Serum levels of selected cytokines [interleukin (IL)-17A, IL-18, IL-23] and chemokines (RANTES, IP10) in the acute phase of immunoglobulin A vasculitis in children

Study on the correlation between intestinal flora and cytokines in children with Henoch-Schönlein purpura

BACKGROUND

The pathogenesis of Henoch-Schönlein purpura (HSP) is complex. It is currently believed that the development of HSP involves abnormalities in humoral immunity and cellular immunity. The intestinal microbiota has a powerful regulatory effect on the human immune system and has been shown to serve a significant role in the pathogenesis of various immune-mediated disorders. This study examines changes in intestinal flora and cytokines(IFN-γ, IL-4, IL-10, and IL-17) in children with HSP and explores their correlation, offering fresh insights for the prevention and treatment of HSP.

METHODS

Blood and stool specimens were collected from 25 healthy children (control group) and 27 children with HSP (observation group). Enzyme-linked immunosorbent assay(ELISA) was used to detect the levels of cytokines IFN-γ, IL-4, IL-17, and IL-10 in the serum of all the study participants, and the 16S rRNA gene sequencing combined with high-throughput sequencing technology was used to analyze the intestinal flora of the study subjects. Finally, the correlation between serum cytokines and gut microbiota was analyzed in the children with HSP.

RESULT

1)The serum levels of IL-4 and IL-17 in the observation group were higher than those in the control group, while the levels of IFN-γ and IL-10 were lower than those in the control group. 2) At the level of phylum, the abundance of Fusobacteria and Verrucomicrobia was higher than that in the control group, while the abundance of Firmicutes was lower than that of the control group, and the differences were statistically significant (P < 0.05); At the level of genus, the abundance of Prevotella and Akkermansia were higher than the control group, while the abundance of Bifidobacterium, Blautia, and Clostridium XlVa was lower than that in the control group, and the differences were all statistically significant (P < 0.05); At the species level, the abundance of Akkermansia muciniphila, Prevotella copri, and Subdoligranulum variabile was higher than that of the control group, while the abundance of Bifidobacterium pseudolongum, Brautella Weiss, and Bacteroides fragilis was lower than that in the control group, and the differences were statistically significant (P < 0.05). 3) The abundance of Blautia and Blautia wexlerae in the observation group was positively associated with the IL-10 level (r = 0.522, r = 0.578, P < 0.01).

CONCLUSION

Disturbances in intestinal flora and changes in serum cytokines IFN-γ, IL-4, IL-10, and IL-17 were present in children with HSP. The abundance of Blautia and Blautia wexlerae in the gut microbiota of children with HSP was positively correlated with serum IL-10 levels.

Deciphering the Pharmacological Mechanism of Compound Purpura Decoction in Treating Henoch-Schonlein Purpura by Network Pharmacology, Molecular Docking and Experimental Validation

Henoch-Schonlein purpura (HSP) is an immunoglobulin A (IgA)-mediated systemic vasculitis that frequently develops in children and may progress to serious complications. Compound purpura decoction (CPD), a classical herbal combination, exerts favourable effects on the clinical symptoms and prognosis of HSP; however, the underlying molecular mechanism remains unclear. First, high-performance liquid chromatography analysis identified five bioactive components in CPD, including protocatechuic acid, chlorogenic acid, mangiferin, baicalin and buddleoside, with contents of 0.011 ± 0.02, 0.577 ± 0.33, 0.150 ± 0.05, 1.132 ± 0.23 and 0.369 ± 0.23 mg/g, respectively. Additionally, we established an animal model of allergic purpura to evaluate the therapeutic effects of CPD on HSP. CPD effectively alleviated renal and cutaneous vasculitis and reduced IgA deposition. CPD could regulate the Treg/Th17 cell balance, decrease the levels of the proinflammatory factors interleukin-6 and tumour necrosis factor-α, and suppress the expression of C3 and C5 (p < 0.05). Network pharmacology analysis suggested that the mechanism of CPD in HSP treatment mainly involved epidermal growth factor receptor (EGFR)-related targets and pathways, followed by molecular docking confirming strong binding affinity between EGFR and the bioactive components (binding energy< -4.25 kcal/mol). Real-time quantitative polymerase chain reaction and western blot showed that CPD suppressed the activation of the EGFR/extracellular signal-regulated kinase (ERK) signalling pathway (p < 0.05), which could be associated with the inhibition of complement system activation. This study provides a new perspective for understanding the pathogenesis and treatment of HSP.

