Myxovirus Resistance Protein A Expression Research Articles

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.

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.

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.

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.

Myxovirus resistance protein A activates type I IFN signaling pathway to inhibit Zika virus replication

Myxovirus resistance protein A(MxA), one of the dynamin superfamily of large guanosine triphosphatase and a classical interferon stimulated gene (ISG) induced by type I interferons (IFNs), plays antiviral role in various virus infections. However, the effect of MxA on Zika virus (ZIKV) infection and its underlying mechanism remain elusive. In this study, we aimed to explore the role of MxA in ZIKV infection and its potential mechanisms. MxA overexpression was achieved by transfection with plasmid. The levels of MxA expression and ZIKV replication were assayed by both qRT-PCR and western blot. The activation status of Jak/STAT signaling pathway was evaluated at three levels: phosphorylation of STAT1 and STAT2(p-STAT1, p-STAT2) (western blot), activity of interferon sensitive response element (ISRE) (dual luciferase reporter gene assay), and the expression levels of ISGs (qRT-PCR). Our results showed that MxA overexpression inhibited ZIKV replication with no effect on virus entry. The expression levels of retinoic acid inducible gene I (RIG-I), melanoma differentiation-associated gene-5(MDA5), Toll-like receptor3(TLR3) and interferon regulatory Factor 3(IRF3), as well as IFNα and IFNβ, were increased in parallel with MxA upregulation. Interestingly, the inhibitory effect of MxA on ZIKV replication was abolished in type I IFN receptor (IFNAR) deficient cells (U5A). These data collectively supported that MxA inhibits ZIKV replication through activation of the type I IFN signaling pathway.

Skeletal Muscle and Peripheral Nerve Histopathology in COVID-19.

To explore the spectrum of skeletal muscle and nerve pathology of patients who died after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and to assess for direct viral invasion of these tissues. Psoas muscle and femoral nerve sampled from 35 consecutive autopsies of patients who died after SARS-CoV-2 infection and 10 SARS-CoV-2-negative controls were examined under light microscopy. Clinical and laboratory data were obtained by chart review. In SARS-CoV-2-positive patients, mean age at death was 67.8 years (range 43-96 years), and the duration of symptom onset to death ranged from 1 to 49 days. Four patients had neuromuscular symptoms. Peak creatine kinase was elevated in 74% (mean 959 U/L, range 29-8,413 U/L). Muscle showed type 2 atrophy in 32 patients, necrotizing myopathy in 9, and myositis in 7. Neuritis was seen in 9. Major histocompatibility complex-1 (MHC-1) expression was observed in all cases of necrotizing myopathy and myositis and in 8 additional patients. Abnormal expression of myxovirus resistance protein A (MxA) was present on capillaries in muscle in 9 patients and in nerve in 7 patients. SARS-CoV-2 immunohistochemistry was negative in muscle and nerve in all patients. In the 10 controls, muscle showed type 2 atrophy in all patients, necrotic muscle fibers in 1, MHC-1 expression in nonnecrotic/nonregenerating fibers in 3, MxA expression on capillaries in 2, and inflammatory cells in none, and nerves showed no inflammatory cells or MxA expression. Muscle and nerve tissue demonstrated inflammatory/immune-mediated damage likely related to release of cytokines. There was no evidence of direct SARS-CoV-2 invasion of these tissues. This study provides Class IV evidence that muscle and nerve biopsies document a variety of pathologic changes in patients dying of coronavirus disease 2019 (COVID-19).

Expression of MxA Protein in Triple Negative Breast Cancer and its Relationship with Prognosis

Objective: To explore the expression of human myxovirus resistance protein A (MxA) in triple negative breast cancer (TNBC) and its relationship with prognosis. Methods: 144 cases of TNBC confirmed by pathology before or after surgery from January 2014 to January 2017 in the First Central Hospital of Baoding City were retrospectively collected. Western blotting was used to detect the expression of MxA protein in TNBC and adjacent breast tissues. According to the expression of MxA protein, 144 TNBC patients were divided into low MxA protein expression group (n = 91) and MxA protein high expression group (n = 53) for subsequent comparison of prognosis of patients in between these two groups. Results: The expression of MxA protein in TNBC tissue was lower than that of adjacent breast tissue, and the difference was statistically significant (P&lt;0.05). The patients in high MxA expression group had higher loco-regional recurrence-free rate, disease-free survival (DFS) rate, and overall survival (OS) rate than those in low MxA expression group for 3 years. On the other hand, the distant metastasis rate was lower in the high expression group compared to that in the low MxA expression group, and the difference was statistically significant (P&lt;0.05). Conclusion: In triple-negative breast cancer, high MxA expression is a potential predictor of TNBC prognosis.

