Observational study of Interleukin-21 (IL-21) does not distinguish Kawasaki disease from other causes of fever in children

SARS-CoV-2 infection in the context of Kawasaki disease and multisystem inflammatory syndrome in children

Recent studies have noted an increasing number of Kawasaki-like cases in the pediatric population following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In the literature, the condition is described as multiple inflammatory syndrome in children (MIS-C) or pediatric inflammatory syndrome (PIMS). A similar clinical course of Kawasaki disease (KD) and MIS-C causes difficulties in distinguishing between both conditions. However, the differential diagnosis is crucial since patients with MIS-C can present severe symptoms (myocardial dysfunction, fever, mucocutaneous symptoms) and require more extensive monitoring during treatment than children diagnosed with KD. Along with assessing epidemiological and genetic factors, it is imperative to estimate the risk of developing MIS-C in KD patients with confirmed SARS-CoV-2 infection. Genetic predispositions, such as the ITPKC gene polymorphism in KD, ACE deletion (D) polymorphism in SARS-CoV-2, and inborn errors of immunity (IEIs) in MIS-C affect the regulation of immune system complex clearances and cellular adaptations. The virus has a tropism for both vascular and respiratory cells, which further causes additional symptoms necessitating standard therapy with antithrombotic treatment. The diagnostic criteria for KD, MIS-C, and SARS-CoV-2 help differentiate each condition and optimize treatment strategies. Unfortunately, long-term outcomes in KD patients who develop MIS-C due to SARS-CoV-2 infection have been inadequately documented due to the timing of the pandemic, further displaying the need for longitudinal studies in these patients. This review underlines the differences in diagnosis and treatment of KD and MIS-C. Overall, children with KD may develop MIS-C in the setting of SARS-CoV-2 infection, but further research is needed to outline specific etiologies, prognostic factors, and diagnoses.

Clonal expansion and markers of directed mutation of IGHV4-34 B cells in plasmablasts during Kawasaki disease

Kawasaki disease (KD) is the leading cause of acquired heart disease in children. The cause remains unknown; however, epidemiologic and demographic data support a single preceding infectious agent may lead to KD. A variety of pathophysiologic responses have been proposed, including direct invasion of the coronary arteries, a superantigen response, and a post-infectious autoimmune phenomenon. A role for B cell responses during KD are supported by numerous findings including B cell specific markers identified in genome wide association studies. We have recently published data showing children with KD have similar plasmablast (PB) responses to children with infections. Since during other infections, cells expressing antibodies against the preceding infection are enriched in PBs, we sought to explore the specific antibodies encoded by PBs during KD. In one child we see a massive expansion in IGHV4-34 utilizing antibodies, which has been associated with autoimmunity in the past. We further explored this expansion of IGHV4-34 utilization during the peripheral PB rise with next generation sequencing (NGS) analysis and utilizing newer techniques of chromium chip single cell separation (10x Genomics®). We also utilized peptide array screening to attempt to identify an antigen to the most prolific clones.

CASP5 and CR1 as potential biomarkers for Kawasaki disease: an Integrated Bioinformatics-Experimental Study

BACKGROUND

Kawasaki disease (KD) is a pediatric inflammatory disorder causes coronary artery complications. The disease overlapping manifestations with a set of symptomatically like diseases such as bacterial and viral infections, juvenile idiopathic arthritis, Henoch-Schönlein purpura, infection of unknown etiology, group-A streptococcal and adenoviral infections, and incomplete KD could lead to misdiagnosis of the disease.

METHODS

In the present study, we applied weighted gene co-expression network analysis (WGCNA) to identify network modules of co-expressed genes in GSE73464 and also, limma package was used to identify the differentially expressed genes (DEGs) in KD expression arrays composed of GSE73464, GSE18606, GSE109351, and GSE68004. By merging the results of WGCNA and limma, we detected hub genes. Then, analyzed the peripheral blood mononuclear cells (PBMCs) of 16 patients and 8 control subjects using Real-Time Polymerase Chain Reaction (RT-PCR) to evaluate the previous results.

RESULTS

We assessed the diagnostic potency of the screened genes by plotting the area under curve (AUC). We finally identified 2 genes CASP5(Caspase 5) and CR1(Complement C3b/C4b Receptor 1) which were shown to potentially discriminate KD from other similar diseases and also from healthy people.

