The Long Pentraxin PTX3 as a Humoral Innate Immunity Functional Player and Biomarker of Infections and Sepsis

Abstract

The first line of defense in innate immunity is provided by cellular and humoral mediators. Pentraxins are a superfamily of phylogenetically conserved humoral mediators of innate immunity. PTX3, the first long pentraxin identified, is a soluble pattern recognition molecule rapidly produced by several cell types in response to primary pro-inflammatory signals and microbial recognition. PTX3 acts as an important mediator of innate immunity against pathogens of fungal, bacterial and viral origin, and as a regulator of inflammation, by modulating complement activation and cell extravasation, and facilitating pathogen recognition by myeloid cells. In sepsis, PTX3 plasma levels are associated with severity of the condition, patient survival, and response to therapy. In combination with other established biomarkers, PTX3 could improve stratification of sepsis patients and thus, complement the system of classification and monitoring of this disease.

Keywords: inflammation; innate immunity; pentraxin; pentraxin 3 (PTX3); sepsis.

Figure 1

Role of PTX3 in innate immune responses and inflammation. Inflammatory stimuli and cellular sources of PTX3 are shown. Once released, PTX3 interacts with microorganisms, complement components, phagocytosis receptors, P-selectin, and components of the haemostatic system and fibrinolytic cascade, thus promoting pathogen clearance, tuning inflammatory responses and promoting tissue remodeling.

Figure 2

PTX3 in the prognosis of sepsis. PTX3 can be considered as a reliable biomarker for prognosis of sepsis patients, predicting severity of disease, incidence of new organ failures and mortality risk. Addition of PTX3 levels measured on the first day in ICU or ER to the panel of markers routinely used in Intensive care units and emergency room units, may increase the accuracy of prognosis in sepsis patients.