Inflammation, Immunology and Allergy
Inflammation can be defined as a complex body defence mechanism responding to dangerous endogenous or exogenous stimuli in order to restore body homeostasis. Thus, the skin is continuously challenged to prevent inflammation, and inflammatory skin diseases are very common worldwide. Similarly, allergic reactions (types 1–4) are inflammatory processes created by the body system to respond to ‘danger signals’ of various origins. Very early in phylogenesis, inflammation is associated with the host defence against infectious, allergic or toxic agents, UV radiation, noxious heat and cold, or other injury. Innate and later adaptive immune mechanisms have been established that, uncontrolled, potentially lead to chronic disease or death, as in anaphylactic shock. The body system responds with the induction of various inflammatory pathways such as radical oxygen species, nitric oxide derivatives, complement compounds, adenosine monophosphate, antimicrobial peptides, cytokines, chemokines, prostaglandins, leukotrienes, proteases, neuropeptides and growth factors, just to name a few. This chapter systematically covers the various mechanisms that regulate inflammatory and allergic responses and refers in a translational setting to the diseases that are involved in order better to understand the clinical characteristics of a skin disease, its differential diagnoses and optimal treatment options.
Keywords innate immunity, adaptive immunity, leukocytes, cell signalling, cytokine, autoimmune disease, neuromediator, anaphylaxis, keratinocyte, mast cell