Development and immunological evaluation of HLA-specific chronic myeloid leukemia polyepitope vaccine in Chinese population

Background

BCR/ABL and Wilms’ tumor 1 (WT1) are an ideal tumor associated antigens which can be used to develop a potential chronic myeloid leukemia (CML) dentritic cell (DC) vaccine. Here, we constructed a novel polyepitope vaccine which used recombinant lentiviral vector carrying BCR/ABL and WT1 genes, and determined the immunological effects of this vaccine in vitro.

Methods

The DC vaccine was constructed using lentiviral vector transduced DCs. T lymphocytes were stimulated with DC vaccine and then co-cultured in vitro with peripheral blood mononuclear cells (PBMCs) from CML or ALL patients, respectively. The cytotoxicity of proliferous cytotoxic T lymphocytes (CTLs) was determined by the LDH assay. The IFN-γ production of CTLs was detected using ELISPOT assay.

Results

We constructed an lentiviral vector encoding 50 different epitopes from BCR/ABL and WT1 antigens, and transferred it into DCs to prepare the DC vaccine successfully. The in vivo stimulation of CTLs with this DC vaccine were proved to show strong cytotoxicity and produce high level of IFN-γ.

Conclusions

The novel recombinant lentiviral polyepitope DC vaccine is a promising candidate for clinical trials and may be an effective approach for CML immunotherapy.     

Docosahexaenoic acid prevents dendritic cell maturation and in vitro and in vivo expression of the IL-12 cytokine family

Background  

Acute and chronic inflammation play essential roles in inflammatory/autoimmune conditions. Protective anti-inflammatory effects of the n-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were reported in animal models of colitis, sepsis, and stroke. Since dendritic cells (DC) represent the essential cellular link between innate and adaptive immunity and have a prominent role in tolerance for self-antigens, we sought to investigate the impact of DHA on DC maturation and proinflammatory cytokine production.     

SHIV virus-like particles bind and activate human dendritic cells

We previously demonstrated that mucosal immunization with SHIV virus-like particles (VLPs) was able to induce strong humoral and cellular immune responses against HIV envelope protein (Env). To understand the mechanism for such enhanced immune responses, we studied the interaction between VLPs and dendritic cells (DCs) in initiating immune responses. We found that about 50% of DCs were bound by octadecyle rhodamine B (R18) labeled SHIV VLPs. The bound SHIV VLPs were internalized by DCs when cultured at 37 °C. Incubation of immature human PBMC-derived DCs with SHIV VLPs for 48 h resulted in the significant up-regulation of CD40, CD80, CD83, CD54, CD86, HLA-A, B, C and HLA-DR, DP, DQ molecules on activated DC CD11c⁺ subpopulations. SHIV VLPs efficiently stimulated DCs to release IL-12, IFN-γ and TNF-α. Furthermore, SHIV VLPs-activated DCs were fully functional in inducing allogeneic T cell proliferation. We conclude that DCs can interact and process SHIV VLPs efficiently and may be critical in initiation of SHIV VLPs-induced immune responses. Thus, interaction between VLPs and DCs may play an important role in the enhancement of immune responses in VLPs-based vaccination.     

A comparative analysis of chiropractic and general practitioner patients in North America: Findings from the joint Canada/United States survey of health, 2002–03

Background  

Scientifically rigorous general population-based studies comparing chiropractic with primary-care medical patients within and between countries have not been published. The objective of this study is to compare care seekers of doctors of chiropractic (DCs) and general practitioners (GPs) in the United States and Canada on a comprehensive set of sociodemographic, quality of life, and health-related variables.     

Vitamin D3 metabolite calcidiol primes human dendritic cells to promote the development of immunomodulatory IL-10-producing T cells

