Younger Age of First Exposure to Soccer Heading is Associated with Decreased MicroRNA‐7844‐5p

Abstract

Younger age of first exposure (AFE) to American football has been associated with later‐life cognitive deficits in former National Football League players experiencing cognitive and behavioral deficits, but not in other cohorts of high school, college, amateur, or professional contact/collision sports athletes. Although several studies evaluated clinical outcomes, limited information exists among these cohorts and subclinical measures, such as blood biomarkers may serve as an early indicator of future impairments. Extracellular vesicles, including exosome‐like vesicles (ELVs), are released from cells and contain a variety of molecular cargo from the originating cell, and have emerged as reliable biomarker candidates. OBJECTIVE The purpose of this study was to compare plasma ELV concentration, size, and microRNA (miRNA) levels between soccer players reporting AFE to soccer heading before age 10 years (AFE≤10) and soccer players reporting AFE to soccer heading after age 10 years (AFE>10). METHODS College‐aged soccer players self‐reported AFE to soccer heading. Participants were divided into two groups based on their responses: AFE>10 (n=9, 5 males, 12.33±0.24 years) and AFE≤10 (n=18, 11 males, 7.94±0.46 years). Plasma ELV concentration and size were assessed using nanoparticle tracking analysis. Total RNA was isolated from ELVs, followed by performing miRNA first strand cDNA synthesis and subsequently qPCR. Comparisons were made via unpaired t‐test (p<0.05). RESULTS Data are presented as mean ± SE. AFE≤10 was associated with decreased miR‐7844‐5p when compared to AFE>10 (~60%, p=0.03). No changes in miRNA were observed for miR‐92b‐5p, miR‐423‐5p, miR‐24‐3p, miR‐144‐5p, miR‐221‐5p, and miR‐22‐3p. Groups did not differ in concentration (AFE≤10, 8.34 ×109 ELVs/ml plasma ±0.96 ×109 vs AFE>10, 8.39 ×109 EVs/ml plasma ±0.98 ×109) or size (AFE≤10, 117.58 nm ±7.12 vs AFE>10, 106.40 nm ±4.14) of circulating ELVs. CONCLUSION Collectively these data demonstrate that younger AFE to soccer heading was associated with decreased circulating miR‐7844‐5p. Decreased circulating miR‐7844‐5p may be an early indicator of future pathology. Support or Funding Information Supported by NIH‐NINDS R01 NS102157‐01, NIH P20 GM113125, NIH P20 GM103446, NIH R03 HD094594