Sex differences in senescence burden within human osteoarthritic synovial fibroblasts

Female synovial fibroblasts show higher levels of senescence markers and a reduced ability to handle oxidative stress, which may help explain the increased risk of osteoarthritis in women.

Summary and findings

This study measured the senescence burden in osteoarthritic human synovial fibroblasts from 10 male and 10 female donors. It was found that fibroblasts from female donors exhibited higher levels of senescence-associated proteins compared to males. The study aimed to understand the role of biological sex in osteoarthritis risk.

Abstract

<h4>Objective</h4> Cellular senescence has been shown to underlie many age-related diseases, including osteoarthritis (OA). In addition to age, biological sex is an OA risk factor with females at greater risk of hand and knee OA. We profiled the senescence burden in OA human synovial fibroblasts while accounting for these factors to understand how senescence may contribute to the increased burden of OA in females. <h4>Methods</h4> Synovial fibroblasts were isolated from tissue obtained at knee arthroplasty for OA from 10 male and 10 female donors. Single cell multiplexed immunofluorescence imaging was used to profile the senescence burden in samples age-matched to account for the differences in chronological age. Clustering was performed using stability and generalizability scoring. <h4>Results</h4> Independent of chronological age, OA synovial fibroblasts from female donors showed higher levels of senescence associated proteins p16, p21, p53, phospho-p65, IL-6, and IL-8. Assessment of oxidative stress associated proteins NRF2, SEPP1, NQO1 and TXNIP indicated a lower capacity for female cells to respond to oxidative stress. Clustering analysis revealed male and female enriched clusters. The female-enriched clusters showed higher levels of senescence-associated proteins and an increased oxidative stress response. <h4>Conclusions</h4> OA synovial fibroblasts from female donors demonstrated higher levels of senescence associated markers, lower ability to respond to oxidative stress, and increased senescence with increasing age. These findings indicate that female synovial fibroblasts are more likely to show markers of senescence and oxidative stress, suggesting senescence can contribute to the increased incidence of osteoarthritis in women.

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