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Targeting of a Fixed Bacterial Immunogen to Fc Receptors Reverses the Anti-Inflammatory Properties of the Gram-Negative Bacterium, Francisella tularensis, during the Early Stages of Infection.

Babadjanova Z, Wiedinger K, Gosselin EJ, Bitsaktsis C - PLoS ONE (2015)

Bottom Line: It is well established that IL-10 has the ability to inhibit robust antigen presentation by dendritic cells and macrophages, thus suppressing the generation of protective immunity.The pathogenesis of F. tularensis is not fully understood, and research has failed to develop an effective vaccine to this date.These results provide important insight for further understanding the protective immune mechanisms generated when targeting immunogens to Fc receptors.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Seton Hall University, South Orange, New Jersey, United States of America.

ABSTRACT
Production of pro-inflammatory cytokines by innate immune cells at the early stages of bacterial infection is important for host protection against the pathogen. Many intracellular bacteria, including Francisella tularensis, the agent of tularemia, utilize the anti-inflammatory cytokine IL-10, to evade the host immune response. It is well established that IL-10 has the ability to inhibit robust antigen presentation by dendritic cells and macrophages, thus suppressing the generation of protective immunity. The pathogenesis of F. tularensis is not fully understood, and research has failed to develop an effective vaccine to this date. In the current study, we hypothesized that F. tularensis polarizes antigen presenting cells during the early stages of infection towards an anti-inflammatory status characterized by increased synthesis of IL-10 and decreased production of IL-12p70 and TNF-α in an IFN-ɣ-dependent fashion. In addition, F. tularensis drives an alternative activation of alveolar macrophages within the first 48 hours post-infection, thus allowing the bacterium to avoid protective immunity. Furthermore, we demonstrate that targeting inactivated F. tularensis (iFt) to Fcγ receptors (FcɣRs) via intranasal immunization with mAb-iFt complexes, a proven vaccine strategy in our laboratories, reverses the anti-inflammatory effects of the bacterium on macrophages by down-regulating production of IL-10. More specifically, we observed that targeting of iFt to FcγRs enhances the classical activation of macrophages not only within the respiratory mucosa, but also systemically, at the early stages of infection. These results provide important insight for further understanding the protective immune mechanisms generated when targeting immunogens to Fc receptors.

No MeSH data available.


Related in: MedlinePlus

Administration of mAb-iFt immune complexes reverses the anti-inflammatory properties of LVS in mouse PECs ex vivo.C57BL/6 mice were immunized i.n. with PBS, iFt (2x107 CFUs), or mAb-iFt, boosted on day 21 and challenged on day 35 with 10,000 CFUs of Ft LVS. After 48 hours post—LVS challenge, the PECs of immunized mice were harvested and cultured in the presence or absence of Ft. LVS at 1:10 and 1:100 MOI for 24 hrs. The cytokine production was measured as previously described. Results are representative of three independent experiments. (*) P-value < 0.1; (**) P-value < 0.05; bars represent the SD.
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pone.0129981.g001: Administration of mAb-iFt immune complexes reverses the anti-inflammatory properties of LVS in mouse PECs ex vivo.C57BL/6 mice were immunized i.n. with PBS, iFt (2x107 CFUs), or mAb-iFt, boosted on day 21 and challenged on day 35 with 10,000 CFUs of Ft LVS. After 48 hours post—LVS challenge, the PECs of immunized mice were harvested and cultured in the presence or absence of Ft. LVS at 1:10 and 1:100 MOI for 24 hrs. The cytokine production was measured as previously described. Results are representative of three independent experiments. (*) P-value < 0.1; (**) P-value < 0.05; bars represent the SD.

Mentions: One of the critical immune responses to bacterial infection is the synthesis and release of pro-inflammatory cytokines by innate immune cells during the early stages of infection [1–3]. Given the ability of F. tularensis to evade the immune system by favoring the short-term secretion of anti-inflammatory cytokines [12, 27], it was of interest to investigate the cytokine levels produced by PECs at the early stages of infection. Therefore, we analyzed the production of inflammatory cytokines IL-12p70 and TNF-α as well as the anti-inflammatory cytokine IL-10 using PECs from immunized and subsequently challenged mice. On day 35 post-immunization mice were challenged with 10,000 CFU of live F. tularensis LVS and cells were isolated two days post-infection. PECs were further stimulated with LVS ex vivo (at 1:10 and 1:100 MOI) for 24 hours and the cytokine levels in the supernatant were measured by the BD Biosciences Cytometric Bead Array (CBA). We observed that the levels of IL-12p70 (Fig 1A) and TNF-α (Fig 1B) in supernatants from PECs of mAb-iFt immunized mice were significantly higher (two to three fold) in comparison to mice immunized with iFt alone. By contrast, the levels of IL-10 production were 2-fold lower in the mAb-iFt compared to mice immunized with iFt alone (Fig 1C) independent of the MOI tested.


