A novel receptor for platelet-activating factor and lysophosphatidylcholine in Trypanosoma cruzi.

The lipid mediators, platelet-activating factor (PAF) and lysophosphatidylcholine (LPC), play relevant pathophysiological roles in Trypanosoma cruzi infection. Several species of LPC, including C18:1 LPC, which mimics the effects of PAF, are synthesized by T. cruzi. The present study identified a receptor in T. cruzi, which was predicted to bind to PAF, and found it to be homologous to members of the progestin and adiponectin family of receptors (PAQRs). We constructed a three-dimensional model of the T. cruzi PAQR (TcPAQR) and performed molecular docking to predict the interactions of the TcPAQR model with C16:0 PAF and C18:1 LPC. We knocked out T. cruzi PAQR (TcPAQR) gene and confirmed the identity of the expressed protein through immunoblotting and immunofluorescence assays using an anti-human PAQR antibody. Wild-type and knockout (KO) parasites were also used to investigate the in vitro cell differentiation and interactions with peritoneal mouse macrophages; TcPAQR KO parasites were unable to react to C16:0 PAF or C18:1 LPC. Our data are highly suggestive that PAF and LPC act through TcPAQR in T. cruzi, triggering its cellular differentiation and ability to infect macrophages.

Forty Years Since the Structural Elucidation of Platelet-Activating Factor (PAF): Historical, Current, and Future Research Perspectives.

In the late 1960s, Barbaro and Zvaifler described a substance that caused antigen induced histamine release from rabbit platelets producing antibodies in passive cutaneous anaphylaxis. Henson described a 'soluble factor' released from leukocytes that induced vasoactive amine release in platelets. Later observations by Siraganuan and Osler observed the existence of a diluted substance that had the capacity to cause platelet activation. In 1972, the term platelet-activating factor (PAF) was coined by Benveniste, Henson, and Cochrane. The structure of PAF was later elucidated by Demopoulos, Pinckard, and Hanahan in 1979. These studies introduced the research world to PAF, which is now recognised as a potent phospholipid mediator. Since its introduction to the literature, research on PAF has grown due to interest in its vital cell signalling functions and more sinisterly its role as a pro-inflammatory molecule in several chronic diseases including cardiovascular disease and cancer. As it is forty years since the structural elucidation of PAF, the aim of this review is to provide a historical account of the discovery of PAF and to provide a general overview of current and future perspectives on PAF research in physiology and pathophysiology.

Enzymatic methods for choline-containing water soluble phospholipids based on fluorescence of choline oxidase: Application to lyso-PAF.

In this paper we present methods to determine water soluble phospholipids containing choline (wCh-PL). The analytes were hydrolyzed by the enzyme phospholipase D and the choline formed was oxidized by the enzyme Choline Oxidase (ChOx); the fluorescence changes of the ChOx are followed during the enzymatic reaction, avoiding the necessity of an indicating step. Both reactions (hydrolysis and oxidation) can be combined in two different ways: 1) a two-step process (TSP) in which the hydrolysis reaction takes place during an incubation time and then the oxidation reaction is carried out, the analytical signal being provided by the intrinsic fluorescence of ChOx due to tryptophan; 2) a one-step process (OSP) in which both enzymatic reactions are carried out simultaneously in the same test; in this case the analytical signal is provided by the ChOx extrinsic fluorescence due to a fluorescent probe (Ru (II) chelate) linked to the enzyme (ChOx-RuC). The analytical capabilities of these methods were studied using 1,2-dioctanoyl-sn-glycero-3-phosphocholine (C8PC), a water soluble short alkyl chain Ch-PL as a substrate, and 1-O-hexadecyl-sn-glyceryl-3-phosphorylcholine (lyso-PAF). The analytical features of merit for both analytes using both methods were obtained. The TSP gave a 10-fold sensitivity and lower quantification limit (1.0*10-5 M for lyso-PAF), but OSP reduced the determination time and permitted to use the same enzyme aliquot for several measurements. Both methods gave similar precision (RSD 7%, n = 5). The TSP was applied to the determination of C8PC and lyso-PAF in spiked synthetic serum matrix using the standard addition method. The application of this methodology to PLD activity determination is also discussed.

Platelet-Activating Factor Quantification Using Reversed Phase Liquid Chromatography and Selected Reaction Monitoring in Negative Ion Mode.