[Exploring the mechanism of IgA vasculitis pathogenesis through the interaction of thrombin and inflammatory factors using urinary proteomics]

OBJECTIVES

To explore the evidence, urinary biomarkers, and partial mechanisms of hypercoagulability in the pathogenesis of IgA vasculitis (IgAV).

METHODS

Differential expression of proteins in the urine of 10 healthy children and 10 children with IgAV was screened using high-performance liquid chromatography-tandem mass spectrometry, followed by Reactome pathway analysis. Protein-protein interaction (PPI) network analysis was conducted using STRING and Cytoscape software. In the validation cohort, 15 healthy children and 25 children with IgAV were included, and the expression levels of differential urinary proteins were verified using enzyme-linked immunosorbent assay.

RESULTS

A total of 772 differential proteins were identified between the IgAV group and the control group, with 768 upregulated and 4 downregulated. Reactome pathway enrichment results showed that neutrophil degranulation, platelet activation, and hemostasis pathways were involved in the pathogenesis of IgAV. Among the differential proteins, macrophage migration inhibitory factor (MIF) played a significant role in neutrophil degranulation and hemostasis, while thrombin was a key protein in platelet activation and hemostasis pathways. PPI analysis indicated that thrombin directly interacted with several proteins involved in inflammatory responses, and these interactions involved MIF. Validation results showed that compared to healthy children, children with IgAV had significantly higher urine thrombin/creatinine and urine MIF/creatinine levels (P<0.05).

CONCLUSIONS

Thrombin contributes to the pathogenesis of IgAV through interactions with inflammatory factors. Urinary thrombin and MIF can serve as biomarkers reflecting the hypercoagulable and inflammatory states in children with IgAV.

IL-17 promotes IL-18 production via the MEK/ERK/miR-4492 axis in osteoarthritis synovial fibroblasts

The concept of osteoarthritis (OA) as a low-grade inflammatory joint disorder has been widely accepted. Many inflammatory mediators are implicated in the pathogenesis of OA. Interleukin (IL)-18 is a pleiotropic cytokine with versatile cellular functions that are pathogenetically important in immune responses, as well as autoimmune, inflammatory, and infectious diseases. IL-17, a proinflammatory cytokine mainly secreted by Th17 cells, is upregulated in OA patients. However, the role of IL-17 in OA progression is unclear. The synovial tissues collected from healthy donors and OA patients were used to detect the expression level of IL-18 by IHC stain. The OA synovial fibroblasts (OASFs) were incubated with recombinant IL-17 and subjected to Western blot, qPCR, and ELISA to examine IL-18 expression level. The chemical inhibitors and siRNAs which targeted signal pathways were used to investigate signal pathways involved in IL-17-induced IL-18 expression. The microRNAs which participated IL-18 expression were surveyed with online databases miRWalk and miRDB, followed by validation with qPCR. This study revealed significantly higher levels of IL-18 expression in synovial tissue from OA patients compared with healthy controls, as well as increased IL-18 expression in OASFs from rats with severe OA. In vitro findings indicated that IL-17 dose-dependently promoted IL-18 production in OASFs. Molecular investigations revealed that the MEK/ERK/miR-4492 axis stimulated IL-18 production when OASFs were treated with IL-17. This study provides novel insights into the role of IL-17 in the pathogenesis of OA, which may help to inform OA treatment in the future.

IL-4-secreting CD40L+ MAIT cells support antibody production in the peripheral blood of Heonch-Schönlein purpura patients

OBJECTIVE

Here, we explored the phenotype and function of MAIT cells in the peripheral blood of patients with HSP.

METHODS

Blood samples from HSP patients and HDs were assessed by flow cytometry and single-cell RNA sequencing to analyze the proportion, phenotype, and function of MAIT cells. Th-cytokines in the serum of HSP patients were analyzed by CBA. IgA in cocultured supernatant was detected by CBA to analyze antibody production by B cells.

RESULTS

The percentage of MAIT cells in HSP patients was significantly reduced compared with that in HDs. Genes related to T cell activation and effector were up-regulated in HSP MAIT cells, indicating a more activated phenotype. In addition, HSP MAIT cells displayed a Th2-like profile with the capacity to produce more IL-4 and IL-5, and IL-4 was correlated with IgA levels in the serum of HSP patients. Furthermore, CD40L was up-regulated in HSP MAIT cells, and CD40L+ MAIT cells showed an increased ability to produce IL-4 and to enhance IgA production by B cells.

