Free radicals and antioxidants. Cell and biochemical mediators involved in allergy, immunomodulation and inflammation.

BYMahender.K

M.Pharm 1st yr 1st sem.

Srikrupa institute of pharmaceutical sciences,

Velkatta,kondapak,medak.

Andhra pradesh.

Under the guidance ofDr. T.Shivaraj gouda M.pharm.,PhD

H.O.D. (Pharmacology)

Free radicals and antioxidants

Free radicals:Free radicals are atoms or groups of atoms with an odd

(unpaired) number of electrons these are also known as Reactive Oxygen Species (ROS) and these compounds are formed when oxygen molecules combine with other molecules.

Once formed these highly reactive radicals can start a chain reaction, like dominoes. Their chief danger comes from the damage they can do when they react with important cellular components such as DNA, or the cell membrane.

Cells may function poorly or die if this occurs. To prevent free radical damage the body has a defense system of antioxidants.

Where do these free radicals come from?

• An oxygen molecule with paired electrons is stable; however oxygen with an unpaired electron is reactive. The radicals are likely to take part in chemical reactions, taking electrons from vital components and leaving them damaged.

• Radicals also play an important role in combustion, atmospheric chemistry, polymerization, biochemistry, and many other chemical processes, including human physiology

Antioxidants:Antioxidants are molecules which can safely interact with

free radicals and terminate the chain reaction before vital molecules are damaged.

Although there are several enzyme systems within the body that scavenge free radicals, the principle micronutrient (vitamin) antioxidants are vitamin E, beta-carotene, and vitamin C.

Additionally, selenium, a trace metal that is required for proper function of one of the body's antioxidant enzyme systems, is sometimes included in this category.

The body cannot manufacture these micronutrients so they must be supplied in the diet.

Hopefully we have enough antioxidants to "fight off" the Free Radicals!

Unfortunately, free radicals are not just formed through breathing and other normal bodily processes, but we have many outside influences and factors that dramatically further produce free radicals in our cells. (stress, toxins, chemicals, etc.)

Then there are many things that deplete our antioxidant supply.(medication, cigarette smoke, Tylenol, etc.)

So, not only do we have more stresses in our life that create more free radicals than even just 30 years ago, but we have also become dependant on drugs, surgeries and medication that deplete our natural antioxidant supply.

Now, more than ever we need to eat antioxidant rich foods and take antioxidant supplements.

Free radicals in our cells are like little fires. Once a free radical is formed that “small fire” begins to grow just like a real fire.

If this fire is not put out by antioxidants then these fires cause serious damage to our cells, tissues, and then organs.

Free radicals will damage our cell membranes, enzymes, blood lipoprotein, unsaturated fatty acids in our cell membranes and even damage our chromosomes and DNA.

All of this damage will eventually lead to premature aging and disease.

Functions of antioxidant:The most important and well characterised natural

antioxidants in the animal body are vitamin E and C.

Four possible mechanisms have been suggested (John, 1989) by which antioxidants function to reduce the rate of oxidation of fats and oils. These are:

Hydrogen donation by the antioxidant.

Electron donation by the antioxidant.

Addition of the lipid to the antioxidant.

Formation of a complex between the lipid and antioxidant.

The Best Natural Antioxidants:

Beans - High in folate, fiber and antioxidants, beans can help lower cholesterol and scavenge free radicals

Blueberries - Blueberries have one of the highest levels of antioxidants than any fruit or vegetable. They have a wide variety of different beneficial phytonutrients as well.

Broccoli - Broccoli helps promote eye health

Spinach - Spinach Contains iron, and is packed with carotenoids which help your eyes

Sweet Potatoes - These boost  your immune system

Walnuts - These are one of the few plant sources that are high in omega-3 fatty acids. They also have some of the best antioxidants known for fighting cancers, as well as amino acids that can reduce the risk of heart attack.

Salmon - Salmon is another excellent source of omega three fatty acids that reduce the risk of heart disease and heart attack.

• Vitamin E : d-alpha tocopherol. A fat soluble vitamin present in nuts, seeds, vegetable and fish oils, whole grains (esp. wheat germ), fortified cereals, and apricots. Current recommended daily allowance RDA{Recommended Dietary Allowance}is 15 IU{International Unit} per day for men and 12 IU per day for women.

• Vitamin C : Ascorbic acid is a water soluble vitamin present in citrus fruits and juices, green peppers, cabbage, spinach, broccoli, kale, cantaloupe, kiwi, and strawberries. The RDA is 60 mg per day. Intake above 2000 mg may be associated with adverse side effects in some individuals.

• Beta-carotene is a precursor to vitamin A (retinol) and is present in liver, egg yolk, milk, butter, spinach, carrots, squash, broccoli, yams, tomato, cantaloupe, peaches, and grains. Because beta-carotene is converted to vitamin A by the body there is no set requirement. Instead the RDA is expressed as retinol equivalents (RE), to clarify the relationship. (NOTE: Vitamin A has no antioxidant properties and can be quite toxic when taken in excess.)

