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Fig. 1 | Clinical and Molecular Allergy

Fig. 1

From: Biological clocks: their relevance to immune-allergic diseases

Fig. 1

Schematic representation of the master clock regulation of the immune system. Entrainment of the suprachiasmatic nuclei (SCN) is mediated by the input from intrinsically photosensitive retinal ganglion cells activated by light (from the sun and artificial lights from screens and indoor illumination). SCN controls directly the hypothalamus and the hypothalamus–pituitary–adrenal gland (HPA) axis, the autonomous nervous system and the pineal gland. Hormones and neurotransmitters (in boxes) from these clock-regulated structures modulate the activation and functions of different cell types of both the innate and adaptive immune system. Cytokines and chemokines produced by immune cells feed back on the SCN (dotted line). Through transcriptional mechanisms the SCN indirectly regulates also the synchronization of secondary clocks in peripheral tissues and other circadian cycles (wake/sleep, fast/feeding, etc.). NE norepinephrine

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