Journal of Leukocyte Biology最新文献

Host defense functions of neutrophils during infection critically depend on microbicidal and proteolytic proteins stored in primary, secondary, and tertiary granules that are released into the phagosome or into the extracellular space upon degranulation. Granules are generated during granulopoiesis, and impaired granule production or granule protein sorting has been linked to inefficient pathogen clearance resulting in recurrent bacterial and fungal infections. Here, we studied the role of secretory carrier associated membrane protein 3 (SCAMP3) for neutrophil defense functions. We generated Scamp3 knockout (KO) Hoxb8 cells and found that killing of Escherichia coli by Scamp3 KO Hoxb8 cell-derived neutrophils (dHoxb8 cells) was compromised as compared with control dHoxb8 cells in vitro. Mass spectrometric and Western blot analyses revealed a significant reduction of primary, secondary, and tertiary granule proteins in the genetic absence of Scamp3, resulting in a reduced overall granularity of these cells. Accordingly, degranulation was reduced in Scamp3 KO dHoxb8 cells compared with control dHoxb8 cells. Similarly, Scamp3 deficiency in zebrafish resulted in reduced neutrophil granularity in comparison with wild-type animals. However, neutrophil migration toward sites of E. coli infection was unaffected in scamp3 KO zebrafish larvae. In summary, SCAMP3 represents an important novel player in granule equipment and degranulation, with key functions in neutrophil defense mechanisms during host-pathogen interactions in vitro.

Evolutionarily conserved HOXA9 is a well-known player of hematopoiesis and leukemogenesis. However, the involvement of this transcription factor in CD4+ T cell development is largely unexplored. Th2 cells play a critical role in the pathogenesis of numerous autoimmune disorders. The development of this heterogenic subpopulation of cells is orchestrated by a consortium of factors including GATA3 and PU.1, among others. Here, we recognized the molecular regulation bestowed by HOXA9 in Th2 cell development. We found that overexpression of HOXA9 in Th2 cell leads to increased secretion of IL-10 while suppressing IL-4 and IL-13. Through promoter activity analysis, we determined the crucial role played by the structural domains of HOXA9 on Th2-specific cytokines. These findings further indicated the presence of other cofactors that contribute to the functional activity of HOXA9. Our findings demonstrated that HOXA9 can engage in physical interactions with PU.1 and PBX1, but not with GATA3, and exhibits direct binding to PU.1-specific chromosomal loci within Th2 cells. PBX1 overexpression stimulates the secretion of IL-4, IL-13, and IL-10. In contrast, the combined overexpression of HOXA9 and PBX1 suppresses IL-4 and IL-13 secretion but boosts IL-10 production. Taken together, the data suggest that PBX1 acts specifically as a coregulator for HOXA9 in the context of Th2 cell function. The contribution of HOXA9 and PBX1 is significantly more pronounced in the proximal promoter region of the Il10 gene. This study has significantly advanced our understanding of Th2 cell differentiation and cytokine production, regulated by HOXA9-PBX1 axis through interactions with other key transcription factors.

Regulatory T cells (Tregs) play a crucial role in the immune system, and their dysfunction can lead to the development of autoimmune conditions. In cancer, tumors frequently hijack the immunosuppressive function of Tregs to evade immune responses. Due to their central role in key pathological processes, Tregs have gained increasing attention as promising targets for various clinical applications. However, their relative scarcity (∼5% to 10% of CD4+ T cells) and instability presents a technical challenge for research and therapeutic development. In congenic animal models used to investigate autologous cell transfer-based therapies, this challenge is even greater, as Treg donor animals may only be able to provide cells to a small number of recipient mice. Here, we present an optimized protocol for ex vivo editing and expansion of mouse Tregs. Because a recent study demonstrated the anticancer potential of SRC-3 KO mouse Tregs, we use them here as a case study.

Following the 2025 Nobel Prize in Physiology or Medicine for the discovery of regulatory T cells (Tregs), a recent article in Nature Communications reports the generation of allogeneic, genome-edited Tregs engineered to evade immune rejection while retaining suppressive function. Through non-viral CRISPR deletion of B2M and CIITA and insertion of an HLA-E-B2M fusion, the authors produced hypo-immunogenic Tregs that persisted and promoted graft tolerance in humanized mice. In this News and Views, the promise and challenges of such universal "off-the-shelf" Tregs are discussed, emphasizing how genome engineering is reshaping Treg biology into a new era of programmable immune tolerance.

Neuroinflammation plays a vital role in determining the trajectory of Alzheimer's disease (AD) progression. In the AD brain, microglial exposure to pathological amyloid β (Aβ42) and tau peptide aggregates results in an NLRP3 inflammasome-activated proinflammatory response that ranges from mild to severe. Recently we have shown that dementia subjects with higher levels of soluble TAM receptors Tyro3 and AXL in the cerebrospinal fluid indicated cognitive protection. The molecular mechanism for this protective effect of TAM receptors is unknown. Here, we identified a beneficial role of TAM receptors using Tyro3-overexpressing (Tyro3OE) and Axl-overexpressing THP-1 cells. In the Tyro3OE cells, the levels of the proinflammatory cytokine IL-1β were markedly decreased in the AD microenvironment (tau + Aβ42) and the classical NLRP3 inflammasome model (lipopolysaccharide [LPS] + nigericin) in comparison with the control cells. This was mediated by increased STAT1 phosphorylation and reduced IL-1β transcription enhancer C-EBP-β in Tyro3OE cells. The use of the JAK1/2 inhibitor ruxolitinib reduced the phosphorylation of STAT1, leading to a partial restoration of IL-1β in the Tyro3OE cells. Last, we found a significantly reduced IL-1β in the brains of AD mice that has activated TAM signaling through Gas6-α-Aβ lentiviral injection. In summary, TAM receptor Tyro3 overexpression decreased AD-associated IL-1β release from macrophages thereby uncovering a potential beneficial role for TAM receptors during neuroinflammation in AD.

