A novel susceptibility locus in the IL12B region is associated with the pathophysiology of Takayasu arteritis through IL-12p40 and IL-12p70 production

A Glimpse into Humoral Response and Related Therapeutic Approaches of Takayasu's Arteritis

Takayasu's arteritis (TAK) manifests as an insidiously progressive and debilitating form of granulomatous inflammation including the aorta and its major branches. The precise etiology of TAK remains elusive, with current understanding suggesting an autoimmune origin primarily driven by T cells. Notably, a growing body of evidence bears testimony to the widespread effects of B cells on disease pathogenesis and progression. Distinct alterations in peripheral B cell subsets have been described in individuals with TAK. Advancements in technology have facilitated the identification of novel autoantibodies in TAK. Moreover, emerging data suggest that dysregulated signaling cascades downstream of B cell receptor families, including interactions with innate pattern recognition receptors such as toll-like receptors, as well as co-stimulatory molecules like CD40, CD80 and CD86, may result in the selection and proliferation of autoreactive B cell clones in TAK. Additionally, ectopic lymphoid neogenesis within the aortic wall of TAK patients exhibits functional characteristics. In recent decades, therapeutic interventions targeting B cells, notably utilizing the anti-CD20 monoclonal antibody rituximab, have demonstrated efficacy in TAK. Despite the importance of the humoral immune response, a systematic understanding of how autoreactive B cells contribute to the pathogenic process is still lacking. This review provides a comprehensive overview of the biological significance of B cell-mediated autoimmunity in TAK pathogenesis, as well as insights into therapeutic strategies targeting the humoral response. Furthermore, it examines the roles of T-helper and T follicular helper cells in humoral immunity and their potential contributions to disease mechanisms. We believe that further identification of the pathogenic role of autoimmune B cells and the underlying regulation system will lead to deeper personalized management of TAK patients. We believe that further elucidation of the pathogenic role of autoimmune B cells and the underlying regulatory mechanisms holds promise for the development of personalized approaches to managing TAK patients.

Baricitinib for refractory Takayasu arteritis: a prospective cohort study in a tertiary referral centre

OBJECTIVE

To investigate the treatment efficacy and safety of baricitinib in patients with refractory Takayasu arteritis (TAK).

METHODS

We performed a prospective cohort study in which baricitinib 4 mg daily was prescribed to patients with refractory TAK, combined with oral glucocorticoids (GCs).

RESULTS

10 patients with refractory TAK were enrolled with a median age of 28 (IQR=22-37) years, median disease duration of 50 (IQR=24-65) months. The median dose of GCs was 10 (IQR=8.1-22.5) mg prednisone or equivalence dosage at baseline. At 6 months of baricitinib treatment, 6/10 (60%) patients had an overall treatment response. During an average follow-up of 15.3 (range 4-31) months, 4/10 (40%) patients maintained overall treatment response. 8/10 (80%) patients tapered or maintained the same dose of GCs with no change of the combined classical synthetic disease-modifying antirheumatic drugs. Two patients discontinued GCs at 18 and 24 months and were in continuous remission till the end of the study. One patient withdrew baricitinib due to liver dysfunction.

CONCLUSION

Baricitinib 4 mg daily is effective for refractory TAK and is well tolerated.

Enhanced efficacy of the novel recombinant clone VasSF in a mouse model of antineutrophil cytoplasmic antibody-associated vasculitis

Based on the efficacy of intravenous immunoglobulin (IVIg) for the treatment of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), we developed a recombinant single-chain-fragment variable clone, VasSF, therapeutic against AAV in a mouse model (SCG/Kj mice). VasSF is thought to bind to vasculitis-associated apolipoprotein A-II (APOA2) as a target molecule. VasSF is a promising new drug against AAV, but difficulties in the yield and purification of VasSF remain unresolved. We produced monomers of new VasSF molecules by modifying the plasmid structure for VasSF expression and simplifying the purification method using high-performance liquid chromatography. We compared the therapeutic effects between 5-day continuous administration of the monomers, as in IVIg treatment, and single shots of 5-day-equivalent doses. We also evaluated the life-prolonging effect of the single-shot treatment. Two-dimensional western blots were used to examine the binding of VasSF to APOA2. Our improved manufacturing method resulted in a 100-fold higher yield of VasSF than in our previous study. Monomerization of VasSF stabilized its efficacy. Single shots of a small amount (1/80 000 of IVIg) produced sufficient therapeutic effects, including decreased glomerular crescent formation, a decreasing trend of serum ANCA against myeloperoxidase (MPO-ANCA), decreases in multiple proinflammatory cytokines, and a trend toward prolonged survival. Two-dimensional western blots confirmed the binding of VasSF to APOA2. The newly produced pure VasSF monomers are stable and therapeutic for AAV with a single low-dose injection, possibly by removing vasculitis-associated APOA2. Thus, the new VasSF described herein is a promising drug against AAV.

