Cryptochromes Regulate Circadian Inflammation Save

Circadian rhythms may be disrupted or become exaggerated in a variety of inflammatory conditions. For instance, interleukin-6 (IL-6) and IL-1 have a known circadian cycle to their production, but the same can not be said for TNF. 

It has long been postulated that circadian biology may influence inflammatory arthritis or explain certain features, such as morning stiffness.

The Faseb Journal reports on a study wherein researchers examined a variety of mechanistic links by using mice with collagen-induced arthritis. After induction, they found robust daily variation in paw swelling and inflammatory cytokine expression. (Citation source http://buff.ly/2aEzx6n) 

Inflammatory markers were significantly repressed during the dark hours and increased thereafter. The inflammatory cells responsible for this diurnal variation was the fibroblast-like synoviocytes (FLSs).

Constant light exposure to the arthritic mice caused a loss of the nighttime repression of local inflammation.

Moreover, they found that core clock proteins CRYPTOCHROMES 1 and 2 repressed inflammation within the FLS, and provide novel evidence that a CRYPTOCHROME activator has anti-inflammatory properties in human cells.

Cryptochromes have proven anti-inflammatory effects in cultured cells as well, and present new opportunities for the development of drugs that may be used to treat inflammatory diseases and conditions, such as rheumatoid arthritis.