Myxovirus Resistance Protein A Research Articles

Use of the FebriDx® host-response point-of-care test may reduce antibiotic use for respiratory tract infections in primary care: a mixed-methods feasibility study.

FebriDx® is a CE-marked, single-use point-of-care test with markers for bacterial [C-reactive protein (CRP)] and viral [myxovirus resistance protein A (MxA)] infection, using finger-prick blood samples. Results are available after 10-12 min. We explored the usability and potential impact of FebriDx® in reducing antibiotic prescriptions for lower respiratory tract infection (LRTI) in primary care, and the feasibility of conducting a randomized controlled trial (RCT). Patients (aged ≥1 year) with LRTI deemed likely to receive antibiotic prescription were recruited at nine general practices and underwent FebriDx® testing. Data collection included FebriDx® results, antibiotic prescribing plan (before and after testing) and re-consultation rates. Staff completed System Usability Scale questionnaires. From 31 January 2023 to 9 June 2023, 162 participants participated (median age 57 years), with a median symptom duration of 7 days (IQR 5-14). A valid FebriDx® result was obtained in 97% (157/162). Of 155 patients with available results, 103 (66%) had no detectable CRP or MxA, 28 (18%) had CRP only, 5 (3%) had MxA only, and 19 (12%) had both CRP and MxA. The clinicians' stated management plan was to prescribe antibiotics for 86% (134/155) before testing and 45% (69/155) after testing, meaning a 41% (95% CI: 31%, 51%) difference after testing, without evidence of increased re-consultation rates. Ease-of-use questionnaires showed 'good' user-friendliness. Use of FebriDx® to guide antibiotic prescribing for LRTI in primary care was associated with a substantial reduction in prescribing intentions. These results support a fully powered RCT to confirm its impact and safety.

Rational design of MIPs for the detection of Myxovirus resistance protein A (MxA), a biomarker for viral infection

Accurate diagnosis is crucial for effective patient care and the containment of antimicrobial resistance outbreaks. The intricate challenge of distinguishing bacterial from viral infections, coupled with limited diagnostic tools and overlapping symptoms has driven the utilization of molecular imprinting techniques. This study focuses on developing cost-effective, chemically stable antibody analogs for the interferon-induced protein myxovirus resistance protein A (MxA). MxA is an intracellular, cytoplasmic GTPase having activity against a wide range of viruses and serves as a distinctive biomarker for viral infections. We utilized computational design to guide the polymer assembly, centering on epitope imprinting to target MxA-specific regions crucial for interaction. Molecular docking calculations, alongside a pioneering multi-monomer simultaneous docking (MMSD) protocol, efficiently elucidate cooperativity during pre-polymerization. Monomer binding affinity scores, such as for APTMS, exhibited notable increase, ranging from −3.11 to −13.03 kcal/mol across various MMSD combinations compared to a maximum of −2.78 kcal/mol in single monomer docking, highlighting the capacity of MMSD in elucidating crucial monomer-monomer interactions. This computational approach provides a theoretical alternative to labor-intensive experimental optimization, streamlining the development process for synthetic receptors. Simulations reveal unique interactions enhancing MIP-peptide complementarity, yielding optimized receptors selectively binding to MxA epitopes. The obtained MIPs demonstrated a maximum adsorption capacity of approximately 12 mg/g and captured 1.6 times more epitope and 2.6 times more epitope containing MxA protein than corresponding NIPs. A proof-of-concept study demonstrates MxA protein binding to synthetic receptors, highlighting the potential of MIPs, analogous to antibodies, in overcoming current diagnostic challenges for precise detection of viral infection.

Exposure to PM2.5 modulate the pro-inflammatory and interferon responses against influenza virus infection in a human 3D bronchial epithelium model

Epidemiological studies showed a positive association between exposure to PM2.5 and the severity of influenza virus infection. However, the mechanisms by which PM2.5 can disrupt antiviral defence are still unclear. From this perspective, the objective of this study was to evaluate the effects of PM2.5 on antiviral signalling in the respiratory epithelium using the bronchial Calu-3 cell line grown at the air-liquid interface. Pre-exposure to PM2.5 before infection with the influenza virus was investigated, as well as a co-exposure. Although a physical interaction between the virus and the particles seems possible, no effect of PM2.5 on viral replication was observed during co-exposure, although a downregulation of IFN-β release was associated to PM2.5 exposure. However, pre-exposure slightly increased the viral nucleoprotein production and the pro-inflammatory response. Conversely, the level of the myxovirus resistance protein A (MxA), an interferon-stimulated gene (ISG) induced by IFN-β, was reduced. Therefore, these results suggest that pre-exposure to PM2.5 could alter the antiviral response of bronchial epithelial cells, increasing their susceptibility to viral infection.