Psoriasis and Leprosy: An Arcane Relationship

Purpose

Psoriasis (Ps) and leprosy are chronic inflammatory skin disorders, characterised by enhanced innate and adaptive immunity. Ps and leprosy rarely coexist. The molecular immune mechanism of the Ps and leprosy rarely coexistence is unclear.

Patients and Methods

RNA-sequencing (RNA-seq) was performed on 20 patients with Ps, 5 adults with lepromatous leprosy (L-lep), and 5 patients with tuberculoid leprosy (T-lep) to analyse the differentially expressed genes (DEGs) between them. Moreover, the biological mechanism of Ps and leprosy was explored by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, Gene Ontology (GO) analysis, Gene Set Enrichment Analysis analysis, and protein-protein interaction (PPI) analyses. Finally, 13 DEGs of 10 skin biopsies of Ps patients, 6 samples of L-lep patients, 6 samples of T-lep patients and 5 healthy controls were confirmed by quantitative real-time polymerase chain reaction (qRT-PCR).

Results

The PPI network was constructed and primarily associated with immune response, IL-17 signalling, and Toll-like receptor pathway between Ps and leprosy. Th17 markers (interleukin (IL)-19, IL-20, IL-36A, IL-36G, IL-22, IL-17A, and lipocalin-2 (LCN2) had higher expression in Ps than in L-lep and T-lep, whereas macrophage biomarkers (CLEC4E and TREM2), SPP1, and dendritic cell (DC)-related hallmarks (ITGAX) and TNF-a had significantly lower expression across Ps and T-lep than in L-lep.

Conclusion

To put it simply, Ps patients with IL-17A, IL-19, IL-20, IL-36A, IL-36G, and IL-22 in conjunction with LCN2 with up-graduated expression might be not susceptible to L-lep. However, high levels of CLEC4E, TREM2, and SPP1 in L-lep patients indicated that they unlikely suffered from Ps.

Animal models for large vessel vasculitis - The unmet need

Our understanding of the pathogenesis of large vessel vasculitis (LVV) are mainly achieved by studying the arteries taken from temporal artery biopsy in giant cell arteries (GCA) or surgical or autopsy specimens in Takayasu arteritis (TAK). These artery specimens provide invaluable information about pathological changes in these conditions that GCA and TAK are similar but are distinctly different in immune cell infiltrate and distribution of inflammatory cells in anatomical locations. However, these specimens of established arteritis do not provide information of the arteritis initiation and early events which are impossible to obtain in human artery specimens. Animal models for LVV are needed but not available. Here, several approaches are proposed for experimentation to generate animal models to aid in delineating the interaction of immune reaction with arterial wall components.

SAPHO syndrome with Takayasu arteritis successfully treated with tofacitinib

SAPHO syndrome is an autoinflammatory disease with a variety of clinical manifestations, which may be accompanied by other systemic inflammatory diseases in addition to the typical manifestations of common synovitis, acne, pustulosis, hyperostosis, and osteitis. Here, we report the first case of SAPHO syndrome combined with Takayasu arteritis.

