Publications by authors named "Liliana M Massis"

16 Publications

  • Page 1 of 1

A Rapid Caspase-11 Response Induced by IFN Priming Is Independent of Guanylate Binding Proteins.

iScience 2020 Oct 29;23(10):101612. Epub 2020 Sep 29.

Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.

In mammalian cells, inflammatory caspases detect Gram-negative bacterial invasion by binding lipopolysaccharides (LPS). Murine caspase-11 binds cytosolic LPS, stimulates pyroptotic cell death, and drives sepsis pathogenesis. Extracellular priming factors enhance caspase-11-dependent pyroptosis. Herein we compare priming agents and demonstrate that IFN priming elicits the most rapid and amplified macrophage response to cytosolic LPS. Previous studies indicate that IFN-induced expression of caspase-11 and guanylate binding proteins (GBPs) are causal events explaining the effects of priming on cytosolic LPS sensing. We demonstrate that these events cannot fully account for the increased response triggered by IFN treatment. Indeed, IFN priming elicits higher pyroptosis levels in response to cytosolic LPS when macrophages stably express caspase-11. In macrophages lacking GBPs encoded on chromosome 3, IFN priming enhanced pyroptosis in response to cytosolic LPS as compared with other priming agents. These results suggest an unknown regulator of caspase-11-dependent pyroptosis exists, whose activity is upregulated by IFN.
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http://dx.doi.org/10.1016/j.isci.2020.101612DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7566093PMC
October 2020

Genetic variation in the MacAB-TolC efflux pump influences pathogenesis of invasive Salmonella isolates from Africa.

PLoS Pathog 2020 08 24;16(8):e1008763. Epub 2020 Aug 24.

Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America.

The various sub-species of Salmonella enterica cause a range of disease in human hosts. The human-adapted Salmonella enterica serovar Typhi enters the gastrointestinal tract and invades systemic sites to cause enteric (typhoid) fever. In contrast, most non-typhoidal serovars of Salmonella are primarily restricted to gut tissues. Across Africa, invasive non-typhoidal Salmonella (iNTS) have emerged with an ability to spread beyond the gastrointestinal tract and cause systemic bloodstream infections with increased morbidity and mortality. To investigate this evolution in pathogenesis, we compared the genomes of African iNTS isolates with other Salmonella enterica serovar Typhimurium and identified several macA and macB gene variants unique to African iNTS. MacAB forms a tripartite efflux pump with TolC and is implicated in Salmonella pathogenesis. We show that macAB transcription is upregulated during macrophage infection and after antimicrobial peptide exposure, with macAB transcription being supported by the PhoP/Q two-component system. Constitutive expression of macAB improves survival of Salmonella in the presence of the antimicrobial peptide C18G. Furthermore, these macAB variants affect replication in macrophages and influence fitness during colonization of the murine gastrointestinal tract. Importantly, the infection outcome resulting from these macAB variants depends upon both the Salmonella Typhimurium genetic background and the host gene Nramp1, an important determinant of innate resistance to intracellular bacterial infection. The variations we have identified in the MacAB-TolC efflux pump in African iNTS may reflect evolution within human host populations that are compromised in their ability to clear intracellular Salmonella infections.
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http://dx.doi.org/10.1371/journal.ppat.1008763DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7446830PMC
August 2020

Salmonella-Driven Polarization of Granuloma Macrophages Antagonizes TNF-Mediated Pathogen Restriction during Persistent Infection.

Cell Host Microbe 2020 01 26;27(1):54-67.e5. Epub 2019 Dec 26.

