Jacqueline M. Bourgeois

Endurance exercise rescues progeroid aging and induces systemic mitochondrial rejuvenation in mtDNA mutator mice

A causal role for mitochondrial DNA (mtDNA) mutagenesis in mammalian aging is supported by recent studies demonstrating that the mtDNA mutator mouse, harboring a defect in the proofreading-exonuclease activity of mitochondrial polymerase gamma, exhibits accelerated aging phenotypes characteristic of human aging, systemic mitochondrial dysfunction, multisystem pathology, and reduced lifespan. Epidemiologic studies in humans have demonstrated that endurance training reduces the risk of chronic diseases and extends life expectancy. Whether endurance exercise can attenuate the cumulative systemic decline observed in aging remains elusive. Here we show that 5 mo of endurance exercise induced systemic mitochondrial biogenesis, prevented mtDNA depletion and mutations, increased mitochondrial oxidative capacity and respiratory chain assembly, restored mitochondrial morphology, and blunted pathological levels of apoptosis in multiple tissues of mtDNA mutator mice. These adaptations conferred complete phenotypic protection, reduced multisystem pathology, and prevented premature mortality in these mice. The systemic mitochondrial rejuvenation through endurance exercise promises to be an effective therapeutic approach to mitigating mitochondrial dysfunction in aging and related comorbidities.

Molecular detection of the ETV6-NTRK3 gene fusion differentiates congenital fibrosarcoma from other childhood spindle cell tumors

Congenital fibrosarcoma (CFS) is a pediatric spindle cell tumor of the soft tissues that usually presents before the age of 2 years. Although these tumors display histologic features of malignancy and frequently recur, they have a relatively good prognosis and only rarely metastasize. CFS must therefore be differentiated from more aggressive spindle cell sarcomas that occur during childhood, particularly adult-type fibrosarcoma (ATFS), which can have an identical morphology. CFS must also be distinguished from benign but cellular fibroblastic lesions of the same age group, including infantile fibromatosis (IFB) and myofibromatosis (MFB). Unfortunately, standard pathologic examination often does not differentiate CFS from these other conditions. The authors recently identified a novel chromosomal translocation in CFS, t(12;15)(p13;q25), which gives rise to an ETV6-NTRK3 gene fusion. They subsequently developed reverse transcription-polymerase chain reaction (RT-PCR) assays that can detect ETV6-NTRK3 fusion transcripts in CFS frozen or paraffin-embedded tumor specimens. To confirm the use of this assay in the differential diagnosis of CFS, they have screened a larger series of childhood pediatric spindle cell lesions for ETV6-NTRK3 gene fusions, including 11 cases of CFS, 13 malignant spindle cell tumors (including ATFS), and 38 benign spindle cell tumors (including IFB and MFB). Of the 11 cases diagnosed as CFS, 10 showed the ETV6-NTRK3 gene fusion, whereas none of the 51 other malignant or benign spindle cell tumors demonstrated this fusion gene. They also compared their RT-PCR findings with those of conventional cytogenetics and with immunohistochemical detection of the ETV6-NTRK3 protein using antisera to NTRK3. They conclude that RT-PCR analysis is superior to these techniques for the detection of the ETV6-NTRK3 gene fusion in pediatric spindle cell tumors, and it is a reliable and specific modality for the diagnosis of CFS.

Massage Therapy Attenuates Inflammatory Signaling After Exercise-Induced Muscle Damage

