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1.
PLoS Pathog ; 20(1): e1011280, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38271464

ABSTRACT

Subverting the host immune response to inhibit inflammation is a key virulence strategy of Yersinia pestis. The inflammatory cascade is tightly controlled via the sequential action of lipid and protein mediators of inflammation. Because delayed inflammation is essential for Y. pestis to cause lethal infection, defining the Y. pestis mechanisms to manipulate the inflammatory cascade is necessary to understand this pathogen's virulence. While previous studies have established that Y. pestis actively inhibits the expression of host proteins that mediate inflammation, there is currently a gap in our understanding of the inflammatory lipid mediator response during plague. Here we used the murine model to define the kinetics of the synthesis of leukotriene B4 (LTB4), a pro-inflammatory lipid chemoattractant and immune cell activator, within the lungs during pneumonic plague. Furthermore, we demonstrated that exogenous administration of LTB4 prior to infection limited bacterial proliferation, suggesting that the absence of LTB4 synthesis during plague contributes to Y. pestis immune evasion. Using primary leukocytes from mice and humans further revealed that Y. pestis actively inhibits the synthesis of LTB4. Finally, using Y. pestis mutants in the Ysc type 3 secretion system (T3SS) and Yersinia outer protein (Yop) effectors, we demonstrate that leukocytes recognize the T3SS to initiate the rapid synthesis of LTB4. However, several Yop effectors secreted through the T3SS effectively inhibit this host response. Together, these data demonstrate that Y. pestis actively inhibits the synthesis of the inflammatory lipid LTB4 contributing to the delay in the inflammatory cascade required for rapid recruitment of leukocytes to sites of infection.


Subject(s)
Plague , Yersinia pestis , Humans , Animals , Mice , Yersinia pestis/metabolism , Plague/microbiology , Type III Secretion Systems/metabolism , Leukotriene B4/metabolism , Leukocytes/metabolism , Inflammation , Bacterial Proteins/metabolism
2.
mBio ; 14(3): e0065823, 2023 06 27.
Article in English | MEDLINE | ID: mdl-37042761

ABSTRACT

Pathogenic microbial ecosystems are often polymicrobial, and interbacterial interactions drive emergent properties of these communities. In the oral cavity, Streptococcus gordonii is a foundational species in the development of plaque biofilms, which can contribute to periodontal disease and, after gaining access to the bloodstream, target remote sites such as heart valves. Here, we used a transposon sequencing (Tn-Seq) library of S. gordonii to identify genes that influence fitness in a murine abscess model, both as a monoinfection and as a coinfection with an oral partner species, Porphyromonas gingivalis. In the context of a monoinfection, conditionally essential genes were widely distributed among functional pathways. Coinfection with P. gingivalis almost completely changed the nature of in vivo gene essentiality. Community-dependent essential (CoDE) genes under the coinfection condition were primarily related to DNA replication, transcription, and translation, indicating that robust growth and replication are required to survive with P. gingivalis in vivo. Interestingly, a group of genes in an operon encoding streptococcal receptor polysaccharide (RPS) were associated with decreased fitness of S. gordonii in a coinfection with P. gingivalis. Individual deletion of two of these genes (SGO_2020 and SGO_2024) resulted in the loss of RPS production by S. gordonii and increased susceptibility to killing by neutrophils. P. gingivalis protected the RPS mutants by inhibiting neutrophil recruitment, degranulation, and neutrophil extracellular trap (NET) formation. These results provide insight into genes and functions that are important for S. gordonii survival in vivo and the nature of polymicrobial synergy with P. gingivalis. Furthermore, we show that RPS-mediated immune protection in S. gordonii is dispensable and detrimental in the presence of a synergistic partner species that can interfere with neutrophil killing mechanisms. IMPORTANCE Bacteria responsible for diseases originating at oral mucosal membranes assemble into polymicrobial communities. However, we know little regarding the fitness determinants of the organisms that initiate community formation. Here, we show that the extracellular polysaccharide of Streptococcus gordonii, while important for streptococcal survival as a monoinfection, is detrimental to survival in the context of a coinfection with Porphyromonas gingivalis. We found that the presence of P. gingivalis compensates for immune protective functions of extracellular polysaccharide, rendering production unnecessary. The results show that fitness determinants of bacteria in communities differ substantially from those of individual species in isolation. Furthermore, constituents of communities can undertake activities that relieve the burden of energetically costly biosynthetic reactions on partner species.


