ABSTRACT
BACKGROUND: Repeated exposure to ultraviolet (UV) rays damages skin connective tissue, which is thought to be associated with wrinkle formation. We hypothesized that repeated mild inflammation may cause the connective tissue alterations in photoaging. OBJECTIVE: To clarify the behavior of neutrophils and neutrophil elastase (NE) activity in the photoaging process and to examine the mechanisms of connective tissue damage resulting from NE in photoaging. METHODS: Mouse dorsal skin was irradiated with a suberythemal dose of UVB three times a week. After 5 or 10 weeks of irradiation, neutrophils were investigated by light microscopy and transmission electron microscopy. NE activity was examined by in situ zymography. Activation of proMMP-2 and proMMP-1 by NE both in the purified enzyme and in human skin fibroblast culture was examined by gelatin zymography or immunoblotting respectively. RESULTS: Both neutrophil infiltration and NE activity were elevated in photoaging. Furthermore, activated MMP-2 and MMP-1 were increased by NE treatment in a dose-dependent manner. CONCLUSIONS: In the present study, we demonstrated that neutrophil infiltration and NE activity are elevated in the chronic UVB-irradiated skin of hairless mice and we confirmed the involvement of NE in MMP activation. These data suggest that NE indirectly plays a role in skin photoaging through MMP activation.
Subject(s)
Leukocyte Elastase/metabolism , Skin Aging/physiology , Skin Aging/radiation effects , Ultraviolet Rays/adverse effects , Animals , Cells, Cultured , Enzyme Activation/radiation effects , Enzyme Precursors/metabolism , Extracellular Matrix/enzymology , Extracellular Matrix/radiation effects , Female , Gelatinases/metabolism , Humans , Matrix Metalloproteinase 1/metabolism , Mice , Mice, Hairless , Microscopy, Electron, Transmission , Models, Biological , Neutrophil Infiltration/physiology , Neutrophil Infiltration/radiation effects , Neutrophils/enzymology , Neutrophils/pathology , Neutrophils/radiation effects , Skin/enzymology , Skin/pathology , Skin/radiation effectsABSTRACT
In some cases of atopic dermatitis (AD), a possible pathological contribution to disease development by Candida albicans (C. albicans) has been suggested. AD patients with severe symptoms showing positive capsulated hydrolic carrier polymer radioallergosorbent test (CAP-RAST) against C. albicans demonstrated significantly higher levels of serum IgE Abs than did AD patients with mild symptoms. Based on the clinical facts, we have postulated that elimination of C. albicans by mucosal vaccination may lead to the restoration of severe symptoms in AD patients. For this purpose, we have developed an allergic murine model. Mice which were systemically challenged with C. albicans-associated antigen, manganese superoxide dismutase (MnSOD) or secreted aspartic proteases 2 (SAP2), together with alum, exhibited hyper IgE Abs. Systemically primed mice were then immunized with MnSOD or SAP2 plus cholera toxin (CT) as mucosal adjuvant through the nasal route. Interestingly, nasally immunized mice showed increased levels of Candida Ag-specific IgA Ab in fecal and nasal washes as well as in saliva samples but unchanged levels in Ag-specific IgE responses. Consistent with the Ab levels, high numbers of Candida Ag-specific IgA Ab-forming cells were induced in mononuclear cells isolated from intestinal lamina propria, nasal passages and salivary glands of nasally vaccinated mice with Ag plus CT. Furthermore, nasal immunization using MnSOD or SAP2 together with CT resulted in the elimination of colonized C. albicans from the intestinal tract. These results also suggest a potential role of mucosal vaccination in the control of C. albicans in patients with allergic diseases, including AD, although more research is needed to establish this therapeutic approach for mucosal vaccination.
