Publications by authors named "Angelica M Riestra"

8 Publications

  • Page 1 of 1

Tuning the Innate Immune Response to Cyclic Dinucleotides by Using Atomic Mutagenesis.

Chembiochem 2020 09 8;21(18):2595-2598. Epub 2020 Jun 8.

Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0358, USA.

Cyclic dinucleotides (CDNs) trigger the innate immune response in eukaryotic cells through the stimulator of interferon genes (STING) signaling pathway. To decipher this complex cellular process, a better correlation between structure and downstream function is required. Herein, we report the design and immunostimulatory effect of a novel group of c-di-GMP analogues. By employing an "atomic mutagenesis" strategy, changing one atom at a time, a class of gradually modified CDNs was prepared. These c-di-GMP analogues induce type-I interferon (IFN) production, with some being more potent than c-di-GMP, their native archetype. This study demonstrates that CDN analogues bearing modified nucleobases are able to tune the innate immune response in eukaryotic cells.
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http://dx.doi.org/10.1002/cbic.202000162DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7494572PMC
September 2020

The Fungal Pathogen Promotes Bladder Colonization of Group B .

Front Cell Infect Microbiol 2019 10;9:437. Epub 2020 Jan 10.

Collaborative to Halt Antibiotic-Resistant Microbes, Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States.

Group B (GBS) is a common cause of bacterial urinary tract infections (UTI) in susceptible populations, including pregnant women and the elderly. However, the factors that govern GBS persistence and disease severity in this niche are not fully understood. Here, we report that the presence of the fungus , a common urogenital colonizer, can promote GBS UTI. Co-inoculation of GBS with increased bacterial adherence to bladder epithelium and promoted GBS colonization in a adhesin-dependent manner. This study demonstrates that fungal colonization of the urogenital tract may be an important determinant of bacterial pathogenesis during UTI.
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http://dx.doi.org/10.3389/fcimb.2019.00437DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6966239PMC
September 2020

Targeting the Achievement Gap: Strategies Toward Removing Inequities in Undergraduate Immunology Education.

Front Immunol 2019 11;10:2906. Epub 2019 Dec 11.

Department of Biological Sciences, California State Polytechnic University, Pomona, CA, United States.

A diverse student body enriches the classroom with lived experiences, varied skillsets, community and cultural knowledge, resiliency, and altruistic interests, all critical attributes that benefit both the classroom and the STEM field at large. However, a persistent disparity in academic and educational attainment exists between under-represented minority (URM) and non-URM students in STEM fields. This achievement gap discourages talented URM students from entering STEM professions, threatening the potential, expertise, and perspective of these professions. Here we describe the factors that contribute to the achievement gap and present strategies, utilized in our Immunology classrooms, for combating each factor. We discuss project-based learning pedagogy to give students increased agency and feelings of empowerment. We also highlight concrete practices to foster students' science identities and sense of community, factors that highly promote STEM retention. The dynamic subject of Immunology provides myriad opportunities to implement a curriculum committed to equity, as we outline below.
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http://dx.doi.org/10.3389/fimmu.2019.02906DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6919194PMC
October 2020

Siglec-14 Enhances NLRP3-Inflammasome Activation in Macrophages.

J Innate Immun 2020 5;12(4):333-343. Epub 2019 Dec 5.

Glycobiology Research and Training Center, UC San Diego, La Jolla, California, USA,

