Mesoporous Silica Nanoparticles as a Potential Platform for Vaccine Development against Tuberculosis.

The increasing emergence of new strains of Mycobacterium tuberculosis (Mtb) highly resistant to antibiotics constitute a public health issue, since tuberculosis still constitutes the primary cause of death in the world due to bacterial infection. Mtb has been shown to produce membrane-derived extracellular vesicles (EVs) containing proteins responsible for modulating the pathological immune response after infection. These natural vesicles were considered a promising alternative to the development of novel vaccines. However, their use was compromised by the observed lack of reproducibility between preparations. In this work, with the aim of developing nanosystems mimicking the extracellular vesicles produced by Mtb, mesoporous silica nanoparticles (MSNs) have been used as nanocarriers of immunomodulatory and vesicle-associated proteins (Ag85B, LprG and LprA). These novel nanosystems have been designed and extensively characterized, demonstrating the effectiveness of the covalent anchorage of the immunomodulatory proteins to the surface of the MSNs. The immunostimulatory capacity of the designed nanosystems has been demonstrated by measuring the levels of pro- (TNF) and anti-inflammatory (IL-10) cytokines in exposed macrophages. These results open a new possibility for the development of more complex nanosystems, including additional vesicle components or even antitubercular drugs, thus allowing for the combination of immunomodulatory and bactericidal effects against Mtb.