Cytokine expression profile in tears of COVID-19 patients
Purpose
To study the local immune response to SARS-CoV-2 by evaluating tear cytokine expression profile in COVID-19 patients.
Methods
We enrolled 90 COVID-19 patients (30 each mild/moderate/severe disease) and 30 healthy controls. Baseline tears and conjunctival swabs of COVID-19 patients were collected during their hospitalization, within < 2 days of their blood sample collection. Conjunctival swabs were subjected to quantitative RT-PCR. Tear cytokines IL-2, IL-4, IL-6, IL-10, TNF, IFN-γ and IL-17 were measured using BDTM Cytometric Bead Array kit.
Results
TNF was significantly higher and IL-4 lower in tears of COVID-19 patients versus healthy controls, with similar differential expression in serum. IL-6 (upto 215.4 pg/mL) and IL-10 (upto 81.8 pg/mL) were the most abundant cytokines in tears of COVID-19 patients. IL-6 was also higher in ‘severe’ disease, both in tears (significantly, p=0.026) and serum (not significant, p= 0.547). IL-17 was significantly (p=0.022) higher in tears collected within 1-7 days of disease onset, as compared to samples collected later. Six (6.7%) conjunctival swabs were positive for RT-PCR.
Conclusion
High TNF and low IL-4 expression in both tears and peripheral blood provides an opportunity to explore the immunological behaviour of tears in COVID-19. High IL-6 levels in ‘severe’ disease and high tear IL-17 in ‘early’ disease (with reduced serum levels) may indicate their increased local production, influenced by disease duration and severity, and help in understanding the role of ocular surface in COVID-19.
Conflict of interest
No
Authors 1
Last name
BANSAL
Initials of first name(s)
R
Department
Ophthalmology, PGIMER
City
Chandigarh
Country
India
Authors 2
Last name
punniyamurthy
Initials of first name(s)
A
Department
Biochemistry, PGIMER
City
Chandigarh
Country
India
Authors 3
Last name
Verma
Initials of first name(s)
I
Department
Biochemistry, PGIMER
City
Chandigarh
Country
India
Authors 4
Last name
Gupta
Initials of first name(s)
V
Department
Ophthalmology, PGIMER
City
Chandigarh
Country
India
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