CONCLUSIONS

The results of RT-PCR and AUC confirmed the diagnostic potentials of two suggested biomarkers for KD.

Antibodies and Immunity During Kawasaki Disease

The cause of Kawasaki disease (KD), the leading cause of acquired heart disease in children, is currently unknown. Epidemiology studies support that an infectious disease is involved in at least starting the inflammatory cascade set off during KD. Clues from epidemiology support that humoral immunity can have a protective effect. However, the role of the immune system, particularly of B cells and antibodies, in pathogenesis of KD is still unclear. Intravenous immunoglobulin (IVIG) and other therapies targeted at modulating inflammation can prevent development of coronary aneurysms. A number of autoantibody responses have been reported in children with KD and antibodies have been generated from aneurysmal plasma cell infiltrates. Recent reports show that children with KD have similar plasmablast responses as other children with infectious diseases, further supporting an infectious starting point. As ongoing studies are attempting to identify the etiology of KD through study of antibody responses, we sought to review the role of humoral immunity in KD pathogenesis, treatment, and recovery.

Obesity and childhood asthma in male schoolchildren in Saudi Arabia: Is there a role for leptin, interleukin-4, interleukin-5, and interleukin-21?

BACKGROUND

Adiposity is associated with high serum levels of adipokines and chemokines which are possibly implicated in a co-existence of obesity and asthma.

OBJECTIVES

Elucidate the possible roles of leptin, interleukin (IL)-4, IL-5 and IL-21 in linking obesity with childhood asthma.

DESIGN

Cross-sectional, analytical.

SETTING

Population of schoolchildren in a small Saudi city.

SUBJECTS AND METHODS

The study included a representative sample of Saudi schoolchildren grouped as obese asthmatics, non-obese asthmatics, or obese nonasthmatics, with nonobese nonasthmatics as a control group. An asthma control test was done for the asthmatic groups.

MAIN OUTCOME MEASURES

Serum levels of leptin, IL-4, IL-5, and IL-21.

SAMPLE SIZE

345 male schoolchildren with a mean (SD) age of 13.0 (2.3) years.

RESULTS

Median serum leptin concentrations in obese asthmatics were significantly higher than in nonobese asthmatics ( P<.001). Uncontrolled asthmatics also had significantly higher leptin levels than controlled asthmatic children ( P<.002). Leptin levels were weakly but significantly correlated with the cytokines IL-4, IL-5, and IL-21.

CONCLUSIONS

Leptin may contribute to a link between obesity and childhood asthma. Differences in IL-21 levels between nonobese and obese asthmatics suggest that the co-existence of asthma and obesity increased IL-21 levels. Leptin plus some proinflammatory cytokines especially IL-21 may be potential predictors for asthma control in children.

LIMITATIONS

Blood sampling at different stages of asthma might influence cytokine expression.

CONFLICT OF INTEREST

None.

Association between Interleukin-21 and Interleukin-21 receptor gene polymorphisms with susceptibility to chronic hepatitis B virus infection and HBV spontaneous clearance in Iranian population

Hepatitis B virus (HBV) infection is a major public health concern due to the infection often leads to chronic infection, liver cirrhosis and also liver cancer. The host immune response to HBV infection and also genetic background play significant role in outcome of infection. Single nucleotide polymorphisms (SNPs) are the most important kind of variation in genetic sequences that caused by point mutations. As cytokines have major roles in viral infections, it seems that cytokine gene polymorphisms are independently associated with response to viral infections. Interleukin 21 (IL-21) plays an influential role in both innate and adaptive immune responses. Its specific receptor, IL-21R, produced and located on the surface of T, B and natural killer (NK) cells and is critical for the proliferation and differentiation of these immune effector cells. Many studies confirmed that the IL-21 involved in response to viral infections. We aimed to investigate the association of G/T IL-21 (rs2055979) and C/T IL-21R (rs3093390) gene polymorphisms with chronic hepatitis B virus infection and HBV spontaneous clearance in Iranian population.

METHODS

In this study, blood samples were gathered from 320 patients with chronic HBV and 310 healthy controls and also 120 HBV spontaneous clearance individuals. Following genomic DNA extraction, genotypes of the selected SNPs determined by PCR and restriction fragment length polymorphism (RFLP) method. The results were analyzed by SPSS software using Chi-square, Logistic Regression, ANOVA and Independent Samples t-Test.

