The tumour-derived extracellular vesicle proteome varies by endometrial cancer histology and is confounded by an obesogenic environment.

Endometrial cancer, the most common gynaecological cancer worldwide, is closely linked to obesity and metabolic diseases, particularly in younger women. New circulating biomarkers have the potential to improve diagnosis and treatment selections, which could significantly improve outcomes. Our approach focuses on extracellular vesicle (EV) biomarker discovery by directly profiling the proteome of EVs enriched from frozen biobanked endometrial tumours. We analysed nine tissue samples to compare three clinical subgroups-low BMI (Body Mass Index) Endometrioid, high BMI Endometrioid, and Serous (any BMI)-identifying proteins related to histological subtype, BMI, and shared secreted proteins. Using collagenase digestion and size exclusion chromatography, we successfully enriched generous quantities of EVs (range 204.8-1291.0 µg protein: 1.38 × 1011-1.10 × 1012 particles), characterised by their size (∼150 nm), expression of EV markers (CD63/81), and proposed endometrial cancer markers (L1CAM, ANXA2). Mass spectrometry-based proteomic profiling identified 2075 proteins present in at least one of the 18 samples. Compared to cell lysates, EVs were successfully depleted for mitochondrial and blood proteins and enriched for common EV markers and large secreted proteins. Further analysis highlighted significant differences in EV protein profiles between the high BMI subgroup and others, underlining the impact of comorbidities on the EV secretome. Interestingly, proteins differentially abundant in tissue subgroups were largely not also differential in matched EVs. This research identified secreted proteins known to be involved in endometrial cancer pathophysiology and proposed novel diagnostic biomarkers (EIF6, MUC16, PROM1, SLC26A2).

Messenger RNA-encoded antibody approach for targeting extracellular and intracellular tau.

Monoclonal antibodies have emerged as a leading therapeutic agent for the treatment of disease, including Alzheimer's disease. In the last year, two anti-amyloid monoclonal antibodies, lecanemab and aducanumab, have been approved in the USA for the treatment of Alzheimer's disease, whilst several tau-targeting monoclonal antibodies are currently in clinical trials. Such antibodies, however, are expensive and timely to produce and require frequent dosing regimens to ensure disease-modifying effects. Synthetic in vitro-transcribed messenger RNA encoding antibodies for endogenous protein expression holds the potential to overcome many of the limitations associated with protein antibody production. Here, we have generated synthetic in vitro-transcribed messenger RNA encoding a tau-specific antibody as a full-sized immunoglobulin and as a single-chain variable fragment. In vitro transfection of human neuroblastoma SH-SY5Y cells demonstrated the ability of the synthetic messenger RNA to be translated into a functional tau-specific antibody. Furthermore, we show that the translation of the tau-specific single-chain variable fragment as an intrabody results in the specific engagement of intracellular tau. This work highlights the utility of messenger RNA for the delivery of antibody therapeutics, including intrabodies, for the targeting of tau in Alzheimer's disease and other tauopathies.

Do Bacterial Outer Membrane Vesicles Contribute to Chronic Inflammation in Parkinson's Disease?

Parkinson's disease (PD) is an increasingly common neurodegenerative disease. It has been suggested that the etiology of idiopathic PD is complex and multifactorial involving environmental contributions, such as viral or bacterial infections and microbial dysbiosis, in genetically predisposed individuals. With advances in our understanding of the gut-brain axis, there is increasing evidence that the intestinal microbiota and the mammalian immune system functionally interact. Recent findings suggest that a shift in the gut microbiome to a pro-inflammatory phenotype may play a role in PD onset and progression. While there are links between gut bacteria, inflammation, and PD, the bacterial products involved and how they traverse the gut lumen and distribute systemically to trigger inflammation are ill-defined. Mechanisms emerging in other research fields point to a role for small, inherently stable vesicles released by Gram-negative bacteria, called outer membrane vesicles in disease pathogenesis. These vesicles facilitate communication between bacteria and the host and can shuttle bacterial toxins and virulence factors around the body to elicit an immune response in local and distant organs. In this perspective article, we hypothesize a role for bacterial outer membrane vesicles in PD pathogenesis. We present evidence suggesting that these outer membrane vesicles specifically from Gram-negative bacteria could potentially contribute to PD by traversing the gut lumen to trigger local, systemic, and neuroinflammation. This perspective aims to facilitate a discussion on outer membrane vesicles in PD and encourage research in the area, with the goal of developing strategies for the prevention and treatment of the disease.

