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Interactions among three molecules generated from leukocytes and/or epithelial cells, elastase, PEPI and SLPI mediates the host defense and wound repair. Results rveal that SLPI/elastase act through PEPI/epithelins to operate a switch found at the interface between innate immunity and wound healing.

Author(s): Gillian S. Ashcroft [1, 3]; Kejian Lei [1, 3]; Wenwen Jin [1]; Glenn Longenecker [2]; Ashok B. Kulkarni [2]; Teresa Greenwell-Wild [1]; Hollie Hale-Donze [1]; George McGrady [1]; Xiao-Yu [...]

Presents information on the immune system as it relates to ageing. Background information on the studies of the ageing immune system; Details on what the nature of immunity; Description of the effects of human ageing.

Post-menopausal women have an increased risk of developing a number of degenerative pathological conditions, linked by the common theme of excessive inflammation. Systemic estrogen replacement (in the form of hormone replacement therapy) is able to accelerate healing of acute cutaneous wounds in elderly females, linked to its potent antiinflammatory activity. However, in contrast to many other age-associated pathologies, the detailed mechanisms through which estrogen modulates skin repair, particularly the cell type-specific role of the two estrogen receptors, ERalpha and ERbeta, has yet to be determined. Here, we use pharmacological activation and genetic deletion to investigate the role of both ERalpha and ERbeta in cutaneous tissue repair. Unexpectedly, we report that exogenous estrogen replacement to ovariectomised mice in the absence of ERbeta actually delayed wound healing. Moreover, healing in epidermal-specific ERbeta null mice (K14-cre/ERbeta(L2/L2)) largely resembled that in global ERbeta null mice. Thus, the beneficial effects of estrogen on skin wound healing are mediated by epidermal ERbeta, in marked contrast to most other tissues in the body where ERalpha is predominant. Surprisingly, agonists to both ERalpha and ERbeta are potently antiinflammatory during skin repair, indicating clear uncoupling of inflammation and overall efficiency of repair. Thus, estrogen-mediated antiinflammatory activity is not the principal factor in accelerated wound healing.

Background: Multiple processes have been implicated in age-related delayed healing, including altered gene expression, intrinsic cellular changes, and changes in extracellular milieu (including hormones). To date, little attempt has been made to assess the relative contribution of each of these processes to a human aging phenomenon. The objective of this study is to determine the contribution of estrogen versus aging in age-associated delayed human wound healing., Results: Using an Affymetrix microarray-based approach we show that the differences in gene expression between male elderly and young human wounds are almost exclusively estrogen regulated. Expression of 78 probe sets was significantly decreased and 10 probe sets increased in wounds from elderly subjects (with a fold change greater than 7). A total of 83% of down-regulated probe sets and 80% of up-regulated probe sets were estrogen-regulated. Differentially regulated genes were validated at the level of gene and protein expression, with genes identified as estrogen-regulated in human confirmed as estrogen-dependent in young estrogen depleted mice in vivo. Moreover, direct estrogen regulation is demonstrated for three array-identified genes, Sele, Lypd3 and Arg1, in mouse cells in vitro., Conclusion: These findings have clear implications for our understanding of age-associated cellular changes in the context of wound healing, the latter acting as a paradigm for other age-related repair and maintenance processes, and suggest estrogen has a more profound influence on aging than previously thought.