Abstract
BackgroundImmunoglobulin G4-related disease (IgG4-RD) is a newly recognized systemic, immune-mediated, and fibro-inflammatory disease. Hypocomplementemia was found in part of IgG4-RD patients especially in the setting of active disease.ObjectivesThis study aimed to clarify the clinical features, treatment efficacy, and outcome in IgG4-RD patients with hypocomplementemia.Methods312 IgG4-RD patients were recruited in our prospective cohort conducted in Peking Union Medical College Hospital. Patients were divided into hypocomplementemia group and normal complement group according to serum C3 and C4 levels measured at baseline before treatment. Low serum C3 levels (< 0.73 g/L) and/or C4 levels (< 0.10 g/L) were defined as hypocomplementemia. Demographic data, clinical characteristics, laboratory parameters, treatment, and outcome of two groups were analyzed and compared.ResultsHypocomplementemia was identified in 65 (20.8%) cases of untreated IgG4-RD patients at baseline. The average age of hypocomplementemia group was 55.85 ± 10.89 years, with male predominance (72.3%). Compared with normal complement group, patients with hypocomplementemia were likely to have more involved organs, higher IgG4-RD responder index (IgG4-RD RI), and higher laboratory parameters such as counts of eosinophils, inflammatory markers, immunoglobulin G (IgG), IgG1, IgG3, IgG4, and IgE. In addition, lymph nodes, lacrimal gland, submandibular gland, parotid gland, paranasal sinus, bile ducts, and prostate gland were more commonly affected (p < 0.05). Serum C3 and C4 showed a significant positively correlation with each other. Both C3 and C4 were negatively correlated with the number of involved organs, IgG, IgG3, IgG4, and IgG4-RD RI, as well as positively correlated with IgA and hypersensitive C reactive protein (hsCRP). 64 (98.5%) patients responded quickly to initial therapy at a 3-month follow-up. Fifteen (23.1%) patients relapsed during follow-up with mean recurrence time of 14.2 ± 13.8 months. Compared with normal complement group, there was no significant difference of relapse rate in two groups (P = 0.401).ConclusionsClinical characteristics of IgG4-related disease with hypocomplementemia differ from normal complement group. Serum C3 and C4 at baseline before treatment could be biological markers for disease activity. IgG4-RD with hypocomplementemia responded well to treatment and had no significant difference of relapse rate in IgG4-RD with normal complement.
Highlights
Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized multi-organ, immune-mediated, and fibro-inflammatory disease with pathologically characterized by IgG4-positive lymphoplasmacytic infiltration, storiform-fibrosis, and obliterative phlebitis
Clinical characteristics of IgG4-related disease with hypocomplementemia differ from normal complement group
Patient enrollment In our prospective cohort of IgG4-RD carried out in the Peking Union Medical College Hospital, 312 newly diagnosed patients were enrolled from January 2014 to January 2019, who fulfilled the 2011 comprehensive diagnostic criteria [9, 10], had complement tested at baseline, and had been followed up for more than 6 months
Summary
Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized multi-organ, immune-mediated, and fibro-inflammatory disease with pathologically characterized by IgG4-positive lymphoplasmacytic infiltration, storiform-fibrosis, and obliterative phlebitis. Complement is one of the first lines of defense against infections by promoting inflammation and orchestrating opsonization of pathological material, and other critical roles including disposal of immune complexes and apoptotic cellular debris [3]. It serves as a functional bridge between the innate and adaptive immune systems by enhancing antibody responses and regulating B and T cells activation, playing important roles in the development of numerous inflammatory diseases [3,4,5]. Hypocomplementemia was found in part of IgG4-RD patients especially in the setting of active disease
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