Different Effects of Pro-Inflammatory Factors and Hyperosmotic Stress on Corneal Epithelial Stem/Progenitor Cells and Wound Healing in Mice

Abstract

Chronic inflammation and severe dry eye are two important adverse factors for the successful transplant of cultured limbal stem cells. The aim of this study was to investigate the effects of inflammation and hyperosmotic stress (a key pathological factor in dry eye) on corneal epithelial stem cells (CESCs) and corneal epithelial wound healing. We observed that the CESCs exhibited significant morphological changes when treated with interleukin‐1 beta (IL‐1β), tumor necrosis factor alpha (TNF‐α), or hyperosmotic stress. Colony‐forming efficiency or colony‐forming size was decreased with the increasing concentrations of IL‐1β, TNF‐α, or hyperosmotic stress, which was exacerbated when treated simultaneously with pro‐inflammatory factors and hyperosmotic stress. However, the colony‐forming capacity of CESCs recovered more easily from pro‐inflammatory factor treatment than from hyperosmotic stress treatment. Moreover, when compared with pro‐inflammatory factors treatment, hyperosmotic stress treatment caused a more significant increase of apoptotic and necrotic cell numbers and cell cycle arrest in the G2/M phase. Furthermore, the normal ability of corneal epithelial wound healing in the mice model was suppressed by both pro‐inflammatory factors and hyperosmotic stress treatment, and especially severely by hyperosmotic stress treatment. In addition, inflammation combined with hyperosmotic stress treatment induced more serious epithelial repair delays and apoptosis in corneal epithelium. Elevated levels of inflammatory factors were found in hyperosmotic stress‐treated cells and mice corneas, which persisted even during the recovery period. The results suggested that pro‐inflammatory factors cause transient inhibition, while hyperosmotic stress causes severe apoptosis and necrosis, persistent cell cycle arrest of CESCs, and severe corneal wound healing delay. Stem Cells Translational Medicine 2019;8:46–57

The proinflammatory cytokines IL‐1β and TNF‐α modulate corneal epithelial wound healing through p16Ink4a suppressing STAT3 activity

“…Mounting evidence has shown that proinflammatory cytokines, particularly interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), are involved in inflammation, immunity, tissue repair, and cancer (Aarreberg et al, 2019;Bachus et al, 2019;Balkwill, 2009;Gomez et al, 2018;Johnson, O'Keefe, & Grandis, 2018;Kang, Tanaka, Narazaki, & Kishimoto, 2019;Stock, Jama, Hansen, & Wicks, 2019). In the cornea, proinflammatory cytokines are pleiotropic, wherein they are associated with corneal immune response, angiogenesis, chemotaxis, wound healing, and corneal diseases (Torres & Kijlstra, 2001;Wilson et al, 2001;Yang et al, 2019). A recent study has reported that IL-1β is elevated and IL-1 receptor antagonist (IL-1Ra) is suppressed in diabetic corneas, and an imbalance in IL-1β and IL-1Ra levels causes delayed corneal epithelial wound healing (Yan et al, 2016).…”

Antiapoptotic Properties of Mesenchymal Stem Cells in a Mouse Model of Corneal Inflammation

“…To confirm the published observations that proinflammatory cytokines induce apoptosis in corneal cells [3,4], the corneal explants were cultured with IL-1b, IFN-g, and TNF-a, or with H 2 O 2 as an inductor of apoptosis [18]. After a 48-h cultivation, the expression of genes for antiapoptotic molecule Bcl-1 and for proapoptotic molecules Bax and p53 was determined by RT-PCR.…”

“…It has been shown that cells of the damaged cornea produce proinflammatory molecules, such as interleukin-la (IL-1a), IL-1b, and tumor necrosis factor-a (TNF-a) [1,2]. It has been demonstrated that increased levels of proinflammatory cytokines lead to apoptosis in in vivo and in vitro models [3,4].…”

Mesenchymal Stem Cell-Based Therapy for Retinal Degenerative Diseases: Experimental Models and Clinical Trials

“…These molecules can be produced either by inflammatory immune cells or by the activated cells of the retina [ 57 ]. It has been shown in vitro and in vivo that increased levels of proinflammatory cytokines can induce apoptosis of the surrounding cells [ 58 , 59 ]. Moreover, chronic inflammation is associated with endoplasmic reticulum stress, which also promotes the induction of apoptosis [ 60 ].…”