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Active immunization with human interleukin-15 induces neutralizing antibodies in non-human primates

View Article: PubMed Central - PubMed

ABSTRACT

Background: Interleukin-15 is an immunostimulatory cytokine overexpressed in several autoimmune and inflammatory diseases such as Rheumatoid Arthritis, psoriasis and ulcerative colitis; thus, inhibition of IL-15-induced signaling could be clinically beneficial in these disorders. Our approach to neutralize IL-15 consisted in active immunization with structurally modified human IL-15 (mhIL-15) with the aim to induce neutralizing antibodies against native IL-15. In the present study, we characterized the antibody response in Macaca fascicularis, non-human primates that were immunized with a vaccine candidate containing mhIL-15 in Aluminum hydroxide (Alum), Montanide and Incomplete Freund’s Adjuvant.

Results: Immunization with mhIL-15 elicited a specific antibodies response that neutralized native IL-15-dependent biologic activity in a CTLL-2 cell proliferation assay. The highest neutralizing response was obtained in macaques immunized with mhIL-15 adjuvanted in Alum. This response, which was shown to be transient, also inhibited the activity of simian IL-15 and did not affect the human IL-2-induced proliferation of CTLL-2 cells. Also, in a pool of synovial fluid cells from two Rheumatoid Arthritis patients, the immune sera slightly inhibited TNF-α secretion. Finally, it was observed that this vaccine candidate neither affect animal behavior, clinical status, blood biochemistry nor the percentage of IL-15-dependent cell populations, specifically CD56+ NK and CD8+ T cells.

Conclusion: Our results indicate that vaccination with mhIL-15 induced neutralizing antibodies to native IL-15 in non-human primates. Based on this fact, we propose that this vaccine candidate could be potentially beneficial for treatment of diseases where IL-15 overexpression is associated with their pathogenesis.

No MeSH data available.


Related in: MedlinePlus

Recognition and neutralizing capacity of sera from the Alum group in presence of simian IL-15. a ELISA for recognition of simian IL-15 by Abs from sera of immunized macaques. The plate was coated with 1 μg/ml recombinant simian IL-15 and it was incubated with the pool of sera per group diluted 1:4000. b Inhibition of simian IL-15-induced proliferation of CTLL-2 cells by sera from the Alum group. Cells were cultured in the presence of simian IL-15, simian IL-15 plus serial dilutions of serum (starting dilution 1:25) or medium. Cell proliferation was evaluated by MTT staining. All tested sera correspond to 15 days after the third immunization
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Fig5: Recognition and neutralizing capacity of sera from the Alum group in presence of simian IL-15. a ELISA for recognition of simian IL-15 by Abs from sera of immunized macaques. The plate was coated with 1 μg/ml recombinant simian IL-15 and it was incubated with the pool of sera per group diluted 1:4000. b Inhibition of simian IL-15-induced proliferation of CTLL-2 cells by sera from the Alum group. Cells were cultured in the presence of simian IL-15, simian IL-15 plus serial dilutions of serum (starting dilution 1:25) or medium. Cell proliferation was evaluated by MTT staining. All tested sera correspond to 15 days after the third immunization

Mentions: In order to evaluate the recognition of sera from immunized animals on self-IL-15 and their effect on the activity of simian IL-15, we obtained this cytokine by cloning its cDNA upon RNA isolated from PBMC of Macaca fascicularis in E. coli (unpublished results). First, recognition of simian IL-15 by Abs from sera of the Alum group was assessed by ELISA. As illustrated in Fig. 5a, the sera recognized simian IL-15 immobilized on the plate. The OD 450 nm values corresponding to the immunized groups were, at least, 5 times higher than that obtained from the placebo group. In addition, these sera inhibited the activity of simian IL-15 and showed a neutralizing effect in a dose-dependent manner (Fig. 5b). The calculated ID50 values were similar among the three animals (1:831, 1:635 and 1:636).Fig. 5


