Interaction of human dendritic cell receptor DEC205/CD205 with keratins

DEC205 (CD205) is one of the major endocytic receptors on dendritic cells and has been widely used as a receptor target in immune therapies. It has been shown that DEC205 can recognize dead cells through keratins in a pH-dependent manner. However, the mechanism underlying the interaction between DEC205 and keratins remains unclear. Here we determine the crystal structures of an N-terminal fragment of human DEC205 (CysR∼CTLD3). The structural data show that DEC205 shares similar overall features with the other mannose receptor family members such as the mannose receptor and Endo180, but the individual domains of DEC205 in the crystal structure exhibit distinct structural features that may lead to specific ligand binding properties of the molecule. Among them, CTLD3 of DEC205 adopts a unique fold of CTLD, which may correlate with the binding of keratins. Furthermore, we examine the interaction of DEC205 with keratins by mutagenesis and biochemical assays based on the structural information and identify an XGGGX motif on keratins that can be recognized by DEC205, thereby providing insights into the interaction between DEC205 and keratins. Overall, these findings not only improve the understanding of the diverse ligand specificities of the mannose receptor family members at the molecular level but may also give clues for the interactions of keratins with their binding partners in the corresponding pathways.

Transcriptional profiling of macrophages in situ in metastatic melanoma reveals localization-dependent phenotypes and function

Modulation of immune function at the tumor site could improve patient outcomes. Here, we analyze patient samples of metastatic melanoma, a tumor responsive to T cell-based therapies, and find that tumor-infiltrating T cells are primarily juxtaposed to CD14+ monocytes/macrophages rather than melanoma cells. Using immunofluorescence-guided laser capture microdissection, we analyze transcriptomes of CD3+ T cells, CD14 + monocytes/macrophages, and melanoma cells in non-dissociated tissue. Stromal CD14+ cells display a specific transcriptional signature distinct from CD14+ cells within tumor nests. This signature contains LY75, a gene linked with antigen capture and regulation of tolerance and immunity in dendritic cells (DCs). When applied to TCGA cohorts, this gene set can distinguish patients with significantly prolonged survival in metastatic cutaneous melanoma and other cancers. Thus, the stromal CD14+ cell signature represents a candidate biomarker and suggests that reprogramming of stromal macrophages to acquire DC function may offer a therapeutic opportunity for metastatic cancers.

Insufficiency of CD205-positive cortical thymic epithelial cells in immature Japanese Black cattle with severe thymic abnormalities and poor prognosis

To investigate the involvement of thymic function in the development of diseases with poor prognosis in calves, this study conducted a survey for the assessment of thymus cell composition in immature Japanese Black cattle with poor prognosis. Histopathological evaluation of 47 cattle showed signs of acute thymic involution in most cases. Less than half of the cases had a cortex predominant over the medulla in the thymic parenchyma, and a quarter of the cases indicated severe histological condition with an unclear boundary between the cortex and medulla. Correlation analysis revealed a close relationship between the corresponding stages of acute involution, cortical occupancy, and the expression of CD4, CD8B, and CD205. When cases were grouped by cortical occupancy, the expression of CD4 and CD8B expression was lower in the severe group with less than 25 % cortical occupancy, and the expression of CD205 was lower in the group with an unclear cortical-medullary boundary. Meanwhile, there was no difference in the expressions of IL7, CD80, FEZF2, and FOXN1 according to cortical occupancy. Immunohistochemistry has shown that cytokeratin-positive thymic epithelial cells are more densely populated in the severe thymus. UEA-I-binding medullary thymic epithelial cells were also present, but CD205-positive cortical thymic epithelial cells were rare in severe thymus. Moreover, there were significantly fewer Ki-67-positive cells in cattle with severe thymus. Therefore, these results indicate that thymic histological abnormalities frequently occur in immature cattle with a poor prognosis, and the presence of CD205-positive cortical thymic epithelial cells is associated with the severity of the abnormalities.

CD205+ polymorphonuclear myeloid-derived suppressor cells suppress antitumor immunity by overexpressing GLUT3

Myeloid‐derived suppressor cells (MDSCs) are responsible for antitumor immunodeficiency in tumor‐bearing hosts. Primarily, MDSCs are classified into 2 groups: monocytic (M)‐MDSCs and polymorphonuclear (PMN)‐MDSCs. In most cancers, PMN‐MDSCs (CD11b⁺Ly6C^lowLy6G⁺ cells) represent the most abundant MDSC subpopulation. However, the functional and phenotypic heterogeneities of PMN‐MDSC remain elusive, which delays clinical therapeutic targeting decisions. In the 4T1 murine tumor model, CD11b⁺Ly6G^low PMN‐MDSCs were sensitive to surgical and pharmacological interventions. By comprehensively analyzing 64 myeloid cell‐related surface molecule expression profiles, cell density, nuclear morphology, and immunosuppressive activity, the PMN‐MDSC population was further classified as CD11b⁺Ly6G^lowCD205⁺ and CD11b⁺Ly6G^highTLR2⁺ subpopulations. The dichotomy of PMN‐MDSCs based on CD205 and TLR2 is observed in 4T07 murine tumor models (but not in EMT6). Furthermore, CD11b⁺Ly6G^lowCD205⁺ cells massively accumulated at the spleen and liver of tumor‐bearing mice, and their abundance correlated with in situ tumor burdens (with or without intervention). Moreover, we demonstrated that CD11b⁺Ly6G^lowCD205⁺ cells were sensitive to glucose deficiency and 2‐deoxy‐d‐glucose (2DG) treatment. Glucose transporter 3 (GLUT3) knockdown by siRNA significantly triggered apoptosis and reduced glucose uptake in CD11b⁺Ly6G^lowCD205⁺ cells, demonstrating the dependence of CD205⁺ PMN‐MDSCs survival on both glucose uptake and GLUT3 overexpression. As GLUT3 has been recognized as a target for the rescue of host antitumor immunity, our results further directed the PMN‐MDSC subsets into the CD205⁺GLUT3⁺ subpopulation as future targeting therapy.

