SARS-CoV-2 spike protein induces inflammation via TLR2-dependent activation of the NF-kB pathway

The pathogenesis of COVID-19 is associated with a hyperinflammatory response; however, the precise mechanism of SARS-CoV-2-induced inflammation is poorly understood. Here we investigated direct inflammatory functions of major structural proteins of SARS-CoV-2. We observed that spike (S) protein potently induced inflammatory cytokines and chemokines including IL-6, IL-1b, TNFa, CXCL1, CXCL2, and CCL2, but not IFNs in human and mouse macrophages. No such inflammatory response was observed in response to membrane (M), envelope (E), and nucleocapsid (N) proteins. When stimulated with extracellular S protein, human and mouse lung epithelial cells also produced inflammatory cytokines and chemokines. Interestingly, epithelial cells expressing S protein intracellularly were non-inflammatory, but elicited an inflammatory response in macrophages when co-cultured. Biochemical studies revealed that S protein triggers inflammation via activation of the NF-kB pathway in a MyD88-dependent manner. Further, such an activation of the NF-kB pathway was abrogated in Tlr2-deficient macrophages. Consistently, administration of S protein induced IL-6, TNF-a, and IL-1b in wild-type, but not Tlr2-deficient mice. Notably, upon recognition of S protein, TLR2 dimerizes with TLR1 or TLR6 to activate the NF-kB pathway. Together these data reveal a mechanism for the cytokine storm during SARS-CoV-2 infection and suggest that TLR2 could be a potential therapeutic target for COVID-19.

Download Full-text

SARS-CoV-2 spike protein induces inflammation via TLR2-dependent activation of the NF-κB pathway

10.1101/2021.03.16.435700 ◽

2021 ◽

Author(s):

Shahanshah Khan ◽

Mahnoush S. Shafiei ◽

Christopher Longoria ◽

John Schoggins ◽

Rashmin C. Savani ◽

...

Keyword(s):

Epithelial Cells ◽

Inflammatory Response ◽

Inflammatory Cytokines ◽

Lung Epithelial Cells ◽

Dependent Manner ◽

S Protein ◽

Cytokines And Chemokines ◽

Lung Epithelial ◽

Mouse Macrophages ◽

Human And Mouse

Pathogenesis of COVID-19 is associated with a hyperinflammatory response; however, the precise mechanism of SARS-CoV-2-induced inflammation is poorly understood. Here we investigated direct inflammatory functions of major structural proteins of SARS-CoV-2. We observed that spike (S) protein potently induces inflammatory cytokines and chemokines including IL-6, IL-1b, TNFa, CXCL1, CXCL2, and CCL2, but not IFNs in human and mouse macrophages. No such inflammatory response was observed in response to membrane (M), envelope (E), and neucleocapsid (N) proteins. When stimulated with extracellular S protein, human lung epithelial cells A549 also produce inflammatory cytokines and chemokines. Interestingly, epithelial cells expressing S protein intracellularly are non-inflammatory, but elicit an inflammatory response in macrophages when co-cultured. Biochemical studies revealed that S protein triggers inflammation via activation of the NF-kB pathway in a MyD88-dependent manner. Further, such an activation of the NF-kB pathway is abrogated in Tlr2-deficient macrophages. Consistently, administration of S protein induces IL-6, TNF-a, and IL-1b in wild-type, but not Tlr2-deficient mice. Together these data reveal a mechanism for the cytokine storm during SARS-CoV-2 infection and suggest that TLR2 could be a potential therapeutic target for COVID-19.

Download Full-text

Intestinal Bacteroides Modulates Systemic Inflammation and the Microbial Ecology in a Mouse Model of CF: Evidence for Propionate and other Short Chain Fatty Acids Reducing Systemic Inflammatory Cytokines

10.1101/2022.01.05.475125 ◽

2022 ◽

Author(s):

Courtney Price ◽

Rebecca Valls ◽

Alexis Ramsey ◽

Nicole Loeven ◽

Jane Jones ◽

...

