scholarly journals Proteome Analysis of Coinfection of Epithelial Cells with Filifactor alocis and Porphyromonas gingivalis Shows Modulation of Pathogen and Host Regulatory Pathways

2014 ◽  
Vol 82 (8) ◽  
pp. 3261-3274 ◽  
Author(s):  
A. Wilson Aruni ◽  
Kangling Zhang ◽  
Yuetan Dou ◽  
Hansel Fletcher
Keyword(s):  
Epithelial Cells ◽  
Porphyromonas Gingivalis ◽  
Epigenetic Modification ◽  
Polymicrobial Infection ◽  
Host Cells ◽  
Periodontal Pocket ◽  
Membrane Microdomains ◽  
Content Type ◽  
Regulatory Pathways ◽  
Filifactor Alocis

ABSTRACTChanges in periodontal status are associated with shifts in the composition of the bacterial community in the periodontal pocket. The relative abundances of several newly recognized microbial species, includingFilifactor alocis, as-yet-unculturable organisms, and other fastidious organisms have raised questions on their impact on disease development. We have previously reported that the virulence attributes ofF. alocisare enhanced in coculture withPorphyromonas gingivalis. We have evaluated the proteome of host cells andF. alocisduring a polymicrobial infection. Coinfection of epithelial cells withF. alocisandP. gingivalisstrains showed approximately 20% to 30% more proteins than a monoinfection. UnlikeF. alocisATCC 35896, the D-62D strain expressed more proteins during coculture withP. gingivalisW83 than withP. gingivalis33277. Proteins designated microbial surface component-recognizing adhesion matrix molecules (MSCRAMMs) and cell wall anchor proteins were highly upregulated during the polymicrobial infection. Ultrastructural analysis of the epithelial cells showed formation of membrane microdomains only during coinfection. The proteome profile of epithelial cells showed proteins related to cytoskeletal organization and gene expression and epigenetic modification to be in high abundance. Modulation of proteins involved in apoptotic and cell signaling pathways was noted during coinfection. The enhanced virulence potential ofF. alocismay be related to the differential expression levels of several putative virulence factors and their effects on specific host cell pathways.

scholarly journals Filifactor alocis Has Virulence Attributes That Can Enhance Its Persistence under Oxidative Stress Conditions and Mediate Invasion of Epithelial Cells by Porphyromonas gingivalis

2011 ◽  
Vol 79 (10) ◽  
pp. 3872-3886 ◽  
Author(s):  
A. Wilson Aruni ◽  
Francis Roy ◽  
H. M. Fletcher
Keyword(s):  
Oxidative Stress ◽  
Epithelial Cells ◽  
Porphyromonas Gingivalis ◽  
Virulence Factors ◽  
Clinical Isolates ◽  
Periodontal Pocket ◽  
Periodontal Pathogens ◽  
Content Type ◽  
Invasive Capacity ◽  
Filifactor Alocis

ABSTRACTFilifactor alocis, a Gram-positive anaerobic rod, is one of the most abundant bacteria identified in the periodontal pockets of periodontitis patients. There is a gap in our understanding of its pathogenicity and ability to interact with other periodontal pathogens. To evaluate the virulence potential ofF. alocisand its ability to interact withPorphyromonas gingivalisW83, several clinical isolates ofF. alociswere characterized.F. alocisshowed nongingipain protease and sialidase activities.In silicoanalysis revealed the molecular relatedness of several virulence factors fromF. alocisandP. gingivalis. In contrast toP. gingivalis,F. alociswas relatively resistant to oxidative stress and its growth was stimulated under those conditions. Biofilm formation was significantly increased in coculture. There was an increase in adherence and invasion of epithelial cells in coculture compared withP. gingivalisorF. alocismonocultures. In those epithelial cells, endocytic vesicle-mediated internalization was observed only during coculture. TheF. alocisclinical isolate had an increased invasive capacity in coculture withP. gingivaliscompared to the ATCC 35896 strain. In addition, there was variation in the proteomes of the clinical isolates compared to the ATCC 35896 strain. Hypothetical proteins and those known to be important virulence factors in other bacteria were identified. These results indicate thatF. alocishas virulence properties that may enhance its ability to survive and persist in the periodontal pocket and may play an important role in infection-induced periodontal disease.

