Trans-10, cis-12 conjugated linoleic acid and the PPAR-γ agonist rosiglitazone attenuate lipopolysaccharide-induced TNF-α production by bovine immune cells

Anti-steatotic effects of PPAR-alpha and gamma involve gut-liver axis modulation in high-fat diet-fed mice

AIM

To evaluate the effects of PPARα and PPARγ activation (alone or in combination) on the gut-liver axis, emphasizing the integrity of the intestinal barrier and hepatic steatosis in mice fed a high saturated fat diet.

METHODS

Male C57BL/6J were fed a control diet (C) or a high-fat diet (HF) for ten weeks. Then, a four-week treatment started: HF-α (WY14643), HF-γ (low-dose pioglitazone), and HF-αγ (combination).

RESULTS

The HF caused overweight, insulin resistance, impaired gut-liver axis, and marked hepatic steatosis. Treatments reduced body mass, improved glucose homeostasis, and restored the gut microbiota diversity and intestinal barrier gene expression. Treatments also lowered the plasma lipopolysaccharide concentrations and favored beta-oxidation genes, reducing macrophage infiltration and steatosis in the liver.

CONCLUSION

Treatment with PPAR agonists modulated the gut microbiota and rescued the integrity of the intestinal barrier, alleviating hepatic steatosis. These results show that these agonists can contribute to metabolic-associated fatty liver disease treatment.

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.

Hormonal and immunological responses of Holstein dairy cows from late lactation to the dry period and from the dry period to early lactation

Parturition and dry-off are challenging events for dairy cows partially due to changes in endocrine responses. The aim of this experiment was to evaluate blood concentrations of cortisol and prolactin and their effects on proliferation of peripheral blood mononuclear cells (PBMC) with or without stimulation by common immune cell mitogens (lipopolysaccharide [LPS], and concanavalin A [ConA]) of multiparous dairy cows from late lactation to the dry period and from the dry period to early lactation. Two groups of cows were enrolled: cows from late lactation to the dry period enrolled at 8 d before dry-off (LTD, n = 6, days in milk at dry-off = 332 ± 41 d) and cows from the dry period to early lactation enrolled at 7 d before expected calving date (DTL, n = 7). Blood was collected on d -8, 3, 7, and 15 relatives to dry-off for LTD cows, and on d -7, 3, 7, and 21 relatives to calving for DTL cows to analyze circulating stress hormones and to isolate PBMC. The PBMC were stimulated in vitro with prolactin (PRL), hydrocortisone (HDC), LPS, ConA, PRL + LPS, PRL + ConA, HDC+LPS, and HDC + ConA to assess proliferative responses. Plasma cortisol and PRL concentrations of LTD and DTL cows were not affected by time. Regardless of time, addition of HDC reduced PBMC proliferation stimulated by LPS, but PRL had no effect. No time effect was observed for proliferation of PBMC collected from LTD cows, but PBMC collected at 21 d after calving had higher proliferative responses to LPS and ConA than those from late dry period or early lactation. In conclusion, results from this experiment confirmed the lower PBMC proliferation during the transition period from the final week of gestation to early lactation and suggested that cows transitioning from late lactation to dry period maintained unchanged cell-mediated immune function.

Role of Peroxisome Proliferator-Activated Receptors (PPARs) in Energy Homeostasis of Dairy Animals: Exploiting Their Modulation through Nutrigenomic Interventions

Peroxisome proliferator-activated receptors (PPARs) are the nuclear receptors that could mediate the nutrient-dependent transcriptional activation and regulate metabolic networks through energy homeostasis. However, these receptors cannot work properly under metabolic stress. PPARs and their subtypes can be modulated by nutrigenomic interventions, particularly under stress conditions to restore cellular homeostasis. Many nutrients such as polyunsaturated fatty acids, vitamins, dietary amino acids and phytochemicals have shown their ability for potential activation or inhibition of PPARs. Thus, through different mechanisms, all these nutrients can modulate PPARs and are ultimately helpful to prevent various metabolic disorders, particularly in transition dairy cows. This review aims to provide insights into the crucial role of PPARs in energy metabolism and their potential modulation through nutrigenomic interventions to improve energy homeostasis in dairy animals.

Role of nutraceuticals during the transition period of dairy cows: a review

The transition period of dairy cattle is characterized by a number of metabolic, endocrine, physiologic, and immune adaptations, including the occurrence of negative energy balance, hypocalcemia, liver dysfunction, overt systemic inflammatory response, and oxidative stress status. The degree and length of time during which these systems remain out of balance could render cows more susceptible to disease, poor reproductive outcomes, and less efficient for milk production and quality. Studies on both monogastrics and ruminants have reported the health benefits of nutraceuticals (e.g. probiotics, prebiotics, dietary lipids, functional peptides, phytoextracts) beyond nutritional value, interacting at different levels of the animal’s physiology. From a physiological standpoint, it seems unrealistic to disregard any systemic inflammatory processes. However, an alternate approach is to modulate the inflammatory process per se and to resolve the systemic response as quickly as possible.

