Heterogeneity of neutrophils in arterial hypertension

A high concentration of neutrophil extracellular traps is observed in humans and mice suffering from endometriosis

We wished to ascertain if there is an association between neutrophil extracellular traps and endometriosis (EMS). We collected the lesional tissues and normal endometrium of 30 patients suffering from endometriosis. Samples were also taken from healthy controls. Blood from the peripheral circulation was collected to isolate serum and neutrophils. A mouse model of endometriosis was also created. Expression of citrullinated histone and the myeloperoxidase level in tissue were measured by immunofluorescence staining and western blotting. The myeloperoxidase level in peripheral blood serum was measured by enzyme-linked immunosorbent assay. Staining (Trypan Blue) and flow cytometry were used to measure the apoptosis of neutrophils in peripheral blood. BALB/C mice were modeled by allotransplantation, and the experimental parameters noted above quantified. The myeloperoxidase content in the peripheral blood of patients with endometriosis was increased compared with that in healthy controls. Flow cytometry showed that the percent apoptosis of neutrophils in patients with endometriosis was lower than that in healthy controls. Expression of citrullinated histone was higher in the endometriosis group in humans and mice compared with respective controls according to immunofluorescence staining and western blotting. Our data suggest that a high concentration of neutrophil extracellular traps was observed in humans and mice suffering from endometriosis.

Low-Density Neutrophils Contribute to Subclinical Inflammation in Patients with Type 2 Diabetes

Type 2 diabetes (T2D) is characterized by low-grade inflammation. Low-density neutrophils (LDNs) represent normally less than 2% of total neutrophils but increase in multiple pathologies, releasing inflammatory cytokines and neutrophil extracellular traps (NETs). We assessed the count and role of high-density neutrophils (HDNs), LDNs, and NET-related activities in patients with T2D. HDNs and LDNs were purified by fluorescence-activated cell sorting (FACS) and counted by flow cytometry. Circulating inflammatory and NETs biomarkers were measured by ELISA (Enzyme Linked Immunosorbent Assay). NET formation was quantified by confocal microscopy. Neutrophil adhesion onto a human extracellular matrix (hECM) was assessed by optical microscopy. We recruited 22 healthy volunteers (HVs) and 18 patients with T2D. LDN counts in patients with diabetes were significantly higher (160%), along with circulating NETs biomarkers (citrullinated H3 histone (H3Cit), myeloperoxidase (MPO), and MPO-DNA (137%, 175%, and 69%, respectively) versus HV. Circulating interleukins (IL-6 and IL-8) and C-Reactive Protein (CRP) were significantly increased by 117%, 171%, and 79%, respectively, in patients compared to HVs. Isolated LDNs from patients expressed more H3Cit, MPO, and NETs, formed more NETs, and adhered more on hECM compared to LDNs from HVs. Patients with T2D present higher levels of circulating LDN- and NET-related biomarkers and associated pro-inflammatory activities.

Neutrophil heterogeneity and aging: implications for COVID-19 and wound healing

Neutrophils play a critical role in the immune response to infection and tissue injury. However, recent studies have shown that neutrophils are a heterogeneous population with distinct subtypes that differ in their functional properties. Moreover, aging can alter neutrophil function and exacerbate immune dysregulation. In this review, we discuss the concept of neutrophil heterogeneity and how it may be affected by aging. We then examine the implications of neutrophil heterogeneity and aging for COVID-19 pathogenesis and wound healing. Specifically, we summarize the evidence for neutrophil involvement in COVID-19 and the potential mechanisms underlying neutrophil recruitment and activation in this disease. We also review the literature on the role of neutrophils in the wound healing process and how aging and neutrophil heterogeneity may impact wound healing outcomes. Finally, we discuss the potential for neutrophil-targeted therapies to improve clinical outcomes in COVID-19 and wound healing.

The double-edged role of neutrophil heterogeneity in inflammatory diseases and cancers

Neutrophils are important immune cells act as the body's first line of defense against infection and respond to diverse inflammatory cues. Many studies have demonstrated that neutrophils display plasticity in inflammatory diseases and cancers. Clarifying the role of neutrophil heterogeneity in inflammatory diseases and cancers will contribute to the development of novel treatment strategies. In this review, we have presented a review on the development of the understanding on neutrophil heterogeneity from the traditional perspective and a high-resolution viewpoint. A growing body of evidence has confirmed the double-edged role of neutrophils in inflammatory diseases and tumors. This may be due to a lack of precise understanding of the role of specific neutrophil subsets in the disease. Thus, elucidating specific neutrophil subsets involved in diseases would benefit the development of precision medicine. Thusly, we have summarized the relevance and actions of neutrophil heterogeneity in inflammatory diseases and cancers comprehensively. Meanwhile, we also discussed the potential intervention strategy for neutrophils. This review is intended to deepen our understanding of neutrophil heterogeneity in inflammatory diseases and cancers, while hold promise for precise treatment of neutrophil-related diseases.

