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Zhao JJ, Jiang L, Zhu YQ, Feng XP. Effect of Lactobacillus acidophilus and Porphyromonas gingivalis on proliferation and apoptosis of gingival epithelial cells. Adv Med Sci 2019; 64:54-57. [PMID: 30472626 DOI: 10.1016/j.advms.2018.04.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 12/04/2017] [Accepted: 04/26/2018] [Indexed: 11/25/2022]
Abstract
PURPOSE This study aimed to evaluate the possible antagonistic effects of Lactobacillus acidophilus on Porphyromonas gingivalis, and detect inhibition of Lactobacillus acidophilus on Porphyromonas gingivalis when they are co-cultured with human gingival epithelial cells. MATERIALS AND METHODS Human gingival epithelial cells were co-cultured with Lactobacillus acidophilus and Porphyromonas gingivalis alone or together. The amount of Porphyromonas gingivalis adhering to or invading the epithelial cells were determined by bacterial counts. The cellular proliferation was assayed by the MTT method. Apoptosis was detected by flow cytometry with apoptosis detection kit. RESULTS On one hand, Lactobacillus acidophilus reduced the inhibitory effect of Porphyromonas gingivalis on the human gingival epithelial cells proliferation in a dose dependent manner. On the other hand, Porphyromonas gingivalis induced significant apoptosis on human gingival epithelial cells, and Lactobacillus acidophilus inhibited this apoptosis-inducing effect of Porphyromonas gingivalis in a dose dependent manner. CONCLUSIONS Porphyromonas gingivalis inhibits the proliferation and induces the apoptosis of human gingival epithelial cells. Lactobacillus acidophilus could attenuate this effect in a dose-dependent manner, and it thus reduces the destruction from pathogens. Lactobacillus acidophilus could be an effective candidate for probiotic therapy in periodontal diseases.
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Gut microbiome of Moroccan colorectal cancer patients. Med Microbiol Immunol 2018; 207:211-225. [PMID: 29687353 PMCID: PMC6096775 DOI: 10.1007/s00430-018-0542-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 03/24/2018] [Indexed: 12/18/2022]
Abstract
Although colorectal cancer is the third leading cause of death in Morocco, there are no studies of the microbiome changes associated with the disease in the Moroccan population. The aim of our study was to compare the stool microbiome of Moroccan cancer patients with healthy individuals. We analyzed the microbiome composition of samples from 11 CRC patients and 12 healthy individuals by 16S rRNA amplicon sequencing. Principal coordinate analysis of samples revealed defined cancer versus healthy clusters. Our findings showed that cancer samples had higher proportions of Firmicutes (T = 50.5%; N = 28.4%; p = 0.04), specifically of Clostridia (T = 48.3%; N = 19.0%; p = 0.002), and Fusobacteria (T = 0.1%; N = 0.0%; p = 0.02), especially of Fusobacteriia (T = 0.1%; N = 0.0%; p = 0.02), while Bacteroidetes were enriched in healthy samples (T = 35.1%; N = 62.8%; p = 0.06), particularly the class Bacteroidia (T = 35.1%; N = 62.6%; p = 0.06). Porphyromonas, Clostridium, Ruminococcus, Selenomonas, and Fusobacterium were significantly overrepresented in diseased patients, similarly to other studies. Predicted functional information showed that bacterial motility proteins, flagellar assembly, and fatty acid biosynthesis metabolism were significantly overrepresented in cancer patients, while amino acid metabolism and glycan biosynthesis were overrepresented in controls. This suggests that involvement of these functional metagenomes is similar and relevant in the carcinogenesis process, independent of the origin of the samples. Results from this study allowed identification of bacterial taxa relevant to the Moroccan population and encourages larger studies to facilitate population-directed therapeutic approaches.
