P38-Mediated Cellular Senescence in Conjunctivochalasis Fibroblasts

Conjunctivochalasis (CCH) is a common ocular disease and has received extensive attention recently. However, its exact pathogenesis remains largely unknown. Owing to the high morbidity of CCH in older people, this study aimed to investigate whether cellular senescence contributes to CCH progression and the underlying mechanism.

Loose conjunctival tissues from CCH patients (n = 13) and normal conjunctival tissues from age-matched persons (n = 12) were obtained and the fibroblasts were separately induced and obtained. Cellular senescence, and the expression of senescence-associated genes (p53 and p21) and p38 in CCH conjunctival tissues and normal controls, were determined by senescence-associated β-galactosidase (SA-β-Gal) staining and quantitative (q)RT-PCR, respectively. To explore the effects of p38 on cellular senescence in CCH fibroblasts, small interfering RNA (siRNA) targeting p38 (siP38) and p38-specific inhibitor SB203580 was performed in CCH fibroblasts. Then, cellular senescence, cell viability, reactive oxygen species (ROS) production, and gene expression were detected according to the corresponding methods.

CCH conjunctival tissues had significantly more senescent cells, evidenced by more SA-β-Gal-positive cells, and higher expression of senescence-associated genes (p53 and p21) and p38. CCH fibroblasts transfected with siP38 or treated with SB203580 had obviously reduced numbers of senescent cells, decreased ROS production, and increased cell viability, as well as reduced expression of senescence-associated genes. Meanwhile, blocking p38 signaling decreased the expression of p53 and p21.

Therefore, these findings indicate that cellular senescence might be a causative factor for CCH. P38 signaling might play an important role in the progress of cellular senescence in CCH fibroblasts via manipulation of p53/p21 signaling.