SRP-positive necrotising myopathy: takes more than just the muscles.

Necrotising myopathy is an autoimmune disease that commonly affects muscles. Here we examine a case of a middle-aged women presenting with a chief report of shortness of breath, who subsequently developed muscle weakness. Her clinical course was complicated by respiratory failure and pulmonary hypertension likely due to the underlying pathology of signal recognition particle-positive necrotising myopathy. After further evaluation, her shortness of breath was thought to be secondary to muscle pathology rather than cardiopulmonary pathology. She was transferred to our institution for workup by rheumatology. At the time of admission, 6 months after initial presentation, her weakness progressed, so that she was unable to lift her arms and legs against gravity. Furthermore, neurological examination revealed mild facial and nuchal weakness, severe proximal weakness, more moderate distal weakness and global areflexia.

Parasite specific 7SL-derived small RNA is an effective target for diagnosis of active trypanosomiasis infection.

Human and animal African trypanosomiasis (HAT & AAT, respectively) remain a significant health and economic issue across much of sub-Saharan Africa. Effective control of AAT and potential eradication of HAT requires affordable, sensitive and specific diagnostic tests that can be used in the field. Small RNAs in the blood or serum are attractive disease biomarkers due to their stability, accessibility and available technologies for detection. Using RNAseq, we have identified a trypanosome specific small RNA to be present at high levels in the serum of infected cattle. The small RNA is derived from the non-coding 7SL RNA of the peptide signal recognition particle and is detected in the serum of infected cattle at significantly higher levels than in the parasite, suggesting active processing and secretion. We show effective detection of the small RNA in the serum of infected cattle using a custom RT-qPCR assay. Strikingly, the RNA can be detected before microscopy detection of parasitaemia in the blood, and it can also be detected during remission periods of infection when no parasitaemia is detectable by microscopy. However, RNA levels drop following treatment with trypanocides, demonstrating accurate prediction of active infection. While the small RNA sequence is conserved between different species of trypanosome, nucleotide differences within the sequence allow generation of highly specific assays that can distinguish between infections with Trypanosoma brucei, Trypanosoma congolense and Trypanosoma vivax. Finally, we demonstrate effective detection of the small RNA directly from serum, without the need for pre-processing, with a single step RT-qPCR assay. Our findings identify a species-specific trypanosome small RNA that can be detected at high levels in the serum of cattle with active parasite infections. This provides the basis for the development of a cheap, non-invasive and highly effective diagnostic test for trypanosomiasis.

Statin-naïve anti-HMGCR antibody-mediated necrotizing myopathy in China.

This study aimed to clarify the phenotypes and therapeutic responses of statin-naïve anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) antibody-mediated necrotizing myopathy. Anti-HMGCR antibodies were tested with ELISA methodology in the sera sample of 98 patients meeting the idiopathic inflammatory myopathy criteria and with negative anti-signal recognition particle (SRP) antibody. Twenty-one statin-naïve patients with anti-HMGCR antibody were detected (21.4%), with onset age from 6 to 67 years old. Proximal weakness and neck flexion weakness was the core neurological feature. The average maximal creatine kinase (CK) level was 7968.6 ±â€¯4408.7U/L. Muscle MR imaging showed edema (88.2%), moderate or severe fatty replacement (70.6%) and muscle atrophy (88.2%) in lower limbs. Fatty replacement was significantly more prominent in the medial and posterior musculature than the anterior musculature (p = 0.0013). Seven (33.3%) patients were treated with mono-glucocorticoid, and thirteen (61.9%) patients needed adjuvant immunosuppressant. Eight (38.1%) patients experienced symptom relapse. The early-onset patients (<50 years old) were found with higher CK levels, shorter duration course, poorer response to adjuvant immunosuppressant and more recurrent weakness than the late-onset patients (≥50 years old). As a conclusion, Statin-naïve anti-HMGCR antibody-mediated necrotizing myopathy may not be rare. Compared with late-onset statin-naïve patients with anti-HMGCR antibody-mediated necrotizing myopathy, early-onset patients presented severer clinical features and worse therapeutic responses.

