Abstract
BACKGROUND: First described in 1994, fibrocytes are now appreciated to participate in different inflammatory and fibrogenic processes as well as in wound healing. Fibrocytes are unique in their expression of both myeloid and connective tissue products, which include a distinct cytokine and surface marker expression profile. Recent studies suggest their clinical utility as predictive biomarkers and as targets for therapeutic intervention. THE PROBLEM: Fibrocytes are involved in physiological and beneficial processes such as wound repair. Their involvement in detrimental processes such as aberrant collagen deposition in different fibrosing diseases reveals the sensitive balance in which these bone marrow progenitors have to be maintained. BASIC/CLINICAL SCIENCE ADVANCES: The enumeration of circulating fibrocytes and correlation with clinical severity of different fibrosing disorders is one of the most promising advantages in recent fibrocyte research. Besides their potential as a biomarker, fibrocytes may be therapeutically targeted by serum amyloid P, which inhibits their differentiation. In addition, recent murine studies supported the immunomodulatory potential of fibrocytes and demonstrated that these cells are controlled by CD4(+) T cells. CLINICAL CARE RELEVANCE: The potential prognostic utility of quantifying circulating fibrocytes in patients suffering from fibrotic diseases is one of the most promising aspects in possible clinical applications. In addition, controlling the number and differentiation of fibrocytes by therapeutic regulation of known differentiation by specific T-cell immunosuppression may open new avenues for the treatment of fibrosing diseases. CONCLUSION: Further detailed understanding of fibrocyte biology and their regulation in different disorders is desirable to advance new therapies for the treatment of chronic fibrosing disorders such as interstitial lung disease and to promote wound repair.