Abstract：
BACKGROUND: Primary ciliary dyskinesia (PCD) is a genetic disorder caused by aberrant motile cilia function that results in defective ciliary airway clearance and subsequently to recurrent airway infections and bronchiectasis.
OBJECTIVE: How many functional multiciliated airway cells are sufficient to maintain ciliary airway clearance?
METHODS: To answer this question we exploited the molecular defects of the X-linked recessive PCD variant caused by pathogenic variants in DNAAF6 (PIH1D3), characterized by immotile cilia in the affected males. We carefully analyzed the clinical phenotype, molecular defect (immunofluorescence and transmission-electron microscopy) and performed in vitro (particle tracking in air-liquid interface cultures) and in vivo (radiolabeled tracer studies) studies to assess ciliary clearance of respiratory cells from females with heterozygous and males with hemizygous pathogenic DNAAF6 variants.
RESULTS: PCD males with hemizygous pathogenic DNAAF6 variants displayed exclusively immotile cilia, absence of ciliary clearance and severe PCD symptoms. Due to random or skewed X-chromosome inactivation in six females with heterozygous pathogenic DNAAF6 variants, 54.3%±10 (range 38%-70%) of multiciliated cells were defective. Nevertheless, in vitro and in vivo assessment of the ciliary airway clearance was normal or slightly abnormal. Consistently, heterozygous female individuals showed no or only mild respiratory symptoms.
CONCLUSIONS: Our findings indicate that 30%-62% of functioning multiciliated respiratory cells are able to generate either normal or slightly reduced ciliary clearance. Because heterozygous females displayed either no or subtle respiratory symptoms, complete correction of 30% of cells by precision medicine might be able to improve ciliary airway clearance in PCD individuals as well as clinical symptoms.
OBJECTIVE: How many functional multiciliated airway cells are sufficient to maintain ciliary airway clearance?
METHODS: To answer this question we exploited the molecular defects of the X-linked recessive PCD variant caused by pathogenic variants in DNAAF6 (PIH1D3), characterized by immotile cilia in the affected males. We carefully analyzed the clinical phenotype, molecular defect (immunofluorescence and transmission-electron microscopy) and performed in vitro (particle tracking in air-liquid interface cultures) and in vivo (radiolabeled tracer studies) studies to assess ciliary clearance of respiratory cells from females with heterozygous and males with hemizygous pathogenic DNAAF6 variants.
RESULTS: PCD males with hemizygous pathogenic DNAAF6 variants displayed exclusively immotile cilia, absence of ciliary clearance and severe PCD symptoms. Due to random or skewed X-chromosome inactivation in six females with heterozygous pathogenic DNAAF6 variants, 54.3%±10 (range 38%-70%) of multiciliated cells were defective. Nevertheless, in vitro and in vivo assessment of the ciliary airway clearance was normal or slightly abnormal. Consistently, heterozygous female individuals showed no or only mild respiratory symptoms.
CONCLUSIONS: Our findings indicate that 30%-62% of functioning multiciliated respiratory cells are able to generate either normal or slightly reduced ciliary clearance. Because heterozygous females displayed either no or subtle respiratory symptoms, complete correction of 30% of cells by precision medicine might be able to improve ciliary airway clearance in PCD individuals as well as clinical symptoms.
摘要：
背景：原发性纤毛运动障碍（PCD）是由异常的活动纤毛功能引起的遗传性疾病，导致纤毛气道清除缺陷，随后导致反复的气道感染和支气管扩张。
目的：有多少功能性多纤毛气道细胞足以维持纤毛气道清除？
方法：为了回答这个问题，我们利用了由DNAAF6（PIH1D3）致病变异引起的X连锁隐性PCD变异的分子缺陷，在受影响的雄性中表现为不活动的纤毛。我们仔细分析了临床表型，分子缺陷（免疫荧光和透射电子显微镜），并进行了体外（气-液界面培养中的颗粒追踪）和体内（放射性标记的示踪剂研究）研究，以评估杂合雌性和半合子致病性DNAAF6变体雄性的呼吸道细胞的纤毛清除。
结果：具有半合子致病性DNAAF6变体的PCD男性表现出完全不运动的纤毛，无纤毛清除和严重PCD症状。由于六位具有杂合致病性DNAAF6变异体的女性随机或偏斜的X染色体失活，54.3％±10（范围38％-70％）的多纤毛细胞有缺陷。然而，体外和体内评估纤毛气道清除正常或轻微异常。始终如一，杂合的女性个体没有或仅表现出轻度的呼吸道症状。
结论：我们的研究结果表明，30％-62％的功能多纤毛呼吸细胞能够产生正常或略微降低的纤毛清除。因为杂合雌性没有或表现出轻微的呼吸道症状，通过精准医学完全纠正30%的细胞可能能够改善PCD个体的纤毛气道清除率以及临床症状。
目的：有多少功能性多纤毛气道细胞足以维持纤毛气道清除？
方法：为了回答这个问题，我们利用了由DNAAF6（PIH1D3）致病变异引起的X连锁隐性PCD变异的分子缺陷，在受影响的雄性中表现为不活动的纤毛。我们仔细分析了临床表型，分子缺陷（免疫荧光和透射电子显微镜），并进行了体外（气-液界面培养中的颗粒追踪）和体内（放射性标记的示踪剂研究）研究，以评估杂合雌性和半合子致病性DNAAF6变体雄性的呼吸道细胞的纤毛清除。
结果：具有半合子致病性DNAAF6变体的PCD男性表现出完全不运动的纤毛，无纤毛清除和严重PCD症状。由于六位具有杂合致病性DNAAF6变异体的女性随机或偏斜的X染色体失活，54.3％±10（范围38％-70％）的多纤毛细胞有缺陷。然而，体外和体内评估纤毛气道清除正常或轻微异常。始终如一，杂合的女性个体没有或仅表现出轻度的呼吸道症状。
结论：我们的研究结果表明，30％-62％的功能多纤毛呼吸细胞能够产生正常或略微降低的纤毛清除。因为杂合雌性没有或表现出轻微的呼吸道症状，通过精准医学完全纠正30%的细胞可能能够改善PCD个体的纤毛气道清除率以及临床症状。