Subject(s)
Coinfection , Streptococcus gordonii , Animals , Mice , Streptococcus gordonii/genetics , Coinfection/microbiology , Ecosystem , Biofilms , Mouth
3.
Infect Immun ; 91(2): e0031922, 2023 02 16.
Article in English | MEDLINE | ID: mdl-36648232

ABSTRACT

Increased prevalence and abundance of Selenomonas sputigena have been associated with periodontitis, a chronic inflammatory disease of tooth-supporting tissues, for more than 50 years. Over the past decade, molecular surveys of periodontal disease using 16S and shotgun metagenomic sequencing approaches have confirmed the disease association of classically recognized periodontal pathogens such as Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia while highlighting previously underappreciated organisms such as Filifactor alocis and S. sputigena. Despite abundant clinical association between S. sputigena and periodontal disease, we have little to no understanding of its pathogenic potential, and virulence mechanisms have not been studied. In this study, we sought to characterize the response of gingival epithelial cells to infection with S. sputigena. Here, we show that S. sputigena attaches to gingival keratinocytes and induces expression and secretion of cytokines and chemokines associated with inflammation and leukocyte recruitment. We demonstrate that S. sputigena induces signaling through Toll-like receptor 2 (TLR2) and TLR4 but evades activation of TLR5. Cytokines released from S. sputigena-infected keratinocytes induced monocyte and neutrophil chemotaxis. These results show that S. sputigena-host interactions have the potential to contribute to bacterially driven inflammation and tissue destruction, the hallmark of periodontitis. Characterization of previously unstudied pathogens may provide novel approaches to develop therapeutics to treat or prevent periodontal disease.


Subject(s)
Periodontal Diseases , Periodontitis , Humans , Inflammation , Periodontitis/pathology , Porphyromonas gingivalis/metabolism , Cytokines/metabolism , Epithelial Cells/metabolism
4.
Immunol Rev ; 314(1): 93-110, 2023 03.
Article in English | MEDLINE | ID: mdl-36271881

ABSTRACT

Neutrophils are of key importance in periodontal health and disease. In their absence or when they are functionally defective, as occurs in certain congenital disorders, affected individuals develop severe forms of periodontitis in early age. These observations imply that the presence of immune-competent neutrophils is essential to homeostasis. However, the presence of supernumerary or hyper-responsive neutrophils, either because of systemic priming or innate immune training, leads to imbalanced host-microbe interactions in the periodontium that culminate in dysbiosis and inflammatory tissue breakdown. These disease-provoking imbalanced interactions are further exacerbated by periodontal pathogens capable of subverting neutrophil responses to their microbial community's benefit and the host's detriment. This review attempts a synthesis of these findings for an integrated view of the neutrophils' ambivalent role in periodontal disease and, moreover, discusses how some of these concepts underpin the development of novel therapeutic approaches to treat periodontal disease.


Subject(s)
Neutrophils , Periodontitis , Humans , Inflammation , Periodontium , Homeostasis
5.
J Clin Periodontol ; 50(1): 121-130, 2023 01.
Article in English | MEDLINE | ID: mdl-36122937

ABSTRACT

AIM: Filifactor alocis has recently emerged as a periodontal pathobiont that appears to thrive in the oral cavity of smokers. We hypothesized that identification of smoke-responsive F. alocis genes would provide insight into adaptive strategies and that cigarette smoke would enhance F. alocis pathogenesis in vivo. MATERIALS AND METHODS: F. alocis was grown in vitro and cigarette smoke extract-responsive genes determined by RNAseq. Mice were exposed, or not, to mainstream 1R6F research cigarette smoke and infected with F. alocis, or not, in an acute ligature model of periodontitis. Key clinical, infectious, and immune data were collected. RESULTS: In culture, F. alocis growth was unaffected by smoke conditioning and only a small number of genes were specifically regulated by smoke exposure. Reduced murine mass, differences in F. alocis-cognizant antibody production, and altered immune profiles as well as altered alveolar bone loss were all attributable to smoke exposure and/or F. alocis infection in vivo. CONCLUSIONS: F. alocis is well-adapted to tobacco-rich conditions and its pathogenesis is enhanced by tobacco smoke exposure. A smoke-exposed ligature model of periodontitis shows promise as a tool with which to further unravel mechanisms underlying tobacco-enhanced, bacteria-induced disease.


