Decoding lymphomyeloid divergence and immune hyporesponsiveness in G-CSF-primed human bone marrow by single-cell RNA-seq

High-Lactate-Metabolizing Photosynthetic Bacteria Reprogram Tumor Immune Microenvironment

The elevated levels of lactate in tumor tissue play a pivotal role in fostering an immunosuppressive microenvironment. Therefore, efficiently reducing lactate levels to reprogram tumor immune microenvironment (TIM) is considered a crucial step for boosted immunotherapy. Here, a high-lactate-metabolizing photosynthetic bacteria (LAB-1) is selectively screened for TIM reprogramming, which then improves the efficacy of tumor immunotherapy. The culture medium for LAB-1 screening is initially developed through an orthogonal experiment, simulating the tumor microenvironment (TME) and utilizing lactate as the sole organic carbon source. As demonstrated in a murine 4T1 model, LAB-1 colonizes the TME selectively, resulting in a significant reduction in lactate levels and a subsequent increase in pH values within the tumor tissue. Furthermore, single-cell RNA sequencing analysis reveals that LAB-1 effectively reprograms the TIM, thereby enhancing the effectiveness of antitumor immune therapy. This approach of utilizing lactate-consuming bacteria represents a potent tool for augmenting tumor immunotherapy efficiency.

Myelopreservation with Trilaciclib in recurrent advanced ovarian cancer: a case report

Ovarian cancer is a prevalent malignant tumor of the female reproductive system, often remaining concealed until it reaches an advanced stage. The standard treatment protocol includes cytoreductive surgery for ovarian cancer plus postoperative consolidation chemotherapy and maintenance therapy, although it carries a high recurrence rate. During the treatment period, chemotherapy can lead to bone marrow suppression, a condition known as Chemotherapy-Induced Myelosuppression (CIM). This suppression may necessitate dose reduction or chemotherapy treatment cycle delay. In severe cases, CIM can result in infection, fever, and potential harm to the patient's life. Here, we report a case of a female patient with ovarian malignant tumor of biochemical recurrence who treated with chemotherapy combined with Trilaciclib, following previous perioperative chemotherapy with occurrence of severe CIM. It involves an intravenous injection of Trilaciclib before chemotherapy, which significantly abates the side effects of chemotherapy, reduces the occurrence of severe CIM, improves the patients' quality of life, and decreases the economic burden of hospitalization. We hope that this retrospective analysis of the case may serve as a reference in preventing and treating severe CIM during chemotherapy in some patients with malignant tumors, ultimately benefiting more patients with tumors.

Single-Cell RNA Sequencing in Organ and Cell Transplantation

Single-cell RNA sequencing is a high-throughput novel method that provides transcriptional profiling of individual cells within biological samples. This method typically uses microfluidics systems to uncover the complex intercellular communication networks and biological pathways buried within highly heterogeneous cell populations in tissues. One important application of this technology sits in the fields of organ and stem cell transplantation, where complications such as graft rejection and other post-transplantation life-threatening issues may occur. In this review, we first focus on research in which single-cell RNA sequencing is used to study the transcriptional profile of transplanted tissues. This technology enables the analysis of the donor and recipient cells and identifies cell types and states associated with transplant complications and pathologies. We also review the use of single-cell RNA sequencing in stem cell implantation. This method enables studying the heterogeneity of normal and pathological stem cells and the heterogeneity in cell populations. With their remarkably rapid pace, the single-cell RNA sequencing methodologies will potentially result in breakthroughs in clinical transplantation in the coming years.

Circulating IRF8-expressing CD123+CD127+ lymphoid progenitors: key players in human hematopoiesis

Lymphopoiesis is the process in which B and T cells, and innate lymphoid cells (ILCs) develop from hematopoietic progenitors that exhibit early lymphoid priming. The branching points where lymphoid-primed human progenitors are further specified to B/T/ILC differentiation trajectories remain unclear. Here, we discuss the emerging role of interferon regulatory factor (IRF)8 as a key factor to bridge human lymphoid and dendritic cell (DC) differentiation, and the current evidence for the existence of circulating and tissue-resident CD123+CD127+ lymphoid progenitors. We propose a model whereby DC/B/T/ILC lineage programs in circulating CD123+CD127+ lymphoid progenitors are expressed in balance. Upon tissue seeding, the tissue microenvironment tilts this molecular balance towards a specific lineage, thereby determining in vivo lineage fates. Finally, we discuss the translational implication of these lymphoid precursors.