Perimysial microarteriopathy in dermatomyositis with anti-nuclear matrix protein-2 antibodies.

Dermatomyositis (DM) with anti-nuclear matrix protein-2 (NXP-2) antibodies usually shows multifocal ischaemic lesions in muscle. Here, we aimed to investigate the microarteriopathy underlying muscle ischaemia in anti-NXP-2-positive DM. A total of 16 patients diagnosed with anti-NXP-2-positive DM were investigated by muscle biopsy. A total of 13 patients with DM with other myositis-specific antibodies and 11 normal controls were included for comparison. Immunofluorescence assays were performed to localize endothelial cells, smooth muscle cells and pericytes, and to determine lesions in myofibers and microvessels by vascular endothelial growth factor and myxovirus resistance protein A (MxA). Electron microscopy was carried out to assess ultrastructure alterations. Subcutaneous edema, severe muscle weakness and dysphagia together with elevated creatine kinase, D-dimer and triglyceride levels, and decreased albumin levels were found in anti-NXP-2-positive DM. Muscle ischaemia included regional muscle edema, perifascicular atrophy, microinfarcts and focal punched-out vacuoles. The density of arterioles was higher in anti-NXP-2-positive DM (P＜0.05). Perimysial arterioles with thickened vascular wall, thrombosis and lipid accumulation were found in the vascular wall of diseased perimysial arterioles. The frequency of diseased arterioles and thrombosis was higher in anti-NXP-2-positive DM (P<0.05). Sarcoplasmic vascular endothelial growth factor and MxA expression was observed in multifocal ischaemic lesions. MxA was present in endothelial and smooth muscle cells of the diseased arterioles and pericytes. Electron microscopy confirmed damaged capillaries and tubuloreticular structures. Our research suggested that perimysial arterioles were most commonly involved in anti-NXP-2-positive DM, which led to muscle ischaemia.

Diagnostic potential of sarcoplasmic myxovirus resistance protein A expression in subsets of dermatomyositis

To elucidate the diagnostic value of sarcoplasmic expression of myxovirus resistance protein A (MxA) for dermatomyositis (DM) specifically analysing different DM subforms, and to test the superiority of MxA to other markers. Immunohistochemistry for MxA and retinoic acid-inducible gene I (RIG-I) was performed on skeletal muscle samples and compared with the item presence of perifascicular atrophy (PFA) in 57 DM patients with anti-Mi-2 (n=6), -transcription intermediary factor 1 gamma (n=10), -nuclear matrix protein 2 (n=13), -melanoma differentiation-associated gene 5 (MDA5) (n=10) or -small ubiquitin-like modifier activating enzyme (n=1) autoantibodies and with no detectable autoantibody (n=17). Among the patients, nine suffered from cancer and 22 were juvenile-onset type. Disease controls included antisynthetase syndrome (ASS)-associated myositis (n=30), immune-mediated necrotizing myopathy (n=9) and inclusion body myositis (n=5). Sarcoplasmic MxA expression featured 77% sensitivity and 100% specificity for overall DM patients, while RIG-I staining and PFA reached respectively 14% and 59% sensitivity and 100% and 86% specificity. In any subset of DM, sarcoplasmic MxA expression showed higher sensitivity than RIG-I and PFA. Some anti-MDA5 antibody-positive DM samples distinctively showed a scattered staining pattern of MxA. No ASS samples had sarcoplasmic MxA expression even though six patients had DM skin rash. Sarcoplasmic MxA expression is more sensitive than PFA and RIG-I expression for a pathological diagnosis of DM, regardless of the autoantibody-related subgroup. In light of its high sensitivity and specificity, it may be considered a pathological hallmark of DM per se. Also, lack of MxA expression in ASS supports the idea that ASS is a distinct entity from DM.

Expression of myxovirus-resistance protein A: a possible marker of muscle disease activity and autoantibody specificities in juvenile dermatomyositis.

