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Lipidated promiscuous peptide augments the expression of MHC-II molecules on dendritic cells and activates T cells.

Gowthaman U, Rai PK, Zeng W, Jackson DC, Agrewala JN - Indian J. Med. Res. (2013)

Bottom Line: L91 did not elicit anti-peptide antibodies.As L91 does not provoke the generation of anti-peptide antibodies, there is no fear of the efficacy of the vaccine being neutralized by pre-existing anti-mycobacterial antibodies in TB-endemic population.In conclusion, L91 may be considered as a future potential candidate vaccine against TB.

View Article: PubMed Central - PubMed

Affiliation: CSIR-Institute of Microbial Technology, Chandigarh, India.

ABSTRACT

Background & objectives: In spite of the fact that BCG is the most widely used vaccine, tuberculosis (TB) continues to be a major killer disease in TB-endemic regions. Recently, many emerging evidences from the published literature indicate the role of environmental mycobacteria in blocking the processing and presentation of BCG antigens and thereby impairing with suboptimal generation of protective T cells. To surmount this problem associated with BCG, we constructed a novel lipopeptide (L91) by conjugating a promiscuous peptide consisting of CD4 + T-helper epitope of sequence of 91-110 of 16 kDa antigen of Mycobacterium tuberculosis to Pam2Cys, an agonist of Toll-like receptor-2.

Methods: Mice were immunized subcutaneously with 20 nmol of L91, followed by a booster with 10 nmol, after an interval of 21 days of primary immunization. Animals were sacrificed after seven days of post-booster immunization. L91 induced immune response was characterized by the expression of MHC-II and CD74 on the surface of dendritic cells (DCs) by flowcytometry. Cytokines (IL-4, IL-10, IFN-γ) secretion and anti-peptide antibodies were measured by ELISA.

Results: Self-adjuvanting lipopeptide vaccine (L91) was directly bound to MHC-II molecules and without requiring extensive processing for its presentation to T cells. It stimulated and activated dendritic cells and augmented the expression of MHC-II molecules. Further, it activated effector CD4 T cells to mainly secrete interferon (IFN)-γ but not interleukin (IL)-4 and IL-10. L91 did not elicit anti-peptide antibodies.

Interpretation & conclusions: The findings suggest that L91 evokes maturation and upregulation of MHC class II molecules and promotes better antigen presentation and, therefore, optimum activation of T cells. L91 mainly induces effector Th1 cells, as evidenced by predominant release of IFN-γ, consequently can mount favourable immune response against M. tuberculosis . As L91 does not provoke the generation of anti-peptide antibodies, there is no fear of the efficacy of the vaccine being neutralized by pre-existing anti-mycobacterial antibodies in TB-endemic population. In conclusion, L91 may be considered as a future potential candidate vaccine against TB.

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Related in: MedlinePlus

L91 elicits Th1 but not Th2 response. The cells obtained from immunized mice were cultured with L91, F91, Pam2Cys or medium alone for 48 h. Secretion of cytokines in the culture supernatants was measured by ELISA. The results depicted as bar diagrams show the change in ratio of (a) IFN-γ and IL-4; (b) IFN-γ and IL-10. Data are expressed as the mean ± SD and are pooled data from 3 independent experiments with 3-4 mice per group. **P<0.003.
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Figure 2: L91 elicits Th1 but not Th2 response. The cells obtained from immunized mice were cultured with L91, F91, Pam2Cys or medium alone for 48 h. Secretion of cytokines in the culture supernatants was measured by ELISA. The results depicted as bar diagrams show the change in ratio of (a) IFN-γ and IL-4; (b) IFN-γ and IL-10. Data are expressed as the mean ± SD and are pooled data from 3 independent experiments with 3-4 mice per group. **P<0.003.

Mentions: L91 immunization elicits secretion of IFN-γ: The role of Th1 cells and the cytokine IFN-γ has been very well established in protection against TB13. In contrast, Th2 cells and their associated cytokines (IL-4, IL-10) are correlated with the progression of disease13. Therefore, the production of Th1 and Th2-like cytokines was monitored in the mice immunized with L91 or F91. It was of interest to note that L91 significantly (P<0.003) augmented release of IFN-γ by effector T cells when compared to IL-4 and IL-10 (Fig. 2a, b). We did not observe much secretion of cytokines in the cells pulsed with F91 or Pam2Cys.


