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IL-33 released by alum is responsible for early cytokine production and has adjuvant properties.

Rose WA, Okragly AJ, Patel CN, Benschop RJ - Sci Rep (2015)

Bottom Line: Alum can induce the release of endogenous danger signals via cellular necrosis which elicits inflammation-associated cytokines resulting in humoral immunity.Furthermore, IL-33 itself functions as an adjuvant that, while only inducing a marginal primary response, facilitates a robust secondary response comparable to that observed with alum.Our results provide novel insights into the mechanism of action behind alum-induced cytokine responses and show that IL-33 is sufficient to provide a robust secondary antibody response independently of alum.

View Article: PubMed Central - PubMed

Affiliation: Biotechnology Discovery Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, 46285.

ABSTRACT
Human vaccines have used aluminium-based adjuvants (alum) for >80 years despite incomplete understanding of how alum enhances the immune response. Alum can induce the release of endogenous danger signals via cellular necrosis which elicits inflammation-associated cytokines resulting in humoral immunity. IL-33 is proposed to be one such danger signal that is released from necrotic cells. Therefore, we investigated whether there is a role for IL-33 in the adjuvant activity of alum. We show that alum-induced cellular necrosis results in elevated levels of IL-33 following injection in vivo. Alum and IL-33 induce similar increases in IL-5, KC, MCP-1, MIP-1α and MIP-1β; many of which are dependent on IL-33 as shown in IL-33 knockout mice or by using an IL-33-neutralizing recombinant ST2 receptor. Furthermore, IL-33 itself functions as an adjuvant that, while only inducing a marginal primary response, facilitates a robust secondary response comparable to that observed with alum. However, IL-33 is not absolutely required for alum-induced antibody responses since alum mediates similar humoral responses in IL-33 knockout and wild-type mice. Our results provide novel insights into the mechanism of action behind alum-induced cytokine responses and show that IL-33 is sufficient to provide a robust secondary antibody response independently of alum.

No MeSH data available.


Related in: MedlinePlus

Addition of DNA did not alter IL-33-induced antibody responses.C57BL/6 mice (n = 5 mice/group) were injected i.p. with PBS, alum mixed with PBS at 1:2 ratio, IL-33 or IL-33 mixed with 8μg mouse genomic DNA in combination with NP-CGG then boosted i.p. on day 14 with PBS/NP-CGG. Antigen specific IgM, IgG1and IgE serum titers were quantified via ELISA. Data are representative of two independent experiments. *p < 0.05 and ***p < 0.001 alum compared to IL-33/DNA groups (Two-way ANOVA with Bonferroni multiple comparison test). ##p < 0.01 IL-33 compared to IL-33/DNA groups (Two-way ANOVA with Bonferroni multiple comparison test).
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f6: Addition of DNA did not alter IL-33-induced antibody responses.C57BL/6 mice (n = 5 mice/group) were injected i.p. with PBS, alum mixed with PBS at 1:2 ratio, IL-33 or IL-33 mixed with 8μg mouse genomic DNA in combination with NP-CGG then boosted i.p. on day 14 with PBS/NP-CGG. Antigen specific IgM, IgG1and IgE serum titers were quantified via ELISA. Data are representative of two independent experiments. *p < 0.05 and ***p < 0.001 alum compared to IL-33/DNA groups (Two-way ANOVA with Bonferroni multiple comparison test). ##p < 0.01 IL-33 compared to IL-33/DNA groups (Two-way ANOVA with Bonferroni multiple comparison test).

Mentions: In addition to alum-induced release of IL-33 via cellular necrosis (Fig. 1a), other endogenous danger signals also could contribute to the adjuvant activity of alum. Marichal et al. showed that alum induced the release of DNA via cellular necrosis and that this was in part responsible for mediating alum adjuvant properties19. Since we showed that IL-33 only recapitulates parts of the effects induced by alum, we tested whether co-injection of mouse genomic DNA (to mimic DNA released from necrotic cells) with IL-33/NP-CGG would result in antibody response profiles that were similar to alum-induced responses. Addition of DNA to IL-33 did not appreciably change the IgM, IgG1 or IgE responses relative to IL-33 alone (Fig. 6). A single noted difference was a significant increase in the IgG1 titer on day 17 for the IL-33/DNA group compared to IL-33 alone. These results demonstrate that addition of DNA to IL-33 during immunizations did not enhance the antibody response to levels equivalent to those observed with alum. Therefore, other endogenous danger signals are likely necessary for mediating the full adjuvant activity of alum.


