|Classification and external resources|
Fibrosis is the formation of excess fibrous connective tissue in an organ or tissue in a reparative or reactive process. This can be a reactive, benign, or pathological state. In response to injury, this is called scarring and if fibrosis arises from a single cell line this is called a fibroma. Physiologically, this acts to deposit connective tissue, which can obliterate the architecture and function of the underlying organ or tissue. Fibrosis can be used to describe the pathological state of excess deposition of fibrous tissue, as well as the process of connective tissue deposition in healing.
Fibrosis is similar to the process of scarring, in that both involve stimulated cells laying down connective tissue, including collagen and glycosaminoglycans. Immune cells called macrophages, as well as any damaged tissue between surfaces called interstitium, release TGF beta. There are numerous reasons for this, including inflammation of the nearby tissue, or a generalised inflammatory state, with increased circulating mediators. TGF beta stimulates the proliferation and activation of fibroblasts, which deposit connective tissue.
Examples of fibrosis
Fibrosis can occur in many tissues within the body, typically as a result of inflammation or damage, and examples include:
- Pulmonary fibrosis
- Mediastinal fibrosis (soft tissue of the mediastinum)
- Myelofibrosis (bone marrow)
- Retroperitoneal fibrosis (soft tissue of the retroperitoneum)
- Progressive massive fibrosis (lungs); a complication of coal workers' pneumoconiosis
- Nephrogenic systemic fibrosis (skin)
- Crohn's Disease (intestine)
- Keloid (skin)
- Scleroderma/systemic sclerosis (skin, lungs)
- Arthrofibrosis (knee, shoulder, other joints)
- Peyronie's disease (penis)
- Dupuytren's contracture (hands,fingers)
- Some forms of adhesive capsulitis (shoulder)
- Birbrair, A.; Zhang, T.; Wang, Z.-M.; Messi, M. L.; Mintz, A.; Delbono, O. (2013). "Type-1 pericytes participate in fibrous tissue deposition in aged skeletal muscle". AJP: Cell Physiology 305 (11): C1098. doi:10.1152/ajpcell.00171.2013.
- Glossary of dermatopathological terms. DermNet NZ
- Trojanowska, Maria (15 June 2012). "Mediators of Fibrosis". The Open Rheumatology Journal 6 (1): 70–71. doi:10.2174/1874312901206010070. PMC 3395879. PMID 22802903.