C-reactive Protein in Inflammatory Diseases: Clinical Aspects

Dear Colleagues,

This Topic focuses on the clinical relevance of C-reactive protein. Most physicians are familiar with it as a diagnostic biomarker, but only a few have realised that it can be a pathomolecule. After all, biomarker is of course not a physiological function. The main task of CRP is to mark cells to be disposed of, which has been shown for decades in various animal models and has been broken down to the molecular level. For several decades, CRP has been established as an extremely sensitive, reliable and early indicator of inflammatory and tissue-destructive processes. Following an acute phase stimulus, up to 1000-fold increased values can be measured.

This prototype of the human acute phase protein has been considered an inflammatory marker since it was first described by Tillet and Francis in 1930.

However, the mere use of CRP as a readily measurable inflammation marker neglects the biological function of the protein.

CRP is a serum protein and a mediator of innate immunity. The diverse functions of CRP across all living species led to the conclusion that CRP is a prehistoric precursor of all antibodies in the evolutionarily much-later-appearing mammals.

Already in the horseshoe crab (Limulus), a “living fossil” at least 250 million years old, CRP forms immune complexes together with the complement system and thus assumes defence functions. At the same time, it acts phylogenetically as an antibody in numerous species, such as fish, which have no adaptive immune system. In humans, its functions are complex and part of re-intensified research.

It is now accepted, even if not everyone is aware of it, that CRP plays a central role in the development of inflammation-related tissue damage. CRP activates (in the manner of antibodies) the complement system via the classical pathway and macrophages via Fc receptors. Therefore, CRP, in the manner of antibodies, binds to Fc receptors.

The present Topic aims to provide an overview of relevant studies and provide an outlook into the future perspective on this pivotal protein. This will not only provide valuable information on the potential for CRP-driven prognostic decisions, but also identify obstacles that need to be overcome to address CRP therapeutically.

Dr. Ahmed Sheriff
Prof. Dr. Jan Torzewski
Topic Editors