Immunologic predictors of vaccine responsiveness in patients with lymphoma and CLL.

Patients with B-cell lymphomas have altered cellular components of vaccine responses due to malignancy and therapy, and the optimal timing of vaccination relative to therapy remains unknown. SARS-CoV-2 vaccines created an opportunity for new insights in vaccine timing because patients were challenged with a novel antigen across multiple phases of treatment. We studied serologic mRNA vaccine response in retrospective and prospective cohorts with lymphoma and CLL, paired with clinical and research immune parameters. Reduced serologic response was observed more frequently during active therapies, but non-response was also common within observation and post-treatment groups. Total IgA and IgM correlated with successful vaccine response. In individuals treated with CART-19, non-response was associated with reduced B and T follicular helper cells. Predictors of vaccine response varied by disease and therapeutic group, and therefore further studies of immune health during and after cancer therapies are needed to allow individualized vaccine timing.

Metabolomic and Immunologic Discriminators of MIS-C at Emergency Room Presentation.

Multisystem Inflammatory Syndrome in Childhood (MIS-C) follows SARS-CoV-2 infection and frequently leads to intensive care unit admission. The inability to rapidly discriminate MIS-C from similar febrile illnesses delays treatment and leads to misdiagnosis. To identify diagnostic discriminators at the time of emergency department presentation, we enrolled 104 children who met MIS-C screening criteria, 14 of whom were eventually diagnosed with MIS-C. Before treatment, we collected breath samples for volatiles and peripheral blood for measurement of plasma proteins and immune cell features. Clinical and laboratory features were used as inputs for a machine learning model to determine diagnostic importance. MIS-C was associated with significant changes in breath volatile organic compound (VOC) composition as well as increased plasma levels of secretory phospholipase A2 (PLA2G2A) and lipopolysaccharide binding protein (LBP). In an integrated model of all analytes, the proportion of TCRVß21.3+ non-naive CD4 T cells expressing Ki-67 had a high sensitivity and specificity for MIS-C, with diagnostic accuracy further enhanced by low sodium and high PLA2G2A. We anticipate that accurate diagnosis will become increasingly difficult as MIS-C becomes less common. Clinical validation and application of this diagnostic model may improve outcomes in children presenting with multisystem febrile illnesses.

Recommendations for reproducibility of cerebrospinal fluid extracellular vesicle studies.

Cerebrospinal fluid (CSF) is a clear, transparent fluid derived from blood plasma that protects the brain and spinal cord against mechanical shock, provides buoyancy, clears metabolic waste and transports extracellular components to remote sites in the brain. Given its contact with the brain and the spinal cord, CSF is the most informative biofluid for studies of the central nervous system (CNS). In addition to other components, CSF contains extracellular vesicles (EVs) that carry bioactive cargoes (e.g., lipids, nucleic acids, proteins), and that can have biological functions within and beyond the CNS. Thus, CSF EVs likely serve as both mediators of and contributors to communication in the CNS. Accordingly, their potential as biomarkers for CNS diseases has stimulated much excitement for and attention to CSF EV research. However, studies on CSF EVs present unique challenges relative to EV studies in other biofluids, including the invasive nature of CSF collection, limited CSF volumes and the low numbers of EVs in CSF as compared to plasma. Here, the objectives of the International Society for Extracellular Vesicles CSF Task Force are to promote the reproducibility of CSF EV studies by providing current reporting and best practices, and recommendations and reporting guidelines, for CSF EV studies. To accomplish this, we created and distributed a world-wide survey to ISEV members to assess methods considered 'best practices' for CSF EVs, then performed a detailed literature review for CSF EV publications that was used to curate methods and resources. Based on responses to the survey and curated information from publications, the CSF Task Force herein provides recommendations and reporting guidelines to promote the reproducibility of CSF EV studies in seven domains: (i) CSF Collection, Processing, and Storage; (ii) CSF EV Separation/Concentration; (iii) CSF EV Size and Number Measurements; (iv) CSF EV Protein Studies; (v) CSF EV RNA Studies; (vi) CSF EV Omics Studies and (vii) CSF EV Functional Studies.

