Cyclic stretch increases glucose uptake and pro-inflammatory response in rat alveolar epithelial type II cells.

Background: Mechanical ventilation (MV) is used to improve gas exchange but can exacerbate lung inflammation by increasing alveolar cell stretch, leading to ventilator-induced lung injury (VILI). Alveolar epithelial stretching promotes cytokine release, but its effects on glucose uptake remain unclear. Methods: Rat alveolar epithelial type II cells (L2 AECs) treated and untreated with lipopolysaccharide (LPS) were exposed to 1 or 4 hours of 30% cyclic stretch. Non-stretched cells, stimulated or not with LPS, served as a control. Glucose oxidase activity was measured using a colorimetric/fluorometric assay, while glucose uptake was assessed by immunofluorescence using the fluorescent glucose analog 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose (2-NBDG). Gene expression and secretion were measured by real-time polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Statistical analyses were performed using one-way ANOVA followed by Šidák's multiple comparisons test, with significance set at Results: 30% cyclic stretch significantly increased glucose uptake and glucose oxidase activity in both LPS-treated and untreated cells. Inflammatory gene expression and mediator secretion were predominantly increased in LPS-primed cells, although the effects varied according to the marker and time point. Conclusions: Overall, excessive cyclic stretch increased the glucose-related readouts assessed in AECs L2 cells, whereas inflammatory responses were more strongly influenced by LPS stimulation and varied among mediators and time points.