Mass Cytometry Reveals the Imbalanced Immune State in the Peripheral Blood of Patients with Essential Hypertension

Mounting evidence has confirmed that essential hypertension (EH) is closely related to low-grade inflammation, but there is still a lack of in-depth understanding of the state of immune cells in the circulating blood of patients with EH. We analyzed whether hypertensive peripheral blood immune cell balance was destroyed. The peripheral blood mononuclear cells (PBMCs) of all subjects were analyzed using time-of-flight cytometry (CyTOF) based on 42 kinds of metal-binding antibodies. CD45⁺ cells were categorized into 32 kinds of subsets. Compared with the health control (HC) group, the percentage of total dendritic cells, two kinds of myeloid dendritic cell subsets, one intermediate/nonclassical monocyte subset and one CD4⁺ central memory T cell subset in the EH group, was significantly higher; the percentage of low-density neutrophils, four kinds of classical monocyte subsets, one CD14^lowCD16^- monocyte subset, one naive CD4⁺ and one naive CD8⁺ T cell subsets, one CD4⁺ effector and one CD4⁺ central memory T cell subsets, one CD8⁺ effector memory T cell subset, and one terminally differentiated γδ T cell subset, decreased significantly in EH. What is more, the expression of many important antigens was enhanced in CD45⁺ immune cells, granulocytes, and B cells in patients with EH. In conclusion, the altered number and antigen expression of immune cells reflect the imbalanced immune state of the peripheral blood in patients with EH.

Role of the renin-angiotensin system in NETosis in the coronavirus disease 2019 (COVID-19)

Myocardial infarction and stroke are the leading causes of death in the world. Numerous evidence has confirmed that hypertension promotes thrombosis and induces myocardial infarction and stroke. Recent findings reveal that neutrophil extracellular traps (NETs) are involved in the induction of myocardial infarction and stroke. Meanwhile, patients with severe COVID-19 suffer from complications such as myocardial infarction and stroke with pathological signs of NETs. Due to the extremely low amount of virus detected in the blood and remote organs (e.g., heart, brain and kidney) in a few cases, it is difficult to explain the mechanism by which the virus triggers NETosis, and there may be a different mechanism than in the lung. A large number of studies have found that the renin-angiotensin system regulates the NETosis at multiple levels in patients with COVID-19, such as endocytosis of SARS-COV-2, abnormal angiotensin II levels, neutrophil activation and procoagulant function at multiple levels, which may contribute to the formation of reticular structure and thrombosis. The treatment of angiotensin-converting enzyme inhibitors (ACEI), angiotensin II type 1 receptor blockers (ARBs) and neutrophil recruitment and active antagonists helps to regulate blood pressure and reduce the risk of net and thrombosis. The review will explore the possible role of the angiotensin system in the formation of NETs in severe COVID-19.

Low-Density Neutrophils in Healthy Individuals Display a Mature Primed Phenotype

Neutrophils are the most abundant leukocytes in human peripheral blood, comprising about 70% of all leukocytes. They are regarded as the first line of defense of the innate immune system, but neutrophils have also the ability of regulating the adaptive immune response. Recently, However, multiple phenotypes and functional states of neutrophils have been reported, particularly in inflammation, autoimmunity, and cancer. One possible subtype of neutrophils, the so-called low-density neutrophils (LDN) is found among mononuclear cells (MNC), monocytes and lymphocytes, after separating the leukocytes from blood by density gradient centrifugation. LDN increase in numbers during several pathological conditions. However, LDN present in healthy conditions have not been investigated further. Therefore, in order to confirm the presence of LDN in blood of healthy individuals and to explore some of their cellular functions, neutrophils and MNC were isolated by density gradient centrifugation. Purified neutrophils were further characterized by multicolor flow cytometry (FACS) and then, using the same FACS parameters cells in the MNC fraction were analyzed. Within the MNC, LDN were consistently found. These LDN had a normal mature neutrophil morphology and displayed a CD10+, CD11b+, CD14low, CD15high, CD16bhigh, CD62L+, CD66b+, and CXCR4+ phenotype. These LDN had an enhanced reactive oxygen species (ROS) production and increased phagocytic capacity and were able to produce neutrophil extracellular traps (NET) similarly to neutrophils. These data confirm the presence of a small number of LDN is blood of healthy individuals and suggest that these LDN represent mature cells with a primed phenotype.