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

Narrative Review of n-3 Polyunsaturated Fatty Acid Supplementation upon Immune Functions, Resolution Molecules and Lipid Peroxidation

Fish oil supplementation is commonplace in human nutrition and is being used in both enteral and parenteral formulations during the treatment of patients with a large variety of diseases and immune status. The biological effects of fish oil are believed to result from their content of n-3 polyunsaturated fatty acids (PUFA), particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). These fatty acids are known to have numerous effects upon immune functions and are described as immunomodulatory. However, immunomodulatory is a nondescript term that encompasses immunostimulation and immunosuppression. The primary goal of this review is to better describe the immune effects of n-3 PUFA as they relate to immunostimulatory vs. immunosuppressive effects. One mechanism proposed for the immune effects of n-3 PUFA relates to the production of specialized pro-resolving mediators (SPMs). A second goal of this review is to evaluate the effects of n-3 PUFA supplementation upon production of SPMs. Although n-3 PUFA are stated to possess anti-oxidative properties, these molecules are highly oxidizable due to multiple double bonds and may increase oxidative stress. Thus, the third goal of this review is to evaluate the effects of n-3 PUFA upon lipid oxidation. We conclude, based upon current scientific evidence, that n-3 PUFA suppress inflammatory responses and most cellular immune responses such as chemotaxis, transmigration, antigen presentation, and lymphocyte functions and should be considered immunosuppressive. n-3 PUFA induced production of resolution molecules is inconsistent with many resolution molecules failing to respond to n-3 PUFA supplementation. n-3 PUFA supplementation is associated with increased lipid peroxidation in most studies. Vitamin E co-administration is unreliable for prevention of the lipid peroxidation. These effects should be considered when administering n-3 PUFA to patients that may be immunosuppressed or under high oxidative stress due to illness or other treatments.

Fish oil supplementation reduces maternal defensive inflammation and predicts a gut bacteriome with reduced immune priming capacity in infants

Habitual supplementation of fish oil is thought to provide benefits to the developing infant; however, the effects on infant microbial establishment and immune development are unknown. A 6-month observational cohort study was conducted where 47 out of 91 women self-administered dietary fish oil during breastfeeding. Infant stool and mothers' breast milk were collected each month over 6 months. Gas chromatography was used to quantify breast milk fatty acids and high-throughput sequencing was used to assess the infant fecal microbiota. Immune markers and parent-reported questionnaires were used to assess infant immunity and health up to 2 years. Our results reveal that fish oil supplementation decreased secretory immunoglobulin A and increased IL-10 production in lactating women along with increased breast milk eicosapentaenoic acid, and this corresponded to increased abundances of fecal Bifidobacterium and Lactobacillus spp. in their infants. Docosahexaenoic acid levels in breast milk aligned with decreases in infant gut bacterial richness and the predicted bacterial phenotypes suggested that fish oil lowers commensal traits involved in pathogen colonization resistance. Despite this, there were no differences in sickness incidence in toddlers. This study revealed that fish oil associates with decreases in breast milk defensive inflammatory responses and corresponds with infant fecal microbiota with anti-inflammatory potential.

Effects of polysaccharides from wild morels on immune response and gut microbiota composition in non-treated and cyclophosphamide-treated mice

Polysaccharides isolated from mushrooms have been identified as potential prebiotics that could impact gut microbiota. In this study, a water-soluble polysaccharide (MP) extracted from wild morels was evaluated for its effects on the gut microbiota of non-treated and cyclophosphamide (CP)-treated mice. The results showed that MP restored the spleen weight and increased the counts of white blood cells and lymphocytes in the peripheral blood and spleen of the CP-treated mice. Mice treated with MP exhibited increased levels of short-chain fatty acid (SCFA)-producing bacteria, especially Lachnospiraceae, compared to normal mice, and increased levels of Bacteroidetes and SCFA-producing bacteria, especially Ruminococcaceae, compared to the CP-treated mice. Moreover, MP treatment increased the production of valeric acid and decreased the production of acetic acid in the non-treated mice and increased the production of acetic acid, propionic acid, butyric acid, and valeric acid in the CP-treated mice. These results show that MP is potentially good for health.

