Abstract
Purpose :
Ocular surface (OS) conditions such as dry eye (DE) and Keratoconus(KC) are known to be immune-mediated. However, the relationship of trafficking immune cell types with these conditions in humans is underexplored. Hence, we studied the immune cell subsets on the OS of these patients.
Methods :
OS immune cells were collected using sterile saline from healthy control subjects (Ctrls, 37 eyes), evaporative DE (EDE, 16 eyes), aqueous-deficient DE (ADE, 16 eyes), ADE- Stevens-Johnson syndrome (ADE-SJS, 20 eyes) and KC (61 eyes) patients with prior informed consent and ethics committee approval. Patients underwent vision testing, Schirmers test I (ST), TBUT, OSDI scoring and corneal topography imaging. OS immune cells collected were stained with antibodies for leukocytes(CD45), T cells(CD3), neutrophils(CD66b), macrophages(CD163), Natural Killer cells(CD56), NKT cells(CD3+ CD56+) gamma delta T cells(gdT), and analysed by flow cytometry.
Results :
CD45+ cells were significantly (*P<0.05) higher in ADE/ADE-SJS compared to EDE, KC and Ctrls. Significantly higher CD66b+(Total/Hi) was observed in ADE/ADE-SJS and EDE but not in KC compared to Ctrls, and were significantly lower in EDE and KC compared ADE-SJS. Significantly higher CD163+ was observed in ADE. CD56+(Total/Low/Hi) cells were lower in ADE/ADE-SJS, EDE and KC. CD56+ levels were significantly lower than ADE/ADE-SJS compared to KC. Significantly higher levels of gdT cells was observed in ADE-SJS and advanced grade of KC (3/4) compared to Ctrls. CD56+ cells correlated inversely with OSDI(*r= -0.574), and positively with TBUT(*r=0.442) and ST(*r=0.295). CD66b+ cells correlated directly to OSDI(*r =0.554) but inversely to TBUT(*r=-0.517) and ST(*r=-0.682). CD45+ and gdT cells inversely correlated with ST(*r=-0.445 and *r=-0.271, respectively). Significantly higher levels of CD3+, gdT cells and NKT cells, and lower levels of CD56+low and CD56+hi cells were observed in higher grades of KC(≥2) compared to Ctrls. Significantly lower levels of CD66b+low cells were observed in all grades of KC.
Conclusions :
Increased activated neutrophils, gdT cells and decreased NK cells are associated with DE types and severity. Lower quiescent neutrophils and NK cells but higher gdT and NKTs were associated with KC severity. Thus, suggesting the role of distinct immune cells in OS disease pathobiology.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.