Mucosal and systemic immune responses to Mycobacterium tuberculosis antigen 85A following its co-delivery with CpG, MPLA or LTB to the lungs in mice

PLoS One. 2013 May 10;8(5):e63344. doi: 10.1371/journal.pone.0063344. Print 2013.

Abstract

Pulmonary vaccination is a promising route for immunization against tuberculosis because the lung is the natural site of infection with Mycobacterium tuberculosis. Yet, adjuvants with a suitable safety profile need to be found to enhance mucosal immunity to recombinant antigens. The aim of this study was to evaluate the immunogenicity, the safety and the protective efficacy of a subunit vaccine composed of the immunodominant mycolyl-transferase antigen 85A (Ag85A) and one of three powerful mucosal adjuvants: the oligodeoxynucleotide containing unmethylated cytosine-phosphate-guanine motifs (CpG), the monophosphoryl lipid A of Salmonella minnesota (MPLA) or the B subunit of heat-labile enterotoxin of Escherichia coli (LTB). BALB/c mice were vaccinated in the deep lungs. Our results showed that lung administration of these adjuvants could specifically induce different types of T cell immunity. Both CpG and MPLA induced a Th-1 type immune response with significant antigen-specific IFN-γ production by spleen mononuclear cells in vitro and a tendency of increased IFN-γ in the lungs. Moreover, MPLA triggered a Th-17 response reflected by high IL-17A levels in the spleen and lungs. By contrast, LTB promoted a Th-2 biased immune response, with a production of IL-5 but not IFN-γ by spleen mononuclear cells in vitro. CpG did not induce inflammation in the lungs while LTB and MPLA showed a transient inflammation including a neutrophil influx one day after pulmonary administration. Pulmonary vaccination with Ag85A without or with MPLA or LTB tended to decrease bacterial counts in the spleen and lungs following a virulent challenge with M. tuberculosis H37Rv. In conclusion, CpG and MPLA were found to be potential adjuvants for pulmonary vaccination against tuberculosis, providing Th-1 and Th-17 immune responses and a good safety profile.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyltransferases / administration & dosage
  • Acyltransferases / immunology*
  • Adjuvants, Immunologic / administration & dosage
  • Animals
  • Antigens, Bacterial / administration & dosage
  • Antigens, Bacterial / immunology*
  • Biomarkers / metabolism
  • Female
  • Immunity, Cellular
  • Immunity, Humoral
  • Immunity, Mucosal*
  • Inflammation / immunology
  • Inflammation / metabolism
  • Lipid A / administration & dosage
  • Lipid A / analogs & derivatives
  • Lung / immunology*
  • Lung / microbiology
  • Mice
  • Mycobacterium tuberculosis / immunology*
  • Spleen / immunology
  • Tuberculosis / immunology*
  • Tuberculosis / prevention & control
  • Tuberculosis Vaccines / administration & dosage
  • Tuberculosis Vaccines / immunology*
  • Vaccines, Subunit / administration & dosage
  • Vaccines, Subunit / immunology

Substances

  • Adjuvants, Immunologic
  • Antigens, Bacterial
  • Biomarkers
  • Lipid A
  • Tuberculosis Vaccines
  • Vaccines, Subunit
  • Acyltransferases
  • antigen 85A, Mycobacterium tuberculosis
  • monophosphoryl lipid A

Grants and funding

The work was supported by the Fonds de la Recherche Scientifique Médicale (grant number 3.4530.09 FNRS, Belgium; www1.frs-fnrs.be) and by the Fonds National de la Recherche Scientifique (FNRS, Belgium). The work was also partially supported by grant G.0063.09N of FWO-Vlaanderen. Rita Vanbever is Senior research associate of the FNRS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.