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Enzyme-Releasing Peptide
Published in Jason Kelley, Cytokines of the Lung, 2022
Allen B. Cohen, Edmund J. Miller, Cassandra MacArthur
Neutrophils contain different kinds of granules or packets of enzymes that are released to the extracellular milieu when the granules are extruded (degranulated). Each type of granule contains different enzymes, and each is released by separate kinds of stimuli. Some of the granules are easy to release, and the release of others is difficult. One type of granule, the specific granule, contains receptors on the granule membrane. When the specific granule constituents are extruded, the granule’s membranes become part of the plasma membrane and the receptors become accessible to their agonists or up-regulated. Azurophilic granules are more difficult to release and contain elastase, myeloperoxidase, and other proteinases and hydrolases.
Constitutive Host Resistance
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
The granules of the neutrophil and eosinophil contain enzymes, whereas those within the basophil contain biologically active amines. The enzymes in the neutrophilic granules are important for the destruction and digestion of microorganisms and other foreign organic materials (Table 3.1). The granules are classified into two types: the primary or azurophilic granules, and the secondary, or specific, granules. The terms primary and secondary refer to the color or appearance of the granules during differentiation rather than to the importance of the granules. The azurophilic granules contain peroxidase, myeloperoxidase, acid hydrolases, neutral proteases, cationic antimicrobial proteins, and lysozyme. The neutral proteases include elastase, collagenase, and cathepsin G. Enzymes released by neutrophils will activate complement and generate kinins (see chapter 4); the enzymes therefore enhance vascular permeability and chemotaxis indirectly. The specific granules contain lactoferrin and lysozyme.
Eosinophils in Airway Hyperresponsiveness
Published in Devendra K. Agrawal, Robert G. Townley, Inflammatory Cells and Mediators in Bronchial Asthma, 2020
Sohei Makino, Takeshi Fukuda, Shinji Motojima, Tatsuo Yukawa
The most distinguishing morphological feature of the eosinophil is the cytoplasmic granule termed “specific granule”. These are stained a yellow-pink color by acid dyes such as eosin. These membrane-bound granules consist of an electron-dense crystalloid core with an electron-lucent matrix surrounding it.
Molecular aspects of the altered Angiotensin II signaling in Gitelman’s syndrome
Published in Expert Opinion on Orphan Drugs, 2022
Verdiana Ravarotto, Giovanni Bertoldi, Lucia Federica Stefanelli, Laura Gobbi, Lorenzo A. Calò
NOXs are the main oxidative stress inducers through the catalytic production of superoxide from oxygen and NAD(P)H [68]. NOXs are characterized by a catalytic subunit and a little p22phox subunit which binds to the complex in a highly regulated process that involves specific post-translational modifications of these subunits, resulting in the formation of the heterodimeric cytochrome b558. The association between p22phox and NOX induces a phosphorylation cascade of different cytosolic subunits and conformational changes in both the enzyme and the cellular membrane, activating the complex [68,69]. NOXs reduce the oxygen using NADPH as an electron donor triggering a radical species cascade. Physiologically, this process occurs after the phagocytic fusion of the membranes of secretory vesicles and specific granules with the cellular plasma membrane as a defense measure against external pathogens [70,71]. Once the phagosome is formed, a lethal chemical environment is generated for the exogenous microorganisms [72]. In these processes, the role of the p22phox subunit is critical for the generation of radicals, thus rendering this protein a specific biomarker for the assessment of oxidative stress status [73,74].
Blood eosinophils in COPD: friend or foe?
Published in Expert Review of Respiratory Medicine, 2022
Anastasia Papaporfyriou, Petros Bakakos, Georgios Hillas, Andriana I. Papaioannou, Stelios Loukides
Eosinophils are end-stage granulocytes that act as immune-effector and inflammatory cells, which are usually present in small numbers in the blood and tissues of healthy individuals [8]. The pluripotent CD34+ granulocyte progenitor hematopoietic cells in the bone marrow differentiate into eosinophils influenced by the cytokine interleukin 5 (IL-5) and through the induction of expression of the IL-5 receptor, a subunit on the progenitor cells [9]. Eosinophils are unique and differ from other granulocytes due to the presence of large specific granules, known as secondary granules that comprise a dense crystalline core and a matrix, surrounded by a membrane and contain a large number of mediators (basic proteins, cytokines, chemokines, growth factors, and enzymes), which could induce inflammation and tissue damage [10,11].
Role of Mac-1 integrin in generation of extracellular vesicles with antibacterial capacity from neutrophilic granulocytes
Published in Journal of Extracellular Vesicles, 2020
Ákos M. Lőrincz, Balázs Bartos, Dávid Szombath, Viktória Szeifert, Csaba I. Timár, Lilla Turiák, László Drahos, Ágnes Kittel, Dániel S. Veres, Ferenc Kolonics, Attila Mócsai, Erzsébet Ligeti
Next we asked the question whether stimulation of the different receptors only determined the number and function of produced EVs or they also affect cargo sorting into the released vesicles. With this goal in mind, we investigated the protein composition of the separated EV populations by proteomic analysis. We could identify a total of 206 proteins with 1% FDR. The label-free quantitative investigation indicated that the largest fraction of the protein content originated from granules of neutrophils, whereby azurophilic and specific granules were more abundantly represented than gelatinase granules or secretory vesicles (Figure 4(a)). The non-granule fraction of proteins consisted of cytoskeletal elements, cytosolic and mitochondrial proteins (Supplementary Table 1).