Synergistic PA and HA mutations confer mouse adaptation of a contemporary A/H3N2 influenza virus

The mouse is the most widely used animal model for influenza virus research. However, the susceptibility of mice to seasonal influenza virus depends on the strain of mouse and on the strain of the influenza virus. Seasonal A/H3N2 influenza viruses do not replicate well in mice and therefore they need to be adapted to this animal model. In this study, we generated a mouse-adapted A/H3N2 virus (A/Switzerland/9715293/2013 [MA-H3N2]) by serial passaging in mouse lungs that exhibited greater virulence compared to the wild-type virus (P0-H3N2). Seven mutations were found in the genome of MA-H3N2: PA(K615E), NP(G384R), NA(G320E) and HA(N122D, N144E, N246K, and A304T). Using reverse genetics, two synergistically acting genes were found as determinants of the pathogenicity in mice. First, the HA substitutions were shown to enhanced viral replication in vitro and, second, the PA-K615E substitution increased polymerase activity, although did not alter virus replication in vitro or in mice. Notably, single mutations had only limited effects on virulence in vitro. In conclusion, a co-contribution of HA and PA mutations resulted in a lethal mouse model of seasonal A/H3N2 virus. Such adapted virus is an excellent tool for evaluation of novel drugs or vaccines and for study of influenza pathogenesis.

Reducing the burden of obesity-associated cancers with anti-inflammatory long-chain omega-3 polyunsaturated fatty acids

Today's world population has an unprecedented risk of dying from the consequences of being overweight and obese. Chronic diseases such as cardiovascular disease, type 2 diabetes, and cancer are often accelerated because of excessive adiposity. Various biological mechanisms are implicated in the obesity-cancer link, particularly local and systemic inflammation as well as altered growth factor signaling pathways. In order to combat obesity-induced inflammation and the resulting increases in cancer risk and progression, the identification of safe and effective mechanism-based interventions is imperative. Notably, long chain omega-3 polyunsaturated fatty acids (PUFAs) modulate the secretion of pro-inflammatory cytokines, prostaglandins and other inflammatory mediators, restore insulin sensitivity, and can prevent or delay tumorigenesis. Delineating the precise mechanisms by which omega-3 PUFAs suppress obesity-induced inflammation will help identify promising key mechanistic targets and intervention strategies to break the obesity-cancer link.

Immuno-enhancement effects of ethanol extract from Cyrtomium macrophyllum (Makino) Tagawa on cyclophosphamide-induced immunosuppression in BALB/c mice

ETHNOPHARMACOLOGICAL RELEVANCE

Cyrtomium macrophyllum (Makino) Tagawa has been traditionally used as a herbal medicine for the treatment of various infectious diseases such as tapeworm infestation, colds, and viral diseases. However, no systematic study of the immunity of Cyrtomium macrophyllum ethanol extracts (CM) has yet been reported. The present work evaluates these traits.

MATERIALS AND METHODS

120 male BALB/c mice were divided into 6 groups of 20 mice each: (1) normal group (sterile physiological saline), which served as a blank control; (2) model group (Cyclophosphamide, CY) group (sterile physiological saline), which served as a negative control; (3) low-dose CM (50 mg/kg BW); (4) intermediate-dose CM (100 mg/kg BW); (5) high-dose CM (200 mg/kg BW); (6) CM group (200 mg/kg BW). CY (0.2 ml) was administered via intraperitoneal injection. The other regimens were administered via gavage in 0.2 ml solution. Phytochemical of CM was characterized by HPLC-LTQ-Orbitrap. The acute toxicity effect of the ethanol extract of Cyrtomium macrophyllum was also investigated.

RESULTS

The spleen and thymus indices of mice receiving low, intermediate, and high doses of CM recovered more quickly than those of CY mice, and they did so in a dose-dependent manner. These mice also showed higher T cell and B cell proliferation responses and macrophage function than those of CY mice, and their serum levels of interleukin-6 and interferon-γ had become normal. In acute toxicity test, CM exhibited no mortality and behavioral changes in mice. Quantitative phytochemical analysis showed flavonoids, polyphenols, and tannins to be the major compounds present in the extract, at 27.64%, 30.87%, and 11.22%, respectively. We found that 16 compounds were characterized by the interpretation of their mass spectra obtained by the MS/MS.

CONCLUSION

The current study demonstrates that Cyrtomium macrophyllum ethanol extract improved immune function in CY-treated mice.

