TNF induces the expression of the sialyltransferase ST3Gal IV in human bronchial mucosa via MSK1/2 protein kinases and increases FliD/sialyl-Lewisx-mediated adhesion of Pseudomonas aeruginosa

Abstract

We have shown previously that the pro-inflammatory cytokine TNF (tumour necrosis factor) could drive sLe(x) (sialyl-Lewis(x)) biosynthesis through the up-regulation of the BX transcript isoform of the ST3GAL4 (ST3 β-galactoside α-2,3-sialyltransferase 4) sialyltransferase gene in lung epithelial cells and human bronchial mucosa. In the present study, we show that the TNF-induced up-regulation of the ST3GAL4 BX transcript is mediated by MSK1/2 (mitogen- and stress-activated kinase 1/2) through the ERK (extracellular-signal-regulated kinase) and p38 MAPK (mitogen-activated protein kinase) pathways, and increases sLe(x) expression on high-molecular-mass glycoproteins in inflamed airway epithelium. We also show that the TNF-induced sLe(x) expression increases the adhesion of the Pseudomonas aeruginosa PAO1 and PAK strains to lung epithelial cells in a FliD-dependent manner. These results suggest that ERK and p38 MAPK, and the downstream kinase MSK1/2, should be considered as potential targets to hamper inflammation, bronchial mucin glycosylation changes and P. aeruginosa binding in the lung of patients suffering from lung diseases such as chronic bronchitis or cystic fibrosis.

The Interaction between Respiratory Pathogens and Mucus

“…The sialylation of MUC1 affects PA adhesion by reducing the accessibility of β-D-galactose sites on MUC1, which are necessary for PA adhesion via flagellin (Lillehoj et al, 2012; Pastoriza Gallego and Hulen, 2006). Sialyl-Lewis x moieties on mucins in particular appear to be preferential binding sites for PA via flagellin (Colomb et al, 2014; Scharfman et al, 1999). Sialyl-Lewis X moieties are tetra-saccharide-terminating glycan chains on N - and O -linked glycans that are important blood type antigens.…”

“…There are indications that the lung environment in CF is pro-inflammatory, a state further exacerbated by the chronic bacterial infections common in CF (Berger, 2002). Inflammation exacerbates these infections as pro-inflammatory cytokines such as TNFα, IL-6 and IL-8 increase Sialyl-Lewis x expression on mucins, which facilitates PA attachment (Colomb et al, 2014; Groux-Degroote et al, 2008) (figure 2a and b). Mucins obtained from CF airways are enriched with Sialyl-Lewis x and this has been shown to correlate to the severity of infection in CF (Davril et al, 1999).…”

Role of Cytokine-Induced Glycosylation Changes in Regulating Cell Interactions and Cell Signaling in Inflammatory Diseases and Cancer

“…These results indicate the involvement of a common signaling pathway regulating these three genes, dependent of the PI-PLC pathway rather than the NF-κB pathway. Further studies concerning the mechanisms involved in ST3GAL4 gene over-expression by TNF in human bronchial explants and in the A549 lung carcinoma cell line have shown the involvement of Extracellular Signal-Regulated kinases (ERK), p38 and Mitogen- and Stress-activated kinases 1/2 (MSK1/2) in the signaling pathways leading to sLe x and 6-sulfo-sLe x over-expression, while no role of the NF-κB pathway was shown [49]. …”

“…Moreover, the expression of this specific ST3GAL4 mRNA is increased by TNF treatment in both the human bronchial mucosa and in A549 lung cancer cell line, and is correlated with sLe x and 6-sulfo-sLe x over-expression on glycoproteins. Interestingly, even if in silico analysis of the ST4GAL4 genomic sequence have identified putative NF-κB binding site upstream the ST3GAL4 BX transcription start site (TSS), the only functional TNF responsive element is an intronic sequence downstream the BX TSS [49,50]. …”

The evolving dynamics of the microbial community in the cystic fibrosis lung

“…The unresolved inflammation in the chronically infected patient has a detrimental effect on lung function but may also serve to further enhance pathogen survival in the lung. One recently elucidated mechanism by which this occurs involves the upregulation of the sialyltransferase responsible for modifications to mucins in response to the inflammatory cytokine TNF, resulting in increased levels of the P. aeruginosa ligand sLex in bronchial mucosa (Colomb et al, 2013). A B. cenocepacia strain of the epidemic ET12 lineage activates the TNF receptor 1 (TNFR1) which is likely to play a role in the potent proinflammatory response induced by this species.…”