Journal of Leukocyte Biology最新文献

Prior studies have demonstrated associations between eosinophil activation products and incident stroke. We investigated whether circulating eosinophil concentration is associated with imaging markers of atherosclerotic cardiovascular disease (ASCVD), analyzing two arterial beds (carotid artery plaque [CAP] and coronary artery calcium [CAC]) in the Multi-Ethnic Study of Atherosclerosis (MESA). The MESA enrolled individuals age 45-84, without ASCVD at baseline. ASCVD risk factors, blood eosinophils, CAP presence/score (0-12) and CAC presence/Agatston score were measured at MESA Exam No. 5. Using logistic and linear regression analyses, the relationships between blood eosinophils, CAP or CAC presence, or scores (log[score+1]), adjusted for confounders, were evaluated. The 2,166 participants were a mean (standard deviation [SD]) 69.6 (9.3) years old, 53% female, 29% Hispanic, 28% Black, 1% Chinese American. The eosinophil count was median (interquartile range) 0.10 (0.10,0.20) x 103/μl, CAP score 2 (0,4) and CAC score 45 (0,292) Agatston units. In risk-factor adjusted models, increased blood eosinophil count (per 1 SD [0.15x103/μl]) associated with log scores of CAP (β: 0.05 [95% CI 0.02 to 0.08, p = 0.001) or CAC (β: 0.11, [0.01 to 0.21], p = 0.03). Similar associations were observed for eosinophils and CAP (odds ratio [OR]: 1.12, [1.01 to 1.25], p = 0.03) and CAC (OR: 1.15, [1.02 to 1.30], p = 0.02) presence. In conclusion, in a large, multi-ethnic US cohort, blood eosinophils were independently linked to imaging atherosclerosis measures in two arterial distributions. These data suggest potential roles of eosinophilic inflammation in atherosclerosis.

Bazedoxifene is a selective estrogen receptor modulator that is prescribed to menopausal women to treat symptoms of estrogen deficiency. Furthermore, bazedoxifene is being considered for cancer therapeutics due to its ability to block IL-6 signaling. However, various selective estrogen receptor modulators have been shown to dysregulate the activation and functions of immune cells. Neutrophils are critical players during inflammation, and these medications have been shown to modulate neutrophil activity. Hence, we hypothesize that bazedoxifene could interact with neutrophils and affect their functions. We collected neutrophils from healthy female and male donors and treated them with bazedoxifene. We assessed neutrophil viability by flow cytometry and their metabolic activity with an extracellular flux analyzer (Seahorse). The production of cytokines, phagocytosis, and the production of reactive oxygen species were measured by ELISA, the uptake of pHrodo-conjugated E. coli, and luminol chemiluminescence, respectively. Finally, estrogen receptor and kinase inhibitors were used to investigate mechanisms of action. High doses of bazedoxifene compromise neutrophil viability in a sex-dependent manner. However, these concentrations can increase the release of inflammatory cytokines while impairing antimicrobial functions in both sexes. The effects of bazedoxifene on neutrophil function are independent of estrogen receptors but may be partially mediated by p38 MAPK activation. Taken together, bazedoxifene could promote neutrophilic inflammation by releasing chemokines while hindering pathogenic clearance. These observations expand our knowledge on the adverse effects of selective estrogen receptor modulators on immune cells, and they highlight the importance to understanding their activity before becoming repurposed to treat chronic conditions.

Tumor necrosis factor-α (TNF) and its receptors have emerged as key players in autoimmunity but also influence tumor development and the tumor microenvironment in many ways. TNF-inhibiting biologics are used very successfully in the clinic to treat autoimmune diseases. However, in some TNF-mediated diseases, TNF blockers are either ineffective or even worsen the disease course. One possible explanation for this treatment failure is that TNF blockers inhibit not only the typically TNF receptor-1 (TNFR1)-mediated TNF pathology, but also the immunosuppressive activities of TNFR2. Therefore, there is great interest in testing TNFR1- and TNFR2-specific biologics in autoimmune diseases and tumor therapy. In this review, we focus on the development of TNFR2-selective biologics. After a brief introduction to the biology and pathobiology of TNFR2, we discuss in detail the current concepts of how TNFR2 becomes activated by its natural ligands but also by genetically engineered biologics. This serves as a rational basis for discussing the aspects that must be considered in the development of both inhibitors and engagers of TNFR2. In particular, we provide a comprehensive overview on the structure and molecular mode of action of the plethora of published TNFR2-targeting biologics, paying particular attention to common principles and mechanisms but also to the limitations and challenges of some of these biologics.

