2022 Annual Meeting and Alumni Reunion
Category : Basic and Translational Research Candidate : Amirreza Naderi Poster #: B17
The Effect of Neurokinin-1 Antagonism in Treating the Allergic Red Eye
Amirreza Naderi1 , 2 ; Shudan Wang ; Lingjia Liu ; Tomas Blanco ; Xia , Yutong ; Chen , Yihe ; Reza Dana
Purpose : Allergic conjunctivitis and various conditions can cause conjunctival vessel dilation , leading to ocular redness ( OR ). Using an animal model of allergic OR , we evaluated the therapeutic efficacy of topical blockade of substance P ( SP ), which preferentially binds to neurokinin-1receptor ( NK1R ) , in treating red eye .
Methods : Allergic OR was induced in guinea pigs with topical 1.5 mg / mL histamine . NK1R antagonist , L- 703,606 , was applied 10 minutes before or after OR induction as pre-induction or post-induction treatment , respectively . Their eyes ( N = 12 / group ) were imaged by a slit lamp every 30 seconds in the first 2 minutes , and at 6 , 10 , 20 , 30 , 40 , 50 , and 60 minutes . The redness was analyzed via pixel analysis to calculate the ocular redness index ( ORI ), a score between 0 to 100 . After 60 minutes , tear fluid was collected to quantify SP levels by ELSIA ( N = 6 / group ). Expression levels of IL-4 , IL-5 , IL-13 and TNF-α , cytokines associated with allergic response , were evaluated in conjunctiva via PCR ( N = 6 / group ). Lastly , conjunctiva were harvested and stained with H & E to quantify the size of blood vessels and eosinophil and neutrophil infiltration . Toluidine blue staining was used to enumerate mast cells ( N = 6 / group ).
Results : With histamine induction , the ORI peaked at 10 minutes ( maximum ORI : 17.04 ± 0.99 ). Topical treatment of L-703,606 significantly ( P < 0.05 ) reduced ORI ( pre-induction : 7.38 ± 0.71 ; post-induction : 10.91 ± 0.59 ). Compared to naive guinea pigs , histamine increased the conjunctival blood vessel diameter nearly three times ( naive : 10.15 ± 1.41 ; histamine : 30.66 ± 4.12 ). Both pre- and post-induction treatment decreased blood vessels diameter ( pre-induction : 16.84 ± 2.21 ; post-induction : 23.69 ± 2.36 ) but only pre-induction had significant ( P < 0.05 ) change . The tear concentration of SP was 71.64 ± 19.16 pg / mL in the naive group , and 270.60 ± 38.04 pg / mL in histamine-induced group . Pre-induction treatment significantly ( P < 0.05 ) decreased SP concentrations to 154.10 ± 9.72 pg / mL and post-induction treatment lowered SP levels to 191.10 ± 13.52 pg / mL . The numbers of eosinophils and neutrophils were 8.50 ± 2.69 and 4.67 ± 2.91 respectively in the conjunctiva of the naive group . Histamine increased the eosinophil count to 46.00 ± 2.57 and neutrophils to 31.47 ± 2.33 . Postinduction treatment reduced eosinophils to 35.50 ± 1.66 and neutrophils to 21.87 ± 1.97 , while pre-induction treatment significantly ( P < 0.01 ) decreased eosinophils to 26.00 ± 2.92 and neutrophils to 14.53 ± 2.31 . Finally , application of histamine significantly increased the expression levels of IL-4 , IL-5 , IL-13 , and TNF-alpha by 3-6 times compared to the normal control . Pre-induction treatment with L-703,606 effectively suppressed the upregulation of all cytokines to nearly normal levels , and post-induction treatment significantly reduced the expression levels of these cytokines by ~ 50 %.
Conclusions : Topical administration of the NK1R antagonist effectively reduces allergy-induced ocular redness by decreasing SP release in the tear fluid , allergy-associated cytokines in the conjunctiva and leukocyte infiltration .