HULC and 7SL RNA expression levels in patients with Crimean-Congo hemorrhagic fever.

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease caused by the Crimean-Congo hemorrhagic fever virus. Long non-coding RNAs (lncRNAs) are generally classified as transcripts longer than 200 nucleotides (nt). The various lncRNAs expressed in infected cells are responsible for regulating the expression of viral and host genes. This is the first study to investigate hepatocellular carcinoma upregulated long non-coding RNA (HULC) and 7SL RNA expression levels in patients with CCHF. Blood samples were taken from 100 individuals (60 patients and 40 controls), and total RNA isolation was performed. Quantitative polymerase chain reaction (qPCR) was performed using the SYBR Green method to determine HULC and 7SL RNA expression levels in the study population. Compared the patient and control groups, HULC was upregulated statistically significantly (P = 0.04) and 7SL RNA was downregulated (P = 0.93) in patients. Also, there was a statistically significant difference between fatal cases and surviving patients for HULC and 7SL RNA (P < 0.01 and P = 0.03, respectively). In addition, HULC expression was increased statistically significantly in fatal cases compared with surviving patients in terms of clinical parameters such as aspartate aminotransferase (P < 0.01), alanine aminotransferase (P < 0.01), international normalized ratio (P = 0.05), prothrombin time (P = 0.01), active partial thromboplastin time (P < 0.01), and lactate dehydrogenase (P < 0.01). These findings highlighted that HULC and 7SL RNA could be important mediators for studying the pathogenesis of CCHF and significant therapeutic targets of the disease.

7SL RNA in vertebrate red blood cells.

We report that 7SL, the RNA component of the signal recognition particle (SRP), is an abundant noncoding RNA (ncRNA) in mature red blood cells (RBCs) of human, mouse, and the frog Xenopus. 7SL RNA in RBCs is not associated with the canonical proteins of the SRP. Instead, it coimmunoprecipitates from a lysate of RBCs with a number of membrane-binding proteins. Human and mouse RBCs also contain a previously undescribed 68 nt RNA, sRN7SL, derived from the "S domain" of 7SL RNA. We discuss the possibility that 7SL RNA is selectively protected from nucleases by association with the RBC membrane. Because 7SL is not associated with the canonical proteins of the SRP, it could represent a nonfunctional remnant of the protein synthetic machinery. Alternatively, it could play a new, as yet undefined role in RBC metabolism.

Childhood autoimmune necrotizing myopathy with anti-signal recognition particle antibodies.

INTRODUCTION: The aim of this study was to describe the therapeutic effects of immunomodulatory therapy in 3 patients with childhood autoimmune necrotizing myopathy with anti-signal recognition particle antibodies (SRP-ANM). METHODS: Before treatment, data on clinical features, muscle pathology, and thigh MRIs were obtained. After definitive diagnoses, all 3 patients were treated with intravenous immunoglobulin and corticosteroids, and thigh MRIs were performed. RESULTS: Clinical improvements were associated with declines in serum creatine kinase levels. Pretreatment thigh MRIs revealed diffuse, but uneven or focal edema, mostly in the posterior thigh muscles, which was alleviated after immunomodulatory therapy. DISCUSSION: Childhood SRP-ANM responded well to immunomodulatory therapy. The extent of edema, as monitored by thigh MRI, appears to be a useful marker of disease severity and therapeutic benefit. Muscle Nerve 56: 1181-1187, 2017.

Autoantibody levels in myositis patients correlate with clinical response during B cell depletion with rituximab.

