Volume 98, Issue 1 pp. 12-21
Outstanding Observation

Systems immunology reveals a linked IgG3–C4 response in patients with acute rheumatic fever

Amy W Chung

Amy W Chung

Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia

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Timothy KC Ho

Timothy KC Ho

School of Medical Sciences, University of Auckland, Auckland, New Zealand

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Paulina Hanson-Manful

Paulina Hanson-Manful

School of Medical Sciences, University of Auckland, Auckland, New Zealand

Maurice Wilkins Centre for Biodiscovery, University of Auckland, Auckland, New Zealand

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Susanne Tritscheller

Susanne Tritscheller

School of Medical Sciences, University of Auckland, Auckland, New Zealand

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Jeremy M Raynes

Jeremy M Raynes

School of Medical Sciences, University of Auckland, Auckland, New Zealand

Maurice Wilkins Centre for Biodiscovery, University of Auckland, Auckland, New Zealand

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Alana L Whitcombe

Alana L Whitcombe

School of Medical Sciences, University of Auckland, Auckland, New Zealand

Maurice Wilkins Centre for Biodiscovery, University of Auckland, Auckland, New Zealand

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Mei Lin Tay

Mei Lin Tay

School of Medical Sciences, University of Auckland, Auckland, New Zealand

Maurice Wilkins Centre for Biodiscovery, University of Auckland, Auckland, New Zealand

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Reuben McGregor

Reuben McGregor

School of Medical Sciences, University of Auckland, Auckland, New Zealand

Maurice Wilkins Centre for Biodiscovery, University of Auckland, Auckland, New Zealand

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Natalie Lorenz

Natalie Lorenz

School of Medical Sciences, University of Auckland, Auckland, New Zealand

Maurice Wilkins Centre for Biodiscovery, University of Auckland, Auckland, New Zealand

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Jane R Oliver

Jane R Oliver

Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia

University of Otago, Wellington, New Zealand

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Jason K Gurney

Jason K Gurney

University of Otago, Wellington, New Zealand

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Cristin G Print

Cristin G Print

School of Medical Sciences, University of Auckland, Auckland, New Zealand

Maurice Wilkins Centre for Biodiscovery, University of Auckland, Auckland, New Zealand

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Nigel J Wilson

Nigel J Wilson

Starship Children's Hospital, Auckland, New Zealand

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William J Martin

William J Martin

Science for Technological Innovation Science Challenge, Callaghan Innovation, Wellington, New Zealand

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Deborah A Williamson

Deborah A Williamson

Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia

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Michael G Baker

Michael G Baker

University of Otago, Wellington, New Zealand

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Nicole J Moreland

Corresponding Author

Nicole J Moreland

School of Medical Sciences, University of Auckland, Auckland, New Zealand

Maurice Wilkins Centre for Biodiscovery, University of Auckland, Auckland, New Zealand

Correspondence

Nicole J Moreland, School of Medical Sciences, University of Auckland, 85 Park Road, Grafton 1023, Auckland, New Zealand.

E-mail: [email protected]

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First published: 18 November 2019
Citations: 15

Abstract

Acute rheumatic fever (ARF) and chronic rheumatic heart disease (RHD) are autoimmune sequelae of a Group A streptococcal infection with significant global mortality and poorly understood pathogenesis. Immunoglobulin and complement deposition were observed in ARF/RHD valve tissue over 50 years ago, yet contemporary investigations have been lacking. This study applied systems immunology to investigate the relationships between the complement system and immunoglobulin in ARF. Patients were stratified by C-reactive protein (CRP) concentration into high (≥10 μg mL−1) and low (<10 μg mL−1) groups to distinguish those with clinically significant inflammatory processes from those with abating inflammation. The circulating concentrations of 17 complement factors and six immunoglobulin isotypes and subclasses were measured in ARF patients and highly matched healthy controls using multiplex bead-based immunoassays. An integrative statistical approach combining feature selection and principal component analysis revealed a linked IgG3–C4 response in ARF patients with high CRP that was absent in controls. Strikingly, both IgG3 and C4 were elevated above clinical reference ranges, suggesting these features are a marker of ARF-associated inflammation. Humoral immunity in response to M protein, an antigen implicated in ARF pathogenesis, was completely polarized to IgG3 in the patient group. Furthermore, the anti-M-protein IgG3 response was correlated with circulating IgG3 concentration, highlighting a potential role for this potent immunoglobulin subclass in disease. In conclusion, a linked IgG3–C4 response appears important in the initial, inflammatory stage of ARF and may have immediate utility as a clinical biomarker given the lack of specific diagnostic tests currently available.

Video Short

Systems immunology reveals a linked IgG3–C4 response in patients with acute rheumatic fever

by Chung et al.

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