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Background Photodynamic therapy (PDT) has been described for photoageing treatment, but its mechanism of action is not clarified. Although PDT-induced matrix metalloproteinase (MMP) expression and collagen production have been studied in normal skin and in inflammatory disease, there is no report about the effect of PDT on the extracellular matrix in photodamaged skin. Objectives To evaluate skin remodelling induced by methyl aminolaevulinate (MAL)-PDT in photodamaged skin by histological and immunohistochemical studies. Methods Fourteen patients were treated with two sessions of MAL-PDT. The light source was a light-emitting diode (635 nm, 37 J cm−2). Skin biopsies were performed in all patients before and at 3 and 6 months after treatment. Immunohistochemical studies evaluated collagen types I and III, MMP-1, MMP-3, MMP-7, MMP-9, MMP-12 and tissue inhibitor of metalloproteinases-1. Results Global improvement in photodamaged skin was observed. A significant increase in expression of MMP-9 in the dermis was detected at 3 months after treatment ( P = 0·002). Significant increases in the expression of collagen type I at 3 months ( P = 0·002) and at 6 months after treatment ( P = 0·001) were also observed. Conclusions Skin remodelling induced by MAL-PDT was demonstrated in photodamaged skin. Two sessions of MAL-PDT increases immunohistochemical expression of MMP-9 in the dermis at 3 months after treatment, and also of collagen type I. [ABSTRACT FROM AUTHOR]

The high incidence of overwhelming postsplenectomy infection caused by Streptococcus pneumoniae can be reduced by splenic autotranspiantation. In this study the effect of splenectomy and splenic autotransplantation on the immune response to S. pneumoniae infection was investigated. Balb/c mice were divided into three groups: splenectomized (SP), splenectomized and autotransplanted (AT), and sham operated control (CT). Five days post-infection the serum antibody levels were measured and the number of S. pneumoniae CR1, neutrophil accumulation and IL-17 production in the liver and lungs were investigated. SP mice showed greater number of bacteria in both organs and lower serum levels of S. pneumoniae-specific 1gM, lgG1 and lgc2a antibodies. IL-17 production and neutrophil recruitment to the liver and lungs were lower in SP mice, in comparison with both the Cr and the AT groups. Levels of S. pneumoniae-specific 1gM, CFU counts, neutrophil accumulation and lL-17 production did not differ significantly between the CF and AT groups. These results suggest that splenic autotransplantation restores the capacity of splenectomized mice to fight S. pneumoniae infection. [ABSTRACT FROM AUTHOR]