Myxovirus resistance protein A (MxA) expression in myositides: Sarcoplasmic expression is common in both dermatomyositis and lupus myositis.

INTRODUCTION/AIMS: Myxovirus resistance protein A (MxA) is a type I interferon (IFN1) pathway activation marker and MxA sarcoplasmic expression is currently recognized as a highly specific marker for dermatomyositis (DM). However, we have frequently observed endothelial tubuloreticular inclusions (TRI), another surrogate IFN1 activation marker, in a variety of overlap myositides. The aim of this study was to examine MxA expression in those myositides. METHODS: We retrospectively performed MxA immunostaining on a wide range of myositides. RESULTS: MxA sarcoplasmic expression was present in DM (94.4%, 17/18), active lupus myositis (LM, 80%,16/20), inactive LM (36%, 4/11), antisynthetase syndrome (ASyS, 20%, 2/10), systemic sclerosis (13%, 2/15), Sjogren's syndrome (7.7%, 1/13), and human immunodeficiency virus (HIV) myositis (5.6%, 1/18) and was absent in immune-mediated necrotizing myopathy (IMNM, 0/16) and hydroxychloroquine myopathy (0/5). The sensitivity and specificity of MxA sarcoplasmic expression for LM and DM combined compared with all other myositides were 84.6% (95% CI: 69.5-94.1) and 92.1 (95% CI: 83.6-97.0), respectively, and superior to TRIs. MxA capillary expression was nonspecific. Histologically, 35% of LM cases demonstrated a unique panfascicular necrotizing myopathy pattern. The remainder of the LM cases had significant morphological overlap with DM/ASyS (20%), IMNM (20%), or polymyositis (15%). DISCUSSION: MxA sarcoplasmic expression is highly prevalent in LM and DM and is a useful marker in differentiating DM and LM from other myositides. LM can manifest in various pathology patterns that need to be differentiated from DM, IMNM, ASyS, and polymyositis.

Ectopic PLAG1 induces muscular dystrophy in the mouse.

Even though various genetic mutations have been identified in muscular dystrophies (MD), there is still a need to understand the biology of MD in the absence of known mutations. Here we reported a new mouse model of MD driven by ectopic expression of PLAG1. This gene encodes a developmentally regulated transcription factor known to be expressed in developing skeletal muscle, and implicated as an oncogene in certain cancers including rhabdomyosarcoma (RMS), an aggressive soft tissue sarcoma composed of myoblast-like cells. By breeding loxP-STOP-loxP-PLAG1 (LSL-PLAG1) mice into the MCK-Cre line, we achieved ectopic PLAG1 expression in cardiac and skeletal muscle. The Cre/PLAG1 mice died before 6 weeks of age with evidence of cardiomyopathy significantly limiting left ventricle fractional shortening. Histology of skeletal muscle revealed dystrophic features, including myofiber necrosis, fiber size variation, frequent centralized nuclei, fatty infiltration, and fibrosis, all of which mimic human MD pathology. QRT-PCR and Western blot revealed modestly decreased Dmd mRNA and dystrophin protein in the dystrophic muscle, and immunofluorescence staining showed decreased dystrophin along the cell membrane. Repression of Dmd by ectopic PLAG1 was confirmed in dystrophic skeletal muscle and various cell culture models. In vitro studies showed that excess IGF2 expression, a transcriptional target of PLAG1, phenocopied PLAG1-mediated down-regulation of dystrophin. In summary, we developed a new mouse model of a lethal MD due to ectopic expression of PLAG1 in heart and skeletal muscle. Our data support the potential contribution of excess IGF2 in this model. Further studying these mice may provide new insights into the pathogenesis of MD and perhaps lead to new treatment strategies.

The broad antibacterial activity of a small synthetic receptor for cellular phosphatidylglycerol lipids.