Keyword(s):

Epithelial Cells ◽

Inflammatory Response ◽

Inflammatory Cytokines ◽

Relative Abundance ◽

Intestinal Epithelial Cells ◽

Short Chain Fatty Acids ◽

Short Chain ◽

Intestinal Microbiome ◽

Dependent Manner ◽

Intestinal Epithelial

Persons with cystic fibrosis, starting in early life, have intestinal microbiome dysbiosis characterized in part by a decreased relative abundance of the genus Bacteroides. Bacteroides is a major producer of the intestinal short chain fatty acid (SCFA) propionate. We demonstrate here that CFTR-/- Caco-2 intestinal epithelial cells are responsive to the anti-inflammatory effects of propionate. Furthermore, Bacteroides isolates inhibit the IL-1β-induced inflammatory response of CFTR-/- Caco-2 intestinal epithelial cells and do so in a propionate-dependent manner. Bacteroides isolates also produce low levels of butyrate; this SCFA is positively correlated with inhibition of the inflammatory response. Finally, the introduction of Bacteroides-supplemented stool from infants with CF into the gut of CftrF508del mice results in an increase in propionate in the stool as well as the reduction in several systemic pro-inflammatory cytokines. Bacteroides supplementation also reduced the fecal relative abundance of E. coli, indicating a potential interaction between these two microbes, consistent with previous clinical studies. Together, our data indicate the important role of Bacteroides and Bacteroides-derived propionate in the context of the developing microbiome in infants and children with CF, which could help explain the observed gut-lung axis in CF.

Download Full-text

Vapors Produced by Electronic Cigarettes and E-Juices with Flavorings Induce Toxicity, Oxidative Stress, and Inflammatory Response in Lung Epithelial Cells and in Mouse Lung

PLoS ONE ◽

10.1371/journal.pone.0116732 ◽

2015 ◽

Vol 10 (2) ◽

pp. e0116732 ◽

Cited By ~ 289

Author(s):

Chad A. Lerner ◽

Isaac K. Sundar ◽

Hongwei Yao ◽

Janice Gerloff ◽

Deborah J. Ossip ◽

...

Keyword(s):

Oxidative Stress ◽

Epithelial Cells ◽

Inflammatory Response ◽

Electronic Cigarettes ◽

Lung Epithelial Cells ◽

Mouse Lung ◽

Lung Epithelial

Download Full-text

Inflammatory response of tracheobronchial epithelial cells to endotoxin

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00391.2004 ◽

2006 ◽

Vol 290 (1) ◽

pp. L86-L96 ◽

Cited By ~ 19

Author(s):

Simona B. Neff ◽

Birgit Roth Z'graggen ◽

Thomas A. Neff ◽

Marina Jamnicki-Abegg ◽

Dominik Suter ◽

...

Keyword(s):

Epithelial Cell ◽

Epithelial Cells ◽

Lung Injury ◽

Inflammatory Response ◽

Adhesion Molecule ◽

Cell Damage ◽

Intercellular Adhesion Molecule ◽

Dependent Manner ◽

Intercellular Adhesion Molecule 1 ◽

Cytokines And Chemokines

Respiratory epithelial cells play a crucial role in the inflammatory response in endotoxin-induced lung injury, an experimental model for acute lung injury. To determine the role of epithelial cells in the upper respiratory compartment in the inflammatory response to endotoxin, we exposed tracheobronchial epithelial cells (TBEC) to lipopolysaccharide (LPS). Expression of inflammatory mediators was analyzed, and the biological implications were assessed using chemotaxis and adherence assays. Epithelial cell necrosis and apoptosis were determined to identify LPS-induced cell damage. Treatment of TBEC with LPS induced enhanced protein expression of cytokines and chemokines (increases of 235–654%, P < 0.05), with increased chemotactic activity regarding neutrophil recruitment. Expression of the intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was enhanced by 52–101% ( P < 0.0001). This upregulation led to increased adhesion of neutrophils, with >95% adherence to TBEC after LPS stimulation, which could be blocked by either ICAM-1 (69%) or VCAM-1 antibodies (55%) ( P < 0.05). Enhanced neutrophil-induced necrosis of TBEC was observed when TBEC were exposed to LPS. Reduced neutrophil adherence by ICAM-1 or VCAM-1 antibodies resulted in significantly lower TBEC death (52 and 34%, respectively, P < 0.05). Therefore, tight adherence of neutrophils to TBEC appears to promote epithelial cell killing. In addition to indirect effector cell-induced TBEC death, direct LPS-induced cell damage was seen with increased apoptosis rate in LPS-stimulated TBEC (36% increase of caspase-3, P < 0.01). These data provide evidence that LPS induces TBEC killing in a necrosis- and apoptosis-dependent manner.

Download Full-text

DRP1-Mediated Mitochondrial Fission Regulates the Lung Epithelial Response to Allergen

10.21203/rs.3.rs-654294/v1 ◽

2021 ◽

Author(s):

Sierra Bruno ◽

Amit Kumar ◽

Zoe Mark ◽

Ravishankar Chandrasekaran ◽

Emily Nakada ◽

...

