Level and avidity of antineutrophil cytoplasmic antibodies specific to lactoferrin are useful biomarkers in systemic lupus erythematosus

OBJECTIVES

To evaluate specificity, level, and avidity of antineutrophil cytoplasmic antibodies (ANCA) in systemic lupus erythematosus (SLE). There are no studies of ANCA avidity in SLE.

METHODS

Level (ELISA) and avidity (ELISA) of myeloperoxidase (MPO-), proteinase 3 (PR3-), lactoferrin (LF-), cathepsin G, elastase (EL-), and bactericidal/permeability increasing protein (BPI)-ANCA in 142 SLE patients were studied. SLE activity was measured by SLEDAI-2 K. 25/40 ANCA-positive patients were immunoserologically followed (12 ± 2 months).

RESULTS

40/142 (28.2%) SLE patients were ANCA-positive: LF- (21/40), MPO- (19/40), EL- (6/40), PR3- (3/40), and BPI-ANCA (1/40). Only LF-ANCA were associated with renal manifestations (p < 0.05), and positive predictive value for renal involvement in ANCA-positive SLE was 76.2%. LF-ANCA-positive patients had higher SLEDAI-2 K (p < 0.05) and more frequently had anti-dsDNA (p < 0.05), low C3 (p < 0.001), and low C4 (p < 0.05) than LF-ANCA-negative patients. LF-ANCA level was in a positive correlation with SLEDAI-2 K, anti-dsDNA, and anti-C1q (p < 0.01) and in a negative correlation with C3 and C4 (p < 0.05). LF-ANCA avidity was higher than MPO-, EL-, PR3-, and BPI-ANCA avidity (p < 0.01). In LF-ANCA-positive patients, renal manifestations were associated with higher LF-ANCA level (p < 0.01) and avidity (p < 0.05). Based on LF-ANCA level and avidity, the receiver operating characteristic curves for discriminating patients with and without renal involvement had areas under the curves of 0.988 (95% CI: 0.949-1.00) and 0.813 (95% CI: 0.607-1.00), respectively. After the follow-up period, number of LF-ANCA-positive patients decreased (p < 0.01).

CONCLUSIONS

In contrast to other ANCAs, only LF-ANCA level correlated with activity and standard serological SLE markers. LF-ANCA level and avidity might be biomarkers of renal involvement in SLE. LF-ANCA are promising serological marker in SLE. Key Points • LF- and MPO-ANCA were most frequently found, while EL-, PR3-, and BPI-ANCA were rarely detected in SLE. • In contrast to other ANCAs, only LF-ANCA were associated with renal involvement, and their level correlated with the activity and standard serological markers of SLE. • LF-ANCA avidity was higher than other ANCAs' avidity; LF-ANCA level and avidity might be useful biomarkers of renal manifestations in SLE. • Detection of ANCA specificity, level, and avidity may help in the diagnosis of particular clinical SLE phenotypes.

ANCA-Associated Intrahepatic Duct Injury Associated with Levamisole-Adulterated Cocaine

Damage to the liver or kidney can occur through direct toxic effects; however, damage can also be drug-induced immune-mediated. Levamisole-adulterated cocaine (LAC) is known to cause antineutrophil cytoplasmic antibody- (ANCA-) associated vasculitis and glomerulonephritis leading to acute kidney injury and end-stage renal disease. It remains unclear whether LAC is associated with hepatic duct damage. Here, we report a case with biopsy-proven evidence of intrahepatic duct damage months after being diagnosed with ANCA-associated crescentic and sclerosing glomerulonephritis caused by LAC use. This case represents the first report of LAC-induced ANCA-associated hepatic duct cholestasis in the setting of previous LAC-induced ANCA-positive glomerulonephritis.

Antineutrophil cytoplasmic antibody profiles differ according to type of primary sclerosing cholangitis and autoimmune hepatitis

OBJECTIVES

To determine the frequency of the antineutrophil cytoplasmic antibodies (ANCA), antiproteinase-3 and antimyeloperoxidase, in primary sclerosing cholangitis (PSC) with or without inflammatory bowel disease (IBD+ or IBD-) and in different types of autoimmune hepatitis (AIH). Additionally, to verify the agreement between ANCA patterns by indirect immunofluorescence and their antigenic specificities by ELISA.

METHODS

For this study, 249 patients were enrolled (42 PSC/IBD+; 33 PSC/IBD-; 31 AIH type-1; 30 AIH type-2; 31 AIH type-3; 52 primary biliary cirrhosis; 30 healthy controls) whose serum samples were tested for ANCA autoantibodies.

RESULTS

There were fewer female subjects in the PSC/IBD- group (p=0.034). Atypical perinuclear-ANCA was detected more frequently in PSC/IBD+ patients than in PSC/IBD- patients (p=0.005), and was significantly more frequent in type-1 (p<0.001) and type-3 AIH (p=0.012) than in type-2 AIH. Proteinase-3-ANCA was detected in 25 samples (only one with cytoplasmic-ANCA pattern), and more frequently in PSC/IBD+ than in PSC/IBD- patients (p=0.025). Myeloperoxidase-ANCA was identified in eight samples (none with the perinuclear-ANCA pattern). Among the 62 reactive samples for atypical perinuclear-ANCA, 13 had antigenic specific reactions for proteinase-3 and myeloperoxidase.

CONCLUSIONS

PSC/IBD+ differed from PSC/IBD- in terms of sex and proteinase 3-ANCA and atypical perinuclear-ANCA reactivity, the latter of which was more frequently detected in type-1 and type-3 AIH than in type-2 AIH. There was no agreement between ANCA patterns and antigenic specificities in IBD and autoimmune liver diseases, which reinforces the need for proteinase-3 and myeloperoxidase antibody testing.

