Dendritic cells from the elderly display an intrinsic defect in the production of IL-10 in response to Lithium Chloride

Chronic, low grade inflammation is a characteristic of old age. Innate immune system cells such as dendritic cells (DCs) from the elderly display a pro-inflammatory phenotype associated with increased reactivity to self. Lithium is a well-established anti-inflammatory agent used in the treatment of bipolar disorders. It has also been reported to reduce inflammation in DCs. Here, we investigated whether Lithium is effective in reducing the inflammatory responses in DCs from the elderly. The effect of Lithium Chloride (LiCl) was compared on the response of TLR4 agonist, LPS and TLR2 agonist, PAM3CSK4 stimulated aged and young DCs. LiCl enhanced the production of IL-10 in LPS stimulated young DCs. However, it did not affect TNF-α and IL-6 production. In contrast, in aged DCs, LiCl reduced the secretion of TNF-α and IL-6 in LPS stimulated DCs but did not increase IL-10. LiCl had no significant effect on PAM3CSK4 responses in aged and young DCs. LiCl treated DCs also displayed differences at the level of CD4 T cell priming and polarization. LPS-stimulated young DCs reduced IFN-γ secretion and biased the Th cell response towards Th2/Treg while LiCl treated aged DCs only reduced IFN-γ secretion but did not bias the response towards Th2/Treg. In summary, our data suggests that LiCl reduces inflammation in aged and young DCs via different mechanisms. Furthermore, the effect of LiCl is different on LPS and PAM3CSK4 responses.