Evidence that polyhydroxylated C60 fullerenes (fullerenols) amplify the effect of lipopolysaccharides to induce rapid leukocyte infiltration in vivo.

Fullerenols C60(OH) have therapeutic potential, but there is debate regarding their toxicity. Here, we tested the hypothesis that C60(OH)n possesses a pro-inflammatory effect in vivo. Kinetic and dose-dependent experiments performed with the murine air pouch model of acute inflammation revealed that, unlike TiO2 used as a positive control in this model, C60(OH)n NPs were not pro-inflammatory in CD-1, C57BL/6, and BALB/c mice. However, after 3 h of treatment, C60(OH)n NPs were found to amplify the effect of lipopolysaccharides (LPS) causing a rapid leukocyte influx in which the major cells observed are neutrophils. The use of an antibody array assay to detect different analytes simultaneously indicates that the amplification effect is, at least partially, explained by an increased local production of several cytokines/chemokines in the exudates, including the pro-inflammatory cytokine IL-6. Using an ELISA to quantify the amount of IL-6 produced into air pouch exudates, we demonstrated that C60(OH)n increases the LPS-induced local production of this cytokine. Therefore, although C60(OH)n NPs alone do not exert proinflammatory activity under certain conditions, they can act in concert with other agents to cause inflammation, a situation that is likely to occur in vivo.