scholarly journals Porphyromonas gingivalis Fimbriae Bind to Cytokeratin of Epithelial Cells

2002 ◽  
Vol 70 (1) ◽  
pp. 96-101 ◽  
Author(s):  
Hakimuddin T. Sojar ◽  
Ashu Sharma ◽  
Robert J. Genco
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Porphyromonas Gingivalis ◽  
Polyclonal Antibodies ◽  
Cell Extract ◽  
Host Cells ◽  
Amino Terminal ◽  
A Minor ◽  
Sepharose 4B ◽  
Overlay Assay

ABSTRACT The adherence of Porphyromonas gingivalis to host cells is likely a prerequisite step in the pathogenesis of P. gingivalis-induced periodontal disease. P. gingivalis binds to and invades epithelial cells, and fimbriae are shown to be involved in this process. Little is known regarding epithelial receptor(s) involved in binding of P. gingivalis fimbriae. Using an overlay assay with purified P. gingivalis fimbriae as a probe, two major epithelial cell proteins with masses of 50 and 40 kDa were identified by immunoblotting with fimbria-specific antibodies. Iodinated purified fimbriae also bound to the same two epithelial cell proteins. An affinity chromatography technique was utilized to isolate and purify the epithelial components to which P. gingivalis fimbriae bind. Purified fimbriae were coupled to CNBr-activated Sepharose-4B, and the solubilized epithelial cell extract proteins bound to the immobilized fimbriae were isolated from the column. A major 50-kDa component and a minor 40-kDa component were purified and could be digested with trypsin, suggesting that they were proteins. These affinity-eluted 50- and 40-kDa proteins were then subjected to amino-terminal sequencing, and no sequence could be determined, suggesting that these proteins have blocked amino-terminal residues. CNBr digestion of the 50-kDa component resulted in an internal sequence homologous to that of Keratin I molecules. Further evidence that P. gingivalis fimbriae bind to cytokeratin molecule(s) comes from studies showing that multicytokeratin rabbit polyclonal antibodies cross-react with the affinity-purified 50-kDa epithelial cell surface component. Also, binding of purified P. gingivalis fimbriae to epithelial components can be inhibited in an overlay assay by multicytokeratin rabbit polyclonal antibodies. Furthermore, we showed that biotinylated purified fimbriae bind to purified human epidermal keratin in an overlay assay. These studies suggest that the surface-accessible epithelial cytokeratins may act as receptor(s) for P. gingivalis fimbriae. We hypothesize that adherence of P. gingivalis fimbriae to cytokeratin may be important for colonization of oral mucous membranes and possibly also for activation of epithelial cells.

scholarly journals Role of Intracellular Carbon Metabolism Pathways in Shigella flexneri Virulence

2014 ◽  
Vol 82 (7) ◽  
pp. 2746-2755 ◽  
Author(s):  
E. A. Waligora ◽  
C. R. Fisher ◽  
N. J. Hanovice ◽  
A. Rodou ◽  
E. E. Wyckoff ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Pentose Phosphate Pathway ◽  
Carbon Metabolism ◽  
Cultured Cells ◽  
Shigella Flexneri ◽  
Plaque Assay ◽  
Pentose Phosphate ◽  
Host Cells ◽  
Content Type ◽  
Pathway Gene

