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

LncRNAs in Kawasaki disease and Henoch-Schönlein purpura: mechanisms and clinical applications

Kawasaki disease (KD) and Henoch-Schönlein purpura (HSP) are the two most predominant types of childhood vasculitis. In childhood vasculitis, factors such as lack of sensitive diagnostic indicators and adverse effects of drug therapy may cause multiorgan system involvement and complications and even death. Many studies suggest that long noncoding RNAs (lncRNAs) are involved in the mechanism of vasculitis development in children and can be used to diagnose or predict prognosis by lncRNAs. In existing drug therapies, lncRNAs are also involved in drug-mediated treatment mechanisms and are expected to improve drug toxicity. The aim of this review is to summarize the link between lncRNAs and the pathogenesis of KD and HSP. In addition, we review the potential applications of lncRNAs in multiple dimensions, such as diagnosis, treatment, and prognosis prediction. This review highlights that targeting lncRNAs may be a novel therapeutic strategy to improve and treat KD and HSP.

The role of antibody glycosylation in autoimmune and alloimmune kidney diseases

Immunoglobulin glycosylation is a pivotal mechanism that drives the diversification of antibody functions. The composition of the IgG glycome is influenced by environmental factors, genetic traits and inflammatory contexts. Differential IgG glycosylation has been shown to intricately modulate IgG effector functions and has a role in the initiation and progression of various diseases. Analysis of IgG glycosylation is therefore a promising tool for predicting disease severity. Several autoimmune and alloimmune disorders, including critical and potentially life-threatening conditions such as systemic lupus erythematosus, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis and antibody-mediated kidney graft rejection, are driven by immunoglobulin. In certain IgG-driven kidney diseases, including primary membranous nephropathy, IgA nephropathy and lupus nephritis, particular glycome characteristics can enhance in situ complement activation and the recruitment of innate immune cells, resulting in more severe kidney damage. Hypofucosylation, hypogalactosylation and hyposialylation are the most common IgG glycosylation traits identified in these diseases. Modulating IgG glycosylation could therefore be a promising therapeutic strategy for regulating the immune mechanisms that underlie IgG-driven kidney diseases and potentially reduce the burden of immunosuppressive drugs in affected patients.

The Diagnostic Role of Skin Manifestations in Rheumatic Diseases in Children: A Critical Review of Paediatric Vasculitis

Skin lesions are frequently observed in children with rheumatic diseases, particularly in conditions such as IgA vasculitis (IgAV) and Kawasaki disease (KD). In paediatric vasculitis, the presence of skin lesions serves as an early indicator, emphasising the importance of timely diagnosis to prevent complications, such as cardiac or renal involvement. Conversely, autoinflammatory disorders like juvenile systemic lupus erythematosus (SLE) and juvenile dermatomyositis (DM) may manifest with cutaneous manifestations either at the onset of disease or during its progression. Identifying these skin lesions prior to the appearance of systemic symptoms offers an opportunity for early diagnosis and treatment, which has a positive influence on the outcomes. Additionally, it is noteworthy that specific rheumatological conditions, such as acute rheumatic fever (ARF) or oligoarticular or polyarticular forms of juvenile idiopathic arthritis (JIA), may exhibit occasional, but significant skin involvement, which is strongly correlated with an unfavourable prognosis. The assessment of skin is important in the holist approach to assessing patients for potentially systemic/multisystem disorder and helps distinguish discrete conditions.

Exploring potential predictors of Henoch-Schönlein purpura nephritis: a pilot investigation on urinary metabolites

Henoch-Schönlein purpura nephritis (HSPN) is the most severe manifestation of Henoch-Schönlein purpura (HSP). This study aimed to determine the role of urine metabolomics in predicting HSPN and explore the potential mechanisms of HSP. A liquid chromatography-tandem mass spectrometry-based untargeted metabolomics analysis was performed to investigate the urinary metabolic profiles of 90 participants, comprising 30 healthy children (group CON) and 60 patients with HSP, including 30 HSP patients without renal involvement (group H) and 30 HSPN patients (group HSPN). The differentially expressed metabolites (DEMs) were identified using orthogonal partial least squares discriminant analysis (OPLS-DA), and subsequent bioinformatics analysis was conducted to elucidate the perturbed metabolic pathways. A total of 43 DEMs between H and HSPN groups were analyzed by the Kyoto Encyclopedia of Gene and Genome (KEGG) database, and the result indicates that glycine, serine and threonine metabolism, and cysteine and methionine metabolism were significantly disturbed. A composite model incorporating propionylcarnitine and indophenol sulfate was developed to assess the risk of renal involvement in pediatric patients with HSP.   Conclusion: This study reveals the metabolic alterations in healthy children, HSPN patients, and HSP patients without renal involvement. Furthermore, propionylcarnitine and indophenol sulfate may be potential predictive biomarkers of the occurrence of HSPN. What is Known: • HSP is the predominant type of vasculitis observed in children. The long-term prognosis of HSP is contingent upon the extent of renal impairment. In severe nephritis, a delay in appropriate treatment may lead to fibrosis progression and subsequent development of chronic kidney disease (CKD), even leading to renal failure. • The application of metabolomics in investigating diverse renal disorders has been documented. Urine is a robust and sensitive medium for metabolomics detection. What is New: • The metabolic profiles were identified in urine samples of healthy children and those with HSP at the early stage of the disease. Different metabolites were identified between HSP patients without nephritis and those who developed HSPN. • These different metabolites may affect oxidative stress in the progression of HSPN.

Enterohemorrhagic Escherichia coli: trigger for small vessel vasculitis

We describe the case of a 19-year-old woman who presented with abdominal pain, vomiting, and a palpable purpuric rash. The patient subsequently developed dysentery and was found to have an infection from Shiga toxin-producing Escherichia coli. The patient also met diagnostic criteria for IgA vasculitis (also known as Henoch Schönlein purpura) but had negative immunofluorescence biopsies of the rash. The patient was treated with steroids and achieved recovery. To our knowledge, this is the first documented case of IgA vasculitis in the setting of an enterohemorrhagic E. coli infection. This case highlights an atypical presentation of IgA vasculitis and the need to include small vessel vasculitis as a differential diagnosis when treating patients of all ages.

Unravelling the Link between the Gut Microbiome and Autoimmune Kidney Diseases: A Potential New Therapeutic Approach

The gut microbiota and short chain fatty acids (SCFA) have been associated with immune regulation and autoimmune diseases. Autoimmune kidney diseases arise from a loss of tolerance to antigens, often with unclear triggers. In this review, we explore the role of the gut microbiome and how disease, diet, and therapy can alter the gut microbiota consortium. Perturbations in the gut microbiota may systemically induce the translocation of microbiota-derived inflammatory molecules such as liposaccharide (LPS) and other toxins by penetrating the gut epithelial barrier. Once in the blood stream, these pro-inflammatory mediators activate immune cells, which release pro-inflammatory molecules, many of which are antigens in autoimmune diseases. The ratio of gut bacteria Bacteroidetes/Firmicutes is associated with worse outcomes in multiple autoimmune kidney diseases including lupus nephritis, MPO-ANCA vasculitis, and Goodpasture's syndrome. Therapies that enhance SCFA-producing bacteria in the gut have powerful therapeutic potential. Dietary fiber is fermented by gut bacteria which in turn release SCFAs that protect the gut barrier, as well as modulating immune responses towards a tolerogenic anti-inflammatory state. Herein, we describe where the current field of research is and the strategies to harness the gut microbiome as potential therapy.

