The role of phospholipid oxidation products in inflammatory and autoimmune diseases: evidence from animal models and in humans

Obesity and lipid metabolism in the development of osteoporosis (Review)

Osteoporosis is a common bone metabolic disease that causes a heavy social burden and seriously threatens life. Improving osteogenic capacity is necessary to correct bone mass loss in the treatment of osteoporosis. Osteoblasts are derived from the differentiation of bone marrow mesenchymal stem cells, a process that opposes adipogenic differentiation. The peroxisome proliferator‑activated receptor γ and Wnt/β‑catenin signaling pathways mediate the mutual regulation of osteogenesis and adipogenesis. Lipid substances play an important role in the occurrence and development of osteoporosis. The content and proportion of lipids modulate the activity of immunocytes, mainly macrophages, and the secretion of inflammatory factors, such as IL‑1, IL‑6 and TNF‑α. These inflammatory effectors increase the activity and promote the differentiation of osteoclasts, which leads to bone imbalance and stronger bone resorption. Obesity also decreases the activity of antioxidases and leads to oxidative stress, thereby inhibiting osteogenesis. The present review starts by examining the bidirectional differentiation of BM‑MSCs, describes in detail the mechanism by which lipids affect bone metabolism, and discusses the regulatory role of inflammation and oxidative stress in this process. The review concludes that a reasonable adjustment of the content and proportion of lipids, and the alleviation of inflammatory storms and oxidative damage induced by lipid imbalances, will improve bone mass and treat osteoporosis.

Beneficial Effects of Plant Oils Supplementation on Multiple Sclerosis: A Comprehensive Review of Clinical and Experimental Studies

Multiple sclerosis disease (MS) is a 38.5 chronic neurological autoimmune disease that affects the nervous system, and its incidence is increasing globally. At present, there is no cure for this disease, and with its severity and disabling variety, it is important to search for possibilities that could help to slow its progression. It is recognized that the mechanisms of MS pathology, its development and degree of activity can be affected by dietary factors. In this review, the beneficial health effects of 10 plants oils-mainly seed oils, including pomegranate seed oil, sesame oil, acer truncatum bunge seed oil, hemp seeds oil, evening primrose seed oil, coconut oil, walnut oil, essential oil from Pterodon emarginatus seeds, flaxseed oil and olive oil-on MS are discussed. The literature data indicate that plant oils could be effective for the treatment of MS and its related symptoms primarily through reducing inflammation, promoting remyelination, immunomodulation and inhibiting oxidative stress. Plant oils may potentially reduce MS progression. Longitudinal research including a larger sample size with a longer duration is essential to confirm the findings from the selected plant oils. Moreover, new plant oils should be studied for their potential MS benefit.

The Role of the Oxidative State and Innate Immunity Mediated by TLR7 and TLR9 in Lupus Nephritis

Lupus nephritis (LN) is a severe complication of systemic lupus erythematosus (SLE) and is considered one of the leading causes of mortality. Multiple immunological pathways are involved in the pathogenesis of SLE, which makes it imperative to deepen our knowledge about this disease's immune-pathological complexity and explore new therapeutic targets. Since an altered redox state contributes to immune system dysregulation, this document briefly addresses the roles of oxidative stress (OS), oxidative DNA damage, antioxidant enzymes, mitochondrial function, and mitophagy in SLE and LN. Although adaptive immunity's participation in the development of autoimmunity is undeniable, increasing data emphasize the importance of innate immunity elements, particularly the Toll-like receptors (TLRs) that recognize nucleic acid ligands, in inflammatory and autoimmune diseases. Here, we discuss the intriguing roles of TLR7 and TLR9 in developing SLE and LN. Also included are the essential characteristics of conventional treatments and some other novel and little-explored alternatives that offer options to improve renal function in LN.

Evaluation of thiol/disulfide hemostasis and serum Ischemia modified albumin as oxidative stress biomarkers in systemic lupus erythematosus patients: Relationship with major organ involvement and disease activity

OBJECTIVES

We aimed to compare thiol/disulfide hemostasis and serum ischemia-modified albumin (IMA) levels, which are indicators of oxidative stress (OS), in patients with systemic lupus erythematosus (SLE), with the healthy control (HC) group and to evaluate the relationship of these parameters with disease activity and major organ involvement.

MATERIAL-METHODS

Eighty-four SLE patients and 96 HCs were included in this study. The disease activity of SLE patients was calculated using The Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K). Patients with SLEDAI-2K ≤ 5 were classified as low disease activity (LDA) and those with SLEDAI-2K > 6 as high disease activity (HDA). Thiol/disulfide hemostasis was evaluated using a new automated method and natural thiol (NT), total thiol (TT), disulfide (SS) levels, SS/NT, SS/TT, NT/TT ratios, and serum IMA levels were recorded.

RESULTS

NT and TT levels were significantly lower (490.11 ± 123.61 vs 536.96 ± 86.05, p = 0.003) (532.56 ± 125.80 vs 565.72 ± 89.82, p = 0.046), SS level (21.22 ± 11.75 vs 13.37 ± 9.31, p < 0.001) was higher, and SS/TT (4.64 ± 2.93 vs 2.52 ± 1.82, p < 0.001) and SS/NT (4.12 ± 2.33 vs 2.35 ± 1.59, p < 0.001) ratios were significantly higher in SLE patients compared to HCs. IMA values were not different between the two groups (p = 0.920). NT (449.84 ± 136.98 vs 520.32 ± 104.11, p = 0.012) and TT levels (492.01 ± 138.45±562.97 ± 107.09, p = 0.013) were significantly lower and serum IMA levels (0.802 ± 0.089 vs 0.764 ± 0.040, p = 0.023) were significantly higher in SLE patients with HDA than in LDA patients. There was a weak negative correlation between NT (r = -0.284, p=0.009) (r = -0.291, p = 0.007) and TT levels (r = -0.281, p = 0.010) (r = -0.289, p = 0.008) and a weak positive correlation between IMA levels (r = 0.279, p = 0.011) (r = 0.263, p = 0.016) and SLEDAI-2K, and major organ involvement.

CONCLUSION

It is thought that thiol/disulfide hemostasis and IMA levels may be used as ideal biomarkers of OS in SLE patients and may reflect the disease activity and major organ involvement.

Unravelling hierarchical levels of structure in lipid membranes

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A set of hierarchical levels of structure can be proposed for lipid bilayers.

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The composition of a lipid bilayer is identified as a fluid version of primary structure.

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The interaction between leaflets is taken as the secondary structure of lipid bilayers.

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A method to identify membrane domains and their interaction is proposed as a third level of structure.

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The highly specific lipid perturbation around embedded macromolecules is taken as the quaternary level of structure.