ABSTRACTShigella flexneri, which replicates in the cytoplasm of intestinal epithelial cells, can use the Embden-Meyerhof-Parnas, Entner-Doudoroff, or pentose phosphate pathway for glycolytic carbon metabolism. To determine which of these pathways is used by intracellularS. flexneri, mutants were constructed and tested in a plaque assay for the ability to invade, replicate intracellularly, and spread to adjacent epithelial cells. Mutants blocked in the Embden-Meyerhof-Parnas pathway (pfkABandpykAFmutants) invaded the cells but formed very small plaques. Loss of the Entner-Doudoroff pathway geneedaresulted in small plaques, but the doubleeda eddmutant formed normal-size plaques. This suggested that the plaque defect of theedamutant was due to buildup of the toxic intermediate 2-keto-3-deoxy-6-phosphogluconic acid rather than a specific requirement for this pathway. Loss of the pentose phosphate pathway had no effect on plaque formation, indicating that it is not critical for intracellularS. flexneri. Supplementation of the epithelial cell culture medium with pyruvate allowed the glycolysis mutants to form larger plaques than those observed with unsupplemented medium, consistent with data from phenotypic microarrays (Biolog) indicating that pyruvate metabolism was not disrupted in these mutants. Interestingly, the wild-typeS. flexnerialso formed larger plaques in the presence of supplemental pyruvate or glucose, with pyruvate yielding the largest plaques. Analysis of the metabolites in the cultured cells showed increased intracellular levels of the added compound. Pyruvate increased the growth rate ofS. flexneriin vitro, suggesting that it may be a preferred carbon source inside host cells.

scholarly journals Upregulation of the Adhesin Gene EPA1 Mediated by PDR1 in Candida glabrata Leads to Enhanced Host Colonization

mSphere ◽  
2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Luis A. Vale-Silva ◽  
Beat Moeckli ◽  
Riccardo Torelli ◽  
Brunella Posteraro ◽  
Maurizio Sanguinetti ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Epithelial Cells ◽  
Candida Glabrata ◽  
Resistance Mechanism ◽  
Cell Types ◽  
Host Cells ◽  
Regulation Mechanism ◽  
Content Type

ABSTRACT Candida glabrata is an important fungal pathogen in human diseases and is also rapidly acquiring drug resistance. Drug resistance can be mediated by the transcriptional activator PDR1, and this results in the upregulation of multidrug transporters. Intriguingly, this resistance mechanism is associated in C. glabrata with increased virulence in animal models and also with increased adherence to specific host cell types. The C. glabrata adhesin gene EPA1 is a major contributor of virulence and adherence to host cells. Here, we show that EPA1 expression is controlled by PDR1 independently of subtelomeric silencing, a known EPA1 regulation mechanism. Thus, a relationship exists between PDR1, EPA1 expression, and adherence to host cells, which is critical for efficient virulence. Our results demonstrate that acquisition of drug resistance is beneficial for C. glabrata in fungus-host relationships. These findings further highlight the challenges of the therapeutic management of C. glabrata infections in human patients. Candida glabrata is the second most common Candida species causing disseminated infection, after C. albicans. C. glabrata is intrinsically less susceptible to the widely used azole antifungal drugs and quickly develops secondary resistance. Resistance typically relies on drug efflux with transporters regulated by the transcription factor Pdr1. Gain-of-function (GOF) mutations in PDR1 lead to a hyperactive state and thus efflux transporter upregulation. Our laboratory has characterized a collection of C. glabrata clinical isolates in which azole resistance was found to correlate with increased virulence in vivo. Contributing phenotypes were the evasion of adhesion and phagocytosis by macrophages and an increased adhesion to epithelial cells. These phenotypes were found to be dependent on PDR1 GOF mutation and/or C. glabrata strain background. In the search for the molecular effectors, we found that PDR1 hyperactivity leads to overexpression of specific cell wall adhesins of C. glabrata. Further study revealed that EPA1 regulation, in particular, explained the increase in adherence to epithelial cells. Deleting EPA1 eliminates the increase in adherence in an in vitro model of interaction with epithelial cells. In a murine model of urinary tract infection, PDR1 hyperactivity conferred increased ability to colonize the bladder and kidneys in an EPA1-dependent way. In conclusion, this study establishes a relationship between PDR1 and the regulation of cell wall adhesins, an important virulence attribute of C. glabrata. Furthermore, our data show that PDR1 hyperactivity mediates increased adherence to host epithelial tissues both in vitro and in vivo through upregulation of the adhesin gene EPA1. IMPORTANCE Candida glabrata is an important fungal pathogen in human diseases and is also rapidly acquiring drug resistance. Drug resistance can be mediated by the transcriptional activator PDR1, and this results in the upregulation of multidrug transporters. Intriguingly, this resistance mechanism is associated in C. glabrata with increased virulence in animal models and also with increased adherence to specific host cell types. The C. glabrata adhesin gene EPA1 is a major contributor of virulence and adherence to host cells. Here, we show that EPA1 expression is controlled by PDR1 independently of subtelomeric silencing, a known EPA1 regulation mechanism. Thus, a relationship exists between PDR1, EPA1 expression, and adherence to host cells, which is critical for efficient virulence. Our results demonstrate that acquisition of drug resistance is beneficial for C. glabrata in fungus-host relationships. These findings further highlight the challenges of the therapeutic management of C. glabrata infections in human patients.

