B Cells and Antibodies in Kawasaki Disease

Identification of a mimotope of a complex gp41 Human Immunodeficiency VIrus epitope related to a non-structural protein of Hepacivirus previously implicated in Kawasaki disease

Background

We have previously isolated a highly mutated VH1-02 antibody termed group C 76-Q13-6F5 (6F5) that targets a conformational epitope on gp41. 6F5 has the capacity to mediate Ab dependent cell cytotoxicity (ADCC). When the VH1-02 group C 76 antibodies variable chain sequence was reverted to germline (76Canc), this still retained ADCC activity. Due to this ability for the 76Canc germline antibody to functionally target this epitope, we sought to identify a protein target for vaccine development.

Methods

Initially, we interrogated peptide targeting by screening a microarray containing 29,127 linear peptides. Western blot and ELISAs were used to confirm binding and explore human serum targeting. Autoimmune targeting was further interrogated on a yeast-displayed human protein microarray.

Results

76Canc specifically recognized a number of acidic peptides. Meme analysis identified a peptide sequence similar to a non-structural protein of Hepacivirus previously implicated in Kawasaki disease (KD). Binding was confirmed to top peptides, including the Hepacivirus-related and KD-related peptide. On serum competitions studies using samples from children with KD compared to controls, targeting of this epitope showed no specific correlation to having KD. Human protein autoantigen screening was also reassuring.

Conclusions

This study identifies a peptide that can mimic the gp41 epitope targeted by 76C group antibodies (i.e. a mimotope). We show little risk of autoimmune targeting including any inflammation similar to KD, implying non-specific targeting of this peptide during KD. Development of such peptides as the basis for vaccination should proceed cautiously.

The Systemic Immune-Inflammation Index (SII) and coronary artery lesions in Kawasaki disease

Coronary artery lesions (CALs) are the most common complications of Kawasaki disease (KD) and play a crucial role in determining the prognosis of the disease. Consequently, the early identification of children with KD who are at risk of developing coronary artery damage is vitally important. We sought to investigate the relationship between the Systemic Immune-Inflammation Index (SII) and CALs in patients with KD and to assess its predictive value. We carried out a retrospective review and analysis of medical records for KD patients treated at the First Affiliated Hospital of Anhui Medical University between January 2017 and January 2023. We utilized single-variable tests, binary logistic regression analysis, ROC curve analysis, restricted cubic spline tests, and curve fitting to evaluate the association between SII and CALs. In our study, 364 patients were included, with 63 (17.3%) presenting with CALs at the time of admission. The binary logistic regression analysis indicated that SII was a significant risk factor for CALs at admission, evident in both unadjusted and models adjusted for confounders. The ROC curve analysis revealed an AUC (Area Under the Curve) value of 0.789 (95%CI 0.723-0.855, P < 0.001) for SII's predictive ability regarding CALs at admission. A consistent positive linear relationship between SII and the risk of CALs at admission was observed in both the raw and adjusted models. Our research findings suggest that SII serves as a risk factor for CALs and can be used as an auxiliary laboratory biomarker for predicting CALs.

Emerging evidence of microbial infection in causing systematic immune vasculitis in Kawasaki disease

Kawasaki disease (KD) is a systematic vasculitis that is often complicated by coronary artery lesions and is a leading cause of acquired heart disease in developed countries. Previous studies have suggested that genetic susceptibility, together with an inducing infectious agent, could be involved in KD pathogenesis; however, the precise causative agent of this disease remains unknown. Moreover, there are still debates concerning whether KD is an infectious disease or an autoimmune disease, although many studies have begun to show that various pathogens functioning as critical inducers could activate different kinds of immune cells, consequently leading to the dysfunction of endothelial cells and systematic vasculitis. Here in this review, we attempt to summarize all the available evidence concerning pathogen infections associated with KD pathogenesis. We also discuss the related mechanisms, present a future perspective, and identify the open questions that remain to be investigated, thereby providing a comprehensive description of pathogen infections and their correlations with the host immune system in leading to KD.

