Ferroptosis: Can Iron be the Last or Cure for a Cell?

Ferroptosis is one of the forms of programmed cell death. Besides being a necessary micronutrient, iron is the key element that initiates ferroptosis in the cell. Intracellular unstable iron accumulation increases the amount of intracellular ROS, especially by the peroxidation of unsaturated membrane phospholipids. Insufficient antioxidant capacity and decreased glutathione levels play an important role in this process. The research reveals that an imbalance between unoxidized polyunsaturated fatty acids (PUFAs) and oxidized PUFAs, particularly oxidized arachidonic acid, accelerates ferroptosis. These oxidative reactions change the permeability of lysosomal and cellular membranes and cell death occurs. Iron chelators, lipophilic antioxidants, and specific inhibitors prevent ferroptosis. In addition to being accepted as a physiological process, it seems to be associated with tissue reperfusion damage, ischemic, neurodegenerative diseases, hematological and nephrological disorders. Ferroptosis is also being explored as a treatment option where it may offer a treatment option for some types of cancer. In this section, the brief history of ferroptosis, its morphological, molecular, and pathophysiological features are mentioned. Ferroptosis seems to be a rich field of research as a treatment option for many diseases in the future.

Role of fatty acids in inflammation, atherosclerosis, metabolic disorders and gout

Fatty acids (FA) are present in all types of organisms and play an important role in energy metabolism. The length and number of double bonds in the FA of membrane phospholipids determine the viscosity, the activity of transport systems and enzymes, and also the susceptibility to lipid peroxidation. The review discusses the influence of free unsaturated FAs with short and long chains on various inflammatory mechanisms, including atherosclerosis. It has been shown that FAs can reduce endothelial activation and affect the metabolism of eicosanoids. A new model of fundamental factors determining the variability of the timing, degree and duration of acute inflammatory reactions in the deposition of urate crystals in tissues, in which FAs play an important role is considered, using gout as an example. In the future, the study of FAs will expand the understanding of the pathophysiology of chronic inflammation in various diseases, metabolic disorders and atherosclerosis and enable the development of new treatment strategies.

Olive Oil Extracts and Oleic Acid Attenuate the LPS-Induced Inflammatory Response in Murine RAW264.7 Macrophages but Induce the Release of Prostaglandin E2

Olive oil contains high amounts of oleic acid (OA). Although OA has been described to inhibit inflammatory processes, the effects of olive oil on cellular mechanisms remain poorly understood. Therefore, we compared the effects of major fatty acids (FA) from olive oil with those of olive oil extracts (OOE) on inflammatory mediators and alterations in the cellular phospholipid composition in murine macrophages. Upon treatment with different OOE, FA compositions of lipopolysaccharide (LPS)-stimulated murine RAW264.7 macrophages were analyzed using gas chromatography. Olive oil extracts and OA significantly reduced the LPS-induced expression of inducible nitric oxide synthase (iNos), cyclooxygenase (Cox2), and interleukin-6 mRNA. In addition, a significant decrease in Cox2 and iNos protein expression was observed. The formation of nitric oxide was significantly reduced, while the formation of prostaglandin (PG) E2 from arachidonic acid significantly increased after treatment with OOE or OA. The latter was associated with a shift in the phospholipid FA composition from arachidonic acid to OA, resulting in an elevated availability of arachidonic acid. Together, OOE and OA mediate anti-inflammatory effects in vitro but increase the release of arachidonic acid and hereinafter PGE2, likely due to elongation of OA and competitive incorporation of fatty acids into membrane phospholipids.

Characterization of the Glehnia littoralis Non-specific Phospholipase C Gene GlNPC3 and Its Involvement in the Salt Stress Response

Glehnia littoralis is a medicinal halophyte that inhabits sandy beaches and has high ecological and commercial value. However, the molecular mechanism of salt adaptation in G. littoralis remains largely unknown. Here, we cloned and identified a non-specific phospholipase C gene (GlNPC3) from G. littoralis, which conferred lipid-mediated signaling during the salt stress response. The expression of GlNPC3 was induced continuously by salt treatment. Overexpression of GlNPC3 in Arabidopsis thaliana increased salt tolerance compared to wild-type (WT) plants. GlNPC3-overexpressing plants had longer roots and higher fresh and dry masses under the salt treatment. The GlNPC3 expression pattern revealed that the gene was expressed in most G. littoralis tissues, particularly in roots. The subcellular localization of GlNPC3 was mainly at the plasma membrane, and partially at the tonoplast. GlNPC3 hydrolyzed common membrane phospholipids, such as phosphotidylserine (PS), phosphoethanolamine (PE), and phosphocholine (PC). In vitro enzymatic assay showed salt-induced total non-specific phospholipase C (NPC) activation in A. thaliana GlNPC3-overexpressing plants. Plant lipid profiling showed a significant change in the membrane-lipid composition of A. thaliana GlNPC3-overexpressing plants compared to WT after the salt treatment. Furthermore, downregulation of GlNPC3 expression by virus-induced gene silencing in G. littoralis reduced the expression levels of some stress-related genes, such as SnRK2, P5SC5, TPC1, and SOS1. Together, these results indicated that GlNPC3 and GlNPC3-mediated membrane lipid change played a positive role in the response of G. littoralis to a saline environment.

