This work extrapolates to humans the previous animal studies on blood heterochronicity and establishes a novel direct measurement of biological age. Our results support the hypothesis that, similar to mice, human aging is driven by age-imposed systemic molecular excess, the attenuation of which reverses biological age, defined in our work as a deregulation (noise) of 10 novel protein biomarkers. The results on biological age are strongly supported by the data, which demonstrates that rounds of therapeutic plasma exchange (TPE) promote a global shift to a younger systemic proteome, including youthfully restored pro-regenerative, anticancer, and apoptotic regulators and a youthful profile of myeloid/lymphoid markers in circulating cells, which have reduced cellular senescence and lower DNA damage. Mechanistically, the circulatory regulators of the JAK-STAT, MAPK, TGF-beta, NF-κB, and Toll-like receptor signaling pathways become more youthfully balanced through normalization of TLR4, which we define as a nodal point of this molecular rejuvenation. The significance of our findings is confirmed through big-data gene expression studies.

Many patients with COVID-19 experience a range of debilitating symptoms months after being infected, a syndrome termed long-haul COVID. A 68-year-old male presented with lung opacity, fatigue, physical and cognitive weaknesses, loss of smell and lymphocytopenia. After rounds of therapeutic plasma exchange (TPE), the patient returned to normal activities and work. Mechanistically in the patient's peripheral blood mononuclear cells (PBMCs), markers of inflammatory macrophages diminished and markers of lymphocytes, including natural killer (NK) cells and cytotoxic CD8 T-cells, increased. Circulating inflammatory proteins diminished, while positive regulators of tissue repair increased. This case study suggests that TPE has the capacity to treat long-haul COVID.