Cigarette smoke-induced necroptosis and DAMP release trigger neutrophilic airway inflammation in mice

Abstract

Recent data indicate a role for airway epithelial necroptosis, a regulated form of necrosis, and the associated release of damage-associated molecular patterns (DAMPs) in the development of chronic obstructive pulmonary disease (COPD). DAMPs can activate pattern recognition receptors (PRRs), triggering innate immune responses. We hypothesized that cigarette smoke (CS)-induced epithelial necroptosis and DAMP release initiate airway inflammation in COPD. Human bronchial epithelial BEAS-2B cells were exposed to cigarette smoke extract (CSE), and necrotic cell death (membrane integrity by propidium iodide staining) and DAMP release (i.e., double-stranded DNA, high-mobility group box 1, heat shock protein 70, mitochondrial DNA, ATP) were analyzed. Subsequently, BEAS-2B cells were exposed to DAMP-containing supernatant of CS-induced necrotic cells, and the release of proinflammatory mediators [C-X-C motif ligand 8 (CXCL-8), IL-6] was evaluated. Furthermore, mice were exposed to CS in the presence and absence of the necroptosis inhibitor necrostatin-1, and levels of DAMPs and inflammatory cell numbers were determined in bronchoalveolar lavage fluid. CSE induced a significant increase in the percentage of necrotic cells and DAMP release in BEAS-2B cells. Stimulation of BEAS-2B cells with supernatant of CS-induced necrotic cells induced a significant increase in the release of CXCL8 and IL-6, in a myeloid differentiation primary response gene 88-dependent fashion. In mice, exposure of CS increased the levels of DAMPs and numbers of neutrophils in bronchoalveolar lavage fluid, which was statistically reduced upon treatment with necrostatin-1. Together, we showed that CS exposure induces necrosis of bronchial epithelial cells and subsequent DAMP release in vitro, inducing the production of proinflammatory cytokines. In vivo, CS exposure induces neutrophilic airway inflammation that is sensitive to necroptosis inhibition.

Oral feeding with probioticLactobacillus rhamnosusattenuates cigarette smoke-induced COPD in C57Bl/6 mice: Relevance to inflammatory markers in human bronchial epithelial cells

“…Our findings corroborate previous studies showing that that CS inhalation induces a robust migration of 432 inflammatory cells to the lung environment, mainly macrophage and neutrophils [41][42][43]. In response to 435 differentiation of monocytes in lung tissue, amplifying the inflammatory process [44][45][46].…”

Necroptosis: Mechanisms and Relevance to Disease

“…In line with this notion, necroptosis or core components of the necroptotic machinery contribute to various inflammatory disorders, including Crohn disease (68); rheumatoid arthritis (52); multiple sclerosis (178); TNF-driven autoinflammatory disorders, including the so-called systemic inflammatory response syndrome (SIRS) (47, 179) and the toxicity of systemic irradiation (180); severe cutaneous reactions to drugs (181); allograft rejection (182, 183); remote lung injury postengraftment (184); cigarette smoke–driven chronic obstructive pulmonary disease (COPD) (185, 186); acute pancreatitis (12, 32, 112); and some manifestations of systemic lupus erythematosus (187). Some of these findings, however, have been obtained in mice receiving Nec-1, NSA, or Ripk1 -targeting siRNAs as sole inhibitors of necroptosis and, hence, should be taken with caution.…”

Cigarette smoke extract may induce lysosomal storage disease‐like adverse health effects

“…Accumulated evidence shows that cigarette smoke causes a wide spectrum of human disorders by affecting the immune system (defense function) of the host (Martí‐Lliteras et al, ; Pouwels et al, ; Zuo et al, ) and regulating lung disease pathogenesis (Ryter & Choi, ; Ryter, Ma, & Choi, ). For example, CSE increased the surface expression of adhesion molecules such as ICAM‐1 and E‐selectin, together with DNA damage.…”