Vitamin D is recognized as a potent immunosuppressive drug. The suppressive effects of vitamin D are attributed to its physiologically active metabolite 1,25 dihydroxy vitamin D3 (calcitriol), which was shown, to prime dendritic cells (DCs) to promote the development of regulatory T (Treg) cells. Despite the potential benefit in treating autoimmune diseases, clinical application of calcitriol is hindered by deleterious side effects manifested by hypercalcemia and hypercalciuria. Conversely, the physiological precursors of calcitriol, vitamin D3 (cholecalciferol) and its first metabolite 25-hydroxy vitamin D3 (calcidiol) are widely applied in the clinic due to their low calcimic burden. However, the mechanisms by which cholecalciferol and calcidiol may modulate adaptive immunity remain elusive. This prompted us to unravel the immunosuppressive capacity of these precursors by assessing their influence on DC functions and the subsequent polarization of naïve CD4⁺ T cells. In this study we show that, whereas cholecalciferol has insignificant effects on DC maturation and cytokine production, it only weakly primed DCs to induce suppressive T cells. However, like calcitriol, calcidiol not only exerted an inhibitory effect on DC maturation and cytokine production, and primed DCs to promote the development of suppressive IL-10-producing Treg cells. Strikingly, in contrast to the population of IL-10-producing Treg cells induced by calcitriol-primed DCs, the IL-10-producing Treg cells induced by calcidiol-primed DCs exhibited sustained IFN-γ production in face of their suppressive capacity. Experiments with the steroid synthesis inhibitor ketoconazole indicated that the immunomodulatory features of the precursors are dependent on their conversion into calcitriol. Collectively, calcidiol is a potent immune modulator, which may be more adequate than calcitriol for the treatment of chronic inflammatory diseases, since it is less hypercalcimic. This may be of particular interest for the treatment of allergic disease, where concurrent suppression and sustained IFN-γ production by Treg cells effectively counterbalance the Th2-dominated immune responses.     

Comparison of clinical grade type 1 polarized and standard matured dendritic cells for cancer immunotherapy

Monocyte-derived dendritic cells (DCs) used for immunotherapy e.g. against cancer are commonly matured by pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and prostaglandin E₂ although the absence of Toll-like receptor mediated activation prevents secretion of IL-12 from DCs and subsequent efficient induction of type 1 effector T cells. Standard matured clinical grade DCs “sDCs” were compared with DCs matured with either of two type 1 polarizing maturation cocktails; the alpha-type-1 DCs “αDC1s” (TNF-α, IL-1β, IFN-γ, IFN-α, Poly(I:C)) and “mDCs” (monophosphoryl lipid A (MPL), IFN-γ) or a mixed cocktail – “mpDCs”, containing MPL, IFN-γ and PGE₂. αDC1s and mDCs secreted IL-12 directly and following re-stimulation with CD40L-expressing cells and they mainly secreted the T effector cell attracting chemokines CXCL10 and CCL5 as opposed to sDCs that mainly secreted CCL22, known to attract regulatory T cells. αDC1s and mDCs were functionally superior to sDCs as they polarized naïve CD4⁺ T cells most efficiently into T helper type 1 effector cells and primed more functional MART-1 specific CD8⁺ T cells although with variation between donors. αDC1s and mDCs were transiently less capable of CCL21-directed transwell migration than standard matured DCs, likely due to their increased secretion of CCL19, which mediate internalization of CCR7. mpDCs were intermediate between standard and polarized DCs both in terms of IL-12 secretion and transwell migratory ability but functionally they resembled sDCs and strikingly had the highest expression of the inhibitory molecules PD-L1 and CD25. Thus, further studies with type 1 polarized DCs are warranted for use in immunotherapy, but when combined with PGE₂ as in mpDCs, they seems to be less optimal for maturation of DCs.     

Pathogen sensors and chemokine receptors in dendritic cell subsets

Pathogen sensors such as Toll-like receptors (TLRs) detect microorganism- or host-derived conserved molecular structures, including lipids or nucleic acids and provoke activation of Ag presenting cells such as dendritic cells (DCs). Several synthetic TLR ligands, especially oligonucleotides, are being developed as promising vaccines for infectious diseases, cancers or allergies. DCs are heterogeneous and consist of various subsets, each of which expresses a subset-specific repertoire of TLRs and responds to the TLR signaling in a subset-specific manner. Furthermore, each DC subset expresses a set of chemokine receptors that regulate its function and behavior. Here I review the functions of two DC subsets and how chemokine receptors function in these subsets. One is the plasmacytoid DC (pDC), which expresses nucleic acid sensing receptors TLR7 and TLR9 and secretes large amounts of type I interferons in response to TLR7/9 signaling. The other is splenic CD8α⁺ conventional DC (cDC). This DC subset expresses lipid sensors, TLR2 and TLR4, and nucleic acid sensors, TLR3, TLR9 and TLR13 and is specialized for antigen crosspresentation. Several chemokine receptors are differentially expressed on these DC subsets. The homologues of these murine DC subsets are also found in humans. Understanding how these DC subsets function and respond to TLR ligands and chemokines should be important for development of effective vaccines.     

