Changes in the immune functions and susceptibility to Listeria monocytogenes infection in mice fed dietary lipids

Growth and response to Escherichia coli lipopolysaccharide challenge in Lohmann LSL-Lite pullets when fed a source of omega-3 fatty acids and yeast bioactives from hatch through to 16 wk of age

Growth and response to Escherichia coli lipopolysaccharide (LPS) challenge in Lohmann LSL-Lite pullets when fed a source of omega-3 fatty acids (n-3 FA) and yeast bioactives (YB) from hatch through to 16 wk of age (woa) were investigated. Co-extruded full fat flaxseed and pulse mixture (FFF; 1:1 wt/wt) supplied n-3 FA and YB were yeast cell walls processed with β-1,3-glucan hydrolase. A total of 1,064-day-old pullets were placed in cages (19 birds/cage) and allocated to 7 diets (n = 8). The iso-caloric and iso-nitrogenous diets were control, control + 1, 3, or 5% FFF and + 0.025, 0.05, or 0.1% YB. The birds had ad libitum access to feed and water. Body weight (BW), feed intake, and lymphoid organs weight were recorded. At 15 woa, 2 pairs of pullets/cage received intravenous injection of either 1 mL of sterile saline without or with 8 mg LPS/kg BW. Injected pullets were bled, monitored for BW and cloaca temperature at time points within 168 h. Birds fed 1% FFF were heavier (P < 0.04) than birds fed other diets at 16 woa with FFF and YB exhibiting non-linear responses. Control birds had heavier (P = 0.02) thymus at 4 woa. Spleen weight increased quadratically (P < 0.05) in response to FFF at 8 and YB at 16 woa. The LPS increased cloaca temperature and altered concentration of several plasma metabolites (P < 0.05). The interaction (P < 0.05) between LPS and diet was such that control birds exhibited lower creatine kinase (CK) upon challenge with LPS relative to birds fed other diets. The LPS birds fed 1% FFF and 0.05% YB showed higher plasma albumin than non-LPS cohorts. Non-LPS birds fed control, 1 and 3% FFF had higher plasma K than LPS cohorts. In general, FFF and YB exhibited linear and quadratic effects (P < 0.05) on select plasma metabolites. In conclusion, dietary provision of n-3 FA and YB influenced pullet BW at sexual maturity, development of lymphoid organs and modulated some plasma metabolites in response to LPS.

Dietary arachidonate in milk replacer triggers dual benefits of PGE2 signaling in LPS-challenged piglet alveolar macrophages

Background

Respiratory infections challenge the swine industry, despite common medicinal practices. The dual signaling nature of PGE₂ (supporting both inflammation and resolution) makes it a potent regulator of immune cell function. Therefore, the use of dietary long chain n-6 PUFA to enhance PGE₂ effects merits investigation.

Methods

Day-old pigs (n = 60) were allotted to one of three dietary groups for 21 d (n = 20/diet), and received either a control diet (CON, arachidonate = 0.5% of total fatty acids), an arachidonate (ARA)-enriched diet (LC n-6, ARA = 2.2%), or an eicosapentaenoic (EPA)-enriched diet (LC n-3, EPA = 3.0%). Alveolar macrophages and lung parenchymal tissue were collected for fatty acid analysis. Isolated alveolar macrophages were stimulated with LPS in situ for 24 h, and mRNA was isolated to assess markers associated with inflammation and eicosanoid production. Culture media were collected to assess PGE₂ secretion. Oxidative burst in macrophages was measured by: 1) oxygen consumption and extracellular acidification (via Seahorse), 2) cytoplasmic oxidation and 3) nitric oxide production following 4, 18, and 24 h of LPS stimulation.

Results

Concentration of ARA (% of fatty acids, w/w) in macrophages from pigs fed LC n-6 was 86% higher than CON and 18% lower in pigs fed LC n-3 (P < 0.01). Following LPS stimulation, abundance of COX-2 and TNF-α mRNA (P <  0.0001), and PGE₂ secretion (P < 0. 01) were higher in LC n-6 PAM vs. CON. However, ALOX5 abundance was 1.6-fold lower than CON. Macrophages from CON and LC n-6 groups were 4-fold higher in ALOX12/15 abundance (P < 0.0001) compared to LC n-3. Oxygen consumption and extracellular acidification rates increased over 4 h following LPS stimulation (P < 0.05) regardless of treatment. Similarly, increases in cytoplasmic oxidation (P < 0.001) and nitric oxide production (P <  0.002) were observed after 18 h of LPS stimulation but were unaffected by diet.

