[libribook.com] Traumatic Scar Tissue Management 1st Edition

Neuropeptides
Under physiological and pathophysiological conditions, neuropeptides released
during wound healing modulate a number of important aspects of the process
such as cell proliferation, cytokine and growth factor production, antigen
presentation, mast cell degradation, increased vascular permeability and
neovascularization (Lawman et al. 1985, Quinlan et al. 1998, Gibran et al. 2002,
Muangman et al. 2004, Scott et al. 2007, Hanna & Katz 2011, Chéret et al.
2013).
Altered neuropeptide levels are implicated in pathophysiological scar formation,
pruritus and chronic pain (Henderson et al. 2006, Scott et al. 2007, Almarestani
et al. 2008, Cheng et al. 2011, Widgerow 2013, Xiao et al. 2013).
Substance P
During wound healing there is early release of substance P in the local milieu of
the epidermis and ECM. In addition to its role in pain signaling, substance P is
also known to induce inflammation and mediate angiogenesis, keratinocyte
proliferation and fibrogenesis. Altered levels of substance P can instigate
excessive inflammation and subsequent sequelae (Quinlan et al. 1998, Quinlan et
al. 1999, Broome & Miyan 2000, Scott et al. 2007).
Substance P concentration has been found to be significantly greater in
hypertrophic scars than in normal uninjured skin and the proliferative effect of
substance P on fibroblasts is thought to contribute to keloid formation (Crowe et
al. 1994, Scott et al. 2007, Jing et al. 2010).
When stimulated by substance P, mast cells in hypertrophic scars were found to
release more histamine than those found in normal skin. Additionally, mast cells
are capable of promoting proliferation of fibroblasts. Therefore mast cells are
thought to play a role in fibroblast mediated hypertrophic scar formation and
pruritus mediated by the release of excess histamine (Scott et al. 2007, Cheng et
al. 2011, Widgerow 2013).
In addition to acute pain signaling, substance P is implicated in mediating certain
chronic pain related symptoms, such as hyperalgesia and allodynia, seen with
mature hypertrophic scars (Henderson et al. 2006, 2012).