Markedly elevated CD64 expression on neutrophils and monocytes as a biomarker for diagnosis and therapy assessment in Kawasaki disease

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.

Intravenous Immunoglobulin in Kawasaki Disease-Evolution and Pathogenic Mechanisms

Kawasaki disease (KD) is an acute vasculitis of childhood that affects the medium vessels with a special predilection to the involvement of coronary arteries. The major morbidity of this disease is due to coronary artery aneurysm, which occurs in about 25-30% of untreated cases. For decades now, intravenous immunoglobulin (IVIg) has consistently been shown to reduce the risk of CAAs to less than 5%. However, the mechanism of immunomodulation remains unclear. Several studies on the role of IVIg in the modulation of toll-like receptor pathways, autophagy, and apoptosis of the mononuclear phagocytic system, neutrophil extracellular trap, and dendritic cell modulation suggest a modulatory effect on the innate immune system. Similarly, certain studies have shown its effect on T-cell differentiation, cytokine release, and regulatory T-cell function. In this review, we discuss the potential mechanisms underlying the immunomodulatory actions of IVIg in patients with Kawasaki disease. Furthermore, we provide a summary of the evidence regarding various infusion protocols and dosages utilized in the treatment of KD patients.

Intravenous Immunoglobulin: Mechanism of Action in Autoimmune and Inflammatory Conditions

Intravenous immunoglobulin (IVIG) is the mainstay of therapy for humoral immune deficiencies and numerous inflammatory disorders. Although the use of IVIG may be supplanted by several targeted therapies to cytokines, the ability of polyclonal normal IgG to act as an effector molecule as well as a regulatory molecule is a clear example of the polyfunctionality of IVIG. This article will address the mechanism of action of IVIG in a number of important conditions that are otherwise resistant to treatment. In this commentary, we will highlight mechanistic studies that shed light on the action of IVIG. This will be approached by identifying effects that are both common and disease-specific, targeting actions that have been demonstrated on cells and processes that represent both innate and adaptive immune responses.

Identification and validation of autophagy-related genes in Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is a systemic vasculitis of unknown etiology affecting mainly children. Studies have shown that the pathogenesis of KD may be related to autophagy. Using bioinformatics analysis, we assessed the significance of autophagy-related genes (ARGs) in KD.

METHODS

Common ARGs were identified from the GeneCards Database, the Molecular Signatures Database (MSigDB), and the Gene Expression Omnibus (GEO) database. ARGs were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis and protein-protein interaction (PPI) network analysis. Furthermore, related microRNAs (miRNAs), transcription factors (TFs), and drug interaction network were predicted. The immune cell infiltration of ARGs in tissues was explored. Finally, we used receiver operating characteristic (ROC) curves and quantitative real-time PCR (qRT-PCR) to validate the diagnostic value and expression levels of ARGs in KD.

RESULTS

There were 20 ARGs in total. GO analysis showed that ARGs were mainly rich in autophagy, macro-autophagy, and GTPase activity. KEGG analysis showed that ARGs were mainly rich in autophagy-animal and the collecting duct acid secretion pathway. The expression of WIPI1, WDFY3, ATP6V0E2, RALB, ATP6V1C1, GBA, C9orf72, LRRK2, GNAI3, and PIK3CB is the focus of PPI network. A total of 72 related miRNAs and 130 related TFs were predicted by miRNA and TF targeting network analyses. Ten pairs of gene-drug interaction networks were also predicted; immune infiltration analysis showed that SH3GLB1, ATP6V0E2, PLEKHF1, RALB, KLHL3, and TSPO were closely related to CD8 + T cells and neutrophils. The ROC curve showed that ARGs had good diagnostic value in KD. qRT-PCR showed that WIPI1 and GBA were significantly upregulated.

CONCLUSION

Twenty potential ARGs were identified by bioinformatics analysis, and WIPI1 and GBA may be used as potential drug targets and biomarkers.

Similarities and differences between MIS-C and KD: a systematic review and meta-analysis

BACKGROUND

Multisystem inflammatory syndrome in children (MIS-C) is a new syndrome with some clinical manifestations similar to Kawasaki disease (KD), which is difficult to distinguish.

OBJECTIVE

The study aimed to characterize the demographic characteristics, clinical characteristics, laboratory features, cardiac complications, and treatment of MIS-C compared with KD.