Conclusions

We infer that enriching diets with arachidonic acid may be an effective means to enhance a stronger innate immunologic response to respiratory challenges in neonatal pigs. However, further work is needed to examine long-term safety, clinical efficacy and economic viability.

Electronic supplementary material

The online version of this article (10.1186/s40104-019-0321-1) contains supplementary material, which is available to authorized users.

Dietary fatty acids and immune response to food-borne bacterial infections

Functional innate and acquired immune responses are required to protect the host from pathogenic bacterial infections. Modulation of host immune functions may have beneficial or deleterious effects on disease outcome. Different types of dietary fatty acids have been shown to have variable effects on bacterial clearance and disease outcome through suppression or activation of immune responses. Therefore, we have chosen to review research across experimental models and food sources on the effects of commonly consumed fatty acids on the most common food-borne pathogens, including Salmonella sp., Campylobacter sp., Shiga toxin-producing Escherichia coli, Shigella sp., Listeria monocytogenes, and Staphylococcus aureus. Altogether, the compilation of literature suggests that no single fatty acid is an answer for protection from all food-borne pathogens, and further research is necessary to determine the best approach to improve disease outcomes.

Fatty Acid use in Diving Mammals: More than Merely Fuel

Diving mammals, are under extreme pressure to conserve oxygen as well as produce adequate energy through aerobic pathways during breath-hold diving. Typically a major source of energy, lipids participate in structural and regulatory roles and have an important influence on the physiological functions of an organism. At the stoichiometric level, the metabolism of polyunsaturated fatty acids (PUFAs) utilizes less oxygen than metabolizing either monounsaturated fatty acids or saturated fatty acids (SFAs) and yields fewer ATP per same length fatty acid. However, there is evidence that indicates the cellular metabolic rate is directly correlated to the lipid composition of the membranes such that the greater the PUFA concentration in the membranes the greater the metabolic rate. These findings appear to be incompatible with diving mammals that ingest and metabolize high levels of unsaturated fatty acids while relying on stored oxygen. Growing evidence from birds to mammals including recent evidence in Weddell seals also indicates that at the whole animal level the utilization of PUFAs to fuel their metabolism actually conserves oxygen. In this paper, we make an initial attempt to ascertain the beneficial adaptations or limitations of lipids constituents and potential trade-offs in diving mammals. We discuss how changes in Antarctic climate are predicted to have numerous different environmental effects; such potential shifts in the availability of certain prey species or even changes in the lipid composition (increased SFA) of numerous fish species with increasing water temperatures and how this may impact the diving ability of Weddell seals.

Acquired resistance to Listeria monocytogenes during a secondary infection in a murine model fed dietary lipids

OBJECTIVE

The ω-3 polyunsaturated fatty acids can suppress immune system functions. This property may cause adverse effects by impairing host resistance to infection. The present study focused on estimating the impact of different dietary lipids on the immune system of mice after a secondary infection with Listeria monocytogenes.

METHODS

BALB/c mice were divided into five dietary groups of olive oil, fish oil, sunflower oil, high-oleic sunflower oil, or low fat that was administered for 8 wk. The mice were immunized with 10(3) colony-forming units. Thirty-eight days later, each mouse was challenged with 10(4) colony-forming units. Mice survival and bacterial clearance from livers and spleens were determined. In addition, cytokine, chemokine, and adhesion molecule productions were quantified from the sera.

RESULTS

Survival percentage in mice fed a fish oil diet was 100% and bacterial numbers from spleen were decreased at 72 h. Interleukin-12, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 productions were decreased. Levels of tumor necrosis factor-α and interferon-γ were increased, whereas macrophage inflammatory protein-1α (MIP-1α) production was unaltered.

