A leaky gut contributes to postural dysfunction in patients with Alzheimer's disease

Interconnections between the Gut Microbiome and Alzheimer's Disease: Mechanisms and Therapeutic Potential

Alzheimer's disease (AD) is a neurodegenerative disease that is known to accumulate amyloid-β (Aβ) and tau protein. Clinical studies have not identified pathogenesis mechanisms or produced an effective cure for AD. The Aβ monoclonal antibody lecanemab reduces Aβ plaque formation for the treatment of AD, but more studies are required to increase the effectiveness of drugs to reduce cognitive decline. The lack of AD therapy targets and evidence of an association with an acute neuroinflammatory response caused by several bacteria and viruses in some individuals has led to the establishment of the infection hypothesis during the last 10 years. How pathogens cross the blood-brain barrier is highly topical and is seen to be pivotal in proving the hypothesis. This review summarizes the possible role of the gut microbiome in the pathogenesis of AD and feasible therapeutic approaches and current research limitations.

Lipid-Lowering Medications are Associated with Reduced Sarcopenia-Related Quality of Life in Older Adults with Hyperlipidemia

PURPOSE

Statins medications negatively affect age-associated loss of muscle mass and strength, termed sarcopenia, and neuromuscular junction (NMJ) integrity. However, their association with the sarcopenia-related-quality-of-life (SarQoL) is unknown.

METHODS

In this cross-sectional, case control study, we recruited male nonusers (n = 75 and age 75.2 ± 5.9 years) and users (n = 77 and age 77.1 ± 6.2 years) of statins to evaluate SarQoL and handgrip strength (HGS). We also measured plasma C-terminal agrin fragment-22 (CAF22) as a marker of NMJ degradation.

RESULTS

Statin users had higher CAF22, and lower HGS, and cumulative SarQoL scores than non-users (all p < 0.05). Plasma CAF22 exhibited negative correlations with SarQoL scores for physical and mental health, locomotion, functionality, activities-of-daily-living, and cumulative SarQoL in statins users and non-users (all p < 0.05). Lastly, the cumulative SarQoL scores exhibited positive associations with HGS and gait speed in the study participants (all p < 0.05).

CONCLUSIONS

Collectively, statin usage was associated with NMJ degradation and reduced SarQoL. Statins should be cautiously prescribed in patients with sarcopenia with reduced QoL.

Butyrate supplementation reduces sarcopenia by repairing neuromuscular junction in patients with chronic obstructive pulmonary disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is associated with an intestinal leak and neuromuscular junction (NMJ) degradation, which contributes to physical compromise and accelerated age-related muscle loss, called sarcopenia. However, the relevant interventions partly remain ineffective. We investigated the effects of exogenous butyrate on sarcopenia and physical capacity with relevance to intestinal permeability and NMJ integrity in COPD patients.

METHODS

COPD patients were randomized into placebo (n = 67) and butyrate (n = 64) groups in a double-blind manner. The patients in the butyrate group received one 300 mg capsule a day for 12 weeks. We measured circulating markers of intestinal leak (zonulin), systemic bacterial load (LBP), and NMJ loss (CAF22), along with handgrip strength (HGS), and short physical performance battery (SPPB) at baseline and 12 weeks.

RESULTS

Butyrate supplementation improved HGS and gait speed in COPD patients. Among SPPB indices, butyrate improved the ability to maintain postural balance and walking and prevented a decline in the ability to rise from a chair. Butyrate also reduced the plasma levels of zonulin, LBP, and CAF22 levels in COPD patients (all p < 0.05). Regression analysis revealed significant associations of plasma zonulin and CAF22 with HGS, gait speed, and cumulative SPPB scores in butyrate group. These changes were associated with reduced markers of inflammation and muscle damage.

CONCLUSION

Butyrate may provide a therapeutic approach to sarcopenia and physical dependency in COPD by repairing intestinal leak and NMJ loss.

Implications of microbe-derived ɣ-aminobutyric acid (GABA) in gut and brain barrier integrity and GABAergic signaling in Alzheimer's disease

The gut microbial ecosystem communicates bidirectionally with the brain in what is known as the gut-microbiome-brain axis. Bidirectional signaling occurs through several pathways including signaling via the vagus nerve, circulation of microbial metabolites, and immune activation. Alterations in the gut microbiota are implicated in Alzheimer's disease (AD), a progressive neurodegenerative disease. Perturbations in gut microbial communities may affect pathways within the gut-microbiome-brain axis through altered production of microbial metabolites including ɣ-aminobutyric acid (GABA), the primary inhibitory mammalian neurotransmitter. GABA has been shown to act on gut integrity through modulation of gut mucins and tight junction proteins and may be involved in vagus nerve signal inhibition. The GABAergic signaling pathway has been shown to be dysregulated in AD, and may be responsive to interventions. Gut microbial production of GABA is of recent interest in neurological disorders, including AD. Bacteroides and Lactic Acid Bacteria (LAB), including Lactobacillus, are predominant producers of GABA. This review highlights how temporal alterations in gut microbial communities associated with AD may affect the GABAergic signaling pathway, intestinal barrier integrity, and AD-associated inflammation.