Aminoacyl-tRNA Synthetases: On Anti-Synthetase Syndrome and Beyond

UPLC/Q-TOF-MS-based metabolomics and molecular docking analysis of Bifidobacterium adolescentis exposure to levofloxacin

Antibiotic-associated diarrhea is a common adverse reaction caused by the widespread use of antibiotics. The decrease in probiotics is one of the reasons why antibiotics cause drug-induced diarrhea. However, few studies have addressed the intrinsic mechanism of antibiotics inhibiting probiotics. To investigate the underlying mechanism of levofloxacin against Bifidobacterium adolescentis, we used a metabolomics mass spectrometry-based approach and molecular docking analysis for a levofloxacin-induced B. adolescentis injury model. The results showed that levofloxacin reduced the survival rate of B. adolescentis and decreased the number of B. adolescentis. The untargeted metabolomics analysis identified 27 potential biomarkers, and many of these metabolites are involved in energy metabolism, amino acid metabolism and the lipid metabolism pathway. Molecular docking showed that levofloxacin can bind with aminoacyl-tRNA synthetase and lactic acid dehydrogenase. This result provides a novel insight into the mechanism of the adverse reactions of levofloxacin.

Review of Pulmonary Manifestations in Antisynthetase Syndrome

Antisynthetase syndrome (ASyS) is now a widely recognized entity within the spectrum of idiopathic inflammatory myopathies. Initially described in patients with a triad of myositis, arthritis, and interstitial lung disease (ILD), its presentation can be diverse. Additional common symptoms experienced by patients with ASyS include Raynaud's phenomenon, mechanic's hand, and fever. Although there is a significant overlap with polymyositis and dermatomyositis, the key distinction lies in the presence of antisynthetase antibodies (ASAs). Up to 10 ASAs have been identified to correlate with a presentation of ASyS, each having manifestations that may slightly differ from others. Despite the proposal of three classification criteria to aid diagnosis, the heterogeneous nature of patient presentations poses challenges. ILD confers a significant burden in patients with ASyS, sometimes manifesting in isolation. Notably, ILD is also often the initial presentation of ASyS, requiring pulmonologists to remain vigilant for an accurate diagnosis. This article will comprehensively review the various aspects of ASyS, including disease presentation, diagnosis, management, and clinical course, with a primary focus on its pulmonary manifestations.

Association between anti-PL7 antibodies and increased fibrotic component in patients with antisynthetase syndrome and interstitial lung disease: a cross-sectional study

OBJECTIVE

To evaluate whether anti-PL7 and anti-PL12 autoantibodies are associated with a greater extent of the fibrotic component of ILD in ASSD patients.

METHODS

Patients with ILD-ASSD who were positive for one of the following autoantibodies: anti-Jo1, anti-PL7, anti-PL12, and anti-EJ were included. Clinical manifestations, CPK levels, pulmonary function tests, and HCRT assessments were prospectively collected according to the Goh index. The fibrotic, inflammatory, and overall extension of the Goh index and DLCO were assessed by multiple linear analyses and compared between ASSD antibody subgroups.

RESULTS

Sixty-six patients were included; 17 were positive for anti-Jo1 (26%), 17 for anti-PL7 (26%), 20 for anti-PL12 (30%), and 9 (14%) for anti-EJ. Patients with anti-PL7 and anti-PL12 had a more extensive fibrotic component than anti-Jo1. Anti-PL7 patients had a 7.9% increase in the fibrotic extension (cβ = 7.9; 95% CI 1.863, 13.918), and the strength of the association was not modified after controlling for sex, age, and time of disease evolution (aβ = 7.9; 95% CI 0.677, 15.076) and also was associated with an increase in ILD severity after adjusting for the same variables, denoted by a lower DLCO (aβ =  - 4.47; 95% CI - 8.919 to - 0.015).

CONCLUSIONS

Anti-PL7-positive ASSD patients had more extensive fibrosis and severe ILD than the anti-Jo1 subgroup. This information is clinically useful and has significant implications for managing these patients, suggesting the need for early consideration of concurrent immunosuppressive and antifibrotic therapy.

Beyond protein synthesis: non-translational functions of threonyl-tRNA synthetases

Aminoacyl-tRNA synthetases (AARSs) play an indispensable role in the translation of mRNAs into proteins. It has become amply clear that AARSs also have non-canonical or non-translational, yet essential, functions in a myriad of cellular and developmental processes. In this mini-review we discuss the current understanding of the roles of threonyl-tRNA synthetase (TARS) beyond protein synthesis and the underlying mechanisms. The two proteins in eukaryotes - cytoplasmic TARS1 and mitochondrial TARS2 - exert their non-canonical functions in the regulation of gene expression, cell signaling, angiogenesis, inflammatory responses, and tumorigenesis. The TARS proteins utilize a range of biochemical mechanisms, including assembly of a translation initiation complex, unexpected protein-protein interactions that lead to activation or inhibition of intracellular signaling pathways, and cytokine-like signaling through cell surface receptors in inflammation and angiogenesis. It is likely that new functions and novel mechanisms will continue to emerge for these multi-talented proteins.

