Advances in the genomics of ANCA-associated vasculitis-a view from East Asia

Association of tyrosine kinase 2 polymorphisms with susceptibility to microscopic polyangiitis in a Guangxi population

Background

Heredity and epigenetics affect the pathogenesis of microscopic polyangiitis (MPA). Tyrosine kinase 2 (TYK2) polymorphisms (rs2304256C > A, rs280519A > G, and rs12720270G > A) may be potential protective factors against anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Current research suggests that TYK2 is associated with various autoimmune diseases; however, no study has examined the relationship between TYK2 polymorphisms and AAV. This study assessed the effect of TYK2 polymorphisms on susceptibility to MPA.

Methods

Overall, 562 Chinese participants (265 patients with MPA and 297 healthy volunteers) were recruited. Polymerase chain reactions combined with high-throughput sequencing were used to analyze polymorphic loci, while logistic regression analysis was used to assess the relationship between polymorphism of the TYK2 gene and MPA susceptibility.

Results

In males, individuals with the CA genotype (rs2304256) in the overdominant model showed a significantly reduced risk of MPA (odds ratio (OR) = 0.52; 95% confidence interval (CI) [0.29-0.93]; p = 0.025). Regarding rs280519, male carriers of the AG genotype had a significantly lower risk of developing MPA in both the codominant (OR = 0.51; 95% CI [0.28-0.93]; p = 0.039) and overdominant (OR = 0.48; 95% CI [0.27-0.86]; p = 0.013) models. The GA genotype of rs12720270 was associated with low susceptibility to MPA in males (OR = 0.52; 95% CI [0.29-0.93]; p = 0.027).

Conclusions

This study indicates that mutations in the TYK2 gene (rs2304256, rs280519, and rs12720270) may be associated with a reduced risk of MPA in the male Chinese population in Guangxi. The A allele of single nucleotide polymorphism (SNP) rs2304256 may be a protective factor against MPA, while the G alleles of SNPs rs280519 and rs12720270 are protective factors against MPA.

Latent class analysis of chest CT abnormalities to define subphenotypes in patients with MPO-ANCA-positive microscopic polyangiitis

BACKGROUND

Patients with microscopic polyangiitis (MPA) and positive myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) may present with various abnormalities in chest computed tomography (CT). This study aimed to identify subphenotypes using latent class analysis (LCA) and to explore the relationship between the subphenotypes and clinical patterns, as well as compare the clinical characteristics of these subphenotypes in patients with MPO-ANCA-positive MPA (MPO-MPA).

METHODS

The study identified subphenotypes using LCA based on chest CT findings in 178 patients with MPO-MPA and pulmonary involvement from June 2014 to August 2022.

RESULTS

LCA identified 27 participants (15.2%) in class 1, 43 (24.1%) in class 2, 35 (19.7%) in class 3, and 73 (41.0%) in class 4. Class 1 was characterized by prominent inflammatory exudation, class 2 by fibrosis and architectural distortion, class 3 by predominantly bronchiectasis, and class 4 by lesions mixed with inflammation and fibrosis. Class 1 had the highest level of extrapulmonary disease activity, with 77.8% of patients experiencing diffuse alveolar hemorrhage. Class 2 had the lowest level of extrapulmonary disease activity, with 41.9% of patients showing usual interstitial pneumonia. Class 3 patients were more likely to have complications involving the ear, nose, and throat, as well as pulmonary infections before treatment, and they exhibited the best outcomes. The characteristics and outcomes of class 4 were intermediate among the four classes.

CONCLUSIONS

These findings suggest that bronchiectasis may represent a unique pattern of pulmonary involvement in MPO-MPA, highlighting the importance of screening for bronchiectasis in MPO-MPA and identifying optimal management strategies.

Renal damage and old age: risk factors for thrombosis in patients with ANCA-associated vasculitis

INTRODUCTION

Thrombosis in ANCA-associated vasculitis (AAV) was prevalent and has been neglected in Chinese patients. This study tried to describe the clinical characteristics, identify the risk factors, and investigate the causal relationship between AAV and venous thromboembolism (VTE) by two-sample Mendelian randomization (MR) analysis.