Roles of Oxidative Injury and Nitric Oxide System Derangements in Kawasaki Disease Pathogenesis: A Systematic Review

Kawasaki disease (KD) is an acute febrile vasculitis that occurs mostly in children younger than five years. KD involves multiple intricately connected inflammatory reactions activated by a cytokine cascade. Despite therapeutic advances, coronary artery damage may develop in some patients, who will be at risk of clinical cardiovascular events and even sudden death. The etiology of KD remains unclear; however, it may involve both genetic and environmental factors leading to aberrant inflammatory responses. Given the young age of onset, prenatal or perinatal exposure may be etiologically relevant. Multisystem inflammatory syndrome in children, a post-infectious hyper-inflammatory disorder associated with severe acute respiratory syndrome coronavirus 2, has features that overlap with those of KD. Available evidence indicates that vascular endothelial dysfunction is a critical step in the sequence of events leading to the development of cardiovascular lesions in KD. Oxidative stress and the dysregulation of the nitric oxide (NO) system contribute to the pathogenesis of inflammatory responses related to this disease. This review provides current evidence and concepts highlighting the adverse effects of oxidative injury and NO system derangements on the initiation and progression of KD and potential therapeutic strategies for cardiovascular pathologies in affected children.

Multisystem Inflammatory Syndrome in Children and Kawasaki Disease: A Spectrum of Postinfectious Hyperinflammatory Disease

Kawasaki disease and multisystem inflammatory syndrome in children are hyperinflammatory conditions that share similar emerging pathophysiology hypotheses, clinical features, treatment strategies, and outcomes. Although both conditions have key differences, growing evidence suggests that both conditions might be closely related on a larger spectrum of postinfectious autoimmune responses.

Autoimmune Heart Disease: A Comprehensive Summary for Forensic Practice

Autoimmune heart disease is a non-random condition characterised by immune system-mediated aggression against cardiac tissue. Cardiac changes often exhibit nonspecific features and, if unrecognised, can result in fatal outcomes even among seemingly healthy young individuals. In the absence of reliable medical history, the primary challenge lies in differentiating between the various cardiopathies. Numerous immunohistochemical and genetic studies have endeavoured to characterise distinct types of cardiopathies, facilitating their differentiation during autopsy examinations. However, the presence of a standardised protocol that forensic pathologists can employ to guide their investigations would be beneficial. Hence, this summary aims to present the spectrum of autoimmune cardiopathies, including emerging insights such as SARS-CoV-2-induced cardiopathies, and proposes the utilisation of practical tools, such as blood markers, to aid forensic pathologists in their routine practice.

Basophils Predict Mite Sensitization in Patients with Kawasaki Disease

Background: Patients with Kawasaki disease (KD) are at a significantly increased risk of allergic diseases. Immunoglobulin E (IgE) is an immunoglobulin that mediates allergic sensitization to various allergens and is related to various allergic diseases. However, few studies have analyzed specific IgE on allergy biomarkers after KD is diagnosed. Objective: This study aimed to investigate the pattern of specific IgE levels against food and inhalant allergens. Methods: This retrospective study was conducted in Taiwan to identify patients admitted with KD. A subset of 453 admitted KD children younger than or equal to five years of age with intravenous immunoglobulin (IVIG) was followed up at our clinic with available specific IgE data. Results: The most common allergens were Dermatophagoides farina or pteronyssinus, house-dust, and cockroach mix. Positive specific IgE for Dermatophagoides farina or pteronyssinus was less common in children diagnosed with KD who were two years old or younger (p = 0.028). KD patients with higher basophils before IVIG (p = 0.010 and 0.018 for two different mites) and higher C-reactive protein (CRP, p = 0.030 and 0.028) after IVIG were at higher risk of mite sensitization. Integrated mite sensitization demonstrated higher basophils before IVIG, age at KD diagnosis, and the male sex to be clinically meaningful after logistic regression models. Conclusions: This study is the first to suggest that specific IgE in KD patients may be correlated with age at KD diagnosis, as well as basophils. Further longitudinal prospective studies are warranted to clarify the unique profile of specific IgE in KD patients.

Presence of coronary aneurysms during Kawasaki Disease (KD) correlates with lower levels of autoantibodies to both full form and spliced variant of immune regulator Del-1

Kawasaki disease (KD), a rare multisystem inflammatory condition that predominantly affects children under six years of age, is the leading cause of childhood-acquired heart disease in developed countries. The pathogenesis is unknown, but studies support that an infectious stimulus triggers an autoimmune reaction in a genetically susceptible child. Recent studies demonstrated an association with autoantibody response to Del-1 (also known as EDIL3) in children with KD. Del-1 is an extracellular matrix protein that is expressed both in macrophages and vascular endothelium. Del-1 has an anti-inflammatory role by preventing leucocyte migration to inflammatory sites. Del-1 has two expression variants and genetic variants of Del-1 have been associated with the risk of intracranial aneurysms. Due to the physiologic plausibility for a role during KD, we chose to assess if autoantibodies against DEL-1 are seen in a larger cohort of children with KD and to assess if responses correlated to aneurysm formation. Contrary to prior findings, in comparison to febrile controls, autoantibodies were not overall higher in children with KD. Elevation in Post-IVIG samples in comparison to pre-IVIG and convalescent samples supports the commonality of anti-Del-1 antibodies. Autoantibodies were notably lower in children with KD who had coronary Z score elevations in comparison to those who did not.

