IFN-beta1b augments glucocorticoid-induced suppression of tumor necrosis factor-alpha production by increasing the number of glucocorticoid receptors on a human monocytic cell line

Antimalarial drugs inhibit IFNα-enhanced TNFα and STAT4 expression in monocytes: implication for systemic lupus erythematosus

OBJECTIVES

To analyse the influence of IFNα on TNFα production by human peripheral blood mononuclear cells (PBMCs), as well as the possible interference of this cytokine on the effect of antimalarial drugs, TNFα regulators widely used in the treatment of systemic lupus erythematosus (SLE).

METHODS

PBMCs, monocytes or T cells were treated with IFNα alone or simultaneously to cellular stimuli as well as in the presence or absence of chloroquine. Supernatants from such cultures were collected to quantify TNFα by ELISA. TNFα and STAT4 expression in cultured cells were analysed by intracellular flow cytometry. In addition, STAT4 gene expression and serum levels of TNFα and IFNα were quantified in 53 SLE patients and 45 controls.

RESULTS

IFNα alone did not modify significantly TNFα production, but an increase was observed in stimulated PBMC. Further analyses showed that monocytes were the cellular population responsible for this effect. In addition, IFNα treatment increased STAT4 in stimulated monocytes, suggesting that TNFα upregulation could be mediated by STAT4. On the other hand, the analysis of the antimalarial effect showed that chloroquine was able to inhibit in vitro the expression of TNFα and STAT4 enhanced by IFNα. In antimalarial-treated SLE patients, however, only those with high IFNα serum levels presented lower expression of STAT4.

CONCLUSIONS

IFNα treatment enhances the induction of TNFα and STAT4 in stimulated monocytes, an effect inhibited in vitro by chloroquine treatment. However, the consequence of antimalarial treatment on SLE patients could be different depending on their IFNα serum levels.

Type I IFN and TNFα cross-regulation in immune-mediated inflammatory disease: basic concepts and clinical relevance

A cross-regulation between type I IFN and TNFα has been proposed recently, where both cytokines are hypothesized to counteract each other. According to this model, different autoimmune diseases can be viewed as disequilibrium between both cytokines. As this model may have important clinical implications, the present review summarizes and discusses the currently available clinical evidence arguing for or against the proposed cross-regulation between TNFα and type I IFN. In addition, we review how this cross-regulation works at the cellular and molecular levels. Finally, we discuss the clinical relevance of this proposed cross-regulation for biological therapies such as type I IFN or anti-TNFα treatment.