Browsing by Author "Silva, Pedro H."

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    Clustering analyses of murine bone marrow-derived neutrophils reveal a phenotypic heterogeneity that can respond differentially to stimulation
    (Elsevier Ltd., 2025) Silva, Pedro H.; Peñaloza Cerda, Hernán F.; Cordero, José; Kalergis Parra, Alexis Mikes; Barrera Rojas, Nelson Patricio; Bueno Ramírez, Susan
    Neutrophils are granulocytic cells produced in the bone marrow from a granulocytic progenitor cell. During infection, the production of chemokines and cytokines induces the recruitment of neutrophils to the infected tissue to promote the clearance of microbial pathogens. Several studies have shown that different subpopulations of neutrophils can be identified during infection. However, no previous studies evaluated subpopulations of neutrophils purified from the bone marrow (BM), which are typically used to study the biology of these cells based on the assumption that the neutrophil population is homogeneous. In the present study, responses of purified BM-derived neutrophils to various stimuli such as PMA, LPS, and Streptococcus pneumoniae were evaluated using flow cytometry and bh-SNE analyses. Further, neutrophil population heterogeneity was assessed by clustering analyses. Our data suggest that purified BM-derived neutrophils were not a homogeneous cell population and were clustered into 12 subsets, each displaying a unique marker profile, where CD11b and CD62L emerged as pivotal markers for neutrophil function. Importantly, the subsets responded differentially to each stimulus, suggesting a nuanced activation pattern. Changes in biomarker expression were analyzed via Ingenuity Pathway Analysis (IPA) to unravel functional implications of the identified clusters, revealing subsets associated with different neutrophil functions, such as “Migration of neutrophils” or “Phagocytosis in neutrophils”. This study contributes to understanding the diversity of purified BM- derived neutrophils and the implications of using these cellular preparations to raise conclusions about the functionality of these cells in various infection models.
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    Human metapneumovirus respiratory infection affects both innate and adaptive intestinal immunity
    (2024) Sepulveda-Alfaro, Javiera; Catalan, Eduardo A.; Vallejos, Omar P.; Ramos-Tapia, Ignacio; Madrid-Munoz, Cristobal; Mendoza-Leon, Maria J.; Suazo, Isidora D.; Rivera-Asin, Elizabeth; Silva, Pedro H.; Alvarez-Mardones, Oscar; Castillo-Godoy, Daniela P.; Riedel, Claudia A.; Schinnerling, Katina; Ugalde, Juan A.; Soto, Jorge A.; Bueno, Susan M.; Kalergis, Alexis M.; Melo-Gonzalez, Felipe
    Introduction Respiratory infections are one of the leading causes of morbidity and mortality worldwide, mainly in children, immunocompromised people, and the elderly. Several respiratory viruses can induce intestinal inflammation and alterations in intestinal microbiota composition. Human metapneumovirus (HMPV) is one of the major respiratory viruses contributing to infant mortality in children under 5 years of age worldwide, and the effect of this infection at the gut level has not been studied.Methods Here, we evaluated the distal effects of HMPV infection on intestinal microbiota and inflammation in a murine model, analyzing several post-infection times (days 1, 3, and 5). Six to eight-week-old C57BL/6 mice were infected intranasally with HMPV, and mice inoculated with a non-infectious supernatant (Mock) were used as a control group.Results We did not detect HMPV viral load in the intestine, but we observed significant changes in the transcription of IFN-gamma in the colon, analyzed by qPCR, at day 1 post-infection as compared to the control group. Furthermore, we analyzed the frequencies of different innate and adaptive immune cells in the colonic lamina propria, using flow cytometry. The frequency of monocyte populations was altered in the colon of HMPV -infected mice at days 1 and 3, with no significant difference from control mice at day 5 post-infection. Moreover, colonic CD8+ T cells and memory precursor effector CD8+ T cells were significantly increased in HMPV-infected mice at day 5, suggesting that HMPV may also alter intestinal adaptive immunity. Additionally, we did not find alterations in antimicrobial peptide expression, the frequency of colonic IgA+ plasma cells, and levels of fecal IgA. Some minor alterations in the fecal microbiota composition of HMPV -infected mice were detected using 16s rRNA sequencing. However, no significant differences were found in beta-diversity and relative abundance at the genus level.Discussion To our knowledge, this is the first report describing the alterations in intestinal immunity following respiratory infection with HMPV infection. These effects do not seem to be mediated by direct viral infection in the intestinal tract. Our results indicate that HMPV can affect colonic innate and adaptive immunity but does not significantly alter the microbiota composition, and further research is required to understand the mechanisms inducing these distal effects in the intestine.