STUDY DESIGN

Studies were selected by searching the PubMed, EMBASE and so on before February 28, 2022. Statistical analyses were performed using Review Manager 5.4 software and STATA 14.0.

RESULTS

Fourteen studies with 2928 participants were included. MIS-C patients tended to be older and there was no significant difference in the sex ratio. In terms of clinical characteristics, MIS-C patients were more frequently represented with respiratory, gastrointestinal symptoms and shock. At the same time, they had a lower incidence of conjunctivitis than KD patients. MIS-C patients had lower lymphocyte counts, platelet (PLT) counts, erythrocyte sedimentation rates (ESRs), alanine transaminase (ALT), and albumin levels and had higher levels of aspartate transaminase (AST), N-terminal pro-B-type natriuretic peptide (NT-pro-BNP), troponin, C-reactive protein (CRP), D-dimer, fibrinogen, ferritin, and creatinine. MIS-C patients had a higher incidence of left ventricle (LV) dysfunction, valvular regurgitation, pericardial effusion, myocarditis, and pericarditis. The incidence of coronary artery lesion (CAL) was lower in MIS-C patients [OR (95% CI): 0.52 (0.29, 0.93), p =0.03], while it was similar in the acute period. MIS-C patients had higher utilization of glucocorticoids (GCs) and lower utilization of intravenous immune globulin (IVIG).

CONCLUSIONS

There were specific differences between MIS-C and KD, which might assist clinicians with the accurate recognition of MIS-C and further mechanistic research.

The neutrophil: A key resourceful agent in immune‐mediated vasculitis

The term "vasculitis" refers to a group of rare immune-mediated diseases characterized by the dysregulated immune system attacking blood vessels located in any organ of the body, including the skin, lungs, and kidneys. Vasculitides are classified according to the size of the vessel that is affected. Although this observation is not specific to small-, medium-, or large-vessel vasculitides, patients show a high circulating neutrophil-to-lymphocyte ratio, suggesting the direct or indirect involvement of neutrophils in these diseases. As first responders to infection or inflammation, neutrophils release cytotoxic mediators, including reactive oxygen species, proteases, and neutrophil extracellular traps. If not controlled, this dangerous arsenal can injure the vascular system, which acts as the main transport route for neutrophils, thereby amplifying the initial inflammatory stimulus and the recruitment of immune cells. This review highlights the ability of neutrophils to "set the tone" for immune cells and other cells in the vessel wall. Considering both their long-established and newly described roles, we extend their functions far beyond their direct host-damaging potential. We also review the roles of neutrophils in various types of primary vasculitis, including immune complex vasculitis, anti-neutrophil cytoplasmic antibody-associated vasculitis, polyarteritis nodosa, Kawasaki disease, giant cell arteritis, Takayasu arteritis, and Behçet's disease.

Learning about Kawasaki disease from COVID-19 and the Multisystem Inflammatory Syndrome in Children

PURPOSE OF REVIEW

Multisystem Inflammatory Syndrome in Children (MIS-C) is a novel syndrome that has appeared in the wake of the severe acute respiratory syndrome coronavirus -2 pandemic, with features that overlap with Kawasaki disease (KD). As a result, new interest and focus have arisen in KD, and specifically mechanisms of the disease.

RECENT FINDINGS

A major question in the literature on the nature of MIS-C is if, and how, it may be related to KD. This has been explored using component analysis type studies, as well as other unsupervised analysis, as well as direct comparisons. At present, the answer to this question remains opaque, and several studies have interpreted their findings in opposing ways. Studies seem to suggest some relationship, but that MIS-C and KD are not the same syndrome.

SUMMARY

Study of MIS-C strengthens the likelihood that KD is a postinfectious immune response, and that perhaps multiple infectious agents or viruses underlie the disease. MIS-C and KD, while not the same disease, could plausibly be sibling disorders that fall under a larger syndrome of postacute autoimmune febrile responses to infection, along with Kawasaki shock syndrome.