A secretory phospholipase D hydrolyzes phosphatidylcholine to suppress rice heading time

Phospholipase D (PLD) hydrolyzes membrane phospholipids and is crucial in various physiological processes and transduction of different signals. Secretory phospholipases play important roles in mammals, however, whose functions in plants remain largely unknown. We previously identified a rice secretory PLD (spPLD) that harbors a signal peptide and here we reported the secretion and function of spPLD in rice heading time regulation. Subcellular localization analysis confirmed the signal peptide is indispensable for spPLD secretion into the extracellular spaces, where spPLD hydrolyzes substrates. spPLD overexpression results in delayed heading time which is dependent on its secretory character, while suppression or deficiency of spPLD led to the early heading of rice under both short-day and long-day conditions, which is consistent with that spPLD overexpression/suppression indeed led to the reduced/increased Hd3a/RFT1 (Arabidopsis Flowing Locus T homolog) activities. Interestingly, rice Hd3a and RFT1 bind to phosphatidylcholines (PCs) and a further analysis by lipidomic approach using mass spectrometry revealed the altered phospholipids profiles in shoot apical meristem, particularly the PC species, under altered spPLD expressions. These results indicate the significance of secretory spPLD and help to elucidate the regulatory network of rice heading time.

51 Palmitoylethanolamide associated to polydatin reduces inflammation in human endothelial vascular cells exposed to doxorubicin and trastuzumab through PPAR-a and NLRP3-related pathways

Aims Palmitoylethanolamide is an endogenous fatty acid mediator that is synthetized from membrane phospholipids by N-acyl phosphatidylethanolamine phospholipase D. Polydatin is a nutraceutical agent derived from trans-resveratrol with established anti-inflammatory and anti-atherogenic properties. We aimed to assess whether palmitoylethanolamide combined to polydatin, co-incubated during doxorubicin and trastuzumab, reduces anticancer drugs-related cardiotoxicity in cellular models. Methods Human vascular endothelial cells were exposed to subclinical concentration of doxorubicin (at 100 and 200 nM) combined to trastuzumab (at 100 and 200 nM) alone or in combination with a formulation composed by palmitoylethanolamide and polydatin (500 nM and 50 µM, respectively) for 48 h. After the incubation period, we performed the following tests: determination of cell viability, through analysis of mitochondrial dehydrogenase activity, study of lipid peroxidation (quantifying cellular Malondialdehyde and 4-hydroxynonenal), intracellular Ca2+ homeostasis. Moreover, pro-inflammatory studied were also performed (activation of NLRP3 inflammasome; expression of peroxisome proliferator-activated receptor-α; mTORC1 Fox01/3a; transcriptional activation of p65/NF-κB and secretion of cytokines involved in cardiotoxicity (Interleukins 1β, 8, 6). Results Palmitoylethanolamide combined to polydatin co-incubated with doxorubicin exerts vasculoprotective effects, enhancing cell viability of 54.7–68.3% compared to untreated cells (P < 0.001 for all). The formulation reduced significantly the cardiotoxicity through peroxisome proliferator-activated receptor-α–related pathways and NLRP3 inflammasome but without the involvement of calcium homeostasis. Conclusion The present study demonstrates that palmitoylethanolamide and polydatin protects against vasculotoxicity of doxorubicin and trastuzumab by promoting an anti-inflammatory phenotype, representing a new therapeutic approach to resolve doxorubicin-induced vasculotoxicity and inflammation.

Incidence of antiphospholipid antibodies in new patients with non-Hodgkin lymphoma

Non-Hodgkin’s lymphoma (NHL) presents a group of histologically and biologically inhomogeneous B and T cell neoplasms of lymphoid tissue with a completely unidentified etiology. Antiphospholipid antibodies (aPL) are antibodies produced as a result of misinterpretation of platelet membrane phospholipids. It is well known that antiphospholipid antibodies are general risk factors that induce the disorder of the physiological process of hemostasis. Respectively, it is interesting to appreciate the incidence of antiphospholipid antibodies in new non-Hodgkin lymphomas patients depending on age, sex, type of non-Hodgkin’s lymphoma, the peculiarities of the onset of the disease, the degree of disease spread. According to the results of our study, we found a 14.8% incidence of aPL in primary patients with non-Hodgkin’s lymphoma, more frequently in men and people older than 50 years. The positivity of aPL antibodies depended on the immunohistochemical type of malignant lymphoma, the degree of dissemination of the tumor process and independent of the location of the tumor focus (nodal or extranodal) of NHL. The incidence of aPL antibody types was uneven with the obvious predominance of lupus anticoagulant. Th is study allowed the evaluation of the incidence of antiphospholipid antibodies in primary patients with non-Hodgkin’s lymphoma.