A Review of Antisynthetase Syndrome-Associated Interstitial Lung Disease

Our objective in this review article is to present a clinical case of a patient with antisynthetase syndrome (ASyS) and provide an overview of the pathogenesis, classification criteria, antibody profiles, clinical features, and current knowledge of treatment options, focusing on interstitial lung disease (ILD). ASyS is an uncommon autoimmune disease with a heterogenous clinical presentation characterized by the presence of autoantibodies against an aminoacyl-tRNA synthetase and manifested by myositis, fever, inflammatory arthritis, Raynaud's phenomenon, mechanics hands, and ILD. ASyS-associated ILD (ASyS-ILD) is the most serious complication of ASyS, which may evolve to rapidly progressive ILD; therefore, it often requires thorough clinical and radiologic evaluation including recognition of a specific clinical phenotype associated with the antisynthetase antibodies (ASAbs) to guide therapeutic interventions.

Autoantibody evaluation in idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM), generally referred to as myositis is a heterogeneous group of diseases characterized by muscle inflammation and/or skin involvement, diverse extramuscular manifestations with variable risk for malignancy and response to treatment. Contemporary clinico-serologic categorization identifies 5 main clinical groups which can be further stratified based on age, specific clinical manifestations and/or risk for cancer. The serological biomarkers for this classification are generally known as myositis-specific (MSAs) and myositis-associated antibodies. Based on the use of these antibodies, IIM patients are classified into anti-synthetase syndrome, dermatomyositis, immune-mediated necrotizing myopathy, inclusion body myositis, and overlap myositis. The current classification criteria for IIM requires clinical findings, laboratory measurements, and histological findings of the muscles. However, the use MSAs and myositis-associated autoantibodies as an adjunct for disease evaluation is thought to provide a cost-effective personalized approach that may not only guide diagnosis but aid in stratification and/or prognosis of patients. This review provides a comprehensive overview of contemporary autoantibodies that are specific or associated myositis. In addition, it highlights possible pathways for the detection and interpretation of these antibodies with limitations for routine clinical use.

The enchanting canvas of CAR technology: Unveiling its wonders in non-neoplastic diseases

Chimeric antigen receptor (CAR) T cells have made a groundbreaking advancement in personalized immunotherapy and achieved widespread success in hematological malignancies. As CAR technology continues to evolve, numerous studies have unveiled its potential far beyond the realm of oncology. This review focuses on the current applications of CAR-based cellular platforms in non-neoplastic indications, such as autoimmune, infectious, fibrotic, and cellular senescence-associated diseases. Furthermore, we delve into the utilization of CARs in non-T cell populations such as natural killer (NK) cells and macrophages, highlighting their therapeutic potential in non-neoplastic conditions and offering the potential for targeted, personalized therapies to improve patient outcomes and enhanced quality of life.

Glycyl-tRNA Synthetase Induces Psoriasis-Like Skin by Facilitating Skin Inflammation and Vascular Endothelial Cell Angiogenesis

Psoriasis is characterized by excessive keratinocyte proliferation and immunocyte infiltration, but the underlying pathogenesis remains unclear. Aminoacyl-tRNA synthetases are universally expressed enzymes that catalyze the first step of protein synthesis. Glycyl-tRNA synthetase (GARS) is a member of the aminoacyl-tRNA synthetase family. In addition to its canonical function, we found that GARS was overexpressed in the serum and skin lesions of patients with psoriasis. Moreover, GARS was highly expressed in human skin keratinocytes, and GARS knockdown in keratinocytes suppressed cell proliferation and promoted apoptosis through NF-κB/MAPK signaling pathway. Moreover, intradermal injection of recombinant GARS protein caused skin thickening, angiogenesis, and IFN/TNF-driven skin inflammation. Intriguingly, the reported functional receptor for GARS, cadherin 6 (CDH6), was specifically expressed in vascular endothelial cells, and we found that keratinocyte-derived GARS promotes inflammation and angiogenesis of vascular endothelial cells through CDH6. In addition, intradermal injection of GARS aggravated the phenotype and angiogenesis in imiquimod-induced psoriasiform dermatitis models, whereas the psoriatic phenotype and angiogenesis were relieved after knockdown of GARS by adeno-associated virus. Taken together, the results of this study identify the critical role of GARS in the pathogenesis of psoriasis and suggest that blocking GARS may be a therapeutic approach for alleviating psoriasis.

Anti-synthetase syndrome is associated with a higher risk of hospitalization among patients with idiopathic inflammatory myopathy and COVID-19

Background

Data with fine granularity about COVID-19-related outcomes and risk factors were still limited in the idiopathic inflammatory myopathies (IIMs) population. This study aimed to investigate clinical factors associated with hospitalized and severe COVID-19 in patients with IIMs, particularly those gauged by myositis-specific antibodies.

