To understand why chronic inflammation happens, some of the biochemical processes leading to all inflammation must first be understood. If there is one thing to take away from this section, it is that the four proteins listed below play key roles in our immune response. While we may not understand the full relationship they have to chronic inflammation, they are known factors which act as biomarkers and lead to a chronically inflamed state.

1. Tumor Necrosis Factor alpha (TNFa):

TNFa signals to the body to bring the neutrophil white blood cells to the site of infection or injury. TNFa is known as a cytokine, or a cell-signalling protein. Cytokines are messengers very similar in function, but not identical, to hormones.

TNFa acts like a "first responder" at an accident--it signals to the body where the most damage is so that the immune system can send the right response, which is to send neutrophils, which act like EMTs and firemen, clearing wreckage to reach the injured and carting them away in ambulances.

2. Nuclear Factor kappa B (NFkB):

NFkB works like a switch for certain genes. When NFkB is allowed to enter the nucleus, which it does through the aid of TNFa, it turns on the genes which allow cells to proliferate, mature, and avoid destruction through apoptosis (programmed cell death). This allows white blood cells to replicate and do their job in cleaning up the infected or injured area. NFkB is a transcription factor protein complex.

NFkB is similar to the priority setting on a communications line--it opens all channels available for the quickest response. When NFkB is turned on, EMTs, police, and firemen will continue to flock to the scene of the accident. When NFkB gets turned off, they stop coming and start to leave.

3. Interleukin-6 (IL-6):

IL-6 dictates the neutrophils to destroy themselves and draws monocytes, another type of white blood cell, to the infected or injured area instead. The monocytes create macrophages which clean up the debris and pathogens through phagocytosis, the process by which macrophages eat dead cells and other particles whole. IL-6 is also a cytokine (a messenger), like TNFa.

IL-6 acts to call in the road crew to clean up the debris from an accident and oversees the progress. As the road gets closer to being completely clear, IL-6 sends the cleaners, police, and anybody left at the scene of the accident away and ultimately declares the road open once again.

4.C-Reactive Protein (CRP):

CRP is produced by the liver in response to IL-6 levels and binds to the surface of dead and dying cells, and also to certain forms of bacteria. CRP acts as a form of signal for the macrophages to ingest something through phagocytosis, and thus helps in the ultimate clearing of debris during inflammation. CRP is a "pattern recognition receptor" protein, which means it marks recognized debris for removal.

CRP acts like the paint a logger marks trees to harvest with--it's a sign that this tree is okay to remove but that one isn't. Without CRP, it would take our body a lot longer to figure out what it ought to remove and what it ought not.Source