In vivo evaluation of a morpholino antisense oligomer directed against tumor necrosis factor-alpha.

Morpholino antisense oligomers directed against the cytokine tumor necrosis factor (TNF-alpha) can specifically inhibit production of TNF-alpha by macrophages in vitro. To evaluate the efficacy of morpholino antisense in vivo, we characterized a mouse model of increased pulmonary TNF-alpha production and inflammation in response to aerosolized endotoxin. Pretreatment of mice by intranasal (i.n.) insufflation of oligomers (30 microl of 100 microM/ml) 12 hours prior to lipopolysaccharide (LPS) exposure resulted in specific and consistent inhibition of TNF-alpha production by the oligomer MAS-2, whereas no effect was observed with a sequence-scrambled control (% inhibition 31.5 +/- 3.5 vs. 1.3 +/- 8.0, respectively, p < 0.005). Dose-response analysis showed similar efficacy for MAS-2 at 25-100 microM/ml and diminished effects with lower concentrations. Inhibition of TNF-alpha did not alter the increase in neutrophils seen in bronchoalveolar lavage (BAL) fluid, a result consistent with observations using i.n. administration of neutralizing anti-TNF-alpha antibody or TNF receptor knockout mice. The results establish that morpholino oligomers directed against cytokine targets can function in vivo. Additional studies of other targets and administration protocols to improve efficacy are warranted.