PD-1 antibody and ruxolitinib enhances graft-versus-lymphoma effect without increasing acute graft-versus-host disease in mice

Hematopoietic Stem Cells and Their Niche in Bone Marrow

Extensive research has explored the functional correlation between stem cells and progenitor cells, particularly in blood. Hematopoietic stem cells (HSCs) can self-renew and regenerate tissues within the bone marrow, while stromal cells regulate tissue function. Recent studies have validated the role of mammalian stem cells within specific environments, providing initial empirical proof of this functional phenomenon. The interaction between bone and blood has always been vital to the function of the human body. It was initially proposed that during evolution, mammalian stem cells formed a complex relationship with the surrounding microenvironment, known as the niche. Researchers are currently debating the significance of molecular-level data to identify individual stromal cell types due to incomplete stromal cell mapping. Obtaining these data can help determine the specific activities of HSCs in bone marrow. This review summarizes key topics from previous studies on HSCs and their environment, discussing current and developing concepts related to HSCs and their niche in the bone marrow.

JAK inhibition enhances checkpoint blockade immunotherapy in patients with Hodgkin lymphoma

Unleashing antitumor T cell activity by checkpoint inhibitor immunotherapy is effective in cancer patients, but clinical responses are limited. Cytokine signaling through the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway correlates with checkpoint immunotherapy resistance. We report a phase I clinical trial of the JAK inhibitor ruxolitinib with anti-PD-1 antibody nivolumab in Hodgkin lymphoma patients relapsed or refractory following checkpoint inhibitor immunotherapy. The combination yielded a best overall response rate of 53% (10/19). Ruxolitinib significantly reduced neutrophil-to-lymphocyte ratios and percentages of myeloid suppressor cells but increased numbers of cytokine-producing T cells. Ruxolitinib rescued the function of exhausted T cells and enhanced the efficacy of immune checkpoint blockade in preclinical solid tumor and lymphoma models. This synergy was characterized by a switch from suppressive to immunostimulatory myeloid cells, which enhanced T cell division.

Thrombin receptor activating peptide-6 decreases acute graft-versus-host disease through activating GPR15

G-protein coupled receptor 15 (GPR15) is expressed on T-cells. We previously reported knockout of GPR15 increased acute graft-versus-host disease (GvHD) in mice. In this study, we identified thrombin receptor activating peptide-6 (TRAP-6, peptide sequence: SFLLRN) as an activator of GPR15. GRP15 and β-arrestin2 were needed for TRAP-6-mediated inhibition of mixed lymphocyte reactions. TRAP-6 decreased acute GvHD in allotransplant models in mice, an effect dependent on GPR15-expression in donor T-cells. RNA-seq and protein analyses indicated TRAP-6 increased binding of β-arrestin2/TAB1 and inhibited phosphorylation of TAK1 and NF-κB-P65. GPR15 is expressed differently on CD4+ T-cells and CD8+ T-cells. TRAP-6 inhibited phosphorylation of NF-κB-P65 in CD4+ T-cells but increased granzyme B expression in CD8+ T-cells. TRAP-6 decreased acute GvHD without inhibiting graft-versus-tumor (GvT) efficacy against A20 lymphoma cells. SALLRN, a mutant of TRAP-6, preserved the anti-acute GvHD effect but avoided the adverse effects of TRAP-6. TRAP-6 and SALLRN also decreased allogeneic and xenogeneic reactions induced by human blood mononuclear cells. In conclusion, TRAP-6 activated GPR15 on T-cells and decreased acute GvHD in mice without impairing GvT efficacy.