Outcome Measures and Biomarkers for Disease Assessment in Takayasu Arteritis

Takayasu arteritis (TAK) is a less common large vessel vasculitis where histopathology of involved arteries is difficult to access except during open surgical procedures. Assessment of disease activity in TAK, therefore, relies on surrogate measures. Clinical disease activity measures such as the National Institutes of Health (NIH) score, the Disease Extent Index in TAK (DEI.TAK) and the Indian TAK Clinical Activity Score (ITAS2010) inconsistently associate with acute phase reactants (APRs). Computerized tomographic angiography (CTA), magnetic resonance angiography (MRA), or color Doppler Ultrasound (CDUS) enables anatomical characterization of stenosis, dilatation, and vessel wall characteristics. Vascular wall uptake of 18-fluorodeoxyglucose or other ligands using positron emission tomography computerized tomography (PET-CT) helps assess metabolic activity, which reflects disease activity well in a subset of TAK with normal APRs. Angiographic scoring systems to quantitate the extent of vascular involvement in TAK have been developed recently. Erythrocyte sedimentation rate and C-reactive protein have a moderate performance in distinguishing active TAK. Numerous novel biomarkers are under evaluation in TAK. Limited literature suggests a better assessment of active disease by combining APRs, PET-CT, and circulating biomarkers. Validated damage indices and patient-reported outcome measures specific to TAK are lacking. Few biomarkers have been evaluated to reflect vascular damage in TAK and constitute important research agenda.

Perspectives of JAK Inhibitors for Large Vessel Vasculitis

Vasculitis is an inflammation of the blood vessels caused by autoimmunity and/or autoinflammation, and recent advances in research have led to a better understanding of its pathogenesis. Glucocorticoids and cyclophosphamide have long been the standard of care. However, B-cell depletion therapy with rituximab has become available for treating antineutrophil cytoplasmic antibody-associated vasculitis (AAV). More recently, avacopan, an inhibitor of the complement 5a receptor, was shown to have high efficacy in remission induction against AAV. Thus, treatment options for AAV have been expanded. In contrast, in large vessel vasculitis (LVV), including giant cell arteritis and Takayasu arteritis, tocilizumab, an IL-6 receptor antagonist, was shown to be effective in suppressing relapse and has steroid-sparing effects. However, the relapse rate remains high, and other therapeutic options have long been awaited. In the last decade, Janus kinase (JAK) inhibitors have emerged as therapeutic options for rheumatoid arthritis (RA). Their efficacy has been proven in multiple studies; thus, JAK inhibitors are expected to be promising agents for treating other rheumatic diseases, including LVV. This mini-review briefly introduces the mechanism of action of JAK inhibitors and their efficacy in patients with RA. Then, the pathophysiology of LVV is updated, and a rationale for treating LVV with JAK inhibitors is provided with a brief introduction of our preliminary results using a mouse model. Finally, we discuss the newly raised safety concerns regarding JAK inhibitors and future perspectives for treating LVV.

Novel Therapies in Takayasu Arteritis

Takayasu Arteritis (TAK) is a large-vessel vasculitis that preferentially involves the aorta and its primary branches. Cardiac involvement is frequent in TAK and is a major determinant of the patient's outcome. Glucocorticoids (GC) are the mainstay of therapy for TAK, with high doses of GC effective to induce remission. However, relapses are common and lead to repeated and prolonged GC treatments with high risk of related adverse events. Potential GC toxicity is a major concern, especially because patients with TAK are young and need to be treated for several years, often for the whole life. Conventional immunosuppressive drugs are used in patients with severe manifestations but present some limitations. New therapeutic approaches are needed for patients with refractory disease or contraindications to conventional therapies. Fortunately, major progress has been made in understanding TAK pathogenesis, leading to the development of targeted biotherapies. In particular, IL-6 and TNF-α pathways seems to be the most promising therapeutic targets, with emerging data on Tocilizumab and TNF inhibitors. On the other hand, new insights on JAK-Inhibitors, Rituximab, Ustekinumab and Abatacept have been explored in recent studies. This review summarizes the emerging therapies used in TAK, focusing on the most recent studies on biologics and analyzing their efficacy and safety.

An Update on Childhood-Onset Takayasu Arteritis

Takayasu Arteritis (TAK) is a rare large vessel vasculitis affecting the aorta and its major branches. The heterogeneous and often severe clinical manifestations result from systemic and local inflammation as well as end-organ ischemia. Disease flares are common and contribute to accrued damage over time with significant morbidity and mortality. Newer understanding of the pathogenesis in TAK has paved the way for the use of pathway targeting agents such as tumor necrosis factor (TNF)α- or interleuking (IL)-6-inhibitors with improved disease control. Nevertheless, long-term data are lacking, particularly in children; prognosis often remains guarded and the disease burden high. This article aims at providing a comprehensive review of childhood-onset TAK with a focus on recent publications.