Subject(s)
Periodontitis , Tobacco Smoke Pollution , Mice , Animals , Virulence , Clostridiales , Periodontitis/etiology
6.
Front Oral Health ; 3: 981343, 2022.
Article in English | MEDLINE | ID: mdl-36046121

ABSTRACT

Periodontitis is a dysbiotic disease caused by the interplay between the microbial ecosystem present in the disease with the dysregulated host immune response. The disease-associated microbial community is formed by the presence of established oral pathogens like Aggregatibacter actinomycetemcomitans as well as by newly dominant species like Filifactor alocis. These two oral pathogens prevail and grow within the periodontal pocket which highlights their ability to evade the host immune response. This review focuses on the virulence factors and potential pathogenicity of both oral pathogens in periodontitis, accentuating the recent description of F. alocis virulence factors, including the presence of an exotoxin, and comparing them with the defined factors associated with A. actinomycetemcomitans. In the disease setting, possible synergistic and/or mutualistic interactions among both oral pathogens might contribute to disease progression.

7.
Front Allergy ; 3: 980515, 2022.
Article in English | MEDLINE | ID: mdl-36092279

ABSTRACT

Background: Allergic rhinitis (AR) affects up to 40% of the general population, there are large-scale multicenter studies that have described its characteristics and few studies have focused on studying patients with AR in Latin America (LA). Methodology: A cross-sectional, descriptive, multicenter study was carried out in four LA countries (Colombia, Argentina, Cuba and Peru). Patients diagnosed with AR between November 2017 and June 2020 were included. Sociodemographic and clinical data, sensitization profile and current treatment were collected in the Electronic Data Collection (BDClinic). Patients also filled out this questionnaires: Rhinitis Control Assessment Test (RCAT), Reflexive Total Nasal Symptom Score (rTNSS), Modified ARIA Criteria for AR Severity (mARIA) and ESPRINT-15. Risk of bias was examined by applying the STROBE checklist. Results: The study included 412 patients. Median age was 25 years (15-39). Two hundred and twenty four (54.3%) were women. Nasal obstruction was present in 303 (73.5%). Three hundred and thirty four (81%) had a persistent AR. One hundred and twenty one (31.3%) had associated asthma. The most frequently positive skin tests were: Dermatophagoides pteronyssinus in 365 (88.6%) and Dermatophagoides farinae in 331 (81.3%). Four hundred and eleven patients (99%) reported that AR affected their quality of life. The median score of ESPRINT-15 was 1.87 (0.93-2.93), The mean values of RCAT and rTNSS were 19.01 (±4.59) and 5.4 (±2.97) respectively. Two hundred and fifty (60%) were receiving only oral antihistamines. Physicians decided to start nasal corticosteroids in 296 (71.8%). Only seventy patients (16.9%) were receiving immunotherapy. Conclusion: These findings confirm that most of patients with AR in LA have a persistent disease with a negative impact on quality of life. Dust mites are the main sensitizers. These findings will allow to know the true impact of AR and can lead to a better disease management.

8.
Front Immunol ; 13: 879686, 2022.
Article in English | MEDLINE | ID: mdl-35711435

ABSTRACT

Neutrophils play a significant role in determining disease severity following SARS-CoV-2 infection. Gene and protein expression defines several neutrophil clusters in COVID-19, including the emergence of low density neutrophils (LDN) that are associated with severe disease. The functional capabilities of these neutrophil clusters and correlation with gene and protein expression are unknown. To define host defense and immunosuppressive functions of normal density neutrophils (NDN) and LDN from COVID-19 patients, we recruited 64 patients with severe COVID-19 and 26 healthy donors (HD). Phagocytosis, respiratory burst activity, degranulation, neutrophil extracellular trap (NET) formation, and T-cell suppression in those neutrophil subsets were measured. NDN from severe/critical COVID-19 patients showed evidence of priming with enhanced phagocytosis, respiratory burst activity, and degranulation of secretory vesicles and gelatinase and specific granules, while NET formation was similar to HD NDN. COVID LDN response was impaired except for enhanced NET formation. A subset of COVID LDN with intermediate CD16 expression (CD16Int LDN) promoted T cell proliferation to a level similar to HD NDN, while COVID NDN and the CD16Hi LDN failed to stimulate T-cell activation. All 3 COVID-19 neutrophil populations suppressed stimulation of IFN-γ production, compared to HD NDN. We conclude that NDN and LDN from COVID-19 patients possess complementary functional capabilities that may act cooperatively to determine disease severity. We predict that global neutrophil responses that induce COVID-19 ARDS will vary depending on the proportion of neutrophil subsets.