Targeting of a Fixed Bacterial Immunogen to Fc Receptors Reverses the Anti-Inflammatory Properties of the Gram-Negative Bacterium, Francisella tularensis, during the Early Stages of Infection.

Babadjanova Z, Wiedinger K, Gosselin EJ, Bitsaktsis C - PLoS ONE (2015)

Administration of mAb-iFt immune complexes reverses the anti-inflammatory properties of LVS in mouse PECs ex vivo.C57BL/6 mice were immunized i.n. with PBS, iFt (2x107 CFUs), or mAb-iFt, boosted on day 21 and challenged on day 35 with 10,000 CFUs of Ft LVS. After 48 hours post—LVS challenge, the PECs of immunized mice were harvested and cultured in the presence or absence of Ft. LVS at 1:10 and 1:100 MOI for 24 hrs. The cytokine production was measured as previously described. Results are representative of three independent experiments. (*) P-value < 0.1; (**) P-value < 0.05; bars represent the SD.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482730&req=5

pone.0129981.g001: Administration of mAb-iFt immune complexes reverses the anti-inflammatory properties of LVS in mouse PECs ex vivo.C57BL/6 mice were immunized i.n. with PBS, iFt (2x107 CFUs), or mAb-iFt, boosted on day 21 and challenged on day 35 with 10,000 CFUs of Ft LVS. After 48 hours post—LVS challenge, the PECs of immunized mice were harvested and cultured in the presence or absence of Ft. LVS at 1:10 and 1:100 MOI for 24 hrs. The cytokine production was measured as previously described. Results are representative of three independent experiments. (*) P-value < 0.1; (**) P-value < 0.05; bars represent the SD.
Mentions: One of the critical immune responses to bacterial infection is the synthesis and release of pro-inflammatory cytokines by innate immune cells during the early stages of infection [1–3]. Given the ability of F. tularensis to evade the immune system by favoring the short-term secretion of anti-inflammatory cytokines [12, 27], it was of interest to investigate the cytokine levels produced by PECs at the early stages of infection. Therefore, we analyzed the production of inflammatory cytokines IL-12p70 and TNF-α as well as the anti-inflammatory cytokine IL-10 using PECs from immunized and subsequently challenged mice. On day 35 post-immunization mice were challenged with 10,000 CFU of live F. tularensis LVS and cells were isolated two days post-infection. PECs were further stimulated with LVS ex vivo (at 1:10 and 1:100 MOI) for 24 hours and the cytokine levels in the supernatant were measured by the BD Biosciences Cytometric Bead Array (CBA). We observed that the levels of IL-12p70 (Fig 1A) and TNF-α (Fig 1B) in supernatants from PECs of mAb-iFt immunized mice were significantly higher (two to three fold) in comparison to mice immunized with iFt alone. By contrast, the levels of IL-10 production were 2-fold lower in the mAb-iFt compared to mice immunized with iFt alone (Fig 1C) independent of the MOI tested.

Bottom Line: It is well established that IL-10 has the ability to inhibit robust antigen presentation by dendritic cells and macrophages, thus suppressing the generation of protective immunity.The pathogenesis of F. tularensis is not fully understood, and research has failed to develop an effective vaccine to this date.These results provide important insight for further understanding the protective immune mechanisms generated when targeting immunogens to Fc receptors.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Seton Hall University, South Orange, New Jersey, United States of America.

ABSTRACT
Production of pro-inflammatory cytokines by innate immune cells at the early stages of bacterial infection is important for host protection against the pathogen. Many intracellular bacteria, including Francisella tularensis, the agent of tularemia, utilize the anti-inflammatory cytokine IL-10, to evade the host immune response. It is well established that IL-10 has the ability to inhibit robust antigen presentation by dendritic cells and macrophages, thus suppressing the generation of protective immunity. The pathogenesis of F. tularensis is not fully understood, and research has failed to develop an effective vaccine to this date. In the current study, we hypothesized that F. tularensis polarizes antigen presenting cells during the early stages of infection towards an anti-inflammatory status characterized by increased synthesis of IL-10 and decreased production of IL-12p70 and TNF-α in an IFN-ɣ-dependent fashion. In addition, F. tularensis drives an alternative activation of alveolar macrophages within the first 48 hours post-infection, thus allowing the bacterium to avoid protective immunity. Furthermore, we demonstrate that targeting inactivated F. tularensis (iFt) to Fcγ receptors (FcɣRs) via intranasal immunization with mAb-iFt complexes, a proven vaccine strategy in our laboratories, reverses the anti-inflammatory effects of the bacterium on macrophages by down-regulating production of IL-10. More specifically, we observed that targeting of iFt to FcγRs enhances the classical activation of macrophages not only within the respiratory mucosa, but also systemically, at the early stages of infection. These results provide important insight for further understanding the protective immune mechanisms generated when targeting immunogens to Fc receptors.

No MeSH data available.


Related in: MedlinePlus