Beneficial effects of massage on tired muscles work through anti-inflammatory and mitochondrial biogenesis pathways. The Mechanism of Massage Massage is a popular treatment—both for its putative healing properties and because it feels good—but is not among the usual tools of physicians. To validate its usefulness and understand how massage affects muscles in biomedical terms, Crane and his colleagues have documented the biological changes that massage evokes in the leg muscles of 11 young men who had just pushed themselves to exhaustion with heavy exercise. The exercise itself caused massive changes in gene expression, but after 10 min of massage, signaling pathways responsive to mechanical stresses were activated. Massage reduced signs of inflammation, and massaged muscle cells were better able to make new mitochondria—promoting faster recovery from exercise-induced muscle damage. Massage stretches and pulls muscles and, as one might expect, the authors found that mechanosensory sensors focal adhesion kinase–1 and its downstream effectors extracellular signaling kinases 1 and 2 were activated, as revealed by their increased phosphorylation. Several hours after massage, another downstream target of this pathway, PGC-1α, shifted into the nucleus, where it in turn activated transcription of its own targets COX7B and ND1. This set of responses indicated that additional mitochondria were forming, presumably accelerating healing of the muscle. Massage also altered the behavior of NFκB, causing less of this key inflammatory mediator to accumulate in the nucleus. Consequently, the NFκB-regulated heat shock proteins and immune cytokines interleukin-6 and tumor necrosis factor–α were less active, a sign of less cellular stress and inflammation. But one oft-repeated idea turned out not to be true. As others have shown, massage did not help clear lactic acid from tired muscles. And glycogen levels were also unchanged. Now that we know something about how massage heals, perhaps we will soon get some idea of why it is so enjoyable. Massage therapy is commonly used during physical rehabilitation of skeletal muscle to ameliorate pain and promote recovery from injury. Although there is evidence that massage may relieve pain in injured muscle, how massage affects cellular function remains unknown. To assess the effects of massage, we administered either massage therapy or no treatment to separate quadriceps of 11 young male participants after exercise-induced muscle damage. Muscle biopsies were acquired from the quadriceps (vastus lateralis) at baseline, immediately after 10 min of massage treatment, and after a 2.5-hour period of recovery. We found that massage activated the mechanotransduction signaling pathways focal adhesion kinase (FAK) and extracellular signal–regulated kinase 1/2 (ERK1/2), potentiated mitochondrial biogenesis signaling [nuclear peroxisome proliferator–activated receptor γ coactivator 1α (PGC-1α)], and mitigated the rise in nuclear factor κB (NFκB) (p65) nuclear accumulation caused by exercise-induced muscle trauma. Moreover, despite having no effect on muscle metabolites (glycogen, lactate), massage attenuated the production of the inflammatory cytokines tumor necrosis factor–α (TNF-α) and interleukin-6 (IL-6) and reduced heat shock protein 27 (HSP27) phosphorylation, thereby mitigating cellular stress resulting from myofiber injury. In summary, when administered to skeletal muscle that has been acutely damaged through exercise, massage therapy appears to be clinically beneficial by reducing inflammation and promoting mitochondrial biogenesis.

Nutritional therapy improves function and complements corticosteroid intervention in mdx mice

Corticosteroid therapy for Duchenne muscular dystrophy is effective but associated with long‐term side effects. To determine the potential therapeutic benefit from four nutritional compounds (creatine monohydrate, conjugated linoleic acid, α‐lipoic acid, and β‐hydroxy‐β‐methylbutyrate) alone, in combination, and with corticosteroids (prednisolone), we evaluated the effects on several variables in exercising mdx mice. Outcome measures included grip strength, rotarod performance, serum creatine kinase levels, muscle metabolites, internalized myonuclei, and retroperitoneal fat pad weight. In isolation, each nutritional treatment showed some benefit, with the combination therapy showing the most consistent benefits. Prednisolone and the combination therapy together provided the most consistent evidence of efficacy; increased peak grip strength (P < 0.05), decreased grip strength fatigue (P < 0.05), decreased number of internalized myonuclei (P < 0.01), and smaller retroperitoneal fat pad stores (P < 0.001). This study provided evidence for therapeutic benefit from a four‐compound combination therapy alone, and in conjunction with corticosteroids in the mdx model of DMD. Muscle Nerve, 2005

Naproxen does not alter indices of muscle damage in resistance-exercise trained men