Effects of thyroxine and 1-methyl, 2-mercaptoimidazol on phosphoinositides synthesis in rat liver

Background  

Phosphoinositides mediate one of the intracellular signal transduction pathways and produce a class of second messengers that are involved in the action of hormones and neurotransmitters on target cells. Thyroid hormones are well known regulators of lipid metabolism and modulators of signal transduction in cells. However, little is known about phosphoinositides cycle regulation by thyroid hormones. The present paper deals with phosphoinositides synthesis de novo and acylation in liver at different thyroid status of rats.     

Addition of interferon-alpha to a standard maturation cocktail induces CD38 up-regulation and increases dendritic cell function

Monocyte-derived dendritic cells (DCs) are used as adjuvant cells in cancer immunotherapy and have shown promising results. In order to obtain full functional capacity, these DCs need to be maturated, and the current “gold standard” for this process is maturation with TNF-α, IL-1β, IL-6 and PGE₂ used for generating standard DCs (sDC). Several studies indicate that IFN-α might also be important for DC differentiation and maturation. In this study, we tested the effect of IFN-α alone or as addition to the gold standard sDC cocktail. We observed that maturation by IFN-α differs from sDC maturation: The major phenotypic change after IFN-α maturation was dose-dependent up-regulation of CD38 but not CD83, while sDCs expressed the opposite profile with low CD38 and high CD83 expression. Similarly, maturation by Poly I:C leads to CD38high, CD83low DCs indicating a functional relationship between CD38, IFN-α and TLR3. Thus, CD38 appear to be a relevant marker for activation by TLR3 or IFN-α. Addition of IFN-α to the sDC cocktail results in up-regulation of both CD38 and CD83 and improved capacity for induction of autologous T-cell responses despite few other changes in DC phenotype and cytokine secretion. Our observations suggest that IFN-α could be included in maturation protocols for clinical grade DCs used for immunotherapy against cancer and should be included if DCs are used for CD8+ T-cell stimulation in vitro.     

Fish oil supplementation reverses the effect of cholesterol on apoptotic gene expression in smooth muscle cells

Background  

Nutritional control of gene regulation guides the transformation of smooth muscle cells (SMC) into foam cells in atherosclerosis. Oxidative stress has been reported in areas of lipid accumulation, activating proliferation genes. Suppression of oxidative stress by antioxidant administration reduces this activation and the progression of lesions. We hypothesized that fish oil consumption may protect against atherosclerotic vascular disease. The study objective was to determine the effects of dietary cholesterol and fish-oil intake on the apoptotic pathways induced by 25-hydroxycholesterol (25-HC) in SMC cultures.     

视黄酸对脐血树突状细胞的作用及其途径

目的:研究视黄酸(RA)对脐血树突状细胞(dendriticcell,DC)分化、成熟和功能的影响,探讨视黄酸受体(retinoicacidreceptorα,RARα)在RA对脐血DC调节中的作用。方法:收集脐血9份,分离单个核细胞后,均匀分为4组:对照组、RA组、RARα特异性拮抗剂组(RO组)、RA+RO组。在体外进行DC的诱导培养,流式细胞仪检测细胞表面标记及其荧光强度,观察RA及RARα对DC分化、成熟的影响;培养DC与T细胞进行混合淋巴细胞反应(mixedlymphocytereaction,MLR)后,观察RA及RARα对DC刺激异体T细胞增殖能力的作用;采用ELISA法和RT-PCR法研究RA和RARα在DC对Th细胞极向分化调节中的作用。结果:RA使DC的分化、成熟明显受抑,但当RO同时加入时,则可逆转该影响;MLR后发现RO可逆转RA对T细胞增殖的抑制作用;在DC对T细胞极向分化的研究中,无论在蛋白水平还是基因水平,RO均可明显阻止RA对Th1(IFN-γ)的下调和对Th2(IL-4、IL-10)的上调作用。结论:RA抑制体外培养的脐血单个核细胞向DC的分化和成熟,降低其MLR能力,使免疫反应向Th2方向偏移。RARα从多个环节上参与了RA对脐血DC的调节作用。     

Pediatric patient asthma-related emergency department visits and admissions in Washington,DC, from 2001–2004, and associations with air quality,socio-economic status and age group

Background  

The District of Columbia (DC) Department of Health, under a grant from the US Centers for Disease Control and Prevention, established an Environmental Public Health Tracking Program. As part of this program, the goals of this contextual pilot study are to quantify short-term associations between daily pediatric emergency department (ED) visits and admissions for asthma exacerbations with ozone and particulate concentrations, and broader associations with socio-economic status and age group.     

