Transcriptomic study on the effect of Igf1r deficiency in control and bleomycin-challenged mouse lungs.

Acute lung injury (ALI), ARDS and COVID-19 usually involve a “cytokine storm”. IGF1R (Insulin-like growth factor receptor 1) maintains lung homeostasis and is implicated in these pulmonary inflammatory diseases. In mice, widespread IGF1R deficiency was reported to counteract respiratory inflammation and alveolar damage after bleomycin (BLM)-induced ALI. To explore the molecular mechanisms mediated by Igf1r signaling after BLM challenge, we performed RNA-sequencing in lungs of IGF1R-deficient mice after BLM or saline (SAL) instillation. Transcriptomic analysis identified differentially expressed genes between BLM-challenged and SAL-treated control lungs, detecting biological processes and signaling pathways involved in ALI pathobiology. Igf1r depletion in BLM-challenged mice reversed large part of the transcriptional changes triggered by BLM, counteracting the transcriptomic profile of the inflammatory "cytokine storm". Data mining also identified changes in the expression of gene clusters with key roles in DNA damage, metabolic reprogramming, mitochondrial homeostasis, and epigenetics. Exploration of these functional groups, together with validation studies, provide new insights into the molecular mechanisms underlying the attenuating effect of Igf1r deficiency on ALI. These findings allow a more comprehensive view of IGF1R signaling at the transcriptional level, reinforcing its important role in promoting ALI and postulating it as a global epigenetic regulator in ARDS.