Browsing by Author "Suazo Gálvez, Isidora del Carmen"

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    Evaluation of changes in virulence gene expression in Salmonella enterica serovar Enteritidis resulting from deletion of genes associated to the excision of the pathogenicity island ROD21.
    (2023) Suazo Gálvez, Isidora del Carmen; Bueno Ramírez, Susan; Pontificia Universidad Católica de Chile. Facultad de Ciencias Biológicas
    Pathogenicity islands (PAIs) are mobile genetic elements acquired by horizontal gene transfer in bacteria. Some PAIs have been described as excisable elements, in which the excision process involves several proteins that are encoded within and outside the PAIs, among them, an integrase and a recombination directionality factor (RDF). This process is involved in the regulation of bacterial gene expression and virulence. Salmonella enterica serovar Enteritidis (SEn) is a pathogenic Gram-negative bacteria, which possesses several PAIs. One of them, known as ROD21, is an excisable PAI that has been linked to virulence in mice and poultry. In the case of ROD21, the genes SEN1970 and SEN1998 encode an integrase and an RDF, respectively. We developed a new mutant SEn strain lacking both SEN1970 and SEN1998 which in contrast to previous results showed us that the lack of these genes in SEn has no significant effect on the frequency of ROD21 excision, but it indeed has an impact on the transcriptional pattern of SEn, particularly affecting the transcription of genes located in SPI-2. In vivo experiments in mice also showed a differential capacity of our mutant SEn to reach levels of colonization at later stages of infection, as compared to the wild-type SEn strain. These results have led us to conclude that SEN1970 and SEN1998 are not essential for ROD21 excision but do have a possible role in regulating the transcription of virulence genes located in other pathogenicity islands, affecting the ability of SEn to cause systemic infection in mice.
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    Interleukin-10 Produced by Myeloid-Derived Suppressor Cells Provides Protection to Carbapenem-Resistant Klebsiella pneumoniae Sequence Type 258 by Enhancing Its Clearance in the Airways
    (2019) Peñaloza Cerda, Hernán F.; Noguera Mijares, Loreani Paola; Ahn, D.; Vallejos, Omar; Castellanos, Raquel M.; Vazquez, Yaneisi; Salazar Echegarai, Francisco Javier; González Carreño, Liliana; Suazo Gálvez, Isidora del Carmen; Pardo Roa, Catalina; Salazar, Geraldyne; Prince, Alice; Bueno Ramírez, Susan
    Carbapenem-resistant Klebsiella pneumoniae sequence type 258 (CRKP-ST258) can cause chronic infections in lungs and airways, with repeated episodes of bacteremia. In this report we addressed whether the recruitment of myeloid cells producing the anti-inflammatory cytokine interleukin-10 (IL-10) modulates the clearance of CKRP-ST258 in the lungs and establishes bacterial persistence. Our data demonstrate that during pneumonia caused by a clinical isolate of CRKP-ST258 (KP35) there is an early recruitment of monocyte-myeloid-derived suppressor cells (M-MDSCs) and neutrophils that actively produce IL-10. However, M-MDSCs were the cells that sustained the production of IL-10 over the time of infection evaluated. Using mice unable to produce IL-10 (IL-10-/-), we observed that the production of this cytokine during the infection caused by KP35 is important to control bacterial burden, to prevent lung damage, to modulate cytokine production, and to improve host survival. Importantly, intranasal transfer of bone marrow-derived M-MDSCs from mice able to produce IL-10 at 1 day prior to infection improved the ability of IL-10-/- mice to clear KP35 in the lungs, decreasing their mortality. Altogether, our data demonstrate that IL-10 produced by M-MDSCs is required for bacterial clearance, reduction of lung tissue damage, and host survival during KP35 pneumonia.
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    Opposing roles of IL-10 in acute bacterial infection
    (2016) Schultz, B.; Nieto Pacheco, Pamela Andrea; Salazar, G.; Suazo Gálvez, Isidora del Carmen; González Muñoz, Pablo Alberto; Riedel, C.; Alvarez Lobos, M.; Kalergis Parra, Alexis Mikes; Bueno Ramírez, Susan; Penaloza, H.
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    Pathogenicity island excision during an infection by Salmonella enterica serovar Enteritidis is required for crossing the intestinal epithelial barrier in mice to cause systemic infection
    (2019) Pardo Roa, Catalina; Salazar, G.A.; Noguera, L.; Salazar Echegarai, Francisco Javier; Vallejos, O.P.; Suazo Gálvez, Isidora del Carmen; Schultz, B.M.; Coronado Arrázola, Irenice; Kalergis Parra, Alexis Mikes; Bueno Ramírez, Susan