Innate immune memory in inflammatory arthritis.

Area of Science:

• Immunology
• Cell Biology
• Rheumatology

Background:

• Immunological memory, traditionally linked to adaptive T and B cells, has a historical precedent dating back to ancient observations of pathogen protection.
• Recent research reveals that innate immune cells also possess memory-like properties, a phenomenon termed 'trained immunity'.
• Trained immunity is reshaping the understanding of chronic inflammatory and autoimmune conditions.

Purpose of the Study:

• To review the memory-like characteristics of innate immune cells in the context of inflammatory arthritis.
• To explore the interplay between chronic inflammatory environments and cellular reprogramming in disease pathogenesis.

Main Methods:

• Review of current literature on innate immune memory and inflammatory arthritis.
• Analysis of mechanisms involving cytokine signaling, metabolic and epigenetic reprogramming of hematopoietic progenitors.
• Examination of imprinted memory in mature innate cells, including osteoclasts.

Main Results:

• Aberrant pro-inflammatory signaling drives metabolic and epigenetic reprogramming in hematopoietic progenitors, worsening inflammatory responses and osteoclast differentiation.
• This reprogramming leads to exacerbated bone destruction in inflammatory arthritis.
• Memory imprinted on mature cells, such as osteoclasts, affects therapeutic responses and disease outcomes, causing persistent flares and relapse.

Conclusions:

• Innate immune memory plays a significant role in the pathogenesis of inflammatory arthritis.
• Cellular reprogramming by chronic inflammation contributes to disease progression, bone loss, and treatment resistance.
• Understanding trained immunity in innate cells offers new perspectives for managing chronic inflammatory and autoimmune diseases.