Correlation between elevated platelet count and immunoglobulin levels in the early convalescent stage of Kawasaki disease

Kawasaki Disease: An update on Genetics and Pathophysiology

Kawasaki disease (KD), a systemic vasculitic condition predominantly affecting children, remains a significant challenge in pediatric health care. First identified in 1967, KD is now recognized as the primary cause of pediatric ischemic heart disease in developed countries. This review provides a comprehensive update of KD, focusing on biomarkers, pathophysiology, and genetic associations. KD's clinical manifestation, including symptoms such as persistent fever and mucocutaneous changes, often overlaps with other pediatric conditions, complicating its diagnosis. This ambiguity, especially in cases of incomplete KD, highlights the critical need for specific biomarkers and more precise diagnostic methods. Recent studies have made promising advancements in identifying serum biomarkers and microRNAs, contributing to the development of rapid diagnostic tools. However, these are yet to be fully integrated into clinical practice. The article focuses on the pathophysiological aspects of KD, highlighting the potential for targeted therapies and personalized medicine approaches based on genetic predispositions. Collaborative efforts in global research and raising public awareness about KD are emphasized as key strategies for improving its management. This review presents the current understanding of KD while pointing out the gaps and future directions in research and clinical care. The ultimate goal is to enhance diagnostic accuracy, optimize treatment strategies, and improve patient outcomes, thereby addressing the complexities of this enigmatic and potentially life-threatening condition in pediatric medicine.

Guideline for the diagnosis and treatment of incomplete Kawasaki disease in children in China

BACKGROUND

Kawasaki disease (KD) is a pyretic ailment predominantly observed in children aged below 5 years. There is currently a dearth of precise markers for timely identification of incomplete Kawasaki disease (IKD). It is imperative to develop updated, comprehensive, and evidence-based guidelines to effectively direct clinical practice.

METHODS

The guideline development group comprised individuals with diverse expertise in both content and methodology and carried out an extensive exploration of the following digital repositories: CNKI, VIP, Wanfang Data, UpToDate, BMJ, Clinical Evidence, National Guideline Clearinghouse, Joanna Briggs Institute Library, Cochrane Library, and PubMed. The entire period from the establishment of these databases until January 1, 2024 was covered. To evaluate IKD, systematic reviews and randomised controlled trials were assessed using the risk of prejudice instrument specified in the Cochrane Handbook, along with the evidence robustness framework established by the GRADE group. The recommendations were formulated based on the findings, considering the evidence strength. After several iterations of expert consensus, the relevant professional committees in China endorsed the ultimate guideline.

RESULTS

These guidelines address clinical questions regarding the classification and definition of KD, diagnosis of IKD, treatment during the acute phase of IKD, and follow-up of IKD.

CONCLUSIONS

To provide healthcare professionals with guidance and decision-making bases for the diagnosis and treatment of IKD in China, 13 recommendations were formulated based on expert consensus and evidence of best practices.

The incidence of periungual desquamation and thrombocytosis in Kawasaki disease and the importance of systematic observation in the subacute phase

Background

Periungual desquamation and thrombocytosis are characteristic of the subacute phase of Kawasaki disease (KD). However, accurate observations of periungual desquamation and thrombocytosis are lacking.

Methods

This retrospective study included patients with acute-phase KD who received treatment at seven affiliated university hospitals in Korea between 2015 and 2017. Data were extracted from an anonymized registry established by the Korean Society of Kawasaki Disease. We investigated whether the findings of patients observed according to a set protocol until the subacute stage (group I) were different from those of patients observed without the use of a protocol (group II).

Results

A total of 879 patients with KD were included in the analysis. Periungual desquamation was observed in 85% and 12.7% of patients in groups I and II, respectively. Thrombocytosis was observed in 76.7% and 44.7% of patients in groups I and II, respectively. Furthermore, compared to the initial test, the platelet counts of patients increased 100% and 67.9% in group I and II, respectively. When incomplete KD was defined only by the main symptoms during the acute stage and the diagnostic criterion of periungual desquamation during the subacute stage was excluded, the significant difference in the incidence of incomplete KD between groups I and II was no longer apparent.

Conclusion

Performing regular and detailed observations has resulted in a higher incidence of periungual desquamation and thrombocytosis during the subacute phase of KD than those reported in recent studies. This indicates that until now, we have been neglecting the observation of symptoms and signs during the subacute phase. Regular monitoring during this period can also aid in differentiating suspected cases of KD and facilitate appropriate follow-up of complications.

A decision tree model for predicting intravenous immunoglobulin resistance and coronary artery involvement in Kawasaki disease

Objectives

This study aims to develop a new algorithm for predicting intravenous immunoglobulin (IVIG) resistance and coronary artery involvement in Kawasaki disease (KD) through decision tree models.

Methods

Medical records of children hospitalized for KD were analysed retrospectively. We compared the clinical characteristics, and the laboratory data in the groups with IVIG resistance and coronary artery dilatations (CADs) in KD patients. The decision tree models were developed to predict IVIG resistance and CADs.

Results

A total 896 patients (511 males and 385 females; 1 month-12 years) were eligible. IVIG resistance was identified in 111 (12.3%) patients, and CADs were found in 156 (17.4%). Total bilirubin and nitrogen terminal- pro-brain natriuretic peptide (NT-proBNP) were significantly higher in IVIG resistant group than in IVIG responsive group (0.62 ± 0.8 mg/dL vs 1.38 ± 1.4 mg/dL and 1231 ± 2136 pg/mL vs 2425 ± 4459 mL, respectively, P < 0.01). Also, CADs were more developed in the resistant group (39/111; 14.9% vs. 117/785; 35.1%, P < 0.01). The decision tree for predicting IVIG resistance was classified based on total bilirubin (0.7 mg/mL, 1.46 mg/dL) and NT-proBNP (1561 pg/mL), consisting of two layers and four nodes, with 86.2% training accuracy and 90.5% evaluation accuracy. The Receiver Operating Characteristic (ROC) evaluated the predictive ability of the decision tree, and the area under the curve (AUC) (0.834; 95% confidence interval, 0.675–0.973; P < 0.05) showed relatively higher accuracy. The group with CADs had significantly higher total bilirubin and NT-proBNP levels than the control group (0.64 ± 0.82 mg/dL vs 1.04 ± 1.14 mg/dL and 1192 ± 2049 pg/mL vs 2268 ± 4136 pg/mL, respectively, P < 0.01). The decision trees for predicting CADs were classified into two nodes based on NT-proBNP (789 pg/mL) alone, with 83.5% training accuracy and 90.3% evaluation accuracy.

Conclusion

A new algorithm decision tree model presents for predicting IVIG resistance and CADs in KD, confirming the usefulness of NT-proBNP as a predictor of KD.

Etiological and pathophysiological enigmas of severe coronavirus disease 2019, multisystem inflammatory syndrome in children, and Kawasaki disease

During the coronavirus disease 2019 (COVID-19) pandemic, a novel multisystem inflammatory syndrome in children (MIS-C) has been reported worldwide since the first cases were reported in Europe in April 2020. MIS-C is temporally associated with severe acute respiratory syndrome coronavirus 2 infection and shows Kawasaki disease (KD)-like features. The epidemiological and clinical characteristics in COVID-19, KD, and MIS-C differ, but severe cases of each disease share similar clinical and laboratory findings such as a protracted clinical course, multiorgan involvement, and similar activated biomarkers. These findings suggest that a common control system of the host may act against severe disease insult. To solve the enigmas, we proposed the protein-homeostasis-system hypothesis in that every disease involves etiological substances and the host's immune system controls them by their size and biochemical properties. Also, it is proposed that the etiological agents of KD and MIS-C might be certain strains in the microbiota of human species and etiological substances in severe COVID-19, KD, and MIS-C originate from pathogen-infected cells. Since disease severity depends on the amounts of inflammation-inducing substances and corresponding immune activation in the early stage of the disease, an early proper dose of corticosteroids and/or intravenous immunoglobulin (IVIG) may help reduce morbidity and possibly mortality among patients with these diseases. Corticosteroids are low cost and an analogue of host-origin cortisol among immune modulators. This study's findings will help clinicians treating severe COVID-19, KD, and MIS-C, especially in developing countries, where IVIG and biologics supplies are insufficient.

Hygiene Hypothesis as the Etiology of Kawasaki Disease: Dysregulation of Early B Cell Development

Kawasaki disease (KD) is an acute systemic vasculitis that occurs predominantly in children under 5 years of age. Despite much study, the etiology of KD remains unknown. However, epidemiological and immunological data support the hygiene hypothesis as a possible etiology. It is thought that more sterile or clean modern living environments due to increased use of sanitizing agents, antibiotics, and formula feeding result in a lack of immunological challenges, leading to defective or dysregulated B cell development, accompanied by low IgG and high IgE levels. A lack of B cell immunity may increase sensitivity to unknown environmental triggers that are nonpathogenic in healthy individuals. Genetic studies of KD show that all of the KD susceptibility genes identified by genome-wide association studies are involved in B cell development and function, particularly in early B cell development (from the pro-B to pre-B cell stage). The fact that intravenous immunoglobulin is an effective therapy for KD supports this hypothesis. In this review, I discuss clinical, epidemiological, immunological, and genetic studies showing that the etiopathogenesis of KD in infants and toddlers can be explained by the hygiene hypothesis, and particularly by defects or dysregulation during early B cell development.

Bioinformatics identification of hub genes and signaling pathways regulated by intravenous immunoglobulin treatment in acute Kawasaki disease

Kawasaki disease (KD) is an acute, self-limiting form of vasculitis commonly encountered in infants and young children. Intravenous immunoglobulin (IVIG) is the primary drug used for the treatment of KD, which may significantly reduce the occurrence of coronary artery lesions. However, the specific molecular profile changes of KD caused by IVIG treatment have remained elusive and require further research. The present study was designed to identify key genes, pathways and immune cells affected by IVIG treatment using multiple bioinformatics analysis methods. The results suggested that myeloid cells and neutrophils were affected by IVIG treatment. Kyoto Encyclopedia of Genes and Genomes pathway analysis identified that hematopoietic cell lineages and osteoclast differentiation may have an important role in the mechanism of action of IVIG treatment. Immune cell analysis indicated that the levels of monocytes, M1 macrophages, neutrophils and platelets were markedly changed in patients with KD after vs. prior to IVIG treatment. The key upregulated genes, including ZW10 interacting kinetochore protein, GINS complex subunit 1 and microRNA-30b-3p in whole blood cells of patients with KD following treatment with IVIG indicated that these IVIG-targeted molecules may have important roles in KD. In addition, these genes were further examined by literature review and indicated to be involved in cell proliferation, apoptosis and virus-related immune response in patients with KD. Therefore, the present results may provide novel insight into the mechanisms of action of IVIG treatment for KD.

Identification of increased expression of activating Fc receptors and novel findings regarding distinct IgE and IgM receptors in Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is associated with expression and methylation of Fc gamma receptor genes. We characterized immunoglobulin A (IgA), IgE, IgG, and IgM receptor expression levels in KD.

METHODS

Fc receptor expression levels were characterized using GeneChip Human Transcriptome Array 2.0 (HTA 2.0) with 18 KD patients, 18 non-febrile controls, and 18 febrile controls. Another 48 control individuals and 46 patients with KD were measured using pyrosequencing for the methylation levels.

RESULTS

The mRNA expression levels of FCER1A and FCER2 were significantly lower in KD patients than in non-febrile controls and then rose following treatments with intravenous immunoglobulin (IVIG). Expression levels of FCER1G increased compared to the non-febrile subjects and then subsided after IVIG. FCER1A methylation was significantly lower among KD patients and even lower in KD patients with IVIG resistance. HTA analysis revealed higher mRNA levels of FCAR, FCGR1C, and FCGR2A in KD patients. FCMR mRNA expression levels were significantly lower in KD patients. FCMR expression levels rose after IVIG treatment. After IVIG, FCGR1A, B, and C decreased even lower than the febrile controls.

CONCLUSION

This is the first study indicating that IgA, IgE, IgG, and IgM receptors are associated with KD. We highlighted potential biomarkers related to Fc receptors and their regulation.

The Platelet microRNA Profile of Kawasaki Disease: Identification of Novel Diagnostic Biomarkers

Challenging diagnosis and unknown etiology of Kawasaki disease (KD) increase the coronary artery lesions incidence. microRNAs (miRNAs) are the most promising biomarkers because of their stability in peripheral blood and noninvasive measurement procedure, whose potential utility have been proved in cancers. To explore the utility of differentially expressed (DE) miRNAs as early diagnostic markers, 44 patients (25 incomplete KD and 19 complete KD) and 31 febrile controls were recruited for small RNA sequencing. From all the 1922 expressed miRNA, 210 DE miRNAs were found between KD and febrile control groups. Though platelet miRNA profiles of complete KD incomplete KD were much similar through cluster analysis, the DE miRNAs were not identical. Eight DE miRNAs were validated by real-time quantitative PCR (qRT-PCR) in complete or incomplete KD groups using a normalizer, miR-126-3p, which was identified by geNorm and NormFinder tools. The expression level of miRNAs continuous changed over time was observed and the function analysis showed the potential role of miRNAs as therapeutic biomarkers. Additionally, the prediction model for KD showed a sensitivity of 78.8% and a specificity of 71.4%, respectively. This study used small RNA sequencing to identify miRNA biomarkers KD diagnosis based on a large sample size. Our findings shine a light on the understanding of molecular pathogenesis of KD and may improve the accuracy of KD diagnosis and prognosis in clinical.

Low FCMR mRNA expression in leukocytes of patients with Kawasaki disease six months after disease onset

BACKGROUND

Immunoglobulin (Ig) M plays an important role in immune regulation. FCMR-encoded FcμR is a receptor of IgM. Previous research has suggested that IgM levels may be involved in the coronary artery lesions of Kawasaki syndrome or Kawasaki disease (KD). In this study, we aimed to explore the roles of mRNA expressions of IgM receptors, particularly FCMR, in KD patients. FCMR encodes the Fc fragment of immunoglobulin M receptor.

METHODS

We enrolled 60 KD patients and 55 non-KD controls. Whole-blood leukocytes were isolated, and the mRNA expression for FCMR was determined. Each mRNA consisted of a sample taken before intravenous immunoglobulin (IVIG) was administered (acute, KD1) and those taken at three weeks, six months, and one year later (KD3, KD4, KD5). Paired KD subjects were analyzed from both the acute and convalescent phases (n = 28).

RESULTS

After six months and one year of treatment, KD patients still apparently have lower FCMR compared with controls (P = .004). FCMR expressions were downregulated in male patients with KD prior to IVIG administration (P = .044). The FCMR of paired KD patients who received IVIG treatments after six months was significantly lower than before undergoing IVIG treatment (P = .044). Expressions in the polymorphonuclear leukocytes were similar to those in the peripheral blood mononuclear cells.

CONCLUSION

The unique data supported that FCMR is expressed by granulocytes at RNA levels in humans and demonstrated lower FCMR six months after the onset of KD. The findings remind us of the need to track the health of children with KD over the long term, even if we think patients have fully recovered.

Adjuvant herbal therapy for targeting susceptibility genes to Kawasaki disease: An overview of epidemiology, pathogenesis, diagnosis and pharmacological treatment of Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is a self-limiting acute systemic vasculitis occur mainly in infants and young children under 5 years old. Although the use of acetylsalicylic acid (AAS) in combination with intravenous immunoglobulin (IVIG) remains the standard therapy to KD, the etiology, genetic susceptibility genes and pathogenic factors of KD are still un-elucidated.

PURPOSE

Current obstacles in the treatment of KD include the lack of standard clinical and genetic markers for early diagnosis, possible severe side effect of AAS (Reye's syndrome), and the refractory KD cases with resistance to IVIG therapy, therefore, this review has focused on introducing the current advances in the identification of genetic susceptibility genes, environmental factors, diagnostic markers and adjuvant pharmacological intervention for KD.

RESULTS

With an overall update in the development of KD from different aspects, our current bioinformatics data has suggested CASP3, CD40 and TLR4 as the possible pathogenic factors or diagnostic markers of KD. Besides, a list of herbal medicines which may work as the adjunct therapy for KD via targeting different proposed molecular targets of KD have also been summarized.

CONCLUSION

With the aid of modern pharmacological research and technology, it is anticipated that novel therapeutic remedies, especially active herbal chemicals targeting precise clinical markers of KD could be developed for accurate diagnosis and treatment of the disease.

Kawasaki Disease and Allergic Diseases

Background: Kawasaki disease (KD) is an inflammatory disorder with an unknown etiology. It is the leading cause of acquired heart disease, which leads to coronary vasculitis among children. Studies of frequent manifestation of allergic diseases in children with KD have been the subject of mounting clinical interest. However, evidence supporting the association between KD and allergies has yet to be systematically reviewed. Methods: In this article, we reviewed current literature regarding the association between KD and allergic diseases. References for this review were identified through searches of PubMed, Cochrane, and Embase through the end of August 2020. Results: The results of the analyses of immune repertoire, clinical, and epidemiological studies have indicated some of the characteristics of infectious disease for KD. Although some allergic disorders, such as asthma, may be exacerbated by viral infections, allergies are typically caused by an allergen that triggers an immune response, with the potential involvement of type 2 inflammation and immune disturbances leading to tissue remodeling in genetically susceptible hosts. The effect of intravenous immunoglobulin is multi-faceted and results in a decrease in activating Fc gamma receptor IIA and an increase in anti-inflammatory eosinophils. The findings from this review demonstrate that children who have suffered from KD are more likely to have allergic rhinitis than the general population and their siblings, a condition that lasts until the age of 17. When followed up as teenagers and adults, children with KD are more likely to develop urticaria. Conclusions: This review supports that allergic diseases, such as allergic rhinitis, have been demonstrated to increase following KD. Therefore, the importance of allergic diseases in patients with KD should be emphasized in long-term care. Interventions that include strategies for managing allergies in children with KD would be beneficial.

Changes in and significance of platelet function and parameters in Kawasaki disease

Kawasaki disease (KD) is a systemic febrile, inflammatory vascular disease of unknown etiology. The coronary artery abnormality (CAA) caused by KD has become the most commonly acquired heart disease in children. Initial treatment of intravenous immunoglobulin (IVIG) can reduce the incidence of CAA. Thrombocytosis is common during the course of KD, but changes in and significances of platelet function and parameters are unclear. In this study, we enrolled 120 patients, including 40 patients with KD, 40 febrile controls, and 40 afebrile controls. The platelet function was assessed using the platelet function analyzer (PFA)-200. Platelet parameters, including platelet count (PLT), mean platelet volume (MPV), platelet distribution width (PDW), and platelet hematocrit (PCT) were measured. In the febrile period, the PDW and MPV were lower in KD patients (P < 0.05). The platelet function did not change significantly during the febrile period of KD but weakened in the defervescence phase. No significant differences between the CAA and normal groups, and between IVIG resistance and response groups. The diagnostic cutoff value of the PDW level for predicting KD was 10.85 fL with a sensitivity of 55% and a specificity of 77.5% (area under curve (AUC) = 0.690, 95% confidence interval (CI): 0.574–0.806, P < 0.01). Besides, the MPV level was 9.55 fL with sensitivity of 75% and specificity of 70% (AUC = 0.733, 95%CI: 0.620–0.846, P < 0.001). This is the first longitudinal study of platelet function changes in KD patients using PFA-200. Besides, lower PDW and MPV may be available markers for early diagnosis of KD.

