Polymyositis-dermatomyositis and infections
ABSTRACT In genetically predisposed individuals, viruses, bacteria, or parasitic infectious agents are suspected to induce autoimmunity and/or to exacerbate the disease once the self-tolerance is broken. Although direct evidence for this association is still lacking, numerous data from animal models as well as from humans support the hypothesis of a direct contribution of pathogens to the induction of several autoimmune diseases. This review focused on the possible role of infectious agents as triggers of autoimmunity in polymyositis (PM) and dermatomyositis (DM). Epidemiological studies, clinical and experimental findings that support the hypothesis of infection-induced PM and DM are summarized and discussed. In addition, immune response abnormalities and immunosuppressive medications may be responsible for the high percentage of infectious complications in PM and DM patients. In this review, the increased risk of developing infections in these patients is also underlined and published data are reported.
- SourceAvailable from: Marcelo Heron Petri[Show abstract] [Hide abstract]
ABSTRACT: Myositis specific autoantibodies are associated with unique clinical subsets and are useful biomarkers in polymyositis/dermatomyositis (PM/DM). A 120 kD protein recognized by certain patients with DM was identified and clinical features of patients with this specificity were characterized. The 120 kD protein recognized by a prototype serum was purified and identified by mass spectrometry and immunological methods. Autoantibody to this 120 kD protein was screened in sera from 2,356 patients with various diagnoses from four countries, including 254 PM/DM, by immunoprecipitation of 35S-methionine labeled K562 cell extracts. Clinical information of patients with this specificity was collected. The 120 kD protein, which exactly comigrated with PL-12, was identified as transcription intermediary factor TIF1β (TRIM28) by mass spectrometry and validated by immunoassays. By immunofluorescence, anti-TIF1β positivity showed a fine-speckled nuclear staining pattern. Four cases of anti-TIF1β were identified; all are women, one each in a Japanese, African American, Caucasian, and Mexican individual. Three had a diagnosis of DM and one case was classified as having an undifferentiated connective tissue disease with an elevated CPK but without significant muscle symptoms. This individual also had a history of colon cancer, cervical squamous metaplasia and fibroid tumors of the uterus. Myopathy was mild in all cases and resolved without treatment in one case. The anti-TIF1β specificity was not found in other conditions. Anti-TIF1β is a new DM autoantibody associated with a mild form of myopathy. Whether it has an association with malignancy, as in the case of anti-TIF1γ, or other unique features will need to be evaluated in future studies.Arthritis research & therapy 04/2012; 14(2):R79. DOI:10.1186/ar3802 · 4.12 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Autophagy has a large range of physiological functions and its dysregulation contributes to several human disorders, including autoinflammatory/autoimmune diseases such as inflammatory myopathies (IIMs). In order to better understand the pathogenetic mechanisms of these muscular disorders, we sought to define the role of autophagic processes and their relation with the innate immune system in the three main subtypes of IIM, specifically sporadic inclusion body myositis (sIBM), polymyositis (PM), dermatomyositis (DM) and juvenile dermatomyositis (JDM). We found that although the mRNA transcript levels of the autophagy-related genes BECN1, ATG5 and FBXO32 were similar in IIM and controls, autophagy activation in all IIM subgroups was suggested by immunoblotting results and confirmed by immunofluorescence. TLR4 and TLR3, two potent inducers of autophagy, were highly increased in IIM, with TLR4 transcripts significantly more expressed in PM and DM than in JDM, sIBM and controls, and TLR3 transcripts highly up-regulated in all IIM subgroups compared to controls. Co-localization between autophagic marker, LC3, and TLR4 and TLR3 was observed not only in sIBM but also in PM, DM and JDM muscle tissues. Furthermore, a highly association with the autophagic processes was observed in all IIM subgroups also for some TLR4 ligands, endogenous and bacterial HSP60, other than the high-mobility group box 1 (HMGB1). These findings indicate that autophagic processes are active not only in sIBM but also in PM, DM and JDM, probably in response to an exogenous or endogenous 'danger signal'. However, autophagic activation and regulation, and also interaction with the innate immune system, differ in each type of IIM. Better understanding of these differences may lead to new therapies for the different IIM types.PLoS ONE 11/2014; 9(11):e111490. DOI:10.1371/journal.pone.0111490 · 3.53 Impact Factor
- La Presse Médicale 02/2009; 38(2):303-316. DOI:10.1016/j.lpm.2008.09.021 · 1.17 Impact Factor