A susceptibility locus in the IL12B but not LILRA3 region is associated with vascular damage in Takayasu arteritis

HLA-B*52 is an established genetic factor in Takayasu arteritis (TAK). Recently, single nucleotide polymorphisms (SNPs) in IL12B (rs6871626) and LILRA3 (rs103294) were newly identified as non-HLA susceptibility loci in TAK. Here, we examined how these SNPs contribute to clinical characteristics and vascular damage in TAK. We retrospectively reviewed the medical records of 99 TAK patients enrolled in our previous genome-wide association study, and whose genotypes for IL12B rs6871626, LILRA3 rs103294, and HLA-B*52 were available. Incidence of aortic regurgitation (AR) was significantly associated with the A allele (risk allele) of IL12B rs6871626 (CC 42%, AC 61%, AA 81%; p = 0.0052; odds ratio [OR] 2.45), as well as with the incidence of hypertension (p = 0.049; OR 1.82) and the proportion of patients who underwent aortic valve replacement (p = 0.023; OR 3.64). Regarding vascular damage, there was positive correlation between the Takayasu Arteritis Damage Score and the A allele of IL12B rs6871626 (CC 3.42 ± 2.71, AC 4.06 ± 3.25, AA 6.00 ± 2.81; p = 0.0035; β = 1.35) and between the Vasculitis Damage Index and the A allele (CC 3.47 ± 1.98, AC 4.33 ± 2.40, AA 5.37 ± 2.22; p = 0.0054; β = 0.96). Contrarily, no correlation was found between LILRA3 rs103294 and vascular damage. In the present study, IL12B rs6871626 was associated with vascular damage in TAK, whereas LILRA3 rs103294 was not. Genotyping of IL12B rs6871626 may help to identify patients at risk of disease progression.

Polymorphisms in TNFAIP3, but not in STAT4, BANK1, BLK, and TNFSF4, are associated with susceptibility to Takayasu arteritis

BACKGROUND

Takayasu arteritis (TAK) is considered a rare disease characterized by nonspecific inflammation of the large arteries, especially the aorta and its major branches. Because TAK is an autoimmune disease (AD), it could share susceptibility loci with other pathologies such as systemic lupus erythematosus (SLE), and rheumatoid arthritis (RA), among others. Widely explored polymorphisms in non-HLA genes, including TNFAIP3, STAT4, TNFSF4, BANK1, and BLK have been consistently associated with both SLE and RA, but they have not been evaluated in TAK.

OBJECTIVE

The aim of our study was to investigate whether TNFAIP3, STAT4, BANK1, BLK, and TNFSF4 polymorphisms are associated with susceptibility to TAK.

METHODS

The TNFAIP3 rs2230926T/G and rs5029924C/T, STAT4 rs7574865G/T, BANK1 10516487G/A, BLK rs2736340T/C, rs13277113A/G, and TNFS4 rs2205960G/T polymorphisms were genotyped in 101 cases and 276 controls by using a TaqMan SNP genotyping assay. An association analysis was performed.

RESULTS

The TNFAIP3 rs2230926T/G and rs5029924C/T polymorphisms were in complete linkage disequilibrium and turned out to be risk factors for TAK (OR = 4.88, p = 0.0001). The STAT4, BANK1, BLK, and TNFSF4 polymorphisms were not associated with the disease.

CONCLUSIONS

This is the first study documenting an association of TNFAIP3 rs2230926T/G and rs5029924C/T with TAK. Our results provide new information on the genetic bases of TAK.

