Rhinovirus/enterovirus RNA in tonsillar tissue of children with tonsillar disease

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Abstract

Background

Human rhinoviruses (HRVs) together with the closely related human enteroviruses (HEVs) cause most of the acute respiratory illnesses throughout the year. HRVs have been detected in most parts of the respiratory tract but not in pharyngeal tonsils.

Objectives

We aimed to find out whether HRVs were detectable in tonsillar tissue and if their presence correlated to the tonsillar disease.

Study design

Thirty-three tonsillar samples collected in February–March 2003 from children with no acute respiratory symptoms were studied with HRV in situ hybridization (HRV-ISH). Ten tonsillar samples were further examined in a separate laboratory by two different reverse transcription polymerase chain reaction (RT-PCR) methods designed for detection of HRV/HEV RNA.

Results

Twenty of the 33 samples (62%) were positive by HRV-ISH. Five positive and five negative HRV-ISH samples were investigated by two different PCR methods. HRV/HEV RNA was detected in 9 of the 10 specimens by a hanging drop-nested PCR. One HRV-ISH negative sample was positive by a conventional non-nested PCR. One of the samples studied by all three methods, from a patient with recurrent tonsillitis, had no detectable HRV/HEV RNA. Positive result in HRV-ISH did not correlate significantly with underlying tonsillar disease, history of respiratory infections or bronchial asthma. Altogether HRV/HEV RNA was detected in 75% of the tonsils with no correlation to patients’ operation indication or history of respiratory diseases.

Conclusions

In February–March, HRV/HEV RNA was frequently found in tonsillar tissue in children irrespective of the tonsillar pathology. Whether detection of the RNA is a marker of chronic infection or is merely remnant of past infection is not known.

Introduction

The pathogenesis of common tonsillar diseases, chronic or recurrent tonsillitis and hyperplasia is largely unknown. Several pathogenic microbes, both bacteria and viruses, are known to be harbored by tonsils (Anlar et al., 2002, Endo et al., 2001, Frankel et al., 1997, Roush et al., 2001, Stenfors et al., 2003, Tanaka, 2001). Often, positive microbiological findings do not correlate with concurrent clinical disease (Brook and Foote, 1989, Brook and Foote, 1990, Fujimura et al., 2004).

Tonsillectomy is one of the most common pediatric operations, with indications ranging from recurrent or chronic tonsillitis through tonsillar hypertrophy to obstructive sleep disorders (Mattila et al., 2001). Commonly several indications exist simultaneously.

Human rhinoviruses (HRVs) belong to picornaviruses and, during spring and autumn seasons, they cause most of common colds (Arruda et al., 1997). The closely related enteroviruses (HEVs), another genus in the Picornavirus family, are also frequently associated with acute respiratory symptoms, and are relatively prominent during the winter months (Nokso-Koivisto et al., 2004). Rhinoviruses replicate in epithelial cells in the posterior nasopharynx (Arruda et al., 1995), adenoid area and nasal passages (Pitkaranta et al., 2002, Pitkaranta et al., 2003). Rhinovirus RNA has also been shown in the maxillary sinus epithelium of patients with acute sinusitis (Pitkaranta et al., 2001). In addition, in situ hybridization studies have established that rhinovirus infections occur in the tracheobronchial tree following experimental infection (Papadopoulos and Johnston, 2000). Pharyngeal symptoms are common during rhinoviral infections, yet HRV has not been demonstrated in palatine tonsillar tissue.

We aimed to find out whether HRV could be detected in tonsillar tissue, and whether demonstrable picornaviruses were associated with tonsillar diseases in children.

Section snippets

Patients and methods

We recruited, during February and March 2003, 33 consecutive voluntary children (2–18 years) referred to the Department of Otorhinolaryngology of Helsinki University Central Hospital for elective tonsillectomy or adenotonsillectomy. For enrolment, children had to be without acute respiratory symptoms at the time of the operation. Inclusion criteria were: recurrent tonsillitis (at least 6/year or 3/year for 2 consecutive years, with at least one positive culture for Streptococcus pyogenes), or a

Patient history

Tonsillectomy was performed to 23 boys and 10 girls, 14 of them also had adenoidectomy. The median age of the children was 7.5 years (range 2.0–16.8 years, Table 1). Snoring was reported as a symptom for 90% of children. Frequently, recurrent upper respiratory infections (n = 18) and recurrent (over three episodes of) otitis media (n = 17) were common complaints. Recurrent (>3) sinusitis (n = 2) and bronchial asthma (n = 3) were rare. Recurrent tonsillitis was uncommon in family members (n = 4) or day

Discussion

The present study shows, that HRV RNA, or that of closely related HEV strains, can frequently be found in the palatine tonsils of children with both recurrent or chronic tonsillitis and tonsillar hypertrophy. Several other viruses, including HIV, human herpesvirus 6, Ebstein-Barr virus, measles virus and newly human papillomavirus-16, have been previously found in the tonsils (Anlar et al., 2002, Chen et al., 2005, Endo et al., 2001, Frankel et al., 1997, Roush et al., 2001, Stenfors et al.,

Acknowledgements

We thank Ms. Tuula Halmesvaara, Ms. Svetlana Kaijalainen, Ms. Irina Suomalainen and the research laboratory of the Department of Otorhinolaryngology for expert technical assistance.

This study was supported by grants from a special governmental subsidy for health sciences research in Finland, the Pediatric Research Foundation, Microbes and Man Research Programme of Academy of Finland, Sigrid Jusélius Foundation and Finska Läkaresällskapet.

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