Peritumoral dermis of squamous cell carcinomas in renal transplant recipients contains less CD11c+ myeloid dendritic cells and FoxP3+ T cells compared to immunocompetent controls

BACKGROUND

Renal transplant recipients (RTR) have an increased risk of developing cutaneous squamous cell carcinomas (SCC). These SCC are often more aggressive than SCC in immunocompetent individuals.

OBJECTIVES

In this comparative study, we analysed the cell composition in the tissue immediately surrounding invasive SCC in immunosuppressed RTR and immunocompetent controls in an effort to further elucidate the role of the local immune system.

METHODS

Morphology and quantity of various dendritic cell (DC) subsets, macrophages and FoxP3+ T cells were analysed by immunohistochemical staining.

RESULTS

The number of CD11c+ myeloid DC and FoxP3+ T cells was significantly reduced in RTR, whereas the number of plasmacytoid DC, Langerhans cells and macrophages was similar in RTR and controls.

CONCLUSIONS

A reduction in CD11c+ mDC in peritumoral dermis in RTR might contribute to impaired immunosurveillance thus giving rise to an increased risk to develop aggressive SCC in these patients.

Characterization of monocyte-derived dendritic cells from immunosuppressed renal transplant recipients with and without squamous cell carcinomas

Renal transplant recipients (RTR) have a high risk of tumour development, especially cutaneous squamous cell carcinomas (SCC), due to long-term immunosuppressive therapy. RTR may develop multiple lesions over short time periods, and these are often more aggressive with a higher risk of local recurrence and metastasis resulting in increased morbidity and mortality in these patients. Therefore, we took the first step towards evaluating the possibility of generating a therapeutic vaccine based on monocyte-derived dendritic cells (moDC) for these patients. We analysed the phenotype and cytokine/chemokine profile of moDC from long-term immunosuppressed RTR with and without previous SCC. The number of peripheral blood mononuclear cells (PBMC) isolated per ml blood as well as the efficiency of generating moDC from peripheral blood mononuclear cells (PBMC) was similar in patients and immunocompetent controls. Phenotype and cytokine/chemokine profile of the moDC from immunosuppressed patients were similar to those from immunocompetent controls, making moDC-based immunotherapy a potential future treatment option for RTR with multiple SCC.

Type 1 regulatory T cells and regulatory B cells induced by tolerogenic dendritic cells

Dendritic cells (DC) are professional antigen-presenting cells that are capable of both activating immune responses and inducing tolerance. Several studies have revealed efficiency of therapeutic vaccination with tolerogenic DC (tolDC) in inhibition of experimental autoimmunity. The purpose of this study was to compare four different protocols for generation of tolDC - the antidiabetic drug troglitazone (TGZ DC), NF-κB inhibitor BAY 11-7082 (BAY DC), prostaglandin D2 metabolite 15d-PGJ2 (PGJ DC) and a combination of dexamethasone and 1α,25-dihydroxyvitamin D3 (DexVD3 DC) regarding phenotype, cytokine production and T cell stimulatory capacity. TGZ DC and BAY DC had a phenotype comparable to immature DC, while DexVD3 DC were more macrophage like. Analysis of cytokine production using cell culture supernatants from all DC populations revealed that DexVD3 DC were efficient producers of IL-10 and produced less pro-inflammatory cytokines. T cells primed with DexVD3 DC showed reduced proliferation, and further analyses of these T cells revealed that functionally effective type 1 regulatory T cells (Tr1) but not FoxP3(+) Treg were induced. Furthermore, DexVD3 DC promoted the induction of regulatory B cells (Breg). Together, these results indicate that DexVD3 DC have the best potential to be used in a tolerogenic antigen-presenting cell-based immunotherapy setting.