Marsico Lung Institute, UNC Chapel Hill, Chapel Hill, North Carolina, USA.
Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hillgrid.10698.36, Chapel Hill, North Carolina, USA.
mSphere. 2022 Aug 31;7(4):e0029122. doi: 10.1128/msphere.00291-22. Epub 2022 Aug 15.
The pathological properties of airway mucus in cystic fibrosis (CF) are dictated by mucus concentration and composition, with mucins and DNA being responsible for mucus viscoelastic properties. As CF pulmonary disease progresses, the concentrations of mucins and DNA increase and are associated with increased mucus viscoelasticity and decreased transport. Similarly, the biophysical properties of bacterial biofilms are heavily influenced by the composition of their extracellular polymeric substances (EPS). While the roles of polymer concentration and composition in mucus and biofilm mechanical properties have been evaluated independently, the relationship between mucus concentration and composition and the biophysical properties of biofilms grown therein remains unknown. Pseudomonas aeruginosa biofilms were grown in airway mucus as a function of overall concentration and DNA concentration to mimic healthy, and CF pathophysiology and biophysical properties were evaluated with macro- and microrheology. Biofilms were also characterized after exposure to DNase or DTT to examine the effects of DNA and mucin degradation, respectively. Identifying critical targets in biofilms for disrupting mechanical stability in highly concentrated mucus may lead to the development of efficacious biofilm therapies and ultimately improve CF patient outcomes. Overall mucus concentration was the predominant contributor to biofilm viscoelasticity and both DNA degradation and mucin reduction resulted in compromised biofilm mechanical strength. Pathological mucus in cystic fibrosis (CF) is highly concentrated and insufficiently cleared from the airway, causing chronic inflammation and infection. Pseudomonas aeruginosa establishes chronic infection in the form of biofilms within mucus, and this study determined that biofilms formed in more concentrated mucus were more robust and less susceptible to mechanical and chemical challenges compared to biofilms grown in lower concentrated mucus. Neither DNA degradation nor disulfide bond reduction was sufficient to fully degrade biofilms. Mucus rehydration should remain a priority for treating CF pulmonary disease with concomitant multimechanistic biofilm degradation agents and antibiotics to clear chronic infection.
气道黏液的病理特性取决于黏液浓度和组成，黏蛋白和 DNA 负责黏液的黏弹性。随着囊性纤维化（CF）肺部疾病的进展，黏蛋白和 DNA 的浓度增加，并与黏液的黏弹性增加和输送减少有关。同样，细菌生物膜的生物物理特性也受到其细胞外聚合物（EPS）组成的严重影响。虽然聚合物浓度和组成对黏液和生物膜机械性能的作用已分别进行了评估，但黏液浓度和组成与在其中生长的生物膜的生物物理特性之间的关系仍不清楚。在模拟健康和 CF 病理生理学的情况下，根据总浓度和 DNA 浓度在气道黏液中培养铜绿假单胞菌生物膜，并利用宏观和微观流变学评估其生物物理特性。还对暴露于 DNase 或 DTT 后的生物膜进行了表征，以分别检查 DNA 和黏蛋白降解的影响。确定生物膜中在高浓度黏液中破坏机械稳定性的关键靶标可能会导致开发有效的生物膜治疗方法，并最终改善 CF 患者的预后。总体黏液浓度是生物膜黏弹性的主要贡献者，DNA 降解和黏蛋白减少都导致生物膜机械强度受损。囊性纤维化（CF）的病理性黏液高度浓缩，并且不能从气道中充分清除，导致慢性炎症和感染。铜绿假单胞菌以生物膜的形式在黏液中形成慢性感染，本研究表明，与在低浓度黏液中生长的生物膜相比，在更浓缩的黏液中形成的生物膜更坚固，对机械和化学挑战的抵抗力更低。DNA 降解和二硫键减少都不足以完全降解生物膜。在治疗 CF 肺部疾病时，应优先考虑黏液再水化，并同时使用多种机制的生物膜降解剂和抗生素来清除慢性感染。
