Stopping TIME for initiating a DEFENSE response.

What is it about?

Melatonin, besides being the hormone of darkness, plays a key role as an immune modulator. At the initial phase of a defense response, the synthesis of melatonin is switched from the pineal to phagocytes. In this revision, we show that this switch is coordinated by a unique factor triggered by pathogen- or danger-associated molecular patterns. Depending on the cellular environment this transcription factor induces or blocks the expression of the key enzyme in melatonin synthesis. WHY? 1 - reducing CIRCULATING melatonin favors the entrance of phagocytes to the site of lesion 2 - Melatonin synthesized by macrophages and monocytes increases its phagocytic activity, while reduces the synthesis of NO. 3 - therefore, melatonin synthesized by phagocytes plays an essential role in the regenerative phase of an inflammatory response. Finally, it is important to consider that the melatonin synthesis by phagocytes needs to be reduced after the end of the defense response, as the maintenance of high levels of locally synthesized melatonin will impair the synthesis of NO, and the initiation of another defense response

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Why is it important?

This is a new paradigm for acute defense response that shows how the timing organization of the organism is changed for allowing a proper mounting of a defense response. In addition, we show that melatonin, the hormone of darkness, plays other functions independent of environment lighting,

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