PURPOSE Unaccustomed exercise is associated with an elevated plasma creatine kinase (CK), myofibrillar inflammation, and delayed onset muscle soreness (DOMS). Nonsteroidal antiinflammatory drugs (NSAID) may attenuate DOMS and indirect indices of inflammation in humans. METHODS We studied the effects of an NSAID (naproxen sodium (500 mg, 2 times a day for 48 h)) taken before and after resistance exercise in eight healthy, moderately trained men in a randomized, double-blind trial. The exercise consisted of unilateral knee concentric/eccentric weight lifting with 6 sets x 10 repetitions at 80-85% of the 1 repetition maximal contraction. Muscle biopsies of each vastus lateralis (EX = exercised/REST = control) were taken 24 h after exercise for immunohistochemical staining of inflammatory cells (leukocyte common antigen). At 24 and 48 h postexercise, we also determined DOMS, plasma CK activity, and knee extensor muscle torque. RESULTS Exercise resulted in an increased CK activity at +24 and +48 h (vs preexercise: P < 0.01), with no treatment effect. There were no treatment effects for any of the measured variables except for a return of voluntary knee extension torque to baseline by +48 h postexercise for NSAID treatment (P < 0.05). CONCLUSIONS NSAID administration did not alter CK rise, muscle force deficit at 24 h postexercise, nor perceived muscle pain. In addition, the increased CK at 24 h postexercise was not associated with an acute myofibrillar inflammatory cell infiltrate in moderately trained men after resistance exercise.

A Novel Approach to Tumor Suppression with Microencapsulated Recombinant Cells

A novel approach to cancer gene therapy is to implant microcapsules containing nonautologous cells engineered to secrete molecules with antineoplastic properties. The efficacy of this treatment is now tested in a mouse model bearing HER-2/neu-positive tumors. Nonautologous mouse myoblasts (C(2)C(12)) were genetically modified to secrete interleukin-2 linked to the Fv region of a humanized antibody with affinity to HER-2/neu. The resulting fusion protein, sFvIL-2, would encompass immune-stimulatory cytokine activity now targeted to the HER-2/neu-expressing tumor. These recombinant cells were then immunoprotected with alginate-poly-L-lysine-alginate microcapsules before implantation into tumor-bearing mice. Treatment with these encapsulated cells led to a delay in tumor progression and prolonged survival of the animals. The long-term efficacy was limited by an inflammatory reaction against the implanted microcapsules probably because of the secreted cytokine and antigenic response against the xenogeneic fusion protein itself. However, over the short term (initial 2 weeks), efficacy was confirmed when a significant amount of biologically active interleukin-2 was detected systemically, and targeting of the fusion protein to the HER-2/neu-expressing tumor was shown immunohistochemically. The tumor suppression in the treated animals was associated with increased apoptosis and necrosis in the tumor tissue, thus demonstrating successful targeting of the antiproliferative effect to the tumors by this delivery paradigm. In conclusion, this new approach to systemic cancer gene therapy needs to be modified to provide long-term delivery, but has demonstrated short-term efficacy and potential to become a cost-effective, benign, and non-viral-based adjunct to the current armory of anticancer strategies.

Oxidative stress and antioxidant enzyme upregulation in SOD1‐G93A mouse skeletal muscle

Amyotrophic lateral sclerosis (ALS) is caused by motor neuron loss in the spinal cord, but the mechanisms responsible are not known. Ubiquitous transgenic overexpression of copper/zinc superoxide dismutase (SOD1) mutations causing familial ALS (SOD1mut) leads to an ALS phenotype in mice; however, restricted expression of SOD1mut in neurons alone is not sufficient to cause this phenotype, suggesting that non‐neuronal SOD1mut expression is also required for disease manifestation. Recently, several investigators have suggested that SOD1mut‐mediated oxidative stress in skeletal muscle may contribute to ALS pathogenesis. The purpose of this study was to examine oxidative stress and antioxidant enzyme adaptation in 95‐day‐old SOD1‐G93A skeletal muscle. We observed significant elevations in both malondialdehyde (22% and 31% in red and white gastrocnemius, respectively) and protein carbonyls (53% in red gastrocnemius) in SOD1‐G93A mice. Copper/zinc SOD activity was higher in red and white SOD1‐G93A gastrocnemius (7‐ and 10‐fold, respectively), as was manganese SOD (4‐ and 5‐fold, respectively) and catalase (2‐ and 2.5‐fold, respectively). Taken together, our data demonstrate oxidative stress and compensatory antioxidant enzyme upregulation in SOD1‐G93A skeletal muscle. Muscle Nerve, 2006

