The chronic inflammatory component of asthma is propagated by granulocytes, including neutrophils and eosinophils, in the peripheral circulation and airway. Previous studies have suggested that these cells have an altered expression of adhesion-related molecules and a propensity for the release of granule contents that may contribute to tissue damage and enhance inflammatory complications in patients with status asthmaticus. The goal of this prospective cohort study at a tertiary care pediatric hospital with a large population of asthma patients was to assess the role of granulocyte-based inflammation in the development of asthma exacerbation. Subjects were enrolled from two patient populations: those with mild-to-moderate asthma exacerbations seen in the emergency department and those with severe asthma admitted to the intensive care unit (PICU). Clinical data were collected, and blood was drawn. Granulocytes were immediately purified, and the phenotype was assessed, including the expression of cell surface markers, elastase release, and cytokine production. Severe asthmatics admitted to the PICU displayed a significantly higher total neutrophil count when compared with healthy donors. Moreover, little to no eosinophils were found in granulocyte preparations from severe asthmatics. Circulating neutrophils from severe asthmatics admitted to the PICU displayed significantly increased elastase release ex vivo when compared with the PMN from healthy donors. These data suggest that the neutrophil-based activation and release of inflammatory products displayed by severe asthmatics may contribute to the propagation of asthma exacerbations.

Some extracellular glycoconjugates have sialic acid as the terminal sugar, and sialidases are enzymes that remove this sugar. Mammals have 4 sialidases and can be elevated in inflammation and fibrosis. In this report, we show that incubation of human neutrophils with the extracellular human sialidase NEU3, but not NEU1, NEU2 or NEU4, induces human male and female neutrophils to change from a round to a more amoeboid morphology, causes the primed human neutrophil markers CD11b, CD18, and CD66a to localize to the cell cortex, and decreases the localization of the unprimed human neutrophil markers CD43 and CD62-L at the cell cortex. NEU3, but not the other 3 sialidases, also causes human male and female neutrophils to increase their F-actin content. Human neutrophils treated with NEU3 show a decrease in cortical levels of Sambucus nigra lectin staining and an increase in cortical levels of peanut agglutinin staining, indicating a NEU3-induced desialylation. The inhibition of NEU3 by the NEU3 inhibitor 2-acetylpyridine attenuated the NEU3 effect on neutrophil morphology, indicating that the effect of NEU3 is dependent on its enzymatic activity. Together, these results indicate that NEU3 can prime human male and female neutrophils, and that NEU3 is a potential regulator of inflammation.
©2022 Society for Leukocyte Biology.

Some extracellular glycoconjugates have sialic acid as the terminal sugar, and sialidases are enzymes that remove this sugar. Mammals have four sialidases, but their biological functions are unclear. In this report, we show that incubation of human neutrophils with the human sialidase NEU3, but not NEU1, NEU2 or NEU4, inducess human male and female neutrophils to change from a round to a more amoeboid morphology, causes the primed neutrophil markers CD66, CD11B, and CD18 to localize to the cell cortex, and decreases the localization of the unprimed neutrophil markers CD43 and CD62L at the cell cortex. NEU3, but not the other 3 sialidases, also causes human male and female neutrophils to increase their F-actin content. The inhibition of NEU3 by the NEU3 inhibitor 2-acetylpyridine attenuated the NEU3 effect on neutrophil morphology, indicating that the effect of NEU3 is dependent on its enzymatic activity. Together, these results indicate that NEU3 can prime human male and female neutrophils, and that NEU3 is a potential regulator of inflammation.

Renal endothelial cells (ECs) play crucial roles in vasorelaxation, ultrafiltration, and selective transport of electrolytes and water, but also in leakage of the glomerular filtration barrier and inflammatory processes like complement activation and leukocyte recruitment. In addition, they are target cells for both cellular and antibody-mediated rejection in the transplanted kidney. To study the molecular and cellular processes underlying EC behavior in renal disease, well-characterized primary renal ECs are indispensible. In this report, we describe a straightforward procedure to isolate ECs from the perfusion fluid of human donor kidneys by a combination of negative selection of monocytes/macrophages, positive selection by CD31 Dynabeads, and propagation in endothelium-specific culture medium. Thus, we isolated and propagated renal ECs from 102 donor kidneys, representative of all blood groups and major human leukocyte antigen (HLA) class I and II antigens. The obtained ECs were positive for CD31 and von Willebrand factor, expressed other endothelial markers such as CD34, VEGF receptor-2, TIE2, and plasmalemmal vesicle associated protein-1 to a variable extent, and were negative for the monocyte marker CD14 and lymphatic endothelial marker podoplanin. HLA class II was either constitutively expressed or could be induced by interferon-γ. Furthermore, as a proof of principle, we showed the diagnostic value of this renal endothelial biobank in renal endothelium-specific cross-matching tests for HLA antibodies.NEW & NOTEWORTHY We describe a new and widely accessible approach to obtain human primary renal endothelial cells in a standardized fashion, by isolating from the perfusate of machine-perfused donor kidneys. Characterization of the cells showed a mixed population originating from different compartments of the kidney. As a proof of principle, we demonstrated a possible diagnostic application in an endothelium-specific cross-match. Next to transplantation, we foresee further applications in the field renal endothelial research.

Triggering receptor expressed on myeloid cells 1 (TREM-1) is a receptor mainly expressed on myeloid cells, and it plays an important role in modulating immune response against infectious agents. The function of TREM-1 on nonmyeloid cells such as Vδ2 T cells has not been characterized, and their role in pulmonary tuberculosis (TB) remains unclear. To assess the expression of TREM-1 on blood Vδ2 T cells from pulmonary TB patients and investigate its mechanism of induction, we exploited flow cytometry analysis to study the expression of TREM-1 on Vδ2 T cells from active pulmonary TB patients and control subjects. In this study we demonstrate that TREM-1 (TREM-1+) is highly expressed on Vδ2 T cells of patients with active pulmonary TB. Unlike TREM-1--expressing Vδ2 T cells, TREM-1+-producing Vδ2 T cells display APC-like phenotypes. Surprisingly, TREM-1+ signaling promotes the Ag-presenting capability of Vδ2 T cells to induce the CD4+ T cell response. TREM-1+Vδ2 T cells induced the proliferation and differentiation of naive CD4+ T cells, as well as the elimination of intracellular mycobacteria. We identified TREM-1+ (but not TREM-1-) as an Ag-presentation amplifier on human blood Vδ2 T cells, and data shed new light on the regulation of Vδ2 T cells in the phase of innate and adaptive immune responses against Mycobacterium tuberculosis infection. Targeting TREM-1+Vδ2 T cells may be a promising approach for TB therapy.
Copyright © 2018 by The American Association of Immunologists, Inc.