Elevated liver enzymes following polytraumatic injury

Brain-derived extracellular vesicles mediate traumatic brain injury associated multi-organ damage

Traumatic brain injury (TBI) can negatively impact systemic organs, which can lead to more death and disability. However, the mechanism underlying the effect of TBI on systemic organs remains unclear. In previous work, we found that brain-derived extracellular vesicles (BDEVs) released from the injured brain can induce systemic coagulation with a widespread fibrin deposition in the microvasculature of the lungs, kidney, and heart in a mouse model of TBI. In this study, we investigated whether BDEVs can induce heart, lung, liver, and kidney injury in TBI mice. The results of pathological staining and related biomarkers indicated that BDEVs can induce histological damage and systematic dysfunction. In vivo imaging system demonstrated that BDEVs can gather in systemic organs. We also found that BDEVs could induce cell apoptosis in the lung, liver, heart, and kidney. Furthermore, we discovered that BDEVs could cause multi-organ endothelial cell damage. Finally, this secondary multi-organ damage could be relieved by removing circulating BDEVs. Our research provides a novel perspective and potential mechanism of TBI-associated multi-organ damage.

Evaluation of Liver Graft Donation After Euthanasia

Importance

The option of donating organs after euthanasia is not well known. Assessment of the results of organ transplants with grafts donated after euthanasia is essential to justify the use of this type of organ donation.

Objectives

To assess the outcomes of liver transplants (LTs) with grafts donated after euthanasia (donation after circulatory death type V [DCD-V]), and to compare them with the results of the more commonly performed LTs with grafts from donors with a circulatory arrest after the withdrawal of life-supporting treatment (type III [DCD-III]).

Design, Setting, and Participants

This retrospective multicenter cohort study analyzed medical records and LT data for most transplant centers in the Netherlands and Belgium. All LTs with DCD-V grafts performed from the start of the donation after euthanasia program (September 2012 for the Netherlands, and January 2005 for Belgium) through July 1, 2018, were included in the analysis. A comparative cohort of patients who received DCD-III grafts was also analyzed. All patients in both cohorts were followed up for at least 1 year. Data analysis was performed from September 2019 to December 2019.

Exposures

Liver transplant with either a DCD-V graft or DCD-III graft.

Main Outcomes and Measures

Primary outcomes were recipient and graft survival rates at years 1, 3, and 5 after the LT. Secondary outcomes included postoperative complications (early allograft dysfunction, hepatic artery thrombosis, and nonanastomotic biliary strictures) within the first year after the LT.

Results

Among the cohort of 47 LTs with DCD-V grafts, 25 organ donors (53%) were women and the median (interquartile range [IQR]) age was 51 (44-59) years. Among the cohort of 542 LTs with DCD-III grafts, 335 organ donors (62%) were men and the median (IQR) age was 49 (37-57) years. Median (IQR) follow-up was 3.8 (2.1-6.3) years. In the DCD-V cohort, 30 recipients (64%) were men, and the median (IQR) age was 56 (48-64) years. Recipient survival in the DCD-V cohort was 87% at 1 year, 73% at 3 years, and 66% at 5 years after LT. Graft survival among recipients was 74% at 1 year, 61% at 3 years, and 57% at 5 years after LT. These survival rates did not differ statistically significantly from those in the DCD-III cohort. Incidence of postoperative complications did not differ between the groups. For example, the occurrence of early allograft dysfunction after the LT was found to be 13 (31%) in the DCD-V cohort and 219 (45%) in the DCD-III cohort. The occurrence of nonanastomotic biliary strictures after the LT was found to be 7 (15%) in the DCD-V cohort and 83 (15%) in the DCD-III cohort.

Conclusions and Relevance

The findings of this cohort study suggest that LTs with DCD-V grafts yield similar outcomes as LTs with DCD-III grafts; therefore, grafts donated after euthanasia may be a justifiable option for increasing the organ donor pool. However, grafts from these donations should be considered high-risk grafts that require an optimal donor selection process and logistics.