Subject(s)
COVID-19 , Extracellular Traps , Extracellular Traps/metabolism , Humans , Neutrophils/metabolism , Respiratory Burst , SARS-CoV-2
9.
Mol Microbiol ; 117(6): 1340-1351, 2022 06.
Article in English | MEDLINE | ID: mdl-35437843

ABSTRACT

Periodontitis is a chronic inflammatory infectious disease that affects the integrity of tooth-supporting tissues and has adverse systemic consequences. Advances in sequencing technologies have uncovered organisms that are exclusively found in high numbers in periodontal lesions, such as the gram-positive anaerobic rod, Filifactor alocis. F. alocis can manipulate neutrophil effector functions, which allows the organism to survive within these granulocytes. Several neutrophil functions have been tested in the context of F. alocis challenge, but the effect of the organism on neutrophil apoptosis is still unknown. RNA sequencing of human neutrophils challenged with F. alocis showed that apoptosis pathways were differentially regulated. Compared to media-cultured controls, F. alocis-challenged neutrophils maintain their nuclear morphology, do not stain for Annexin V or 7-AAD, and have decreased DNA fragmentation. Inhibition of apoptosis by F. alocis involved reduced caspase-3, -8, and - 9 activation and upregulation of important anti-apoptotic proteins. Prolonged lifespan was dependent on contact through TLR2/6, and F. alocis-challenged neutrophils retained their functional capacity to induce inflammation for longer timepoints. This is the first in-depth characterization of neutrophil apoptotic programs in response to an oral pathogen and provides key information on how bacteria manipulate immune cell mechanisms to maintain a dysregulated inflammatory response.


Subject(s)
Neutrophils , Periodontitis , Clostridiales , Humans , Longevity , Neutrophils/microbiology , Periodontitis/microbiology
10.
J Clin Med ; 11(5)2022 Mar 05.
Article in English | MEDLINE | ID: mdl-35268530

ABSTRACT

BACKGROUND: Macrophage scavenger receptor 1 (MSR1) has mostly been described in macrophages, but we previously found a significant gene expression increase in peripheral blood mononuclear cells (PBMCs) of asthmatic patients. OBJECTIVE: To confirm those results and to define its cellular origin in PBMCs. METHODS: Four groups of subjects were studied: healthy controls (C), nonallergic asthmatic (NA), allergic asthmatic (AA), and chronic obstructive pulmonary disease (COPD) patients. RNA was extracted from PBMCs. MSR1 gene expression was analyzed by RT-qPCR. The presence of MSR1 on the cellular surface of PBMC cellular subtypes was analyzed by confocal microscopy and flow cytometry. RESULTS: MSR1 gene expression was significantly increased in the three clinical conditions compared to the healthy control group, with substantial variations according to disease type and severity. MSR1 expression on T cells (CD4+ and CD8+), B cells, and monocytes was confirmed by confocal microscopy and flow cytometry. In all clinical groups, the four immune cell subtypes studied expressed MSR1, with a greater expression on B lymphocytes and monocytes, exhibiting differences according to disease and severity. CONCLUSIONS: This is the first description of MSR1's presence on lymphocytes' surfaces and reinforces the potential role of MSR1 as a player in asthma and COPD.

11.
Front Immunol ; 12: 707096, 2021.
Article in English | MEDLINE | ID: mdl-34456916

ABSTRACT

Aggregatibacter actinomycetemcomitans is a gram-negative facultative anaerobe and an opportunistic oral pathogen, strongly associated with periodontitis and other inflammatory diseases. Periodontitis is a chronic inflammation of the periodontium resulting from the inflammatory response of the host towards the dysbiotic microbial community present at the gingival crevice. Previously, our group identified catecholamines and iron as the signals that activate the QseBC two-component system in A. actinomycetemcomitans, necessary for the organism to acquire iron as a nutrient to survive in the anaerobic environment. However, the source of catecholamines has not been identified. It has been reported that mouse neutrophils can release catecholamines. In periodontitis, large infiltration of neutrophils is found at the subgingival pocket; hence, we wanted to test the hypothesis that A. actinomycetemcomitans exploits human neutrophils as a source for catecholamines. In the present study, we showed that human neutrophils synthesize, store, and release epinephrine, one of the three main types of catecholamines. Human neutrophil challenge with A. actinomycetemcomitans induced exocytosis of neutrophil granule subtypes: secretory vesicles, specific granules, gelatinase granules, and azurophilic granules. In addition, by selectively inhibiting granule exocytosis, we present the first evidence that epinephrine is stored in azurophilic granules. Using QseC mutants, we showed that the periplasmic domain of the QseC sensor kinase is required for the interaction between A. actinomycetemcomitans and epinephrine. Finally, epinephrine-containing supernatants collected from human neutrophils promoted A. actinomycetemcomitans growth and induced the expression of the qseBC operon under anaerobic conditions. Based on our findings, we propose that A. actinomycetemcomitans promotes azurophilic granule exocytosis by neutrophils as an epinephrine source to promote bacterial survival.


