Modelling Graft-Versus-Host Disease in Mice Using Human Peripheral Blood Mononuclear Cells

Interspecies transcriptome profiles of human T cell activation and liver inflammation in a xenogeneic graft-versus-host disease model

Background

Xenogeneic transplantation induces acute graft-versus-host disease (aGvHD) and subsequent vital organ damage. Herein, we aimed to examine hepatic damage associated with aGvHD using histopathology and gene expression profiles.

Methods

A xenografic GvHD model was established by engrafting human peripheral blood mononuclear cells (PBMCs) into immunodeficient NOD-scid IL2Rγnull (NSG) mice after busulfan conditioning. NSG mice were assigned to groups treated with saline (S group) or a combination of busulfan and PBMCs (BP group). Histological lesions and RNA sequencing analysis of gene profiles in the BP group (GvHD model) were compared with those in the P group.

Results

Predominant T cell subsets (95 %) in the blood of the BP group were identified as cytotoxic CD8+ T cells (56 %) and helper CD4+ T cells (31 %). Symptoms of aGvHD, including hepatocyte necrosis, bile duct hyperplasia, and human T cell infiltration, were observed. Gene expression analysis revealed upregulation of Th1 and Th2 cell differentiation (STAT4, IL4R, and NFACT1), T cell receptor signaling pathway (CD226 and GBP1), IL-1 pathway (CCL3, NAIP, and IRAK4), cell cycle (CDCA5, CDCA8, MCM5, KNL1, BUB1B, FBXO5, and CENPE) in human cells. In mouse cells, Il1a, Ifngr, Tnfrsf, and Il6ra genes (cytokines or their receptors) and Icam, Vcam, and Endra genes (adhesion molecules) were upregulated, whereas genes related to chromosome condensation (H2ac and H2bc) and fatty acid/steroid metabolism (Fasn, Rdh, and Scd) were downregulated. Interspecies gene network analysis revealed that activated human T cells are associated with liver damage through inflammatory and metabolic pathways, accompanied by increased mouse cell adhesion molecules and cytokines.

Conclusion

Our findings offer valuable insights into the pathophysiology and biomarkers of aGvHD and may contribute to the development of novel therapeutics.

Applications of Organoids in Advancing Drug Discovery and Development

Organoids are small, self-organizing three-dimensional cell cultures that are derived from stem cells or primary organs. These cultures replicate the complexity of an organ, which cannot be achieved by single-cell culture systems. Organoids can be used in testing of new drugs instead of animals. Development and validation of organoids is thus important to reduce the reliance on animals for drug testing. In this review, we have discussed the developmental and regulatory aspects of organoids and highlighted their importance in drug development. We have first summarized different types of culture-based organoid systems such as submerged Matrigel, micro-fluidic 3D cultures, inducible pluripotent stem cells, and air-liquid interface cultures. These systems help us understand the intricate interplay between cells and their surrounding milieu for identifying functions of target receptors, soluble factors, and spatial interactions. Further, we have discussed the advances in humanized severe-combined immunodeficiency mouse models and their applications in the pharmacology of immune-oncology. Since regulatory aspects are important in using organoids for drug development, we have summarized FDA and EMA regulations on organoid research to support pre-clinical studies. Finally, we have included some unique studies highlighting the use of organoids in studying infectious diseases, cancer, and fundamental biology. These studies also exemplify the latest technological advances in organoid development resulting in improved efficiency. Overall, this review comprehensively summarizes the applications of organoids in early drug development during discovery and pre-clinical studies.

Dual roles of CD11b+CD33+HLA-DR-/lowCD14- myeloid-derived suppressor cells with a granulocytic morphology following allogeneic hematopoietic stem cell transplantation: from inflammation promoters to immune suppressors within 90 days

Introduction

Granulocytic myeloid-derived suppressor cells (G-MDSCs) show fast recovery following allogeneic hematopoietic stem cell transplantation (allo-HSCT) constituting the major part of peripheral blood in the early phase. Although G-MDSCs mediate immune suppression through multiple mechanisms, they may also promote inflammation under specific conditions.

Methods

G-MDSCs were isolated from 82 patients following allo-HSCT within 90 days after allo-HSCT, and their interactions with autologous CD3+ T-cells were examined. T-cell proliferation was assessed by flow cytometry following CFSE staining, while differentiation and interferon-γ secretion were characterized using chemokine receptor profiling and ELISpot assays, respectively. NK cell cytotoxicity was evaluated through co-culture with K562 cells. An aGVHD xenogeneic model in humanized mice was employed to study the in vivo effects of human leukocytes. Furthermore, transcriptional alterations in G-MDSCs were analyzed via RNA sequencing to investigate functional transitions.

