Sepsis and cholestasis: basic findings in the sinusoid and bile canaliculus

Systemic Disease and the Liver Part 2: Pregnancy-Related Liver Injury, Sepsis/Critical Illness, Hypoxia, Psoriasis, Scleroderma/Sjogren's Syndrome, Sarcoidosis, Common Variable Immune Deficiency, Cystic Fibrosis, Inflammatory Bowel Disease, and Hematologic Disorders

The liver is involved in many multisystem diseases and commonly may manifest with abnormal liver chemistry tests. The liver test perturbations may be multifactorial in nature, however, as patients are receiving many different medications and can also have intrinsic liver disease that may be exacerbated by the systemic disorder. Some disorders have typical histologic findings that can be diagnosed on liver biopsy, whereas others will show a more nonspecific histology. Clinicians should be aware of these conditions so as to consider the performance of a liver biopsy at the most opportune time and setting to help establish the diagnosis of acute or chronic liver disease.

Persistent Cholestatic Injury and Secondary Sclerosing Cholangitis in COVID-19 Patients

CONTEXT.–

Coronavirus disease 2019 (COVID-19) has been associated with liver injury, and a small subset of patients recovering from severe disease have shown persistent markedly elevated liver biochemistries for months after infection.

OBJECTIVE.–

To characterize persistent biliary injury after COVID-19.

DESIGN.–

A search of the pathology archives identified 7 post-COVID-19 patients with persistent biliary injury, and the clinical, radiologic, and pathologic features were assessed.

RESULTS.–

All patients in this cohort presented with respiratory symptoms and had a complicated clinical course with acute elevation of liver biochemistries. Alkaline phosphatase (ALP) was markedly and persistently elevated after discharge (median peak ALP: 1498 IU/L, at a median of 84 days from diagnosis). Magnetic resonance cholangiopancreatography (MRCP) showed 3 patients with irregularity, stricturing, and dilatation of intrahepatic ducts; no radiographic abnormalities were identified in the remaining 4 patients. Liver biopsies showed mild portal changes with features of cholestatic injury in 4 patients (bile duct injury and canalicular cholestasis) and marked biliary obstruction in 2 patients (profound cholestasis, ductular reaction, and bile infarcts), but no SARS-CoV-2 ribonucleic acid (RNA) was identified on in-situ hybridization. On follow-up, most patients had minimal intervention and showed marked improvement of liver biochemistries but with mild persistent elevation of ALP.

CONCLUSIONS.–

A subset of critically ill COVID-19 patients demonstrates marked and persistent cholestatic injury, with radiographic and histologic evidence of secondary sclerosing cholangitis, suggesting that cholestatic liver disease and secondary sclerosing cholangitis may be long-term sequelae of COVID-19 acute illness as a longstanding manifestation of critical illness.

The association between N-acetylcysteine treatment and hepatic healing in patients with non-acetaminophen-induced liver injury in pediatric intensive care: A single-center retrospective study

OBJECTIVE

The aim of this study was to determine the association between the use of intravenous N-acetylcysteine (NAC) and hepatic healing in pediatric intensive care unit (PICU) patients with non-acetaminophen-induced hepatic injury, except for acute liver failure.

METHODS

The data of patients who received intravenous NAC as adjuvant therapy for transaminase levels more than sixfold normal values during their PICU stay between 2010 and 2014 were retrospectively collected from the medical records database. The patients who did not receive NAC with elevated transaminase levels during their PICU stay between 2014 and 2018 were also collected as the standard of care (SOC) cohort.

RESULTS

More than 50% of the liver injuries were secondary to acute hypoxia, hypotension, sepsis, and inflammation. The median number of elevated transaminase period (ETP) days of the NAC and SOC groups were 5 (IQR: 4) and 4 (IQR: 4), respectively (p = 0.17). There was no significant difference between the groups in terms of minimum and maximum laboratory values during ETP. There was no significant difference in terms of ETP and maximum ALT levels between the NAC and SOC groups in the hypoxia-hypotension subgroup.

CONCLUSION

This study did not show an association between indirect measures of hepatic healing and post-insult use of NAC in pediatric liver injury in the PICU setting.

Defense mechanisms to increasing back pressure for hepatic oxygen transport and venous return in porcine fecal peritonitis

