Trans -10, cis -12-conjugated linoleic acid modulates NF-κB activation and TNF-α production in porcine peripheral blood mononuclear cells via a PPARγ-dependent pathway

Conjugated linoleic acid (CLA) as a functional food: Is it beneficial or not?

Conjugated linoleic acid (CLA) has attracted great attention in recent years as a popular class of functional food that is broadly used. It refers to a group of geometric and positional isomers of linoleic acid (LA) with a conjugated double bond. The main natural sources of CLA are dairy products, beef and lamb, whereas only trace amounts occur naturally in plant lipids. CLA has been shown to improve various health issues, having effects on obesity, inflammatory, anti-carcinogenicity, atherogenicity, immunomodulation, and osteosynthesis. Also, compared to studies on humans, many animal researches reveal more positive benefits on health. CLA represents a nutritional avenue to improve lifestyle diseases and metabolic syndrome. Most of these effects are attributed to the two major CLA isomers [conjugated linoleic acid cis-9,trans-11 isomer (c9,t11), and conjugated linoleic acid trans-10,cis-12 isomer (t10,c12)], and their mixture (CLA mix). In contrast, adverse effects of CLA have been also reported, such as glucose homeostasis, insulin resistance, hepatic steatosis and induction of colon carcinogenesis in humans, as well as milk fat inhibition in ruminants, lowering chicken productivity, influencing egg quality and altering growth performance in fish. This review article aims to discuss the health benefits of CLA as a nutraceutical supplement and highlight the possible mechanisms of action that may contribute to its outcome. It also outlines the feasible adverse effects of CLA besides summarizing the recent peer-reviewed publications on CLA to ensure its efficacy and safety for proper application in humans.

Piperine treating sciatica through regulating inflammation and MiR-520a/P65 pathway

Although the etiology of sciatica remains uncertain, there is increasing evidence that the disease process of sciatica is associated with the levels of inflammatory factors. Piperine, an alkaloid isolated from Piper nigrum, has previously been demonstrated to inhibit inflammation and analgesic effects. The purpose of this study is to verify the regulatory relationship between miR-520a and p65 and to explore how miR-520a/P65 affects the level of cytokines under the action of piperine, so as to play a therapeutic role in sciatica. Through ELISA experiment, we confirmed that four inflammatory factors (IL-1β, TNF-α, IL-10, TGF-β1) can be used as evaluation indexes of sciatica. The differentially expressed miRNA was screened as miR-520a, by microarray technology, and the downstream target of miR-520a was P65 by bioinformatics. Real-time fluorescence quantitative PCR confirmed that the expression of miR-520a was negatively correlated with pro-inflammatory cytokines, positively correlated with anti-inflammatory cytokines and negatively correlated with p65 expression at mRNA level. The expression of p65 was positively correlated with pro-inflammatory cytokines and negatively correlated with anti-inflammatory cytokines at the protein level verified by ELISA and Western blot. HE staining analysis showed that the nerve fibers were repaired by piprine, the vacuoles were significantly reduced, and the degree of nerve fiber damage was also improved. Immunohistochemical analysis showed that the expression of p65 decreased after administration of piperine. Dual-luciferase reporter gene assay confirmed that the luciferase signal decreased significantly after cotransfection of miR-520a mimics and p65 3'UTR recombinant plasmid. To sum up, in the rat model of non-compressed lumbar disc herniation, piperine plays a significant role in analgesia. MiR-520a can specifically and directly target P65, and piperine can promote the expression of miR-520a, then inhibit the expression of p65, down-regulate the pro-inflammatory factors IL-1β and TNF-α, and up-regulate the effects of anti-inflammatory factors IL-10 and TGF-β1, so as to treat sciatica.

Interaction between piperine and genes associated with sciatica and its mechanism based on molecular docking technology and network pharmacology

Abstract

Piperine is the main active component of Piper longum L., which is also the main component of anti-sciatica Mongolian medicine Naru Sanwei pill. It has many pharmacological activities such as anti-inflammatory and immune regulation. This paper aims to preliminarily explore the potential mechanism of piperine in the treatment of sciatica through network pharmacology and molecular docking. TCMSP, ETCM database and literature mining were used to collect the active compounds of Piper longum L. Swiss TargetPrediction and SuperPred server were used to find the targets of compounds. At the same time, CTD database was used to collect the targets of sciatica. Then the above targets were compared and analyzed to select the targets of anti-sciatica in Piper longum L. The Go (gene ontology) annotation and KEGG pathway of the targets were enriched and analyzed by Metascape database platform. The molecular docking between the effective components and the targets was verified by Autodock. After that, the sciatica model of rats was established and treated with piperine. The expression level of inflammatory factors and proteins in the serum and tissues of rat sciatic nerve were detected by ELISA and Western blot. HE staining and immunohistochemistry were carried out on the sciatica tissues of rats. The results showed that Piper longum L. can regulate the development of sciatica and affect the expressions of PPARG and NF-kB1 through its active ingredient piperine, and there is endogenous interaction between PPARG and NF-kB1.

