Effects of TGFB1 and 17 B estradiol on corneal stiffness and thickness

Background: Impaired corneal stiffness and transparency are the hallmarks of some of the leading global causes of corneal blindness diseases, such as keratoconus (KCN) which is characterized by central thinning and conical protrusion of cornea. The stiffness and transparency allow it to withstand internal and external pressure all the while maintaining transparency. These properties are attributable to corneal extracellular matrix (ECM) collagen which is the primary contributor of corneal stiffness. Several environmental, genetic and physiological factors including Transforming growth factor beta 1 (TGFB1) and hormones including 17B estradiol (E2) have been shown to directly or indirectly increase or decrease corneal collagen and thus corneal stiffness and thickness, but data on effects of TGFB1 on whole corneal tissue and its young modulus & thickness are minimal. While the effect of E2 on collagen deposition and resulsting stiffness have been studied in other parts of the body including cardiovascular system, its impact on corneal stiffness & thickness, is scarce. Clinical data suggest E2 impacts corneal thickness, vision and likely stiffness during pregnancy and menstrual cycle, though warrants further investigation and understanding. In case of individuals with preexisting KCN, the disease may progress leading to inversible visual impairment. Current therapeutic options are invasive and may not be suitable for all. Thus, there is a dire need to investigate the effects of E2 & TGFB1, a primary modulator corneal ECM, on corneal stiffness & thickness which could further our understand of normal and disease physiology and improve clinical management and prevention of disease progression. We thus decided to study the effects of TGFB1 & E2 of young’s modulus of corneal tissue, and corneal thickness using uniaxial extension and optical coherence tomography (OCT) respectively. Method: 1) To obtain young’s modulus, 10 freshly harvested porcine eyes were obtained and dissected to acquire central 6 mm wide full thickness corneal strips which were further divided into equal 3 mm wide strips, producing 2 strips from each eye. For 5 eyes, 1 strip from each eye was added to 2 ml control solution containing 2% dextran, 1% FBS in phenol free DMEM, and 1 strip in control solution + 10 ug/ml TGFB1. For other 5 eyes, the above process was repeated but the treatment was 2ml control solution+1 ng/ml E2. The strips were incubated at room temperature for 5 days. Uniaxial extension using dynamic mechanical analyzer was performed. The applied load & extension were used to produce Young's modulus using custom MATLAB scripts. 2) Separately, 14 freshly harvested intact porcine eye globes were analyzed for corneal thickness using OCT (initial reading & control). Damaged eyes were excluded. Afterwards the globes were placed in either TGFB1 (n=7) or E2 (n=7) treatement solutions as above for 48 hrs and the measurements were repeated to assess the differences in thickness. The results were analyzed using student’s T test. Results:1) TGFB1 & E2 decreased stiffness compared to control but the difference between control & TGFB1 treatment was not significant. E2 treatment significantly decreased corneal stiffness compared to TGFB1 and control (p< 0.001). 2) There was a significant increase in thickness of corneas treated with TGFB1 & E2 compared to control (p< 0.001). The corneas treated with TGFB1 were significantly thicker than those treated with E2 (P=0.02). Conclusion: We concluded TGFB1 may cause increase in thickness of corneas & E2 can make the corneas significantly less stiff. Our next steps focus on exploring the underlying cellular mechanisms for these changes. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.