Article Text
PDF
Abstract
Objectives Hypocomplementaemia is common in patients with IgG4-related disease (IgG4-RD). We aimed to determine the IgG4-RD features associated with hypocomplementaemia and investigate mechanisms of complement activation in this disease.
Methods We performed a single-centre cross-sectional study of 279 patients who fulfilled the IgG4-RD classification criteria, using unadjusted and multivariable-adjusted logistic regression to identify factors associated with hypocomplementaemia.
Results Hypocomplementaemia was observed in 90 (32%) patients. In the unadjusted model, the number of organs involved (OR 1.42, 95% CI 1.23 to 1.63) and involvement of the lymph nodes (OR 3.87, 95% CI 2.19 to 6.86), lungs (OR 3.81, 95% CI 2.10 to 6.89), pancreas (OR 1.66, 95% CI 1.001 to 2.76), liver (OR 2.73, 95% CI 1.17 to 6.36) and kidneys (OR 2.48, 95% CI 1.47 to 4.18) were each associated with hypocomplementaemia. After adjusting for age, sex and number of organs involved, only lymph node (OR 2.59, 95% CI 1.36 to 4.91) and lung (OR 2.56, 95% CI 1.35 to 4.89) involvement remained associated with hypocomplementaemia while the association with renal involvement was attenuated (OR 1.6, 95% CI 0.92 to 2.98). Fibrotic disease manifestations (OR 0.43, 95% CI 0.21 to 0.87) and lacrimal gland involvement (OR 0.53, 95% CI 0.28 to 0.999) were inversely associated with hypocomplementaemia in the adjusted analysis. Hypocomplementaemia was associated with higher concentrations of all IgG subclasses and IgE (all p<0.05). After adjusting for serum IgG1 and IgG3, only IgG1 but not IgG4 remained strongly associated with hypocomplementaemia.
Conclusions Hypocomplementaemia in IgG4-RD is not unique to patients with renal involvement and may reflect the extent of disease. IgG1 independently correlates with hypocomplementaemia in IgG4-RD, but IgG4 does not. Complement activation is likely involved in IgG4-RD pathophysiology.
- Autoimmune Diseases
- Vasculitis
- Risk Factors
- Immune Complex Diseases
Data availability statement
Data are available on reasonable request. Deidentified participant data can be made available on reasonable request. Please contact JHS (jhstone@mgh.harvard.edu) or GK (gkatz@mgh.harvard.edu) with data sharing requests.
Statistics from Altmetric.com
Data availability statement
Data are available on reasonable request. Deidentified participant data can be made available on reasonable request. Please contact JHS (jhstone@mgh.harvard.edu) or GK (gkatz@mgh.harvard.edu) with data sharing requests.
Footnotes
Handling editor Josef S Smolen
X @GuyKatzMD, @zach_wallace_md, @alhkim
Contributors GK, CP, ZSW, TG, JPA, AHK and JHS contributed to the study design and acquisition, analysis or interpretation of data. BJ, GAM, IJ, YZ, HL, ADF and SSP contributed to data acquisition, analysis and interpretation. All authors contributed to manuscript preparation or revision and approved the final version prior to publication. All authors agreed to be accountable for all aspects of the work. GK and JHS are co-corresponding authors on this work, and GK is the guarantor of this work.
Funding This study was funded by National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) (K08 AR079615). Rheumatology Research Foundation (998547). National Institutes of Health/National Institute of Allergy and Infectious Diseases (NIH/NIAID(UM1AI144295). Autoimmunity Center of Excellence.
Competing interests The authors declare competing interests with the Rheumatology Research Foundation, NIH, Sanofi, Zenas, Amgen, Genentech, Sana, National Multiple Sclerosis Society, GlaxoSmithKline, Helmsley Charitable Trust, AstraZeneca, Bristol Myers Squibb, Novartis, Alexion Pharmaceuticals, ANI Pharmaceuticals, Aurinia Pharmaceuticals, Exagen Diagnostics, Kypha, Pfizer, UpToDate, The Rheumatology Education Group, Lupus Foundation of America-Heartland Chapter, St Louis Rheumatology Chapter, Lupus Research Alliance, National Scleroderma Foundation, AbbVie, Acepodia, Alpine Immune Sciences, Argenx, Connect Biopharma, CTI BioPharma, Horizon Therapeutics, iCell Gene Therapeutics, IQVIA, Prometheus Biosciences/Merck, Q32 Bio, Salvina Therapeutics, IgG4ward! Foundation, Achillion Pharmaceuticals, Annexon Pharmaceuticals, Arrowhead Pharmaceuticals, Autobahn Therapeutics, Avidity Partners, BioMarin Pharmaceuticals, Broadwing Bio, Celldex Therapeutics, 4D Molecular Therapeutics, HiBIO, Janssen, Kypha, Merck KGaA, Takeda Pharmaceuticals, Compliment Corporation, Gemini Therapeutics, Leducq Foundation, Be Bio Pharma, Paratus, Octagon Therapeutics, Ab Pro, Viela Bio, MedPace and BioCryst.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.
Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.