The immune landscape of SARS-CoV-2-associated Multisystem Inflammatory Syndrome in Children (MIS-C) from acute disease to recovery

Multisystem inflammatory syndrome in children (MIS-C) is a life-threatening disease occurring several weeks after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Deep immune profiling showed acute MIS-C patients had highly activated neutrophils, classical monocytes and memory CD8+ T-cells, with increased frequencies of B-cell plasmablasts and double-negative B-cells. Post treatment samples from the same patients, taken during symptom resolution, identified recovery-associated immune features including increased monocyte CD163 levels, emergence of a new population of immature neutrophils and, in some patients, transiently increased plasma arginase. Plasma profiling identified multiple features shared by MIS-C, Kawasaki Disease and COVID-19 and that therapeutic inhibition of IL-6 may be preferable to IL-1 or TNF-α. We identified several potential mechanisms of action for IVIG, the most commonly used drug to treat MIS-C. Finally, we showed systemic complement activation with high plasma C5b-9 levels is common in MIS-C suggesting complement inhibitors could be used to treat the disease.

Upregulation of type 1 conventional dendritic cells implicates antigen cross-presentation in multisystem inflammatory syndrome

Background

Multisystem inflammatory syndrome in children (MIS-C) is an acute, febrile, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-associated syndrome, often with cardiohemodynamic dysfunction. Insight into mechanism of disease is still incomplete.

Objective

Our objective was to analyze immunologic features of MIS-C patients compared to febrile controls (FC).

Methods

MIS-C patients were defined by narrow criteria, including having evidence of cardiohemodynamic involvement and no macrophage activation syndrome. Samples were collected from 8 completely treatment-naive patients with MIS-C (SARS-CoV-2 serology positive), 3 patients with unclassified MIS-C–like disease (serology negative), 14 FC, and 5 MIS-C recovery (RCV). Three healthy controls (HCs) were used for comparisons of normal range. Using spectral flow cytometry, we assessed 36 parameters in antigen-presenting cells (APCs) and 29 in T cells. We used biaxial analysis and uniform manifold approximation and projection (UMAP).

Results

Significant elevations in cytokines including CXCL9, M-CSF, and IL-27 were found in MIS-C compared to FC. Classic monocytes and type 2 dendritic cells (DCs) were downregulated (decreased CD86, HLA-DR) versus HCs; however, type 1 DCs (CD11c⁺CD141⁺CLEC9A⁺) were highly activated in MIS-C patients versus FC, expressing higher levels of CD86, CD275, and atypical conventional DC markers such as CD64, CD115, and CX3CR1. CD169 and CD38 were upregulated in multiple monocyte subtypes. CD56^dim/CD57⁻/KLRG^hi/CD161⁺/CD38⁻ natural killer (NK) cells were a unique subset in MIS-C versus FC without macrophage activation syndrome.

Conclusion

Orchestrated by complex cytokine signaling, type 1 DC activation and NK dysregulation are key features in the pathophysiology of MIS-C. NK cell findings may suggest a relationship with macrophage activation syndrome, while type 1 DC upregulation implies a role for antigen cross-presentation.

Cardiac pathology and outcomes vary between Kawasaki disease and PIMS-TS

Overlapping clinical features promoted the discussion of whether Kawasaki disease (KD) and PIMS-TS share pathophysiological features and disease outcomes. Medical records from English patients with KD (2015-02/20, N = 27) and PIMS-TS (02/2020-21, N = 34) were accessed to extract information. Children with PIMS-TS were older and more frequently of minority ethnicity background. They patients more commonly exhibited cytopenias and hyperferritinemia, which associated with diffuse cardiac involvement and functional impairment. In some PIMS-TS cases, cardiac pathology developed late, but outcomes were more favorable. In both, KD and PIMS-TS, baseline coronary diameter was a predictor of outcomes. PIMS-TS treatment more frequently included respiratory and cardiovascular support, and corticosteroids with IVIG. Cardiac involvement in PIMS-TS may be the result of a cytokine storm. Though more severe and diffuse when compared to KD, cardiac involvement of PIMS-TS has a more favorable prognosis, which may, after recovery, mitigate the need for long-term follow up.

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.

