Matrix metalloproteinase-8 overexpression prevents proper tissue repair.

BACKGROUND: The collagenolytic matrix metalloproteinase-8 (MMP-8) is essential for normal tissue repair but is often overexpressed in wounds with disrupted healing. Our aim was to study the impact of a local excess of this neutrophil-derived proteinase on wound healing using recombinant adenovirus-driven transduction of full-length Mmp8 (AdMMP-8). METHODS: The effect of MMP-8 overexpression was evaluated in dermal fibroblasts and in two wound healing models in male Wistar rats: subcutaneously positioned ePTFE catheters and linear incisional skin wounds. RESULTS: Fibroblasts transduced with AdMMP-8 secreted MMP-8 with type I collagenolytic activity that could be blocked by a selective MMP-8 inhibitor. AdMMP-8 (5 × 10(10) viral particles) administered in homologous fibrin increased MMP-8 mRNA (P < .05) levels compared to parallel wounds treated with a control adenovirus expressing lacZ (AdLacZ). Impaired wound healing was demonstrated with AdMMP-8 by decreased collagen deposition and breaking strength of incisional wounds on day 7 compared to AdLacZ-treated wounds (P < .05). We found no significant effect of AdMMP-8 on mRNA levels of MMP-9, COL1A1, or COL3A1, but AdMMP-8 treatment decreased the number of neutrophils. In the incisional wounds, MMP-8 gene transfer was not associated with significant changes in macrophage numbers or amount of granulation tissue but did increase MMP-8 protein by 76% (P < .01) and decrease type I collagen protein by 29% (P < .05) compared with AdLacZ. CONCLUSION: These results demonstrate that superphysiologic levels of the proteinase MMP-8 can result in decreased collagen and lead to impaired wound healing. This observation makes MMP-8 a potential drug target in compromised human wound healing associated with MMP-8 overexpression.

Matrix metalloproteinases in the cervical mucus plug in relation to gestational age, plug compartment, and preterm labor.

BACKGROUND: High concentrations of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have been identified in the cervical mucus plug (CMP) at term of pregnancy. Their physiological and pathophysiological implications, however, remain to be elucidated, and CMPs from preterm labor have never been examined. This study was therefore conducted to describe the concentrations of MMP-2, TIMP-1, MMP-8 and MMP-9 in the CMP in relation to gestational age, IL-8 as an indicator of inflammation, compartment of the CMP, and preterm labor. METHODS: An aliquot of the distal plug compartment facing the vaginal microflora (CMP-dist) was collected from non-pregnant (n = 15), early pregnant (n = 15) and term pregnant women (n = 15). Whole CMPs shed during active vaginal term (n = 15) and preterm (n = 4) labor were also included. Protein concentrations were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: MMP-2 was not detectable in the non-pregnant CMP-dists whereas high concentrations were found in early pregnancy followed by an 85% decline at term. High concentrations of TIMP-1 were found in both the non-pregnant and early pregnant CMP-dists with a 90% decline at term. Consequently, the molar TIMP/MMP ratio was 40 in the non-pregnant state and 0.2 at term. The MMP-2 and TIMP-1 concentrations were alike in the CMP-dists and the whole CMPs.MMP-8, MMP-9, and IL-8 were mainly found in the distal CMP compartment. MMP-8 and MMP-9 concentrations were several fold increased in this compartment during pregnancy compared to the non-pregnant state. In the preterm whole CMPs, MMP-8, MMP-9 and IL-8 were 2 to 5 fold increased compared to term whole CMPs. CONCLUSIONS: These results suggest that CMP MMP-2 reflects the non-leukocyte dependent cervical remodeling that occurs in early pregnancy, whereas MMP-8 and MMP-9 are involved in the defense against ascending infections primarily located to the distal compartment of the CMP. The upregulation of MMP-8, MMP-9 and IL-8 in whole CMPs from preterm labor may indicate the involvement of an intrauterine infection.

Overexpression of hyaluronan in the tunica media promotes the development of atherosclerosis.

The arterial content of hyaluronan (HA) undergoes diffuse changes as part of the diabetic macroangiopathy. Because HA influences the phenotype of vascular cells in vitro such as proliferation, migration, and secretion, it is tempting to speculate that diabetes-induced hastened cardiovascular disease may be linked to the increased amount of HA. To explore the pathophysiological role of altered HA content in the arterial wall in vivo, we created transgenic (Tg) mice with HA overexpression in smooth muscle cells (SMCs) in large and small vessels, targeted by the alpha smooth-muscle-cell-actin (alphaSMA) promoter fused to the human hyaluronan synthase 2 (hHAS2) cDNA. RT-PCR demonstrated hHAS2 mRNA expression in the tunica media of large and small vessels. In situ hybridization confirmed that hHAS2 mRNA was targeted to the SMCs. The aortic HA content was elevated in the Tg mice, and by immunohistochemistry, it was seen that HA accumulated in the tunica media. The secretory profile of high- and low-molecular HA was similar in wild-type and Tg animals. Overproduction of HA in the aorta resulted in thinning of the elastic lamellae in Tg mice. Our data suggest that this may lead to increased mechanical stiffness and strength, as determined by controlled stretching until failure. Finally, overproduction of HA on the genetic background of the ApoE-deficient mouse strain promoted atherosclerosis development in the aorta. These results indicate that a single component of the diabetic macroangiopathy, diffuse accumulation of HA, accelerates the progression of atherosclerosis.