High central venous pressure (CVP) acutely decreases venous return. How this affects hepatic oxygen transport in sepsis remains unclear. The aim of this study was to evaluate the effects of repeated increases in CVP via standard nursing procedures (NPs) on hepato-splanchnic and renal oxygen transport in a prolonged porcine sepsis model. Twenty anesthetized and mechanically ventilated pigs with regional hemodynamics monitored were randomized to fecal peritonitis or controls (n = 10 pigs/group). Resuscitation was started after 8 h of observation and continued for 3 days. NPs were performed at baseline and 8 h, 32 h, 56 h, and 72 h after resuscitation started. NPs increased CVP by 4-7 mmHg in both groups. In controls, this was associated with less decrease in hepatic arterial (Q_ha; 62 ± 70 mL/min) than portal venous flow (Q_pv; 364 ± 151 mL/min). Portal venous oxygen content and hepatic O₂ delivery (Do₂) and consumption (V̇o₂) decreased by 11 ± 6 mL/dL and 0.9 ± 0.3 and 0.4 ± 0.3 mL·min^-1·kg^-1, respectively. In septic animals, hepatic Do₂ decreased more in response to increasing CVP (1.5 ± 0.9 mL·min^-1·kg^-1), which was attributable to a larger fall in both Q_ha (88 ± 66 ml/min) and portal O₂ content (14 ± 10 mL/dL, all P < 0.05). This resulted in numerically lower hepatic V̇o₂ since O₂ extraction did not increase significantly. In control conditions, a smaller decrease in Q_ha compared with Q_pv helped to limit the reduction in hepatic V̇o₂ in response to acute CVP increase. In sepsis, the contribution of Q_ha to maintain hepatic Do₂ was reduced, which jeopardized hepatic V̇o₂ further. Renal arterial flow was similarly affected by CVP increase as Q_ha.NEW & NOTEWORTHY Sepsis impairs intrinsic mechanisms to attenuate effects of increasing back pressure on hepatic oxygen transport.

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

Supplemental Digital Content is available in the text

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.

Histopathological changes of organ dysfunction in sepsis

BACKGROUND

Sepsis is a highly lethal disorder. Organ dysfunction in sepsis is not defined as a clinicopathological entity but rather by changes in clinical, physiological, or biochemical parameters. Pathogenesis and specific treatment of organ dysfunction in sepsis are unknown. The study of the histopathological correlate of organ dysfunction in sepsis will help understand its pathogenesis.

METHODS

We searched in PubMed, EMBASE, and Scielo for original articles on kidney, brain, and liver dysfunction in human sepsis. A defined search strategy was designed, and pertinent articles that addressed the histopathological changes in sepsis were retrieved for review. Only studies considered relevant in the field were discussed.

RESULTS

Studies on acute kidney injury (AKI) in sepsis reveal that acute tubular necrosis is less prevalent than other changes, indicating that kidney hypoperfusion is not the predominant pathogenetic mechanism of sepsis-induced AKI. Other more predominant histopathological changes are apoptosis, interstitial inflammation, and, to a lesser extent, thrombosis. Brain pathological findings include white matter hemorrhage and hypercoagulability, microabscess formation, central pontine myelinolysis, multifocal necrotizing leukoencephalopathy, metabolic changes, ischemic changes, and apoptosis. Liver pathology in sepsis includes steatosis, cholangiolitis and intrahepatic cholestasis, periportal inflammation, and apoptosis. There is no information on physiological or biochemical biomarkers of the histopathological findings.

CONCLUSIONS

Histopathological studies may provide important information for a better understanding of the pathogenesis of organ dysfunction in sepsis and for the design of potentially effective therapies. There is a lack of clinically available biomarkers for the identification of organ dysfunction as defined by the histological analysis.

Hepatobiliary Complications in Critically Ill Patients

Critically ill patients frequently present with the systemic inflammatory response syndrome, which is largely a reflection of the liver's response to injury. Underlying hepatic congestion is a major risk factor for hypoxic liver injury, the most common cause for hepatocellular injury. Cholestatic liver injury often occurs in critically ill patients due to inhibition of farnesoid X receptor (FXR), the main regulator of bile acid handling, particularly in the liver and intestines. Additional injury to the liver occurs due to alterations in the bile acid pool with increased cytotoxic forms and disturbance in the typical processing of xenobiotics in the liver.

Hepatic changes in systemic infection

Liver is an integral part of the host-defense mechanism and facilitates clearance of pathogenic organisms in systemic infection by modulating the immunological response. It undergoes several cellular and molecular changes resulting in the release of pro-inflammatory cytokines, which regulate various metabolic and immunological signalling pathways. Some of these changes are pathogen-specific and essential in determining the host response to systemic infection. However, alterations in the immunological homeostasis can adversely affect the liver and lead to hepatic dysfunction. This article focuses on these molecular and immunological changes that occur within the liver in response to extra-hepatic systemic infection and its consequences.

[Sepsis as a cause of intrahepatic cholestasis]

INTRODUCTION

The causes of intrahepatic cholestasis include cholestatic viral hepatitis, primary biliary cirrhosis, benign recurrent cholestasis, primary sclerosing cholangitis and sepsis. During sepsis, proinflammatory cytokines and nitric oxide cause cholestasis by impairing hepatocellular and ductal bile formation.

