Chemokine gene expression in lung CD8 T cells correlates with protective immunity in mice immunized intra-nasally with Adenovirus-85A

Abstract

BackgroundImmunization of BALB/c mice with a recombinant adenovirus expressing Mycobacterium tuberculosis (M. tuberculosis) antigen 85A (Ad85A) protects against aerosol challenge with M. tuberculosis only when it is administered intra-nasally (i.n.). Immunization with Ad85A induces a lung-resident population of activated CD8 T cells that is antigen dependent, highly activated and mediates protection by early inhibition of M. tuberculosis growth. In order to determine why the i.n. route is so effective compared to parenteral immunization, we used microarray analysis to compare gene expression profiles of pulmonary and splenic CD8 T cells after i.n. or intra-dermal (i.d.) immunization.MethodTotal RNA from CD8 T cells was isolated from lungs or spleens of mice immunized with Ad85A by the i.n. or i.d. route. The gene profiles generated from each condition were compared. Statistically significant (p ≤ 0.05) differentially expressed genes were analyzed to determine if they mapped to particular molecular functions, biological processes or pathways using Gene Ontology and Panther DB mapping tools.ResultsCD8 T cells from lungs of i.n. immunized mice expressed a large number of chemokines chemotactic for resting and activated T cells as well as activation and survival genes. Lung lymphocytes from i.n. immunized mice also express the chemokine receptor gene Cxcr6, which is thought to aid long-term retention of antigen-responding T cells in the lungs. Expression of CXCR6 on CD8 T cells was confirmed by flow cytometry.ConclusionsOur microarray analysis represents the first ex vivo study comparing gene expression profiles of CD8 T cells isolated from distinct sites after immunization with an adenoviral vector by different routes. It confirms earlier phenotypic data indicating that lung i.n. cells are more activated than lung i.d. CD8 T cells. The sustained expression of chemokines and activation genes enables CD8 T cells to remain in the lungs for extended periods after i.n. immunization. This may account for the early inhibition of M. tuberculosis growth observed in Ad85A i.n. immunized mice and explain the effectiveness of i.n. compared to parenteral immunization with this viral vector.

Coinfection with Streptococcus pneumoniae Negatively Modulates the Size and Composition of the Ongoing Influenza-Specific CD8+ T Cell Response

“…While not yet evaluated, it is also possible that chemokine production is dysregulated in influenza-specific effector cells. CD8 + T cells can produce a number of chemokines that regulate the recruitment and function of a broad array of cells (53, 54). In disease processes where individuals survive past the initial phase of bacterial infection (24–48h), as is the case in our model, a reduction in cytokines/chemokines has the potential to significantly impact ongoing inflammation and/or the response to tissue damage.…”

CXCR6 Is a Marker for Protective Antigen-Specific Cells in the Lungs after Intranasal Immunization against Mycobacterium tuberculosis

“…immunization with Ad85A. BALB/c mice immunized with Ad85A i.n., but not i.d., showed a statistically significant reduction in mycobacterial load following pulmonary M. tuberculosis challenge (Table 1) (26,40). Since microarray analysis of CD8 T cells isolated from the lungs of mice immunized with Ad85A i.n.…”

“…immunized mice showed enhanced expression of several tissue-targeting chemokines and a single chemokine receptor, CXCR6, compared to lung CD8 T cells from i.d. immunized mice (26).…”

Persistence in Temporary Lung Niches: A Survival Strategy of Lung-Resident Memory CD8+T Cells

“…It has also been reported that CXCR6 + memory CD8 + T cells accumulate in the lung following intranasal, but not intradermal delivery of antigen (72,73). In fact, the expression of CXCL16 is strongly enhanced in response to inflammatory stimuli, thereby accelerating the active re-cruitment of effector T cells into inflamed tissues (2,38,85).…”