CRP (C-Reactive Protein) Revisited: An Old Yet New Biomarker of Acute and Chronic Inflammation

C-reactive protein (CRP) was discovered as a protein that reacts with C-polysaccharides to form precipitates in the serum of patients with pneumococcal infection. Subsequently, it was found to increase in the serum of patients with bacterial infections and rheumatic diseases, and it has since been widely recognized as a nonspecific biomarker of acute inflammation and utilized in clinical medicine. Meanwhile, CRP-like proteins are also present in the hemolymph of horseshoe crabs, and it has become clear that these proteins have long played a crucial role in the humoral innate immune response against foreign microorganisms. In recent years, advances in molecular analysis have revealed the details of the complex biological functions performed by CRP. Furthermore, with the development of highly sensitive CRP measurement methods, its importance as a biomarker is gaining attention not only in acute inflammatory diseases but also in chronic inflammatory diseases such as cardiovascular disease, diabetes, cancer and neurological disorders. New treatment strategies targeting CRP, based on recent findings, are also being explored.