How pneumococci evade the immune system

A novel study led by Birgitta Henriques-Normark at Karolinska Institutet sheds light upon how pneumococci inhibit immune reactions and survive inside human cells, causing pneumonia. Parts of the analyses were enabled by the Mass Spectrometry Based Proteomics unit of SciLifeLab.

Pneumococci bacteria are found in the normal flora of healthy individuals of all ages, including pre-school children. Usually, pneumococci are harmless but they are also a common cause of medical conditions as otitis, pneumonia and meningitis. Globally, some two million people die from pneumococcal infections every year.

The current study explores the toxin pneumolysin, which is produced by the pneumococcus and facilitates its disease-inducing effects. One unexpected finding was that pneumolysin is able to chemically interact with the receptor, MRC-1 molecule that is found in certain immune cells, and by doing so trigger an anti-inflammatory response. Once inside the immune cells, the bacteria can hide from further attack and possibly even grow, to eventually give rise to pneumonia.

Read the press release by Karolinska Institutet

Read the full paper in Nature Microbiology