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

Abstract

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.

• Authors: Sevim Barbasso Helmers, Mei Bruton, Ingela Loell, Ann-Kristin Ulfgren, Alastair J Gracie, Iain B McInnes, Ingrid E Lundberg
• Journal: Rheumatology (Oxford, England) (Rheumatology (Oxford)) Vol. 57 Issue 12 Pg. 2149-2157 (12 01 2018) ISSN: 1462-0332 [Electronic] England
• PMID: 30102381 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• IL18 protein, human
• Immunosuppressive Agents
• Interleukin-18

Topics

• Adult
• Aged
• Biopsy
• Cohort Studies
• Dermatomyositis (drug therapy, metabolism)
• Female
• Humans
• Immunosuppressive Agents (therapeutic use)
• Interleukin-18 (metabolism)
• Male
• Middle Aged
• Muscle, Skeletal (metabolism)
• Polymyositis (drug therapy, metabolism)
• Treatment Outcome