Department of Microbiology and Immunology, Stanford University, Stanford, CA, USA. Electronic address:

Many intracellular bacteria can establish chronic infection and persist in tissues within granulomas composed of macrophages. Granuloma macrophages exhibit heterogeneous polarization states, or phenotypes, that may be functionally distinct. Here, we elucidate a host-pathogen interaction that controls granuloma macrophage polarization and long-term pathogen persistence during Salmonella Typhimurium (STm) infection. We show that STm persists within splenic granulomas that are densely populated by CD11bCD11cLy6C macrophages. STm preferentially persists in granuloma macrophages reprogrammed to an M2 state, in part through the activity of the effector SteE, which contributes to the establishment of persistent infection. We demonstrate that tumor necrosis factor (TNF) signaling limits M2 granuloma macrophage polarization, thereby restricting STm persistence. TNF neutralization shifts granuloma macrophages toward an M2 state and increases bacterial persistence, and these effects are partially dependent on SteE activity. Thus, manipulating granuloma macrophage polarization represents a strategy for intracellular bacteria to overcome host restriction during persistent infection.
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http://dx.doi.org/10.1016/j.chom.2019.11.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7065835PMC
January 2020

Drp1/Fis1 interaction mediates mitochondrial dysfunction in septic cardiomyopathy.

J Mol Cell Cardiol 2019 05 11;130:160-169. Epub 2019 Apr 11.

Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.

Mitochondrial dysfunction is a key contributor to septic cardiomyopathy. Although recent literature implicates dynamin related protein 1 (Drp1) and its mitochondrial adaptor fission 1 (Fis1) in the development of pathologic fission and mitochondrial failure in neurodegenerative disease, little is known about the role of Drp1/Fis1 interaction in the context of sepsis-induced cardiomyopathy. Our study tests the hypothesis that Drp1/Fis1 interaction is a major driver of sepsis-mediated pathologic fission, leading to mitochondrial dysfunction in the heart.

Methods: H9C2 cardiomyocytes were treated with lipopolysaccharide (LPS) to evaluate changes in mitochondrial membrane potential, oxidative stress, cellular respiration, and mitochondrial morphology. Balb/c mice were treated with LPS, cardiac function was measured by echocardiogaphy, and mitochondrial morphology determined by electron microscopy (EM). Drp1/Fis1 interaction was inhibited by P110 to determine whether limiting mitochondrial fission can reduce LPS-induced oxidative stress and cardiac dysfunction.

Results: LPS-treated H9C2 cardiomyocytes demonstrated a decrease in mitochondrial respiration followed by an increase in mitochondrial oxidative stress and a reduction in membrane potential. Inhibition of Drp1/Fis1 interaction with P110 attenuated LPS-mediated cellular oxidative stress and preserved membrane potential. In vivo, cardiac dysfunction in LPS-treated mice was associated with increased mitochondrial fragmentation. Treatment with P110 reduced cardiac mitochondrial fragmentation, prevented decline in cardiac function, and reduced mortality.

Conclusions: Sepsis decreases cardiac mitochondrial respiration and membrane potential while increasing oxidative stress and inducing pathologic fission. Treatment with P110 was protective in both in vitro and in vivo models of septic cardiomyopathy, suggesting a key role of Drp1/Fis1 interaction, and a potential target to reduce its morbidity and mortality.
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http://dx.doi.org/10.1016/j.yjmcc.2019.04.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6948926PMC
May 2019

Western diet regulates immune status and the response to LPS-driven sepsis independent of diet-associated microbiome.

Proc Natl Acad Sci U S A 2019 02 11;116(9):3688-3694. Epub 2019 Feb 11.

Department of Microbiology and Immunology, Stanford School of Medicine, Stanford University, Stanford, CA 94305;