Functional significance of DNA methylation: epigenetic insights into Sjögren's syndrome.

Sjögren's syndrome (SjS) is a systemic, highly diverse, and chronic autoimmune disease with a significant global prevalence. It is a complex condition that requires careful management and monitoring. Recent research indicates that epigenetic mechanisms contribute to the pathophysiology of SjS by modulating gene expression and genome stability. DNA methylation, a form of epigenetic modification, is the fundamental mechanism that modifies the expression of various genes by modifying the transcriptional availability of regulatory regions within the genome. In general, adding a methyl group to DNA is linked with the inhibition of genes because it changes the chromatin structure. DNA methylation changes the fate of multiple immune cells, such as it leads to the transition of naïve lymphocytes to effector lymphocytes. A lack of central epigenetic enzymes frequently results in abnormal immune activation. Alterations in epigenetic modifications within immune cells or salivary gland epithelial cells are frequently detected during the pathogenesis of SjS, representing a robust association with autoimmune responses. The analysis of genome methylation is a beneficial tool for establishing connections between epigenetic changes within different cell types and their association with SjS. In various studies related to SjS, most differentially methylated regions are in the human leukocyte antigen (HLA) locus. Notably, the demethylation of various sites in the genome is often observed in SjS patients. The most strongly linked differentially methylated regions in SjS patients are found within genes regulated by type I interferon. This demethylation process is partly related to B-cell infiltration and disease progression. In addition, DNA demethylation of the runt-related transcription factor (RUNX1) gene, lymphotoxin-α (LTA), and myxovirus resistance protein A (MxA) is associated with SjS. It may assist the early diagnosis of SjS by serving as a potential biomarker. Therefore, this review offers a detailed insight into the function of DNA methylation in SjS and helps researchers to identify potential biomarkers in diagnosis, prognosis, and therapeutic targets.

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

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. We retrospectively performed MxA immunostaining on a wide range of myositides. 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%). 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.

Contribution of Complement, Microangiopathy and Inflammation in Idiopathic Inflammatory Myopathies.

Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group characterized by muscle weakness and skin symptoms and are categorized into six subtypes: dermatomyositis (DM), polymyositis (PM), anti-synthetase syndrome (ASS), immune-mediated myopathy (IMNM), inclusion body myopathy (IBM), and overlap myositis. Myositis-specific autoantibodies were detected for the diagnosis and classification of IIM. This review highlights the pathogenic contributions of the complement system, microangiopathy, and inflammation in IIM. Deposition of complement around capillaries and/or the sarcolemma was observed in muscle biopsy specimens from patients with DM, ASS, and IMNM, suggesting the pathomechanism of complement-dependent muscle and endothelial cell injury. A recent study using human muscle microvascular endothelial cells showed that Jo-1 antibodies from ASS induce complement-dependent cellular cytotoxicity in vitro. Based on both clinical and pathological observations, antibody- and complement-mediated microangiopathy may contribute to the development of DM and anti-Jo-1 ASS. Juvenile DM is characterized by the loss of capillaries, perivascular inflammation, and small-vessel angiopathies, which may be related to microinfarction and perifascicular atrophy. Several serum biomarkers that reflect the IFN1 signature and microangiopathy are elevated in patients with DM. The pathological observation of myxovirus resistance protein A (MxA), which suggests a type 1 interferon (IFN1) signature in DM, supports the diagnosis and further understanding of the pathomechanism of IIM. A recent report showed that an increase in triggering receptor expressed on myeloid cells (TREM-1) around perimysial blood vessels and muscles in patients with IIM plays a role in triggering inflammation and promoting the migration of inflammatory cells by secreting proinflammatory cytokines, such as tumor necrosis factor α. The deposition of complement in muscles and capillaries is a characteristic feature of DM, ASS, and IMNM. Microangiopathy plays a pathogenic role in DM, possibly resulting in perifascicular atrophy. Further understanding of the detailed pathomechanism regarding complement, microangiopathy, and inflammation may lead to novel therapeutic approaches for IIM.