scholarly journals Fur Represses Adhesion to, Invasion of, and Intracellular Bacterial Community Formation within Bladder Epithelial Cells and Motility in Uropathogenic Escherichia coli

2016 ◽  
Vol 84 (11) ◽  
pp. 3220-3231 ◽  
Author(s):  
Kumiko Kurabayashi ◽  
Tomohiro Agata ◽  
Hirofumi Asano ◽  
Haruyoshi Tomita ◽  
Hidetada Hirakawa
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Antimicrobial Agents ◽  
Host Cells ◽  
Type I ◽  
Wild Type ◽  
Content Type ◽  
Type I Fimbriae ◽  
Tract Infections

Uropathogenic Escherichia coli (UPEC) is a major pathogen that causes urinary tract infections (UTIs). This bacterium adheres to and invades the host cells in the bladder, where it forms biofilm-like polymicrobial structures termed intracellular bacterial communities (IBCs) that protect UPEC from antimicrobial agents and the host immune systems. Using genetic screening, we found that deletion of the fur gene, which encodes an iron-binding transcriptional repressor for iron uptake systems, elevated the expression of type I fimbriae and motility when UPEC was grown under iron-rich conditions, and it led to an increased number of UPEC cells adhering to and internalized in bladder epithelial cells. Consequently, the IBC colonies that the fur mutant formed in host cells were denser and larger than those formed by the wild-type parent strain. Fur is inactivated under iron-restricted conditions. When iron was depleted from the bacterial cultures, wild-type UPEC adhesion, invasion, and motility increased, similar to the case with the fur mutant. The purified Fur protein bound to regions upstream of fimA and flhD , which encode type I fimbriae and an activator of flagellar expression that contributes to motility, respectively. These results suggest that Fur is a repressor of fimA and flhD and that its repression is abolished under iron-depleted conditions. Based on our in vitro experiments, we conclude that UPEC adhesion, invasion, IBC formation, and motility are suppressed by Fur under iron-rich conditions but derepressed under iron-restricted conditions, such as in patients with UTIs.

scholarly journals Intracellular Vibrio parahaemolyticus Escapes the Vacuole and Establishes a Replicative Niche in the Cytosol of Epithelial Cells

mBio ◽  
2014 ◽  
Vol 5 (5) ◽  
Author(s):  
Marcela de Souza Santos ◽  
Kim Orth
Keyword(s):  
Epithelial Cells ◽  
Acute Gastroenteritis ◽  
Vibrio Parahaemolyticus ◽  
Marine Bacterium ◽  
Host Cells ◽  
Secretion Systems ◽  
Content Type ◽  
Early Endosomes ◽  
Extracellular Bacterium