Viral vector and route of administration determine the ILC and DC profiles responsible for downstream vaccine-specific immune outcomes

This study demonstrates that route and viral vector can significantly influence the innate lymphoid cells (ILC) and dendritic cells (DC) recruited to the vaccination site, 24?h post delivery. Intranasal (i.n.) vaccination induced ST2/IL-33R⁺ ILC2, whilst intramuscular (i.m.) induced IL-25R⁺ and TSLPR⁺ (Thymic stromal lymphopoietin protein receptor) ILC2 subsets. However, in muscle a novel ILC subset devoid of the known ILC2 markers (IL-25R^? IL-33R^? TSLPR^?) were found to express IL-13, unlike in lung. Different viral vectors also influenced the ILC-derived cytokines and the DC profiles at the respective vaccination sites. Both i.n. and i.m. recombinant fowlpox virus (rFPV) priming, which has been associated with induction of high avidity T cells and effective antibody differentiation exhibited low ILC2-derived IL-13, high NKp46⁺ ILC1/ILC3 derived IFN-γ and low IL-17A, together with enhanced CD11b⁺ CD103^? conventional DCs (cDC). In contrast, recombinant Modified Vaccinia Ankara (rMVA) and Influenza A vector priming, which has been linked to low avidity T cells, induced opposing ILC derived-cytokine profiles and enhanced cross-presenting DCs. These observations suggested that the former ILC/DC profiles could be a predictor of a balanced cellular and humoral immune outcome. In addition, following i.n. delivery Rhinovirus (RV) and Adenovius type 5 (Ad5) vectors that induced elevated ILC2-derived IL-13, NKp46⁺ ILC1/ILC3-derived-IFN-γ and no IL-17A, predominantly recruited CD11b^? B220⁺ plasmacytoid DCs (pDC). Knowing that pDC are involved in antibody differentiation, we postulate that i.n. priming with these vectors may favour induction of effective humoral immunity. Our data also revealed that vector-specific replication status and/or presence or absence of immune evasive genes can significantly alter the ILC and DC activity. Collectively, our findings suggest that understanding the route- and vector-specific ILC and DC profiles at the vaccination site may help tailor/design more efficacious viral vector-based vaccines, according to the pathogen of interest.     

Role of DNA topology in uptake of polyplex molecules by dendritic cells

Dendritic cells (DCs) are an attractive target for DNA vaccines as they are potent antigen presenting cells. This study demonstrated how non-viral gene delivery to DCs involving complexes of poly-l-lysine (PLL) and plasmid DNA (pDNA) (polyplexes) showed dependence on DNA vector topology. DNA topology is of importance from both production and regulatory viewpoints. In our previous study with CHO cells we demonstrated that polyplex uptake was dependent on DNA topology whereby complexes containing supercoiled (SC) pDNA were smaller, more resistant to nucleases and more effectively condensed by PLL than open circular (OC) and linear-pDNA complexes. In this study polyplex uptake in DCs was measured qualitatively and quantitatively by confocal microscopy along with gene expression studies and measurement of DC phenotype. PLL is known for its ability to condense DNA and serve as an effective gene delivery vehicle. Quantification studies revealed that by 1h following uptake 15% (±2.59% relative standard error [RSE]) of SC-pDNA polyplexes were identified to be associated (fluorescent co-localisation) with the nucleus, in comparison to no nuclear association identified for OC- and linear-pDNA complexes. By 48 h following uptake, 30% (±1.82% RSE) of SC-pDNA complexes associated with the nucleus in comparison to 16% (±4.40% RSE) and 12% (±6.97% RSE) of OC- and linear-pDNA polyplexes respectively. Confocal microscopy images showed how DNA and PLL remained associated following uptake by dual labelling. Polyplex (containing 20 μg pDNA) gene expression (plasmid encoded lacZ [β-galactosidase] reporter gene) in DCs was greatest for SC-pDNA polyplexes at 14.12% unlike that of OC- (9.59%) and linear-pDNA (7.43%). DCs express cell surface markers which contribute towards antigen presentation. Polyplex gene expression did not alter DC phenotype through surface marker expression. This may be due to the pDNA dose employed (20μg) as other studies have used doses as high as 200 μg pDNA to induce DC phenotypic changes. Although no change in DC phenotype occurred, this could be advantageous in terms of biocompatibility. Collectively these results indicate that DNA topology is an important parameter for DC vector design, particularly pDNA in the SC conformation in regards to DNA vaccination studies.     

