Cytokines Differently Define the Immunomodulation of Mesenchymal Stem Cells from the Periodontal Ligament

Abstract

Human periodontal ligament stem cells (hPDLSCs) play an important role in periodontal tissue homeostasis and regeneration. The function of these cells in vivo depends largely on their immunomodulatory ability, which is reciprocally regulated by immune cells via cytokines, particularly interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and interleukin (IL)-1β. Different cytokines activate distinct signaling pathways and might differently affect immunomodulatory activities of hPDLSCs. This study directly compared the effect of IFN-γ, TNF-α, or IL-1β treated primary hPDLSCs on allogenic CD4+ T lymphocyte proliferation and apoptosis in an indirect co-culture model. The effects of IFN-γ, TNF-α, and IL-1β on the expression of specific immunomodulatory factors such as intoleamine-2,3-dioxygenase-1 (IDO-1), prostaglandin E2 (PGE2), and programmed cell death 1 ligand 1 (PD-L1) and ligand 2 (PD-L2) in hPDLSCs were compared. The contribution of different immunomodulatory mediators to the immunomodulatory effects of hPDLSCs in the indirect co-culture experiments was assessed using specific inhibitors. Proliferation of CD4+ T lymphocytes was inhibited by hPDLSCs, and this effect was strongly enhanced by IFN-γ and IL-1β but not by TNF-α. Apoptosis of CD4+ T lymphocytes was decreased by hPDLSCs per se. This effect was counteracted by IFN-γ or IL-1β. Additionally, IFN-γ, TNF-α, and IL-1β differently regulated all investigated immunomediators in hPDLSCs. Pharmacological inhibition of immunomediators showed that their contribution in regulating CD4+ T lymphocytes depends on the cytokine milieu. Our data indicate that inflammatory cytokines activate specific immunomodulatory mechanisms in hPDLSCs and the expression of particular immunomodulatory factors, which underlies a complex reciprocal interaction between hPDLSCs and CD4+ T lymphocytes.

Immunomodulation of MSCs and MSC-Derived Extracellular Vesicles in Osteoarthritis

“…PGE2 secreted by MSCs can also inhibit T-cell proliferation by decreasing IL-2 and down-regulating IL-2 receptor, leading to impaired DNA binding activity of transcription factors through inhibition of Janus kinase 3 signaling (Burr et al, 2013 ). Under stimulation by proinflammatory factors such as TNF-α and IFN-γ, MSCs can inhibit the proliferation of T cells and induce the apoptosis of activated T cells by producing IDO (Behm et al, 2020 ), an iron-containing heme monomer membrane-binding protein that can catalyze the transformation of tryptophan into l -canine uric acid and picolinic acid. Tryptophan is an essential amino acid for the maintenance of T-cell activation and proliferation (Liu et al, 2016 ).…”

Continuing Effect of Cytokines and Toll-Like Receptor Agonists on Indoleamine-2,3-Dioxygenase-1 in Human Periodontal Ligament Stem/Stromal Cells

“…IDO-1 is one of the most investigated immunomediator, which was demonstrated to be one of the key functional immunomediator suppressing various immune cells (reviewed in [ 19 , 26 ]). Additionally, our previous study demonstrated via pharmacological inhibition the functional involvement of IDO-1 in the observed suppression of CD4 + T lymphocyte proliferation [ 25 ]. These IDO-1 based immunomodulatory mechanisms seem to play crucial roles in both the hPDLSCs’ in vivo regeneration potential and inflammatory processes [ 18 ].…”

“…In total, 250,000 hPDLSCs were seeded per well in 6-well plates using 3 mL DMEM supplemented with 10% FBS and 1% P/S. After 24 h incubation, hPDLSCs were stimulated with one of the following commercially available cytokines or TLRs: 100 ng/mL of human recombinant IFN-γ [ 25 , 36 ] (PeproTech, Rocky Hill, SC, USA), 10 ng/mL human recombinant TNF-α [ 25 , 37 ] (PeproTech, Rocky Hill, SC, USA), 5 ng/mL human recombinant IL-1β [ 25 , 38 ] (PeproTech, Rocky Hill, SC, USA), 1 µg/mL TLR-3 agonist Poly I/C [ 32 ] (Invivogen, San Diego, CA, USA) and 1 µg/mL TLR-2/1 agonist Pam3CSK4 [ 31 , 33 ] (Invivogen, San Diego, CA, USA). Stimulation was performed with 1 mL DMEM per well, supplemented with 1% P/S but without FBS.…”

“…In resting hPDLSCs immunomodulatory activities and also IDO-1 expression is generally low. Several environmental factors, such as inflammatory cytokines, strongly increase the production of IDO-1 and consequently boost the immunomodulatory activities of hPDLSCs [ 25 ]. These cytokines, such as interleukin (IL)-1β, tumor necrosis factor (TNF)-α and interferon (IFN)-γ, are produced by various immune cells [ 19 , 26 ].…”

Potential Suppressive Effect of Nicotine on the Inflammatory Response in Oral Epithelial Cells: An In Vitro Study

“…Isolation of total cellular mRNA, its transcription into cDNA, and qPCR were performed using the TaqMan ® Gene Expression Cells-to-CT™ kit (Ambion/Applied Biosystems, Foster City, CA, USA) as previously described [ 29 , 30 ]. Real-time PCR was performed on an Applied Biosystems Step One Plus real-time PCR instrument using TaqMan ® gene expression assays (all from Applied Biosystems, Foster City, CA, USA) with the following ID numbers: ICAM-1: Hs00164932_m1, IL-8: Hs00174103_m1, β-defensin: Hs00823638_m1, GAPDH: Hs99999905_m1.…”