The multiple faces of the human immune system: Modern life causes low-grade inflammation and thereby provokes conflict between the selfish immune system and the selfish brain

This thesis describes the multiple ways by which the human immune system can react upon direct and indirect challenges, such as infection and wounds on the one hand, and chronic stress factors, such as smoking, on the other. The human defense system exhibits a type of selfish behaviour during both acute- and chronic activity states. Acute activation of the immune system is normally finalized in a short time through multiple mechanisms exerting immune inhibiting effects. This means that an inflammation is normally self-limiting, which protects the body against secondary damaging effects of the immune system itself. Chronic activity of the immune system is caused by all those risk factors related with modern life, including sedentary time, lack of exercise, sleep deprivation, smoking, overeating and also non-solved psycho-emotional problems. The sum of risk factors produces chronic activation of stress axes and entrance of bacterial debris in the blood stream, causing a chronic infectious state that is referred to as chronic low-grade inflammation. This low-grade inflammation should be considered as the cause of most, if not all, chronic non-communicable diseases (CNCD). Our interventions show that a short bout of "ancient" stress factors could finalize the chronic activity of the immune system and in this way protect people against the toxic effects of modern life. Evidence is given through changes in metabolic parameters such as weigh loss and decrease of glucose, triglycerides and cholesterol. Changes which were achieved after an intervention period of only ten days