In analogy with the hierarchical levels typically used to describe the structure of nucleic acids or proteins and keeping in mind that lipid bilayers are not just mere envelopers for biological material but directly responsible for many important functions of life, it is discussed here how membrane models can also be interpreted in terms of different hierarchies in their structure. Namely, lipid composition, interaction between leaflets, existence and interaction of domains arising from the coordinate behavior of lipids and their properties, plus the manifest and specific perturbation of the lipid organization around macromolecules embedded in a membrane are hereby used to define the primary, secondary, tertiary and quaternary structures, respectively. Molecular Dynamics simulations are used to illustrate this proposal. Alternative levels of organization and methods to define domains can be proposed but the final aim is to highlight the paradigm arising from this description which is expected to have significant consequences on deciphering the underlying factors governing membranes and their interactions with other molecules.

Diet and Hygiene in Modulating Autoimmunity During the Pandemic Era

The immune system is an efficiently toned machinery that discriminates between friends and foes for achieving both host defense and homeostasis. Deviation of immune recognition from foreign to self and/or long-lasting inflammatory responses results in the breakdown of tolerance. Meanwhile, educating the immune system and developing immunological memory are crucial for mounting defensive immune responses while protecting against autoimmunity. Still to elucidate is how diverse environmental factors could shape autoimmunity. The emergence of a world pandemic such as SARS-CoV-2 (COVID-19) not only threatens the more vulnerable individuals including those with autoimmune conditions but also promotes an unprecedented shift in people's dietary approaches while urging for extraordinary hygiene measures that likely contribute to the development or exacerbation of autoimmunity. Thus, there is an urgent need to understand how environmental factors modulate systemic autoimmunity to better mitigate the incidence and or severity of COVID-19 among the more vulnerable populations. Here, we discuss the effects of diet (macronutrients and micronutrients) and hygiene (the use of disinfectants) on autoimmunity with a focus on systemic lupus erythematosus.

UCTD and SLE patients show increased levels of oxidative and DNA damage together with an altered kinetics of DSB repair

Immunological tolerance is a critical feature of the immune system; its loss might lead to an abnormal response of lymphocytes causing autoimmune diseases. One of the most important groups belonging to autoimmune disorders is the connective tissue diseases (CTD). CTD are classified among systemic rheumatic diseases and include pathologies such as systemic lupus erythematosus (SLE), and undifferentiated CTD (UCTD). In this study, we evaluated oxidative and genome damage in peripheral blood lymphocytes from patients with SLE and UCTD, further classified on the basis of disease activity and the presence/absence of a serological profile. Oxidative damage was evaluated in cell membrane using the fluorescent fatty acid analogue BODIPY 581/591 C11. The percentage of oxidised lymphocytes in both SLE and UCTD patients was higher than in the control group, and the oxidative stress correlated positively with both disease activity and autoantibody profile. The γH2AX focus assay was used to quantify the presence of spontaneous double strand breaks (DSBs), and to assess the abilities of DSBs repair system after T cells were treated with mitomycin C (MMC). Subjects with these autoimmune disorders showed a higher number of γH2AX foci than healthy controls, but no correlation with diseases activity and presence of serological profile was observed. In addition, patients displayed an altered response to MMC-induced DSBs, which led their peripheral cells to greatly increase apoptosis. Taken together our results confirmed an interplay among oxidative stress, DNA damage and impaired DNA repair, which are directly correlated to the aggressiveness and clinical progression of the diseases. We propose the evaluation of these molecular markers to better characterize SLE and UCTD, aiming to improve the treatment plan and the quality of the patients' life.

Therapeutic Potential and Immunomodulatory Role of Coenzyme Q10 and Its Analogues in Systemic Autoimmune Diseases

Coenzyme Q₁₀ (CoQ₁₀) is a mitochondrial electron carrier and a powerful lipophilic antioxidant located in membranes and plasma lipoproteins. CoQ₁₀ is endogenously synthesized and obtained from the diet, which has raised interest in its therapeutic potential against pathologies related to mitochondrial dysfunction and enhanced oxidative stress. Novel formulations of solubilized CoQ₁₀ and the stabilization of reduced CoQ₁₀ (ubiquinol) have improved its bioavailability and efficacy. Synthetic analogues with increased solubility, such as idebenone, or accumulated selectively in mitochondria, such as MitoQ, have also demonstrated promising properties. CoQ₁₀ has shown beneficial effects in autoimmune diseases. Leukocytes from antiphospholipid syndrome (APS) patients exhibit an oxidative perturbation closely related to the prothrombotic status. In vivo ubiquinol supplementation in APS modulated the overexpression of inflammatory and thrombotic risk-markers. Mitochondrial abnormalities also contribute to immune dysregulation and organ damage in systemic lupus erythematosus (SLE). Idebenone and MitoQ improved clinical and immunological features of lupus-like disease in mice. Clinical trials and experimental models have further demonstrated a therapeutic role for CoQ₁₀ in Rheumatoid Arthritis, multiple sclerosis and type 1 diabetes. This review summarizes the effects of CoQ₁₀ and its analogs in modulating processes involved in autoimmune disorders, highlighting the potential of these therapeutic approaches for patients with immune-mediated diseases.

The role of oxidized phospholipids in the development of disease

Oxidized phospholipids (OxPLs), complex mixtures of phospholipid oxidation products generated during normal or pathological processes, are increasingly recognized to show bioactive effects on many cellular signalling pathways. There is a growing body of evidence showing that OxPLs play an important role in many diseases, so it is essential to define the specific role of OxPLs in different diseases for the design of disease therapies. In vastly diverse pathological processes, OxPLs act as pro-inflammatory agents and contribute to the progression of many diseases; in addition, they play a role in anti-inflammatory processes, promoting the dissipation of inflammation and inhibiting the progression of some diseases. In addition to participating in the regulation of inflammatory responses, OxPLs affect the occurrence and development of diseases through other pathways, such as apoptosis promotion. In this review, the different and even opposite effects of different OxPL molecular species are discussed. Furthermore, the specific effects of OxPLs in various diseases, as well as the receptor and cellular mechanisms involved, are summarized.

Erythrocytes as markers of oxidative stress related pathologies

Erythrocytes are deeply sensitive cells and important health indicators. During inflammatory response RBC, as a part of haematological system, are exposed to circulating inflammatory mediators and related oxidative stress. They present a highly specialized and organized cell membrane that interacts with inflammatory mediators and oxidative agents, leading to a variety of structural changes that promptly signal an abnormal situation. This review is aimed to provide an overview on erythrocyte involvement in physiological and pathological processes related to oxidative stress, such as aging, Down syndrome, neurodegenerative diseases, for instance Alzheimer Disease, erectile dysfunction and cardiovascular diseases. In particular this review will focus on the effects of oxidative stress on structural changes in the cell membrane and also on in the activity of erythrocyte enzymes such as membrane-bound, cytosolic glycohydrolases and RBC-eNOS. This review also underlines the potential clinical application of erythrocyte specific related parameters, which can be important tools not only for the study but also for the monitoring of several oxidative stress related diseases.

