Autoantibodies Against Albumin in Patients With Systemic Lupus Erythematosus

Abstract

Objectives: Autoantibodies and aberrant immune complexes are pathological hallmarks of systemic lupus erythematosus (SLE). This study aimed to determine the occurrence of IgG autoantibodies against human serum albumin (anti-HSA IgG) and their potential association with antibodies against bovine serum albumin (anti-BSA IgG) in patients with SLE.Methods: Sera of 180 SLE patients included to the Swiss SLE Cohort Study and 188 age- and sex-matched healthy controls were evaluated. Levels of anti-HSA IgG and anti-BSA IgG were quantified by ELISA. Selected samples were further characterized using serum fractions obtained by fast liquid chromatography (FPLC).Results: SLE patients had increased levels of anti-HSA IgG (p = 0.002) but similar levels of anti-BSA IgG compared to matched healthy controls. Anti-HSA IgG levels correlated with the SLE Disease Activity Index (SLEDAI), which was more pronounced in patients with an physician's global assessment (PGA) of ≥ 1 (r = 0.309, p = 0.0066). Anti-HSA IgG was partially complexed with serum albumin but also occurred as monomeric autoantibodies in highly positive SLE patients. A positive correlation between anti-HSA IgG and anti-BSA IgG was found that was stronger in SLE patients than in healthy controls (r = 0.3172, p < 0.001 vs. r = 0.2122, p < 0.0035). Binding of anti-BSA IgG was inhibited partially in the presence of HSA in samples with double positivity for anti-HSA and anti-BSA (median inhibition 47.9%, range 0.9–100%) and vice versa.Conclusion: In SLE patients there is an increased prevalence of anti-HSA IgG antibodies that are associated with SLE disease activity.

Discovery of Novel Circulating Immune Complexes in Lupus Nephritis Using Immunoproteomics

“…To confirm this, we performed a bioinformatics analysis to determine which proteins may be involved in the disease course of SLE or LN and may potentially serve as a disease biomarker. As shown in Supplementary Table 1 and Supplementary Table 2 , among the 77 proteins, 32 of them are highly abundant proteins including keratins, histones, complement system proteins, and albumin and immunoglobulin family proteins which have already been discussed extensively in previous studies ( 32 – 36 ). Therefore, they were eliminated from further analysis in the current study.…”

Use of Physician Global Assessment (PGA) in Systemic lupus erythematosus: a systematic review of its psychometric properties

“…Supporting the face validity property, PGA was defined “gold-standard” in 11 studies (2, 10-11, 21, 32, 49, 67, 76, 78, 84, 88) and in 32 it was used as the reference to which other activity scores were compared, such as the SLEDAI (4, 10, 13, 25, 27-28, 31, 33, 35-36, 41, 46-47, 50-51, 53, 62, 65, 68, 72-73, 76, 81, 96-99), BILAG (4, 27, 35-36, 46, 65, 72-73, 81, 98), SLAM (4, 72, 76, 99), LAI (68, 88), patient global assessment (ptGA) (81, 83-84) and ECLAM (35). However, it was used as a single outcome measure only in two studies (49, 100) whilst in the majority the PGA was scored together with another instrument (typically the SLEDAI) (2, 9, 11-12, 21, 24, 30, 32, 34, 37-40, 44-45, 48-49, 55, 58-59, 61, 63-64, 66-67, 74-75, 80, 82, 86, 89-95, 103).…”

“…In one open-label study (43) the decrease in PGA score was considered the primary endpoint. In 32 studies, disease activity measured by PGA was compared to changes in laboratory markers, with the aim to correlate clinical and serological features (9, 21, 30, 32, 34, 37-39, 44-45, 48-49, 55, 58-61, 63-64, 66-67, 69, 71, 74-75, 82, 86, 89, 91-94).…”

MHC haplotype and B cell autoimmunity: Correlation with pathogenic IgG autoantibody subclasses and Fc glycosylation patterns

“…The expression of an MHC haplotype that is not associated with the development of the autoimmune disease may not necessarily prevent the production of IgG autoantibodies, but the expression of a disease‐prone MHC haplotype seems to be associated with the induction of pro‐inflammatory IgG Fc N‐glycosylation and highly pathogenic IgG autoantibodies [12]. In this context, it is interesting that various IgG autoantibodies are found in the peripheral blood of a considerable number of healthy individuals [35–37]. In some cases, these individuals may develop autoimmune diseases later [38].…”

“…In this context, it is interesting that various IgG autoantibodies are found in the peripheral blood of a considerable number of healthy individuals [35][36][37]. In some cases, these individuals may develop autoimmune diseases later [38].…”