The presence of c-reactive protein (CRP) isoforms during murine wound healing

Hynes, Julia Sarah (2013) The presence of c-reactive protein (CRP) isoforms during murine wound healing. Masters by Research thesis (MPhil), Manchester Metropolitan University.

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Abstract

Native C reactive protein (nCRP) is a pentameric oligoprotein composed of 5 identical protomers. Levels of this acute phase protein increase up to 1000 fold with the onset of inflammation; dissociation into single subunits creates a new isoform known as modified/monomeric CRP (mCRP). To date there has been no investigation of the presence and role of CRP in cutaneous wound healing. Our work presents a temporal and spatial profile for the presence of both CRP isoforms from 6 different time points post-wounding spanning 3 major phases of the wound healing process. Wax embedded murine (BALB/c) wound samples were sectioned and stained by immunohistochemistry with monoclonal antibodies(mCRP; 8C10 and nCRP; 2C10) specific to each isoform. CRP-positive cells were quantified by microscopy and expressed as a ratio of the total cell count to allow comparison between samples. During the acute wound healing process significant differences between expression of each isoform were found at day 3 post-wounding (D3) in inflammatory cells (p=<0.0001), and at both D7 and D14 in blood vessels(p=<0.0001). Moreover, expression of each CRP isoform was dependent on cell type and time point post-wounding. Expression of both isoforms decreased significantly in inflammatory cells between early and late inflammation (D3 and D7) (p=<0.0001). A similar pattern was seen in fibroblasts between D14 and D21, indicative of the late proliferative and early tissue-remodeling phases. However, levels of nCRP increased significantly in blood vessels between D7 and D14 (p=<0.0001), compared to no significant difference in mCRP expression. We also investigated CRP expression in the early inflammatory phase (D3) of an acute (intact) and delayed (ovariectomised) model of murine wound healing and found mCRP to be expressed significantly higher (p=0.013) than nCRP in the delayed (impaired) model of wound healing. However, there was no significant difference in mCRP expression between the acute and impaired healing models but rather a significantly decreased expression of nCRP in the delayed model of healing. To conclude the varying levels of expression in a cell type and time-specific manner suggests each isoform may exert differing biological activities important to the wound healing process that warrants further investigation. Moreover, differences in expression between acute and delayed wound healing models suggest CRP isoforms may mediate age-related impaired healing and chronic wounds. Further studies are required to determine the differential effects of CRP isoforms on cutaneous healing processes and the precise roles they may play during wound repair.