bacterial DNABII

We examined sinus mucosal samples recovered from pediatric chronic rhinosinusitis (CRS) patients for the presence of Z‐form extracellular DNA (eDNA) due to its recently elucidated role in pathogenesis of disease. Further, we immunolabeled these specimens for the presence of both members of the bacterial DNA‐binding DNABII protein family, integration host factor (IHF) and histone‐like protein (HU), due to their known role in converting common B‐DNA to the rare Z‐form.

Sinus mucosa samples recovered from 20 patients during functional endoscopic sinus surgery (FESS) were immunolabelled for B‐ and Z‐DNA, as well as for both bacterial DNABII proteins.

Nineteen of 20 samples (95%) included areas rich in eDNA, with the majority in the Z‐form. Areas positive for B‐DNA were restricted to the most distal regions of the mucosal specimen. Labeling for both DNABII proteins was observed on B‐ and Z‐DNA, which aligned with the role of these proteins in the B‐to‐Z DNA conversion.

Abundant Z‐form eDNA in culture‐positive pediatric CRS samples suggested that bacterial DNABII proteins were responsible for the conversion of eukaryotic B‐DNA that had been released into the luminal space by PMNs during NETosis, to the Z‐form. The presence of both DNABII proteins on B‐DNA and Z‐DNA supported the known role of these bacterial proteins in the B‐to‐Z DNA conversion. Given that Z‐form DNA both stabilizes the bacterial biofilm and inactivates PMN NET‐mediated killing of trapped bacteria, we hypothesize that this conversion may be contributing to the chronicity and recalcitrance of CRS to treatment.

NA Laryngoscope, 134:1564–1571, 2024

Otitis media with effusion (OME) is a common disease of childhood that is largely asymptomatic. However, middle ear fluid can persist for months and negatively impact a child's quality of life. Many cases of OME remain chronic and require surgical intervention. Because biofilms are known to contribute to the persistence of many diseases, this study examined effusions collected from children with chronic OME for the presence of essential biofilm structural components, members of the DNABII family of bacterial DNA‐binding proteins.

Middle ear effusions were recovered from 38 children with chronic OME at the time of tympanostomy tube insertion. A portion of each specimen was submitted for microbiology culture. The remaining material was assessed by immunoblot to quantitate individual DNABII proteins, integration host factor (IHF), and histone‐like protein (HU).

Sixty‐five percent of effusions (24 of 37) were culture‐positive for bacterial species or yeast, whereas 35% (13 of 37) were culture‐negative. IHF was detected in 95% (36 of 38) at concentrations from 2 to 481 ng/μL effusion. HU was detected in 95% (36 of 38) and quantitated from 13 to 5,264 ng/μL effusion (P ≤ 0.05 compared to IHF).

Because DNABII proteins are essential structural components of bacterial biofilms, these data lend further support to our understanding that biofilms are present in the vast majority of chronic middle ear effusions, despite negative culture results. The presence and ubiquity of DNABII proteins in OME specimens indicated that these proteins can serve as an important clinical target for our novel DNABII‐directed strategy to treat biofilm diseases such as chronic OME.

NALaryngoscope, 130:806–811, 2020

The purpose of this review is to discuss the unique pathways of biofilm formation utilized by respiratory pathogens and current and future therapeutic strategies to inhibit biofilm formation or eradicate established biofilm in the context of these pathogens. Both nonselective and selective strategies for inhibiting biofilm formation or disrupting established biofilm are discussed.

Numerous strategies are being actively pursued to inhibit biofilm formation or eradicate established biofilm in respiratory pathogens. These can be broadly categorized by the stage of biofilm formation (adhesion, extracellular polysaccharide synthesis or structure, EPS, and matrix degradation) that they target and by their selectivity or lack thereof for specific biofilm pathogens. Nonselective inhibitors of adhesion include N-acetylcysteine and artificial surfactants and biosurfactants. Selective inhibitors of adhesion include mannosides that target host-EPS interactions, EPS-targeted antibodies, and other inhibitors of bacterial adhesion. Nonselective inhibitors of EPS synthesis and structure include cyclic di-GMP and cyclic di-AMP-through disruption of glucan-producing exoenzymes. Selective inhibitors of EPS synthesis and structure include antibodies that target proteins essential for biofilm structure (such as DNABII proteins and type IV pilin protein in NTHi) or antibodies that target critical molecules in biofilm formation (such as DNA adenine methyltransferase in Streptococcus pneumoniae). Nonselective agents for EPS or biofilm matrix degradation include peptidoglycan hydrolases that enzymatically degrade bacterial cell wall peptidoglycan and DNase, which degrades extracellular DNA from neutrophils and microorganism-derived DNA. Selective agents for EPS or biofilm matrix degradation include exopolysaccharide-degrading enzymes, such as glycoside hydrolases active against Staphylococcus aureus or exopolysaccharide-degrading enzymes that target Psl and Pel from Pseudomonas aeruginosa. Current strategies toward inhibiting biofilm formation or disrupting established biofilm represent an exciting new approach toward treatment of chronic infectious diseases. Application of these strategies toward treatment of pediatric respiratory tract infections also offers promise of a better understanding of the significance of mucosal biofilm in the pathogenesis of these conditions.