Background/Purpose:

Systemic lupus erythematosus (SLE) is characterized by chronic stimulation of the innate immune system by endogenous nucleic acids through toll-like receptors (TLRs) pathway, which results in the elevation of interferon-alfa (IFN-α). Though glucocorticoid have been widely used to treat autoimmune diseases for their strong anti-inflammatory effects, a recent research has found that TLRs recognition of self nucleic acids hampers the effects of glucocorticoid in lupus. Hydroxychloroquine has been reported to block the TLRs.We want to evaluate whether hydroxychloroquine and/or glucocorticoid influence the production of IFN-α stimulated by TLR-9 agonist in human peripheral blood mononuclear cells (PBMCs). Moreover, we want to explore whether hydroxychloroquine influences the expression of signal proteins in the TLR-9 pathway.

Methods:

 Freshly isolated PBMCs of healthy donors were stimulated with the TLR-9 agonist, CpG oligodeoxynucleotides (CpG-A ODN)-2216, then treated with hydroxychloroquine and/or different doses of glucocorticoid (hydrocortisone: low dose (10^-6M), median dose (10^-5M), high dose (10^-4M), pulse dose (10^-3M)). The changes in the expression of IFN-α and signal proteins (TLR7, TLR9, MyD88, AP-1, IKK-α, NF-κB) in PBMCs were detected by real time PCR.

Results:

 (1) Hydroxychloroquine significantly reversed the elevation of IFN-α caused by ODN 2216 (p=0.005), and in low dose (p=0.017), median dose (p=0.01) and high dose (p<0.001) of glucocorticoid, while could not significantly down-regulate the expression of IFN-α stimulated by ODN 2216 in pulse dose of glucocorticoid (p=0.05). (2) Hydroxychloroquine had no effects on the expression of TLR7, TLR9, MyD88, AP-1, IKK-α and NF-κB in PBMCs stimulated by ODN 2216. (3) Pluse dose of glucocorticoid could increase the production of IFN-α stimulated by ODN 2216 to some extent. (4) Pluse dose of glucocorticoid could significantly elevate the expression of TLR9 (p=0.016), IKK-α (P=0.025) and NF-κB (P<0.001) in the TLR pathway .

Conclusion:

(1) Hydroxychloroquine hampers the critical pathogenesis of SLE that the IFN-α expression elevates in PBMCs through TLR-9 recognition of nucleotides, which is irresponsive to glucocorticoid alone. This result suggests that combination with hydroxychloroquine may help glucocorticoid to achieve a better disease control. (2) Hydroxychloroquine does not significantly influence signal proteins (TLR7, TLR9 MyD88, AP-1, IKK-α and NF-κB) in the TLR pathway, which implies its weak influence in innate immunity. (3) The side-effects of pluse dose glucocorticoid in the elevation of IFN-α may related to the elevated expression of TLR9, IKK-α and NF-κB in PBMCs stimulated by ODN 2216.

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« Back to 2013 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/hydroxychloroquine-reverse-the-elevation-of-interferon-alfa-initiated-by-tlr-9-agonist-which-irresponsive-to-glucocorticoid/