Examinando por Autor "Escobar, Alejandro"

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    Lipopolysaccharide from Porphyromonas gingivalis, but Not from Porphyromonas endodontalis, Induces Macrophage M1 Profile
    (MDPI, 2022-09) Veloso, Pablo; Fernández, Alejandra; Astorga, Jessica; González Quintanilla, David; Castro, Alfredo; Escobar, Alejandro; Hoare, Anilei; Hernández, Marcela
    Apical Lesions of Endodontic Origin (ALEO) are initiated by polymicrobial endodontic canal infection. Porphyromonas gingivalis (Pg) and Porphyromonas endodontalis (Pe) lipopolysaccharides (LPS) can induce a pro-inflammatory macrophage response through their recognition by TLR2 and TLR4. However, polarization responses induced by Pg and/or Pe LPS in macrophages are not fully understood. We aimed to characterize the polarization profiles of macrophages differentiated from THP-1 cells following Pg and/or Pe LPS stimulation from reference strain and clinical isolates. A modified LPS purification protocol was implemented and the electrophoretic LPS profiles were characterized. THP-1 human monocytes differentiated to macrophages were stimulated with Pg and Pe LPS. Polarization profiles were characterized through cell surface markers and secreted cytokines levels after 24 h of stimulation. TLR2 and TLR4 cell surfaces and transcriptional levels were determined after 24 or 2 h of LPS stimulation, respectively. LPS from Pg induced a predominant M1 profile in macrophages evidenced by changes in the expression of the surface marker CD64 and pro-inflammatory cytokine profiles, TNF-α, IL-1β, IL-6, and IL-12. Pe LPS was unable to induce a significant response. TLR2 and TLR4 expressions were neither modified by Pg or Pe LPS. Pg LPS, but not Pe LPS, induced a macrophage M1 Profile. © 2022 by the authors.
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    Macrophage–Neisseria gonorrhoeae Interactions: A Better Understanding of Pathogen Mechanisms of Immunomodulation
    (Frontiers Media S.A., 2018-12) Escobar, Alejandro; Rodas, Paula; Acuña-Castillo, Claudio
    Neisseria gonorrhoeae is a significant health problem worldwide due to multi-drug resistance issues and absence of an effective vaccine. Patients infected with N. gonorrhoeae have not shown a better immune response in successive infections. This might be explained by the fact that N. gonorrhoeae possesses several mechanisms to evade the innate and adaptative immune responses at different levels. Macrophages are a key cellular component in the innate immune response against microorganisms. The current information suggests that gonococcus can hijack the host response by mechanisms that involve the control of macrophages activity. In this mini review, we intend to condense the recent knowledge on the macrophage–N. gonorrhoeae interactions with a focus on strategies developed by gonococcus to evade or to exploit immune response to establish a successful infection. Finally, we discuss the opportunities and challenges of therapeutics for controlling immune manipulation by N. gonorrhoeae. © Copyright © 2018 Escobar, Rodas and Acuña-Castillo.
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    Neisseria gonorrhoeae modulates immunity by polarizing human macrophages to a M2 profile
    (Public Library of Science, 2015-06) Ortiz, María Carolina; Lefimil, Claudia; Rodas, Paula; Vernal, Rolando; Lopez, Mercedes; Acuña-Castillo, Claudio; Imarai, Mónica; Escobar, Alejandro
    Current data suggest that Neisseria gonorrhoeae is able to suppress the protective immune response at different levels, such as B and T lymphocytes and antigen-presenting cells. The present report is focused on gonococcus evasion mechanism on macrophages (MΦ) and its impact in the subsequent immune response. In response to various signals MΦ may undergo classical-M1 (M1-MΦ) or alternative-M2 (M2-MΦ) activation. Until now there are no reports of the gonococcus effects on human MΦ polarization. We assessed the phagocytic ability of monocyte-derived MΦ (MDM) upon gonococcal infection by immunofluorescence and gentamicin protection experiments. Then, we evaluated cytokine profile and M1/ M2 specific-surface markers on MΦ challenged with N. gonorrhoeae and their proliferative effect on T cells. Our findings lead us to suggest N. gonorrhoeae stimulates a M2-MΦ phenotype in which some of the M2b and none of the M1-MΦ-associated markers are induced. Interestingly, N. gonorrhoeae exposure leads to upregulation of a Programmed Death Ligand 1 (PD-L1), widely known as an immunosuppressive molecule. Moreover, functional results showed that N. gonorrhoeae-treated MΦ are unable to induce proliferation of human T-cells, suggesting a more likely regulatory phenotype. Taken together, our data show that N. gonorroheae interferes with MΦ polarization. This study has important implications for understanding the mechanisms of clearance versus long-term persistence of N. gonorroheae infection and might be applicable for the development of new therapeutic strategies. © 2015 Ortiz et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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    The NarE protein of neisseria gonorrhoeae catalyzes ADP-ribosylation of several ADP-ribose acceptors despite an N-terminal deletion
    (Oxford University Press, 2016-09) Rodas, Paula I.; Álamos-Musre, A. Said; Álvarez, Francisca P.; Escobar, Alejandro; Tapia, Cecilia V.; Osorio, Eduardo; Otero, Carolina; Calderón, Iván L.; Fuentes, Juan A.; Gil, Fernando; Paredes-Sabja, Daniel; Christodoulides, Myron
    The ADP-ribosylating enzymes are encoded in many pathogenic bacteria in order to affect essential functions of the host. In this study, we show that Neisseria gonorrhoeae possess a locus that corresponds to the ADP-ribosyltransferase NarE, a previously characterized enzyme in N. meningitidis. The 291 bp coding sequence of gonococcal narE shares 100% identity with part of the coding sequence of the meningococcal narE gene due to a frameshift previously described, thus leading to a 49-amino-acid deletion at the N-terminus of gonococcal NarE protein. However, we found a promoter region and a GTG start codon, which allowed expression of the protein as demonstrated by RT-PCR and western blot analyses. Using a gonococcal NarE–6xHis fusion protein, we demonstrated that the gonococcal enzyme underwent auto-ADP-ribosylation but to a lower extent than meningococcal NarE. We also observed that gonoccocal NarE exhibited ADP-ribosyltransferase activity using agmatine and cell-free host proteins as ADP-ribose acceptors, but its activity was inhibited by human β-defensins. Taken together, our results showed that NarE of Neisseria gonorrhoeae is a functional enzyme that possesses key features of bacterial ADP-ribosylating enzymes.