Adipose tissue protects against sepsis-induced muscle weakness in mice: from lipolysis to ketones.

BACKGROUND: ICU-acquired weakness is a debilitating consequence of prolonged critical illness that is associated with poor outcome. Recently, premorbid obesity has been shown to protect against such illness-induced muscle wasting and weakness. Here, we hypothesized that this protection was due to increased lipid and ketone availability. METHODS: In a centrally catheterized, fluid-resuscitated, antibiotic-treated mouse model of prolonged sepsis, we compared markers of lipolysis and fatty acid oxidation in lean and obese septic mice (n = 117). Next, we compared markers of muscle wasting and weakness in septic obese wild-type and adipose tissue-specific ATGL knockout (AAKO) mice (n = 73), in lean septic mice receiving either intravenous infusion of lipids or standard parenteral nutrition (PN) (n = 70), and in lean septic mice receiving standard PN supplemented with either the ketone body 3-hydroxybutyrate or isocaloric glucose (n = 49). RESULTS: Obese septic mice had more pronounced lipolysis (p ≤ 0.05), peripheral fatty acid oxidation (p ≤ 0.05), and ketogenesis (p ≤ 0.05) than lean mice. Blocking lipolysis in obese septic mice caused severely reduced muscle mass (32% loss vs. 15% in wild-type, p < 0.001) and specific maximal muscle force (59% loss vs. 0% in wild-type; p < 0.001). In contrast, intravenous infusion of lipids in lean septic mice maintained specific maximal muscle force up to healthy control levels (p = 0.6), whereas this was reduced with 28% in septic mice receiving standard PN (p = 0.006). Muscle mass was evenly reduced with 29% in both lean septic groups (p < 0.001). Lipid administration enhanced fatty acid oxidation (p ≤ 0.05) and ketogenesis (p < 0.001), but caused unfavorable liver steatosis (p = 0.01) and a deranged lipid profile (p ≤ 0.01). Supplementation of standard PN with 3-hydroxybutyrate also attenuated specific maximal muscle force up to healthy control levels (p = 0.1), but loss of muscle mass could not be prevented (25% loss in both septic groups; p < 0.001). Importantly, this intervention improved muscle regeneration markers (p ≤ 0.05) without the unfavorable side effects seen with lipid infusion. CONCLUSIONS: Obesity-induced muscle protection during sepsis is partly mediated by elevated mobilization and metabolism of endogenous fatty acids. Furthermore, increased availability of ketone bodies, either through ketogenesis or through parenteral infusion, appears to protect against sepsis-induced muscle weakness also in the lean.

Amino acid supplements in critically ill patients.

Observational studies have associated a low amino acid intake with adverse outcome of critical illness. Although this finding could theoretically be explained by differences in feeding tolerance related to illness severity, guidelines have recommended to administer sufficient amounts of amino acids from early onwards in the disease course. Recently, however, several high quality randomized controlled trials have not shown benefit by early amino acid supplementation and some trials even found potential harm, thus questioning this recommendation. These negative results could be related to amino acid-induced suppression of autophagy, to the inability to suppress bulk catabolism by exogenous amino acids, or to the administration of an amino acid mixture with an inappropriate composition. Currently, there is no evidence supporting administration of individual amino acid supplements during critical illness and glutamine administration may be harmful. The optimal timing, dose and composition of the amino acid mixture for critically ill patients remain unclear.

Role of glucagon in protein catabolism.

