1,25-dihydroxyvitamin D3 induces stable and reproducible therapeutic tolerogenic dendritic cells with specific epigenetic modifications

Abstract

Autologous, antigen-specific, tolerogenic dendritic cells (tolDCs) are presently assessed to reverse and possibly cure autoimmune diseases such as type 1 diabetes (T1D). Good Manufacturing Practice production and clinical implementation of such cell therapies critically depend on their stability and reproducible production from healthy donors and, more importantly, patient-derived monocytes. Here the authors demonstrate that tolDCs (modulated using 1,25-dihydroxyvitamin D3 and dexamethasone) displayed similar features, including protein, transcriptome and epigenome profiles, between two international clinical centers and between T1D and healthy donors, validating reproducible production. In addition, neither phenotype nor function of tolDCs was affected by repeated stimulation with inflammatory stimuli, underscoring their stability as semi-mature DCs. Furthermore, tolDCs exhibited differential DNA methylation profiles compared with inflammatory mature DCs (mDCs), and this was already largely established prior to maturation, indicating that tolDCs are locked into an immature state. Finally, approximately 80% of differentially expressed known T1D risk genes displayed a corresponding differential DNA methylome in tolDCs versus mDCs and metabolic and immune pathway genes were also differentially methylated and expressed. In summary, tolDCs are reproducible and stable clinical cell products unaffected by the T1D status of donors. The observed stable, semi-mature phenotype and function of tolDCs are exemplified by epigenetic modifications representative of immature-stage cells. Together, the authors' data provide a strong basis for the production and clinical implementation of tolDCs in the treatment of autoimmune diseases such as T1D.

Distinct metabolic states guide maturation of inflammatory and tolerogenic dendritic cells

“…Single-cell heatmap overlay of selected immune markers demonstrated a progressive increase of HLA-DR and CD86 with maturation in control wells, which was reduced in both tolerogenic counterparts. Consistent with previous reports 12 , 38 , tol-DC exhibited a robust increase in CD14, CD141, and ILT3, and PD-L1 across all maturation stages (Fig. 4A , Supplementary Fig.…”

Functional Impact of Risk Gene Variants on the Autoimmune Responses in Type 1 Diabetes

“…Interestingly, only five of these genes were also reported as direct targets of VDR ( 170 ), leaving others to an indirect control by VDR-targeted transcription factors. Of the direct VitD3-targets, the expression of ORMDL3 , SH2B3 , IKZF1 , PTPN2 and IFIH1 genes was lower in tolDC while RAC2 and PTPN22 were higher in tolDC than in the inflammatory mDCs ( 17 , 18 ).…”

“…This natural immunomodulator influences the development and function of T cells, B cells and monocytes ( 172 , 174 , 175 ), and controls the ability of the immune system to dampen inflammation. In two independent studies we found that about a third of the transcripts encoded by non-HLA T1D risk genes were differentially expressed between inflammatory mDCs and VitD3-derived tolDCs ( 17 , 18 ). Interestingly, only five of these genes were also reported as direct targets of VDR ( 170 ), leaving others to an indirect control by VDR-targeted transcription factors.…”

“…The functional outcomes of the coding T1D risk variants have been reviewed recently ( 59 ), and a fine mapping of the 10 known susceptibility regions combined with functional analyses provided further insight in potentially causal missense and non-coding SNP variants ( 60 ). Many of these risk genes were differentially expressed in dendritic cells upon tolerogenic modulation ( 17 , 18 ). Hence, we here consider the functional roles in immune regulation of the minor T1D risk genes as such or when influenced by the SNP.…”

“…Indeed, many of the associated T1D risk genes are controlled by lymphoid enhancers or involved in immune networks ( 11 , 16 ). Our studies focusing on the differential transcriptome of tolerogenic (tolDC) versus inflammatory dendritic cells (mDCs) showed that a tolerogenic modulation of monocytes by 1,25(OH) 2 vitamin D3 (VitD3) induced a stable change in the expression of sets of these non-HLA risk genes ( 17 , 18 ), inspiring a hypothesis that quantitative and/or qualitative effects of the SNPs on the related gene products may reflect in a change of the immune regulatory vs. an immune activating balance. Here, we aim to review the knowledge of functional consequences of T1D risk SNPs on the regulation, expression and function of linked risk genes and further contemplate how this may impact the functionality of the effector vs. regulatory T cells, changing the balance between immune activation and suppression in the pancreas that is critical to attenuate chronic inflammation and an uncontrolled damage of insulin producing β-cells.…”