Graphic abstract

The Microbiome of the Built Environment and Human Behavior: Implications for Emotional Health and Well-Being in Postmodern Western Societies

It is increasingly evident that inflammation is an important determinant of cognitive function and emotional behaviors that are dysregulated in stress-related psychiatric disorders, such as anxiety and affective disorders. Inflammatory responses to physical or psychological stressors are dependent on immunoregulation, which is indicated by a balanced expansion of effector T-cell populations and regulatory T cells. This balance is in part driven by microbial signals. The hygiene or "old friends" hypothesis posits that exposure to immunoregulation-inducing microorganisms is reduced in modern urban societies, leading to an epidemic of inflammatory disease and increased vulnerability to stress-related psychiatric disorders. With the global trend toward urbanization, humans are progressively spending more time in built environments, thereby, experiencing limited exposures to these immunoregulatory "old friends." Here, we evaluate the implications of the global trend toward urbanization, and how this transition may affect human microbial exposures and human behavior.

Modulation of inflammation and immunity by dietary conjugated linoleic acid

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid. This family of polyunsaturated fatty acids has drawn significant attention in the last three decades for its variety of biologically beneficial properties and health effects. CLA has been shown to exert various potent protective functions such as anti-inflammatory, anticarcinogenic, antiadipogenic, antidiabetic and antihypertensive properties in animal models of disease. Therefore, CLA represents a nutritional avenue to prevent lifestyle diseases or metabolic syndrome. Initially, the overall effects of CLA were thought to be the result of interactions between its two major isomers: cis-9, trans-11 and trans-10, cis-12. However, later evidence suggests that such physiological effects of CLA might be different between the isomers: t-10, c-12-CLA is thought to be anticarcinogenic, antiobesity and antidiabetic, whereas c-9, t-11-CLA is mainly anti-inflammatory. Although preclinical data support a benefit of CLA supplementation, human clinical findings have yet to show definitive evidence of a positive effect. The purpose of this review is to comprehensively summarize the mechanisms of action and anti-inflammatory properties of dietary CLA supplementation and evaluate the potential uses of CLA in human health and disease.

Dietary conjugated linoleic acid and its effect on immune response in pigs infected with the porcine reproductive and respiratory syndrome virus

The aim of this study was to evaluate the effects of dietary conjugated linoleic acid (CLA) on immune response in pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV). A total of 18 pigs 4 weeks of age were allocated to 3 treatments, 6 per treatment: 0% CLA, 1% CLA, and 2% CLA. Serum IL-1β, IL-6 and TNF-α; lymphocyte proliferation; and IL-2, IFN-γ, IL-10, IL-4 and IL-12 in PBMCs were evaluated. NF-κB, COX2, iNOS and PPAR-γ mRNA were also evaluated. No differences were observed among treatment groups in most of the in vivo cytokine profiles; only TNF-α production was increased in infected pigs in the CLA-supplemented groups. The cytokine profile in vitro was not affected by CLA supplementation. CLA decreased the proliferation of PBMCs stimulated with PRRSVs. Inflammation mediators and PPAR-γ were not affected by CLA in infected pigs. CLA did not improve the immune response of PRRSV infected pigs.

Yeast cell surface display of linoleic acid isomerase from Propionibacterium acnes and its application for the production of trans-10, cis-12 conjugated linoleic acid

Conjugated linoleic acid (CLA), a family of geometric and positional isomers of linoleic acid, has many health-promoting properties. Different isomers of CLA may have very different physiological effects. In the current work, we explore the possibility to produce single isomer of CLA by using biocatalysis based on displayed biocatalysts on the yeast cell surfaces. A reporter system used to assess gene expression and protein distribution was established by combining the egfp gene to the N-terminus of Propionibacterium acnes pai gene encoding the linoleic isomerase onto vector pYD1. After induction of the yeast strains containing pYD1::egfp::pai with galactose, strong green fluorescence was observed on the surface of cells, demonstrating that the fusion protein was successfully displayed. Using the engineered strains as whole-cell biocatalyst, trans-10, cis-12 CLA was detected in the reaction mixture. To improve the biocatalytic potential of this system, the first 20 amino codons of pai were modified, and the catalytic reaction conditions were optimized. Optimization of the codon usage resulted in 35% increase of CLA production, and the maximum yield of CLA was observed within 20 H in the optimal conditions: pH 7.0, 4 mg/mL linoleic acid, 37 °C. The system established in the present work can guide the development of biocatalytic strategies to produce trans-10, cis-12 CLA single isomer.

