Manuel Soto-Catalán

Metabolic associated fatty liver disease (MAFLD) is a hepatic manifestation of metabolic syndrome and usually associated with obesity and diabetes. Our aim is to characterize the pathophysiological mechanism involved in MAFLD development in Black Tan and brachyuric (BTBR) insulin-resistant mice in combination with leptin deficiency (ob/ob). We studied liver morphology and biochemistry on our diabetic and obese mice model (BTBR ob/ob) as well as a diabetic non-obese control (BTBR + streptozotocin) and non-diabetic control mice (BTBR wild type) from 4–22 weeks. Lipid composition was assessed, and lipid related pathways were studied at transcriptional and protein level. Microvesicular steatosis was evident in BTBR ob/ob from week 6, progressing to macrovesicular in the following weeks. At 12th week, inflammatory clusters, activation of STAT3 and Nrf2 signaling pathways, and hepatocellular ballooning. At 22 weeks, the histopathological features previously observed were maintained and no signs of fibrosis were detected. Lipidomic analysis showed profiles associated with de novo lipogenesis (DNL). BTBR ob/ob mice develop MAFLD profile that resemble pathological features observed in humans, with overactivation of inflammatory response, oxidative stress and DNL signaling pathways. Therefore, BTBR ob/ob mouse is an excellent model for the study of the steatosis to steatohepatitis transition.

Excitotoxic cell death because of the massive release of glutamate and ATP contributes to the secondary extension of cellular and tissue loss following traumatic spinal cord injury (SCI). Evidence from blockage experiments suggests that over‐expression and activation of purinergic receptors, especially P2X₇, produces excitotoxicity in neurodegenerative diseases and trauma of the central nervous system. We hypothesize that the down‐regulation of specific miRNAs after the SCI contributes to the over‐expression of P2X₇ and that restorative strategies can be used to reduce the excitotoxic response. In the present study, we have employed bioinformatic analyses to identify microRNAs whose down‐regulation following SCI can be responsible for P2X₇ over‐expression and excitotoxic activity. Additional luciferase assays validated microRNA‐135a‐5p (miR‐135a) as a posttranscriptional modulator of P2X₇. Moreover, gene expression analysis in spinal cord samples from a rat SCI model confirmed that the decrease in miR‐135a expression correlated with P2X₇ over‐expression after injury. Transfection of cultures of Neuro‐2a neuronal cell line with a miR‐135a inhibitory sequences (antagomiR‐135a), simulating the reduction of miR‐135a observed after SCI, resulted in the increase of P2X₇ expression and the subsequent ATP‐dependent rise in intracellular calcium concentration. Conversely, a restorative strategy employing miR‐135a mimicked reduced P2X₇ expression, attenuating the increase in intracellular calcium concentration that depends on this receptor and protecting cells from excitotoxic death. Therefore, we conclude that miR‐135a is a potential therapeutic target for SCI and that restoration of its expression may reduce the deleterious effects of ATP‐dependent excitotoxicity induced after a traumatic spinal cord injury. image