ABSTRACT Vibrio parahaemolyticus is a globally disseminated Gram-negative marine bacterium and the leading cause of seafood-borne acute gastroenteritis. Pathogenic bacterial isolates encode two type III secretion systems (T3SS), with the second system (T3SS2) considered the main virulence factor in mammalian hosts. For many decades, V. parahaemolyticus has been studied as an exclusively extracellular bacterium. However, the recent characterization of the T3SS2 effector protein VopC has suggested that this pathogen has the ability to invade, survive, and replicate within epithelial cells. Herein, we characterize this intracellular lifestyle in detail. We show that following internalization, V. parahaemolyticus is contained in vacuoles that develop into early endosomes, which subsequently mature into late endosomes. V. parahaemolyticus then escapes into the cytoplasm prior to vacuolar fusion with lysosomes. Vacuolar acidification is an important trigger for this escape. The cytoplasm serves as the pathogen’s primary intracellular replicative niche; cytosolic replication is rapid and robust, with cells often containing over 150 bacteria by the time of cell lysis. These results show how V. parahaemolyticus successfully establishes an intracellular lifestyle that could contribute to its survival and dissemination during infection. IMPORTANCE The marine bacterium V. parahaemolyticus is the leading cause worldwide of seafood-borne acute gastroenteritis. For decades, the pathogen has been studied exclusively as an extracellular bacterium. However, recent results have revealed the pathogen’s ability to invade and replicate within host cells. The present study is the first characterization of the V. parahaemolyticus’ intracellular lifestyle. Upon internalization, V. parahaemolyticus is contained in a vacuole that would in the normal course of events ultimately fuse with a lysosome, degrading the vacuole’s contents. The bacterium subverts this pathway, escaping into the cytoplasm prior to lysosomal fusion. Once in the cytoplasm, it replicates prolifically. Our study provides new insights into the strategies used by this globally disseminated pathogen to survive and proliferate within its host.

scholarly journals Galactose Impacts the Size and Intracellular Composition of the Asaccharolytic Oral PathobiontPorphyromonas gingivalis

2018 ◽  
Vol 85 (4) ◽  
Author(s):  
Zachary D. Moye ◽  
Courtney M. Gormley ◽  
Mary E. Davey
Keyword(s):  
Stationary Phase ◽  
Porphyromonas Gingivalis ◽  
Physiological State ◽  
Periodontal Pathogen ◽  
Periodontal Pocket ◽  
Enzyme Linked Immunosorbent Assay ◽  
Gram Positive ◽  
Content Type ◽  
The Impact ◽  
Gram Positive Cocci