METHODS

In this retrospective, observational study, we included all hospitalized AAV patients from Jan 2013 to Apr 2022 in Peking Union Medical College Hospital. We collected their clinical data for multivariate regression analysis to determine the risk factors for thrombosis. The nomogram was constructed by applying these risk factors to predict thrombosis in AAV patients. As for MR analysis, we selected single nucleotide polymorphisms (SNPs) related to AAV from published genome-wide association studies and extracted the outcome data containing deep vein thrombosis (DVT) and pulmonary embolism (PE) from the UK biobank.

RESULTS

1203 primary AAV patients were enrolled, and thrombosis occurred in 11.3%. Multivariate regression suggested that older than 65 years, EGPA, neurological involvement, lung involvement, significantly elevated serum creatinine (> 500µmol/L), and elevated D-dimer were associated with thrombosis in AAV patients. The model demonstrated satisfied discrimination with an AUC of 0.769 (95% CI, 0.726-0.812). MR analysis showed that EGPA could increase the risk of developing DVT and PE (OR = 1.0038, 95%CI = 1.0035-1.0041, P = 0.009).

CONCLUSION

Thrombosis was not rare in Chinese patients with AAV. Renal damage and old age emerged as critical risk factors for thrombosis. EGPA might have a potential causal relationship with DVT and PE.

Occupational Silica Exposure as a Potential Risk for Microscopic Polyangiitis

Microscopic polyangiitis is an important and common component of cytoplasmic antibody-associated vasculitides that can lead to serious morbidity and even death. A clear causative etiology has not been identified. Although silica is well known to produce lung damage, the negative renal effects of silica exposure should not be overlooked. We present a case of renal dysfunction associated with silica exposure, its diagnosis by renal biopsy, and the treatment method used. Environmental or occupational silica exposure can cause microscopic polyangiitis. Working in occupations with increased risk of silica exposure may result in serious medical problems.

Association between the AKT1 single nucleotide polymorphism (rs2498786, rs2494752 and rs5811155) and microscopic polyangiitis risk in a Chinese population

Microscopic polyangiitis (MPA) is an autoimmune disease, characterized by ANCA in blood and necrotizing inflammation of small and medium-sized vessels, one of the three clinical phenotypes of ANCA-associated vasculitis (AAV). Autophagy has been confirmed to be involved in the pathogenesis of AAV. AKT1 is one of the autophagy-regulated proteins. Its single nucleotide polymorphisms (SNPs) are associated with multiple immune-related diseases, but there are rarely studies in AAV. The incidence rate of AAV has a notable geographic difference, and MPA is predominant in China. The aim of this study was to investigate the association between AKT1 SNP and MPA risk. Genotypes of 8 loci in AKT1 were evaluated by multiplex polymerase chain reaction (PCR) and high-throughput sequencing in 416 people, including 208 MPA patients and 208 healthy volunteers from Guangxi in China. Additionally, data of 387 healthy volunteers from China were obtained from the 1000Genomes Project on public database. Differences were observed between the loci (rs2498786, rs2494752, and rs5811155) genotypes in AKT1 and MPA risk (P = 7.0 × 10^-4, P = 3.0 × 10^-4, and P = 5.9 × 10^-5, respectively). A negative association was detected in the Dominant model (P = 1.2 × 10^-3, P = 2.0 × 10^-4 and P = 3.6 × 10^-5, respectively). A haplotype (G-G-T) was associated with MPA risk negatively (P = 7.0 × 10^-4). This study suggests that alleles (rs2498786 G, rs2494752 G and rs5811155 insT) are protective factors for MPA and alleles (rs2494752 G and rs5811155 insT) for MPO-ANCA in patients with MPA. There is a haplotype (G-G-T), which is a protective factor for MPA. It suggests that the role of AKT1 in MPA/AAV needs further study to provide more intervention targets for MPA/AAV.