Trimodal single-cell profiling reveals a novel pediatric CD8αα+ T cell subset and broad age-related molecular reprogramming across the T cell compartment.

Age-associated changes in the T cell compartment are well described. However, limitations of current single-modal or bimodal single-cell assays, including flow cytometry, RNA-seq (RNA sequencing) and CITE-seq (cellular indexing of transcriptomes and epitopes by sequencing), have restricted our ability to deconvolve more complex cellular and molecular changes. Here, we profile >300,000 single T cells from healthy children (aged 11-13 years) and older adults (aged 55-65 years) by using the trimodal assay TEA-seq (single-cell analysis of mRNA transcripts, surface protein epitopes and chromatin accessibility), which revealed that molecular programming of T cell subsets shifts toward a more activated basal state with age. Naive CD4+ T cells, considered relatively resistant to aging, exhibited pronounced transcriptional and epigenetic reprogramming. Moreover, we discovered a novel CD8αα+ T cell subset lost with age that is epigenetically poised for rapid effector responses and has distinct inhibitory, costimulatory and tissue-homing properties. Together, these data reveal new insights into age-associated changes in the T cell compartment that may contribute to differential immune responses.

Exploring the significance of lipids in Alzheimer's disease and the potential of extracellular vesicles.

Lipids play a significant role in maintaining central nervous system (CNS) structure and function, and the dysregulation of lipid metabolism is known to occur in many neurological disorders, including Alzheimer's disease. Here we review what is currently known about lipid dyshomeostasis in Alzheimer's disease. We propose that small extracellular vesicle (sEV) lipids may provide insight into the pathophysiology and progression of Alzheimer's disease. This stems from the recognition that sEV likely contributes to disease pathogenesis, but also an understanding that sEV can serve as a source of potential biomarkers. While the protein and RNA content of sEV in the CNS diseases have been studied extensively, our understanding of the lipidome of sEV in the CNS is still in its infancy.

The Proteome and Lipidome of Extracellular Vesicles from Haemonchus contortus to Underpin Explorations of Host-Parasite Cross-Talk.

Many parasitic worms have a major adverse impact on human and animal populations worldwide due to the chronicity of their infections. There is a growing body of evidence indicating that extracellular vesicles (EVs) are intimately involved in modulating (suppressing) inflammatory/immune host responses and parasitism. As one of the most pathogenic nematodes of livestock animals, Haemonchus contortus is an ideal model system for EV exploration. Here, employing a multi-step enrichment process (in vitro culture, followed by ultracentrifugation, size exclusion and filtration), we enriched EVs from H. contortus and undertook the first comprehensive (qualitative and quantitative) multi-omic investigation of EV proteins and lipids using advanced liquid chromatography-mass spectrometry and informatics methods. We identified and quantified 561 proteins and 446 lipids in EVs and compared these molecules with those of adult worms. We identified unique molecules in EVs, such as proteins linked to lipid transportation and lipid species (i.e., sphingolipids) associated with signalling, indicating the involvement of these molecules in parasite-host cross-talk. This work provides a solid starting point to explore the functional roles of EV-specific proteins and lipids in modulating parasite-host cross-talk, and the prospect of finding ways of disrupting or interrupting this relationship to suppress or eliminate parasite infection.

IgA deficiency destabilizes homeostasis toward intestinal microbes and increases systemic immune dysregulation.

The ability of most patients with selective immunoglobulin A (IgA) deficiency (SIgAD) to remain apparently healthy has been a persistent clinical conundrum. Compensatory mechanisms, including IgM, have been proposed, yet it remains unclear how secretory IgA and IgM work together in the mucosal system and, on a larger scale, whether the systemic and mucosal anti-commensal responses are redundant or have unique features. To address this gap in knowledge, we developed an integrated host-commensal approach combining microbial flow cytometry and metagenomic sequencing (mFLOW-Seq) to comprehensively define which microbes induce mucosal and systemic antibodies. We coupled this approach with high-dimensional immune profiling to study a cohort of pediatric patients with SIgAD and household control siblings. We found that mucosal and systemic antibody networks cooperate to maintain homeostasis by targeting a common subset of commensal microbes. In IgA-deficiency, we find increased translocation of specific bacterial taxa associated with elevated levels of systemic IgG targeting fecal microbiota. Associated features of immune system dysregulation in IgA-deficient mice and humans included elevated levels of inflammatory cytokines, enhanced follicular CD4 T helper cell frequency and activation, and an altered CD8 T cell activation state. Although SIgAD is clinically defined by the absence of serum IgA, the symptomatology and immune dysregulation were concentrated in the SIgAD participants who were also fecal IgA deficient. These findings reveal that mucosal IgA deficiency leads to aberrant systemic exposures and immune responses to commensal microbes, which increase the likelihood of humoral and cellular immune dysregulation and symptomatic disease in patients with IgA deficiency.