To this aim, a growing body of literature underscores the efficacy of nutraceuticals (active compounds) during the critical phase of the transition period. Supplementation of essential fatty acids throughout a 2-month period (i.e. a month before and a month after calving) successfully attenuates the inflammatory status with a quicker resolution of phenomenon. In this context, the inflammatory and immune response scenario has been recognized to be targeted by the beneficial effect of methyl donors, such as methionine and choline, directly and indirectly modulating such response with the increase of antioxidants GSH and taurine. Indirectly by the establishment of a healthy gastrointestinal tract, yeast and yeast-based products showed to modulate the immune response, mitigating negative effects associated with parturition stress and consequent disorders.

The use of phytoproducts has garnered high interest because of their wide range of actions on multiple tissue targets encompassing a series of antimicrobial, antiviral, antioxidant, immune-stimulating, rumen fermentation, and microbial modulation effects. In this review, we provide perspectives on investigations of regulating the immune responses and metabolism using several nutraceuticals in the periparturient cow.

Effects of Aloe arborescens Whole Plant Homogenate on Lipid Metabolism, Inflammatory Conditions and Liver Function of Dairy Cows during the Transition Period

Simple Summary

This study highlights the positive effect of an Aloe arborescens Mill. whole plant homogenate on the liver and renal function of dairy cows during the peripartum period. Such positive effects could depend on both anti-hyperlipidemic and anti-inflammatory effects of Aloe that could have mitigated hepatic stresses that typically occur in early lactation. Our findings suggest Aloe arborescens supplementation to be an effective strategy to ameliorate adverse metabolic conditions in transition cows, indicating it as a preventive nutraceutical strategy against metabolic disorders.

Abstract

The anti-hyperlipidemic and anti-inflammatory effects exerted by Aloe on monogastric mammals suggest it as a potential strategy to address the tremendous metabolic alterations that affect dairy cows during their transition to calving. A group of 20 multiparous Italian Holstein dairy cows were housed in freestalls and allocated into two homogeneous groups to receive either 200 g/d of water (CTR) or 200 g/day of Aloe arborescens Mill. whole plant homogenate through a rumen tube (AAM) between −14 and 14 days from calving (DFC). From −14 to 35 DFC, the BCS, and milk yield were measured, and blood samples were collected to assess the hematochemical profile. Data underwent ANOVA testing using a mixed model for repeated measurements, including the treatment and time and their interactions as fixed effects. Compared to CTR cows, AAM cows had a less pronounced BCS loss in early lactation (p < 0.01), indicating less mobilization of body reserves. Compared to CTR cows, AAM cows had a lower plasma concentration of nonesterified fatty acids and beta hydroxybutyrate (p < 0.01 and = 0.01 respectively) that, paired with the lower butterfat content and fat/protein ratio in their milk (p = 0.03 and < 0.01 respectively), indicates that Aloe reduced the mobilization of body fats. AAM cows had a reduced concentration of myeloperoxidase in plasma and a lower SCC in milk compared to CTR cows (p = 0.02 for both), indicating an anti-inflammatory effect of Aloe. Furthermore, AAM cows had a lower plasma concentration of ceruloplasmin (p < 0.05) and higher plasma concentration of cholesterol, retinol, and paraoxonase compared to CTR cows (p < 0.01, < 0.01 and < 0.05 respectively), indicating Aloe was effective in mitigating the acute phase response in early lactation. Finally, AAM cows had lower plasma creatinine concentrations around calving (p < 0.05), a lower concentration of plasma bilirubin, and a higher concentration of plasma tocopherol compared to CTR cows (p = 0.01 for both). These data suggest Aloe has anti-hyperlipidemic and anti-inflammatory effects on transition dairy cows that could have ameliorated liver and kidney function disruption and increased the availability of body antioxidants in early lactation.

Wound Healing and Omega-6 Fatty Acids: From Inflammation to Repair

Wound healing is an evolutionarily conserved process that is essential for species survival. Wound healing involves a series of biochemical and cellular events that are tightly controlled, divided into 3 concomitant and overlapping phases: inflammation, proliferation, and remodelling. Poor wound healing or a chronic wound represents a silent epidemic that affects billions of people worldwide. Considering the involvement of immune cells in its resolution, recent studies are focused on investigating the roles of immune nutrients such as amino acids, minerals, and fatty acids on wound healing. Among the fatty acids, much attention has been given to omega-6 (ω-6) fatty acids since they can modulate cell migration and proliferation, phagocytic capacity, and production of inflammatory mediators. The present review summarizes current knowledge about the role of ω-6 fatty acids in the wound healing context.