ABSTRACTThe asaccharolytic anaerobePorphyromonas gingivalismetabolizes proteins it encounters in the periodontal pocket, including host-derived glycoproteins such as mucins and immunoglobulins. Often, these proteins are protected by a diverse array of carbohydrates tethered to the polypeptide chain via glycolytic bonds, andP. gingivalisproduces enzymes capable of liberating these carbohydrates, exposing the proteinaceous core. In this study, we investigated the effect of individual monosaccharides, including galactose,l-fucose, mannose, and glucose, on the growth and physiology ofP. gingivalis. Of the carbohydrates tested, only galactose noticeably altered the density of the bacterial culture, and we observed that cultures grown with galactose reached significantly higher densities during stationary phase. Importantly, electron micrographs and plating ofP. gingivalisin stationary phase demonstrated that the presence of galactose did not increase cell numbers; instead, the higher densities resulted from the expansion of individual cells which contained large intracellular granules. Initial attempts to characterize these granules revealed only a subtle increase in soluble carbohydrates, suggesting they are likely not composed of stored carbohydrate. Also, an analysis of major surface polysaccharides via an enzyme-linked immunosorbent assay (ELISA) did not reveal significant differences between cells grown with or without galactose. Finally, an initial investigation of the transcriptional changes elicited by galactose in late exponential phase suggested that genes important for cell shape and for the general stress response may play roles in this phenomenon. Overall, galactose, a monosaccharide commonly present on the surfaces of host proteins, substantially alters the physiology ofP. gingivalisvia the production of large, currently undefined, intracellular granules.IMPORTANCEEnvironmental perturbations are central to the ability of pathobionts, such asPorphyromonas gingivalis, to promote the development of diseased sites. In the case of periodontal disease, increased local pH, a shift to anaerobic surroundings, and the accumulation of Gram-negative anaerobes at the expense of Gram-positive cocci are known ecological fluctuations prominently associated with progression toward disease. Importantly, in contrast, the alterations to subgingival food webs in disease sites remain poorly characterized. We hypothesized that given the dramatic shift in community structure during disease, it is possible that free carbohydrates, which would typically be readily metabolized by Gram-positive cocci after cleavage from glycoproteins, may increase in concentration locally and thereby affect the physiological state of the subgingival microbiota. In this study, we explored the impact of free monosaccharides onP. gingivalisto gain deeper insight into the effect of dysbiotic conditions on the growth and physiology of this periodontal pathogen.

scholarly journals Filifactor alocis Promotes Neutrophil Degranulation and Chemotactic Activity

2016 ◽  
Vol 84 (12) ◽  
pp. 3423-3433 ◽  
Author(s):  
Cortney L. Armstrong ◽  
Irina Miralda ◽  
Adam C. Neff ◽  
Shifu Tian ◽  
Aruna Vashishta ◽  
...  
Keyword(s):  
P38 Mapk ◽  
Periodontal Pocket ◽  
Human Neutrophils ◽  
Neutrophil Chemotaxis ◽  
Granule Exocytosis ◽  
Content Type ◽  
Innate Defense ◽  
Random Migration ◽  
Neutrophil Degranulation ◽  
Filifactor Alocis

Filifactor alocis is a recently recognized periodontal pathogen; however, little is known regarding its interactions with the immune system. As the first-responder phagocytic cells, neutrophils are recruited in large numbers to the periodontal pocket, where they play a crucial role in the innate defense of the periodontium. Thus, in order to colonize, successful periodontal pathogens must devise means to interfere with neutrophil chemotaxis and activation. In this study, we assessed major neutrophil functions, including degranulation and cell migration, associated with the p38 mitogen-activated protein kinase (MAPK) signaling pathway upon challenge with F. alocis. Under conditions lacking a chemotactic gradient, F. alocis -challenged neutrophils had increased migration compared to uninfected cells, indicating that F. alocis increases chemokinesis in human neutrophils. In addition, neutrophil chemotaxis induced by interleukin-8 was significantly enhanced when cells were challenged with F. alocis , compared to noninfected cells. Similar to live bacteria, heat-killed F. alocis induced both random and directed migration of human neutrophils. The interaction of F. alocis with Toll-like receptor 2 induced granule exocytosis along with a transient ERK1/2 and sustained p38 MAPK activation. Moreover, F. alocis -induced secretory vesicle and specific granule exocytosis were p38 MAPK dependent. Blocking neutrophil degranulation with TAT-SNAP23 fusion protein significantly reduced the chemotactic and random migration induced by F. alocis . Therefore, we propose that induction of random migration by F. alocis will prolong neutrophil traffic time in the gingival tissue, and subsequent degranulation will contribute to tissue damage.

scholarly journals Porphyromonas gingivalis Induction of MicroRNA-203 Expression Controls Suppressor of Cytokine Signaling 3 in Gingival Epithelial Cells

