Mast cell chymase decreases severity of group B Streptococcus infections

Published online: September 12, 2017

Group B Streptococcus (GBS) are lower genital tract bacteria that are frequently associated with preterm births, stillbirths and can cause serious infectious such pneumonia, sepsis and meningitis in the newborn. Although women testing positive for GBS receive antibiotics during labor and delivery, no strategies exist to prevent GBS infection in the developing fetus before labor or GBS infections that occur in babies (>7 days of age).

In the article recently published in The Journal of Allergy and Clinical Immunology (JACI), Gendrin and Shubin (co-first authors) and colleagues theorized that resident immune cells such as mast cells regulate the host immune response to lower genital tract bacteria. Specifically, the authors addressed how chymase, a protease released by mast cells, contributes to host defense against GBS infections.

The authors found that mice that were deficient in expression of the mast cell chymase exhibited increased susceptibility to systemic GBS infection and also had higher rates of GBS infection-associated preterm birth. A closer look revealed that by digesting a key host extracellular matrix protein known as fibronectin, chymase diminished the ability of GBS to colonize and disseminate within the host.

The author’s findings suggest that the protective/antibacterial effect of chymase may offer a future therapeutic strategy for decreasing GBS infections and associated preterm births.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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