Late Breaking Abstract - Effect of Hypercapnia in human primary culture of alveolar cells in vitro

Title: Effect of hypercapnia in human primary culture of alveolar cells in vitro Introduction: Recent insights have emerged regarding the impact of hypercapnia on cellular and molecular function. Hypercapnia may have potentially beneficial effects in patients with ARDS, which are independent of the benefits from ventilation with low tidal volumes. However, other studies suggest that CO2 can act as a signaling molecule via pH independent mechanisms resulting in deleterious effects in the lung. Objectives: Determine the effects and mechanism of action of different CO2 and pH levels in human alveolar type II cells. Methods: After a signed informed patient consent, hATII were isolated from lung biopsies of patients that underwent lobectomy, and were incubated at 37oC with 5% CO2 concentration (normocapnia) or 15% CO2 concentration [pCO2=80 mmHg]. The media in both groups were buffered with 15mM THAM to maintain pH at 7.4. Results: hATII at 15% CO2 produced and increased IL6 and IL1β. IL1β peak was reversed with THAM. Hypercapnia was associated with an increase of CXCL1 levels (neutrophils recruitment) and an increase in apoptosis independent of pH (caspase 3, 8 and 9). Figure 1. Conclusions: Human alveolar cells exposed to hypercapnia produced an inflammatory response, with an increase in neutrophils recruitment and a significant increase in apoptosis, all of them independent of pH.