PURPOSE OF REVIEW: Glucagon is known as a key hormone in the control of glucose and amino acid metabolism. Critical illness is hallmarked by a profound alteration in glucose and amino acid metabolism, accompanied by muscle wasting and hypoaminoacidemia. Here we review novel insights in glucagon (patho)physiology and discuss the recently discovered role of glucagon in controlling amino acid metabolism during critical illness. RECENT FINDINGS: The role of glucagon in glucose metabolism is much more complex than originally anticipated, and glucagon has shown to be a key player in amino acid metabolism. During critical illness, the contribution of glucagon in bringing about hyperglycemia appeared to be quite limited, whereas increased glucagon availability seems to contribute importantly to the typical hypoaminoacidemia via stimulating hepatic amino acid breakdown, without affecting muscle wasting. Providing amino acids further increases hepatic amino acid breakdown, mediated by a further increase in glucagon. SUMMARY: Glucagon plays a crucial role in amino acid metabolism during critical illness, with an apparent feedback loop between glucagon and circulating amino acids. Indeed, elevated glucagon may, to a large extent, be responsible for the hypoaminoacidemia in the critically ill and infusing amino acids increases glucagon-driven amino acid breakdown in the liver. These novel insights further question the rationale for amino acid administration during critical illness.

Role of Glucagon in Catabolism and Muscle Wasting of Critical Illness and Modulation by Nutrition.

RATIONALE: Critical illness is hallmarked by muscle wasting and disturbances in glucose, lipid, and amino acid homeostasis. Circulating concentrations of glucagon, a catabolic hormone that affects these metabolic pathways, are elevated during critical illness. Insight in the nutritional regulation of glucagon and its metabolic role during critical illness is lacking. OBJECTIVES: To evaluate whether macronutrient infusion can suppress plasma glucagon during critical illness and study the role of illness-induced glucagon abundance in the disturbed glucose, lipid, and amino acid homeostasis and in muscle wasting during critical illness. METHODS: In human and mouse studies, we infused macronutrients and manipulated glucagon availability up and down to investigate its acute and chronic metabolic role during critical illness. MEASUREMENTS AND MAIN RESULTS: In critically ill patients, infusing glucose with insulin did not lower glucagon, whereas parenteral nutrition containing amino acids increased glucagon. In critically ill mice, infusion of amino acids increased glucagon and up-regulated markers of hepatic amino acid catabolism without affecting muscle wasting. Immunoneutralizing glucagon in critically ill mice only transiently affected glucose and lipid metabolism, did not affect muscle wasting, but drastically suppressed markers of hepatic amino acid catabolism and reversed the illness-induced hypoaminoacidemia. CONCLUSIONS: These data suggest that elevated glucagon availability during critical illness increases hepatic amino acid catabolism, explaining the illness-induced hypoaminoacidemia, without affecting muscle wasting and without a sustained impact on blood glucose. Furthermore, amino acid infusion likely results in a further breakdown of amino acids in the liver, mediated by increased glucagon, without preventing muscle wasting. Clinical trial registered with www.clinicaltrials.gov (NCT 00512122).

Mitochondrial and endoplasmic reticulum dysfunction and related defense mechanisms in critical illness-induced multiple organ failure.

Patients with critical illness-induced multiple organ failure suffer from a very high morbidity and mortality, despite major progress in intensive care. The pathogenesis of this condition is complex and incompletely understood. Inadequate tissue perfusion and an overwhelming inflammatory response with pronounced cellular damage have been suggested to play an important role, but interventions targeting these disturbances largely failed to improve patient outcome. Hence, new therapeutic perspectives are urgently needed. Cellular dysfunction, hallmarked by mitochondrial dysfunction and endoplasmic reticulum stress, is increasingly recognized as an important contributor to the development of organ failure in critical illness. Several cellular defense mechanisms are normally activated when the cell is in distress, but may fail or respond insufficiently to critical illness. This insight may open new therapeutic options by stimulating these cellular defense mechanisms. This review summarizes the current understanding of the role of mitochondrial dysfunction and endoplasmic reticulum stress in critical illness-induced multiple organ failure and gives an overview of the corresponding cellular defense mechanisms. Therapeutic perspectives based on these cellular defense mechanisms are discussed. This article is part of a Special Issue entitled: Immune and Metabolic Alterations in Trauma and Sepsis edited by Dr. Raghavan Raju.

The effect of spinal versus general anaesthesia on perioperative muscle weakness in patients having bilateral total hip arthroplasty: a single center randomized clinical trial.

