Evidence of local antibody response againstAlloiococcus otitidisin the middle ear cavity of children with otitis media

Abstract

Alloiococcus otitidis is a recently discovered bacterium frequently associated with otitis media. However, no study is available as to whether A. otitidis has a pathogenic role and induces local immune response in the middle ear as a true pathogen. Whole bacterial sonicate of A. otitidis was separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and transferred to a nitrocellulose membrane. Then, Western blot analysis was performed with supernatant of the middle ear effusions from children with A. otitidis-positive otitis media. SDS-PAGE of the bacterial sonicate showed several protein bands, designated A1-A11. Western blot analysis revealed the presence of IgG, secretory IgA, IgG2, and IgM against A. otitidis in the middle ear effusions. Absorption of the specimens with sonicates of other major middle ear pathogens did not alter the reactivity of antibodies against the alloiococcal antigens. The results suggest that specific local immune response against A. otitidis is induced during middle ear infection of the organism as a true pathogen. A5, A6 or A11 is expected to be a main antigenic determinant. This is the first report to show evidence of local antibody response against A. otitidis and to disclose antigenic components of A. otitidis.

Interleukin-8 induction via NF-κB, p38 mitogen-activated protein kinase and extracellular signal-regulated kinase1/2 pathways in human peripheral blood mononuclear cells by Alloiococcus otitidis

“…A. otitidis enhances the expression of an activation antigen, CD69, on human PBMCs, and stimulates the release of T helper type 1 cytokines from PBMCs as well as other middle ear pathogens such as S. pneumoniae [12]. And, children with otitis media produce specific antibodies against A. otitidis in the middle ear cavity [13]. These studies suggest that A. otitidis may have immunostimulating activity.…”

Preliminary study of proinflammatory cytokines and chemokines in the middle ear of acute otitis media due to Alloiococcus otitidis

“…These results suggest that A. otitidis has the potential to induce these cytokines/ chemokines, contributing to the development of inflammation in the middle ear in a similar manner to S. pneumoniae. Considering the previous finding that A. otitidis becomes immunogenic in the human middle ear [21], this study will help us to understand the association of this organism with otitis media.…”

Alloiococcus otitidis Forms Multispecies Biofilm with Haemophilus influenzae: Effects on Antibiotic Susceptibility and Growth in Adverse Conditions

“…In the past, A. otitidis has been considered a commensal of the external ear canal (Frank et al, 2003 ; Tano et al, 2008 ). However, consensus on the role of A. otitidis remains divided, as A. otitidis has been shown to have pathogenic traits including eliciting immune responses in vitro (Himi et al, 2000 ; Tarkkanen et al, 2000 ; Harimaya et al, 2005 , 2007a , b , 2009 ), invading intracellularly (Faden and Dryja, 1989 ) and having been identified as a pathogen in device related (Marchino et al, 2013 ) and chronic infection (Cakar et al, 2013 ). Utilizing culture-independent 16S rRNA sequencing, our department confirmed that A. otitidis and H. influenzae are the two most common bacteria demonstrated in children with OME and that the external ear canal may act as a reservoir for the middle ear (Chan et al, 2017 , 2016 ).…”