Persistent erythema with niacin is not attributable to aspirin resistance

Dysregulation of phospholipase and cyclooxygenase expression is involved in Schizophrenia

BACKGROUND

Schizophrenia (SZ) is a severe mental disease with highly heterogeneous clinical manifestations and pathological mechanisms. Schizophrenia is linked to abnormalities in cell membrane phospholipids and blunting of the niacin skin flush response, but the associations between these phenotypes and its molecular pathogenesis remain unclear. This study aimed to describe the PLA2/COX pathway, the key link between phospholipids and niacin flush, and to illustrate the pathogenic mechanisms in schizophrenia that mediate the above phenotypes.

METHODS

A total of 166 patients with schizophrenia and 54 healthy controls were recruited in this study and assigned to a discovery set and a validation set. We assessed the mRNA levels of 19 genes related to the PLA2/COX cascade in leukocytes by real-time PCR. Plasma IL-6 levels were measured with an ELISA kit. Genetic association analysis was performed on PLA2G4A and PTGS2 to investigate their potential relationship with blunted niacin-skin response in an independent sample set.

FINDINGS

Six of the 19 genes in the PLA2/COX pathway exhibited significant differences between schizophrenia and healthy controls. The disturbance of the pathway indicates the activation of arachidonic acid (AA) hydrolysis and metabolization, resulting in the abnormalities of membrane lipid homeostasis and immune function, further increasing the risk of schizophrenia. On the other hand, the active process of AA hydrolysis from cell membrane phospholipids and decreased transcription of CREB1, COX-2 and PTGER4 may explain the reported findings of a blunted niacin response in schizophrenia. The significant genetic associations between PLA2G4A and PTGS2 with the niacin-skin responses further support the inference.

INTERPRETATION

These results suggested that the activation of AA hydrolysis and the imbalance in COX-1 and COX-2 expression are involved in the pathogenesis of schizophrenia and blunting of the niacin flush response.

FUNDING

This work was supported by the National Key R&D Program of China (2016YFC1306900, 2016YFC1306802); the National Natural Science Foundation of China (81971254, 81771440, 81901354); Interdisciplinary Program of Shanghai Jiao Tong University (ZH2018ZDA40, YG2019GD04, YG2016MS48); Grants of Shanghai Brain-Intelligence Project from STCSM (16JC1420500); Shanghai Key Laboratory of Psychotic Disorders (13DZ2260500); and Shanghai Municipal Science and Technology Major Project (2017SHZDZX01); China Postdoctoral Science Foundation (2018M642029, 2018M630442, 2019M661526, 2020T130407); Natural Science Foundation of Shanghai (20ZR1426700); and Startup Fund for Youngman Research at SJTU (19 × 100040033).

Skin blood flow response to topically applied methyl nicotinate: Possible mechanisms

BACKGROUND

Methyl nicotinate (MN) induces a local cutaneous erythema in the skin and may be valuable as a local provocation in the assessment of microcirculation and skin viability. The mechanisms through which MN mediates its vascular effect are not fully known. The aim of this study was to characterize the vasodilatory effects of topically applied MN and to study the involvement of nitric oxide (NO), local sensory nerves, and prostaglandin-mediated pathways.

METHODS

MN was applied on the skin of healthy subjects in which NO-mediated (L-NMMA), nerve-mediated (lidocaine/prilocaine), and cyclooxygenase-mediated (NSAID) pathways were selectively inhibited. Microvascular responses in the skin were measured using laser speckle contrast imaging (LSCI).

RESULTS

NSAID reduced the MN-induced perfusion increase with 82% (P < .01), whereas lidocaine/prilocaine reduced it with 32% (P < .01). L-NMMA did not affect the microvascular response to MN.

CONCLUSION

The prostaglandin pathway and local sensory nerves are involved in the vasodilatory actions of MN in the skin.