# New Clues to the Pathogenesis of Idiopathic Orbital Inflammation: Elevated IL‐8 and MCP‐1 in Tear Fluid

## TL;DR

This study finds higher levels of IL-8 and MCP-1 in tears of patients with idiopathic orbital inflammation, suggesting a new immunologic mechanism and potential biomarkers.

## Contribution

The study identifies elevated IL-8 and MCP-1 in tear fluid as potential biomarkers for idiopathic orbital inflammation.

## Key findings

- IL-8 and MCP-1 levels in tear fluid were significantly elevated in idiopathic orbital inflammation patients.
- Orbital tissues from IOI patients showed overexpression of IL-8 and MCP-1.
- Plasma levels of IL-8 and MCP-1 were not significantly different between IOI patients and controls.

## Abstract

To characterize tear cytokine profiles in patients with idiopathic orbital inflammation (IOI) and analyze the expression of altered cytokines in blood and involved tissues.

This case‐control study enrolled 18 IOI patients and 11 age‐/sex‐matched controls. Ocular Surface Disease Index (OSDI), corneal fluorescent staining, tear film breakup time (TBUT), Schirmer I test, and other clinical and laboratory parameters were obtained from all participants. Concentrations of cytokines in tear fluid, blood, and tissues were determined using a multiplex bead immunoassay system, enzyme‐linked immunosorbent assay, and immunohistochemistry.

Significantly elevated levels of interleukin (IL)‐8 and monocyte chemoattractant protein (MCP)‐1 (both p < 0.05) were found in IOI tear fluid. The area under receiver operating characteristic curve was 0.73 and 0.74 for IL‐8 and MCP‐1, respectively. IL‐8 and MCP‐1 were overexpressed in orbital tissues from patients with IOI, while the plasma levels of IL‐8 and MCP‐1 in the IOI group were parallel to the control group.

The dysregulation of tear cytokine profiles provides a new insight into the potential immunologic mechanism for IOI. The elevated IL‐8 and MCP‐1 may represent candidate biomarkers of IOI.