Rhinovirus infections cause exacerbations of asthma. We postulated that people with asthma are more susceptible to rhinovirus infection than people without the disease and compared the susceptibility of these groups.
We recruited 76 cohabiting couples. One person in every couple had atopic asthma and one was healthy. Participants completed daily diary cards of upper-respiratory-tract (URT) and lower-respiratory-tract (LRT) symptoms and measured peak expiratory flow twice daily. Every 2 weeks nasal aspirates were taken and examined for rhinovirus. Mixed models were used to compare risks of infection between groups. We also compared the severity and duration of infections.
We analysed 753 samples. Rhinovirus was detected in 10.1% (38/378) of samples from participants with asthma and 8.5% (32/375) of samples from healthy participants. After adjustment for confounding factors, asthma did not significantly increase risk of infection (odds ratio 1.15, 95% CI 0.71-1.87). Groups did not differ in frequency, severity, or duration of URT infections or symptoms associated with rhinovirus infection. First rhinovirus infection was associated more frequently with LRT infection in participants with asthma than in healthy individuals (12 of 28 infections vs four of 23, respectively, p=0.051). Symptoms of LRT associated with rhinovirus infection were significantly more severe (p=0.001) and longer-lasting in participants with asthma than in healthy participants (p=0.005).
People with atopic asthma are not at greater risk of rhinovirus infection than healthy individuals but suffer from more frequent LRT infections and have more severe and longer-lasting LRT symptoms.
"Bacterial infections, such as Streptococcus pneumoniae, Haemophilius influenzae and Moraxella cattarhalis are also present during asthma exacerbations and have been shown to be both triggers of the exacerbation or play an opportunistic role following viral infection . Moreover, microbial exacerbations have been shown not only to extend the period of illness, but also increase the respiratory symptoms, such as airway hyperresponsiveness (AHR) , , . Despite the breadth of epidemiological studies in this area, the mechanisms behind these phenomena are still poorly understood. "
[Show abstract][Hide abstract] ABSTRACT: It is well-established that bacterial and viral infections have an exacerbating effect on allergic asthma, particularly aggravating respiratory symptoms, such as airway hyperresponsiveness (AHR). The mechanism by which these infections alter AHR is unclear, but some studies suggest that Toll-like receptors (TLRs) play a role. In this study, we investigated the impact of TLR3 and TLR4 ligands on AHR and airway inflammation in a model of pre-established allergic inflammation. Female BALB/c mice were sensitised and challenged intranasally (i.n.) with either PBS or ovalbumin (OVA) and subsequently i.n. challenged with poly (I:C) (TLR3) or LPS (TLR4) for four consecutive days. The response to methacholine was measured in vivo; cellular and inflammatory mediators were measured in blood, lung tissue and broncheoalveolar lavage fluid (BALF). OVA challenge resulted in an increase in AHR to methacholine, as well as increased airway eosinophilia and TH2 cytokine production. Subsequent challenge with TLR agonists resulted in a significant increase in AHR, but decreased TLR-specific cellular inflammation and production of immune mediators. Particularly evident was a decline in LPS-induced neutrophilia and neutrophil-associated cytokines following LPS and poly (I:C) treatment. The present data indicates that TLRs may play a pivotal role in AHR in response to microbial infection in allergic lung inflammation. These data also demonstrate that aggravated AHR occurs in the absence of an exacerbation in airway inflammation and that allergic inflammation impedes a subsequent inflammatory response to TLRs. These results may parallel clinical signs of microbial asthma exacerbation, including an extended duration of illness and increased respiratory symptoms.
PLoS ONE 08/2014; 9(8):e104114. DOI:10.1371/journal.pone.0104114 · 3.23 Impact Factor
"Reports indicate that majority of the viral respiratory tract infections caused by human rhinoviruses are associated with asthma exacerbations (Busse et al., 2010). However, studies also indicate that asthmatic individuals do not necessarily develop frequent episodes of cold, and the severity and duration are not enhanced by respiratory allergies or asthma (Doyle et al., 1992; Corne et al., 2002). "
"Prospective monitoring studies using reverse transcription polymerase chain reaction (RT-PCR) indicate that as many as 85% of acute asthma exacerbations in children, and about 60% in adults, were associated with the presence of upper respiratory tract (URT) infections. Corne et al. (2002) found that the detection rates of HRV in asthmatic (10.1%) and healthy participants (8.5%) were similar, but the LRT symptoms were significantly more severe and longer lasting in the asthmatic group than in the healthy group based on one definition of URT and LRT symptoms (Table 2; Johnston et al., 1995). There is no common antigen across all strains of HRVs; therefore, no reliable diagnostic method for HRV infection has been established using HRV antigens or HRV-specific antibody. "
[Show abstract][Hide abstract] ABSTRACT: Viral respiratory infections may be associated with the virus-induced asthma in adults as well as children. Particularly, human rhinovirus is strongly suggested a major candidate for the associations of the virus-induced asthma. Thus, in this review, we reviewed and focused on the epidemiology, pathophysiology, and treatment of virus-induced asthma with special reference on human rhinovirus. Furthermore, we added our preliminary data regarding the clinical and virological findings in the present review.
Frontiers in Microbiology 05/2014; 5:226. DOI:10.3389/fmicb.2014.00226 · 3.99 Impact Factor
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