Immunology and Antiaging Medicine: Inflammaging due to Chronic Inflammation

Inflammation is a biological response in tissues that occurs when harmful stimuli such as infection by pathogens, foreign bodies, or tissue damage are applied. The classical four signs of inflammation, as described in Latin, are rubor (redness), calor (heat), tumor (swelling), and dolor (pain). These signs represent reactions common to acute inflammation, consisting of vasodilation and increased permeability, migration and infiltration of inflammatory cells into tissues due to various inflammatory mediators, neutralization of inflammatory responses by immune reactions, and healing processes through tissue regeneration and repair. On the other hand, when the causative factors of inflammation persist and cannot be eliminated, or when the resolution mechanism of inflammation does not function properly, inflammation becomes chronic. Chronic inflammation causes functional impairment at the site of inflammation, which is considered the fifth sign of inflammation. In chronic inflammation, infiltration of inflammatory cells centered on macrophages, tissue destruction, angiogenesis, and tissue remodeling (structural changes) due to fibrosis occur, eventually leading to irreversible organ dysfunction. However, many aspects of the molecular mechanism are still unclear. The World Health Organization (WHO) defines chronic diseases such as cardiovascular diseases, cancer, metabolic diseases, respiratory diseases, and neuropsychiatric diseases as noncommunicable diseases (NCDs), and positions them as important issues in medicine and public health. Chronic inflammation is a common underlying pathology in these NCDs.