A small receptor molecule composed of a porphyrin core with tetrakis-ammonium glycine pickets (liptin 3e) appears to target anionic phosphatidylglycerol (PG) lipid head groups through multifunctional binding-pocket complementarity. Although a major component of bacterial cell membranes, PG is not widely found in animal cells, making PG potentially selective for bacterial targeting. Growth of microbial isolates was monitored in liquid cultures treated with liptin 3e by dilution plate counts and turbidity. Inhibition of growth by liptin 3e was observed for the ESKAPE human pathogens (Enterobacter aerogenes, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterococcus faecium), Escherichia coli, Mycobacterium smegmatis, Streptococcus sobrinus, and methicillin-resistant S. aureus (MRSA), with certain species suppressed at <1 µg/mL (sub-µM) concentrations. Prolonged lag phases were observed, although cell viability was mainly unaffected, suggesting that liptin treatment caused bacteriostasis. Cultures treated with liptin 3e eventually recovered, resumed growth, and reached the same final densities as untreated cultures. Growth of the fungus Candida albicans was not appreciably inhibited by liptin 3e. If liptins exhibit bacteriostasis through broad extracellular binding to PG head groups, thereby disrupting cellular processes, liptins may be considered for development into preclinical drug candidates or be useful as a targeting system for molecular beacons or antibacterial drugs.

Molecular markers of brain cholesterol homeostasis are unchanged despite a smaller brain mass in a mouse model of cholesteryl ester storage disease.

Lysosomal acid lipase (LAL), encoded by the gene LIPA, facilitates the intracellular processing of lipids by hydrolyzing cholesteryl esters and triacylglycerols present in newly internalized lipoproteins. Loss-of-function mutations in LIPA result in cholesteryl ester storage disease (CESD) or Wolman disease when mutations cause complete loss of LAL activity. Although the phenotype of a mouse CESD model has been extensively characterized, there has not been a focus on the brain at different stages of disease progression. In the current studies, whole-brain mass and the concentrations of cholesterol in both the esterified (EC) and unesterified (UC) fractions were measured in Lal-/- and matching Lal+/+ mice (FVB-N strain) at ages ranging from 14 up to 280 days after birth. Compared to Lal+/+ controls at 50, 68-76, 140-142, and 230-280 days of age, Lal-/- mice had brain weights that averaged approximately 6%, 7%, 18%, and 20% less, respectively. Brain EC levels were higher in the Lal-/- mice at every age, being elevated 27-fold at 230-280 days. Brain UC concentrations did not show a genotypic difference at any age. The elevated brain EC levels in the Lal-/- mice did not reflect EC in residual blood. An mRNA expression analysis for an array of genes involved in the synthesis, catabolism, storage, and transport of cholesterol in the brains of 141-day old mice did not detect any genotypic differences although the relative mRNA levels for several markers of inflammation were moderately elevated in the Lal-/- mice. The possible sites of EC accretion in the central nervous system are discussed.

A CADM3 variant causes Charcot-Marie-Tooth disease with marked upper limb involvement.

The CADM family of proteins consists of four neuronal specific adhesion molecules (CADM1, CADM2, CADM3 and CADM4) that mediate the direct contact and interaction between axons and glia. In the peripheral nerve, axon-Schwann cell interaction is essential for the structural organization of myelinated fibres and is primarily mediated by the binding of CADM3, expressed in axons, to CADM4, expressed by myelinating Schwann cells. We have identified-by whole exome sequencing-three unrelated families, including one de novo patient, with axonal Charcot-Marie-Tooth disease (CMT2) sharing the same private variant in CADM3, Tyr172Cys. This variant is absent in 230 000 control chromosomes from gnomAD and predicted to be pathogenic. Most CADM3 patients share a similar phenotype consisting of autosomal dominant CMT2 with marked upper limb involvement. High resolution mass spectrometry analysis detected a newly created disulphide bond in the mutant CADM3 potentially modifying the native protein conformation. Our data support a retention of the mutant protein in the endoplasmic reticulum and reduced cell surface expression in vitro. Stochastic optical reconstruction microscopy imaging revealed decreased co-localization of the mutant with CADM4 at intercellular contact sites. Mice carrying the corresponding human mutation (Cadm3Y170C) showed reduced expression of the mutant protein in axons. Cadm3Y170C mice showed normal nerve conduction and myelin morphology, but exhibited abnormal axonal organization, including abnormal distribution of Kv1.2 channels and Caspr along myelinated axons. Our findings indicate the involvement of abnormal axon-glia interaction as a disease-causing mechanism in CMT patients with CADM3 mutations.

Distinct tissue injury patterns in juvenile dermatomyositis auto-antibody subgroups.

