Laquinimod dampens IL-1β signaling and Th17-polarizing capacity of monocytes in patients with MS

Abstract

ObjectiveTo assess the impact of laquinimod treatment on monocytes and to investigate the underlying immunomodulatory mechanisms in MS.MethodsIn 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.ResultsLaquinimod 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.ConclusionsOur 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.

Astrocytes and Inflammatory T Helper Cells: A Dangerous Liaison in Multiple Sclerosis

“…Laquinimod (LQ) is a quinoline-3-carboxamide derivate under clinical trial evaluation for the treatment of RRMS ( 179 ). In EAE, LQ treatment ameliorated disease progression by reducing the polarization and recruitment of Th17 cells as well as the production of inflammatory cytokines ( 180 , 181 ). Treatment of human astrocytes with LQ inhibited IL-1β-induced downregulation of glutamate transporters GLAST and GLT1 and restored astrocyte glutamate uptake ( 178 ).…”

Monocytes in central nervous system remyelination

“…One possibility which may account for this result is that CCR2 + monocytes require IL‐1β signaling to migrate into the CNS (Paré et al, 2018), and IL‐1R inhibition may have therefore prevented the presence of regenerative infiltrating monocytes in lesions. In addition, another drug previously explored for treatment of MS, Laquinimod, acts to reduce secretion of IL‐1β by monocytes via NF‐kB signaling (Engel et al, 2021), and has shown limited efficacy in clinical trials (Giovannoni et al, 2020; Thöne & Linker, 2016). It is therefore conceivable that inflammasome‐targeting drugs may compromise adequate influx of classical monocytes to aid in remyelination – a postulate which warrants further investigation.…”

Laquinimod Inhibits Microglial Activation, Astrogliosis, BBB Damage, and Infarction and Improves Neurological Damage after Ischemic Stroke

“…23 Many in vitro studies indicate that LAQ displays beneficial effects in various disease model. Engels et al reported that LAQ inhibits IL-1β signaling and Th17polarizing capacity of monocytes in patients with MS. 24 Mishra et al demonstrated that LAQ decreased the increase of the levels of several pro-and anti-inflammatory cytokines, including TNF and IL-6 and IL-10, in human microglia by lipopolysaccharide (LPS). 20 It is well known that glial activation is involved in mediating neuroinflammation.…”