CONCLUSION

Immune defense in mice fed a fish oil diet was improved after secondary exposure, acquiring an adequate resistance. This result could be attributable to an increase of a T-helper type 1 response.

Fish oil-fed mice have impaired resistance to influenza infection

Dietary fish oils, rich in (n-3) PUFA, including eicosapentaenoic acid and docosahexaenoic acid, have been shown to have antiinflammatory properties. Although the antiinflammatory properties of fish oil may be beneficial during a chronic inflammatory illness, the same antiinflammatory properties can suppress the inflammatory responses necessary to combat acute viral infection. Given that (n-3) fatty acid-rich fish oil supplementation is on the rise and with the increasing threat of an influenza pandemic, we tested the effect of fish oil feeding for 2 wk on the immune response to influenza virus infection. Male C57BL/6 mice fed either a menhaden fish oil/corn oil diet (4 g fish oil:1 g corn oil, wt:wt at 5 g/100 g diet) or a control corn oil diet were infected with influenza A/PuertoRico/8/34 and analyzed for lung pathology and immune function. Although fish oil-fed mice had lower lung inflammation compared with controls, fish oil feeding also resulted in a 40% higher mortality rate, a 70% higher lung viral load at d 7 post infection, and a prolonged recovery period following infection. Although splenic natural killer (NK) cell activity was suppressed in fish oil-fed mice, lung NK activity was not affected. Additionally, lungs of infected fish oil-fed mice had significantly fewer CD8+ T cells and decreased mRNA expression of macrophage inflammatory protein-1-alpha, tumor necrosis factor-alpha, and interleukin-6. These results suggest that the antiinflammatory properties of fish oil feeding can alter the immune response to influenza infection, resulting in increased morbidity and mortality.

Multiple factors interact to produce responses resembling spectrum of human disease in Campylobacter jejuni infected C57BL/6 IL-10-/- mice

BACKGROUND

Campylobacter jejuni infection produces a spectrum of clinical presentations in humans--including asymptomatic carriage, watery diarrhea, and bloody diarrhea--and has been epidemiologically associated with subsequent autoimmune neuropathies. This microorganism is genetically variable and possesses genetic mechanisms that may contribute to variability in nature. However, relationships between genetic variation in the pathogen and variation in disease manifestation in the host are not understood. We took a comparative experimental approach to explore differences among different C. jejuni strains and studied the effect of diet on disease manifestation in an interleukin-10 deficient mouse model.

RESULTS

In the comparative study, C57BL/6 interleukin-10-/- mice were infected with seven genetically distinct C. jejuni strains. Four strains colonized the mice and caused disease; one colonized with no disease; two did not colonize. A DNA:DNA microarray comparison of the strain that colonized mice without disease to C. jejuni 11168 that caused disease revealed that putative virulence determinants, including loci encoding surface structures known to be involved in C. jejuni pathogenesis, differed from or were absent in the strain that did not cause disease. In the experimental study, the five colonizing strains were passaged four times in mice. For three strains, serial passage produced increased incidence and degree of pathology and decreased time to develop pathology; disease shifted from watery to bloody diarrhea. Mice kept on an ~6% fat diet or switched from an approximately 12% fat diet to an approximately 6% fat diet just before infection with a non-adapted strain also exhibited increased incidence and severity of disease and decreased time to develop disease, although the effects of diet were only statistically significant in one experiment.

CONCLUSION

C. jejuni strain genetic background and adaptation of the strain to the host by serial passage contribute to differences in disease manifestations of C. jejuni infection in C57BL/6 IL-10-/- mice; differences in environmental factors such as diet may also affect disease manifestation. These results in mice reflect the spectrum of clinical presentations of C. jejuni gastroenteritis in humans and contribute to usefulness of the model in studying human disease.

Examination of host immune resistance against Listeria monocytogenes infection in cyclophosphamide-treated mice after dietary lipid administration

BACKGROUND & AIMS

Despite the beneficial effects in the resolution of inflammatory disorders due to their immunosuppressive properties, n-3 polyunsaturated fatty acids are associated with a reduction of immune resistance to some microorganisms. Here, we examine the influence of different dietary lipids on host immune resistance against Listeria monocytogenes in mice treated with cyclophosphamide (CPA).

