Staphylococcus epidermidis and biofilm‐associated neutrophils in chronic rhinosinusitis. A pilot study

Abstract

A key role of bacterial biofilm in the pathogenesis of chronic rhinosinusitis (CRS) with (CRSwNP) and without nasal polyps (CRSsNP) is commonly accepted. However, the impact of some bacterial species isolated from inflamed sinus mucosa on biofilm formation is unclear. In particular, the role of Staphylococcus epidermidis as aetiological agents of CRS is controversial. Moreover, the effect of biofilm formation on neutrophil infiltration and activity in CRSwNP calls for explanation. In this study, biofilms were found in three of 10 patients (mean age = 46 ± 14) with CRS undergoing endoscopic sinus surgery by means of scanning electron microscopy. Unexpectedly, S. epidermidis was the primary isolated bacteria and was also found to be present in all biofilm-positive mucosa specimens, indicating its pivotal role in the pathogenesis of severe chronic infections associated with biofilm formation. We have also measured the activity of myeloperoxidase (MPO), the most abundant neutrophil enzyme, to demonstrate the presence of neutrophils in the samples tested. Our present results show that the level of MPO in CRS associated with biofilm is lower than that without biofilm. It may suggest either a low number of neutrophils or the presence of a type of neutrophils with compromised antimicrobial activity, described as biofilm-associated neutrophils (BAN). Finally, we conclude that further studies with a large number of CRS cases should be performed to establish the association between S. epidermidis and other frequently isolated bacterial species from paranasal sinuses, with the severity of CRS, biofilm formation and the infiltration of BAN.

<p>Bacterial Flora of the Nose and Paranasal Sinuses Among Patients Over 65 Years Old with Chronic Rhinosinusitis Who Underwent Endoscopic Sinus Surgery</p>

“…17,18 Also, in some studies of bacterial biofilm of the sinus mucosa, the dominance of Staphylococcus epidermidis over Staphylococcus aureus and other bacteria in the production of biofilm has been reported. 19 In our study in the group of patients after 65 years of age (compared to younger patients), more frequent occurrence of two opportunistic Gram-negative bacteria was confirmed: Pseudomonas aeruginosa and Proteus spp. (p = 0.01).…”

Pseudomonas aeruginosa biofilm is a potent inducer of phagocyte hyperinflammation

“…The main objective of this study was to show that neutrophils and macrophages can be effectively stimulated by P. aeruginosa -derived biofilm extracellular substances without direct contact with bacterial cells, because the biofilm provides a very concentrated stable source of PAMPS which are otherwise present at very low concentrations in bacterial culture supernatant. We further hypothesize that the presence of such stimulated cells (BANs, BAMs) in a hyperinflammatory state of activation may explain the detrimental role of neutrophils in chronic P. aeruginosa infection associated with the pathogenesis of CF [ 41 , 42 ] and, as we have previously observed, in chronic rhinosinusitis [ 15 ].…”

“…We hypothesize that neutrophils and macrophages, upon contact with active biofilm matrix components such as found in a biofilm environment, polarize into biofilm-associated neutrophils (BANs) and biofilm-associated macrophages (BAMs). Based on previous studies [ 15 , 21 , 22 ], we suggest that these phagocytes will be of hyperinflammatory phenotype, sometimes referred to as N1/M1 phenotypes. We explore this hypothesis by examining the inflammatory phenotype of macrophages and neutrophils exposed to P. aeruginosa extracellular products produced early (8 h) in culture, when biofilm production is just initiated, and P. aeruginosa extracellular products produced late (72 h), when massive biofilm production takes place.…”

“…Biofilm may, therefore, both protect bacteria from killing, yet activate hyperinflammation. It has been well documented that hyperinflammatory response, the effect of activation of neutrophils and macrophages with limited access to targets, does favor chronic inflammation without effective bacterial clearance [ 15 – 18 ]. Such reaction was also named as “ frustrated phagocytosis ” [ 19 , 20 ].…”

Endotypes of allergic diseases and asthma: An important step in building blocks for the future of precision medicine

“…86 A low number of neutrophils or the presence of a type of neutrophils with compromised antimicrobial activity was related to the formation of biofilms in CRS. 87 The increased activity of neutrophil elastase is in direct correlation with the levels of interleukin-8 and neutrophils. 88 In a subset of chronic obstructive lung disease (COPD) patients the tripeptide matrikine proline-glycine-proline (PGP) seems to play a role.…”