Expansion of natural killer cell receptor (CD94/NKG2A)-expressing cytolytic CD8 T cells and CD4+CD25+ regulatory T cells from the same cord blood unit

Single-Cell RNA Sequencing Reveals the Heterogeneity of Infiltrating Immune Cell Profiles in the Hepatic Cystic Echinococcosis Microenvironment

Human cystic echinococcosis, caused by the larval stage of Echinococcus granulosus sensu lato, has been reported a near-cosmopolitan zoonotic disease. Various infiltrating immune cells gather around the lesion and produce a lesion microenvironment; however, cellular composition and heterogeneity in hepatic cystic echinococcosis lesion microenvironments are incompletely understood. Here, 81,865 immune cells isolated from peripheral blood, perilesion liver tissue, and adjacent normal liver tissue from four cystic echinococcosis patients were profiled using single-cell RNA sequencing. We identified 23 discrete cell populations and found distinct differences in infiltrating immune cells between tissue environments. Despite the significant similarity between perilesion and adjacent normal liver tissue-resident immune cells, the cellular proportions of type 2 innate lymphoid cells (ILC2s) and plasmacytoid dendritic cells (pDCs) were higher in perilesion liver tissue. Interestingly, the immunosuppressive gene NFKBIA was upregulated in these cells. Seven subsets of CD4⁺ T cell populations were found, and there were more regulatory-CD4⁺ T cells (Treg-CD4⁺) and Th2-CD4⁺ T cells in perilesion tissue than in adjacent normal tissue. There was close contact between CD4⁺ T cells and ILC2s and pDCs, which caused upregulation of genes related to positive immune activity in adjacent normal liver tissue. However, expression of genes related to immunosuppression, especially the immune inhibitory checkpoint gene NKG2A/HLA-E, was obviously higher in perilesion tissue, suggesting that cellular interaction resulted in an inhibitory microenvironment in the cystic echinococcosis (CE) lesion. This work offers new insights into the transcriptional heterogeneity of infiltrating immune cells in hepatic cystic echinococcosis lesion microenvironments at a single-cell level and provides potential target signatures for diagnosis and immunotherapies.

Naïve T cells, unconventional NK and NKT cells, and highly responsive monocyte-derived macrophages characterize human cord blood

This study compares the human immune systems of neonates and adults. Flow cytometric analysis was used to study the cellular phenotypes of cord blood (CB) and adult peripheral blood (APB). Luminex analysis was used to determine the levels of cytokines in cell culture supernatants. Our findings indicate that T cells in CB were mainly naïve and thus less responsive to PMA/ionomycin with the synthesis of cytokines. The percentages of CD3(+)CD4(+)CD25(high) and of CD3(+)CD4(+)CD25(dim) cells expressing chemokine receptors were different between CB and APB. TLR1, TLR6 and TLR9 expressions on NK and NKT cells also differed between CB and APB. CB monocyte-derived macrophages responded better than APB macrophages to TLR ligands with increased secretion of inflammatory cytokines, especially IL-6. The high levels of the inflammatory cytokines in cell culture supernatants of CB were mainly due to higher numbers of responsive macrophages, since dendritic cell numbers were lower in CB than APB.

Expansion of CD4(+)CD25 (+) regulatory T cells from cord blood CD4(+) cells using the common γ-chain cytokines (IL-2 and IL-15) and rapamycin

Rapamycin has important roles in the modulation of regulatory T cells. We tried to expand CD4(+)CD25(+) regulatory T cells (Treg cells) from umbilical cord blood (CB) CD4-positive cells using interleukin (IL)-15 or IL-2 with transforming growth factor (TGF)-β and rapamycin. We were able to obtain more than 500-fold expansion of CD4(+)CD25(+) cells from CB CD4(+) cells using IL-15 and TGF-β with rapamycin. These expanded CD4(+)CD25(+) cells expressed forkhead box P3 (FoxP3) mRNA at a level about 100-fold higher and could suppress allogeneic mixed lymphocyte culture (MLC) by more than 50%. Early after rapamycin stimulation, CB CD4(+) cells showed increased expression of FoxP3 and a serine/threonine kinase Pim2 and sustained expression of negative phosphoinositide 3-kinase regulator phosphatase and tensin homolog deleted on chromosome 10 (PTEN). On the other hand, CD4(+)CD25(+) cells expanded with rapamycin for 8 days showed much higher levels of FoxP3 mRNA expression and decreased expression of PTEN. A comparison of IL-15 stimulation and IL-2 stimulation showed slightly higher efficiency of IL-15 for expansion of CD4(+)CD25(+) cells, and for FoxP3 expression, IL-15 also showed significantly higher efficacy for inhibition of MLC. The combination of the common γ-chain cytokine IL-15, TGF-β, and rapamycin may be a useful means for expanding Treg cells. Pim2 expression early after stimulation with rapamycin may be important for conferring rapamycin resistance for growth of Treg cells. IL-15 is not less useful than IL-2 for expansion of Treg cells.

Immune regulatory cells in umbilical cord blood and their potential roles in transplantation tolerance

Umbilical cord blood (UCB) is a source of primitive hematopoietic stem (HSC) and progenitor cells, that served as an alternative to bone marrow (BM) for effective transplantation therapy. Success of HSC transplantation (HSCT) is limited in part by graft-versus-host disease (GVHD), graft rejection and delayed immune reconstitution, which all relate to immunological complications. GVHD after UCB transplantation is lower compared to that of BM HSCT. This may relate to the tolerogenic nature of T cells, mononuclear cells (MNCs) and especially immune regulatory cells existing in UCB. UCB contains limiting numbers of HSC or CD34(+) cell dose for adult patients resulting in delayed engraftment after UCB transplantation (UCBT). This needs to be improved for optimal transplantation outcomes. Approaches have been undertaken to promote HSC engraftment, including co-infusion of multiple units of UCB cells. These new methods however added additional immunological complications. Herein, we describe current knowledge on features of UCB immune cells, including regulatory T cells (Tregs) and mesenchymal stem/stromal cells (MSCs) and their potential future usage to reduce GVHD.

Phenotypic differences between cord blood and adult peripheral blood

BACKGROUND AND OBJECTIVES

Neonates are more susceptible to infections than adults, due to a less mature immune system. The objective of this study was to compare the immunophenotypes of cord blood (CB) and adult peripheral blood (APB) and to establish whether or not there are immunophenotypical differences.

METHODS

CB and APB were collected into CPD anticoagulant. Whole blood was stained with fluorochrome conjugated antibodies, cells were fixed, red cells were lysed, and samples were run in a FACSCanto flow cytometer.

RESULTS

Plots of SSC vs. CD45 showed two lymphocyte-like populations in CB with the same low SSC characteristics while there was only one low SSC lymphoid population in APB. The CD45dim population included the majority of CD34+ cells, but it also included T, B, NKT, and NK cells. The percentages of CD3+, CD3+CD4+, CD3+CD8+, CD19+, CD3+CD56+, and CD3-CD56+ in the CD45high gate of CB were similar to the percentages obtained for APB. Meanwhile, in the CD45dim gate, the percentages were either lower (CD3+, CD3+CD4+, CD3+CD8+) or higher (CD19+, CD3+CD56+, CD3-CD56+) than in the CD45high gate.

CONCLUSIONS

CB presents two lymphoid populations defined by different levels of expression of the phosphatase CD45; the CD45dim subsets likely represent cells with elevated proliferative activity possibly due to the differential expression of CD45 but still not yet immunologically mature with regard to immunophenotype and function.