Phosphonate-Modified Cellulose Nanocrystals Potentiate the Th1 Polarising Capacity of Monocyte-Derived Dendritic Cells via GABA-B Receptor

Abstract

Purpose Phosphonates, like 3-AminoPropylphosphonic Acid (ApA), possess a great potential for the therapy of bone tumours, and their delivery via cellulose nanocrystals (CNCs) seems a promising approach for their increased efficacy in target tissues. However, the immunological effects of CNC-phosphonates have not been investigated thoroughly. The main aim was to examine how the modification of CNCs with phosphonate affects their immunomodulatory properties in human cells. Methods Wood-based native (n) CNCs were modified via oxidation (ox-CNCs) and subsequent conjugation with ApA (ApA-CNCs). CNCs were characterised by atomic force microscopy (AFM) and nanoindentation. Cytotoxicity and immunomodulatory potential of CNCs were investigated in cultures of human peripheral blood mononuclear cells (PBMCs) and monocyte-derived dendritic cells (MoDCs)/T cells co-cultures by monitoring phenotype, cytokines production, allostimulatory and Th/Treg polarisation capacity. Results AFM showed an increase in CNCs' thickens, elasticity modulus and hardness during the modification with ApA. When applied at non-toxic doses, nCNCs showed a tolerogenic potential upon internalisation by MoDCs, as judged by their increased capacity to up-regulate tolerogenic markers and induce regulatory T cells (Treg), especially when present during the differentiation of MoDCs. In contrast, ox- and ApA-CNCs induced oxidative stress and autophagy in MoDCs, which correlated with their stimulatory effect on the maturation of MoDCs, but also inhibition of MoDCs differentiation. ApA-CNC-treated MoDCs displayed the highest allostimulatory and Th1/CTL polarising activity in co-cultures with T cells. These effects of ApA-CNCs were mediated via GABA-B receptor-induced lowering of cAMP levels in MoDCs, and they could be blocked by GABA-B receptor inhibitor. Moreover, the Th1 polarising and allostimulatory capacity of MoDCs differentiated with ApA-CNC were largely preserved upon the maturation of MoDCs, whereas nCNC- and ox-CNC-differentiated MoDCs displayed an increased tolerogenic potential. Conclusion The delivery of ApA via CNCs induces potent DC-mediated Th1 polarisation, which could be beneficial in their potential application in tumour therapy.

Sitagliptin Induces Tolerogenic Human Dendritic Cells

“…In addition, imMODCs were characterized by lower expression of HLA-DR and NLRP3 inflammasome in comparison with mMoDCs that were treated with maturation-inducing stimuli. These findings are in agreement with already published papers [34][35][36][37][38].…”

“…Furthermore, MoDCs are mostly used DCs in vaccination protocols in clinical trials [34]. In most of our papers published to date including the last one [35], we provided evidence that imMoDCs down-regulate CD14 (a main monocyte marker) and acquire CD1a (a DC marker). Most frequently, CD1a is not expressed on all imMoDCs, so CD1a+ and CD1a-DCs are developed, which differ by some functional properties [36].…”

Exogenous α-ketoglutarate Modulates Redox Metabolism and Functions of Human Dendritic Cells, Altering Their Capacity to Polarise T Cell Response

“…To evaluate the maturation capacity of αKG-differentiated and control moDCs, the cells were stimulated with LPS/IFN-γ which are known to induce their Th1 polarising capacity 19 , 24 , 40 . Expectedly, LPS/IFN-γ up-regulated the expression of HLA-DR, IL-1β, CD83, CD86, CD40, CCR7, IL-12, NLRP3 and TNF-α by control moDCs.…”

“…The metabolic activity of PBMCs cultivated with α-KG was analysed after 24h and 48h in an MTT assay. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Merk Sigma) at the final concentration of 0.5 mg/mL, was performed as described previously 24 .…”

“…Apoptosis and necrosis of PBMCs were analysed by staining the permeabilised and non-permeabilised cells, with propidium iodide (PI, 50 μg/mL, Sigma-Aldrich), respectively, and the analyses by flow cytometry. The total % of dead (predominantly necrotic) cells was determined as the % of PI + cells, whereas the % of apoptotic cells was determined by analysing sub-G1 peak in the samples that were fixed/permeabilised with ice-cold 75% ethanol, as described previously 24 .…”