Keyword(s):

Epithelial Cell ◽

Epithelial Cells ◽

Inflammatory Response ◽

Mitochondrial Fission ◽

Airway Epithelial Cells ◽

Lung Epithelial Cells ◽

Airway Epithelial ◽

Cytokines And Chemokines ◽

Lung Epithelial ◽

Pro Inflammatory Cytokines

Abstract Background: Mitochondria regulate a myriad of cellular needs and functions. Dysregulation of mitochondrial control within airway epithelial cells has been implicated in the pro-inflammatory response to allergens in asthmatics. Because of their multifaceted nature, mitochondrial structure needs to be tightly regulated through fission and fusion. Dynamin Related Protein 1 (DRP1), a cytosolic GTPase, is a key driver of mitochondrial fission. During allergic asthma, airway epithelial mitochondria appear smaller and structurally altered. The role of DRP1-mediated mitochondrial fission, however, has not been fully elucidated in allergic airway disease. Methods: We used a Human Bronchial Epithelial Cell line (HBECs), primary Mouse Tracheal Epithelial Cells (MTECs), and conditional ablation of DRP1 in lung epithelial cells to investigate mitochondrial fission and its impact on the pro-inflammatory response to House Dust Mite (HDM) in vitro and in vivo. Results: Our data suggest that, following HDM challenge, mitochondrial fission is rapidly upregulated in airway epithelial cells and precedes production of pro-inflammatory cytokines and chemokines. Further, deletion of DRP1 in lung epithelial cells lead to decreased mitochondrial fission and enhanced pro-inflammatory signaling in response to HDM. Analysis of lung epithelial specific DRP1 deletion in mice demonstrated enhanced Airway Hyper Responsiveness (AHR), inflammation, differential mucin transcription, and epithelial cell death. Conclusions: Mitochondrial fission is rapidly upregulated in airway epithelial cells following HDM exposure, prior to epithelial release of pro-inflammatory cytokines and chemokines. Deletion of DRP1, a necessary pro- fission protein, reduces fission and enhances the pro-inflammatory epithelial response to HDM, exacerbating the allergic response.

Download Full-text

Ubiquitin-Specific Protease 14 (USP14) Aggravates Inflammatory Response and Apoptosis of Lung Epithelial Cells in Pneumonia by Modulating Poly (ADP-Ribose) Polymerase-1 (PARP-1)

Inflammation ◽

10.1007/s10753-021-01482-3 ◽

2021 ◽

Author(s):

Chengcheng Huang ◽

Hui Cao ◽

Jie Qin ◽

Lei Xu ◽

Fang Hu ◽

...

Keyword(s):

Epithelial Cells ◽

Inflammatory Response ◽

Lung Epithelial Cells ◽

Lung Epithelial ◽

Specific Protease ◽

Ubiquitin Specific Protease ◽

Parp 1

Download Full-text

Effect of Slit/Robo signaling on regeneration in lung emphysema

Experimental & Molecular Medicine ◽

10.1038/s12276-021-00633-8 ◽

2021 ◽

Author(s):

Jin-Soo Park ◽

RyeonJin Cho ◽

Eun-Young Kang ◽

Yeon-Mok Oh

Keyword(s):

Epithelial Cells ◽

Mouse Model ◽

Lung Epithelial Cells ◽

Mouse Lung ◽

Chronic Obstructive ◽

Irreversible Damage ◽

Lung Epithelial ◽

And Migration ◽

Proliferation And Migration

AbstractEmphysema, a pathological component of chronic obstructive pulmonary disease, causes irreversible damage to the lung. Previous studies have shown that Slit plays essential roles in cell proliferation, angiogenesis, and organ development. In this study, we evaluated the effect of Slit2 on the proliferation and migration of mouse lung epithelial cells and its role in regeneration in an emphysema lung mouse model. Here, we have shown that Slit2/Robo signaling contributes to the regeneration of lungs damaged by emphysema. Mouse epithelial lung cells treated with Slit2 exhibited increased proliferation and migration in vitro. Our results also showed that Slit2 administration improved alveolar regeneration in the emphysema mouse model in vivo. Furthermore, Slit2/Robo signaling increased the phosphorylation of ERK and Akt, which was mediated by Ras activity. These Slit2-mediated cellular signaling processes may be involved in the proliferation and migration of mouse lung epithelial cells and are also associated with the potential mechanism of lung regeneration. Our findings suggest that Slit2 administration may be beneficial for alveolar regeneration in lungs damaged by emphysema.

Download Full-text