B. pertussis Toxin

Pertussis toxin (PT) is a protein-based AB 5 type exotoxin produced by the bacterium Bordetella pertussis, which causes whooping cough. PT is involved in the colonization of the respiratory tract and the establishment of infection. Research suggests PT may have a therapeutic role in treating a number of common human ailments, including hypertension, viral inhibition, and autoimmune inhibition. PT has been shown to affect the innate immune response. It inhibits the early recruitment of neutrophils and macrophages, and interferes with the early chemokine production and the inhibition of the neutrophil chemotaxis. Chemokines are signaling molecules produced by infected cells and attract neutrophils and macrophages. Because of the disrupted signaling pathways, synthesis of chemokines will be affected. This will prevent the infected cell from producing them and thereby inhibiting recruitment of neutrophils. Under normal circumstances, alveolar macrophages and other lung cells produce a variety of chemokines. Eventually, PT causes lymphocytosis, one of the systemic manifestations of whooping cough. PT, a decisive virulence determinant of B. pertussis, is able to cross the blood-brain barrier by increasing its permeability. As a result, PT can cause severe neurological complications. However, recently it has been found that the medicinal usage of Pertussis toxin can promote the development of regulatory T cells and prevent central nervous system autoimmune disease, such as multiple sclerosis.