Köten Bente, Simanski Maren, Gläser Regine, Podschun Rainer, Schröder Jens-Michael, Harder Jürgen
Department of Dermatology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
PLoS One. 2009 Jul 29;4(7):e6424. doi: 10.1371/journal.pone.0006424.
Human skin is able to mount a fast response against invading microorganisms by the release of antimicrobial proteins such as the ribonuclease RNase 7. Because RNase 7 exhibits high activity against Enterococcus faecium the aim of this study was to further explore the role of RNase 7 in the cutaneous innate defense system against E. faecium.
METHODOLOGY/PRINCIPAL FINDINGS: Absolute quantification using real-time PCR and ELISA revealed that primary keratinocytes expressed high levels of RNase 7. Immunohistochemistry showed RNase 7 expression in all epidermal layers of the skin with an intensification in the upper more differentiated layers. Furthermore, RNase 7 was secreted by keratinocytes in vitro and in vivo in a site-dependent way. RNase 7 was still active against E. faecium at low pH (5.5) or high NaCl (150 mM) concentration and the bactericidal activity of RNase 7 against E. faecium required no ribonuclease activity as shown by recombinant RNase 7 lacking enzymatic activity. To further explore the role of RNase 7 in cutaneous defense against E. faecium, we investigated whether RNase 7 contributes to the E. faecium killing activity of skin extracts derived from stratum corneum. Treatment of the skin extract with an RNase 7 specific antibody, which neutralizes the antimicrobial activity of RNase 7, diminished its E. faecium killing activity.
CONCLUSIONS/SIGNIFICANCE: Our data indicate that RNase 7 contributes to the E. faecium-killing activity of skin extracts and suggest an important role for RNase 7 in the protection of human skin against E. faecium colonization.
人类皮肤能够通过释放抗菌蛋白（如核糖核酸酶RNase 7）对入侵微生物发起快速反应。由于RNase 7对粪肠球菌表现出高活性，本研究的目的是进一步探索RNase 7在皮肤针对粪肠球菌的固有防御系统中的作用。
方法/主要发现：使用实时PCR和ELISA进行绝对定量分析显示，原代表皮角质形成细胞表达高水平的RNase 7。免疫组织化学显示，RNase 7在皮肤的所有表皮层均有表达，且在上层分化程度更高的层中表达增强。此外，RNase 7在体外和体内均由角质形成细胞以位点依赖的方式分泌。在低pH（5.5）或高NaCl（150 mM）浓度下，RNase 7对粪肠球菌仍具有活性，并且如缺乏酶活性的重组RNase 7所示，RNase 7对粪肠球菌的杀菌活性不需要核糖核酸酶活性。为了进一步探索RNase 7在皮肤抵御粪肠球菌中的作用，我们研究了RNase 7是否有助于角质层来源的皮肤提取物对粪肠球菌的杀伤活性。用中和RNase 7抗菌活性的RNase 7特异性抗体处理皮肤提取物，可降低其对粪肠球菌的杀伤活性。
结论/意义：我们的数据表明，RNase 7有助于皮肤提取物对粪肠球菌的杀伤活性，并提示RNase 7在保护人类皮肤免受粪肠球菌定植方面具有重要作用。
