Cumulative effects of excess high-normal alanine aminotransferase levels in relation to new-onset metabolic dysfunction-associated fatty liver disease in China.

BACKGROUND: Within the normal range, elevated alanine aminotransferase (ALT) levels are associated with an increased risk of metabolic dysfunction-associated fatty liver disease (MAFLD). AIM: To investigate the associations between repeated high-normal ALT measurements and the risk of new-onset MAFLD prospectively. METHODS: A cohort of 3553 participants followed for four consecutive health examinations over 4 years was selected. The incidence rate, cumulative times, and equally and unequally weighted cumulative effects of excess high-normal ALT levels (ehALT) were measured. Cox proportional hazards regression was used to analyse the association between the cumulative effects of ehALT and the risk of new-onset MAFLD. RESULTS: A total of 83.13% of participants with MAFLD had normal ALT levels. The incidence rate of MAFLD showed a linear increasing trend in the cumulative ehALT group. Compared with those in the low-normal ALT group, the multivariate adjusted hazard ratios of the equally and unequally weighted cumulative effects of ehALT were 1.651 [95% confidence interval (CI): 1.199-2.273] and 1.535 (95%CI: 1.119-2.106) in the third quartile and 1.616 (95%CI: 1.162-2.246) and 1.580 (95%CI: 1.155-2.162) in the fourth quartile, respectively. CONCLUSION: Most participants with MAFLD had normal ALT levels. Long-term high-normal ALT levels were associated with a cumulative increased risk of new-onset MAFLD.

Multiple brain regions are involved in reaction to acute restraint stress in CYLD-knockout mice.

The lysine 63 deubiquitinase cylindromatosis (CYLD) is expressed at high levels in the brain and is considered to be involved in anxious and depressive behavior, cognitive inflexibility, and autism disorders. Previous research was limited in some brain regions, including the hippocampus, striatum, and amygdala. To better understand whether CYLD plays a role in adaptation to stress and which brain regions are involved, we analyzed the behavior of CYLD-knockout mice in the elevated plus maze (EPM) and light-dark box test (LDT) after acute restraint stress (ARS) and mapped their c-Fos immunoreactivity in brain sections. Here we report that CYLD deficiency leads to an unexpected reaction to ARS in mice, and is accompanied by significant neuronal activation of brain regions including the medial prefrontal cortex (mPFC), dorsal striatum (DS), nucleus accumbens (NAc), and basal lateral amygdala (BLA), but not ventral hippocampus (vHPC). Our findings show that CYLD participates in ARS-induced anxious behavior and that this involves multiple brain regions.

Microglial activation in the dorsal striatum participates in anxiety-like behavior in Cyld knockout mice.

CYLD lysine 63 deubiquitinase (CYLD), that is mainly involved in immune responses and inflammation, is expressed at high levels in the brain, especially in the dorsal striatum, but its physiological function of CYLD in the brain remains unexplored. The present study investigated the effect of Cyld gene knockout on behavior relevant to the dorsal striatum, such as motor activity and depression-like and anxiety-like behavior. Microglia and the pro-inflammatory cytokines including interleukin (IL)-1 ß and tumor necrosis factor (TNF)- α were evaluated in the dorsal striatum to elucidate the underlying mechanism. Cyld knockout (Cyld-/-) mice exhibited anxiety-like behavior, but not motor deficits or depression-like behavior. Microglia were activated and the mRNA levels of IL-1 ß and TNF- α were increased in the dorsal striatum of Cyld-/- mice compared to Cyld+/+ mice. The microglial modulator minocycline partially reversed the anxiety-like behavior, microglial activation and increase in IL-1 ß and TNF- α mRNA and protein levels in the dorsal striatum of Cyld-/- mice. Collectively, these results suggest that Cyld knockout leading to microglial activation promotes IL-1 ß and TNF- α expression and acts as a critical pathway in the pathophysiology of anxiety.