Impact of Lipid Metabolism on Macrophage Polarization: Implications for Inflammation and Tumor Immunity

Novel immune cross-talk between inflammatory bowel disease and IgA nephropathy

The mechanisms underlying the complex correlation between immunoglobulin A nephropathy (IgAN) and inflammatory bowel disease (IBD) remain unclear. This study aimed to identify the optimal cross-talk genes, potential pathways, and mutual immune-infiltrating microenvironments between IBD and IgAN to elucidate the linkage between patients with IBD and IgAN. The IgAN and IBD datasets were obtained from the Gene Expression Omnibus (GEO). Three algorithms, CIBERSORTx, ssGSEA, and xCell, were used to evaluate the similarities in the infiltrating microenvironment between the two diseases. Weighted gene co-expression network analysis (WGCNA) was implemented in the IBD dataset to identify the major immune infiltration modules, and the Boruta algorithm, RFE algorithm, and LASSO regression were applied to filter the cross-talk genes. Next, multiple machine learning models were applied to confirm the optimal cross-talk genes. Finally, the relevant findings were validated using histology and immunohistochemistry analysis of IBD mice. Immune infiltration analysis showed no significant differences between IBD and IgAN samples in most immune cells. The three algorithms identified 10 diagnostic genes, MAPK3, NFKB1, FDX1, EPHX2, SYNPO, KDF1, METTL7A, RIDA, HSDL2, and RIPK2; FDX1 and NFKB1 were enhanced in the kidney of IBD mice. Kyoto Encyclopedia of Genes and Genomes analysis showed 15 mutual pathways between the two diseases, with lipid metabolism playing a vital role in the cross-talk. Our findings offer insights into the shared immune mechanisms of IgAN and IBD. These common pathways, diagnostic cross-talk genes, and cell-mediated abnormal immunity may inform further experimental studies.

Ferroptosis and cuproptosis: Metal-dependent cell death pathways activated in response to classical chemotherapy - Significance for cancer treatment?

Apoptosis has traditionally been regarded as the desired cell death pathway activated by chemotherapeutic drugs due to its controlled and non-inflammatory nature. However, recent discoveries of alternative cell death pathways have paved the way for immune-stimulatory treatment approaches in cancer. Ferroptosis (dependent on iron) and cuproptosis (dependent on copper) hold promise for selective cancer cell targeting and overcoming drug resistance. Copper ionophores and iron-bearing nano-drugs show potential for clinical therapy as single agents and as adjuvant treatments. Here we review up-to-date evidence for the involvement of metal ion-dependent cell death pathways in the cytotoxicity of classical chemotherapeutic agents (alkylating agents, topoisomerase inhibitors, antimetabolites, and mitotic spindle inhibitors) and their combinations with cuproptosis and ferroptosis inducers, indicating the prospects, advantages, and obstacles of their use.

Phosphoproteomics Reveals Selective Regulation of Signaling Pathways by Lysophosphatidic Acid Species in Macrophages

Lysophosphatidic acid (LPA) species, prevalent in the tumor microenvironment (TME), adversely impact various cancers. In ovarian cancer, the 18:0 and 20:4 LPA species are selectively associated with shorter relapse-free survival, indicating distinct effects on cellular signaling networks. Macrophages represent a cell type of high relevance in the TME, but the impact of LPA on these cells remains obscure. Here, we uncovered distinct LPA-species-specific responses in human monocyte-derived macrophages through unbiased phosphoproteomics, with 87 and 161 phosphosites upregulated by 20:4 and 18:0 LPA, respectively, and only 24 shared sites. Specificity was even more pronounced for downregulated phosphosites (163 versus 5 sites). Considering the high levels 20:4 LPA in the TME and its selective association with poor survival, this finding may hold significant implications. Pathway analysis pinpointed RHO/RAC1 GTPase signaling as the predominantly impacted target, including AHRGEF and DOCK guanine exchange factors, ARHGAP GTPase activating proteins, and regulatory protein kinases. Consistent with these findings, exposure to 20:4 resulted in strong alterations to the actin filament network and a consequent enhancement of macrophage migration. Moreover, 20:4 LPA induced p38 phosphorylation, a response not mirrored by 18:0 LPA, whereas the pattern for AKT was reversed. Furthermore, RNA profiling identified genes involved in cholesterol/lipid metabolism as selective targets of 20:4 LPA. These findings imply that the two LPA species cooperatively regulate different pathways to support functions essential for pro-tumorigenic macrophages within the TME. These include cellular survival via AKT activation and migration through RHO/RAC1 and p38 signaling.