Platelet-activating factor (PAF) is a potent biologically active phospholipid that mediates human physiological and pathophysiologic responses. PAF levels increase transiently and are typically assessed by techniques with limitations related to expense, sensitivity, pre-analysis derivatization and interference with isobaric molecules. This study elucidates a facile, accurate liquid chromatography-mass spectrometry analytical method for PAF. In negative ion mode using electrospray ionization, collisionally-activated dissociation analysis showed a unique product ion for acetate adducts of PAF molecular species representing the loss of methyl acetate from the polar head group and loss of a part of the acetate group from the sn-2 position. This product ion was exploited for selected reaction monitoring of PAF molecular species following separation by reversed-phase liquid chromatography. Standard calibration responses were determined, and this method was able to detect as low as 100 fmol of PAF. Finally, PAF molecular species were quantified in human neutrophils and monocytes.

Comparative Experimental and Computational Study of Monoalkyl Chain Phosphatidylcholine-Containing Thermoresponsive Liposomes.

Liposomes containing lysophospholipids are intensively studied as drug delivery systems that are stable at normal body temperature but exhibit fast release of their drug load at slightly elevated temperatures. In this study, the stability and release properties of dipalmitoylglycerophosphocholine (DPPC)-based liposomes incorporating the commonly used lysophosphatidylocholine (lyso-PC), and a series of monoalkyl chain ether-linked phosphatidylcholine, i.e., the biologically relevant monoalkyl chain platelet activating factor (PAF) and its derivatives lyso-PAF and methyl-PAF, were investigated. To this end a series of PEGylated small unilamellar liposomes with DPPC:monoalkyl lipid compositions of 5% and 10% molar ratio were prepared and compared with regard to stability (37 °C) and release properties at elevated temperatures (38-43 °C). All systems were characterized with respect to size distribution, ζ-potential, and phase transition characteristics. The presence of ether-lipids endows liposomes with superior (∼10% increase) release properties at 5% incorporation compared to lyso-PC, while at 10% molar ratio the formulations do not differ significantly, the release being close to 90%. The findings are supported by atomistic molecular dynamics simulations that suggest a correlation between the enhanced permeability and increased penetration of water molecules within the bilayers with density fluctuations resulting from the increased area-per-lipid and the disorder of the lysolipids alkyl chains.

Bacterial exploitation of phosphorylcholine mimicry suppresses inflammation to promote airway infection.

Regulation of neutrophil activity is critical for immune evasion among extracellular pathogens, yet the mechanisms by which many bacteria disrupt phagocyte function remain unclear. Here, we have shown that the respiratory pathogen Streptococcus pneumoniae disables neutrophils by exploiting molecular mimicry to degrade platelet-activating factor (PAF), a host-derived inflammatory phospholipid. Using mass spectrometry and murine upper airway infection models, we demonstrated that phosphorylcholine (ChoP) moieties that are shared by PAF and the bacterial cell wall allow S. pneumoniae to leverage a ChoP-remodeling enzyme (Pce) to remove PAF from the airway. S. pneumoniae-mediated PAF deprivation impaired viability, activation, and bactericidal capacity among responding neutrophils. In the absence of Pce, neutrophils rapidly cleared S. pneumoniae from the airway and impeded invasive disease and transmission between mice. Abrogation of PAF signaling rendered Pce dispensable for S. pneumoniae persistence, reinforcing that this enzyme deprives neutrophils of essential PAF-mediated stimulation. Accordingly, exogenous activation of neutrophils overwhelmed Pce-mediated phagocyte disruption. Haemophilus influenzae also uses an enzyme, GlpQ, to hydrolyze ChoP and subvert PAF function, suggesting that mimicry-driven immune evasion is a common paradigm among respiratory pathogens. These results identify a mechanism by which shared molecular structures enable microbial enzymes to subvert host lipid signaling, suppress inflammation, and ensure bacterial persistence at the mucosa.

The role of platelet-activating factor in mesangial pathophysiology.

