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Eicosanoid levels in nasal secretions from individuals with chronic rhinosinusitis (CRS) may help differentiate between patients with varying nasal polyp (NP) severity and aspirin-exacerbated respiratory disease (AERD). Eicosanoid levels also appear to relate to loss of smell and increased fractional exhaled nitric oxide (FeNO), according to study findings published in the journal Prostaglandins, Leukotrienes & Essential Fatty Acids (PLEFA).
Study authors found in patients with CRS, severe nasal polyposis and inflammation of mucous may be associated with a dysregulated eicosanoid profile, but the clinical role played by eicosanoids in CRSwNP (CRS with NP) has yet to be fully clarified. Study authors at Sophiahemmet Hospital in Stockholm, Sweden, therefore conducted a study to assess the levels of eicosanoids and inflammatory mediators in nasal secretions and urine from patients with different levels of NP severity or AERD.
The study authors recruited patients scheduled for sinus surgery due to bilateral CRS without nasal polyps (CRSsNP), CRSwNP, or CRSwNP-AERD with the hospital’s Department of Otolaryngology. Nasal polyp severity was studied endoscopically, with each nostril scored on a scale of 0 (no polyps detected) to 4 (presence of large polyps blocking the inferior meatus), and the total score reflecting the sum of the right and left nostril scores. Patients with CRSwNP were subdivided into 2 groups based NP severity scores: CRSwNP-low severity (NP score ≤4, n=11); and CRSwNP-high severity (NP score ≥5, n=32). These patients were compared with those with CRSsNP (n=12) and CRSwNP-AERD (n=11). Researchers also recruited a control group (n=25) without CRS.
A smell test was performed in all participants via use of Burghart Sniffin’ Sticks (Extended Test n-Butanol, MediSense), a validated tool for evaluating the degree of smell loss. This tool comprises 3 subtests: (1) threshold (T), (2) discrimination (D), and (3) identification (I). All study participants were exposed to odors using felt-tip pens placed under their noses and asked to identify and discriminate between various odors. Fractional exhaled nitric oxide (FeNO), eosinophil blood count, and computed tomography (CT) findings at least 3 months prior to surgery were evaluated as well.
Analysis showed that levels of leukotriene E4 (LTE4) were considerably higher in nasal secretions from participants with CRSwNP-AERD vs from those in the control group, those categorized as CRSwNP-low severity, and those categorized as CRSwNP-high (P =.07). Additionally, when compared with the control group, individuals with CRSwNP-high severity reported a tendency toward elevated levels of LTE4 (P =.06). Further, in comparing LTE4 levels between cohorts, the investigators found that levels increased from the control group to the low polyp grade group to the high polyp grade group, with the highest levels observed in the cohort with CRSwNP-AERD.
Levels of prostaglandin D2 in nasal secretions, as well as urinary levels of 11β-prostaglandin F2α, differed between those in the CRSwNP-low severity group and those in the high severity group. These results suggest that the urinary metabolite may be more closely related to asthma comorbidity, said the study authors.
In discussing study limitations, study authors noted that FeNO values could be lowered to a significant degree in patients with asthma considered to be “well treated,” thus limiting the discriminatory value of FeNO. The use of enzyme immunoassays in the analyses of eicosanoids, rather than liquid chromatography tandem mass spectrometry, may also be a potential study limitation.
Study authors concluded that “subdividing patients based on NP severity in combination with analysis of eicosanoids in non-invasively collected nasal secretions, may have clinical implications when assessing CRS disease severity.” They added that further research is needed to determine whether similar eicosanoid inflammatory signatures relate to disease progression and refractory polyp growth.
Reference
Nordström A, Jangard M, Svedberg M, Ryott M, Kumlin M. Levels of eicosanoids in nasal secretions associated with nasal polyp severity in chronic rhinosinusitis. Prostaglandins Leukot Essent Fatty Acids. Published online July 23, 2022. doi:10.1016/j.plefa.2022.102474
