Different maturation cocktails provide dendritic cells with different chemoattractive properties.

Ena Wang,Barbara Seliger,Chiara Massa,Carolin Thomas,Francesco Marincola

doi:10.1186/s12967-015-0528-7

Abstract

BackgroundDendritic cells (DC) are currently implemented as immunotherapeutic strategy for the treatment of tumor patients based on their central role in the immune system. Despite good results were obtained in vitro and in animal models, their clinical use has provided limited success suggesting the requirement to optimise the protocol for their production.MethodsA cDNA array was performed on FastDC obtained from the differentiation of human peripheral blood monocytes stimulated with the clinical gold standard or with two alternative maturation cocktails combining interferon (IFN)γ and ligands for different toll like receptors (TLR).ResultsA stronger modulation of the DC transcriptome with respect to immature DC was found in alternatively stimulated DC when compared to DC stimulated with the clinical gold standard. A major class of molecules differentially expressed using distinct DC stimulation protocols were chemokines. Validation of their differential expression pattern at the mRNA and protein level confirmed the secretion of inflammatory chemokines by the alternative DC. Functional analyses of the chemotactic properties of DC “wash out” supernatants highlighted the ability of alternative, but not of gold standard DC to efficiently recruit immune cells with a prevalence of monocytes. Effector cells belonging to the innate as well as adaptive immunity were also attracted and the interaction with alternative DC resulted in enhanced secretion of IFNγ and induction of cytotoxic activity. Using leukocytes from cancer patients, it was demonstrated that the monocyte-attracting activity targeted cells with an inflammatory phenotype characterised by high levels of HLA-DR expression.ConclusionsDespite other classes of immune modulatory genes differently expressed in the alternative DC require to be investigated and characterised regarding their functional consequences, the reduced maturation state and chemoattractive properties of the gold standard versus alternative DC clearly promote the necessity to change the clinically used maturation cocktail of DC in order to improve the outcome of patients treated with DC-based vaccines.

Highlights

Dendritic cells (DC) are currently implemented as immunotherapeutic strategy for the treatment of tumor patients based on their central role in the immune system
In order to improve the functionality of vaccine DC the established protocols have been modified by changing (1) the source of cells [2, 3], (2) the differentiation protocol when starting from monocytes or precursor cells [4,5,6] and (3) the composition of the maturation cocktails in order to provide all necessary functions to the DC [7,8,9]
Increased alteration of the DC transcriptome using alternative maturation cocktails We previously characterized the phenotype and functional activity of monocytes differentiated into DC using the shortened “FastDC” protocol and stimulated with the clinical gold standard cytokine cocktail or with alternative cocktails based on a combination of different toll like receptor (TLR) ligands with IFNγ

Summary

Introduction

Dendritic cells (DC) are currently implemented as immunotherapeutic strategy for the treatment of tumor patients based on their central role in the immune system. During the last two decades strategies have been developed to implement dendritic cell (DC)-based therapies for the treatment of cancer Despite their successful usage in murine models, this approach demonstrated only a limited efficacy in the human setting, . In addition to providing all the required signals for a proper activation of effector cells, an important requirement of vaccine DC is their ability to “reach” the effector cells, mediated either by their own migration or by the recruitment of effector cells Chemokines and their receptors exploit a central role in the correct homing of immune cells under homeostatic and inflammatory conditions [10]. The secretion of a number of pro-inflammatory chemokines was enhanced in alternatively matured DC They displayed an enhanced ability to recruit other immune cells to the vaccine DC proximity. Alterations in the set of expressed chemokines might be important for the choice of DC for the treatment of tumors known to be susceptible to a particular effector type attracted by the different chemokines

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Discussion

Conclusion