Leveraging Genetic Findings for Precision Medicine in Vasculitis

Risk loci involved in giant cell arteritis susceptibility: a genome-wide association study

BACKGROUND

Giant cell arteritis is an age-related vasculitis that mainly affects the aorta and its branches in individuals aged 50 years and older. Current options for diagnosis and treatment are scarce, highlighting the need to better understand its underlying pathogenesis. Genome-wide association studies (GWAS) have emerged as a powerful tool for unravelling the pathogenic mechanisms involved in complex diseases. We aimed to characterise the genetic basis of giant cell arteritis by performing the largest GWAS of this vasculitis to date and to assess the functional consequences and clinical implications of identified risk loci.

METHODS

We collected and meta-analysed genomic data from patients with giant cell arteritis and healthy controls of European ancestry from ten cohorts across Europe and North America. Eligible patients required confirmation of giant cell arteritis diagnosis by positive temporal artery biopsy, positive temporal artery doppler ultrasonography, or imaging techniques confirming large-vessel vasculitis. We assessed the functional consequences of loci associated with giant cell arteritis using cell enrichment analysis, fine-mapping, and causal gene prioritisation. We also performed a drug repurposing analysis and developed a polygenic risk score to explore the clinical implications of our findings.

FINDINGS

We included a total of 3498 patients with giant cell arteritis and 15 550 controls. We identified three novel loci associated with risk of giant cell arteritis. Two loci, MFGE8 (rs8029053; p=4·96 × 10-8; OR 1·19 [95% CI 1·12-1·26]) and VTN (rs704; p=2·75 × 10-9; OR 0·84 [0·79-0·89]), were related to angiogenesis pathways and the third locus, CCDC25 (rs11782624; p=1·28 × 10-8; OR 1·18 [1·12-1·25]), was related to neutrophil extracellular traps (NETs). We also found an association between this vasculitis and HLA region and PLG. Variants associated with giant cell arteritis seemed to fulfil a specific regulatory role in crucial immune cell types. Furthermore, we identified several drugs that could represent promising candidates for treatment of this disease. The polygenic risk score model was able to identify individuals at increased risk of developing giant cell arteritis (90th percentile OR 2·87 [95% CI 2·15-3·82]; p=1·73 × 10-13).

INTERPRETATION

We have found several additional loci associated with giant cell arteritis, highlighting the crucial role of angiogenesis in disease susceptibility. Our study represents a step forward in the translation of genomic findings to clinical practice in giant cell arteritis, proposing new treatments and a method to measure genetic predisposition to this vasculitis.

FUNDING

Institute of Health Carlos III, Spanish Ministry of Science and Innovation, UK Medical Research Council, and National Institute for Health and Care Research.

Single-cell transcriptomic profiling reveals a pathogenic role of cytotoxic CD4+ T cells in giant cell arteritis

Giant cell arteritis (GCA) is a systemic vasculitis mediated by an aberrant immunological response against the blood vessel wall. Although the pathogenic mechanisms that drive GCA have not yet been elucidated, there is strong evidence that CD4+ T cells are key drivers of the inflammatory process occurring in this vasculitis. The aim of this study was to further delineate the role of CD4+ T cells in GCA by applying single-cell RNA sequencing and T cell receptor (TCR) repertoire profiling to 114.799 circulating CD4+ T cells from eight GCA patients in two different clinical states, active and in remission, and eight healthy controls. Our results revealed an expansion of cytotoxic CD4+ T lymphocytes (CTLs) in active GCA patients, which expressed higher levels of cytotoxic and chemotactic genes when compared to patients in remission and controls. Accordingly, differentially expressed genes in CTLs of active patients were enriched in pathways related to granzyme-mediated apoptosis, inflammation, and the recruitment of different immune cells, suggesting a role of this cell type in the inflammatory and vascular remodelling processes occurring in GCA. CTLs also exhibited a higher clonal expansion in active patients with respect to those in remission. Drug repurposing analysis prioritized maraviroc, which targeted CTLs, as potentially repositionable for this vasculitis. In addition, effector regulatory T cells (Tregs) were decreased in GCA and showed lower expression of genes involved in their suppressive activity. These findings provide further insights into the pathogenic role of CD4+ T cells in GCA and suggest targeting CTLs as a potential therapeutic option.

