Identified a new receptor of the immune system against invasive pneumococcal infection

A study led by Dr. José Yuste, a group 2 researcher at CIBERES and the National Center for Microbiology of the Carlos III Health Institute, has made it possible to identify a new receptor present in neutrophils that protects against pneumococcal infection. In this work, recently published in the journal PLoS Pathogens , other researchers from CIBERES Group 2 led by Dr. Ernesto García at the CIB-CSIC, the Hospital de la Princesa and the University College in London have collaborated.

Invasive pneumococcal disease is associated with high rates of morbidity and mortality throughout the world, mainly affecting the pediatric population, over 65 years of age, and immunosuppressed patients. In this study, it is demonstrated that the P-selectin glycoprotein ligand 1 (PSGL-1) present in neutrophils acts as a true phagocytic receptor, recognizing the capsule and the LytA protein of Streptococcus pneumoniae as bacterial ligands. As a consequence, the bacterium is efficiently destroyed by these phagocytic cells, favoring the resolution of the infectious process.

This work is complemented with animal studies using mice deficient in this receptor, demonstrating that the absence of PSGL-1 increases the susceptibility to infection and the severity of invasive pneumococcal disease. The study also shows that during pneumococcal pneumonia, one of the main functions of this receptor is to prevent the spread of bacteria from the lungs to the bloodstream. Once the bacteria have accessed the circulatory system, this receptor would be in charge of effectively recognizing and destroying pneumococci, increasing the survival of the host against this devastating infectious disease.

This study represents a new advance in the knowledge of new defense mechanisms against pneumococcal infections.