Performance of the FebriDx Rapid Point-of-Care Test for Differentiating Bacterial and Viral Respiratory Tract Infections in Patients with a Suspected Respiratory Tract Infection in the Emergency Department.

FebriDx is a rapid point-of-care test combining qualitative measurements of C-reactive protein (CRP) and Myxovirus Resistance Protein A (MxA) using a disposable test device to detect and differentiate acute bacterial from viral respiratory tract infections. The goal of this study was to investigate the diagnostic accuracy of FebriDx in patients with suspected respiratory tract infections in the emergency department (ED). This was an observational cohort study, performed in the ED of an academic hospital. Patients were included if they had a suspected infection. The primary outcome was the presence of a bacterial or viral infection, determined by clinical adjudication by an expert panel. The sensitivity, specificity, and positive and negative predictive value of FebriDx for the presence of bacterial versus non-bacterial infections, and viral versus non-viral infections were calculated. Between March 2019 and November 2020, 244 patients were included. A bacterial infection was present in 41%, viral infection was present in 24%, and 4% of the patients had both viral and bacterial pathogens. FebriDx demonstrated high sensitivity in the detection of bacterial infection (87%), high NPV (91%) to rule out bacterial infection, and high specificity (94%) for viral infection in patients with a suspected infection in the ED.

Developing a Tool for Differentiation Between Bacterial and Viral Respiratory Infections Using Myxovirus Resistance Protein A and C-Reactive Protein.

The aim was to assess the performance of a blood assay combining measurements of MxA (myxovirus resistance protein A) and CRP (C-reactive protein) to differentiate viral from bacterial respiratory infections. In a prospective study, MxA and CRP were measured in the blood by the AFIAS panel in adults admitted with respiratory infection. Patients were split into discovery and validation cohorts. Final diagnosis was adjudicated by a panel of experts. Microbiology-confirmed cases comprised the discovery cohort, and infections adjudicated as highly probable viral or bacterial comprised the validation cohort. A total of 537 patients were analyzed: 136 patients were adjudicated with definitive viral infections and 131 patients with definitive bacterial infections. Using logistic regression analysis, an equation was developed to calculate the probability for bacterial infection using the absolute value of MxA and CRP. Calculated probability≥0.5 and/or MxA to CRP ratio less than 2 applied as the diagnostic rule for bacterial infections. This rule provided 91.6% sensitivity and 90.4% negative predictive value for the diagnosis of bacterial infections. This diagnostic sensitivity was confirmed in the validation cohort. A MxA/CRP ratio less than 0.15 was associated with unfavorable outcome. The calculation of the probability for bacterial infection using MxA and CRP may efficiently discriminate between viral and bacterial respiratory infections.

Emergency Department point-of-care antiviral host response testing is accurate during periods of multiple respiratory virus co-circulation

FebriDx is a CE-marked, FDA-approved point-of-care test that detects the antiviral host response protein Myxovirus Resistance Protein A (MxA), in addition to C-reactive protein, using finger-prick blood. FebriDx MxA detection had a high negative predictive value for COVID-19 in symptomatic adults presenting to hospital in the first waves of the pandemic and was used subsequently as a 'rule out' triage tool in Emergency departments. The diagnostic accuracy of FebriDx MxA in the current context of co-circulation of influenza, SARS-CoV-2, and Respiratory Syncytial Virus (RSV), and in the era of COVID-19 vaccination, is unknown. We retrospectively evaluated the diagnostic performance of FebriDx MxA in adults with acute respiratory symptoms presenting to the Emergency Department (ED) of a large UK teaching hospital using Reverse Transcription Polymerase Chain Reaction (RT-PCR) as the reference standard (Cepheid Xpert Xpress SARS-CoV-2/Flu/RSV). Between March 9th 2022 and March 8th 2023, 5426 patients had both FebriDx and RT-PCR testing with valid results. 999 (18.4%) of patients had influenza detected, 520 (9.6%) SARS-CoV-2, and 190 (3.5%) RSV. Negative Predictive Value (NPV) of MxA detection by FebriDx was 97.5% (96.9-98.0) for influenza, 97.1% (96.4-97.7) for SARS-CoV-2, 98.1% (97.5-98.6) for RSV, and 92.8% (91.8-93.7) for all viruses combined. In symptomatic adults, FebriDx MxA had a high NPV for influenza and RSV, and retained a high NPV for SARS-CoV-2, in the context of virus co-circulation and widespread COVID-19 vaccination. FebriDx continues to be a useful 'rule out' triage tool in the ED and could potentially be scaled to provide a national triage solution for future viral pandemics.