Advances in Metabolic Regulation of Macrophage Polarization State

Macrophages are significant immune-related cells that are essential for tissue growth, homeostasis maintenance, pathogen resistance, and damage healing. The studies on the metabolic control of macrophage polarization state in recent years and the influence of polarization status on the development and incidence of associated disorders are expounded upon in this article. Firstly, we reviewed the origin and classification of macrophages, with particular attention paid to how the tricarboxylic acid cycle and the three primary metabolites affect macrophage polarization. The primary metabolic hub that controls macrophage polarization is the tricarboxylic acid cycle. Finally, we reviewed the polarization state of macrophages influences the onset and progression of cancers, inflammatory disorders, and other illnesses.

PPARs in atherosclerosis: The spatial and temporal features from mechanism to druggable targets

BACKGROUND

Atherosclerosis is a chronic and complex disease caused by lipid disorder, inflammation, and other factors. It is closely related to cardiovascular diseases, the chief cause of death globally. Peroxisome proliferator-activated receptors (PPARs) are valuable anti-atherosclerosis targets that showcase multiple roles at different pathological stages of atherosclerosis and for cell types at different tissue sites.

AIM OF REVIEW

Considering the spatial and temporal characteristics of the pathological evolution of atherosclerosis, the roles and pharmacological and clinical studies of PPARs were summarized systematically and updated under different pathological stages and in different vascular cells of atherosclerosis. Moreover, selective PPAR modulators and PPAR-pan agonists can exert their synergistic effects meanwhile reducing the side effects, thereby providing novel insight into future drug development for precise spatial-temporal therapeutic strategy of anti-atherosclerosis targeting PPARs.

KEY SCIENTIFIC

Concepts of Review: Based on the spatial and temporal characteristics of atherosclerosis, we have proposed the importance of stage- and cell type-dependent precision therapy. Initially, PPARs improve endothelial cells' dysfunction by inhibiting inflammation and oxidative stress and then regulate macrophages' lipid metabolism and polarization to improve fatty streak. Finally, PPARs reduce fibrous cap formation by suppressing the proliferation and migration of vascular smooth muscle cells (VSMCs). Therefore, research on the cell type-specific mechanisms of PPARs can provide the foundation for space-time drug treatment. Moreover, pharmacological studies have demonstrated that several drugs or compounds can exert their effects by the activation of PPARs. Selective PPAR modulators (that specifically activate gene subsets of PPARs) can exert tissue and cell-specific effects. Furthermore, the dual- or pan-PPAR agonist could perform a better role in balancing efficacy and side effects. Therefore, research on cells/tissue-specific activation of PPARs and PPAR-pan agonists can provide the basis for precision therapy and drug development of PPARs.

The arachidonic acid metabolome reveals elevation of prostaglandin E2 biosynthesis in colorectal cancer

Arachidonic acid metabolites are a family of bioactive lipids derived from membrane phospholipids. They are involved in cancer progression, but arachidonic acid metabolite profiles and their related biosynthetic pathways remain uncertain in colorectal cancer (CRC). To compare the arachidonic acid metabolite profiles between CRC patients and healthy controls, quantification was performed using a liquid chromatography-mass spectrometry-based analysis of serum and tissue samples. Metabolomics analysis delineated the distinct oxidized lipids in CRC patients and healthy controls. Prostaglandin (PGE2)-derived metabolites were increased, suggesting that the PGE2 biosynthetic pathway was upregulated in CRC. The qRT-PCR and immunohistochemistry analyses showed that the expression level of PGE2 synthases, the key protein of PGE2 biosynthesis, was upregulated in CRC and positively correlated with the CD68+ macrophage density and CRC development. Our study indicates that the PGE2 biosynthetic pathway is associated with macrophage infiltration and progression of CRC tumors.