CONCLUSION:• Antioxidant plays a very important role in the body

defense system against reactive oxygen species.

• Vegetable oils contain natural antioxidants.

• Lipid peroxidation is the introduction of a functional group containing two catenated oxygyen atoms into unsturated fatty acids in a free radical reaction.

• Antioxidant enzymes are an important protective mechanism ROS.

ALLERGY

An allergy is a hypersensitivity disorder of the immune system.

Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an “allergen”.

Allergic reactions are distinctive because of excessive activation of certain white blood cells called mast cells and basophils by a type of antibody called Immunoglobulin E (IgE).

This reaction results in an inflammatory response which can range from uncomfortable to dangerous.

Origin of the Word “Allergy”

The word allergy is a combination of two Greek words:

“Allos” - other and

“Ergos” - action

Some Allergic Conditions & Symptoms

• Some serious allergic diseases are: asthma, dermatitis, bee sting allergy, food allergy, conjunctivitis, and severe systemic anaphylaxis

• Some common symptoms of allergy are: nose itching, sneezing, burning sensation, production of watery or mucous excretion, and possibly altered condition of other organs

The Allergy Pathway

Allergy degranulation processes

Cells Involved In Allergic Reactions CD4+ T cells play the central role in allergic

inflammation.

Two types of CD4+ : T helper-1 (Th1) - Produces IL-2, TNF-, and interferon- (IFN-

). Antagonize the allergic response.

T helper-2 (Th2): Produces IL-4, IL-5, IL-6, IL-9, IL-10, and IL-13. IL-4 and IL-13 play the main role in allergic response.

Histamine which causes the 5 symptoms of allergic inflammation:heat, pain, swelling, redness and itchiness.

IL-4, affects more B cells to differentiate into plasma cells and produce more IgE and thus the vicious cycle continues.

Types of Allergy:There are four types of allergic reactions:

Type-1 allergic reaction (immediate, anaphylactic): Develops when the allergen stimulates the organism to produce IgE. It is also known as IgE mediated, immediate or anaphylactic reaction

Type-2 allergic reaction (cytotoxic): Develops when the allergic reaction is accompanied by the appearance of IgG or IgM class immunoglobulins. These antibodies react with allergens on the surface of the blood cells or bone marrow cells membranes and causing them to undergo lysis

Type-3 allergic reaction: Develops when allergen reacts with IgG, IgM, IgA or IgE forming immune complexes that are deposited in tissues and initiate inflammations

Type-4 allergic reaction: It is also known as a delayed or cellular reaction. T lymphocytes play main role in this type of allergic reaction when they encounter specific allergen, by secreting cytokines triggering inflammatory reaction in tissues.

Types of AllergenThere are 2 types of Allergens:

(a) Allergens from the natural environment:

• These are of high-molecular weight compounds, molecular weight higher than 10 kDa. Most of these allergens have an enzymatic function in their natural state.

• Few examples are: pollen of different plants, mould fungi spores, bacteria, house dust mites, epidermis of house pets, insect venom, some food proteins, etc.

(b) Allergens from a chemical environment:

• These are usually low-molecular chemical compounds, less than 1 kDa. They usually bind with a large protein and exert allergenic effect.

• Few examples are: metals, drugs, additives to food products, latex, aldehydes.

Medication

Several antagonistic drugs are used to block the action of allergic mediators, or to prevent activation of cells and degranulation processes.

These include antihistamines, glucocorticoids, epinephrine (adrenaline), theophylline and cromolyn sodium. Anti-leukotrienes, such as Montelukast (Singulair) or Zafirlukast (Accolate), are FDA approved for treatment of allergic diseases.

Anti-cholinergics, decongestants, mast cell stabilizers, and other compounds thought to impair eosinophil chemotaxis, are also commonly used. These drugs help to alleviate the symptoms of allergy, and are imperative in the recovery of acute anaphylaxis, but play little role in chronic treatment of allergic disorders.

Inflammation:

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants.

Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process.

Inflammation is not a synonym for infection even in cases where inflammation is caused by infection.

Although infection is caused by a microorganism, inflammation is one of the responses of the organism to the pathogen.

However, inflammation is a stereotyped response, and therefore it is considered as a mechanism of innate immunity as compared to adaptive immunity, which is specific for each pathogen.

Cellular Components of inflammation:Granulocytes:

• Polymorphonuclear cells( neutrophils)

• Basophils

• Eosinophils

Lymphocytes:

• B cells and humoral immunity,

• T cells and cell mediated immunity,

• Natural killer cells.

Monocytes and macrophages.

• Endothelium

• Fibroblasts

• Smooth muscle cells

• Mast cells

Chemical Mediators:• Chemical substances synthesised or released which

mediate the changes in inflammation.

