CD160 is a member of the immunoglobulin superfamily with a pattern of expression mainly restricted to cytotoxic cells. To assess the functional relevance of the HVEM/CD160 signaling pathway in allogeneic cytotoxic responses, exon 2 of the CD160 gene was targeted by CRISPR/Cas9 to generate CD160 deficient mice. Next, we evaluated the impact of CD160 deficiency in the course of an alloreactive response. To that aim, parental donor WT (wild-type) or CD160 KO (knock-out) T cells were adoptively transferred into non-irradiated semiallogeneic F1 recipients, in which donor alloreactive CD160 KO CD4 T cells and CD8 T cells clonally expanded less vigorously than in WT T cell counterparts. This differential proliferative response rate at the early phase of T cell expansion influenced the course of CD8 T cell differentiation and the composition of the effector T cell pool that led to a significant decreased of the memory precursor effector cells (MPECs) / short-lived effector cells (SLECs) ratio in CD160 KO CD8 T cells compared to WT CD8 T cells. Despite these differences in T cell proliferation and differentiation, allogeneic MHC class I mismatched (bm1) skin allograft survival in CD160 KO recipients was comparable to that of WT recipients. However, the administration of CTLA-4.Ig showed an enhanced survival trend of bm1 skin allografts in CD160 KO with respect to WT recipients. Finally, CD160 deficient NK cells were as proficient as CD160 WT NK cells in rejecting allogeneic cellular allografts or MHC class I deficient tumor cells. CD160 may represent a CD28 alternative costimulatory molecule for the modulation of allogeneic CD8 T cell responses either in combination with costimulation blockade or by direct targeting of alloreactive CD8 T cells that upregulate CD160 expression in response to alloantigen stimulation.
Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.

The thymic function to produce self-protective and self-tolerant T cells is chiefly mediated by cortical thymic epithelial cells (cTECs) and medullary TECs (mTECs). Recent studies including single-cell transcriptomic analyses have highlighted a rich diversity in functional mTEC subpopulations. Because of their limited cellularity, however, the biochemical characterization of TECs, including the proteomic profiling of cTECs and mTECs, has remained unestablished. Utilizing genetically modified mice that carry enlarged but functional thymuses, here we show a combination of proteomic and transcriptomic profiles for cTECs and mTECs, which identified signature molecules that characterize a developmental and functional contrast between cTECs and mTECs. Our results reveal a highly specific impact of the thymoproteasome on proteasome subunit composition in cTECs and provide an integrated trans-omics platform for further exploration of thymus biology.
Published by Elsevier Inc.

A strong humoral response to infection requires the collaboration of several hematopoietic cell types that communicate via antigen presentation, surface coreceptors and their ligands, and secreted factors. The proinflammatory cytokine IL-6 has been shown to promote the differentiation of activated CD4(+) T cells into T follicular helper cells (T(FH) cells) during an immune response. T(FH) cells collaborate with B cells in the formation of germinal centers (GCs) during T cell-dependent antibody responses, in part through secretion of critical cytokines such as IL-21. In this study, we demonstrate that loss of either IL-6 or IL-21 has marginal effects on the generation of T(FH) cells and on the formation of GCs during the response to acute viral infection. However, mice lacking both IL-6 and IL-21 were unable to generate a robust T(FH) cell-dependent immune response. We found that IL-6 production in follicular B cells in the draining lymph node was an important early event during the antiviral response and that B cell-derived IL-6 was necessary and sufficient to induce IL-21 from CD4(+) T cells in vitro and to support T(FH) cell development in vivo. Finally, the transcriptional activator Oct2 and its cofactor OBF-1 were identified as regulators of Il6 expression in B cells.

IL-10 is a pleiotropic cytokine and potent negative regulator of both innate and adaptive immune responses. Consequently, IL-10-deficient (IL-10(-/-)) mice have enhanced contact hypersensitivity (CHS) to topical hapten.
Although the importance of IL-10 production by (regulatory) T cells and Langerhans cells in regulating CHS has been established by cell type-specific il-10 gene targeting, it remains elusive to what extent IL-10 controls dendritic cell (DC) function in vivo.
To this aim, we generated mice with a DC-specific deletion of the IL-10 receptor (IL-10R).
Despite the ability of IL-10 to inhibit DC maturation in vitro, DCs of resting DC-IL10R(-/-) mice retained their immature phenotype in vivo. In contrast, IL-10R(-/-) DCs produced increased levels of proinflammatory cytokines and IL-10 after in vitro stimulation. Induction of CHS was indistinguishable from that seen in control mice at 24 hours after hapten challenge but resulted in increased ear swelling at 48 hours and delayed resolution of the inflammatory reaction. Adoptive T-cell transfer experiments revealed that only T-cell reactivation and not sensitization by IL-10R(-/-) DCs leads to enhanced CHS. Accordingly, the expression of proinflammatory cytokines and IL-10 was augmented in the skin of DC-IL10R(-/-) mice after hapten challenge.
Our data demonstrate that IL-10 signaling in DCs is dispensable during naive T-cell priming but is critical to prevent an exaggerated effector T-cell response in the skin.
Copyright © 2011 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

Intestinal intraepithelial lymphocytes carrying the γδ TCR (γδ iIEL) are involved in the maintenance of epithelial integrity. γδ iIEL have an activated phenotype, characterized by CD69 expression and increased cell size compared with systemic T lymphocytes. As an additional activation marker, the majority of γδ iIEL express the CD8αα homodimer. However, our knowledge about cognate ligands for most γδ TCR remains fragmentary and recent advances show that γδ T cells including iIEL may be directly activated by cytokines or through NK-receptors, TLR and other pattern recognition receptors. We therefore asked whether the TCR of γδ iIEL was functional beyond its role during thymic selection. Using TcrdH2BeGFP (Tcrd, T-cell receptor δ locus; H2B, histone 2B) reporter mice to identify γδ T cells, we measured their intracellular free calcium concentration in response to TCR-crosslinking. In contrast to systemic γδ T cells, CD8αα(+) γδ iIEL showed high basal calcium levels and were refractory to TCR-dependent calcium-flux induction; however, they readily produced CC chemokine ligand 4 (CCL4) and IFN-γ upon TCR triggering in vitro. Notably, in vivo blocking of the γδ TCR with specific mAb led to a decrease of basal calcium levels in CD8αα(+) γδ iIEL. This suggests that the γδ TCR of CD8αα(+) γδ iIEL is constantly being triggered and therefore functional in vivo.
Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.