Genomic atlas of the human plasma proteome.

Although plasma proteins have important roles in biological processes and are the direct targets of many drugs, the genetic factors that control inter-individual variation in plasma protein levels are not well understood. Here we characterize the genetic architecture of the human plasma proteome in healthy blood donors from the INTERVAL study. We identify 1,927 genetic associations with 1,478 proteins, a fourfold increase on existing knowledge, including trans associations for 1,104 proteins. To understand the consequences of perturbations in plasma protein levels, we apply an integrated approach that links genetic variation with biological pathway, disease, and drug databases. We show that protein quantitative trait loci overlap with gene expression quantitative trait loci, as well as with disease-associated loci, and find evidence that protein biomarkers have causal roles in disease using Mendelian randomization analysis. By linking genetic factors to diseases via specific proteins, our analyses highlight potential therapeutic targets, opportunities for matching existing drugs with new disease indications, and potential safety concerns for drugs under development.

Association of Glutathione Transferase M1, T1, P1 and A1 Gene Polymorphism and Susceptibility to IgA Vasculitis.

Endothelial cell injury is a hallmark of IgA vasculitis (IgAV), possibly associated with various factors, including oxidative stress. Certain single nucleotide polymorphisms (SNPs) of glutathione S-transferases (GST) genes have been shown to increase susceptibility to oxidative stress. The objective of our study was to evaluate the gene polymorphisms of GSTM1, GSTT1, GSTP1, and GSTA1 in patients with IgAV. DNA was extracted from the blood of 124 children with IgAV and 168 age-matched healthy controls. A higher frequency of the GSTM1 null genotype was observed in patients with gastrointestinal (GI) system involvement compared to those without GI system involvement (51.5% vs. 28.6%, p = 0.011). Additionally, the GSTM1 null genotype was less prevalent (30.8% vs. 69.2%, p = 0.032), while the GSTP1 Val/Val genotype was significantly more prevalent in patients who developed urogenital complications (scrotal swelling) during the course of the disease (60% vs. 40%, p = 0.039). This study is the first to suggest an association between GSTM1 and GSTP1 polymorphisms and various phenotypes observed during the clinical course of IgAV in the pediatric population. However, it was performed on a national and likely single ethnic cohort, too small for definitive conclusions, so larger studies are needed to confirm this association.

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.

Early-onset pulmonary and cutaneous vasculitis driven by constitutively active SRC-family kinase HCK.

BACKGROUND: Inborn errors of immunity are genetic disorders characterized by various degrees of immune dysregulation that can manifest as immune deficiency, autoimmunity, or autoinflammation. The routine use of next-generation sequencing in the clinic has facilitated the identification of an ever-increasing number of inborn errors of immunity, revealing the roles of immunologically important genes in human pathologies. However, despite this progress, treatment is still extremely challenging. OBJECTIVE: We sought to report a new monogenic autoinflammatory disorder caused by a de novo activating mutation, p.Tyr515∗, in hematopoietic cell kinase (HCK). The disease is characterized by cutaneous vasculitis and chronic pulmonary inflammation that progresses to fibrosis. METHODS: Whole-exome sequencing, Sanger sequencing, mass spectrometry, and western blotting were performed to identify and characterize the pathogenic HCK mutation. Dysregulation of mutant HCK was confirmed ex vivo in primary cells and in vitro in transduced cell lines. RESULTS: Mutant HCK lacking the C-terminal inhibitory tyrosine Tyr522 exhibited increased kinase activity and enhanced myeloid cell priming, migration and effector functions, such as production of the inflammatory cytokines IL-1ß, IL-6, IL-8, and TNF-α, and production of reactive oxygen species. These aberrant functions were reflected by inflammatory leukocyte infiltration of the lungs and skin. Moreover, an overview of the clinical course of the disease, including therapies, provides evidence for the therapeutic efficacy of the Janus kinase 1/2 inhibitor ruxolitinib in inflammatory lung disease. CONCLUSIONS: We propose HCK-driven pulmonary and cutaneous vasculitis as a novel autoinflammatory disorder of inborn errors of immunity.

Hematological and Genetic Markers in the Rational Approach to Patients With HCV Sustained Virological Response With or Without Persisting Cryoglobulinemic Vasculitis.