Sarcoplasmic Myxovirus Resistance Protein A: A Study of Expression in Idiopathic Inflammatory Myopathy.

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of autoimmune diseases affecting primarily proximal muscles. Major subtypes include dermatomyositis, polymyositis, inclusion body myositis, immune-mediated necrotizing myopathy and antisynthetase syndrome. Overexpression of sarcoplasmic myxovirus-resistance protein A (MxA) has been observed in muscle biopsy specimens of dermatomyositis but is rarely seen in other subtypes of IIM and other myopathies. We evaluate the expression of sarcoplasmic MxA and its diagnostic value in IIM and other myopathies. One hundred and thirty-eight muscle biopsy specimens with the diagnosis of IIM and other myopathies from 2011 to 2020 were reviewed and stained for MxA by immunohistochemistry. The difference of the expression of MxA between IIM and other myopathies was analyzed by Fisher's exact test, and the sensitivity and specificity of MxA immunohistochemistry in the diagnosis of IIM were assessed. MxA protein was positive in 16/138 (11.6%) specimens. All 12 dermatomyositis specimens positive for MxA protein were positive in perifascicular area pattern. Only dermatomyositis specimens had a significantly higher percentage of positive sarcoplasmic MxA expression than specimens of other subtypes of IIM (p<0.001). Sarcoplasmic MxA expression for dermatomyositis diagnosis had a sensitivity of 46.15% (95% CI 26.59-66.63%) and a specificity of 94.44% (95% CI 81.34-99.32%) with the positive and negative likelihood ratio of 8.31 (95% CI 2.03-34.01) and 0.57 (95% CI 0.40-0.82), respectively. The MxA immunohistochemistry is highly specific for dermatomyositis and should be added to a routine inflammatory panel of muscle biopsy. MxA expression should be cautiously interpreted to avoid pitfalls.

Evidence for increased interferon type I activity in CD8+ T cells in giant cell arteritis patients.

Giant cell arteritis (GCA) is a vasculitis of the medium- and large-sized arteries. Interferon type I (IFN-I) is increasingly recognized as a key player in autoimmune diseases and might be involved in GCA pathogenesis, however evidence is limited. IFN-I activates Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathways, leading to increased expression of interferon stimulated genes. In this study, IFN-I activity in GCA is explored, focusing on CD8+ T cells. Expression of phospho-STAT (pSTAT) 1, 3 and 5 was investigated in IFN-α-stimulated peripheral mononuclear cells (PBMCs) gated separately for CD8+ T cells of patients with GCA (n=18), healthy controls (HC, n=15) and infection controls (n=11) by Phosphoflow method combined with fluorescent cell barcoding technique. Furthermore, IFN-I induced myxovirus-resistance protein A (MxA) and CD8+ T cell expression was investigated by immunohistochemistry in temporal artery biopsies (TAB) of GCA patients (n=20) and mimics (n=20), and in aorta tissue of GCA (n=8) and atherosclerosis patients (n=14). pSTAT1 expression was increased in IFN-α stimulated CD8+ T cells from GCA patients, whereas no difference was observed in pSTAT3 and pSTAT5 expression. MxA was present in TABs of 13/20 GCA patients compared to 2/20 mimics and in 8/8 GCA+ compared to 13/14 GCA- aorta tissues. MxA location partially co-localized with CD8+T cells. Our results provide evidence for increased IFN-I activity in CD8+ T cells of GCA patients, both systemically and locally. These findings warrant further investigation regarding IFN-I induced biomarkers and IFN-I related novel therapeutic options in GCA.

A type I interferon footprint in pre-operative biopsies is an independent biomarker that in combination with CD8+ T cell quantification can improve the prediction of response to neoadjuvant treatment of rectal adenocarcinoma

