Erythrocyte Glutathione S-Transferase Activity as a Sensitive Marker of Kidney Function Impairment in Children with IgA Vasculitis.

IgA vasculitis (IgAV) is the most common childhood vasculitis. The main cause of morbidity and mortality in children with IgAV is nephritis (IgAVN), but the risk of its development, severity, and chronicity remain unclear. Erythrocyte glutathione S-transferase (e-GST) activity has been previously detected as a sensitive marker of kidney function impairment in several diseases. We spectrophotometrically assessed and correlated e-GST activity between 55 IgAV patients without nephritis (IgAVwN), 42 IgAVN patients, and 52 healthy controls. At disease onset, e-GST activity was significantly higher in IgAVN patients (median (interquartile range)) (5.7 U/gHb (4.4-7.5)) than in IgAVwN patients (3.1 U/gHb (2.2-4.2); p < 0.001), and controls (3.1 U/gHb (1.9-4.2); p < 0.001). Therewithal, there were no differences between the IgAVwN patients and controls (p = 0.837). e-GST activity was also significantly higher in the IgAVN patients than in the IgAVwN patients after 3 months (5.0 U/gHb (4.2-6.2) vs. 3.3 U/gHb (2.3-4.1); p < 0.001) and 6 months (4.2 U/gHb (3.2-5.8) vs. 3.3 U/gHb (2.1-4.1); p < 0.001) since the disease onset. Consistent correlations between e-GST activity and serum creatinine, estimated glomerular filtration rate (eGFR), and proteinuria levels were not detected. In conclusion, increased e-GST activity can serve as a subtle indicator of kidney function impairment in children with IgAV.

Serum Levels of S100A8/A9 as a Biomarker of Disease Activity in Patients with IgA Vasculitis.

S100A8/A9 protein is a well-known marker of disease activity or severity in many autoimmune and autoinflammatory diseases, but there have not been many studies about the role of S100A8/A9 in IgA vasculitis (IgAV). The aim of our study was to evaluate S100A8/A9 as a possible biomarker of activity in IgAV. We measured the serum levels of S100A8/A9 in pediatric patients with IgA vasculitis at the onset of the disease, after three months, and after six months. We compared these levels between patients with active disease, remission, and a control group, and assessed their correlation with disease activity and other markers of inflammation. Patients with active disease had significantly higher levels of serum S100A8/A9 (median ± SD) than those in the control group at the beginning of the disease (5740 ± 3157 ng/mL vs. 1447 ± 858.3 ng/mL; p < 0.0001), but also three months and six months after disease onset (p < 0.001). There was a positive correlation between S100A8/A9 serum levels and disease activity (p = 0.0003). Patients with active disease had significantly higher levels of S100A8/A9 than those in remission three months after disease onset (p = 0.0260). There was a correlation between S100A8/A9 and C-reactive protein, the C3 component of complement, ferritin, and fibrinogen. Serum levels of S100A8/A9 were also higher in patients with greater skin areas covered with rash. We demonstrated that serum levels of S100A8/A9 correlated well with disease activity and other biomarkers of inflammation in children with IgAV. According to our results, serum S100A8/A9 may be a good indicator of active disease in IgAV.

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.

HLA Polymorphisms and Clinical Manifestations in IgA Vasculitis.

Studies concerning the genetic background of IgA vasculitis (IgAV), a small-vessel vasculitis occurring predominantly in childhood, have confirmed that the HLA-DRB1 gene showed a strong association with disease susceptibility. The objective was to investigate human leukocyte antigen (HLA) polymorphisms among Croatian patients with IgAV and their influence on disease susceptibility and clinical heterogeneity. Thus, 130 children with IgAV and 202 unrelated healthy individuals were enrolled in the study. Genomic DNA was extracted from whole peripheral blood, and HLA-A, -B, -DRB1 and -DQB1 gene polymorphism analysis was performed. HLA-A*03 (21.4% vs. 12.38%, p = 0.0092), HLA-B*37 (2.9% vs. 0.2%, p = 0.0054) and HLA-DRB1*12 (3.1% vs. 0.7%, p = 0.0216) alleles were significantly more frequent in IgAV patients than in controls. High-resolution typing revealed significantly higher frequency of HLA-DRB1*10:01 and -DRB1*11:03 among IgAV patients with gastrointestinal manifestations of the disease in comparison to controls (p = 0.0021 and p = 0.0301, respectively), while HLA-DRB1*14:01P occurred significantly more often in the group of patients who developed nephritis during the course of the disease (17.5% vs. 4.5%, p = 0.0006). Our results demonstrated that there is an association of HLA-A*03, HLA-B*37 and HLA-DRB1*12 alleles with susceptibility to IgAV in the examined Croatian pediatric population. Studies which aim to determine the HLA profile may contribute to the elucidation of the genetic background of autoimmune diseases, including IgAV.