BACKGROUND AND AIMS: Direct-acting antivirals (DAAs) usually lead to improvement/remission of cryoglobulinemic vasculitis (CV), although symptoms may persist/recur after a sustained virological response (SVR). We evaluated hematological and genetic markers in patients with HCV-SVR vasculitis with and without persisting/recurring symptoms to early predict the CV outcome. APPROACH AND RESULTS: Ninety-eight patients with HCV-CV were prospectively enrolled after a DAA-induced SVR: Group A: 52 with complete clinical response; Group B: 46 with symptom maintenance/recurrence. Monoclonal B-cell lymphocytosis, t(14;18) translocation, and abnormal free light chains κ/λ ratios were detected by flow cytometry or nested-PCR or nephelometry in 4% Group A versus 17% Group B (P = 0.04) patients, 17% Group A versus 40% Group B patients (P = 0.02), and 17% Group A versus 47% Group B (P = 0.003) patients, respectively. At least 1 out of 3 clonality markers was altered/positive in 29% of Group A versus 70% of Group B patients (P < 0.0001). When available, pretherapy samples were also tested for t(14;18) translocation (detected in 12/37 [32%] Group A and 21/38 [55%] Group B) and κ/λ ratios (abnormal in 5/35 [14%] Group A and 20/38 [53%] Group B) (P = 0.0006), whereas at least one clonality marker was detected/altered in 16/37 (43%) Group A and 30/38 (79%) Group B (P = 0.002). CV-associated single-nucleotide polymorphisms were tested by real-time PCR. Among them, notch4 rs2071286 T minor allele and TT genotype showed a higher frequency in Group B versus Group A (46% vs. 29%, P = 0.01, and 17% vs. 2%, P = 0.006, respectively). CONCLUSIONS: Hematological or genetic analyses could be used to foresee the CV clinical response after DAA therapy and could be valuable to assess a rational flowchart to manage CV during follow-up.

B-cell activating factor (BAFF), BAFF promoter and BAFF receptor allelic variants in hepatitis C virus related Cryoglobulinemic Vasculitis and Non-Hodgkin's Lymphoma.

Cryoglobulinemic Vasculitis (CV) is an autoimmune/lymphoproliferative disorder associated with HCV infection that in 5%-10% of cases evolves into a B cell Non-Hodgkin's Lymphoma (NHL). B-cell activating factor (BAFF) is a key regulator in B-cell development and survival. Particular genetic variants are responsible for BAFF signaling impairment in autoimmune and neoplastic diseases. We evaluated BAFF and BAFF-receptor (BAFF-R) polymorphisms in order to determine if they predispose to HCV-related CV and NHL. The analysis was performed on 416 HCV-chronically infected patients: 136 HCV without signs/symptoms of lymphoproliferations/autoimmunity (HCV), 166 HCV with CV (HCV-CV) and 114 HCV with NHL (HCV-NHL). Rs9514828 SNP on BAFF promoter, rs61756766 on BAFF-R and rs12428930 on the BAFF gene were evaluated by Real-Time PCR. Concerning rs9514828, the frequency of C/T genotype was significantly higher in HCV-CV than in HCV. The difference in the distribution of the T/T mutant genotype in HCV-CV compared to HCV was significant as well as the distribution of C/T and T/T genotype in HCV-NHL versus HCV. T minor allele was more frequent in HCV-NHL and HCV-CV than in HCV. The distribution of C/T + T/T (for the dominant model of penetrance C/T + T/T vs. C/C) was significantly higher in HCV-CV and HCV-NHL than in HCV. Genotyping of rs61756766 on BAFF-R coding gene, revealed C/T heterozygosis at a frequency of 11% in HCV-NHL versus 3% in HCV. The T minor allele frequency was higher in HCV-NHL than in HCV. No differences emerged by genotyping rs12428930 SNP on BAFF coding gene. Our results reinforce the hypothesis that BAFF/BAFF-R genetic pattern has a role in the pathogenesis of HCV-related lymphoproliferations. BAFF/BAFF-R variants could identify a risk haplotype for HCV related CV and NHL and a BAFF/BAFF-R genetic profile assessment could potentially contribute to tailoring anti-BAFF therapy by identifying patients with BAFF alterations in which the treatment could be more beneficial.

