The Biology of Fibrosis
Fibrosis results from deregulation of the wound healing processes. There are three
stages to the wound healing process: initiation, propagation and resolution.
Fibrosis
results from chronic stimulation of initiation, amplification of propagation and
insufficient stimulation and recruitment of resolution responses.
There is emerging
recognition in the scientific field that there are two types of immune responses
to injury that regulate these three stages of wound healing and thereby fibrosis. There is a primary inflammatory immune response that functions
to clean and sterilize the wound; however this process also generates damaged tissue.
This damaged tissue can promote initiation of fibrotic changes, and can stimulate
a secondary pro-fibrotic immune response that amplifies the propagation stage.
Finally
resolution of scar tissue is now recognized to require recruitment of certain primary inflammatory
immune cell populations.
Research has shown that traditional non-specific anti-inflammatory
drugs are ineffective at blocking progression of fibrotic disease. However, these
agents only affect
the primary inflammatory immune response. They do not appear
to affect the secondary pro-fibrotic immune response and may actually inhibit recruitment
of the
resolution response.