Limited Applicability of GW9662 to Elucidate PPARγ-Mediated Fatty Acid Effects in Primary Human T-Helper Cells

Synthetic antagonists of the nuclear receptor PPARγ such as GW9662 are widely used to elucidate receptor-mediated ligand effects. In addition and complementary to recent work, we examined whether GW9662 is suitable to serve for mechanistic investigation in T-helper cells. Human peripheral blood mononuclear cells (PBMC) were preincubated with increasing concentrations of GW9662 (0, 0.4, 2, and 10 μmol/L) 30 min before adding the c9,t11-isomer of conjugated linoleic acid (c9,t11-CLA) as representative of PPARγ-activating fatty acids with immunomodulatory properties. Corresponding cultures were incubated with GW9662 in the absence of the fatty acid. After 19 h, cells were mitogen stimulated for further 5 h. Subsequently, intracellular IL-2 was measured in CD3⁺CD4⁺ lymphocytes by means of flow cytometry. 100 μmol/L c9,t11-CLA reduced the number of T-helper cells expressing IL-2 by 68%. GW9662 failed to abrogate this fatty acid effect, likely due to the fact that the compound exerted an own inhibitory effect on IL-2 production. Moreover, GW9662 dose-dependently induced cell death in human leukocytes. These results suggest that application of GW9662 is not conducive in this experimental setting.

Effects of cis-9,trans-11 and trans-10,cis-12 conjugated linoleic acid, linoleic acid, phytanic acid and the combination of various fatty acids on proliferation and cytokine expression of bovine peripheral blood mononuclear cells

Fatty acids may have an impact on immune functions, which is important in times of increased mobilization of body fat, e.g., around parturition. The aim of the present study was to investigate the effects of the CLA isomers cis-9,trans-11 and trans-10,cis-12, phytanic acid (PA), linoleic acid (LA) and a fatty acid (FA) mixture (containing 29.8% palmitic acid, 6.7% palmitoleic acid, 17.4% stearic acid and 46.1% oleic acid) on the proliferation of bovine blood mononuclear cells (PBMC) in vitro using alamar blue (AB) and 5-bromo-2′-deoxyuridine (BrdU) assay. Quantitative real time polymerase chain reaction analyses were performed to evaluate the expression of interleukin (IL)-4, IL-10, interferon (IFN)-γ, tumor necrosis factor (TNF)-α and peroxisome proliferator-activated receptor (PPAR)-γ in response to cis-9,trans-11 and LA. The IC₅₀ values did not differ between the investigated FA, but there were differences within the proliferation in the response of these FA in a concentration range between 20 and 148 µM (e.g., increased proliferation after treatment with lower concentrations of LA). No differences occurred when different FA combinations were tested. ConA stimulation increased the expression of TNF-α and IFN-γ, whereas IL-10 decreased. In general, neither the baseline expression nor the ConA-stimulated mRNA expression of cytokines and PPAR-γ were affected by the FA. In conclusion, all FA inhibit the proliferation of PBMC dose dependently without significantly altering the induced cytokine spectrum of activated bovine PBMC.

Long chain fatty acids and gene expression in inflammation and immunity

PURPOSE OF REVIEW

The purpose of this review is to discuss recent studies reporting on the influence of fatty acids on gene expression in relation to inflammation and immune responses.

RECENT FINDINGS

Saturated fatty acids promote, whereas several n-3 fatty acids, in particular eicosapentaenoic and docosahexaenoic acids, some isomers of conjugated linoleic acid, and punicic acid suppress, expression of inflammatory genes. The most common targets of fatty acids are genes encoding cytokines, chemokines, cyclooxygenase, nitric oxide synthase, and matrix metalloproteinases. The anti-inflammatory actions of fatty acids often involve inhibition of activation of nuclear factor-κB and activation of peroxisome proliferator-activated receptors α and γ. Common upstream events include actions on Toll-like receptors and via G-protein coupled receptors. Fatty acids can influence expression of genes involved in immune and inflammatory cell development and differentiation. Recent studies using genome-wide analyses demonstrate that dietary fatty acids can alter expression of a large number (many hundreds) of genes in human peripheral blood mononuclear cells.