INTRODUCTION: Juvenile dermatomyositis (JDM) can be classified into clinical serological subgroups by distinct myositis-specific antibodies (MSAs). It is incompletely understood whether different MSAs are associated with distinct pathological characteristics, clinical disease activities, or response to treatment. METHODS: We retrospectively reviewed clinicopathological data from consecutive JDM patients followed in the pediatric rheumatology clinic at a single center between October 2016 and November 2018. Demographics, clinical data, and laboratory data were collected and analyzed. Detailed muscle biopsy evaluation of four domains (inflammation, myofiber, vessels, and connective tissue) was performed, followed by statistical analysis. RESULTS: Of 43 subjects included in the study, 26 (60.5%) had a detectable MSA. The most common MSAs were anti-NXP-2 (13, 30.2%), anti-Mi-2 (7, 16.3%), and anti-MDA-5 (5, 11.6%). High titer anti-Mi-2 positively correlated with serum CK > 10,000 at initial visit (r = 0.96, p = 0.002). Muscle biopsied from subjects with high titer anti-Mi-2 had prominent perifascicular myofiber necrosis and perimysial connective tissue damage that resembled perifascicular necrotizing myopathy, but very little capillary C5b-9 deposition. Conversely, there was no positive correlation between the levels of the anti-NXP-2 titer and serum CK (r = - 0.21, p = 0.49). Muscle biopsies from patients with anti-NXP-2 showed prominent capillary C5b-9 deposition; but limited myofiber necrosis. Only one patient had anti-TIF1γ autoantibody, whose muscle pathology was similar as those with anti-NXP2. All patients with anti-MDA-5 had normal CK and near normal muscle histology. CONCLUSIONS: Muscle biopsy from JDM patients had MSA specific tissue injury patterns. These findings may help improve muscle biopsy diagnosis accuracy and inform personalized treatment of JDM.

ASCL1 regulates neurodevelopmental transcription factors and cell cycle genes in brain tumors of glioma mouse models.

Glioblastomas (GBMs) are incurable brain tumors with a high degree of cellular heterogeneity and genetic mutations. Transcription factors that normally regulate neural progenitors and glial development are aberrantly coexpressed in GBM, conferring cancer stem-like properties to drive tumor progression and therapeutic resistance. However, the functional role of individual transcription factors in GBMs in vivo remains elusive. Here, we demonstrate that the basic-helix-loop-helix transcription factor ASCL1 regulates transcriptional targets that are central to GBM development, including neural stem cell and glial transcription factors, oncogenic signaling molecules, chromatin modifying genes, and cell cycle and mitotic genes. We also show that the loss of ASCL1 significantly reduces the proliferation of GBMs induced in the brain of a genetically relevant glioma mouse model, resulting in extended survival times. RNA-seq analysis of mouse GBM tumors reveal that the loss of ASCL1 is associated with downregulation of cell cycle genes, illustrating an important role for ASCL1 in controlling the proliferation of GBM.

Distinct Expression Patterns of Carbonic Anhydrase IX in Clear Cell, Microcystic, and Angiomatous Meningiomas.

Clear cell, microcytic, and angiomatous meningiomas are 3 vasculature-rich variants with overlapping morphological features but different prognostic and treatment implications. Distinction between them is not always straightforward. We compared the expression patterns of the hypoxia marker carbonic anhydrase IX (CA-IX) in meningiomas with predominant clear cell (n = 15), microcystic (n = 9), or angiomatous (n = 11) morphologies, as well as 117 cases of other World Health Organization recognized histological meningioma variants. Immunostaining for SMARCE1 protein, whose loss-of-function has been associated with clear cell meningiomas, was performed on all clear cell meningiomas, and selected variants of meningiomas as controls. All clear cell meningiomas showed absence of CA-IX expression and loss of nuclear SMARCE1 expression. All microcystic and angiomatous meningiomas showed diffuse CA-IX immunoreactivity and retained nuclear SMARCE1 expression. In other meningioma variants, CA-IX was expressed in a hypoxia-restricted pattern and was highly associated with atypical features such as necrosis, small cell change, and focal clear cell change. In conclusion, CA-IX may serve as a useful diagnostic marker in differentiating clear cell, microcystic, and angiomatous meningiomas.

Cell-of-origin susceptibility to glioblastoma formation declines with neural lineage restriction.