CD101 is a disulfide-linked immunoglobulin-like glycoprotein with a unique glutamine-tryptophan-isoleucine (EWI) sequence motif. Allelic variations within the Cd101 gene can influence CD101 expression and function of different myeloid cell and T lymphocyte populations. CD101 serves also as maturation marker for neutrophils and differentiation marker for dendritic cell (DC), eosinophil and T cell subsets. While the numbers of CD101-expressing eosinophils and T lymphocytes increase in certain chronic disorders, DCs, macrophages and neutrophils with reduced expression of this transmembrane molecule are transiently observed during acute inflammation, cytokine exposure or bacterial infection. Indeed, cell-specific expression of CD101 correlates with different functional responses and cellular phenotypes in various settings including Mycobacterium tuberculosis and viral infections, allergic disorders and cancer immunotherapy. Importantly, myeloid cells and regulatory T cells mediate more powerful protection against experimental enterocolitis and type 1 diabetes when they both express CD101. In contrast, CD101 expression on eosinophils is associated with enhanced inflammatory responses. Moreover, CD101-expressing neutrophils limit bacterial infections better than CD101-deficient cells. Thus, CD101 simultaneously contributes to the restriction of microbial infections and the regulation of immune-mediated tissue damage. However, the mechanisms underlying the diverse functions of CD101 as well as the general biological role of CD101 have not been characterized yet. Moreover, the factors contributing to the regulation of CD101 expression remain unknown. Here, we review current information about the immune-modulatory and anti-microbial functions of CD101. Moreover, we discuss the potential role of CD101 as biomarker for inflammatory and infectious diseases and as predictor for the outcome of cancer immunotherapy.

IKZF3/Aiolos is a zinc-finger transcriptional transcription factor that functions as a transcriptional repressor in B cell development. IKZF3 mutations are associated with human diseases including immunodeficiency, leukemia and lymphoma. H195Y IKZF3 mutation was discovered in a mouse model of precursor B cell acute lymphoblastic leukemia. Forced expression of H195Y IKZF3 in pre-B cells altered gene expression changes induced by interleukin-7. The goal of this study was to determine how H195Y mutation of IKZF3 affects its regulation of target genes. To address this goal, we determined the effect of wild type (WT) versus mouse H195Y or human H196Y IKZF3 on three direct target genes, Cish, Il7r, and Igll1. We found that mouse or human IKZF3 repressed Cish, Il7r, and Igll1 promoter reporter activity in transiently transfected pre-B ALL cell lines. H195Y IKZF3 failed to repress Cish, Il7r, and Igll1 promoter activity. Stable transduction with mouse H195Y or human H196Y IKZF3 increased endogenous Cish and Igll1 gene expression in pre-B-ALL cell lines. H196Y IKZF3 had increased stability compared to WT IKZF3 in transduced cells, with a half-life of 10.3 hrs compared to 6.0 hr for WT IKZF3. In summary, these experiments suggest that H195Y/H196Y mutation of IKZF3 impairs transcriptional repression activity of IKZF3. Second, this mutation increases protein stability, resulting in higher levels of protein expression. This study provides insight into mechanisms by which IKZF3 mutations promote immunodeficiency, leukemia, and lymphoma.

Mucosal-associated invariant T (MAIT) cells are unique unconventional T cells with diverse roles in immunity, yet how their context informs their function is not well known. This contextual regulation is particularly relevant in cancer, where MAIT cells have an enigmatic role. We performed a systematic review and meta-analysis to identify MAIT cell transcriptomic signatures under different environmental conditions. We identified 4 bulk-RNA-sequencing studies that compared multiple activation stimuli. We found a stimulus-specific transcriptional signature for immune checkpoint genes, that we confirmed in a single-cell RNA-sequencing dataset. We used flow cytometry to examine in vitro human MAIT cells across 4 activation stimuli and confirmed that stimulus drives unique checkpoint signatures upon MAIT activation for Lag3, PD-L1, PD-1, NKG2A, and Tigit. Strikingly, PD-L1 was more highly induced in vitro than PD-1 in MAIT cells up to 72 h. Our data suggest that human MAIT cell regulation is context-dependent. These findings have the potential to critically inform efforts targeting MAIT cells for cancer immunotherapy.