Vasculitis therapy refines vasculitis mechanistic classification

The primary vasculitides constitute a heterogeneous group of immune mediated diseases of incompletely understood pathogenesis currently classified by the size of blood vessels affected (Chapel Hill classification). In recent years, several drugs with well-characterized immunological targets have been tested in clinical trials in large vessel vasculitis and small vessel vasculitis. Such trials provide "reverse translational" or bedside to bench information about underlying pathogenic mechanisms. Therefore, the aim of this systematic literature review was to examine the evidence base for a more refined mechanistic immunological classification of vasculitis. A total of 40 studies (20 randomized controlled trials (RCTs), 16 prospective studies, 1 retrospective cohort study and 3 case series) were included for full qualitative assessment. RCTs concerning biologic therapy for large vessel vasculitis mainly supports interleukin 6 receptor inhibition (tocilizumab). RCTs concerning biologic therapy for granulomatosis with polyangiitis and microscopic polyangiitis mainly support anti-CD20 treatment (rituximab) and complement inhibition with a small molecule C5a receptor antagonist (avacopan) is an emerging treatment option. The biologic treatment of eosinophilic granulomatosis with polyangiitis is centered around interleukin 5 inhibition (mepolizumab). Studies on tumor necrosis factor alpha inhibition (adalimumab, infliximab, and etanercept) showed negative results in giant cell arteritis but some effect in Takayasu arteritis. Taken together, clinical studies with cytokine and cell specific drugs are dissecting the heterogeneous immunopathogenic mechanisms of vasculitis and support a mechanistic immunological classification. Especially, cytokine antagonism is pointing towards immunological distinctions between eosinophilic granulomatosis with polyangiitis and granulomatosis with polyangiitis/microscopic polyangiitis and differences between giant cell arteritis and Takayasu arteritis.

Pathogenesis of liver injury in Takayasu arteritis: advanced understanding leads to new horizons

Liver injury in Takayasu arteritis (TA) is a rare phenomenon. Most symptoms are nonspecific, and the exact pathogenesis remains to be elucidated. Early diagnosis and new treatment methods are important for an improved prognosis. A summary of the clinical information and mechanistic analyses may contribute to making an early diagnosis and development of new treatment methods. A PubMed search was conducted using the specific key words “Takayasu arteritis” and “liver” or “hepatitis” or “hepatic”. Symptoms and treatment of TA with an accompanying liver injury were reviewed retrospectively. Many factors are presumed to be involved in the mechanism of TA with liver injury, including the immune response, genes, infections, and gut microbiota. There are several lines of evidence indicating that immune dysfunction is the main pathogenic factor that triggers granuloma formation in TA patients. However, the role of genetics and infections has not been fully confirmed. Recently, the gut microbiota has emerged as an essential component in the process. We reviewed in detail the current concepts that support the complex pathogenesis of TA accompanied by liver injury, and we presented recent theories from the literature. Finally, we discussed future research directions of liver injury in TA.

Cellular Signaling Pathways in Medium and Large Vessel Vasculitis

Autoimmune and autoinflammatory diseases of the medium and large arteries, including the aorta, cause life-threatening complications due to vessel wall destruction but also by wall remodeling, such as the formation of wall-penetrating microvessels and lumen-stenosing neointima. The two most frequent large vessel vasculitides, giant cell arteritis (GCA) and Takayasu arteritis (TAK), are HLA-associated diseases, strongly suggestive for a critical role of T cells and antigen recognition in disease pathogenesis. Recent studies have revealed a growing spectrum of effector functions through which T cells participate in the immunopathology of GCA and TAK; causing the disease-specific patterning of pathology and clinical outcome. Core pathogenic features of disease-relevant T cells rely on the interaction with endothelial cells, dendritic cells and macrophages and lead to vessel wall invasion, formation of tissue-damaging granulomatous infiltrates and induction of the name-giving multinucleated giant cells. Besides antigen, pathogenic T cells encounter danger signals in their immediate microenvironment that they translate into disease-relevant effector functions. Decisive signaling pathways, such as the AKT pathway, the NOTCH pathway, and the JAK/STAT pathway modify antigen-induced T cell activation and emerge as promising therapeutic targets to halt disease progression and, eventually, reset the immune system to reestablish the immune privilege of the arterial wall.

Pathogenesis of Giant Cell Arteritis and Takayasu Arteritis-Similarities and Differences

PURPOSE OF REVIEW

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are auto-inflammatory and autoimmune diseases with a highly selective tissue tropism for medium and large arteries. In both diseases, CD4⁺ T cells and macrophages form granulomatous lesions within the arterial wall, a tissue site normally protected by immune privilege. Vascular lesions can be accompanied by an extravascular component, typically an intense hepatic acute phase response that produces well-known laboratory abnormalities, e.g., elevated ESR and CRP. It is unclear whether GCA and TAK lie on a spectrum of disease or whether they represent fundamentally different disease processes.

