Supplementary Material for: Processing of Laminin α Chains Generates Peptides Involved in Wound Healing and Host Defense

Laminins play a fundamental role in basement membrane architecture and function in human skin. The C-terminal laminin G domain-like (LG) modules of laminin α chains are modified by proteolysis to generate LG1-3 and secreted LG4-5 tandem modules. In this study, we provide evidence that skin-derived cells process and secrete biologically active peptides from the LG4-5 module of the laminin α3, α4 and α5 chain in vitro and in vivo. We show enhanced expression and processing of the LG4-5 module of laminin α3 in keratinocytes after infection and in chronic wounds in which the level of expression and further processing of the LG4-5 module correlated with the speed of wound healing. Furthermore, bacterial or host-derived proteases promote processing of laminin α3 LG4-5. On a functional level, we show that LG4-5-derived peptides play a role in wound healing. Moreover, we demonstrate that LG4-derived peptides from the α3, α4 and α5 chains have broad antimicrobial activity and possess strong chemotactic activity to mononuclear cells. Thus, the data strongly suggest a novel multifunctional role for laminin LG4-5-derived peptides in human skin and its involvement in physiological processes and pathological conditions such as inflammation, chronic wounds and skin infection.

层粘连蛋白（Laminins）在人体皮肤的基底膜架构与功能中发挥基础性作用。层粘连蛋白α链的C端层粘连蛋白G结构域样（LG）模块经蛋白水解修饰后，可生成LG1-3并分泌出LG4-5串联模块。本研究中，我们证实皮肤来源细胞可在体外及体内，从层粘连蛋白α3、α4及α5链的LG4-5模块中加工并分泌生物活性肽。我们发现，感染后的角质形成细胞以及慢性伤口组织内，层粘连蛋白α3的LG4-5模块的表达与加工过程均被显著增强，且该模块的表达水平及后续加工程度与伤口愈合速度呈显著正相关。此外，细菌或宿主来源的蛋白酶可促进层粘连蛋白α3 LG4-5模块的水解加工。在功能层面，我们证实LG4-5来源的肽类在伤口愈合过程中发挥关键作用。进一步研究表明，源自α3、α4及α5链的LG4肽段具备广谱抗菌活性，同时对单核细胞具有较强的趋化活性。综上，本研究数据有力提示，层粘连蛋白LG4-5来源的肽类在人体皮肤中存在全新的多功能作用，并参与炎症、慢性伤口及皮肤感染等多种生理过程与病理状态。