The altering cellular components and function in tumor microenvironment during remissive and relapsed stages of anti-CD19 CAR T-cell treated lymphoma mice

Anti-CD19 chimeric antigen receptor (CAR) T cells represent a highly promising strategy for B-cell malignancies. Despite the inspiring initial achievement, remission in a notable fraction of subjects is short-lived, and relapse remains a major challenge. Tumor microenvironment (TME) was proved to be aroused by CAR T cells; however, little is known about the dynamic characteristics of cellular components in TME especially during the different phases of disease after anti-CD19 CAR T-cell treatment. We took advantage of an immunocompetent model receiving syngeneic A20 lymphoma cells to dissect the changes in TME with or without CAR T-cell injection. We found that anti-CD19 CAR T-cell treatment attenuated the symptoms of lymphoma and significantly prolonged mice survival through eradicating systemic CD19⁺ cells. Increased myeloid subsets, including CD11c⁺ DCs and F4/80⁺ macrophages with higher MHC II and CD80 expression in bone marrow, spleen, and liver, were detected when mice reached remission after anti-CD19 CAR T treatment. Compared to mice without anti-CD19 CAR T administration, intrinsic T cells were triggered to produce more IFN-γ and TNF-α. However, some lymphoma mice relapsed by day 42 after therapy, which coincided with CAR T-cell recession, decreased myeloid cell activation and increased Treg cells. Elevated intrinsic T cells with high PD-1 and TIGIT exhaust signatures and attenuated cytotoxicity in TME were associated with the late-stage relapse of CAR T-cell treatment. In summary, the cellular compositions of TME as allies of CAR T cells may contribute to the anti-tumor efficacy at the initial stage, whereas anti-CD19 CAR T-cell disappearance and host response immunosuppression may work together to cause lymphoma relapse after an initial, near-complete elimination phase.

Blockade of PD-1/PD-L1 increases effector T cells and aggravates murine chronic graft-versus-host disease

T-cells mediated immunopathology is crucial for pathogenesis of chronic graft-versus-host disease (cGVHD), a common complication following allogeneic hematopoietic cell transplantation. Programmed death-1 (PD-1) regulates long-term survival and functional exhaustion of T-cell which might play a role in regulating cGVHD. We examined PD-1 expression on T cells of cGVHD mice and tested the impact of a PD-1 antibody on severity of cGVHD in murine allotransplant models. We also used a murine graft-versus-tumor (GVT) model to explore how tumor cell-derived PD-L1 affect the GVT effect and occurrence of cGVHD. PD-1 fluorescence intensity on CD4⁺ T-cells increased in mice developing cGVHD. PD-1^High T cells expressed higher levels of IFNγ and IL-17, comparing with PD-1^Low T cells. Giving the PD-1 antibody increased proportions of Th1, Th17 and Tc1 cells, but decreased proportion of Treg cells in allotransplant mice. The PD-1 antibody decreased survival of recipients and induced severe lung cGVHD. In the GVT model, knockdown of PD-L1 in A20 tumor cells enhanced GVT effect but increased cGVHD. In vitro study showed knockdown of PD-L1 in tumor cells increased cytotoxicity of T cells and reduced apoptosis of T cells. Knockdown of PD-L1 in tumor cells increased protein levels of phosphorylated AKT, Bcl-2 and Mcl-1, but decreased protein levels of Bak and Bax in co-cultured allogeneic T cells. In conclusion, expression of PD-1 on T cells increased in mice undergoing cGVHD. Intervention of the PD-1/PD-L1 pathway showed a significant impact on occurrence of cGVHD and GVT effect.

Identification of two immune-related risk score signatures through integrated analysis of multi-omics data in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. Immunotherapy has become a major treatment for advanced HCC, but the therapeutic effects remain unsatisfactory. In this study, we constructed an immune cell risk score (ICS) and an immune cell-related gene risk score (ICRGS) for the prognosis prediction of HCC through integrated analysis of bulk and single-cell RNA (scRNA) sequencing data. These two risk score signatures both showed good predictive values in the training and validation cohorts. The potential interactions among these prognostic immune cell types were elucidated by cell-cell communication analysis. The results of enrichment analysis and gene set enrichment analysis (GSEA) of the prognostic genes showed that metabolic-related processes were involved in the immune response of HCC. Furthermore, the results of correlation analyses further confirmed the hub genes that were strongly correlated with immune cells. Finally, potential therapeutic drugs targeting these hub genes were screened by CellMiner based on NCI-60 cell line set. Taken together, two useful models for the prognosis prediction of HCC patients were constructed in this study. The functional differences between the two groups of HCC patients separated by ICS or ICRGS provide fundamental knowledge for finding synergistic therapeutic targets for HCC immunotherapy.

