Increased expression levels of inflammatory cytokines and adhesion molecules in lipopolysaccharide‑induced acute inflammatory apoM‑/‑ mice

Delineating the intricacies of polymorphisms, structures, functions and therapeutic applications of biological high-density lipoprotein-apolipoprotein M: A review

Apolipoprotein-M (ApoM), primarily associated with high-density lipoproteins (HDL), plays a crucial role in lipid metabolism and cardiovascular health. It facilitates the transport of lipids such as cholesterol and sphingosine-1-phosphate (S1P), contributing to reverse cholesterol transport (RCT), which removes excess cholesterol from peripheral tissues to the liver for excretion. Through its association with HDL and S1P, ApoM exerts anti-inflammatory, anti-thrombotic, and anti-apoptotic effects. The ApoM-S1P complex regulates various cellular, immunological, and physiological processes via S1P receptors, and its dysregulation is linked to metabolic and inflammatory disorders. Reduced plasma ApoM levels are associated with atherosclerosis, diabetes, and chronic systemic inflammation. ApoM levels and paraoxonase-1 activity in early pregnancy correlate with gestational hypertension risk, potentially affecting fetal vascular health. ApoM also functions as a S1P chaperone, and recent research highlights the roles of ApoM/S1P axis and the ApoA1-ApoM (A1M) complex in glucose and lipid metabolism, emphasizing its therapeutic relevance in cardiovascular diseases (CVD), cancer, and diabetes. The ApoM-Fc fusion protein exhibits promising therapeutic potential by reducing fibrosis, enhancing endothelial function, and promoting tissue regeneration. HDL-ApoM macromolecules bind bacterial endotoxins and aids in its clearance. This review explores ApoM gene organization, isoforms, point mutations, protein structure, functions and their relevance for developing novel therapeutics.

Large-scale plasma proteomics uncovers novel targets linking ambient air pollution and depression

Despite the growing recognition of association between air pollution and increased risk of depression, the intricate biological mechanisms underlying it remains unclear. In this study, a total of 1463 plasma proteins were measured by the Olink Explore platform for 50,553 participants in a large prospective cohort. Four air pollutants were assessed using land-use regression models: particulate matter with aerodynamic diameter ≤ 2.5μm (PM2.5), particulate matter with aerodynamic diameter > 2.5μm and ≤ 10μm (PM2.5-10), nitrogen dioxide (NO2), and nitric oxide (NO). The air pollution index was calculated using principal components analysis to assess joint exposure to air pollution. Logistic regression and Cox proportional hazards regression analyses were respectively used to explore the impact of the interaction between air pollution exposure and plasma proteins on the prevalence and incidence of depression. Functional enrichment analysis and drug prediction analysis were conducted to explore the biological mechanisms and drugs associated with identified plasma proteins with interaction effects. Logistic regression analysis detected seven significant air pollutant and plasma protein interactions for the prevalence of depression, such as CDHR5 vs. PM2.5 (OR: 0.58; 95% CI: 0.48-0.71), TNFRSF13C vs. NO (OR :0.70, 95% CI: 0.58-0.84) and ICAM5 vs. air pollution index (OR: 1.38, 95% CI: 1.17-1.63). Two significant interactions were identified for the incidence of depression: CDHR5 vs. PM2.5 (HR: 0.62, 95% CI: 0.50-0.76) and HSD11B1 vs. PM2.5 (HR: 1.48, 95% CI: 1.22-1.81). The plasma proteins that interacted with air pollutants were enriched in various Gene Ontology terms and pathways involving immunity, endocrine, inflammation, neurological function and metabolism, such as neuroinflammatory response, neuron projection guidance, regulation of lymphocyte mediated immunity, steroid biosynthetic process and lipid digestion. We also found that these proteins interacted with multiple drugs, such as risperidone, olanzapine and progesterone. This study identified novel targets linking ambient air pollution and depression, providing the insights for biological mechanisms of air pollution affecting the risk of depression.

Plasma apolipoprotein M predicts overall survival in metastatic breast cancer patients

PURPOSE

Apolipoprotein M (APOM) is a plasma apolipoprotein closely involved with lipid metabolism and inflammation. In vitro studies suggest that APOM may also have a tumor-suppressive role in breast cancer. In the present study, we aimed to evaluate the impact of plasma APOM levels on the prognosis of breast cancer patients.

METHODS

We measured APOM levels using an enzyme-linked immunosorbent assay in 75 patients with ER-positive/HER2-negative metastatic breast cancer. The endpoint was overall survival (OS) at 24 months.

