Relevance of Dietary Lipids as Modulators of Immune Functions in Cells Infected with Listeria monocytogenes

Abstract

Nutritional status may have significant importance for the immune system, and particularly, unsaturated fatty acids may serve as modulators of immune functions. Clinical and epidemiological studies have demonstrated that fatty acids are involved in the reduction of the inflammatory processes that occur in diseases characterized by an overactivation of the immune system. At the same time, an increase in susceptibility to infection has also been reported. The importance of immune system modulation by dietary lipids in the presence of an intracellular bacterial pathogen, such as Listeria monocytogenes, was evaluated in the present study. BALB/c mice were divided into four groups which were each fed a low-fat (2.5% by weight) diet, an olive oil (OO; 20% by weight) diet, a fish oil (FO; 20% by weight) diet, or a hydrogenated coconut oil (HCO; 20% by weight) diet for 4 weeks. In each group, lymphocye proliferation was measured, and a reduction in the stimulation index was observed in the FO and HCO groups. Cytotoxicity exerted by L. monocytogenes was increased in the groups fed diets containing OO and FO after 6 h of incubation with the bacterium. An important increase in the production of reactive oxygen species was found in the groups fed the HCO diet after 12 h of incubation with L. monocytogenes. Finally, invasion and adhesion factors were not modified substantially by the action of dietary lipids, although these factors were reduced in cells from mice fed an FO diet. These results underline the importance of several dietary lipids as biological modulators of immune functions and their crucial role in the alteration of host natural resistance.According to present knowledge, many fatty acids contained in the diets of both animals and humans may exert a modulatory effect on immune functions (5, 12). It is generally assumed that the long-chain n-3 polyunsaturated fatty acids eicosapentaenoic acid (20:5[n-3]) and docosahexaenoic acid (DHA; 22: 6[n-3]), contained in fish oil, promote an immunosuppressive function. However, it has also been determined that monounsaturated fatty acids, such as oleic acid (derived from olive oil), rather than the other biological substances contained in this fat, cause an important reduction of numerous immune functions (21). Therefore, as a consequence of these events, many immunological functions, such as lymphocyte proliferation (15,24), cytokine production (15, 24), expression of cell surface molecules (20), natural killer (NK) cell activity (36), and phagocytosis (7), are modulated by the action of fatty acids. As a result, in recent years, numerous studies have indicated the potential role of several dietary lipids in the development of cancer or in the increase in resistance to tumors (9, 31). Similarly, unsaturated fatty acids have been applied in the resolution of inflammatory disorders associated with diseases characterized by an overreactivation of the immune system, such as rheumatoid arthritis (22, 23), psoriasis (2), and multiple sclerosis (1,18). However, despite the benefi...

Fatty acids and the immune system: from basic science to clinical applications

“…(Data are taken from Kew et al 2004. ) Listeria monocytogenes to adhere to or invade the cells in vitro (Puertollano et al 2002). Also, the same group investigated the effects of diets containing hydrogenated coconut oil, sunflower oil and olive oil on phagocytic activity in Balb/c mice and demonstrated that the olive oil diet enhanced phagocytic activity and production of IL-1 relative to the other groups (De Pablo et al 1998b).…”

Effects of protected fish oil in the diet of periparturient dairy goats on phenotypic variation in blood and milk leukocytes

“…Immunological changes that are associated with the metabolic and physical stresses of parturition increase in the weeks before calving and peak at parturition (Mallard et al, 1998;Mallard, 1999); -E-mail: valerio.bronzo@unimi.it however, data on the immune status of dairy goats in the peripartum period are limited (Azab et al, 1999;Agazzi et al, 2004). Previous research in animal models has identified several nutritional approaches that may modulate the production of key factors involved in the activation and regulation of innate and adaptive immunity (Calder, 1997;Puertollano et al, 2002;Lessard et al, 2004). Gershwin et al (1985) and Johnston (1988) observed that both cell-mediated immunity and humoural immunity are influenced by the amount and types of fat in the diet, while Calder and Grimble (2002) presented evidence that fatty acids (FAs) can act as second messengers or regulators of signal transduction molecules.…”

Assessment of Interleukin-12, Gamma Interferon, and Tumor Necrosis Factor Alpha Secretion in Sera from Mice Fed with Dietary Lipids during Different Stages ofListeria monocytogenesInfection

“…Despite this, several studies have reported that an excess intake of n-3 polyunsaturated fatty acids may cause undesirable effects in both humans and animals, because they are able to reduce host immune resistance against infectious microorganisms (1,11). Thus, numerous investigations have indicated that diets containing n-3 polyunsaturated fatty acids enhance susceptibility to infection by Listeria monocytogenes (8,13,23), Salmonella enterica serovar Typhimurium (7), Mycobacterium tuberculosis (21), or Pseudomonas aeruginosa (22), whereas other recent observations have reported that these diets increase immune resistance against Klebsiella pneumoniae (2,3,27), although these effects could not be demonstrated in infection with Streptococcus pneumoniae (27). Therefore, it is possible that the consequences derived from the reduction of immune resistance by n-3 polyunsaturated fatty acids may also depend on the type of microorganisms and their pathogenic mechanisms.…”