The contribution of lineage identity and differentiation state to malignant transformation is controversial. We have previously shown that adult neural stem and early progenitor cells give origin to glioblastoma. Here we systematically assessed the tumor-initiating potential of adult neural populations at various stages of lineage progression. Cell type-specific tamoxifen-inducible Cre recombinase transgenes were used to target glioblastoma-relevant tumor suppressors Nf1, Trp53 and Pten in late-stage neuronal progenitors, neuroblasts and differentiated neurons. Mutant mice showed cellular and molecular defects demonstrating the impact of tumor suppressor loss, with mutant neurons being the most resistant to early changes associated with tumor development. However, we observed no evidence of glioma formation. These studies show that increasing lineage restriction is accompanied by decreasing susceptibility to malignant transformation, indicating a glioblastoma cell-of-origin hierarchy in which stem cells sit at the apex and differentiated cell types are least susceptible to tumorigenesis.

BRAF mutation leading to central nervous system rosai-dorfman disease.

Rosai-Dorfman disease (RDD) is an uncommon histiocytic proliferative disorder that can present in nodal, extranodal, or, extremely rarely, in central nervous system (CNS)-restricted form. RDD is characterized histologically as a non-Langerhans cell histiocytosis composed of atypical CD68+ /S-100+ /CD1a- macrophages demonstrating prominent emperipolesis and effacement of the surrounding tissue. Previously thought to represent a reactive process, recent studies have raised the possibility that RDD and other histiocytic lesions, including Erdheim-Chester and Langerhans cell histiocytosis, are clonal processes linked to somatic mutations in the mitogen-activated protein (MAP) kinase pathway. Herein, we present a fatal case of RDD isolated to the CNS and used a next-generation targeted gene panel and Sanger sequencing to uncover a pathogenic deletion in the ß3-αC loop of the kinase domain in exon 12 of BRAF. This mutation, previously described in melanoma and Langerhans cell histiocytosis, represents the first BRAF mutation of this kind identified in RDD. These findings support the idea that RDD is a neoplastic condition and raise the possibility that inhibitors of the MAP kinase pathway may be effective in RDD. Ann Neurol 2018;83:147-152.

Remote acoustic sensing as a safety mechanism during exposure of metal implants to alternating magnetic fields.

Treatment of prosthetic joint infections often involves multiple surgeries and prolonged antibiotic administration, resulting in a significant burden to patients and the healthcare system. We are exploring a non-invasive method to eradicate biofilm on metal implants utilizing high-frequency alternating magnetic fields (AMF) which can achieve surface induction heating. Although proof-of-concept studies demonstrate the ability of AMF to eradicate biofilm in vitro, there is a legitimate safety concern related to the potential for thermal damage to surrounding tissues when considering heating implanted metal objects. The goal of this study was to explore the feasibility of detecting acoustic emissions associated with boiling at the interface between a metal implant and surrounding soft tissue as a wireless safety sensing mechanism. Acoustic emissions generated during in vitro and in vivo AMF exposures were captured with a hydrophone, and the relationship with surface temperature analyzed. The effect of AMF exposure power, surrounding media composition, implant location within the AMF transmitter, and implant geometry on acoustic detection during AMF therapy was also evaluated. Acoustic emissions were reliably identified in both tissue-mimicking phantom and mouse studies, and their onset coincided with the implant temperature reaching the boiling threshold. The viscosity of the surrounding medium did not impact the production of acoustic emissions; however, emissions were not present when the medium was oil due to the higher boiling point. Results of simulations and in vivo studies suggest that short-duration, high-power AMF exposures combined with acoustic sensing can be used to minimize the amount of thermal damage in surrounding tissues. These studies support the hypothesis that detection of boiling associated acoustic emissions at a metal/tissue interface could serve as a real-time, wireless safety indicator during AMF treatment of biofilm on metallic implants.

Diffuse microvascular C5b-9 deposition is a common feature in muscle and nerve biopsies from diabetic patients.

Terminal complement complex deposition in endomysial capillaries detected by a C5b-9 immunostain is considered a diagnostic feature for dermatomyositis. However, we found widespread microvascular C5b-9 reactivity in a substantial subset of muscle biopsies with denervation changes, and in nerve biopsies of peripheral neuropathies, particularly in patients with diabetes. It is unclear whether the presence of C5b-9 deposition signifies active immune-mediated vascular injury that requires immune suppression therapy. We retrospectively identified 63 nerve biopsies in patients with a documented history of diabetes, 26 of which had concomitant muscle biopsies, as well as 54 control nerve biopsies in patients without a documented diabetes history, 18 of which had concomitant muscle biopsies. C5b-9 immunostain was performed on all cases. 87% of the nerve biopsies and 92% of the muscle biopsies from diabetic patients showed microvascular C5b-9 reactivity, compared to 34% and 50% in non-diabetic patients. The differences were statistically significant (p < 0.0001 for nerve and p = 0.002 for muscle). The C5b-9 reactivity was generally proportional to the extent of microvascular sclerosis in diabetic patients, but unrelated to inflammation or vasculitis. C5b-9 deposition in micro-vasculature in both muscle and nerve is therefore a common feature in patients with diabetic neuropathies and may have diagnostic utility. Precaution needs to be taken before using muscle capillary C5b-9 reactivity as evidence of myositis.