RESULTS

During the 24-month follow-up period, 34.7% of the patients died. Baseline APOM levels were significantly reduced in patients who deceased during follow-up compared to survivors (42.7 ± 14.5 µg/mL versus 52.2 ± 13.8 µg/mL; P = 0.003). Cox regression analysis showed a hazard ratio of 0.30 [95% confidence interval 0.15-0.61]; P < 0.001 per doubling of APOM levels. Correction for age, C-reactive protein, menopausal state, histology of the primary tumor, metastatic site, number of metastases, endocrine resistance, scheduled therapy line, and kind of scheduled therapy indicated that circulating APOM predicted OS independently of these parameters (HRper doubling = 0.23 [0.09-0.56; P = 0.001).

CONCLUSIONS

Our study suggests that circulating APOM is significantly linked with reduced mortality in metastatic breast cancer patients.

Macrophage Reprogramming and Cancer Therapeutics: Role of iNOS-Derived NO

Nitric oxide and its production by iNOS is an established mechanism critical to tumor promotion or suppression. Macrophages have important roles in immunity, development, and progression of cancer and have a controversial role in pro- and antitumoral effects. The tumor microenvironment consists of tumor-associated macrophages (TAM), among other cell types that influence the fate of the growing tumor. Depending on the microenvironment and various cues, macrophages polarize into a continuum represented by the M1-like pro-inflammatory phenotype or the anti-inflammatory M2-like phenotype; these two are predominant, while there are subsets and intermediates. Manipulating their plasticity through programming or reprogramming of M2-like to M1-like phenotypes presents the opportunity to maximize tumoricidal defenses. The dual role of iNOS-derived NO also influences TAM activity by repolarization to tumoricidal M1-type phenotype. Regulatory pathways and immunomodulation achieve this through miRNA that may inhibit the immunosuppressive tumor microenvironment. This review summarizes the classical physiology of macrophages and polarization, iNOS activities, and evidence towards TAM reprogramming with current information in glioblastoma and melanoma models, and the immunomodulatory and therapeutic options using iNOS or NO-dependent strategies.

Adipose-Derived Lipid-Binding Proteins: The Good, the Bad and the Metabolic Diseases

Adipose tissue releases a large range of bioactive factors called adipokines, many of which are involved in inflammation, glucose homeostasis and lipid metabolism. Under pathological conditions such as obesity, most of the adipokines are upregulated and considered as deleterious, due to their pro-inflammatory, pro-atherosclerotic or pro-diabetic properties, while only a few are downregulated and would be designated as beneficial adipokines, thanks to their counteracting properties against the onset of comorbidities. This review focuses on six adipose-derived lipid-binding proteins that have emerged as key factors in the development of obesity and diabetes: Retinol binding protein 4 (RBP4), Fatty acid binding protein 4 (FABP4), Apolipoprotein D (APOD), Lipocalin-2 (LCN2), Lipocalin-14 (LCN14) and Apolipoprotein M (APOM). These proteins share structural homology and capacity to bind small hydrophobic molecules but display opposite effects on glucose and lipid metabolism. RBP4 and FABP4 are positively associated with metabolic syndrome, while APOD and LCN2 are ubiquitously expressed proteins with deleterious or beneficial effects, depending on their anatomical site of expression. LCN14 and APOM have been recently identified as adipokines associated with healthy metabolism. Recent findings on these lipid-binding proteins exhibiting detrimental or protective roles in human and murine metabolism and their involvement in metabolic diseases are also discussed.

Revealing the Role of High-Density Lipoprotein in Colorectal Cancer

Colorectal cancer (CRC) is a highly prevalent malignancy with multifactorial etiology, which includes metabolic alterations as contributors to disease development. Studies have shown that lipid status disorders are involved in colorectal carcinogenesis. In line with this, previous studies have also suggested that the serum high-density lipoprotein cholesterol (HDL-C) level decreases in patients with CRC, but more recently, the focus of investigations has shifted toward the exploration of qualitative properties of HDL in this malignancy. Herein, a comprehensive overview of available evidences regarding the putative role of HDL in CRC will be presented. We will analyze existing findings regarding alterations of HDL-C levels but also HDL particle structure and distribution in CRC. In addition, changes in HDL functionality in this malignancy will be discussed. Moreover, we will focus on the genetic regulation of HDL metabolism, as well as the involvement of HDL in disturbances of cholesterol trafficking in CRC. Finally, possible therapeutic implications related to HDL will be presented. Given the available evidence, future studies are needed to resolve all raised issues concerning the suggested protective role of HDL in CRC, its presumed function as a biomarker, and eventual therapeutic approaches based on HDL.