RPE cells may harbor latent M tuberculosis

This experimental study aids our understanding of how retinal pigment epithelium (RPE) cells could be the likely site for latent Mycobacterium tuberculosis, as well as for subsequent reactivation and development of posterior uveitis.

It is important because M tuberculosis is a prominent cause of posterior uveitis in tuberculosis (TB)-endemic regions. Clinical and histopathologic evidence suggests that RPE can harbor M tuberculosis. However, the mechanism of M tuberculosis phagocytosis and its growth in RPE is not clear.

In this experimental study, the authors investigated the bacillary phagocytosis, replication and cytopathic effects of M tuberculosis H37Ra attenuated tubercle bacillus in RPE cells compared with macrophages.

The results indicate that M tuberculosis is phagocytized by RPE to a similar extent as in macrophages. However, RPE cells are better able to control bacillary growth, and RPE cell survival is greater than that of THP-1 cells following mycobacterial infection, suggesting that RPE can serve as a reservoir for intraocular M tuberculosis infection.