Waliza Ansar - Clinical Significance of C-reactive Protein

C-reactive protein (CRP) is a fascinating acute phase protein which plays a range of functions in different physiological or pathophysiological states. Since its discovery, it has been regarded as a useful biomarker of tissue injury, infection, and inflammation. The native CRP (nCRP) and the modified isoforms (mCRP) appeared in due course of different researches. The mCRP is formed when CRP is exposed to acidic pH and redox conditions (conditions mimicking inflammatory microenvironments). The nCRP is the native pentameric structure. CRP is functional in both native (nCRP) and its non-native pentameric (mCRP) structural conformations. The functional roles of native CRP are quite different from mCRP. The mCRP binds to PC and also to immobilized (in vitro) factor H, the complement inhibitor for beneficial complement-resistant activity. Thus, nCRP is protective only against early-stage infection, while mCRP is protective against both early- and late-stage infections. As nCRP exhibits PC-independent anti-pneumococcal activity, it is quite feasible that CRP functions as a general antibacterial molecule. They have different impacts in diverse pathophysiological states. CRP as a biomarker of inflammation, is a clinically significant predictor of potential episodes of cardiovascular disease, independent of other risk factors. Researchers suggested the structurefunction relationship between the mCRP isoforms and nCRP. Attempts had been made to recognize the possible significance between the diversity of structures and their opposing roles. This chapter discusses the biochemical facets of CRP biology, emphasizing on the supposed application between the structural biology of CRP isoforms, their physiological relevance, differentiation, and condition-based pathophysiological roles.