Human tissue-resident peritoneal macrophages reveal resistance towards oxidative cell stress induced by non-invasive physical plasma

In the context of multimodal treatments for abdominal cancer, including procedures such as cytoreductive surgery and intraperitoneal chemotherapy, recurrence rates remain high, and long-term survival benefits are uncertain due to post-operative complications. Notably, treatment-limiting side effects often arise from an uncontrolled activation of the immune system, particularly peritoneally localized macrophages, leading to massive cytokine secretion and phenotype changes. Exploring alternatives, an increasing number of studies investigated the potential of plasma-activated liquids (PAL) for adjuvant peritoneal cancer treatment, aiming to mitigate side effects, preserve healthy tissue, and reduce cytotoxicity towards non-cancer cells. To assess the non-toxicity of PAL, we isolated primary human macrophages from the peritoneum and subjected them to PAL exposure. Employing an extensive methodological spectrum, including flow cytometry, Raman microspectroscopy, and DigiWest protein analysis, we observed a pronounced resistance of macrophages towards PAL. This resistance was characterized by an upregulation of proliferation and anti-oxidative pathways, countering PAL-derived oxidative stress-induced cell death. The observed cellular effects of PAL treatment on human tissue-resident peritoneal macrophages unveil a potential avenue for PAL-derived immunomodulatory effects within the human peritoneal cavity. Our findings contribute to understanding the intricate interplay between PAL and macrophages, shedding light on the promising prospects for PAL in the adjuvant treatment of peritoneal cancer.

Bulk and single-cell sequencing identified a prognostic model based on the macrophage and lipid metabolism related signatures for osteosarcoma patients

The introduction of multidrug combination chemotherapy has significantly advanced the long-term survival prospects for osteosarcoma (OS) patients over the past decades. However, the escalating prevalence of chemoresistance has emerged as a substantial impediment to further advancements, necessitating the formulation of innovative strategies. Our present study leveraged sophisticated bulk and single-cell sequencing techniques to scrutinize the OS immune microenvironment, unveiling a potential association between the differentiation state of macrophages and the efficacy of OS chemotherapy. Notably, we observed that a heightened presence of lipid metabolism genes and pathways in predifferentiated macrophages, constituting the major cluster of OS patients exhibiting a less favorable response to chemotherapy. Subsequently, we developed a robust Macrophage and Lipid Metabolism (MLMR) risk model and a nomogram, both of which demonstrated commendable prognostic predictive performance. Furthermore, a comprehensive investigation into the underlying mechanisms of the risk model revealed intricate associations with variations in the immune response among OS patients. Finally, our meticulous drug sensitivity analysis identified a spectrum of potential therapeutic agents for OS, including AZD2014, Sapitinib, Buparlisib, Afuresertib, MIRA-1, and BIBR-1532. These findings significantly augment the therapeutic arsenal available to clinicians managing OS, presenting a promising avenue for elevating treatment outcomes.

Iron Load Toxicity in Medicine: From Molecular and Cellular Aspects to Clinical Implications

Iron is essential for all organisms and cells. Diseases of iron imbalance affect billions of patients, including those with iron overload and other forms of iron toxicity. Excess iron load is an adverse prognostic factor for all diseases and can cause serious organ damage and fatalities following chronic red blood cell transfusions in patients of many conditions, including hemoglobinopathies, myelodyspasia, and hematopoietic stem cell transplantation. Similar toxicity of excess body iron load but at a slower rate of disease progression is found in idiopathic haemochromatosis patients. Excess iron deposition in different regions of the brain with suspected toxicity has been identified by MRI T2* and similar methods in many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Based on its role as the major biological catalyst of free radical reactions and the Fenton reaction, iron has also been implicated in all diseases associated with free radical pathology and tissue damage. Furthermore, the recent discovery of ferroptosis, which is a cell death program based on free radical generation by iron and cell membrane lipid oxidation, sparked thousands of investigations and the association of iron with cardiac, kidney, liver, and many other diseases, including cancer and infections. The toxicity implications of iron in a labile, non-protein bound form and its complexes with dietary molecules such as vitamin C and drugs such as doxorubicin and other xenobiotic molecules in relation to carcinogenesis and other forms of toxicity are also discussed. In each case and form of iron toxicity, the mechanistic insights, diagnostic criteria, and molecular interactions are essential for the design of new and effective therapeutic interventions and of future targeted therapeutic strategies. In particular, this approach has been successful for the treatment of most iron loading conditions and especially for the transition of thalassemia from a fatal to a chronic disease due to new therapeutic protocols resulting in the complete elimination of iron overload and of iron toxicity.