Dimethyl fumarate activates the prostaglandin EP2 receptor and stimulates cAMP signaling in human peripheral blood mononuclear cells.

Dimethyl fumarate (DMF) was recently approved by the FDA for the treatment of relapsing remitting MS. The pathology of MS is a result of both immune dysregulation and oxidative stress induced damage, and DMF is believed to have therapeutic effects on both of these processes. However, the mechanisms of action of DMF are not fully understood. To determine if DMF is able to activate signaling cascades that affect immune dysregulation, we treated human peripheral blood mononuclear cells with DMF. We discovered that DMF stimulates cyclic adenosine monophosphate (cAMP) production after 1 min treatment in vitro. cAMP is a small molecule second messenger that has been shown to modulate immune response. Using pharmacological inhibitors, we determined that adenylyl cyclase mediates DMF induced cAMP production; DMF activated the prostaglandin EP2 receptor to produce cAMP. This response was not due to increased endogenous production of prostaglandin E2 (PGE2), but was enhanced by addition of exogenous PGE2. Furthermore, we determined that the bioactive metabolite of DMF, monomethyl fumarate (MMF), also stimulates cAMP production. These novel findings suggest that DMF may provide protection against MS by inhibiting immune cell function via the cAMP signaling pathway.

Lipoic Acid Stimulates cAMP Production in Healthy Control and Secondary Progressive MS Subjects.

Lipoic acid (LA) exhibits antioxidant and anti-inflammatory properties; supplementation reduces disease severity and T lymphocyte migration into the central nervous system in a murine model of multiple sclerosis (MS), and administration in secondary progressive MS (SPMS) subjects reduces brain atrophy compared to placebo. The mechanism of action (MOA) of LA's efficacy in suppression of MS pathology is incompletely understood. LA stimulates production of the immunomodulator cyclic AMP (cAMP) in vitro. To determine whether cAMP could be involved in the MOA of LA in vivo, we performed a clinical trial to examine whether LA stimulates cAMP production in healthy control and MS subjects, and whether there are differences in the bioavailability of LA between groups. We administered 1200 mg of oral LA to healthy control, relapsing remitting MS (RRMS) and SPMS subjects, and measured plasma LA and cAMP levels in peripheral blood mononuclear cells (PBMCs). There were no significant differences between the groups in pharmacokinetic (PK) parameters. Healthy and SPMS subjects had increased cAMP at 2 and 4 h post-LA treatment compared to baseline, while RRMS subjects showed decreases in cAMP. Additionally, plasma concentrations of prostaglandin E2 (PGE2, a known cAMP stimulator) were significantly lower in female RRMS subjects compared to female HC and SPMS subjects 4 h after LA ingestion. These data indicate that cAMP could be part of the MOA of LA in SPMS, and that there is a divergent response to LA in RRMS subjects that may have implications in the efficacy of immunomodulatory drugs. This clinical trial, "Defining the Anti-inflammatory Role of Lipoic Acid in Multiple Sclerosis," NCT00997438, is registered at https://clinicaltrials.gov/ct2/show/record/NCT00997438 .

Donor variability may mask dimethyl fumarate's effects on nuclear factor E2-related factor 2 in human peripheral blood mononuclear cells.

OBJECTIVE: Dimethyl fumarate (DMF) is an anti-inflammatory and antioxidant drug used to treat multiple sclerosis, but its mechanism(s) of action are not fully understood. In central nervous system (CNS) cells, DMF activates nuclear factor E2-related factor 2 (Nrf2), perhaps ameliorating oxidative stress-induced damage. However, it is not known whether DMF also activates Nrf2 in peripheral immune cells, which are known to participate in CNS demyelination. We conducted a single observation study to determine whether DMF can activate Nrf2 in peripheral immune cells in vitro. RESULTS: We performed enzyme-linked immunosorbent assays to measure Nrf2 activation in nuclear extracts of human peripheral blood mononuclear cells treated with DMF at time points from 0 to 6 h, initially determining that DMF did not activate Nrf2, and that the mechanism(s) of action of DMF may thus differ in the periphery compared to the CNS. However, further analyses of our data suggest that high Tmax variability is masking Nrf2 activation in individual donors. Additionally, there may be sub-populations of responders, perhaps related to genetic polymorphisms in Nrf2.

α-Tocopherol (vitamin E) stimulates cyclic AMP production in human peripheral mononuclear cells and alters immune function.

α-Tocopherol, the most biologically active member of the vitamin E family of fat soluble compounds, exhibits both antioxidant and anti-inflammatory properties. However, its mechanisms of action are not fully understood. Here, we show that, unlike other antioxidants, α-tocopherol stimulates the production of cyclic adenosine monophosphate (cAMP). Inhibitor studies demonstrate that the prostaglandin EP2 and EP4 receptors and adenylyl cyclases mediate the effects of α-tocopherol on cAMP production. Additionally, we show that α-tocopherol attenuates pro-inflammatory cytokine and chemokine production. This study provides novel evidence that α-tocopherol stimulates cAMP signaling, suggesting a mechanism of action for the immunomodulatory effects of vitamin E.