Insight into the Interplay of Gd-IgA1, HMGB1, RAGE and PCDH1 in IgA Vasculitis (IgAV)

The pathogenesis of IgAV, the most common systemic vasculitis in childhood, appears to be complex and requires further elucidation. We aimed to investigate the potential role of galactose-deficient immunoglobulin A1 (Gd-IgA1), high-mobility group box 1 (HMGB1), receptor for advanced glycation end products (RAGE) and protocadherin 1 (PCDH1) in the pathogenesis of IgAV. Our prospective study enrolled 86 patients with IgAV and 70 controls. HMGB1, RAGE, Gd-IgA1 and PCDH1 in serum and urine were determined by the enzyme-linked immunosorbent assay (ELISA) method at the onset of the disease and after a six-month interval in patients and once in the control group. Serum concentrations of HMGB1, RAGE and PCDH1 and urinary concentrations of HMGB1, RAGE, Gd-IgA1 and PCDH1 were significantly higher in patients with IgAV than in the control group (p < 0.001). Concentrations of HMGB1 (5573 pg/mL vs. 3477 pg/mL vs. 1088 pg/mL, p < 0.001) and RAGE (309 pg/mL vs. 302.4 pg/mL vs. 201.3 pg/mL, p = 0.012) in the serum of patients remained significantly elevated when the disease onset was compared with the six-month follow-up interval, and thus could be a potential marker of disease activity. Urinary concentration of HMGB1 measured in the follow-up period was higher in patients with nephritis compared to IgAV without nephritis (270.9 (146.7-542.7) ng/mmol vs. 133.2 (85.9-318.6) ng/mmol, p = 0.049) and significantly positively correlated with the urine albumine to creatinine ratio (τ = 0.184, p < 0.05), the number of erythrocytes in urine samples (τ = 0.193, p < 0.05) and with the outcome of nephritis (τ = 0.287, p < 0.05); therefore, HMGB1 could be a potential tool for monitoring patients with IgAV who develop nephritis. Taken together, our results imply a possible interplay of Gd-IgA1, HMGB1, RAGE and PCDH1 in the development of IgAV. The identification of sensitive biomarkers in IgAV may provide disease prevention and future therapeutics.

Involvement of M1-Activated Macrophages and Perforin/Granulysin Expressing Lymphocytes in IgA Vasculitis Nephritis

We investigated the polarisation of CD68+ macrophages and perforin and granulysin distributions in kidney lymphocyte subsets of children with IgA vasculitis nephritis (IgAVN). Pro-inflammatory macrophage (M)1 (CD68/iNOS) or regulatory M2 (CD68/arginase-1) polarisation; spatial arrangement of macrophages and lymphocytes; and perforin and granulysin distribution in CD3+ and CD56+ cells were visulaised using double-labelled immunofluorescence. In contrast to the tubules, iNOS+ cells were more abundant than the arginase-1+ cells in the glomeruli. CD68+ macrophage numbers fluctuated in the glomeruli and were mostly labelled with iNOS. CD68+/arginase-1+ cells are abundant in the tubules. CD56+ cells, enclosed by CD68+ cells, were more abundant in the glomeruli than in the tubuli, and co-expressed NKp44. The glomerular and interstitial/intratubular CD56+ cells express perforin and granulysin, respectively. The CD3+ cells did not express perforin, while a minority expressed granulysin. Innate immunity, represented by M1 macrophages and CD56+ cells rich in perforin and granulysin, plays a pivotal role in the acute phase of IgAVN.

Taxonomic and functional shifts of gut microbiome in immunoglobulin A vasculitis children and their mothers

Objectives

To examine the gut microbiota characteristics in children with immunoglobulin A vasculitis and their interrelationships with the host, while evaluate the vertical inheritance of microbiota in the development and progression of IgA vasculitis.

Methods

This study investigated the gut microbiome of 127 IgA vasculitis mother-child pairs and 62 matched healthy mother-child pairs, and compared the gut microbial composition of different groups. The pathway enrichment analysis evaluated potential gut microbiome-mediated pathways involved in the pathophysiology of IgA vasculitis. The Spearman correlation analysis illustrated the relationships between clinical variables and bacterial biomarkers.

Results

This study identified distinct intestinal microbiome in IgA vasculitis children compared to healthy children, and further pointed out the association in gut microbiota between IgA vasculitis children's and their mother's. The relative abundance of Megamonas and Lactobacillus in IgAV children was positively correlated with that in their mothers. The pathway enrichment analysis found microbial biosynthesis of vitamins and essential amino acids was upregulated in children with IgA vasculitis. Correlation analysis showed bacterial biomarkers were correlated with indicators of blood coagulation.

Conclusion

Children with IgA vasculitis have unique bacterial biomarkers and may affect coagulation function, and their gut microbiome was closely associated with that of their mothers. The observed association in gut microbiota between IgA vasculitis children and their mothers suggested a potential intergenerational influence of the maternal microbiota on the development or progression of IgA vasculitis in children.

Ang-1, Ang-2, and Tie2 are diagnostic biomarkers for Henoch-Schönlein purpura and pediatric-onset systemic lupus erythematous

Henoch-Schönlein purpura (HSP) and pediatric-onset systemic lupus erythematosus (pSLE) are closely associated with vasculitis and vascular diseases. This study aimed to investigate the clinical diagnostic values of Ang-1, Ang-2, and Tie2 for HSP and pSLE. We surveyed 82 HSP patients, 34 pSLE patients, and 10 healthy children. The expression levels of Ang-1, Ang-2, and Tie2 in the serum and urine were assessed using enzyme-linked immunosorbent assay. The diagnostic values of Ang-1, Ang-2, and Tie2 for HSP and pSLE were evaluated using receiver operating characteristic curve analysis. The results revealed that the serum and urine expression levels of Ang-2 and Tie2 were significantly elevated in HSP and pSLE patients, whereas the Ang-1/Ang-2 values were reduced. Additionally, Ang-1 was highly expressed in the serum and urine of HSP patients and in the serum of pSLE patients. Ang-1, Ang-2, and Tie2 showed differential expression in various types of HSP and pSLE compared with their expression in healthy controls. In summary, Ang-1, Ang-2, and Tie2 can serve as biomarkers for HSP and pSLE. Moreover, Ang-1/Ang-2 values are reduced in HSP and pSLE patients. Ang-1, Ang-2, and Tie2 can be used as biomarkers for HSP and pSLE.

Epidemiology and clinical characteristics of biopsy-confirmed adult-onset IgA vasculitis in southern Sweden

OBJECTIVE

Immunoglobulin A vasculitis (IgAV) is the most prevalent primary childhood vasculitis in Sweden, but is considerably rarer in adults. This study aims to describe the epidemiology, clinical characteristics and renal outcome of adult-onset IgAV in Skåne, Sweden.

METHODS

The study area consisted of Skåne, the southernmost region of Sweden, with a population ≥18 years of 990 464 on 31 December 2010. Adult patients assigned the International Classification of Diseases-10 code for IgAV (D69.0) from 2000 through 2019 were retrospectively identified in a population-based database. Medical records were reviewed to validate the diagnosis of IgAV and extract data. Only patients with clinical manifestations of IgAV and biopsy-confirmed disease were included. The annual incidence and point prevalence of biopsy-confirmed IgAV were estimated.