Association of HLA-class II alleles with risk of relapse in myeloperoxidase-antineutrophil cytoplasmic antibody positive vasculitis in the Japanese population

Background

Disease relapse remains a major problem in the management of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). In European populations, HLA-DPB1*04:01 is associated with both susceptibility and relapse risk in proteinase 3-ANCA positive AAV. In a Japanese population, we previously reported an association between HLA-DRB1*09:01 and DQB1*03:03 with susceptibility to, and DRB1*13:02 with protection from, myeloperoxidase-ANCA positive AAV (MPO-AAV). Subsequently, the association of DQA1*03:02, which is in strong linkage disequilibrium with DRB1*09:01 and DQB1*03:03, with MPO-AAV susceptibility was reported in a Chinese population. However, an association between these alleles and risk of relapse has not yet been reported. Here, we examined whether HLA-class II is associated with the risk of relapse in MPO-AAV.

Methods

First, the association of HLA-DQA1*03:02 with susceptibility to MPO-AAV and microscopic polyangiitis (MPA) and its relationship with previously reported DRB1*09:01 and DQB1*03:03 were examined in 440 Japanese patients and 779 healthy controls. Next, the association with risk of relapse was analyzed in 199 MPO-ANCA positive, PR3-ANCA negative patients enrolled in previously reported cohort studies on remission induction therapy. Uncorrected P values (Puncorr) were corrected for multiple comparisons in each analysis using the false discovery rate method.

Results

The association of DQA1*03:02 with susceptibility to MPO-AAV and MPA was confirmed in a Japanese population (MPO-AAV: Puncorr=5.8x10-7, odds ratio [OR] 1.74, 95% confidence interval [CI] 1.40-2.16, MPA: Puncorr=1.1x10-5, OR 1.71, 95%CI 1.34-2.17). DQA1*03:02 was in strong linkage disequilibrium with DRB1*09:01 and DQB1*03:03, and the causal allele could not be determined using conditional logistic regression analysis. Relapse-free survival was shorter with nominal significance in carriers of DRB1*09:01 (Puncorr=0.049, Q=0.42, hazard ratio [HR]:1.87), DQA1*03:02 (Puncorr=0.020, Q=0.22, HR:2.11) and DQB1*03:03 (Puncorr=0.043, Q=0.48, HR:1.91) than in non-carriers in the log-rank test. Conversely, serine carriers at position 13 of HLA-DRβ1 (HLA-DRβ1_13S), including DRB1*13:02 carriers, showed longer relapse-free survival with nominal significance (Puncorr=0.010, Q=0.42, HR:0.31). By combining DQA1*03:02 and HLA-DRβ1_13S, a significant difference was detected between groups with the highest and lowest risk for relapse (Puncorr=0.0055, Q=0.033, HR:4.02).

Conclusion

HLA-class II is associated not only with susceptibility to MPO-AAV but also with risk of relapse in the Japanese population.

Meta-analysis confirmed genetic susceptibility conferred by multiple risk variants from CTLA4 and SERPINA1 in granulomatosis with polyangiitis

BACKGROUND

Granulomatosis with polyangiitis (GPA) is a rare systemic autoimmune disease. Smaller sample size and complex nature of the disease pathogenesis has made it challenging to perform well-powered genetic investigations. We performed a systematic review based meta-analysis in GPA to investigate the genetic susceptibility conferred by non-human leukocyte antigen (non-HLA) candidate genes.

METHODS

A systematic review was performed using web-based literature search and eligible studies were included following inclusion-exclusion criteria. Studies were evaluated for their quality of evidence and study outcome was assessed using the Newcastle-Ottawa Scale and Grades of Research, Assessment, Development and Evaluation tools. Reviewer's agreement was accessed through Cohen's κ value. Meta-analyses were performed using RevMan 5 tool. Meta-odds ratio (meta-OR) and Z test P value were evaluated to estimate the genetic susceptibility for each of the variants.