Clinical features, treatment and outcome of pediatric patients with severe cutaneous manifestations in IgA vasculitis: Multicenter international study.

OBJECTIVE: IgA vasculitis (IgAV) (formerly Henoch-Schönlein Purpura, HSP) rarely causes severe skin lesions in children. The purpose of the research was to determine whether severe skin manifestations were associated with a more severe disease course. METHODS: Severe cutaneous manifestations were defined as presence of hemorrhagic vesicles, bullae, ulcerations and/or necroses. Data were collected retrospectively from 12 international tertiary university medical centers. RESULTS: A total of 64 patients with the most severe skin changes in IgAV/HSP and median (Q1, Q3) age of 8.08 (5.08, 11.92) years at the disease onset were compared with 596 IgAV/HSP patients without these manfiestations and median (Q1, Q3) age of 6.33 (4.50, 8.92) years. The patients with severe cutaneous manifestations were older in comparison to other patients with IgAV/HSP (p<0.001), they developed nephritis more frequently (40.6% vs. 20.6%, p = 0.001) with worse outcome of renal disease (p = 0.001). This group of patients also had higher frequencies of severe gastrointestinal complications like hematochezia, massive bleeding and/or intussusception (29.3% vs. 14.8%, p<0.001). d-dimer concentrations were significantly higher in these patients (4.60 mg/L vs. 2.72 mg/L, p = 0.003) and they had more frequent need for treatment with systemic glucocorticoids (84.4% vs. 37.2%, p<0.001) in comparison with the control group. Further multivariate analysis showed that severe cutaneous changes were associated with higher risk of developing nephritis [OR=3.1 (95%CI 1.04-9.21), p = 0.042] and severe gastrointestinal complications [OR=3.65 (95%CI 1.08-12.37), p = 0.038]. CONCLUSION: Patients with IgAV/HSP and severe skin manifestations had a more severe clinical course and more frequently required glucocorticoids compared to classic IgAV/HSP patients.

The Impact of Vitamin D Levels on Clinical Manifestations of Multisystem Inflammatory Syndrome in Children: A Cross-Sectional Study.

BACKGROUND: Hyperinflammatory response that resembles Kawasaki disease may develop in children after COVID-19 disease, and it is called multisystem inflammatory syndrome in children. The cause of MIS-C is dysregulated innate immune response and a subsequent cytokine storm that results in endothelial damage. It has been determined that low levels of serum 25(OH)D increase the risk of developing immune-related diseases and disorders. METHODS: To determine the incidence of hypovitaminosis D, and a possible correlation between 25(OH)D levels and the clinical severity of MIS-C, 21 patients hospitalized in the University Hospital of Split due to MIS-C were evaluated. RESULTS: Hypovitaminosis D was detected in 95% of MIS-C patients. We found a significant relationship between the severity of MIS-C and 25(OH)D levels, as patients with more severe MIS-C had lower 25(OH)D. MIS-C patients with lower vitamin D levels had worse systolic and diastolic function of the left ventricle according to echocardiograms. There was no relationship between 25(OH)D levels and the tested laboratory inflammatory and cardiac markers. CONCLUSION: Hypovitaminosis D is very common in children with MIS-C and influences the severity of the disease. VD could be a new potential biomarker in MIS-C, and VD replacement therapy should be considered early on in the treatment of MIS-C.

Semiquantitative classification (SQC) and Oxford classifications predict poor renal outcome better than The International Study of Kidney Disease in Children (ISKDC) and Haas in patients with IgAV nephritis: a multicenter study.