Results

G-MDSCs promoted inflammation in the early-stage, by facilitating cytokine secretion and proliferation of T cells, as well as their differentiation into pro-inflammatory T helper subsets. At day 28, patients with a higher number of G-MDSCs exhibited an increased risk of developing grades II-IV aGvHD. Besides, adoptive transfer of G-MDSCs from patients at day 28 into humanized mice exacerbated aGvHD. However, at day 90, G-MDSCs led to immunosuppression, characterized by upregulated expression of indoleamine 2,3-dioxygenase gene and interleukin-10 secretion, coupled with the inhibition of T cell proliferation. Furthermore, transcriptional analysis of G-MDSCs at day 28 and day 90 revealed that 1445 genes were differentially expressed. These genes were associated with various pathways, revealing the molecular signatures of early post-transplant differentiation in G-MDSCs. In addition, genes linked to the endoplasmic reticulum stress were upregulated in patients without aGvHD. The acquisition of immunosuppressive function by G-MDSCs may depend on the activation of CXCL2 and DERL1 genes.

Conclusion

Our findings revealed the alteration in the immune characteristics of G-MDSCs within the first 90 days post-allo-HSCT. Moreover, the quantity of G-MDSCs at day 28 may serve as a predictive indicator for the development of aGvHD.

A CD6-targeted antibody-drug conjugate as a potential therapy for T cell-mediated disorders

The selective targeting of pathogenic T cells is a holy grail in the development of new therapeutics for T cell-mediated disorders, including many autoimmune diseases and graft versus host disease. We describe the development of a CD6-targeted antibody-drug conjugate (CD6-ADC) by conjugating an inactive form of monomethyl auristatin E (MMAE), a potent mitotic toxin, onto a mAb against CD6, an established T cell surface marker. Even though CD6 is present on all T cells, only the activated (pathogenic) T cells vigorously divide and thus are susceptible to the antimitotic MMAE-mediated killing via the CD6-ADC. We found CD6-ADC selectively killed activated proliferating human T cells and antigen-specific mouse T cells in vitro. Furthermore, in vivo, whereas the CD6-ADC had no significant detrimental effect on normal T cells in naive CD6-humanized mice, the same dose of CD6-ADC, but not the controls, efficiently treated 2 preclinical models of autoimmune uveitis and a model of graft versus host disease. These results provide evidence suggesting that CD6-ADC could be further developed as a potential therapeutic agent for the selective elimination of pathogenic T cells and treatment of many T cell-mediated disorders.

Human A2-CAR T Cells Reject HLA-A2 + Human Islets Transplanted Into Mice Without Inducing Graft-versus-host Disease

BACKGROUND

Type 1 diabetes is an autoimmune disease characterized by T-cell-mediated destruction of pancreatic beta-cells. Islet transplantation is an effective therapy, but its success is limited by islet quality and availability along with the need for immunosuppression. New approaches include the use of stem cell-derived insulin-producing cells and immunomodulatory therapies, but a limitation is the paucity of reproducible animal models in which interactions between human immune cells and insulin-producing cells can be studied without the complication of xenogeneic graft-versus-host disease (xGVHD).

METHODS

We expressed an HLA-A2-specific chimeric antigen receptor (A2-CAR) in human CD4 + and CD8 + T cells and tested their ability to reject HLA-A2 + islets transplanted under the kidney capsule or anterior chamber of the eye of immunodeficient mice. T-cell engraftment, islet function, and xGVHD were assessed longitudinally.

RESULTS

The speed and consistency of A2-CAR T-cell-mediated islet rejection varied depending on the number of A2-CAR T cells and the absence/presence of coinjected peripheral blood mononuclear cells (PBMCs). When <3 million A2-CAR T cells were injected, coinjection of PBMCs accelerated islet rejection but also induced xGVHD. In the absence of PBMCs, injection of 3 million A2-CAR T cells caused synchronous rejection of A2 + human islets within 1 wk and without xGVHD for 12 wk.

CONCLUSIONS

Injection of A2-CAR T cells can be used to study rejection of human insulin-producing cells without the complication of xGVHD. The rapidity and synchrony of rejection will facilitate in vivo screening of new therapies designed to improve the success of islet-replacement therapies.