Subject(s)
Aggregatibacter actinomycetemcomitans/metabolism , Epinephrine/metabolism , Neutrophils/metabolism , Pasteurellaceae Infections/metabolism , Periodontitis/microbiology , Cell Survival/physiology , Humans
12.
mBio ; 12(3): e0100821, 2021 06 29.
Article in English | MEDLINE | ID: mdl-34076467

ABSTRACT

The Dot/Icm type IV secretion system (T4SS) of Legionella pneumophila is essential for lysosomal evasion and permissiveness of macrophages for intracellular proliferation of the pathogen. In contrast, we show that polymorphonuclear cells (PMNs) respond to a functional Dot/Icm system through rapid restriction of L. pneumophila. Specifically, we show that the L. pneumophila T4SS-injected amylase (LamA) effector catalyzes rapid glycogen degradation in the PMNs cytosol, leading to cytosolic hyperglucose. Neutrophils respond through immunometabolic reprogramming that includes upregulated aerobic glycolysis. The PMNs become activated with spatial generation of intracellular reactive oxygen species within the Legionella-containing phagosome (LCP) and fusion of specific and azurophilic granules to the LCP, leading to rapid restriction of L. pneumophila. We conclude that in contrast to macrophages, PMNs respond to a functional Dot/Icm system, and specifically to the effect of the injected amylase effector, through rapid engagement of major microbicidal processes and rapid restriction of the pathogen. IMPORTANCE Legionella pneumophila is commonly found in aquatic environments and resides within a wide variety of amoebal hosts. Upon aerosol transmission to humans, L. pneumophila invades and replicates with alveolar macrophages, causing pneumonia designated Legionnaires' disease. In addition to alveolar macrophages, neutrophils infiltrate into the lungs of infected patients. Unlike alveolar macrophages, neutrophils restrict and kill L. pneumophila, but the mechanisms were previously unclear. Here, we show that the pathogen secretes an amylase (LamA) enzyme that rapidly breakdowns glycogen stores within neutrophils, and this triggers increased glycolysis. Subsequently, the two major killing mechanisms of neutrophils, granule fusion and production of reactive oxygen species, are activated, resulting in rapid killing of L. pneumophila.


Subject(s)
Legionella pneumophila/immunology , Neutrophils/microbiology , Type IV Secretion Systems/immunology , Bacterial Proteins/metabolism , Cytosol/microbiology , Glycogen/metabolism , Glycolysis , Humans , Legionella pneumophila/genetics , Legionella pneumophila/metabolism , Legionnaires' Disease/microbiology , Phagosomes/immunology , Phagosomes/microbiology , Reactive Oxygen Species/immunology , Type IV Secretion Systems/genetics
13.
JCI Insight ; 6(9)2021 05 10.
Article in English | MEDLINE | ID: mdl-33986193

ABSTRACT

SARS coronavirus 2 (SARS-CoV-2) is a novel viral pathogen that causes a clinical disease called coronavirus disease 2019 (COVID-19). Although most COVID-19 cases are asymptomatic or involve mild upper respiratory tract symptoms, a significant number of patients develop severe or critical disease. Patients with severe COVID-19 commonly present with viral pneumonia that may progress to life-threatening acute respiratory distress syndrome (ARDS). Patients with COVID-19 are also predisposed to venous and arterial thromboses that are associated with a poorer prognosis. The present study identified the emergence of a low-density inflammatory neutrophil (LDN) population expressing intermediate levels of CD16 (CD16Int) in patients with COVID-19. These cells demonstrated proinflammatory gene signatures, activated platelets, spontaneously formed neutrophil extracellular traps, and enhanced phagocytic capacity and cytokine production. Strikingly, CD16Int neutrophils were also the major immune cells within the bronchoalveolar lavage fluid, exhibiting increased CXCR3 but loss of CD44 and CD38 expression. The percentage of circulating CD16Int LDNs was associated with D-dimer, ferritin, and systemic IL-6 and TNF-α levels and changed over time with altered disease status. Our data suggest that the CD16Int LDN subset contributes to COVID-19-associated coagulopathy, systemic inflammation, and ARDS. The frequency of that LDN subset in the circulation could serve as an adjunct clinical marker to monitor disease status and progression.