Sepsis is a deleterious immune response to infection that leads to organ failure and is the 11th most common cause of death worldwide. Despite plaguing humanity for thousands of years, the host factors that regulate this immunological response and subsequent sepsis severity and outcome are not fully understood. Here we describe how the Western diet (WD), a diet high in fat and sucrose and low in fiber, found rampant in industrialized countries, leads to worse disease and poorer outcomes in an LPS-driven sepsis model in WD-fed mice compared with mice fed standard fiber-rich chow (SC). We find that WD-fed mice have higher baseline inflammation (metaflammation) and signs of sepsis-associated immunoparalysis compared with SC-fed mice. WD mice also have an increased frequency of neutrophils, some with an "aged" phenotype, in the blood during sepsis compared with SC mice. Importantly, we found that the WD-dependent increase in sepsis severity and higher mortality is independent of the microbiome, suggesting that the diet may be directly regulating the innate immune system through an unknown mechanism. Strikingly, we could predict LPS-driven sepsis outcome by tracking specific WD-dependent disease factors (e.g., hypothermia and frequency of neutrophils in the blood) during disease progression and recovery. We conclude that the WD is reprogramming the basal immune status and acute response to LPS-driven sepsis and that this correlates with alternative disease paths that lead to more severe disease and poorer outcomes.
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http://dx.doi.org/10.1073/pnas.1814273116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6397595PMC
February 2019

Legionella longbeachae Is Immunologically Silent and Highly Virulent In Vivo.

J Infect Dis 2017 Feb;215(3):440-451

Department of Cell Biology.

Background: Legionella longbeachae (Llo) and Legionella pneumophila (Lpn) are the most common pneumonia-causing agents of the genus. Although both species can be lethal to humans and are highly prevalent, little is known about the molecular pathogenesis of Llo infections. In murine models of infection, Lpn infection is self-limited, whereas Llo infection is lethal.

Methods: We used mouse macrophages, human macrophages, human epithelial cells, and mouse infections in vivo to evaluate multiple parameters of the infection.

Results: We determined that the Llo Dot/Icm secretion system is critical for virulence. Different than Lpn, Llo disseminates and the animals develop a severe pulmonary failure, as demonstrated by lung mechanics and blood oxygenation assays. As compared to Lpn, Llo is immunologically silent and fails to trigger the production of cytokines in human pulmonary epithelial cells and in mouse and human macrophages. Infections in Tnfr1-/-, Ifng-/-, and Il12p40-/- mice supported the participation of cytokines for the resistance phenotype.

Conclusions: Both Lpn and Llo require the Dot/Icm system for pathogenesis, but the infection outcome is strikingly different. Llo is immunologically silent, highly virulent, and lethal. The differences reported herein may reflect unappreciated clinical differences in patients infected with Lpn or Llo.
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http://dx.doi.org/10.1093/infdis/jiw560DOI Listing
February 2017

Murine Alveolar Macrophages Are Highly Susceptible to Replication of Coxiella burnetii Phase II In Vitro.

Infect Immun 2016 09 19;84(9):2439-48. Epub 2016 Aug 19.

Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo, FMRP/USP, Ribeirão Preto, São Paulo, Brazil

Coxiella burnetii is a Gram-negative bacterium that causes Q fever in humans. Q fever is an atypical pneumonia transmitted through inhalation of contaminated aerosols. In mammalian lungs, C. burnetii infects and replicates in several cell types, including alveolar macrophages (AMs). The innate immunity and signaling pathways operating during infection are still poorly understood, in part because of the lack of relevant host cell models for infection in vitro In the study described here, we investigated and characterized the infection of primary murine AMs by C. burnetii phase II in vitro Our data reveal that AMs show a pronounced M2 polarization and are highly permissive to C. burnetii multiplication in vitro Murine AMs present an increased susceptibility to infection in comparison to primary bone marrow-derived macrophages. AMs support more than 2 logs of bacterial replication during 12 days of infection in culture, similar to highly susceptible host cells, such as Vero and THP-1 cells. As a proof of principle that AMs are useful for investigation of C. burnetii replication, we performed experiments with AMs from Nos2(-/-) or Ifng(-/-) mice. In the absence of gamma interferon and nitric oxide synthase 2 (NOS2), AMs were significantly more permissive than wild-type cells. In contrast, AMs from Il4(-/-) mice were more restrictive to C. burnetii replication, supporting the importance of M2 polarization for the permissiveness of AMs to C. burnetii replication. Collectively, our data account for understanding the high susceptibility of alveolar macrophages to bacterial replication and support the use of AMs as a relevant model of C. burnetii growth in primary macrophages.
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http://dx.doi.org/10.1128/IAI.00411-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4995897PMC
September 2016

Inhibition of inflammasome activation by Coxiella burnetii type IV secretion system effector IcaA.

