1,721,032 research outputs found
On the Improper Use of the Term High-Density Neutrophils
No full textRecent studies have revealed that neutrophils exhibit an unsuspected heterogeneity. In this context, the term high-density neutrophils (HDNs) has recently gained ground to define nothing more than neutrophils displaying an unaltered normal density. Therefore, as discussed here, we argue that the HDNs term must be avoided, as it is confounding and scientifically inappropriate
Social networking of human neutrophils within the immune system
No full textIt is now widely recognized that neutrophils are highly versatile and sophisticated cells that display de novo synthetic capacity and may greatly extend their lifespan. In addition, concepts such as "neutrophil heterogeneity" and "neutrophil plasticity" have started to emerge, implying that, under pathological conditions, neutrophils may differentiate into discrete subsets defined by distinct phenotypic and functional profiles. A number of studies have shown that neutrophils act as effectors in both innate and adaptive immunoregulatory networks. In fact, once recruited into inflamed tissues, neutrophils engage into complex bidirectional interactions with macrophages, natural killer, dendritic and mesenchymal stem cells, B and T lymphocytes or platelets. As a result of this crosstalk, mediated either by contact-dependent mechanisms or cell-derived soluble factors, neutrophils and target cells reciprocally modulate their survival and activation status. Altogether, these novel aspects of neutrophil biology have shed a new light not only on the potential complex roles that neutrophils play during inflammation and immune responses, but also in the pathogenesis of several inflammatory disorders including infection, autoimmunity and cancer
On the detection of neutrophil-derived vascular endothelial growth factor (VEGF)
No full textNo availabl
REGULATION OF B-CELL–ACTIVATING FACTOR (BAFF)/B LYMPHOCYTE STIMULATOR (BLyS) EXPRESSION IN HUMAN NEUTROPHILS
No full textThe expression and production of cytokines by cells of the innate immune system, including monocytes/macrophages, dendritic and NK cells, play a critical role not only in defensive and inflammatory but also in immunoregulatory and anti-/pro-tumoral processes. Studies performed in the last years have well ascertained that polymorphonuclear neutrophils can also be induced to express and produce chemokines, proinflammatory, anti-inflammatory, immunoregulatory, angiogenic and fibrogenic cytokines, as well as ligands belonging to the TNF superfamily. Among the latter group of molecules, B-cell-activating factor (BAFF)/B lymphocyte stimulator (BLyS), known to be essential for B lymphocyte homeostasis and related pathologies, has recently been identified as one of the factors potentially expressed by human neutrophils. The addition of this novel TNF superfamily member, and more recently also of the closely related "A Proliferation-Inducing Ligand" (APRIL), to the list of cytokines produced by neutrophils not only testifies to the continuous growth of this area of investigation, but also implies the involvement of neutrophils in B-cell-dependent autoimmune diseases and tumors
How murine neutrophils are hijacked within the microenvironment of pancreatic cancer
No full textDiscoveries made in the past decades have brought out that, in addition to their classical primary defensive functions against infections, polymorphonuclear neutrophils play key effector roles not only in chronic inflammatory and immune-mediated diseases but also in cancer. In addition, depending on their differentiation/activation status and/or on the physiological or pathological microenvironment in which they reside, neutrophils have been shown to behave as highly plastic cells, able to acquire new phenotypes/functional states. All these features are well manifested in cancer and modulated during tumor progression. Herein, we discuss intriguing data by Lai Ng's group that have shed light on the origin and development of terminally differentiated, proangiogenic, tumor-associated neutrophils, facilitating tumor growth in a murine orthotopic model of pancreatic ductal adenocarcinoma. These findings help to progress toward the ambitious goal of selectively targeting only the skewed pathological neutrophil populations present within the tumor microenvironment
Location in the spleen dictates the function of murine neutrophils
No full textIn this issue of JEM, Deniset et al. (https://doi.org/10.1084/jem.20161621) provide new data that extend our knowledge on the mechanisms whereby Streptococcus pneumoniae is cleared by the spleen. The authors identify novel populations of murine splenic neutrophils that localize in the red pulp and the marginal zone. During the acute phases of S. pneumoniae infection, these populations of splenic neutrophils act in concert with specialized macrophage and B cell populations to provide very rapid innate immune protection
Neutrophil Diversity in Health and Disease
No full textNew evidence has challenged the outdated dogma that neutrophils are a homogeneous population of short-lived cells. Although neutrophil subpopulations with distinct functions have been reported under homeostatic and pathological conditions, a full understanding of neutrophil heterogeneity and plasticity is currently lacking. We review here current knowledge of neutrophil heterogeneity and diversity, highlighting the need for deep genomic, phenotypic, and functional profiling of the identified neutrophil subpopulations to determine whether these cells truly represent bona fide novel neutrophil subsets. We suggest that progress in understanding neutrophil heterogeneity will allow the identification of clinically relevant neutrophil subpopulations that may be used in the diagnosis of specific diseases and lead to the development of new therapeutic approaches
Multiple roles of Lyn kinase in myeloid cell signaling and function.
No full textLyn is an Src family kinase present in B lymphocytes and myeloid cells. In these cell types, Lyn establishes signaling thresholds by acting as both a positive and a negative modulator of a variety of signaling responses and effector functions. Lyn deficiency in mice results in the development of myeloproliferation and autoimmunity. The latter has been attributed to the hyper-reactivity of Lyn-deficient B cells due to the unique role of Lyn in downmodulating B-cell receptor activation, mainly through phosphorylation of inhibitory molecules and receptors. Myeloproliferation results, on the other hand, from the enhanced sensitivity of Lyn-deficient progenitors to a number of colony-stimulating factors (CSFs). The hyper-sensitivity to myeloid growth factors may also be secondary to poor inhibitory receptor phosphorylation, leading to impaired recruitment/activation of tyrosine phosphatases and reduced downmodulation of CSF signaling responses. Despite these observations, the overall role of Lyn in the modulation of myeloid cell effector functions is much less well understood, as often both positive and negative roles of this kinase have been reported. In this review, we discuss the current knowledge of the duplicitous nature of Lyn in the modulation of myeloid cell signaling and function
- …
