L-carbocisteine inhibits respiratory syncytial virus infection in human tracheal epithelial cells

To examine the effects of L-carbocisteine on airway infection with respiratory syncytial (RS) virus, human tracheal epithelial cells were pretreated with L-carbocisteine and infected with RS virus. Viral titer, virus RNA, and pro-inflammatory cytokine secretion, including interleukin (IL)-1 and IL-6, increased with time after infection. L-carbocisteine reduced the viral titer in the supernatant fluids, the amount of RS virus RNA. RS virus infection susceptibility, and the concentration of pro-inflammatory cytokines induced by virus infection. L-carbocisteine reduced the expression of intercellular adhesion molecule (ICAM)-1, an RS virus receptor, on the cells. However, L-carbocisteine had no effects on the expression of heparan sulfate, a glycosaminoglycan that binds to the RS virus attachment protein, or on the amount of intracellular activated-RhoA, isoform A of the Ras-homologous family, that binds to the RS virus fusion protein. These findings suggest that L-carbocisteine may inhibit RS virus infection by reducing the expression of ICAM-1. It may also modulate airway inflammation during RS virus infection. (C) 2011 Elsevier B.V. All rights reserved.