Age-related self-DNA accumulation may accelerate arthritis in rats and in human rheumatoid arthritis.

The incidence of rheumatoid arthritis (RA) is increasing with age. DNA fragments is known to accumulate in certain autoimmune diseases, but the mechanistic relationship among ageing, DNA fragments and RA pathogenesis remain unexplored. Here we show that the accumulation of DNA fragments, increasing with age and regulated by the exonuclease TREX1, promotes abnormal activation of the immune system in an adjuvant-induced arthritis (AIA) rat model. Local overexpression of TREX1 suppresses synovial inflammation in rats, while conditional genomic deletion of TREX1 in AIA rats result in higher levels of circulating free (cf) DNA and hence abnormal immune activation, leading to more severe symptoms. The dysregulation of the heterodimeric transcription factor AP-1, formed by c-Jun and c-Fos, appear to regulate both TREX1 expression and SASP induction. Thus, our results confirm that DNA fragments are inflammatory mediators, and TREX1, downstream of AP-1, may serve as regulator of cellular immunity in health and in RA.

Exploring SARS-CoV-2 Delta variant spike protein receptor-binding domain (RBD) as a target for tanshinones and antimalarials.

The interaction of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor-binding domain (RBD) of spike protein with angiotensin-converting enzyme 2 (ACE2) mediates cell invasion. While this interaction mechanism is conserved, the RBD is affected by amino acid mutations in variants such as Delta and Omicron, resulting in enhanced transmissibility and altered ligand binding. Tanshinones are currently investigated as multi-target antiviral agents, but the studies were limited to the original SARS-CoV-2. This study aims at investigating the interaction of tanshinones with the Delta RBD. Chloroquine, methylene blue and pyronaridine, antimalarials previously identified as SARS-CoV-2 RBD binders, were studied for reference. Docking indicated the best scores for tanshinones, while bio-layer interferometry and molecular dynamics highlighted methylene blue as the best Delta RBD binder, although with decreased affinity with respect to the original strain.

Saponins isolated from Radix polygalae extent lifespan by modulating complement C3 and gut microbiota.

With the increase in human lifespan, population aging is one of the major problems worldwide. Aging is an irreversible progressive process that affects humans via multiple factors including genetic, immunity, cellular oxidation and inflammation. Progressive neuroinflammation contributes to aging, cognitive malfunction, and neurodegenerative diseases. However, precise mechanisms or drugs targeting age-related neuroinflammation and cognitive impairment remain un-elucidated. Traditional herbal plants have been prescribed in many Asian countries for anti-aging and the modulation of aging-related symptoms. In general, herbal plants' efficacy is attributed to their safety and polypharmacological potency via the systemic manipulation of the body system. Radix polygalae (RP) is a herbal plant prescribed for anti-aging and the relief of age-related symptoms; however, its active components and biological functions remained un-elucidated. In this study, an active methanol fraction of RP containing 17 RP saponins (RPS), was identified. RPS attenuates the elevated C3 complement protein in aged mice to a level comparable to the young control mice. The active RPS also restates the aging gut microbiota by enhancing beneficial bacteria and suppressing harmful bacteria. In addition, RPS treatment improve spatial reference memory in aged mice, with the attenuation of multiple molecular markers related to neuroinflammation and aging. Finally, the RPS improves the behavior and extends the lifespan of C. elegans, confirming the herbal plant's anti-aging ability. In conclusion, through the mouse and C. elegas models, we have identified the beneficial RPS that can modulate the aging process, gut microbiota diversity and rectify several aging-related phenotypes.