Platelet-activating factor (PAF) is a powerful proinflammatory mediator that displays an exceedingly diverse spectrum of biological effects. Importantly, PAF is shown to participate in a broad range of pathologic conditions. This review focuses on the role that PAF plays specifically in the pathophysiology of the kidney, the organ that is both a source and a target of PAF. Renal mesangial cells are responsible for glomerular PAF generation and, ultimately, are the victims of its excessive production. Mesangial pathology is widely acknowledged to reflect glomerular damage, which culminates in glomerulosclerosis and proteinuria. Therefore, modulation of mesangial cell responses would offer a pathophysiology-based therapeutic approach to prevent glomerular injury. However, the currently available therapeutic modalities do not allow for targeted intervention into these processes. A more profound understanding of the mechanisms that govern PAF metabolism and signaling in mesangial cells is important, because it could facilitate the quest for improved therapies for renal patients on the basis of PAF as a drug target.

Snake venom serine proteinases specificity mapping by proteomic identification of cleavage sites.

Many snake venom toxins are serine proteases but their specific in vivo targets are mostly unknown. Various act on components of the coagulation cascade, and fibrinolytic and kallikrein-kinin systems to trigger various pathological effects observed in the envenomation. Despite showing high similarity in terms of primary structure snake venom serine proteinases (SVSPs) show exquisite specificity towards macromolecular substrates. Therefore, the characterization of their peptide bond specificity is important for understanding the active site preference associated with effective proteolysis as well as for the design of peptide substrates and inhibitors. Bothrops jararaca contains various SVSPs among which Bothrops protease A is a specific fibrinogenolytic agent and PA-BJ is a platelet-activating enzyme. In this study we used proteome derived peptide libraries in the Proteomic Identification of protease Cleavage Sites (PICS) approach to explore the peptide bond specificity of Bothrops protease A and PA-BJ in order to determine their individual peptide cleavage sequences. A total of 371 cleavage sites (208 for Bothrops protease A and 163 for PA-BJ) were detected and both proteinases displayed a clear preference for arginine at the P1 position. Moreover, the analysis of the specificity profiles of Bothrops protease A and PA-BJ revealed subtle differences in the preferences along P6-P6', despite a common yet unusual preference for Pro at P2. Taken together, these results map the subsite specificity of both SVSPs and shed light in the functional differences between these proteinases. BIOLOGICAL SIGNIFICANCE: Proteolysis is key to various pathological effects observed upon envenomation by viperid snakes. The use of the Proteomic Identification of protease Cleavage Sites (PICS) approach for the easy mapping of proteinase subsite preferences at both the prime- and non-prime sides concurrently gives rise to a fresh understanding of the interaction of the snake venom serine proteinases with peptide and macromolecular substrates and indicates that their hydrolytic activity is influenced by the amino acid sequences adjacent to the scissile bond.

Structural and functional analysis of a platelet-activating lysophosphatidylcholine of Trypanosoma cruzi.

BACKGROUND: Trypanosoma cruzi is the causative agent of the life-threatening Chagas disease, in which increased platelet aggregation related to myocarditis is observed. Platelet-activating factor (PAF) is a potent intercellular lipid mediator and second messenger that exerts its activity through a PAF-specific receptor (PAFR). Previous data from our group suggested that T. cruzi synthesizes a phospholipid with PAF-like activity. The structure of T. cruzi PAF-like molecule, however, remains elusive. METHODOLOGY/PRINCIPAL FINDINGS: Here, we have purified and structurally characterized the putative T. cruzi PAF-like molecule by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Our ESI-MS/MS data demonstrated that the T. cruzi PAF-like molecule is actually a lysophosphatidylcholine (LPC), namely sn-1 C18:1(delta 9)-LPC. Similar to PAF, the platelet-aggregating activity of C18:1-LPC was abrogated by the PAFR antagonist, WEB 2086. Other major LPC species, i.e., C16:0-, C18:0-, and C18:2-LPC, were also characterized in all T. cruzi stages. These LPC species, however, failed to induce platelet aggregation. Quantification of T. cruzi LPC species by ESI-MS revealed that intracellular amastigote and trypomastigote forms have much higher levels of C18:1-LPC than epimastigote and metacyclic trypomastigote forms. C18:1-LPC was also found to be secreted by the parasite in extracellular vesicles (EV) and an EV-free fraction. A three-dimensional model of PAFR was constructed and a molecular docking study was performed to predict the interactions between the PAFR model and PAF, and each LPC species. Molecular docking data suggested that, contrary to other LPC species analyzed, C18:1-LPC is predicted to interact with the PAFR model in a fashion similar to PAF. CONCLUSIONS/SIGNIFICANCE: Taken together, our data indicate that T. cruzi synthesizes a bioactive C18:1-LPC, which aggregates platelets via PAFR. We propose that C18:1-LPC might be an important lipid mediator in the progression of Chagas disease and its biosynthesis could eventually be exploited as a potential target for new therapeutic interventions.

