Red Blood Cell-Conditioned Media from Non-Alcoholic Fatty Liver Disease Patients Contain Increased MCP1 and Induce TNF-α Release

BACKGROUNDNon-Alcoholic Fatty Liver Disease (NAFLD) constitutes a global pandemic. An intricate network among cytokines and lipids possesses a central role in NAFLD pathogenesis. Red blood cells comprise an important source of both cytokines and signaling lipids and have an important role in the molecular crosstalk during immunometabolic deregulation. However, their role in NAFLD has not been investigated in deep. METHODSConditioned media from erythrocytes derived from 10 NAFLD patients (4 men, 6 women, aged 57.875{+/-}15,16) and 10 healthy controls (4 men, 6 women, aged 39.3{+/-}15.55) were produced and used for the analysis of 9 cytokines (IFN-{gamma}, TNF-, CCL2, CCL5, IL-8, IL-1{beta}, IL-12p40, IL-17, MIP-1{beta}), 2 signaling lipids (Sphingosine 1-phosphate and Lysophosphatidic Acid), and cholesterol. Their effect on the cytokine profile released by RAW 264.7 macrophages was also studied. RESULTSErythrocytes from patients with NAFLD augmented the levels of MCP1 in the growth medium in comparison to the erythrocytes derived from healthy controls (37{+/-}40 pg/ml vs 6.51{+/-}5.63). No statistically significant differences were found between patients and healthy controls with regard to S1P, LPA, cholesterol and 8 other cytokines. TNF-a release by RAW 264.7 cells was increased after incubation with patient-derived erythrocyte conditioned medium compared to medium without RAW 264.7 cells from either healthy of NAFLD subjects. CONCLUSIONSErythrocytes could contribute to the liver infiltration by monocytes and to the activation of macrophages, partially due to release of CCL2, in the context of NAFLD.