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Porphyromonas gingivalis modulates Pseudomonas aeruginosa-induced apoptosis of respiratory epithelial cells through the STAT3 signaling pathway. Microbes Infect 2013; 16:17-27. [PMID: 24140557 DOI: 10.1016/j.micinf.2013.10.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 09/22/2013] [Accepted: 10/04/2013] [Indexed: 12/31/2022]
Abstract
Pseudomonas aeruginosa is an important opportunistic bacterial pathogen, causing infections of respiratory and other organ systems in immunocompromised hosts that may invade and proliferate in mucosal epithelial cells to induce apoptosis. Previous studies suggest that oral bacteria, especially gram-negative periodontal pathogens, may enhance P. aeruginosa invasion into respiratory epithelial cells to augment tissue destruction. In this study, we investigated the effect of the periodontopathogen Porphyromonas gingivalis on P. aeruginosa-induced epithelial cell apoptosis. P. gingivalis invasion transiently inhibited P. aeruginosa-induced apoptosis in respiratory epithelial cells via the signal transducer and activator of transcription 3 (STAT3) signaling pathway. The activated STAT3 up-regulated the downstream anti-apoptotic moleculars survivin and B-cell leukemia-2 (bcl-2). This process was accompanied by down-regulation of pro-apoptosis molecular Bcl-2-associated death promoter (bad) and caspase-3 activity inhibition. In addition, the activation of the STAT3 pathway was affected by P. gingivalis in a dose-dependent manner. Finally, co-invasion of P. aeruginosa and P. gingivalis led to greater cell death compared with P. aeruginosa challenge alone. These results suggest that regulation of P. aeruginosa-induced apoptosis by P. gingivalis contributes to the pathogenesis of respiratory disease. Interference with this process may provide a potential therapeutic strategy for the treatment and prevention of respiratory disease.
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Chen W, Liu F, Ling Z, Tong X, Xiang C. Human intestinal lumen and mucosa-associated microbiota in patients with colorectal cancer. PLoS One 2012; 7:e39743. [PMID: 22761885 PMCID: PMC3386193 DOI: 10.1371/journal.pone.0039743] [Citation(s) in RCA: 657] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 05/25/2012] [Indexed: 12/12/2022] Open
Abstract
Recent reports have suggested the involvement of gut microbiota in the progression of colorectal cancer (CRC). We utilized pyrosequencing based analysis of 16S rRNA genes to determine the overall structure of microbiota in patients with colorectal cancer and healthy controls; we investigated microbiota of the intestinal lumen, the cancerous tissue and matched noncancerous normal tissue. Moreover, we investigated the mucosa-adherent microbial composition using rectal swab samples because the structure of the tissue-adherent bacterial community is potentially altered following bowel cleansing. Our findings indicated that the microbial structure of the intestinal lumen and cancerous tissue differed significantly. Phylotypes that enhance energy harvest from diets or perform metabolic exchange with the host were more abundant in the lumen. There were more abundant Firmicutes and less abundant Bacteroidetes and Proteobacteria in lumen. The overall microbial structures of cancerous tissue and noncancerous tissue were similar; howerer the tumor microbiota exhibited lower diversity. The structures of the intestinal lumen microbiota and mucosa-adherent microbiota were different in CRC patients compared to matched microbiota in healthy individuals. Lactobacillales was enriched in cancerous tissue, whereas Faecalibacterium was reduced. In the mucosa-adherent microbiota, Bifidobacterium, Faecalibacterium, and Blautia were reduced in CRC patients, whereas Fusobacterium, Porphyromonas, Peptostreptococcus, and Mogibacterium were enriched. In the lumen, predominant phylotypes related to metabolic disorders or metabolic exchange with the host, Erysipelotrichaceae, Prevotellaceae, and Coriobacteriaceae were increased in cancer patients. Coupled with previous reports, these results suggest that the intestinal microbiota is associated with CRC risk and that intestinal lumen microflora potentially influence CRC risk via cometabolism or metabolic exchange with the host. However, mucosa-associated microbiota potentially affects CRC risk primarily through direct interaction with the host.