RESULTS

Fifty-nine patients (19 women) were classified as having adult-onset IgAV. The incidence was 3 per 1 000 000 and was higher among men than women (4 vs 2/1 000 000, p=0.004). Ninety-seven per cent of patients presented with non-thrombocytopenic purpura, 78% with renal involvement, 59% with arthritis/arthralgia and 39% with gastrointestinal symptoms. Fifteen per cent developed chronic kidney disease stage ≥G3 a and one patient progressed to end-stage kidney disease during follow-up.

CONCLUSION

Adult-onset IgAV is rare in southern Sweden with the incidence higher in men than in women. IgAV frequently affects the kidneys and leads to chronic kidney disease in adults, although the long-term renal outcome appears favourable compared with other small-vessel vasculitides affecting the kidneys.

[Immunoglobulin A vasculitis]

The immune-mediated small vessel vasculitis is known as Schoenlein-Henoch purpura predominantly from pediatrics and in these cases occurs more frequently after infections of the upper airways. In adults, immunoglobulin A (IgA) vasculitis often proceeds more severely und recurrently with the classical tetrad of skin manifestations in the sense of leukocytoclastic vasculitis, joint affection, gastrointestinal involvement and IgA nephritis, in contrast to the mostly mild and self-limiting course in children. The background of this systemic vasculitis with formation of IgA immune complexes is considered to be an altered glycosylation of IgA, as this causes the exposure of binding sites for autoantibodies so that an immune complex reaction can be elicited. This ultimately leads to perivascular deposition of IgA and a further activation of neutrophils. Groundbreaking in the diagnostics is the histological detection of leukocytoclastic vasculitis and in cases of renal manifestations a kidney biopsy with characteristic deposits of immune complexes, which cannot be clearly differentiated from IgA nephropathy. The treatment is aimed at the respective manifestation and is mostly based on consensus recommendations due to the lack of randomized studies. In addition to immunosuppressive medication, in the presence of a chronic kidney disease general nephroprotection is becoming increasingly more important also by inhibition of sodium-glucose transporter 2 (SGLT2). The type and extent of kidney involvement and also rare cardiac manifestations are the main determinants of the prognosis. Continuous medical accompaniment of those affected is necessary due to the possible progression of the disease and the risk of recurrence.

Association between TRAF1/C5 Gene Polymorphisms and IgA Vasculitis in Chinese Children

OBJECTIVE

To investigate the association between loci rs3761847 and rs10818488 of tumor necrosis factor receptor-associated factor 1/complement C5 (TRAF1/C5) gene and the susceptibility to IgAV.

METHODS

100 blood samples of children with IgAV and 100 blood samples of healthy children were collected from the Third Xiangya Hospital of Central South University from June 2017 to June 2019. The target gene fragment was amplified by polymerase chain reaction (PCR), and the single nucleic acid gene polymorphism of the gene loci was detected by PCR sequencing based typing technique. The association between gene polymorphism of each locus and susceptibility to IgAV was analyzed.

RESULTS

There were significant differences in both genotype (P < .05) and allele frequencies （P < .05) of rs3761847 of TRAF1/C5 gene between the IgAV group and the control group.Besides, the risks of developing IgAV in children with the TT genotype was 0.495 times and in children with the C allele was 1.627 times of that in children with other genotypes and alleles, respectively (P < .05). For IgAV patients, renal involvement risk in children with CC genotype was 5.859 times of that in children with other genotypes (P < .05). There were no significant differences in genotype (P > .05) and allele frequencies (P > .05) of rs10818488 of TRAF1/C5 gene between the IgAV group and the control group. IgAV patients with TT genotype had a 3.2 times higher risk of renal involvement than those with other genotypes (P < .05).

CONCLUSIONS

There is an association between locus rs3761847 of TRAF1/C5 gene single nucleotide polymorphisms and susceptibility to IgAV. The T allele at locus rs3761847 of TRAF1/C5 gene may be a protective factor for IgAV. The C allele at locus rs3761847 and the T allele at locus rs10818488 of TRAF1/C5 gene may be associated with kidney injury in IgAV.

Drusen and Other Retinal Findings in People With IgA Glomerulonephritis

PURPOSE

Retinal drusen have been described in people with IgA nephropathy. We examined the frequency of drusen in IgA nephropathy and compared their location and composition with those for drusen in age-related macular degeneration.

DESIGN

Immunohistological case series of eyes of patients with IgA nephropathy, and a comparison eye with age-related macular degeneration.

METHODS

Donor eyes from 4 individuals (3 male, 1 female, aged 40-80 years) with biopsy-proven IgA nephropathy and kidney failure were examined for the presence of drusen, and location and composition using antibodies for vitronectin, IgA, IgM, IgG, C3, and C1q. Results were compared with those for drusen in macular degeneration without IgA nephropathy.

RESULTS

All 4 donors had sparse, subretinal pigment epithelium drusen of 55-65 mm diameter that stained for vitronectin but not for IgA or complement. All donors had retinal capillaries and choriocapillaris staining for IgA. The youngest donor (female, 40) had rare deposits in the outer nuclear layer that stained for IgA, but not for vitronectin. The oldest donor (male, 82) had large cystlike spaces in the inner nuclear and plexiform layers, and smaller cysts in the outer nuclear layer, with no staining for IgA or complement.

CONCLUSIONS

Retinal drusen are uncommon in IgA nephropathy, even with kidney failure. Drusen in IgA nephropathy resemble drusen found in age-related macular degeneration. IgA-staining deposits in the outer nuclear layer were likely due to systemic deposition of IgA and complement activation. The nature of cystic spaces is unknown. Further analysis of the retinas of people with glomerulonephritis is recommended.

IgA vasculitis in adults, pediatrics and non-vasculitic IgA nephropathy, retrospective analysis from 2 centers

Renal involvement represents the major long-term morbidity associated with IgA vasculitis (IgAV). Our aim was to evaluate clinical characteristics and long-term renal outcomes of IgAV in pediatrics and adults comparing to IgA nephropathy (IgAN). Our retrospective study included children and adults with IgAV and IgAN patients, admitted in a 13-year period (2007-2019) to rheumatology clinics and in hospital pediatric and internal medicine departments. We compared frequencies of clinical manifestations, laboratory findings, treatments, long-term outcomes at 1 year follow-up, including all-cause mortality and dialysis until the end of follow-up time. A total of 60 adult IgAV, 60 pediatric IgAV and 45 IgAN patients were evaluated. Adult IgAV patients were significantly older than IgAN patients (53.1 ± 17.4 years vs 45.1 ± 15.7 years respectively, P = .02) and had significantly higher rates of cardiovascular comorbidities. The risk and time to dialysis were similar among IgAN and adult IgAV groups. Yet, overall mortality at long term follow up was higher in IgAV adult group compared to IgAN. No dialysis or renal transplantation were reported in pediatric IgAV patients. IgAV and IgAN adult patients were comparable regarding risk of end stage renal disease. Of note, high mortality rates were observed among adult IgAV group.

Urinary markers of the alternative and lectin complement pathway are increased in IgA vasculitis nephritis

Background

IgA vasculitis (IgAV) is the most common form of childhood vasculitis. Nephritis (IgAVN) occurs in 50% of patients and 1-2% progress to chronic kidney disease stage 5. The pathophysiology of nephritis remains largely unknown, but recent evidence suggests that the complement system may be involved. The aim of this cross-sectional study was to explore whether there is evidence of alternative and/or lectin complement pathway activation in children with IgAVN.

