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Tobacco upregulates P. gingivalis fimbrial proteins which induce TLR2 hyposensitivity.

Bagaitkar J, Demuth DR, Daep CA, Renaud DE, Pierce DL, Scott DA - PLoS ONE (2010)

Bottom Line: We have previously shown that cigarette smoke extract (CSE) represents an environmental stress to which P. gingivalis adapts by altering the expression of several virulence factors - including major and minor fimbrial antigens (FimA and Mfa1, respectively) and capsule - concomitant with a reduced pro-inflammatory potential of intact P. gingivalis.We hypothesized that CSE-regulation of capsule and fimbrial genes is reflected at the ultrastructural and functional levels, alters the nature of host-pathogen interactions, and contributes to the reduced pro- inflammatory potential of smoke exposed P. gingivalis.These studies provide some of the first information to explain, mechanistically, how tobacco smoke changes the P. gingivalis phenotype in a manner likely to promote P. gingivalis colonization and infection while simultaneously reducing the host response to this major mucosal pathogen.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, Kentucky, United States of America.

ABSTRACT

Background: Tobacco smokers are more susceptible to periodontitis than non-smokers but exhibit reduced signs of clinical inflammation. The underlying mechanisms are unknown. We have previously shown that cigarette smoke extract (CSE) represents an environmental stress to which P. gingivalis adapts by altering the expression of several virulence factors - including major and minor fimbrial antigens (FimA and Mfa1, respectively) and capsule - concomitant with a reduced pro-inflammatory potential of intact P. gingivalis.

Methodology/principal findings: We hypothesized that CSE-regulation of capsule and fimbrial genes is reflected at the ultrastructural and functional levels, alters the nature of host-pathogen interactions, and contributes to the reduced pro- inflammatory potential of smoke exposed P. gingivalis. CSE induced ultrastructural alterations were determined by electron microscopy, confirmed by Western blot and physiological consequences studied in open-flow biofilms. Inflammatory profiling of specific CSE-dysregulated proteins, rFimA and rMfa1, was determined by quantifying cytokine induction in primary human innate and OBA-9 cells. CSE up-regulates P. gingivalis FimA at the protein level, suppresses the production of capsular polysaccharides at the ultrastructural level, and creates conditions that promote biofilm formation. We further show that while FimA is recognized by TLR2/6, it has only minimal inflammatory activity in several cell types. Furthermore, FimA stimulation chronically abrogates the pro-inflammatory response to subsequent TLR2 stimulation by other TLR-2-specific agonists (Pam3CSK4, FSL, Mfa1) in an IkappaBalpha- and IRAK-1-dependent manner.

Conclusions/significance: These studies provide some of the first information to explain, mechanistically, how tobacco smoke changes the P. gingivalis phenotype in a manner likely to promote P. gingivalis colonization and infection while simultaneously reducing the host response to this major mucosal pathogen.

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Related in: MedlinePlus

FimA induced tolerance reduces Iκ-Bα degradation.(A) Human PBMCs were pre-treated with 1 µg/ml rFimA for 24 hrs before stimulation with 1 µg/ml of rMfa1 for various timepoints. Immunoblots (25 µg protein per well) were probed for IκBα and re-probed β-actin to ensure equal loading. (B) Mean (s.e.) normalized band intensities.
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pone-0009323-g006: FimA induced tolerance reduces Iκ-Bα degradation.(A) Human PBMCs were pre-treated with 1 µg/ml rFimA for 24 hrs before stimulation with 1 µg/ml of rMfa1 for various timepoints. Immunoblots (25 µg protein per well) were probed for IκBα and re-probed β-actin to ensure equal loading. (B) Mean (s.e.) normalized band intensities.

Mentions: NF-κB transcription factors are complexed with IκB proteins in the cytosol. On receiving specific, but varied, extracellular signals IκBα is phosphorylated and targeted for proteasome-mediated degradation, resulting in the release and nuclear translocation of transcriptionally effective NF-κB [9], [10], [30], [31], [32], [33]. We compared Iκ-Bα protein levels in PBMCs exposed to rMfa1, with or without pre-incubation with rFimA. As shown in Figure 6, while the potent pro-inflammatory agonist, Mfa1, induced rapid and extensive Iκ-Bα degradation, pre-incubation with rFimA efficiently abrogated this Mfa1-triggered Iκ-Bα degradation. Thus, FimA appears to promote TLR2 hyposensitivity by inhibiting TLR2 agonist-induced degradation of Iκ-Bα. Essentially identical results were found for a second TLR2 agonist, FSL (data not shown).


