By dint of the aging population and further deepened with the Covid-19 pandemic, lung disease has turned out to be a major cause of worldwide morbidity and mortality. The condition is exacerbated when the immune system further attacks the healthy, rather than the diseased, tissue within the lung. Governed by unremittingly proliferating mesenchymal cells and increased collagen deposition, if inflammation persists, as frequently occurs in aging lungs, the tissue develops tumors and/or turns into scars (fibrosis), with limited regenerative capacity and organ failure. Fas ligand (FasL, a ligand of the Fas cell death receptor) is a key factor in the regulation of these processes. FasL is primarily found in two forms: full length (membrane, or mFasL) and cleaved (soluble, or sFasL). We and others found that T-cells expressing the mFasL retain autoimmune surveillance that controls mesenchymal, as well as tumor cell accumulation following an inflammatory response. However, mesenchymal cells from fibrotic lungs, tumor cells, or cells from immune-privileged sites, resist FasL + T-cell-induced cell death. The mechanisms involved are a counterattack of immune cells by FasL, by releasing a soluble form of FasL that competes with the membrane version, and inhibits their cell death, promoting cell survival. This review focuses on understanding the previously unrecognized role of FasL, and in particular its soluble form, sFasL, in the serum of aged subjects, and its association with the evolution of lung disease, paving the way to new methods of diagnosis and treatment.
【저자키워드】 aging, pulmonary disease, Autoimmune response, soluble Fas ligand, 【초록키워드】 Treatment, Evolution, Inflammation, Tumor, pandemic, Diagnosis, lung, Lung disease, fibrosis, immune system, serum, survival, Surveillance, Lungs, Control, membrane, morbidity and mortality, Autoimmune, collagen, receptor, T-cell, cell death, regenerative, mechanism, association, Ligand, Inflammatory response, Immune cell, tumor cells, Organ failure, Regulation, tissue, key factor, full length, attack, Cell, scar, develop, involved, inhibit, exacerbated, subjects, occur, expressing, turn, cleaved, persists, the healthy, tumor cell, 【제목키워드】 response,