Pathologic Analysis of Twenty-one Appendices From Children With Multisystem Inflammatory Syndrome Compared to Specimens of Acute Appendicitis: A Cross-sectional Study.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) is a rare, severe complication of coronavirus disease 2019, commonly involving the gastrointestinal tract. Some children with MIS-C undergo appendectomy before the final diagnosis. There are several hypotheses explaining the pathomechanism of MIS-C, including the central role of the viral antigen persistence in the gut, associated with lymphocyte exhaustion. We aimed to examine appendectomy specimens from MIS-C patients and assess their pathologic features, as well as the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens. METHODS: In this cross-sectional study we included 21 children with MIS-C who underwent appendectomy. The control group included 21 sex- and age-matched children with acute appendicitis (AA) unrelated to SARS-CoV-2 infection. Histologic evaluation of appendiceal specimens included hematoxylin and eosin staining and immunohistochemical identification of lymphocyte subpopulations, programmed cell death protein-1 (PD-1) and SARS-CoV-2 nucleocapsid antigen. RESULTS: Appendices of MIS-C patients lacked neutrophilic infiltrate of muscularis propria typical for AA (14% vs. 95%, P < 0.001). The proportion of CD20+ to CD5+ cells was higher in patients with MIS-C (P = 0.04), as was the proportion of CD4+ to CD8+ (P < 0.001). We found no proof of SARS-CoV-2 antigen presence, nor lymphocyte exhaustion, in the appendices of MIS-C patients. CONCLUSIONS: The appendiceal muscularis of patients with MIS-C lack edema and neutrophilic infiltration typical for AA. SARS-CoV-2 antigens and PD-1 are absent in the appendices of children with MIS-C. These findings argue against the central role of SARS-CoV-2 persistence in the gut and lymphocyte exhaustion as the major triggers of MIS-C.

Assessment of the Choroidal Vascular Structure in Multisystem Inflammatory Syndrome in Children.

PURPOSE: To evaluate the choroidal vascular structure in cases of multisystem inflammatory syndrome in children (MIS-C). METHODS: This prospective study included 38 eyes of 19 patients with MIS-C and 60 eyes of 30 healthy participants. Optical coherence tomography (OCT) imaging was performed at 1 month after diagnosis in the MIS-C group. Using enhanced depth imaging OCT, choroidal thickness was measured in the subfoveal, nasal, and temporal quadrants at 500 and 1,500 µm distances from the fovea (SCT, N500CT, T500CT, N1500CT, and T1500CT, respectively). The luminal, stromal, and total choroidal areas were evaluated with the binarization method in ImageJ software (National Institutes of Health). The ratio of the luminal area to the total choroidal area was determined as the choroidal vascular index (CVI). RESULTS: The age and sex distributions of the two groups without any ophthalmologic pathology were similar (P > .05). The choroidal thickness values in all quadrants except for T1500CT were similar between the two groups (P > .05). T1500CT was significantly lower in the MIS-C group (P = .02). The luminal choroidal area was 1.04 ± 0.10 mm2 in the MIS-C group and 1.26 ± 0.24 mm2 in the healthy control group (P < .001), and the CVI values were 0.52 ± 0.04 and 0.57 ± 0.09, respectively (P = .01). The stromal and total choroidal area values did not significantly differ between the two groups (P > .05). CONCLUSIONS: This is the first study to evaluate CVI in patients with MIS-C. It was observed that the choroidal vascular structure could be affected in the early period of MIS-C, as shown by a decrease in the CVI value and luminal vascular area. OCT can be used to monitor ocular vascular changes in these patients. [J Pediatr Ophthalmol Strabismus. 2024;61(2):120-126.].

Effects of the exosomes of adipose-derived mesenchymal stem cells on apoptosis and pyroptosis of injured liver in miniature pigs.