Two-step maturation of immature DCs with proinflammatory cytokine cocktail and poly(I:C) enhances migratory and T cell stimulatory capacity

Effective induction of cell-mediated immune responses strongly depends on the ability of dendritic cells (DCs) to produce Th1-polarizing cytokines, migrate to lymph nodes and stimulate T cells through antigen-presenting complex and costimulatory molecules. While various protocols for optimizing DC maturation with single or multiple stimuli mimicking infections or inflammatory milieu have been proposed for the generation of DCs with features desired for clinical application, stepwise maturation of DCs by these multiple stimuli has not been systemically assessed. Among the combinations of several immune-modulating factors with known effects on DC maturation, we found that stepwise DC maturation with cytokine cocktail (TNF-α + IL-6 + IL-1β + PGE₂) followed by poly(I:C) stimulation enhanced the production of IL-12 with strong allostimulatory capacity. While there were no significant differences between DC matured by simultaneous or sequential activation by cytokine cocktail and poly(I:C) in expression of markers and costimulatory molecules of mature DCs, the delivery of inflammatory signal prior to poly(I:C) results in sustained interleukin-12 expression with reduced IL-10 than DC matured by simultaneous stimulation. This sequential stimulation significantly increased migratory capacity in response to CCL21 and CXCL12 compared to DC matured with cytokine cocktail. Furthermore, these DCs retained their responsiveness to CD40L stimulation in secondary IL-12 production and efficiently generated autologous antigen-specific effector T cells as evidenced by ELISPOT assay. Thus, we propose a novel DC maturation protocol in which stimulation of DCs with cytokine cocktail and subsequently with poly(I:C) generates DCs with a high migratory capacity with a preferential Th1 inducing capacity.     

Omega 3 fatty acids reduce myeloid progenitor cell frequency in the bone marrow of mice and promote progenitor cell differentiation

Background  

Omega 3 fatty acids have been found to inhibit proliferation, induce apoptosis, and promote differentiation in various cell types. The processes of cell survival, expansion, and differentiation are of key importance in the regulation of hematopoiesis. We investigated the role of omega 3 fatty acids in controlling the frequency of various myeloid progenitor cells in the bone marrow of mice. Increased progenitor cell frequency and blocked differentiation are characteristics of hematopoietic disorders of the myeloid lineage, such as myeloproliferative diseases and myeloid leukemias.     

Immunological Effect of Active Hexose Correlated Compound (AHCC) in Healthy Volunteers: A Double-Blind,Placebo-Controlled Trial

The aim of this study was to evaluate the effects of active hexose correlated compound (AHCC) intake on immune responses by investigating the number and function of circulating dendritic cells (DCs) in healthy volunteers. Twenty-one healthy volunteers were randomized to receive placebo or AHCC at 3.0 g/day for 4 wk. The number of circulating cluster of differentiation (CD)11c⁺ DCs (DC1) and CD11c^? DCs (DC2) were measured. Allogeneic mixed-leukocyte reaction (MLR) was performed. Natural killer (NK) cell activity and the proliferative response of T lymphocytes toward mitogen (phytohemagglutinin [PHA]) were measured. We also measured cytokine production stimulated by lipopolysaccharide [interleukin (IL)-2, IL-4, IL-6, IL-10, interferon gamma-γ, tumor necrosis factor-α). The AHCC group (n = 10) after AHCC intake had a significantly higher number of total DCs compared to that at baseline and values from control subjects (n = 11). The number of DC1s in the AHCC group after intake was significantly higher than at baseline. DC2s in the AHCC group were significantly increased in comparison with controls. The MLR in the AHCC group was significantly increased compared to controls. No significant differences in PHA, NK cell activity, and cytokine production were found between groups. AHCC intake resulted in the increased number of DCs and function of DC1s, which have a role in specific immunity.     

