Biological aging of different blood cell types

Area of Science:

• Gerontology
• Epigenetics
• Molecular Biology

Background:

• Biological age (BA) reflects age-related decline, with DNA methylation clocks and telomere length (TL) being key indicators.
• Whole blood, a common sample for aging studies, comprises diverse cell types, potentially influencing BA measurements.
• Previous research has not fully elucidated cell type-specific variations in BA indicators.

Purpose of the Study:

• To compare biological ages (BAs) across 12 distinct blood cell types.
• To assess cell type-specific associations between BA indicators and chronological age (CA).
• To investigate the impact of cell composition on BA measurements in aging research.

Main Methods:

• Analysis of DNA methylation-based BA indicators, including TL, cg16867657, Hannum, Horvath, DNAmPhenoAge, and DunedinPACE clocks.
• Utilized 428 biological samples from 12 different blood cell types.
• Compared BA values between cell types and whole blood, and assessed correlations with chronological age within each cell type.

Main Results:

• Significant differences in BA were observed between most blood cell types and whole blood (p < 0.05).
• DNAmPhenoAge exhibited the largest cell type differences (up to 44.5 years), while DNA methylation-based TL showed the smallest.
• T cells generally displayed younger BA, monocytes older BA, and most BA indicators correlated strongly with CA within cell types, except DunedinPACE.

Conclusions:

• DNA methylation-based BA indicators demonstrate distinct cell type-specific characteristics.
• Cellular composition significantly impacts BA measurements, necessitating consideration in aging studies and intervention assessments.
• Findings provide insights into epigenetic clock mechanisms and highlight the importance of accounting for cell types in aging research.