BACKGROUND: Perioperative neuro-endocrine stress response may contribute to acquired muscle weakness. Regional anaesthesia has been reported to improve the outcome of patients having total hip arthroplasty. In this study, it was hypothesized that spinal anaesthesia (SA) decreases the perioperative neuro-endocrine stress response and perioperatively acquired muscle weakness (PAMW), as compared to general anaesthesia (GA). METHODS: Fifty subjects undergoing bilateral total hip arthroplasty (THA) were randomly allocated to receive a standardized SA (n = 25) or GA (n = 25). Handgrip strength was assessed preoperatively, on the first postoperative day (primary endpoint) and on day 7 and 28. Respiratory muscle strength was measured by maximal inspiratory pressure (MIP). Stress response was assessed by measuring levels of Adrenocorticotropic hormone (ACTH), cortisol and interleukin-6 (IL-6). RESULTS: Handgrip strength postoperatively (day 1) decreased by 5.4 ± 15.9% in the SA group, versus 15.2 ± 11.7% in the GA group (p = 0.02). The handgrip strength returned to baseline at day 7 and did not differ between groups at day 28. MIP increased postoperatively in patients randomized to SA by 11.7 ± 48.3%, whereas it decreased in GA by 12.2 ± 19.9% (p = 0.04). On day 7, MIP increased in both groups, but more in the SA (49.0 ± 47.8%) than in the GA group (14.2 ± 32.1%) (p = 0.006). Postoperatively, the levels of ACTH, cortisol and IL-6 increased in the GA, but not in the SA group (p < 0.004). CONCLUSION: In patients having bilateral THA, SA preserved the postoperative respiratory and peripheral muscle strength and attenuated the neuro-endocrine and inflammatory responses. TRIAL REGISTRATION: clinicaltrials.gov NCT03600454.

Development of muscle weakness in a mouse model of critical illness: does fibroblast growth factor 21 play a role?

BACKGROUND: Critical illness is hallmarked by severe stress and organ damage. Fibroblast growth factor 21 (FGF21) has been shown to rise during critical illness. FGF21 is a pleiotropic hormone that mediates adaptive responses to tissue injury and repair in various chronic pathological conditions. Animal studies have suggested that the critical illness-induced rise in FGF21 may to a certain extent protect against acute lung, liver, kidney and brain injury. However, FGF21 has also been shown to mediate fasting-induced loss of muscle mass and force. Such loss of muscle mass and force is a frequent problem of critically ill patients, associated with adverse outcome. In the present study, we therefore investigated whether the critical illness-induced acute rise in FGF21 is muscle-protective or rather contributes to the pathophysiology of critical illness-induced muscle weakness. METHODS: In a catheterised mouse model of critical illness induced by surgery and sepsis, we first assessed the effects of genetic FGF21 inactivation, and hence the inability to acutely increase FGF21, on survival, body weight, muscle wasting and weakness, and markers of muscle cellular stress and dysfunction in acute (30 h) and prolonged (5 days) critical illness. Secondly, we assessed whether any effects were mirrored by supplementing an FGF21 analogue (LY2405319) in prolonged critical illness. RESULTS: FGF21 was not required for survival of sepsis. Genetic FGF21 inactivation aggravated the critical illness-induced body weight loss (p = 0.0003), loss of muscle force (p = 0.03) and shift to smaller myofibers. This was accompanied by a more pronounced rise in markers of endoplasmic reticulum stress in muscle, without effects on impairments in mitochondrial respiratory chain enzyme activities or autophagy activation. Supplementing critically ill mice with LY2405319 did not affect survival, muscle force or weight, or markers of muscle cellular stress/dysfunction. CONCLUSIONS: Endogenous FGF21 is not required for sepsis survival, but may partially protect muscle force and may reduce cellular stress in muscle. Exogenous FGF21 supplementation failed to improve muscle force or cellular stress, not supporting the clinical applicability of FGF21 supplementation to protect against muscle weakness during critical illness.

Clinical and microbiological evaluation of temocillin for bloodstream infections with Enterobacterales: a Belgian single-centre retrospective study.

