Rv0315, a novel immunostimulatory antigen of Mycobacterium tuberculosis, activates dendritic cells and drives Th1 immune responses

Abstract

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) is one of the most deadly infectious diseases, with approximately two million people dying of TB annually. An effective therapeutic method for activating dendritic cells (DCs) and driving Th1 immune responses would improve host defenses and further the development of a TB vaccine. Given the importance of DC maturation in eliciting protective immunity against TB, we investigated whether Rv0315, a newly identified Mtb antigen, can prompt DC maturation. We found that Rv0315 functionally activated DCs by augmenting the expression of the co-stimulatory molecules CD80 and CD86 as well as MHC class I/II molecules. Moreover, it increased DC secretion of the pro-inflammatory cytokines IL-6, IL-1β, and TNF-α. Unlike LPS, however, Rv0315 induced the secretion of IL-12p70, but not IL-10. In addition, Rv0315-treated DCs accelerated the proliferation of CD4(+) and CD8(+) splenic T cells from Mtb-infected mice, with increased levels of IFN-γ, in syngeneic and allogeneic mixed lymphocyte reactions, indicating that Rv0315 contributes to Th1 polarization of the immune response. Importantly, both mitogen-activated protein kinases and nuclear factor κB signaling mediated the expression of DC surface markers and cytokines. Taken together, our results indicate that Rv0315 is a novel DC maturation-inducing antigen that drives T cell immune responses toward Th1 polarization, suggesting that Rv0315 plays a key role in determining the nature of the immune response to TB.

Serodiagnostic Potential of Mycobacterium avium MAV2054 and MAV5183 Proteins

“…Multidimensional fractionation was performed as described previously (19). In brief, the CFP was precipitated with ammonium sulfate (50% and 80% saturation).…”

Mycobacterium paratuberculosis CobT Activates Dendritic Cells via Engagement of Toll-like Receptor 4 Resulting in Th1 Cell Expansion

“…Cytotoxicity Analyses-To investigate the cytotoxic effect of MAP CobT on DCs, the cell death pattern of DCs in 12-well plates (0.5 ϫ 10 6 cells/ml) was analyzed after treatment with 10 g/ml of MAP CobT as recently described (17).…”

“…Cytokine Measurements-A sandwich enzyme-linked immunosorbent assay (ELISA) was used to detect IL-6, IL-1␤, TNF-␣, IFN-␥, IL-4, IL-2, IL-12p70, and IL-10 in culture supernatants as described previously (17).…”

“…Intracellular Cytokine Assays-Intracellular cytokine assays was carried out as previously described (17). Intracellular IL-12p70, IL-10, IL-2, IL-4, and IFN-␥ were detected with fluorescein-conjugated antibodies (BD Biosciences) in a permeation buffer.…”

“…Both OVAspecific CD8 ϩ and CD4 ϩ T cell responders were obtained from splenocytes of OT-1 and OT-2 mice, respectively. These T cells were stained with 1 M carboxyfluorescein diacetate succinimidyl ester (CFSE) (Invitrogen) as previously described (17). DCs (2 ϫ 10 5 cells per well) treated with OVA peptide in the presence of MAP CobT for 24 h were co-cultured with CFSEstained CD8…”