Persistent Activation of Innate Immunity in Patients with Primary Antibody Deficiencies

Primary antibody deficiencies (PAD) represent a heterogeneous group of disorders, with common variable immunodeficiency being the most common with clinical significance. The main phenotypic defect resides in the inability of B cells to produce antibodies, and the cornerstone of therapy is immunoglobulin replacement treatment in order to fight infections. However, the management of the other inflammatory manifestations is inadequate, reinforcing the hypothesis that a complex genetic background affecting additional cell populations, such as polymorphonuclear cells (PMN) and monocytes, influences the expression of the clinical phenotype of the disease. In this study, we investigated by flow cytometry in different conditions (resting state, and after isolation and incubation, with and without stimuli) the expression pattern of several markers on PMN and monocytes, indicative of their maturation, capacity for chemotaxis, adhesion, opsonization, migration, and phagocytosis in 25 PAD patients, 12 healthy blood donors, and 4 septic patients. In this context, we also analyzed patients before and after the initiation of replacement treatment, as well as an untreated patient in different clinical conditions. Interestingly, we observed that PAD patients exhibit a chronic activation status of the innate immunity compartment, along with several differences in the expression of activation, maturation, and adhesion markers, with respect to different clinical conditions. Moreover, immunoglobulin replacement treatment had a favorable effect on PMN, as it was expressed by a more mature and less activated phenotype on basal state cells, and an enhanced activation capacity after LPS exposure. Thus, we conclude that PAD patients display a persistent innate immune cell activation, which is probably associated with the chronic inflammatory stress, usually observed in these disorders.

Mapping Systemic Inflammation and Antibody Responses in Multisystem Inflammatory Syndrome in Children (MIS-C)

Initially, children were thought to be spared from disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, a month into the epidemic, a novel multisystem inflammatory syndrome in children (MIS-C) emerged. Herein, we report on the immune profiles of nine MIS-C cases. All MIS-C patients had evidence of prior SARS-CoV-2 exposure, mounting an antibody response with intact neutralization capability. Cytokine profiling identified elevated signatures of inflammation (IL-18 and IL-6), lymphocytic and myeloid chemotaxis and activation (CCL3, CCL4, and CDCP1), and mucosal immune dysregulation (IL-17A, CCL20, and CCL28). Immunophenotyping of peripheral blood revealed reductions of non-classical monocytes, and subsets of NK and T lymphocytes, suggesting extravasation to affected tissues. Finally, profiling the autoantigen reactivity of MIS-C plasma revealed both known disease-associated autoantibodies (anti-La) and novel candidates that recognize endothelial, gastrointestinal, and immune-cell antigens. All patients were treated with anti-IL-6R antibody and/or IVIG, which led to rapid disease resolution.

Mapping Systemic Inflammation and Antibody Responses in Multisystem Inflammatory Syndrome in Children (MIS-C)

Initially, the global outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spared children from severe disease. However, after the initial wave of infections, clusters of a novel hyperinflammatory disease have been reported in regions with ongoing SARS-CoV-2 epidemics. While the characteristic clinical features are becoming clear, the pathophysiology remains unknown. Herein, we report on the immune profiles of eight Multisystem Inflammatory Syndrome in Children (MIS-C) cases. We document that all MIS-C patients had evidence of prior SARS-CoV-2 exposure, mounting an antibody response with normal isotype-switching and neutralization capability. We further profiled the secreted immune response by high-dimensional cytokine assays, which identified elevated signatures of inflammation (IL-18 and IL-6), lymphocytic and myeloid chemotaxis and activation (CCL3, CCL4, and CDCP1) and mucosal immune dysregulation (IL-17A, CCL20, CCL28). Mass cytometry immunophenotyping of peripheral blood revealed reductions of mDC1 and non-classical monocytes, as well as both NK- and T- lymphocytes, suggesting extravasation to affected tissues. Markers of activated myeloid function were also evident, including upregulation of ICAM1 and FcγR1 in neutrophil and non-classical monocytes, well-documented markers in autoinflammation and autoimmunity that indicate enhanced antigen presentation and Fc-mediated responses. Finally, to assess the role for autoimmunity secondary to infection, we profiled the auto-antigen reactivity of MIS-C plasma, which revealed both known disease-associated autoantibodies (anti-La) and novel candidates that recognize endothelial, gastrointestinal and immune-cell antigens. All patients were treated with anti-IL6R antibody or IVIG, which led to rapid disease resolution tracking with normalization of inflammatory markers.

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.