Identification of new risk loci shared across systemic vasculitides points towards potential target genes for drug repurposing

OBJECTIVES

The number of susceptibility loci currently associated with vasculitis is lower than in other immune-mediated diseases due in part to small cohort sizes, a consequence of the low prevalence of vasculitides. This study aimed to identify new genetic risk loci for the main systemic vasculitides through a comprehensive analysis of their genetic overlap.

METHODS

Genome-wide data from 8467 patients with any of the main forms of vasculitis and 29 795 healthy controls were meta-analysed using ASSET. Pleiotropic variants were functionally annotated and linked to their target genes. Prioritised genes were queried in DrugBank to identify potentially repositionable drugs for the treatment of vasculitis.

RESULTS

Sixteen variants were independently associated with two or more vasculitides, 15 of them representing new shared risk loci. Two of these pleiotropic signals, located close to CTLA4 and CPLX1, emerged as novel genetic risk loci in vasculitis. Most of these polymorphisms appeared to affect vasculitis by regulating gene expression. In this regard, for some of these common signals, potential causal genes were prioritised based on functional annotation, including CTLA4, RNF145, IL12B, IL5, IRF1, IFNGR1, PTK2B, TRIM35, EGR2 and ETS2, each of which has key roles in inflammation. In addition, drug repositioning analysis showed that several drugs, including abatacept and ustekinumab, could be potentially repurposed in the management of the analysed vasculitides.

CONCLUSIONS

We identified new shared risk loci with functional impact in vasculitis and pinpointed potential causal genes, some of which could represent promising targets for the treatment of vasculitis.

Endovascular Intervention in a Narrowing Vessel of the Left Vertebral Artery with Bilateral Common Carotid Artery Occlusion and Aneurysm Rupture and Hemorrhage in the V4 Segment of the Right Vertebral Artery

In this study, a case of bilateral common carotid artery occlusion and aneurysm in the V4 segment of the right vertebral artery with constriction of the left vertebral artery is presented. By improving digital subtraction angiography, an elderly female patient with subarachnoid haemorrhage (SAH) was diagnosed with a V4 segment of right vertebral artery aneurysm, a microaneurysm at the beginning of basilar aneurysms, bilateral common carotid artery occlusion, and narrowing vessel of left vertebral artery (DSA). Through the compensation of the basilar artery, the bilateral vertebral arteries provide intracranial and extracranial blood. Because the vertebral artery is narrowed, the right vertebral artery has priority in intracranial and extracranial blood delivery. Many members of the patient's immediate family have vasculitis, which has yet to be proven by appropriate laboratory testing but is thought to be the major cause of big artery occlusion. After cerebral angiography, the major source of this subarachnoid haemorrhage was determined to be a V4 segment of right vertebral artery aneurysm. Endovascular stent-assisted coil embolization was used to treat a V4 section of the right vertebral artery aneurysm. Because the basilar aneurysm was distal to the artery, interventional embolization was difficult to do, and it was not the major cause of the subarachnoid haemorrhage, the patient was advised to have follow-up surveillance, and she recovered well following the procedure. The combination of endovascular intervention of bilateral common carotid artery blockage and V4 segment of right vertebral artery aneurysm yielded excellent clinical outcomes in this instance. Endovascular treatment of a bilateral common carotid artery blockage paired with a V4 segment of a right vertebral artery aneurysm yielded excellent clinical outcomes in this patient, although long-term follow-up is necessary.

Unraveling the Immunopathogenesis and Genetic Variants in Vasculitis Toward Development of Personalized Medicine

Leukocytoclastic vasculitis (LCV) is a systemic autoimmune disease characterized by the inflammation of the vascular endothelium. Cutaneous small vessel vasculitis (CSVV) and anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) are two examples of LCV. Advancements in genomic technologies have identified risk haplotypes, genetic variants, susceptibility loci and pathways that are associated with vasculitis immunopathogenesis. The discovery of these genetic factors and their corresponding cellular signaling aberrations have enabled the development and use of novel therapeutic strategies for vasculitis. Personalized medicine aims to provide targeted therapies to individuals who show poor response to conventional interventions. For example, monoclonal antibody therapies have shown remarkable efficacy in achieving disease remission. Here, we discuss pathways involved in disease pathogenesis and the underlying genetic associations in different populations worldwide. Understanding the immunopathogenic pathways in vasculitis and identifying associated genetic variations will facilitate the development of novel and targeted personalized therapies for patients.

