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Photodynamic therapy (PDT) has become an emerging novel therapeutic approach for treating localized microbial infections, particularly those sustained by multidrug-resistant strains. Given the irreplaceable role played by professional phagocytes in limiting infections, such as polymorphonuclear neutrophils, any newly designed antimicrobial therapeutic approach must not interfere with their function. The present investigation presents a detailed analysis of the effect of PDT on the viability and several functional responses of human polymorphonuclear neutrophils loaded with methylene blue (MB), one of the more commonly used photosensitizers in antimicrobial PDT. Taking advantage of the use of a specifically-designed optical LED array for illuminating MB-loaded human polymorphonuclear neutrophils, a number of cell functions have been assayed under miniaturized, strictly controlled and reproducible experimental conditions. The major findings of this study are the following: (1) MB-PDT increases human neutrophils adhesion and does not modify myeloperoxidase release; (2) MB-PDT markedly enhances reactive oxygen species generation that is independent of superoxide-forming phagocytic oxidase and very likely ascribable to LED-dependent excitation of accumulated methylene blue; (3) MB-PDT almost abolishes human neutrophils candidacidal activity by hindering the engulfing machinery. This in vitro study may represent a valuable reference point for future research on PDT applications for treating localized microbial infections., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Introduction: Bacillus Calmette-Guerin (BCG) is used to treat high risk superficial bladder cancer, but its anti-tumor effect remains incompletely defined. Recently a role for polymophonuclear (PMN) neutrophils has been suggested. To investigate the role of granulocytes, we monitored the activation state of these cells in the urine of BCG-treated patients., Materials and Methods: Ten patients with stage T1, grade 3 (T1G3) transitional cell carcinoma received an 8 week course of BCG after undergoing transurethral resection of the bladder. Cytological and enzymatic analyses of urine samples collected before and 2 hours after the physiological expulsion of BCG were performed. The activation state of urine granulocytes and the presence of activating factors within the urine samples were monitored., Results: BCG immunotherapy stimulated, through soluble factors, the activation of PMN neutrophils, which transmigrated into the bladder, and the degree of activation of the PMN neutrophils was related directly to the number of epithelial cells detached from the urothelial layer., Conclusions: This study suggests that PMN neutrophils can participate in reducing the recurrence of bladder cancer by promoting urothelial cell turnover proportionally to their degree of activation. Our results provide further evidence to support the role of PMN neutrophils in BCG immunotherapy.

Secretion in neutrophils is thought to be regulated in different ways for the different granule types. Specific granules are endowed with proteins which are related to docking and fusion events and are absent on azurophilic granules. Furthermore, even if secretion of content from all neutrophil granules is a Ca(2+)-dependent process, a higher concentration of cytosolic calcium is required for azurophilic than for specific granule secretion. In this paper we show that human neutrophils and promyelocitic cells express neuronal calcium sensor-1 (NCS-1), a calcium binding protein involved in exocytosis in various cell types. Both mRNA and protein were found in mature cells and precursors. NCS-1 is shown to be mainly associated with azurophilic granules and, therefore could play an instrumental role in the calcium-dependent secretion of azurophilic granules.

oxidation, we set up a method for measuring MPO intraphagosomal release in human neutrophils. The method is based on the passive engulfment of DAB together with the phagocytosable particle. Inside the vacuole, this substrate is oxidized by MPO released from the azurophilic granules. The colorimetrical evaluation of the amount of DAB oxidized allows for cheap, rapid quantification of MPO intraphagosomal secretion in whole cells. Using this method, we show that the degranulation process, involving azurophilic granules, can be monitored carefully during phagocytosis. It takes place after the ingestion of zymosan particles opsonized with normal human serum, as well as during IgG-mediated phagocytosis and under conditions where beta2 integrins are blocked. However our findings also show that the extent of intraphagosomal secretion depends on either the extent of opsonization or the type of receptor engaged during the phagocytic event.

The evidence that small GTPases of the Rab family are regulators of vesicle traffic which can influence various cell functions prompted us to investigate the potential role of one of these proteins, Rab5a, in human neutrophils. In this paper we show that a large amount of Rab5a is present in the cytosol of peripheral blood mature neutrophils. The remaining protein was found to be membrane and azurophilic granule associated. Upon neutrophil challenge with PMA for 10 min the amount of membrane-associated Rab5a was upregulated while the cytosolic content of the protein concomitantly decreased. These findings support the hypothesis that Rab5a could be involved in the mechanism of neutrophil activation by modulating the rate of endocytosis and/or vesicle fusion.

Oral Diseases (2010) 16, 365–374 Objective: A neuropathic basis has been suggested for burning mouth syndrome (BMS) and an altered concentration of neuropeptides has been reported in lingual oral mucosa and saliva in this disease. The aims of this study were to compare the levels of nerve growth factor (NGF), substance P (SP) and degranulation products from mast cells and neutrophils in the saliva of BMS subjects with those of control subjects. Material and Methods: Salivary flow rate, protein concentration, NGF peptide and mRNA, SP, mast cells tryptase, neutrophil myeloperoxidase and calprotectin were analyzed in saliva of 20 BMS subjects and of 20 age- and gender-matched healthy subjects. Results and Conclusions: NGF peptide and tryptase activity were shown to be significantly and persistently higher in saliva of BMS subjects, with respect to control values. Conversely the salivary levels of SP were shown to be significantly lower, while neutrophil markers didn’t show any change. We conclude that the neuropathic origin of the disease is confirmed at salivary level. Furthermore, the higher tryptase activity indicates a possible involvement of mast cells. The salivary neuropeptide concentration in BMS subjects, together with mast cell derived compounds, could be useful biomarkers for diagnosis and monitoring of this disease. [ABSTRACT FROM AUTHOR]