Hyperbaric oxygen therapy aggravates liver reperfusion injury in rats

TNFα is a key trigger of inflammation in diet-induced non-obese MASLD in mice

Tumor necrosis factor alpha (TNFα) is thought to be a critical factor in the development of metabolic dysfunction-associated steatotic liver disease (MASLD). Here, we determined the effects of a treatment with the anti-TNFα antibody infliximab and a genetic deletion of TNFα, respectively, in the development of non-obese diet-induced early metabolic dysfunction-associated steatohepatitis (MASH) in mice. The treatment with infliximab improved markers of liver damage in mice with pre-existing early MASH. In TNFα-/- mice, the development of early signs of MASH and insulin resistance was significantly attenuated compared to wild-type animals. While mRNA expression of proinflammatory cytokines like interleukin 1β (Il1b) and interleukin 6 (Il6) were significantly lower in livers of MASH-diet-fed TNFα-/- mice compared to wild-type mice with early MASH, markers of intestinal barrier function were similarly impaired in both MASH-diet-fed groups compared to controls. Our data suggest that TNFα is a key regulator of hepatic inflammation and insulin resistance associated with the development of early non-obese MASH.

Fortifying Butterfat with Soybean Oil Attenuates the Onset of Diet-Induced Non-Alcoholic Steatohepatitis and Glucose Intolerance

The addition of plant oils such as soybean oil (S) to a diet rich in saturated fatty acids is discussed as a possible route to prevent or diminish the development of metabolic disease. Here, we assessed whether a butterfat-rich diet fortified with S affects the development of early non-alcoholic steatohepatitis (NASH) and glucose intolerance. Female C57BL/6J mice were fed a standard-control diet (C); a fat-, fructose-, and cholesterol-rich diet (FFC, 25E% butterfat, 50% (wt./wt.) fructose, 0.16% (wt./wt.) cholesterol); or FFC supplemented with S (FFC + S, 21E% butterfat + 4E% S) for 13 weeks. Indicators of liver damage, inflammation, intestinal barrier function, and glucose metabolism were measured. Lipopolysaccharide (LPS)-challenged J774A.1 cells were incubated with linolenic and linoleic acids (ratio 1:7.1, equivalent to S). The development of early NASH and glucose intolerance was significantly attenuated in FFC + S–fed mice compared to FFC-fed mice associated with lower hepatic toll-like receptor-4 mRNA expression, while markers of intestinal barrier function were significantly higher than in C-fed mice. Linolenic and linoleic acid significantly attenuated LPS-induced formation of reactive nitrogen species and interleukin-1 beta mRNA expression in J774A.1 cells. Our results indicate that fortifying butterfat with S may attenuate the development of NASH and glucose intolerance in mice.

Hyperbaric Oxygen Therapy in Liver Diseases

Hyperbaric oxygen therapy (HBOT) is an efficient therapeutic option to improve progress of lots of diseases especially hypoxia-related injuries, and has been clinically established as a wide-used therapy for patients with carbon monoxide poisoning, decompression sickness, arterial gas embolism, problematic wound, and so on. In the liver, most studies positively evaluated HBOT as a potential therapeutic option for liver transplantation, acute liver injury, nonalcoholic steatohepatitis, fibrosis and cancer, especially for hepatic artery thrombosis. This might mainly attribute to the anti-oxidation and anti-inflammation of HBOT. However, some controversies are existed, possibly due to hyperbaric oxygen toxicity. This review summarizes the current understandings of the role of HBOT in liver diseases and hepatic regeneration. Future understanding of HBOT in clinical trials and its in-depth mechanisms may contribute to the development of this novel adjuvant strategy for clinical therapy of liver diseases.