Establishment of the method for screening the potential targets and effective components of huatuo reconstruction pill.

Huatuo reconstruction pill (HTRP) is a traditional Chinese medicine prescription that mainly treats for hemiplegia and postoperation of brain stroke. Existing pharmacological studies have previously shown that HTRP could inhibit in vitro thrombosis, delay platelet adhesion, dilate blood vessels, and improve the microcirculation disturbances. In this paper, we chiefly concerned about the potential targets of HTRP and tried to figure out the active components of it. Computer-aided drug design method was emploied to search for the active components and explain the mechanism between the targets and the small molecules at molecular lever. The potential targets of this compound pharmaceutics were searched through relevant pharmacological studies and three pharmacophore models which involved the platelet activating factor (PAF) receptor, the angiotensin converting enzyme (ACE) and the 5-hydroxytryptamine receptor (5-HT2A) were constructed by Discotech method of Sybyl. Thus, the candidate compounds which agreed with the pharmacophore models were obtained by the virtual screening to the known ingredients of HTRP. Based on that, sequence and structure prediction of the unknown targets were realized by homology modeling which were used for molecular docking with those candidate compounds. Results showed that three compounds, which may prove to be valid to these targets, got higher scores than the existing corresponding inhibitors after molecular docking, including ferulic acid, onjixanthone I and albiflorin. And the three molecules may refer to the singificant substances to the total compounds of HTRP which were effective to the disease.

Steroidal saponins from Tribulus terrestris.

Sixteen steroidal saponins, including seven previously unreported compounds, were isolated from Tribulus terrestris. The structures of the saponins were established using 1D and 2D NMR spectroscopy, mass spectrometry, and chemical methods. They were identified as: 26-O-ß-d-glucopyranosyl-(25R)-furost-4-en-2α,3ß,22α,26-tetrol-12-one (terrestrinin C), 26-O-ß-d-glucopyranosyl-(25R)-furost-4-en-22α,26-diol-3,12-dione (terrestrinin D), 26-O-ß-d-glucopyranosyl-(25S)-furost-4-en-22α,26-diol-3,6,12-trione (terrestrinin E), 26-O-ß-d-glucopyranosyl-(25R)-5α-furostan-3ß,22α,26-triol-12-one (terrestrinin F), 26-O-ß-d-glucopyranosyl-(25R)-furost-4-en-12ß,22α,26-triol-3-one (terrestrinin G), 26-O-ß-d-glucopyranosyl-(1→6)-ß-d-glucopyranosyl-(25R)-furost-4-en-22α,26-diol-3,12-dione (terrestrinin H), and 24-O-ß-d-glucopyranosyl-(25S)-5α-spirostan-3ß,24ß-diol-12-one-3-O-ß-d-glucopyranosyl-(1→4)-ß-d-galactopyranoside (terrestrinin I). The isolated compounds were evaluated for their platelet aggregation activities. Three of the known saponins exhibited strong effects on the induction of platelet aggregation.

Influence of platelet-activating factor, lyso-platelet-activating factor and edelfosine on Langmuir monolayers imitating plasma membranes of cell lines differing in susceptibility to anti-cancer treatment: the effect of plasmalogen level.

Three structurally related but differing in biological activities single-chained ether phospholipids (PAF (platelet-activating factor) and lyso-PAF) and an anti-cancer drug (edelfosine (ED)) were investigated in Langmuir monolayers imitating natural membranes. The aim of the undertaken experiments was to study the influence of these lipids on monolayers mimicking plasma membranes of cell lines differing in susceptibility to the anti-cancer activity of ED, i.e. promyelocytic leukaemia cells (HL-60) and promyeloblastic leukaemia cells (K-562). As these cells differ essentially in the cholesterol/phospholipid ratio and plasmalogen concentration in the membrane, we have carried out systematic investigations in artificial systems of various compositions. The results for model leukaemia cell membrane were compared with data acquired for systems imitating normal leucocytes. Our results show that the level of plasmalogens significantly modulates the influence of the single-chained phospholipids on the investigated systems. The experiments confirmed also that the interactions of ether lipids with a model membrane of HL-60 cells (in biological tests sensitive to ED) have opposite character when compared with K-562, being resistant to ED. Moreover, the values of the parameters characterizing monolayers serving as membrane models (strength of interactions, monolayers fluidity and morphology) proved both sensitivity of these cells to ED and lack of their susceptibility towards PAF. Interestingly, it has been found that lyso-PAF, which is usually described as an inactive precursor of PAF, displays a stronger effect on HL-60 model membranes than ED.