Background: Expanding the use of temocillin could be an important weapon in the fight against antimicrobial resistance. However, EUCAST defined clinical breakpoints for a limited number of species and only for urinary tract infections (UTI), including urosepsis but excluding severe sepsis and septic shock. Moreover, a dosage of 2 g q8h is advised in most cases. Objectives: Evaluation of temocillin use for the treatment of bacteraemia, correlating clinical and microbiological outcomes with infection site, infection severity, temocillin dosage, Enterobacterales species and MIC. Patients and methods: All adult patients with blood cultures positive for temocillin-susceptible Enterobacterales and treated with temocillin for ≥72 h from June 2018 until June 2021 were considered for inclusion. The primary outcome was clinical success, defined as resolution of infection signs, no relapse of the same infection and no antibiotic switch due to insufficient clinical improvement. The secondary outcome was microbiological success. Results: In total, 182 episodes were included [140 UTI versus 42 non-UTI, 171 Escherichia coli, Klebsiella species (except Klebsiella aerogenes) and Proteus mirabilis (EKPs) versus 11 non-EKPs]. Clinical and microbiological failure were low (8% and 3%, respectively). No difference in outcome was observed for dosages of 2 g q12h versus 2 g q8h, either for EKP versus non-EKP isolates or MIC values ≤8 versus 16 mg/L. Considering only bacteraemia episodes of UTI origin, using the 16 mg/L breakpoint, there was no difference in success rate between regimens of 2 g q12h and 2 g q8h. Conclusions: Temocillin 2 g q12h can be successfully used for the treatment of systemic UTI. Prospective studies are needed to assess outcomes and evaluate non-inferiority compared with other broad-spectrum antibiotics in non-UTI infections, including bacteraemia.

Population-wide persistent hemostatic changes after vaccination with ChAdOx1-S.

Various vaccines were developed to reduce the spread of the Severe Acute Respiratory Syndrome Cov-2 (SARS-CoV-2) virus. Quickly after the start of vaccination, reports emerged that anti-SARS-CoV-2 vaccines, including ChAdOx1-S, could be associated with an increased risk of thrombosis. We investigated the hemostatic changes after ChAdOx1-S vaccination in 631 health care workers. Blood samples were collected 32 days on average after the second ChAdOx1-S vaccination, to evaluate hemostatic markers such as D-dimer, fibrinogen, α2-macroglobulin, FVIII and thrombin generation. Endothelial function was assessed by measuring Von Willebrand Factor (VWF) and active VWF. IL-6 and IL-10 were measured to study the activation of the immune system. Additionally, SARS-CoV-2 anti-nucleoside and anti-spike protein antibody titers were determined. Prothrombin and fibrinogen levels were significantly reduced after vaccination (-7.5% and -16.9%, p < 0.0001). Significantly more vaccinated subjects were outside the normal range compared to controls for prothrombin (42.1% vs. 26.4%, p = 0.026) and antithrombin (23.9% vs. 3.6%, p = 0.0010). Thrombin generation indicated a more procoagulant profile, characterized by a significantly shortened lag time (-11.3%, p < 0.0001) and time-to-peak (-13.0% and p < 0.0001) and an increased peak height (32.6%, p = 0.0015) in vaccinated subjects compared to unvaccinated controls. Increased VWF (+39.5%, p < 0.0001) and active VWF levels (+24.1 %, p < 0.0001) pointed toward endothelial activation, and IL-10 levels were significantly increased (9.29 pg/mL vs. 2.43 pg/mL, p = 0.032). The persistent increase of IL-10 indicates that the immune system remains active after ChAdOx1-S vaccination. This could trigger a pathophysiological mechanism causing an increased thrombin generation profile and vascular endothelial activation, which could subsequently result in and increased risk of thrombotic events.

Alterations in adipose tissue during critical illness: An adaptive and protective response?

