Exploring atypical manifestations and multisystem involvement of Epstein-Barr virus infection in hospitalized pediatric patients from Mexico: insights from a tertiary hospital (2012-2022).

INTRODUCTION: Epstein-Barr virus (EBV) infection, with a global prevalence exceeding 95%, typically manifests in children as infectious mononucleosis. However, clinical practice frequently encounters diverse atypical presentations characterized by multisystem involvement, often resulting in an unfavorable clinical course. Our objective is to describe the clinical manifestations and results of EBV infection in a tertiary pediatric hospital in Mexico. METHOD: An observational, transversal, retrospective, and descriptive study that included a systematic review of medical records (2012-2022) of patients under 18 years of age with detectable EBV particles in peripheral blood. RESULTS: The study included 26 patients with a median age of 5 years and a male predominance of 53.8%. Predominant symptoms were fever (85%) and lymphadenopathy (35%). Sixty-five percent had severe and atypical manifestations, including pneumonia and hepatic, hematologic-oncologic, and autoimmune diseases. Anemia, thrombocytopenia and leukopenia were common, with lymphocytosis in 19% of cases. The median EBV viral load was 2816 copies/mL (range: 555-355,500 copies/mL). Four deaths related to EBV infection were reported. Viral load in these cases also varied widely from 594 to 121,000 copies/mL. Supportive care was administered to 85% of patients, while others received antiviral treatment, steroids, and rituximab. CONCLUSION: Atypical manifestations were common, especially in children with multisystem involvement. EBV should be considered as a potential contributor to a diverse spectrum of clinical presentations, emphasizing the need for comprehensive evaluation and awareness in clinical diagnosis.

INTRODUCCIÓN: La infección por el virus de Epstein-Barr (VEB) tiene una prevalencia mundial superior al 95%. Se considera que en los niños se manifiesta principalmente como mononucleosis infecciosa; sin embargo, en la práctica clínica, a menudo encontramos numerosas manifestaciones atípicas con compromiso multisistémico que llevan a un curso desfavorable. Nuestro objetivo es describir las manifestaciones clínicas y los resultados de la infección por VEB en un hospital pediátrico de tercer nivel en México. MÉTODO: Estudio observacional, transversal, retrospectivo y descriptivo, en el cual se revisaron sistemáticamente los expedientes médicos de pacientes menores de 18 años con una detección positiva de partículas de VEB en sangre periférica en el periodo 2012-2022. RESULTADOS: Se incluyeron 26 pacientes con una mediana de edad de 5 años y predominio de varones (53.8%). El 65% presentaron manifestaciones graves y atípicas, incluyendo enfermedades respiratorias, hepáticas, hematooncológicas y autoinmunitarias. Los síntomas más frecuentes fueron fiebre (85%) y linfadenopatía (35%). El 54% presentaron manifestaciones atípicas, incluyendo linfohistiocitosis hemofagocítica, neumonía y neoplasia. La anemia, la trombocitopenia y la leucocitopenia fueron comunes, mientras que el 19% presentaron linfocitosis. La media de la carga viral fue de 2816 copias/ml (555-355,500). Se informaron cuatro muertes atribuidas a la infección por VEB, con valores de carga viral de 594 a 121,000 copias/ml. El 85% de los pacientes recibieron solo tratamiento sintomático, mientras que otros recibieron antivirales, esteroides y rituximab. CONCLUSIÓN: Las manifestaciones atípicas se observaron comúnmente, en especial en niños con compromiso multisistémico. El VEB debe considerarse como un potencial factor contribuyente en el diagnóstico de una amplia gama de manifestaciones clínicas.

Macrophage Polarization Modulates FcγR- and CD13-Mediated Phagocytosis and Reactive Oxygen Species Production, Independently of Receptor Membrane Expression.

In response to microenvironmental cues, macrophages undergo a profound phenotypic transformation acquiring distinct activation phenotypes ranging from pro-inflammatory (M1) to anti-inflammatory (M2). To study how activation phenotype influences phagocytosis and production of reactive oxygen species (ROS) mediated by receptors for IgG antibodies (Fcγ receptors) and by CD13, human monocyte-derived macrophages were polarized to distinct phenotypes using IFN-γ (Mϕ-IFN-γ), IL-4 (Mϕ-IL-4), or IL-10 (Mϕ-IL-10). Phenotypically, Mϕ-IFN-γ were characterized as CD14+CD80+CD86+ cells, Mϕ-IL-4 as CD209highCD206+CD11b+CD14low, and Mϕ-IL-10 as CD16+CD163+ cells. Compared to non-polarized macrophages, FcγRI expression increased in Mϕ-IFN-γ and Mϕ-IL-10 and FcγRIII expression increased in Mϕ-IL-10. None of the polarizing cytokines modified FcγRII or CD13 expression. Functionally, we found that cytokine-mediated activation significantly and distinctively affected FcγR- and CD13-mediated phagocytosis and ROS generation. Compared to non-polarized macrophages, FcγRI-, FcγRII-, and CD13-mediated phagocytosis was significantly increased in Mϕ-IL-10 and decreased in Mϕ-IFN-γ, although both cytokines significantly upregulated FcγRI expression. IL-10 also increased phagocytosis of Escherichia coli, showing that the effect of IL-10 on macrophage phagocytosis is not specific for a particular receptor. Interestingly, Mϕ-IL-4, which showed poor FcγR- and CD13-mediated phagocytosis, showed very high phagocytosis of E. coli and zymosan. Coupled with phagocytosis, macrophages produce ROS that contribute to microbial killing. As expected, Mϕ-IFN-γ showed significant production of ROS after FcγRI-, FcγRII-, or CD13-mediated phagocytosis. Unexpectedly, we found that Mϕ-IL-10 can also produce ROS after simultaneous stimulation through several phagocytic receptors, as coaggregation of FcγRI/FcγRII/CD13 induced a belated but significant ROS production. Together, these results demonstrate that activation of macrophages by each cytokine distinctly modulates expression of phagocytic receptors, FcγR- and CD13-mediated phagocytosis, and ROS production.