Methods

Children with IgAV were recruited and grouped according to proteinuria: IgAVN or IgAV without nephritis (IgAVwoN). Age and sex-matched healthy controls (HCs) were also recruited. Cross-sectional urine and plasma concentrations of complement factor D (CFD), factor B (CFB), and MBL-associated protease 1 (MASP-1) were performed using commercially available enzyme-linked immunoassays.

Results

A total of 50 children were included (IgAVN, n = 15; IgAVwoN, n = 20, HCs, n = 15). The mean age was 8.5 ± 3.7 years old, male:female ratio was 1:1. Urinary CFD and CFB concentrations were statistically significantly increased in children with IgAVN (3.5 ± 5.4 μg/mmol; 25.9 ± 26.5 μg/mmol, respectively) compared to both IgAVwoN (0.4 ± 0.4 μg/mmol, P = 0.002; 9.2 ± 11.5 μg/mmol, P = 0.004) and HCs (0.3 ± 0.2 μg/mmol, P < 0.001; 5.1 ± 6.0 μg/mmol, P < 0.001). No statistically significant difference was reported for the plasma concentrations of CFD and CFB. Urinary MASP-1 concentrations were statistically significantly increased in IgAVN (116.9 ± 116.7 ng/mmol) compared to HCs (41.4 ± 56.1 ng/mmol, P = 0.006) and plasma MASP-1 concentrations were increased in IgAVwoN (254.2 ± 23.3 ng/mL) compared to HCs (233.4 ± 6.6 ng/mL, P = 0.046).

Conclusion

There is evidence of complement pathway products in the urine of children with IgAVN that warrants further investigation.

A narrative review of potential drug treatments for nephritis in children with IgA vasculitis (HSP)

Immunoglobulin A (IgA) vasculitis (IgAV, also known as Henoch-Schoenlein purpura, HSP) is the most common vasculitis of childhood. It usually presents with a simple, self-limiting disease course; however, a small subset of patients may develop kidney involvement (IgAV-N) which occurs 4-12 weeks after disease onset and is the biggest contributor to long-term morbidity. Treatment currently targets patients with established kidney involvement; however; there is a desire to work towards early prevention of inflammation during the window of opportunity between disease presentation and onset of significant nephritis. There are no clinical trials evaluating drugs which may prevent or halt the progression of nephritis in children with IgAV apart from the early use of corticosteroids which have no benefit. This article summarises the latest scientific evidence and clinical trials that support potential therapeutic targets for IgAV-N that are currently being developed based on the evolving understanding of the pathophysiology of IgAV-N. These span the mucosal immunity, B-cell and T-cell modulation, RAAS inhibition, and regulation of complement pathways, amongst others. Novel drugs that may be considered for use in early nephritis include TRF-budesonide; B-cell inhibiting agents including belimumab, telitacicept, blisibimod, VIS649, and BION-1301; B-cell depleting agents such as rituximab, ofatumumab, and bortezomib; sparsentan; angiotensin converting enzyme inhibitors (ACE-Is); and complement pathway inhibitors including avacopan, iptacopan, and narsoplimab. Further clinical trials, as well as pre-clinical scientific studies, are needed to identify mechanistic pathways as there may be an opportunity to prevent nephritis in this condition. Key Points • Kidney involvement is the main cause of long-term morbidity and mortality in IgA vasculitis despite the current treatment recommendations. • The evolving understanding of the pathophysiology of IgA vasculitis is allowing exploration of novel treatment options which target underlying immune pathways. • Novel treatments currently being trialled in IgA nephropathy may have benefit in IgA vasculitis due to the similarities in the underlying pathophysiology, such as TRF-budesonide, B-cell modulators, and complement inhibitors. • Further studies, including clinical trials of novel drugs, are urgently needed to improve the long-term outcomes for children with IgA vasculitis nephritis.

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.

Secukinumab-induced IgA vasculitis in a patient with psoriatic arthritis

OBJECTIVES

Secukinumab (SEC) is an effective and widely used drug in psoriatic disease and axial spondyloarthritis. However, SEC has been found to be associated with inflammatory conditions and vasculitis. These inflammatory adverse effects may complicate the treatment of underlying disease, and clinicians may experience difficulties in recognizing and managing this unusual condition.

CASE REPORT

A man aged 56 years with psoriatic disease refractory to conventional disease-modifying antirheumatic drugs was given adalimumab for 6 weeks, then switched to SEC when his psoriatic lesions were exacerbated. After 3 weeks of SEC treatment, he developed systemic features of IgA vasculitis while his skin lesions and arthritis persisted.

CONCLUSIONS

Although SEC-related inflammatory adverse events, including vasculitis, are rarely encountered in clinical practice, it is essential to recognize them because they can be mistaken as a component of the underlying inflammatory disease. In addition, the dramatic improvement in many cases after the cessation of SEC underlines the importance of making an accurate diagnosis. Pathogenetically, these adverse events are likely to be paradoxical reactions, except for SEC-induced inflammatory bowel diseases. However, in many aspects, their pathogenesis is controversial and needs clarification.

A case series on recurrent and persisting IgA vasculitis (Henoch Schonlein purpura) in children

BACKGROUND

IgA vasculitis (IgAV) is a small vessel vasculitis that is more common in childhood. Very limited evidence exists on patients who experience an atypical disease course. The aim of this study was to describe a cohort of children diagnosed with recurrent or persisting IgAV to identify any themes associated with their disease course and areas of unmet needs.

METHODS

A single centre retrospective study of children diagnosed with recurrent or persisting IgAV at Alder Hey Children's Hospital (Liverpool, UK). Clinical data, including features at presentation and during follow up, potential triggers, abnormal laboratory and histology results, treatment and outcome at last clinical review were retrospectively collected. Key themes were identified.

RESULTS

A total of 13 children met the inclusion criteria (recurrent disease, n = 4; persisting disease, n = 9). Median age at first presentation was 10.2 years [2.6-15.5], female:male ratio 1.2:1. Children in the atypical cohort were significantly older than a larger cohort of children who followed a non-complicated disease course (median age 5.5 years (range [0.6-16.7], p = 0.003)). All children re-presented with a purpuric rash (either recurring or persisting), accompanied by joint involvement in 92% of patients (12/13). Disease-modifying anti-rheumatic drugs (DMARDs) were used in 8/13 (62%) children. The median time from first presentation to diagnosis of atypical disease was 18.4 months [5.3-150.8] and the time from first presentation to treatment was 24.1 months [1.8-95.4]. Use of corticosteroids was significantly higher in children with renal involvement (p = 0.026). During follow up, 8/13 (62%) children were admitted at least once, whilst 10/13 (77%) had re-presented at least once to the emergency department. Five (38%) children were referred to psychology services and 7 (54%) children reported feelings of frustration.

CONCLUSIONS

This series describes some characteristics of a small cohort of children with atypical IgAV. It also identifies unmet needs in children with atypical IgAV, which includes delays in diagnosis and lengthy waits for treatment, lack of high-quality evidence regarding treatment choices and a high unrecognised disease burden. Further research is needed to study this subgroup of children as evidence is lacking.

