Role of tissue eosinophils in chronic rhinosinusitis-associated olfactory loss

Mucus T helper 2 biomarkers predict chronic rhinosinusitis disease severity and prior surgical intervention

BACKGROUND

Chronic rhinosinusitis (CRS) is a diverse clinical syndrome with a heterogeneous pathophysiology. Early attempts to identify CRS endotypes and biomarkers have largely relied on analysis of surgically obtained tissue, thus limiting their practical utility. This study examined the ability of mucus T helper 2 (Th2) biomarkers to predict CRS disease severity and clinical characteristics.

METHODS

CRS (n = 90) and healthy control subjects (n = 17) were prospectively enrolled prior to surgical intervention and mucus levels of interleukin (IL)-4, IL-5, and IL-13 were determined using a multiplex cytometric bead assay. Data for relevant cytokines was then scaled, normalized, and later combined to develop standardized metrics indicative of Th2-associated inflammation. Th2-high and Th2-low subgroups were consequently identified and validated against factors associated with disease severity and clinical outcomes.

RESULTS

Mucus levels of IL-5 and IL-13 were elevated in CRS subjects compared to controls, while no significant difference was noted for IL-4. IL-5 and IL-13 high CRS were associated with worse objective measures of disease severity and greater rates of revision surgery. Similar relationships were noted for both cytokines when CRS with nasal polyps (CRSwNP) patients were analyzed separately. Th2-high CRS and Th2-low CRS were then categorized using a scaled IL-5/IL-13 metric. Th2-high CRS was characterized by an increased number of subjects with nasal polyps and comorbid asthma, and worse symptom and computed tomography (CT) scores.

CONCLUSION

The Th2-associated cytokines, IL-5 and IL-13, are detectable in sinonasal mucus and their levels can be used to define Th2-high and Th2-low CRS. Identification of Th2-high and Th2-low endotypes using mucus-based biomarkers could facilitate stratification of CRS subgroups and guide personalized therapies.

Causality Assessment of Olfactory and Gustatory Dysfunction Associated with Intranasal Fluticasone Propionate: Application of the Bradford Hill Criteria

Causality assessment is crucial to post-marketing pharmacovigilance and helps optimize safe and appropriate use of medicines by patients in the real world. Self-reported olfactory and gustatory dysfunction are common in the general population as well as in patients with allergic rhinitis and nasal polyposis. Intranasal corticosteroids, including intranasal fluticasone propionate (INFP), are amongst the most effective drugs indicated in the treatment of allergic rhinitis and nasal polyposis. While intranasal corticosteroids are associated with olfactory and gustatory dysfunction and are currently labeled for these adverse events, causality assessment has not been performed to date. Although there is no single widely accepted method to assess causality in pharmacovigilance, the Bradford Hill criteria offer a robust and comprehensive approach because nine distinct aspects of an observed potential drug–event association are assessed. In this literature-based narrative review, Hill’s criteria were applied to determine causal inference between INFP and olfactory and gustatory dysfunction.