Two-Tier Lyme Disease Serology in Children with Previous Lyme Disease.

Background: A history of Lyme disease can complicate the interpretation of Lyme disease serology in acutely symptomatic patients. Materials and Methods: We prospectively enrolled children undergoing evaluation for Lyme disease in the emergency department of one of eight participating Pedi Lyme Net centers. We selected symptomatic children with a Lyme disease history (definite, probable, or none) as well as an available research biosample. We defined a Lyme disease case with either an erythema migrans (EM) lesion or positive two-tier serology with compatible symptoms. Using a generalized estimating equation, we examined the relationship between time from previous Lyme disease diagnosis and current Lyme disease after adjustment for patient demographics and symptoms as well as clustering by center. Results: Of 2501 prospectively enrolled study patients, 126 (5.0%) reported a history of definite or probable Lyme disease. Of these children with previous Lyme disease, 47 met diagnostic criteria for Lyme disease at the time of enrollment (37.3%; 95% confidence interval [CI] 29.1-45.7%); 2 had an EM lesion, and 45 had positive two-tier Lyme disease serology. Over time from the previous Lyme disease diagnosis, the less likely the patient met diagnostic criteria for Lyme disease (adjusted odds ratio 0.62 per time period; 95% CI 0.46-0.84). Conclusions: For children with a history of Lyme disease before enrollment, one-third met the diagnostic criteria for acute Lyme disease with a declining rate over time from previous Lyme disease diagnosis. Novel Lyme disease diagnostics are needed to help distinguish acute from previous Lyme disease.

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.

Evidence of thrombotic microangiopathy in children with SARS-CoV-2 across the spectrum of clinical presentations.

Most children with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have mild or minimal disease, with a small proportion developing severe disease or multisystem inflammatory syndrome in children (MIS-C). Complement-mediated thrombotic microangiopathy (TMA) has been associated with SARS-CoV-2 infection in adults but has not been studied in the pediatric population. We hypothesized that complement activation plays an important role in SARS-CoV-2 infection in children and sought to understand if TMA was present in these patients. We enrolled 50 hospitalized pediatric patients with acute SARS-CoV-2 infection (n = 21, minimal coronavirus disease 2019 [COVID-19]; n = 11, severe COVID-19) or MIS-C (n = 18). As a biomarker of complement activation and TMA, soluble C5b9 (sC5b9, normal 247 ng/mL) was measured in plasma, and elevations were found in patients with minimal disease (median, 392 ng/mL; interquartile range [IQR], 244-622 ng/mL), severe disease (median, 646 ng/mL; IQR, 203-728 ng/mL), and MIS-C (median, 630 ng/mL; IQR, 359-932 ng/mL) compared with 26 healthy control subjects (median, 57 ng/mL; IQR, 9-163 ng/mL; P < .001). Higher sC5b9 levels were associated with higher serum creatinine (P = .01) but not age. Of the 19 patients for whom complete clinical criteria were available, 17 (89%) met criteria for TMA. A high proportion of tested children with SARS-CoV-2 infection had evidence of complement activation and met clinical and diagnostic criteria for TMA. Future studies are needed to determine if hospitalized children with SARS-CoV-2 should be screened for TMA, if TMA-directed management is helpful, and if there are any short- or long-term clinical consequences of complement activation and endothelial damage in children with COVID-19 or MIS-C.