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.

NE strengthens the immunosuppression induced by AlCl₃ through β₂-AR/cAMP pathway in cultured rat peritoneal macrophages

To investigate the effect of noradrenaline (NE) on the immunosuppression induced by aluminum trichloride (AlCl3), the peritoneal macrophages were cultured with RPMI-1640 medium containing 0.97 mM AlCl3 (1/10 IC50). NE was added to the medium at the final concentrations of 0 (control group, N-C), 0.1 (low-dose group, N-L), 1 (mid-dose group, N-M), and 10 (high-dose group, N-H) nM, respectively. No addition of both AlCl3 and NE serviced as blank group (D-C). Chemotaxis, adhesion, phagocytosis, tumor necrosis factor α (TNF-α) secretion, cyclic adenosine monophosphate (cAMP) content, β2 adrenergic receptors (β2-AR) density, and messenger RNA (mRNA) expression of macrophages were detected. The results showed that AlCl3 reduced the chemotaxis, adhesion, phagocytosis, and TNF-α secretion and increased the cAMP content, β2-AR density, and mRNA expression of peritoneal macrophages. Meanwhile, the chemotaxis, adhesion, phagocytosis, TNF-α secretion, β2-AR density, and mRNA expression were reduced while the cAMP content was increased in NE-treated groups than those in N-C group. The results indicated that NE strengthens the immunosuppression induced by AlCl3 in cultured rat peritoneal macrophages through the β2-AR/cAMP pathway.

Oxaliplatin neurotoxicity involves peroxisome alterations. PPARγ agonism as preventive pharmacological approach

The development of neuropathic syndromes is an important, dose limiting side effect of anticancer agents like platinum derivates, taxanes and vinca alkaloids. The causes of neurotoxicity are still unclear but the impairment of the oxidative equilibrium is strictly related to pain. Two intracellular organelles, mitochondria and peroxisomes cooperate to the maintaining of the redox cellular state. Whereas a relationship between chemotherapy-dependent mitochondrial alteration and neuropathy has been established, the role of peroxisome is poor explored. In order to study the mechanisms of oxaliplatin-induced neurotoxicity, peroxisomal involvement was evaluated in vitro and in vivo. In primary rat astrocyte cell culture, oxaliplatin (10 µM for 48 h or 1 µM for 5 days) increased the number of peroxisomes, nevertheless expression and functionality of catalase, the most important antioxidant defense enzyme in mammalian peroxisomes, were significantly reduced. Five day incubation with the selective Peroxisome Proliferator Activated Receptor-γ (PPAR-γ) antagonist G3335 (30 µM) induced a similar peroxisomal impairment suggesting a relationship between PPARγ signaling and oxaliplatin neurotoxicity. The PPARγ agonist rosiglitazone (10 µM) reduced the harmful effects induced both by G3335 and oxaliplatin. In vivo, in a rat model of oxaliplatin induced neuropathy, a repeated treatment with rosiglitazone (3 and 10 mg kg⁻¹ per os) significantly reduced neuropathic pain evoked by noxious (Paw pressure test) and non-noxious (Cold plate test) stimuli. The behavioral effect paralleled with the prevention of catalase impairment induced by oxaliplatin in dorsal root ganglia. In the spinal cord, catalase protection was showed by the lower rosiglitazone dosage without effect on the astrocyte density increase induced by oxaliplatin. Rosiglitazone did not alter the oxaliplatin-induced mortality of the human colon cancer cell line HT-29. These results highlight the role of peroxisomes in oxaliplatin-dependent nervous damage and suggest PPARγ stimulation as a candidate to counteract oxaliplatin neurotoxicity.

Postpartal immunometabolic gene network expression and function in blood neutrophils are altered in response to prepartal energy intake and postpartal intramammary inflammatory challenge

