Enhancing BCG Vaccine Efficacy

• 25 Sep 2019

A recent study has found that curcumin in nanoparticle form has the potential to enhance the efficacy of Bacille Calmette-Guérin (BCG) vaccine, used against Tuberculosis (TB).

Curcumin

• Curcumin is the active ingredient of the dietary spice turmeric (Curcuma longa) and has been consumed for medicinal purposes for thousands of years.
• It has a wide range of applications such as antibacterial activity, anti-inflammatory, anti-oxidant, chemotherapeutic, anti-proliferative, wound healing, antiparasitic, anti-malarial, diabetes, obesity, neurologic, psychiatric disorders and cancer, as well as chronic illnesses affecting the eyes, lungs, etc.
• Although curcumin has shown therapeutic efficacy against many human ailments, one of the major problems with curcumin is its poor bioavailability.
• One of the promising approaches to increase the bioavailability of curcumin include the use of nanoparticles.

Lacuna in BCG Vaccine

• BCG vaccine is effective against disseminated and meningeal TB in young children.
• The vaccine induces two types of immune cells — effector memory T cells and central memory T cells.
• The effector memory T cells play a crucial role in mounting an immediate immune response against virulent TB bacteria and also kill them.
• The central memory T cells help in long-term protection in children. But, after persisting for some time, the central memory cells ultimately diminish. As a result, the protection does not last beyond childhood and adults become vulnerable to TB infection despite BCG vaccination.

Curcumin in Nanoparticle Form & Enhanced Efficiency

• One way of enhancing the efficacy of the BCG vaccine is by increasing the number of central memory cells so they last longer and confer protection for a longer duration.
• The researchers found that injecting curcumin nanoparticles, soon after vaccinating the mice with BCG, produced an appreciable enhancement of the central memory T cells.
• Curcumin also helps in the activation of innate immune cells known as macrophages and dendritic cells. TB bacteria reside and grow inside the macrophages. But once activated by curcumin nanoparticles, macrophages and dendritic cells clear the bacteria.
• It enhances the level of TB-specific acquired immune cells (Th1 and Th17 cells) and simultaneously reduces the level of certain other cells (Th2 and Tregs) thus improving the efficacy of the BCG vaccine.
  
  • After TB infection, the levels of Th2 and Tregs cells increase and they inhibit the host-protective effect of Th1 and Th17 responses.
• It, in a way confers protection against adult pulmonary TB.

Source: TH