METHODS

Balb/c mice were fed one of four diets, which contained either olive oil (OO), fish oil (FO), hydrogenated coconut oil (HCO) or low fat (LF) for 4 weeks. Subsequently, mice were treated with CPA or PBS, prior to L. monocytogenes infection. Splenocyte proliferation, survival analysis, counts of viable bacteria from spleens and livers, and measurement of pro-inflammatory cytokine levels were determined.

RESULTS

The FO-rich diet reduced survival, particularly in CPA-treated mice. CPA was responsible for a significant increase of viable bacteria recovery from spleens and livers within each group fed high fat diets, which was aggravated in mice fed an FO diet. In addition, a significant increase of both TNF-alpha and IL-12p70 levels was detected in this group. These results may acquire a crucial relevance in clinical nutrition, particularly when FO diets are administered to immunocompromised patients.

CONCLUSIONS

The mechanism(s) that impair(s) the elimination of L. monocytogenes could be associated with a low mitogen-stimulated splenocyte proliferation, and with an alteration of pro-inflammatory cytokine production. The application of the neutropenic agent CPA moderately aggravates the immunosuppressive state mainly in FO-fed animals.

Significance of olive oil in the host immune resistance to infection

The effects exerted by polyunsaturated fatty acids (PUFA) on immune system functions have been investigated in recent years. These studies have reported the important role thatn-3 PUFA play in the diminution of incidence and severity of inflammatory disorders. Nevertheless, less attention has been paid to the action of monounsaturated fatty acids (MUFA) upon the immune system. The administration of a diet containing a high amount of olive oil in experimental animals produces a suppression of lymphocyte proliferation, an inhibition of cytokine production and a reduction in natural killer (NK) cell activity. Despite these alterations in immune functions, it has been reported that olive oil-rich diets are not as immunosuppressive as fish oil diets. An important aspect in immunonutrition is focused on the relationship between fats, the immune system and host resistance to infection, particularly when these nutrients are supplied to patients at risk of sepsis. Different studies have determined that olive oil-rich diets do not impair the host resistance to infection. Therefore, olive oil constitutes a suitable fat that may be applied in clinical nutrition and administered to critically ill patients. In the present review, we summarize the current knowledge on olive oil and immune system functions, the biological consequences derived from the administration of diets containing olive oil and the impact of olive oil on immune defence.

Effect of dietary fish oil supplementation on cellular adhesion molecule expression and tissue myeloperoxidase activity in diabetic mice with sepsis

This study investigated the effect ofn-3 fatty acids on adhesion molecules and tissue myeloperoxidase (MPO) activity in diabetic mice with sepsis. Diabetes was induced by a streptozotocin injection. Mice with blood glucose levels exceeding 2000 mg/l were considered diabetic. Diabetic mice were assigned to two groups with a medium-fat (10 %, w/w) diet either provided by soyabean oil (SO,n30) or fish oil (FO,n30).n-3 fatty acids provided 4·3 % of the total energy and then-3/n-6 fatty acid ratio was 1:2 in the FO diet. After feeding the respective diet for 3 weeks, all mice had sepsis induced by caecal ligation and puncture (CLP) and were killed at 0, 6 or 24 h after CLP, with ten mice at each time-point. The result showed that compared with the SO group, FO group had lower PGE2and TNF-α levels in peritoneal lavage fluid after CLP. Lymphocyte CD11a/CD18 expressions were higher at 6 h, whereas the percentage was lower at 24 h in the SO group than in the FO group. Neutrophil CD11b/CD18 expressions were significantly higher in the SO group than in the FO group at 0 h. The FO group had lower organ MPO activities at various time-points after CLP when compared with those of the SO group. The present findings suggest that compared with the diabetic mice fed SO, a low-dosen-3 fatty acid supplementation may attenuate leucocyte adhesion and infiltration into tissues in diabetic mice complicated with sepsis.