The Hepatoprotective mechanisms of 17β-estradiol after traumatic brain injury in male rats: Classical and non-classical estrogen receptors

Protective effects of estrogen (E2) on traumatic brain injury (TBI) have been determined. In this study, the hepatoprotective effects of E2 after TBI through its receptors and oxidative stress regulation have been evaluated. Diffuse TBI induced by the Marmarou method in male rats. G15, PHTPP, MPP, and ICI182-780 as selective antagonists of E2 were injected before TBI. The results indicated that TBI induces a significant increase in liver enzymes [Alkaline phosphatase (ALP), Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Glutamyl transferase (GGT)], and oxidants levels [Malondialdehyde (MDA), Nitric oxide (NO)] and decreases in antioxidant biomarkers [Glutathione peroxidase (GPx) and Superoxide dismutase (SOD)] in the brain and liver, and plasma. We also found that E2 significantly preserved levels of these biomarkers and enzymatic activity. All antagonists inhibited the effects of E2 on increasing SOD and GPx. Also, the effects of E2 on brain MDA levels were inhibited by all antagonists, but in the liver, only ICI + G15 + E2 + TBI group was affected. The impacts of E2 on brain and liver and plasma NO levels were inhibited by all antagonists. The current findings demonstrated that E2 probably improved liver injury after TBI by modulating oxidative stress. Also, both classic (ERβ, ERα) and non-classic [G protein-coupled estrogen receptor (GPER)] receptors are affected in the protective effects of E2.

Alterations in Peripheral Organs following Combined Hypoxemia and Hemorrhagic Shock in a Rat Model of Penetrating Ballistic-Like Brain Injury

Polytrauma, with combined traumatic brain injury (TBI) and systemic damage are common among military and civilians. However, the pathophysiology of peripheral organs following polytrauma is poorly understood. Using a rat model of TBI combined with hypoxemia and hemorrhagic shock, we studied the status of peripheral redox systems, liver glycogen content, creatinine clearance, and systemic inflammation. Male Sprague-Dawley rats were subjected to hypoxemia and hemorrhagic shock insults (HH), penetrating ballistic-like brain injury (PBBI) alone, or PBBI followed by hypoxemia and hemorrhagic shock (PHH). Sham rats received craniotomy only. Biofluids and liver, kidney, and heart tissues were collected at 1 day, 2 days, 7 days, 14 days, and 28 days post-injury (DPI). Creatinine levels were measured in both serum and urine. Glutathione levels, glycogen content, and superoxide dismutase (SOD) and cytochrome C oxidase enzyme activities were quantified in the peripheral organs. Acute inflammation marker serum amyloid A-1 (SAA-1) level was quantified using western blot analysis. Urine to serum creatinine ratio in PHH group was significantly elevated on 7-28 DPI. Polytrauma induced a delayed disruption of the hepatic GSH/GSSG ratio, which resolved within 2 weeks post-injury. A modest decrease in kidney SOD activity was observed at 2 weeks after polytrauma. However, neither PBBI alone nor polytrauma changed the mitochondrial cytochrome C oxidase activity. Hepatic glycogen levels were reduced acutely following polytrauma. Acute inflammation marker SAA-1 showed a significant increase at early time-points following both systemic and brain injury. Overall, our findings demonstrate temporal cytological/tissue level damage to the peripheral organs due to combined PBBI and systemic injury.

Inhibition of Cerebral High-Mobility Group Box 1 Protein Attenuates Multiple Organ Damage and Improves T Cell-Mediated Immunity in Septic Rats

Sepsis remains one of the leading causes of mortality in intensive care units, but there is a shortage of effective treatments. A dysregulated host immune response and multiple organ injury are major factors for the pathogenesis and progression of sepsis, which require specific mechanism and treatment. In the present study, we performed an intracerebroventricular (ICV) injection of BoxA, a specific antagonist of high-mobility group box 1 protein (HMGB1), in septic rats that were produced by cecal ligation and puncture surgery; we further assessed the functional changes of multiple organs and splenic T lymphocytes. We found that the inhibition of cerebral HMGB1 significantly alleviated multiple organ damage under septic exposure, including damage to the heart, liver, lungs, and kidneys; reversed the immune dysfunction of T cells; and increased the survival of septic rats. These data suggest that central HMGB1 might be a potential therapeutic target for septic challenge and that inhibition of brain HMGB1 can protect against multiple organ dysfunction induced by sepsis.