LncRNA-MAP3K4 regulates vascular inflammation through the p38 MAPK signaling pathway and cis-modulation of MAP3K4.

Chronic vascular inflammation plays a key role in the pathogenesis of atherosclerosis. Long non-coding RNAs (lncRNAs) have emerged as essential inflammation regulators. We identify a novel lncRNA termed lncRNA-MAP3K4 that is enriched in the vessel wall and regulates vascular inflammation. In the aortic intima, lncRNA-MAP3K4 expression was reduced by 50% during the progression of atherosclerosis (chronic inflammation) and 70% during endotoxemia (acute inflammation). lncRNA-MAP3K4 knockdown reduced the expression of key inflammatory factors (eg, ICAM-1, E-selectin, MCP-1) in endothelial cells or vascular smooth muscle cells and decreased monocytes adhesion to endothelium, as well as reducing TNF-α, IL-1ß, COX2 expression in macrophages. Mechanistically, lncRNA-MAP3K4 regulates inflammation through the p38 MAPK signaling pathway. lncRNA-MAP3K4 shares a bidirectional promoter with MAP3K4, an upstream regulator of the MAPK signaling pathway, and regulates its transcription in cis. lncRNA-MAP3K4 and MAP3K4 show coordinated expression in response to inflammation in vivo and in vitro. Similar to lncRNA-MAP3K4, MAP3K4 knockdown reduced the expression of inflammatory factors in several different vascular cells. Furthermore, lncRNA-MAP3K4 and MAP3K4 knockdown showed cooperativity in reducing inflammation in endothelial cells. Collectively, these findings unveil the role of a novel lncRNA in vascular inflammation by cis-regulating MAP3K4 via a p38 MAPK pathway.

The Immunogenetics of Vasculitis.

Vasculitides are a cluster of diseases defined by an immune attack targeting vessels of different sizes. While most types of vasculitis have an undetermined cause, progress has been achieved in the recent decade in elucidating the mechanisms that participate in the inflammatory damage of the blood vessel wall. Several studies have emphasized that genetic susceptibility is an important aspect of the pathogenesis of vasculitides. The most prominent genetic risk loci for vasculitides reside within the major histocompatibility complex region. This indicates that the immune system is a major contributor to the pathogenesis of this group of diseases. In this chapter, we provide an updated overview of the etiology and pathogenesis of these entities with an emphasis on the major insights gained from recent genetic studies in the highly studied types of vasculitides.

Missing Self-Induced Microvascular Rejection of Kidney Allografts: A Population-Based Study.

BACKGROUND: Circulating anti-HLA donor-specific antibodies (HLA-DSA) are often absent in kidney transplant recipients with microvascular inflammation (MVI). Missing self, the inability of donor endothelial cells to provide HLA I-mediated signals to inhibitory killer cell Ig-like receptors (KIRs) on recipient natural killer cells, can cause endothelial damage in vitro, and has been associated with HLA-DSA-negative MVI. However, missing self's clinical importance as a nonhumoral trigger of allograft rejection remains unclear. METHODS: In a population-based study of 924 consecutive kidney transplantations between March 2004 and February 2013, we performed high-resolution donor and recipient HLA typing and recipient KIR genotyping. Missing self was defined as the absence of A3/A11, Bw4, C1, or C2 donor genotype, with the presence of the corresponding educated recipient inhibitory KIR gene. RESULTS: We identified missing self in 399 of 924 transplantations. Co-occurrence of missing self types had an additive effect in increasing MVI risk, with a threshold at two concurrent types (hazard ratio [HR], 1.78; 95% confidence interval [95% CI], 1.26 to 2.53), independent of HLA-DSA (HR, 5.65; 95% CI, 4.01 to 7.96). Missing self and lesions of cellular rejection were not associated. No HLA-DSAs were detectable in 146 of 222 recipients with MVI; 28 of the 146 had at least two missing self types. Missing self associated with transplant glomerulopathy after MVI (HR, 2.51; 95% CI, 1.12 to 5.62), although allograft survival was better than with HLA-DSA-associated MVI. CONCLUSION: Missing self specifically and cumulatively increases MVI risk after kidney transplantation, independent of HLA-DSA. Systematic evaluation of missing self improves understanding of HLA-DSA-negative MVI and might be relevant for improved diagnostic classification and patient risk stratification.