Effects of ω-3 fatty acids on leukocyte Th1/Th2 cytokine and integrin expression in rats with gut-derived sepsis

OBJECTIVES

This study examined the effect of fish oil (FO)-enriched diets before and/or omega-3 fatty acid-containing total parenteral nutrition (TPN) after sepsis on the distribution of the T-lymphocyte subpopulation, intracellular cytokine, and intestinal immunity in rats with gut-derived sepsis.

METHODS

Rats were assigned to a control or one of four experimental groups. The control group and groups 1 and 2 were fed a semipurified diet, and groups 3 and 4 received FO instead of 20% soybean oil. After feeding the diets for 10 d, sepsis was induced by cecal ligation and puncture (CLP) in the experimental groups, whereas a sham operation was performed in the control group. TPN was maintained for 3 d after the CLP or sham operation. The control group and groups 1 and 3 were infused with conventional TPN, whereas the TPN solution used for groups 2 and 4 were supplemented with FO. All rats were sacrificed 3 d after the operation to examine their immune responses.

RESULTS

Plasma and intestinal immunoglobin A levels were higher in the FO-supplemented groups than in the control group and group 1. Lymphocyte interferon-gamma expression in groups 3 and 4 was significantly lower, whereas interleukin-4 expression was higher than those of the control group and groups 1 and 2. The splenocyte CD4 percentage in groups 3 and 4 and the CD4/CD8 ratio in group 4 were significantly higher than those in group 1.

CONCLUSION

These findings suggest that FO administration before and/or after CLP are not immunosuppressive. FO-enriched diets before or before and after CLP resulted in a T-helper type 2 response and enhanced immunoglobulin A secretion. In addition, the splenocyte CD4 levels and CD4/CD8 ratio were maintained in rats with gut-derived sepsis.

Effects of acute or chronic omega-3 and omega-6 polyunsaturated fatty acid treatment on behavioral, neuroendocrine and cytokine changes elicited by exogenous interleukin-1beta challenge

Chronic omega-3 or omega-6 polyunsaturated fatty acid (n-3; n-6 respectively) treatment attenuated human interleukin-1beta (hIL-1beta; 5.0 microg/kg)-elicited rise of circulating ACTH levels and attenuated the sickness behavior and locomotor suppression elicited by the cytokine. Furthermore, hIL-1beta markedly elevated circulating levels of plasma IL-6, an effect attenuated by n-3, but not n-6 treatment. Such protective effects were not evident upon short-term (3 day) n-3 exposure. These results demonstrate that long-term administration of either n-3 or n-6 confers protection against several neuroendocrinological, immunological and behavioral actions of hIL-1beta challenge, although in general the effects of n-3 were more pronounced.

Assessment of interleukin-12, gamma interferon, and tumor necrosis factor alpha secretion in sera from mice fed with dietary lipids during different stages of Listeria monocytogenes infection

Recent experimental observations have determined that long-chain n-3 polyunsaturated fatty acids suppress immune functions and are involved in the reduction of infectious disease resistance. BALB/c mice were fed for 4 weeks with one of four diets containing either olive oil (OO), fish oil (FO), hydrogenated coconut oil, or a low fat level. Interleukin-12p70 (IL-12p70), gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha) production in the sera of mice fed these diets and challenged with Listeria monocytogenes were determined by enzyme-linked immunosorbent assay. In addition, bacterial counts from spleens of mice were carried out at 24, 72, or 96 h of infection. Here, we quantified an initial diminution of production of both IL-12p70 and IFN-gamma, which appear to play an important role in the reduction of host resistance to L. monocytogenes infection. In addition, an efficient elimination of L. monocytogenes was observed in spleens of mice fed a diet containing OO at 96 h of infection, despite reductions in IL-12p70 and TNF-alpha production, suggesting an improvement of immune resistance. Overall, our results indicate that the initial reduction of both IL-12 and IFN-gamma production before L. monocytogenes infection represents the most relevant event that corroborates the impairment of immune resistance by n-3 polyunsaturated fatty acids during the different stages of infection. However, we speculate that the modulation of other cytokines must be also involved in this response, because the alteration of cytokine production in mice fed an FO diet in a late phase of L. monocytogenes infection was similar to that in mice fed OO, whereas the ability to eliminate this bacterium from the spleen was improved in the latter group.