Neurological involvement, immune response, and biomarkers in Kawasaki disease along with its pathogenesis, therapeutic and diagnostic updates

Kawasaki disease is an acute, febrile disease that is not typically fatal if treated and affects infants and children more commonly. More than 80% of the afflicted patients are under the age of four. This disease most commonly affects coronary arteries. In a minority of cases, Aneurysms can burst or produce thrombosis, and they can cause infarction. The distinctive redness in the palms and soles of the feet might result from a delayed-type hypersensitivity reaction to a cross-reactive or recently discovered antigen (s). Autoantibodies against epithelial cells and smooth muscle cells are produced as a result of subsequent macromolecule synthesis and polyclonal white blood cell activation, which intensifies the redness. Kawasaki disease's clinical manifestations range from oral skin disease to the blistering of the mucosa, symptoms involving the hands and the feet, skin disease of the palms and soles, a desquamative rash, and cervical lymphatic tissue enlargement (so it is also referred to as tissue layer lymphatic tissue syndrome). Most untreated patients develop some vessel sequelae, from well-organized coronary inflammation to severe arterial blood vessel dilatation to giant artery aneurysms with rupture or occlusion, infarction, and thrombosis. With human gamma globulin administration, reasonable standards of medical care, and the use of analgesics, the speed of symptomatic progression and inflammatory artery changes are reduced. In this review, we have covered the immunology of Kawasaki disease, its biomarkers, and the neurological manifestations of this multisystem illness. We have also included a discussion on its pathogenesis, diagnosis, and treatment.

Neurological involvement, immune response, and biomarkers in Kawasaki disease along with its pathogenesis, therapeutic and diagnostic updates

Kawasaki disease is an acute, febrile disease that is not typically fatal if treated and affects infants and children more commonly. More than 80% of the afflicted patients are under the age of four. This disease most commonly affects coronary arteries. In a minority of cases, Aneurysms can burst or produce thrombosis, and they can cause infarction. The distinctive redness in the palms and soles of the feet might result from a delayed-type hypersensitivity reaction to a cross-reactive or recently discovered antigen (s). Autoantibodies against epithelial cells and smooth muscle cells are produced as a result of subsequent macromolecule synthesis and polyclonal white blood cell activation, which intensifies the redness. Kawasaki disease's clinical manifestations range from oral skin disease to the blistering of the mucosa, symptoms involving the hands and the feet, skin disease of the palms and soles, a desquamative rash, and cervical lymphatic tissue enlargement (so it is also referred to as tissue layer lymphatic tissue syndrome). Most untreated patients develop some vessel sequelae, from well-organized coronary inflammation to severe arterial blood vessel dilatation to giant artery aneurysms with rupture or occlusion, infarction, and thrombosis. With human gamma globulin administration, reasonable standards of medical care, and the use of analgesics, the speed of symptomatic progression and inflammatory artery changes are reduced. In this review, we have covered the immunology of Kawasaki disease, its biomarkers, and the neurological manifestations of this multisystem illness. We have also included a discussion on its pathogenesis, diagnosis, and treatment.

B Cells at the Cross-Roads of Autoimmune Diseases and Auto-Inflammatory Syndromes

Whereas autoimmune diseases are mediated primarily by T and B cells, auto-inflammatory syndromes (AIFS) involve natural killer cells, macrophages, mast cells, dendritic cells, different granulocyte subsets and complement components. In contrast to autoimmune diseases, the immune response of patients with AIFS is not associated with a breakdown of immune tolerance to self-antigens. Focusing on B lymphocyte subsets, this article offers a fresh perspective on the multiple cross-talks between both branches of innate and adaptive immunity in mounting coordinated signals that lead to AIFS. By virtue of their potential to play a role in adaptive immunity and to exert innate-like functions, B cells can be involved in both promoting inflammation and mitigating auto-inflammation in disorders that include mevalonate kinase deficiency syndrome, Kawasaki syndrome, inflammatory bone disorders, Schnitzler syndrome, Neuro-Behçet's disease, and neuromyelitis optica spectrum disorder. Since there is a significant overlap between the pathogenic trajectories that culminate in autoimmune diseases, or AIFS, a more detailed understanding of their respective roles in the development of inflammation could lead to designing novel therapeutic avenues.