Sulphite oxidase (SO) - a mitochondrial autoantigen as target for humoral and cellular immune reactions in primary sclerosing cholangitis

Background

In a recent study we had evidence that sulphite oxidase (SO) may be a relevant autoantigen in primary sclerosing cholangitis (PSC). Aim of the present study was, therefore, to analyse humoral and cellular immune-reactivity towards SO in these patients in more detail.

Methods

Sera from 53 patients with PSC (30 untreated and 23 treated with ursodeoxycholic acid [UDCA] at time of analysis), from 422 patients with different hepatic and non-hepatic disorders, and from 50 healthy individuals were tested by ELISA for antibodies against full-length-SO (SO-fl) and its three major domains expressed in E.coli (SO-I, SO-II, SO-III). For epitope-mapping, 29 overlapping peptides were used. Peripheral blood mononuclear cells (PBMC) were obtained from 33 PSC-patients and analysed for SO-induced proliferation, production of cytokines, and expression of the activation marker cluster of differentiation (CD) 69.

Results

43% of the 30 untreated and 26% of the 23 treated PSC-patients had IgG anti-SO-antibodies predominantly reacting with SO-fl, SO-I and SO-II. Antibody-reactivity decreased after UDCA-treatment. Prevalence and reactivity of anti-SO-antibodies were significantly higher in PSC than in patients with other hepatic and non-hepatic disorders. Epitope mapping revealed no distinct immuno-dominant regions within SO. Incubation of PBMC from PSC-patients (but not from controls) with SO-antigens revealed an activation of B-cells and a T-helper cell type-2 reaction pattern (production of interleukin [IL]-13, IL-10).

Conclusions

PSC-patients show humoral and cellular immune response towards SO. Antibodies may be predominantly directed against conformational epitopes. SO enhances in vitro especially T-helper cell type-2 immune-reactions, which may be pro-fibrotic. SO is a detoxifying enzyme present also in bacteria; further studies analysing its role in the aetiology and pathogenesis in PSC may, therefore, be important.

Electronic supplementary material

The online version of this article (10.1186/s12876-018-0787-x) contains supplementary material, which is available to authorized users.

Histone modification signature at myeloperoxidase and proteinase 3 in patients with anti-neutrophil cytoplasmic autoantibody-associated vasculitis

BACKGROUND

Anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is a systemic autoimmune disease characterized by destructive vascular inflammation. Two prominent ANCA autoantigens are myeloperoxidase (MPO) and proteinase 3 (PR3), and transcription of MPO and PRTN3, the genes encoding the autoantigens, is associated with disease activity. We investigated whether patients with AAV have alterations in histone modifications, particularly those associated with transcriptional activation, at MPO and PRTN3.

RESULTS

We identified a network of genes regulating histone modifications that were differentially expressed in AAV patients compared to healthy controls. We focused on four genes (EHMT1 and EHMT2, ING4, and MSL1) and found their expression correlated with expression of MPO and PRTN3. Methylation of histone H3K9, catalyzed by EHMT1 and EHMT2 and associated with gene silencing, was most depleted at MPO and PRTN3 in patients with active disease and the highest MPO and PRTN3 expression. Acetylation of histone H4K16, modified by complexes containing ING4 and MSL1 and associated with gene activation, was most enriched at MPO and PRTN3 in patients with active disease and the highest MPO and PRTN3 expression. Methylation at H3K4, a mark of transcriptional activation, was enriched at MPO and PRTN3 in patients and healthy controls.

CONCLUSIONS

MPO and PRTN3 in neutrophils of AAV patients with active disease have a distinct pattern of histone modifications, which implicates epigenetic mechanisms in regulating expression of autoantigen genes and suggests that the epigenome may be involved in AAV pathogenesis.

MMP-2 is a disease-modifying gene in primary sclerosing cholangitis

BACKGROUND

Primary sclerosing cholangitis (PSC) is a chronic inflammatory disease of the bile ducts, frequently necessitating orthotopic liver transplantation (OLT), often accompanied by inflammatory bowel disease (IBD). Matrix metalloproteinases (MMPs) are associated with fibrotic diseases caused by the involvement in tissue remodelling.

AIM

To evaluate the contribution of MMP-2 and -9 promoter polymorphisms to disease severity in PSC, as assessed by death or need for OLT.

METHODS

Matrix metalloproteinase-2 (-1306 C/T) and -9 (-1562 C/T) gene promoter polymorphisms were analyzed in 132 PSC patients. Follow-up was from onset PSC until death, OLT or end of follow-up.

RESULTS

Twenty-year cumulative incidence (CI) of death or OLT for PSC patients with MMP-2 CT genotype was 86.5% compared to 52.8% for CC genotype (P = 0.030) and reached 100% at 11.3 years for TT genotype. In patients with IBD, CIs were similar: 20-years CI of death or OLT for MMP-2 CT genotype was 86.0% compared to 49.0% for CC genotype and 100% at 11.3 years for TT genotype. Patients without IBD showed a similar trend in 20 years CI for MMP-2 CT (77.8%) compared to CC (57.8%) and CI for TT genotype reached 100% at 9.3 years. Multivariate analysis showed, along with age at diagnosis, a stepwise increase in hazard ratio for MMP-2 T-allele polymorphism for death or OLT. MMP-9 genotype was not associated with disease severity in PSC.

CONCLUSION

Matrix metalloproteinase-2 C to T-1306 gene promoter polymorphism in PSC is an independent risk factor for disease severity as reflected by the need for OLT or disease progression leading to mortality.