Deficiency in the frequency and function of Tr1 cells in IgAV and the possible role of IL-27.

OBJECTIVE: Type 1 regulatory T (Tr1) cells are involved in the pathogenesis of numerous immune-mediated diseases. However, little is known about whether and how Tr1 cells affect the development of IgA vasculitis (IgAV). We aimed to investigate this question in IgAV patients. METHODS: . Tr1 cells in peripheral blood and kidney tissue of IgAV patients were analysed by multi-parametric flow cytometry and immunofluorescence techniques. An in vitro assay of suppression of T cell proliferation and cytokine release was performed to evaluate the function of Tr1 cells. Real-time PCR and cell stimulation in vitro were used to explore the roles of IL-27 and early growth response gene 2 (EGR2). RESULTS: The frequency of Tr1 cells was decreased in peripheral blood but increased in kidney tissue from IgAV patients. A defective suppressive function of Tr1 cells in IgAV was observed. The frequency of Tr1 cells and the cytokines secreted by them were up-regulated in the presence of recombinant IL-27 in vitro. Moreover, IL-27 also increased the expression of EGR2. Furthermore, lower frequency of Tr1 cells during remission had a higher recurrence rate. CONCLUSION: Tr1 cells are involved in the pathogenesis of IgAV. The low IL-27 in IgAV is responsible for impaired frequency and function of Tr1 cells, and EGR2 may be the specific transcription factor involved in the progression. Tr1 may be a risk factor for IgAV recurrence.

A Pooled Study of Angiotensin-Converting Enzyme Insertion/Deletion Gene Polymorphism in Relation to Risk, Pathology and Prognosis of Childhood Immunoglobulin A Vasculitis Nephritis.

The angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism has been inconsistently reported to be a risk factor for Childhood immunoglobulin A vasculitis (IgAV) nephritis. We comprehensively searched electronic databases as of Jan 2020. Nineteen studies with 1104 cases and 1589 controls were included. Sensitivity analyses based on different subgroups were performed. Further analyses were conducted for association of ACE polymorphism with disease severity and prognosis. Significant associations were found between ACE I/D polymorphism and childhood IgAV nephritis, with the strongest association in DD vs. II comparison (OR 1.72, 95% CI 1.21-2.46). Subgroup analyses generally showed significant results. Besides, ACE polymorphism was significantly associated with proteinuria (DD + DI vs. II: OR 2.22, 95% CI 1.14-4.33; DI + II vs. DD: OR 0.49, 95% CI 0.30-0.81) and worse prognosis (the strongest effect in DD + DI vs. II: OR 4.43, 95% CI 1.84-10.71) among children with IgAV nephritis. The ACE polymorphism seemed not to be associated with hematuria, hypertension, and renal pathology. This study suggested significant association of ACE gene polymorphism with the risk of IgAV nephritis in children. D allele in the ACE genotype could be a useful genetic marker to predict proteinuria and worse prognosis for childhood IgAV nephritis.

Genotype and functional correlates of disease phenotype in deficiency of adenosine deaminase 2 (DADA2).

BACKGROUND: Deficiency of adenosine deaminase 2 (DADA2) is a syndrome with pleiotropic manifestations including vasculitis and hematologic compromise. A systematic definition of the relationship between adenosine deaminase 2 (ADA2) mutations and clinical phenotype remains unavailable. OBJECTIVE: We sought to test whether the impact of ADA2 mutations on enzyme function correlates with clinical presentation. METHODS: Patients with DADA2 with severe hematologic manifestations were compared with vasculitis-predominant patients. Enzymatic activity was assessed using expression constructs reflecting all 53 missense, nonsense, insertion, and deletion genotypes from 152 patients across the DADA2 spectrum. RESULTS: We identified patients with DADA2 presenting with pure red cell aplasia (n = 5) or bone marrow failure (BMF, n = 10) syndrome. Most patients did not exhibit features of vasculitis. Recurrent infection, hepatosplenomegaly, and gingivitis were common in patients with BMF, of whom half died from infection. Unlike patients with DADA2 with vasculitis, patients with pure red cell aplasia and BMF proved largely refractory to TNF inhibitors. ADA2 variants associated with vasculitis predominantly reflected missense mutations with at least 3% residual enzymatic activity. In contrast, pure red cell aplasia and BMF were associated with missense mutations with minimal residual enzyme activity, nonsense variants, and insertions/deletions resulting in complete loss of function. CONCLUSIONS: Functional interrogation of ADA2 mutations reveals an association of subtotal function loss with vasculitis, typically responsive to TNF blockade, whereas more extensive loss is observed in hematologic disease, which may be refractory to treatment. These findings establish a genotype-phenotype spectrum in DADA2.