Subject(s)
Blood Coagulation Disorders/blood , Blood Coagulation Disorders/etiology , COVID-19/blood , COVID-19/complications , Neutrophils/immunology , SARS-CoV-2 , Adult , Aged , Aged, 80 and over , Biomarkers/blood , Blood Coagulation Disorders/immunology , COVID-19/immunology , Cytokines/blood , Female , GPI-Linked Proteins/blood , Hospitalization , Humans , Inflammation Mediators/blood , Male , Middle Aged , Neutrophils/classification , Pandemics , Phagocytosis , Platelet Activation , Receptors, IgG/blood , Respiratory Distress Syndrome/blood , Respiratory Distress Syndrome/etiology , Respiratory Distress Syndrome/immunology , Severity of Illness Index
14.
Mol Oral Microbiol ; 36(2): 103-120, 2021 04.
Article in English | MEDLINE | ID: mdl-33128827

ABSTRACT

Periodontitis is an irreversible, chronic inflammatory disease where inflammophilic pathogenic microbial communities accumulate in the gingival crevice. Neutrophils are a major component of the innate host response against bacterial challenge, and under homeostatic conditions, their microbicidal functions typically protect the host against periodontitis. However, a number of periodontal pathogens developed survival strategies to evade neutrophil microbicidal functions while promoting inflammation, which provides a source of nutrients for bacterial growth. Research on periodontal pathogens has largely focused on a few established species: Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis. However, advances in culture-independent techniques have facilitated the identification of new bacterial species in periodontal lesions, such as the two Gram-positive anaerobes, Filifactor alocis and Peptoanaerobacter stomatis, whose characterization of pathogenic potential has not been fully described. Additionally, there is not a full understanding of the pathogenic mechanisms used against neutrophils by organisms that are abundant in periodontal lesions. This presents a substantial barrier to the development of new approaches to prevent or ameliorate the disease. In this review, we first summarize the neutrophil functions affected by the established periodontal pathogens listed above, denoting unknown areas that still merit a closer look. Then, we review the literature on neutrophil functions and the emerging periodontal pathogens, F. alocis and P. stomatis, comparing the effects of the emerging microbes to that of established pathogens, and speculate on the contribution of these putative pathogens to the progression of periodontal disease.


Subject(s)
Clostridiales , Neutrophils , Aggregatibacter actinomycetemcomitans , Humans , Inflammation , Porphyromonas gingivalis , Treponema denticola
15.
FASEB J ; 34(7): 9120-9140, 2020 07.
Article in English | MEDLINE | ID: mdl-32433819

ABSTRACT

Homeostasis between pro- and anti- inflammatory responses induced by bacteria is critical for the maintenance of health. In the oral cavity, pro-inflammatory mechanisms induced by pathogenic bacteria are well-established; however, the anti-inflammatory responses that act to restrain innate responses remain poorly characterized. Here, we demonstrate that infection with the periodontal pathogen Porphyromonas gingivalis enhances the activity of Janus kinase 3 (JAK3) in innate immune cells, and subsequently phospho-inactivates Nedd4-2, an ubiquitin E3 ligase. In turn, Wingless-INT (Wnt) 3 (Wnt3) ubiquitination is decreased, while total protein levels are enhanced, leading to a reduction in pro-inflammatory cytokine levels. In contrast, JAK3 or Wnt3a inhibition robustly enhances nuclear factor kappa-light-chain-enhancer of activated B cells activity and the production of pro-inflammatory cytokines in P. gingivalis-stimulated innate immune cells. Moreover, using gain- and loss-of-function approaches, we demonstrate that downstream molecules of Wnt3a signaling, including Dvl3 and ß-catenin, are responsible for the negative regulatory role of Wnt3a. In addition, using an in vivo P. gingivalis-mediated periodontal disease model, we show that JAK3 inhibition enhances infiltration of inflammatory cells, reduces expression of Wnt3a and Dvl3 in P. gingivalis-infected gingival tissues, and increases disease severity. Together, our results reveal a new anti-inflammatory role for JAK3 in innate immune cells and show that the underlying signaling pathway involves Nedd4-2-mediated Wnt3a ubiquitination.


Subject(s)
Bacteroidaceae Infections/complications , Bone Resorption/prevention & control , Inflammation/prevention & control , Janus Kinase 3/metabolism , Periodontal Diseases/prevention & control , Protective Agents , Wnt3A Protein/metabolism , Animals , Bacteroidaceae Infections/microbiology , Bone Resorption/etiology , Bone Resorption/metabolism , Bone Resorption/pathology , Inflammation/etiology , Inflammation/metabolism , Inflammation/pathology , Janus Kinase 3/genetics , Mice , Mice, Inbred C57BL , Periodontal Diseases/etiology , Periodontal Diseases/metabolism , Periodontal Diseases/pathology , Porphyromonas gingivalis/pathogenicity , Signal Transduction , Wnt3A Protein/genetics
16.
Front Immunol ; 11: 497, 2020.
Article in English | MEDLINE | ID: mdl-32373107