RECENT FINDINGS

GCA and TAK share many clinical features, but there are substantial differences in genetics, epidemiology, disease mechanisms, response to treatment, and treatment complications that give rise to different disease trajectories. A significant difference lies in the composition of the wall-infiltrating immune cell compartment, which in TAK includes a significant population of CD8⁺ T cells as well as natural killer cells, specifying disparate disease effector pathways mediating tissue damage and vessel wall remodeling. Despite the similarities in tissue tropism and histomorphology, GCA and TAK are two distinct vasculitides that rely on separate disease mechanisms and require disease-specific approaches in diagnosis and management.

Long-term outcomes of refractory Takayasu arteritis patients treated with biologics including ustekinumab

OBJECTIVES

Biologics have been used to treat refractory Takayasu arteritis (TAK), but their efficacy and safety have not been sufficiently evaluated.

METHODS

We extracted clinical information from medical records for TAK patients who were treated with biologics including ustekinumab (UST) at Kyoto University Hospital. We also analysed the patient's genetic backgrounds.

RESULTS

Of 163 cases, 12 (7.4%) were treated with infliximab, tocilizumab, or UST (n = 3). Erythrocyte sedimentation rate (ESR), C-reactive protein levels (CRP), and prednisolone (PSL) dose were significantly decreased 12 months after the initiation of biologics. When compared with the 15 patients who were only treated with immunosuppressants (IS group), the change in ESR from baseline was significantly lower in the biologics group than in the IS group (-2 mm/h, p = .005). The proportion of patients with HLA-B*52 and the risk-type alleles of the SNP were similar in both groups. Among the biologics, TCZ showed the highest continuation rate. UST exhibited marginal effects on reducing ESR, CRP levels, and PSL dose. No adverse events were observed in patients with UST for approximately 3 years.

CONCLUSIONS

Biological treatments resulted in a reduction in inflammatory markers and PSL dose in refractory TAK patients.

Roles of cytotoxic lymphocytes and MIC/LILR families in pathophysiology of Takayasu arteritis

Takayasu arteritis (TAK) affects the aorta and its primary branches, mainly in young women. In its advanced stages, it can cause severe complications, such as cerebral infarction, impaired vision, and valvular heart diseases. In the aortic tissue of TAK, there is increased infiltration of cytotoxic lymphocytes, such as natural killer (NK) cells and CD8⁺T cells, and enhanced expression of accessory molecules, such as major histocompatibility complex (MHC) and MHC class I chain-related gene (MIC) family. Genome-wide association studies on TAK have identified susceptibility genes, such as IL-12p40, MICA, MICB, leukocyte immunoglobulin-like receptor A3 (LILRA3), and LILRB3. Other studies have also shown their involvement in the pathophysiology of TAK. In addition, we reported the importance of NK cells by enhancer enrichment analysis. These results suggest that the gene polymorphisms that potentially upregulate the expression of cytokines and accessory molecules, which contribute to the activation of cytotoxic lymphocytes, are associated with the development of TAK. Based on these results, new molecular targeted therapies look promising.

Family-based genome-wide association study of leprosy in Vietnam

Leprosy is a chronic infectious disease of the skin and peripheral nerves with a strong genetic predisposition. Recent genome-wide approaches have identified numerous common variants associated with leprosy, almost all in the Chinese population. We conducted the first family-based genome-wide association study of leprosy in 622 affected offspring from Vietnam, followed by replication in an independent sample of 1181 leprosy cases and 668 controls of the same ethnic origin. The most significant results were observed within the HLA region, in which six SNPs displayed genome-wide significant associations, all of which were replicated in the independent case/control sample. We investigated the signal in the HLA region in more detail, by conducting a multivariate analysis on the case/control sample of 319 GWAS-suggestive HLA hits for which evidence for replication was obtained. We identified three independently associated SNPs, two located in the HLA class I region (rs1265048: OR = 0.69 [0.58-0.80], combined p-value = 5.53x10-11; and rs114598080: OR = 1.47 [1.46-1.48], combined p-value = 8.77x10-13), and one located in the HLA class II region (rs3187964 (OR = 1.67 [1.55-1.80], combined p-value = 8.35x10-16). We also validated two previously identified risk factors for leprosy: the missense variant rs3764147 in the LACC1 gene (OR = 1.52 [1.41-1.63], combined p-value = 5.06x10-14), and the intergenic variant rs6871626 located close to the IL12B gene (OR = 0.73 [0.61-0.84], combined p-value = 6.44x10-8). These results shed new light on the genetic control of leprosy, by dissecting the influence of HLA SNPs, and validating the independent role of two additional variants in a large Vietnamese sample.