AimsTo evaluate the relationship between expression of myxovirus‐resistance protein A (MxA) protein on muscle biopsies by immunohistochemistry and disease activity in juvenile dermatomyositis (JDM) patients. Also, another aim was to investigate whether the expression of MxA is related with myositis‐specific autoantibodies (MSA) status in JDM patients.Methods103 patients (median aged 6.3, interquartile range 0.5–15.9) enrolled in the Juvenile Dermatomyositis Cohort and Biomarker Study (JDCBS). Muscle biopsies were stained with MxA and scored. Clinical data at initial presentation were collected and autoantibodies were analysed. Multiple linear regression analysis was performed to estimate the association between MxA expression on muscle fibres and muscle disease activity, and MSA status.ResultsExpression of MxA protein on JDM samples was identified in 61.2%. There was a significant association between MxA scores and Childhood Myositis Assessment Scale (CMAS) (P = 0.002), and Manual Muscle Testing of Eight Muscles (MMT8) (P = 0.026). CMAS and MMT8 scores were significantly lower in the group of patients with strong MxA expression. MxA scores differed according to MSA subgroups (P = 0.002). Patients with positive nuclear matrix protein 2 autoantibodies had strong MxA expression, whereas anti‐melanoma differentiation‐associated gene 5 positive patients had no or weak MxA expression.ConclusionsThis study reveals the significant association between level of MxA expression on muscle fibres and clinical measures of muscular disease activity in JDM patients and MSA status. This confirms type I interferonopathies in muscle fibres of JDM patients which could help with improving treatment outcome in JDM patients and underscoring the distinct pathophysiological pathways in different MSA status.

Myxovirus resistance protein A inhibits hepatitis C virus replication through JAK-STAT pathway activation.

The interferon-inducible dynamin-like GTPase myxovirus resistance protein A (MxA) exhibits activity against multiple viruses. However, its role in the life cycle of hepatitis C virus (HCV) is unclear, and the mechanisms underlying the anti-HCV activity of MxA require further investigation. In this study, we demonstrated that exogenous MxA expression in the Huh7 and Huh7.5.1 hepatoma cell lines significantly decreased the levels of HCV RNA and core proteins, whereas MxA knockdown exerted the opposite effect. MxA-mediated inhibition of HCV replication was found to involve the JAK-STAT pathway: STAT1 phosphorylation and the expression of IFN-stimulated genes (ISGs) such as guanylate-binding protein 1 and 2'-5'-oligoadenylate synthetase 1 were augmented by MxA overexpression and reduced by endogenous MxA silencing. Treatment with the JAK inhibitor ruxolitinib abrogated the MxA-mediated suppression of HCV replication and activation of the JAK-STAT pathway. Additionally, transfection with an MxA mutant with disrupted GTP-binding consensus motifs abrogated activation of the JAK-STAT pathway and resistance to HCV replication. This study shows that MxA inhibits HCV replication by activating the JAK-STAT signaling pathway through a mechanism involving its GTPase function.

Outpatient Antibiotic Stewardship: A Growing Frontier-Combining Myxovirus Resistance Protein A With Other Biomarkers to Improve Antibiotic Use.

BackgroundThe majority of oral antibiotics are prescribed in outpatient primary and urgent care clinics for acute respiratory infections. Effective antibiotic stewardship must include proper prescribing for outpatients as well as for those in a hospital or long-term care facility. MethodsMajor databases, including MEDLINE and the Cochrane Library, were searched for prospective human clinical studies, including children and/or adults published between January 1966 and November 2017 that evaluated Myxovirus resistance protein A (MxA) as a biomarker for diagnosing viral infections as well as both C-reactive protein (CRP) and procalcitonin (PCT) as potential biomarkers for identifying and differentiating true bacterial upper respiratory infection (URI) from colonization.ResultsTen prospective human studies, totaling 1683 patients, were identified that evaluated MxA as a viral biomarker in children and/or adults. Both systematic review articles, meta-analyses, and randomized controlled clinical trials that examined CRP and/or PCT as a biomarker for identifying clinically significant bacterial infections and supporting antibiotic stewardship were identified.ConclusionsQuick and accurate differentiation between a viral and bacterial respiratory infection is critical to effectively combat antibiotic misuse. MxA expression in peripheral blood is a highly specific marker for viral infection. Combining MxA with other inflammatory biomarkers to test for respiratory infections offers enhanced sensitivity and specificity, forming an excellent tool for antibiotic stewardship in the outpatient setting.

Autocrine activation of the IFN signaling pathway may promote immune escape in glioblastoma.