Testicular ischemia associated with IgA vasculitis in a child: a case report and literature review

Testicular necrosis is a rare and severe complication of immunoglobulin A (IgA) vasculitis (IgAV). Herein, We report a case of a 10-year-old boy who was admitted to the hospital due to skin purpura and intermittent abdominal pain for 10 days and bilateral testicular pain for 2 days. Scrotal ultrasonography indicated right testicle ischemia, right epididymo-orchitis, and bilateral hydrocele of the testis. Scrotal surgical exploration revealed significant swelling and darkening of the right testicle. Conservative treatment led to improvement in his condition, and he was discharged. During 3 months of follow-up, there was no recurrence of skin purpura or pain, and the urine tests were normal. Color ultrasound indicated only partial blood flow signal to the right testicle tissue, which was slightly smaller than the left testicle. This case highlights the need for continuous attention from clinicians to the signs and symptoms of the reproductive system during the diagnosis and treatment of IgAV. Continuous monitoring with ultrasound can aid in early detection, diagnosis, and treatment of reproductive system lesions of IgA vasculitis.

Neutrophil extracellular traps involved in the pathogenesis of IgA vasculitis: Confirmed in two IgAV rat models

BACKGROUND

Neutrophil extracellular traps (NETs) have been found to play a role in the development of autoimmune diseases. In the past two years, studies have demonstrated a significantly increase of NETs in skin tissues during the early stages of IgAV, indicating their involvement in disease activity among children with IgAV. However, the presence of NETs in IgAV animal models has not yet been reported. The objective of this study is to investigate whether NETs are involved in the pathogenesis of IgA vasculitis (IgAV) rats.

METHODS

Twenty-four SD rats were randomly divided into three groups: the ovalbumin group, the gliadin group, and the control group. The IgAV rat models were established administering Indian ink with ovalbumin (ovalbumin group) or gliadin (gliadin group) with Freund's complete adjuvant. The cell-free DNA (cf-DNA) was quantified by using dsDNA quantification kit, while the levels of Immunoglobulins, complement C3 and myeloperoxidase-DNA (MPO-DNA) in serum were tested using enzyme linked immunosorbent assay (ELISA). The IgA, complement C3 and NETs in tissues were detected through multiple immunofluorescences.

RESULTS

Both the ovalbumin group and gliadin group showed IgA and C3 deposition in various tissues, including the glomerular mesangial region, skin, and digestive tract, while the control group showed no such deposition. The levels of circulatory cf-DNA and MPO-DNA, which are components of NETs, were significantly elevated in both ovalbumin and gliadin groups compared with the control group. Furthermore, the presence of NETs were found in gastrointestinal and renal tissues of the ovalbumin and gliadin groups, but not in the control group.

CONCLUSIONS

IgAV model rat can be established through the combination of ovalbumin and gliadin with Indian ink and Freund's complete adjuvant. This study provides the first confirmation that NETs are involved in the pathogenesis of IgAV rat.

An Unusual Case of Bilateral Lower Extremity Edema in the Elderly: Immunoglobulin A (IgA) Vasculitis

We report a case of a 74-year-old male who exhibited bilateral lower extremity edema over three days. Examination revealed no signs of heart, renal, or hepatic failure, and hypothyroidism was also ruled out. An outpatient regimen of 40 mg furosemide was initiated. At a 12-day follow-up, although the edema had improved, the patient had developed pain in both lower limbs, especially ankles, accompanied by numerous petechiae and erythemas, some of which had formed papules. Skin biopsy of the rash displayed leukocytoclastic vasculitis with immunoglobulin A (IgA) deposition within the vascular walls, leading to a diagnosis of IgA vasculitis. Given the rarity of IgA vasculitis in elderly patients and the broad spectrum of potential diagnoses related to bilateral lower extremity edema in this population, IgA vasculitis can be easily overlooked. While this case did not present with glomerulonephritis, regular renal function monitoring is recommended due to the prognostic implications of renal involvement in adult-onset IgA vasculitis.

Venous sinus thrombosis in a case of immunoglobulin A vasculitis and a systemic review of literature

OBJECTIVES

To describe venous sinus thrombosis involved in immunoglobulin A (IgA) vasculitis and identify the clinical features and imaging findings of this rare disease.

METHODS

We describe a case with venous sinus thrombosis related to IgA vasculitis, and a systematic review of previously reported cases in the literature.

RESULTS

A 10-year-old boy presented with recurrent petechiae of the lower extremities with abdominal pain, and was diagnosed as having IgA vasculitis. He had a sudden headache during the treatment of steroids, and venous sinus thrombosis was diagnosed according to magnetic resonance imaging. Venous sinus thrombosis is a rare complication of IgA vasculitis. Based on the systematic review, most of these reported cases who developed venous sinus thrombosis had multi-system involvement, which included skin, joints, gastrointestinal tract or kidneys. Sudden headache was the most common symptom of central venous sinus thrombosis. Some cases may also manifest as seizures and blindness. The sagittal sinus was the most common site of thrombosis. Magnetic resonance image, magnetic resonance venography, or computed tomography angiography were helpful for early diagnosis of this disease. Combination therapy of steroids and anticoagulation medication was effective in rapidly reliving clinical symptoms.

CONCLUSIONS

Sudden headache in patients with IgA vasculitis requires vigilance for the possibility of central venous sinus thrombosis. Anti-inflammatories combined with anticoagulant therapy were needed for these patients.

Association of the Monocyte-to-High-Density Lipoprotein Cholesterol Ratio with Gastrointestinal Involvement of Immunoglobulin a Vasculitis

Objective

To illustrate the association of monocyte to high-density lipoprotein cholesterol ratio (MHR) and other serum indicators with the pathogenesis and prognosis of immunoglobulin A vasculitis (IgAV) patients in different subgroups.

Methods

A total of 158 adult patients and 113 healthy controls were enrolled, and the clinical presentation and laboratory indexes were comprehensively assessed.

Results

IgAV patients show significantly elevated levels of inflammatory parameters and lipid profiles compared to healthy controls (P < 0.05). Higher levels of the MHR and other normal inflammatory indicators were found in patients with Gastrointestinal (GI) involvement compared to other subgroups. And in group with GI involvement, significantly higher white blood cell (WBC), neutrophil, complement 4 (C4), NLR (neutrophil-to-lymphocyte ratio) and PLR (platelet-to-lymphocyte ratio) levels and lower levels of apolipoprotein-a (Apo-a) were observed. Their correlation analysis demonstrated positive results between MHR level and white blood cell (WBC) count (r = 0.416, P = 0.034), D-Dimer (r = 0.464, P = 0.026) and monocyte (r = 0.947, P < 0.001). And the time until first remission of skin purpura was shown positively correlated with their age (r = 0.456, P = 0.043), C-reactive protein (CRP) level (r = 0.641, P = 0.018), D-Dimer level (r = 0.502, P = 0.040) while negatively correlated with albumin (Alb) level (r=-0.626, P = 0.003) and low-density lipoprotein (LDL) level (r=-0.478, P = 0.033).

Conclusion

Our study suggests that those biomarkers represented for inflammatory responses, lipid profile and immunological functions have significant differences in the subgroups of adult IgAV patients. In addition, we also found that MHR level may serve as a potential biomarker for the pathogenesis and prognosis of IgAV patients with GI involvement.

IgA Vasculitis Following COVID-19 Vaccination: A French Multicenter Case Series Including 12 Patients

OBJECTIVE

The worldwide coronavirus disease 2019 (COVID-19) vaccination campaign triggered several autoimmune diseases. We hereby aimed to describe IgA vasculitis (IgAV) following COVID-19 vaccination.

METHODS

We conducted a national, multicenter, retrospective study in France of new-onset adult IgAV diagnosis following COVID-19 vaccination.

