Aims: Irisin is a hormone cleaved from fibronectin type‐III domain‐containing protein 5 in response to exercise and may be therapeutic in Alzheimer's disease (AD). Irisin is shown to repair damage caused by midlife cardiometabolic risk factors for AD (i.e., diabetes mellitus; hypertension), prevent neural amyloid beta aggregation and reduce neuroinflammation. However, there are no investigations of irisin's effect on AD‐associated tauopathy in the brain. This study begins to address this gap in knowledge.Methods: Transgenic htau mice that selectively develop age‐related tauopathy were treated with recombinant irisin (100 µg/kg weekly i.p.) beginning at a pre‐symptomatic age (4 months) to determine if irisin could prevent emergence of early neuropathology. One month later, mice were sacrificed to collect brain tissue and serum. Protein levels of ptau (serine 202), inflammatory cytokine tumour necrosis factor alpha (TNFα) and FNDC5 were quantified using capillary‐based western blotting (Wes).Results: Our data show that irisin treatment significantly reduced ptau and TNFα in the hippocampus and serum of female htau mice compared to vehicle‐treated controls. Irisin treatment did not alter ptau levels in male htau hippocampus and appeared to enhance both neural and systemic TNFα levels.Conclusions: This study provides the first evidence that enhancing the endogenous hormone irisin may be therapeutic against emerging neuropathology in a tauopathy‐selective AD model. This is important because there are currently no disease‐modifying therapeutics available for AD, and few agents in development address the multiple disease targets irisin appears to—making irisin an intriguing therapeutic candidate for further investigation.

Mice fed a high-fat diet for 12 weeks or longer develop hyperglycemia, insulin resistance, dyslipidemia, and fatty liver. Additionally, a high-fat diet induces inflammation that remodels and affects the anti-inflammatory and antiatherogenic property of the high-density lipoprotein (HDL). However, the precise time course of metabolic disease progression and HDL remodeling remains unclear. Short-term (four weeks) high-fat feeding (60% fat calories) was performed in wild-type male C57BL/6J mice to gain insights into the early metabolic disease processes in conjunction with a HDL proteome dynamics analysis using a heavy water metabolic labeling approach. The high-fat diet-fed mice developed hyperglycemia, impaired glucose tolerance, hypercholesterolemia without hypertriglyceridemia or hepatic steatosis. A plasma HDL proteome dynamics analysis revealed increased turnover rates (and reduced half-lives) of several acute-phase response proteins involved in innate immunity, including complement C3 (12.77 ± 0.81 vs. 9.98 ± 1.20 h, p < 0.005), complement factor B (12.71 ± 1.01 vs. 10.85 ± 1.04 h, p < 0.05), complement Factor H (19.60 ± 1.84 vs. 16.80 ± 1.58 h, p < 0.05), and complement factor I (25.25 ± 1.29 vs. 19.88 ± 1.50 h, p < 0.005). Our findings suggest that an early immune response-induced inflammatory remodeling of the plasma HDL proteome precedes the diet-induced steatosis and dyslipidemia.

ATP13A2 is a lysosomal polyamine transporter with loss of function mutations linked to multiple neurodegenerative disorders including Parkinson’s disease (PD). Knockout of ATP13A2 in mice leads to age-related sensorimotor impairments and in the brain lipofuscinosis, gliosis, and modest alpha-synuclein (αSyn) pathology. However, few studies have included ATP13A2 heterozygous mice as a comparison. In the present study, the effect of reduced or complete loss of ATP13A2 function on behavior, αSyn, gliosis, dopamine, and polyamines were determined in mice. Male and female ATP13A2 wildtype (WT), heterozygous (Het), and knockout (KO) mice were assessed behaviorally at 3, 12, and 18 months of age. In the brain, αSyn, phosphorylated αSyn, and GFAP were measured in the prefrontal cortex, striatum, ventral midbrain, and cerebellum. Polyamine and neurotransmitter analyses were performed in the same brain regions. Similar to previous studies, KO mice developed motor impairments and widespread gliosis in the brain. In addition, polyamine content was altered in Het and KO mice. In contrast, Het mice showed impairments in cognitive function and an age-related increase in αSyn in the brain. These results indicate potentially different pathological mechanisms when ATP13A2 is reduced compared to when it is knocked out and may have important implications for disease modification in synucleinopathies including PD.

Forkhead box protein A3 (FOXA3), also known as hepatocyte nuclear factor 3g (HNF3g), is a member of the FOX family of transcription factors and regulates lipid and glucose metabolism and liver regeneration. Hepatic FOXA3 is reduced in obesity and patients with metabolic dysfunction-associated steatohepatitis (MASH). So far, it remains unknown whether hepatic FOXA3 is essential for regulating lipid metabolism or metabolic dysfunction-associated liver disease (MASLD). In this study, we first investigated whether genetic inactivation of hepatocyte Foxa3 affected the development of MASLD/MASH in C57BL/6 mice and then explored whether loss of hepatocyte Foxa3 regulated atherosclerosis development in Ldlr-deficient mice. Inactivation of Foxa3 in hepatocytes did not affect the development of Western diet-induced MASLD/MASH in C57BL/6 mice but attenuated MASH development in Western diet-fed Ldlr-deficient mice. Moreover, genetic loss of hepatocyte Foxa3 ameliorated hyperlipidemia and atherosclerosis in Ldlr-deficient mice. In Ldlr-deficient mice, loss of hepatocyte Foxa3 resulted in reduced expression of lipogenic, pro-inflammatory, or fibrogenic genes in the liver and reduced cholic acid levels in plasma and bile. Thus, hepatocyte FOXA3 loss confers protection against the development of MASH and atherosclerosis in hyperlipidemic Ldlr-deficient mice.