Nat Commun 2015 Dec 21;6:10205. Epub 2015 Dec 21.

Department of Cell Biology, Medical School of Ribeirão Preto, University of São Paulo (FMRP/USP), Ribeirão Preto, Sao Paulo 14049-900, Brazil.

Coxiella burnetii is a highly infectious bacterium that promotes its own replication in macrophages by inhibiting several host cell responses. Here, we show that C. burnetii inhibits caspase-1 activation in primary mouse macrophages. By using co-infection experiments, we determine that the infection of macrophages with C. burnetii inhibits the caspase-11-mediated non-canonical activation of the NLRP3 inflammasome induced by subsequent infection with Escherichia coli or Legionella pneumophila. Genetic screening using flagellin mutants of L. pneumophila as a surrogate host, reveals a novel C. burnetii gene (IcaA) involved in the inhibition of caspase activation. Expression of IcaA in L. pneumophila inhibited the caspase-11 activation in macrophages. Moreover, icaA(-) mutants of C. burnetii failed to suppress the caspase-11-mediated inflammasome activation induced by L. pneumophila. Our data reveal IcaA as a novel C. burnetii effector protein that is secreted by the Dot/Icm type IV secretion system and interferes with the caspase-11-induced, non-canonical activation of the inflammasome.
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http://dx.doi.org/10.1038/ncomms10205DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4703858PMC
December 2015

Cytosolic flagellin-induced lysosomal pathway regulates inflammasome-dependent and -independent macrophage responses.

Proc Natl Acad Sci U S A 2013 Aug 13;110(35):E3321-30. Epub 2013 Aug 13.

Departamento de Ciências Biológicas, Universidade Federal de São Paulo, CEP 04044-010, Sao Paulo, Brazil.

NAIP5/NLRC4 (neuronal apoptosis inhibitory protein 5/nucleotide oligomerization domain-like receptor family, caspase activation recruitment domain domain-containing 4) inflammasome activation by cytosolic flagellin results in caspase-1-mediated processing and secretion of IL-1β/IL-18 and pyroptosis, an inflammatory cell death pathway. Here, we found that although NLRC4, ASC, and caspase-1 are required for IL-1β secretion in response to cytosolic flagellin, cell death, nevertheless, occurs in the absence of these molecules. Cytosolic flagellin-induced inflammasome-independent cell death is accompanied by IL-1α secretion and is temporally correlated with the restriction of Salmonella Typhimurium infection. Despite displaying some apoptotic features, this peculiar form of cell death do not require caspase activation but is regulated by a lysosomal pathway, in which cathepsin B and cathepsin D play redundant roles. Moreover, cathepsin B contributes to NAIP5/NLRC4 inflammasome-induced pyroptosis and IL-1α and IL-1β production in response to cytosolic flagellin. Together, our data describe a pathway induced by cytosolic flagellin that induces a peculiar form of cell death and regulates inflammasome-mediated effector mechanisms of macrophages.
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http://dx.doi.org/10.1073/pnas.1305316110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3761566PMC
August 2013

Activation of NLRC4 by flagellated bacteria triggers caspase-1-dependent and -independent responses to restrict Legionella pneumophila replication in macrophages and in vivo.

J Immunol 2011 Dec 11;187(12):6447-55. Epub 2011 Nov 11.

Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil.