Macrophage migration inhibitory factor (MIF) is broadly produced by various cell types, particularly immune cells, and functions as a key modulator of innate and adaptive immunity. Increasing evidence has linked MIF to the pathogenesis of both solid tumors and hematologic malignancies, including chronic lymphocytic leukemia (CLL). We previously showed that the global deletion of Mif in the TCL1 transgenic mouse model for CLL significantly delayed disease development leading to longer overall survival of the knockout mice. In this study, we demonstrated that adaptive transfer of murine CLL cells failed to establish disease in Mif-deficient recipients due to impaired homing of leukemic cells into the spleens, indicating that host-derived Mif is essential for leukemic infiltration and expansion. To identify the most relevant source of Mif in CLL, we generated two CLL mouse strains with B-lymphoid- or myeloid-lineage-specific Mif deletion. In contrast to the global Mif knockout, neither conditional Mif knockout significantly altered CLL progression, illustrating that the cellular source of Mif is less critical than its systemic presence in the tissue environment.

Rhesus theta defensin (RTD)-1, a cyclic antimicrobial peptide, regulates gene expression and immune signaling pathways in cell culture and animal models of immune-mediated diseases. In lipopolysaccharide-stimulated cells, RTD-1 inhibition of proinflammatory cytokine secretion and gene expression is mediated through inhibition of the NF-κB and MAP kinase signaling pathways. To gain insights into RTD-1 regulation of naïve cells, we performed RNA sequencing (RNA-seq) to determine the effect of the peptide on global gene expression in human monocytes and THP-1 monocytes. In both cell types, analysis of differentially expressed genes revealed stimulation of interferon and antiviral gene expression pathways. RTD-1 induced Y701 phosphorylation of STAT1 and activated the ISRE reporter in a JAK-dependent manner. Stimulation of the ISRE reporter by RTD-1 was interferon-α/β receptor dependent but was independent of its NF-κB inhibitory activity in lipopolysaccharide-stimulated cells. RTD-1 inhibited infection of vesicular stomatitis virus pseudotyped with G glycoprotein or SARS-CoV-2 spike protein in THP-1 and Vero E6 cells, respectively. RTD-1 also inhibited infection of Calu-3 2B4 cells by SARS-CoV-2 virus, demonstrating antiviral activity of RTD-1 in diverse cell types. These results demonstrate that RTD-1 stimulates interferon and antiviral pathways, potentially priming cells for resistance to viral infection.

Neutrophils, our frontline of defense against pathogens, exhibit pronounced sexual dimorphism in ontogeny, phenotype, and effector functions. Throughout the human lifespan, estrogen and androgen signaling, together with sex-linked genetic regulators, orchestrate neutrophil production, maturation, and immune activity, contributing to immunological differences between sexes observed across lifespan. Differences in neutrophil antimicrobial and immune responses contribute to disease susceptibility, with females having not only stronger antimicrobial defenses, but also a higher risk of autoimmunity, while males experience greater severity of infections and different cancer risks. This review summarizes and discusses the existing evidence on regulation of neutrophil biology by sex. We (1) describe the dynamics of neutrophils throughout human life in both females and males, (2) delineate sex-specific regulation of neutrophil phenotype and function, and (3) examine the significance of these differences in the susceptibility and outcomes of neutrophil-driven diseases.

Adoptive cell therapy using ex vivo expanded autologous Tregs could be a novel therapeutic approach for cell-based immunotherapy in dogs. This study aimed to expand dog Treg lymphocytes via the use of tregitopes. Peripheral blood mononuclear cells (PBMCs) were isolated from healthy beagle dogs and stimulated with peptides: human tregitope EEQ; two potential canine tregitopes, EQF and PSV; and whole canine IgG in primary cultures. In addition, lymphocytes were simultaneously stimulated with peptides and canine vaccine antigens. The frequencies of Treg lymphocytes (CD4 + CD25 + Foxp3+, CD4 + Foxp3+) and activated lymphocytes (CD4 + CD25+) were determined by flow cytometry. A statistically significant increase in the frequency of CD4 + Foxp3+ and CD4 + CD25 + Foxp3+ lymphocytes stimulated with PSV and EQF peptides and canine IgG was observed. No increase in the Treg lymphocyte frequency occurred after EEQ Tregitope stimulation or vaccine antigen costimulation. Canine Treg lymphocytes isolated from peripheral blood are sensitive to stimulation with peptides with potential tregitope properties derived from canine proteins.

Assembly of NADPH oxidase 2 (NOX2) proteins in neutrophils plays an essential role in controlling microbial infections by producing high levels of reactive oxygen species (ROS). We report that neutrophils and NOX2 are required to control Pseudomonas aeruginosa in a clinically relevant murine model of blinding corneal infection. Given the published role for the voltage-gated proton channel Hv1 in sustaining NOX2-mediated ROS production, we examined the role of Hv1 in P. aeruginosa keratitis. Hvcn1-/- mice exhibited an impaired ability to kill bacteria that was associated with reduced neutrophil recruitment to infected corneas. However, in contrast to earlier reports, we found that Hvcn1-/- neutrophils produce more rather than less ROS compared with control, wild type neutrophils infected with P. aeruginosa or stimulated with PMA or zymosan. Collectively, we demonstrate that Hv1 has an important role in control of bacterial growth by neutrophils in bacterial infection beyond the regulation of ROS production.