Hepatic ischemia-reperfusion injury (HIRI) is a complication of hepatectomy that affects the functional recovery of the remnant liver, which has been demonstrated to be associated with pyroptosis and apoptosis. Mesenchymal stem cells (MSCs) can protect against HIRI in rodents. Paracrine mechanisms of MSCs indicated that MSCs-derived exosomes (MSCs-exo) are one of the important components within the paracrine substances of MSCs. Moreover, miniature pigs are ideal experimental animals in comparative medicine compared to rodents. Accordingly, this study aimed to investigate whether hepatectomy combined with HIRI in miniature pigs would induce pyroptosis and whether adipose-derived MSCs (ADSCs) and their exosomes (ADSCs-exo) could positively mitigate apoptosis and pyroptosis. The study also compared the differences in the effects and the role of ADSCs and ADSCs-exo in pyroptosis and apoptosis. Results showed that severe ultrastructure damage occurred in liver tissues and systemic inflammatory response was induced after surgery, with TLR4/MyD88/NFκB/HMGB1 activation, NLRP3-ASC-Caspase1 complex generation, GSDMD revitalization, and IL-1ß, IL-18, and LDH elevation in the serum. Furthermore, expression of Fas-Fasl-Caspase8 and CytC-APAF1-Caspase9 was increased in the liver. The ADSCs or ADSCs-exo intervention could inhibit the expression of these indicators and improve the ultrastructural pathological changes and systemic inflammatory response. There was no significant difference between the two intervention groups. In summary, ADSCs-exo could effectively inhibit pyroptosis and apoptosis similar to ADSCs and may be considered a safe and effective cell-free therapy to protect against liver injury.

Neutrophil extracellular traps formation and clearance is enhanced in fever and attenuated in hypothermia.

Fever and hypothermia represent two opposite strategies for fighting systemic inflammation. Fever results in immune activation; hypothermia is associated with energy conservation. Systemic Inflammatory Response Syndrome (SIRS) remains a significant cause of mortality worldwide. SIRS can lead to a broad spectrum of clinical symptoms but importantly, patients can develop fever or hypothermia. During infection, polymorphonuclear cells (PMNs) such as neutrophils prevent pathogen dissemination through the formation of neutrophil extracellular traps (NETs) that ensnare and kill bacteria. However, when dysregulated, NETs also promote host tissue damage. Herein, we tested the hypothesis that temperature modulates NETs homeostasis in response to infection and inflammation. NETs formation was studied in response to infectious (Escherichia coli, Staphylococcus aureus) and sterile (mitochondria) agents. When compared to body temperature (37°C), NETs formation increased at 40°C; interestingly, the response was stunted at 35°C and 42°C. While CD16+ CD49d+ PMNs represent a small proportion of the neutrophil population, they formed ~45-85% of NETs irrespective of temperature. Temperature increased formyl peptide receptor 1 (FPR1) expression to a differential extent in CD16+ CD49d- vs. CD49d+ PMNSs, suggesting further complexity to neutrophil function in hypo/hyperthermic conditions. The capacity of NETs to induce Toll-like receptor 9 (TLR9)-mediated NF-κB activation was found to be temperature independent. Interestingly, NET degradation was enhanced at higher temperatures, which corresponded with greater plasma DNase activity in response to temperature increase. Collectively, our observations indicate that NETs formation and clearance are enhanced at 40°C whilst temperatures of 35°C and 42°C attenuate this response. Targeting PMN-driven immunity may represent new venues for intervention in pathological inflammation.

Systemic inflammatory response markers for prediction of response to neoadjuvant chemotherapy in patients with advanced gastric cancer.

BACKGROUND: Tumour development is greatly influenced by the systemic inflammatory response. Inflammatory factors, such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphcyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR), mirror the balance between systemic inflammation and anti-tumour response. The current investigation examined the predictive and prognostic value of NLR, PLR, and LMR in advanced gastric cancer (GC) patients. METHODS: This study is a retrospective, observational analysis involving 105 GC patients treated with neoadjuvant chemotherapy (NAC). Thestudy population included patients who met the eligibility criteria.The relationship between NLR, PLR, LMR and demographic and clinical variables was assessed using theΧ2test. Survival data were analysed by Kaplan-Meier curves. RESULTS: High NLR levels were associated with more advanced tumour stage.Higher risk of no tumour regression after NAC was observed if a high pretreatment level of NLR or PLR was found. All patients with an increase in NLR after NAC had a significantly higher risk of no tumor response.In groups high (no change), increase, decrease, and low (no change), NLR and PLR OS medians were: 33, 67, 78, and not reached-NR and 34, 29, 36, and NR, respectively. All patients had a significantly higher risk of death if NLR increased after NAC. An increase in post-NAC PLR level was associated with an increased risk of death only if the PLR baseline value was low. CONCLUSION: NLR and PLR are promising predictive and prognostic factors in advanced GC patients treated with NAC.

The role of mtDAMPs in the trauma-induced systemic inflammatory response syndrome.