Active immunization with human interleukin-15 induces neutralizing antibodies in non-human primates
Recognition and neutralizing capacity of sera from the Alum group in presence of simian IL-15. a ELISA for recognition of simian IL-15 by Abs from sera of immunized macaques. The plate was coated with 1 μg/ml recombinant simian IL-15 and it was incubated with the pool of sera per group diluted 1:4000. b Inhibition of simian IL-15-induced proliferation of CTLL-2 cells by sera from the Alum group. Cells were cultured in the presence of simian IL-15, simian IL-15 plus serial dilutions of serum (starting dilution 1:25) or medium. Cell proliferation was evaluated by MTT staining. All tested sera correspond to 15 days after the third immunization
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036325&req=5

Fig5: Recognition and neutralizing capacity of sera from the Alum group in presence of simian IL-15. a ELISA for recognition of simian IL-15 by Abs from sera of immunized macaques. The plate was coated with 1 μg/ml recombinant simian IL-15 and it was incubated with the pool of sera per group diluted 1:4000. b Inhibition of simian IL-15-induced proliferation of CTLL-2 cells by sera from the Alum group. Cells were cultured in the presence of simian IL-15, simian IL-15 plus serial dilutions of serum (starting dilution 1:25) or medium. Cell proliferation was evaluated by MTT staining. All tested sera correspond to 15 days after the third immunization
Mentions: In order to evaluate the recognition of sera from immunized animals on self-IL-15 and their effect on the activity of simian IL-15, we obtained this cytokine by cloning its cDNA upon RNA isolated from PBMC of Macaca fascicularis in E. coli (unpublished results). First, recognition of simian IL-15 by Abs from sera of the Alum group was assessed by ELISA. As illustrated in Fig. 5a, the sera recognized simian IL-15 immobilized on the plate. The OD 450 nm values corresponding to the immunized groups were, at least, 5 times higher than that obtained from the placebo group. In addition, these sera inhibited the activity of simian IL-15 and showed a neutralizing effect in a dose-dependent manner (Fig. 5b). The calculated ID50 values were similar among the three animals (1:831, 1:635 and 1:636).Fig. 5

View Article: PubMed Central - PubMed

ABSTRACT

Background: Interleukin-15 is an immunostimulatory cytokine overexpressed in several autoimmune and inflammatory diseases such as Rheumatoid Arthritis, psoriasis and ulcerative colitis; thus, inhibition of IL-15-induced signaling could be clinically beneficial in these disorders. Our approach to neutralize IL-15 consisted in active immunization with structurally modified human IL-15 (mhIL-15) with the aim to induce neutralizing antibodies against native IL-15. In the present study, we characterized the antibody response in Macaca fascicularis, non-human primates that were immunized with a vaccine candidate containing mhIL-15 in Aluminum hydroxide (Alum), Montanide and Incomplete Freund’s Adjuvant.

Results: Immunization with mhIL-15 elicited a specific antibodies response that neutralized native IL-15-dependent biologic activity in a CTLL-2 cell proliferation assay. The highest neutralizing response was obtained in macaques immunized with mhIL-15 adjuvanted in Alum. This response, which was shown to be transient, also inhibited the activity of simian IL-15 and did not affect the human IL-2-induced proliferation of CTLL-2 cells. Also, in a pool of synovial fluid cells from two Rheumatoid Arthritis patients, the immune sera slightly inhibited TNF-α secretion. Finally, it was observed that this vaccine candidate neither affect animal behavior, clinical status, blood biochemistry nor the percentage of IL-15-dependent cell populations, specifically CD56+ NK and CD8+ T cells.

Conclusion: Our results indicate that vaccination with mhIL-15 induced neutralizing antibodies to native IL-15 in non-human primates. Based on this fact, we propose that this vaccine candidate could be potentially beneficial for treatment of diseases where IL-15 overexpression is associated with their pathogenesis.

No MeSH data available.


Related in: MedlinePlus