IL-33 released by alum is responsible for early cytokine production and has adjuvant properties.

Rose WA, Okragly AJ, Patel CN, Benschop RJ - Sci Rep (2015)

Addition of DNA did not alter IL-33-induced antibody responses.C57BL/6 mice (n = 5 mice/group) were injected i.p. with PBS, alum mixed with PBS at 1:2 ratio, IL-33 or IL-33 mixed with 8μg mouse genomic DNA in combination with NP-CGG then boosted i.p. on day 14 with PBS/NP-CGG. Antigen specific IgM, IgG1and IgE serum titers were quantified via ELISA. Data are representative of two independent experiments. *p < 0.05 and ***p < 0.001 alum compared to IL-33/DNA groups (Two-way ANOVA with Bonferroni multiple comparison test). ##p < 0.01 IL-33 compared to IL-33/DNA groups (Two-way ANOVA with Bonferroni multiple comparison test).
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Related In: Results  -  Collection

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f6: Addition of DNA did not alter IL-33-induced antibody responses.C57BL/6 mice (n = 5 mice/group) were injected i.p. with PBS, alum mixed with PBS at 1:2 ratio, IL-33 or IL-33 mixed with 8μg mouse genomic DNA in combination with NP-CGG then boosted i.p. on day 14 with PBS/NP-CGG. Antigen specific IgM, IgG1and IgE serum titers were quantified via ELISA. Data are representative of two independent experiments. *p < 0.05 and ***p < 0.001 alum compared to IL-33/DNA groups (Two-way ANOVA with Bonferroni multiple comparison test). ##p < 0.01 IL-33 compared to IL-33/DNA groups (Two-way ANOVA with Bonferroni multiple comparison test).
Mentions: In addition to alum-induced release of IL-33 via cellular necrosis (Fig. 1a), other endogenous danger signals also could contribute to the adjuvant activity of alum. Marichal et al. showed that alum induced the release of DNA via cellular necrosis and that this was in part responsible for mediating alum adjuvant properties19. Since we showed that IL-33 only recapitulates parts of the effects induced by alum, we tested whether co-injection of mouse genomic DNA (to mimic DNA released from necrotic cells) with IL-33/NP-CGG would result in antibody response profiles that were similar to alum-induced responses. Addition of DNA to IL-33 did not appreciably change the IgM, IgG1 or IgE responses relative to IL-33 alone (Fig. 6). A single noted difference was a significant increase in the IgG1 titer on day 17 for the IL-33/DNA group compared to IL-33 alone. These results demonstrate that addition of DNA to IL-33 during immunizations did not enhance the antibody response to levels equivalent to those observed with alum. Therefore, other endogenous danger signals are likely necessary for mediating the full adjuvant activity of alum.

Bottom Line: Alum can induce the release of endogenous danger signals via cellular necrosis which elicits inflammation-associated cytokines resulting in humoral immunity.Furthermore, IL-33 itself functions as an adjuvant that, while only inducing a marginal primary response, facilitates a robust secondary response comparable to that observed with alum.Our results provide novel insights into the mechanism of action behind alum-induced cytokine responses and show that IL-33 is sufficient to provide a robust secondary antibody response independently of alum.

View Article: PubMed Central - PubMed

Affiliation: Biotechnology Discovery Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, 46285.

ABSTRACT
Human vaccines have used aluminium-based adjuvants (alum) for >80 years despite incomplete understanding of how alum enhances the immune response. Alum can induce the release of endogenous danger signals via cellular necrosis which elicits inflammation-associated cytokines resulting in humoral immunity. IL-33 is proposed to be one such danger signal that is released from necrotic cells. Therefore, we investigated whether there is a role for IL-33 in the adjuvant activity of alum. We show that alum-induced cellular necrosis results in elevated levels of IL-33 following injection in vivo. Alum and IL-33 induce similar increases in IL-5, KC, MCP-1, MIP-1α and MIP-1β; many of which are dependent on IL-33 as shown in IL-33 knockout mice or by using an IL-33-neutralizing recombinant ST2 receptor. Furthermore, IL-33 itself functions as an adjuvant that, while only inducing a marginal primary response, facilitates a robust secondary response comparable to that observed with alum. However, IL-33 is not absolutely required for alum-induced antibody responses since alum mediates similar humoral responses in IL-33 knockout and wild-type mice. Our results provide novel insights into the mechanism of action behind alum-induced cytokine responses and show that IL-33 is sufficient to provide a robust secondary antibody response independently of alum.

No MeSH data available.


Related in: MedlinePlus