Lipidated promiscuous peptide augments the expression of MHC-II molecules on dendritic cells and activates T cells.

Gowthaman U, Rai PK, Zeng W, Jackson DC, Agrewala JN - Indian J. Med. Res. (2013)

L91 elicits Th1 but not Th2 response. The cells obtained from immunized mice were cultured with L91, F91, Pam2Cys or medium alone for 48 h. Secretion of cytokines in the culture supernatants was measured by ELISA. The results depicted as bar diagrams show the change in ratio of (a) IFN-γ and IL-4; (b) IFN-γ and IL-10. Data are expressed as the mean ± SD and are pooled data from 3 independent experiments with 3-4 mice per group. **P<0.003.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928704&req=5

Figure 2: L91 elicits Th1 but not Th2 response. The cells obtained from immunized mice were cultured with L91, F91, Pam2Cys or medium alone for 48 h. Secretion of cytokines in the culture supernatants was measured by ELISA. The results depicted as bar diagrams show the change in ratio of (a) IFN-γ and IL-4; (b) IFN-γ and IL-10. Data are expressed as the mean ± SD and are pooled data from 3 independent experiments with 3-4 mice per group. **P<0.003.
Mentions: L91 immunization elicits secretion of IFN-γ: The role of Th1 cells and the cytokine IFN-γ has been very well established in protection against TB13. In contrast, Th2 cells and their associated cytokines (IL-4, IL-10) are correlated with the progression of disease13. Therefore, the production of Th1 and Th2-like cytokines was monitored in the mice immunized with L91 or F91. It was of interest to note that L91 significantly (P<0.003) augmented release of IFN-γ by effector T cells when compared to IL-4 and IL-10 (Fig. 2a, b). We did not observe much secretion of cytokines in the cells pulsed with F91 or Pam2Cys.

Bottom Line: L91 did not elicit anti-peptide antibodies.As L91 does not provoke the generation of anti-peptide antibodies, there is no fear of the efficacy of the vaccine being neutralized by pre-existing anti-mycobacterial antibodies in TB-endemic population.In conclusion, L91 may be considered as a future potential candidate vaccine against TB.

View Article: PubMed Central - PubMed

Affiliation: CSIR-Institute of Microbial Technology, Chandigarh, India.

ABSTRACT

Background & objectives: In spite of the fact that BCG is the most widely used vaccine, tuberculosis (TB) continues to be a major killer disease in TB-endemic regions. Recently, many emerging evidences from the published literature indicate the role of environmental mycobacteria in blocking the processing and presentation of BCG antigens and thereby impairing with suboptimal generation of protective T cells. To surmount this problem associated with BCG, we constructed a novel lipopeptide (L91) by conjugating a promiscuous peptide consisting of CD4 + T-helper epitope of sequence of 91-110 of 16 kDa antigen of Mycobacterium tuberculosis to Pam2Cys, an agonist of Toll-like receptor-2.

Methods: Mice were immunized subcutaneously with 20 nmol of L91, followed by a booster with 10 nmol, after an interval of 21 days of primary immunization. Animals were sacrificed after seven days of post-booster immunization. L91 induced immune response was characterized by the expression of MHC-II and CD74 on the surface of dendritic cells (DCs) by flowcytometry. Cytokines (IL-4, IL-10, IFN-γ) secretion and anti-peptide antibodies were measured by ELISA.

Results: Self-adjuvanting lipopeptide vaccine (L91) was directly bound to MHC-II molecules and without requiring extensive processing for its presentation to T cells. It stimulated and activated dendritic cells and augmented the expression of MHC-II molecules. Further, it activated effector CD4 T cells to mainly secrete interferon (IFN)-γ but not interleukin (IL)-4 and IL-10. L91 did not elicit anti-peptide antibodies.

Interpretation & conclusions: The findings suggest that L91 evokes maturation and upregulation of MHC class II molecules and promotes better antigen presentation and, therefore, optimum activation of T cells. L91 mainly induces effector Th1 cells, as evidenced by predominant release of IFN-γ, consequently can mount favourable immune response against M. tuberculosis . As L91 does not provoke the generation of anti-peptide antibodies, there is no fear of the efficacy of the vaccine being neutralized by pre-existing anti-mycobacterial antibodies in TB-endemic population. In conclusion, L91 may be considered as a future potential candidate vaccine against TB.

Show MeSH
Related in: MedlinePlus