Distinct Signatures in the Receptor Repertoire Discriminate CD56bright and CD56dim Natural Killer Cells

NK cells are phenotypically and functionally diverse lymphocytes due to variegated expression of a large array of receptors. NK-cell activity is tightly regulated through integration of receptor-derived inhibitory and activating signals. Thus, the receptor profile of each NK cell ultimately determines its ability to sense aberrant cells and subsequently mediate anti-viral or anti-tumor responses. However, an in-depth understanding of how different receptor repertoires enable distinct immune functions of NK cells is lacking. Therefore, we investigated the phenotypic diversity of primary human NK cells by performing extensive phenotypic characterization of 338 surface molecules using flow cytometry (n = 18). Our results showed that NK cells express at least 146 receptors on their surface. Of those, 136 (>90%) exhibited considerable inter-donor variability. Moreover, comparative analysis of CD56bright and CD56dim NK cells identified 70 molecules with differential expression between the two major NK-cell subsets and allowed discrimination of these subsets via unsupervised hierarchical clustering. These receptors were associated with a broad range of NK-cell functions and multiple molecules were not previously associated with predominant expression on either subset (e.g. CD82 and CD147). Altogether, our study contributes to an improved understanding of the phenotypic diversity of NK cells and its potential functional implications on a cellular and population level. While the identified distinct signatures in the receptor repertoires provide a molecular basis for the differential immune functions exerted by CD56bright and CD56dim NK cells, the observed inter-individual differences in the receptor repertoire of NK cells may contribute to a diverging ability to control certain diseases.

Systematic Multiomic Analysis of Ly75 Gene Expression and Its Prognostic Value Through the Infiltration of Natural Killer (NK) Cells in Skin Cutaneous Melanoma

Ly75 (also known as DEC-205 or CD205) is expressed in immune cells and cancers and involved in tumor immunity. However, clinical relevance of Ly75 expression in skin cutaneous melanoma (SKCM) have not been comprehensively studied. This study analyzed the correlation between Ly75 mRNA expression and patient survival using systematic multiomic analysis tools. Ly75 mRNA expression level was significantly lower in SKCM tissues than in normal tissues. Survival analysis showed that Ly75 expression significantly correlated with good patient survival. To determine possible mechanisms, the association between Ly75 expression and immune cell infiltration was analyzed. Ly75 expression was positively correlated with various infiltrated immune cells, particularly with natural killer (NK) cell infiltration and activation in SKCM. Moreover, analysis of Ly75-co-altered gene expression revealed that Ptprc (CD45) was most significantly correlated with Ly75. Gene ontology analysis of Ly75-co-altered genes indicated the relation to lymphocyte activation, including NK cell activation. Overall, our study provides the first clinical evidence that Ly75 expression is significantly associated with melanoma patient survival and NK cell infiltration, suggesting that Ly75 could be a useful prognostic factor.

CD205-positive, Sepharose-induced peritoneal exudate cells: a new resource for DC research in the chicken

Dendritic cells (DC) are important antigen-presenting cells and are among the least characterized immune cells in the chicken. In order to obtain chicken DC, current protocols require isolation of bone marrow myeloid progenitor cells and induction of DC differentiation with supplemental cytokines or negative selection of splenic cell preparations. Chicken peritoneal exudate cells (PEC) have traditionally been a source of various immune cells for ex vivo studies, primarily to investigate heterophils and macrophages. In this study, we observe the presence of CD205⁺ PEC populations, a marker of DC, as an additional resource to isolate and study chicken primary DCs. A panel of monoclonal antibodies was developed against the chicken CD205 DC marker and used to isolate CD205⁺ DC from the PEC population using magnetic bead cell sorting. This study reports the development of new anti-CD205 monoclonal antibodies as a reagent for chicken DC research, as well as PEC as a potential source of CD205⁺ DC for ex vivo studies in the chicken.

An immunohistochemical panel consisting of EZH2, C-KIT, and CD205 is useful for distinguishing thymic squamous cell carcinoma from type B3 thymoma

Type B3 thymoma and thymic squamous cell carcinoma (SqCC) often cause a diagnostic problem due to their histological similarities. The aim of this study is to identify EZH2 as a novel and powerful biomarker that can effectively distinguish thymic SqCC from type B3 thymoma, and find optimal combinations among 11 markers. A total of 53 patients, comprising 26 with type B3 thymoma and 27 with thymic SqCC, were allocated to the discovery or validation cohorts, and immunohistochemical staining was performed and analyzed. The expression level of each marker was scored, and receiver-operator characteristic curve analysis was performed to evaluate their diagnostic accuracies. This analysis identified EZH2, C-KIT, and CD205 as useful markers for distinguishing thymic SqCC, and a combined panel approach using them further improved diagnostic accuracy in both the discovery and validation cohorts. In the combined cohorts analysis, EZH2 was the single best marker with 88.9% sensitivity and 100% specificity [area under the curve (AUC) = 0.967]. The sensitivity and specificity were 85.2% and 100% (AUC = 0.962) for C-KIT, and 100% and 73.1% (AUC = 0.844) for CD205. The combined panel had the highest sensitivity and specificity at 96.3% and 100%, which was significantly or marginally higher than those of EZH2, C-KIT, and CD205 alone (P = 0.071, 0.034, and 0.005, respectively). The present findings indicate that EZH2 is useful as a novel diagnostic marker for distinguishing thymic SqCC and that the panel approach can be used as an effective differential diagnostic tool in daily practice.