Aggressive Behavior in Silent Subtype III Pituitary Adenomas May Depend on Suppression of Local Immune Response: A Whole Transcriptome Analysis.

Silent subtype III pituitary adenomas (SS-3) are clinically nonfunctional adenomas that are more aggressive in terms of invasion and risk of recurrence than their conventional null cell counterparts. We previously showed that these tumors can be distinguished by immunohistochemistry based on the identification of a markedly enlarged and fragmented Golgi apparatus. To understand the molecular correlates of differential aggressiveness, we performed whole transcriptome sequencing (RNAseq) on 4 SS-3 and 4 conventional null cell adenomas. The genes that were highly upregulated in all the SS-3 adenomas included 2 secreted proteins involved in the suppression of T-lymphocyte activity, i.e., ARG2 (multiple testing adjusted padj = 1.5 × 10-3) and SEMA3A (padj = 3.3 × 10-3). Highly downregulated genes in all the SS-3 adenomas included HLA-B (padj = 3.3 × 10-6), suggesting reduced antigen presentation by the adenoma to cytotoxic T-cells. Quantitative RT-PCR of these genes performed on the adenoma samples supported the RNAseq results. We also found a relative decrease in the overall concentration of T-lymphocytes in the SS-3 tumors. These results suggest that SS-3 adenomas actively suppress the immune system and raise the possibility that they may be treatable with immune checkpoint inhibitors or nonspecific cancer immunotherapies.

Employing high-frequency alternating magnetic fields for the non-invasive treatment of prosthetic joint infections.

Treatment of prosthetic joint infection (PJI) usually requires surgical replacement of the infected joint and weeks of antibiotic therapy, due to the formation of biofilm. We introduce a non-invasive method for thermal destruction of biofilm on metallic implants using high-frequency (>100 kHz) alternating magnetic fields (AMF). In vitro investigations demonstrate a >5-log reduction in bacterial counts after 5 minutes of AMF exposure. Confocal and scanning electron microscopy confirm removal of biofilm matrix components within 1 minute of AMF exposure, and combination studies of antibiotics and AMF demonstrate a 5-log increase in the sensitivity of Pseudomonas aeruginosa to ciprofloxacin. Finite element analysis (FEA) simulations demonstrate that intermittent AMF exposures can achieve uniform surface heating of a prosthetic knee joint. In vivo studies confirm thermal damage is confined to a localized region (<2 mm) around the implant, and safety can be achieved using acoustic monitoring for the presence of surface boiling. These initial studies support the hypothesis that AMF exposures can eradicate biofilm on metal implants, and may enhance the effectiveness of conventional antibiotics.

Morin Stain Detects Aluminum-Containing Macrophages in Macrophagic Myofasciitis and Vaccination Granuloma With High Sensitivity and Specificity.

Macrophagic myofasciitis (MMF) is an inflammatory condition associated with the intramuscular (i.m.) injection of aluminum adjuvant-containing vaccines. It is clinically characterized by myalgia, weakness, and chronic fatigue and histologically by aggregates of cohesive macrophages with abundant basophilic, periodic acid-Schiff (PAS)-positive, diastase-resistant granules that percolate through the peri- and endomysium without eliciting substantial myofiber damage. The definitive diagnosis of MMF requires demonstration of aluminum within these macrophages. We evaluated the Morin stain, a simple, 2-step histochemical stain for aluminum, as a confirmatory diagnostic tool for MMF. Among 2270 muscle biopsies processed at UTSW between 2010 and 2015, a total of 12 MMF cases and 1 subcutaneous vaccination granuloma case were identified (11 pediatric, 2 adults). With the Morin stain, all 13 cases showed strong granular reactivity within the cytoplasm of macrophages but not in myofibers or connective tissue. Three cases of inflammatory myopathy with abundant macrophages (IMAM), 8 cases of granulomatous inflammation and 23 other deltoid muscle biopsies used as controls were all negative. Morin stain could be used in both formalin-fixed paraffin-embedded and cryostat sections. Thus, Morin stain detects aluminum with high sensitivity and specificity in human muscle and soft tissue and may improve the diagnostic yield of MMF and vaccination granuloma.