Evaluation of air oxidized PAPC: A multi laboratory study by LC-MS/MS

Oxidized LDL (oxLDL) has been shown to play a crucial role in the onset and development of cardiovascular disorders. The study of oxLDL, as an initiator of inflammatory cascades, led to the discovery of a variety of oxidized phospholipids (oxPLs) responsible for pro-inflammatory actions. Oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC) is frequently used by the scientific community as a representative oxPL mixture to study the biological effects of oxidized lipids, due to the high abundance of PAPC in human tissues and the biological activities of oxidized arachidonic acids derivatives. Most studies focusing on oxPAPC effects rely on in-house prepared mixtures of oxidized species obtained by exposing PAPC to air oxidation. Here, we described a multi-laboratory evaluation of the compounds in oxPAPC by LC-MS/MS, focusing on the identification and relative quantification of the lipid peroxidation products (LPPs) formed. PAPC was air-oxidized in four laboratories using the same protocol for 0, 48, and 72 h. It was possible to identify 55 different LPPs with unique elemental composition and characterize different structural isomeric species within these. The study showed good intra-sample reproducibility and similar qualitative patterns of oxidation, as the most abundant LPPs were essentially the same between the four laboratories. However, there were substantial differences in the extent of oxidation, i.e. the amount of LPPs relative to unmodified PAPC, at specific time points. This shows the importance of characterizing air-oxidized PAPC preparations before using them for testing biological effects of oxidized lipids, and may explain some variability of effects reported in the literature.

Health Risk Assessment of Occupationally Pesticide-Exposed Population of Cancer Prone Area of Punjab

The alarming health issues especially the unusually high number of cancer cases in agriculture community of Bathinda district of Punjab (India) is a serious concern. There is limited knowledge about the role of gene-environment interactions in oncogenesis prevalent in this area. The aim of this study was to evaluate the association of oxidative stress with CYP1A2, CYP2B6, CYP2C9, CYP3A4, and PON1 genetic variation in the pesticide-exposed (occupationally) population of Bathinda district of Punjab (India). This study demonstrated significantly elevated relative risk (RR) of lower antioxidant defense mechanism (Glutathione, Catalase, Superoxide Dismutase, Glutathione peroxidases, and Glutathione Reductase) in occupationally pesticide-exposed group (n = 120) as compared with unexposed group (n = 84) from Bathinda district of Punjab (India). Our data shows pesticide exposure to be a major risk factor leading to increased oxidative stress inside the body. Gas chromatographic analysis revealed the residues of organophosphates (chlorpyriphos, dichlorvos, ethoprophos) and herbicides (atrazine, butachlor, alachlor, metolachlor) in the blood samples of the exposed population. In vitro results showed a dose dependent decrease in cell viability following treatment of pesticides detected in blood samples in hPBMCs and A549 cell line. Genetic variation analysis revealed missense mutations in CYP2B6 (2 mutations), CY3A4 (1 mutation), and CYP2C9 (2 mutations). The observed mutations have been predicted to cause structural and conformation change in protein structure which could result in altered stability. In first of its kind of study, our data reveal oxidative stress and pesticide residue accumulation inside the body to be the major reasons for health concerns in Bathinda district.

Necrosis Driven Triglyceride Synthesis Primes Macrophages for Inflammation During Mycobacterium tuberculosis Infection

Pulmonary tuberculosis (TB) exhibits granulomatous inflammation, a site of controlling bacterial dissemination at the cost of host tissue damage. Intrigued by the granuloma type-dependent expression of inflammatory markers in TB, we sought to investigate underlying metabolic changes that drive amplification of inflammation in TB. Here, we show an association of higher inflammation in necrotic granulomas with the presence of triglyceride (TG)-rich foamy macrophages. The conspicuous absence of these macrophages in solid granulomas identified a link between the ensuing pathology and the metabolic programming of foamy macrophages. Consistent with in vivo findings, in vitro infection of macrophages with Mycobacterium tuberculosis (Mtb) led to increase in TG synthesis only under conditions of ~60% necrosis. Genetic and pharmacologic intervention that reduced necrosis prevented this bystander response. We further demonstrate that necrosis independent of Mtb also elicits the same bystander response in human macrophages. We identified a role for the human enzyme involved in TG synthesis, diacylglycerol O-acyltransferase (DGAT1), in this phenomenon. The increased TG levels in necrosis-associated foamy macrophages promoted the pro-inflammatory state of macrophages to infection while silencing expression of diacylglycerol O-acyltransferase (DGAT1) suppressed expression of pro-inflammatory genes. Our data thus invoke a role for storage lipids in the heightened host inflammatory response during infection-associated necrosis. Our data provide a functional role to macrophage lipid droplets in host defense and open new avenues for developing host-directed therapies against TB.

SLE autoantibodies are well recognized by peroxynitrite-modified-HSA: Its implications in the pathogenesis of SLE

Systemic lupus erythematosus (SLE) is an autoimmune disorder where the role of inflammatory processes in the etiopathogenesis is well documented. Despite extensive research, the trigger for initiation of the disease has not been identified. Peroxynitrite, a strong nitrating/oxidizing agent has been reported in SLE and other autoimmune diseases. In this study, human serum albumin (HSA) was exposed to peroxynitrite for 30min at 37°C. The structure of HSA was grossly perturbed when examined by various physico-chemical techniques. Peroxynitrite mediated nitration of HSA was confirmed by LCMS/MS. Furthermore, increase in hydrodynamic radius of peroxynitrite-modified-HSA suggests the attachment of nitro group(s). Aggregation in peroxynitrite-modified-HSA was evident in a TEM scan. Nitration, oxidation, cross linking, aggregation etc conferred immunogenicity on peroxynitrite-modified-HSA. High titre antibodies were elicited in rabbits immunized with peroxynitrite-modified-HSA. Induced antibodies were highly specific for peroxynitrite-modified-HSA but showed considerable binding with other nitrated molecules. Direct binding/inhibition ELISA carried out with autoantibodies in SLE sera showed preferential binding with peroxynitrite-modified-HSA. Anti-nDNA positive IgG from SLE sera showed preference for peroxynitrite-modified-HSA when subjected to immunoassay (direct binding and inhibition) and mobility shift assay. Our results reinforce the role of augmented inflammation in SLE progression.

Mechanisms of atherosclerosis and cardiovascular disease in antiphospholipid syndrome and systemic lupus erythematosus. New therapeutic approaches

Systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) are 2 highly related autoimmune-rheumatic diseases associated with an increased risk of developing cardiovascular (CV) diseases. Despite the great progresses made in understanding the pathological mechanisms leading to CV diseases in those pathologies, there is still the unmet need to improve long term prognosis. CV diseases in SLE and APS is thought to happen as the result of a complex interaction between traditional CV risk factors, immune deregulation and disease activity, including the synergic effect of cytokines, chemokines, adipokines, proteases, autoantibodies, adhesion receptors, oxidative stress and a plethora of intracellular signalling molecules. Genomic and epigenomic analyses have further allowed the identification of specific signatures explaining the proathero-thrombotic profiles of APS and SLE patients. This review examines the complex role of these heterogeneous factors, and analyses new therapeutic approaches under study to reduce the CV risk in these autoimmune disorders.