Glycosidated phospholipids - a promising group of anti-tumour lipids.

Synthetic alkylphospholipids (APLs), exhibit similarity to the platelet-activating factor (PAF). These compounds have antiproliferative effects on tumour cells and can therefore be regarded as a new class of drugs. Unlike classic cytostatic agents, synthetic alkylphospholipids do not interfere with the DNA or the mitotic spindle apparatus. Instead, due to their aliphatic character, alkylphospholipids accumulate in cell membranes, where they have an impact on lipid metabolism and lipid-dependent signalling pathways which leads to inhibition of proliferation and induction of apoptosis in malignant cells. Normal cells remain unaffected by these compounds. Glycosidated phospholipids, are a novel class of alkylphospholipids, in which carbohydrates or carbohydrate-related molecules are introduced in the chemical lead of PAF. These hybrid alkylphospholipids also exhibit anti-proliferative capacity. Furthermore, members of this subfamily also modulate cell adhesion, differentiation, apoptosis and migration of tumour cells. Among the members of this group, Inositol-C2-platelet-activating factor (Ino-C2-PAF) is the most effective compound developed so far. Recently, we also showed that Ino-C2-PAF exhibited the strongest impact on the gene expression levels of immortalised keratinocytes in comparison to edelfosine and another glycosidated alkylphospholipid, Glucose-platelet-activating factor (Glc-PAF). Furthermore, Ino-C2-PAF reduced the expression of genes encoding proteins associated with inflammation and the innate and acquired immune responses.

Isolation, functional characterization and proteomic identification of CC2-PLA2 from Cerastes cerastes venom: a basic platelet-aggregation-inhibiting factor.

Three-step chromatography and proteomic analysis have been used to purify and characterize a new basic phospholipase A2 named CC2-PLA2 from the venom of Cerastes cerastes. This phospholipase A2 has been isolated to an extent of about 50-folds and its molecular weight was estimated at 13,534 Da. For CC2-PLA2 identification and LC-MALDI-MS/MS analysis, the protein was reduced, alkylated and double hydrolyzed by lysine-C endopeptidase and trypsin. Tryptic fragments of LC-MS/MS analyzed CC2-PLA2 showed sequence similarities with other snake venom PLA2. This presents only 51 % (61/120 amino acid residues) sequence homology with the first PLA2 (gi |129506|) previously purified from the same venom. The isolated CC2-PLA2 displayed anti-aggregative effect on platelets and induced an inflammatory response characterized by leukocytosis in the peripheral blood. This inflammatory response is accompanied by a release of inflammatory mediators such as IL-6, eosinophil peroxidase and complement system. Obtained results indicate that CC2-PLA2 induced a release of high level of pro-inflammatory (IL-6) cytokine and no effect on the level of anti-inflammatory cytokine (IL-10) in blood sera. Furthermore, eosinophil peroxidase activity and hemolytic complement effect increased in peripheral blood. Mononuclear and neutrophil cells were found predominant in the induced leucocytosis following CC2-PLA2 administration into animals.

Catalytic synthesis of enantiopure mixed diacylglycerols ­ synthesis of a major M. tuberculosis phospholipid and platelet activating factor.

An efficient catalytic one-pot synthesis of TBDMS-protected diacylglycerols has been developed, starting from enantiopure glycidol. Subsequent migration-free deprotection leads to stereo- and regiochemically pure diacylglycerols. This novel strategy has been applied to the synthesis of a major Mycobacterium tuberculosis phospholipid, its desmethyl analogue, and platelet activating factor.

Lancolides, antiplatelet aggregation nortriterpenoids with tricyclo[6.3.0.0(2,11)]undecane-bridged system from Schisandra lancifolia.