Pathogenic microorganisms are sensed by the inflammasome, resulting in the release of the pro-immune and proinflammatory cytokine interleukin-1β (IL-1β). In humans, the paired sialic acid-binding Ig-like lectin receptors Siglec-5 (inhibitory) and Siglec-14 (activating) have been shown to have reciprocal roles in regulating macrophage immune responses, but their interaction with IL-1β signaling and the inflammasome has not been characterized. Here we show that in response to known inflammasome activators (ATP, nigericin) or the sialic acid-expressing human bacterial pathogen group B Streptococcus (GBS), the presence of Siglec-14 enhances, whereas Siglec-5 reduces, inflammasome activation and macrophage IL-1β release. Human THP-1 macrophages stably transfected with Siglec-14 exhibited increased caspase-1 activation, IL-1β release and pyroptosis after GBS infection, in a manner blocked by a specific inhibitor of nucleotide-binding domain leucine-rich repeat protein 3 (NLRP3), a protein involved in inflammasome assembly. Another leading pathogen, Streptococcus pneumoniae, lacks sialic acid but rather prominently expresses a sialidase, which cleaves sialic acid from macrophages, eliminating cis- interactions with the lectin receptor, thus attenuating Siglec-14 induced IL-1β secretion. Vimentin, a cytoskeletal protein released during macrophage inflammatory activation is known to induce the inflammasome. We found that vimentin has increased interaction with Siglec-14 compared to Siglec-5, and this interaction heightened IL-1β production by Siglec-14-expressing cells. Siglec-14 is absent from some humans because of a SIGLEC5/14 fusion polymorphism, and we found increased IL-1β expression in primary macrophages from SIGLEC14+/+ individuals compared to those with the SIGLEC14-/+ and SIGLEC14-/- genotypes. Collectively, our results identify a new immunoregulatory role of Siglec-14 as a positive regulator of NLRP3 inflammasome activation.
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http://dx.doi.org/10.1159/000504323DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7383293PMC
July 2021

A Novel Cadherin-like Protein Mediates Adherence to and Killing of Host Cells by the Parasite Trichomonas vaginalis.

mBio 2019 05 14;10(3). Epub 2019 May 14.

Molecular Biology Institute, University of California, Los Angeles, California, USA

, a prevalent sexually transmitted parasite, adheres to and induces cytolysis of human mucosal epithelial cells. We have characterized a hypothetical protein, TVAG_393390, with predicted tertiary structure similar to that of mammalian cadherin proteins involved in cell-cell adherence. TVAG_393390, renamed cadherin-like protein (CLP), contains a calcium-binding site at a position conserved in cadherins. CLP is surface localized, and its mRNA and protein levels are significantly upregulated upon parasite adherence to host cells. To test the roles of CLP and its calcium-binding dependency during host cell adherence, we first demonstrated that wild-type CLP (CLP) binds calcium with a high affinity, whereas the calcium-binding site mutant protein (CLP-mut) does not. CLP and CLP-mut constructs were then used to overexpress these proteins in Parasites overexpressing CLP have ∼3.5-fold greater adherence to host cells than wild-type parasites, and this increased adherence is ablated by mutating the calcium-binding site. Additionally, competition with recombinant CLP decreased parasite binding to host cells. We also found that overexpression of CLP induced parasite aggregation which was further enhanced in the presence of calcium, whereas CLP-mut overexpression did not affect aggregation. Lastly, parasites overexpressing wild-type CLP induced killing of host cells ∼2.35-fold, whereas parasites overexpressing CLP-mut did not have this effect. These analyses describe the first parasitic CLP and demonstrate a role for this protein in mediating parasite-parasite and host-parasite interactions. CLP may represent convergent evolution of a parasite protein that is functionally similar to the mammalian cell adhesion protein cadherin, which contributes to parasite pathogenesis. The adherence of pathogens to host cells is critical for colonization of the host and establishing infection. Here we identify a protein with no known function that is more abundant on the surface of parasites that are better at binding host cells. To interrogate a predicted function of this protein, we utilized bioinformatic protein prediction programs which allowed us to uncover the first cadherin-like protein (CLP) found in a parasite. Cadherin proteins are conserved metazoan proteins with central roles in cell-cell adhesion, development, and tissue structure maintenance. Functional characterization of this CLP from the unicellular parasite demonstrated that the protein mediates both parasite-parasite and parasite-host adherence, which leads to an enhanced killing of host cells by Our findings demonstrate the presence of CLPs in unicellular pathogens and identify a new host cell binding protein family in a human-infective parasite.
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http://dx.doi.org/10.1128/mBio.00720-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6520450PMC
May 2019

The murine vaginal microbiota and its perturbation by the human pathogen group B Streptococcus.

BMC Microbiol 2018 11 26;18(1):197. Epub 2018 Nov 26.

Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California San Diego, 9500 Gilman Dr, MC 0760, La Jolla, CA, 92093-0760, USA.

