Am. J. Respir. Cell Mol. Biol., Vol 14, No. 5, 05 1996, 454-460.
Inhibition of Sephadex-induced lung injury in the rat by Ro 45-2081, a tumor necrosis factor receptor fusion protein
PR Gater, MA Wasserman, PM Paciorek and LM Renzetti
Department of Inflammation/Autoimmune Disease, Roche Pharmaceuticals, Hoffmann-La Roche, Inc., Nutley, New Jersey 07110-1199.
Tumor necrosis factor (TNF) is an inflammatory cytokine produced by many
cell types which may contribute to the pathophysiology of a variety of lung
diseases. In this study we have used Ro 45-2081 (a soluble receptor
composed of the human p55 TNF receptor and human heavy- chain
immunoglobulin G) to explore the role of TNF in the acute inflammatory
response in the rat lung to intravenous injection of Sephadex beads. The
effects of Ro 45-2081 have also been compared with those of dexamethasone.
At 24 and 72 h after Sephadex, there was a significant increase in the
total number of leukocytes in bronchoalveolar lavage fluid (BALF). At 24 h,
the number of neutrophils comprised around 50% of the total leukocyte
number, decreasing to around 10% of total by 72 h. The eosinophil count was
maintained at around 10% of the total leukocyte number. Pretreatment with
either Ro 45-2081 [1 and 3 mg kg-1, intraperitoneally (i.p.)] or
dexamethasone (0.1 and 0.3 mg kg-1, i.p.) inhibited the neutrophilia at 24
h after Sephadex, although Ro 45-2081 had no significant effect on total
cell number. At 72 h after Sephadex, Ro 45-2081 (1 and 3 mg kg-1, i.p.,
daily) significantly reduced the neutrophil influx into BALF but had no
inhibitory effect on eosinophil number. In contrast, dexamethasone (0.1 and
0.3 mg kg-1, i.p., daily) virtually abolished the infiltration of
neutrophils and eosinophils into BALF. The lack of effect of Ro 45-2081 on
eosinophil infiltration into the rat lung and the inhibition caused by
dexamethasone suggest that factors other than TNF are involved in this part
of the inflammatory response induced by Sephadex. However, the inhibitory
effects of Ro 45-2081 show that TNF may play an important role in the
recruitment of neutrophils into the lungs of Sephadex-treated rats.