INTRODUCTION: Several histologic classifications are used in the evaluation of IgA vasculitis nephritis (IgAVN), however, to date, no studies have determined which one has the strongest association with the severity of IgAVN and, as a consequence, its outcomes. MATERIALS AND METHODS: Patients included in the study were diagnosed with IgAV and IgAVN in seven tertiary university medical centers in Croatia, Italy and Israel. The International Study of Kidney Disease in Children (ISKDC), Haas, Oxford, and Semiquantitative classification (SQC) classifications were used in the analysis and description of renal biopsy. Time from biopsy to outcome evaluation was a statistically significant factor in outcome prediction that was used to define the base model, and was a covariate in all the tested models. RESULTS: Sixty-seven patients were included in this study. The SQC classification proved to be the best one in outcome prediction, followed by the Oxford classification. The ISKDC and Haas classifications could not predict renal outcome. The Oxford parameters for mesangial hypercellularity and tubular atrophy, as well as the SQC parameters for cellular crescents showed an independent statistically significant contribution to outcome prediction. High level of twenty-four hour protein excretion was associated with a higher grade in the Oxford, SQC and ISKDC classifications. Endocapillary proliferation was positively associated with the Pediatric Vasculitis Activity Score (PVAS) at diagnosis, while tubular atrophy was negatively associated. CONCLUSION: The SQC, followed by the Oxford classification were found to provide the best classifications of renal biopsy analysis in patients to predict the outcome in patients with IgAVN. Cellular crescents, mesangial hypercellularity and tubular atrophy showed significant contributions, indicating that active and chronic variables should be included in the estimation.

Persistence and Severity of Cutaneous Manifestations in IgA Vasculitis Is Associated with Development of IgA Vasculitis Nephritis in Children.

BACKGROUND/OBJECTIVE: The purpose of this study was to evaluate the prevalence and severity of skin involvement in children with IgA vasculitis (IgAV) and its relationship with clinical and biochemical parameters and the risk of developing IgA vasculitis nephritis (IgAVN), the only cause of long-term morbidity and the main prognostic factor in IgAV patients. METHODS: This national multicenter retrospective study included 611 patients under the age of 18 years with IgAV referred to five Croatian tertiary hospitals between 2009 and 2019. Patient data were collected from a database with systematic analysis of IgAV patients in the Croatian population. RESULTS: Among the 611 children, 205 (33.55%) had purpura on the lower extremities, in 207 (33.88%) the rash extended on the trunk, in 149 (24.39%) it extended to the upper extremities, in 32 (5.24%) the rash was generalized, while 15 (2.47%) had the most severe skin symptoms: bullae, ulcerations, and necroses. IgAVN developed in 130 (21.28%) and persistent IgAVN (present for >3 months) in 48 (7.86%) children. Multivariate logistic regression found that presence of ulcerations and necroses (OR 3.20 [95% CI 1.03-9.91]), persistent purpura (OR 2.89 [95% CI 1.71-4.88]), and higher age (OR 1.16 [95% CI 1.09-1.23]) were significant predictors of IgAVN, whereas persistent purpura (OR 20.11 [95% CI 1.09-372.52]), male sex (OR 3.32 [95% CI 1.13-9.80]), and higher age (OR 1.15 [95% CI 1.00-1.30]) were predictors of persistent IgAVN. Among the laboratory parameters, higher serum urea (OR 1.43 [95% CI 1.03-2.00]) and reduction in activated partial thromboplastin time (OR 0.83 [95% CI 0.74-0.93]) were shown to have a significant impact on increasing the risk of persistent IgAVN. CONCLUSION: With increasing severity and duration of cutaneous manifestations in IgAV, the risk of developing IgAVN increases, making the prognosis worse, with a greater likelihood to need more aggressive treatment.

Gastrointestinal involvement and its association with the risk for nephritis in IgA vasculitis.