Severe Agitation as an Unusual Presentation of Multisystem Inflammatory Syndrome in Children

Multisystem inflammatory syndrome in children (MIS-C) is a rare hyperinflammatory syndrome that mainly affects children after a primary infection with coronavirus disease 2019 (COVID-19), with the possibility of severe and lethal complications. We report a case of a unique presentation of MIS-C in a four-year-old boy who presented with severe agitation, muscle spasms, and two days of fever. Other findings consistent with MIS-C were revealed later, and he was managed with intravenous immunoglobulin (IVIG) and steroids. He showed a dramatic response of improvement and was discharged. This case report aimed to raise health professionals' awareness about the atypical presentations of MIS-C and the importance of early diagnosis, treatment, and follow-up MIS-C cases to avoid complications affecting children's lives.

Advances in understanding Kawasaki disease-related immuno-inflammatory response and vascular endothelial dysfunction

Kawasaki disease (KD) is a systemic vasculitis of unknown etiology, which tends to involve coronary arteries and can lead to acquired heart disease in children. The immuno-inflammatory response and vascular endothelial dysfunction are important causes of coronary artery disease in patients with KD. Multisystem inflammatory syndrome in children (MIS-C) is a rare inflammatory disease in children identified in recent years, which is caused by severe acute respiratory syndrome coronavirus 2 infection; this disease overlaps with KD. This review examines research progress concerning the immuno-inflammatory response and vascular endothelial dysfunction associated with KD, as well as differences between KD and MIS-C.

Mechanisms of Immune Dysregulation in COVID-19 Are Different From SARS and MERS: A Perspective in Context of Kawasaki Disease and MIS-C

Coronaviruses have led to three major outbreaks to date-Severe Acute Respiratory Syndrome (SARS; 2002), Middle East Respiratory Syndrome (MERS; 2012) and the ongoing pandemic, Coronavirus Disease (COVID-19; 2019). Coronavirus infections are usually mild in children. However, a few children with MERS had presented with a severe phenotype in the acute phase resulting in progressive pneumonic changes with increasing oxygen dependency and acute respiratory distress requiring ventilatory support. A subset of children with a history of SARS-CoV-2 infection develops a multisystem hyper-inflammatory phenotype known as Multisystem Inflammatory Syndrome in Children (MIS-C). This syndrome occurs 4-6 weeks after infection with SARS-CoV-2 and has been reported more often from areas with high community transmission. Children with MIS-C present with high fever and often have involvement of cardiovascular, gastrointestinal and hematologic systems leading to multiorgan failure. This is accompanied by elevation of pro-inflammatory cytokines such as IL-6 and IL-10. MIS-C has several similarities with Kawasaki disease (KD) considering children with both conditions present with fever, rash, conjunctival injection, mucosal symptoms and swelling of hands and feet. For reasons that are still not clear, both KD and MIS-C were not reported during the SARS-CoV and MERS-CoV outbreaks. As SARS-CoV-2 differs from SARS-CoV by 19.5% and MERS by 50% in terms of sequence identity, differences in genomic and proteomic profiles may explain the varied disease immunopathology and host responses. Left untreated, MIS-C may lead to severe abdominal pain, ventricular dysfunction and shock. Immunological investigations reveal reduced numbers of follicular B cells, increased numbers of terminally differentiated CD4+T lymphocytes, and decreased IL-17A. There is still ambiguity about the clinical and immunologic risk factors that predispose some children to development of MIS-C while sparing others. Host-pathogen interactions in SARS, MERS and COVID-19 are likely to play a crucial role in the clinical phenotypes that manifest. This narrative review focuses on the immunological basis for development of MIS-C syndrome in the ongoing SARS-CoV-2 pandemic. To the best of our knowledge, these aspects have not been reviewed before.

Cytokine Cascade in Kawasaki Disease Versus Kawasaki-Like Syndrome

Kawasaki disease (KD) is a medium vessel systemic vasculitis that predominantly occurs in children below five years of age. It is an acute febrile condition in which coronary artery aneurysms and myocarditis are the most common cardiovascular complications. It is most often characterized by hypercytoki-nemia. The etiopathogenesis of KD is not fully understood. The present review synthesizes the recent advances in the pathophysiology and treatment options of KD. According to different studies, the genetic, infections and autoimmunity factors play a major role in pathogenesis. Several susceptibility genes (e.g. caspase 3) and cytokines (e.g. IL-2, IL-4, IL-6, IL-10, IFN-γ and TNF-α) have been identified in KD. Patients with high cytokine levels are predisposed to KD shock syndrome. The importance of respiratory viruses in the pathogenesis of the disease is unclear. Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may induce in children and adults an abnormal systemic inflammatory response. This syndrome shares characteristics with KD. It has been called by many terms like MIS-C (Multisystem Inflammatory Syndrome in Children), PIMS-TS (pediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2), hyperinflammatory shock syndrome, cytokine storm (cytokine release syndrome) or simply, Kawasaki-like syndrome. The cytokine’s role in the development of KD or Kawasaki-like syndrome being triggered by COVID-19 is controversial. The presences of the antiendothelial cell autoantibodies (AECAs) together with the newly developed hypothesis of immunothrombosis are considered potential pathogenic mechanisms for KD. In consequence, the diagnosis and treatment of KD and Kawasaki-like syndrome, one of the most common causes of acquired heart disease in developed countries, are challenging without a clearly defined protocol.

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.

A Review of Coronaviruses Associated With Kawasaki Disease: Possible Implications for Pathogenesis of the Multisystem Inflammatory Syndrome Associated With COVID-19

Multisystem Inflammatory Syndrome in Children (MIS-C), representing a new entity in the spectrum of manifestations of COVID-19, bears symptomatic resemblance with Kawasaki Disease (KD). This review explores the possible associations between KD and the human coronaviruses and discusses the pathophysiological similarities between KD and MIS-C and proposes implications for the pathogenesis of MIS-C in COVID-19. Since 2005, when a case-control study demonstrated the association of a strain of human coronavirus with KD, several studies have provided evidence regarding the association of different strains of the human coronaviruses with KD. Thus, the emergence of the KD-like disease MIS-C in COVID-19 may not be an unprecedented phenomenon. KD and MIS-C share a range of similarities in pathophysiology and possibly even genetics. Both share features of a cytokine storm, leading to a systemic inflammatory response and oxidative stress that may cause vasculitis and precipitate multi-organ failure. Moreover, antibody-dependent enhancement, a phenomenon demonstrated in previous coronaviruses, and the possible superantigenic behavior of SARS-CoV-2, possibly may also contribute toward the pathogenesis of MIS-C. Lastly, there is some evidence of complement-mediated microvascular injury in COVID-19, as well as of endotheliitis. Genetics may also represent a possible link between MIS-C and KD, with variations in FcγRII and IL-6 genes potentially increasing susceptibility to both conditions. Early detection and treatment are essential for the management of MIS-C in COVID-19. By highlighting the potential pathophysiological mechanisms that contribute to MIS-C, our review holds important implications for diagnostics, management, and further research of this rare manifestation of COVID-19.

Identification of rare coding variants associated with Kawasaki disease by whole exome sequencing

Kawasaki disease (KD) is an acute pediatric vasculitis that affects genetically susceptible infants and children. To identify coding variants that influence susceptibility to KD, we conducted whole exome sequencing of 159 patients with KD and 902 controls, and performed a replication study in an independent 586 cases and 732 controls. We identified five rare coding variants in five genes (FCRLA, PTGER4, IL17F, CARD11, and SIGLEC10) associated with KD (odds ratio [OR], 1.18 to 4.41; p = 0.0027–0.031). We also performed association analysis in 26 KD patients with coronary artery aneurysms (CAAs; diameter > 5 mm) and 124 patients without CAAs (diameter < 3 mm), and identified another five rare coding variants in five genes (FGFR4, IL31RA, FNDC1, MMP8, and FOXN1), which may be associated with CAA (OR, 3.89 to 37.3; p = 0.0058–0.0261). These results provide insights into new candidate genes and genetic variants potentially involved in the development of KD and CAA.

High Serum Total IgE at Admission Is Associated with Coronary Artery Lesions in Children with Kawasaki Disease

Kawasaki disease (KD) is associated with allergy. As immunoglobulin E (IgE), a key element of allergic reactions, is related with coronary heart disease, we evaluated the serum total IgE levels, and investigated its clinical relevance in 339 children with KD. These patients were classified as high IgE group and normal IgE group according to the reference value of IgE. Serum IgE levels in the high group (279.76 ± 202.54 IU/mL) significantly increased compared with the normal group (5.51 ± 15.79 IU/mL) (p < 0.001). There were also no significant differences in the frequency of major clinical manifestation between the two groups. The number of patients who developed coronary artery lesions (CALs) was significantly higher in the high group (p = 0.004), and the serum levels of IgE were also markedly higher in the KD patients with CALs than in patients without CALs (p = 0.002). High total serum IgE was an independent prognostic for CALs in the multivariate analysis. In conclusion, serum IgE levels may be associated with CALs in children with KD.

Atlas of circulating immune cells in Kawasaki disease

Increasing evidence shows that the pathogenesis of Kawasaki disease (KD) is caused by abnormal and unbalanced innate and adaptive immune responses. However, the changes in and functions of adaptive immune cells in the peripheral blood of subjects with KD remain controversial. In this study, three different methods, CIBERSORT, Immune Cell Abundance Identifier (ImmuCellAI), and immune cell markers, were used to evaluate the proportions and abundances of immune cells in eight KD datasets (GSE9863, GSE9864, GSE18606, GSE63881, GSE68004, GSE73461, GSE73463, and GSE64486; a total of 1,251 samples). Compared with those in normal controls and convalescent KD samples, the proportions and abundances of innate immune cells such as neutrophils, monocytes, and macrophages in acute KD peripheral blood samples were significantly increased, while those of adaptive immune cells such as B and T cells were significantly decreased. The change tendencies of these immune cells were similar to those observed in other febrile illnesses but were more significant. However, in the coronary artery tissues of patients with convalescent KD, adaptive immune cells, especially B cells and CD8+ T cell subsets, were significantly increased. This result suggests that adaptive immune cells can be selectively recruited from peripheral blood into the coronary arteries. In addition, we found that elevated neutrophils in peripheral blood could be used as a biomarker to assist in the differential diagnosis of KD, but we did not find immune cells that could accurately predict intravenousimmunoglobulin (IVIG) responses in multiple datasets.

CD24 for Cardiovascular Researchers: A Key Molecule in Cardiac Immunology, Marker of Stem Cells and Target for Drug Development

The study of the membrane protein, CD24, and its emerging role in major disease processes, has made a huge leap forward in the past two decades. It appears to have various key roles in oncogenesis, tumor progression and metastasis, stem cell maintenance and immune modulation. First described in the 1980s as the homologous human protein to the mouse HSA (Heat Stable Antigen), it was reported as a surface marker in developing hematopoietic cell lines. The later discovery of its overexpression in a large number of human neoplasms, lead cancer researchers to discover its various active roles in critical checkpoints during cancer development and progression. Targeting CD24 in directed drug development showed promising results in cancer treatment. More recently, the chimeric CD24-Fc protein has shown exciting results in clinical trials as a specific modulator of auto-inflammatory syndromes. This report is aimed to summarize the relevant literature on CD24 and tie it together with recent advancements in cardiovascular research. We hypothesize that CD24 is a promising focus of research in the understanding of cardiovascular disease processes and the development of novel biological therapies.

Activin a suppresses peripheral CD8+ T lymphocyte activity in acute-phase Kawasaki disease

BACKGROUND

Kawasaki disease is an autoimmune disease characterized by systemic vasculitis of unknown aetiology and most commonly occurs in children under 5 years old. Previous studies have found that the over-activation of lymphocytes is an important mechanism of Kawasaki disease. Activin A, also known as immunosuppressive factor P, is a multifunctional growth and transforming factor. However, whether activin A is involved in the regulation of peripheral lymphocytes activity in Kawasaki disease is unclear. Thus, we aimed to investigate the effect of activin A on the activity of peripheral lymphocytes in acute-phase Kawasaki disease.

METHODS

Seven patients with Kawasaki disease and seven healthy controls were studied. Peripheral blood lymphocytes were isolated by Ficoll density gradient centrifugation. The activation of CD4⁺ and CD8⁺ T cells and CD19⁺ B cells was investigated by flow cytometry. The expression of activin type IIA receptors was investigated by flow cytometry.

RESULTS

Immune imbalance in CD4 and CD8 lymphocytes were detected in acute-phase Kawasaki disease. The expression of activin type IIA receptors on CD8⁺ T cells and CD19⁺ B cells was increased in acute-phase Kawasaki disease and decreased following treatment with activin A. Activin A suppressed the expression of CD25 and CD69 on CD8⁺ T cells and the expression of CD69 on CD19⁺ B cells.

