Pseudomonas aeruginosa Activates PKC-Alpha to Invade Middle Ear Epithelial Cells

Area of Science:

• Microbiology and Immunology
• Cell Biology
• Otolaryngology

Background:

• Otitis media (OM), particularly chronic suppurative otitis media (CSOM), is a significant health issue causing hearing loss and CNS complications.
• Pseudomonas aeruginosa is a primary pathogen in CSOM, known to invade human middle ear epithelial cells (HMEECs).
• The molecular mechanisms underlying P. aeruginosa invasion of HMEECs remain largely unknown.

Purpose of the Study:

• To investigate the role of the Protein Kinase C (PKC) pathway in P. aeruginosa colonization of HMEECs.
• To elucidate the specific PKC pathway components involved in bacterial invasion.
• To identify potential therapeutic targets for CSOM based on host-pathogen interactions.

Main Methods:

• Activation of the PKC pathway, specifically PKC-alpha (PKC-α) phosphorylation, by otopathogenic P. aeruginosa in HMEECs was assessed.
• The dependence of PKC-α phosphorylation on bacterial OprF expression was evaluated.
• The association between PKC-α activation and actin condensation was observed.
• The effect of blocking the PKC pathway on bacterial invasion and actin condensation was determined.

Main Results:

• Otopathogenic P. aeruginosa activates the PKC pathway, leading to PKC-α phosphorylation in HMEECs.
• PKC-α phosphorylation by P. aeruginosa is dependent on the bacterial OprF protein.
• PKC-α activation correlates with actin condensation within HMEECs.
• Inhibition of the PKC pathway significantly reduces P. aeruginosa invasion and subsequent actin condensation.

Conclusions:

• The host PKC-α pathway plays a crucial role in the invasion of HMEECs by P. aeruginosa.
• PKC-α activation, mediated by bacterial OprF, facilitates bacterial entry and cytoskeletal changes.
• This study reveals a novel host signaling pathway involved in CSOM pathogenesis, opening avenues for new treatment strategies.