Thrombospondin-1 mediates muscle damage in brachio-cervical inflammatory myopathy and systemic sclerosis.

OBJECTIVE: To describe the clinical, serologic and histologic features of a cohort of patients with brachio-cervical inflammatory myopathy (BCIM) associated with systemic sclerosis (SSc) and unravel disease-specific pathophysiologic mechanisms occurring in these patients. METHODS: We reviewed clinical, immunologic, muscle MRI, nailfold videocapillaroscopy, muscle biopsy, and response to treatment data from 8 patients with BCIM-SSc. We compared cytokine profiles between patients with BCIM-SSc and SSc without muscle involvement and controls. We analyzed the effect of the deregulated cytokines in vitro (fibroblasts, endothelial cells, and muscle cells) and in vivo. RESULTS: All patients with BCIM-SSc presented with muscle weakness involving cervical and proximal muscles of the upper limbs plus Raynaud syndrome, telangiectasia and/or sclerodactilia, hypotonia of the esophagus, and interstitial lung disease. Immunosuppressive treatment stopped the progression of the disease. Muscle biopsy showed pathologic changes including the presence of necrotic fibers, fibrosis, and reduced capillary number and size. Cytokines involved in inflammation, angiogenesis, and fibrosis were deregulated. Thrombospondin-1 (TSP-1), which participates in all these 3 processes, was upregulated in patients with BCIM-SSc. In vitro, TSP-1 and serum of patients with BCIM-SSc promoted proliferation and upregulation of collagen, fibronectin, and transforming growth factor beta in fibroblasts. TSP-1 disrupted vascular network, decreased muscle differentiation, and promoted hypotrophic myotubes. In vivo, TSP-1 increased fibrotic tissue and profibrotic macrophage infiltration in the muscle. CONCLUSIONS: Patients with SSc may present with a clinically and pathologically distinct myopathy. A prompt and correct diagnosis has important implications for treatment. Finally, TSP-1 may participate in the pathologic changes observed in muscle.

Calbindin D-28k-immunoreactivity in rat muscle spindle; a light and electron microscopic study.

The localization of the vitamin D-dependent calcium-binding protein, calbindin D-28k (CaBP), was studied immunocytochemically in rat striated muscle. CaBP-like immunoreactivity was found in some of the intrafusal fibres in muscle spindles. The spindle capsule and the perineurial sheath of the nerve bundles were occasionally immunoreactive to CaBP. In electron microscope the labelling for CaBP was found diffusely in sarcoplasm, in Z-bands and inside the terminal cisternae of intrafusal muscle fibres. The present findings suggest that CaBP may have a role in maintaining the appropriate microenvironment in the intracapsular space of muscle spindle and that CaBP may be involved in the function of intrafusal muscle fibres.

Motor nerve terminal destruction and regeneration following anti-ganglioside antibody and complement-mediated injury: an in and ex vivo imaging study in the mouse.

Both the neural and glial components of the neuromuscular junction (NMJ) have been identified as potential sites for anti-ganglioside antibody (Ab) binding and complement-mediated injury in murine models for the human peripheral nerve disorder Guillain-Barré syndrome (GBS). Some patients suffering from the acute motor axonal neuropathy (AMAN) forms of GBS recover very rapidly from paralysis; it has been proposed that in these cases the injury was restricted to the distal motor axons and nerve terminals (NTs) which are able to regenerate over a very short time-frame. To test this hypothesis, the ventral neck muscles of mice (n=45) expressing cytosolic fluorescent proteins in their axons (CFP) and Schwann cells (GFP) were subjected to a single topical application of anti-ganglioside Ab followed by a source of complement. Group A (n=15) received Ab that selectively bound to the NTs, group B (n=15) received Abs that bound both to the NTs and the perisynaptic Schwann cells (pSCs) and group C (control animals; n=15) only received complement. Evolution of the injury was documented by in vivo imaging, and following euthanasia the muscles were reimaged ex vivo both quantitatively and qualitatively, either immediately, or after 1, 2, 3 or 5 days of regeneration (each n=3 per group). Within 15 minutes of complement application, a rapid loss of CFP overlying the NMJ could be seen; in group A, the GFP signal remained unchanged, whereas in group B the GFP signal was also lost. In group C no changes to either CFP or GFP were observed. At 24 h, 6% of the superficial NMJs in group A and 12% of the NMJs in group B exhibited CFP. In both groups, CFP returned within the next five days (group A: 93.5%, group B: 94%; p=0.739), with the recovery of CFP being preceded by a return of GFP-positive cells overlying the NMJ in group B. Auxiliary investigations revealed that the loss of CFP at the NMJ correlated with a loss of NT neurofilament immuno-reactivity and a return of CFP at the NMJ was accompanied by a return of neurofilament. In ultrastructural investigations, injured NTs were electron lucent and exhibited damaged mitochondria, a loss of filaments and a loss of synaptic vesicles. The examination of muscles after five days of regeneration revealed physiological NT-profiles. The results described above indicate that following a single anti-ganglioside Ab-mediated and complement-mediated attack, independent of whether there are healthy and mature perisynaptic Schwann cells overlying the NMJ, the murine NT is capable of recovering both its architectural and axolemmal integrity very rapidly. This data supports the notion that an equivalent mechanism may account for the rapid recovery seen in some clinical cases of AMAN.