Systemic inflammatory response syndrome (SIRS) is a non-specific exaggerated defense response caused by infectious or non-infectious stressors such as trauma, burn, surgery, ischemia and reperfusion, and malignancy, which can eventually lead to an uncontrolled inflammatory response. In addition to the early mortality due to the "first hits" after trauma, the trauma-induced SIRS and multiple organ dysfunction syndrome (MODS) are the main reasons for the poor prognosis of trauma patients as "second hits". Unlike infection-induced SIRS caused by pathogen-associated molecular patterns (PAMPs), trauma-induced SIRS is mainly mediated by damage-associated molecular patterns (DAMPs) including mitochondrial DAMPs (mtDAMPs). MtDAMPs released after trauma-induced mitochondrial injury, including mitochondrial DNA (mtDNA) and mitochondrial formyl peptides (mtFPs), can activate inflammatory response through multiple inflammatory signaling pathways. This review summarizes the role and mechanism of mtDAMPs in the occurrence and development of trauma-induced SIRS.

Fluoroquinolone-resistant Escherichia coli among the rectal flora is the predominant risk factor for severe infection after transrectal ultrasound-guided prostate biopsy: a prospective observational study.

BACKGROUND: Infection of the prostate gland following biopsy, usually with Escherichia coli, is a common complication, despite the use of antimicrobial prophylaxis. A fluoroquinolone (FQ) is commonly prescribed as prophylaxis. Worryingly, the rate of fluoroquinolone-resistant (FQ-R) E. coli species has been shown to be increasing. OBJECTIVE: This study aimed to identify risk factors associated with infection after transrectal ultrasound-guided prostate biopsy (TRUS-Bx). METHODS: This was a prospective study on patients undergoing TRUS-Bx in southeast Sweden. Prebiopsy rectal and urine cultures were obtained, and antimicrobial susceptibility and risk-group stratification were determined. Multivariate analyses were performed to identify independent risk factors for post-biopsy urinary tract infection (UTI) and FQ-R E. coli in the rectal flora. RESULTS: In all, 283 patients were included, of whom 18 (6.4%) developed post-TRUS-Bx UTIs. Of these, 10 (3.5%) had an UTI without systemic inflammatory response syndrome (SIRS) and 8 (2.8%) had a UTI with SIRS. Being in the medium- or high-risk groups of infectious complications was not an independent risk factor for UTI with SIRS after TRUS-Bx, but low-level FQ-resistance (minimum inhibitory concentration (MIC): 0.125-0.25 mg/L) or FQ-resistance (MIC > 0.5 mg/L) among E. coli in the faecal flora was. Risk for SIRS increased in parallel with increasing degrees of FQ-resistance. Significant risk factor for harbouring FQ-R E.coli was travelling outside Europe within the previous 12 months. CONCLUSION: The predominant risk factor for UTI with SIRS after TRUS-Bx was FQ-R E. coli among the faecal flora. The difficulty in identifying this type of risk factor demonstrates a need for studies on the development of a general approach either with rectal swab culture for targeted prophylaxis, or prior rectal preparation with a bactericidal agent such as povidone-iodine before TRUS-Bx to reduce the risk of FQ-R E. coli-related infection.

Acute cerebellar ataxia during acute COVID-19: A case series and review of the literature.

Acute coronavirus disease 2019 (COVID-19)-associated cerebellar ataxia without multisystem inflammatory syndrome in children (MIS-C) or encephalopathy in children has been rarely reported. We reviewed medical records of hospitalized children who had developed cerebellar ataxia during the acute phase of COVID-19 infection, without MIS-C or encephalopathy, in our center. We also conducted a literature review and summarized the clinical characteristics, treatment, and outcomes. We found three cases in our center and additional three cases in the literature. All patients were male and five were preschool children. The cerebellar symptoms started between day 2 and day 10 during the acute phase of the COVID-19 infection. Two cases were complicated by mutism. One patient received therapy for acute cerebellar ataxia with corticosteroids, and others did not receive any specific therapy for acute cerebellar ataxia. The symptoms improved completely in all patients, with the recovery interval ranging from one week to two months. Further studies are warranted to elucidate the pathogenesis of acute cerebellar ataxia during acute COVID-19 in children.

Protective mechanisms of Leontopodium leontopodioides extracts on lipopolysaccharide-induced acute kidney injury viathe NF-κB/NLRP3 pathway.