Methods

This retrospective cohort study was conducted in the Renji IIM cohort in Shanghai, China, under an upsurge of SARS-CoV-2 omicron variant infections from December 2022 to January 2023. Clinical data were collected and analyzed by multivariable logistic regression to determine risk factors. High-dimensional flow cytometry analysis was performed to outline the immunological features.

Results

Among 463 infected patients in the eligible cohort (n=613), 65 (14.0%) were hospitalized, 19 (4.1%) suffered severe COVID-19, and 10 (2.2%) died. Older age (OR=1.59/decade, 95% CI 1.18 to 2.16, p=0.003), requiring family oxygen supplement (2.62, 1.11 to 6.19, 0.028), patients with anti-synthetase syndrome (ASyS) (2.88, 1.12 to 7.34, 0.027, vs. other dermatomyositis), higher IIM disease activity, and prednisone intake >10mg/day (5.59, 2.70 to 11.57, <0.001) were associated with a higher risk of hospitalization. Conversely, 3-dose inactivated vaccination reduced the risk of hospitalization (0.10, 0.02 to 0.40, 0.001, vs. incomplete vaccination). Janus kinase inhibitor (JAKi) pre-exposure significantly reduced the risk of severe COVID-19 in hospitalized patients (0.16, 0.04 to 0.74, 0.019, vs. csDMARDs). ASyS patients with severe COVID-19 had significantly reduced peripheral CD4+ T cells, lower CD4/CD8 ratio, and fewer naive B cells but more class-switched memory B cells compared with controls.

Conclusion

ASyS and family oxygen supplement were first identified as risk factors for COVID-19-related hospitalization in patients with IIMs. JAKi pre-exposure might protect IIM patients against severe COVID-19 complications.

Murine models of idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) are divided into polymyositis and dermatomyositis (DM) with specific cutaneous manifestation. Several myositis-specific autoantibodies (MSAs) have been identified in IIMs and were found to be associated with distinct clinical features, including anti-synthetase syndrome (ASyS) and immune-mediated necrotizing myopathy (IMNM). Moreover, MSA-related clinical features have been identified even within DM. Although MSAs are valuable for the diagnosis of IIMs, the pathogenic roles of these antibodies remain unknown. To investigate the pathogenesis of IIMs, classical murine models of autoimmune myositis, experimental autoimmune myositis, and C protein-induced myositis have been established by immunization with muscle-specific antigens, myosin, and myosin-binding skeletal C protein, respectively. To according to MSA-related autoimmunity, a murine model of ASyS was generated by immunization with a murine recombinant histidyl-transfer RNA (tRNA) synthetase, Jo-1, in which muscle and lung inflammation are induced depending on acquired immunity. Furthermore, it was found that the transfer of human Immunoglobulin G (IgGs) from patients with IMNM, comprising anti-signal recognition particles and anti-3-hydroxy-3-methylglutaryl coenzyme A reductase antibodies, induced complement-mediated myositis in recipient mice. We found that CD8+ T cell-mediated myositis can be established depending on autoimmunity against transcriptional intermediary factor 1γ (TIF1γ), an autoantigen for MSAs induced by recombinant human TIF1γ immunization. These new murine models reflecting MSA-associated IIMs will reveal the immunological mechanisms underlying IIMs.

Comprehensive Exploration of Antinuclear Antibodies (ANAs): Unveiling Clinical Significance, Associations with Cancer, and the Nuances of Differential Diagnosis in Positive ANA Patients

This comprehensive review delves into the complex realm of antinuclear antibodies (ANAs), expanding beyond their traditional involvement in autoimmune rheumatic disorders. By digging into historical changes, diagnostic complexity, and clinical significance, the debate reveals the shifting relationships between ANAs, particularly with cancer. Specialized studies provide practical insights on ANA testing processes, standardization, and upcoming challenges. Examining prevalence trends in the United States provides a time dimension to ANA dynamics, linking autoimmune and oncological considerations. The debate delves into the complexity of lupus erythematosus, emphasizing ANAs' diverse presentations and their potential as flexible diagnostic and prognostic indicators. The complex relationship between ANAs and cancer is highlighted, demonstrating their potential as early markers or indicators of malignancies. Looking ahead, this synthesis anticipates advances in personalized medicine and collaborative research, putting ANAs at the forefront of advanced diagnostics and treatments for autoimmune disorders and cancer. This synthesis envisions a future for ANA research in which these antibodies play a critical role in promoting personalized treatment, enhancing diagnostics, and fostering collaborative initiatives that cross traditional boundaries. As ANAs grow more prominent at the junction of autoimmune illnesses and cancer, this synthesis lays the path for further research and novel advances in understanding, diagnosing, and treating complicated medical conditions.