Hepatic alterations are accompanied by changes to bile acid transporter-expressing neurons in the hypothalamus after traumatic brain injury

Annually, there are over 2 million incidents of traumatic brain injury (TBI) and treatment options are non-existent. While many TBI studies have focused on the brain, peripheral contributions involving the digestive and immune systems are emerging as factors involved in the various symptomology associated with TBI. We hypothesized that TBI would alter hepatic function, including bile acid system machinery in the liver and brain. The results show activation of the hepatic acute phase response by 2 hours after TBI, hepatic inflammation by 6 hours after TBI and a decrease in hepatic transcription factors, Gli 1, Gli 2, Gli 3 at 2 and 24 hrs after TBI. Bile acid receptors and transporters were decreased as early as 2 hrs after TBI until at least 24 hrs after TBI. Quantification of bile acid transporter, ASBT-expressing neurons in the hypothalamus, revealed a significant decrease following TBI. These results are the first to show such changes following a TBI, and are compatible with previous studies of the bile acid system in stroke models. The data support the emerging idea of a systemic influence to neurological disorders and point to the need for future studies to better define specific mechanisms of action.

Fractalkine suppression during hepatic encephalopathy promotes neuroinflammation in mice

Background

Acute liver failure is associated with numerous systemic consequences including neurological dysfunction, termed hepatic encephalopathy, which contributes to mortality and is a challenge to manage in the clinic. During hepatic encephalopathy, microglia activation and neuroinflammation occur due to dysregulated cell signaling and an increase of toxic metabolites in the brain. Fractalkine is a chemokine that is expressed primarily in neurons and through signaling with its receptor CX3CR1 on microglia, leads to microglia remaining in a quiescent state. Fractalkine is often suppressed during neuropathies that are characterized by neuroinflammation. However, the expression and subsequent role of fractalkine on microglia activation and the pathogenesis of hepatic encephalopathy due to acute liver failure is unknown.

Methods

Hepatic encephalopathy was induced in mice via injection of azoxymethane (AOM) or saline for controls. Subsets of these mice were implanted with osmotic minipumps that infused soluble fractalkine or saline into the lateral ventricle of the brain. Neurological decline and the latency to coma were recorded in these mice, and brain, serum, and liver samples were collected. Neurons or microglia were isolated from whole brain samples using immunoprecipitation. Liver damage was assessed using hematoxylin and eosin staining and by measuring serum liver enzyme concentrations. Fractalkine and CX3CR1 expression were assessed by real-time PCR, and proinflammatory cytokine expression was assessed using ELISA assays.

Results

Following AOM administration, fractalkine expression is suppressed in the cortex and in isolated neurons compared to vehicle-treated mice. CX3CR1 is suppressed in isolated microglia from AOM-treated mice. Soluble fractalkine infusion into the brain significantly reduced neurological decline in AOM-treated mice compared to saline-infused AOM-treated mice. Infusion of soluble fractalkine into AOM-treated mice reduced liver damage, lessened microglia activation, and suppressed expression of chemokine ligand 2, interleukin-6, and tumor necrosis factor alpha compared to saline-infused mice.

Conclusions

These findings suggest that fractalkine-mediated signaling is suppressed in the brain following the development of hepatic encephalopathy. Supplementation of AOM-treated mice with soluble fractalkine led to improved outcomes, which identifies this pathway as a possible therapeutic target for the management of hepatic encephalopathy following acute liver injury.