CONCLUSIONS

The expression of activin type IIA receptor was increased on CD8⁺ T cells and CD19⁺ B cells in Kawasaki disease. Activin A suppressed the expression of CD25, CD69 and activin type IIA receptors on peripheral CD8⁺ T lymphocyte. Activin A plays different roles in different lymphocyte subsets and suppresses peripheral CD8⁺ T lymphocyte activity in acute-phase Kawasaki disease.

The Mystery of MIS-C Post-SARS-CoV-2 Infection

Following emergence of the coronavirus disease 2019 (COVID-19) pandemic, a surge in the life-threatening illness now termed 'multisystem inflammatory syndrome in children' (MIS-C) has raised questions about the unique effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in children and adolescents. Two important new studies by Consiglio et al. and Gruber et al. have begun to shine light on the immune drivers of this enigmatic disease.

Kawasaki Disease: an Update

PURPOSE OF REVIEW

Provide the most recent updates on the epidemiology, pathogenesis, and treatment advances in Kawasaki disease.

RECENT FINDINGS

Treatment advances in complex, IVIG-refractory cases of Kawasaki disease. Multisystem inflammatory syndrome, a newly reported inflammatory condition with Kawasaki-like features and an association with the 2019 Coronavirus (COVID-19). Kawasaki disease (KD) is a rare systemic inflammatory disease that predominately affects children less than 5 years of age. Pathogenesis of KD remains unknown; the leading theory is that an unknown stimulus triggers an immune-mediated inflammatory cascade in a genetically susceptible child. Classic KD is a clinical diagnosis based on set criteria and excluding other similar clinical entities. Patients who do not fulfill complete diagnostic criteria for KD are often referred to as atypical (or incomplete) KD. The most feared complication of KD is coronary artery abnormality development, and patients with atypical KD are also at risk. Administration of intravenous immunoglobulin (IVIG) and aspirin has greatly reduced the incidence of coronary lesions in affected children. Several other immune-modulating therapies have recently been utilized in complex or refractory cases.

Clinical Utility of a Highly Sensitive Lateral Flow Immunoassay as determined by Titer Analysis for the Detection of anti-SARS-CoV-2 Antibodies at the Point-of-Care

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), became a pandemic in early 2020. Lateral flow immunoassays for antibody testing have been viewed as a cheap and rapidly deployable method for determining previous infection with SARS-CoV-2; however, these assays have shown unacceptably low sensitivity. We report on nine lateral flow immunoassays currently available and compare their titer sensitivity in serum to a best-practice enzyme-linked immunosorbent assay (ELISA) and viral neutralization assay. For a small group of PCR-positive, we found two lateral flow immunoassay devices with titer sensitivity roughly equal to the ELISA; these devices were positive for all PCR-positive patients harboring SARS-CoV-2 neutralizing antibodies. One of these devices was deployed in Northern Italy to test its sensitivity and specificity in a real-world clinical setting. Using the device with fingerstick blood on a cohort of 27 hospitalized PCR-positive patients and seven hospitalized controls, ROC curve analysis gave AUC values of 0.7646 for IgG. For comparison, this assay was also tested with saliva from the same patient population and showed reduced discrimination between cases and controls with AUC values of 0.6841 for IgG. Furthermore, during viral neutralization testing, one patient was discovered to harbor autoantibodies to ACE2, with implications for how immune responses are profiled. We show here through a proof-of-concept study that these lateral flow devices can be as analytically sensitive as ELISAs and adopted into hospital protocols; however, additional improvements to these devices remain necessary before their clinical deployment.

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.

Increased Interleukin-35 suppresses peripheral CD14+ monocytes function in patients with Kawasaki disease

Background

Interleukin-35 (IL-35) is a newly identified IL-12 cytokine family member, which regulates the activity of immune cells in infectious diseases and autoimmune disorders. However, the regulatory function of IL-35 in Kawasaki disease is not well elucidated.

Methods

Thirty-three patients with Kawasaki disease and seventeen healthy controls were studied. Peripheral IL-35 concentration was measured by enzyme linked immunosorbent assay. CD14⁺ monocytes were purified, and mRNA expression of IL-35 receptor (IL-12Rβ2 and gp130) was semi-quantified by real-time polymerase chain reaction. CD14⁺ monocytes were stimulated with recombinant IL-35. The modulatory role of IL-35 treated CD14⁺ monocytes to naïve CD4⁺ T cell activation was investigated by flow cytometry. The influence of IL-35 to cytotoxicity of CD14⁺ monocytes was assessed by measuring target cell death, cytokine and granzyme secretion.