A new class of highly oxygenated Schisandra nortriterpenoids, lancolides A-D (1-4), from Schisandra lancifolia, represents the first example of natural products that possess a tricyclo[6.3.0.0(2,11)]undecane-bridged system. Their structures were elucidated by NMR spectra, X-ray diffraction, and quantum chemical calculations. Lancolides A (1) and D (4) had specific antiplatelet aggregation induced by platelet-activating factor (PAF).

Activation of bile salt dependent lipase by (lyso)phosphatidic acid and platelet activating factor.

The activity of breast milk BSDL was assayed with or without phospholipids as extra-intestinal effector candidates. Phosphatidic acid, lysophosphatidic acid and platelet activating factor but not phosphatidylcholine and lysophosphatidylcholine stimulated BSDL activity at least as efficiently as taurocholate. The apparent dissociation constants of PA and LPA at saturating concentrations of three different substrates were between 0.1 and 13.4 µM and that of PAF was below or equal to 200 pM. Kinetic data suggested the existence of at least one binding site for each of these effectors. PA, LPA and PAF are likely extra-intestinal modulators of BSDL activity.

Targeted lipidomics - advances in profiling lysophosphocholine and platelet-activating factor second messengers.

Glycerophosphocholines are the major building blocks of biological membranes. They are also precursors of low-molecular-weight second messengers with mass to charge ratios of 450-600. These messengers include lysophosphatidylcholines (LPCs) and lyso-platelet activating factors (PAFs) that may be further processed into PAFs. Often considered as a single species, LPCs, PAFs and lyso-PAFs are, in fact, families of glycerophosphocholine-derived lipids distinguished by the linkage of their sn-1 carbon chains to the phosphoglyceride backbone (ester or ether), their sn-1 carbon chain length and degree of unsaturation, and the identity of their sn-2 constituents (a hydroxyl or acetyl group). Each LPC and PAF species exhibits a different affinity for its cognate G-protein-coupled receptors, and each species elicits receptor-independent actions that play critical signalling roles. Targeted mass spectrometry-based lipidomic approaches are enabling the molecular identification and quantification of these low-abundance second messengers. Variations between datasets map the temporal landscape of second messengers available for signalling, and provide snapshots of the state of structural membrane compositional remodelling at the time of extraction. Here, we review a number of advances in lipidomic methodologies used to identify LPCs, lyso-PAFs and PAFs, and highlight how these targeted approaches are providing valuable insight into the roles played by the cellular lipidome in cell function and disease susceptibility.

Targeting Trypanosoma cruzi platelet-activating factor receptors: scope for the development of novel drugs to treat Chagas Disease.

Chagas Disease (CD), a tropical parasitic disease caused by the flagellate protozoan Trypanosoma cruzi, accounts for the highest burden of parasitic diseases in the Western hemisphere. Current drug treatments for CD are highly toxic and often ineffective, particularly for the chronic stage of the disease, a fact that clearly emphasizes the importance of identification/validation of molecular targets for the development of new drugs to treat the disease. Here, we review in details the evidences that suggest the existence of specific receptors for platelet-activating factor (PAF) in T. cruzi, the role of PAF on the control of parasite differentiation and the potential of exploring these putative receptors as new targets for the chemotherapy of CD.

Differential interaction of peptides derived from C-terminal domain of human apolipoprotein E with platelet activating factor analogs.

Apolipoprotein-derived peptides are promising candidates for the treatment of various inflammatory conditions and the main mechanism proposed for the protective action of these peptides includes binding to pro-inflammatory lipid mediators with high affinity and facilitating their sequestration/metabolism/clearance in the body. Molecules that act as pro-inflammatory lipid mediators differ considerably in their molecular structures, chemical compositions and physicochemical properties. Importance of the properties of pro-inflammatory lipid mediators on the biological activity of apolipoprotein-derived peptides has not been studied in detail. In this study, we characterized the physicochemical properties of aggregates containing lyso-PAF, acetyl-PAF and butanoyl-PAF, three closely related pro-inflammatory lipid mediators, and studied their interaction with peptides derived from the C-terminal domains of human apolipoprotein E. These PAF-analogs differ only in the chemical composition of the functional groups they carry at the sn-2 positions. Our results show that physicochemical properties of aggregates containing lyso-PAF, acetyl-PAF and butanoyl-PAF differ considerably and affect their apolipoprotein-derived peptides-binding capacity.