Nasal Nitric Oxide and Nasal Cytology as Predictive Markers of Short-Term Sublingual Allergen-Specific Immunotherapy Efficacy in Children with Allergic Rhinitis

Background Few studies have been conducted on the short-term response to sublingual immunotherapy (SLIT). Objective The purpose of our experimental trial was to evaluate if two markers such as nasal nitric oxide (nNO) and nasal cytology could be useful to identify a precocious clinical efficacy of SLIT treatment. Methods We enrolled 34 children aged 6 to 14 years old with diagnosis of allergic rhinitis (AR) and documented sensitization towards house dust mites. We started allergoid-monomeric tablets immunotherapy along with any conventional therapy for AR and we evaluated at baseline (T0), after one (T1), two (T2), three (T3), and six months (T6) the effects of the treatment through the study of: i) a visual analogue scale (VAS 1-10); ii) measurement of nNO; iii) measurement of FeNO; iv) nasal cytology; v) spirometry; and vi) evaluation of any conventional therapy. Results We observed an improvement in symptoms evaluated by global VAS (T0 vs. T6: 47.13 vs. 17.57; p < .05) and a statistically significant reduction of nNO (1035.2 ± 956.08 vs. 139.2 ± 59.01; p < .05). In this case, significance was reached when the patients completed the 6 months of treatment. Cytological evaluation revealed significant reduction in nasal eosinophils (T0 vs. T6: 87% vs. 16%; p < .01). Moreover, at T0, 56% of patients had also neutrophils that were reduced up to the 8% at T6 (p < .05). Conclusions Our data confirm the effectiveness of SLIT treatment from a clinical perspective and identifies two biomarkers, such as nNO and nasal cytology, as predictive of treatment efficacy in the short term.

Can nasal nitric oxide be a biomarker to differentiate allergic and non-allergic rhinitis?

Background Nasal nitric oxide (nNO), a noninvasive indicator for eosinophilic airway inflammation, has not been adequately studied in different types of rhinitis. The aim of this study was to compare nNO levels between allergic (AR) and non-allergic rhinitis (NAR). Patients were included based on their chronic nasal symptoms. Total nasal symptoms score (TNSS) were evaluated. nNO was measured transnasally with a flow of 5 ml/s from the nostril with an NO analyzer (NIOX MINO; Aerocrine, Sweden). Results were evaluated as parts per billion (ppb). Results Four hundred forty-three patients (277 F/166 M)—337 with AR (76%) and 106 with NAR (24%)—were assessed. Patients with AR had significantly higher TNSS, more severe disease, and longer duration of disease compared to NAR group. Allergic rhinitis had significantly higher nNO levels than NAR (370 ppb vs 290 ppb) (p = 0.001). Likewise, significant differences were observed in female gender, in patients with BMI ≥ 25 kg/m2 and those without sinusitis between the two groups. When nNO were further evaluated in comorbid asthma, patients with AR w/o asthma had the highest TNSS and had significantly higher nNO level (p < 0.001). NAR+A group, with the longest duration of rhinitis, was significantly older and had the lowest nNO level (p < 0.001). Conclusions This study showed that nNO levels were significantly higher in AR patients than NAR. Although there is no recommended standard threshold for nNO, this study confirmed the utility of nNO in differentiating AR and NAR in addition to its known fast and non-invasive advantages.