Small extracellular vesicles promote invadopodia activity in glioblastoma cells in a therapy-dependent manner.

PURPOSE: The therapeutic efficacy of radiotherapy/temozolomide treatment for glioblastoma (GBM) is limited by the augmented invasiveness mediated by invadopodia activity of surviving GBM cells. As yet, however the underlying mechanisms remain poorly understood. Due to their ability to transport oncogenic material between cells, small extracellular vesicles (sEVs) have emerged as key mediators of tumour progression. We hypothesize that the sustained growth and invasion of cancer cells depends on bidirectional sEV-mediated cell-cell communication. METHODS: Invadopodia assays and zymography gels were used to examine the invadopodia activity capacity of GBM cells. Differential ultracentrifugation was utilized to isolate sEVs from conditioned medium and proteomic analyses were conducted on both GBM cell lines and their sEVs to determine the cargo present within the sEVs. In addition, the impact of radiotherapy and temozolomide treatment of GBM cells was studied. RESULTS: We found that GBM cells form active invadopodia and secrete sEVs containing the matrix metalloproteinase MMP-2. Subsequent proteomic studies revealed the presence of an invadopodia-related protein sEV cargo and that sEVs from highly invadopodia active GBM cells (LN229) increase invadopodia activity in sEV recipient GBM cells. We also found that GBM cells displayed increases in invadopodia activity and sEV secretion post radiation/temozolomide treatment. Together, these data reveal a relationship between invadopodia and sEV composition/secretion/uptake in promoting the invasiveness of GBM cells. CONCLUSIONS: Our data indicate that sEVs secreted by GBM cells can facilitate tumour invasion by promoting invadopodia activity in recipient cells, which may be enhanced by treatment with radio-chemotherapy. The transfer of pro-invasive cargos may yield important insights into the functional capacity of sEVs in invadopodia.

Profound phenotypic and epigenetic heterogeneity of the HIV-1-infected CD4+ T cell reservoir.

Understanding the complexity of the long-lived HIV reservoir during antiretroviral therapy (ART) remains a considerable impediment in research towards a cure for HIV. To address this, we developed a single-cell strategy to precisely define the unperturbed peripheral blood HIV-infected memory CD4+ T cell reservoir from ART-treated people living with HIV (ART-PLWH) via the presence of integrated accessible proviral DNA in concert with epigenetic and cell surface protein profiling. We identified profound reservoir heterogeneity within and between ART-PLWH, characterized by new and known surface markers within total and individual memory CD4+ T cell subsets. We further uncovered new epigenetic profiles and transcription factor motifs enriched in HIV-infected cells that suggest infected cells with accessible provirus, irrespective of reservoir distribution, are poised for reactivation during ART treatment. Together, our findings reveal the extensive inter- and intrapersonal cellular heterogeneity of the HIV reservoir, and establish an initial multiomic atlas to develop targeted reservoir elimination strategies.

ATH434 Rescues Pre-motor Hyposmia in a Mouse Model of Parkinsonism.

Hyposmia is a prevalent prodromal feature of Parkinson's disease (PD), though the neuropathology that underlies this symptom is poorly understood. Unlike the substantia nigra, the status of metal homeostasis in the olfactory bulbs has not been characterized in PD. Given the increasing interest in metal modulation as a therapeutic avenue in PD, we sought to investigate bulbar metals and the effect of AT434 (formerly PBT434) an orally bioavailable, small molecule modulator of metal homeostasis on hyposmia in a mouse model of parkinsonism (the tau knockout (tau-/-) mouse). 5.5 (pre-hyposmia) and 13.5-month-old (pre-motor) mice were dosed with ATH434 (30 mg/kg/day, oral gavage) for 6 weeks. Animals then underwent behavioral analysis for olfactory and motor phenotypes. The olfactory bulbs and the substantia nigra were then collected and analyzed for metal content, synaptic markers, and dopaminergic cell number. ATH434 was able to prevent the development of hyposmia in young tau-/- mice, which coincided with a reduction in bulbar iron and copper levels, an increase in synaptophysin, and a reduction in soluble α-synuclein. ATH434 was able to prevent the development of motor impairment in aged tau-/- mice, which coincided with a reduction in iron levels and reduced neurodegeneration in the substantia nigra. These data implicate metal dyshomeostasis in parkinsonian olfactory deficits, and champion a potential clinical benefit of ATH434 in both prodromal and clinical stages of PD.