ABSTRACT Tailored treatment for patients with rectal cancer requires clinically available markers to predict their response to neoadjuvant treatment. The quantity of tumor-infiltrating lymphocytes (TILs) in pre-operative tumor biopsies has been suggested to predict a favorable response, but opposing results exist. A biopsy-adapted Immunoscore (ISB) based on TILs has recently emerged as a promising predictor of tumor regression and prognosis in (colo)rectal cancer. We aimed to refine the ISB for prediction of response using multiplex immunofluorescence (mIF) on pre-operative rectal cancer biopsies. We combined the distribution and density of conventional T cell subsets and γδT cells with a type I Interferon (IFN)-driven response assessed using Myxovirus resistance protein A (MxA) expression. We found that pathological complete response (pCR) following neoadjuvant treatment was associated with type I IFN. Stratification of patients according to the density of CD8+ in the entire tumor tissue and MxA+ cells in tumor stroma, where equal weight was assigned to both parameters, resulted in improved predictive quality compared to the ISB. This novel stratification approach using these two independent parameters in pre-operative biopsies could potentially aid in identifying patients with a good chance of achieving a pCR following neoadjuvant treatment.

MxA Protein Expression and Histological Characteristics on Muscle Biopsy in Myositis (P9-8.001)

<h3>Objective:</h3> To evaluate both myofiber and capillary MxA expression in a wide range of potentially type 1 interferon driven myositis. <h3>Background:</h3> The myxovirus resistance protein A (MxA) is one of the most highly induced protein by type I interferons. The current international neuromuscular workshop recognizes MxA reactivity on myofibers as a definitive marker for dermatomyositis, with 98–100% specificity on muscle biopsies. However, many type I interferon driven inflammatory myositis have not been tested in previous studies. <h3>Design/Methods:</h3> We evaluated both myofiber and capillary MxA expression in a wide range of potentially type 1 interferon driven myositis, including lupus myositis, HIV myositis, Sjogren’s disease associated myositis, systemic sclerosis associated myositis and antisynthetase syndrome associated myositis. Dermatomyositis and immune mediated necrotizing myopathy served as positive and negative control, respectively. We also cross compared the presence of endothelial tubuloreticular inclusions (TRI), another type 1 interferon activation marker, with MxA expressions. <h3>Results:</h3> Myofiber MxA expression was present in 78.9% (15/19) of active lupus myositis but was uncommon in active myositis associated with HIV (1/18), Sjogren’s disease (1/12), systemic sclerosis (2/14), and antisynthetase syndrome (2/11). Capillary MxA expression was much more prevalent and less specific, present in lupus (18/19), HIV (8/18), Sjogren’s disease (9/12), systemic sclerosis (11/14), and antisynthetase syndrome (9/11). There was a positive correlation between myofiber MxA expression and presence of endothelial tubuloreticular inclusions. Histologically, lupus myositis was characterized by a “pan-fascicular” necrotizing myopathy pattern. <h3>Conclusions:</h3> MxA myofiber expression is not a specific marker for dermatomyositis. Nevertheless, MxA is still a highly useful tool in muscle biopsy whose myofiber expression is strongly suggestive of either dermatomyositis or lupus myositis. The “pan-fascicular” necrotizing myopathy pattern in lupus myositis may serve as a useful histological feature to differentiate from the “perifascicular” injury pattern in dermatomyositis. <b>Disclosure:</b> Dr. Trivedi has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Argenx. The institution of Dr. Trivedi has received research support from NIH. Dr. Xing has nothing to disclose. Nicole Bitencourt has nothing to disclose. Chunyu Cai has nothing to disclose.

Cancer-associated Regional Ischemic Myopathy: A Rare Immune Myopathy (P9-8.008)