The design of propolis flavone microemulsion and its effect on enhancing the immunity and antioxidant activity in mice

The objective of the present study was to formulate a microemulsion system for improving the activity of propolis flavone (PF). Pseudo-ternary phase diagrams were constructed to evaluate the existence area of PF microemulsion (PFM). The formulation was characterized by particle size, zeta potential, morphology and stability. The results showed that the optimal PFM formulation consists of 5.3% ethyl acetate, 14% RH-40, 7% ethanol and 73.7% water (w/w), with a solubility of PF up to 3.0 mg mL(-1). The immune-enhancing and antioxidant activity of PFM in vitro and in vivo were performed. The results showed that PFM could significantly promote the splenocyte proliferation and the secretion of IL-2 and IFN-γ in vitro. In vivo, PFM at high and medium doses was able to significantly increase the thymus and spleen indices, enhance splenocyte activity and improve the contents of IgG and IgM in serum, it could also improve the antioxidant activity, significantly increase the levels of superoxidase dismutase and glutathione peroxidase, and decrease the malondialdehyde levels compared with PF. These results indicated that microemulsion could be used as an effective formulation for enhancing the activity of PF. Therefore, microemulsion would be expected to exploit into a new-type preparation of PF.

Immunomodulation by dietary long chain omega-3 fatty acids and the potential for adverse health outcomes

Recommendations to consume fish for prevention of cardiovascular disease (CVD), along with the U.S. Food and Drug Administration-approved generally recognized as safe (GRAS) status for long chain omega-3 fatty acids, may have had the unanticipated consequence of encouraging long-chain omega-3 (ω-3) fatty acid [(eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] supplementation and fortification practices. While there is evidence supporting a protective role for EPA/DHA supplementation in reducing sudden cardiac events, the safety and efficacy of supplementation with LCω-3PUFA in the context of other disease outcomes is unclear. Recent studies of bacterial, viral, and fungal infections in animal models of infectious disease demonstrate that LCω-3PUFA intake dampens immunity and alters pathogen clearance and can result in reduced survival. The same physiological properties of EPA/DHA that are responsible for the amelioration of inflammation associated with chronic cardiovascular pathology or autoimmune states, may impair pathogen clearance during acute infections by decreasing host resistance or interfere with tumor surveillance resulting in adverse health outcomes. Recent observations that high serum LCω-3PUFA levels are associated with higher risk of prostate cancer and atrial fibrillation raise concern for adverse outcomes. Given the widespread use of supplements and fortification of common food items with LCω-3PUFA, this review focuses on the immunomodulatory effects of the dietary LCω-3PUFAs, EPA and DHA, the mechanistic basis for potential negative health outcomes, and calls for biomarker development and validation as rational first steps towards setting recommended dietary intake levels.

Microemulsion can improve the immune-enhancing activity of propolis flavonoid on immunosuppression and immune response

The objective of the present study was to investigate whether the immune-enhancing activity of propolis flavone (PF) could be improved after PF was made into PF microemulsion (PFM). Two experiments were carried out. In immunosuppression experiment, the immune-enhancing effect of PFM in immunosuppressive chickens was performed. The results showed that PFM at high and medium doses was able to overcome the CTX-induced immunosuppression, significantly increases the immune organ indexes, enhances lymphocyte proliferation and improves the concentrations of IL-2 and IL-6 in serum when compared with PF. In immune response experiment, the adjuvant effect of PFM at three doses and PF were compared on chickens which were immunized intramuscularly with Avian Influenza Recombinant Newcastle Disease Virus bivalent Vaccine. The results showed that PFM at high and medium doses could significantly promote lymphocyte proliferation, enhances antibody titer and the concentrations of IgG and IgM, and its efficacy were significantly better than PF at most time points. These results indicated that PFM could significantly improve the immune-enhancing activity and adjuvanticity of PF, and its high and medium doses possessed the best efficacy. Therefore, the microemulsion could be used as an effective formulation for enhancing the bioavailability of PF.

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.

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.

Evaluation on the pathogenicity of Erysipelothrix tonsillarum for pigs by immunosuppression with cyclophosphamide or dexamethasone

The pathogenicity of Erysipelothrix tonsillarum was evaluated in pigs immunosuppressed with cyclophosphamide (CY) or dexamethasone (DM). Animals were treated with 15 mg/kg CY (n=8, five injections), 1 mg/kg DM (n=8, nine injections) or left untreated (n=8). On the fifth day after the beginning of drug treatments, swine were inoculated with one of two E. tonsillarum serovar 7 strains (approximately 10(6) CFU per pig). In the CY-treated group, both circulating neutrophil and lymphocyte counts decreased, whereas in the DM-treated group, lymphocyte counts decreased but neutrophil counts increased. During the observation period, none of the CY- or DM-treated pigs developed clinical signs or gross lesions, as well as non-treated pigs. Growth agglutination antibody titres in all pigs remained unchanged. Our findings indicate that E. tonsillarum strains are avirulent for swine, regardless of immune status.