Correlation of hair cortisol and interleukin 6 with structural change in the active progression of keratoconus.

PURPOSE

To evaluate interleukin (IL) and hair cortisol concentrations (HCCs) in progressive keratoconus (KC) and compare them with KC-stable eyes and healthy control, and to determine the correlation of these inflammatory mediators and HCCs and their relationship with structural damage represented by increased corneal curvature.

SETTING

University of Sao Paulo, Brazil.

DESIGN

Prospective observational comparative study.

METHODS

133 eyes of 74 patients were included. The concentrations of tear cytokines: IL1B, IL6, IL8, IL10, IL12p70, and tumor necrosis factor α were obtained by capillary flow and measured using a flow cytometer. HCCs were determined from the most proximal hair segment as an index of cumulative secretion and measured by liquid chromatography mass spectrometry.

RESULTS

133 eyes of 74 patients. Only IL6 was increased in progressive KC tears compared with stable KC (6.59 ± 3.25 pg/mL vs 4.72 ± 1.91 pg/mL; P < .0001) with a positive correlation between IL6 and maximum keratometry (Kmax) (P < .0001). Progressive KC exhibited significantly higher HCC than stable KC (0.624 ± 0.160 ng/mg vs 0.368 ± 0.0647 ng/mg; P < .0001) and healthy controls (0.624 ± 0.160 ng/mg vs 0.351 ± 0.0896 ng/mg; P < .0001). There was a significant correlation between HCC and Kmax (P < .0001).

CONCLUSIONS

KC eyes that are progressing have a higher concentration of IL6 and long-term cortisol than patients with stable forms of KC; second, there is a significant correlation between this increase in IL6 and cortisol with corneal structural damage. Finally, there is a meaningful relationship between this interleukin and the previous few months' cortisol levels.