RESULTS

In total, 12 patients with new-onset IgAV were included. Of these, 5 (41.7%) were women, and the median age was 52.5 (IQR 30.75-60.5) years. Of the 12 patients, 10 had received an mRNA vaccine and 2 had received a viral vector vaccine. The median time from vaccination to onset of symptoms was 11.5 (IQR 4.25-21.25) days. Vasculitis occurred after the first vaccine dose in most patients (n = 8). All patients had skin involvement, with skin necrosis in 4 patients. In total, 7 patients had joint involvement and 2 had arthritis. A total of 4 patients had nonsevere gastrointestinal involvement and 2 had nonsevere renal involvement. The median C-reactive protein level was 26 (IQR 10-66.75) mg/L, the median creatininemia level was 72 (IQR 65-81) μmol/L, and 1 patient had an estimated glomerular filtration rate of less than 60 mL/min at management. All patients received treatment, including 9 patients (75%) who received glucocorticoids. In total, 5 patients received a vaccine dose after developing IgAV, 1 of whom experienced a minor cutaneous relapse.

CONCLUSION

The baseline presentation of IgAV following COVID-19 vaccination was mild to moderate, and outcomes were favorable. Thus, a complete COVID-19 vaccination regimen should be completed in this population. Of note, a fortuitous link cannot be ruled out, requiring a worldwide pharmacovigilance search to confirm these findings.

Ceramides in Autoimmune Rheumatic Diseases: Existing Evidence and Therapeutic Considerations for Diet as an Anticeramide Treatment

Autoimmune rheumatic diseases (AIRDs) constitute a set of connective tissue disorders and dysfunctions with akin clinical manifestations and autoantibody responses. AIRD treatment is based on a comprehensive approach, with the primary aim being achieving and attaining disease remission, through the control of inflammation. AIRD therapies have a low target specificity, and this usually propels metabolic disturbances, dyslipidemias and increased cardiovascular risk. Ceramides are implicated in inflammation through several different pathways, many of which sometimes intersect. They serve as signaling molecules for apoptosis, altering immune response and driving endothelial dysfunction and as regulators in the production of other molecules, including sphingosine 1-phosphate (S1P) and ceramide 1-phosphate (C1P). With lipid metabolism being severely altered in AIRD pathology, several studies show that the concentration and variety of ceramides in human tissues is altered in patients with rheumatic diseases compared to controls. As a result, many in vitro and some in vivo (animal) studies research the potential use of ceramides as therapeutic targets in rheumatoid arthritis (RA), ankylosing spondylitis, systemic lupus erythematosus, fibromyalgia syndrome, primary Sjögren's syndrome, systemic sclerosis, myositis, systemic vasculitis and psoriatic arthritis. Furthermore, the majority of ceramide synthesis is diet-centric and, as a result, dietary interventions may alter ceramide concentrations in the blood and affect health. Subsequently, more recently several clinical trials evaluated the possibility of distinct dietary patterns and nutrients to act as anti-ceramide regimes in humans. With nutrition being an important component of AIRD-related complications, the present review details the evidence regarding ceramide levels in patients with AIRDs, the results of anti-ceramide treatments and discusses the possibility of using medical nutritional therapy as a complementary anti-ceramide treatment in rheumatic disease.

Kidney biopsy diagnosis in childhood in the Norwegian Kidney Biopsy Registry and the long-term risk of kidney replacement therapy: a 25-year follow-up

BACKGROUND

There is scarce information on biopsy-verified kidney disease in childhood and its progression to chronic kidney disease stage 5 (CKD 5). This study aims to review biopsy findings in children, and to investigate risk of kidney replacement therapy (KRT).

METHODS

We conducted a retrospective long-term follow-up study of children included in the Norwegian Kidney Biopsy Registry (NKBR) and in the Norwegian Renal Registry (NRR) from 1988 to 2021.

RESULTS

In total, 575 children with a median (interquartile range, IQR) age of 10.7 (6.1 to 14.1) years were included, and median follow-up time (IQR) after kidney biopsy was 14.3 (range 8.9 to 21.6) years. The most common biopsy diagnoses were minimal change disease (MCD; n = 92), IgA vasculitis nephritis (IgAVN; n = 76), IgA nephropathy (n = 63), and focal and segmental glomerulosclerosis (FSGS; n = 47). In total, 118 (20.5%) of the biopsied children reached CKD 5, median (IQR) time to KRT 2.3 years (7 months to 8.4 years). Most frequently, nephronophthisis (NPHP; n = 16), FSGS (n = 30), IgA nephropathy (n = 9), and membranoproliferative glomerulonephritis (MPGN; n = 9) led to KRT.

CONCLUSIONS

The risk of KRT after a kidney biopsy diagnosis is highly dependent on the diagnosis. None of the children with MCD commenced KRT, while 63.8% with FSGS and 100% with NPHP reached KRT. Combining data from kidney biopsy registries with registries on KRT allows for detailed information concerning the risk for later CKD 5 after biopsy-verified kidney disease in childhood. A higher resolution version of the Graphical abstract is available as Supplementary information.

IgA Vasculitis Following COVID-19 Vaccination

As new variants of SARS-CoV-2 continue to emerge worldwide, countries are striving to fully vaccinate their population in a bid to prevent severe disease, subsequent hospitalizations, and the associated strain on their healthcare systems and death. In this context, there is growing evidence of rare, potential side effects associated with COVID-19 vaccines. IgA vasculitis is a systemic, IgA-mediated vasculitis characterized by palpable purpura, arthralgia, abdominal pain, and renal involvement. It is the most common type of vasculitis in childhood, sporadically affecting the adult population. However, there have been multiple reports of IgA vasculitis following vaccination against COVID-19. Herein, we present the case of a 72-year-old patient with palpable purpura that developed two weeks after receiving the Pfizer BioNTech vaccine. Laboratory investigations revealed elevated serum creatinine (2.6 mg/dL), macroalbuminuria (8.6 g/24 h), and macroscopic hematuria. Histopathological examination confirmed necrotizing vasculitis, and a diagnosis of IgA vasculitis was established. Considering the clinical presentation, the laboratory and histopathological findings, and the time interval between the vaccination and the development of symptoms, we strongly believe that IgA vasculitis in this patient arose as a side effect of the Pfizer BioNTech vaccine.

Immunoglobulin a vasculitis with testicular/epididymal involvement in children: A retrospective study of a ten-year period

The clinical characteristics and risk factors for testicular/epididymal involvement in 73 children with immunoglobulin A vasculitis (IgAV) who were admitted to our hospital between January 2012 and November 2022 were reviewed. The demographic data, laboratory parameters, and follow-up data of the patients were compared to those of 146 males without testicular/epididymal involvement. A logistic regression analysis was performed to determine the variables associated with testicular/epididymal involvement. The prevalence of testicular/epididymal involvement among male patients with IgAV was 1.3% (73/5,556). Increased blood flow in the testes and/or epididymis on ultrasound was found in 71 patients. The remaining two patients underwent surgical exploration for loss or reduction of testicular blood flow. One patient underwent orchiectomy for intraoperative confirmation of complete right testicular infarction. Pathological findings revealed IgA immune complex deposition in the testis. Patient age (odds ratio [OR] = 0.792; 95% confidence interval [CI]: 0.682-0.919, p = 0.002), platelet count (OR = 1.011; 95% CI: 1.002-1.020, p = 0.013), and immunoglobulin M (IgM) levels (OR = 0.236; 95% CI: 0.091-0.608, p = 0.003) were strongly associated with the occurrence of testicular/epididymal involvement in IgAV. Therefore, young age, increased platelet count, and low IgM levels in patients with IgAV are potential risk factors for testicular/epididymal involvement. Doppler ultrasound can help differentiate IgAV from acute scrotum. Most patients with testicular/epididymal involvement have good prognoses, although serious complications such as testicular infarction may occur.