RESULTS

According to our results, in IL-21R (rs3093390 C/T) gene polymorphism, allele frequency of T is statistically different in the HBV spontaneous clearance group compared to chronic HBV cases. But there is no significant difference between G/T IL-21 (rs2055979) and C/T IL-21R (rs3093390) genotypes distribution in three groups. Also we found that higher serum aspartate transaminase (AST) level in HBV spontaneous clearance group is significantly associated with TT genotype of IL-21 (rs2055979) compared to GG genotype (P value = 0.006).

DISCUSSION

Our results showed that T allele frequency in IL-21R (rs3093390 C/T) gene polymorphism could consider as a host genetic factor for HBV spontaneous clearance. Probably we can serve it as a potential prognostic genetic marker for spontaneous clearance of HBV infection.

Variation in IL-21-secreting circulating follicular helper T cells in Kawasaki disease

Objective

Circulating follicular helper T (cTfh) cells are a specialized subset of CD4⁺ T cells that express the CXC-chemokine receptor 5 (CXCR5). These cells exhibit immune activities by inducing B cell differentiation and proliferation via the secretion of interleukin (IL)-21. Multiple studies have demonstrated that cTfh cells are associated with the progression and severity of numerous diseases. To investigate the role of cTfh cells in the development of Kawasaki disease (KD), we analyzed the distinct subpopulations of cTfh cells and serum IL-21 levels in different phases of KD.

Methods

According to the differential expression of inducible co-stimulator (ICOS) and programmed cell death protein 1 (PD-1), cTfh cells were divided into distinct subsets. We used flow cytometry and flow cytometric bead arrays (CBA) to analyze subsets of CD4⁺CXCR5⁺ T cells and serum IL-21 levels. The samples were collected from control subjects and Kawasaki disease patients in the acute and remission phases.

Results

In the acute phase (AP), the percentages of ICOS^highPD-1^high, ICOS⁺PD-1⁺, ICOS⁻PD-1⁺, CD45RA⁻IL-21⁺ cTfh cells and serum IL-21 levels significantly increased. Furthermore, the percentages of ICOS^highPD-1^high and ICOS⁺PD-1⁺ cTfh cells positively correlated with erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) values, whereas the percentage of ICOS⁻PD-1⁺ cTfh cells indicated negative correlations. The percentages of ICOS⁺PD-1⁺, ICOS^highPD-1^high and CD45RA⁻IL-21⁺ cTfh cells correlated positively with serum IL-21 levels. In the remission phase (RP), the percentages of ICOS⁻PD-1⁺, CD45RA⁻IL-21⁺ cTfh cells and serum IL-21 levels were significantly decreased. In contrast, the percentages of ICOS⁺PD-1⁺, ICOS^highPD-1^high, and ICOS⁺PD-1⁻ cTfh cells were further increased. Among these subsets, only CD45RA⁻IL-21⁺ cTfh cells correlated positively with serum IL-21 levels.

Conclusions

The present study is the first investigation that examined the distribution of circulating cTfh cell subsets in Kawasaki disease. Both cTfh cells and serum IL-21 are essential to the pathogenesis of KD. Our study provides further understanding of the immune response involved in KD and offers novel insights in the pathogenetic mechanism of this disease.

Electronic supplementary material

The online version of this article (10.1186/s12865-018-0282-8) contains supplementary material, which is available to authorized users.

Serum exosomal miR-328, miR-575, miR-134 and miR-671-5p as potential biomarkers for the diagnosis of Kawasaki disease and the prediction of therapeutic outcomes of intravenous immunoglobulin therapy

