Expression of IL-8, IL-6 and IL-1β in tears as a main characteristic of the immune response in human microbial keratitis.

Concepcion Santacruz,Sonia Perez-Tapia,Lenin Pavon,Luisa Loustaunau,Marisela Linares,Yonathan Garfias,Maria Jimenez-Martinez

doi:10.3390/ijms16034850

Abstract

Corneal infections are frequent and potentially vision-threatening diseases, and despite the significance of the immunological response in animal models of microbial keratitis (MK), it remains unclear in humans. The aim of this study was to describe the cytokine profile of tears in patients with MK. Characteristics of ocular lesions such as size of the epithelial defect, stromal infiltration, and hypopyon were analyzed. Immunological evaluation included determination of interleukine (IL)-1β, IL-6, IL-8, IL-10, IL-12 and tumor necrosis factor (TNF)-α in tear samples obtained from infected eyes of 28 patients with MK and compared with their contralateral non-infected eyes. Additionally, frequency of CD4+, CD8+, CD19+ and CD3−CD56+ cells was also determined in peripheral blood mononuclear cells in patients with MK, and compared with 48 healthy controls. Non-significant differences were observed in the size of the epithelial defect, stromal infiltration, and hypopyon. Nevertheless, we found an immunological profile apparently related to MK etiology. IL-8 > IL-6 in patients with bacterial keratitis; IL-8 > IL-6 > IL-1β and increased frequency of circulating CD3−CD56+ NK cells in patients with gram-negative keratitis; and IL-8 = IL-6 > IL-1β in patients with fungal keratitis. Characterization of tear cytokines from patients with MK could aid our understanding of the immune pathophysiological mechanisms underlying corneal damage in humans.

Highlights

Corneal infections are frequent and potentially vision-threatening diseases; Prompt diagnosis and optimal treatment are necessary to prevent devastating outcomes
The most frequent causative microorganism of fungal keratitis was Fussarium spp.; Gram-positive bacterial keratitis was caused by Streptococcus spp.; While gram-negative bacterial keratitis was originated by Pseudomonas spp. (See Table 1)
All patients included in this study had a relevant medical history that was related to microbial keratitis (See Table 1, and Tables S1–S3)

Summary

Introduction

Corneal infections are frequent and potentially vision-threatening diseases; Prompt diagnosis and optimal treatment are necessary to prevent devastating outcomes. Many studies have emphasized the importance of determining the epidemiological profile and performing microbial identification with regard to describing the predisposing factors to develop microbial keratitis (MK) [3,4,5,6] Factors such as trauma, contact lens wear, dry eye, ocular surface disorders and immunosuppression may alter the immune defense mechanisms of the outer eye, and permit microorganisms to invade the cornea [7]. MK is a rare condition in the absence of risk factors, 1.5–2 millions of new cases arise globally, and its presentation is considered a silent epidemic [8]. This is likely to be the case in countries, such as India, where the incidence of MK is ten times more frequent compared to the United States [9]

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