Oral Supplementation of Glutamine Attenuates the Progression of Nonalcoholic Steatohepatitis in C57BL/6J Mice

Background: Universally accepted therapeutic strategies for the treatment of nonalcoholic steatohepatitis (NASH) are still lacking. Studies suggest a preventive effect of oral Gln supplementation on the development of NASH; however, whether Gln also has therapeutic potential for pre-existing NASH has not yet been clarified.Objective: The aim of the present study was to determine whether Gln prevents the progression of diet-induced NASH in mice.Methods: For 8 wk, female C57BL/6J mice (6-8 wk old) were pair-fed a liquid Western-style diet [WSD, 25% of energy from fat, 50% wt:wt fructose, 0.16% wt:wt cholesterol] or control diet (C diet) to induce liver damage. From week 8 to 13, they were pair-fed the C diet or WSD alone or supplemented with l-Gln to provide 2.1 g/kg body weight (C diet + Gln or WSD + Gln). Energy intake was adjusted to the group with the lowest energy intake. Indexes of liver damage and inflammation, intestinal barrier function, and toll-like receptor 4 (Tlr4) signaling in the liver were determined.Results: The liver histology scores significantly increased from 8 to 13 wk (+31%) in WSD-fed mice and were significantly higher than in controls (P ≤ 0.05 for both time comparisons), whereas scores did not differ between C diet-fed and WSD + Gln-fed mice after 13 wk of feeding. The occludin protein concentrations in the small intestinal tissue were similarly reduced in both WSD-fed groups when compared with controls [WSD compared with C diet (-53%) and C diet + Gln (-42%), P ≤ 0.05; WSD + Gln compared with C diet + Gln (-34%), P ≤ 0.05] after 13 wk, whereas the expression of myeloid differentiation primary response gene 88 mRNA and concentration of inducible nitric oxide synthase and 4-hydroxynonenal protein adducts were significantly higher only in livers of WSD-fed mice (P ≤ 0.05 for the WSD group compared with all other groups; WSD + Gln group compared with the C diet groups: NS).Conclusion: Taken together, our data suggest that oral Gln supplementation protects mice from the progression of pre-existing, WSD-induced NASH.

Treatment with alpha-galactosylceramide protects mice from early onset of nonalcoholic steatohepatitis: Role of intestinal barrier function

SCOPE

The role of invariant natural killer T cells in the development of nonalcoholic steatohepatitis (NASH) has not yet been fully understood. Here, the effect of the invariant natural killer T-cell activator alpha-galactosylceramide (αGalCer) on the development of nonalcoholic fatty liver disease and intestinal barrier function was assessed in a mouse model of early Western-style diet (WSD) induced NASH.

METHODS AND RESULTS

Female C57BL/6J mice were either fed a liquid control diet or a liquid fructose-enriched WSD for 6 wk while being treated three times weekly with αGalCer (2 μg intraperitoneal) or vehicle. Indices of liver damage, glucose metabolism, and intestinal permeability were measured. Treatment with αGalCer markedly suppressed hepatic fat accumulation and inflammation while not affecting fasting glucose. The protective effects of αGalCer were associated with a protection against the increased translocation of bacterial endotoxins and the decreased protein levels of tight junction proteins occludin and zonula occludens 1 found in vehicle-treated mice while being fed a WSD.

CONCLUSION

Taken together, our data suggest that the protective effects of αGalCer against the development of a diet-induced NASH in mice are associated with a protection against the increased translocation of intestinal bacterial endotoxins associated with the development of NASH.

Hyperbaric oxygen and hyperbaric air preconditioning induces ischemic tolerance to transient forebrain ischemia in the gerbil

Ischemic preconditioning with sublethal stress triggers defensive mechanisms against ischemic brain damage; however, such manipulations are potentially dangerous and, therefore, safe stimuli have been sought. Hyperoxia preconditioning by administration of hyperbaric (HBO) or normobaric oxygen (NBO) may have neuroprotective potential. The aim of this study was to determine whether preconditioning with HBO and air (HBA) applied at 2.5 absolute pressure (ATA) or NBO preconditioning induces ischemic tolerance in the brain of gerbils subjected to 3min transient cerebral ischemia. Neuronal cell survival, changes in brain temperature, the generation of factors involved in neurodegeneration and basic behavior in nest building were all tested. Hyperoxic preconditioning prevented ischemia-induced neuronal cell loss, reduced the number of TUNEL positive cells in the CA1 region of the hippocampus and improved the nest building process compared to untreated ischemic animals. Preconditioning also suppressed the production of reactive oxygen species and increased Bax expression normally observed after an ischemic episode. Only HBO preconditioning inhibited ischemia-evoked increases in brain temperature. Our results show that hyperoxic preconditioning results in induction of ischemic tolerance and prevents ischemia-induced neuronal damage in the gerbil brain. Pressurized air preconditioning was as effective as HBO or NBO preconditioning in providing neuroprotection. The observed neuroprotection probably results from mild oxidative stress evoked by increased brain tissue oxidation and activation of antioxidant and antiapoptotic defenses.

