Background

Cathepsin C (CatC) is a lysosomal enzyme involved in activation of serine proteases from immune and inflammatory cells. Several loss-of-function mutations in the CatC gene have been shown to be the genetic mark of Papillon-Lefèvre syndrome (PLS), a rare autosomal recessive disease characterized by severe early-onset periodontitis, palmoplantar hyperkeratosis, and increased susceptibility to infections. Deficiencies or dysfunction in other cathepsin family proteins, such as cathepsin B or D, have been associated with autophagic and lysosomal disorders.

Objectives

Here we characterized the basis for autophagic dysfunction in patients with PLS by analyzing skin fibroblasts derived from patients with several mutations in the CatC gene and reduced enzymatic activity.

Methods

Skin fibroblasts were isolated from patients with PLS assessed by using genetic analysis. Authophagic flux dysfunction was evaluated by examining accumulation of p62/SQSTM1 and a bafilomycin assay. Ultrastructural analysis further confirmed abnormal accumulation of autophagic vesicles in mutant cells. A recombinant CatC protein was produced by a baculovirus system in insect cell cultures.

Results

Mutant fibroblasts from patients with PLS showed alterations in oxidative/antioxidative status, reduced oxygen consumption, and a marked autophagic dysfunction associated with autophagosome accumulation. These alterations were accompanied by lysosomal permeabilization, cathepsin B release, and NLR family pyrin domain containing 3 (NLRP3) inflammasome activation. Treatment of mutant fibroblasts with recombinant CatC improved cell growth and autophagic flux and partially restored lysosomal permeabilization.

Conclusions

Our data provide a novel molecular mechanism underlying PLS. Impaired autophagy caused by insufficient lysosomal function might represent a new therapeutic target for PLS.

中文翻译：

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重组组织蛋白酶C治疗可恢复Papillon-Lefèvre综合征患者的自噬功能障碍

背景

组织蛋白酶C（CatC）是一种溶酶体酶，参与激活来自免疫细胞和炎性细胞的丝氨酸蛋白酶。CatC基因中的几个功能丧失突变已被证明是Papillon-Lefèvre综合征（PLS）的遗传标记，Papillon-Lefèvre综合征是一种罕见的常染色体隐性遗传病，其特征是严重的早发性牙周炎，掌plant过度角化和对感染的易感性增加。其他组织蛋白酶家族蛋白（例如组织蛋白酶B或D）的缺陷或功能障碍与自噬和溶酶体疾病有关。

目标

在这里，我们通过分析源自CatC基因若干突变且酶活性降低的患者的皮肤成纤维细胞，来表征PLS患者自噬功能障碍的基础。

方法

通过遗传分析从患有PLS的患者中分离出皮肤成纤维细胞。通过检查p62 / SQSTM1的积累和bafilomycin分析评估了吞噬通量功能障碍。超微结构分析进一步证实了自噬小泡在突变细胞中的异常积累。杆状病毒系统在昆虫细胞培养物中产生了重组的CatC蛋白。

结果

来自PLS患者的突变成纤维细胞显示出氧化/抗氧化状态的改变，氧气消耗的减少以及与自噬体积累相关的明显的自噬功能障碍。这些改变伴有溶酶体通透性，组织蛋白酶B释放和含有3（NLRP3）炎性小体活化的NLR家族吡啶结构域。用重组CatC处理突变型成纤维细胞可改善细胞生长和自噬通量，并部分恢复溶酶体通透性。

结论

我们的数据提供了PLS潜在的新型分子机制。溶酶体功能不足引起的自噬受损可能代表PLS的新治疗靶点。