Effect of Interleukin 6 on Scleral Fibroblast Proliferation, Differentiation, and Apoptosis Involved in Myopic Scleral Remodeling.

INTRODUCTION: Scleral hypoxia (HO) is present in myopic eyes, and interleukin (IL)-6 is increased in the aqueous humor of patients with high myopia. The aim of this study was to investigate the effects of IL-6 on scleral fibroblast proliferation, differentiation, and apoptosis under conditions of HO and the possible role of IL-6 in myopic scleral remodeling. METHODS: Primary human scleral fibroblasts (HSFs) were cultured using a tissue mass adherent method. First, cells were cultured under conditions of HO (2% O2) or normoxia (NO, 20% O2) for different times. A quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence were used to detect the expression of IL-6 in HSFs. Next, cells were divided into five groups: NO, HO, HO plus IL-6, HO plus IL-6 receptor inhibitor (IL6RI), and HO plus IL-6 and IL6RI. The groups were treated separately for 72 h. Cell counting kit-8 assay and flow cytometry were used to detect cell proliferation and apoptosis, respectively. Western blotting and qRT-PCR were used to detect the expression of various genes in the transforming growth factor-ß1/Smad2/matrix metalloproteinase-2 pathway; these methods and immunofluorescence were also used to detect transdifferentiation of HSFs. RESULTS: HO resulted in upregulation of IL-6 expression in HSFs. Compared with NO, HO resulted in diminished cell proliferation and increased apoptosis and differentiation in HSFs; the above trend was further enhanced by the addition of IL6RI. Compared with the HO group, the addition of IL-6 led to a decrease in cell proliferation and an increase in apoptosis and differentiation of HSFs; the above trends showed opposite changes after the addition of both IL-6 and IL6RI. Additionally, IL-6 and IL6RI exerted opposite regulatory effects on the transforming growth factor-ß1/Smad2/matrix metalloproteinase-2 pathway under conditions of HO. CONCLUSION: HO caused HSFs to overexpress IL-6. IL-6 has a role in scleral remodeling in myopic eyes through affecting the proliferation, differentiation, and apoptosis of HSFs.