Protein-Protein Interactions of Seryl-tRNA Synthetases with Emphasis on Human Counterparts and Their Connection to Health and Disease

Seryl-tRNA synthetases (SerRSs), members of the aminoacyl-tRNA synthetase family, interact with diverse proteins, enabling SerRSs to enhance their role in the translation of the genetic message or to perform alternative functions in cellular processes beyond translation. Atypical archaeal SerRS interacts with arginyl-tRNA synthetase and proteins of the ribosomal P-stalk to optimize translation through tRNA channeling. The complex between yeast SerRS and peroxin Pex21p provides a connection between translation and peroxisome function. The partnership between Arabidopsis SerRS and BEN1 indicates a link between translation and brassinosteroid metabolism and may be relevant in plant stress response mechanisms. In Drosophila, the unusual heterodimeric mitochondrial SerRS coordinates mitochondrial translation and replication via interaction with LON protease. Evolutionarily conserved interactions of yeast and human SerRSs with m3C32 tRNA methyltransferases indicate coordination between tRNA modification and aminoacylation in the cytosol and mitochondria. Human cytosolic SerRS is a cellular hub protein connecting translation to vascular development, angiogenesis, lipogenesis, and telomere maintenance. When translocated to the nucleus, SerRS acts as a master negative regulator of VEGFA gene expression. SerRS alone or in complex with YY1 and SIRT2 competes with activating transcription factors NFκB1 and c-Myc, resulting in balanced VEGFA expression important for proper vascular development and angiogenesis. In hypoxia, SerRS phosphorylation diminishes its binding to the VEGFA promoter, while the lack of nutrients triggers SerRS glycosylation, reducing its nuclear localization. Additionally, SerRS binds telomeric DNA and cooperates with the shelterin protein POT1 to regulate telomere length and cellular senescence. As an antitumor and antiangiogenic factor, human cytosolic SerRS appears to be a promising drug target and therapeutic agent for treating cancer, cardiovascular diseases, and possibly obesity and aging.

Semi-quantitative thigh magnetic resonance imaging scores in assessing disease activity and determining long-term clinical outcome in idiopathic inflammatory myopathies: a causal mediation analysis

OBJECTIVES

To evaluate the relationship of thigh MRI (t-MRI) with manual muscle testing-8 (MMT-8), muscle enzymes and autoantibodies. To determine the causal and mediating factors resulting in poor recovery of MMT-8 in inflammatory myositis (IIM).

METHODS

This was a single-centre retrospective study in IIM patients. t-MRI was semi-quantitatively scored for muscle oedema, fascial oedema, muscle atrophy and fatty infiltration. Spearman correlation of t-MRI scores was done with muscle enzymes at baseline, and MMT-8 at baseline and on follow-up. Causal mediation analysis was performed with age, sex, symptom duration, autoantibodies, diabetes and BMI as independent variables, follow-up MMT-8 as dependent and t-MRI scores as mediating variables.

RESULTS

Baseline evaluation was done on 59 and follow-up on 38 patients. Median follow-up of the cohort was 31 (10-57) months. Baseline MMT-8 negatively correlated with muscle oedema (r = -0755), fascial oedema (r = -0.443) and muscle atrophy (r = -0.343). Creatinine kinase (r = 0.422) and aspartate transaminase (r = 0.480) positively correlated with muscle oedema. Follow-up MMT-8 correlated negatively with baseline atrophy (r = -0.497) and fatty infiltration (r = -0.531). On follow-up, MMT-8 males had positive total effect (estimate (95%CI)) via atrophy [2.93 (0.44, 4.89)] and fatty infiltration [2.08 (0.54, 3.71)]. Antisynthetase antibody had a positive total effect via fatty infiltration [4.50 (0.37, 7.59)]. Age had a negative total effect via atrophy [-0.09 (0.19, -0.01)] and fatty infiltration [-0.07 (-0.15, -0.01)]. Disease duration had a negative total effect via fatty infiltration [-0.18 (-0.27, -0.02)].

CONCLUSION

Baseline fatty infiltration and muscle atrophy resulting from older age, female sex, longer disease duration and absent anti-synthetase antibodies, partly mediate muscle recovery in IIM.

From Suspected COVID-19 to Anti-synthetase Syndrome: A Diagnostic Challenge in the Pandemic Era

Anti-synthetase syndrome (ASS), a rare immunomediated disease, is characterized by multiple signs and symptoms. Not all patients develop the entire clinical spectrum of the syndrome, as it often varies depending on the involved antibodies. In this case report, a 53-year-old non-smoking woman had complaints of fatigue and dyspnea on exertion for five weeks. The outpatient study revealed creatine kinase (CK) 351U/L, ANAs+, anti-SSa+, normal echocardiogram, and a chest X-ray suggesting imaging suspicion of SARS-CoV-2 pneumonia. Referred to the emergency department, she was hospitalized for bilateral interstitial pneumonia without respiratory failure. Three SARS-CoV-2 polymerase chain reaction tests were negative. She underwent a five-day course of dexamethasone 6mg due to suspected coronavirus disease 2019 (COVID-19) sequelae with favorable progress. About a month later, she experienced fatigue, exertional intolerance, morning cough, and Raynaud's phenomenon episodes. Anti-SARS-CoV-2 antibodies were negative, and a follow-up chest CT showed bilateral organizing pneumonia. Bronchofibroscopy and bronchoalveolar lavage with cytology suggestive of inflammatory appearance, predominantly CD8+ lymphocytes, were performed. Subsequently, positive results for anti-OJ antibodies were obtained. A diagnosis of ASS was established, and prednisolone was initiated at 60mg/day with a tapering regimen, resulting in clinical and radiological improvement. Additional therapy with azathioprine was proposed. This case is presented due to highly suggestive COVID-19 imaging changes, emphasizing the importance of a high suspicion of ASS, despite nearly exclusive pulmonary involvement, with only one isolated elevated CK value and no musculoskeletal complaints. It is also noteworthy for the association with anti-OJ antibodies, rarely identified, often presenting interstitial lung disease as an isolated manifestation.

