Browsing by Author "Bueno, Susan M."

Now showing 1 - 3 of 3
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    Altered Chemokine Receptor Expression in Papillary Thyroid Cancer
    (MARY ANN LIEBERT, INC, 2009) Gonzalez, Hernan E.; Leiva, Andrea; Tobar, Hugo; Boehmwald, Karen; Tapia, Grace; Torres, Javiera; Mosso, Lorena M.; Bueno, Susan M.; Gonzalez, Pablo; Kalergis, Alexis M.; Riedel, Claudia A.
    Background: Papillary thyroid cancer (PTC), the most prevalent type of differentiated thyroid carcinoma, displays a strikingly high frequency of lymph node metastasis (LNM). Recent data suggest that chemokines can play an important role in promoting tumor progression and metastatic migration of tumor cells. Here we have evaluated whether PTC tissues express a different pattern of chemokine receptors and if the expression of these receptors correlates with LNM.
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    Excision of an Unstable Pathogenicity Island in Salmonella enterica Serovar Enteritidis Is Induced during Infection of Phagocytic Cells
    (PUBLIC LIBRARY SCIENCE, 2011) Quiroz, Tania S.; Nieto, Pamela A.; Tobar, Hugo E.; Salazar Echegarai, Francisco J.; Lizana, Rodrigo J.; Quezada, Carolina P.; Santiviago, Carlos A.; Araya, Daniela V.; Riedel, Claudia A.; Kalergis, Alexis M.; Bueno, Susan M.
    The availability of the complete genome sequence of several Salmonella enterica serovars has revealed the presence of unstable genetic elements in these bacteria, such as pathogenicity islands and prophages. This is the case of Salmonella enterica serovar Enteritidis (S. Enteritidis), a bacterium that causes gastroenteritis in humans and systemic infection in mice. The whole genome sequence analysis for S. Enteritidis unveiled the presence of several genetic regions that are absent in other Salmonella serovars. These regions have been denominated "regions of difference'' (ROD). In this study we show that ROD21, one of such regions, behaves as an unstable pathogenicity island. We observed that ROD21 undergoes spontaneous excision by two independent recombination events, either under laboratory growth conditions or during infection of murine cells. Importantly, we also found that one type of excision occurred at higher rates when S. Enteritidis was residing inside murine phagocytic cells. These data suggest that ROD21 is an unstable pathogenicity island, whose frequency of excision depends on the environmental conditions found inside phagocytic cells.
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    Limited Heme Oxygenase Contribution to Modulating the Severity of Salmonella enterica serovar Typhimurium Infection
    (SPRINGER INTERNATIONAL PUBLISHING AG, 2022) Sebastian, Valentina P.; Moreno-Tapia, Daniela; Melo-Gonzalez, Felipe; Hernandez-Caceres, Maria P.; Salazar, Geraldyne A.; Pardo-Roa, Catalina; Farias, Monica A.; Vallejos, Omar P.; Schultz, Barbara M.; Morselli, Eugenia; Alvarez-Lobos, Manuel M.; Gonzalez, Pablo A.; Kalergis, Alexis M.; Bueno, Susan M.
    An important virulence trait of Salmonella enterica serovar Typhimurium (S. Typhimurium) is the ability to avoid the host immune response, generating systemic and persistent infections. Host cells play a crucial role in bacterial clearance by expressing the enzyme heme oxygenase 1 (Hmox1), which catalyzes the degradation of heme groups into Fe2+, biliverdin, and carbon monoxide (CO). The role of Hmox1 activity during S. Typhimurium infection is not clear and previous studies have shown contradictory results. We evaluated the effect of pharmacologic modulation of Hmox1 in a mouse model of acute and persistent S. Typhimurium infection by administering the Hmox1 activity inductor cobalt protoporphyrin-IX (CoPP) or inhibitor tin protoporphyrin-IX (SnPP) before infection. To evaluate the molecular mechanism involved, we measured the colocalization of S. Typhimurium and autophagosome and lysosomal markers in macrophages. Administering CoPP reduced the bacterial burden in organs of mice 5 days post-infection, while SnPP-treated mice showed bacterial loads similar to vehicle-treated mice. Furthermore, CoPP reduced bacterial loads when administered after infection in macrophages in vitro and in a persistent infection model of S. Typhimurium in vivo, while tin protoporphyrin-IX (SnPP) treatment resulted in a bacterial burden similar to vehicle-treated controls. However, we did not observe significant differences in co-localization of green fluorescent protein (GFP)-labeled S. Typhimurium with the autophagic vesicles marker microtubule-associated protein 1A/1B-light chain 3 (LC3) and the lysosomal marker lysosomal-associated membrane protein 1 (LAMP-1) in macrophages treated with CoPP. Our results suggest that CoPP can enhance antimicrobial activity in response to Salmonella infection, reducing bacterial dissemination and persistence in mice, in a CO and autophagy- independent manner.