Identification of Inflammasome Pathway Biomarkers in Human Tears

Abstract

Purpose : The inflammasome pathway is implicated in systemic disorders and various eye diseases, including dry eye, glaucoma, and age-related macular degeneration. Tears offer a noninvasive source of biomarkers, and we hypothesize that inflammasome pathway biomarkers, particularly mtDNA, can be identified in tears. We propose a pilot study to identify biomarkers from the inflammasome pathway in tear samples collected with Schirmer strips.

Methods : Tear samples were collected from 7 eyes from 5 healthy subjects (n=7) using filter papers with the Schirmer I test without anesthesia. The strips were eluted with ddH₂O at room temperature. Both the protein and DNA were isolated from the tear samples. Then Western blotting was performed using the pro-Caspase 1 antibody to determine the presence of the inflammasome marker. The mtDNA was measured by qRT-PCR using 18S as the nuclear reference gene and MT-ND2 as the mitochondrial DNA target.

Results : mtDNA was present in 3 out of 7 eyes, with two showing upregulated pro-Caspase 1, a pro-inflammatory cytokine involved in the apoptosis cascade.

Conclusions : The identification of mtDNA in human tears, coupled with elevated levels of pro-inflammatory biomarkers supports our hypothesis that the inflammasome pathway can be accessed and studied through tear analysis. Further studies are required comparing healthy eyes vs. inflammatory and non-inflammatory eye diseases to elucidate the inflammasome pathway’s role. We expect that these findings may serve as a biomarker to diagnose, follow up, and potentially treat various eye conditions.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Relative mtDNA Copy Number (qRT-PCR) in 3 out of 7 eyes from 5 healthy subjects. Eyes that did not demonstrate mtDNA presence are not shown (tears samples 1, 2, 3, and 6).

 

pro-Caspase 1 level (Western blot) with results normalized to the tear sample 7 levels. Eyes that did not demonstrate pro-Caspase 1 presence are not shown (tears samples 1, 2, 3, and 4).