Macrophage AMPK β1 activation by PF-06409577 reduces the inflammatory response, cholesterol synthesis, and atherosclerosis in mice

Activation of autophagy with PF-06409577 alleviates heatstroke-induced organ injury

Heat waves are a significant environmental issue threatening global human health. Extreme temperatures can lead to various heat-related illnesses, with heatstroke being among the most severe. Currently, there are no effective treatments to mitigate the multi-organ damage caused by heatstroke. We found that heat stress activated autophagy. Knockdown of the autophagy-related gene 7 (ATG7) or knockout of the autophagy initiation regulatory genes UNC-51-like autophagy activating kinase 1/2 (ULK1/ULK2) increased cell death. PF-06409577, an allosteric activator of AMP-activated protein kinase β (AMPKβ), reduced heat stress-induced cell death by promoting autophagy. Inhibition of ATG7 or ULK1 weakened PF-06409577's protective effect on cells. Treatment of heatstroke mouse models with PF-06409577 suppressed high temperature-induced damage to multiple organs, including the liver, kidneys, lungs, and small intestine. PF-06409577 protected liver and kidney functions, lowered the expression of kidney injury markers neutrophil gelatinase associated lipocalin (Ngal), secreted phosphoprotein 1 (Spp1), and clusterin (Clu), and reduced levels of the inflammatory factor IL-6. Additionally, it decreased heat stress-induced macrophage infiltration and IL-6 production in the liver. The results indicate that activation of autophagy serves a protective function during heat stress, and the AMPK activator PF-06409577 exhibits potential in mitigating heatstroke-induced multi-organ damage through its ability to promote autophagy.

The relationship between non-HDL-C/HDL-C ratio and bone mineral density: an NHANES study

Background

The non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) is a newly developed lipid parameter. However, the current research has only explored the relationship with lumbar spine bone mineral density, lacking studies on bone mineral density at other sites, total body bone mineral density, and an analysis of risk factors. This study aims to determine the potential association between NHHR and lumbar BMD, increase awareness of the impact of lipid levels on bone health.

Methods

By utilizing data from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2018, we conducted univariate and generalized linear models (GLMs) analysis, stratified analysis, threshold effect analysis, smooth curve fitting and stratified analysis to investigate the association between NHHR and BMD. NHHR levels were categorized into tertiles (low, medium, and high) based on their distribution among the study population.

Results

The study included 8,671participants, studies have shown, the ratio of non-high-density lipoprotein to high-density lipoprotein (NHHR) exhibits a stratified correlation with bone mineral density (BMD). In the BMI subgroup, NHHR is significantly negatively correlated with BMD at multiple sites in the low-to-middle BMI group (BMI <25 kg/m2), while no significant correlation is found in the high BMI group (BMI ≥30 kg/m2). In the gender subgroup, NHHR has a more pronounced effect on male BMD, mainly reflected in the reduction of lumbar spine and total body BMD. In the age subgroup, the negative correlation between NHHR and BMD is strongest in the younger group (18-30 years), gradually weakening in the middle-aged (31-44 years) and older groups (45-59 years). Further analysis suggests that dyslipidemia may influence bone metabolism through pathways such as inflammation and oxidative stress.

Conclusion

The effect of NHHR on bone mineral density (BMD) varies by BMI, gender, and age. This study suggests that controlling NHHR levels may be a potential intervention target for bone health management, particularly for individuals with low-to-middle BMI, males, and younger populations. These findings offer a new perspective on the relationship between lipid metabolism and bone metabolism and provide scientific evidence for the development of personalized osteoporosis prevention and treatment strategies.

