Nicotinamide Suppresses Hyperactivation of Dendritic Cells to Control Autoimmune Disease through PARP Dependent Signaling

Abstract

Dendritic cells (DCs) are crucial in initiating and shaping both innate and adaptive immune responses. Clinical studies and experimental models have highlighted their significant involvement in various autoimmune diseases, positioning them as promising therapeutic targets. Nicotinamide (NAM), a form of vitamin B3, with its anti-inflammatory properties, has been suggested, while the involvement of NAM in DCs regulation remains elusive. Here, through analyzing publicly available databases, we observe substantial alterations in NAM levels and NAM metabolic pathways during DCs activation. Furthermore, we discover that NAM, but not Nicotinamide Mononucleotide (NMN), significantly inhibits DCs over-activation in vitro and in vivo. The suppression of DCs hyperactivation effectively alleviates symptoms of psoriasis. Mechanistically, NAM impairs DCs activation through a Poly (ADP-ribose) polymerases (PARPs)-NF-κB dependent manner. Notably, phosphoribosyl transferase (NAMPT) and PARPs are significantly upregulated in lipopolysaccharide (LPS)-stimulated DCs and psoriasis patients; elevated NAMPT and PARPs expression in psoriasis patients correlates with higher psoriasis area and severity index (PASI) scores. In summary, our findings underscore the pivotal role of NAM in modulating DCs functions and autoimmune disorders. Targeting the NAMPT-PARP axis emerges as a promising therapeutic approach for DC-related diseases.

Keywords: NF-κB; PARP; dendritic cell; nicotinamide; psoriasis.

Figure 1

NAM inhibits DCs maturation and Ag presentation. (A) Schematic illustration of the NAM salvage pathway. (B) GSEA analysis of NAM salvage pathway in LPS-stimulated activated DCs from the GEO dataset (GSE185881). (C) Relative abundances of NAM in LPS-stimulated DCs at different time points. (D) Representative flow overlay histograms and statistical analysis of the expression levels of CD80, CD86, MHC-I, and MHC-II in vehicle- or NAM-treated BMDCs after stimulation with LPS (n = 3). (E) Statistical analysis of the expression levels of CD80, CD86, MHC-I, and MHC-II in vehicle- or NMN-treated BMDCs after stimulation with LPS (n = 3). (F) The percentage of EGFP⁺YAe⁺ cells in vehicle- or NAM-treated BMDCs after in vitro antigen uptake and presentation assay with Eα peptide (n = 3). (G) The percentage of EGFP⁺YAe⁺ cells in vehicle- or NMN-treated BMDCs after in vitro antigen uptake and presentation assay with Eα peptide (n = 3). Data are presented as means ± SD. *** p < 0.001; NS, not significant. Unpaired two-tailed Student’s t-test.

Figure 2

NAM impairs DC-mediated T cell priming. (A) Proliferation rates of CFSE-labeled OT-II cells incubated with vehicle- or NAM-treated BMDCs pulsed with OVA_323–339 at day 3 (n = 3). (B,C) Representative flow staining and quantification of IFNγ⁺, IL4^+, or IL17A⁺ OT-II cells incubated with vehicle- or NAM-treated BMDCs pulsed with OVA_323–339 (n = 3). (D) Proliferation rates of CFSE-labeled OT-II cells incubated with vehicle- or NMN-treated BMDCs pulsed with OVA_323–339 at day 3 (n = 3). (E) The Flow cytometry analysis and quantification of IFNγ⁺, IL4^+, or IL17A⁺ OT-II cells incubated with vehicle- or NMN-treated BMDCs pulsed with OVA_323–339 (n = 3). Data are presented as means ± SD. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001; NS, not significant. Unpaired two-tailed Student’s t-test.

