Roles of Heparin-Binding Protein in Bacterial Infections

Infectious diseases remain a major health problem, where sepsis and other severe infectious diseases are common causes of morbidity and mortality. The importance of early and appropriate treatment of sepsis and severe bacterial infections has been underlined by the successes of measures like the Surviving Sepsis Campaign, among others. Thus, there is a need for clinical and laboratory tools to identify a patient with severe infection early and to distinguish between bacterial and non-bacterial conditions. Heparin-binding protein (HBP) is also called azurocidin, or cationic antimicrobial protein of 37 kDa (CAP37). It is a multifunctional granule-associated protein that is rapidly mobilized from migrating polymorphonuclear leukocytes. HBP acts as a chemoattractant, an activator of monocytes and macrophages, and induces vascular leakage and edema formation. The release of HBP is triggered by ligation of neutrophilic β₂-integrins, a process that may be initiated by bacterial structures. The overall outcome is powerful vascular leakage. It has been shown that patients with severe sepsis express high levels of HBP in plasma before they develop hypotension. HBP is also involved in the pathophysiology of soft tissue infection. In conclusion, this protein is strongly involved in the pathophysiology of severe bacterial infections, and thus represents a potential diagnostic marker and a target for treatment.