Inflammation – a type of a non-specific immune response – is the biologic process by which the body responds to infection, irritation or other injury or environmental exposures. When inflammation involves primarily the musculoskeletal system, this may result to pathogenesis of diseases collectively called “inflammatory rheumatic diseases”. Some of the most well-known inflammatory rheumatic diseases include:
a) Chronic inflammatory arthritides [Rheumatoid arthritis (RA) and spondyloarthropathies (SpA)]
b) Collagen vascular diseases (SLE, systemic sclerosis, myositis)
c) Systemic vasculitides (Adamantiades-Behcet's disease, ANCA-associated vasculitides).
d) Other autoinflammatory diseases such as the familial Mediterranean fever (FMF).
Inflammatory rheumatic diseases are not uncommon affecting up to 5% of the adult population. People of both genders and across all ages can be affected. In general, women tend to be afflicted more commonly than men; in fact, some autoimmune rheumatic diseases such as SLE, have a very strong predilection for women of the reproductive age. If not managed appropriately, inflammation may lead to irreversible injury (damage) of the joints (bone and cartilage), kidneys, heart and lung, blood, skin or other organs, thus causing significant morbidity and disability.
Inflammatory rheumatic diseases are characterized by both acute and chronic inflammation. Inflammation is provoked either by an immune response directed against self-constituents (auto-immunity) or by yet unidentified non-self, non-pathogen targets (auto-inflammation). Research has thus far revealed the important role of cells (B and T lymphocytes, monocytes and monocyte-derived cells, dendritic cells, neutrophils), co-stimulatory or inhibitory molecules such as CTLA-4, PD-1, and BTLA, as well as cytokines such as tumor necrosis factor (TNF), interferon-gamma (IFN-γ) and interleukins in mediating tissue injury. De-regulation of cytokine production or cytokine networks have also been implicated in their pathogenesis.