ABSTRACT

Periodontitis is an irreversible, bacteria-induced, chronic inflammatory disease that compromises the integrity of tooth-supporting tissues and adversely affects systemic health. As the immune system's first line of defense against bacteria, neutrophils use their microbicidal functions in the oral cavity to protect the host against periodontal disease. However, periodontal pathogens have adapted to resist neutrophil microbicidal mechanisms while still propagating inflammation, which provides essential nutrients for the bacteria to proliferate and cause disease. Advances in sequencing technologies have recognized several newly appreciated bacteria associated with periodontal lesions such as the Gram-positive anaerobic rod, Filifactor alocis. With the discovery of these oral bacterial species, there is also a growing need to assess their pathogenic potential and determine their contribution to disease progression. Currently, few studies have addressed the pathogenic mechanisms used by oral bacteria to manipulate the neutrophil functional responses at the level of the transcriptome. Thus, this study aims to characterize the global changes at the gene expression level in human neutrophils during infection with F. alocis. Our results indicate that the challenge of human neutrophils with F. alocis results in the differential expression of genes involved in multiple neutrophil effector functions such as chemotaxis, cytokine and chemokine signaling pathways, and apoptosis. Moreover, F. alocis challenges affected the expression of components from the TNF and MAPK kinase signaling pathways. This resulted in transient, dampened p38 MAPK activation by secondary stimuli TNFα but not by fMLF. Functionally, the F. alocis-mediated inhibition of p38 activation by TNFα resulted in decreased cytokine production but had no effect on the priming of the respiratory burst response or the delay of apoptosis by TNFα. Since the modulatory effect was characteristic of viable F. alocis only, we propose this as one of F. alocis' mechanisms to control neutrophils and their functional responses.


Subject(s)
Clostridiales/immunology , Neutrophils/physiology , Periodontitis/immunology , Enzyme Activation , Extracellular Signal-Regulated MAP Kinases/metabolism , Gene Expression Profiling , Humans , Respiratory Burst , Signal Transduction , Tumor Necrosis Factor-alpha/metabolism
17.
Pathogens ; 9(2)2020 Feb 15.
Article in English | MEDLINE | ID: mdl-32075233

ABSTRACT

Mycobacterium smegmatis rarely causes disease in the immunocompetent, but reported cases of soft tissue infection describe abscess formation requiring surgical debridement for resolution. Neutrophils are the first innate immune cells to accumulate at sites of bacterial infection, where reactive oxygen species and proteolytic enzymes are used to kill microbial invaders. As these phagocytic cells play central roles in protection from most bacteria, we assessed human neutrophil phagocytosis and granule exocytosis in response to serum opsonized or non-opsonized M. smegmatis mc2. Although phagocytosis was enhanced by serum opsonization, M. smegmatis did not induce exocytosis of secretory vesicles or azurophilic granules at any time point tested, with or without serum opsonization. At early time points, opsonized M. smegmatis induced significant gelatinase granule exocytosis compared to non-opsonized bacteria. Differences in granule release between opsonized and non-opsonized M. smegmatis decreased in magnitude over the time course examined, with bacteria also evoking specific granule exocytosis by six hours after addition to cultured primary single-donor human neutrophils. Supernatants from neutrophils challenged with opsonized M. smegmatis were able to digest gelatin, suggesting that complement and gelatinase granule exocytosis can contribute to neutrophil-mediated tissue damage seen in these rare soft tissue infections.

18.
Mol Immunol ; 118: 153-164, 2020 02.
Article in English | MEDLINE | ID: mdl-31884387

ABSTRACT

BACKGROUND: Accumulating evidence suggests a regulatory role of Wnt proteins in innate immune responses. However, the effects of Wnt3a signaling on TLR4-mediated inflammatory responses are controversial and the signaling crosstalk between TLR4 and Wnt3a remains uncertain. METHODS: Gain- and Loss- of function approaches were utilized to determine the function of Wnt3a signaling in TLR4-mediated inflammatory responses. Cytokine production at protein and mRNA levels and phosphorylation of signaling molecules were measured by ELISA, qRT-PCR, and Western Blot, respectively. Endotoxemia mouse model was employed to assess the effect of Wnt3a on systemic inflammatory cytokine levels and neutrophil infiltration. RESULTS: LPS stimulation leads to an increase of Wnt3a expression and its downstream molecule, Dvl3, in primary monocytes. Inhibition or silence of Wnt3a or Dvl3 significantly increases the production of pro-inflammatory cytokines (IL-12, IL-6, TNFα), robustly reduces ß-catenin accumulation, and enhances the phosphorylation of NF-κB P65 and its DNA binding activity. These results were confirmed by multiple gain- and loss- of function approaches including specific siRNA and ectopic expression of Dvl3, GSK3ß, and ß-catenin in monocytes. Moreover, in vivo relevance was established in a murine endotoxin model, in which Wnt3a inhibition enhances the inflammatory responses by augmenting the systemic pro-inflammatory cytokine levels and neutrophil infiltration. CONCLUSIONS: TLR4 activation promotes Wnt3a-Dvl3 signaling, which acts as rheostats to restrain the intensity of inflammation through regulating GSK3ß-ß-catenin signaling and NF-κB activity. GENERAL SIGNIFICANCE: Wnt3a-Dvl3-ß-catenin signaling axis could be a potential interventional target for manipulating the direction and intensity of inflammatory responses.


