Research Report 2010 2011 - Helmholtz-Zentrum für ...

104 SCIENTIFIC REPORTS | Infection and Immunity | Strategies for Prevention and Therapy
04.3 Antigen Delivery Systems and Vaccines
PROJECT LEADER | Prof. Carlos A. Guzmán, M.D., Ph.D. | Department of Vaccinology and Applied Microbiology |
cag@helmholtz-hzi.de
PROJECT MEMBERS | Dr. Pablo D. Becker | Dr. Jennifer Debarry | Dr. Thomas Ebensen | Dr. Miriam Nörder |
Dr. Peggy Riese | Rimma Libanova | Kirsten Scholz | Dr. Kai Schulze | Sebastian Weissmann | Dr. Beata Zygmunt
The main aim of this project is the development of tools and
strategies to optimize the delivery of vaccine antigens, particularly
by the mucosal route, and their subsequent exploitation
for the generation of vaccines against specific diseases.
Improving antigen design Despite the strong immune
responses elicited after natural infection with Trypanosoma
cruzi or vaccination against it, parasite survival in the host
suggests that these responses are insufficient or inherently
inadequate. T. cruzi contains a major cystein proteinase,
cruzipain, which is an attractive candidate vaccine antigen.
We produced full-length recombinant cruzipain (rCz), as
well as truncated forms encompassing its N- and C-terminal
domains. Groups of mice were then immunized with the
recombinant proteins combined with CpG-ODN and Czspecific
antibody responses were measured. The highest
IgG titers were observed in mice vaccinated with either the
C-terminal domain or the full-length protein. In contrast, low
antibody titers were stimulated in mice immunized with the
N-terminal domain, thereby suggesting a parasite immune
escape mechanism by avoiding antibody production against
the catalytic N-terminal domain. Similarly, cellular responses
were poorly restimulated with the N-terminal domain in
mice immunized with full-length rCz, whereas most of the
response was evoked by the C-terminal domain. However, the
cellular responses were much stronger when the N-terminal
domain was used for immunization, suggesting that cellular
responses can be down-regulated by full-length Cz to avoid
recognition of the N-terminal domain. Masking of the essential
domain can be reverted by using the N-terminal domain as
a tailored immunogen to redirect host responses to provide
enhanced protection. In fact, mice immunized with the N-
terminal domain were able to better control infection, resulting
in significant lower parasite loads throughout the acute
phase and limited tissue injury during the chronic phase.
Optimizing vaccination strategies Mucosal vaccination
is an attractive strategy for antigen administration, since
this approach is not associated with pain or stress, has an
extremely easy and cost-efficient administration logistics
and does not require highly trained personnel. However,
although many features of the mucosal immune system
have been dissected, there is an incomplete knowledge on
the effector mechanisms triggered by mucosal vaccination.
In this context, the stimulation of specific T helper (Th)
subsets is critical to promote efficient immunity without
side effects. Thus, we investigated which Th subsets are
preferentially stimulated following intranasal immunization.
In comparison to parenteral immunization we detected
an up-regulation of CCR-6 on CD4+ cells which correlated
with an enhanced production of IL-17. This preferential
induction of Th17 immune response is independent from
the kind of adjuvant used.
(A) Antibody response in mice immunized with full-length rCz
or its domains. . (B) Parasite loads during the acute phase of
T. cruzi infection in vaccinated mice. (C) Micrographs of skeletal
muscle from control mice show severe inflammation (×40),
whereas animals immunized with rCz (D), the C-terminal (E)
and the N-terminal (F) domain show moderate inflammation
with edema (lower and upper arrows, ×10), moderate inflammation
and collagen deposition (upper and lower arrows, ×40)
and mild inflammation (×20), respectively; *P < 0.05, **P <
0.01, ***P < 0.001.
It is known that Th17 cells play a critical role in immune
responses against important respiratory pathogens. Thus,
our observation that a Th17 response pattern is specifically
promoted by intranasal immunization has important implications
in the context of optimizing rational vaccine design.
Cazorla, S. I., Frank, F. M. , Becker, P. D., Arnaiz, M., Mirkin G. A., Corral R. S., Guzmán
C. A*. and Malchiodi E. L.* (2010). Redirection of the immune response to the functional
catalytic domain of the cystein proteinase cruzipain improves protective immunity
against Trypanosoma cruzi infection. Journal of Infectious Diseases. 202:136-144.
*Corresponding authors.
Zygmunt, B. M., Rharbaoui F., Groebe L., and Guzman C. A. (2009). Intranasal immunization
promotes Th17 immune responses. Journal of Immunology. 183:6933-6938.