Tobacco upregulates P. gingivalis fimbrial proteins which induce TLR2 hyposensitivity.

Bagaitkar J, Demuth DR, Daep CA, Renaud DE, Pierce DL, Scott DA - PLoS ONE (2010)

FimA induced tolerance reduces Iκ-Bα degradation.(A) Human PBMCs were pre-treated with 1 µg/ml rFimA for 24 hrs before stimulation with 1 µg/ml of rMfa1 for various timepoints. Immunoblots (25 µg protein per well) were probed for IκBα and re-probed β-actin to ensure equal loading. (B) Mean (s.e.) normalized band intensities.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2864253&req=5

pone-0009323-g006: FimA induced tolerance reduces Iκ-Bα degradation.(A) Human PBMCs were pre-treated with 1 µg/ml rFimA for 24 hrs before stimulation with 1 µg/ml of rMfa1 for various timepoints. Immunoblots (25 µg protein per well) were probed for IκBα and re-probed β-actin to ensure equal loading. (B) Mean (s.e.) normalized band intensities.
Mentions: NF-κB transcription factors are complexed with IκB proteins in the cytosol. On receiving specific, but varied, extracellular signals IκBα is phosphorylated and targeted for proteasome-mediated degradation, resulting in the release and nuclear translocation of transcriptionally effective NF-κB [9], [10], [30], [31], [32], [33]. We compared Iκ-Bα protein levels in PBMCs exposed to rMfa1, with or without pre-incubation with rFimA. As shown in Figure 6, while the potent pro-inflammatory agonist, Mfa1, induced rapid and extensive Iκ-Bα degradation, pre-incubation with rFimA efficiently abrogated this Mfa1-triggered Iκ-Bα degradation. Thus, FimA appears to promote TLR2 hyposensitivity by inhibiting TLR2 agonist-induced degradation of Iκ-Bα. Essentially identical results were found for a second TLR2 agonist, FSL (data not shown).

Bottom Line: We have previously shown that cigarette smoke extract (CSE) represents an environmental stress to which P. gingivalis adapts by altering the expression of several virulence factors - including major and minor fimbrial antigens (FimA and Mfa1, respectively) and capsule - concomitant with a reduced pro-inflammatory potential of intact P. gingivalis.We hypothesized that CSE-regulation of capsule and fimbrial genes is reflected at the ultrastructural and functional levels, alters the nature of host-pathogen interactions, and contributes to the reduced pro- inflammatory potential of smoke exposed P. gingivalis.These studies provide some of the first information to explain, mechanistically, how tobacco smoke changes the P. gingivalis phenotype in a manner likely to promote P. gingivalis colonization and infection while simultaneously reducing the host response to this major mucosal pathogen.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, Kentucky, United States of America.

ABSTRACT

Background: Tobacco smokers are more susceptible to periodontitis than non-smokers but exhibit reduced signs of clinical inflammation. The underlying mechanisms are unknown. We have previously shown that cigarette smoke extract (CSE) represents an environmental stress to which P. gingivalis adapts by altering the expression of several virulence factors - including major and minor fimbrial antigens (FimA and Mfa1, respectively) and capsule - concomitant with a reduced pro-inflammatory potential of intact P. gingivalis.

Methodology/principal findings: We hypothesized that CSE-regulation of capsule and fimbrial genes is reflected at the ultrastructural and functional levels, alters the nature of host-pathogen interactions, and contributes to the reduced pro- inflammatory potential of smoke exposed P. gingivalis. CSE induced ultrastructural alterations were determined by electron microscopy, confirmed by Western blot and physiological consequences studied in open-flow biofilms. Inflammatory profiling of specific CSE-dysregulated proteins, rFimA and rMfa1, was determined by quantifying cytokine induction in primary human innate and OBA-9 cells. CSE up-regulates P. gingivalis FimA at the protein level, suppresses the production of capsular polysaccharides at the ultrastructural level, and creates conditions that promote biofilm formation. We further show that while FimA is recognized by TLR2/6, it has only minimal inflammatory activity in several cell types. Furthermore, FimA stimulation chronically abrogates the pro-inflammatory response to subsequent TLR2 stimulation by other TLR-2-specific agonists (Pam3CSK4, FSL, Mfa1) in an IkappaBalpha- and IRAK-1-dependent manner.

Conclusions/significance: These studies provide some of the first information to explain, mechanistically, how tobacco smoke changes the P. gingivalis phenotype in a manner likely to promote P. gingivalis colonization and infection while simultaneously reducing the host response to this major mucosal pathogen.

Show MeSH
Related in: MedlinePlus