RATIONALE: Critical illness is characterized by lean tissue wasting, whereas adipose tissue is preserved. Overweight and obese critically ill patients may have a lower risk of death than lean patients, suggestive of a protective role for adipose tissue during illness. OBJECTIVES: To investigate whether adipose tissue could protectively respond to critical illness by storing potentially toxic metabolites, such as excess circulating glucose and triglycerides. METHODS: We studied adipose tissue morphology and metabolic activity markers in postmortem biopsies of 61 critically ill patients and 20 matched control subjects. Adipose morphology was also studied in in vivo biopsies of 27 patients and in a rabbit model of critical illness (n = 22). MEASUREMENTS AND MAIN RESULTS: Adipose tissue from critically ill patients revealed a higher number and a smaller size of adipocytes and increased preadipocyte marker levels as compared with control subjects. Virtually all adipose biopsies from critically ill patients displayed positive macrophage staining. The animal model demonstrated similar changes. Glucose transporter levels and glucose content were increased. Glucokinase expression was up-regulated, whereas glycogen and glucose-6-phosphate levels were low. Acetyl CoA carboxylase protein and fatty acid synthase activity were increased. Hormone-sensitive lipase activity was not altered, whereas lipoprotein lipase activity was increased. A substantially increased AMP-activated protein kinase activity may play a crucial role. CONCLUSIONS: Postmortem adipose tissue biopsies from critically ill patients displayed a larger number of small adipocytes in response to critical illness, revealing an increased ability to take up circulating glucose and triglycerides. Similar morphologic changes were present in vivo. Such changes may render adipose tissue biologically active as a functional storage depot for potentially toxic metabolites, thereby contributing to survival.

On the Role of Illness Duration and Nutrient Restriction in Cholestatic Alterations that Occur During Critical Illness.

BACKGROUND AND AIMS: Elevated markers of cholestasis are common in response to critical illness, and associated with adverse outcome. The role of illness duration and of nutrient restriction on underlying molecular pathways of such cholestatic responses have not been thoroughly investigated. METHODS: In a mouse model of surgery- and sepsis-induced critical illness, molecular pathways of cholestasis were investigated up to 7 days. To assess which changes are explained by illness-induced lack of feeding, nutrient-restricted healthy mice were studied and compared with ad libitum fed healthy mice. Furthermore, serum bile acid (BA) concentrations were quantified in 1,114 human patients with either short or long intensive care unit (ICU) stay, matched for type and severity of illness, up to ICU-day-7. RESULTS: In critically ill mice, either evoked by surgery or sepsis, circulating and hepatic BA-levels progressively increased with time from day-3 onward, preceded by unsuppressed or upregulated CYP7A1 and CYP27A1 protein expression. From 30 h onward, nuclear farnesoid-X-receptor-retinoid-X-receptor staining was significantly suppressed in both critically ill groups, followed from day-3 onward by decreased gene expression of the apical exporter BA-specific export pump and increased expression of basolateral exporters multidrug resistance-associated protein 3 (MRP3) and MRP4. Nutrient restriction in healthy mice only partly mirrored illness-induced alterations in circulating BA and BA-transporters, without changing nuclear receptors or synthesis markers expression. Also in human critically ill patients, serum BA increased with time in long-stay patients only, similarly for patients with or without sepsis. CONCLUSIONS: Circulating BA concentrations rose days after onset of sepsis- and surgery-induced, critical illness, only partially explained by lack of feeding, preceded by suppressed nuclear feedback-sensors and ongoing BA synthesis. Expression of transporters suggested ongoing reversed BA-flow toward the blood.

Use of a Central Venous Line for Fluids, Drugs and Nutrient Administration in a Mouse Model of Critical Illness.

This protocol describes a centrally catheterized mouse model of prolonged critical illness. We combine the cecal ligation and puncture method to induce sepsis with the use of a central venous line for fluids, drugs and nutrient administration to mimic the human clinical setting. Critically ill patients require intensive medical support in order to survive. While the majority of patients will recover within a few days, about a quarter of the patients need prolonged intensive care and are at high risk of dying from non-resolving multiple organ failure. Furthermore, the prolonged phase of critical illness is hallmarked by profound muscle weakness, and endocrine and metabolic changes, of which the pathogenesis is currently incompletely understood. The most widely used animal model in critical care research is the cecal ligation and puncture model to induce sepsis. This is a very reproducible model, with acute inflammatory and hemodynamic changes similar to human sepsis, which is designed to study the acute phase of critical illness. However, this model is hallmarked by a high lethality, which is different from the clinical human situation, and is not developed to study the prolonged phase of critical illness. Therefore, we adapted the technique by placing a central venous catheter in the jugular vein allowing us to administer clinically relevant supportive care, to better mimic the human clinical situation of critical illness. This mouse model requires an extensive surgical procedure and daily intensive care of the animals, but it results in a relevant model of the acute and prolonged phase of critical illness.