Emerging Therapeutic Options for Refractory Pulmonary Sarcoidosis: The Evidence and Proposed Mechanisms of Action

Sarcoidosis is a systemic disease with heterogenous clinical phenotypes characterized by non-necrotizing granuloma formation in affected organs. Most disease either remits spontaneously or responds to corticosteroids and second-line disease-modifying therapies. These medications are associated with numerous toxicities that can significantly impact patient quality-of-life and often limit their long-term use. Additionally, a minority of patients experience chronic, progressive disease that proves refractory to standard treatments. To date, there are limited data to guide the selection of alternative third-line medications for these patients. This review will outline the pathobiological rationale behind current and emerging therapeutic agents for refractory or drug-intolerant sarcoidosis and summarize the existing clinical evidence in support of their use.

FARSB Facilitates Hepatocellular Carcinoma Progression by Activating the mTORC1 Signaling Pathway

Hepatocellular carcinoma (HCC) is a common malignant tumor with high mortality. Human phenylalanine tRNA synthetase (PheRS) comprises two α catalytic subunits encoded by the FARSA gene and two β regulatory subunits encoded by the FARSB gene. FARSB is a potential oncogene, but no experimental data show the relationship between FARSB and HCC progression. We found that the high expression of FARSB in liver cancer is closely related to patients' low survival and poor prognosis. In liver cancer cells, the mRNA and protein expression levels of FARSB are increased and promote cell proliferation and migration. Mechanistically, FARSB activates the mTOR complex 1 (mTORC1) signaling pathway by binding to the component Raptor of the mTORC1 complex to play a role in promoting cancer. In addition, we found that FARSB can inhibit erastin-induced ferroptosis by regulating the mTOR signaling pathway, which may be another mechanism by which FARSB promotes HCC progression. In summary, FARSB promotes HCC progression and is associated with the poor prognosis of patients. FARSB is expected to be a biomarker for early screening and treatment of HCC.

Clinical Characteristics of Anti-Synthetase Syndrome and Variables Associated with Interstitial Lung Disease and Mortality: A Retrospective Cohort Study

Anti-synthetase syndrome (ASS) is a rare autoimmune disease. Since the knowledge of ASS remains limited, we conducted the retrospective study aiming to describe clinical characteristics and identify variables associated with interstitial lung disease (ILD) and mortality among patients with ASS. Patients diagnosed with ASS from January 2013 to October 2022 were included. Patient demographics, clinical manifestations, myositis auto-antibody profiles, HRCT findings, and laboratory tests were collected. Variables associated with mortality risk and ILD were evaluated using the Cox proportional hazards model and the logistic regression model, respectively. A total of 82 patients with ASS were included. Clinical manifestations included arthritis (57%), Raynaud's phenomenon (32%), mechanic's hands (29%), fever (26%), and myositis (17%). The myositis auto-antibody profiles included anti-PL-7 (29%), anti-Jo-1 (27%), anti-EJ (17%), anti-PL-12 (16%), and anti-OJ (11%). ILD was observed in 64 patients (78%). Among patients with ILD, 21 initially presented with ILD before developing other ASS clinical manifestations, 29 simultaneously presented with ILD and other symptoms, and 14 had isolated ILD throughout follow-up. Overall, 6 patients presented with rapid-progressive ILD. With a median follow-up time of 2.5 years, mortality was observed in 10 patients (12.2%). Factors associated with mortality included increased lymphocyte counts (adjusted HR, 0.74; 95% CI, 0.61-0.91; p < 0.01), isolated ILD (adjusted HR, 9.59; 95% CI, 1.52-60.61; p = 0.02) and the presence of anti-Ro52 antibodies (adjusted HR, 0.14; 95% CI, 0.02-0.93; p = 0.04). Factors associated with ILD included age (adjusted OR, 1.10; 95% CI, 1.03-1.18; p = 0.01), presence of anti-Ro52 antibodies (adjusted OR, 17.92; 95% CI, 2.13-138.68; p = 0.01), and presence of arthritis (adjusted OR, 0.09; 95% CI, 0.01-0.75; p = 0.03). Our study demonstrated a favorable overall mortality rate among ASS patients.