<h3>Objective:</h3> To describe clinical and pathological features of a rare immune myopathy featured by regional ischemia in the setting of cancer. <h3>Background:</h3> Regional ischemic immune myopathy (RIIM) is a rare disorder attributed to myovasculopathy and considered paraneoplastic. It has a high mortality rate. Contrary to dermatomyositis, where microvasculopathy leads to perifascicular pathology and sometimes muscle ischemia, RIIM is characterized by regional necrosis in border zones between perimysial vessels. <h3>Design/Methods:</h3> Review of patient’s clinical and laboratory findings. <h3>Results:</h3> An 81-year-old man manifested subacute proximal limb weakness, dysphagia, and 25-pound weight loss. He had stage IV prostate cancer, diagnosed 3 months prior to weakness-onset. Examination revealed mild facial weakness, flaccid dysarthria, moderate-to-severe neck and limb girdle weakness and atrophy. Videofluoroscopic swallow study showed severe oropharyngeal dysphagia with aspiration. CK was 689 U/L (normal 39–108 U/L) at presentation but 6,145 U/L six weeks earlier. Myositis-associated and HMGCR antibodies were negative. EMG showed proximal-predominant myopathic changes with fibrillation potentials. Muscle biopsy revealed several well-demarcated areas of ischemia involving adjacent fascicles. Necrotic fibers were in a similar early stage of necrosis with no macrophagic infiltration and diffuse sarcoplasmic C5b-9 deposition. A few small collections of perimysial perivascular inflammatory cells were present in the areas of the specimen not affected by ischemia. There was patchy capillary depletion and dilation; some capillaries in areas not affected by ischemia showed complement deposition. Myxovirus resistance protein A (MxA) expression occurred diffusely, especially in necrotic fibers, but without perifascicular predominance. Patient received IVIG 2g/Kg and prednisone 40 mg daily. The limb weakness stabilized while the dysphagia progressed. He expired 3 weeks later. <h3>Conclusions:</h3> RIIM is a rare myovasculopathy leading to muscle weakness in the setting of cancer. In keeping with published data, it has a poor prognosis. The identification of RIIM myopathological changes should trigger the search for underlying malignancy in patients without known cancer. <b>Disclosure:</b> Dr. Granger has nothing to disclose. Dr. Soontrapa has nothing to disclose. Dr. Klein has a non-compensated relationship as a Klein with Neurology Journal that is relevant to AAN interests or activities. Dr. Milone has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Argenx. Dr. Milone has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Neurology Genetics, AAN. The institution of Dr. Milone has received research support from Mayo Clinic, CCaTS-CBD. The institution of Dr. Milone has received research support from Mayo Clinic, SGP Award. The institution of Dr. Milone has received research support from MDA for Care Center grant. The institution of Dr. Milone has received research support from Regenerative medicine Minnesota.

Symptomatic Myopathies in Sarcoidosis: Disease Spectrum and Myxovirus Resistance Protein A (MxA) Expression (S7.002)

<h3>Objective:</h3> We aim to investigate clinical and pathological spectrum including myxovirus resistance protein A (MxA) expression among sarcoidosis patients with symptomatic myopathy. <h3>Background:</h3> About 50–80% of sarcoidosis patients have intramuscular granulomas, but only 0.5–2.5% exhibit myopathic symptoms. Symptomatic myopathy in sarcoidosis patients is not always due to sarcoid myopathy (SM). A few sarcoidosis patients have been reported to have coexisting inclusion body myositis (IBM) or other immune-mediated myopathies. <h3>Design/Methods:</h3> We reviewed Mayo Clinic database (May 1980 – December 2020) to identify sarcoidosis patients with myopathic symptoms and pathological evidence of myopathy. <h3>Results:</h3> Among 5,885 sarcoidosis patients, 21 had symptomatic myopathy. Eight carried diagnosis of sarcoidosis 5.5 years (median) prior to myopathy onset. Eleven patients had SM. The remaining had non-sarcoid myopathies (5 IBM, 1 immune-mediated necrotizing myopathy, 1 nonspecific myositis, 2 nonspecific myopathy and 1 steroid myopathy). Estimated frequency of IBM is 85 per 100,000 sarcoidosis patients. The following features were associated with non-sarcoid myopathies (p&lt;0.05): 1) predominant finger flexor and quadriceps weakness, 2) modified Rankin scale (mRS) &gt;2 at time of diagnosis, 3) creatine kinase &gt; 500 U/L, and 4) absence of intramuscular granulomas. Sarcoplasmic MxA expression was observed in scattered myofibers in 3 patients, 2 of whom tested for dermatomyositis-specific autoantibodies and were negative. Immunosuppressive therapy led to improvement in mRS ≥ 1 in 5/10 SM, none of the 5 IBM, and 3/3 remaining patients with non-sarcoid myopathies. <h3>Conclusions:</h3> Symptomatic myopathy occurred in 0.36% of sarcoidosis patients and only half had SM. One in every 4 sarcoidosis patients with myopathic symptoms had IBM. Frequency of IBM in sarcoidosis is higher than general population. Recognition of features suggestive of alternative etiologies can guide proper treatment and could prevent an unnecessary escalation of immunotherapy in the absence of active sarcoid. Our findings of abnormal MxA expression warrants a larger study. <b>Disclosure:</b> Dr. Chompoopong has nothing to disclose. Dr. Skolka has nothing to disclose. Floranne Ernste has received personal compensation in the range of $500-$4,999 for serving as an officer or member of the Board of Directors for The Myositis Association. The institution of Floranne Ernste has received research support from Octapharma. Dr. Liewluck has nothing to disclose.

