Anti-inflammatory Effects of Dietary Polyunsaturated Fatty Acids (Research Paper Sample)

Anti-inflammatory Effects of Dietary Polyunsaturated Fatty Acids

1 Abstract
Normal hosts respond to infections and injuries though inflammation. The human monocyte/macrophage cell lines (MM6) release a number of cytokines related to inflammation (IL6, TNF alpha). Chronic inflammation can lead to a variety of diseases, including heart disease, diabetes and cancer. These chronic diseases are characterized by the production of inflammatory cytokines, arachidonic acid-derived eicosanoids, other inflammatory agents as well as adhesion molecules. Cytokine release can be upregulated by stimulation with lipopolysaccharide (LPS) or Interferon gamma (IFN) to mimic inflammatory conditions. At sufficiently high intakes, long chain n-3 polyunsaturated fatty acids (PUFAs), such as those present in fish oils, lower the rate of production of inflammatory eicosanoids such as cytokines. N-3 polyunsaturated fats also lower the reactive oxygen species as well as the expression of adhesion molecules. Long chain n-3 polyunsaturated fatty acids also produce resolvins, a family of anti-inflammatory mediators. N-3 polyunsaturated fatty acids have the potential to be effective anti-inflammatory drugs. As a result, they could be used to treat a number of acute and chronic inflammatory conditions. In certain cases (e.g., rheumatoid arthritis), evidence of their clinical benefit is robust, while in others, it is not (eg, in inflammatory bowel diseases and asthma). To assess the therapeutic potential of long-chain n3 PUFAs in inflammatory disorders, more, better-designed, and larger trials are needed. This study sought to identify whether DHA&EPA PUFA’s can attenuate inflammatory cytokine response.
Key Words: DHA, EPA, PUFAs, Inflammation, macrophage, cytokine, N-3 Polyunsaturated fatty acids, chronic inflammation, Viability assay, ELISA test.
2 Introduction
Inflammation is the body’s initial response to an injury or infection, characterized by redness, pain and swelling (Oishi, 2018). Inflammations tend to occur when the rate of flow of blood increases, consequently raising the permeability of blood capillaries, which then allows for the passage of cytokines across the endothelial wall (Calder, 2015). There has been growing concerns over the recently discovered role of dietary polyunsaturated fatty acids in human and animal nutrition. Diet has an effect on the development and optimal functioning of the immune system. These dietary fatty acids have a crucial role to play on the health and competence of the immune systems of various organisms (Moloudizargari et al., 2018). Dietary fats can modulate the composition of the fatty acids of the immune cells, and the outcomes in the composition can affect the reactivity and functioning of immune cells within a short spell. Although there is a high likelihood of the inflammation affecting different body parts, a common characteristic that applies across the board is the excessive production of inflammatory mediators such as cytokines and eicosanoids.
Inflammation initiates the immunologic process of eliminating the invading pathogens and repairing the affected and damaged tissue. These responses tend to be controlled, and the movement of cells into the inflammation tends to be induced by an up-regulation of adhesion molecules such as ICAM-1 and VCAM-1 (Calder, 2017). Granulocytes are the earliest cells which appear on inflamed areas, followed by macrophages and monocytes (Yu et al., 2016). The body uses the granulocytes, macrophages and monocytes to repair damaged tissues and clear our cellular debris (Amanzada et al., 2014). This activity depends on bacterial endotoxins such as lipopolysaccharides, which serve as triggers. Lipopolysaccharides make up the walls of the Gram-negative bacteria, which have the ability of activating monocytes and macrophages, and inducing them to form cytokines in the process.
Monocytes and macrophages also produced by the cytokines to regulate the response of the body to injuries and infections (Mazgaeen and Gurung, 2020). This close relationship is what makes inflammation and inflammatory responses to be a part of the immune response (Stiles, 2020). However, whereas inflammation is the natural and only response a body makes towards an infection, there is a potential of excessive damage to the host’s tissue, further increasing the risk of disease. In most cases, the uncontrolled inflammatory responses are because of an overexpression of endothelial and leukocyte adhesion molecules. High concentration of adhesive molecules such as IL-1β, TNF-α and IL-6 raises the risks of destruction and has been associated with pathological responses that occur in chronic inflammatory infections such as arthritis (Nilsson, 2021). An overproduction of these adhesive molecules can cause loss of bone mass, which may account for changes in body composition and loss of tissues associated with illnesses such as cancer. Inflammation is also closely associated with inflammatory diseases such as cardiovascular diseases and other diseases associated with aging (Mozos et al., 2017). Furthermore, the recent discovery that adipose tissue is a source of inflammatory cytokines has led to the hypothesis that chronic obesity, metabolic syndrome, and diabetes mellitus are all inflammatory diseases.
