The vasculature in sepsis: delivering poison or remedy to the brain?

Long-Term Outcomes in Acute Respiratory Distress Syndrome: Epidemiology, Mechanisms, and Patient Evaluation

Survivors of acute respiratory distress syndrome (ARDS) experience challenges that persist well beyond the time of hospital discharge. Impairment in physical function, cognitive function, and mental health are common and may last for years. The current coronavirus disease 2019 pandemic is drastically increasing the incidence of ARDS worldwide, and long-term impairments will remain lasting effects of the pandemic. Evaluation of the ARDS survivor should be comprehensive, and common domains of impairment that have emerged from long-term outcomes research over the past 2 decades should be systematically evaluated.

Temporal unsnarling of brain's acute neuroinflammatory transcriptional profiles reveals panendothelitis as the earliest event preceding microgliosis

Sepsis-associated encephalopathy (SAE) is an acutely progressing brain dysfunction induced by systemic inflammation. The mechanism of initiation of neuroinflammation during SAE, which ultimately leads to delirium and cognitive dysfunction, remains elusive. We aimed to study the molecular events of SAE to capture its onset and progression into the central nervous system (CNS), and further identify the cellular players involved in mediating acute inflammatory signaling. Gene expression profiling on the cerebral vessels isolated from the brains of the mice treated with peripheral lipopolysaccharide (LPS) revealed that the cerebral vasculature responds within minutes to acute systemic inflammation by upregulating the expression of immediate early response genes, followed by activation of the nuclear factor-κB pathway. To identify the earliest responding cell type, we used fluorescence-activated cell sorting (FACS) to sort the glial and vascular cells from the brains of the mice treated with LPS at different time points, and RNA-seq was performed on microglia and cerebral endothelial cells (CECs). Bioinformatic analysis followed by further validation in all the cell types revealed that panendothelitis. i.e., the activation of CECs is the earliest event in the CNS during the inception of acute neuroinflammation. Microglial activation occurs later than that of CECs, suggesting that CECs are the most likely initial source of proinflammatory mediators, which could further initiate glial cell activation. This is then followed by the activation of apoptotic signaling in the CECs, which is known to lead to the blood-brain barrier disruption and allow peripheral cytokines to leak into the CNS, exacerbate the gliosis, and result in the vicious neuroinflammatory cascade. Together, our results model the earliest sequential events during the advancement of systemic inflammation into the CNS and facilitate to understand the interplay between the vascular and glial cells in initiating and driving acute neuroinflammation during SAE.

Dexmedetomidine-up-regulated microRNA-381 exerts anti-inflammatory effects in rats with cerebral ischaemic injury via the transcriptional factor IRF4

Dexmedetomidine (Dex) possesses analgesic and anaesthetic values and reported being used in cerebral ischaemic injury therapeutics. Accumulating studies have determined the effect of microRNAs (miRNAs) on the cerebral ischaemic injury. Thus, the present study aimed to unravel the molecular mechanism of miR-381 and Dex in cerebral ischaemic injury. For this purpose, the cerebral ischaemic injury rat model was established by induction of middle cerebral artery occlusion (MCAO) and expression of miR-381 and IRF4 was determined. Thereafter, MCAO rats were treated with Dex, miR-381 mimic, miR-381 inhibitor and oe-IRF4 respectively, followed by evaluation of neurological function. Furthermore, neuron cells were isolated from the hippocampus of rats and subjected to oxygen-glucose deprivation (OGD). Then, OGD-treated neuron cells and primary neuron cells were examined by gain- and loss-of-function assay. Neuron cell apoptosis was detected using TUNEL staining and flow cytometry. The correlation between interferon regulatory factor 4 (IRF4) and interleukin (IL)-9 was detected. Our results showed down-regulated miR-38 and up-regulated IRF4 in MCAO rats. Besides, IRF4 was targeted by miR-381 in neuron cells. Dex and overexpressed miR-381, or silenced IRF4 improved the neurological function and inhibited neuron cell apoptosis in MCAO rats. Additionally, in MCAO rats, Dex was found to increase the miR-381 expression and reduced IRF4 expression to decrease the IL-9 expression, which suppressed the inflammatory response and cell apoptosis both in vivo and in vitro. Importantly, our study demonstrated that Dex elevated the expression of miR-381, which ultimately results in the inhibition of inflammation response in rats with cerebral ischaemic injury.