Uncaria tomentosa acts as a potent TNF-alpha inhibitor through NF-kappaB

Uncaria tomentosa, commonly known as Cat's Claw or Uña de gato, is a medicinal plant that has been shown to have effective anti-inflammatory activities. We have previously shown that treatment of monocyte-like THP-1 cells with Uncaria tomentosa inhibits the production of the pro-inflammatory cytokine TNF-alpha while augmenting the production of IL-1beta. Since TNF-alpha and IL-1beta are usually regulated similarly and share a number of common promoter elements, including NF-kappaB and AP-1, the ability of Uncaria tomentosa to differentially regulate these inflammatory cytokines is of particular interest.

To determine the mechanism of action of Uncaria tomentosa, we investigated the effects of specific inhibitors of NF-kappaB on cellular responses including transcription factor activation using TransAM assays, the expression of cytokines as measured by ELISA, and cell survival as measured by changes in cell number following treatment.

Treatment with Uncaria tomentosa inhibited the LPS-dependent activation of specific NF-kappaB and AP-1 components. In addition, treatment with Uncaria tomentosa enhanced cell death when NF-kappaB was inhibited. The ability of Uncaria tomentosa to inhibit TNF-alpha production was diminished when NF-kappaB activation was prevented by drugs that mask NF-kappaB subunit nuclear localization signals, while IL-1beta expression was unchanged.

These results demonstrate that Uncaria tomentosa is able to elicit a response via an NF-kappaB-dependent mechanism. Further studies to characterize the mechanism by which Uncaria tomentosa can affect this pathway could provide a means to develop anti-TNF-alpha therapies.