Analysis of early molecular changes associated with COPD via transcriptomic profiling of A549 cells in an in vitro experiment

Introduction. Chronic obstructive pulmonary disease (COPD) is a common condition of high social importance, in which the response of alveolar epithelium to cigarette smoke may play a critical role in disease pathogenesis.
Aim. To comprehensively characterize transcriptomic alterations in A549 cells in response to cigarette smoke extract (CSE), including differential gene expression and key signaling pathways, and to evaluate their potential contribution to pathological processes associated with COPD.
Materials and methods. A549 cells were cultured in DMEM until reaching 80% confluency, then incubated with 5% CSE or maintained under control conditions for 24 hours (n = 3 per group). Total RNA was extracted and enriched for mRNA. Sequencing was performed on the MGISEQ-200 platform in SE50 mode. Data analysis included read mapping (Salmon), differential gene expression analysis (DESeq2), and functional enrichment (Cytoscape).
Results. CSE exposure was associated with signs of actin cytoskeleton disorganization (Rho GTPase inhibition, ACTB downregulation) and endoplasmic reticulum stress, along with paradoxical activation of mTORC1 signaling amid suppression of transcription, proliferation, and apoptosis – a combination that may represent a state of metabolically active cellular stasis. Concomitantly, proteasomal degradation and antigen presentation of likely defective self-proteins were enhanced, possibly promoting immune surveillance. While proinflammatory signaling was generally attenuated, increased expression of IL1A, SPP1 and CSF3 may facilitate recruitment and activation of neutrophils, macrophages, and monocytes. Impaired efferocytosis (via upregulation of ANXA5) and defective apoptosis induction by cytotoxic T cells (due to disrupted granzyme endocytosis and inhibition of caspases) may lead to persistent inflammation with an autoimmune component.
Conclusion. Activation of mTORC1 signaling and autoantigen presentation under endoplasmic reticulum stress, as well as a potential reduction in the ability of cytotoxic T cells to induce apoptosis, may represent key pathogenic mechanisms of COPD, mediating alveolar epithelial injury induced by cigarette smoke.

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