Sepsis-induced uncontrolled systemic inflammatory response syndrome (SIRS) is a critical cause of multiple organ failure. Acute kidney injury (AKI) is one of the most serious complications associated with an extremely high mortality rate in SIRS, and it lacked simple, safe, and effective treatment strategies. Leontopodium leontopodioides (Willd.) Beauv (LLB) is commonly used in traditional Chinese medicine for the treatment of acute and chronic nephritis. However, it remains unclear whether lipopolysaccharide (LPS) affects LPS-induced AKI. To identify the molecular mechanisms of LLB in LPS-induced HK-2 cells and mice, LLB was prepared by extraction with 70% methanol, while a lipopolysaccharide (LPS)-induced HK-2 cell model and an AKI model were established in this study. Renal histopathology staining was performed to observe the morphology changes. The cell supernatant and kidney tissues were collected for determining the levels of inflammatory factors and protein expression by ELISA, immunofluorescence, and Western blot. The results indicated that LLB significantly reduced the expression of IL-6 and TNF-α in LPS-induced HK-2 cells, as well as the secretion of IL-6, TNF-α, and IL-1ß in the supernatant. The same results were observed in LPS-induced AKI serum. Further studies revealed that LLB remarkably improved oxidative stress and apoptosis based on the content of MDA, SOD, and CAT in serum and TUNEL staining results. Notably, LLB significantly reduced the mortality due to LPS infection. Renal histopathology staining results supported these results. Furthermore, immunofluorescence and Western blot results confirmed that LLB significantly reduced the expression of the protein related to the NF-κB signaling pathway and NLRP3, ASC, and Caspase-1 which were significantly increased through LPS stimulation. These findings clearly demonstrated the potential use of LLB in the treatment of AKI and the crucial role of the NF-κB/NLRP3 pathway in the process through which LLB attenuates AKI induced by LPS.

Protective mechanisms of Leontopodium leontopodioides extracts on lipopolysaccharide-induced acute kidney injury viathe NF-κB/NLRP3 pathway / 中国天然药物

Sepsis-induced uncontrolled systemic inflammatory response syndrome (SIRS) is a critical cause of multiple organ failure. Acute kidney injury (AKI) is one of the most serious complications associated with an extremely high mortality rate in SIRS, and it lacked simple, safe, and effective treatment strategies. Leontopodium leontopodioides (Willd.) Beauv (LLB) is commonly used in traditional Chinese medicine for the treatment of acute and chronic nephritis. However, it remains unclear whether lipopolysaccharide (LPS) affects LPS-induced AKI. To identify the molecular mechanisms of LLB in LPS-induced HK-2 cells and mice, LLB was prepared by extraction with 70% methanol, while a lipopolysaccharide (LPS)-induced HK-2 cell model and an AKI model were established in this study. Renal histopathology staining was performed to observe the morphology changes. The cell supernatant and kidney tissues were collected for determining the levels of inflammatory factors and protein expression by ELISA, immunofluorescence, and Western blot. The results indicated that LLB significantly reduced the expression of IL-6 and TNF-α in LPS-induced HK-2 cells, as well as the secretion of IL-6, TNF-α, and IL-1β in the supernatant. The same results were observed in LPS-induced AKI serum. Further studies revealed that LLB remarkably improved oxidative stress and apoptosis based on the content of MDA, SOD, and CAT in serum and TUNEL staining results. Notably, LLB significantly reduced the mortality due to LPS infection. Renal histopathology staining results supported these results. Furthermore, immunofluorescence and Western blot results confirmed that LLB significantly reduced the expression of the protein related to the NF-κB signaling pathway and NLRP3, ASC, and Caspase-1 which were significantly increased through LPS stimulation. These findings clearly demonstrated the potential use of LLB in the treatment of AKI and the crucial role of the NF-κB/NLRP3 pathway in the process through which LLB attenuates AKI induced by LPS.

Prognostic significance of systemic inflammatory response markers in patients with superficial esophageal squamous cell carcinomas.