SUMMARY

A wide range of fatty acids alter expression of genes involved in development, differentiation, and function of cells involved in inflammation and immunity.

Current issues surrounding the definition of trans-fatty acids: implications for health, industry and food labels

The definition of trans-fatty acids (TFA) was established by the Codex Alimentarius to guide nutritional and legislative regulations to reduce TFA consumption. Currently, conjugated linoleic acid (CLA) is excluded from the TFA definition based on evidence (primarily preclinical studies) implying health benefits on weight management and cancer prevention. While the efficacy of CLA supplements remains inconsistent in randomised clinical trials, evidence has emerged to associate supplemental CLA with negative health outcomes, including increased subclinical inflammation and oxidative stress (particularly at high doses). This has resulted in concerns regarding the correctness of excluding CLA from the TFA definition. Here we review recent clinical and preclinical literature on health implications of CLA and ruminant TFA, and highlight several issues surrounding the current Codex definition of TFA and how it may influence interpretation for public health. We find that CLA derived from ruminant foods differ from commercial CLA supplements in their isomer composition/distribution, consumption level and bioactivity. We conclude that health concerns associated with the use of supplemental CLA do not repudiate the exclusion of all forms of CLA from the Codex TFA definition, particularly when using the definition for food-related purposes. Given the emerging differential bioactivity of TFA from industrial v. ruminant sources, we advocate that regional nutrition guidelines/policies should focus on eliminating industrial forms of trans-fat from processed foods as opposed to all TFA per se.

trans-10,cis-12 conjugated linoleic acid promotes bone formation by inhibiting adipogenesis by peroxisome proliferator activated receptor-γ-dependent mechanisms and by directly enhancing osteoblastogenesis from bone marrow mesenchymal stem cells

The bone undergoes continuous remodeling of osteoblastic bone formation and osteoclastic bone resorption to maintain proper bone mass. It is also reported that bone marrow adiposity has a reciprocal role in osteoblasts due to their same origin from mesenchymal stem cells. In addition, one of the key mediators of adipogenesis, peroxisome-proliferator activated receptor-γ (PPARγ), plays a significant role in osteoblastogenesis in bone marrow mesenchymal stem cells. One dietary component that is known to have significant impact on adiposity and bone mass is conjugated linoleic acid (CLA). However, the link between controlling adiposity to improving bone mass by CLA has not been studied intensively. Thus, the purpose of this study is to determine the role of CLA on bone marrow adiposity and bone formation using murine mesenchymal stem cells. The results confirmed that the trans-10,cis-12 CLA, but not the cis-9,trans-11 CLA isomer, significantly inhibited adipogenesis and promoted osteoblastogenesis from mesenchymal stem cells. The inhibition of adipogenesis by the trans-10,cis-12 CLA was mediated by PPARγ; however, the trans-10,cis-12 CLA had a direct effect on osteoblastogenesis which was independent to PPARγ in this model. The trans-10,cis-12 CLA also had significant effects on osteoclastogenesis inhibitory factor, which suggests potential influence of CLA on osteoclastogenesis. Overall, the results suggest that the trans-10,cis-12, but not the cis-9,trans-11 CLA isomer, has a positive impact on bone health by both PPARγ mediated and independent mechanisms in mesenchymal stem cells.

Dietary conjugated linoleic acid activates PPARγ and the intestinal trefoil factor in SW480 cells and mice with dextran sulfate sodium-induced colitis

A central event in inflammatory bowel disease is the disruption of the mucosal homeostasis. Trefoil peptides [(TFF)] are emerging as key mediators in the defense and repair of the gastrointestinal mucosa. Here, we demonstrate induction of TFF by CLA with therapeutic antiinflammatory effects in a mouse model of inflammatory bowel disease. SW480 cells were treated with linoleic acid or CLA (0-2.5 μmol/L) in the absence or presence of the PPARγ inhibitor GW9662. Cells treated with CLA showed an upregulation of the intestinal trefoil factor, which was prevented by pretreatment with GW9662. Dextran sulfate sodium (2%) was used to induce colitis in mice and they were simultaneously fed with a standard or a CLA-supplemented (100 mg · kg(-1) · d(-1)) diet for 7 d. The CLA-enriched diet prevented the colon shortening induced by DSS and markedly reduced the disease activity index and the colonic expression of inducible NO synthase and NF-κB. Immunohistochemistry revealed an increase in PPARγ and TFF3 expression after CLA administration. Altogether, these results indicate that dietary CLA protects against DSS-induced colitis in a process involving induction of PPARγ and TFF3.