Rare case of ankylosing spondylitis complicated by IgA vasculitis

Ankylosing spondylosis (AS) is characterised by bilateral sacroiliitis, asymmetric peripheral oligoarthritis, association with the human leucocyte antigen-B27, enthesitis and dactylitis. The association of IgA vasculitis with AS has been documented in few case reports. We present a rare case of a man in his 40s with AS, who presented with fever, bloody loose stools, abdominal pain, lower limb arthritis, palpable purpura over the lower limbs. He subsequently, also developed renal involvement in the form of proteinuria. His skin biopsy showed evidence of leucocytoclastic vasculitis, while renal biopsy showed focal proliferative, necrotising IgA glomerulonephritis. He was thus diagnosed to have Henoch Schonlein purpura with IgA nephropathy in the background of AS. He was treated with steroids and mycophenolate mofetil with resolution of his symptoms.

Increased Urinary IgA in Paediatric IgA Vasculitis Nephritis

IgA vasculitis (IgAV) is the most common form of paediatric vasculitis, with up to 50% of patients experiencing kidney inflammation. Much remains unknown about IgAV, but it is believed to arise due to galactose-deficient IgA1 promoting an auto-inflammatory response. This study assesses whether urinary IgA can be detected in children with IgAV to allow further evaluation of IgA1 and whether it has any relationship with nephritis. Urinary and serum IgA concentrations were measured using commercially available ELISA kits. Patients were grouped into IgAV nephritis (IgAVN) or IgAV without nephritis (IgAVwoN). Fifty-nine children were included: IgAVN n = 12, IgAVwoN n = 35, and healthy controls (HC) n = 12, with a mean age of 8.2 ± 4.1 years. Urinary IgA concentrations were statistically significantly higher in patients with IgAV (107.1 ± 136.3 μg/mmol) compared to HC (50.6 ± 26.3 μg/mmol; p = 0.027) and IgAVN (229.8 ± 226.3 μg/mmol) compared to both IgAVwoN (65.0 ± 37.8 μg/mmol; p = 0.002) and HC (p < 0.001). Urinary IgA concentrations were able to distinguish between renal status (AUC 0.838, 95%CI [0.704−0.973], p < 0.001) and did not correlate with proteinuria (r = 0.124; p = 0.407). Urinary IgA concentrations are increased in children with IgAVN, and it has the potential to act as a non-invasive biofluid to further evaluate nephritis in this disease.

Serum Sickness-Like Reaction Associated with Epstein – Barr Virus: Clinical Case

Background. Annular dermatoses are a group of diseases with major clinical manifestation of rashes of relevant form. This manifestation pattern causes difficulties in diagnosis. The case of rarely diagnosed annular dermatosis is presented: serum siknesslike reaction (SSLR) triggered by the Epstein – Barr virus (EBV). Clinical case description. Patient D., 8 years old girl, noted abdominal pain 3 weeks before hospitalization, and later numerous polymorphic rashes (erythematous macules, urticarial elements), swelling and pain in joints. Self-treatment with non-steroidal anti-inflammatory and systemic antihistamines did not lead to any improvement. The patient was hospitalized in the pediatric department at the place of residence, where the diagnosis “Henoch-Schonlein purpura, mixed type” was established according to the results of physical, laboratory (double increase of ALT and AST, ESR up to 166 mm/h, IgM to EBV), and ultrasound (mesenteric lymph nodes hyperplasia) studies. Systemic glucocorticosteroids have led to improvement, however, few days after the end of the treatment there was relapse of rash and arthralgia. Thus, the girl was administrated to clinical diagnostic center. Patient’s general condition was satisfactory at the time of examination. There were numerous erythematous annular urticarial and macular elements (3–12 cm) on the skin of face, body and limbs. Some foci, as well as some resolved rashes had blue spots with indistinct boundaries that disappeared after compression. Mucous membranes, nails and hair were intact. Subjective symptoms — slight burning around rashes, at palpation — low-intensity pain in the left radiocarpal joint. Blood tests: C-reactive protein concentration increased up to 12 mg/L, ESR up to 26 mm/h, IgG to EBV up to 47.7. Conclusion. During differential diagnosis we should consider the possibility of SSLR development in all pediatric patients with annular rashes associated with arthralgia and/or arthritis, fever, history of drug use (most often beta-lactam antibiotics), recent vaccination or manifestations of viral infection, especially in case of cyanotic spots after rashes resolution and non-specific laboratory parameters.

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.

Advances in IgA glycosylation and its correlation with diseases

Immunoglobulin A (IgA) is the most abundant immunoglobulin synthesized in the human body. It has the highest concentration in the mucosa and is second only to IgG in serum. IgA plays an important role in mucosal immunity, and is the predominant antibody used to protect the mucosal surface from pathogens invasion and to maintain the homeostasis of intestinal flora. Moreover, The binding IgA to the FcαRI (Fc alpha Receptor I) in soluble or aggregated form can mediate anti- or pro- inflammatory responses, respectively. IgA is also known as one of the most heavily glycosylated antibodies among human immunoglobulins. The glycosylation of IgA has been shown to have a significant effect on its immune function. Variation in the glycoform of IgA is often the main characteration of autoimmune diseases such as IgA nephropathy (IgAN), IgA vasculitis (IgAV), systemic lupus erythematosus (SLE), and rheumatoid arthritis (RA). However, compared with the confirmed glycosylation function of IgG, the pathogenic mechanism of IgA glycosylation involved in related diseases is still unclear. This paper mainly summarizes the recent reports on IgA’s glycan structure, its function, its relationship with the occurrence and development of diseases, and the potential application of glycoengineered IgA in clinical antibody therapeutics, in order to provide a potential reference for future research in this field.

Sudden Onset of IgA Vasculitis Affecting Vital Organs in Adult Patients following SARS-CoV-2 Vaccines

IgA vasculitis is an immune complex-mediated small-vessel vasculitis that mainly occurs in children and is characterized by palpable purpura, arthralgia, abdominal pain, and glomerulonephritis. We report three cases of new-onset IgA vasculitis involving major organs in adult patients after they received either the ChAdOx1 viral vector (Oxford/AstraZeneca) vaccine or the messenger RNA-1273 (Moderna) vaccine. These cases suggest that COVID-19 vaccines have the potential to trigger IgA vasculitis and indicate that physicians need to monitor for this possible complication.

