Contributed to the conception and design of the study, carried out the statistics and participated in analysis and interpretation of data. MSAs and JDTic MAAs concerning to their geographical location and the possible connection with UV radiation. We collected the prevalence data of fifteen MSA and thirteen MAA from 22 countries around the world and we were able to observe a difference in prevalence between countries and continents. We found variations in anti-PL7, anti-Ro52, anti-La and anti-Ku prevalence relating to UV radiation level. Otherwise, we JDTic observed that anti-Mi-2 prevalence raises near to the Equator in the mean time anti-MJ/NXP2 and anti-ARS prevalence experienced an reverse behavior increasing their prevalence in the geographical locations farther to the Equator. Our results highlighted the importance to include the UV radiation and additional environmental factors in IIM studies, in order to clarify its association with MSA and MAA prevalence as well as its possible part in the immunopathogenesis of these diseases. Keywords: idiopathic inflammatory myopathies (IIM), autoantibodies, prevalence, latitude, UV radiation Intro The idiopathic inflammatory myopathies (IIM), also known as myositis, represent a heterogeneous group of autoimmune rheumatic diseases. The main features are muscle mass weakness, multiorgan involvement including skin, bones, lungs, heart and gastrointestinal tract, as well as malignancy development (1, 2). One of the more recent classification criteria of myositis, is the Classification Criteria for Adult and Juvenile Idiopathic Inflammatory Myopathies founded by the Western Little league Against Rheumatism/American College of Rheumatology (EULAR/ACR) in 2017. Relating to this, the myositis subgroups encompass dermatomyositis (DM), amyopathic dermatomyositis (ADM), juvenile dermatomyositis (JDM), polymyositis (PM), inclusion body myositis (IBM), immune-mediated necrotizing myopathy (IMNM) and juvenile myositis (JM) (3). These subgroups differ in age, medical manifestations and histopathological features. IIM are associated with the presence of myositis specific antibodies (MSA) and myositis connected antibodies (MAA) ( Number 1 ) (4). Open in a separate window Number 1 Subgroups of IIM relating to autoantibody phenotype. Not all autoantibodies are special for the myopathy subgroup, as is the case of anti-Signal Acknowledgement Particle (SRP) that might be found in polymyositis (PM) and immune-mediated necrotizing myopathy (IMNM). Notwithstanding, anti-hydroxymethylglutaryl coenzyme A reductase (HMGCR) is definitely classically observed in IMNM. The anti-aminoacyl tRNA synthetase (ARS) autoantibodies are related to JDTic anti-synthetase syndrome (ASSD). Inclusion body myositis (IBM) is definitely associated but not special for anti-cytosolic 5nucleotidase 1A (cN1A). Dermatomyositis (DM) is definitely associated to malignancy development in positive individuals for anti-Transcription Intermediary Element 1/ (TIF1/). Anti-Mi-2, Nuclear Matrix Protein 2 (NXP2) and anti-Small ubiquitin-like modifier Activating Enzyme (SAE) will also be related to DM. The presence of anti-Melanoma Differentiation-Associate Gene 5 (MDA5) is definitely associated with rapidly progressive interstitial lung disease (RPILD) in amyopathic dermatomyositis (ADM). Environment and genetics might be involved in myositis pathogenesis. UV radiation has been identified as a risk element for DM development (5). The geographic distribution of JDTic MSA for Mi-2 and its association with UV radiation and proximity to the equator area is definitely observed Rabbit Polyclonal to RPC8 (6C9). UV like a Triggering Element for Autoimmunity in Dermatomyositis UV light is definitely classified relating to wavelength into UVA (315 C JDTic 400 nm), UVB (280 C 315 nm) and UVC (200 C 280 nm). In the case of UVB, it does not penetrate deeper than epidermis and is strongly soaked up by DNA and proteins, therefore it is an inducer of DNA damage of keratinocyte resulting in apoptosis and antigen re-localization (10, 11). Additional important aspect of UVB radiation, is definitely that promotes the manifestation of adhesion molecules as well as keratinocyte activation to produce IL-1, IL-6, IL-8, IL-10, GM-CSF, TNF- and IFN-I (12, 13). These cytokines might influence the type I IFN signature in IIM through the myocytes overexpression of MHC class I molecules as well as B cell activating element belonging to the TNF family (BAFF) activation (14). Prevalence of Anti-Mi-2, UV Radiation and Geographical Distribution Anti-Mi-2 is an autoantibody mostly present in DM. Mi-2 antigen offers two acknowledged isoforms named as alpha and beta; encoded from the chromodomain helicase DNA binding protein 3 (value lower than 0.05.