Leveraging microgravity to model metabolic aging in human peripheral blood mononuclear cells

Author

Alexander N. Chebykin, Dominican University of CaliforniaFollow

ORCID

https://orcid.org/0009-0006-1567-865X

Graduation Year

2025

Document Type

Master's Thesis

Degree

Master of Science

Program

Biological Science

Partner Organization

Buck Institute for Research on Aging

Program Director

Patti Culross, MD, MPH

First Reader

David Furman, PhD and Daniel A. Winer, MD

Second Reader

Taylor Valentino, PhD

Abstract

Exposure to microgravity (µG) during spaceflight or via ground-based analogs induces a physiological deterioration with features reminiscent of organismal aging but occuring at an accelerated rate. The immune system is particularly susceptible, showing parallels between aging and µG exposure, but the convergent cellular mechanisms underlying these parallel states of immune dysfunction remain poorly understood. We posit that exposure to simulated µG induces a metabolic phenotype in the immune cells that recapitulates metabolic signatures of immunosenescence. In this thesis, we compared the effects of aging, short-term (24 hours) simulated µG, and pro-inflammatory stimulation with lipopolysaccharide (LPS) on the energy metabolism of human peripheral blood mononuclear cells (PBMCs) from young (20-30 years old) and older (65+ years old) male human donors through the use of a flow cytometry-based single-cell energetic metabolism by profiling translation inhibition (SCENITH) method. These results demonstrated that chronological aging of many immune cell subsets is defined by a significant shift away from mitochondrial dependence for energy production. Daylong exposure to simulated µG induced a nearly identical metabolic phenotype in PBMCs from young donors. Metabolic states of both aged and µG-exposed PBMCs closely resembled the profile of acutely inflamed cells stimulated with LPS. These findings establish mitochondrial impairment as a hub linking the immunometabolic profiles of aging and µG exposure and suggest that the basal state of immune cells under these conditions is primed for inflammation.