Occupational asthma phenotypes identified by increased fractional exhaled nitric oxide after exposure to causal agents

Occupational asthma to “the miracle tree” (Moringa oleifera): first description

“…6 Moreover, the increased FeNO after exposure to M. oleifera seed powder (from 32.37 to 94.34 ppb), which has been associated with OA due to exposure to high-molecular-weight antigens, 7 and our findings of IgE response to Moringa proteins together are consistent with a specific IgE immunologic mechanism that involves one or more of the proteins greater than 10 kDa identified by the immunoblotting technique. 7 To our knowledge, this is the first report of OA to M. oleifera documented through current guidelines, 4,6 suggesting that high-level exposure to Moringa should be considered a potential cause of IgE-mediated asthma. Further studies are however needed to more precisely estimate the prevalence and determinants of Moringa-induced respiratory allergy.…”

Environmental factors associated with baseline and serial changes in fractional exhaled nitric oxide (FeNO) in spice mill workers

“…These findings suggest a lack of sensitivity of the spirometry data and possible underdetection of asthma using conventional means. However, this could also point to a different occupational asthma phenotype associated with exposure to different workplace agents 5. It is possible that high endotoxin exposures, aside from allergen exposures, may also contribute to the pro-inflammatory role of airborne spice dust particulate since controlled exposure to coarse as well as fine ambient particles can independently induce systemic inflammatory responses 30…”

“…Bronchial allergen challenge tests have demonstrated a delayed elevation in FeNO 4 5. The role of FeNO measurement has emerged as providing a complementary role alongside existing pulmonary function tests6 in asthma diagnosis.…”

Diagnosing occupational asthma

“…In subjects with OA, an increase in FeNO occurs later (24 h vs. 6 h) than an increase in sputum eosinophils after challenge exposure to the causal agent . A recent study found that a post‐challenge increase in FeNO levels ≥ 17.5 ppb was associated with a positive SIC with a high specificity of 90% but a low sensitivity of 45% . Although assessment of FeNO may aid in the interpretation of SIC , the usefulness of serial measurements of FeNO at work and off work has not been prospectively investigated; only a few case reports have documented a possible role for this procedure .…”

“…On each day, the maximum, mean and minimum values of peak flow are plotted; there is clear pattern of work-related asthma with recovery on days away from work. levels ≥ 17.5 ppb was associated with a positive SIC with a high specificity of 90% but a low sensitivity of 45% [73]. Although assessment of FeNO may aid in the interpretation of SIC [74], the usefulness of serial measurements of FeNO at work and off work has not been prospectively investigated; only a few case reports have documented a possible role for this procedure [75][76][77].…”