Use of bedaquiline and delamanid in diabetes patients: clinical and pharmacological considerations

Antituberculosis (anti-TB) treatment may be affected by both diabetes and hypoglycemic agents in patients with these 2 comorbidities. However, data supporting this conclusion relate only to standard anti-TB therapies. Sirturo^® (bedaquiline) and Deltyba^® (delamanid), novel drugs for multidrug-resistant tuberculosis (MDR-TB), are recommended for diabetes patients when another effective treatment regimen cannot be provided. Currently, there are no clinical data related to the use of these agents in diabetes patients. Possible alterations in the pharmacokinetics of these novel drugs induced by changes in subcutaneous adipose blood flow, gastric emptying, or nephropathy in diabetes patients, and possible drug–drug interactions with hypoglycemic agents, are of special interest, since the efficacy of bedaquiline and delamanid is concentration dependent. Moreover, it is of fundamental importance to avoid possible additive or synergistic effects of adverse drug reactions in this already vulnerable patient group. We reviewed clinical particularities related to the use of bedaquiline and delamanid in patients with type 1 and 2 diabetes mellitus (DM), as well as pharmacological aspects of the concurrent use of these agents with oral and injectable hypoglycemic agents. Bedaquiline shares liver metabolic pathways with several oral hypoglycemic agents, whereas delamanid may compete with several oral hypoglycemic agents and insulin analogs at protein-binding sites. Special concern exists regarding the use of bedaquiline and delamanid in diabetes patients aged >65 years and patients with severe renal or hepatic impairment or electrolyte disturbances. Concurrent use of bedaquiline and delamanid with insulin analogs, and other hypoglycemic agents that prolong the heart rate-corrected QT interval, such as sulfonylureas and glinides, may enhance this adverse reaction. Hepatic-related adverse reactions may develop more frequently when these drugs are combined with thiazolidinediones and acarbose. Data from Phase III and postmarketing studies are needed to elucidate the effect of DM and hypoglycemic agents on bedaquiline and delamanid effects in MDR-TB patients.

Oxidative stress in the pathogenesis of atherothrombosis associated with anti-phospholipid syndrome and systemic lupus erythematosus: new therapeutic approaches

Atherothrombosis is a recurrent complication in APS and SLE patients. Oxidative stress has been suggested as a key player underlying this process. Autoantibodies have been pointed to as the main contributors to abnormality in the oxidative status observed in APS and SLE patients, promoting the increased production of oxidant species and the reduction of antioxidant molecules. This imbalance causes vascular damage through the activation of immune cells, including monocytes, lymphocytes and neutrophils, causing the expression of pro-inflammatory and procoagulant molecules, the formation of neutrophil extracellular traps and the adhesion of these cells to the endothelium; the induction of cellular apoptosis and impaired cell clearance, which in turn enhances autoantibody neogeneration; and cytotoxicity of endothelial cells. This review describes the mechanisms underlying the role of oxidative stress in the pathogenesis of atherothrombosis associated with APS and SLE, focused on the effect of autoantibodies, the different cell types involved and the diverse effectors, including cytokines, procoagulant proteins and their main modulators, such as oxidant/antioxidant species and intracellular pathways in each pathology. We further discuss new therapies aimed at restoring the oxidative stress balance and subsequently to tackle atherothrombosis in APS and SLE.

Biomarkers of oxidative stress in erythrocytes as a function of human age

Despite more than 300 theories to explain the aging process, oxidative stress theory offers the best mechanism to explain aging and age related disorders. Several studies has shown the importance of oxidative stress during aging. PubMed, Science Direct and Springer online data bases are taken into consideration to write this mini-review. Human erythrocytes are most abundant and specialized cells in the body. Erythrocytes were extensively studied due to their metabolism and gas transport functions. Recent studies on erythrocytes have provided us detailed information of cell membrane and its structural organization that may help in studying the aging and age associated changes. The susceptibility of an organism is associated with the antioxidant potential of the body. Erythrocytes have potent antioxidant protection consisting of enzymatic and non-enzymatic pathways that counteract with reactive oxygen species, thus maintaining the redox regulation in the body. The non-enzymatic and enzymatic antioxidants and other biomarkers associated with erythrocyte membrane transport functions are the main content of this review. Biomarkers of oxidative stress in erythrocytes and its membrane were taken into the consideration during human aging that will be the main subject of this mini- review.

Hydrophilic interaction liquid chromatography-electrospray ionization-tandem mass spectrometry of a complex mixture of native and oxidized phospholipids

A mixture of native and oxidized phospholipids (PLs), generated by the soybean lipoxygenase type V-catalyzed partial oxidation of a lipid extract obtained from human platelets, was analyzed by Hydrophilic Interaction Liquid Chromatography-ElectroSpray Ionization-Tandem Mass Spectrometry (HILIC-ESI-MS/MS). The complexity of the resulting mixture was remarkable, considering that the starting lipid extract, containing (as demonstrated in a previous study) about 130 native PLs, was enriched with enzymatically generated hydroperoxylated derivatives and chemically generated hydroxylated forms of PLs bearing polyunsaturated side chains. Nonetheless, the described analytical approach proved to be very powerful; indeed, focusing on phosphatidylcolines (PCs), the most abundant PL class in human platelets, about fifty different native/oxidized species could be identified in a single HILIC-ESI-MS/MS run. Low-energy collision induced dissociation tandem MS (CID-MS/MS) experiments on chromatographically separated species showed single neutral losses of H2O2 and H2O to be typical fragmentation pathways of hydroperoxylated PCs, whereas a single H2O loss was observed for hydroxylated ones. Moreover, diagnostic losses of n-hexanal or n-pentanol were exploited to recognize PCs hydroperoxylated on the last but five carbon atom of a ɷ-6 polyunsaturated side chain. Despite the low resolution of the 3D ion trap mass analyzer used, the described HILIC-ESI-MS/MS approach appears very promising for the identification of oxidized lipids in oxidatively stressed complex biological systems.