Biomarkers of viral and bacterial infection in rhinovirus pneumonia.

Rhinovirus (RV) is often detected in children hospitalized with pneumonia, but the role of RV in causing pneumonia is still unclear. White blood cell count, C-reactive protein, procalcitonin, and myxovirus resistance protein A (MxA) levels were determined from blood samples in children (n = 24) hospitalized with radiologically verified pneumonia. Respiratory viruses were identified from nasal swabs by using reverse transcription polymerase chain reaction assays. Among RV-positive children, the cycle threshold value, RV subtyping by sequence analysis, and the clearance of RV by weekly nasal swabs were determined. RV-positive children with pneumonia were compared to other virus-positive children with pneumonia, and to children (n = 13) with RV-positive upper respiratory tract infection from a separate earlier study. RV was detected in 6 children and other viruses in 10 children with pneumonia (viral co-detections excluded). All RV-positive children with pneumonia had high white blood cell counts, plasma C-reactive protein or procalcitonin levels, or alveolar changes in chest radiograph strongly indicating bacterial infection. The median cycle threshold value for RV was low (23.2) indicating a high RV load, and a rapid clearance of RV was observed in all. Blood level of viral biomarker MxA was lower among RV-positive children with pneumonia (median 100 μg/L) than among other virus-positive children with pneumonia (median 495 μg/L, p = 0.034) or children with RV-positive upper respiratory tract infection (median 620 μg/L, p = 0.011). Our observations suggest a true viral-bacterial coinfection in RV-positive pneumonia. Low MxA levels in RV-associated pneumonia need further studies.

The relationship between a previous infectious disease caused by influenza, herpes simplex, or Epstein-Barr viruses as the biological threatening agents with recurrent episodes of multiple sclerosis

"Although multiple sclerosis (MS) is the most common neurological disease of young adults, afflicting hundreds of thousands of people worldwide, its pathogenesis is still only incompletely understood. There seems to be substantial heterogeneity in disease mechanisms, but in the majority of cases an autoimmune origin or at least a decisive autoimmune component is postulated. Therefore, pathogenic research focuses on different players programmed by the immune system. In this study, biomarkers such as Human myxovirus resistance protein A (MxA), Anti-EBNA antibody and Interleukin S10-12- 17 have been tested. Study of hypotheses show that: Interleukin levels in the blood of MS patients in the experimental group (patients with recurrence) is higher than controls (patients without recurrence condition). The level of anti-EBNA antibody in MS patients in other groups (patients with recurrent) and control group (patients without recurrence condition) is high. The level of the human myxovirus resistance protein A (MxA) in patients with multiple sclerosis in the experimental group (patients with recurrence) is less than the control group (patients without recurrence condition). The level of anti-EBNA antibody in MS patients in other groups (patients with recurrent) and control group (patients without recurrence condition) is high."

Increased Polymerase Activity of Zoonotic H7N9 Allows Partial Escape from MxA.

The interferon-induced myxovirus resistance protein A (MxA) is a potent restriction factor that prevents zoonotic infection from influenza A virus (IAV) subtype H7N9. Individuals expressing antivirally inactive MxA variants are highly susceptible to these infections. However, human-adapted IAVs have acquired specific mutations in the viral nucleoprotein (NP) that allow escape from MxA-mediated restriction but that have not been observed in MxA-sensitive, human H7N9 isolates. To date, it is unknown whether H7N9 can adapt to escape MxA-mediated restriction. To study this, we infected Rag2-knockout (Rag2-/-) mice with a defect in T and B cell maturation carrying a human MxA transgene (MxAtg/-Rag2-/-). In these mice, the virus could replicate for several weeks facilitating host adaptation. In MxAtg/-Rag2-/-, but not in Rag2-/- mice, the well-described mammalian adaptation E627K in the viral polymerase subunit PB2 was acquired, but no variants with MxA escape mutations in NP were detected. Utilizing reverse genetics, we could show that acquisition of PB2 E627K allowed partial evasion from MxA restriction in MxAtg/tg mice. However, pretreatment with type I interferon decreased viral replication in these mice, suggesting that PB2 E627K is not a true MxA escape mutation. Based on these results, we speculate that it might be difficult for H7N9 to acquire MxA escape mutations in the viral NP. This is consistent with previous findings showing that MxA escape mutations cause severe attenuation of IAVs of avian origin.

