Immune cells of the brain linked to Gulf War Syndrome symptoms

​A new theory based on interactions between the immune system and the brain may provide an explanation for the symptoms experienced by veterans suffering from Gulf War Syndrome.

According to the theory special brain cells called 'microglia', which are actually a form of macrophage (white blood cell) and part of the body's first line immune defense, become sensitised and persistently release chemicals which affects the firing of neurons in the brain, causing chronic pain and other symptoms.

Following an announcement on February 26th made by the Veterans Affairs Department in the US, scientists from across the country were invited to Washington D.C. by the Federal Advisory Committee on Gulf War Veteran's Illnesses to present research related to the symptoms and illnesses suffered by veterans, collectively known as Gulf War Syndrome.

It was at this meeting that Dr. Linda Watkins of the University of Colorado reported on her work demonstrating that microglia play a key role in chronic pain and drug addiction. Conventional wisdom is that it it is only the nerve cells (neurons) themselves that cause chronic pain and tolerance to powerful painkilling drugs such as morphine. Dr Watkins explained that the new understanding of how microglia (essentially the same as macrophages found in the bloodstream but fixed in place in the brain) aggravate neurons after an injury by releasing substances that produce excruciating pain, led to the observation that the process may help to explain Gulf War Syndrome.

Gulf War syndrome has much in common with chronic fatigue syndrome (ME/CFS) and fibromyalgia (FMS) and is characterised by a constellation of unexplained symptoms, many neurological, including chronic pain, chronic fatigue, depression, sleep disturbances, poor memory and concentration, chemical sensitivities, as well as digestive disorders and lung problems. A combination of factors are thought to contribute to its development including multiple vaccinations given to soliders prior to deployment (many containing potentially toxic adjuvants such as squalene), psychological stress, and particularly exposure to low-level neurotoxins including sarin gas, drugs such pyridostigmine bromide (PB) given to soldiers to protect them from chemical warfare agents, pesticides used to treat tents, uniforms and vehicles, insect repellents (e.g. DEET), fumes from oil fields set ablaze by retreating Iraqi soldiers, and depleted uranium (DU) used in armour-piercing munitions by the allied forces. 

Unlike normal pain, chronic pain does not subside after an injury has healed. The latest research based on the principles of psychoneuroimmunology (the study of the connections between the mind, brain and immune system) shows that chronic pain results from ongoing pathological interactions between the brain and immune system. When we are ill the immune system releases chemicals called 'cytokines' which tell the brain to trigger the 'sickness response', that familiar feeling everyone experiences when coming down with the flu, for example. This response forces us to rest and allow the body to use all available energy to fight the infection. Symptoms associated with the sickness response include painful joints and muscles, profound fatigue, headache, and sensitivity to light and sound - all very similar to the symptoms suffered chronically by veterans suffering from Gulf War Syndrome.

Based on her research on microglia in chronic pain that she presented to the Federal Advisory Committee, Dr. Watkins believes an initial exposure to some stressor such as the numerous chemical toxins present in the Gulf �primes� the microglia in the brain to make them hyper sensitive. Then when a second toxin, infection, injury, or highly stressful situation is experienced, the brain's immune cells over-react, triggering excessive secretion of the cytokines cause the sickness response. In Gulf War Syndrome, and perhaps chronic fatigue syndrome, fibromyalgia and other unexplained chronic illnesses, it seems the sickness response is not switched off once the body has healed thus leading to chronic symptoms.

In the case of Gulf War veterans, the initial trigger could have been a reaction to vaccines, psychological stress, or exposure to low-level neurotoxins. A second insult could have then been experienced during the war or once the soldiers were back home. Research from various labs on microglia in chronic pain has identified numerous stages in this neuro-immune signaling process that become disrupted. Several drugs have been found to effectively reverse the process in animals and human trials are now getting underway.

It may be that there is also a role for alternative mind-body therapies such as meditation, breathing techniques, acupuncture, and reflexology in aiding healing from Gulf War Syndrome since evidence suggests they also influence interactions between the immune system and brain.

Source: National Institute of Child Health and Human Development