Delayed Development of Coronary Artery Aneurysm in Patients with Kawasaki Disease Who Were Clinically Responsive to Immunoglobulin

OBJECTIVE

To clarify the frequency and characteristics of discrepant outcomes of intravenous immunoglobulin (IVIG) between fever and coronary artery aneurysms (CAAs) in patients with Kawasaki disease.

STUDY DESIGN

This study included 325 patients who responded to oral aspirin and IVIG alone. The main outcome was CAA 4 weeks after disease onset. CAA was defined as ≥2.5 of maximum z score (Zmax) representing the highest value of 4 coronary artery branches. Immunoglobulin dosage and sequential changes in Zmax were reviewed to investigate the effects on fever and timing of CAA development. Logistic regression analyses with receiver operating characteristic curves using clinical and laboratory variables including the initial Zmax were performed to identify predictors of CAA at 4 weeks.

RESULTS

CAAs were either persistent or appeared de novo 4 weeks after diagnosis in 13 of 325 patients who responded to a single or repeated IVIG. Four single-dose IVIG-responders developed CAA although they had pretreatment Zmax of <2.0. The 2 single-dose IVIG responders with the greatest pretreatment Zmax (>4.5) developed persistent CAA. Receiver operating characteristic analysis demonstrated Zmax of 2.57 as the cut-off for predicting CAA. Multivariable analyses identified >2.5 Zmax (OR 9.08, 95% CI 1.26-65.3, P = .028, 50% sensitivity, 91% specificity) as the sole risk factor for CAA at 4 weeks in single-dose IVIG responders.

CONCLUSIONS

Delayed development and persistence of CAA in single-dose IVIG responders indicate that some factors other than those responsible for systemic inflammation may contribute to vasculitis in CAA. Baseline Zmax 2.5 aids in predicting CAAs.

Associations and Outcomes Between Chronic Traumatic Encephalopathy and Vasculitis in Adult Patients

Chronic traumatic encephalopathy (CTE) results from brain injuries and traumas due to accelerated impacts on the head. In severe cases, the diseases cause brain damage, given the head trauma. On the other hand, vasculitis occurs through antibodies that mistake protein vessels as foreign, hence fighting them and resulting in their damage. Examination is usually conducted through blood tests, with antibodies being identified in the antineutrophil cytoplasm. It is unfortunate that its devastating effects also affect the brain of a human, hence leading to dis-functioning. When vasculitis is left untreated, it results in multiple adverse effects on the human body and health both in the short term and in the long term. This study aims to bring to the awareness of neurosurgeons the associations between CTE and vasculitis. This study has proved that there is a close correlation between the progression of CTE and vasculitis. The inflammatory of the blood vessels, as witnessed in vasculitis, increases the risk factors for CTE. The scaling of the vessels and manifestation of different vasculitis conditions in active central nervous system cells results in the worsening of neurodegeneration of the CTE disease.

Current State of Precision Medicine in Primary Systemic Vasculitides

Precision medicine (PM) is an emerging data-driven health care approach that integrates phenotypic, genomic, epigenetic, and environmental factors unique to an individual. The goal of PM is to facilitate diagnosis, predict effective therapy, and avoid adverse reactions specific for each patient. The forefront of PM is in oncology; nonetheless, it is developing in other fields of medicine, including rheumatology. Recent studies on elucidating the genetic architecture of polygenic and monogenic rheumatological diseases have made PM possible by enabling physicians to customize medical treatment through the incorporation of clinical features and genetic data. For complex inflammatory disorders, the prevailing paradigm is that disease susceptibility is due to additive effects of common reduced-penetrance gene variants and environmental factors. Efforts have been made to calculate cumulative genetic risk score (GRS) and to relate specific susceptibility alleles for use of target therapies. The discovery of rare patients with single-gene high-penetrance mutations informed our understanding of pathways driving systemic inflammation. Here, we review the advances in practicing PM in patients with primary systemic vasculitides (PSVs). We summarize recent genetic studies and discuss current knowledge on the contribution of epigenetic factors and extracellular vesicles (EVs) in disease progression and treatment response. Implementation of PM in PSVs is a developing field that will require analysis of a large cohort of patients to validate data from genomics, transcriptomics, metabolomics, proteomics, and epigenomics studies for accurate disease profiling. This multi-omics approach to study disease pathogeneses should ultimately provide a powerful tool for stratification of patients to receive tailored optimal therapies and for monitoring their disease activity.