BACKGROUND: SARS-CoV-2 invades mitochondria of infected cells resulting in disordered metabolism, mitophagy, and abnormal levels of mitochondrial proteins in extracellular vesicles. Blood extracellular vesicle SARS-CoV-2 proteins and mitochondrial proteins were quantified in COVID-19 to assess possible roles as biomarkers. METHODS: Total extracellular vesicles were precipitated from blood of age- and gender-matched participants with no infection (n=10), acute COVID-19 (n=16), post-acute sequelae of COVID-19 (PASC or long COVID) (n=30), or post-acute COVID without PASC (n=8) and their extracted proteins quantified by enzyme-linked immunosorbent assays (ELISAs). RESULTS: Total extracellular vesicle levels of S1 (receptor-binding domain [RBD]) protein were significantly higher in acute infections than in uninfected controls, post-acute infection without PASC, and PASC. Total extracellular vesicle levels of nucleocapsid (N) protein were significantly higher in PASC than in uninfected controls, acute infections, and post-acute infection without PASC. Neither acute levels of S1(RBD) or N proteins predicted progression to PASC. Levels of neither SARS-CoV-2 protein in established PASC correlated with neuropsychiatric manifestations. Significant decreases in total extracellular vesicle levels of the mitochondrial proteins MOTS-c, VDAC-1, and humanin, and elevations of levels of SARM-1 were observed in acutely infected patients who would develop PASC. Significant decreases in total extracellular vesicle levels of MOTS-c and humanin, but not VDAC-1, and elevations of total extracellular vesicle levels of SARM-1 were characteristic of PASC patients with neuropsychiatric manifestations. CONCLUSIONS: Total extracellular vesicle levels of SARS-CoV-2 proteins in COVID-19 indicate intracellular presence of SARS-CoV-2. Abnormal total extracellular vesicles levels of mitochondrial proteins in acute infections predict a high risk of PASC and later in established PASC are indicative of neuropsychiatric manifestations.

OBJECTIVE: Mitochondrial impairments have been implicated in the pathogenesis of Fragile X-associated tremor/ataxia syndrome (FXTAS) based on analysis of mitochondria in peripheral tissues and cultured cells. We sought to assess whether mitochondrial abnormalities present in postmortem brain tissues of patients with FXTAS are also present in plasma neuron-derived extracellular vesicles (NDEVs) from living carriers of fragile X messenger ribonucleoprotein1 (FMR1) gene premutations at an early asymptomatic stage of the disease continuum. METHODS: We utilized postmortem frozen cerebellar and frontal cortex samples from a cohort of eight patients with FXTAS and nine controls and measured the quantity and activity of the mitochondrial proteins complex IV and complex V. In addition, we evaluated the same measures in isolated plasma NDEVs by selective immunoaffinity capture targeting L1CAM from a separate cohort of eight FMR1 premutation carriers and four age-matched controls. RESULTS: Lower complex IV and V quantity and activity were observed in the cerebellum of FXTAS patients compared to controls, without any differences in total mitochondrial content. No patient-control differences were observed in the frontal cortex. In NDEVs, FMR1 premutation carriers compared to controls had lower activity of Complex IV and Complex V, but higher Complex V quantity. INTERPRETATION: Quantitative and functional abnormalities in mitochondrial electron transport chain complexes IV and V seen in the cerebellum of patients with FXTAS are also manifest in plasma NDEVs of FMR1 premutation carriers. Plasma NDEVs may provide further insights into mitochondrial pathologies in this syndrome and could potentially lead to the development of biomarkers for predicting symptomatic FXTAS among premutation carriers and disease monitoring.

Fragile X (FMR1) premutation is a common mutation that affects about 1 in 200 females and 1 in 450 males and can lead to the development of fragile-X-associated tremor/ataxia syndrome (FXTAS). Although there is no targeted, proven treatment for FXTAS, research suggests that sulforaphane, an antioxidant present in cruciferous vegetables, can enhance mitochondrial function and maintain redox balance in the dermal fibroblasts of individuals with FXTAS, potentially leading to improved cognitive function. In a 24-week open-label trial involving 15 adults aged 60-88 with FXTAS, 11 participants successfully completed the study, demonstrating the safety and tolerability of sulforaphane. Clinical outcomes and biomarkers were measured to elucidate the effects of sulforaphane. While there were nominal improvements in multiple clinical measures, they were not significantly different after correction for multiple comparisons. PBMC energetic measures showed that the level of citrate synthase was higher after sulforaphane treatment, resulting in lower ATP production. The ratio of complex I to complex II showed positive correlations with the MoCA and BDS scores. Several mitochondrial biomarkers showed increased activity and quantity and were correlated with clinical improvements.