The Platelet-to-Lymphocyte Ratio as an Inflammatory Marker in Rheumatic Diseases

The platelet-to-lymphocyte ratio (PLR) has emerged as an informative marker revealing shifts in platelet and lymphocyte counts due to acute inflammatory and prothrombotic states. PLR has been extensively examined in neoplastic diseases accompanied by immune suppression and thrombosis, which can be predicted by combined blood cell counts and their ratios. Several large observational studies have demonstrated the value of shifts in PLR in evaluating the severity of systemic inflammation and predicting infections and other comorbidities, in inflammatory rheumatic diseases. The value of PLR as an inflammatory marker increases when its fluctuations are interpreted along with other complementary hematologic indices, particularly the neutrophil-to-lymphocyte ratio (NLR), which provides additional information about the disease activity, presence of neutrophilic inflammation, infectious complications, and severe organ damage in systemic lupus erythematosus. PLR and NLR have high predictive value in rheumatic diseases with predominantly neutrophilic inflammation (e.g., Behçet disease and familial Mediterranean fever). High PLR, along with elevated platelet count, is potentially useful in diagnosing some systemic vasculitides, particularly giant-cell arteritis. A few longitudinal studies on rheumatic diseases have demonstrated a decrease in PLR in response to anti-inflammatory therapies. The main limitations of PLR studies are preanalytical faults, inadequate standardization of laboratory measurements, and inappropriate subject selection. Nonetheless, accumulating evidence suggests that PLR can provide valuable information to clinicians who encounter multisystem manifestations of rheumatic diseases, which are reflected in shifts in platelet, lymphocyte, neutrophil, or monocyte counts. Interpretation of PLR combined with complementary hematologic indices is advisable to more accurately diagnose inflammatory rheumatic diseases and predict related comorbidities.

Efficacy between low and high dose aspirin for the initial treatment of Kawasaki disease: Current evidence based on a meta-analysis

Background

Kawasaki disease (KD) is now the leading cause of acquired heart disease in children in developed countries. Intravenous immunoglobulin (IVIG) and aspirin were considered as the standard initial treatment of KD for decades. However, the optimal dose of aspirin has remained controversial. In recent years, many studies compared the efficacy of low-dose with high-dose aspirin in the acute phase of KD, but the results have not always been consistent. Therefore, we performed this meta-analysis to evaluate the efficacy of low-dose aspirin compared with high-dose for the initial treatment of KD.

Methods

Studies related to aspirin therapy for KD were selected from PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, and Google scholar through Mar 25^th, 2019. Data were analyzed using STATA Version 15.1. Additionally, publication bias and sensitivity analysis were also performed by STATA version 15.1.

Results

Six studies were included in our analysis of the rate of coronary artery lesion (CAL), five reports for IVIG-resistant KD (rKD), and four for the duration of fever and hospitalization. However, no significant differences were found between low-dose and high-dose aspirin groups in the incidence of CAL (risk ratio (RR), 0.85; 95%CI (0.63, 1.14); P = 0.28), the risk of rKD (RR, 1.39; 95%CI (1.00, 1.93); P = 0.05), and duration of fever and hospitalization (the mean standard deviation (SMD), 0.03; 95%CI (-0.16, 0.22); P = 0.78).

Conclusion

Low-dose aspirin (3–5 mg·kg^-1·d^-1) may be as effective as the use of high-dose aspirin (≥30 mg·kg^-1·d^-1) for the initial treatment of KD. Further well-designed randomized clinical trials are needed to evaluate the efficacy of low-dose aspirin for the initial treatment of KD.