BACKGROUND: We analysed clinical and biochemical parameters in predicting severe gastrointestinal (GI) manifestations in childhood IgA vasculitis (IgAV) and the risk of developing renal complications. METHODS: A national multicentric retrospective study included children with IgAV reviewed in five Croatian University Centres for paediatric rheumatology in the period 2009-2019. RESULTS: Out of 611 children, 281 (45.99%) had at least one GI manifestation, while 42 of 281 (14.95%) had the most severe GI manifestations. Using logistic regression several clinical risk factors for the severe GI manifestations were identified: generalized rash [odds ratio (OR) 2.09 (95% confidence interval (CI) 1.09-4.01)], rash extended on upper extremities (OR 2.77 (95% CI 1.43-5.34)] or face [OR 3.69 (95% CI 1.42-9.43)] and nephritis (IgAVN) [OR 4.35 (95% CI 2.23-8.50)], as well as lower values of prothrombin time (OR 0.05 (95% CI 0.01-0.62)], fibrinogen [OR 0.45 (95% CI 0.29-0.70)] and IgM [OR 0.10 (95% I 0.03-0.35)]] among the laboratory parameters. Patients with severe GI involvement more frequently had relapse of the disease [OR 2.14 (CI 1.04-4.39)] and recurrent rash [OR 2.61 (CI 1.27-5.38)]. Multivariate logistic regression found that the combination of age, GI symptoms at the beginning of IgAV and severity of GI symptoms were statistically significant predictors of IgAVN. Patients in whom IgAV has started with GI symptoms [OR 6.60 (95% CI 1.67-26.06)], older children [OR 1.22 (95% CI 1.02-1.46)] with severe GI form of IgAV (OR 5.90 (95% CI 1.12-31.15)] were particularly high-risk for developing IgAVN. CONCLUSION: We detected a group of older children with the onset of GI symptoms before other IgAV symptoms and severe GI form of the IgAV, with significantly higher risk for acute and chronic complications of IgAV.

Geospatial clustering of childhood IgA vasculitis and IgA vasculitis-associated nephritis.

OBJECTIVES: Research on spatial variability of the incidence of IgA vasculitis (IgAV) in children and its potential implications for elucidation of the multifactorial aetiology and pathogenesis is limited. We intended to observe spatial variability of the incidence of IgAV and IgA vasculitis-associated nephritis (IgAVN) using modern geostatistical methods, and hypothesised that their spatial distribution may be spatially clustered. METHODS: Patients' data were retrospectively collected from 2009 to 2019 in five Croatian University Hospital Centres for paediatric rheumatology, and census data were used to calculate the incidence of IgAV. Using spatial empirical Bayesian smoothing, local Morans' I and local indicator of spatial autocorrelation (LISA), we performed spatial statistical analysis. RESULTS: 596 children diagnosed with IgAV were included in this study, of which 313 (52.52%) were male. The average annual incidence proportion was estimated to be 6.79 per 100 000 children, and the prevalence of IgAVN was 19.6%. Existence of spatial autocorrelation was observed in both IgAV and IgAVN; however, clustering distribution differed. While IgAV showed clustering in Mediterranean and west continental part around cities, IgAVN was clustered in the northern Mediterranean and eastern continental part, where a linear cluster following the Drava and Danube river was observed. CONCLUSION: IgAV incidence in Croatia is similar to other European countries. Spatial statistical analysis showed a non-random distribution of IgAV and IgAVN. Although aetiological associations cannot be inferred, spatial analytical techniques may help in investigating and generating new hypotheses in non-communicable diseases considering possible environmental risk factors and identification of potential genetic or epigenetic diversity.

Rituximab in Treatment of Children with Refractory Vasculitis and Systemic Lupus Erythematosus - Single Center Experience in Croatia.

The aim of this study was to present our experience in rituximab therapy in patients with childhood-onset systemic lupus erythematosus, lupus nephritis, and ANCA-associated vasculitis. We conducted a retrospective clinical chart review of all patients treated with rituximab in the time period from January 2009 to December 2015. Eight patients (3 boys and 5 girls) aged 8 to 15 at the onset of disease were treated with rituximab. Remission of disease was accomplished in 4 patients with childhood-onset systemic lupus erythematosus and lupus nephritis, a partial improvement was achieved in 1 patient with childhood-onset systemic lupus erythematosus and lupus nephritis as well as in 2 patients with vasculitis, while in one patient with vasculitis treatment with rituximab showed no effect and the patient died due to Candida sepsis. Reduction of corticosteroid doses was enabled by rituximab treatment. Rituximab appeared to be a safe and efficient therapeutic option in severe cases of childhood-onset systemic lupus erythematosus or ANCA-associated vasculitis that failed to respond to conventional therapy or as a rescue therapy in life-threatening conditions.