There is a close linkage between PUFAs and inflammation (Marion et al., 2015). This relationship is drawn from the fact that eicosanoids, which regulate inflammation, are produced from 25-carbon polyunsaturated fatty acids. Inflammatory cells are characterized by low concentrations of other 20-carbon PUFAs and a high concentration of n-6 PUFA arachidonic acid (Ferdouse et al., 2019). As a result, the average physiologic outcomes are determined by the present cells, the concentrations of different eicosanoids generated and the sensitivity of the target cells and tissues to the generated eicosanoids.
3 Literature Review
The immune system of most living organisms completely depend on the nutrition and diet for nourishment (Oswald, 2019). The constant supply of dietary constituents that have immune-regulating abilities such as fatty acids and vitamins is what has been thought to boost the immune system. Recent years have seen a steady increase in the number of scientific studies seeking to establish the relationship and impact of polyunsaturated fats on the body’s immune system. Most of these studies have particularly been centered on linoleic acid, ALA, docohexanoic acid, DHA and eicosapentanoic acid, EPA. Most PUFAs are extracted from linoleic acid, LA, and are widely used in feed rations as supplementary ingredients (Sprague et al., 2019). Recent studies suggest that fatty acids tend to alter the immune cell functions by changing the makeup of the cell membrane phospholipids to membrane lipid fluidity. The studies also argue that there is sufficient evidence to conclude that polyunsaturated fatty acids, PUFAS, regulate the metabolism of lipids, promote growth and maturity, on top of their primary role of maintaining cell structure.
Relationship between DHA, EPA and Inflammatory Response.
Both DHA and EPA produce anti-inflammatory resolvins. The two prominent Omega-3 fatty acids found in fish supplements have different inhibitory effects on biochemical markers of inflammation, with one potentially eliciting a higher inti-inflammatory response (Freitas & Campos, 2019). Different studies have been conducted to determine the effect of DHA and EPA on inflammation. A small study recently conducted found out that there was more suppression in the production of pro-inflammatory cytokines in patients who took doses of DHA compared to patients who took dosses of EPA (Duvall & Levy, 2016). This study seems to be casting shadows on the ability of EPAs in suppressing inflammations. According to the published journal, taking EPA supplements was less effective at suppressing cytokines compared to taking DHA supplements. “DHA showed more signs of potency in inhibiting pro-inflammatory cytokines while EPA effectively balanced their profiles against the anti-inflammatory cytokines” (So et al., 2021). There is sufficient evidence to also conclude that raising the DHA to EPA ratio by supplementing it with EPA strikes a balance with more anti-inflammatory cytokines.
Anti-inflammatory Effects of Polyunsaturated Fatty Acids
Most in vivo studies conducted on cell cultures evidence that EPA and DHA have inhibiting properties towards the production of IL-1β and TNF-α monocytes (Honda et al., 2015). Polyunsaturated fatty acids decreased the production of these monocytes when this study was conducted on mice. Although most of these studies use fish oil, there is sufficient evidence to conclude that both DHA and EPA limit the production of inflammatory cytokines (Tortosa et al., 2017). The theory was recently further supported by a study where patients suffering from type 2 diabetes were given doses of DHA and EPA for 42 days. Both patients recorded a decrease in the concentration of plasma TNF-α (Molfino et al., 2017). The reduction in concentration suggest that the EPA and DHA inhibit the production of inflammatory cytokines (Schwanke et al., 2016). Whereas this study proved that EPA and DHA suppress inflammation, other studies have not concluded on the long term effects of dietary n-3 polyunsaturated fatty acids on the production of inflammatory cytokines.
Anti-inflammatory effect

Mechanism likely to be involved

Reduced production of inflammatory cytokines IL-6, IL-6, IL-1β

Differential effects of arachidonic acids and EPA derived eicosanoids

Long-chain polyunsa...