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Affiliation(s)
- Weiguang Chen
- State Key Laboratory for Infectious Diseases Diagnostics and Treatment, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Fanlong Liu
- Department of Anus and Intestine, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Zongxin Ling
- State Key Laboratory for Infectious Diseases Diagnostics and Treatment, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaojuan Tong
- State Key Laboratory for Infectious Diseases Diagnostics and Treatment, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Charlie Xiang
- State Key Laboratory for Infectious Diseases Diagnostics and Treatment, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
- * E-mail:
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Sheets SM, Robles-Price AG, McKenzie RME, Casiano CA, Fletcher HM. Gingipain-dependent interactions with the host are important for survival of Porphyromonas gingivalis. FRONTIERS IN BIOSCIENCE : A JOURNAL AND VIRTUAL LIBRARY 2008; 13:3215-38. [PMID: 18508429 PMCID: PMC3403687 DOI: 10.2741/2922] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Porphyromonas gingivalis, a major periodontal pathogen, must acquire nutrients from host derived substrates, overcome oxidative stress and subvert the immune system. These activities can be coordinated via the gingipains which represent the most significant virulence factor produced by this organism. In the context of our contribution to this field, we will review the current understanding of gingipain biogenesis, glycosylation, and regulation, as well as discuss their role in oxidative stress resistance and apoptosis. We can postulate a model, in which gingipains may be part of the mechanism for P. gingivalis virulence.
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Affiliation(s)
- Shaun M. Sheets
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda University, Loma Linda, California
| | - Antonette G. Robles-Price
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda University, Loma Linda, California
| | - Rachelle M. E. McKenzie
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda University, Loma Linda, California
| | - Carlos A. Casiano
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda University, Loma Linda, California
- The Center for Health Disparities and Molecular Medicine, Loma Linda University, Loma Linda, California
| | - Hansel M. Fletcher
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda University, Loma Linda, California
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Desta T, Graves DT. Fibroblast apoptosis induced by Porphyromonas gingivalis is stimulated by a gingipain and caspase-independent pathway that involves apoptosis-inducing factor. Cell Microbiol 2007; 9:2667-75. [PMID: 17587332 PMCID: PMC2885830 DOI: 10.1111/j.1462-5822.2007.00987.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Porphyromonas gingivalis is an oral bacterium that causes pathology in a number of dental infections that are associated with increased fibroblast cell death. Studies presented here demonstrated that P. gingivalis stimulates cell death by apoptosis rather than necrosis. Unlike previous studies apoptosis was induced independent of proteolytic activity and was also independent of caspase activity because a pancaspase inhibitor, Z-VAD-fmk, had little effect. Moreover, P. gingivalis downregulated caspase-3 mRNA levels and caspase-3 activity. The consequence of this downregulation was a significant reduction in tumour necrosis factor-alpha-induced apoptosis, which is caspase-3-dependent. Immunofluorescence and immunoblot analysis revealed P. gingivalis-induced translocation of apoptosis-inducing factor (AIF) from the cytoplasm to the nucleus. siRNA studies were undertaken and demonstrated that P. gingivalis stimulated cell death was significantly reduced when AIF was silenced (P < 0.05). Treatment of human gingival fibroblasts with H-89, a protein kinase A inhibitor that blocks AIF activation also reduced P. gingivalis-induced apoptosis (P < 0.05). These results indicate that P. gingivalis causes fibroblast apoptosis through a pathway that involves protein kinase A and AIF, is not dependent upon bacterial proteolytic activity and is also independent of the classic apoptotic pathways involving caspase-3.