Molecular Features and Stages of Pulmonary Fibrosis Driven by Type 2 Inflammation

Systemic sclerosis (SSc) is a progressive, multiorgan disease with limited treatment options. Although a recent proof-of-concept study using romilkimab or SAR156597, a bispecific IL-4/IL-13 antibody, suggests a direct role of these cytokines in the pathophysiology of SSc, their contributions to the balance between inflammation and fibrosis are unclear. Here, we determine the roles of type 2 inflammation in fibrogenesis using FRA2-Tg (Fos-related antigen 2-overexpressing transgenic) mice, which develop spontaneous, age-dependent progressive lung fibrosis. We defined the molecular signatures of inflammation and fibrosis at three key stages in disease progression, corresponding to preonset, inflammatory dominant, and fibrosis dominant biology, and revealed an early increase in cytokine-cytokine receptor interactions and antigen-processing and presentation pathways followed by enhanced Th2- and M2 macrophage-driven type 2 responses. This type 2 inflammation progressed to extensive fibrotic pathology by 14-18 weeks of age, with these gene signatures overlapping significantly with those seen in the lungs of patients with SSc with interstitial lung disease (ILD). These changes were also evident in the histopathology, which showed perivascular and peribronchiolar inflammation with prominent eosinophilia and accumulation of profibrotic M2-like macrophages followed by rapid progression to fibrosis with thickened alveolar walls with multifocal fibrotic bands and signs of interstitial pneumonia. Critically, treatment with a bispecific antibody targeting IL-4 and IL-13 during the inflammatory phase abrogated the Th2 and M2 responses and led to near-complete abrogation of lung fibrosis. These data recapitulate important features of fibrotic progression in the lungs of patients with SSc-ILD and enhance our understanding of the progressive pathobiology of SSc. This study also further establishes FRA2-Tg mice as a valuable tool for testing future therapeutic agents in SSc-ILD.

Phenotypic Profiles Among 72 Caucasian and Afro-Caribbean Patients with Antisynthetase Syndrome Involving Anti-PL7 or Anti-PL12 Autoantibodies

OBJECTIVES

Antisynthetase syndrome (ASyS) is a rare autoimmune disease. We aimed to determine clinical, biological, radiological, and evolutive profiles of ASyS patients with anti-PL7 or anti-PL12 autoantibodies.

METHODS

We performed a retrospective study that included adults with overt positivity for anti-PL7/anti-PL12 autoantibodies and at least one Connors' criterion.

RESULTS

Among 72 patients, 69% were women, 29 had anti-PL7 and 43 anti-PL12 autoantibodies, median age was 60.3 years, and median follow-up period was 52.2 months. At diagnosis, 76% of patients had interstitial lung disease, 61% had arthritis, 39% myositis, 25% Raynaud's phenomenon, 18% mechanic's hands, and 17% had fever. The most frequent pattern on initial chest computed tomography was non-specific interstitial pneumonia and 67% had fibrosis at last follow-up. During follow-up, 12 patients had pericardial effusion (18%), 19 had pulmonary hypertension (29%), 9 (12.5%) had neoplasms, and 14 (19%) died. Sixty-seven patients (93%) received at least one steroid or immunosuppressive drug. Patients with anti-PL12 autoantibodies were younger (p=0.01) and more frequently exhibited anti-SSA autoantibodies (p=0.01); patients with anti-PL7 autoantibodies had more severe weakness and higher maximum creatine kinase levels (p=0.03 and 0.04, respectively). Initial severe dyspnoea was more common in patients from the West Indies (p=0.009), with lower predicted values of forced vital capacity, forced expiratory volume in 1s, and total lung capacity (p=0.01, p=0.02, p=0.01, respectively) contributing to a more severe 'respiratory' initial presentation.

CONCLUSIONS

The high mortality and significant numbers of cardiovascular events, neoplasms and lung fibrosis in anti-PL7/12 patients justify close monitoring and question addition of antifibrotic drugs.

Physiological and engineered tRNA aminoacylation

Aminoacyl-tRNA synthetases form the protein family that controls the interpretation of the genetic code, with tRNA aminoacylation being the key chemical step during which an amino acid is assigned to a corresponding sequence of nucleic acids. In consequence, aminoacyl-tRNA synthetases have been studied in their physiological context, in disease states, and as tools for synthetic biology to enable the expansion of the genetic code. Here, we review the fundamentals of aminoacyl-tRNA synthetase biology and classification, with a focus on mammalian cytoplasmic enzymes. We compile evidence that the localization of aminoacyl-tRNA synthetases can be critical in health and disease. In addition, we discuss evidence from synthetic biology which made use of the importance of subcellular localization for efficient manipulation of the protein synthesis machinery. This article is categorized under: RNA Processing Translation > Translation Regulation RNA Processing > tRNA Processing RNA Export and Localization > RNA Localization.