PD-1 directed immunotherapy alters Tfh and humoral immune responses to seasonal influenza vaccine.

Anti-programmed death-1 (anti-PD-1) immunotherapy reinvigorates CD8 T cell responses in patients with cancer but PD-1 is also expressed by other immune cells, including follicular helper CD4 T cells (Tfh) which are involved in germinal centre responses. Little is known, however, about the effects of anti-PD-1 immunotherapy on noncancer immune responses in humans. To investigate this question, we examined the impact of anti-PD-1 immunotherapy on the Tfh-B cell axis responding to unrelated viral antigens. Following influenza vaccination, a subset of adults receiving anti-PD-1 had more robust circulating Tfh responses than adults not receiving immunotherapy. PD-1 pathway blockade resulted in transcriptional signatures of increased cellular proliferation in circulating Tfh and responding B cells compared with controls. These latter observations suggest an underlying change in the Tfh-B cell and germinal centre axis in a subset of immunotherapy patients. Together, these results demonstrate dynamic effects of anti-PD-1 therapy on influenza vaccine responses and highlight analytical vaccination as an approach that may reveal underlying immune predisposition to adverse events.

Signaling Through FcγRIIA and the C5a-C5aR Pathway Mediate Platelet Hyperactivation in COVID-19.

Patients with COVID-19 present with a wide variety of clinical manifestations. Thromboembolic events constitute a significant cause of morbidity and mortality in patients infected with SARS-CoV-2. Severe COVID-19 has been associated with hyperinflammation and pre-existing cardiovascular disease. Platelets are important mediators and sensors of inflammation and are directly affected by cardiovascular stressors. In this report, we found that platelets from severely ill, hospitalized COVID-19 patients exhibited higher basal levels of activation measured by P-selectin surface expression and had poor functional reserve upon in vitro stimulation. To investigate this question in more detail, we developed an assay to assess the capacity of plasma from COVID-19 patients to activate platelets from healthy donors. Platelet activation was a common feature of plasma from COVID-19 patients and correlated with key measures of clinical outcome including kidney and liver injury, and APACHEIII scores. Further, we identified ferritin as a pivotal clinical marker associated with platelet hyperactivation. The COVID-19 plasma-mediated effect on control platelets was highest for patients that subsequently developed inpatient thrombotic events. Proteomic analysis of plasma from COVID-19 patients identified key mediators of inflammation and cardiovascular disease that positively correlated with in vitro platelet activation. Mechanistically, blocking the signaling of the FcγRIIa-Syk and C5a-C5aR pathways on platelets, using antibody-mediated neutralization, IgG depletion or the Syk inhibitor fostamatinib, reversed this hyperactivity driven by COVID-19 plasma and prevented platelet aggregation in endothelial microfluidic chamber conditions. These data identified these potentially actionable pathways as central for platelet activation and/or vascular complications and clinical outcomes in COVID-19 patients. In conclusion, we reveal a key role of platelet-mediated immunothrombosis in COVID-19 and identify distinct, clinically relevant, targetable signaling pathways that mediate this effect.

CMV infection and management among pediatric solid organ transplant recipients.