Ultrastructural injury to interstitial cells of Cajal and communication with mast cells in Crohn's disease

Abstract  Crohns disease associated dysmotility has been attributed to fibrosis and damage to enteric nerves but injury to interstitial cells of Cajal (ICC) could also be involved. We assessed ICC in specimens obtained from patients with Crohns disease and determined the relation between ICC and the inflammatory infiltrate, particularly mast cells (MC) using quantitative immunohistochemistry and electron microscopy. Ultrastructural injury to ICC was patchy in all ICC subtypes but ICC‐Auerbachs plexus (AP) showed damage more frequently, i.e. swelling of mitochondria, decreased electron density, autophagosomes and partial depletion of the cytoplasm. Light microscopy confirmed a significant decrease in c‐kit immunoreactivity for ICC‐AP and an increased number of MC in the muscularis externa. Electron microscopy showed MC exhibiting piecemeal degranulation and making frequent and selective membrane‐to‐membrane contact with all types of injured ICC which suggests chronic release of granule content to affect ICC. Extent of ICC injury was not associated with duration of the disease. In conclusion, ultrastructural injury and loss of ICC‐AP is evident in Crohns disease. Epidemiological and morphological data suggest that ICC have the capacity to regenerate in spite of the chronic insult. The muscularis hosts a marked number of MC that exhibit piecemeal degranulation associated with ICC and may facilitate ICC maintenance.

Novel SCO2 mutation (G1521A) presenting as a spinal muscular atrophy type I phenotype

Rare cases of suspected spinal muscular atrophy (SMA) have been found to have cytochrome c oxidase (COX) deficiency. To date, four cases with SMA features have been reported in children with mutations in the synthesis of cytochrome oxidase 2 (SCO2) gene. We report a male neonate who was born hypotonic, with persistent lactic acidosis, spontaneous activity with EMG testing, development of respiratory distress in the first few hours of life, and died at 30 days of age with progressive cardiomyopathy. Testing for survival motor neurone (smn) and NAIP deletions were negative and a skeletal muscle biopsy showed neurogenic features with severe reductions of COX enzymatic and histochemical staining intensity. Post‐mortem muscle, heart, and liver biopsies showed severe, moderate, and mild reductions in COX activity, respectively, with parallel findings in the protein content for the mitochondrial DNA (COII) and nuclear DNA (COIV) encoded subunits. DNA sequencing of exon 2 of the SCO2 gene revealed compound heterozygosity with mutations at G1541A (common mutation, E140K) and also at a novel site in the copper binding region (G1521A in the current case (converting a highly conserved cysteine to serine (C133S)); mother heterozygous for G1521A; and father heterozygous for G1541A). This case provides strong support that SCO2 mutations can result in neonatal hypotonia with an SMA 1 phenotype. SCO2 mutations should be screened in suspected SMA cases with normal smn mutation analysis and any one of; cardiomyopathy, lactic acidosis, or COX deficiency in muscle.

Diffusion tensor MRI to assess skeletal muscle disruption following eccentric exercise

Introduction: Structural evidence of exercise‐induced muscle disruption has traditionally involved histological analysis of muscle tissue obtained by needle biopsy, however, there are multiple limitations with this technique. Recently, diffusion tensor magnetic resonance imaging (DT‐MRI) has been successfully demonstrated to noninvasively assess skeletal muscle abnormalities induced by traumatic injury. Methods: To determine the potential for DT‐MRI to detect musculoskeletal changes after a bout of eccentric exercise, 10 healthy men performed 300 eccentric actions on an isokinetic dynamometer. DT‐MRI measurements and muscle biopsies from the vastus lateralis were obtained before and 24 h post‐exercise. Results: Z‐band streaming was higher 24 h post‐exercise compared with baseline (P < 0.05). The histological indices of damage coincided with changes in DT‐MRI parameters of fractional anisotropy (FA) and apparent diffusion coefficient; reflecting altered skeletal muscle geometry (P < 0.05). Z‐band streaming quantified per fiber correlated with FA (r = −0.512; P < 0.05). Conclusions: DT‐MRI can detect changes in human skeletal muscle structure following eccentric exercise. Muscle Nerve 46: 42–50, 2012