TNF and rheumatoid arthritis: However, against their involvement the exposure to tumor necrosis factor alpha (TNFα), a cytokine relevant in RA, was previously reported to induce BDNF upregulation either by cultured cerebral endothelial cells (Bayas et al., 2002) or neuron-enriched dissociated culture of trigeminal ganglion (Balkowiec-Iskra et al., 2011).