Results

Plasma IL-35 concentration was elevated in patients with Kawasaki disease. There was no significant differences of either IL-12Rβ2 or gp130 mRNA expression in CD14⁺ monocytes between Kawasaki disease patients and controls. IL-35 suppressed CD14⁺ monocytes induced naïve CD4⁺ T cell activation in Kawasaki disease, and this process required direct cell-to-cell contact. IL-35 also inhibited tumor necrosis factor-α and granzyme B secretion by CD14⁺ monocytes from patients with Kawasaki disease, however, only granzyme B was responsible for the cytotoxicity of CD14⁺ monocytes.

Conclusions

IL-35 played an important immunosuppressive role to CD14⁺ monocytes function in Kawasaki disease.

A framework for understanding Kawasaki disease pathogenesis

Kawasaki disease (KD) is a common vasculitis of childhood, typically affecting children under the age of five. Despite many aspects of its presentation that bear resemblence to acute infection, no causative infectious agent has been identified despite years of intense scrutiny. Unlike most infections, however, there are significant differences in racial predilection that suggest a strong genetic influence. The inflammatory response in KD specifically targets the coronary arteries, also unusual for an infectious condition. In this review, we discuss recent hypotheses on KD pathogenesis as well as new insights into the innate immune response and mechanisms behind vascular damage. The pathogenesis is complex, however, and remains inadequately understood.

Association of the IL16 Asn1147Lys polymorphism with intravenous immunoglobulin resistance in Kawasaki disease

Kawasaki disease (KD) is an acute, self-limited vasculitis, mainly affecting children younger than 5 years old, with accompanying fever and signs of mucocutaneous inflammation. Intravenous immunoglobulin (IVIG) is the standard treatment for KD; however, ~15% of patients are resistant to IVIG treatment. To identify protein coding genetic variants influencing IVIG resistance, we re-analyzed our previous genome-wide association study (GWAS) data from 296 patients with KD, including 101 IVIG non-responders and 195 IVIG responders. Five nonsynonymous SNPs (nsSNPs) in five immune-related genes, including a previously reported SAMD9L nsSNP (rs10488532; p.Val266Ile), were associated with IVIG non-response (odds ratio [OR] = 1.89-3.46, P = 0.0109-0.0035). In a replication study of the four newly-identified nsSNPs, only one in the interleukin 16 (IL16) gene (rs11556218, p.Asn1147Lys) showed a trend of association with IVIG non-response (OR = 1.54, P = 0.0078). The same IL16 nsSNP was more significantly associated with IVIG non-response in combined analysis of all data (OR = 1.64, P = 1.25 × 10^-4). Furthermore, risk allele combination of the IL16 CT and SAMD9L TT nsSNP genotypes exhibited a very strong effect size (OR = 9.19, P = 3.63 × 10^-4). These results implicate IL16 as involved in the mechanism of IVIG resistance in KD.

Current State of Precision Medicine in Primary Systemic Vasculitides

Precision medicine (PM) is an emerging data-driven health care approach that integrates phenotypic, genomic, epigenetic, and environmental factors unique to an individual. The goal of PM is to facilitate diagnosis, predict effective therapy, and avoid adverse reactions specific for each patient. The forefront of PM is in oncology; nonetheless, it is developing in other fields of medicine, including rheumatology. Recent studies on elucidating the genetic architecture of polygenic and monogenic rheumatological diseases have made PM possible by enabling physicians to customize medical treatment through the incorporation of clinical features and genetic data. For complex inflammatory disorders, the prevailing paradigm is that disease susceptibility is due to additive effects of common reduced-penetrance gene variants and environmental factors. Efforts have been made to calculate cumulative genetic risk score (GRS) and to relate specific susceptibility alleles for use of target therapies. The discovery of rare patients with single-gene high-penetrance mutations informed our understanding of pathways driving systemic inflammation. Here, we review the advances in practicing PM in patients with primary systemic vasculitides (PSVs). We summarize recent genetic studies and discuss current knowledge on the contribution of epigenetic factors and extracellular vesicles (EVs) in disease progression and treatment response. Implementation of PM in PSVs is a developing field that will require analysis of a large cohort of patients to validate data from genomics, transcriptomics, metabolomics, proteomics, and epigenomics studies for accurate disease profiling. This multi-omics approach to study disease pathogeneses should ultimately provide a powerful tool for stratification of patients to receive tailored optimal therapies and for monitoring their disease activity.