Clara cells, also known as club cells, are a vital component of the respiratory system. These non-ciliated, non-mucous, secretory cells reside in the epithelium lining the bronchioles (small airways in the lungs). Their primary function involves secreting proteins crucial for maintaining a healthy lung environment.
Key Roles of Clara Cells:
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Secretion of Protective Proteins: Clara cells produce and release the Clara cell 10-kDa secretory protein (CCSP), among other proteins. CCSP plays a role in modulating lung inflammation and immune responses, particularly in the context of respiratory infections like RSV (Respiratory Syncytial Virus). https://journals.aai.org/jimmunol/article/171/2/1051/35896/Clara-Cell-Secretory-Protein-Modulates-Lung They also contribute significantly to the airway lining fluid, a crucial component for maintaining lung health. https://www.sciencedirect.com/topics/neuroscience/clara-cell
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Progenitor Cell Function: Clara cells act as progenitor cells, meaning they can differentiate into other cell types in the bronchiolar epithelium, aiding in tissue repair and regeneration after injury. https://pmc.ncbi.nlm.nih.gov/articles/PMC2787899/ https://pmc.ncbi.nlm.nih.gov/articles/PMC4860431/
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Xenobiotic Metabolism: These cells participate in metabolizing foreign compounds (xenobiotics) that enter the lungs, helping to detoxify harmful substances. https://pmc.ncbi.nlm.nih.gov/articles/PMC2787899/
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Immune System Regulation: Clara cells play a role in regulating the immune response within the airways. https://pmc.ncbi.nlm.nih.gov/articles/PMC2787899/
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Mucin Secretion (in specific contexts): Under certain conditions, such as in response to antigen challenge, Clara cells can secrete mucin, a key component of mucus. https://pubmed.ncbi.nlm.nih.gov/15191915/
Historical Note: It's important to acknowledge the controversial historical context surrounding the naming of Clara cells, as research indicates the namesake, Max Clara, had ties to National Socialism and utilized ethically questionable research practices. https://publications.ersnet.org/content/erj/36/4/722