OBJECTIVES: To determine the longitudinal trends in serum levels of four myositis-associated autoantibodies: anti-Jo-1, -transcription intermediary factor 1 γ (TIF1-γ), -signal recognition particle (SRP) and -Mi-2, after B cell depletion with rituximab, and to determine the longitudinal association of these autoantibody levels with disease activity as measured by myositis core-set measures (CSMs). METHODS: Treatment-resistant adult and pediatric myositis subjects (n = 200) received rituximab in the 44-week Rituximab in Myositis Trial. CSMs [muscle enzymes, manual muscle testing (MMT), physician and patient global disease activity, HAQ, and extramuscular disease activity] were evaluated monthly and anti-Jo-1 (n = 28), -TIF1-γ (n = 23), -SRP (n = 25) and -Mi-2 (n = 26) serum levels were measured using validated quantitative ELISAs. Temporal trends and the longitudinal relationship between myositis-associated autoantibodies levels and CSM were estimated using linear mixed models. RESULTS: Following rituximab, anti-Jo-1 levels decreased over time (P < 0.001) and strongly correlated with all CSMs (P < 0.008). Anti-TIF1-γ levels also decreased over time (P < 0.001) and were only associated with HAQ, MMT and physician and patient global disease activity. Anti-SRP levels did not change significantly over time, but were significantly associated with serum muscle enzymes. Anti-Mi-2 levels significantly decreased over time and were associated with muscle enzymes, MMT and the physician global score. CONCLUSION: Anti-Jo-1, anti-TIF1-γ and anti-Mi-2 levels in myositis subjects decreased after B cell depletion and were correlated with changes in disease activity, whereas anti-SRP levels were only associated with longitudinal muscle enzyme levels. The strong association of anti-Jo-1 levels with clinical outcomes suggests that anti-Jo-1 autoantibodies may be a good biomarker for disease activity.

A new biodosimetric method: branched DNA-based quantitative detection of B1 DNA in mouse plasma.

A simple and accurate method for measuring the biological effects of radiation is of increasing importance, especially in mass casualty scenarios. We have therefore developed a new biodosimetric technique targeting circulating B1 DNA in mouse plasma by branched DNA signal amplification for rapid quantification of plasma DNA. This technology targets repetitive elements of the B1 retrotransposon in the mouse genome, followed by signal amplification using Panomics Quantigene 2.0 reagents. Evaluation was conducted concerning precision, accuracy and linearity. Plasma samples were collected from mice 0-24 h after 0-10 Gy total body irradiation (TBI). The average inter- and intra-assay coefficients of variance were 8.7% and 12.3%, respectively. The average recovery rate of spiked DNA into plasma was 89.5%. This assay revealed that when BALB/c and NIH Swiss mice were exposed to 6 Gy TBI, plasma B1 DNA levels increased significantly at 3 h post-TBI, peaked at 9 h and gradually returned toward baseline levels in 24 h. A dose-dependent change in plasma DNA was observed at 9 h post-TBI; the dose-response relation was monotonic, exhibiting linearity for BALB/c mice from 3 to 6 Gy (r = 0.993) and NIH Swiss mice from 3 to 7 Gy (r = 0.98). This branched DNA-based assay is reliable, accurate and sensitive in detecting plasma B1 DNA quantitatively. A radiation dose-correlated increase in plasma B1 DNA was demonstrated in BALB/c and NIH Swiss mice in the dose range from 3 to 6 Gy, suggesting that plasma B1 DNA has potential as a biomarker for radiation biological effect.

Interaction of rice and human SRP19 polypeptides with signal recognition particle RNA.

The signal recognition particle (SRP) controls the transport of secretory proteins into and across lipid bilayers. SRP-like ribonucleoprotein complexes exist in all organisms, including plants. We characterized the rice SRP RNA and its primary RNA binding protein, SRP19. The secondary structure of the rice SRP RNA was similar to that found in other eukaryotes; however, as in other plant SRP RNAs, a GUUUCA hexamer sequence replaced the highly conserved GNRA-tetranucleotide loop motif at the apex of helix 8. The small domain of the rice SRP RNA was reduced considerably. Structurally, rice SRP19 lacked two small region that can be present in other SRP19 homologues. Conservative structure prediction and site-directed mutagenesis of rice and human SRP19 polypeptides indicated that binding to the SRP RNAs occurred via a loop that is present in the N-domain of both proteins. Rice SRP19 protein was able to form a stable complex with the rice SRP RNA in vitro. Furthermore, heterologous ribonucleoprotein complexes with components of the human SRP were assembled, thus confirming a high degree of structural and functional conservation between plant and mammalian SRP components.