Myeloid Cell-Specific Deletion of AMPKα1 Worsens Ocular Bacterial Infection by Skewing Macrophage Phenotypes

AMP-activated protein kinase (AMPK) plays a crucial role in governing essential cellular functions such as growth, proliferation, and survival. Previously, we observed increased vulnerability to bacterial (Staphylococcus aureus) endophthalmitis in global AMPKα1 knockout mice. In this study, we investigated the specific involvement of AMPKα1 in myeloid cells using LysMCre;AMPKα1fl mice. Our findings revealed that whereas endophthalmitis resolved in wild-type C57BL/6 mice, the severity of the disease progressively worsened in AMPKα1-deficient mice over time. Moreover, the intraocular bacterial load and inflammatory mediators (e.g., IL-1β, TNF-α, IL-6, and CXCL2) were markedly elevated in the LysMCre;AMPKα1fl mice. Mechanistically, the deletion of AMPKα1 in myeloid cells skewed macrophage polarization toward the inflammatory M1 phenotype and impaired the phagocytic clearance of S. aureus by macrophages. Notably, transferring AMPK-competent bone marrow from wild-type mice to AMPKα1 knockout mice preserved retinal function and mitigated the severity of endophthalmitis. Overall, our study underscores the role of myeloid-specific AMPKα1 in promoting the resolution of inflammation in the eye during bacterial infection. Hence, therapeutic strategies aimed at restoring or enhancing AMPKα1 activity could improve visual outcomes in endophthalmitis and other ocular infections.

AMPK-mediated regulation of endogenous cholesterol synthesis does not affect atherosclerosis in a murine Pcsk9-AAV model

BACKGROUND AND AIMS

Dysregulated cholesterol metabolism is a hallmark of atherosclerotic cardiovascular diseases, yet our understanding of how endogenous cholesterol synthesis affects atherosclerosis is not clear. The energy sensor AMP-activated protein kinase (AMPK) phosphorylates and inhibits the rate-limiting enzyme in the mevalonate pathway HMG-CoA reductase (HMGCR). Recent work demonstrated that when AMPK-HMGCR signaling was compromised in an Apoe-/- model of hypercholesterolemia, atherosclerosis was exacerbated due to elevated hematopoietic stem and progenitor cell mobilization and myelopoiesis. We sought to validate the significance of the AMPK-HMGCR signaling axis in atherosclerosis using a non-germline hypercholesterolemia model with functional ApoE.

METHODS

Male and female HMGCR S871A knock-in (KI) mice and wild-type (WT) littermate controls were made atherosclerotic by intravenous injection of a gain-of-function Pcsk9D374Y-adeno-associated virus followed by high-fat and high-cholesterol atherogenic western diet feeding for 16 weeks.

RESULTS

AMPK activation suppressed endogenous cholesterol synthesis in primary bone marrow-derived macrophages from WT but not HMGCR KI mice, without changing other parameters of cholesterol regulation. Atherosclerotic plaque area was unchanged between WT and HMGCR KI mice, independent of sex. Correspondingly, there were no phenotypic differences observed in hematopoietic progenitors or differentiated immune cells in the bone marrow, blood, or spleen, and no significant changes in systemic markers of inflammation. When lethally irradiated female mice were transplanted with KI bone marrow, there was similar plaque content relative to WT.

CONCLUSIONS

Given previous work, our study demonstrates the importance of preclinical atherosclerosis model comparison and brings into question the importance of AMPK-mediated control of cholesterol synthesis in atherosclerosis.

Novel insights and new therapeutic potentials for macrophages in pulmonary hypertension

Inflammation and immune processes underlie pulmonary hypertension progression. Two main different activated phenotypes of macrophages, classically activated M1 macrophages and alternatively activated M2 macrophages, are both involved in inflammatory processes related to pulmonary hypertension. Recent advances suggest that macrophages coordinate interactions among different proinflammatory and anti-inflammatory mediators, and other cellular components such as smooth muscle cells and fibroblasts. In this review, we summarize the current literature on the role of macrophages in the pathogenesis of pulmonary hypertension, including the origin of pulmonary macrophages and their response to triggers of pulmonary hypertension. We then discuss the interactions among macrophages, cytokines, and vascular adventitial fibroblasts in pulmonary hypertension, as well as the potential therapeutic benefits of macrophages in this disease. Identifying the critical role of macrophages in pulmonary hypertension will contribute to a comprehensive understanding of this pathophysiological abnormality, and may provide new perspectives for pulmonary hypertension management.