A monogenic autoinflammatory disease with fatal vasculitis: deficiency of adenosine deaminase 2.

PURPOSE OF REVIEW: To recap the expanding clinical spectrum, genotype-phenotype associations and treatment options in the light of recently published articles regarding the deficiency of adenosine deaminase 2 (DADA2). RECENT FINDINGS: Whole-exome sequencing enabled novel clinical phenotypes associated with ADA2 mutations. Since its discovery, the phenotypic spectrum of DADA2 has substantially expanded to cover Diamond-Blackfan anaemia, cytopenia and immunodeficiency syndromes. In addition to elevated TNF alpha levels, increased levels of interferon-stimulated genes were also detected in patients with DADA2. Given the absence of clinical trials until now, no standard treatment strategy exists for DADA2. Currently, anti-TNF alpha agents are the mainstay of treatment, based on the data both from the initial two reports and from subsequent studies. However, it is still unclear how to manage asymptomatic patients with ADA2 mutation and/or with absent ADA2 activity and what is the optimal duration of anti-TNF therapy. SUMMARY: Among a total of 206 DADA2 patients described so far, the overall mortality was found as 8.3%. Biallelic homozygous G47R mutations were mostly associated with a vascular phenotype, whereas patients with homozygous R169Q mutations seem to display a mixed clinical phenotype including vascular, haematological and immunological manifestations. HSCT should be reserved as a curative treatment option for DADA2 patients unresponsive to the anti-TNF therapy, as it carries a significant morbidity.

ADA2 Deficiency: Case Series of Five Patients with Varying Phenotypes.

OBJECTIVE: To describe the clinical features, genotype, and treatment approaches of patients with confirmed adenosine deaminase 2 (ADA2) deficiency with dissimilar phenotypes. METHODS: A case series of five DADA2 patients from three families was presented. The clinical and laboratory data, treatment protocols, and outcome of the patients were recorded from the patients' medical charts. ADA2 gene was screened by next generation sequencing first and then verified by Sanger sequencing. Serum ADA2 enzyme activity was measured by modified spectrophotometric method. RESULTS: The median (min-max) age at onset of symptoms and age at diagnosis were 11 (9-13.8) years and 15 (9-19) years, respectively. The median (min-max) follow-up period was 8 (6-45) months. There was consanguinity in two families (2/3). The main clinical manifestations are musculoskeletal (5/5), dermatological (4/5), and neurological (2/5). Homozygosity for the p.G47R mutation in ADA2 gene was detected in three patients. A homozygous mutation in ADA2 gene (c.650 T > A; p.Val217Asp) was detected in two siblings. Plasma ADA2 enzymatic activity was absent in all patients. Anti-tumor necrosis factor (TNF) therapy was commenced, and all patients became clinically inactive with normal acute-phase reactants. CONCLUSION: ADA2 mutations should be checked in patients with presence of inflammation and livedoid vasculitis when they have neurological findings, especially in the form of stroke; and a history suggesting for an inherited disease; or presence of resistance to conventional treatment. Besides, anti-TNF seems to be useful for treatment of DADA2.

Platelet-derived calpain cleaves the endothelial protease-activated receptor 1 to induce vascular inflammation in diabetes.