Effect of hyperbaric hepatic hyperoxia on the liver of rats submitted to intermittent ischemia/reperfusion injury

PURPOSE

To determine the effect of hyperbaric hyperoxia as hepatic preconditioning on hepatocellular integrity in rats submitted to intermittent hepatic ischemia/reperfusion injury.

METHODS

Twenty male Wistar rats were divided into 4 groups (SHAM, I/R, HBO-I/R and CONTROL). The surgical technique consisted of total clamping of the hepatic pedicle for 15 min, followed by reperfusion for 5 min, performed twice. The application of hyperbaric oxygen (HBO) was carried out in a collective chamber (simultaneous exposure of 4 rats) pressurized directly with oxygen at 2 ATA for 60 min. Tissue malondialdehyde (MDA) levels were determined and blood samples were collected for the determination of serum AST and ALT levels. Data were analyzed statistically by the Mann-Whitney test, with the level of significance set at p < 0.05.

RESULTS

A statistically significant difference in MDA (p< 0.05) was observed between control and HBO-I/R, but not between control and I/R. Regarding AST, there was a difference between control and I/R and HBO-I/R. Analysis of ALT revealed a significant difference between control and I/R (p<0.05) and between I/R and HBO-I/R, with no difference between control and HBO-IR.

CONCLUSION

Hyperoxic preconditioning proved to be favorable regarding alanine transaminase, but not aspartate aminotranserase or malondialdehyde levels.

Hyperoxic preconditioning in partial liver ischemia

PURPOSE

To evaluate the effect of the hyperbaric oxygen (HBO) treatment as a pre-conditioning for I/R effects in the liver ischemia.

METHODS

Fifty-seven male Wistar rats (260-300g) were submitted to the following procedures: SHAM; I/R, rats submitted to I/R, consisting of partial ischemia of 70% of the liver for 90 minutes followed by 15 minutes of reperfusion; HBO I/R 1 ATA, 30 minutes of HBO treatment at the pressure of 1 absolute atmosphere (ATA) during the ischemia time. HBO I/R 2 ATA, 30 minutes of HBO (2 ATA) during the ischemia time. Pre HBO I/R 30', rats submitted to 30 minutes of HBO (2 ATA) immediately before the I/R time. Pre HBO I/R 90', rats submitted to 90 minutes of HBO (2 ATA) immediately before the I/R time.

RESULTS

There was a significant worsening of all the parameters of mitochondrial energy production (state 3, 4, RCR and Swelling) in the I/R group, when compared to the Sham group (I/R <Sham, p<0.05). There was also a significant worsening in state 4, RCR and mitochondrial edema in the Pre HBO I/R 90' group compared to the I/R group. Hepatic enzyme concentrations were significantly higher in the I/R group.

CONCLUSION

The use of hyperbaric oxygen before and during I/R did not improve the production of hepatocellular energy reduced by I/R, nor did it prevent the installation of mitochondrial edema induced by Iischemia/reperfusion.

Effects of hyperbaric oxygen (HBO), as pre-conditioning in liver of rats submitted to periodic liver ischemia/reperfusion

PURPOSE

to assess the effect of hyperbaric oxygen (HBO) as pre-conditioning on periodic liver ischemia/reperfusion injury.