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Affiliation(s)
| | - Dana T. Graves
- For correspondence. ; Tel. (+1) 617 638 8547; Fax (+1) 617 638 4924
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Mao S, Park Y, Hasegawa Y, Tribble GD, James CE, Handfield M, Stavropoulos MF, Yilmaz Ö, Lamont RJ. Intrinsic apoptotic pathways of gingival epithelial cells modulated by Porphyromonas gingivalis. Cell Microbiol 2007; 9:1997-2007. [PMID: 17419719 PMCID: PMC2886729 DOI: 10.1111/j.1462-5822.2007.00931.x] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Porphyromonas gingivalis can inhibit chemically induced apoptosis in primary cultures of gingival epithelial cells through blocking activation of the effector caspase-3. The anti-apoptotic phenotype of P. gingivalis is conserved across strains and does not depend on the presence of fimbriae, as fimbriae-deficient mutants and a naturally occurring non-fimbriated strain were able to impede apoptosis. To dissect the survival pathways modulated by P. gingivalis, protein and gene expression of a number of components of apoptotic death pathways were investigated. P. gingivalis infection of epithelial cells resulted in the phosphorylation of JAK1 and Stat3. Quantitative real-time reverse transcription polymerase chain reaction showed that expression of Survivin and Stat3 itself, targets of activated Stat3, were elevated in P. gingivalis-infected cells. siRNA knockdown of JAK1, in combination with knockdown of Akt, abrogated the ability of P. gingivalis to block apoptosis. In contrast, cIAP-1 and cIAP-2 were not differentially regulated at either the protein or mRNA levels by P. gingivalis. One mechanism by which P. gingivalis can block apoptotic pathways in gingival epithelial cells therefore is through manipulation of the JAK/Stat pathway that controls the intrinsic mitochondrial cell death pathways. Induction of a pro-survival phenotype may prevent programmed host cell death and aid survival of P. gingivalis within gingival epithelial cells.
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Affiliation(s)
- Song Mao
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - Yoonsuk Park
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - Yoshiaki Hasegawa
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - Gena D. Tribble
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - Chlöe E. James
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - Martin Handfield
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - M. Franci Stavropoulos
- Department of Oral and Maxillofacial Surgery College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - özlem Yilmaz
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
- Department of Periodontology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - Richard J. Lamont
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
- For correspondence. ; Tel. (+1) 352 392 5067; Fax (+1) 352 392 2361
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Morris TL, Arnold RR, Webster-Cyriaque J. Signaling cascades triggered by bacterial metabolic end products during reactivation of Kaposi's sarcoma-associated herpesvirus. J Virol 2007; 81:6032-42. [PMID: 17376930 PMCID: PMC1900322 DOI: 10.1128/jvi.02504-06] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The present studies explore the role of polymicrobial infection in the reactivation of Kaposi's sarcoma-associated herpesvirus (KSHV) and analyze signaling pathways activated upon this induction. We hypothesized that activation of the cellular stress-activated mitogen-activated protein kinase (MAPK) p38 pathway would play a key role in the bacterium-mediated disruption of viral latency similar to that of previously reported results obtained with other inducers of gammaherpesvirus lytic replication. KSHV within infected BCBL-1 cells was induced to replicate following exposure to metabolic end products from gram-negative or -positive bacteria that were then simultaneously exposed to specific inhibitors of signal transduction pathways. We have determined that bacterium-mediated induction of lytic KSHV infection is significantly reduced by the inhibition of the p38 MAPK pathway. In contrast, inhibition of the phosphatidylinositol 3-kinase pathway did not impair induction of lytic replication or p38 phosphorylation. Protein kinase C, though activated, was not the major pathway used for bacterium-induced viral reactivation. Furthermore, hyperacetylation of histones 3 and 4 was detected. Collectively, our results show that metabolic end products from these pathogens induce lytic replication of KSHV in BCBL-1 cells primarily via the activation of a stress-activated MAPK pathway. Importantly, we demonstrate for the first time a mechanism by which polymicrobial bacterial infections result in KSHV reactivation and pathogenesis.
