Enhanced Gamma Interferon Responses of Mouse Spleen Cells following Immunotherapy for Tuberculosis Relapse

Abstract

Gamma interferon responses of spleen cells in mice were examined during postchemotherapy relapse of intraperitoneally induced latent tuberculous infection. The mycobacterial extract RUTI, which prevented the relapse, significantly enhanced the immune responses to secreted and structural recombinant mycobacterial antigens, suggesting that RUTI-mediated protection was mediated by activated T cells.The aim of this study was to assess the mechanisms of the vaccine RUTI as an adjunct to chemotherapy, in a latent tuberculosis experimental model based on the intraperitoneal (IP) infection of mice (6).RUTI has already demonstrated a protective effect in a low-dose aerosol model, inducing a large and fast immune response against antigens secreted by actively growing Mycobacterium tuberculosis bacilli (2, 4). Given the long period required to test this therapeutic approach using the aerosol model, the IP model could be a reliable one to test new immunotherapeutic candidates.Specific-pathogen-free, 7-week-old C57BL/6 female mice were treated by using procedures approved and supervised by the Animal Care Committee of the Germans Trias i Pujol University Hospital. M. tuberculosis strain H37Rv Pasteur was grown in Proskauer Beck medium containing 0.01% Tween 80 (9) to mid-log phase and stored at Ϫ70°C in 2-ml aliquots. Mice were vaccinated subcutaneously twice, at weeks 9 and 11, with RUTI, which consists of liposome-based detoxified fragments of M. tuberculosis cells, cultured under stress conditions and under good manufacturing procedure quality control by Archivel Farma (Badalona, Catalonia, Spain) (2).Mice were infected with 1 ϫ 10 5 CFU M. tuberculosis by IP injection and divided into three groups: the control group, infected but not treated; the chemotherapy-treated group (receiving 25 mg/kg of body weight isoniazid plus 10 mg/kg rifapentin once a week from week 3 to week 9 postinfection); and the vaccinated group, which received two RUTI inoculations after the chemotherapy, at weeks 9 and 11 after infection.The animals were euthanized with an overdose of isofluorane at week 13 postinfection, and the spleens were harvested. Viable bacteria (CFU) were counted four weeks after the spleen homogenates were plated on 7H11 Middlebrook agar (Biomedics s.l., Madrid, Spain) and incubated at 37°C. Data were recorded as the log 10 of the mean number of bacteria recovered per organ. The antigen-stimulated numbers of gamma interferon (IFN-␥)-secreting cells (in spot forming units [SFU] per 1 · 10 6 splenocytes; enzyme-linked immunospot assay [ELISPOT]) and levels of IFN-␥ production (in pg/ml; enzyme-linked immunosorbent assay [ELISA]) were determined after the splenocytes were stimulated for 18 and 96 h with 15 different recombinant antigens, purified protein derivative (10g/ml), or Mycobacterium bovis BCG (10 6 CFU), both purchased at SSI, Denmark. The M. tuberculosis antigens, comprising ESAT-6 (Rv3875), CFP-10 (Rv3874), MPT64 (Rv1980c), Ag 85B (Rv1886c), Ag 16kDa (Rv2031c), Ag 19kDa(Rv3763), Ag 38kDa (Rv0934), Ag 40kDa (Rv2780)...

Efficacy of RUTI® immunotherapy against active tuberculosis in a mouse model challenges the Koch phenomenon

“…We have observed two different mechanisms in RUTI R vaccination that can explain its activity. On one hand, it keeps the immune response against ESAT-6, as has been previously demonstrated (24), a response linked to the presence of active growing bacilli (25), which attends to the reduction of the bacillary load and means that it keeps the surveillance against this type of bacilli, stopping the emergence of new lesions, a fact supported by the reduction of the granulomatous infiltration. On the other hand, when given in combination with HRZE, RUTI R increases the immunity against antigens related to dormant bacilli (HSP16.3 and PsTS1) (26), thus enhancing the surveillance against this bacillary population.…”

Prophylactic Effect of a Therapeutic Vaccine against TB Based on Fragments of Mycobacterium tuberculosis

“…RUTI® is based on fragmented cells of M. tuberculosis , with the product being pasteurized, lyophilized and liposomed to allow better antigen presentation [4] , and has demonstrated its immunogenicity against antigens traditionally related to the stationary phase of the bacilli (Rv 2031c, Rv 0934) [13] . The safety and efficacy of this vaccine have been tested in numerous experiments conducted in mice, guinea pigs, goats and minipigs, and the vaccine finally entered clinical development in 2007 [14] , [15] , [16] , [17] . The phase 1 clinical trial (CT) proved it to be safe and immunogenic, thus allowing RUTI® to be evaluated in the context of a phase 2 CT, which began in South Africa at the second half of 2010 [18] .…”

Vaccines for TB: Lessons from the Past Translating into Future Potentials

“…RUTI extract has successfully elicited the pronounced immune responses caused by the recombinant mycobacterial antigens [ 70 ]. Significant protection was demonstrated in the mice sera treated with RUTI regimen in SCID mice [ 71 ].…”