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.

mTOR pathway activation in large vessel vasculitis

BACKGROUND

Mammalian target of rapamycin complex 1 (mTORC 1) drives the proinflammatory expansion of T helper (TH) type 1, TH17 cells and controls fibroblast proliferation, typical features of large vessel vasculitis (LVV) pathogenesis. Molecular pathways involved in arterial lesions of LVV are unknown.

METHODS

We evaluate mTORC pathway activation in vascular aorta lesions and in T cell homeostasis of patients with LVV.

RESULTS

Proliferation of both endothelial cells and vascular smooth-muscle cells was shown in vascular lesions in LVV. The vascular endothelium of proliferating aorta vessels from patients with LVV showed indications of activation of the mTORC1 pathway (S6RP phosphorylation). In cultured vascular endothelial cells, sera from patients with LVV stimulated mTORC1 through the phosphorylation of S6RP. mTORC1 activation was found also in Th1 and Th17 cells both systemically and in inflamed vessels. Patients with LVV exhibited a diminished S6RP phosphorylation in Tregs. Inhibition of mTORC1 pathway with rapamycin, increase Tregs and decrease effector CD4⁺IFNγ⁺, CD4⁺IL17⁺ and CD4⁺IL21⁺ T cells in patients with LVV.

CONCLUSIONS

We provided evidence that mTORC1 pathway has a central role in driving T cell inflammation and vascular lesions in LVV. Targeting mTORC pathway may represent a new therapeutic option in patients with LVV.

How to conduct research of rare autoimmune diseases

Rare autoimmune diseases are difficult to conduct researches in spite of present era with advanced scientific progress. Research using genetic approach is a promising way since genetic findings implicate causality of diseases. Still, there are multiple obstacles preventing genetic studies of rare diseases. Here, we list up the problems and propose solutions for them with detailed examples. The biggest problem is that it is difficult to collect a substantial number of DNA samples from patients with rare diseases. We propose to collaborate not only with academic institutions and hospitals but with patients' groups. Detailed examples include studies about Takayasu arteritis (TAK), relapsing polychondritis, and systemic sclerosis. In TAK, we identified IL12B, a key gene which seems to play a central role in the disease. After getting evidence of IL12p40 encoded by IL12B as a possible therapeutic target by showing similarities of the genetic background between TAK and ulcerative colitis, we performed a pilot clinical study of ustekinumab, a monoclonal antibody against IL12p40 for patients with refractory TAK and obtained good response. This is a good example of how genetic findings in a rare disease lead to development of new therapeutic option.

Biological treatments in giant cell arteritis & Takayasu arteritis

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are the two main large vessel vasculitides. They share some similarities regarding their clinical, radiological and histological presentations but some pathogenic processes in GCA and TAK are activated differently, thus explaining their different sensitivity to biological therapies. The treatment of GCA and TAK essentially relies on glucocorticoids. However, thanks to major progress in our understanding of their pathogenesis, the role of biological therapies in the treatment of these two vasculitides is expanding, especially in relapsing or refractory diseases. In this review, the efficacy, the safety and the limits of the main biological therapies ever tested in GCA and TAK are discussed. Briefly, anti TNF-α agents appear to be effective in treating TAK but not GCA. Recent randomized placebo-controlled trials have reported on the efficacy and safety of abatacept and mostly tocilizumab in inducing and maintaining remission of GCA. Abatacept was not effective in TAK and robust data are still lacking to draw any conclusions concerning the use of tocilizumab in TAK. Furthermore, ustekinumab appears promising in relapsing/refractory GCA whereas rituximab has been reported to be effective in only a few cases of refractory TAK patients. If a biological therapy is indicated, and in light of the data discussed in this review, the first choice would be tocilizumab in GCA and anti-TNF-α agents (mainly infliximab) in TAK.