In vitro characteristics of an airway barrier‐disrupting factor secreted by Staphylococcus aureus

Abstract

BackgroundStaphylococcus aureus is a major contributor to the pathophysiology of chronic rhinosinusitis (CRS). Previous research has shown that S. aureus–secreted products disrupt the airway barrier.MethodsS. aureus ATCC 13565 and 25923 strains were grown at exponential, postexponential, and stationary phases. Microbial conditioned media (CM) was collected from the cultures and ultrafiltered (UF). Liquid chromatography–electrospray ionization tandem mass spectrometry (LC‐ESI‐MS/MS) was performed on the UF‐CM. UF‐CM was subjected to heat and protease treatment, size fractionation, and ultracentrifugation (UC) separation. Human nasal epithelial cells grown at air‐liquid interface (HNEC‐ALI) cultures were exposed to purified alpha hemolysin (Hla), staphylococcal enterotoxin A (SEA), lipoteichoic acid (LTA), and UF‐CM. Barrier function outcomes were measured by transepithelial electrical resistance (TEER) and apparent permeability (Papp). UC fraction exposed cultures were subjected to immunofluorescence microscopy for tight junction (TJ) protein zonula occludens‐1 (ZO‐1).ResultsLC‐ESI‐MS/MS identified 107 proteins, with Hla being most abundant. Hla, SEA, and LTA did not alter the HNEC‐ALI barrier as measured by TEER or Papp. Barrier disruption caused by UF‐CM peaked in the postexponential phase, was sensitive to heat and protease treatment, >30‐kDa in size, and enriched in the UC fraction. HNEC‐ALI exposed to UF‐CM and UC demonstrated loss of ZO‐1 localization.ConclusionThese results suggest that the S. aureus factor responsible for TJ disruption in HNEC‐ALI cultures is either a protein‐macromolecule or a combination of secreted factors. The product is enriched in the UC fraction, suggesting it is associated with large structures such as membrane components or vesicles.

Sub-Inhibitory Clindamycin and Azithromycin reduce S. aureus Exoprotein Induced Toxicity, Inflammation, Barrier Disruption and Invasion

“…Our previous studies found S. aureus exoproteins could severely disrupt the mucosal barrier structure and function of HNEC-ALI cultures [27,28,29]. To explore the effect of sub-inhibitory clindamycin and azithromycin on S. aureus exoprotein induced barrier dysfunction, S. aureus was cultured with and without ½ MIC clindamycin or azithromycin, exoproteins filtered and added to the apical chamber of HNEC-ALI cultures.…”

Protective Roles of Folic Acid in the Responses of Bovine Mammary Epithelial Cells to Different Virulent Staphylococcus aureus Strains

“…On the other hand, the tight junction pathway also plays a vital function in the normal epithelial barrier protect against pathogens [ 56 ]. S. aureus and MRSA disrupted the tight junction and suppressed its assembly [ 57 , 58 , 59 , 60 ], and FA was able to reduce the damage of S. aureus and MRSA to Mac-T cells’ tight junction ( Figures S8 and S9 ). The genes of SCRIB , ERRB2, and ROCK2 within tight junction pathway were also found to be associated with the GWAS signals of bovine SCS trait ( Figure S13 ).…”

Immunopathologic Role of Eosinophils in Eosinophilic Chronic Rhinosinusitis

“…SEB can also impair nasal epithelial cells’ innate physical barrier defense system. When SEB was applied to nasal epithelial cells, the expression of zonula occludens-1 and occluding protein was decreased, which was associated with increased cellular permeability and decreased trans-epithelial electrical resistance [ 62 ]. Simultaneously, SEB-induced IL-6 and IL-8 production from epithelial cells, as well as endoplasmic reticulum stress, can cause nasal epithelial cell barrier dysfunction.…”