Antisynthetase Syndrome: The Classical Phenotype With a Twist

Antisynthetase syndrome is a systemic autoimmune rheumatic disease characterized by multiple organ involvement, including interstitial lung disease, myositis, non-erosive arthritis, fever, Raynaud's phenomenon, "mechanic's hands," and the presence of autoantibodies against aminoacyl-tRNA synthetases, mainly anti-Jo1 (histidyl) antibodies. Patients with antisynthetase syndrome and active muscle inflammation are usually presented with elevated creatine phosphokinase levels, even in the range of acute rhabdomyolysis. Despite that, the presence of myoglobinuric acute kidney injury is rarely seen in patients with myositis-associated rhabdomyolysis. Herein, we report the case of a 64-year-old man who presented with acute kidney injury due to severe rhabdomyolysis in the setting of antisynthetase syndrome diagnosed by the classical clinical triad of (1) interstitial lung disease, (2) non-erosive arthritis, and (3) active myositis and the presence of anti-Jo1 antibodies. The diagnosis was confirmed by muscle biopsy histological findings as well as electromyography. In this case report, we also discuss the classical clinical manifestations of antisynthetase syndrome and a twist toward this unusual complication associated with active muscle inflammation.

A Case of Antisynthetase Syndrome in the Setting of SARS-Cov-2 Infection

Antisynthetase syndrome is a complex autoimmune disorder, and one of the key criteria for diagnosis is the presence of myositis. Additionally, evidence of interstitial lung disease (ILD) is another important indicator for diagnosis; other clinical features associated with antisynthetase syndrome include arthritis, unexplained and persistent fever, Raynaud's phenomenon, and the presence of mechanic's hands. We report a case of a 36-year-old male who presented to the emergency department with shortness of breath and proximal muscle weakness in the setting of severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection, as his inflammatory markers were elevated and he exhibited features suspicious for antisynthetase syndrome, he was started on methylprednisolone 40 mg intravenously every eight hours, and a myositis panel was checked. In addition, a chest computed tomography (CT) exhibited ground-glass opacities which were compatible with coronavirus disease 2019 (COVID-19). A magnetic resonance image (MRI) of both thighs was done, revealing significant swelling and confirming the suspicion of myositis as his muscle strength in his lower extremities took significant time to improve. As days passed, his muscle strength improved significantly and his creatine phosphatase kinase (CPK) values trended down, indicating that his myositis was improving as well. He was transitioned to oral prednisone 60 mg daily and was discharged home with a rheumatology follow-up to define long-term treatment. A myositis panel revealed anti-glycyl-transferRNA synthetase (EJ) autoantibody positivity and a diagnosis was established. Our case revealed how sometimes laboratory values do not necessarily correlate with disease severity and how we have to do a thorough history of present illness and physical exam to think about unusual diagnoses before putting laboratory data into context.

High expression of TARS is associated with poor prognosis of endometrial cancer

INTRODUCTION

Endometrial cancer is the second largest and most common cancer in the world. It is urgent to explore novel biomarkers.

METHODS

Data were obtained from The Cancer Genome Atlas (TCGA) database. The receiver operating characteristic (ROC) curves, Kaplan-Meier curves and Cox analysis, nomograms, gene set enrichment analysis (GSEA) were conducted. Cell proliferation experiments were performed in Ishikawa cell.

RESULTS

TARS was significantly highly expressed in serous type, G3 grade, and deceased status. Significant association was between high TARS expression with poor overall survival (P = 0.0012) and poor disease specific survival (P = 0.0034). Significant differences were observed in advanced stage, G3 and G4, and old. The stage, diabetes, histologic grade, and TARS expression showed independent prognostic value for overall survival of endometrial cancer. The stage, histologic grade, and TARS expression showed independent prognostic value for disease specific survival of endometrial cancer. Activated CD4⁺ T cell, effector memory CD4⁺ T cell, memory B cell and type 2 T helper cell may participate in the high TARS expression related immune response in endometrial cancer. The CCK-8 results showed significantly inhibited cell proliferation in si-TARS (P < 0.05) and promoted cell proliferation in O-TARS (P < 0.05), confirmed by the colony formation and live/dead staining.

CONCLUSION

High TARS expression was found in endometrial cancer with prognostic and predictive value. This study will provide new biomarker TARS for diagnosis and prognosis of endometrial cancer.

Murine models of idiopathic inflammatory myopathy

Idiopathic inflammatory myopathies (IIMs) are characterized by inflammation of muscles and other organs. Several myositis-specific autoantibodies (MSAs) have been identified in IIMs and were found to be associated with distinct clinical features. Although MSAs are valuable for the diagnosis of IIMs, the pathogenic roles of these antibodies remain unknown. To investigate the pathogenesis of IIMs, several animal models of experimental myositis have been established. Classical murine models of autoimmune myositis, experimental autoimmune myositis, and C protein-induced myositis are established by immunization with muscle-specific antigens, myosin, and skeletal C protein, respectively. Furthermore, a murine model of experimental myositis was generated by immunization with a murine recombinant histidyl-tRNA synthetase, Jo-1, in which muscle and lung inflammation reflecting anti-synthetase syndrome are induced depending on acquired immunity. Recently, the transfer of human IgGs from patients with immune-mediated necrotizing myopathy, comprising anti-signal recognition particles and anti-3-hydroxy-3-methylglutaryl coenzyme A reductase antibodies, was found to induce complement-mediated myositis in recipient mice. CD8⁺ T cell-mediated myositis can be established depending on autoimmunity against transcriptional intermediary factor 1γ (TIF1γ), an autoantigen for MSAs induced by recombinant human TIF1γ immunization. These new murine models reflecting MSA-related IIMs are useful tools for accurately understanding the pathological mechanisms underlying IIMs.

Mechanistic perspectives on anti-aminoacyl-tRNA synthetase syndrome

Antisynthetase syndrome (ASSD) is an autoimmune disease characterized by circulating autoantibodies against one of eight aminoacyl-tRNA synthetases (aaRSs). Although these autoantibodies are believed to play critical roles in ASSD pathogenesis, the nature of their roles remains unclear. Here we describe ASSD pathogenesis and discuss ASSD-linked aaRSs - from the WHEP domain that may impart immunogenicity to the role of tRNA in eliciting the innate immune response and the secretion of aaRSs from cells. Through these explorations, we propose that ASSD pathogenesis involves the tissue-specific secretion of aaRSs and that extracellular tRNAs or tRNA fragments and their ability to engage Toll-like receptor signaling may be important disease factors.

Prognosis of spontaneous pneumomediastinum occurring in dermatomyositis or polymyositis patients with interstitial lung disease according to antimelanoma differentiation-associated gene 5 antibody status: a retrospective cohort study

OBJECTIVES

Spontaneous pneumomediastinum (SPNM) historically has been considered a poor prognostic factor in dermatomyositis/polymyositis patients complicated with interstitial lung disease (ILD). However, there is a lack of actual data regarding the association between SPNM occurrence and mortality in dermatomyositis/polymyositis patients. This study aimed to assess the association between SPNM occurrence and mortality in myositis patients with ILD according to antimelanoma differentiation-associated gene 5 (MDA5) antibody status.

METHODS

Dermatomyositis/polymyositis patients with ILD who were hospitalised at five Japanese hospitals from 2016 to 2020 were included in this retrospective observational study. We collected data about baseline characteristics including myositis-specific autoantibodies, treatments, SPNM and death within 1 year from therapy initiation or strengthening. Baseline characteristics and outcomes were compared between patients with and without SPNM (the SPNM group and the non-SPNM group, respectively).

RESULTS

A total of 119 patients were analysed. SPNM occurred in 23 patients, and 15 patients died. Fifteen patients with SPNM were anti-MDA5 antibody positive. The mortality rate was significantly higher in the SPNM group (34.8%) than in the non-SPNM group (7.3%) (p=0.001). All deaths in the SPNM group occurred in anti-MDA5 antibody-positive patients (8/15), whereas none of the anti-MDA5 antibody-negative patients in the SPNM group died (0/8). In anti-MDA5 antibody-positive patients, the mortality rate was significantly higher in patients with SPNM occurrence (53.3%) than in those without SPNM occurrence (4.0%) (p=0.001).

CONCLUSION

SPNM occurred more frequently in anti-MDA5 antibody-positive than in anti-MDA5 antibody-negative myositis patients. SPNM occurrence was associated with higher mortality risk, especially in anti-MDA5 antibody-positive patients.

Aminoacyl-tRNA synthetases in human health and disease

The Aminoacyl-tRNA Synthetases (aaRSs) are an evolutionarily ancient family of enzymes that catalyze the esterification reaction linking a transfer RNA (tRNA) with its cognate amino acid matching the anticodon triplet of the tRNA. Proper functioning of the aaRSs to create aminoacylated (or “charged”) tRNAs is required for efficient and accurate protein synthesis. Beyond their basic canonical function in protein biosynthesis, aaRSs have a surprisingly diverse array of non-canonical functions that are actively being defined. The human genome contains 37 genes that encode unique aaRS proteins. To date, 56 human genetic diseases caused by damaging variants in aaRS genes have been described: 46 are autosomal recessive biallelic disorders and 10 are autosomal dominant monoallelic disorders. Our appreciation of human diseases caused by damaging genetic variants in the aaRSs has been greatly accelerated by the advent of next-generation sequencing, with 89% of these gene discoveries made since 2010. In addition to these genetic disorders of the aaRSs, anti-synthetase syndrome (ASSD) is a rare autoimmune inflammatory myopathy that involves the production of autoantibodies that disrupt aaRS proteins. This review provides an overview of the basic biology of aaRS proteins and describes the rapidly growing list of human diseases known to be caused by genetic variants or autoimmune targeting that affect both the canonical and non-canonical functions of these essential proteins.