Microcrystalline cellulose induces time-dependent lung functional and inflammatory changes

We determined whether microcrystalline cellulose (MCC), a component of pharmaceutical tablets, induces pulmonary changes. In vivo [resistive and viscoelastic pressures (ΔP1 and ΔP2), static elastance (EL)] and in vitro [tissue resistance (R), elastance (E), and hysteresivity (η)] lung mechanics, histology, and bronchoalveolar lavage fluid (BALF) were analyzed 3 h, 24 h, and 3, 15 and 30 days after intratracheal instillation of saline (C) or MCC in BALB/c mice. ΔP1 increased at 3 h, remaining higher than C until day 3, while EL and ΔP2 increased only at 24 h. At 3 days all mechanical parameters returned to baseline. R and E increased only at 24 h. MCC increased alveolar collapse and the number of neutrophils in BALF at 3 h, until 3 and 15 days, respectively. At 3 days MCC migrate from the airways into the parenchyma, where they were observed until 30 days. In conclusion, microcrystalline cellulose yielded an acute and self-limited inflammation that impaired lung mechanics.