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Updated: Feb 28, 2026
Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells
Published on: December 17, 2015
Gingipain of Porphyromonas gingivalis manipulates M1 macrophage polarization through C5a pathway
Yubo Hou1, Haiyan Yu1, Xinchan Liu2
1Department of Periodontics, School of Stomatology, Jilin University, Changchun, Jilin, China.
Abstract:
Gingipains secreted by Porphyromonas gingivalis (P. gingivalis, Pg) play an important role in maintaining macrophage infiltrating. And, this study is to evaluate effects of gingipain on M1 macrophage polarization after exposure to Porphyromonas gingivalis (P. gingivalis, Pg) and if these effects are through complement component 5a (C5a) pathway. Mouse RAW264.7 macrophages were exposed to gingipain extracts, Escherichia coli lipopolysaccharides (Ec-LPS), Pg-LPS with or without the C5aR antagonist: PMX-53 for 24 h. Then, gene expressions and protein of IL-12, IL-23, iNOS, IL-10, TNF-α, IL-1β, and IL-6 were determined by qRT-PCR and ELISA assays. Surface markers CD86 for M1 and CD206 for M2 were also evaluated by flow cytometry. The results show that gingipain extracts alone increased expressions of IL-12, IL-23, iNOS, TNF-α, IL-1β, and IL-6, but not IL-10. Gingipain extracts plus Ec-LPS decreased expressions of IL-12, IL-23, iNOS, TNF-α, IL-1β, and IL-6 in which Ec-LPS induced increase. For gingipain extracts plus Pg-LPS-treated RAW264.7, macrophages, gingipain extracts enhanced expressions of IL-12 and IL-23 in which Pg-LPS induced increase, but not iNOS and IL-10 while gingipain extracts decreased expressions of TNF-α, IL-1β, and IL-6 in which Pg-LPS induced increase. Interestingly, PMX-53 increased expressions of IL-12, IL-23, and iNOS when RAW264.7 macrophages were treated with gingipain extracts plus Ec-LPS or Pg-LPS and PMX-53, while PMX-53 decreased expressions of TNF-α, IL-1β, and IL-6. Changes of CD86-positive macrophages were consistent with cytokine changes. Our data indicate that gingipain is a critical regulator, more like a promoter to manipulate M1 macrophage polarization in order to benefit P. gingivalis infection through the C5a pathway.
Insights
Gingipains from Porphyromonas gingivalis manipulate M1 macrophage polarization, promoting infection. This occurs via the complement component 5a (C5a) pathway, influencing cytokine expression and macrophage surface markers.
Area of Science:
- Immunology
- Microbiology
- Periodontal disease
Background:
- Porphyromonas gingivalis (Pg) is a key pathogen in periodontitis.
- Gingipains, virulence factors secreted by Pg, are implicated in host immune modulation.
- Macrophage polarization, particularly M1 phenotype, is crucial in inflammatory responses.
Purpose of the Study:
- To investigate the effect of gingipains on M1 macrophage polarization.
- To determine if these effects are mediated through the complement component 5a (C5a) pathway.
- To analyze changes in cytokine expression and surface markers associated with M1 polarization.
Main Methods:
- Mouse RAW264.7 macrophages were treated with gingipain extracts, Escherichia coli lipopolysaccharides (Ec-LPS), or Pg-LPS.
- The C5a receptor antagonist PMX-53 was used to block the C5a pathway.
- Gene and protein expression of key cytokines (IL-12, IL-23, iNOS, IL-10, TNF-α, IL-1β, IL-6) were measured via qRT-PCR and ELISA.
- M1 (CD86) and M2 (CD206) surface markers were assessed by flow cytometry.
Main Results:
- Gingipain extracts alone upregulated pro-inflammatory cytokines (IL-12, IL-23, iNOS, TNF-α, IL-1β, IL-6) and M1 markers.
- In combination with Ec-LPS or Pg-LPS, gingipain modulated cytokine expression, often enhancing Pg-LPS-induced M1 polarization.
- Blocking the C5a pathway with PMX-53 reversed some of the gingipain-induced pro-inflammatory cytokine increases, suggesting C5a pathway involvement.
- Changes in CD86-positive M1 macrophages correlated with observed cytokine expression patterns.
Conclusions:
- Gingipains act as critical regulators, promoting M1 macrophage polarization to favor P. gingivalis infection.
- The C5a pathway is a key mechanism through which gingipains exert their influence on macrophage polarization.
- Targeting gingipains or the C5a pathway may offer therapeutic strategies for periodontitis.
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