CONCLUSION

Our data demonstrate that MAIT cells in HSP patients exhibit an activated phenotype. The enhanced IL-4 production and CD40L expression of MAIT cells in HSP patients could take part in the pathogenesis of HSP.

Causal relationships between circulating inflammatory factors and IgA vasculitis: a bidirectional Mendelian randomization study

Background

IgA vasculitis (IgAV) is an immune-associated vasculitis, yet its exact etiology remains unclear. Here, we explore the interaction between IgAV and inflammatory factors using bidirectional Mendelian randomization (MR).

Methods

We conducted a bidirectional summary-level MR analysis to delineate the causality of C-reactive protein (CRP), procalcitonin (PCT), and 41 circulating inflammatory regulators with IgAV. Data on genetic variants related to inflammation were obtained from three genome-wide association studies (GWASs) on CRP, PCT, and human cytokines, whereas data on IgAV was from large meta-analyses of GWAS among 216 569 FinnGen Biobank participants. The primary MR analysis was performed using the inverse-variance weighted (IVW) approach, and the sensitivity analyses were carried out using MR-Egger, weighted median, weighted mode, and MR-pleiotropy residual sum and outlier.

Results

This study revealed the association of CRP higher levels with increased risk of IgAV through IVW method (Estimate odds ratio [OR] = 1.41, 95% confidence interval [CI]: 1.01-1.98, P = 0.04), MR-Egger (OR = 1.87, CI: 1.15-3.02, P = 0.01), weighted median (OR = 2.00, CI: 1.21-3.30, P = 0.01) and weighted mode (OR = 1.74, CI: 1.13-2.68, P = 0.02). Furthermore, elevated IL-8 was strongly implicated with a higher risk of IgAV (IVW OR = 1.42, CI: 1.05-1.92; P = 0.02). Conversely, genetically predicted IgAV was associated with decreased levels of TNF-β (IVW estimate β = -0.093, CI: -0.178 - -0.007; P = 0.033). Additionally, no such significant statistical differences for other inflammatory factors were found.

Conclusion

Our current study using bidirectional MR analysis provides compelling evidence for a causal effect of CRP, PCT, and circulating inflammatory regulators on IgAV. These findings contribute to a better understanding of the pathogenesis of IgAV and emphasize the potential of targeting inflammatory factors for therapeutic interventions.

IgA vasculitis update: Epidemiology, pathogenesis, and biomarkers

Immunoglobulin A vasculitis (IgAV), formerly known as Henoch-Schönlein purpura, is the most common systemic vasculitis in children, characterized by diverse clinical manifestations with a wide spectrum ranging from isolated cutaneous vasculitis to systemic involvement. The incidence of IgAV is geographically and ethnically variable, with a prevalence in autumn and winter, suggesting a driving role that genetic and environmental factors play in the disease. Although IgAV has a certain degree of natural remission, it varies widely among individuals. Some patients can suffer from severe renal involvement and even progress to end-stage renal disease. Its pathogenesis is complex and has not been fully elucidated. The formation of galactose-deficient IgA1 (Gd-IgA1) and related immune complexes plays a vital role in promoting the occurrence and development of IgAV nephritis. In addition, neutrophil activation is stimulated through the binding of IgA to the Fc alpha receptor I expressed on its surface, resulting in systemic vascular inflammation and tissue damage. Starting from the epidemiological characteristics, this article will review the role of immunological factors such as Gd-IgA1, autoantibodies, circulating immune complexes, complement system, cellular immunization, and the contributions of environmental and genetic factors in the pathogenesis of IgAV, and conclude with the major biomarkers for IgAV.

Biologics for immunoglobulin A vasculitis: targeting vasculitis or comorbid disease?

