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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

IL-33 drives alum-induced cytokine production.WT (black bars) and IL-33 KO (white bars) mice (n = 10–15 mice/group) were injected i.p. with PBS or alum mixed with PBS at 1:2 ratio (Alum). Additionally, WT mice (n = 10 mice/group) were injected i.p. with mouse IgG1 isotype control antibody (Ctrl) or ST2-Fc (grey bars) one hour prior to i.p. injection of PBS or alum mixed with PBS at 1:2 ratio. Serum was collected from all groups six hours later for multiplex cytokine analysis. Data are representative of at least two independent experiments. *p < 0.05 and **p < 0.01 and ***p < 0.001 PBS compared to alum (Two-tailed unpaired Student t-test, n.s. = not significant).
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f3: IL-33 drives alum-induced cytokine production.WT (black bars) and IL-33 KO (white bars) mice (n = 10–15 mice/group) were injected i.p. with PBS or alum mixed with PBS at 1:2 ratio (Alum). Additionally, WT mice (n = 10 mice/group) were injected i.p. with mouse IgG1 isotype control antibody (Ctrl) or ST2-Fc (grey bars) one hour prior to i.p. injection of PBS or alum mixed with PBS at 1:2 ratio. Serum was collected from all groups six hours later for multiplex cytokine analysis. Data are representative of at least two independent experiments. *p < 0.05 and **p < 0.01 and ***p < 0.001 PBS compared to alum (Two-tailed unpaired Student t-test, n.s. = not significant).

Mentions: It is known that i.p. injection of alum or IL-33 results in increased serum cytokine levels89101123. Based on the observed release of IL-33 after i.p. injection of alum (Fig. 1a), we compared the cytokine response elicited by alum or IL-33. Serum was obtained from mice six hours post-injection of selected alum or IL-33 concentrations i.p. and cytokines were quantified using a multiplex ELISA. Both alum and IL-33 induced significant dose-dependent increases in IL-5, IL-6, IL-13, G-CSF, KC, MCP-1, MIP-1α and MIP-1β (Fig. 2). Interestingly, IL-33 induced a much more potent IL-13 response while alum showed a greater release of G-CSF. No significant induction of GM-CSF, IFNγ, IL-1α, IL-1β, IL-2, IL-4, IL-7, IL-9, IL-10, IL-12p40, IL-12p70, IL-15, IL-17, IP-10, MIP-2, RANTES or TNF-α was observed at six hours post-injection of alum or IL-33 compared to PBS treated mice (data not shown). Based on the similarity of these cytokine response profiles, we investigated whether the alum-induced increases were mediated by IL-33. To that end, we injected alum in IL-33 KO mice or neutralized IL-33 activity in WT mice using ST2-Fc. Results from these studies showed that of the alum-induced cytokines in WT mice, IL-5, IL-13, MIP-1α and MIP-1β were completely dependent on IL-33 expression while the increase in IL-6, G-CSF, MCP-1 and KC were partially dependent on IL-33 (Fig. 3 and data not shown). IL-33 injection in IL-33 KO mice produced a similar cytokine response as observed in WT mice (data not shown). These results demonstrate that many alum-induced cytokine increases are mediated by IL-33.


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)

IL-33 drives alum-induced cytokine production.WT (black bars) and IL-33 KO (white bars) mice (n = 10–15 mice/group) were injected i.p. with PBS or alum mixed with PBS at 1:2 ratio (Alum). Additionally, WT mice (n = 10 mice/group) were injected i.p. with mouse IgG1 isotype control antibody (Ctrl) or ST2-Fc (grey bars) one hour prior to i.p. injection of PBS or alum mixed with PBS at 1:2 ratio. Serum was collected from all groups six hours later for multiplex cytokine analysis. Data are representative of at least two independent experiments. *p < 0.05 and **p < 0.01 and ***p < 0.001 PBS compared to alum (Two-tailed unpaired Student t-test, n.s. = not significant).
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f3: IL-33 drives alum-induced cytokine production.WT (black bars) and IL-33 KO (white bars) mice (n = 10–15 mice/group) were injected i.p. with PBS or alum mixed with PBS at 1:2 ratio (Alum). Additionally, WT mice (n = 10 mice/group) were injected i.p. with mouse IgG1 isotype control antibody (Ctrl) or ST2-Fc (grey bars) one hour prior to i.p. injection of PBS or alum mixed with PBS at 1:2 ratio. Serum was collected from all groups six hours later for multiplex cytokine analysis. Data are representative of at least two independent experiments. *p < 0.05 and **p < 0.01 and ***p < 0.001 PBS compared to alum (Two-tailed unpaired Student t-test, n.s. = not significant).
Mentions: It is known that i.p. injection of alum or IL-33 results in increased serum cytokine levels89101123. Based on the observed release of IL-33 after i.p. injection of alum (Fig. 1a), we compared the cytokine response elicited by alum or IL-33. Serum was obtained from mice six hours post-injection of selected alum or IL-33 concentrations i.p. and cytokines were quantified using a multiplex ELISA. Both alum and IL-33 induced significant dose-dependent increases in IL-5, IL-6, IL-13, G-CSF, KC, MCP-1, MIP-1α and MIP-1β (Fig. 2). Interestingly, IL-33 induced a much more potent IL-13 response while alum showed a greater release of G-CSF. No significant induction of GM-CSF, IFNγ, IL-1α, IL-1β, IL-2, IL-4, IL-7, IL-9, IL-10, IL-12p40, IL-12p70, IL-15, IL-17, IP-10, MIP-2, RANTES or TNF-α was observed at six hours post-injection of alum or IL-33 compared to PBS treated mice (data not shown). Based on the similarity of these cytokine response profiles, we investigated whether the alum-induced increases were mediated by IL-33. To that end, we injected alum in IL-33 KO mice or neutralized IL-33 activity in WT mice using ST2-Fc. Results from these studies showed that of the alum-induced cytokines in WT mice, IL-5, IL-13, MIP-1α and MIP-1β were completely dependent on IL-33 expression while the increase in IL-6, G-CSF, MCP-1 and KC were partially dependent on IL-33 (Fig. 3 and data not shown). IL-33 injection in IL-33 KO mice produced a similar cytokine response as observed in WT mice (data not shown). These results demonstrate that many alum-induced cytokine increases are mediated by IL-33.

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