Additive immunosuppressive effect of leflunomide and hydroxychloroquine supports rationale for combination therapy for Sjögren’s syndrome

Abstract

Objective: Effective treatment for primary Sjögren's syndrome (pSS) is not available. pSS immunopathology involves a variety of immune-cells and dysregulated pathways; targeting several pathways instead of only one could therefore be effective. Treatment with leflunomide (LEF) and hydroxychloroquine (HCQ) might be successful given their unique immunosuppressive properties. We aimed to study the in vitro effects of LEF, HCQ and their combination on T-and B-cell proliferation, cytokine and immunoglobulin production by activated PBMCs. Methods: PBMCs of six healthy individuals and nine pSS patients were stimulated with superantigen and TLR9 agonist to mimic the hallmark features. LEF, HCQ and their combinations were tested at clinically observed concentrations and proliferation, cytokine and immunoglobulin production were measured. Results: TCR/TLR9 activation of PBMCs induced strong proliferation of T and B-cells and production of CXCL13, IFN-α, IFN-γ, IgG and IgM. LEF dose-dependently inhibited all measured parameters, where HCQ potently and dose-dependently decreased B cell proliferation, CXCL13, IFN-α, IgG and IgM production. At different concentration combinations, HCQ and LEF inhibited several immune hallmark features more potently than each single compound. Conclusion: A combination of LEF and HCQ at clinically applicable concentrations additively inhibits immune activation, supporting a potential implementation of this drug combination in pSS treatment.

Salivary gland epithelial cells from patients with Sjögren’s syndrome induce B-lymphocyte survival and activation

“…Even tofacitinib, which targets numbers of pro-inflammatory cytokines, was not successful. Leflunomide, a pyrimidine synthesis inhibitor that inhibit B-lymphocyte proliferation and cell cycle progression [10,32], as well as PI3K and BTK inhibitors (targeting at the same time CXCL13, BAFF and IL6 signaling [33]) decreased B-lymphocyte viability in co-cultures. Lastly, PI3K was the only inhibitor to maintain an inhibitory effect under poly(I:C) stimulation, which suggests that in a local IFN-rich environment, such as pSS salivary glands, PI3K inhibition might be the most efficient option.…”

“…Given some recent clinical results [10], we also looked at the effect of the association of leflunomide and hydroxychloroquine. Leflunomide decreased B-lymphocyte viability in coculture, but this effect was lost in the presence of poly(I:C) ( Figure 5I and J).…”

Dendritic cells’ characteristics in patients with treated systemic lupus erythematosus

“…Immunosuppressive treatment, in general, mainly acts on the proliferating cells, such as T and B cells, and stops their differentiation and expansion. Hydroxychloroquine (HCQ) modifies activity of the antigen-presenting cells (DCs and monocytes) (van der Heijden et al, 2019). In the light of given data, HCQ could have the greatest impact on our results.…”

Umbilical Mesenchymal Stem Cell-derived Exosomes Regulate CD4+ T cells in Patients with Primary Sjogren's Syndrome through the Autophagy Pathway

“…The speci c mechanism may be that after autophagy inhibition in CD4 + T cells, CDKN1B aggregation of a negative regulator of cyclin-dependent kinase is promoted, causing CD4 + T cells to not enter the S phase after T cell receptor (TCR) stimulation and inhibiting CD4 + T cell proliferation [53] . Another study also showed that HCQ inhibits peripheral blood T cell proliferation in patients with pSS by inhibiting TCR/ Toll-like receptor 9 [54] . Interestingly, this study found that CD4 + T cell proliferation was inhibited after RAPA-induced autophagy, contrary to the expected results of enhanced proliferation with increased autophagy levels.…”