Investigating Nasal and Ocular Immune Response to Conjunctival Allergen Exposure

The purpose of this pilot, single-centre, prospective, cohort study is to evaluate an updated CAC protocol using timothy grass allergen in participants with allergic rhinoconjunctivitis. The previously standardized CAC protocol from 1990 has not undergone any major public revisions, highlighting a clear need for an updated, evidence-based protocol to support modern ocular allergy studies. Therefore, we propose to develop and pilot a revised CAC model.

This study will enroll non-pregnant and non-lactating female and/or male participants. The pilot sample size will include 6 allergic and 6 non-allergic participants aged 18-70 years. Participants will be recruited from the Kingston, Frontenac, Lennox, and Addington region in Ontario, Canada. All 12 participants will attend three study visits: Visit 1 (Screening), Visit 2 (CAC exposure), and Visit 3 (Follow-up and additional CAC for non-allergic participants).

Visit 2 will occur a minimum of 21 days after Visit 1 and Visit 3 will occur 24 hours after allergen exposure during Visit 2. At Visit 2, symptom scores, tear samples, and nasal fluid (sponge) samples will be collected from all participants. At Visit 3, non-allergic participants will undergo an additional CAC and nasal sponge sampling to assess allergen movement from the eye to the nose.

The investigators hypothesize that CAC with timothy grass allergen in sensitized allergic individuals will induce a measurable allergic response in the eye receiving allergen instillation, compared to pre-exposure levels. This allergic response will be measured using symptom scores (Total Ocular Symptom Score (TOSS), Total Nasal Symptom Score (TNSS), and Total Rhinoconjunctivitis Symptom Score (TRSS)) and allergic biomarkers (IL-1rA, IL-4, IL-5, IL-6, IL-8, IL-9, IL-10, IL-13, IL-25, IL-31, IL-33, EGF, VEGF-A, MCP-1, and TSLP) for the eye and the nose. The investigators also hypothesize that CAC will result in measurable allergen transport (Phl p 5) to the nasal cavity via the nasolacrimal duct, which is associated with activation of nasal mucosal immune responses in the absence of direct nasal allergen exposure.

Inclusion criteria

All participants must be:

• A volunteer between the ages of 18 to 70 years of age.
• Able to understand and willing to provide written informed consent.
• Able and willing to comply with study requirements.
• If the participant is a person of childbearing potential, they must practice abstinence or use a medically acceptable method of birth control and produce a negative urine pregnancy test at Visit 1, Visit 2, and Visit 3 (only non-allergic participants will require a pregnancy testing at Visit 3).

To be enrolled as an allergic participant, participants must:

• Have a minimum 2-year history of grass-specific allergic rhinoconjunctivitis symptoms upon exposure to the relevant allergen, documented by medical history review at Visit 1.
• Have a positive skin prick test response to Timothy grass allergen, defined as a wheal diameter ≥ 5 mm compared to the negative control wheal. This test must be performed by the study team either at the Visit 1 or historically within 1 year of Visit 1 at our research site.
• Have a reported ocular itch ≥2, self-reported ocular redness ≥2, and ophthalmologist/optometrist confirmation of ocular redness (using slit lamp) ≥2 following CAC at Visit 1.

To be enrolled as a non-allergic participant, participants must:

• Produce a negative skin prick test response to a panel of relevant aeroallergens tested at Visit 1 or within 1 year prior to Visit 1 at our research site.
• Produce a negative CAC, defined by an ocular itch = 0, self-reported ocular redness ≤1, and ophthalmologist/optometrist confirmation of ocular redness (using slit lamp) ≤1 after 10 minutes in response to the lowest (1:512), moderate (1:32) and highest (1:4) concentrations of allergen at Visit 1.

Exclusion criteria

Participants presenting with any of the following will not be included in the study:

• Participant has a history of any disease or disorder that, in the judgement of the Principal Investigator, would impact on participant's safety or the results of the study.
• Participant has a significant history of alcohol or drug abuse in the judgment of the Principal Investigator or delegate.
• Participant is pregnant, lactating, or actively trying to become pregnant.
• Participant is unable to comply with the washout periods for restricted medications, contact lens use, and smoking.
• Participant has signs/symptoms of active seasonal AR or is allergic to a seasonal allergen that is present in the outdoor environment during the time of the screening and CAC visits and which the Principal Investigator judges would impact the outcome of the study. If the schedule allows the participant can be re-scheduled for the visit outside the allergy season.
• Participant has any structural nasal abnormalities, nasal polyps on examination, or a history of frequent nose bleeding, as determined by a nasal examination at screening and prior to the CAC, in the judgement of the Principal Investigator or delegate.
• Participant has a history or clinically significant findings during the ocular examination of ocular abnormalities (e.g., meibomian gland dysfunction, moderate to severe dry eyes, cicatrizing conjunctivitis, glaucoma) that may affect the outcome of the study in the judgement of the Investigator.
• Participant has abnormalities detected on physical examination considered by the Principal Investigator to be clinically significant.
• Participant has undergone nasal surgery within the 3 months before Visit 1.
• Participant has undergone ocular surgery within the 3 months before Visit 1.
• Participant has experienced or exhibits any signs or symptoms of an upper respiratory tract infection within 14 days prior to any visit.*
• Participant reports a TNSS ≥4 prior to the titration challenge at Visit 1 or immediately prior to allergen challenge at Visit 2, as per PI judgement.**
• Participant reports ocular itch > 0 and ocular redness > 1 and ophthalmologist/optometrist reported redness > 1 (using slit lamp) in either eye prior to allergen challenge at any visit.
• Participant reports a TNSS change > 2 from baseline, after the negative control and diluent challenge at Visit 1.
• Participant reports ocular itching > 0 or ocular redness > 1, or ophthalmologist/optometrist reported redness >1 (via slit lamp) following challenge with the negative control and diluent control.
• Participant has a history of allergen induced asthma upon exposure to grass allergen, unless well controlled on low dose inhaled corticosteroids or when required (PRN) inhaled corticosteroid/long-acting beta-agonist as per Principal Investigator judgement.
• Participants with asthma requiring the use of a short-acting beta agonist greater than twice a week (unless for viral or execise induced asthma) or with severe asthma requiring maintenance high dose of inhaled or oral corticosteroids or biologic therapy (Omalizumab/Tezepelumab/Dupilumab/Mepolizumab/Benralizumab).
• Participant is currently receiving allergen specific immunotherapy to Timothy grass allergen or concluded a course of grass immunotherapy in the last 3 years.
• Participant has a history of positive test results for to human immunodeficiency viruses (HIV), Tuberculosis (not due to vaccination), Hepatitis B (not due to vaccination) or Hepatitis C.
• Participant has received an investigational product within the previous 30 days.
• Participant is unable and/or unlikely to comprehend and/or follow the protocol over the duration of the study.
• Participant is unwilling to attend study visits or adhere to the study protocol, in the judgement of the Principal Investigator.
• Participant has a known hypersensitivity to any excipient in the study formulation.
• Participant has a history of a severe systemic allergic reaction (e.g., anaphylaxis requiring emergency treatment) to Timothy grass or any grass pollen immunotherapy.
• Participant is currently receiving treatment for acne (e.g., isotretinoin) or has concluded less than 1 month prior to Visit 1.

• Participant may be rescheduled once respiratory infection is cleared **If TNSS≥ 4, participant may be re-booked if appropriate and the schedule permits.