Probe Signal Values in mRNA Arrays Imply an Excessive Involvement of Neutrophil FCGR1 in Tuberculosis

The perturbed genes from transcriptomes are often presented in terms of relative expressions against control samples. However, the probe signal values (PSVs) of genes, implying protein abundances, are often ignored. Here, we explored the PSVs in tuberculosis (TB)-relevant signature genes. The signatures from Mycobacterium tuberculosis-infected THP-1 cells were defined as induced (TMtb-i, with a derived TMtb-iNet) and repressed (TMtb-r). The signature from human blood was defined as a pulmonary TB (PTB)-specific signature (PTBsig). The analysis showed that before infection, TMtb-i and TMtb-iNet had lower PSVs and TMtb-r genes had average PSVs. In the blood of healthy donors, PTBsig (divided into up-regulated PTBsigUp and down-regulated PTBsigDn) displayed average PSVs. This was partly due to masking by the cellular heterogeneity of blood; diverse PSVs were seen in constituent cell populations (CD4/8+ T, monocytes and neutrophils). Specifically, the PSVs of PTBsigUp in the neutrophils of healthy donors were higher (implying higher protein abundances), and much higher in the neutrophils of PTB (implying excessive protein abundances). Based on the PSV patterns of PTBsigUp in four cell populations, we identified three representative highly homologous genes (FCGR1A, FCGR1B, and the pseudogene FCGR1CP, which were often poorly distinguished), of which the summed PSVs were the highest in the neutrophils of PTB patients and healthy donors. The three genes were all up-regulated and responsive to chemotherapy in the blood of PTB, as validated in an RNA-seq-based analysis. This PSV-based study confirms the excessive involvement of neutrophil FCGR1 in PTB.

Clinical features and new diagnostic criteria for the syndrome of periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis

AIM

The syndrome of periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) is a common inflammatory disease that presents with periodic fever. We aimed to establish more specific diagnostic criteria for PFAPA based on the clinical characteristics of PFAPA patients in our directory.

METHOD

The clinical, laboratory, genetic, and family history details of 257 Japanese PFAPA patients treated at our and other affiliated hospitals between April 2000 and April 2018 were analyzed along with quantitative measurements of the number of CD64 molecules on neutrophils, and the levels of serum inflammatory cytokines. The sensitivity and specificity of the criteria were calculated for several diseases.

RESULTS

Because recurrent fevers were crucial findings, they were defined as the required criterion. Tonsillitis/pharyngitis with white moss were important accompanying signs. Other symptoms associated with febrile episodes were cervical lymphadenitis with tenderness, aphthous stomatitis, sore throat, vomiting, and headache but not cough. A total of 159 (62%) patients had a family history of recurrent fevers, indicating autosomal dominant inheritance. C-reactive protein levels were extremely elevated during febrile attacks but normal in attack-free periods. Serum immunoglobulin D levels were high in 72 of the 199 tested patients. Oral glucocorticoid and cimetidine were extremely effective in all and 51.6% of the patients, respectively. We defined the above as supportive criteria. These criteria were sensitive and specific enough to distinguish PFAPA from other recurrent fever diseases. Raised serum interferon-γ levels and remarkable CD64 expression on neutrophils during flare-ups were recognized, indicating they contributed to diagnosis.

CONCLUSION

Our new criteria are useful for diagnosing PFAPA.

Biomarkers in vasculitis

PURPOSE OF REVIEW

Biomarkers are considered to be helpful in diagnosing, monitoring, predicting treatment response, and prognosis in clinical practice and as outcomes in clinical trials. In this article, we review the recent literature on new biomarkers and the expanding use of older ones in vasculitic conditions.

RECENT FINDINGS

In antineutrophil cytoplasmic antibody-associated vasculitis patients antineutrophil cytoplasmic antibody type may be useful as a predictor of relapse and response to rituximab. Moreover, serial measurements of proteinase-3 titer may help to predict relapse. Urinary soluble CD163 levels are promising for identifying active renal vasculitis. Imaging modalities such as positron emission tomography, computerized angiography tomography, and temporal artery ultrasound maintain their role in diagnosis and disease assessment in large vessel vasculitis. Fecal calprotectin is a useful marker of active gastrointestinal involvement in Behçet's syndrome.

SUMMARY

The publications reviewed here potentially may help to move the field of biomarkers in vasculitis management. However, more work toward understanding the underlying pathophysiology and effects of an intervention on the disease process are needed before true biomarkers can be realized. Further studies with appropriate control groups, using good definitions for disease states such as activity and remission are needed to guide our use of these markers correctly in the management of our patients.