SUMMARY Mammals have evolved neurophysiologic reflexes such as coughing and scratching to expel invading pathogens and noxious environmental stimuli. It is well established that these responses are also associated with chronic inflammatory diseases such as asthma and atopic dermatitis. However, the mechanisms by which inflammatory pathways promote sensations such as itch remain poorly understood. Here, we show that type 2 cytokines directly activate sensory neurons in both mice and humans. Further, we demonstrate that chronic itch is dependent on neuronal IL-4Rα and JAK1 signaling. We also observe that patients with recalcitrant chronic itch that failed other immunosuppressive therapies markedly improve when treated with JAK inhibitors. Thus, signaling mechanisms previously ascribed to the immune system may represent novel therapeutic targets within the nervous system. Collectively, this study reveals an evolutionarily conserved paradigm in which the sensory nervous system employs classical immune signaling pathways to influence mammalian behavior.

The somatosensory system relays many signals ranging from light touch to pain and itch.Touch is critical to spatial awareness and communication. However, in disease states, innocuous mechanical stimuli can provoke pathologic sensations such as mechanical itch (alloknesis). The molecular and cellular mechanisms that govern this conversion remain unknown. We found that in mice, alloknesis in aging and dry skin is associated with a loss of Merkel cells, the touch receptors in the skin. Targeted genetic deletion of Merkel cells and associated mechanosensitive Piezo2 channels in the skin was sufficient to produce alloknesis. Chemogenetic activation of Merkel cells protected against alloknesis in dry skin. This study reveals a previously unknown function of the cutaneous touch receptors and may provide insight into the development of alloknesis.

The NLRP3 (nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3) inflammasome-mediated inflammatory responses are critically involved in the progression of atherosclerosis (AS), which is the essential cause for cardiovascular diseases. Melatonin has anti-inflammatory properties. However, little is known about the potential effects of melatonin in the pathological process of AS. Herein, we demonstrate that melatonin suppressed prolonged NLRP3 inflammasome activation in atherosclerotic lesions by reactive oxygen species (ROS) scavenging via mitophagy in macrophages. The atherosclerotic mouse model was induced with a high-fat diet using ApoE−/− mice. Melatonin treatment markedly attenuated AS plaque size and vulnerability. Furthermore, melatonin decreased NLRP3 inflammasome activation and the consequent IL-1β secretion within atherosclerotic lesions. Despite the unchanged protein expression, the silent information regulator 3 (Sirt3) activity was elevated in the atherosclerotic lesions in melatonin-treated mice. In ox-LDL-treated macrophages, melatonin attenuated the NLRP3 inflammasome activation and the inflammatory factors secretion, while this protective effect was abolished by either Sirt3 silence or autophagy inhibitor 3-MA. Mitochondrial ROS (mitoROS), which was a recognized inducer for NLRP3 inflammasome, was attenuated by melatonin through the induction of mitophagy. Both Sirt3-siRNA and autophagy inhibitor 3-MA partially abolished the beneficial effects of melatonin on mitoROS clearance and NLRP3 inflammasome activation, indicating the crucial role of Sirt3-mediated mitophagy. Furthermore, we demonstrated that melatonin protected against AS via the Sirt3/FOXO3a/Parkin signaling pathway. In conclusion, the current study demonstrated that melatonin prevented atherosclerotic progression, at least in part, via inducing mitophagy and attenuating NLRP3 inflammasome activation, which was mediated by the Sirt3/FOXO3a/Parkin signaling pathway. Collectively, our study provides insight into melatonin as a new target for therapeutic intervention for AS.

Background Diabetic cardiomyopathy (DCM) is a major threat for diabetic patients. Silent information regulator 1 (SIRT1) has a regulatory effect on mitochondrial dynamics, which is associated with DCM pathological changes. Our study aims to investigate whether resveratrol, a SRIT1 activator, could exert a protective effect against DCM. Methods and Results Cardiac-specific SIRT1 knockout (SIRT1KO) mice were generated using Cre-loxP system. SIRT1KO mice displayed symptoms of DCM, including cardiac hypertrophy and dysfunction, insulin resistance, and abnormal glucose metabolism. DCM and SIRT1KO hearts showed impaired mitochondrial biogenesis and function, while SIRT1 activation by resveratrol reversed this in DCM mice. High glucose caused increased apoptosis, impaired mitochondrial biogenesis, and function in cardiomyocytes, which was alleviated by resveratrol. SIRT1 deletion by both SIRT1KO and shRNA abolished the beneficial effects of resveratrol. Furthermore, the function of SIRT1 is mediated via the deacetylation effect on peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), thus inducing increased expression of nuclear respiratory factor 1 (NRF-1), NRF-2, estrogen-related receptor-α (ERR-α), and mitochondrial transcription factor A (TFAM). Conclusions Cardiac deletion of SIRT1 caused phenotypes resembling DCM. Activation of SIRT1 by resveratrol ameliorated cardiac injuries in DCM through PGC-1α-mediated mitochondrial regulation. Collectively, SIRT1 may serve as a potential therapeutic target for DCM.