The active translation of MHCII mRNA during dendritic cells maturation supplies new molecules to the cell surface pool

Human leukocyte antigen class II quantification by targeted mass spectrometry in dendritic-like cell lines and monocyte-derived dendritic cells

The major histocompatibility complex II (HLA-II) facilitates the presentation of antigen-derived peptides to CD4+ T-cells. Antigen presentation is not only affected by peptide processing and intracellular trafficking, but also by mechanisms that govern HLA-II abundance such as gene expression, biosynthesis and degradation. Herein we describe a mass spectrometry (MS) based HLA-II-protein quantification method, applied to dendritic-like cells (KG-1 and MUTZ-3) and human monocyte-derived dendritic cells (DCs). This method monitors the proteotypic peptides VEHWGLDKPLLK, VEHWGLDQPLLK and VEHWGLDEPLLK, mapping to the α-chains HLA-DQA1, -DPA1 and -DRA1/DQA2, respectively. Total HLA-II was detected at 176 and 248 fmol per million unstimulated KG-1 and MUTZ-3 cells, respectively. In contrast, TNF- and LPS-induced MUTZ-3 cells showed a 50- and 200-fold increase, respectively, of total α-chain as measured by MS. HLA-II protein levels in unstimulated DCs varied significantly between donors ranging from ~ 4 to ~ 50 pmol per million DCs. Cell surface HLA-DR levels detected by flow cytometry increased 2- to 3-fold after DC activation with lipopolysaccharide (LPS), in contrast to a decrease or no change in total HLA α-chain as determined by MS. HLA-DRA1 was detected as the predominant variant, representing > 90% of total α-chain, followed by DPA1 and DQA1 at 3-7% and ≤ 1%, respectively.

miR-181d regulates human dendritic cell maturation through NF-κB pathway

OBJECTIVES

MicroRNAs (miRNAs) are considered as the cellular regulators which post-transcriptionally modulate gene expression in diverse biological processes including cell development and immunity. In this study, we investigated functions of miR-181d in dendritic cells (DCs) maturation, and the underlying mechanisms were also explored.

MATERIALS AND METHODS

Here we did the miRNA screening in human DCs in response to lipopolysaccharides (LPS) by quantitative real-time PCR (qRT-PCR). The expressions of DCs maturation markers were measured after miRNA mimics transfections. The pharmacological inhibitors of signalling pathways were applied to examine miR-181d effect on DCs maturation by Western blot. Luciferase assay and mixed lymphocyte reaction (MLR) were also performed to reveal the target gene of miR-181d and test the viability of T cells treated with miR-181d transfected DCs.

RESULTS

Overexpression of miR-181d per se is sufficient to promote DCs maturation, and up-regulate CD80 and CD83 expressions without LPS. Besides, we showed that miR-181d activated NF-κB pathway and also promoted the expression of pro-inflammatory cytokine IL12 and TNF-α. Inhibition of NF-κB pathway suppressed DCs maturation. Luciferase reporter assay and target gene knockdown assay indicated that miR-181d targets regulator cylindromatosis (CYLD), a primary negative regulator of NF-κB pathway. MLR assay showed that miR-181d-transfected DCs could promote T-cell proliferation than iDCs in vitro.

CONCLUSION

Our study demonstrates that miR-181d is required for DCs maturation through the activation of NF-κB pathway by targeting CYLD.

Effects of some endocrine disruptors on cell cycle progression and murine dendritic cell differentiation

Endocrine disruptor chemicals (EDCs), which are predominantly present in the environment, are able to mimic or antagonise the biological activity of hormones primarily through the interaction with specific receptors. The main consequences are adverse effects on the growth and development of reproductive organs, the induction of cancer and effects on neuronal differentiation. In this study, we investigated the ability of certain EDCs, Bisphenol A (BPA), Bisphenol B (BPB), Bisphenol F (BPF), 4-n Nonylphenol (NP) and Octylphenol (OP), belonging to a homogeneous group of phenol origin, to interfere with specific cellular processes, namely, proliferation, by using MCF-7 breast carcinoma cells, and differentiation, by using murine bone marrow dendritic cells. We correlated the data on cell growth with the stimulation of cell cycle progression, which could become a step in the development of cancer, and we established a proliferation ranking between the tested EDCs: NP>BPA>OP>BPB>BPF. In addition, we investigated the ability of NP, BPA and OP to induce the differentiation of dendritic cells, the powerful antigen-presenting cells of the immune system. The differentiation and activation of these cells could affect a well-regulated immune response and determine an allergic sensitisation. We found that BPA and NP were active in determining differentiation.

Post-apoptotic tumors are more palatable to dendritic cells and enhance their antigen cross-presentation activity

Critical issues for cytotoxic lymphocyte (CTL) cross-priming are (a) the maturation state of dendritic cells (DC), (b) the source of the tumor-associated antigens (TAA) and (c) the context in which they are delivered to DCs. Drug-induced apoptosis has recently been implicated in CTL cross-priming. However, since drug-treatment produces in vivo more tumor cells than the DC default apoptotic clearance program can cope with, they are expected to proceed to secondary necrosis and change their molecular pattern. Here we have addressed this issue on renal carcinoma cells (RCC) by using different apoptotic stimuli. UVC, but not gamma-irradiation or anthracyclins, induced after 4h treatment of the RCC cell line K1 a combination of apoptotic (phosphatydilserine and calreticulin plasma membrane mobilization) and necrotic (membrane incompetence) features. Heat shock protein (Hsp)-70 and chromatin-bound high mobility box 1 HMGB1 protein, typical of necrosis, were released during the further 20h and thus made accessible to co-cultured monocyte-derived immature (i) DC. UVC-treated, secondary necrotic RCC cell lines were cross-presented with higher efficiency by cytokine-matured (m) DC than their early apoptotic (i.e. gamma-irradiated) counterpart. Upstream events such as increased tumor uptake, activation of genes involved in the antigen-processing machinery, and increased expression of costimulatory and maturation molecules were also observed after loading iDC with secondary necrotic, but not apoptotic, tumor cells. These data offer a description of the molecular and immunogenic characteristics of post-apoptotic tumors which can be exploited to increase the efficiency of in vivo and ex vivo TAA delivery to the DC cross-presentation pathway.