RecombinantMycobacterium bovisbacillus Calmette-Guérin (BCG) expressing mouse IL-18 augments Th1 immunity and macrophage cytotoxicity

Abstract

SUMMARY has been demonstrated to synergize with BCG for induction of a T-helper-type 1 (Th1) immune response. Since successful treatment of superficial bladder cancer with BCG requires proper induction of Th1 immunity, we have developed a recombinant (r) BCG strain that functionally secretes mouse (m) IL-18. This rBCG-mIL-18 strain significantly increased production of the major Th1 cytokine IFN-g in splenocyte cultures, at levels comparable to that elicited by control BCG plus exogenous rIL-18. IFN-g production by splenocytes was eliminated by addition of neutralizing anti-IL-18 antibody. Endogenous IL-12 played a favourable role whereas IL-10 played an adverse role in rBCGmIL-18-induced IFN-g production. Enhanced host antimycobacterial immunity was observed in mice infected with rBCG-mIL-18 which showed less splenic enlargement and reduced bacterial load compared to control mice infected with BCG. Further, splenocytes from rBCG-mIL-18-infected mice, in response to BCG antigen, displayed increased production of IFN-g and GMCSF, decreased production of IL-10, elevated cellular proliferation and higher differentiation of IFN-g -secreting cells. rBCG-mIL-18 also enhanced BCG-induced macrophage cytotoxicity against bladder cancer MBT-2 cells in a dosedependent manner. Neutralizing all endogenous macrophage-derived cytokines tested (IL-12, IL-18 and TNF-a ) as well as IFN-g severely diminished the rBCG-mIL-18-induced macrophage cytolytic activity, indicating a critical role for these cytokines in this process. Cytokine analysis for supernatants of macrophage-BCG mixture cultures manifested higher levels of IFN-g and TNF-a in rBCG-mIL-18 cultures than in control BCG cultures. Taken together, this rBCG-mIL-18 strain augments BCG's immunostimulatory property and may serve as a better agent for bladder cancer immunotherapy and antimycobacterial immunization.

Immunomodulatory effects of recombinant BCG expressing MSP-1C ofPlasmodium falciparumon LPS- or LPS+IFN-γ-stimulated J774A.1 cells

“…We demonstrate here for the first time that the rBCG strain increased macrophage phagocytic activity and induced higher production of NO, iNOS, and pro-inflammatory cytokines such as TNF-α and IL-1β than those produced by parent BCG-infected macrophages. The results are consistent with our previous finding 39 and other studies [46][47][48][49][50] demonstrating that a recombinant BCG is more potent in activating macrophages than parental BCG. These findings support our previous data showing that the rBCG vaccine capable of inducing a strong cell mediated and humoral immune responses in animal model.…”

Effects of DNA- and Mycobacterium bovis BCG-Based Delivery of the Flt3 Ligand on Protective Immunity to Mycobacterium tuberculosis

“…While the vaccine has been engineered to secrete immunostimulatory agents, such as cytokines (20,25,27) and, more recently, chemokines (33), we demonstrate here, for the first time, that the hemopoietic growth factor Flt3L can be expressed and secreted by a bacterial system in a functional form (Fig. 3).…”

Modulation of pulmonary DC function by vaccine‐encoded GM‐CSF enhances protective immunity against Mycobacterium tuberculosis infection

“…Several recombinant BCG (rBCG) strains secreting immunepotentiating molecules have been developed with the objective of manipulating the immunological milieu in situ [16][17][18][19]. We have shown that subcutaneous delivery of BCG expressing APC growth factors can improve anti-BCG immunity and in some cases lead to improved protective efficacy; however, these vaccines were unable to improve protection against pulmonary growth of M. tuberculosis in the mouse [18,19].…”