The Role of Autophagy in Critical Illness-induced Liver Damage.

Mitochondrial dysfunction and endoplasmic reticulum (ER) stress, which activates the unfolded protein response (UPR), mediate critical illness-induced organ failure, often affecting the liver. Autophagy is known to alleviate both and suppressed or insufficiently activated autophagy in prolonged illness has shown to associate with organ failure. Whether insufficient autophagy contributes to organ failure during critical illness by affecting these underlying mechanisms is incompletely understood. In this study, we investigated whether the inability to acutely activate hepatic autophagy during critical illness aggravates liver damage by increasing hepatic mitochondrial dysfunction and affecting the UPR. In a mouse model of critical illness, induced by surgery and sepsis, we investigated the impact of inactivating hepatic autophagy on markers of hepatic mitochondrial function, the UPR and liver damage in acute (1 day) and prolonged (3 days) critical illness. Hepatic autophagy inactivation during critical illness acutely worsened mitochondrial dysfunction and time-dependently modulated the hepatic UPR. Furthermore, autophagy inactivation aggravated markers of liver damage on both time points. In conclusion, the inability to acutely activate autophagy in liver during critical illness worsened hepatic mitochondrial damage and dysfunction, partially prohibited acute UPR activation and aggravated liver damage, indicating that autophagy is crucial in alleviating critical illness-induced organ failure.

Premorbid obesity, but not nutrition, prevents critical illness-induced muscle wasting and weakness.

BACKGROUND: The 'obesity paradox' of critical illness refers to better survival with a higher body mass index. We hypothesized that fat mobilized from excess adipose tissue during critical illness provides energy more efficiently than exogenous macronutrients and could prevent lean tissue wasting. METHODS: In lean and premorbidly obese mice, the effect of 5 days of sepsis-induced critical illness on body weight and composition, muscle wasting, and weakness was assessed, each with fasting and parenteral feeding. Also, in lean and overweight/obese prolonged critically ill patients, markers of muscle wasting and weakness were compared. RESULTS: In mice, sepsis reduced body weight similarly in the lean and obese, but in the obese with more fat loss and less loss of muscle mass, better preservation of myofibre size and muscle force, and less loss of ectopic lipids, irrespective of administered feeding. These differences between lean and obese septic mice coincided with signs of more effective hepatic fatty acid and glycerol metabolism, and ketogenesis in the obese. Also in humans, better preservation of myofibre size and muscle strength was observed in overweight/obese compared with lean prolonged critically ill patients. CONCLUSIONS: During critical illness premorbid obesity, but not nutrition, optimized utilization of stored lipids and attenuated muscle wasting and weakness.

Glycemic control and outcome related to cardiopulmonary bypass.

Perioperative hyperglycemia, aggravated by cardiopulmonary bypass, is associated with adverse outcome in adult and pediatric patients. Whereas hyperglycemia was originally perceived as an adaptive response to surgical stress, it is now clear that glycemic control is a strategy to reduce adverse outcomes after cardiac surgery and cardiopulmonary bypass. The optimal blood glucose target, whether or not glycemic control should be initiated already intraoperatively, and whether or not perioperative glucose administration affects the impact of glycemic control on ischemia-reperfusion damage remain open questions. Hypoglycemia, the risk of which is increased with glycemic control, is also associated with adverse outcomes. However, it remains controversial whether brief episodes of hypoglycemia, rapidly corrected during glycemic control, have adverse effects on outcome. This review gives an overview of the currently available literature on glycemic control during and after cardiac surgery and focuses on the indicated open questions about this intervention for this specific patient population.