Diabetes mellitus is a major risk factor for cardiovascular disease. Platelets from diabetic patients are hyperreactive and release microparticles that carry activated cysteine proteases or calpains. Whether platelet-derived calpains contribute to the development of vascular complications in diabetes is unknown. Here we report that platelet-derived calpain1 (CAPN1) cleaves the protease-activated receptor 1 (PAR-1) on the surface of endothelial cells, which then initiates a signaling cascade that includes the activation of the tumor necrosis factor (TNF)-α converting enzyme (TACE). The latter elicits the shedding of the endothelial protein C receptor and the generation of TNF-α, which in turn, induces intracellular adhesion molecule (ICAM)-1 expression to promote monocyte adhesion. All of the effects of CAPN1 were mimicked by platelet-derived microparticles from diabetic patients or from wild-type mice but not from CAPN1-/- mice, and were not observed in PAR-1-deficient endothelial cells. Importantly, aortae from diabetic mice expressed less PAR-1 but more ICAM-1 than non-diabetic mice, effects that were prevented by treating diabetic mice with a calpain inhibitor as well as by the platelet specific deletion of CAPN1. Thus, platelet-derived CAPN1 contributes to the initiation of the sterile vascular inflammation associated with diabetes via the cleavage of PAR-1 and the release of TNF-α from the endothelial cell surface.

Prolyl Hydroxylase Domain-2 Protein Regulates Lipopolysaccharide-Induced Vascular Inflammation.

Acute lung injury and its more severe form, acute respiratory distress syndrome, are life-threatening respiratory disorders. Overwhelming pulmonary inflammation and endothelium disruption are commonly observed. Endothelial cells (ECs) are well recognized as key regulators in leukocyte adhesion and migration in response to bacterial infection. Prolyl hydroxylase domain (PHD)-2 protein, a major PHD in ECs, plays a critical role in intracellular oxygen homeostasis, angiogenesis, and pulmonary hypertension. However, its role in endothelial inflammatory response is unclear. We investigated the role of PHD2 in ECs during endotoxin-induced lung inflammatory responses with EC-specific PHD2 inducible knockout mice. On lipopolysaccharide challenge, PHD2 depletion in ECs attenuates lipopolysaccharide-induced increases of lung vascular permeability, edema, and inflammatory cell infiltration. Moreover, EC-specific PHD2 inducible knockout mice exhibit improved adherens junction integrity and endothelial barrier function. Mechanistically, PHD2 knockdown induces vascular endothelial cadherin in mouse lung microvascular primary endothelial cells. Moreover, PHD2 knockdown can increase hypoxia-inducible factor/vascular endothelial protein tyrosine phosphatase signaling and reactive oxygen species-dependent p38 activation, leading to the induction of vascular endothelial cadherin. Data indicate that PHD2 depletion prevents the formation of leaky vessels and edema by regulating endothelial barrier function. It provides direct in vivo evidence to suggest that PHD2 plays a pivotal role in vascular inflammation. The inhibition of endothelial PHD2 activity may be a new therapeutic strategy for acute inflammatory diseases.

Role of IRF5 in the pathogenesis of immunoglobulin-A vasculitis.

OBJECTIVES: Interferon regulatory factor 5 (IRF5) is a major regulator of type I interferon induction and is also critical to produce pro-inflammatory cytokines. An influence of IRF5 genetic variants on the increased risk of immune-mediated diseases has been described. Accordingly, we aimed to evaluate the implication of IRF5 in the pathogenesis of Immunoglobulin-A vasculitis (IgAV), an inflammatory vascular pathology. METHODS: Three tag genetic variants (rs2004640, rs2070197 and rs10954213), representative of 3 different haplotype blocks within IRF5, were genotyped in 372 Caucasian patients with IgAV and 876 sex and ethnically matched healthy controls by TaqMan assays. RESULTS: No significant differences in the genotype and allele frequencies between patients with IgAV and healthy controls were observed when each IRF5 polymorphism was evaluated independently. Likewise, no significant differences between patients with IgAV and healthy controls were found when we assessed the three IRF5 polymorphisms combined, conforming haplotypes. In addition, there were no significant differences in genotype, allele and haplotype frequencies of IRF5 when patients with IgAV were stratified according to the age at disease onset or to the presence/absence of gastrointestinal or renal manifestations. CONCLUSIONS: Our results do not support an influence of IRF5 on the pathogenesis of IgAV.

Influence of IL17A gene on the pathogenesis of immunoglobulin-A vasculitis.