METHODS

Thirty-six male Wistar rats were divided into 4 groups (SHAM, I/R , HBO-I/R and CONTROL). The surgical technique consisted of total clamping of the hepatic pedicle for 15 min followed by twice repeated reperfusion for 5 min (unclamping). HBO was applied in a collective chamber (simultaneous exposure of 4 rats) directly pressurized with oxygen at 2 ATA for 60 min. Hepatic mitochondrial function was determined using samples of the median lobe obtained after exactly 5 min of reperfusion for the analysis of mitochondrial respiration based on the determination of states 3 and 4, the respiratory control ratio and the transition of mitochondrial permeability (mitochondrial swelling).Data were analyzed by the Mann-Whitney test and the level of significance was set at p < 0.05.

RESULTS

There was a statistically significant difference (p < 0.05) in state 3 between the CONTROL and I/R and HBO-I/R groups, in state 4 between the CONTROL and I/R and HBO-I/R groups; in respiratory control ratio (RCR) between the CONTROL and I/R and HBO-I/R groups and between the CONTROL and Sham groups, and in mitochondrial swelling between the CONTROL and I/R and HBO-/R groups and between the Sham and I/R and HBO-I/R groups.

CONCLUSION

In this process of periodic ischemia and reperfusion, hyperbaric pre-conditioning did not improve significantly hepatic mitochondrial function.

Effect of hyperbaric oxygen therapy on liver function during intermittent ischemia

PURPOSE: To analyze the effects of hyperbaric oxygen therapy on liver function in rats previously subjected to ischemia and reperfusion. METHODS: A randomly distribution of 23 Wistar rats was conducted into three groups: SHAM, animals subjected to surgical stress without restricting blood flow by clamping the hepatic pedicle, IR, rats underwent hepatic vascular occlusion intermittently for two complete cycles of 15 minutes of ischemia followed by 5 min of reperfusion, IR / HBO, rats underwent hepatic pedicle clamping and thereafter exposed to hyperbaric oxygen pressure of 2 absolute atmospheres for 60 minutes. We evaluated liver function through mitochondrial function, determined by the stages 3 and 4 of respiration, respiratory control ratio (RCR) and mitochondrial permeability transition (Swelling). Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were also quantified . We analyzed the results using the Mann-Whitney test and were considered significant all results with p <0.05. RESULTS: There were significant differences between the results of stage 3 in SHAM vs IR group ; of the stage 4 in the groups IR vs SHAM and SHAM vs IR /HBO; of the Respiratory Control Ratio (RCR) in the group IR vs IR / HBO ; of alanine aminotransferase in the groups IR vs SHAM , SHAM vs IR/HBO and IR vs IR / HBO; aspartate aminotransferase in the groups SHAM vs IR and SHAM vs IR / HBO. CONCLUSION: The whole analysis of the mitochondiral function indicators permits us to conclude that the hyperbaric oxygen therapy acted as a protective agent of the mitochondrial function, minimizing the ischemia-reperfusion injury of the hepatic parenchyma.

Predictors of carbon monoxide poisoning-induced delayed neuropsychological sequelae

OBJECTIVE

Carbon monoxide poisoning (COP) commonly results in delayed neuropsychological sequelae (DNS). The aim of the article is to demonstrate the clinical characteristics and potential predictors of COP-induced DNS later.

METHOD

Retrospective medical record review was performed for patients who had COP in the past year at a National Medical Center in Taiwan. Sixty patients with COP were registered during a one-year period. Fifty-six of them (93.3%) were COP because of suicide attempt. Patients with COP who have a complete medical record of carboxyhemoglobin (COHb) and Glasgow Coma Scale (GCS) and Mini-Mental Status Examination (MMSE) scores were recruited. Multiple regression analysis was performed to search for the predictive factors of DNS.

RESULTS

Forty-three patients were recruited. Most had attempted suicide (93.0%) using CO, and thirteen developed DNS later. A longer duration of admission, more sessions of hyperbaric oxygen therapy, and positive findings in brain computed tomography (CT) scans were more often found in patients with DNS than those without DNS. The GCS and MMSE scores and positive findings in brain CT scans were associated with the development of DNS but COHb was not.

CONCLUSIONS

Our results identified several potential predictors of DNS. This finding may help clinicians understand and treat COP patients efficiently.