Interferons (IFNs) are cytokines typically induced upon viral infection but are constitutively expressed also in the absence of acute infection. The physiological role of autocrine and paracrine IFN signaling, however, remains poorly understood, and its function in glioblastoma has not been explored in depth. Using RNA interference-mediated gene silencing, we characterized constitutive type I IFN signaling and its role in human glioma cells. We observed constitutive expression of phosphorylated signal transducer and activator of transcription 1 (pSTAT1) and myxovirus resistance protein A (MxA), a classical IFN-response marker, in the absence of exogenous IFN-β. In vivo, we found higher MxA expression in gliomas than in normal tissue, suggesting that IFN signaling is constitutively active in these tumors. To demonstrate the presence of an autocrine type I IFN signaling loop in glioma cells in vitro, we first confirmed the expression of the type I alpha/beta receptor (IFNAR)1/2, and its ligands, IFN-α and IFN-β. Small interfering RNA-mediated receptor gene silencing resulted in reduced expression of MxA at mRNA and protein levels, as did gene silencing of the ligands, corroborating the hypothesis of an autocrine signaling loop in which type I IFNs induce intracellular signaling through IFNAR1/2. On a functional level, following IFNAR1 or IFNAR2 gene silencing, we observed reduced programmed death ligand 1 (PD-L1) and major histocompatibility complex (MHC) class I and II expression as well as an enhanced susceptibility to natural killer immune cell lysis, suggesting that autocrine IFN signaling contributes to the immune evasion of glioma cells. Our findings point to an important role of constitutive IFN signaling in glioma cells by modulating their interaction with the microenvironment.

The host defense peptide LL-37 a possible inducer of the type I interferon system in patients with polymyositis and dermatomyositis

The type I interferon (IFN) system has recently been suggested to play important and essential roles in the pathogenesis of myositis. However, a clarification of how type I IFNs could function as triggering factor(s) in the pathogenesis of myositis has yet failed. Through activation of the type I IFN system, the host defense peptide LL-37 carries numerous immunomodulatory properties and is implicated in the pathogenesis of several other autoimmune diseases, including systemic lupus erythematosus (SLE). The expression of LL-37 can be regulated by various endogenous factors including the active form of vitamin D (25(OH)D3). The aim of this study was to explore a potential role of LL-37 in relation to the type I IFN system in patients with polymyositis (PM) and dermatomyositis (DM) and to compare these with SLE patients and healthy controls. We investigated muscle (3 PM, 5 DM) and symptomatic (5 DM) and non-symptomatic (3 PM, 3 DM) skin biopsies from patients with short disease duration and muscle biopsies (3 PM, 1 DM) from patients with long disease duration. Six SLE patients with symptomatic and non-symptomatic skin and five muscle and six skin biopsies from healthy individuals served as controls. Tissue specimens were immunohistochemically stained for LL-37, neutrophils (CD66b), plasmacytoid dendritic cells (BDCA-2), myxovirus resistance protein A (MxA), and macrophages (CD68, CD163). In addition, LL-37 and CD66b double staining was also performed. Serum levels of 25(OH)D3 were investigated in PM and DM patients with short disease duration (3 PM, 5 DM) and in 40 healthy controls. We found that the expression of LL-37, BDCA-2 (the major producer of type I IFNs), MxA (an interferon-inducible protein), and macrophages were higher in muscle tissue of PM and DM patients compared to healthy controls. The LL-37 expression was mainly derived from neutrophils. Neutrophils were increased in both symptomatic and non-symptomatic skin of myositis and SLE patients and BDCA-2 was increased in symptomatic DM skin when compared to healthy controls. Moreover, the expression of MxA in symptomatic and non-symptomatic skin of SLE patients was higher when compared to both myositis patients and healthy controls. There was no difference in the expression of LL-37 in skin of myositis and SLE patients compared to healthy controls. All PM and DM patients with a short disease duration had low 25(OH)D3 levels compared to healthy controls. In conclusion, the present study supports our hypothesis that LL-37 may activate type I IFNs, which could initiate and perpetuate an inflammatory process. The prolonged exposure of the immune system to type I IFNs may eventually break tolerance and lead to autoimmune myositis.

Absence of MxA induction is related to a poor clinical response to interferon beta treatment in multiple sclerosis patients.