Lymphocyte-polarized dendritic cells are highly effective in inducing tumor-specific CTLs

High activity of dendritic cells (DCs) in inducing cytotoxic T cells (CTLs) led to their application as therapeutic cancer vaccines. The ability of DCs to produce IL-12p70 is one of the key requirements for effective CTL induction and a predictive marker of their therapeutic efficacy in vivo. We have previously reported that defined cocktails of cytokines, involving TNFα and IFNγ, induce mature type-1 polarized DCs (DC1s) which produce strongly elevated levels of IL-12 and CXCL10/IP10 upon CD40 ligation compared to "standard" PGE(2)-matured DCs (sDCs; matured with IL-1β, IL-6, TNFα, and PGE(2)) and show higher CTL-inducing activity. Guided by our observations that DC1s can be induced by TNFα- and IFNγ-producing CD8(+) T cells, we have tested the feasibility of using lymphocytes to generate DC1s in a clinically-compatible process, to limit the need for clinical-grade recombinant cytokines and the associated costs. CD3/CD28 activation of bulk lymphocytes expanded them and primed them for effective production of IFNγ and TNFα following restimulation. Restimulated lymphocytes, or their culture supernatants, enhanced the maturation status of immature (i)DCs, elevating their expression of CD80, CD83 and CCR7, and the ability to produce IL-12p70 and CXCL10 upon subsequent CD40 ligation. The "lymphocyte-matured" DC1s showed elevated migration in response to the lymph-node-directing chemokine, CCL21, when compared to iDCs. When loaded with antigenic peptides, supernatant-matured DCs induced much high levels of CTLs recognizing tumor-associated antigenic epitope, than PGE(2)-matured DCs from the same donors. These results demonstrate the feasibility of generation of polarized DC1s using autologous lymphocytes.     

Tetraspanin-3 regulates protective immunity against Eimeria tenella infection following immunization with dendritic cell-derived exosomes

The effects of immunization with dendritic cell (DC) exosomes, which had been incubated with a tetraspanin-3 (Tspan-3) blocking antibody (Ab) or with an isotype-matched non-immune IgG, were studied using an experimental model of Eimeria tenella avian coccidiosis. Purified exosomes from cecal tonsil and splenic DCs expressed Tspan-3 protein. Chickens injected with exosomes incubated with the control IgG and derived from cecal tonsil DCs preloaded in vitro with E. tenella Ag had Ag-immunostaining cells in the ceca, but not the spleen. Conversely, Ag-containing cells were found only in the spleen, but not the ceca, of chickens given IgG treated splenic DC exosomes. Interestingly, chickens that received exosomes incubated with Tspan-3 Ab had Ag-containing cells observed in both lymphoid organs following administration of exosomes from either DC population. After injection of exosomes non-incubated with Tspan-3 Ab, greater numbers of cells secreting interleukin-2 (IL-2), IL-16, interferon-γ, and E. tenella-reactive Abs were observed in the cecal tonsils of chickens immunized with cecal DC exosomes compared with the spleen. By contrast, more cytokine-and Ab-producing cells were present in the spleen of chickens given splenic DC exosomes compared with the ceca. Incubation with Tspan-3 Ab gave similar numbers of cytokine- and Ab-producing cells in the cecal tonsils and spleen regardless of the source of exosomes. Immunization with E. tenella Ag-loaded cecal tonsil DC exosomes increased in vivo resistance against subsequent E. tenella infection. Increased protection against infection following cecal DC exosome immunization was partially blocked by incubation of exosomes with Tspan-3 Ab. These results suggest that Tspan-3 is involved in the tissue distribution, as well as cytokine and Ab production, following DC exosome administration, and that Tspan-3 contributes to in vivo protection against experimental E. tenella challenge infection following exosomal immunization.     

Suppressive actions of eicosapentaenoic acid on lipid droplet formation in 3T3-L1 adipocytes

Background  

Lipid droplet (LD) formation and size regulation reflects both lipid influx and efflux, and is central in the regulation of adipocyte metabolism, including adipokine secretion. The length and degree of dietary fatty acid (FA) unsaturation is implicated in LD formation and regulation in adipocytes. The aims of this study were to establish the impact of eicosapentaenoic acid (EPA; C20:5n-3) in comparison to SFA (STA; stearic acid, C18:0) and MUFA (OLA; oleic acid, C18:1n-9) on 3T3-L1 adipocyte LD formation, regulation of genes central to LD function and adipokine responsiveness. Cells were supplemented with 100 μM FA during 7-day differentiation.