Background: Composition of the vaginal microbiota has significant influence on female urogenital health and control of infectious disease. Murine models are widely utilized to characterize host-pathogen interactions within the vaginal tract, however, the composition of endogenous vaginal flora remains largely undefined with modern microbiome analyses. Here, we employ 16S rRNA amplicon sequencing to establish the native microbial composition of the vaginal tract in adult C57Bl/6 J mice. We further interrogate the impact of estrous cycle and introduction of the human vaginal pathobiont, group B Streptococcus (GBS) on community state type and stability, and conversely, the impact of the vaginal microbiota on GBS persistence.

Results: Sequencing analysis revealed five distinctive community states of the vaginal microbiota dominated largely by Staphylococcus and/or Enterococcus, Lactobacillus, or a mixed population. Stage of estrus did not impact microbial composition. Introduction of GBS decreased community stability at early timepoints; and in some mice, GBS became the dominant bacterium by day 21. Endogenous Staphylococcus abundance correlated with GBS ascension into the uterus, and increased community stability in GBS-challenged mice.

Conclusions: The murine vaginal flora is diverse and fluctuates independently of the estrous cycle. Endogenous flora may impact pathogen colonization and dissemination and should be considered in urogenital infection models.
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http://dx.doi.org/10.1186/s12866-018-1341-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6260558PMC
November 2018

Group A streptococcal M protein activates the NLRP3 inflammasome.

Nat Microbiol 2017 Oct 7;2(10):1425-1434. Epub 2017 Aug 7.

Department of Pediatrics, University of California, San Diego, La Jolla, CA, 92093, USA.

Group A Streptococcus (GAS) is among the top ten causes of infection-related mortality in humans. M protein is the most abundant GAS surface protein, and M1 serotype GAS strains are associated with invasive infections, including necrotizing fasciitis and toxic shock syndrome. Here, we report that released, soluble M1 protein triggers programmed cell death in macrophages (Mϕ). M1 served as a second signal for caspase-1-dependent NLRP3 inflammasome activation, inducing maturation and release of proinflammatory cytokine interleukin-1β (IL-1β) and macrophage pyroptosis. The structurally dynamic B-repeat domain of M1 was critical for inflammasome activation, which involved K efflux and M1 protein internalization by clathrin-mediated endocytosis. Mouse intraperitoneal challenge showed that soluble M1 was sufficient and specific for IL-1β activation, which may represent an early warning to activate host immunity against the pathogen. Conversely, in systemic infection, hyperinflammation associated with M1-mediated pyroptosis and IL-1β release could aggravate tissue injury.
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http://dx.doi.org/10.1038/s41564-017-0005-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5750061PMC
October 2017

A Trichomonas vaginalis Rhomboid Protease and Its Substrate Modulate Parasite Attachment and Cytolysis of Host Cells.

PLoS Pathog 2015 Dec 18;11(12):e1005294. Epub 2015 Dec 18.

Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, California, United States of America.

Trichomonas vaginalis is an extracellular eukaryotic parasite that causes the most common, non-viral sexually transmitted infection worldwide. Although disease burden is high, molecular mechanisms underlying T. vaginalis pathogenesis are poorly understood. Here, we identify a family of putative T. vaginalis rhomboid proteases and demonstrate catalytic activity for two, TvROM1 and TvROM3, using a heterologous cell cleavage assay. The two T. vaginalis intramembrane serine proteases display different subcellular localization and substrate specificities. TvROM1 is a cell surface membrane protein and cleaves atypical model rhomboid protease substrates, whereas TvROM3 appears to localize to the Golgi apparatus and recognizes a typical model substrate. To identify TvROM substrates, we interrogated the T. vaginalis surface proteome using both quantitative proteomic and bioinformatic approaches. Of the nine candidates identified, TVAG_166850 and TVAG_280090 were shown to be cleaved by TvROM1. Comparison of amino acid residues surrounding the predicted cleavage sites of TvROM1 substrates revealed a preference for small amino acids in the predicted transmembrane domain. Over-expression of TvROM1 increased attachment to and cytolysis of host ectocervical cells. Similarly, mutations that block the cleavage of a TvROM1 substrate lead to its accumulation on the cell surface and increased parasite adherence to host cells. Together, these data indicate a role for TvROM1 and its substrate(s) in modulating attachment to and lysis of host cells, which are key processes in T. vaginalis pathogenesis.
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http://dx.doi.org/10.1371/journal.ppat.1005294DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4684317PMC
December 2015
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