FGF21 Response to Critical Illness: Effect of Blood Glucose Control and Relation With Cellular Stress and Survival.

CONTEXT: Critical illness is hallmarked by mitochondrial damage, which is attenuated by targeting normoglycemia. Mitochondrial dysfunction induces fibroblast growth factor-21 (FGF21) via the integrated stress response (ISR). OBJECTIVE: We evaluated whether critical illness elevates serum FGF21 concentrations and whether targeting normoglycemia (80-110 mg/dL) with insulin vs tolerating hyperglycemia may lower serum FGF21 by attenuating mitochondrial dysfunction and the ISR. SETTING/DESIGN: We quantified serum FGF21 concentrations in critically ill patients. To allow tissue analyses, including hepatic fgf21 expression in relation with mitochondrial function and ISR markers, we studied critically ill rabbits. Patients and rabbits were randomized to hyper- or normoglycemia. Patients/Other Participants: We studied 405 fed critically ill patients vs 20 matched non-critically ill control subjects as well as 26 critically ill rabbits vs 13 healthy rabbits. INTERVENTIONS: Insulin was infused to control blood glucose. MAIN OUTCOME MEASURES AND RESULTS: Serum FGF21 concentrations upon intensive care unit admission were 8-fold higher than in control subjects (P < .0001), decreased with time, but always remained higher in nonsurvivors than survivors (P ≤ .006). Maintaining normoglycemia lowered serum FGF21 (P = .01), statistically explaining at least part of its mortality benefit. In ill rabbits, hepatic fgf21 expression was substantially increased (P < .0001) and was tightly correlated with mitochondrial dysfunction (all R(2) ≥ 0.49; all P ≤ .0006 for complex I and V) and ISR markers on day 3 (R(2) ≥ 0.73; P ≤ .0001), all lowered by targeting normoglycemia. CONCLUSION: Critical illness is a potent inducer of serum FGF21 and of liver fgf21 expression, possibly driven at least in part by mitochondrial damage and the ISR, which were all attenuated by targeting normoglycemia.

The impact of resuscitated fecal peritonitis on the expression of the hepatic bile salt transporters in a porcine model.

Sepsis is often associated with cholestatic liver dysfunction caused by changes in the expression profile of hepatic bile salt transporters. However, in rodent endotoxin models, the role of ischemic hepatitis caused by liver hypoperfusion cannot be delineated. We hypothesized that hepatocytes change their expression pattern of bile salt transporters during early severe sepsis despite adequate resuscitation. Fifteen anesthetized and instrumented pigs were randomized to either fecal peritonitis (n = 8) or control (n = 7). Resuscitation was performed by hydroxyethyl starch and norepinephrine infusion. Hemodynamic parameters and markers of cholestatic and ischemic hepatic dysfunction were recorded. At baseline and after 21 h, messenger RNA (mRNA) and protein expression of bile salt transporters was determined by quantitative real-time polymerase chain reaction and immunohistochemistry, respectively, on in vivo liver biopsies. All resuscitated septic pigs developed a normotensive hyperdynamic circulation with increased portal flow. After 21 h of peritonitis, no signs of biochemical or histological cholestasis were present. Na-taurocholate cotransporting polypeptide and bile salt export pump mRNA were downregulated by 83% (P = 0.001) and 67% (P = 0.001), respectively, in comparison with controls, whereas multidrug resistance-associated protein 4 (MRP4) mRNA was upregulated by 85% (P = 0.02). Bile salt export pump and MRP2 staining were downregulated in septic pigs. During early porcine fluid-resuscitated sepsis, hepatic basolateral influx (Na-taurocholate cotransporting polypeptide) and canalicular efflux (bile salt export pump) of bile salts were downregulated without hemodynamic signs of hepatic hypoperfusion or biochemical signs of cholestasis. In parallel, the basolateral escape transport (MRP4) was markedly upregulated, possibly as an early adaptive response to counteract hepatocellular accumulation of toxic bile acids.