Sporadic inclusion body myositis and primary Sjogren's syndrome: an overlooked diagnosis

The Spectrum of Extraglandular Manifestations in Primary Sjögren's Syndrome

Extraglandular manifestations (EGMs) in primary Sjogren's syndrome (pSS) represent the clinical expression of the systemic involvement in this disease. EGMs are characterized by a wide heterogeneity; virtually any organ or system can be affected, with various degrees of dysfunction. The existing gaps of knowledge in this complex domain of extraglandular extension in pSS need to be overcome in order to increase the diagnostic accuracy of EGMs in pSS. The timely identification of EGMs, as early as from subclinical stages, can be facilitated using highly specific biomarkers, thus preventing decompensated disease and severe complications. To date, there is no general consensus on the diagnostic criteria for the wide range of extraglandular involvement in pSS, which associates important underdiagnosing of EGMs, subsequent undertreatment and progression to severe organ dysfunction in these patients. This review article presents the most recent basic and clinical science research conducted to investigate pathogenic mechanisms leading to EGMs in pSS patients. In addition, it presents the current diagnostic and treatment recommendations and the trends for future therapeutic strategies based on personalized treatment, as well as the latest research in the field of diagnostic and prognostic biomarkers for extraglandular involvement in pSS.

Combination of sporadic inclusion body myositis and primary Sjцgren’s syndrome: clinical case and review of literature

The article presents a review of the literature and a clinical observation of a patient with long-term anamnesis of primary Sjцgren's syndrome (SS) in combination with sporadic inclusion body myositis (sIBM). The diagnosis of SS was confirmed in accordance with the Russian diagnostic criteria for SS 2001, as well as with the ACR 2012 and ACR/EULAR 2016 criteria. The diagnosis of sIBM was established on the basis of a characteristic clinical picture: the development of the disease in a woman after 50 years of age with slowly progressive asymmetric muscle weakness and a typical distribution, a moderate increase in the level of creatine phosphokinase (<10 norms for the entire observation period), the presence of a generalized primary muscle process according to needle electromyography, a typical picture of muscle involvement according to magnetic resonance imaging, and the ineffectiveness of high doses of glucocorticoids. The absence of histological confirmation does not contradict the diagnosis, since morphological examination of muscles in patients with a typical course of the disease fails to detect characteristic signs of sIBM in 20% of cases.Currently, there is no effective pathogenetic therapy for sIBM. Understanding the mechanisms of sIBM development will allow to develop effective methods of its treatment.

Anti-Valosin-Containing Protein (VCP/p97) Autoantibodies in Inclusion Body Myositis and Other Inflammatory Myopathies

OBJECTIVE

The rationale for this study was based on reports that valosin-containing protein (VCP) mutations are found in hereditary inclusion body myositis (IBM) and VCP was detected in rimmed vacuoles of sporadic IBM (sIBM) muscle biopsies. Autoantibodies to VCP have not been reported in sIBM or other inflammatory myopathies (IIMs). The aim of this study was to determine the frequency and clinical significance of anti-VCP antibodies in sIBM and other IIMs.

METHODS

Sera were collected from 73 patients with sIBM and 383 comparators or controls, including patients with IIM (n = 69), those with juvenile dermatomyositis (JDM) (n = 67), those with juvenile idiopathic arthritis (JIA) (n = 47), those with primary biliary cholangitis (PBC) (n = 105), controls that were age matched to patients with sIBM (similarly aged controls [SACs]) (n = 63), and healthy controls (HCs) (n = 32). Immunoglobulin G antibodies to VCP were detected by addressable laser bead immunoassay using a full-length recombinant human protein.

RESULTS

Among patients with sIBM, 26.0% (19/73) were positive for anti-VCP. The frequency in disease controls was 15.0% (48/320). Among SACs, the frequency was 1.6% (1/63), and in HCs 0% (0/32). Frequencies were 17.5% (11/63) for IIM, 25.7% (27/105) for PBC, 3.0% (2/67) for JDM, and 17.0% (8/47) for JIA. The sensitivity, specificity, positive predictive value, and negative predictive value of anti-VCP for sIBM were 26.0%, 87.2%, 28.4%, and 85.9%, respectively. Of patients with sIBM, 15.1% (11/73) were positive for both anti-VCP and anti-cytosolic 5'-nucleotidase 1A (NT5c1A). Eleven percent of patients (8/73) were positive for anti-VCP, but negative for anti-NT5c1A.

CONCLUSION

Anti-VCP has low sensitivity and moderate specificity for sIBM but may help fill the seronegative gap in sIBM. Further studies are needed to determine whether anti-VCP is a biomarker for a clinical phenotype that may have clinical value.

Biomarker und Histologie bei idiopathischen inflammatorischen Myopathien

Die idiopathischen inflammatorischen Myopathien (IIM) sind eine Gruppe entzündlicher Muskelerkrankungen für deren Diagnosestellung, Verlaufsbeurteilung, Prognoseabschätzung und Risikostratifizierung Biomarker eine jeweils essentielle Rolle spielen. Biomarker in diesem Kontext können sowohl „herkömmliche“ serologische Marker wie Muskelenzyme oder Autoantikörper, histologische Marker wie entitätsspezifische inflammatorische Muster, aber auch genomische und genetische Marker sein. Der vorliegende Artikel gibt einen Überblick über bewährte und innovative Marker.