Treatment of a multiple sclerosis animal model by a novel nanodrop formulation of a natural antioxidant

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system and is associated with demyelination, neurodegeneration, and sensitivity to oxidative stress. In this work, we administered a nanodroplet formulation of pomegranate seed oil (PSO), denominated Nano-PSO, to mice induced for experimental autoimmune encephalomyelitis (EAE), an established model of MS. PSO comprises high levels of punicic acid, a unique polyunsaturated fatty acid considered as one of the strongest natural antioxidants. We show here that while EAE-induced mice treated with natural PSO presented some reduction in disease burden, this beneficial effect increased significantly when EAE mice were treated with Nano-PSO of specific size nanodroplets at much lower concentrations of the oil. Pathological examinations revealed that Nano-PSO administration dramatically reduced demyelination and oxidation of lipids in the brains of the affected animals, which are hallmarks of this severe neurological disease. We propose that novel formulations of natural antioxidants such as Nano-PSO may be considered for the treatment of patients suffering from demyelinating diseases. On the mechanistic side, our results demonstrate that lipid oxidation may be a seminal feature in both demyelination and neurodegeneration.

Oxidative lipidomics coming of age: advances in analysis of oxidized phospholipids in physiology and pathology

SIGNIFICANCE

Oxidized phospholipids are now well recognized as markers of biological oxidative stress and bioactive molecules with both pro-inflammatory and anti-inflammatory effects. While analytical methods continue to be developed for studies of generic lipid oxidation, mass spectrometry (MS) has underpinned the advances in knowledge of specific oxidized phospholipids by allowing their identification and characterization, and it is responsible for the expansion of oxidative lipidomics.

RECENT ADVANCES

Studies of oxidized phospholipids in biological samples, from both animal models and clinical samples, have been facilitated by the recent improvements in MS, especially targeted routines that depend on the fragmentation pattern of the parent molecular ion and improved resolution and mass accuracy. MS can be used to identify selectively individual compounds or groups of compounds with common features, which greatly improves the sensitivity and specificity of detection. Application of these methods has enabled important advances in understanding the mechanisms of inflammatory diseases such as atherosclerosis, steatohepatitis, leprosy, and cystic fibrosis, and it offers potential for developing biomarkers of molecular aspects of the diseases.

CRITICAL ISSUES AND FUTURE DIRECTIONS

The future in this field will depend on development of improved MS technologies, such as ion mobility, novel enrichment methods and databases, and software for data analysis, owing to the very large amount of data generated in these experiments. Imaging of oxidized phospholipids in tissue MS is an additional exciting direction emerging that can be expected to advance understanding of physiology and disease.

Aggregation of MBP in chronic demyelination

Objectives

Misfolding of key disease proteins to an insoluble state is associated with most neurodegenerative conditions, such as prion, Parkinson, and Alzheimer’s diseases. In this work, and by studying animal models of multiple sclerosis, we asked whether this is also the case for myelin basic protein (MBP) in the late and neurodegenerative phases of demyelinating diseases.

Methods

To this effect, we tested whether MBP, an essential myelin component, present prion-like properties in animal models of MS, as is the case for Cuprizone-induced chronic demyelination or chronic phases of Experimental Autoimmune Encephalomyelitis (EAE).

Results

We show here that while total levels of MBP were not reduced following extensive demyelination, part of these molecules accumulated thereafter as aggregates inside oligodendrocytes or around neuronal cells. In chronic EAE, MBP precipitated concomitantly with Tau, a marker of diverse neurodegenerative conditions, including MS. Most important, analysis of fractions from Triton X-100 floatation gradients suggest that the lipid composition of brain membranes in chronic EAE differs significantly from that of naïve mice, an effect which may relate to oxidative insults and subsequently prevent the appropriate insertion and compaction of new MBP in the myelin sheath, thereby causing its misfolding and aggregation.

Interpretation

Prion-like aggregation of MBP following chronic demyelination may result from an aberrant lipid composition accompanying this pathological status. Such aggregation of MBP may contribute to neuronal damage that occurs in the progressive phase of MS.

Determination of oxidized phosphatidylcholines by hydrophilic interaction liquid chromatography coupled to Fourier transform mass spectrometry

A novel liquid chromatography-mass spectrometry (LC-MS) approach for analysis of oxidized phosphatidylcholines by an Orbitrap Fourier Transform mass spectrometer in positive electrospray ionization (ESI) coupled to hydrophilic interaction liquid chromatography (HILIC) was developed. This method depends on three selectivity criteria for separation and identification: retention time, exact mass at a resolution of 100,000 and collision induced dissociation (CID) fragment spectra in a linear ion trap. The process of chromatography development showed the best separation properties with a silica-based Kinetex column. This type of chromatography was able to separate all major lipid classes expected in mammalian samples, yielding increased sensitivity of oxidized phosphatidylcholines over reversed phase chromatography. Identification of molecular species was achieved by exact mass on intact molecular ions and CID tandem mass spectra containing characteristic fragments. Due to a lack of commercially available standards, method development was performed with copper induced oxidation products of palmitoyl-arachidonoyl-phosphatidylcholine, which resulted in a plethora of lipid species oxidized at the arachidonoyl moiety. Validation of the method was done with copper oxidized human low-density lipoprotein (LDL) prepared by ultracentrifugation. In these LDL samples we could identify 46 oxidized molecular phosphatidylcholine species out of 99 possible candidates.

Increase in oxidative stress as measured by cerebrospinal fluid lipid peroxidation during treatment for childhood acute lymphoblastic leukemia

Five-year survival from childhood acute lymphoblastic leukemia (ALL) approaches 90%, but 40% of survivors experience central nervous system (CNS) treatment-related cognitive problems. Despite considerable evidence for cognitive problems, less is known about mechanisms of neurological injury. Our purpose was to investigate oxidative stress, measured by lipid peroxidation, as a mechanism of CNS treatment-related neurological injury. The sample included 55 children (mean age at diagnosis=6.84 y, SD=3.40) who received intrathecal and intravenous chemotherapy for CNS-directed treatment according to Children's Oncology Group protocols. Glycerophospholipids were extracted from cerebrospinal fluid samples obtained at diagnosis and during intrathecal chemotherapy administration. Unoxidized and oxidized phosphatidylcholine (PC) and phosphatidylinositol (PI) were measured by normal phase high-performance liquid chromatography with diode array detection, and analyzed with a general linear model for repeated measures analysis of variance. Compared with the diagnostic cerebrospinal fluid sample, unoxidized and oxidized PC and PI increased significantly across treatment phases. Amount of intravenous methotrexate received was significantly correlated with oxidized PI, and age at time of ALL diagnosis was significantly associated with oxidized PC. These findings support our hypothesis that oxidative stress is a mechanism of neurological injury associated with CNS-directed treatment for ALL.