Diagnostic Accuracy of a Bacterial and Viral Biomarker Point-of-Care Test in the Outpatient Setting

Acute respiratory infections (ARIs) account for most outpatient visits. Discriminating bacterial vs viral etiology is a diagnostic challenge with therapeutic implications. To investigate whether FebriDx, a rapid, point-of-care immunoassay, can differentiate bacterial- from viral-associated host immune response in ARI through measurement of myxovirus resistance protein A (MxA) and C-reactive protein (CRP) from finger-stick blood. This diagnostic study enrolled adults and children who were symptomatic for ARI and individuals in a control group who were asymptomatic between October 2019 and April 2021. Included participants were a convenience sample of patients in outpatient settings (ie, emergency department, urgent care, and primary care) who were symptomatic, aged 1 year or older, and had suspected ARI and fever within 72 hours. Individuals with immunocompromised state and recent vaccine, antibiotics, stroke, surgery, major burn, or myocardial infarction were excluded. Of 1685 individuals assessed for eligibility, 259 individuals declined participation, 718 individuals were excluded, and 708 individuals were enrolled (520 patients with ARI, 170 patients without ARI, and 18 individuals who dropped out). Bacterial and viral immunoassay testing was performed using finger-stick blood. Results were read at 10 minutes, and treating clinicians and adjudicators were blinded to results. Bacterial- or viral-associated systemic host response to an ARI as determined by a predefined comparator algorithm with adjudication classified infection etiology. Among 520 participants with ARI (230 male patients [44.2%] and 290 female patients [55.8%]; mean [SD] age, 35.3 [17.7] years), 24 participants with missing laboratory information were classified as unknown (4.6%). Among 496 participants with a final diagnosis, 73 individuals (14.7%) were classified as having a bacterial-associated response, 296 individuals (59.7%) as having a viral-associated response, and 127 individuals (25.6%) as negative by the reference standard. The bacterial and viral test correctly classified 68 of 73 bacterial infections, demonstrating a sensitivity of 93.2% (95% CI, 84.9%-97.0%), specificity of 374 of 423 participants (88.4% [95% CI, 85.0%-91.1%]), positive predictive value (PPV) of 68 of 117 participants (58.1% [95% CI, 49.1%-66.7%), and negative predictive value (NPV) of 374 of 379 participants (98.7% [95% CI, 96.9%-99.4%]).The test correctly classified 208 of 296 viral infections, for a sensitivity of 70.3% (95% CI, 64.8%-75.2%), a specificity of 176 of 200 participants (88.0% [95% CI, 82.8%-91.8%]), a PPV of 208 of 232 participants (89.7% [95% CI, 85.1%-92.9%]), and an NPV of 176 of 264 participants (66.7% [95% CI, 60.8%-72.1%]). In this study, a rapid diagnostic test demonstrated diagnostic performance that may inform clinicians when assessing for bacterial or viral etiology of ARI symptoms.

Association of human myxovirus resistance protein A with severity of COVID-19

BackgroundIn this retrospective cohort study, we explored the correlation of blood human myxovirus resistance protein A (MxA) level with severity of disease in hospitalized COVID-19 patients.MethodsAll 304 patients admitted for COVID-19 in our hospital until 30th of April 2021 were included in this study. MxA was measured from peripheral blood samples in 268 cases. Patients were divided into groups based on their level of MxA on admission. We studied baseline characteristics and severity of disease on admission based on clinical parameters and inflammatory biomarker levels in each group. Severity of disease during hospitalization was determined by the applied level of respiratory support, by the usage of corticosteroids and by the duration of hospitalization.ResultsHigher MxA levels on admission were associated with a shorter duration of symptoms before admission, and with more severe disease. Adjusted Odds Ratios for any respiratory support were 9.92 (95%CI 2.11–46.58; p = 0.004) in patients with MxA between 400 μg/L and 799 μg/L (p = 0.004) and 20.08 (95%CI 4.51–89.44; p < 0.001) in patients with MxA ≥ 800 μg/L in comparison with patients with initial MxA < 400 μg/L. The usage of corticosteroids was significantly higher in the high-MxA group (77%) in comparison with the intermediate-MxA group (62%, p = 0.013) and low-MxA group (47%, p < 0.001).ConclusionsHigher initial levels of MxA were associated with more severe COVID-19. MxA may be a helpful additional biomarker to predict the severity of the disease.