Overall, these authors reported that, even though eosinophils accumulate in adipose tissue of obese BALB/c mice, they display homeostatic functions as proposed for the lean adipose tissue (18). including TNF, CCL5 (RANTES), and PGD2. Thus, mice were pre-treated with a mast cell degranulating agent compound 48/80 which was capable to impair leptin-induced PGD2 release, as well as eosinophil recruitment and activation. In agreement with an indirect mast cell-driven trend, eosinophil build up induced by leptin was abolished in TNFR-1 deficient and also in HQL-79Cpretreated mice, but not in mice pretreated with neutralizing antibodies against CCL5, indicating that both standard mast cell-driven signals TNF and PGD2, but not CCL5, contribute to leptin-induced eosinophil influx. Distinctly, leptin-induced eosinophil lipid body (lipid droplet) assembly and LTC4 synthesis appears to depend on both PGD2 and CCL5, since both HQL-79 and anti-CCL5 treatments were able to inhibit these eosinophil activation markers. Completely, our data display that leptin causes eosinophilic swelling an indirect mechanism dependent on activation of resident mast cell secretory activity and mediation by TNF, CCL5, and specially PGD2. leptin on triggering eosinophil recruitment and activation are still missing, despite the fact that some reports show that leptin may regulate eosinophils in low- high-fat diet programs mouse models of obesity (17, 18). Several studies within the cellular mechanisms governing allergy-driven inflammatory diseases have established mast cells as canonical orchestrators of eosinophilic swelling (19, 20). Ubiquitously distributed in cells and preferentially localized in close proximity to vascular vessels, mast cells are strategically localized and ready to coordinate eosinophil recruitment and activation Duocarmycin A under specific activation. Among mast cell repertoire of molecules responsible for eliciting both Duocarmycin A eosinophil migration to sites of allergic reaction and activation of infiltrating eosinophils, important examples are the cytokines IL-5 and eotaxin (19, 20), as well as synthesized lipid mediators notably PGD2 (21). Furthermore, mast cells do communicate bioactive leptin receptors (22), whose activation is able to result in activation of mast cells secretory activities (23). More importantly, mast cells are able to intermediate leptin effects in actually non-conventional mast cell-regulated physiological conditions, like for instance leptin-induced modified sympathetic activity (24), diarrhea-predominant irritable bowel syndrome (25) or coronary atherosclerosis (26). Consequently, it seems sensible to hypothesize that activation of leptin receptor in mast cells would be capable to elicit one of the greatest archetypal functions of mast cellsthe induction of eosinophilic reactions. Our study aims to investigate the ability of leptin to Rabbit polyclonal to ACSM4 result in eosinophilic swelling, characterized by cell migration and cellular activation. Without any disregard to potential direct effects of exogenous leptin on eosinophils studies, including one of ours (16)here, efforts were focused on characterizing indirect mast cell-driven effects of leptin on triggering eosinophilic response activation to result in eosinophil inflammatory response were performed: (i) intraperitoneal (i.p.) administration of murine leptin (0.5, 1, or 2?mg/kg; Peprotech) or its vehicle (sterile LPS-free saline) in naive mice of C57BL/6 background (as indicated) (8); or (ii) intrapleural (i.pl.) injection of leptin (0.5, 1, Duocarmycin A or 2?mg/kg) Duocarmycin A or its vehicle (sterile LPS-free saline) in na?ve or in previously sensitized BALB/cBALB/c mice (while indicated). As previously explained (28), mice were sensitized having a subcutaneous (s.c.) injection (0.2?ml) of ovalbumin (OVA; 50 g; Sigma-Aldrich) and Al(OH)3?(5 mg) in 0.9% NaCl solution (sterile saline) at days 1 and 7. Animals were euthanized 6 or 24?h after leptin administration. Peritoneal and pleural cavities were rinsed with 3?and 0.5?ml of HBSS (Hanks balanced salted remedy), respectively. Total leukocyte count was performed in Neubauer chambers and differential eosinophil count in May-Grunwald-Giemsa stained cytospin slides inside a blinded fashion. Treatments to study the involvement of mTOR pathway in leptin-elicited eosinophil influx, C57BL/6 mice received three i.p. injections of rapamycin (12.5?g/kg; Sigma-Aldrich), 12?h and 15?min before, and 12?h after leptin or saline challenge (8), followed by the peritoneal lavage at 24?h after challenge. For dedication of CCL5 and PGD2 potential part in leptin-induced eosinophilic swelling, sensitized BALB/cBALB/c mice were treated, respectively, either by means of i.pl. injection of neutralizing antibody anti-CCL5 (10 g/cavity; Peprotech) or i.p. injection of selective inhibitor of PGD synthase HQL-79 (1 mg/kg; Cayman Chemicals), both 1?h before leptin injection. To investigate the participation of resident mast cells on leptin-induced eosinophilic reaction, sensitized BALB/cBALB/c mice were treated by means of local (i.pl.) injection of mast cell degranulating agent compound 48/80 (12 g/cavity; Sigma-Aldrich) 72?h before leptin i.pl. administration (29). The effectiveness of a selective impact on resident mast cell human population was ascertained by absence of toluidine blue-stained cells in pleural lavage with no changes in other.
Overall, these authors reported that, even though eosinophils accumulate in adipose tissue of obese BALB/c mice, they display homeostatic functions as proposed for the lean adipose tissue (18)
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