Targeting apoptosis in autoimmune hepatitis

Apoptosis is the predominant mechanism of liver cell death in autoimmune hepatitis, and interventions that can modulate this activity are emerging. The aim of this review was to describe the apoptotic mechanisms, possible aberrations, and opportunities for intervention in autoimmune hepatitis. Studies cited in PubMed from 1972 to 2014 for autoimmune hepatitis, apoptosis in liver disease, apoptosis mechanisms, and apoptosis treatment were examined. Apoptosis is overactive in autoimmune hepatitis, and the principal pathway of cell death is receptor mediated. Surface death receptors are activated by extrinsic factors including liver-infiltrating cytotoxic T cells and the cytokine milieu. The executioner caspases 3 and 7 cleave nuclear deoxyribonucleic acid, and the release of apoptotic bodies can stimulate inflammatory, immune, and fibrotic responses. Changes in mitochondrial membrane permeability can be initiated by caspase 8, and an intrinsic pathway of apoptosis can complement the extrinsic pathway. Defects in the apoptosis of activated effector cells can prolong their survival and sustain the immune response. Caspase inhibitors have been used in diverse experimental and human diseases to retard apoptosis. Oligonucleotides that inhibit the signaling of toll-like receptors can limit the presentation of auto-antigens, and inhibitors of apoptosis that extend the survival of effector cells can be blocked by antisense oligonucleotides. Mechanisms that enhance the clearance of apoptotic bodies and affect key signaling pathways are also feasible. Interventions that influence the survival of liver and effector cells by altering their apoptosis are candidates for study in autoimmune hepatitis.

Lipid hydroperoxide-derived adduction to amino-phospholipid in biomembrane

Phospholipids such as phosphatidylethanolamine and phosphatidylcholine play crucial roles in the biological system to maintain the cellular environmental condition. Despite that, oxidative stress targets these phospholipids containing polyunsaturated fatty acids and accompanies the oxidized phospholipids. Recent studies have been suggested that oxidized phospholipids have the relationship with inflammation and might induce the atherosclerosis formation by uptake of oxidized LDL through scavenger receptor as ligands. Red blood cells, which have been studied the bilayer model, are also modified by oxidative stress because hemoglobin can mediate and produce the reactive oxygen species, which leads to lipid peroxidation of biomembrane. In these oxidation processes of biomolecules, hexanoylation against phosphatidylethanolamine and phosphatidylserine, which has the primary amine and is the target of this modification, generates the oxidized membrane such as erythrocyte ghosts. This unique structure of phosphatidylethanolamine and phosphatidylserine is possibly the useful biomarker to evaluate the oxidation of biomembrane in vivo using liquid chromatography tandem mass spectrometry and monoclonal antibody.

Structural motifs in primary oxidation products of palmitoyl-arachidonoyl-phosphatidylcholines by LC-MS/MS

Oxidative modifications to phospholipids (OxPL) play a major role in modulating signaling events in inflammation and infection, and complete understanding on the induced biological effects can only be understood based on knowledge of the oxidative motifs present. Specific neutral losses observed in tandem mass spectrometry data (LC-MS/MS) of primary peroxidation products in oxidized palmitoyl-arachidonoyl-phosphatidylcholines (OxPAPC) provide information on the prevailing structural motifs regarding the oxidized acyl carbon chain, the nature of oxidized group and the site of carbon oxidation. The higher hydrophobicity of hydroperoxides compared to di-hydroxy derivatives under reverse-phase conditions together with specific fragmentation patterns enabled the identification of 12 structurally different OxPAPC structural (di-hydroxy and hydroperoxide derivatives) and positional isomers as well as the presence of poly-hydroxy together with isoprostanes derivatives. The fragmentation patterns described in quadrupole time-of-flight and linear ion trap instruments complement the m/z value and retention time parameters in the identification of oxidative composition in OxPAPC products becoming a valuable tool for the exploratory screening of oxidized phosphatidylcholines in OxPAPC extracts, distinction of native and modified PC isobaric structures in complex samples contributing to the increased understanding of redox lipidomics in inflammation and infection.

Oxidative stress in the pathology and treatment of systemic lupus erythematosus

Oxidative stress is increased in systemic lupus erythematosus (SLE), and it contributes to immune system dysregulation, abnormal activation and processing of cell-death signals, autoantibody production and fatal comorbidities. Mitochondrial dysfunction in T cells promotes the release of highly diffusible inflammatory lipid hydroperoxides, which spread oxidative stress to other intracellular organelles and through the bloodstream. Oxidative modification of self antigens triggers autoimmunity, and the degree of such modification of serum proteins shows striking correlation with disease activity and organ damage in SLE. In T cells from patients with SLE and animal models of the disease, glutathione, the main intracellular antioxidant, is depleted and serine/threonine-protein kinase mTOR undergoes redox-dependent activation. In turn, reversal of glutathione depletion by application of its amino acid precursor, N-acetylcysteine, improves disease activity in lupus-prone mice; pilot studies in patients with SLE have yielded positive results that warrant further research. Blocking mTOR activation in T cells could conceivably provide a well-tolerated and inexpensive alternative approach to B-cell blockade and traditional immunosuppressive treatments. Nevertheless, compartmentalized oxidative stress in self-reactive T cells, B cells and phagocytic cells might serve to limit autoimmunity and its inhibition could be detrimental. Antioxidant therapy might also be useful in ameliorating damage caused by other treatments. This Review thus seeks to critically evaluate the complexity of oxidative stress and its relevance to the pathogenesis and treatment of SLE.

Inhibition of monocyte chemotaxis by VB-201, a small molecule lecinoxoid, hinders atherosclerosis development in ApoE⁻/⁻ mice

OBJECTIVE

Monocytes are motile cells which sense inflammatory stimuli and subsequently migrate to sites of inflammation. Key players in host defense, monocytes have nevertheless been implicated as requisite mediators of several chronic inflammatory diseases. Inhibition of monocyte chemotaxis is therefore an attractive anti-inflammatory strategy. Oxidized phospholipids (OxPL) are native regulators of inflammation, yet their direct effect on monocyte chemotaxis is poorly defined. In this study, we investigated the direct effect of natural and synthetic phospholipids on monocyte chemotaxis.

METHODS

Exploring various phospholipids using in vitro chemotaxis assays, we found that the natural phospholipid 1-palmitoyl-2-glutaryl phosphatidylcholine (PGPC) can decrease monocyte chemotaxis by 50%, while other tested OxPL had no effect. We generated a library of synthetic OxPL designated lecinoxoids, which was screened for anti-inflammatory properties.

RESULTS AND CONCLUSIONS

VB-201, a small-molecule lecinoxoid, exhibited up to 90% inhibition of monocyte chemotaxis in vitro. Molecular analysis revealed that the effect of VB-201 was not restricted to a specific chemotactic ligand or receptor, and resulted from inhibition of signaling pathways required for monocyte chemotaxis. Interestingly, VB-201 did not inhibit monocyte adhesion or phagocytosis and had no effect on chemotaxis of CD4(+) T-cells or neutrophils. In vivo, oral treatment with VB-201 reduced monocyte migration in a peritonitis model and inhibited atheroma development in ApoE(-/-) mice, without affecting cholesterol or triglyceride levels. Our findings highlight a novel role played by native and synthetic phospholipids in regulation of monocyte chemotaxis. The data strengthen the involvement of phospholipids as key signaling molecules in inflammatory settings and demonstrate their potential therapeutic applicability.