HOW TO TREAT PATIENTS AFTER SERIOUS ADVERSE EFFECTS CAUSED BY TNF INHIBITORS?

Biological agents are widely used in the treatment of autoimmune rheumatic disorders. We report on serious adverse events during treatment with anti-tumor necrosis factor antibody in two of our patients with juvenile idiopathic arthritis. One patient was treated with a biological agent due to juvenile idiopathic arthritis complicated by uveitis, developing miliary tuberculosis during treatment. After treatment with antituberculotics, she recovered completely. Her underlying disease is currently in remission. Another patient was treated for juvenile spondyloarthritis and developed an inflammatory process of the central nervous system with serious neurological deficits. He was treated with high-dose corticosteroids, followed by slowly tapering doses of corticosteroids. His neurological deficits improved, but are still present. Similar cases have been described previously, but there are no recommendations how to treat arthritis afterwards in such patients. We would like to emphasize the need of developing guidelines for further treatment of arthritis after the occurrence of serious adverse effects during treatment with biological agents.

HEREDITARY ANGIOEDEMA DUE TO C1-INHIBITOR DEFICIENCY IN PEDIATRIC PATIENTS IN CROATIA - FIRST NATIONAL STUDY, DIAGNOSTIC AND PROPHYLACTIC CHALLENGES.

Hereditary angioedema (HAE) is a rare autosomal dominant disease with deficiency (type I) or dysfunction (type II) of C1 inhibitor, caused by mutations in the C1-INH gene, characterized by recurrent submucosal or subcutaneous edemas including skin swelling, abdominal pain and life-threatening episodes of upper airway obstruction. The aim of this study was to investigate healthcare experiences in children with HAE due to C1 inhibitor deficiency (C1-INH-HAE) in Croatia in order to estimate the number of affected children and to recommend management protocols for diagnosis, short-term prophylaxis and acute treatment. Patients were recruited during a 4-year period at five hospitals in Croatia. Complement testing was performed in patients with a positive family history. This pilot study revealed nine pediatric patients positive for C1-INH- HAE type I, aged 1-16 years, four of them asymptomatic. Before the age of one year, C1-INH levels may be lower than in adults; it is advisable to confirm C1-INH-HAE after the age of one year. Plasma-derived C1-INH is recommended as acute and short-term prophylactic treatment. Recombinant C1-INH and icatibant are licensed for the acute treatment of pediatric patients. In Croatia, HAE is still underdiagnosed in pediatric population.

Comparison of Different Diagnostic Guidelines for the Diagnosis of Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis: Single Centre Experience.

Macrophage activation syndrome (MAS) is a potentially fatal complication of systemic juvenile idiopathic arthritis (sJIA), caused by exaggerated but ineffective immune response. The aim of the study was to compare the capacity of the HLH-2004 guidelines with the capacity of the MAS guidelines from 2005, and with the new set of classification criteria from 2016 in diagnosing MAS complicating sJIA. The study included 35 children aged 1-18 diagnosed with sJIA according to ILAR criteria and treated at the Department of Pediatrics, Division of Immunology and Rheu-matology, Zagreb University Hospital Centre, in the period from 2009 to 2015. Out of 35 patients diagnosed with sJIA, there were 12 girls and 23 boys, with the mean age at disease onset (±SD) 5.51±3.65 years. Eight patients had flare of disease. With the guidelines from 2005, MAS was diag-nosed in six (17.1%) patients with sJIA. With the new set of classification criteria from 2016, MAS was diagnosed in four (11.4%) patients with sJIA. MAS was not diagnosed with the HLH-2004 guidelines. In our study, four out of six patients had MAS at the onset of sJIA, and in the rest two it occurred during relapse. Two patients with MAS developed full-blown clinical picture while another four had incomplete clinical features with minor laboratory alteration. Due to the use of different di-agnostic guidelines, we found difference in the prevalence of MAS. It was slightly higher in comparison to available studies, while other researched features, such as clinical characteristics, were similar.