Endoscopic resection or esophagectomy has becoming the standard treatment for superficial esophageal squamous cell carcinomas (SESCC), but some patients may develop disease progression or second primary cancers after the therapies. Neutrophil to lymphocyte ratio (NLR), lymphocyte to monocyte ratio (LMR), and platelet to lymphocyte ratio (PLR) reflect the balance between pro-cancer inflammatory and anti-cancer immune responses, however their roles in SESCC are still unknown. We consecutively enrolled patients with newly diagnosed SESCC (clinical stage Tis or T1N0M0) who were treated at our institute. Pre-treatment NLR, LMR and PLR were assessed and then correlated with clinical factors and long-term survival. A total of 156 patients were enrolled (152 males, 4 females; median age: 52.2 years), of whom 104 received endoscopic resection and 52 were treated with esophagectomy or chemoradiation.. During a mean follow-up period of 60.1 months, seventeen patients died of ESCCs, and 45 died of second primary cancers. The 5-year ESCC-specific survival and 5-year overall survival rate were 86% and 57%, respectively. LMR (P < 0.05) and NLR (P < 0.05), but not PLR were significantly correlated with overall survival. Receiver operating characteristic curve analysis showed optimal LMR and NLR cut-off values of 4 and 2.5, respectively, to predict a poor prognosis. Patients with a high NLR or low LMR tended to have longer tumor length, larger circumferential extension, and presence of second primary cancers. Multivariate Cox regression analysis showed that presence of second primary cancers (HR: 5.05, 95%CI: 2.75-9.28), low LMR (HR: 2.56, 95%CI: 1.09-6.03) were independent risk factors for poor survival. A low pre-treatment LMR may be a non-invasive pretreatment predictor of poor prognosis to guide the surveillance program, suggesting that anti-cancer immunity may play a role in the early events of esophageal squamous cancer.

Systemic inflammatory response in predicting outcomes of patients undergoing curative resection for oral squamous cell carcinoma.

This study aimed to evaluate the prognostic significance of the modified Glasgow prognostic score (mGPS), neutrophil:lymphocyte ratio (NLR), and platelet:lymphocyte ratio (PLR) in patients undergoing resection of oral squamous cell carcinoma (OSCC) with curative intent. We also aimed to explore the relation between activated systemic inflammation and adverse tumour characteristics. Between February 2006 and December 2019, data on 825 patients undergoing curative resection of OSCC were retrospectively gathered. Preoperative C-reactive protein and serum albumin levels were obtained to calculate a mGPS. Full blood count parameters were collected to calculate NLR and PLR values. Categorical factors were analysed using the chi squared test. Multivariate regression was performed to identify independent prognostic variables and the predictive value of each model generated. For disease-specific survival (DSS) and overall survival (OS), mGPS (DSS and OS both p<0.001), NLR (DSS and OS both p<0.001) and PLR (DSS and OS both p<0.001) were significant on univariate analysis. Independent predictive variables for DSS included mGPS, clinical node stage, categorised depth of tumour invasion, non-cohesive invasive front, and lymphovascular invasion. The concordance index was acceptable (0.756) for this model. Replacing mGPS with NLR or PLR as a marker of systemic inflammation demonstrated the same preoperative variables as independently predictive for DSS. The concordance index for these models were acceptable (NLR 0.76 and PLR 0.756). The systemic inflammatory response is prognostically significant in patients undergoing curative resection of OSCC. The potential link between an inflammatory tumour microenvironment and activated systemic inflammation merits further investigation.

Circulating cardiomyocyte-derived extracellular vesicles reflect cardiac injury during systemic inflammatory response syndrome in mice.

The release of extracellular vesicles (EVs) is increased under cellular stress and cardiomyocyte damaging conditions. However, whether the cardiomyocyte-derived EVs eventually reach the systemic circulation and whether their number in the bloodstream reflects cardiac injury, remains unknown. Wild type C57B/6 and conditional transgenic mice expressing green fluorescent protein (GFP) by cardiomyocytes were studied in lipopolysaccharide (LPS)-induced systemic inflammatory response syndrome (SIRS). EVs were separated both from platelet-free plasma and from the conditioned medium of isolated cardiomyocytes of the left ventricular wall. Size distribution and concentration of the released particles were determined by Nanoparticle Tracking Analysis. The presence of GFP + cardiomyocyte-derived circulating EVs was monitored by flow cytometry and cardiac function was assessed by echocardiography. In LPS-treated mice, systemic inflammation and the consequent cardiomyopathy were verified by elevated plasma levels of TNFα, GDF-15, and cardiac troponin I, and by a decrease in the ejection fraction. Furthermore, we demonstrated elevated levels of circulating small- and medium-sized EVs in the LPS-injected mice. Importantly, we detected GFP+ cardiomyocyte-derived EVs in the circulation of control mice, and the number of these circulating GFP+ vesicles increased significantly upon intraperitoneal LPS administration (P = 0.029). The cardiomyocyte-derived GFP+ EVs were also positive for intravesicular troponin I (cTnI) and muscle-associated glycogen phosphorylase (PYGM). This is the first direct demonstration that cardiomyocyte-derived EVs are present in the circulation and that the increased number of cardiac-derived EVs in the blood reflects cardiac injury in LPS-induced systemic inflammation (SIRS).