• Histamine by mast cells - vasodilatation.

• Prostaglandins – Cause pain & fever.

• Bradykinin - Causes pain.

• Products of the complement system

• Lymphokines released by sensitized T cells

Inflammatory disorders

Inflammatory abnormalities are a large group of disorders which underlie a vast variety of human diseases.

The immune system is often involved with inflammatory disorders, demonstrated in both allergic reactions and some myopathies, with many immune system disorders resulting in abnormal inflammation.

Non-immune diseases with etiological origins in inflammatory processes include cancer, atherosclerosis, and ischaemic heart disease.

Examples of disorders associated with inflammation include:

• Acne vulgaris

• Asthma

• Autoimmune diseases

• Hypersensitivities

• Inflammatory bowel diseases

• Pelvic inflammatory disease

• Reperfusion injury

• Rheumatoid arthritis

Treatment : Anti-inflammatory

• Steroids

• Non-steroidal anti-inflammatory drugs

• Immune Selective Anti-Inflammatory Derivatives (ImSAIDs)

• Herbs

• Ice treatment

• Food

Immunomodulation

What is an immunomodulator?

• An immunomodulator is any substance that helps to regulate the immune system.

• This "regulation" is a normalisation process, so that an immunomodulator helps to optimise immune response.

• Give an immunomodulator to someone with a low immune system, and it can help raise that immunity;

• Give a modulator to someone with a healthy immune system, and it will have little effect in the body; and

• Give a modulator to someone with an overactive immune system, and can help to normalize that overactive immune system.

• So immunomodulators do not tend to boost immunity, but to normalize it.

How do they work in the body?How immunomodulators work in the body is still largely a

mystery. Part of their benefit appears to be their ability to naturally increase the body's production of messenger molecules, such as cytokines, which mediate and regulate the immune system.

Some of them, like Biobran, can also decrease the production of inflammatory cytokines. Overall, the effect is a more efficient immune system.

Most people using substances like Biobran MGN-3 do so because they have low immune systems.

Increasing cytokine production in this case can significantly help raise the immune response. This site focuses, therefore, on the effect of immunomodulators in helping to increase immune function.

A Standard Immunomodulatory Response:

• After a period of time on a particular dose, this typical modulator modulates the immune system to a characteristic level that is independent of dosage .

• The difference between dosages is that higher doses tend to modulate quicker, and although the difference might only be small, as in this case, it is very significant to those who are seriously unwell and need immune system help as fast as possible.

Types :

There are two types of effects

1. Immunostimulation:

• Increase the immune response, useful in infections, immunodeficiency (for example, AIDS) and cancers.

2. Immunosuppression:

• Inhibits immune response in organ transplantation and autoimmune diseases.

Immunostimulant drugs

Levamisole:

An antihelmintic drug that also restores functions of B lymphocytes, T lymphocytes, monocytes and macrophages, Causes agranulocytosis. Hence it has been used in colon cancer along with 5-FU.

Thalidomide. Different effects of this old drug have been utilized in conditions such as:

• Erythema nodosum leprosum: Anti-inflammatory effect

• Multiple myleoma: Anti-angiogenesis

• Rheumatoid arthritis: Anti TNF effect.

BCG(Bacillus Calmitte Guerin): Used in carcinoma bladder.

Recombinant cytokines.

• Interferons: In tumors and chronic hepatitis B and C

• Interleukin 2 (aldeslukin): has been used in renal cell carcinoma and melanoma

Immunosuppressant drugs:

These drugs have major role in organ transplantation and auto immune diseases. The drugs are:

Calcineurin inhibitors (Specific T-cell inhibitors). Cyclosporine (Ciclosporin), Tacrolimus

Antiproliferative drugs (Cytotoxic drugs). Azathioprine, Cyclophosphamide, Methotrexate, Chlorambucil, Mycophenolate mofetil (MMF)

Glucocorticoids. Prednisolone and others

Antibodies. Muromonab CD3, Antithymocyte globin (ATG), Rho (D) immuneglobin, Efalizumab

Conclusion:• Immunomodulators are going to be a central part of

medicine. Helping the body help itself by optimising the immune system is of central importance in a society so stressed, unhealthily nourished and exposed to toxins that most of us are likely to have compromised immune systems.

• Immunomodulation, however, is a normalizing process, and it is important to bear this in mind when choosing doses over time and comparing different products.

Most immunomodulatory drugs are suppressants◦ Cause problems as it makes patients more susceptible to

infection

◦ Most are somewhat toxic.

Tolerance is a great concept but not yet fully realized.

Stimulants are helpful to boost the immune system.

Immunization has been a proven tool against fighting infectious diseases.

Thank YouNEVER GIVE UP FACE ANY STRUGLE IN UR LIFE TO REACH UR DESTINATION