Inhibition of interleukin-1 receptor-associated kinase 1 decreases murine acute GVHD while preserving graft-versus-lymphoma effect

BACKGROUND

Activation of antigen presenting cells (APC) is crucial in initiating inflammation and alloreaction during acute graft-versus-host disease (aGVHD), a common life-threatening complication of allogeneic hematopoietic cell transplantation. Interleukin-1 receptor-associated kinase 1 (IRAK1) regulates activation of APC in inflammatory settings. Inhibition of IRAK1 might decrease APC activation and aGVHD.

OBJECTIVE

To explore the impact of IRAK1 inhibition on APC activation and aGVHD in mice.

STUDY DESIGN

We administrated a selective IRAK1 inhibitor Jh-X-119-01 to recipient mice receiving allotransplants or co-challenged by A20 lymphoma cells. We assessed aGVHD and graft-versus-lymphoma (GVL) effect. Activations of T-cell and APC were also analyzed.

RESULTS

Jh-X-119-01 increased survival and decreased aGVHD of recipients. Jh-X-119-01 decreased proportions of Th1 cells and Tc1 cells in the aGVHD model and in the in vitro mixed lymphocyte reaction (MLR). The IRAK1 inhibitor reduced productions of TNFα and IFNγ in macrophages of recipient mice. In the in vitro cultured bone marrow dendric cells (BMDCs), Jh-X-119-01 decreased productions of inflammatory cytokines, reduced expressions of CD80 and CD86, and decreased protein levels of anti-apoptotic Bcl2 and phosphorylated NF-κB p65. RNA-seq analysis showed Jh-X-119-01 had an impact on several pathophysiological processes of BMDCs such as reduction of GVHD-relation genes and regulation of helper T cell differentiation. Importantly, IRAK1 inhibition did not impair cytotoxic function of T-cell or the allotransplant-related GVL effect against A20 lymphoma cells. In addition, the IRAK1 inhibitor did not retard recovery of hematopoietic cells in blood or bone marrow.

CONCLUSION

We show selective IRAK1 inhibition ameliorates murine aGVHD but preserves GVL effect. Our findings may have implication for using an IRAK1 inhibitor in allotransplant.

Iguratimod decreases bleomycin-induced pulmonary fibrosis in association with inhibition of TNF-α in mice

Severe interstitial lung disease secondary to connective tissue diseases, characterized by pulmonary inflammation and fibrosis, often have very poor prognosis due to lack of effective treatments. Iguratimod (IGU) shows encouraging efficacy in treating connective tissue diseases, however, the underlying mechanism is still to be elucidated. In this study, we investigated the impact of IGU on bleomycin-induced interstitial lung disease and the related tumor necrosis factor-α (TNF-α) signaling pathway in mice and in the alveolar epithelial cell A549. We found IGU decreased pulmonary inflammation and fibrosis and expression of fibrosis-related genes such as Collagen I, α-smooth muscle actin (α-SMA) and matrix metalloproteinase-2 (MMP-2) induced by bleomycin. IGU inhibited epithelial-mesenchymal transition as evidenced by decreased E-cadherin expression but increased vimentin expression. IGU reduced TNF-α production in the pulmonary fibrosis murine model and in the in vitro cultured A549 cells. Furthermore, IGU ameliorated TNF-α-induced severe pulmonary fibrosis and inhibited TNF-α-induced activation of NF-κB. In addition, IGU decreased IL-6 production and phosphorylation of STAT3. In conclusion, the IGU-mediated anti-fibrogenesis effect was associated with the inhibition of TNF-α and NF-κB.