Host-derived CD8+ dendritic cells are required for induction of optimal graft-versus-tumor responses after experimental allogeneic bone marrow transplantation.

The graft-versus-tumor (GVT) effect after allogeneic hematopoietic cell transplantation (allo-HCT) represents an effective form of immunotherapy against many malignancies. Meaningful separation of the potentially curative GVT responses from graft-versus-host disease (GVHD), the most serious toxicity following T-cell replete allo-HCT, has been an elusive goal. GVHD is initiated by alloantigens, although both alloantigens and tumor-specific antigens (TSAs) initiate GVT responses.

Targeting of microRNA-142-3p in dendritic cells regulates endotoxin-induced mortality.

While miRNAs are increasingly linked to various immune responses, whether they can be targeted for regulating in vivo inflammatory processes such as endotoxin-induced Gram-negative sepsis is not known. Production of cytokines by the dendritic cells (DCs) plays a critical role in response to endotoxin, lipopolysaccharide (LPS). We profiled the miRNA and mRNA of CD11c⁺ DCs in an unbiased manner and found that at baseline, miR-142-3p was among the most highly expressed endogenous miRs while IL-6 was among the most highly expressed mRNA after LPS stimulation.

Ikaros-Notch axis in host hematopoietic cells regulates experimental graft-versus-host disease.

Host hematopoietically derived APCs play a vital role in the initiation of GVH responses. However, the APC autonomous molecular mechanisms that are critical for the induction of GVHD are not known. We report here that the Ikaros-Notch axis in host hematopoietically derived APCs regulates the severity of acute GVHD across multiple clinically relevant murine models of experimental bone marrow transplantation.

Interleukin-6 modulates graft-versus-host responses after experimental allogeneic bone marrow transplantation.

Purpose: The graft-versus-tumor (GVT) effect is a potent form of immunotherapy against many hematologic malignancies and some solid tumors. The beneficial GVT effect after allogeneic bone marrow transplantation (BMT) is tightly linked to its most significant complication, graft-versus-host disease (GVHD). The role of interleukin-6 (IL-6) after allogeneic BMT is not well understood.

Immunization with host-type CD8{alpha}+ dendritic cells reduces experimental acute GVHD in an IL-10-dependent manner.

Little is known about the role of active immunization in suppressing undesirable immune responses. Because CD8alpha(+) dendritic cells (DCs) suppress certain immune responses, we tested the hypothesis that immunization of donors with host-derived CD8alpha(+) DCs will reduce host-specific donor T-cell responses. BALB/c T cells from the animals that were immunized with B6 CD8alpha(+) DCs demonstrated, in vitro and in vivo, significantly reduced proliferation and secretion of inflammatory cytokines but showed enhanced secretion of interleukin-10 (IL-10).

Mesenchymal stem cells for treatment and prevention of graft-versus-host disease after allogeneic hematopoietic cell transplantation.

Allogeneic hematopoietic cell transplantation (allo-HCT) is an effective therapy for hematological malignancies and inherited diseases. However, acute graft-versus-host-disease (aGVHD) is a major life-threatening complication after allo-HCT and there are few therapeutic options for severe steroid-refractory aGVHD. Preliminary studies on co-transplantation of mesenchymal stem cells (MSCs) have shown an improvement in or resolution of severe aGVHD.

Cutting edge: Negative regulation of dendritic cells through acetylation of the nonhistone protein STAT-3.

Histone deacetylase (HDAC) inhibition modulates dendritic cell (DC) functions and regulates experimental graft-vs-host disease and other immune-mediated diseases. The mechanisms by which HDAC inhibition modulates immune responses remain largely unknown. STAT-3 is a transcription factor shown to negatively regulate DC functions.