Features of repeated muscle biopsies and phenotypes of monocytes in paired blood samples and clinical long-term response to treatment in patients with idiopathic inflammatory myopathy: a pilot study.

OBJECTIVES: In a pilot study we aimed to identify biomarkers in repeated muscle biopsies and paired blood samples, taken before and after conventional immunosuppressive therapy, in order to predict long-term therapeutic response in patients with idiopathic inflammatory myopathies (IIM). METHODS: Muscle biopsies were selected from 13 new onset patients, six responders and seven non-responders. Repeated muscle biopsies after a median of 11 months follow-up were available from 9 patients and paired peripheral blood mononuclear cells (PBMCs) from 5 patients. Treatment response after 3 years was defined by MMT-8 measuring muscle strength and the ACR/EULAR 2016 improvement criteria. Frozen biopsy sections were immunohistochemically stained for expression of CD3, CD66b, IL-15, CD68, CD163 and myosin heavy chain neonatal (MHCn). PBMCs were analysed by flow cytometry for monocyte phenotypes (CD14, CD16, CD68, CX3CR1, and CCR2). RESULTS: Before treatment there were no significant differences in any clinical or muscle biopsy variables or monocyte subsets between responders and non-responders. MMT-8 was significantly higher compared to baseline in the responders at 3-year follow-up. In responders the expression of CD68 in the repeated biopsies was significantly lower compared to non-responders (p<0.05). CONCLUSIONS: Baseline biopsy, monocyte profile or clinical data did not predict long-term treatment response, but in the repeated biopsy within 1 year of immunosuppressive treatment, the lower number of macrophages (CD68+) seemed to predict a more favourable long-term clinical response with regard to improved muscle strength.

Expression of interleukin-18 in muscle tissue of patients with polymyositis or dermatomyositis and effects of conventional immunosuppressive treatment.

Objectives: To investigate the expression of IL-18 in symptomatic and asymptomatic muscle tissues of patients with PM and DM and the effects of conventional immunosuppressive treatment on such expression. Methods: Two cohorts of patients were included in this study. The first cohort consisted of 10 new-onset myositis patients. IL-18 expression was compared between symptomatic and asymptomatic muscle biopsies that were taken prior to treatment. The second cohort consisted of another 10 patients with repeated muscle biopsies before and after 8 months with conventional immunosuppressive treatment. Using immunohistochemistry, IL-18 expression in muscle tissues was compared before and after treatment. Biopsies from seven healthy individuals were included as controls. Results: IL-18 expression was predominantly localized to inflammatory cells and capillaries in patients and mostly to capillaries in healthy controls. Total IL-18 expression in muscle tissues from the new-onset patients, at both symptomatic and asymptomatic sites, was significantly higher compared with healthy controls (P = 0.007 and P = 0.002) with no statistical difference in appearances between symptomatic and asymptomatic sites. The number of IL-18 positive capillaries was not different among symptomatic, asymptomatic and healthy muscles. Total IL-18 expression appeared lower in biopsies from patients receiving and improving with immunosuppressive treatment, particularly the number of IL-18 positive inflammatory cells but not the number of IL-18 positive capillaries, which was consistent with significantly decreased expression of CD68+ macrophages (P = 0.04). Conclusion: IL-18 is highly expressed in muscle tissue in the context of inflammatory myopathies and based on its plausible effector functions could provide a novel therapeutic target in future.

Expression of High Mobility Group Protein B1 in Cardiac Tissue of Elderly Patients with Coronary Artery Disease with or without Inflammatory Rheumatic Disease.

BACKGROUND: It is known from clinical practice and observational studies that elderly patients with a diagnosis of inflammatory rheumatic diseases (IRD) bear a significantly increased risk for cardiovascular diseases such as coronary artery disease (CAD) and heart failure. The molecular mechanism, however, is still not known. Recently, high mobility group protein B1 (HMGB1), a ubiquitous, highly conserved single polypeptide expressed in all mammal eukaryotic cells, has been identified to mediate myocardial dysfunction in vitro once released from the nuclei of cardiomyocytes. OBJECTIVE: To investigate whether HMGB1 and its receptors are expressed in cardiac muscles of elderly patients with CAD with or without IRD. METHODS: HMGB1 and its 3 well-known receptors, receptor for advanced glycation end products, Toll-like receptor 2 (TLR2), and TLR4, were examined by immunohistochemistry on myocardial biopsy specimens from 18 elderly patients with CAD (10 with IRD, 8 without IRD). Furthermore, total HMGB1 protein levels were measured by Western blot from the cardiac biopsies in 5 patients with and 5 without IRD. RESULTS: Pathologic cytosolic HMGB1 in cardiomyocytes was massively recorded in all patients with IRD, but only slightly expressed in 1 patient without IRD. Total HMGB1 levels were also consistently lower in myocardial muscle biopsies of patients with IRD compared to those without IRD. Furthermore, all 3 HMGB1 receptors were expressed in cardiomyocytes of all patients. CONCLUSION: The increased cytosolic expression of HMGB1 in cardiomyocytes and the lower total amount of HMGB1 in the cardiac specimens of IRD patients is consistent with a greater release of HMGB1 from the myocardial nuclei in IRD than non-IRD individuals. Thus, the HMGB1 signaling pathways may be more easily activated in elderly CAD patients with concomitant IRD and trigger a detrimental inflammatory process causing severe cardiovascular problems. Therefore, targeting HMGB1 in IRD patients might reduce the risk for cardiovascular events.