Isolated neck extensor myopathy: is it responsive to immunotherapy?

OBJECTIVE: To determine if isolated neck extensor myopathy (INEM) is responsive to immunosuppressive treatment. METHODS: We retrospectively reviewed charts of patients with INEM from 2002 to 2008 to identify patients and determine the response to immunomodulatory therapy. Clinical, electrodiagnostic, histologic, and radiographic data were reviewed. RESULTS: Four patients were identified during the study period. Three were women. The age of onset of neck extensor weakness ranged from 58 to 78 years. Serum creatine kinase levels were within normal limits in all patients. None had clinical, laboratory, or electrophysiological findings to suggest a generalized neuromuscular disorder. On electrodiagnostic studies, all patients had myopathic changes with or without irritative features in cervical paraspinal muscles. No inflammation was present on muscle biopsy from three of the patients. All patients received one or more immunosuppressive agents. Neck strength improved by 1 point or greater on the Medical Research Council scale in all subjects with a peak response observed between 3 and 6 months after treatment initiation. CONCLUSIONS: A trial of immunosuppressive agents should be offered to patients with INEM because a subset will improve. Rigorously defined, INEM is a noninflammatory myopathy. However, a focal myositis could be missed on muscle biopsy and may explain the favorable response to treatment.

Immune-mediated myositis in Crohn's disease.

We report a patient with uncontrolled Crohn's disease who presented with progressive weakness of proximal muscles and a marked elevation of serum creatine kinase. Muscle biopsy from the left deltoid exhibited myositic changes with inflammatory infiltrates in the perimysium, endomysium, and perivascular locations. Most were stained as CD68-positive macrophages, whereas some were CD4- and CD8-positive T lymphocytes. Due to uncontrolled bowel inflammation, several fistulae were found in the descending colon, and partial colectomy was performed. An examination of the resected colon exhibited inflammation of the bowel structure surrounded mainly by CD68-positive macrophages. The histopathological findings of the descending colon were analogous to those of the muscle. After an increased dose of mesalazine and partial colectomy, her muscle symptoms improved. These findings suggest that the myositis in Crohn's disease is immune-mediated and that treatment of bowel inflammation should be emphasized as opposed to steroid or other immunosuppressive therapy.

Response of the dropped head/bent spine syndrome to treatment with intravenous immunoglobulin.

Weakness of neck extension causing a dropped head may result from many neuromuscular disorders. One etiology is isolated neck extensor myopathy. A similar focal myopathy of the lower axial muscles may cause the bent spine syndrome, which manifests as flexion of the trunk and inability to stand upright. Combination of both dropped head and bent spine myopathies is uncommon. Inflammation is usually not pronounced in these conditions and response to immunosuppressive treatment is rare. We present an 81-year-old man who developed progressive weakness of neck and trunk extension over several months, with a prominent inflammatory process in the thoracic paraspinal muscles, which responded dramatically to treatment with intravenous immunoglobulin (IVIg). This case, together with other rare reports, suggests that the presence of inflammation in the biopsy of an affected muscle may predict treatment response.

Brainstem and cervical spinal cord Fos immunoreactivity evoked by nerve growth factor injection into neck muscles in mice.

Although myofascial tenderness is thought to play a key role in the pathophysiology of tension-type headache, very few studies have addressed neck muscle nociception. The neuronal activation pattern following local nerve growth factor (NGF) administration into semispinal neck muscles in anaesthetized mice was investigated using Fos protein immunohistochemistry. In order to differentiate between the effects of NGF administration on c-fos expression and the effects of surgical preparation, needle insertion and intramuscular injection, the experiments were conducted in three groups. In the sham group (n=7) cannula needles were only inserted without any injection. In the saline (n=7) and NGF groups (n=7) 0.9% physiological saline solution or 0.8 microm NGF solution were injected in both muscles, respectively. In comparison with sham and saline conditions, NGF administration induced significantly stronger Fos immunoreactivity in the mesencephalic periaqueductal grey (PAG), the medullary lateral reticular nucleus (LRN), and superficial layers I and II of cervical spinal dorsal horns C1, C2 and C3. This activation pattern corresponds very well to central nervous system processing of deep noxious input. A knowledge of the central anatomical representation of neck muscle pain is an essential prerequisite for the investigation of neck muscle nociception in order to develop a future model of tension-type headache.