Low plasma antibodies specific for phosphatidylethanol in alcohol abusers and patients with alcoholic pancreatitis

Phosphatidylethanol (PEth) is a group of alcohol-modified phospholipids present in cell membranes after heavy drinking. Our aim was to demonstrate the presence of human plasma antibodies binding to PEth and to address their specificity and value in detecting subjects engaged in heavy alcohol consumption. Antibodies to PEth were analyzed in plasma from heavy drinkers (n=20), patients with alcoholic pancreatitis (n=58) and control subjects (n=24), using chemiluminescent immunoassay. Heavy drinkers and patients with alcoholic pancreatitis demonstrated significantly lower levels of plasma IgG, IgA and IgM titers to PEth compared with controls (P<0.001). The specificity of the antibodies to PEth was demonstrated with competitive liquid phase immunoassays and flow cytometry. The plasma IgG, but not IgA or IgM, titers to PEth in heavy drinkers correlated with the whole blood PEth concentration determined by liquid chromatography-mass spectrometry (r=0.655, P=0.002). Compared with traditional markers for alcohol abuse (aspartate aminotransferase, gamma-glutamyl transpeptidase and mean corpuscular volume), receiver operating characteristic curve analysis showed that a low plasma IgA to PEth had the highest area under the curve (AUC 0.940, P<0.001). In conclusion, plasma IgG, IgA and IgM antibodies binding specifically to PEth were found in subjects of all study groups. Subjects with heavy alcohol consumption showed markedly lower plasma immunoglobulin levels to PEth, potentially making them useful as a biomarker to distinguish heavy from moderate alcohol use.

Ramipril attenuates lipid peroxidation and cardiac fibrosis in an experimental model of rheumatoid arthritis

INTRODUCTION

Recent studies revealed that co-morbidity and mortality due to cardiovascular disease are increased in patients with rheumatoid arthritis (RA) but little is known about factors involved in these manifestations. This study aimed at characterizing the impact of arthritis on oxidative stress status and tissue fibrosis in the heart of rats with adjuvant-induced arthritis (AIA).

METHODS

AIA was induced with complete Freund's adjuvant in female Lewis rats. Animals were treated by oral administration of vehicle or angiotensin-converting enzyme inhibitor ramipril (10 mg/kg/day) for 28 days, beginning 1 day after arthritis induction. Isolated adult cardiomyocytes were exposed to 10 μM 4-hydroxynonenal (HNE) for 24 hours in the presence or absence of 10 μM ramipril.

RESULTS

Compared to controls, AIA rats showed significant 55 and 30% increase of 4-HNE/protein adducts in serum and left ventricular (LV) tissues, respectively. Cardiac mitochondrial NADP+-isocitrate dehydrogenase (mNADP-ICDH) activity decreased by 25% in AIA rats without any changes in its protein and mRNA expression. The loss of mNADP-ICDH activity was correlated with enhanced accumulation of HNE/mNADP-ICDH adducts as well as with decrease of glutathione and NADPH. Angiotensin II type 1 receptor (AT1R) expression and tissue fibrosis were induced in LV tissues from AIA rats. In isolated cardiomyocytes, HNE significantly decreased mNADP-ICDH activity and enhanced type I collagen and connective tissue growth factor expression. The oral administration of ramipril significantly reduced HNE and AT1R levels and restored mNADP-ICDH activity and redox status in LV tissues of AIA rats. The protective effects of this drug were also evident from the decrease in arthritis scoring and inflammatory markers.

CONCLUSION

Collectively, our findings disclosed that AIA induced oxidative stress and fibrosis in the heart. The fact that ramipril attenuates inflammation, oxidative stress and tissue fibrosis may provide a novel strategy to prevent heart diseases in RA.

Oxidative stress and fatigue in systemic lupus erythematosus

Objective: The objective of this study is to investigate the relationship of oxidative stress to fatigue in systemic lupus erythematosus (SLE). Methods: Patients with a confirmed diagnosis of SLE by ACR criteria and healthy controls completed validated questionnaires to assess depression and fatigue. Fatigue was measured with the Fatigue Severity Scale (FSS) and the Profile of Fatigue (Prof-F). Visual analogue scales (VAS) were also used to assess fatigue and pain. Depression was measured with the Center for Epidemiologic Studies Depression Scale (CES-D). Plasma F2-isoprostane was measured with gas chromatography/mass spectroscopy to assess oxidative stress. Evaluation included medical record review, physical exam and calculation of body mass index (BMI), disease activity (SLEDAI) and damage (SLICC) in the SLE patients. Results: Seventy-one SLE patients with low disease activity (mean SLEDAI = 1.62 standard error (SE) 0.37, range 0–8) were compared to 51 controls. Fatigue-limiting physical activity (defined as FSS ≥ 4) was present in 56% of patients and 12% of controls. F2-isoprostane was higher in SLE patients with fatigue compared to not-fatigued SLE subjects ( p = .0076) who were otherwise similar in ethnicity, disease activity and cardiovascular risk factors. Plasma F2-isoprostane was strongly correlated with FSS and Profile of Somatic Fatigue (Prof-S) ( p < .0001), VAS fatigue ( p = .005), CES-D ( p = .008) and with BMI ( p = .0001.) In a multivariate model, F2-isoprostane was a significant predictor of FSS after adjustment for age, BMI, pain and depression ( p = .0002). Conclusion: Fatigue in SLE patients with low disease activity is associated with increased F2-isoprostane. F2-isoprostane could provide a useful biomarker to explore mitochondrial function and the regulation of oxidative pathways in patients with SLE in whom fatigue is a debilitating symptom.

Physiological effects of oxidized phospholipids and their cellular signaling mechanisms in inflammation

Oxidized phospholipids, such as the products of the oxidation of 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine by nonenzymatic radical attack, are known to be formed in a number of inflammatory diseases. Interest in the bioactivity and signaling functions of these compounds has increased enormously, with many studies using cultured immortalized and primary cells, tissues, and animals to understand their roles in disease pathology. Initially, oxidized phospholipids were viewed largely as culprits, in line with observations that they have proinflammatory effects, enhancing inflammatory cytokine production, cell adhesion and migration, proliferation, apoptosis, and necrosis, especially in vascular endothelial cells, macrophages, and smooth muscle cells. However, evidence has emerged that these compounds also have protective effects in some situations and cell types; a notable example is their ability to interfere with signaling by certain Toll-like receptors (TLRs) induced by microbial products that normally leads to inflammation. They also have protective effects via the stimulation of small GTPases and induce up-regulation of antioxidant enzymes and cytoskeletal rearrangements that improve endothelial barrier function. Oxidized phospholipids interact with several cellular receptors, including scavenger receptors, platelet-activating factor receptors, peroxisome proliferator-activated receptors, and TLRs. The various and sometimes contradictory effects that have been observed for oxidized phospholipids depend on their concentration, their specific structure, and the cell type investigated. Nevertheless, the underlying molecular mechanisms by which oxidized phospholipids exert their effects in various pathologies are similar. Although our understanding of the actions and mechanisms of these mediators has advanced substantially, many questions do remain about their precise interactions with components of cell signaling pathways.