RESULTS

Eighteen studies were found eligible and 7 genetic variants from only 4 genes, namely CTLA4, PRTN3, SERPINA1 and PTPN22 could be studied for meta-analysis. rs231775-G (49-G) (Meta-OR = 1.42 [1.14-1.76]; P = .001) of CTLA4 and rs7151526-A (Meta-OR = 2.70 [1.51-4.85]; P = .0008) of SERPINA1 were confirmed to be predisposing alleles, and rs5742909-C (318-C) (Meta-OR = 0.65 [0.44-0.97]; P =.03) of CTLA4 was found to be protective for GPA. In concordance with the genetic association of rs7151526-A, serological marker for the same variant "Z" allele of SERPINA1 was found to be predisposing (Meta-OR = 12.60 [5.01-31.68]; P < .00001) for GPA.

CONCLUSION

Genetic variants confirmed in this study play critical roles in T-cell mediated immune function and could be significantly implicated in GPA. Molecular pathology studies are warranted to confirm their role. These markers could be used for efficient patient classification and disease management.

Elevated Level of Serum Interleukin-21 and Its Influence on Disease Activity in Anti-Neutrophil Cytoplasmic Antibodies Against Myeloperoxidase-Associated Vasculitis

Interleukin-21 (IL-21) has been shown to play an important role in the immune system. This study aimed to investigate the changes in the level of IL-21 in patients with anti-neutrophil cytoplasmic antibodies against myeloperoxidase (MPO-ANCA)-associated vasculitis (MPO-AAV), as well as explore its influence on disease activity and the potential mechanism. Flow cytometry was performed to detect the percentage of follicular helper T cells (Tfh) among CD4⁺T cells (Tfh%); the percentage of Tfh-expressing inducible costimulator (ICOS) among Tfh cells (ICOS⁺Tfh%); the percentage of Tfh-expressing programmed cell death protein 1 (PD-1) among Tfh cells (PD-1⁺Tfh%); and mean fluorescence intensity of Tfh-expressing ICOS or PD-1 in the peripheral blood. An enzyme-linked immunosorbent assay was used to measure the levels of serum IL-21 and MPO-ANCA. The Birmingham Vasculitis Activity Score was used to evaluate disease activity. Our results revealed that the level of IL-21 in the patient group was significantly higher than that in the healthy control group (1324.2 ± 125.3 pg/mL vs. 704.2 ± 41.1 pg/mL, P < 0.001), and it was an independent factor affecting the disease activity (P = 0.022). Thus, blocking the activity of IL-21 may represent a potential novel target for the future treatment of MPO-AAV.

Rheumatoid factor positivity in antineutrophil cytoplasmic antibody-associated vasculitis: a distinct clinical entity or innocent bystander?

OBJECTIVE

To investigate the significance of rheumatoid factor (RF) positivity in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) patients.

METHODS

AAV patients were divided into groups as follows: RF (+)/ANCA (+) (n = 94), RF (-)/ANCA (+) (n = 80), RF (+)/ANCA (-) (n = 15), and RF (-)/ANCA (-) (n = 25). Their clinical data, organ involvement patterns, laboratory data, and patient outcomes were assessed. Kaplan-Meier analysis and propensity score matching (PSM) were performed to compare outcomes and analyse differences between the groups.

RESULTS

Of the 214 patients, RF and ANCA positivity was found in 109 (50.9%) and 174 (81.3%) patients, respectively. RF (+)/ANCA (+) patients more frequently presented with general manifestations (58.5%) than the other groups. Additionally, compared with those of RF (-)/ANCA (+) group, RF (+)/ANCA (+) patients were older, had higher white blood cell, neutrophil, platelet counts, and acute phase reactants; however, creatinine and albumin levels were lower. The end-stage kidney disease-free survival rate was significantly higher in the RF (+)/ANCA (+) group (p= 0.013), while the proportion of renal involvement was comparable to the RF (-)/ANCA (+) group. PSM showed no difference in patient outcomes between the two groups after adjustment.

CONCLUSION

RF positivity was associated with a distinct phenotype in AAV patients. In particular, difference was observed in clinical features and outcomes between RF (+)/ANCA (+) and RF (-)/ANCA (+) groups, although the direct prognostic implication of RF was not evident.