Dataset Information

Autophagy Mediates Interleukin-1? Secretion in Human Neutrophils.

ABSTRACT: Interleukin-1? (IL-1?), a major pro-inflammatory cytokine, is a leaderless cytosolic protein whose secretion does not follow the classical endoplasmic reticulum-to-Golgi pathway, and for which a canonical mechanism of secretion remains to be established. Neutrophils are essential players against bacterial and fungi infections. These cells are rapidly and massively recruited from the circulation into infected tissues and, beyond of displaying an impressive arsenal of toxic weapons effective to kill pathogens, are also an important source of IL-1? in infectious conditions. Here, we analyzed if an unconventional secretory autophagy mechanism is involved in the exportation of IL-1? by these cells. Our findings indicated that inhibition of autophagy with 3-methyladenine and Wortmannin markedly reduced IL-1? secretion induced by LPS?+?ATP, as did the disruption of the autophagic flux with Bafilomycin A1 and E64d. These compounds did not noticeable affect neutrophil viability ruling out that the effects on IL-1? secretion were due to cell death. Furthermore, VPS34IN-1, a specific autophagy inhibitor, was still able to reduce IL-1? secretion when added after it was synthesized. Moreover, siRNA-mediated knockdown of ATG5 markedly reduced IL-1? secretion in neutrophil-differentiated PLB985 cells. Upon LPS?+?ATP stimulation, IL-1? was incorporated to an autophagic compartment, as was revealed by its colocalization with LC3B by confocal microscopy. Overlapping of IL-1?-LC3B in a vesicular compartment peaked before IL-1? increased in culture supernatants. On the other hand, stimulation of autophagy by cell starvation augmented the colocalization of IL-1? and LC3B and then promoted neutrophil IL-1? secretion. In addition, specific ELISAs indicated that although both IL-1? and pro-IL-1? are released to culture supernatants upon neutrophil stimulation, autophagy only promotes IL-1? secretion. Furthermore, the serine proteases inhibitor AEBSF reduced IL-1? secretion. Moreover, IL-1? could be also found colocalizing with elastase, suggesting both some vesicles containing IL-1? intersect azurophil granules content and that serine proteases also regulate IL-1? secretion. Altogether, our findings indicate that an unconventional autophagy-mediated secretory pathway mediates IL-1? secretion in human neutrophils.

SUBMITTER: Iula L

PROVIDER: S-EPMC5825906 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Autophagy Mediates Interleukin-1β Secretion in Human Neutrophils.

Iula Leonardo L Keitelman Irene A IA Sabbione Florencia F Fuentes Federico F Guzman Mauricio M Galletti Jeremías Gastón JG Gerber Pehuén Pereyra PP Ostrowski Matías M Geffner Jorge R JR Jancic Carolina C CC Trevani Analía S AS

Frontiers in immunology 20180219

Interleukin-1β (IL-1β), a major pro-inflammatory cytokine, is a leaderless cytosolic protein whose secretion does not follow the classical endoplasmic reticulum-to-Golgi pathway, and for which a canonical mechanism of secretion remains to be established. Neutrophils are essential players against bacterial and fungi infections. These cells are rapidly and massively recruited from the circulation into infected tissues and, beyond of displaying an impressive arsenal of toxic weapons effective to ki ...[more]

PMID: 29515581

Similar Datasets

Project description:Adipose tissue expansion during obesity is associated with increased macrophage infiltration. Macrophage-derived factors significantly alter adipocyte function, inducing inflammatory responses and decreasing insulin sensitivity. Identification of the major factors that mediate detrimental effects of macrophages on adipocytes may offer potential therapeutic targets. IL-1β, a proinflammatory cytokine, is suggested to be involved in the development of insulin resistance. This study investigated the role of IL-1β in macrophage-adipocyte cross-talk, which affects insulin signaling in human adipocytes. Using macrophage-conditioned (MC) medium and human primary adipocytes, we examined the effect of IL-1β antagonism on the insulin signaling pathway. Gene expression profile and protein abundance of insulin signaling molecules were determined, as was the production of proinflammatory cytokine/chemokines. We also examined whether IL-1β mediates MC medium-induced alteration in adipocyte lipid storage. MC medium and IL-1β significantly reduced gene expression and protein abundance of insulin signaling molecules, including insulin receptor substrate-1, phosphoinositide 3-kinase p85α, and glucose transporter 4 and phosphorylation of Akt. In contrast, the expression and release of the proinflammatory markers, including IL-6, IL-8, monocyte chemotactic protein-1, and chemokine (C-C motif) ligand 5 by adipocytes were markedly increased. These changes were significantly reduced by blocking IL-1β activity, its receptor binding, or its production by macrophages. MC medium-inhibited expression of the adipogenic factors and -stimulated lipolysis was also blunted with IL-1β neutralization. We conclude that IL-1β mediates, at least in part, the effect of macrophages on insulin signaling and proinflammatory response in human adipocytes. Blocking IL-1β could be beneficial for preventing obesity-associated insulin resistance and inflammation in human adipose tissue.

Project description:Dental calculus is a mineralized deposit associated with periodontitis. The bacterial components contained in dental calculus can be recognized by host immune sensors, such as Toll-like receptors (TLRs), and induce transcription of proinflammatory cytokines, such as IL-1β. Studies have shown that cellular uptake of crystalline particles may trigger NLRP3 inflammasome activation, leading to the cleavage of the IL-1β precursor to its mature form. Phagocytosis of dental calculus in the periodontal pocket may therefore lead to the secretion of IL-1β, promoting inflammatory responses in periodontal tissues. However, the capacity of dental calculus to induce IL-1β secretion in human phagocytes has not been explored. To study this, we stimulated human polymorphonuclear leukocytes (PMNs) and peripheral blood mononuclear cells (PBMCs) with dental calculus collected from periodontitis patients, and measured IL-1β secretion by ELISA. We found that calculus induced IL-1β secretion in both human PMNs and PBMCs. Calculus also induced IL-1β in macrophages from wild-type mice, but not in macrophages from NLRP3- and ASC-deficient mice, indicating the involvement of NLRP3 and ASC. IL-1β induction was inhibited by polymyxin B, suggesting that LPS is one of the components of calculus that induces pro-IL-1β transcription. To analyze the effect of the inorganic structure, we baked calculus at 250°C for 1 h. This baked calculus failed to induce pro-IL-1β transcription. However, it did induce IL-1β secretion in lipid A-primed cells, indicating that the crystalline structure of calculus induces inflammasome activation. Furthermore, hydroxyapatite crystals, a component of dental calculus, induced IL-1β in mouse macrophages, and baked calculus induced IL-1β in lipid A-primed human PMNs and PBMCs. These results indicate that dental calculus stimulates IL-1β secretion via NLRP3 inflammasome in human and mouse phagocytes, and that the crystalline structure has a partial role in the activation of NLRP3 inflammasome.

Dataset Information

Autophagy Mediates Interleukin-1? Secretion in Human Neutrophils.

Publications

Autophagy Mediates Interleukin-1β Secretion in Human Neutrophils.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets