Cholesterol metabolism in the regulation of inflammatory responses

The balancing act between lipid droplets and lysosomes for membrane functionality in age-related neurodegeneration and inflammation

Age-related neurodegenerative disorders are often associated with disruptions in lipid metabolism. A critical aspect is the impairment of the interaction between lipid droplets (LDs) and lysosomal function, leading to the accumulation of toxic lipid species. This accumulation triggers cellular stress, inflammation, and defective waste processing within cells, disrupting cellular homeostasis and amplifying neuroinflammatory processes. Recent studies have shown that alterations in phospholipid and fatty acid homeostasis drive neuroinflammation and oxidative stress, exacerbating neurodegenerative processes. This review focuses on the role of neuropathy target esterase (PNPLA6/NTE) and NTE-related esterase (PNPLA7/NRE) in lipid metabolism, highlighting how dysregulation of these enzymes contributes to neurodegeneration, inflammation, and lysosomal dysfunction. Additionally, we discuss the involvement of lipid rafts, sphingolipids, and phospholipase enzymes, particularly PLA2 family members, in cellular signaling and membrane dynamics. By examining the relationship between lipid metabolism, inflammatory signaling, and lysosomal storage disorders, we aim to provide a comprehensive understanding of how LDs and lysosomes interact to influence cellular homeostasis in neurodegenerative conditions, which could lead to new therapeutic strategies addressing lipid dysregulation in age-related neurological disorders.

From lipids to glucose: Investigating the role of dyslipidemia in the risk of insulin resistance

Dyslipidemia is recognized as one of the most prevalent metabolic disorders and is frequently associated with other prevalent conditions, particularly diabetes mellitus. There appears to be a bidirectional connection between these two metabolic disorders. While considerable research has focused on how insulin resistance can lead to lipid abnormalities, the reverse relationship specifically, how dyslipidemia could assist in developing insulin resistance and diabetes mellitus has received relatively less attention. This review aims to comprehensively evaluate the mechanisms through which dyslipidemia can induce insulin resistance. Dyslipidemia is primarily classified into three main categories: hypercholesterolemia, hypertriglyceridemia, and low levels of HDL. These conditions may promote insulin resistance across multiple pathways, including the accumulation of lipid metabolites, dysfunction of pancreatic β-cells, increased reactive oxygen species, endoplasmic reticulum stress and inflammation, endothelial dysfunction, alterations in adiponectin levels, changes in bile acid composition and concentration, and dysbiosis of gut microbiota. However, further investigation is required to fully elucidate the cellular and molecular mechanisms underlying the relationship between lipid disorders and insulin resistance. Emphasizing such research could facilitate the development of therapeutic strategies targeting both conditions simultaneously.

Association between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and hyperuricemia: evidence from the CHARLS study

Background and aims

The non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) is an innovative composite lipid measure. This study aims to examine the correlation between NHHR and hyperuricemia in the middle-aged and elderly demographic in China.

Methods

This investigation comprised 4,639 individuals who were devoid of hyperuricemia at baseline in 2011, utilizing data from the China Health and Retirement Longitudinal Study (CHARLS). We utilized multivariable logistic regression, restricted cubic spline (RCS) analysis, and subgroup analysis to investigate the relationship between NHHR and hyperuricemia.

Results

A total of 499 participants (10.76%) experienced hyperuricemia at the 4-year follow-up. The incidence of hyperuricemia was 176% higher for participants in the highest quartile of NHHR than for those in the lowest quartile (OR 2.76, 95% CI 2.10-3.62, p < 0.001). The risk of hyperuricemia was 64% higher in the highest quartile of NHHR than in the lowest quartile in a fully adjusted model (OR 1.64, 95% CI 1.16-2.31, p = 0.005). The risk of hyperuricemia and NHHR had a linearly positive connection, according to restricted cubic spline (RCS) analysis (P for non-linearity > 0.05). Subgroup analysis showed that among women, non-smokers, and those over 60, the relationship between NHHR and hyperuricemia was more significant.

Conclusion

NHHR and hyperuricemia have a substantial linear positive connection, indicating that NHHR might be used as a tool for assessing hyperuricemia risk and offering valuable information for both prevention and therapy.

Assessing the predictive value of time-in-range level for the risk of postoperative infection in patients with type 2 diabetes: a cohort study

Aim

To analyze the correlation between preoperative time-in-range (TIR) levels and postoperative infection in patients with type 2 diabetes mellitus (T2DM) and to evaluate the value of the TIR as a predictor of postoperative infection in patients with T2DM.

Methods

A total of 656 patients with T2DM during the perioperative period were divided into a TIR standard group (TIR≥70%) and a TIR nonstandard group (TIR<70%) according to the TIR value. Modified Poisson regression was used to analyze postoperative risk factors in patients with T2DM. All patients were subsequently divided into a training set and a validation set at a ratio of 7:3. LASSO regression and the Boruta algorithm were used to screen out the predictive factors related to postoperative infection in T2DM patients in the training set. The discrimination and calibration of the model were evaluated by the area under the receiver operating characteristic curve (ROC) and calibration curve, and the clinical net benefit of the model was evaluated and verified through the decision analysis (DCA) curve. Finally, a forest plot was used for relevant subgroup analysis.

Results

Modified Poisson regression analysis revealed that the TIR was a risk factor for postoperative infection in T2DM patients, and when the TIR was <70%, the risk of postoperative infection increased by 52.2% (P <0.05). LASSO regression and Boruta algorithm screening variables revealed that the TIR, lymphocytes, neutrophils, total serum cholesterol, superoxide dismutase and type of incision were predictive factors for postoperative infection in patients with T2DM (P<0.05). The calibration curve confirmed that the model predictions were consistent with reality, and the decision curve confirmed that the model had better clinical benefits. Finally, the results of the subgroup analysis revealed that in each subgroup, the risk of postoperative infection was greater when the TIR was <70% than when the TIR was ≥70%, and there was no interaction between subgroups.

Conclusion

The TIR is related to postoperative infection and can be used as a new indicator to predict the risk of postoperative infection in patients with type 2 diabetes mellitus.

Endogenous production of nitric oxide by iNOS in human cells restricts inflammatory activation and cholesterol/fatty acid biosynthesis

Nitric oxide (NO) is a bioactive gas that is known to control many physiological processes. In human parenchymal cells, the function of iNOS-derived NO is incompletely understood. Here, we used RNA-seq to examine the role of iNOS-derived NO in the control of gene expression in a human lung epithelial cell line treated with inflammatory cytokines. iNOS-derived NO restricted the expression of genes involved in immune signaling, including the immune-related genes CXCL9 and E-selectin that were not previously known to be inhibited by iNOS. We also determined that iNOS-derived NO inhibits the expression of genes needed for cholesterol/fatty acid biosynthesis in response to cytokine stimulation, a process not previously known to be affected by NO. These findings establish the regulation of immune activation and cholesterol/fatty acid biosynthesis as main functions of iNOS in human parenchymal cells.

The role of type I interferon signaling in myeloid anti-tumor immunity

Tumors often arise in chronically inflamed, and thus immunologically highly active niches. While immune cells are able to recognize and remove transformed cells, tumors eventually escape the control of the immune system by shaping their immediate microenvironment. In this context, macrophages are of major importance, as they initially exert anti-tumor functions before they adopt a tumor-associated phenotype that instead inhibits anti-tumor immune responses and even allows for sustaining a smoldering inflammatory, growth promoting tumor microenvironment (TME). Type I interferons (IFNs) are well established modulators of inflammatory reactions. While they have been shown to directly inhibit tumor growth, there is accumulating evidence that they also play an important role in altering immune cell functions within the TME. In the present review, we focus on the impact of type I IFNs on anti-tumor responses, driven by monocytes and macrophages. Specifically, we will provide an overview of tumor-intrinsic factors, which impinge on IFN-stimulated gene (ISG) expression, like the presence of nucleic acids, metabolites, or hypoxia. We will further summarize the current understanding of the consequences of altered IFN responses on macrophage phenotypes, i.e., differentiation, polarization, and functions. For the latter, we will focus on macrophage-mediated tumor cell killing and phagocytosis, as well as on how macrophages affect their environment by secreting cytokines and directly interacting with immune cells. Finally, we will discuss how type I IFN responses in macrophages might affect and should be considered for current and future tumor therapies.

Metabolic Response After a Single Maximal Exercise Session in Physically Inactive Young Adults (EASY Study): Relevancy of Adiponectin Isoforms

The metabolic response to a maximal exercise test in physically inactive adults remains poorly understood, particularly regarding the role of adiponectin, an adipokine with insulin-sensitizing and anti-inflammatory properties. Adiponectin circulates in three isoforms-low (LMW), medium (MMW), and high-molecular-weight (HMW)-with differing bioactivities. While exercise is known to influence adiponectin levels, evidence is conflicting, and few studies have explored isoform-specific changes. This study aimed to evaluate the effects of a single maximal exercise session on circulating adiponectin isoforms and their associations with metabolic and kidney function markers in physically inactive young adults. In this quasi-experimental study, twenty-one physically inactive participants (mean age 24.6 ± 2.1 years, 85.7% women) completed a progressive cycle ergometer test. Circulating levels of LMW and MMW adiponectin, metabolic outcomes (e.g., cholesterol, triglycerides, fibroblast growth factor 21 (FGF21)), and kidney function markers (e.g., creatinine, proteinuria) were assessed before and after exercise using biochemical assays and Western blotting. Comparisons between pre- and post-exercise values were made with the Wilcoxon test. Exercise increased lipid metabolism markers (total cholesterol, triglycerides, HDL) and kidney stress indicators (albuminuria, proteinuria) (p < 0.05). LMW and MMW adiponectin levels showed no significant overall changes, but LMW adiponectin positively correlated with changes in total cholesterol and FGF21, while MMW adiponectin negatively correlated with creatinine and proteinuria (p < 0.05). HMW adiponectin was undetectable by our methods. A single maximal exercise session revealed isoform-specific associations between adiponectin and metabolic or kidney stress markers, emphasizing the complex role of adiponectin in exercise-induced metabolic responses. Future research should explore mechanisms underlying these differential associations to optimize exercise interventions for metabolic health improvement.

Clinical prediction of wound re-epithelisation outcomes in non-severe burn injury using the plasma lipidome

Whilst wound repair in severe burns has received substantial research attention, non-severe burns (<20 % total body surface area) remain relatively understudied, despite causing considerable physiological impact and constituting most of the hospital admissions for burns. Early prediction of healing outcomes would decrease financial and patient burden, and aid in preventing long-term complications from poor wound healing. Lipids have been implicated in inflammation and tissue repair and may play essential roles in burn wound healing. In this study, plasma samples were collected from 20 non-severe burn patients over six weeks from admission, including surgery, and analysed by liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance spectroscopy to identify 850 lipids and 112 lipoproteins. Orthogonal projections to latent structures-discriminant analysis was performed to identify changes associated with re-epithelialisation and delayed re-epithelisation. We demonstrated that the lipid and lipoprotein profiles at admission could predict re-epithelisation outcomes at two weeks post-surgery, and that these discriminatory profiles were maintained up to six weeks post-surgery. Inflammatory markers GlycB and C-reactive protein indicated divergent systemic responses to the burn injury at admission. Triacylglycerols, diacylglycerols and low-density lipoprotein subfractions were associated with re-epithelisation (p-value <0.02, Cliff's delta >0.7), whilst high-density lipoprotein subfractions, phosphatidylinositols, phosphatidylcholines, and phosphatidylserines were associated with delayed wound closure at two weeks post-surgery (p-value <0.01, Cliff's delta <-0.7). Further model validation will potentially lead to personalised intervention strategies to reduce the risk of chronic complications post-burn injury.

Metabolism: an important player in glioma survival and development

Gliomas are malignant tumors originating from both neuroglial cells and neural stem cells. The involvement of neural stem cells contributes to the tumor's heterogeneity, affecting its metabolic features, development, and response to therapy. This review provides a brief introduction to the importance of metabolism in gliomas before systematically categorizing them into specific groups based on their histological and molecular genetic markers. Metabolism plays a critical role in glioma biology, as tumor cells rely heavily on altered metabolic pathways to support their rapid growth, survival, and progression. Dysregulated metabolic processes, involving carbohydrates, lipids, and amino acids not only fuel tumor development but also contribute to therapy resistance and metastatic potential. By understanding these metabolic changes, key intervention points, such as mutations in genes like RTK, EGFR, RAS, and IDH can be identified, paving the way for novel therapeutic strategies. This review emphasizes the connection between metabolic pathways and clinical challenges, offering actionable insights for future research and therapeutic development in gliomas.

Associations between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio and hyperuricemia: a cross-sectional study

BACKGROUND AND OBJECTIVE

The value of the non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) assessment in the context of metabolic abnormalities is growing in importance. Nevertheless, the relationship between NHHR and hyperuricemia (HUA) is unknown. This study seeks to investigate the relationship between NHHR and HUA.

METHODS

The data derived from the 2017-2020 National Health and Nutrition Examination Survey (NHANES) included 7,876 adult participants. The multivariable logistic regression model, subgroup analysis and smooth fitting curve were utilized in order to investigate the association between NHHR and HUA.

RESULTS

In the fully adjusted model 3, NHHR was significantly associated with HUA. Specifically, participants in the highest quartile of NHHR had 1.95 times higher odds of HUA prevalence compared to those in the lowest quartile [2.95 (2.39, 3.64), P < 0.0001]. Although the overall trend suggested a positive association, further analysis using smooth fitting curves and threshold effect analysis indicated that this association was nonlinear, with an inflection point at 5.8. The positive association persisted across different HUA definitions and after removing outliers. Subgroup analysis showed significant interactions between NHHR and HUA in different races and diabetes statuses. The odds of HUA prevalence were higher among non-diabetic participants [1.40 (1.32, 1.49), P < 0.0001] compared to diabetic participants [1.18 (1.06, 1.32), P = 0.0031]. Mexican Americans had the lowest odds of HUA prevalence [1.09 (0.92, 1.27), P = 0.2413] compared to other races.

CONCLUSIONS

There is a significant positive association between NHHR and HUA, indicating that NHHR may serve as a potential risk assessment maker for HUA, although further prospective studies are needed for validation.

Elucidating the Functional Roles of Long Non-Coding RNAs in Alzheimer's Disease

Alzheimer's disease (AD) is a multifaceted neurodegenerative disorder characterized by cognitive decline and neuronal loss, representing a most challenging health issue. We present a computational analysis of transcriptomic data of AD tissues vs. healthy controls, focused on the elucidation of functional roles played by long non-coding RNAs (lncRNAs) throughout the AD progression. We first assembled our own lncRNA transcripts from the raw RNA-Seq data generated from 527 samples of the dorsolateral prefrontal cortex, resulting in the identification of 31,574 novel lncRNA genes. Based on co-expression analyses between mRNAs and lncRNAs, a co-expression network was constructed. Maximal subnetworks with dense connections were identified as functional clusters. Pathway enrichment analyses were conducted over mRNAs and lncRNAs in each cluster, which served as the basis for the inference of functional roles played by lncRNAs involved in each of the key steps in an AD development model that we have previously built based on transcriptomic data of protein-encoding genes. Detailed information is presented about the functional roles of lncRNAs in activities related to stress response, reprogrammed metabolism, cell polarity, and development. Our analyses also revealed that lncRNAs have the discerning power to distinguish between AD samples of each stage and healthy controls. This study represents the first of its kind.

A cross-sectional analysis of the relationship between the non-high density to high density lipoprotein cholesterol ratio (NHHR) and kidney stone risk in American adults

BACKGROUND

Recent interest in the Non-High Density to High Density Lipoprotein Cholesterol ratio (NHHR) has emerged due to its potential role in metabolic disorders. However, the connection between NHHR and the development of kidney stones still lacks clarity. The primary goal of this research is to explore how NHHR correlates with kidney stone incidence.

METHODS

An analysis was conducted on the data collected by the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018, focusing on adults over 20 years diagnosed with kidney stones and those with available NHHR values. Employing weighted logistic regression and Restricted Cubic Spline (RCS) models, NHHR levels' correlation with kidney stone risk was examined. Extensive subgroup analyses were conducted for enhanced reliability of the findings.

RESULTS

The findings indicate a heightened kidney stone risk for those at the highest NHHR levels relative to those at the lowest (reference group). A notable non-linear correlation of NHHR with kidney stone incidence has been observed, with a significant P-value (< 0.001), consistent across various subgroups.

CONCLUSION

A clear link exists between high NHHR levels and increased kidney stone risk in the American adult population. This study highlights NHHR's significance as a potential indicator in kidney stone formation.

Microbial metabolites as modulators of host physiology

The gut microbiota is increasingly recognised as a key player in influencing human health and changes in the gut microbiota have been strongly linked with many non-communicable conditions in humans such as type 2 diabetes, obesity and cardiovascular disease. However, characterising the molecular mechanisms that underpin these associations remains an important challenge for researchers. The gut microbiota is a complex microbial community that acts as a metabolic interface to transform ingested food (and other xenobiotics) into metabolites that are detected in the host faeces, urine and blood. Many of these metabolites are only produced by microbes and there is accumulating evidence to suggest that these microbe-specific metabolites do act as effectors to influence human physiology. For example, the gut microbiota can digest dietary complex polysaccharides (such as fibre) into short-chain fatty acids (SCFA) such as acetate, propionate and butyrate that have a pervasive role in host physiology from nutrition to immune function. In this review we will outline our current understanding of the role of some key microbial metabolites, such as SCFA, indole and bile acids, in human health. Whilst many studies linking microbial metabolites with human health are correlative we will try to highlight examples where genetic evidence is available to support a specific role for a microbial metabolite in host health and well-being.

Exploration of Novel Metabolic Features Reflecting Statin Sensitivity in Lung Cancer Cells

Statins are cholesterol-lowering drugs often used for the treatment of dyslipidemia. Statins also exert anti-cancer effects by inhibiting hydroxymethylglutaryl-CoA reductase (HMGCR), a rate-limiting enzyme in cholesterol synthesis. We previously reported that the susceptibility to statin treatment differs among cancer cells and that functional E-cadherin expression on the plasma membrane could be a biomarker of statin sensitivity in cancer cells. However, the detailed qualitative and molecular differences between statin-sensitive and statin-resistant cancer cells remain unclear. Here, we explored novel parameters related to statin sensitivity by comparing gene expression profiles and metabolite contents between statin-sensitive and statin-resistant lung cancer cell lines. We found that the expression of most cholesterol synthesis genes was lower in the statin-sensitive cancer cell line, HOP-92, than in the statin-resistant cancer cell line, NCI-H322M. Moreover, HOP-92 cells originally exhibited lower levels of CoA and HMG-CoA. Additionally, atorvastatin decreased the mRNA expression of PANK2, a rate-limiting enzyme in CoA synthesis. Atorvastatin also reduced the mRNA levels of the cholesterol esterification enzyme SOAT1, which was consistent with a decrease in the ratio of cholesterol ester to total cholesterol in HOP-92 cells. Our data suggest that the cholesterol synthetic flow and CoA content may be limited in statin-sensitive cancer cells. We also suggest that CoA synthesis and cholesterol storage may fluctuate with atorvastatin treatment in statin-sensitive cancer cells.

Inflammation, atherosclerosis and hypertension: the impact of depression and stress on their complex relationship

This future perspective analyzes the complex relationship between inflammation and atherosclerosis and arterial hypertension. The involvement of inflammation in atherosclerosis has led to research therapies that target inflammation to prevent or treat cardiovascular disease. This aspect has recently been included in the treatment management of residual cardiovascular risk. The recent pandemic has exacerbated cardiovascular risk both through an increase in unhealthy lifestyle behaviors and through the reduction of cardiovascular screening. What actions to take? Primary prevention campaigns for healthy subjects with specific attention to young people.

Cholesterol Metabolism in Antigen-Presenting Cells and HIV-1 Trans-Infection of CD4+ T Cells

Antiretroviral therapy (ART) provides an effective method for managing HIV-1 infection and preventing the onset of AIDS; however, it is ineffective against the reservoir of latent HIV-1 that persists predominantly in resting CD4+ T cells. Understanding the mechanisms that facilitate the persistence of the latent reservoir is key to developing an effective cure for HIV-1. Of particular importance in the establishment and maintenance of the latent viral reservoir is the intercellular transfer of HIV-1 from professional antigen-presenting cells (APCs-monocytes/macrophages, myeloid dendritic cells, and B lymphocytes) to CD4+ T cells, termed trans-infection. Whereas virus-to-cell HIV-1 cis infection is sensitive to ART, trans-infection is impervious to antiviral therapy. APCs from HIV-1-positive non-progressors (NPs) who control their HIV-1 infection in the absence of ART do not trans-infect CD4+ T cells. In this review, we focus on this unique property of NPs that we propose is driven by a genetically inherited, altered cholesterol metabolism in their APCs. We focus on cellular cholesterol homeostasis and the role of cholesterol metabolism in HIV-1 trans-infection, and notably, the link between cholesterol efflux and HIV-1 trans-infection in NPs.

Neuromedin U programs eosinophils to promote mucosal immunity of the small intestine

Eosinophils are granulocytes that play an essential role in type 2 immunity and regulate multiple homeostatic processes in the small intestine (SI). However, the signals that regulate eosinophil activity in the SI at steady state remain poorly understood. Through transcriptome profiling of eosinophils from various mouse tissues, we found that a subset of SI eosinophils expressed neuromedin U (NMU) receptor 1 (NMUR1). Fate-mapping analyses showed that NMUR1 expression in SI eosinophils was programmed by the local microenvironment and further enhanced by inflammation. Genetic perturbation and eosinophil-organoid coculture experiments revealed that NMU-mediated eosinophil activation promotes goblet cell differentiation. Thus, NMU regulates epithelial cell differentiation and barrier immunity by stimulating NMUR1-expressing eosinophils in the SI, which highlights the importance of neuroimmune-epithelial cross-talk in maintaining tissue homeostasis.