Roles of immune cells and their mediators in Chronic Pain. Treatments and Interventions.

Chronic pain –a major debilitating condition difficult to treat– is defined as pain lasting longer than 12 weeks. It contributes to disability, fatigue, anxiety, depression, sleep disturbances, poor quality of life, and increases the healthcare costs. Chronic pain affects approximately one fifth of people worldwide, and increases as the population ages.

Regardless of aetiology and pathophysiological categorization –nociceptive, neuropathic, or idiopathic– the impact of chronic pain is broadly similar across many conditions. Inflammation, which causes inflammatory pain –rheumatoid arthritis (RA) and osteoarthritis (OA) account for ∼42% of the chronic pain patients in Europe; inflammatory bowel disease (IBD)–, nerve injury as a consequence of an operation or trauma, metabolic disorders –diabetic mellitus–, or auto-immune diseases –multiple sclerosis–, may cause neuropathic chronic pain. Cancer or cancer treatment –chemotherapy– may result in painful neuropathies.