The present study was conducted to screen serum exosomal microRNAs (miRNAs) for the early diagnosis of Kawasaki disease (KD) and to investigate their underlying mechanisms by analyzing microarray data under accession numbers GSE60965 [exosomal miRNA, including three pooled serum samples from 5 healthy children, 5 patients with KD and 5 patients with KD following intravenous immunoglobulin (IVIG) therapy] and GSE73577 (mRNA, including peripheral blood mononuclear cell samples from 19 patients with KD prior to and following IVIG treatment) from the Gene Expression Omnibus database. Differentially expressed miRNAs (DE-miRNAs) and genes (DEGs) were identified using the Linear Models for Microarray data method, and the mRNA targets of DE-miRNAs were predicted using the miRWalk 2.0 database. The functions of the target genes were analyzed using the Database for Annotation, Visualization and Integrated Discovery (DAVID). As a result, 65 DE-miRNAs were identified with different expression patterns between the healthy children and patients with KD and between patients with KD and patients with KD following IVIG therapy. The target genes of 15 common DE-miRNAs were predicted. Following overlapping the target genes of DE-miRNAs with 355 DEGs, 28 common genes were identified and further screened to construct a network containing 30 miRNA-mRNA regulatory associations. Of these associations, only miR-328-spectrin α, erythrocytic 1, miR-575-cyclic AMP-responsive element-binding protein 5/b-1,4-galactosyltransferase 5/WD repeat and FYVE domain-containing 3/cystatin-A/C-X-C motif chemokine receptor 1/protein phosphatase 1 regulatory subunit 3B, miR-134-acyl-CoA synthetase long chain family member 1/C-type lectin domain family 1 member A and miR-671-5p-tripartite motif containing 25/leucine rich repeat kinase 2/kinesin family member 1B/leucine rich repeat neuronal 1 were involved in the negative regulation of gene expression. Functional analysis indicated that the identified target genes may be associated with inflammation. Accordingly, serum exosomal miR-328, miR-575, miR-134 and miR-671-5p may act as potential biomarkers for the diagnosis of KD and the prediction of outcomes of the IVIG therapy by influencing the expression of inflammatory genes.

Increases in helminth-induced IL-21 protein levels disappear upon sample freezing

IL-21 is a much studied cytokine that has been implicated in the regulation of TH1, TH2, TH17 and regulatory immune responses; its signalling is a promising therapeutic target for autoimmune, inflammatory and infectious diseases. Despite its biological importance, measuring IL-21 reliably has proved difficult. ELISAs are commonly used to measure cytokines in various biological samples. However, results obtained are only as good as the quality of the sample. Here, we show that when using fresh samples, a significant increase in IL-21 was measured in the intestinal homogenate of mice infected with the intestinal worm Heligmosomoides polygyrus. This difference disappeared when samples were frozen in either liquid nitrogen for two days or at -80 °C for three weeks, with levels in both naïve and infected animals decreasing. This was not observed for the IL-13 cytokine, where freezing had no impact on levels measured. Our study highlights the importance of sample storage to measuring biomarkers. Since modulating IL-21 signalling is such an important potential therapeutic avenue, accurately measuring the levels of this cytokine is key to assessing its role in various research models and clinical settings.

Suppressed plasmablast responses in febrile infants, including children with Kawasaki disease

Background

Kawasaki disease (KD), the leading cause of acquired heart disease in children, primarily affects infants and toddlers. Investigations on immune responses during KD are hampered by a limited understanding of normal immune responses in these ages. It’s well known that Infants have poorer vaccine responses and difficulty with maintaining prolonged serum immunity, but there are few studies on human infants detailing immune deficiencies. Limited studies propose an inability to maintain life-long bone marrow plasma cells. Plasmablasts are a transitional cell form of B cells that lead to long-term Plasma cells. Plasmablasts levels rise in the peripheral blood after exposure to a foreign antigen. In adult studies, these responses are both temporally and functionally well characterized. To date, there have been few studies on plasmablasts in the predominant age range of KD.

Methods

Children presenting to an urban pediatric emergency room undergoing laboratory evaluation, who had concern of KD or had fever and symptoms overlapping those of KD, were recruited. Peripheral blood mononuclear cells were isolated and evaluated utilizing flow cytometry with specific B cell markers from 18 KD subjects and 69 febrile controls.

Results

Plasmablast numbers and temporal formation are similar between infectious disease controls and KD subjects. In both groups, infants have diminished plasmablast responses compared to older children.

Conclusion

In this single-time point survey, infants have a blunted peripheral plasmablast response. Overall, similar plasmablast responses in KD and controls support an infectious disease relationship to KD. Future time-course studies of plasmablasts in infants are warranted as this phenomenon may contribute to observed immune responses in this age group.