Shifting the IGF-axis: An age-related decline in human tear IGF-1 correlates with clinical signs of dry eye

Roshni Patel, Meifang Zhu, Danielle M. Robertson

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Objective: The human corneal epithelium expresses both the insulin-like growth factor type 1 receptor (IGF-1R) and the IGF-1R/insulin receptor (INSR) hybrid. Despite the previous identification of IGF-1 in human tear fluid, little is known regarding the regulation of IGF-1 in tear fluid and its role in corneal epithelial homeostasis. In the present study, we investigated the impact of biological parameters on the concentration of human tear levels of IGF-1. Design: Tear levels of IGF-1 were measured in 41 healthy, human volunteers without any reported symptoms of dry eye. All volunteers underwent standard biomicroscopic examination of the cornea and tear film. In a subgroup of volunteers, corneal staining with sodium fluorescein, tear film break up time and tear production using a Schirmer's test strip were measured to assess clinical signs of dry eye. Tears were collected from the inferior tear meniscus using glass microcapillary tubes and IGF-1 levels were measured using a solid phase sandwich ELISA. Results: Tear levels of IGF-1 were highest in young adults and significantly decreased in older adults (P = 0.003). There were no differences in tear IGF-1 between males and females (P = 0.628). Tear IGF-1 levels were correlated with tear film break up time (R = 0.738) and tear production (R = 0.826). Conclusions: These data indicate that there is a progressive decline in tear IGF-1 due to aging that is associated with clinical signs of dry eye. This effect is likely due to age-related changes in the lacrimal gland.

Original languageEnglish (US)
JournalGrowth Hormone and IGF Research
DOIs
StateAccepted/In press - Jan 1 2018

Keywords

  • Aging
  • Dry eye
  • IGF-1
  • Tears

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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