Effect of Potassium-incorporated Titanium Dioxide in an in vitro Granuloma System for Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) infection is characterized by the development of granulomas. New treatment strategies aimed at latent tuberculosis (TB) infection require a model of granuloma formation that mimics the structures occurring in human TB infection. The use of in vitro models to study Mtb granulomas is also important as they provide new insights into TB biology for the evaluation of novel TB treatment approaches. Several studies have demonstrated an antimicrobial activity of titanium dioxide (TiO₂). Here we investigated the effect of using a nanostructured potassium-incorporated titanium dioxide (KTiO_xs) coated surface in an in vitro granuloma system for Mtb infection. Since nanostructures has a higher surface area to act with more biomolecules, leading to enhance the high-performance to kill microbacteria. We utilized human monocytic cell line (THP-1) cultured on collagen matrix and incubated in the presence of 1,25-dihydroxy-vitamin D3 to induce macrophage differentiation. Cells were then exposed to irradiated Mtb and UV-photoactivated discs coated with inert titanium, TiO₂, and KTiO_xs. The appearance of granuloma formation was recorded overtime. We observed an increase in granuloma length and area over time upon Mtb inoculation that peaked at day 6 post-infection and was maximal on day 7 post-infection for KTiO_xs-treated cells. Our findings show that treatment of human macrophages to KTiO_xs enhances granuloma formation upon Mtb infection in an in vitro granuloma system. This study demonstrates the effect of KTiO_xs in the activation of human macrophages against an intracellular pathogen and may prompt future therapeutic strategies for TB.