The effect of over-feeding energy prepartum on blood polymorphonuclear neutrophil (PMN) response remains unclear. Cows fed controlled (CON; 1.34Mcal/kg of dry matter) or excess energy (OVE; 1.62Mcal/kg dry matter) during the dry period (~45d before expected calving date) received an intramammary (IM) challenge with Escherichia coli lipopolysaccharide (LPS) during the postpartal period to determine the effects of IM LPS and prepartal diet on the expression of key genes associated with immunometabolic response in blood PMN. Feed intake and daily milk yield were recorded throughout the study period. At 7d in milk (DIM), all cows received LPS (200µg) into 1 rear mammary quarter. Blood PMN were isolated at 7, 14, and 30 DIM, as well as before (0h) and after (12h) IM LPS challenge for gene expression analysis using quantitative real time PCR. Phagocytosis capabilities in vitro were assessed at 7, 14, and 30 DIM. Data were analyzed using the MIXED procedure of SAS with repeated measures. No differences in feed intake and milk yield were observed between OVE- and CON-fed cows. As expected, IM LPS challenge altered the expression of genes associated with the immune response (e.g., 1.9- and 1.8-fold for SELL and TLR2, respectively), metabolism (e.g., 1.8- and -1.8-fold for LDHA and SLC2A1, respectively), and transcription (e.g., 1.1- and 1.7-fold for NCOR1 and PPARD, respectively). At 12h postchallenge, an upregulation of TLR2 (1.8-fold), HIF1A (1.9-fold), and NFKB1 (1.5-fold) was observed for OVE rather than CON. At 7 DIM, S100A9 tended (2.2-fold) to be upregulated for OVE rather than CON. At 14 DIM, OVE resulted in lower PMN phagocytosis and an upregulation of NCOR2 (1.6-fold) and RXRA (1.9-fold) compared with CON-fed cows. At 30 DIM, an upregulation of MPO (3.5-fold) and PLA2G4A (1.5-fold) and a tendency for RXRA (1.7-fold) was observed for OVE- rather than CON-fed cows. Our results suggest that IM LPS challenge altered gene expression associated with metabolism in PMN and that OVE impaired PMN phagocytosis and increased the expression of immunometabolic genes after IM LPS challenge and during the postpartal period. The current study provides new linkages among prepartal feed energy intake, metabolism, and immune response of blood PMN and risk of disease during early lactation.

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.

Functional Role of PPARs in Ruminants: Potential Targets for Fine-Tuning Metabolism during Growth and Lactation

Characterization and biological roles of the peroxisome proliferator-activated receptor (PPAR) isotypes are well known in monogastrics, but not in ruminants. However, a wealth of information has accumulated in little more than a decade on ruminant PPARs including isotype tissue distribution, response to synthetic and natural agonists, gene targets, and factors affecting their expression. Functional characterization demonstrated that, as in monogastrics, the PPAR isotypes control expression of genes involved in lipid metabolism, anti-inflammatory response, development, and growth. Contrary to mouse, however, the PPARγ gene network appears to controls milk fat synthesis in lactating ruminants. As in monogastrics, PPAR isotypes in ruminants are activated by long-chain fatty acids, therefore, making them ideal candidates for fine-tuning metabolism in this species via nutrients. In this regard, using information accumulated in ruminants and monogastrics, we propose a model of PPAR isotype-driven biological functions encompassing key tissues during the peripartal period in dairy cattle.

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.

Effect of conjugated linoleic acid on proliferation and cytokine expression of bovine peripheral blood mononuclear cells and splenocytes ex vivo

Twenty-five primiparous Holstein cows were divided into five experimental groups (five animals per group) by different feeding (control fat preparation [CON] or conjugated linoleic acid [CLA] supplement) and slaughtering times. The daily consumption of CLA was 6.0 g of the trans-10, cis-12 CLA-isomer and 5.7 g cis-9, trans-11 CLA isomer. An initial group (IG) was slaughtered one day post partum (pp) and the remaining 20 animals after 42 and 105 days pp, respectively. Blood for peripheral blood mononuclear cells (PBMC) separation was taken seven days ante partum and immediately before slaughter. The spleen was removed during dissection for isolation of splenocytes and samples for histopathological examination. Cell viability and Concanavalin A-stimulated proliferation was analysed by MTT and Alamar Blue assay. Basal expression of cytokines (interleukin [IL]-4, IL-10, IL-12, tumour necrosis factor alpha [TNF-alpha] and interferon gamma [IFN-gamma]) was measured by quantitative real time polymerase chain reaction (qRT-PCR) in unstimulated PMBC and splenocytes. With PBMC, stimulation indices increased from 1 day pp to 105 days pp with no differences between CLA and CON groups. With splenocytes, the stimulation index of the CLA group was lower compared to CON group 105 days pp. Baseline expression of cytokines was not effected by CLA feeding comparing similar time points. Also, no differences occurred in the expression of IL-4 in PBMC and IL-10 as well as TNF-alpha in both cell populations, when comparing the feeding groups separately with IG. IL-4 was more frequently expressed in CLA group 42 days pp in splenocytes. IFN-gamma expression was increased 105 days pp in CLA group in splenocytes and PBMC. IL-12 was higher expressed 105 days (PBMC) or 42 days pp (splenocytes) when compared to IG. There was no effect of CLA feeding or slaughter time on histopathology of the spleen. In conclusion, the present results demonstrate an inhibiting effect of CLA on the mitogen-induced activation of splenocytes.