A Brief Introduction to Some Aspects of the Fluid–Mosaic Model of Cell Membrane Structure and Its Importance in Membrane Lipid Replacement

Early cell membrane models placed most proteins external to lipid bilayers in trimolecular structures or as modular lipoprotein units. These thermodynamically untenable structures did not allow lipid lateral movements independent of membrane proteins. The Fluid–Mosaic Membrane Model accounted for these and other properties, such as membrane asymmetry, variable lateral mobilities of membrane components and their associations with dynamic complexes. Integral membrane proteins can transform into globular structures that are intercalated to various degrees into a heterogeneous lipid bilayer matrix. This simplified version of cell membrane structure was never proposed as the ultimate biomembrane description, but it provided a basic nanometer scale framework for membrane organization. Subsequently, the structures associated with membranes were considered, including peripheral membrane proteins, and cytoskeletal and extracellular matrix components that restricted lateral mobility. In addition, lipid–lipid and lipid–protein membrane domains, essential for cellular signaling, were proposed and eventually discovered. The presence of specialized membrane domains significantly reduced the extent of the fluid lipid matrix, so membranes have become more mosaic with some fluid areas over time. However, the fluid regions of membranes are very important in lipid transport and exchange. Various lipid globules, droplets, vesicles and other membranes can fuse to incorporate new lipids or expel damaged lipids from membranes, or they can be internalized in endosomes that eventually fuse with other internal vesicles and membranes. They can also be externalized in a reverse process and released as extracellular vesicles and exosomes. In this Special Issue, the use of membrane phospholipids to modify cellular membranes in order to modulate clinically relevant host properties is considered.

Helicobacter pylori FabX contains a [4Fe-4S] cluster essential for unsaturated fatty acid synthesis

Unsaturated fatty acids (UFAs) are essential for functional membrane phospholipids in most bacteria. The bifunctional dehydrogenase/isomerase FabX is an essential UFA biosynthesis enzyme in the widespread human pathogen Helicobacter pylori, a bacterium etiologically related to 95% of gastric cancers. Here, we present the crystal structures of FabX alone and in complexes with an octanoyl-acyl carrier protein (ACP) substrate or with holo-ACP. FabX belongs to the nitronate monooxygenase (NMO) flavoprotein family but contains an atypical [4Fe-4S] cluster absent in all other family members characterized to date. FabX binds ACP via its positively charged α7 helix that interacts with the negatively charged α2 and α3 helices of ACP. We demonstrate that the [4Fe-4S] cluster potentiates FMN oxidation during dehydrogenase catalysis, generating superoxide from an oxygen molecule that is locked in an oxyanion hole between the FMN and the active site residue His182. Both the [4Fe-4S] and FMN cofactors are essential for UFA synthesis, and the superoxide is subsequently excreted by H. pylori as a major resource of peroxide which may contribute to its pathogenic function in the corrosion of gastric mucosa.

Lipid droplets are required for lipid mediator production and cancer cell proliferation

Lipid droplets are dynamic organelles with a central role in fatty acid metabolism. They protect cells from lipotoxicity by sequestering excess fatty acids but also provide fatty acids for metabolic reactions and signalling events. Here we show that lipid droplet turnover in cancer cells is required for production of ω-3 and ω-6 polyunsaturated fatty acid (PUFA)-derived inflammatory lipid mediators, including eicosanoids and specialised pro-resolving mediators. We show that incorporation of PUFAs into triglycerides mediated by diacylglycerol acyltransferase 1 (DGAT1), and their release by adipose triglyceride lipase (ATGL), are required for cyclooxygenase- and lipoxygenase-dependent lipid mediator production and cancer cell proliferation. The human group X secreted phospholipase A2 (hGX sPLA2) drives the delivery of membrane-derived PUFAs into lipid droplets, while ATGL promotes the incorporation of lipid droplet-derived PUFAs into phospholipids. The group IVA cytosolic PLA2 (cPLA2α) acts on membrane phospholipids and complements ATGL in the regulation of PUFA trafficking between phospholipids and triglycerides. This study identifies lipid droplets as essential cellular hubs that control PUFA availability for production of lipid mediators involved in inflammation and tumorigenesis.