High cytokine levels in perforated acute otitis media exudates containing live bacteria

Area of Science:

• Immunology
• Microbiology
• Otolaryngology

Background:

• Acute otitis media (AOM) is a common middle ear infection characterized by inflammation and potential tympanic membrane perforation.
• Leukocytes exhibit distinct inflammatory mediator profiles when exposed to Gram-positive versus Gram-negative bacteria in vitro.
• Understanding the in vivo inflammatory response in AOM is crucial for developing targeted therapeutic strategies.

Purpose of the Study:

• To investigate cytokine and prostaglandin E2 (PGE2) levels in middle ear fluids (MEFs) from children with perforated AOM.
• To correlate mediator levels with the presence of bacterial pathogens detected by culture or PCR.
• To compare in vivo cytokine patterns with in vitro leukocyte responses to bacterial stimulation.

Main Methods:

• Analysis of middle ear fluids (MEFs) from children with spontaneously perforated AOM.
• Detection of pathogens using bacterial culture and PCR.
• Quantification of inflammatory mediators including IL-1β, TNF, IL-8, IL-10, IL-6, and PGE2.
• In vitro stimulation of human leukocytes with dead bacteria for comparative analysis.

Main Results:

• MEFs with culturable bacteria showed significantly higher levels of IL-1β, TNF, IL-8, and IL-10 compared to culture-negative fluids.
• IL-6 and PGE2 levels were consistently high regardless of bacterial presence (live, dead, or undetectable).
• In vivo cytokine production (IL-1β, IL-8, IL-10) was substantially higher than in vitro responses, while TNF and IL-6 were comparable.

Conclusions:

• A robust proinflammatory cytokine response characterizes AOM with membrane rupture, irrespective of the specific pathogen.
• Bacterial disintegration rapidly diminishes the production of certain cytokines.
• Sustained levels of IL-6 and PGE2 post-bacterial clearance suggest a role in the resolution phase of AOM.