Although NLRC4/IPAF activation by flagellin has been extensively investigated, the downstream signaling pathways and the mechanisms responsible for infection clearance remain unclear. In this study, we used mice deficient for the inflammasome components in addition to wild-type (WT) Legionella pneumophila or bacteria deficient for flagellin (flaA) or motility (fliI) to assess the pathways responsible for NLRC4-dependent growth restriction in vivo and ex vivo. By comparing infections with WT L. pneumophila, fliI, and flaA, we found that flagellin and motility are important for the colonization of the protozoan host Acanthamoeba castellanii. However, in macrophages and mammalian lungs, flagellin expression abrogated bacterial replication. The flagellin-mediated growth restriction was dependent on NLRC4, and although it was recently demonstrated that NLRC4 is able to recognize bacteria independent of flagellin, we found that the NLRC4-dependent restriction of L. pneumophila multiplication was fully dependent on flagellin. By examining infected caspase-1(-/-) mice and macrophages with flaA, fliI, and WT L. pneumophila, we could detect greater replication of flaA, which suggests that caspase-1 only partially accounted for flagellin-dependent growth restriction. Conversely, WT L. pneumophila multiplied better in macrophages and mice deficient for NLRC4 compared with that in macrophages and mice deficient for caspase-1, supporting the existence of a novel caspase-1-independent response downstream of NLRC4. This response operated early after macrophage infection and accounted for the restriction of bacterial replication within bacteria-containing vacuoles. Collectively, our data indicate that flagellin is required for NLRC4-dependent responses to L. pneumophila and that NLRC4 triggers caspase-1-dependent and -independent responses for bacterial growth restriction in macrophages and in vivo.
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http://dx.doi.org/10.4049/jimmunol.1003784DOI Listing
December 2011

Innate immunity to legionella pneumophila.

Front Microbiol 2011 16;2:109. Epub 2011 May 16.

Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo Ribeirão Preto, SP, Brazil.

Innate immune cells, such as macrophages, are highly adapted to rapidly recognize infections by distinct pathogens, including viruses, bacteria, fungi, and protozoa. This recognition is mediated by pattern recognition receptors (PRRs), which are found in host cell surface membranes and the host cell cytoplasm. PRRs include protein families such as the toll-like receptors, nod-like receptors, RIG-I-like receptors, and sensors of cytosolic DNA. The activation of these PRRs by pathogen-associated molecular patterns leads to transcriptional responses and specific forms of cell death. These processes effectively contribute to host resistance to infection either via cell-autonomous processes that lead to the intracellular restriction of microbial replication and/or by activating pathogen-specific adaptive immune responses. Legionella pneumophila, the causative agent of Legionnaires' disease, is a Gram-negative bacterium that triggers responses by multiple PRRs. Here, we review a set of studies that have contributed to our specific understanding of the molecular mechanisms by which innate immune cells recognize and respond to L. pneumophila and the importance of these processes to the outcome of infection.
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http://dx.doi.org/10.3389/fmicb.2011.00109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3153058PMC
November 2011

A novel pathway for inducible nitric-oxide synthase activation through inflammasomes.

J Biol Chem 2010 Oct 11;285(42):32087-95. Epub 2010 Aug 11.

Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508-900, Brazil.

Innate immune recognition of flagellin is shared by transmembrane TLR5 and cytosolic Nlrc4 (NOD-like receptor family CARD (caspase activation recruitment domain) domain containing 4)/Naip5 (neuronal apoptosis inhibitory protein 5). TLR5 activates inflammatory genes through MYD88 pathway, whereas Nlrc4 and Naip5 assemble multiprotein complexes called inflammasomes, culminating in caspase-1 activation, IL-1β/IL-18 secretion, and pyroptosis. Although both TLR5 and Naip5/Nlrc4 pathways cooperate to clear infections, little is known about the relative anti-pathogen effector mechanisms operating through each of them. Here we show that the cytosolic flagellin (FLA-BSDot) was able to activate iNOS, an enzyme previously associated with TLR5 pathway. Using Nlrc4- or Naip5-deficient macrophages, we found that both receptors are involved in iNOS activation by FLA-BSDot. Moreover, distinct from extracellular flagellin (FLA-BS), iNOS activation by intracellular flagellin is completely abrogated in the absence of caspase-1. Interestingly, IL-1β and IL-18 do not seem to be important for FLA-BSDot-mediated iNOS production. Together, our data defined an additional anti-pathogen effector mechanism operated through Naip5 and Nlrc4 inflammasomes and illustrated a novel signaling transduction pathway that activates iNOS.
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http://dx.doi.org/10.1074/jbc.M110.124297DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2952210PMC
October 2010