Subject(s)
Dishevelled Proteins/metabolism , Glycogen Synthase Kinase 3 beta/metabolism , Inflammation/metabolism , Signal Transduction/physiology , Toll-Like Receptor 4/metabolism , Wnt3A Protein/metabolism , beta Catenin/metabolism , Animals , Cytokines/metabolism , Endotoxins/metabolism , Humans , Lipopolysaccharides/pharmacology , Mice , Mice, Inbred C57BL , Monocytes/metabolism , Multiple Organ Failure/metabolism , Phosphorylation/physiology , Transcription Factor RelA/metabolism , Tumor Necrosis Factor-alpha/metabolism
19.
Infect Immun ; 88(3)2020 02 20.
Article in English | MEDLINE | ID: mdl-31871100

ABSTRACT

Yersinia pestis causes a rapid, lethal disease referred to as plague. Y. pestis actively inhibits the innate immune system to generate a noninflammatory environment during early stages of infection to promote colonization. The ability of Y. pestis to create this early noninflammatory environment is in part due to the action of seven Yop effector proteins that are directly injected into host cells via a type 3 secretion system (T3SS). While each Yop effector interacts with specific host proteins to inhibit their function, several Yop effectors either target the same host protein or inhibit converging signaling pathways, leading to functional redundancy. Previous work established that Y. pestis uses the T3SS to inhibit neutrophil respiratory burst, phagocytosis, and release of inflammatory cytokines. Here, we show that Y. pestis also inhibits release of granules in a T3SS-dependent manner. Moreover, using a gain-of-function approach, we discovered previously hidden contributions of YpkA and YopJ to inhibition and that cooperative actions by multiple Yop effectors are required to effectively inhibit degranulation. Independent from degranulation, we also show that multiple Yop effectors can inhibit synthesis of leukotriene B4 (LTB4), a potent lipid mediator released by neutrophils early during infection to promote inflammation. Together, inhibition of these two arms of the neutrophil response likely contributes to the noninflammatory environment needed for Y. pestis colonization and proliferation.


Subject(s)
Bacterial Proteins/metabolism , Host-Pathogen Interactions/physiology , Neutrophils/physiology , Virulence Factors/metabolism , Yersinia pestis/pathogenicity , Bacterial Proteins/genetics , Cell Degranulation , Gain of Function Mutation , Humans , Leukotriene B4/metabolism , Neutrophils/metabolism , Plague/immunology , Secretory Vesicles/metabolism , Type III Secretion Systems/genetics , Type III Secretion Systems/metabolism , Virulence Factors/genetics , Yersinia pestis/genetics , Yersinia pestis/metabolism
20.
Adv Exp Med Biol ; 1197: 165-178, 2019.
Article in English | MEDLINE | ID: mdl-31732941

ABSTRACT

Periodontitis is a multifactorial chronic inflammatory infectious disease that compromises the integrity of tooth-supporting tissues. The disease progression depends on the disruption of host-microbe homeostasis in the periodontal tissue. This disruption is marked by a shift in the composition of the polymicrobial oral community from a symbiotic to a dysbiotic, more complex community that is capable of evading killing while promoting inflammation. Neutrophils are the main phagocytic cell in the periodontal pocket, and the outcome of the interaction with the oral microbiota is an important determinant of oral health. Novel culture-independent techniques have facilitated the identification of new bacterial species at periodontal lesions and induced a reappraisal of the microbial etiology of periodontitis. In this chapter, we discuss how neutrophils interact with two emerging oral pathogens, Filifactor alocis and Peptoanaerobacter stomatis, and the different strategies deploy by these organisms to modulate neutrophil effector functions, with the goal to outline a new paradigm in our knowledge about neutrophil responses to putative periodontal pathogens and their contribution to disease progression.


Subject(s)
Neutrophils , Periodontitis , Clostridiales/immunology , Dysbiosis , Humans , Microbiota/immunology , Neutrophils/immunology , Neutrophils/microbiology , Periodontitis/immunology , Periodontitis/microbiology , Periodontium/microbiology
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