Assessment of acute thermal damage volumes in muscle using magnetization-prepared 3D T2 -weighted imaging following MRI-guided high-intensity focused ultrasound therapy.

PURPOSE: To evaluate magnetization-prepared 3D T2 -weighted magnetic resonance imaging (MRI) measurements of acute tissue changes produced during ablative MR high-intensity focused ultrasound (MR-HIFU) exposures. MATERIALS AND METHODS: A clinical MR-HIFU system (3T) was used to generate thermal lesions (n = 24) in the skeletal muscles of three pigs. T1 -weighted, 2D T2 -weighted, and magnetization-prepared 3D T2 -weighted sequences were acquired before and after therapy to evaluate tissue changes following ablation. Tissues were harvested shortly after imaging, fixed in formalin, and gross-sectioned. Select lesions were processed into whole-mount sections. Lesion dimensions for each imaging sequence (length, width) and for gross sections (diameter of lesion core and rim) were assessed by three physicists. Contrast-to-background ratio between lesions and surrounding muscle was compared. RESULTS: Lesion dimensions on T1 and 2D T2 -weighted imaging sequences were well correlated (R2 ∼0.7). The contrast-to-background ratio between lesion and surrounding muscle was 7.4 ± 2.4 for the magnetization-prepared sequence versus 1.7 ± 0.5 for a conventional 2D T2 -weighted acquisition, and 7.0 ± 2.9 for a contrast-enhanced T1 -weighted sequence. Compared with diameter measured on gross pathology, all imaging sequences overestimated the lesion core by 22-33%, and underestimated the lesion rim by 6-13%. CONCLUSION: After MR-HIFU exposures, measurements of the acute thermal damage patterns in muscle using a magnetization-prepared 3D T2 -weighted imaging sequence correlate with 2D T2 -weighted and contrast-enhanced T1 -weighted imaging, and all agree well with histology. The magnetization-prepared sequence offers positive tissue contrast and does not require IV contrast agents, and may provide a noninvasive imaging evaluation of the region of acute thermal injury at multiple times during HIFU procedures. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:354-364.

High-dose methotrexate with leucovorin rescue: For monumentally severe CNS inflammatory syndromes.

BACKGROUND: At sufficiently high doses, methotrexate (HDMTX) achieves substantial CNS penetration, whereas other tissues can be rescued from the effects of HDMTX by leucovorin rescue (LR), which does not penetrate the blood-brain barrier. OBJECTIVES: To report on the efficacy and safety of HDMTX with LR (HDMTX-LR), in the treatment of acute demyelinating inflammatory CNS syndromes refractory to conventional immunotherapy. METHODS: We performed a retrospective chart review of 12 patients treated (6 multiple sclerosis [MS], 4 neuromyelitis optica [NMO], and 2 Sjogren's syndrome myelopathy [SSM]) with HDMTX-LR after failing to improve, or exhibiting worsening following conventional immunotherapy. 11 patients were followed for a total of 6months following HDMTX-LR (one was lost to follow up after 1month); and clinical findings were documented at 1month, 3months, and 6months following HDMTX-LR therapy. RESULTS: Ten patients demonstrated both clinical and radiologic evidence of near, if not complete, abolishment of disease activity, in conjunction with impressive reconstitution of neurologic function in the 6-month period following HDMTX-LR. Mean Kurtzke Expanded Disability Status Scale (EDSS) prior to HDMTX-LR was 8.1 (±1.4). Following HDMTX-LR, mean EDSS was 6.6 (±2.4) at 1month, 5.8 (±2.3) at 3months, and 5.7 (±2.3) at 6months. CONCLUSIONS: In this retrospective assessment of treatment-recalcitrant fulminant inflammatory CNS syndromes, HDMTX-LR was observed to be a safe and highly effective treatment, producing the rapid and near complete cessation of disease activity, in conjunction with an important corresponding and 'durable remission' in the majority of our small treatment cohort.