In this study, we aimed to evaluate the clinical features and treatments, including the use of biological disease-modifying anti-rheumatic drugs (bDMARDs) in a large cohort of pediatric and adult immunoglobulin A vasculitis (IgAV). Since data on the use of bDMARDs in IgAV are very limited, we collated the reasons for use of bDMARDs during the disease course. Patients who were enrolled in the Hacettepe University Vasculitis Research Centre (HUVAC) registry were included. In this prospective database dating from 2014, there were 436 IgAV patients classified as IgAV according to Ankara 2008 and/or American College of Rheumatology 1990 criteria. 88 adults and 330 pediatric IgAV patients were included as the main study group. Concomitant spondyloarthritis (SpA) was observed only in adult patients (10% vs 0% in children, p < 0.001). IgAV relapse was more common in adults than in children (p: 0.017). Adult patients were mostly treated with corticosteroid (p < 0.001) and conventional synthetic disease-modifying anti-rheumatic drug treatment (< 0.001), while more than half of the pediatric patients were followed up without immunosuppressive treatment. Ten (11%) adult patients used biologics. Among them, two patients used rituximab due to IgAV disease activity, three used infliximab due to SpA, three used etanercept due to SpA (one patient had a pediatric onset enthesitis-related arthritis), and two used anakinra due to recurrent familial Mediterranean fever attacks. This is the first study evaluating the use of all bDMARDs for any reason in the IgAV cohorts in the literature. None of the pediatric patients used biologics. Our data suggest biologics are mainly used for comorbid inflammatory diseases over refractory vasculitis in adult IgAV.

IgA vasculitis with nephritis: update of pathogenesis with clinical implications

IgA vasculitis with nephritis (IgAVN) shares many pathogenetic features with IgA nephropathy (IgAN). The purpose of this review is to describe our current understanding of the pathogenesis of pediatric IgAVN, particularly as it relates to the four-hit hypothesis for IgAN. These individual steps, i.e., hits, in the pathogenesis of IgAN are (1) elevated production of IgA1 glycoforms with some O-glycans deficient in galactose (galactose-deficient IgA1; Gd-IgA1), (2) generation of circulating IgG autoantibodies specific for Gd-IgA1, (3) formation of pathogenic circulating Gd-IgA1-containing immune complexes, and (4) kidney deposition of the Gd-IgA1-IgG immune complexes from the circulation and induction of glomerular injury. Evidence supporting the four-hit hypothesis in the pathogenesis of pediatric IgAVN is detailed. The genetics, pediatric outcomes, and kidney histopathologic features and the impact of these findings on future treatment and potential biomarkers are discussed. In summary, the evidence points to the critical roles of Gd-IgA1-IgG immune complexes and complement activation in the pathogenesis of IgAVN. Future studies are needed to characterize the features of the immune and autoimmune responses that enable progression of IgA vasculitis to IgAVN.

Pathogenesis of IgA Vasculitis: An Up-To-Date Review

Immunoglobin A (IgA) vasculitis (IgAV), formerly called the Henoch-Schönlein purpura (HSP), is a small vessel vasculitis, characterized by IgA1-dominant immune deposition at diseased vessel walls. IgAV is the most common form of vasculitis in children; typical symptoms include palpable purpura, arthritis or arthralgia, abdominal pain, and hematuria or proteinuria. Galactose-deficient IgA1 is detected in the tissues of the kidney and skin in patients with IgAV; it forms immune complexes leading to subsequent immune reactions and injuries. This report provides the recent advances in the understanding of environmental factors, genetics, abnormal innate and acquired immunity, and the role of galactose-deficient IgA1 immunocomplexes in the pathogenesis of IgAV.

Interleukin -17 and oxidative stress in children with immunoglobulin A vasculitis

Objective: We aimed to investigate levels of interleukin-17 (IL-17) and oxidative stress in the active phase of immunoglobulin A vasculitis (IgAV) and determine whether a relationship exists among IL-17, oxidative stress, and system involvement.Method: Patients diagnosed with IgAV, who were not given non-steroidal anti-inflammatory or steroidal drugs within a month, were enrolled. Blood samples were taken in the active and remission phases of the disease. Malondialdehyde (lipid peroxidation marker), 8-hydroxydeoxyguanosine (DNA oxidation marker), total oxidant status (TOS) and total antioxidant status (TAS) levels for oxidative stress, and IL-17 levels were measured.Results: Forty-four patients aged 1.91-15.41 years were enrolled. IL-17 and TAS levels were significantly higher in the active phase of the disease than in the remission phase. 8-Hydroxydeoxyguanosine levels were higher in patients with gastrointestinal involvement than in patients without involvement in the active phase of the disease. A moderate positive correlation was observed between IL-17 and TAS in both active and remission phases.Conclusion: Our results showed increased DNA oxidation in patients with gastrointestinal involvement in the active phase of IgAV, for the first time. Higher IL-17 and TAS levels in the active phase of the disease and positive correlations of TAS and IL-17 in both active and remission phases suggest that IL-17 and oxidative stress may be related.