2011 ◽  
Vol 79 (7) ◽  
pp. 2632-2637 ◽  
Author(s):  
Catherine E. Moffatt ◽  
Richard J. Lamont
Keyword(s):  
Epithelial Cells ◽  
Porphyromonas Gingivalis ◽  
Luciferase Assay ◽  
Cytokine Signaling ◽  
Mrna Levels ◽  
Suppressor Of Cytokine Signaling ◽  
Content Type ◽  
Downstream Target ◽  
Qrt Pcr ◽  
Gingival Epithelial Cells

ABSTRACTPorphyromonas gingivalisis a pathogen in severe periodontal disease. Able to exploit an intracellular lifestyle within primary gingival epithelial cells (GECs), a reservoir ofP. gingivaliscan persist within the gingival epithelia. This process is facilitated by manipulation of the host cell signal transduction cascades which can impact cell cycle, cell death, and cytokine responses. Using microarrays, we investigated the ability ofP. gingivalis33277 to regulate microRNA (miRNA) expression in GECs. One of several miRNAs differentially regulated by GECs in the presence ofP. gingivaliswas miRNA-203 (miR-203), which was upregulated 4-fold compared to uninfected controls. Differential regulation of miR-203 was confirmed by quantitative reverse transcription-PCR (qRT-PCR). Putative targets of miR-203, suppressor of cytokine signaling 3 (SOCS3) and SOCS6, were evaluated by qRT-PCR. SOCS3 and SOCS6 mRNA levels were reduced >5-fold and >2-fold, respectively, inP. gingivalis-infected GECs compared to controls. Silencing of miR-203 using a small interfering RNA construct reversed the inhibition of SOCS3 expression. A dual luciferase assay confirmed binding of miR-203 to the putative target binding site of the SOCS3 3′ untranslated region. Western blot analysis demonstrated that activation of signal transducer and activator of transcription 3 (Stat3), a downstream target of SOCS, was diminished following miR-203 silencing. This study shows that induction of miRNAs byP. gingivaliscan modulate important host signaling responses.

scholarly journals Determination of Active Phagocytosis of Unopsonized Porphyromonas gingivalis by Macrophages and Neutrophils Using the pH-Sensitive Fluorescent Dye pHrodo

2016 ◽  
Vol 84 (6) ◽  
pp. 1753-1760 ◽  
Author(s):  
Jason C. Lenzo ◽  
Neil M. O'Brien-Simpson ◽  
Jessica Cecil ◽  
James A. Holden ◽  
Eric C. Reynolds
Keyword(s):  
Immune System ◽  
Porphyromonas Gingivalis ◽  
Adaptive Immune System ◽  
Ph Sensitive ◽  
Host Cells ◽  
Periodontal Pathogen ◽  
Phagocytic Cells ◽  
Monocytic Cells ◽  
Content Type ◽  
Major Histocompatibility Complexes

Phagocytosis of pathogens is an important component of the innate immune system that is responsible for the removal and degradation of bacteria as well as their presentation via the major histocompatibility complexes to the adaptive immune system. The periodontal pathogenPorphyromonas gingivalisexhibits strain heterogeneity, which may affect a phagocyte's ability to recognize and phagocytose the bacterium. In addition,P. gingivalisis reported to avoid phagocytosis by antibody and complement degradation and by invading phagocytic cells. Previous studies examining phagocytosis have been confounded by both the techniques employed and the potential of the bacteria to invade the cells. In this study, we used a novel, pH-sensitive dye, pHrodo, to label liveP. gingivalisstrains and examine unopsonized phagocytosis by murine macrophages and neutrophils and human monocytic cells. All host cells examined were able to recognize and phagocytose unopsonizedP. gingivalisstrains. Macrophages had a preference to phagocytoseP. gingivalisstrain ATCC 33277 over other strains and clinical isolates in the study, whereas neutrophils favoredP. gingivalisW50, ATCC 33277, and one clinical isolate over the other strains. This study revealed that allP. gingivalisstrains were capable of being phagocytosed without prior opsonization with antibody or complement.

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