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Affiliation(s)
- T L Morris
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599-7295, USA
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Affiliation(s)
- Anne C R Tanner
- Department of Molecular Genetics, The Forsyth Institute, Boston, Massachusetts, USA
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Influence of Porphyromonas gingivalis on the Expression of Cell Adhesion Molecules and Apoptosis in Human Gingival Epithelial Cells. J Oral Biosci 2006. [DOI: 10.1016/s1349-0079(06)80023-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Holt SC, Ebersole JL. Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia: the "red complex", a prototype polybacterial pathogenic consortium in periodontitis. Periodontol 2000 2005; 38:72-122. [PMID: 15853938 DOI: 10.1111/j.1600-0757.2005.00113.x] [Citation(s) in RCA: 629] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Stanley C Holt
- Department of Periodontology, The Forsyth Institute, Boston, MA, USA
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Sheets SM, Potempa J, Travis J, Casiano CA, Fletcher HM. Gingipains from Porphyromonas gingivalis W83 induce cell adhesion molecule cleavage and apoptosis in endothelial cells. Infect Immun 2005; 73:1543-52. [PMID: 15731052 PMCID: PMC1064927 DOI: 10.1128/iai.73.3.1543-1552.2005] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The presence of Porphyromonas gingivalis in the periodontal pocket and the high levels of gingipain activity detected in gingival crevicular fluid could implicate a role for gingipains in the destruction of the highly vascular periodontal tissue. To explore the effects of these proteases on endothelial cells, we exposed bovine coronary artery endothelial cells and human microvascular endothelial cells to gingipain-active extracellular protein preparations and/or purified gingipains from P. gingivalis. Treated cells exhibited a rapid loss of cell adhesion properties that was followed by apoptotic cell death. Cleavage of N- and VE-cadherin and integrin beta1 was observed in immunoblots of cell lysates. There was a direct correlation between the kinetics of cleavage of N- and VE-cadherin and loss of cell adhesion properties. Loss of cell adhesion, as well as N- and VE-cadherin and integrin beta1 cleavage, could be inhibited or significantly delayed by preincubation of P. gingivalis W83 gingipain-active extracellular extracts with the cysteine protease inhibitor Nalpha-p-tosyl-l-lysine chloromethylketone. Furthermore, purified gingipains also induced endothelial cell detachment and apoptosis. Apoptosis-associated events, including annexin V positivity, caspase-3 activation, and cleavage of the caspase substrates poly(ADP-ribose) polymerase and topoisomerase I (Topo I), were observed in endothelial cells after detachment. All of the effects observed were correlated with the different levels of cysteine-dependent proteolytic activity of the extracts tested. Taken together, these results indicate that gingipains from P. gingivalis can alter cell adhesion molecules and induce endothelial cell death, which could have implications for the pathogenicity of this organism.
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Affiliation(s)
- Shaun M Sheets
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA.
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Shon W, Kim HS, Son HH, Lim S, Lee W. Effects of Sonicated Enterococcus faecalis Extracts on Interleukin-2 and Interleukin-4 Production by Human T Cells. J Endod 2004; 30:701-3. [PMID: 15448462 DOI: 10.1097/01.don.0000129960.58129.af] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In the present authors' previous study, sonicated Enterococcus faecalis extracts were shown to suppress the cell cycle progression of human lymphocytes. To study the effect of this microorganism on the function of lymphocytes, the authors investigated the levels of interleukin-2 (IL-2) and interleukin-4 (IL-4) production by T lymphocytes before and after the addition of sonicated E. faecalis extracts. In this study, levels of IL-2 and IL-4 produced from T cells were evaluated by using the quantitative sandwich enzyme immunoassay technique. In response to phytohemagglutinin (PHA) stimulation, T cells produced increased levels of IL-2 and IL-4. However, the expressions of both cytokines were significantly inhibited when PHA-activated T cells were preexposed to 12.5 microg/ml and 25 microg/ml of sonicated E. faecalis extracts (p < 0.05). This effect was concentration-dependent, because the levels of IL-2 and IL-4 expressions were not affected by the addition of a low concentration (5 microg/ml) of sonicated extract. These findings suggest that Th1 and Th2 immunosuppression mediated by E. faecalis could be a part of the pathogenic mechanism of the endodontic failure associated with this microorganism.