BACKGROUND: Cytomegalovirus (CMV) is an important cause of morbidity and mortality in pediatric solid organ transplant (SOT) recipients. However, the impact of asymptomatic CMV infections (ie, DNAemia) on clinical outcomes is not well established. METHODS: We performed a retrospective cohort study of children undergoing first SOT at our institution from January 2012 to June 2018. We evaluated the epidemiology of CMV infections and performed multivariable Cox regression to assess the association between CMV DNAemia without disease or CMV disease (syndrome or end-organ disease) on negative outcomes (death, re-transplantation, or moderate/severe rejection) within the first year after SOT. RESULTS: Among 271 individuals, 43 (15.9%) developed ≥1 CMV infection during the first year after SOT. There were 56 unique CMV infections including 14 episodes of CMV disease. In 167 patients offered CMV prophylaxis, only 8 (4.8%) developed their first CMV DNAemia episode while on prophylaxis 32 developed CMV DNAemia after prophylaxis completion; only 1 episode of CMV disease occurred while on antiviral prophylaxis. When accounting for receipt of ATG, oral steroids, and number of immunosuppressives on a given day, CMV disease was more strongly associated with negative outcomes (Hazard Ratio (HR): 3.28, 95% CI: 0.73-14.64; p = .12) than CMV DNAemia without disease (HR 1.42, 95% CI: 0.19- 10.79; p = .74), although not to a statistically significant degree. CONCLUSIONS: Most CMV infections occurred after completion of antiviral prophylaxis. CMV disease was more strongly associated with negative outcomes than asymptomatic CMV DNAemia and should be the focus of CMV prevention practices.

Current and Emerging Strategies for Enhancing Antibody Delivery to the Brain.

For the treatment of neurological diseases, achieving sufficient exposure to the brain parenchyma is a critical determinant of drug efficacy. The blood-brain barrier (BBB) functions to tightly control the passage of substances between the bloodstream and the central nervous system, and as such poses a major obstacle that must be overcome for therapeutics to enter the brain. Monoclonal antibodies have emerged as one of the best-selling treatment modalities available in the pharmaceutical market owing to their high target specificity. However, it has been estimated that only 0.1% of peripherally administered antibodies can cross the BBB, contributing to the low success rate of immunotherapy seen in clinical trials for the treatment of neurological diseases. The development of new strategies for antibody delivery across the BBB is thereby crucial to improve immunotherapeutic efficacy. Here, we discuss the current strategies that have been employed to enhance antibody delivery across the BBB. These include (i) focused ultrasound in combination with microbubbles, (ii) engineered bi-specific antibodies, and (iii) nanoparticles. Furthermore, we discuss emerging strategies such as extracellular vesicles with BBB-crossing properties and vectored antibody genes capable of being encapsulated within a BBB delivery vehicle.

Proteomic profiling of MIS-C patients indicates heterogeneity relating to interferon gamma dysregulation and vascular endothelial dysfunction.

Multi-system Inflammatory Syndrome in Children (MIS-C) is a major complication of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection in pediatric patients. Weeks after an often mild or asymptomatic initial infection with SARS-CoV-2 children may present with a severe shock-like picture and marked inflammation. Children with MIS-C present with varying degrees of cardiovascular and hyperinflammatory symptoms. Here we perform a comprehensive analysis of the plasma proteome of more than 1400 proteins in children with SARS-CoV-2. We hypothesize that the proteome would reflect heterogeneity in hyperinflammation and vascular injury, and further identify pathogenic mediators of disease. We show that protein signatures demonstrate overlap between MIS-C, and the inflammatory syndromes macrophage activation syndrome (MAS) and thrombotic microangiopathy (TMA). We demonstrate that PLA2G2A is an important marker of MIS-C that associates with TMA. We find that IFNγ responses are dysregulated in MIS-C patients, and that IFNγ levels delineate clinical heterogeneity.

Current Insights Into the Pathophysiology of Multisystem Inflammatory Syndrome in Children.

Purpose of Review: We highlight the new clinical entity multisystem inflammatory syndrome in children (MIS-C), the progress in understanding its immunopathogenesis, and compare and contrast the clinical and immunologic features of MIS-C with Kawasaki disease (KD). Recent Findings: Studies show immune dysregulation in MIS-C including T lymphocyte depletion and activation, T cell receptor Vbeta skewing, elevated plasmablast frequencies, increased markers of vascular pathology, and decreased numbers and functional profiles of antigen-presenting cells. Summary: MIS-C is a late manifestation of infection with SARS-CoV-2 associated with marked immune activation and many potential mechanisms of immunopathogenesis. MIS-C and KD have clinical similarities but are distinct. Myocardial dysfunction with or without mild coronary artery dilation can occur in MIS-C but generally corrects within weeks. In contrast, the coronary arteries are the primary target in KD, and coronary artery sequelae can be lifelong. Supportive care and anti-inflammatory therapy appear to hasten improvement in children with MIS-C, and there is hope that vaccines will prevent its development.