Aligning the Cord Blood-Bone Marrow Differences and the Post-transplantation Clinical Manifestations by Single-Cell RNA-Seq

Cord blood (CB) transplantation is a promising treatment for hematologic malignancies due to its strong graft-versus-leukemia effect and a low incidence of graft-versus-host disease. However, the risk of infection caused by delayed engraftment has limited its clinical application. In this study, we compared the single-cell RNA-seq of CB, bone marrow (BM), and granulocyte colony-stimulating factor primed BM to understand the differences between these grafts from a comprehensive view, and verified some differences in our clinical data of patients receiving transplantation. We focused on the biological features of key cell types involving the hematopoietic reconstitution and immune reconstitution. Based on the comparison of homing signal and differentiation potential of hematopoietic stem/progenitor cells (HSPCs), CB exhibited a lower content of HSPCs with weaker homing ability but higher stemness than BM. In addition, CB had a higher proportion of naïve T cells, while BM had a higher abundance of effector and memory T cells. Notably, the CD4+ naïve T cells in CB were prone to differentiate into Tregs. In response to neoantigens, the immune activation interactions between T cells and antigen-presenting cells were strong in CB, including CD40_CD40LG, IL16_CD4, and so on. In our clinical data, the subpopulation variations of T cells and the status of monocytes after transplantation were consistent with the results of the single-cell RNA-seq study above. CB, as a new birth system, is immature and active; several mechanisms contribute to its good anti-tumor effect, which can be introduced to other grafts. These findings provide insights into the development of new strategies for hematologic malignancies treatment.

TRPV4 mRNA is elevated in the caudate nucleus with NPH but not in Alzheimer's disease

Symptoms of normal pressure hydrocephalus (NPH) and Alzheimer's disease (AD) are somewhat similar, and it is common to misdiagnose these two conditions. Although there are fluid markers detectable in humans with NPH and AD, determining which biomarker is optimal in representing genetic characteristics consistent throughout species is poorly understood. Here, we hypothesize that NPH can be differentiated from AD with mRNA biomarkers of unvaried proximity to telomeres. We examined human caudate nucleus tissue samples for the expression of transient receptor potential cation channel subfamily V member 4 (TRPV4) and amyloid precursor protein (APP). Using the genome data viewer, we analyzed the mutability of TRPV4 and other genes in mice, rats, and humans through matching nucleotides of six genes of interest and one house keeping gene with two factors associated with high mutation rate: 1) proximity to telomeres or 2) high adenine and thymine (A + T) content. We found that TRPV4 and microtubule associated protein tau (MAPT) mRNA were elevated in NPH. In AD, mRNA expression of TRPV4 was unaltered unlike APP and other genes. In mice, rats, and humans, the nucleotide size of TRPV4 did not vary, while in other genes, the sizes were inconsistent. Proximity to telomeres in TRPV4 was <50 Mb across species. Our analyses reveal that TRPV4 gene size and mutability are conserved across three species, suggesting that TRPV4 can be a potential link in the pathophysiology of chronic hydrocephalus in aged humans (>65 years) and laboratory rodents at comparable ages.

In vivo G-CSF treatment activates the GR-SOCS1 axis to suppress IFN-γ secretion by natural killer cells

Natural killer (NK) cells are lymphocytes that are involved in controlling tumors or microbial infections through the production of interferon gamma (IFN-γ). Granulocyte colony-stimulating factor (G-CSF) inhibits IFN-γ secretion by NK cells, but the mechanism underlying this effect remains unclear. Here, by comparing the multi-omics profiles of human NK cells before and after in vivo G-CSF treatment, we identify a pathway that is activated in response to G-CSF treatment, which suppresses IFN-γ secretion in NK cells. Specifically, glucocorticoid receptors (GRs) activated by G-CSF inhibit secretion of IFN-γ by promoting interactions between SOCS1 promoters and enhancers, as well as increasing the expression of SOCS1. Experiments in mice confirm that G-CSF treatment significantly downregulates IFN-γ secretion and upregulates GR and SOCS1 expression in NK cells. In addition, GR blockade by the antagonist RU486 significantly reverses the effects of G-CSF, demonstrating that GRs upregulate SOCS1 and inhibit the production of IFN-γ by NK cells.

Mining the multifunction of mucosal-associated invariant T cells in hematological malignancies and transplantation immunity: A promising hexagon soldier in immunomodulatory

Mucosal-associated invariant T (MAIT) cells are evolutionarily conserved innate-like T cells capable of recognizing bacterial and fungal ligands derived from vitamin B biosynthesis. Under different stimulation conditions, MAIT cells can display different immune effector phenotypes, exerting immune regulation and anti-/protumor responses. Based on basic biological characteristics, including the enrichment of mucosal tissue, the secretion of mucosal repair protective factors (interleukin-17, etc.), and the activation of riboflavin metabolites by intestinal flora, MAIT cells may play an important role in the immune regulation effect of mucosal lesions or inflammation. At the same time, activated MAIT cells secrete granzyme B, perforin, interferon γ, and other toxic cytokines, which can mediate anti-tumor effects. In addition, since a variety of hematological malignancies express the targets of MAIT cell-specific effector molecules, MAIT cells are also a potentially attractive target for cell therapy or immunotherapy for hematological malignancies. In this review, we will provide an overview of MAIT research related to blood system diseases and discuss the possible immunomodulatory or anti-tumor roles that unique biological characteristics or effector phenotypes may play in hematological diseases.