Laquinimod dampens IL-1β signaling and Th17-polarizing capacity of monocytes in patients with MS
Sinah Engel1, Valérie Jolivel1, Stefan H-P Kraus1
1From the Department of Neurology (S.E., V.J., S.H.-P.K., K.R., F.L.), Focus Program Translational Neuroscience (FTN), University Medical Center of the Johannes Gutenberg University of Mainz, Germany; Biopathology of Myelin (V.J.), Neuroprotection and Therapeutic Strategy, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), University of Strasbourg, France; Institute for Molecular Medicine (M.Z., F.C.K., A.W.), University Medical Centre of the Johannes Gutenberg University of Mainz, Germany; Sheba Cancer Research Center (M.Z.), Chaim Sheba Academic Medical Center, Ramat Gan, Israel; Department of Neurology (H.T.), University of Ulm, Germany and Specialty Clinic of Neurology Dietenbronn, Schwendi, Germany; Clinical Neuroimmunology Unit (R.F.), San Raffaele Scientific Institute, Milan, Italy; and Department of Dermatology (F.C.K.), Heidelberg University Hospital, Heidelberg, Germany.
Objective:
To assess the impact of laquinimod treatment on monocytes and to investigate the underlying immunomodulatory mechanisms in MS.
Methods:
In this cross-sectional study, we performed in vivo and in vitro analyses of cluster of differentiation (CD14+) monocytes isolated from healthy donors (n = 15), untreated (n = 13), and laquinimod-treated patients with MS (n = 14). Their frequency and the expression of surface activation markers were assessed by flow cytometry and the viability by calcein staining. Cytokine concentrations in the supernatants of lipopolysaccharide (LPS)-stimulated monocytes were determined by flow cytometry. The messenger ribonucleic acid (mRNA) expression level of genes involved in cytokine expression was measured by quantitative PCR. The LPS-mediated nuclear factor kappa-light-chain-enhancer of activated B-cell (NF-κB) activation was determined by the quantification of the phosphorylation level of the p65 subunit. Laquinimod-treated monocytes were cocultured with CD4+ T cells, and the resulting cytokine production was analyzed by flow cytometry after intracellular cytokine staining. The interleukin (IL)-17A concentration of the supernatant was assessed by ELISA.
Results:
Laquinimod did not alter the frequency or viability of circulating monocytes, but led to an upregulation of CD86 expression. LPS-stimulated monocytes of laquinimod-treated patients with MS secreted less IL-1β following a downregulation of IL-1β gene expression. Phosphorylation levels of the NF-κB p65 subunit were reduced after laquinimod treatment, indicating a laquinimod-associated inhibition of the NF-κB pathway. T cells primed with laquinimod-treated monocytes differentiated significantly less into IL-17A-producing T helper (Th)-17 cells.
Conclusions:
Our findings suggest that inhibited NF-κB signaling and downregulation of IL-1β expression in monocytes contributes to the immunomodulatory effects of laquinimod and that the impairment of Th17 polarization might mediate its disease-modifying activity in MS.
