reduction in the formation of multinucleated syncytia. Myoblasts cultured on versican scaffolds were smaller compared to cells grown on the empty vector scaffolds at 24 h but not 72 h post seeding, with multinucleated syncytia formation being unaffected. This work allows programmed and distinct morphological effects of cell behavior, paving the way for further mechanistic studies