Abstract
Purpose :
Ocular surface inflammation is a vital immune mechanism, activated in response to a variety of stress and a key driver of disease pathology. Inflammation and autophagy are often implicated in disease conditions but the molecular link between them is poorly studied. The aim of this study is to understand the regulation of inflammatory signaling pathway by using autophagy regulators trehalose (TRE) and chloroquine (CQ) on human corneal cells and blood derived immune cells.
Methods :
Acute inflammatory stress was simulated by treating human corneal epithelial cells (HCE) and peripheral blood mononuclear cells (PBMC) with recombinant TNFα for 2 hours. The regulation of TNFα induced inflammatory and autophagy gene expression and protein activation by TRE(80mM) and CQ(60nM) was studied and compared with Cyclosporine A (CsA). Optimal drug treatment concentrations were determined by dose escalation cytotoxicity studies. Gene expression was evaluated by quantitative PCR, while protein expression and functions were tested by immunoblotting and fluorescence imaging (Cyto-ID, Lysotracker Red).
Results :
TRE treatment reduced inflammation induced gene expression of IL-6(19.7%), MCP-1(24.8%), IL-8(58.3%), MMP-9 (2.02%), LC3(44.37%) and LAMP-1(56.8%) in HCE. In PBMCs, we did not observe significant changes in gene expression levels of inflammatory or autophagy markers by TRE. However, PBMC cells treated with CQ showed a decreasing trend in the gene expression levels of TNFα (37.5%), IL-6(37.9%), MCP-1(14.13%), MMP-9(7.14%), when compared to controls and CsA treatment. But, the CQ treatment did not alter autophagy genes significantly. Similar results were observed in HCE cells treated with CQ. LAMP1 and LC3 protein levels were altered significantly by TRE and to a lesser extent by CQ in both control and TNFα stimulated cells.
Conclusions :
The data demonstrate that TRE and CQ have distinct anti-inflammatory mechanisms in corneal cells and primary immune cells. This regulatory effect of TRE was more pronounced in HCE rather than PBMCs. Interestingly, CQ, an autophagy blocker, had a similar inflammation dampening effect in both HCE and PBMCs without significant changes in autophagy markers. Thus CQ might regulate inflammation in an autophagy independent manner. The data suggest new modalities for treating ocular surface inflammation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.