ABSTRACT
Tonsils has a vital function in the body’s immune system for children and tonsillitis is one of the most frequent causes of children exploring Ear-Nose-throat (ENT) department in hospitals around the worlds.
This study examines the effect of Staphylococcus aureus and Streptococcus pyogenes biofilms on distribution and phenotyping of cellular immunity and serum Toll-like receptor-2 (sTLR2) levels, and the relation of TLR2 Arg753Gln polymorphism with the risk and susceptibility to tonsillitis.
The study included 118 pediatric tonsillitis patients and 50 healthy controls. Thirty isolated S. aureus and S. pyogenes were tested for biofilm forming capability (BFC) and hematological parameters were assessed before tonsillectomy. Nine tonsil samples were evaluated using hematoxylin and eosin (H&E) stain to investigate the histopathological alterations. Immunohistochemistry (IHC) staining was carried out for detecting dendritic cells (CD1a), neutrophils (CD15), macrophages (CD68), helper T cells (CD4), and cytotoxic T cells (CD8). Additionally, Enzyme-Linked Immunosorbent Assay (ELISA) determined levels of serum TLR2, and TLR2 Arg753Gln polymorphism were detected via Amplification Refractory Mutation System–Polymerase Chain Reaction (ARMS-PCR).
According to this research, both S. aureus and S. pyogenes had the ability to form biofilms with different capacities. 72% of the S. aureus isolates showed a moderate BFC compared to 23% strong and 5% with weak ability, while 50% of S. pyogenes showed strong BFC compared to 37% moderate and 13% with weak ability. Hematological parameters showed a significant increase in total white blood cell (WBC) count in tonsillitis patients infected with those bacteria and these bacteria cause hyperplasia and increase in the thickness of tonsillar septa with massive deposition of collagen fibers and hypertrophy of tonsillar follicles was observed with diffuse infiltration of lymphocytes and macrophages.
The effect of biofilms on immune cells CD1a and CD15 showed weak positive staining, while CD68, CD4, and CD8 showed positive to strong positive staining. Additionally, the effect of BFC led to non-significantly increase sTLR2 in S. aureus group (p1=0.6996) while decrease in S. pyogenes group (p2>0.9999) whereas significantly increased in tonsillitis children infected with mixed bacteria (P3=0.0018). Moreover, the Co-dominant GA genotype and the dominant model GA + AA of TLR2 Arg753Gln polymorphism was significantly elevated in 78% and 84% of tonsillitis patients comparing to control group (46%) (OR = 5.72, 95% CI: 2.30–14.2, P < 0.0001) and (OR = 6.38, P < 0.0001).
This study confirmed the association between BFC of S. aureus and S. pyogenes and the persistent nature of the infection, which decreases phagocytosis and the antigen processing and presenting by both neutrophils and dendritic cells. Interestingly, BFC led to increase sTLR2 levels in tonsillitis patients significantly in mixed bacterial group and thus they might be useful as a diagnostic tool for tonsillitis in children. Additionally, the GA genotype of TLR2 Arg753Gln had a significant association with the development of tonsillitis and may serves as a prognostic predictor for tonsillitis risk among children.