The aim of this study is to investigate whether induction of myxovirus resistance protein A (MxA) mRNA after 3 months of interferon-β administration is related to the treatment response in multiple sclerosis (MS) patients. In this prospective study, MS patients were enrolled before starting treatment. Demographic, clinical and radiological variables were recorded. Blood samples were obtained before, and at 3 and 12 months after interferon-β treatment. Real-time PCR was used to analyze MxA mRNA expression. Patients were classified as MxA-low or -high depending on MxA levels at baseline, and as MxA-induced or -non-induced according to whether an increase in MxA expression was detected at month 3. Time to the next relapse was investigated using Cox proportional hazards regression analysis. One hundred and four patients were selected and followed for a median of 2.2 years (IQR 1.6-3.5). On Cox regression analysis, a higher EDSS score before treatment (HR 1.57; 95 % CI 1.02-2.40; p = 0.039), MxA-high status at baseline (HR 2.71; 95 % CI 1.26-5.81; p = 0.010), and MxA-non-induced at month 3 (HR 2.49; 95 % CI 1.08-5.68; p = 0.031), were predictors of poor response to interferon-β in naïve MS patients. Patients showing a lower capacity for MxA induction following 3 months of interferon-β treatment are more likely to be non-responders to this therapy.

Immunological Changes and Increased Expression of Myxovirus Resistance Protein A in Thyroid Tissue of Patients with Recent Onset and Untreated Graves' Disease

Few studies have systematically examined the immune cells that infiltrate thyroid tissue at the time of the onset of Graves' disease (GD). The role of viruses in the pathogenesis of autoimmune thyroid diseases is controversial. The present study analyzed inflammatory responses with respect to signs of virus infection. Thyroid tissue was obtained from 22 patients with newly diagnosed and untreated GD, 24 patients with chronic GD, and 24 controls. Inflammation was assessed by immunostaining for CD4+ and CD8+ T cells, plasma cells (CD138+), and plasmacytoid dendritic cells (PDCs). The production of interferon-inducible myxovirus resistance protein A (MxA) was analyzed as a sign of virus infection. The degree of thyroid inflammation and fibrosis was significantly higher in both patient groups compared with that in controls. The number of CD4+ T cells and plasma cells (activated B cells) was significantly higher in both patient groups. CD8+ cells were only present in patients with chronic disease. MxA expression and the number of PDCs increased only in patients with newly diagnosed GD. There was a strong positive correlation between the number of PDCs and the number of MxA+ leucocytes. The increase in CD8+ T cells during the chronic stage of GD suggests that they may play a role in progression of the autoimmune process from early to chronic thyroiditis. Upregulation of MxA expression during the early stages of the disease, and the positive correlation between the number of PDCs and the number of MxA+ leucocytes, suggests that activated PDCs secrete type I IFNs at the lesion site, possibly in response to viral infection.

Progesterone suppresses interferon signaling by repressing TLR-7 and MxA expression in peripheral blood mononuclear cells of patients infected with hepatitis C virus

This study aimed at investigating the effect of progesterone on interferon signaling pathways in peripheral blood mononuclear cells (PBMCs) of patients infected with hepatitis C virus (HCV). PBMCs were isolated from peripheral blood of 38 treatment-naïve HCV-infected patients, pooled, and stimulated with progesterone in the presence and absence of its receptor antagonist, mifepristone, along with interferon alpha (IFN-α) or imiquimod. Toll-like receptor (TLR) 7 and myxovirus resistance protein A (MxA) were quantified in PBMCs using RT-qPCR. Imiquimod alone or combined with progesterone did not change MxA expression in HCV-infected PBMCs. Progesterone decreased the inducing effect of IFN-α on TLR-7 expression in both males and females. Moreover, progesterone stimulation prior to IFN-α treatment attenuated the Jak/STAT pathway, which was reflected by decreased expression of MxA in females. Progesterone showed a negative impact on the IFN signaling pathway in HCV-infected PBMCs as it decreased the expression of TLR-7 in both genders, while MxA expression was decreased only in females.

Association of TRIM22 with the Type 1 Interferon Response and Viral Control during Primary HIV-1 Infection