Endothelial contribution to COVID-19: an update on mechanisms and therapeutic implications.

The global propagation of SARS-CoV-2 leads to an unprecedented public health emergency. Despite that the lungs are the primary organ targeted by COVID-19, systemic endothelial inflammation and dysfunction is observed particularly in patients with severe COVID-19, manifested by elevated endothelial injury markers, endotheliitis, and coagulopathy. Here, we review the clinical characteristics of COVID-19 associated endothelial dysfunction; and the likely pathological mechanisms underlying the disease including direct cell entry or indirect immune overreactions after SARS-CoV-2 infection. In addition, we discuss potential biomarkers that might indicate the disease severity, particularly related to the abnormal development of thrombosis that is a fatal vascular complication of severe COVID-19. Furthermore, we summarize clinical trials targeting the direct and indirect pathological pathways after SARS-CoV-2 infection to prevent or inhibit the virus induced endothelial disorders.

Multisystem Inflammatory Syndrome in a Pediatric Patient With Sickle Cell Disease and COVID-19: A Case Report.

To this day, there are limited data about the effects and management of coronavirus disease infection in pediatric patients with sickle cell disease. We present the management and successful clinical course of an 8-year-old female with homozygous sickle cell disease (SS) and severe acute chest syndrome secondary to coronavirus disease 2019 infection, complicated by cortical vein thrombosis.

Osteopontin as a biomarker for COVID-19 severity and multisystem inflammatory syndrome in children: A pilot study.

This study sought to evaluate the candidacy of plasma osteopontin (OPN) as a biomarker of COVID-19 severity and multisystem inflammatory condition in children (MIS-C) in children. A retrospective analysis of 26 children (0-21 years of age) admitted to Children's Healthcare of Atlanta with a diagnosis of COVID-19 between March 17 and May 26, 2020 was undertaken. The patients were classified into three categories based on COVID-19 severity levels: asymptomatic or minimally symptomatic (control population, admitted for other non-COVID-19 conditions), mild/moderate, and severe COVID-19. A fourth category of children met the Centers for Disease Control and Prevention's case definition for MIS-C. Residual blood samples were analyzed for OPN, a marker of inflammation using commercial ELISA kits (R&D), and results were correlated with clinical data. This study demonstrates that OPN levels are significantly elevated in children hospitalized with moderate and severe COVID-19 and MIS-C compared to OPN levels in mild/asymptomatic children. Further, OPN differentiated among clinical levels of severity in COVID-19, while other inflammatory markers including maximum erythrocyte sedimentation rate, C-reactive protein and ferritin, minimum lymphocyte and platelet counts, soluble interleukin-2R, and interleukin-6 did not. We conclude OPN is a potential biomarker of COVID-19 severity and MIS-C in children that may have future clinical utility. The specificity and positive predictive value of this marker for COVID-19 and MIS-C are areas for future larger prospective research studies.

Urticarial vasculitis: A potential signpost for multisystem inflammatory syndrome in children.

Multisystem inflammatory syndrome in children (MIS-C) is a rare and serious complication of Sars-Cov-2 infection. Dermatologic manifestations are present in the majority of patients. Skin lesions found in children with MIS-C are classified into four categories: morbilliform, reticulated, scarlatiniform, and urticarial lesions. Clinicopathologic characterization within these categories is limited. Thus, we present a clear example of an urticarial lesion in the context of MIS-C with well-documented clinicopathologic phenomena. A previously healthy 16-year-old female presented with 3 weeks of an itchy, burning rash initially presenting on her right forearm (and lasting greater than 24 hours without migration) before spreading diffusely. She also reported fever, cough, myalgias, nausea, and vomiting of 4 weeks' duration. Physical examination revealed an edematous, maculopapular, nonblanching, erythematous rash covering the patient's upper extremities, abdomen, back, anterior thighs, and face. The patient tested positive for COVID-19. A low-grade leukocytoclastic vasculitis was noted along with intraluminal fibrin and rare microthrombi in vessels of the mid to deep dermis. The patient was diagnosed with MIS-C and urticarial vasculitis. She was treated with steroids and naproxen for subsequent MIS-C flares. Dapsone treatment was started for the urticarial vasculitis.

