Background/Purpose:

DM is an autoimmune disease with cutaneous symptoms often accompanied by inflammatory muscle and/or lung disease. Current therapies for DM are often toxic and ineffective. Ajulemic acid (AJA) is a synthetic, non-psychoactive cannabinoid potentially useful for treating DM. Experiments presented here quantify the capacity of AJA to suppress the secretion of TNF-α and IFN-α, two pro-inflammatory cytokines implicated in the pathogenesis of DM, from the peripheral blood mononuclear cells (PBMCs) of DM patients.

Methods:

PBMCs were isolated from the blood of 22 DM patients and then treated with 0, 3, 10 and 15 µM concentrations of AJA and incubated at 37°C and 5.0% CO₂ for 18 hours both with and without lipopolysaccharide (LPS) in the case of TNF-α and with and without CpG oligonucleotides (CpG) in the case of IFN-α. LPS and CpG were used to stimulate secretion of TNF-α and IFN-α, respectively, in order to ensure sufficient production for quantifying the effects of AJA via ELISA. Statistical analyses were performed on TNF-α and IFN-α secretion values normalized by natural log transformation, and unstimulated TNF-α secretion values below 2 pg/ml were excluded from analysis as outliers.

Results:

The LPS-stimulated PBMCs treated with 0 (n=17), 3 (n=16), 10 (n=16) and 15 (n=15) μM AJA secreted mean (standard deviation = SD) TNF-α values of 7.37 (1.33), 7.73 (1.03), 5.60 (1.91) and 4.20 (1.92) pg/ml, respectively. There was a statistically significant difference between the means using one-way ANOVA analysis (p<0.0001). In the post hoc analysis, AJA suppressed the secretion of TNF-α from LPS-stimulated PBMCs at 10 μM AJA (adjusted p=0.0115) and 15 μM AJA (adjusted p<0.0001), but not at 3 μM AJA (adjusted p=0.9098), when compared to LPS-stimulated PBMCs not treated with AJA. Unstimulated PBMCs treated with 0 (n=11), 3 (n=9), 10 (n=9) and 15 (n=7) μM AJA secreted mean (SD) TNF-α values of 2.27 (1.40), 2.47 (1.75), 1.83 (1.57) and 0.14 (1.72) pg/ml, respectively. Analysis by one-way ANOVA found a statistically significant difference between the means (p=0.0303). In the post hoc analysis, AJA suppressed the secretion of TNF-α from unstimulated PBMCs at 15 μM AJA (adjusted p=0.0444), but not at 3 μM AJA (adjusted p=0.9925) or 10 μM AJA (adjusted p=0.9274), when compared to unstimulated PBMCs not treated with AJA.

CpG-stimulated PBMCs treated with 0 (n=8), 3 (n=7), 10 (n=8) and 15 (n=7) μM AJA secreted mean (SD) IFN-α values of 5.33 (0.77), 1.38 (2.19), 1.06 (0.78) and -0.03 (1.68) pg/ml, respectively. There was a statistically significant difference between the means using one-way ANOVA analysis (p<0.0001). In the post hocanalysis, AJA suppressed IFN-α secretion from CpG-stimulated PBMCs at 3 μM AJA (adjusted p=0.0004), 10 μM AJA (adjusted p=0.0010) and 15 μM AJA (adjusted p=0.0003) when compared to CpG-stimulated PBMCs not treated with AJA. Unstimulated PBMCs secreted too little IFN-α to test the effects of AJA.

Conclusion:

AJA is a novel, non-psychoactive cannabinoid that suppressed secretion of TNF-α and IFN-α from the PBMCs of DM patients in vitro. Thus, AJA may offer patients with DM an effective therapy with less toxicity than other treatments currently available.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ajulemic-acid-is-a-novel-cannabinoid-that-suppresses-the-secretion-of-tnf-and-ifn-from-the-peripheral-blood-mononuclear-cells-of-dm-patients-in-vitro/