Salmonella enterica serovar Typhimurium vaccine strains expressing a nontoxic Shiga-like toxin 2 derivative induce partial protective immunity to the toxin expressed by enterohemorrhagic Escherichia coli.

Clin Vaccine Immunol 2010 Apr 10;17(4):529-36. Epub 2010 Feb 10.

Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, 05508-000, Sao Paulo, SP, Brazil.

Shiga-like toxin 2 (Stx2)-producing enterohemorrhagic Escherichia coli (referred to as EHEC or STEC) strains are the primary etiologic agents of hemolytic-uremic syndrome (HUS), which leads to renal failure and high mortality rates. Expression of Stx2 is the most relevant virulence-associated factor of EHEC strains, and toxin neutralization by antigen-specific serum antibodies represents the main target for both preventive and therapeutic anti-HUS approaches. In the present report, we describe two Salmonella enterica serovar Typhimurium aroA vaccine strains expressing a nontoxic plasmid-encoded derivative of Stx2 (Stx2DeltaAB) containing the complete nontoxic A2 subunit and the receptor binding B subunit. The two S. Typhimurium strains differ in the expression of flagellin, the structural subunit of the flagellar shaft, which exerts strong adjuvant effects. The vaccine strains expressed Stx2DeltaAB, either cell bound or secreted into the extracellular environment, and showed enhanced mouse gut colonization and high plasmid stability under both in vitro and in vivo conditions. Oral immunization of mice with three doses of the S. Typhimurium vaccine strains elicited serum anti-Stx2B (IgG) antibodies that neutralized the toxic effects of the native toxin under in vitro conditions (Vero cells) and conferred partial protection under in vivo conditions. No significant differences with respect to gut colonization or the induction of antigen-specific antibody responses were detected in mice vaccinated with flagellated versus nonflagellated bacterial strains. The present results indicate that expression of Stx2DeltaAB by attenuated S. Typhimurium strains is an alternative vaccine approach for HUS control, but additional improvements in the immunogenicity of Stx2 toxoids are still required.
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http://dx.doi.org/10.1128/CVI.00495-09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2849334PMC
April 2010

CD8+ T cell adjuvant effects of Salmonella FliCd flagellin in live vaccine vectors or as purified protein.

Vaccine 2010 Feb 21;28(5):1373-82. Epub 2009 Nov 21.

Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1374, São Paulo, SP 05008-000, Brazil.

Salmonella flagellin, the flagellum structural subunit, has received particular interest as a vaccine adjuvant conferring enhanced immunogenity to soluble proteins or peptides, both for activation of antibody and cellular immune responses. In the present study, we evaluated the Salmonella enterica FliCd flagellin as a T cell vaccine adjuvant using as model the 9-mer (SYVPSAEQI) synthetic H2(d)-restricted CD8(+) T cell-specific epitope (CS(280-288)) derived from the Plasmodium yoelii circumsporozoite (CS) protein. The FliCd adjuvant effects were determined under two different conditions: (i) as recombinant flagella, expressed by orally delivered live S. Dublin vaccine strains expressing the target CS(280-288) peptide fused at the central hypervariable domain, and (ii) as purified protein in acellular vaccines in which flagellin was administered to mice either as a recombinant protein fused or admixed with the target CS(280-288) peptide. The results showed that CS(280-288)-specific cytotoxic CD8(+) T cells were primed when BALB/c mice were orally inoculated with the expressing the CS(280-288) epitope S. Dublin vaccine strain. In contrast, mice immunized with purified FliCd admixed with the CS(280-288) peptide and, to a lesser extent, fused with the target peptide developed specific cytotoxic CD8(+) T cell responses without the need of a heterologous booster immunization. The CD8(+) T cell adjuvant effects of flagellin, either fused or not with the target peptide, correlated with the in vivo activation of CD11c(+) dendritic cells. Taken together, the present results demonstrate that Salmonella flagellins are flexible adjuvant and induce adaptative immune responses when administered by different routes or vaccine formulations.
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http://dx.doi.org/10.1016/j.vaccine.2009.11.003DOI Listing
February 2010