Urinary Protein Array Analysis to Identify Key Inflammatory Markers in Children with IgA Vasculitis Nephritis

Chronic kidney disease is a recognised complication of immunoglobulin A vasculitis, (IgAV; formerly Henoch–Schonlein purpura—HSP). The pathophysiology of IgAV and why some patients develop significant renal involvement remains largely unknown. Identifying urinary inflammatory markers could direct targets for earlier intervention. The aim of this cross-sectional exploratory study was to perform a large protein array analysis to identify urinary markers to provide insight into the mechanisms of kidney inflammation in children with established IgAV nephritis (IgAVN). Determination of the relative levels of 124 key proteins was performed using commercially available proteome profiler array kits. Twelve children were recruited: IgAVN, n = 4; IgAV without nephritis (IgAVwoN), n = 4; healthy controls (HCs), n = 4. The urinary concentrations of twenty proteins were significantly different in IgAVN compared to IgAVwoN. The largest fold changes were reported for B-cell activating factor (BAFF), Cripto-1, sex-hormone-binding globulin and angiotensinogen. The urinary levels of complement components C5/C5a and factor D were also significantly elevated in patients with IgAVN. A total of 69 urinary proteins significantly raised levels in comparisons made between IgAVN vs. HCs and nine proteins in IgAVwoN vs. HCs, respectively. This study identified key urinary proteins potentially involved in IgAVN providing new insight into the pathophysiology. Further longitudinal studies with larger cohorts are needed to quantitatively analyse these biomarkers.

Adult Onset Immunoglobulin A (IgA) Vasculitis Secondary to Group A Streptococcus Infection

Immunoglobulin A (IgA) vasculitis is a small blood vessel vasculitis that is mediated by immune complex deposition. While it is the most common cause of childhood vasculitis, the disease is uncommon in adults with variable clinical manifestations. A 65-year-old female presented with a diffuse erythematous, pruritic, painful rash across her legs, back, and arms of 12 days’ duration. Associated symptoms included fatigue, lower extremity swelling, and migratory arthralgias of the knees and ankles. Skin examination revealed edematous, blanchable, erythematous, annular papules and plaques on the legs, back, and arms with pitting edema of the lower legs. Laboratory testing revealed an elevated erythrocyte sedimentation rate, hypoalbuminemia, proteinuria, hematuria, and a positive antistreptolysin O titer, indicative of recent group A Streptococcus infection. Treatment with systemic corticosteroids led to a resolution of all her symptoms. Adult onset IgA vasculitis differs in clinical manifestation and treatment from that of the pediatric population. This case demonstrates the importance of considering IgA vasculitis as a differential diagnosis in adults presenting with small vessel vasculitis.

Blood transthyretin for predicting immunoglobulin A vasculitis nephritis outcome in children

BACKGROUND

IgA vasculitis is characterized by inflammation of the blood vessels, which can result in microvascular destruction and consequently renal damage. Transthyretin is a newly discovered angiogenesis regulator in promoting microvascular regeneration. This indicates that transthyretin may act as a potential predictor of IgAV as well as IgAVN.

METHODS

This retrospective study included 125 patients newly diagnosed as IgAV with demographic and laboratory parameters. Of these, 78 patients had demonstrated internal organ damage and 47 patients with only skin and joint injury. Of 78 patients with organ impairment, 27 were diagnosed of renal involvement. Then we evaluated the relationship between NLR, total protein, albumin, globulin, transthyretin, B lymphocyte counts and the severity of IgAV.

RESULTS

For patients with internal organ or renal involvement, the level of transthyretin were lower than non-internal organ damage group (p < 0.001 for both group). Remarkably, the NLR was only higher in patients with internal organ damage group (p = 0.019). Logistic regression analysis showed that NLR and transthyretin both were risk factors for internal organ involvement (OR = 1.768, 0.973 separately), and only transthyretin is the independent risk for renal involvement (OR = 0.981, p < 0.05). The ROC analysis showed an AUC of 0.626 for NLR, 0.815 for transthyretin in predicting organ damage, 0.755 for transthyretin in patients with renal involvement (p < 0.05, to all parameters).

CONCLUSIONS

Transthyretin is a better predictor in predicting internal organ or renal involvement than NLR, and low plasma transthyretin concentration can increase the risk of renal involvement in IgAV patients.

Risk assessment and prediction model of renal damage in childhood immunoglobulin A vasculitis

OBJECTIVES

To explore the risk factors for renal damage in childhood immunoglobulin A vasculitis (IgAV) within 6 months and construct a clinical model for individual risk prediction.

METHODS

We retrospectively analyzed the clinical data of 1,007 children in our hospital and 287 children in other hospitals who were diagnosed with IgAV. Approximately 70% of the cases in our hospital were randomly selected using statistical product service soltions (SPSS) software for modeling. The remaining 30% of the cases were selected for internal verification, and the other hospital's cases were reviewed for external verification. A clinical prediction model for renal damage in children with IgAV was constructed by analyzing the modeling data through single-factor and multiple-factor logistic regression analyses. Then, we assessed and verified the degree of discrimination, calibration and clinical usefulness of the model. Finally, the prediction model was rendered in the form of a nomogram.

RESULTS

Age, persistent cutaneous purpura, erythrocyte distribution width, complement C₃, immunoglobulin G and triglycerides were independent influencing factors of renal damage in IgAV. Based on these factors, the area under the curve (AUC) for the prediction model was 0.772; the calibration curve did not significantly deviate from the ideal curve; and the clinical decision curve was higher than two extreme lines when the prediction probability was ~15-82%. When the internal and external verification datasets were applied to the prediction model, the AUC was 0.729 and 0.750, respectively, and the Z test was compared with the modeling AUC, P > 0.05. The calibration curves fluctuated around the ideal curve, and the clinical decision curve was higher than two extreme lines when the prediction probability was 25~84% and 14~73%, respectively.

CONCLUSION

The prediction model has a good degree of discrimination, calibration and clinical usefulness. Either the internal or external verification has better clinical efficacy, indicating that the model has repeatability and portability.

CLINICAL TRIAL REGISTRATION

www.chictr.org.cn, identifier ChiCTR2000033435.

New Insights and Challenges Associated With IgA Vasculitis and IgA Vasculitis With Nephritis-Is It Time to Change the Paradigm of the Most Common Systemic Vasculitis in Childhood?

What are the challenges ahead and how have we responded so far when it comes to the non-granulomatous systemic vasculitis, characterized mainly by deposits of IgA immune complexes in the endothelium of small blood vessels-IgA vasculitis (IgAV)? That is the question to which we tried to answer. We summarized existing knowledge about epidemiology, pathogenesis, genetics, diagnostic tests and therapy in this somewhat neglected entity in pediatric rheumatology. Since etiopathogenesis of IgA vasculitis is complex, with factors other than galactose-deficient IgA₁-containing immune complexes also being important, and may involve numerous interactions between environmental and genetic factors, genomics alone cannot explain the entirety of the risk for the disease. The incidence of IgAV and nephritis varies worldwide and may be a consequence of overlapping genetic and environmental factors. In addition to the role of the HLA class II genes, some studies have pointed to the importance of non-HLA genes, and modern geostatistical research has also indicated a geospatial risk distribution, which may suggest the strong influence of different environmental factors such as climate, pathogen load, and dietary factors. The application of modern geostatistical methods until recently was completely unknown in the study of this disease, but thanks to the latest results it has been shown that they can help us a lot in understanding epidemiology and serve as a guide in generating new hypotheses considering possible environmental risk factors and identification of potential genetic or epigenetic diversity. There is increasing evidence that an integrative approach should be included in the understanding of IgA vasculitis, in terms of the integration of genomics, proteomics, transcriptomics, and epigenetics. This approach could result in the discovery of new pathways important for finding biomarkers that could stratify patients according to the risk of complications, without an invasive kidney biopsy which is still the gold standard to confirm a diagnosis of nephritis, even if biopsy findings interpretation is not uniform in clinical practice. Ultimately, this will allow the development of new therapeutic approaches, especially important in the treatment of nephritis, for which there is still no standardized treatment.