A Presumed Etiology of Kawasaki Disease Based on Epidemiological Comparison With Infectious or Immune-Mediated Diseases

Background: Kawasaki disease (KD) may be associated with infection of unknown pathogen(s). For predicting of the etiology of KD, we evaluated epidemiological characteristics in KD, common infectious diseases and immune-mediated diseases in childhood. Methods: We respectively, reviewed the data of patients with KD, influenza, aseptic meningitis, exanthem subitum (ES), Mycoplasma pneumoniae (MP) pneumonia, acute pyelonephritis (APN), Henoch-Schönlein purpura (HSP), acute poststreptococcal glomerulonephritis (APSGN), and childhood asthma. We compared and interpreted epidemiological data across the groups. Results: In age distribution, KD, APN, and ES showed a similar pattern in that majority of patients were infants or young children, and other diseases showed a relatively even age-distribution which had a peak age, mainly 5-6 years, with bell-shape patterns. In annual-case pattern, there were epidemic years in aseptic meningitis and MP pneumonia, and the fluctuated annual cases were seen in other diseases. The trends of decreasing cases were seen in APSGN, HSP, and childhood asthma in recent years. In seasonal frequency, influenza or aseptic meningitis occurred in mainly winter or summer season, respectively. HSP and APSGN cases had less in summer, and KD, APN, and ES showed relatively even occurrence throughout a year without significant seasonal variations. Conclusions: Our results suggest that KD agents may be associated with normal flora that are influenced by environmental changes, since pathogens of APN and ES could be regarded as normal flora that originate from the host itself or ubiquitously existing human reservoirs.

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.

IgG levels in Kawasaki disease and its association with clinical outcomes

Previous studies have suggested an association of IgG levels (before and after IVIG infusion) with clinical outcomes in Kawasaki disease. A retrospective analysis was performed that included 418 patients with KD admitted to Tokyo Women's Medical University Yachiyo Medical Center to evaluate pre- and post-IVIG IgG levels and its relation to outcomes. All patients received an initial IVIG infusion and aspirin; IgG levels were measured in 350 patients before IVIG (pre-IVIG IgG levels) and in 373 patients 48 h after starting IVIG infusion (post-IVIG IgG levels). Media and standard deviation of the pre- and post-IVIG IgG levels were reported and classified according to age. Also, IgG z-scores were calculated according to normal values of IgG by age. The number of cases and corresponding percentage of non-responders were reported by age and total patients. The association of pre-IVIG, post-IVIG IgG levels and post-IVIG IgG level/pre-IVIG IgG level ratio with no-response was evaluated by simple logistic regression model based on the IgG z-score, and regression coefficient, X² value, p, and R² of Nagelkerke were reported. Pre-IVIG and post-IVIG IgG levels presented an association with non-responders with statistical significance. This association was more evident between post-IVIG IgG levels and non-responders. Regarding coronary alterations, it was not possible to perform an adequate statistical analysis due the small number of patients. Pre- and post-IVIG infusion IgG levels could be an important biomarker in KD as well as in other inflammatory conditions. Higher IgG levels could be associated with a more effective immunomodulatory action and associated with better clinical outcomes.

Clinical implications in laboratory parameter values in acute Kawasaki disease for early diagnosis and proper treatment

Purpose

This study aimed to analyse laboratory values according to fever duration, and evaluate the relationship across these values during the acute phase of Kawasaki disease (KD) to aid in the early diagnosis for early-presenting KD and incomplete KD patients.

Methods

Clinical and laboratory data of patients with KD (n=615) were evaluated according to duration of fever at presentation, and were compared between patients with and without coronary artery lesions (CALs). For evaluation of the relationships across laboratory indices, patients with a fever duration of 5 days or 6 days were used (n=204).

Results

The mean fever duration was 6.6±2.3 days, and the proportions of patients with CALs was 19.3% (n=114). C-reactive proteins (CRPs) and neutrophil differential values were highest and hemoglobin, albumin, and lymphocyte differential values were lowest in the 6-day group. Patients with CALs had longer total fever duration, higher CRP and neutrophil differential values and lower hemoglobin and albumin values compared to patients without CALs. CRP, albumin, neutrophil differential, and hemoglobin values at the peak inflammation stage of KD showed positive or negative correlations each other.

Conclusion

The severity of systemic inflammation in KD was reflected in the laboratory values including CRP, neutrophil differential, albumin, and hemoglobin. Observing changes in these laboratory parameters by repeated examinations prior to the peak of inflammation in acute KD may aid in diagnosis of early-presenting KD patients.