Paracoccidioides brasiliensis vaccine formulations based on the gp43-derived P10 sequence and the Salmonella enterica FliC flagellin.

Infect Immun 2009 Apr 9;77(4):1700-7. Epub 2009 Feb 9.

Department of Microbiology-ICB, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP 05008-000, Brazil.

Paracoccidioidomycosis (PCM) is a systemic granulomatous disease caused by the dimorphic fungus Paracoccidioides brasiliensis. Anti-PCM vaccine formulations based on the secreted fungal cell wall protein (gp43) or the derived P10 sequence containing a CD4(+) T-cell-specific epitope have shown promising results. In the present study, we evaluated new anti-PCM vaccine formulations based on the intranasal administration of P. brasiliensis gp43 or the P10 peptide in combination with the Salmonella enterica FliC flagellin, an innate immunity agonist binding specifically to the Toll-like receptor 5, in a murine model. BALB/c mice immunized with gp43 developed high-specific-serum immunoglobulin G1 responses and enhanced interleukin-4 (IL-4) and IL-10 levels. On the other hand, mice immunized with recombinant purified flagellins genetically fused with P10 at the central hypervariable domain, either flanked or not by two lysine residues, or the synthetic P10 peptide admixed with purified FliC elicited a prevailing Th1-type immune response based on lung cell-secreted type 1 cytokines. Mice immunized with gp43 and FliC and intratracheally challenged with P. brasiliensis yeast cells had increased fungal proliferation and lung tissue damage. In contrast, mice immunized with the chimeric flagellins and particularly those immunized with P10 admixed with FliC reduced P. brasiliensis growth and lung damage. Altogether, these results indicate that S. enterica FliC flagellin modulates the immune response to P. brasiliensis P10 antigen and represents a promising alternative for the generation of anti-PCM vaccines.
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http://dx.doi.org/10.1128/IAI.01470-08DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663153PMC
April 2009

Cytotoxic T cell adjuvant effects of three Salmonella enterica flagellins.

Braz J Microbiol 2008 Jan 1;39(1):44-9. Epub 2008 Mar 1.

Departmento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo , São Paulo, SP , Brasil.

Bacterial flagellins are important virulence-associated factors and strong inducers of inflammatory responses in mammalian hosts. Flagellins have also been investigated as potential vaccine adjuvants, either for induction of humoral or cellular immune responses, to different target antigens. In this study we investigated the adjuvant properties of three Salmonella enterica flagellins types (FliCd, FliCi and FljB) to an ovalbumin-derived CD8(+) T cell-restricted epitope (OVA257-264). Although mice immunized with the three tested flagellins elicited antigen-specific activated CD8(+) T cells, only animals immunized with FliCi and FliCd flagellins admixed with ovalbumin mounted specific in vivo cytotoxic responses to peptide-pulsed target cells. The present results indicate that Salmonella flagellins are endowed with type-specific adjuvant effects toward murine CD8(+) T cells, a feature that may impact their use as adjuvants for prophylatic or therapeutic vaccines.
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http://dx.doi.org/10.1590/S1517-838220080001000011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768349PMC
January 2008