Potent Bidirectional Cross-Talk Between Plasmacytoid Dendritic Cells and γδT Cells Through BTN3A, Type I/II IFNs and Immune Checkpoints

Abstract

Plasmacytoid DCs (pDCs) and γδT cells are both critical players in immunosurveillance against pathogens and cancer due to their ability to sense microbes and cell stress through recognition of pathogen-associated molecular patterns or altered metabolism [phosphoantigens (PAgs)]. Their unique features, high functional plasticity and ability to interact with many immune cell types allow them to bridge innate and adaptive immunity, initiating and orientating widely immune responses, hence contributing to protective and pathogenic immune responses. Yet, despite strategic and closed missions, potential interactions between pDCs and γδT cells are still unknown. Here we investigated whether there is interplay between pDCs and γδT cells and the underlying molecular mechanisms. Purified human pDCs and γδT cells were cocultured in presence of TLR-L, PAg, and zoledronate (Zol) to mimic both infectious and tumor settings. We demonstrated that TLR7/9L-or Zol-stimulated pDCs drive potent γδT-cell activation, Th1 cytokine secretion and cytotoxic activity. Conversely PAg-activated γδT cells trigger pDC phenotypic changes and functional activities. We provided evidence that pDCs and γδT cells cross-regulate each other through soluble factors and cell-cell contacts, especially type I/II IFNs and BTN3A. Such interplay could be modulated by blocking selective immune checkpoints. Our study highlighted crucial bidirectional interactions between these key potent immune players. The exploitation of pDC-γδT cells interplay represents a promising opportunity to design novel immunotherapeutic strategies and restore appropriate immune responses in cancers, infections and autoimmune diseases.

Zdhhc2 Is Essential for Plasmacytoid Dendritic Cells Mediated Inflammatory Response in Psoriasis

“…Our results showed that deletion of Zdhhc2 in mice dramatically decrease the activation level of all three subsets of T cells including αβ T cells, γδ T cells, and DETC in psoriatic skin. Our new findings in Zdhhc2 deficient mice that both IFN-α production and T cell activation were significantly inhibited, were consistent with results from previous studies showing that IFN-α produced by pDCs was critical to T cell activation ( 24 , 25 ). Other reports indicate that in vitiligo and systemic lupus erythematosus, IFN-α-producing pDCs were also exhibited accumulation in perilesional skin, leading to T cells activation and recruitment ( 36 – 38 ).…”

“…Indeed a recent study showed that type I interferon producing pDCs were responsible for helper T cell activation ( 24 ). In addition, pDCs were found to drive γδ T cell activation through cytokine secretion such as IFN-α and TNF-α ( 25 ). Because we have demonstrated that pDC infiltration and IFN-α production was significantly inhibited in psoriatic skin of Zdhhc2 deficient mice, we next sought to determine whether T cell activation in psoriatic lesions of Zdhhc2 −/− mice was also inhibited.…”

“…It has been reported that T cells also play an important role in the occurrence of psoriasis, and IFN-α produced by pDCs induces T cell activation ( 5 , 24 , 25 ). Our results showed that deletion of Zdhhc2 in mice dramatically decrease the activation level of all three subsets of T cells including αβ T cells, γδ T cells, and DETC in psoriatic skin.…”

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“…Our results showed that deletion of Zdhhc2 in mice dramatically decrease the activation level of all three subsets of T cells including ab T cells, gd T cells, and DETC in psoriatic skin. Our new findings in Zdhhc2 deficient mice that both IFN-a production and T cell activation were significantly inhibited, were consistent with results from previous studies showing that IFN-a produced by pDCs was critical to T cell activation (24,25). Other reports indicate that in vitiligo and systemic lupus erythematosus, IFN-a-producing pDCs were also exhibited accumulation in perilesional skin, leading to T cells activation and recruitment (36)(37)(38).…”

“…Indeed a recent study showed that type I interferon producing pDCs were responsible for helper T cell activation (24). In addition, pDCs were found to drive gd T cell activation through cytokine secretion such as IFN-a and TNF-a (25). Because we have demonstrated that pDC infiltration and IFN-a production was significantly inhibited in psoriatic skin of Zdhhc2 deficient mice, we next sought to determine whether T cell activation in psoriatic lesions of Zdhhc2 −/− mice was also inhibited.…”