Severe burns complicated by acute lung injury are critical causes of respiratory failure and multiple organ dysfunction syndrome. Neutrophils extensively infiltrate lung tissues early postburn to mediate pulmonary damage, but the underlying mechanisms remain unclear. We analyzed gut microbiota of severe burn patients via metagenomics and metabolomics, assessed neutrophil chemotaxis using a self-developed in vitro agarose model, and validated Faecalibacterium prausnitzii and butyrate's effects on restoring neutrophil chemotaxis in gut microbiota-depleted mice via oral gavage (plus in vivo validation with small animal imaging). Bronchoalveolar lavage fluid biomarkers and pulmonary function tests evaluated pulmonary injury from impaired neutrophil chemotaxis. Early postburn, F. prausnitzii and its metabolite butyrate were significantly depleted in patients, concurrent with impaired neutrophil chemotaxis-restored by butyrate supplementation. In murine burn models, F. prausnitzii or butyrate rescued neutrophil chemotaxis, reduced pulmonary neutrophil infiltration, and attenuated lung injury. Mechanistically, butyrate restored neutrophil function in a severe burn patient plasma-stimulated model by downregulating P2X1 receptor expression and suppressing myosin light chain phosphorylation. Our findings indicate postburn gut microbiota dysbiosis and metabolite alterations disrupt neutrophil chemotaxis, causing excessive pulmonary neutrophil infiltration/activation. This highlights gut microbiota-derived metabolites as potential therapeutics for mitigating neutrophil-driven lung injury early postsevere burns.

Ovarian cancer remains the most lethal gynecologic malignancy, due in part to the establishment of a profoundly immunosuppressive tumor microenvironment (TME). While toll-like receptor 5 (TLR5) signaling has previously been implicated in promoting myeloid cell recruitment to the ovarian TME, source(s) of ligand and systemic effects on hematopoiesis remain poorly understood. Here, we demonstrate that ovarian cancer disrupts gut barrier integrity, leading to systemic translocation of TLR5 ligands into the peritoneum, blood, and bone marrow. This translocation correlates with enhanced expansion of myeloid progenitors in the bone marrow of wild-type (WT) but not TLR5-deficient (TLR5 KO) mice, leading to enhanced accumulation of monocytes and macrophages into the TME. In the bone marrow, direct TLR5 signaling induced expansion of TLR5-expressing granulocyte-monocyte progenitors, a phenotype recapitulated both using an in vitro colony-forming assay and in a mixed bone marrow chimera model. Acute pharmacologic blockade of TLR5 in tumor-bearing mice altered the composition of tumor-associated myeloid populations, reducing the frequency of monocytes and CCR2-expressing macrophages accumulating within the TME of WT mice. These data reveal that chronic TLR5 signaling, driven by tumor-induced loss of gut barrier integrity, promotes expansion of myeloid cells within the bone marrow and is a host-intrinsic mechanism driving accumulation of immature monocytes and macrophages into the TME.

While sex differences in neutrophil metabolism have been documented, whether this metabolic dimorphism extends to specific neutrophil subsets remains unknown. Low-density neutrophils (LDNs) are characterized by their lower buoyant density compared with normal-density neutrophils (NDNs), are present in low numbers in healthy individuals, and are often associated with disease severity and immune dysregulation. LDNs and NDNs from healthy human donors were isolated, whereafter cellular metabolism, specifically oxidative phosphorylation and glycolysis, alongside flow cytometry for maturity markers (CD16hi/lo), was assessed. Male LDNs exhibited significantly higher basal oxygen consumption rate (OCR) and adenosine triphosphate production than female LDNs, while no sex differences were observed in NDNs. Strikingly, male LDNs also had higher OCR and glycolysis than their matched NDNs, whereas female LDNs exhibited a lower OCR than their NDNs. Our study reveals subset-specific sexual metabolic reprogramming in LDNs, whereby male LDNs exhibit a hypermetabolic phenotype. These findings provide a metabolic basis for sex-biased immune responses and highlight the need for sex-stratified approaches in neutrophil-targeted therapies.

As the barrier between the contents of the intestines and the rest of the body, intestinal epithelial cells (IEC) occupy a crucial niche for the health of the organism. They are responsible for nutrient absorption and transfer, barrier maintenance, and interactions with the massive community of microorganisms that live in the gut. While this community primarily includes commensal microbes, many pathogens use the gastrointestinal tract as an initial site of infection. IEC are important as a physical barrier, but a growing body of research demonstrates their importance as active participants in host immunity. In this review, we discuss the role of IEC in responding to infection by intracellular bacteria, parasites, and viruses. IEC express an array of intracellular sensors to rapidly detect invading pathogens and initiate cytokine production. In addition, IEC are equipped to present antigen to T cells, and express co-stimulatory molecules that enhance or limit T cell responses, although the impact of these interactions remains unclear. Determining how IEC participate in host immunity and pursuing the open questions we identify in this review will be broadly important for understanding infection and immunity in the gastrointestinal tract.