Type 1 interferons (IFNs) induce the expression of the tripartite interaction motif (TRIM) family of E3 ligases, but the contribution of these antiviral factors to HIV pathogenesis is not completely understood. We hypothesized that the increased expression of select type 1 IFN and TRIM isoforms is associated with a significantly lower likelihood of HIV-1 acquisition and viral control during primary HIV-1 infection. We measured IFN-α, IFN-β, myxovirus resistance protein A (MxA), human TRIM5α (huTRIM5α), and TRIM22 mRNA levels in peripheral blood mononuclear cells (PBMCs) of high-risk, HIV-1-uninfected participants and HIV-1-positive study participants. Samples were available for 32 uninfected subjects and 28 infected persons, all within 1 year of infection. HIV-1-positive participants had higher levels of IFN-β (P = 0.0005), MxA (P = 0.007), and TRIM22 (P = 0.01) and lower levels of huTRIM5α (P < 0.001) than did HIV-1-negative participants. TRIM22 but not huTRIM5α correlated positively with type 1 IFN (IFN-α, IFN-β, and MxA) (all P < 0.0001). In a multivariate model, increased MxA expression showed a significant positive association with viral load (P = 0.0418). Furthermore, TRIM22 but not huTRIM5α, IFN-α, IFN-β, or MxA showed a negative correlation with plasma viral load (P = 0.0307) and a positive correlation with CD4(+) T-cell counts (P = 0.0281). In vitro studies revealed that HIV infection induced TRIM22 expression in PBMCs obtained from HIV-negative donors. Stable TRIM22 knockdown resulted in increased HIV-1 particle release and replication in Jurkat reporter cells. Collectively, these data suggest concordance between type 1 IFN and TRIM22 but not huTRIM5α expression in PBMCs and that TRIM22 likely acts as an antiviral effector in vivo.

Inhibition of interferon-α-induced signaling by hyperosmolarity and hydrophobic bile acids

Apart from viral conditions, host factors such as elevated bile acid concentrations are determinants of successful interferon-α (IFN-α) treatment in patients with chronic hepatitis C or B. The present study demonstrates that hydrophobic bile acids inhibit Jak1- and Tyk2-phosphorylation, which lead to blockade of STAT1-mediated IFN-α-signaling in the sodium-taurocholate cotransporting peptide (NTCP)-transfected human hepatoma cell line HepG2, resulting in a decreased mRNA and protein expression of IFN-stimulated genes such as myxovirus resistance protein A (MxA) or dsRNA-activated protein kinase (PKR). In addition, hyperosmotic stress leads to an inhibition of IFN-α-induced Jak1- and Tyk2-phosphorylation, and STAT1/STAT2-phosphorylation and gene expression. This inhibitory effect of hydrophobic bile acids or hyperosmolarity is not due to caspase-mediated cleavage or lysosomal degradation of the cognate receptors or to the generation of oxidative stress, activation of p38- or Erk-mediated MAPK pathways or phosphatase activity. Preincubation with the organic osmolyte betaine blocked the inhibitory effect of bile acids or hyperosmolarity on MxA protein expression, but had no effect on transcript levels or activation of STAT1, suggesting that betaine mediates its effects on MxA expression at a translational or post-translational level. Our findings could provide a rationale for betaine use in cholestatic HBV/HCV patients undergoing interferon therapy.

Neutralizing antibodies, MxA expression and MMP‐9/TIMP‐1 ratio as markers of bioavailability of interferon‐beta treatment in multiple sclerosis patients: a two‐year follow‐up study

The objective of this study was to correlate the detection of neutralizing antibodies (NAbs) by the cytopathic effect (CPE) assay, with the expression of myxovirus resistance protein A (MxA), and the ratio between matrix metalloproteinase 9 (MMP-9) and its tissular inhibitor (TIMP-1), in order to evaluate their usefulness as markers of interferon beta (IFN-beta) bioavailability. Pairs of blood and serum samples were collected from 50 patients with multiple sclerosis (MS) during 2 years of IFN-beta treatment. Expression of MxA, MMP-9 and TIMP-1 were analysed by quantitative PCR, and NAbs were measured by CPE assay. During the study, 60% of patients presented NAbs. The number of serum samples that were NAbs+ was significantly increased amongst patients with relapses (41/92 vs. 33/108, P = 0.04). With one serum sample and with a NAb titre >100 tenfold reduction unit (TRU), 66.7% of patients with MS suffered from relapses, 41.7% suffered from progression, and 75% was not an optimal clinical responder. We did not find any significant difference in MxA. We found that 62.5% of patients with MS patients whose ratio was increased twofold after 2 years suffered from relapses, 37.5% suffered from progression, and 68.7% was not an optimal clinical responder. The early detection of NAbs by CPE assay and the finding of only one serum sample with a NAb titre >100 TRU seem to be markers of low bioavailability of IFN-beta, whilst a twofold decrease in the MMP-9/TIMP-1 ratio by quantitative PCR assay seems to be a marker of high bioavailability of IFN-beta.