Cord Blood-Derived Multipotent Stem Cells Ameliorate in Vitro/in Vivo Alloreactive Responses, and This Effect Is Associated with Exosomal Microvesicles in Vitro.

Human cord blood derived-multipotent stem cells (CB-SCs) have been found to have immunomodulatory capabilities that can result in inhibition of immune activation. Clinically, when used to interact with apheresed peripheral blood mononuclear cells (PBMCs) before reinfusion, they can counteract inflammation and restore immune balance in patients with autoimmune diseases, including alopecia areata and type 1 diabetes. The present study aimed to explore the potential application of CB-SCs to control donor alloreactive responses involved in allogeneic hematopoietic cell transplantation, which often results in acute graft-versus-host disease (GVHD). Phenotypically, we demonstrated that CB-SCs express CD45, CD11b, and CD9 markers on the cell surface; express Oct3/4, a transcription factor for embryonic stem cells; are negative for CD3, CD14, and CD34 expression; and have low expression of HLA-DR. In an allogeneic mixed lymphocyte culture (MLC) using human CD4 T cell enriched PBMCs and allogeneic myeloid derived dendritic cells, direct coculture with CB-SCs decreased CD4 T cell proliferation and activation, as evidenced by a marked decrease in the expression of the late activation markers CD25 and HLA-DR and a reduction of the PKH26 cell proliferation membrane lipophilic marker. Cytokine profiling of MLC supernatants revealed decreased concentrations of inflammatory proteins, including IFN-γ, IL-17, IL-13, IL-2, IL-6, and MIP1-α, along with marked increases in IL-1RA, IP-10, and MCP-1 concentrations in the presence of CB-SCs. Furthermore, transwell MLC experiments revealed that a soluble component was partially responsible for the immunomodulatory effects of CB-SCs. In this regard, exosomal microvesicles (EVs) positive for CD9, CD63, and CD81 were found in CB-SC-derived, ultrafiltered, and ultracentrifuged culture supernatants. CB-SC-EVs inhibited T cell proliferation in allogeneic MLC, suggesting a potential mode of action in allogeneic responses. Finally, CB-SCs were evaluated for their cellular therapy potential in vivo and found to ameliorate the development of GVHD responses in a xenogeneic human PBMC-induced NSG mouse model. Taken together, our results indicate that CB-SCs can directly and indirectly attenuate alloreactive CD4 T cell activation and proliferation in vitro with a potentially related EV mode of action and may have potential as a cellular therapy to control donor T cell-mediated GVHD responses in vivo.

The circuitry of the tumor microenvironment in adult and pediatric Hodgkin lymphoma: cellular composition, cytokine profile, EBV, and exosomes.

BACKGROUND: Classical Hodgkin lymphoma (cHL) is a unique lymphoid malignancy with a tumor microenvironment (TME) consisting of a small number of neoplastic-Hodgkin and Reed-Sternberg (H-RS) cells (<1%), surrounded by a large number of nonneoplastic infiltrating immune cells (>90%). The TME of cHL critically depends on immune cells to support tumor growth as H-RS cells cannot survive and proliferate in isolation. RECENT FINDINGS: Programmed cell death protein 1 (PD-1) ligand expressed on H-RS cells inhibits the clearance of tumor by causing T-cell exhaustion. Nivolumab and pembrolizumab, PD-1 inhibitors, have been proven to be effective in treating adult and pediatric patients with R/R cHL. Tumor-associated macrophages (TAMs) are a central component of TME and are known to cause poor prognosis in adult HL. However, the prognostic impact of CD68+ TAMs in pediatric HL remains ambiguous. EBV modulates the tumor milieu of HL and plays a strategic role in immune escape by enrichment of the TME with Treg cells and associated immunosuppressive cytokines in adult HL. In contrast, EBV+ pediatric patients have increased infiltration of CD8+ T-cells and show a better therapeutic response suggesting viral-related TME is distinct in childhood HL. The role of CASP3 in apoptosis of H-RS cells and its correlation with response prediction in adult and pediatric HL suggest it may serve as a potential biomarker. In cHL, CD30, EBV, and NF-κB signaling employ exosomes for cell-cell communication that triggers the migration capacity of fibroblasts, stimulate to produce proinflammatory cytokines, and help to create a tumor-supportive microenvironment. CONCLUSION: The cHL microenvironment is distinct in adult and pediatric HL. Future studies are required to understand the role of interplay between H-RS cells and EBV-associated microenvironment and their clinical outcome. They may present novel therapeutic targets for the development of antilymphoma therapy.

Anti-HIV activity of human defensin 5 in primary CD4+ T cells under serum-deprived conditions is a consequence of defensin-mediated cytotoxicity.

BACKGROUND: We have previously shown that human defensin 5 (HD5) promotes HIV infectivity in both primary CD4+ T cells and HeLa cells expressing CD4 and CCR5. HD5 is induced in response to sexually transmitted infections (STIs) such as Chlamydia trachomatis and Neisseria gonorrhoeae, suggesting it plays a role in STI-mediated enhancement of HIV transmission. In contrast to our findings, a recent study reports that HD5 has an anti-HIV effect in primary CD4+ T cells under serum-deprived conditions. To resolve these apparently contradictory observations, we investigated experimental parameters that might contribute to contrasting effects of HD5. RESULTS: Serum-deprived culture conditions were associated with anti-HIV activity. In contrast to the dependence of the HIV enhancing effect on HD5 structure, the anti-HIV activity in serum-deprived primary CD4+ T cells was independent of HD5 structure as the linear peptide [Abu] HD5 exhibited similar anti-HIV activity. Under serum deprived conditions, HD5 blocked CD4-receptor-independent HIV-1vsv infection before or after viral entry. We found that HD5 and its linear form induced significant cell death in primary CD4+ T cells under serum-deprived culture conditions. HD5-mediated apoptosis was observed as early as 2 h after addition of defensins to serum-deprived primary CD4+ T cells. In contrast to primary CD4+ T cells, HD5 did not induce cytotoxicity and promote HIV infectivity of HeLa-CD4-CCR5 cells under serum-deprived conditions. CONCLUSIONS: These results indicate that under serum-deprived culture conditions HD5 is toxic for primary CD4+ T cells, warranting caution in data interpretation.