Interleukin-8 and extracellular vesicles spread senescence in Lymphangioleiomyomatosis microenvironment

The Senescence-Associated Secretory Phenotype (SASP), a hallmark of cellular senescence, is characterized by the presence of pro-inflammatory molecules, small Extracellular Vesicles (sEVs), and proteins that remodel the extracellular matrix. For this reason, SASP might contribute to the detrimental effects of senescence by promoting inflammation and parenchymal destruction. By controlling the translation of SASP factors, the mechanistic Target of Rapamycin (mTOR) is a central regulator of senescence. As a paradigm of senescence-driven lung impairment, we developed an in vitro model of Lymphangioleiomyomatosis (LAM), a pulmonary low-grade, destructive, metastasizing rare neoplasm. Primary LAM/TSC cells, that do not express the mTOR regulator tuberin, are senescent depending on mTOR constitutive activation and induce senescence in non-LAM pulmonary lung fibroblasts (PLFs) through their conditioned medium (CM), also inducing the secretion of the SASP factor Interleukin-8 (IL-8). Here, we demonstrate the possibility to counteract both the autocrine senescence in LAM/TSC cells and senescence induced on PLFs by inhibiting CXCR2, an IL-8 receptor that controls the senescent response to IL-8 stimuli, through the small molecule SB225002. With the aim to deepen the composition of LAM/TSC CM to identify the factors involved in senescence process, we also demonstrate that LAM/TSC cells release sEVs that contribute to senescence spreading on PLFs. Interestingly, IL-8 is enriched in the LAM/TSC sEVs samples compared to PLFs. Taken together, our results indicate the therapeutic potential to interfere with senescence spreading in lung microenvironment and suggest the employment of molecules targeting senescence as a worthy pharmacological approach for LAM.