Inflammation-related gene expression by lipid oxidation-derived products in the progression of atherosclerosis

Vascular areas of atherosclerotic development persist in a state of inflammation, and any further inflammatory stimulus in the subintimal area elicits a proatherogenic response; this alters the behavior of the artery wall cells and recruits further inflammatory cells. In association with the inflammatory response, oxidative events are also involved in the development of atherosclerotic plaques. It is now unanimously recognized that lipid oxidation-derived products are key players in the initiation and progression of atherosclerotic lesions. Oxidized lipids, derived from oxidatively modified low-density lipoproteins (LDLs), which accumulate in the intima, strongly modulate inflammation-related gene expression, through involvement of various signaling pathways. In addition, considerable evidence supports a proatherogenic role of a large group of potent bioactive lipids called eicosanoids, which derive from oxidation of arachidonic acid, a component of membrane phospholipids. Of note, LDL lipid oxidation products might regulate eicosanoid production, modulating the enzymatic degradation of arachidonic acid by cyclooxygenases and lipoxygenases; these enzymes might also directly contribute to LDL oxidation. This review provides a comprehensive overview of current knowledge on signal transduction pathways and inflammatory gene expression, modulated by lipid oxidation-derived products, in the progression of atherosclerosis.

Enhancement by LDL of transfer of L-4F and oxidized lipids to HDL in C57BL/6J mice and human plasma

The apoA-I mimetic peptide L-4F [(Ac-D-W-F-K-A-F-Y-D-K-V-A-E-K-F-K-E-A-F-NH2) synthesized from all L-amino acids] has shown potential for the treatment of a variety of diseases. Here, we demonstrate that LDL promotes association between L-4F and HDL. A 2- to 3-fold greater association of L-4F with human HDL was observed in the presence of human LDL as compared with HDL by itself. This association further increased when LDL was supplemented with the oxidized lipid 15S-hydroxy-5Z, 8Z, 11Z, 13E-eicosatetraenoic acid (15HETE). Additionally, L-4F significantly (P = 0.02) promoted the transfer of 15HETE from LDL to HDL. The transfer of L-4F from LDL to HDL was demonstrated both in vitro and in C57BL/6J mice. L-4F, injected into C57BL/6J mice, associated rapidly with HDL and was then cleared quickly from the circulation. Similarly, L-4F loaded onto human HDL and injected into C57BL/6J mice was cleared quickly with T(1/2) = 23.6 min. This was accompanied by a decline in human apoA-I with little or no effect on the mouse apoA-I. Based on these results, we propose that i) LDL promotes the association of L-4F with HDL and ii) in the presence of L-4F, oxidized lipids in LDL are rapidly transferred to HDL allowing these oxidized lipids to be acted upon by HDL-associated enzymes and/or cleared from the circulation.

Lipidomics era: accomplishments and challenges

Lipid mediators participate in signal transduction pathways, proliferation, apoptosis, and membrane trafficking in the cell. Lipids are highly complex and diverse owing to the various combinations of polar headgroups, fatty acyl chains, and backbone structures. This structural diversity continues to pose a challenge for lipid analysis. Here we review the current state of the art in lipidomics research and discuss the challenges facing this field. The latest technological developments in mass spectrometry, the role of bioinformatics, and the applications of lipidomics in lipid metabolism and cellular physiology and pathology are also discussed.

Autoimmune hepatitis induced by syngeneic liver cytosolic proteins biotransformed by alcohol metabolites

BACKGROUND AND AIMS

Aldehydes that are produced following the breakdown of ethanol (acetaldehyde) and lipid peroxidation of membranes (malondialdehyde) have been shown to bind (adduct) proteins. Additionally, these two aldehydes can combine (MAA) on nonsyngeneic and syngeneic proteins to initiate numerous immune responses to the unmodified part of the protein in the absence of an adjuvant. Therefore, these studies provide a potential mechanism for the development of antigen-specific immune responses resulting in liver damage should syngeneic liver proteins be adducted with MAA.

METHODS

This study sought to test whether MAA-modified syngeneic liver cytosolic proteins administered daily in the absence of adjuvant into C57BL/6 mice abrogates tolerance to initiate a MAA-induced autoimmune-like hepatitis.

RESULTS

In mice immunized with MAA-modified cytosols, there was an increase in liver damage as assessed by aspartate aminotransferase/alanine aminotransferase levels that correlated with liver pathology scores and the presence of the pro-fibrotic factors, smooth muscle actin, TGF-β, and collagen. IgG antibodies and T-cell proliferative responses specific for cytosolic proteins were also detected. Pro-inflammatory cytokines were produced in the livers of animals exposed to MAA-modified cytosols. Finally, transfer of immunized T cells to naïve animals caused biochemical and histological evidence of liver damage.

CONCLUSIONS

These data demonstrate that a disease with an autoimmune-like pathophysiology can be generated in this animal model using soluble MAA-modified syngeneic liver cytosols as the immunogen. These studies provide insight into potential mechanism(s) that the metabolites of alcohol may play in contributing to the onset of an autoimmune-like disease in patients with alcoholic liver disease.

The vascular contribution to Alzheimer's disease

AD (Alzheimer's disease) is a progressive neurodegenerative disease of unknown origin. Despite questions as to the underlying cause(s) of this disease, shared risk factors for both AD and atherosclerotic cardiovascular disease indicate that vascular mechanisms may critically contribute to the development and progression of both AD and atherosclerosis. An increased risk of developing AD is linked to the presence of the apoE4 (apolipoprotein E4) allele, which is also strongly associated with increased risk of developing atherosclerotic cardiovascular disease. Recent studies also indicate that cardiovascular risk factors, including elevated blood cholesterol and triacylglycerol (triglyceride), increase the likelihood of AD and vascular dementia. Lipids and lipoproteins in the circulation interact intimately with the cerebrovasculature, and may have important effects on its constituent brain microvascular endothelial cells and the adjoining astrocytes, which are components of the neurovascular unit. The present review will examine the potential mechanisms for understanding the contributions of vascular factors, including lipids, lipoproteins and cerebrovascular Abeta (amyloid beta), to AD, and suggest therapeutic strategies for the attenuation of this devastating disease process. Specifically, we will focus on the actions of apoE, TGRLs (triacylglycerol-rich lipoproteins) and TGRL lipolysis products on injury of the neurovascular unit and increases in blood-brain barrier permeability.