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Affiliation(s)
- WonJun Shon
- Department of Conservative Dentistry, Seoul National University, 28 YeonGun Dong, ChongNo-Gu, Seoul 110-749, Republic of Korea
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Yilmaz O, Jungas T, Verbeke P, Ojcius DM. Activation of the phosphatidylinositol 3-kinase/Akt pathway contributes to survival of primary epithelial cells infected with the periodontal pathogen Porphyromonas gingivalis. Infect Immun 2004; 72:3743-51. [PMID: 15213114 PMCID: PMC427421 DOI: 10.1128/iai.72.7.3743-3751.2004] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Porphyromonas gingivalis, an important periodontal pathogen, infects primary gingival epithelial cells (GECs). Despite the large number of bacteria that replicate inside the GECs, the host cell remains viable. We demonstrate that P. gingivalis triggers rapid and reversible surface phosphatidylserine exposure through a mechanism requiring caspase activation. However, after 1 day of infection, the bacteria no longer induce phosphatidylserine externalization and instead protect infected cells against apoptosis. Infection exerts its effect at the level of mitochondria, as P. gingivalis also blocks depolarization of the mitochondrial transmembrane potential and cytochrome c release. Interestingly, protein kinase B/Akt is phosphorylated during infection, which can be blocked with the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Suppression of the PI3K/Akt pathway following staurosporine treatment results in mitochondrial-membrane depolarization, cytochrome c release, DNA fragmentation, and increased apoptosis of infected GECs. Thus, P. gingivalis stimulates early surface exposure of phosphatidylserine, which could downmodulate the inflammatory response, while also promoting host cell survival through the PI3K/Akt pathway.
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Affiliation(s)
- Ozlem Yilmaz
- Department of Pathobiology, University of Washington, School of Public Health, HSC Box 357238, Seattle, WA 98195, USA.
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Lee W, Lim S, Son HH, Bae KS. Sonicated extract of Enterococcus faecalis induces irreversible cell cycle arrest in phytohemagglutinin-activated human lymphocytes. J Endod 2004; 30:209-12. [PMID: 15085047 DOI: 10.1097/00004770-200404000-00006] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The purpose of this study was to examine whether the sonicated extract of Enterococcus faecalis (SEF) alters the cell cycle transition of lymphocytes and thus regulates the fate of the arrested cells. Human lymphocytes were activated by phytohemagglutinin in the presence or absence of SEF, and cell cycle was assessed by flow cytometry. Seventy-two hours after activation with phytohemagglutinin, cells were activated from G0/G1 to S (6.1%) and G2/M (3.8%) phases of the cell cycle. In contrast, pretreatment with SEF resulted in 90.5% of cells remaining in G0/G1, and cell cycle progression to the S and G2/M phases was consequently inhibited. Caspase assay demonstrated that SEF-treated cells exhibited significantly increased apoptosis (56.7%) compared with phytohemagglutinin alone (28.1%). We propose that if this irreversible cell cycle arrest induced by E. faecalis occurs in vivo, it may result in local immunosuppression and contribute to the pathogenesis of endodontic failure. Our findings that E. faecalis can inhibit lymphocyte responses may be of particular relevance to the pathogenesis of endodontic failure. Although the immunologic mechanism involved in the pathogenesis of persistent periapical lesion is not clearly defined, it is reasonable to predict that the altered immune reaction may be linked to the immunosuppressive potential of E. faecalis or other oral bacteria.
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Affiliation(s)
- WooCheol Lee
- Department of Conservative Dentistry, School of Dentistry, Seoul National University, Seoul, Korea
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