Figure 3

NAM ameliorates the psoriasis-like skin inflammation in IMQ-induced mouse models. (A) Schematic diagram of psoriasis-like mouse model induction. Mice were topically treated with 62.5 mg IMQ on shaved back skin daily for 6 consecutive days. NAM (300 mg/kg per mouse) or PBS was intravenously injected into the mice 1 h before IMQ treatment on 6 consecutive days. Samples were harvested on day 6 for subsequent experiments. (B) Representative photos of mouse back skin treated with vehicle or NAM (n = 5). (C) Daily clinical scores (PASI) for disease severity from IMQ-induced C57BL/6 mice treated with vehicle or NAM (n = 5). (D) Back thickness of IMQ-induced C57BL/6 mice treated with vehicle or NAM (n = 5). (E) H&E staining of skin sections of IMQ-induced C57BL/6 mice treated with vehicle or NAM (n = 5). Scale bar = 100 μm. (F) Expression of pathogenic factors in the skin of IMQ-induced C57BL/6 mice treated with vehicle or NAM as determined by quantitative PCR (n = 5). Data are presented as means ± SD. ** p < 0.01, **** p < 0.0001. Unpaired two-tailed Student’s t-test.

Figure 4

NAM inhibits DCs activation and infiltration in psoriasiform skin inflammation. (A,B) Representative flow cytometry plots (A) and statistical analysis (B) of CD45⁺CD11c⁺ cells in Draining lymph nodes (DLN) from IMQ-induced C57BL/6 mice treated with vehicle or NAM (n = 5). (C) Statistical analysis of CD45⁺CD11c⁺ cells in the skin from IMQ-induced C57BL/6 mice treated with vehicle or NAM (n = 5). (D,E) The statistical analysis of DC activation in DLN (D) and skin (E) on day 6 from IMQ-induced C57BL/6 mice treated with vehicle or NAM (n = 5). Data are presented as means ± SD. *** p < 0.001, **** p < 0.0001. Unpaired two-tailed Student’s t-test.

Figure 5

NAM regulates DC activation through a PARP-dependent NF-κB signaling pathway. (A) RNA expression levels of NAM salvage pathway-related genes in LPS-stimulated activated DCs (GSE235310). (B) Schematic illustration of the regulation between NAM, PARP, and NF-κB. (C) mRNA expression of Parp3, Parp9, Parp10 and Parp11 in vehicle- or LPS-stimulated BMDCs (n = 3). (D) mRNA expression of Cd80 and Cd86 in vehicle-, NAM- or PARP inhibitor (Venadaparib)-treated BMDCs after stimulation with LPS (n = 3). (Control: without LPS stimulation). (E) mRNA expression of Tnf and Il1b in vehicle-, NAM- or Venadaparib-treated BMDCs after stimulation with LPS (n = 3). (Control: without LPS stimulation). (F,G) Representative flow overlay histograms (F) and statistical analysis (G) of BMDCs treated as indicated and stimulated by LPS (n = 3). (H) Fold change for the inhibitory ability of NAM in vehicle- or Venadaparib-treated BMDCs (n = 3). Data are presented as means ± SD. ** p < 0.01, *** p < 0.001, **** p < 0.0001. Unpaired two-tailed Student’s t-test.

Figure 6

NAMPT is obviously upregulated during DCs activation in psoriasis. (A) GSEA analysis of DCs pathway in skin samples from psoriasis patients and healthy controls from the GEO dataset (GSE121212). (B) GSEA analysis of NAM salvage pathway in skin samples from psoriasis patients and healthy controls from the GEO dataset (GSE121212). (C) GSEA analysis of NF-κB signaling pathway between NAMPT high- and low-level groups in clinical samples from the GEO dataset (GSE121212). (D) Correlation heatmap of NAM salvage pathway-related genes with the infiltration levels of various immune cell types in the skin of psoriasis patients and healthy controls from the GEO dataset (GSE121212). (E) GSEA analysis of DCs function-related gene sets in skin samples from psoriasis patients and healthy controls from the GEO dataset (GSE121212).

Figure 7

Upregulation of the NAMPT-PARP axis in DCs and psoriasis predicts higher PASI score. (A) Correlation of RNA expression levels between NAMPT and PARP family genes in LPS-stimulated DCs and control cells from the GEO dataset (GSE235310). (B) RNA expression levels of NAM salvage pathway-related genes in skin samples from psoriasis patients and healthy controls from the GEO dataset (GSE121212). (C) Correlation of RNA expression levels between NAMPT and PARP family genes in skin samples from psoriasis patients and healthy controls from the GEO dataset (GSE121212). (D) Correlation between PASI score and RNA expression levels of NAM salvage pathway-related genes from the GEO dataset (GSE121212).