OBJECTIVES: Cytokines signaling pathway genes represent a key component of the genetic network implicated in the pathogenesis of immunoglobulin-A vasculitis (IgAV), an inflammatory vascular pathology. Interleukin (IL)17A is described as a genetic risk locus for some autoimmune diseases, such as giant cell arteritis and spondyloarthritis. Accordingly, we aimed to determine the potential influence of IL17A on the pathogenesis of IgAV. METHODS: Five IL17A tag polymorphisms (rs4711998, rs8193036, rs3819024, rs2275913 and rs7747909), which cover the major variability of this gene, were genotyped in 360 Caucasian patients with IgAV and 1,003 sex and ethnically matched healthy controls using TaqMan probes. RESULTS: No statistically significant differences between patients with IgAV and healthy controls were observed when each IL17A genetic variant was analysed independently. Similarly, no statistically significant differences between patients with IgAV and healthy controls were found when the five IL17A polymorphisms were evaluated combined conforming haplotypes. In addition, there were no statistically significant differences in genotype, allele and haplotype frequencies of IL17A when patients with IgAV were stratified according to the age at disease onset or to the presence/absence of gastrointestinal or renal manifestations. CONCLUSIONS: Our results do not support an influence of IL17A on the pathogenesis of IgAV.

Variation in complement factor H affects complement activation in immunoglobulin A vasculitis with nephritis.

BACKGROUND: Immunoglobulin A (IgA) vasculitis with nephritis (IgAVN) and IgA nephropathy (IgAN) are widely considered as related diseases. Considerable evidences support the notion of involvement of complement activation in both IgAVN and IgAN. Our previous studies identified a genetic variant in complement factor H (CFH), rs6677604, as an IgAN-susceptible variant by genome-wide association study, and further confirmed its linkage to CFHR3-1Δ and proved its influence on complement activation and thereby on IgAN susceptibility. AIM: To explore the role of rs6677604 in complement activation of IgAVN. METHODS: In this study, we enrolled 632 patients with IgAVN, 1178 patients with IgAN and 902 healthy controls. The genotype of rs6677604 was measured by TaqMan allele discrimination assays or was extracted from genome-wide association study data. RESULTS: The frequency of the rs6677604-A allele was significantly higher in IgAVN than in IgAN. However, no significant differences were observed between IgAVN and the controls. Higher complement factor H (FH) levels were observed in IgAVN than IgAN, and positive correlation between circulating FH and C3 levels was present in IgAVN. In both IgAVN and IgAN, rs6677604-A was associated with less intensity of glomerular C3 deposits. In agreement with the higher frequency of rs6677604-A in IgAVN, the glomerular C3 deposits of patients with IgAVN were less intense than those in IgAN. CONCLUSION: Our findings suggest that genetic variation in CFH (rs6677604) is involved in the phenotype of complement activation in both IgAVN and IgAN. Moreover, rs6677604 might contribute to the difference of complement activation intensity between IgAVN and IgAN.

Platelet-neutrophil interaction aggravates vascular inflammation and promotes the progression of atherosclerosis by activating the TLR4/NF-κB pathway.

Platelet-neutrophil interaction is well known for its role in inflammatory diseases; however, its biological role in atherosclerosis (AS) progression remains unclear. Human peripheral blood neutrophils were obtained to compare toll-like receptor 4 (TLR4), tumor necrosis factor α (TNF-α), interleukin (IL)-1ß and myeloid-related proteins 8/14 (Mrp8/14) levels in 22 AS patients with those in 18 healthy controls using quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA). Meanwhile, mouse marrow neutrophils subjected to different treatment were collected for the ELISA assay, cell apoptosis, and Western blot analysis. Normal diet or high-fat diet ApoE-/- mice with or without administration of Mrp8/14 antagonist paquinimod were used for plasma collection to measure total cholesterol, triglycerides, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol, TNF-α, IL-1ß, Mrp8/14, TLR4, and nuclear factor (NF)-κB p65 levels. The results showed that Mrp8/14 and TLR4-mediated inflammatory pathway was activated in neutrophils of AS patients. In vitro experiments demonstrated that platelet-neutrophil interaction promoted the Mrp8/14 release and inhibited neutrophil apoptosis via P-selectin. Furthermore, platelet-neutrophil interaction upregulated TLR4/myeloid differentiation factor 88/NF-κB pathway. Conversely, Mrp8/14/TLR4/NF-κB interference alleviated AS progression. In conclusion, Mrp8/14/TLR4/NF-κB activated by platelet-neutrophil interaction is an important inflammatory signaling pathway for AS pathogenesis.