Differentiating multisystem inflammatory syndrome in children: a single-centre retrospective cohort study.

OBJECTIVE: Features of multisystem inflammatory syndrome in children (MIS-C) overlap with other febrile illnesses, hindering prompt and accurate diagnosis. The objectives of this study were to identify clinical and laboratory findings that distinguished MIS-C from febrile illnesses in which MIS-C was considered but ultimately excluded, and to examine the diseases that most often mimicked MIS-C in a tertiary medical centre. STUDY DESIGN: We identified all children hospitalised with fever who were evaluated for MIS-C at our centre and compared clinical signs and symptoms, SARS-CoV-2 status and laboratory studies between those with and without MIS-C. Multivariable logistic LASSO (least absolute shrinkage and selection operator) regression was used to identify the most discriminative presenting features of MIS-C. RESULTS: We identified 50 confirmed MIS-C cases (MIS-C+) and 68 children evaluated for, but ultimately not diagnosed with, MIS-C (MIS-C-). In univariable analysis, conjunctivitis, abdominal pain, fatigue, hypoxaemia, tachypnoea and hypotension at presentation were significantly more common among MIS-C+ patients. MIS-C+ and MIS-C- patients had similar elevations in C-reactive protein (CRP), but were differentiated by thrombocytopenia, lymphopenia, and elevated ferritin, neutrophil/lymphocyte ratio, BNP and troponin. In multivariable analysis, predictors of MIS-C included age, neutrophil/lymphocyte ratio, platelets, conjunctivitis, oral mucosa changes, abdominal pain and hypotension. CONCLUSIONS: Among hospitalised children undergoing evaluation for MIS-C, children with MIS-C were older, more likely to present with conjunctivitis, oral mucosa changes, abdominal pain and hypotension, and had higher neutrophil/lymphocyte ratios and lower platelet counts. These data may be helpful for discrimination of MIS-C from other febrile illnesses, including bacterial lymphadenitis and acute viral infection, with overlapping features.

Multisystem Inflammatory Syndrome in Children During Induction Chemotherapy in a Newly Diagnosed Pediatric Acute Myeloid Leukemia and Concurrent COVID-19.

A 15-year-old male presented with fatigue and weight loss for 1 month, petechiae and bruising for 2 weeks. He was diagnosed with concurrent new acute myeloid leukemia and coronavirus disease 2019. He was febrile and chest computed tomography scan showed ground glass opacities. Fever resolved after 4 days. Polymerase chain reaction test for coronavirus disease 2019 became negative after 2 days. Induction chemotherapy was initiated on day 8 and was complicated by multisystem inflammatory syndrome in children. The multisystem inflammatory syndrome in children was managed with symptomatic treatment and continued chemotherapy. Patient recovered and end of induction bone marrow showed remission of the leukemia.

TIM3+ TRBV11-2 T cells and IFNγ signature in patrolling monocytes and CD16+ NK cells delineate MIS-C.

In rare instances, pediatric SARS-CoV-2 infection results in a novel immunodysregulation syndrome termed multisystem inflammatory syndrome in children (MIS-C). We compared MIS-C immunopathology with severe COVID-19 in adults. MIS-C does not result in pneumocyte damage but is associated with vascular endotheliitis and gastrointestinal epithelial injury. In MIS-C, the cytokine release syndrome is characterized by IFNγ and not type I interferon. Persistence of patrolling monocytes differentiates MIS-C from severe COVID-19, which is dominated by HLA-DRlo classical monocytes. IFNγ levels correlate with granzyme B production in CD16+ NK cells and TIM3 expression on CD38+/HLA-DR+ T cells. Single-cell TCR profiling reveals a skewed TCRß repertoire enriched for TRBV11-2 and a superantigenic signature in TIM3+/CD38+/HLA-DR+ T cells. Using NicheNet, we confirm IFNγ as a central cytokine in the communication between TIM3+/CD38+/HLA-DR+ T cells, CD16+ NK cells, and patrolling monocytes. Normalization of IFNγ, loss of TIM3, quiescence of CD16+ NK cells, and contraction of patrolling monocytes upon clinical resolution highlight their potential role in MIS-C immunopathogenesis.