Natural Killer Cells and Their Role in Rheumatoid Arthritis: Friend or Foe?

Abstract

Rheumatoid arthritis (RA) is a long-term disease that leads to inflammation of the joints and surrounding tissues. Natural killer (NK) cells are an important part of the innate immune system and are responsible for the first line of defense against pathogens during the initial immune challenge before the adaptive immune system eventually eliminates the infectious burden. NK cells have the capacity to damage normal cells or through interaction with other cells such as dendritic cells, macrophages, and T cells cause autoimmune diseases, such as RA. NK cells isolated from the joints of patients with RA suggest that they may play a role in this disease. However, the involvement of NK cells in RA pathology is not fully elucidated. Both protective and detrimental roles of NK cells in RA have recently been reported. A better understanding of NK cells' role in RA might help to develop new therapeutic strategies for treatment of the RA or other autoimmune diseases. We have decided in this paper to focus on the NK cell biology, and attempt to bring the interested readership of this Journal up to date on the NK cell, specifically its possible relation to RA.

Human Postprandial Nutrient Metabolism and Low-Grade Inflammation: A Narrative Review

“…In fact, a fasting regiment of 7-10 days resulted in decreased CD4+ cells and CD4+ cells were inversely correlated with cortisol levels in peripheral blood, however, this study did not find differences in interleukins, although natural killer cell activity was higher [162]. The role of NK cells in RA is not clear, as both protective and detrimental roles have been described [163]. Interesting insights into the mechanism of decreased inflammation due to fasting comes from animal studies.…”

Activin A as a Mediator of NK–Dendritic Cell Functional Interactions

“…The release of activin A by DCs may thus represent a strategy to counterbalance Th1-biased T cell polarization. Finally, activin A released during NK-DC interactions may contribute to the increased local and systemic levels of these cytokines detected in many acute and chronic inflammatory diseases, such as lichen planus or rheumatoid arthritis, characterized by the concomitant recruitment of these two cell types (20,(44)(45)(46)(47).…”

Anti-inflammatory effects of oxymatrine on rheumatoid arthritis in rats via regulating the imbalance between Treg and Th17 cells

“…In RA, inflammatory cells, including natural killer cells, T and B lymphocytes and neutrophils, infiltrate the synovial membrane, contributing to cartilage and bone degradation (3). Among the proinflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin 17A (IL-17A) are expressed at high levels in the rheumatoid joint and are important in the mechanisms underlying the inflammatory response (4,5).…”