CASE OUTLINE

We report a 48-year-old woman who was admitted to hospital due to malaise, jaundice, fever and pain in the neck. Physical examination revealed jaundice, tachycardia (pulse rate was 120/min), hypotension 90/60 mm Hg. Laboratory findings showed normocytic normochromic anaemia, inflammatory syndrome and abnormal liver function tests indicating cholestasis and hepatocellular necrosis. Abdominal ultrasonography detected hepatosplenomegaly. Chest computed tomography showed bronchopneumonic infiltrates. Percutaneous liver biopsy was performed using a Menghini needle of 1.4 mm. Pathohystological analysis of the liver tissue confirmed reactive, intrahepatic cholestasis. Blood cultures isolated Staphylococcus aureus. After the diagnosis was established the treatment with broad-spectrum antibiotics was carried out, resulting in the improvement of general condition of the patient, regression of inflammatory syndrome, disappearance of cholestasis and regression of pulmonary infiltrates. Abdominal ultrasonography after antibiotic treatment did not show hepatosplenomegaly.

CONCLUSION

Concerning patients with cholestasis of uncertain origin, we should always think of sepsis as a possible cause in order to start antibiotic treatment in time.

Liver histology in ICU patients dying from sepsis: a clinico-pathological study

AIM

To determine end-stage pathologic changes in the liver of septic patients dying in the intensive care unit.

METHODS

Needle liver biopsies obtained immediately after death from 15 consecutive patients with sepsis and no underlying liver disease were subjected to routine histological examination. Liver function tests and clinical monitoring measurements were also recorded.

RESULTS

Liver biochemistries were increased in the majority of patients before death. Histology of liver biopsy specimens showed portal inflammation in 73.3%, centrilobular necrosis in 80%, lobular inflammation in 66.7%, hepatocellular apoptosis in 66.6% and cholangitis/cholangiolitis in 20% of patients. Mixed hepatitic/cholestatic type of liver injury was observed in 6/15 (40%) patients and hepatitc in 9/15 (60%). Steatosis was observed in 11/15 (73.3%) patients affecting 5%-80% of liver parenchyma. Among the histological features, the presence of portal inflammation in liver biopsy was associated with increased hospitalization in the ICU prior death (P=0.026).

CONCLUSION

Features of hepatitis and steatosis are the main histological findings in the liver in the majority of patients dying from sepsis.

Sepsis and cholestasis

Cholestasis is a common complication of bacterial infections and sepsis. This article gives a comprehensive overview of the underlying molecular mechanisms of sepsis-associated cholestasis and jaundice, their clinical presentation, and diagnostic and therapeutic management.

Role of retinoid-X receptor-alpha in the suppression of rat bile acid coenzyme A-amino acid N-acyltransferase in liver during sepsis

Sepsis causes intrahepatic cholestasis and leads to hepatic failure. However, the pathophysiology of hepatic events is unclear. Expression of rat hepatic bile acid coenzyme A-amino acid N-acyltransferase (rBAT), a major enzyme for the conjugation of bile acids, is significantly decreased during sepsis. rBAT transcriptional regulation is mainly by a heterodimer of farnesoid-X receptor (FXR) and retinoid-X receptor-alpha (RXR-alpha) via the inverted repeat 1 sequence. During sepsis, nuclear receptors and translocation of RXR-alpha from cytosol to nucleus decrease. The purpose of this study was to further clarify the mechanisms of RXR-alpha-mediated rBAT regulation during polymicrobial sepsis and with dexamethasone treatment. Polymicrobial sepsis was induced in rats by cecal ligation and puncture (CLP). Liver tissues obtained 3, 6, 9, and 18 h after CLP were studied, and hepatocytes were isolated from rats with sepsis. Post-CLP decreases were observed in mRNA levels of rBAT (6 h), protein levels of rBAT (6 h), RXR-alpha (6 h), and FXR (9 h). DNA binding activity of FXR/RXR significantly decreased at 6 h after CLP. Dexamethasone reversed sepsis-inhibited RXR-alpha expression and the binding activity of FXR/RXR to rBAT DNA as well as rBAT protein expression. The results suggest that suppression of rBAT occurs at the transcriptional level, and the decrease in RXR-alpha by septic insult may play a critical role in rBAT suppression at the early stage of polymicrobial sepsis.

Liver dysfunction associated with artificial nutrition in critically ill patients

INTRODUCTION

Liver dysfunction associated with artificial nutrition in critically ill patients is a complication that seems to be frequent, but it has not been assessed previously in a large cohort of critically ill patients.

METHODS

We conducted a prospective cohort study of incidence in 40 intensive care units. Different liver dysfunction patterns were defined: (a) cholestasis: alkaline phosphatase of more than 280 IU/l, gamma-glutamyl-transferase of more than 50 IU/l, or bilirubin of more than 1.2 mg/dl; (b) liver necrosis: aspartate aminotransferase of more than 40 IU/l or alanine aminotransferase of more than 42 IU/l, plus bilirubin of more than 1.2 mg/dl or international normalized ratio of more than 1.4; and (c) mixed pattern: alkaline phosphatase of more than 280 IU/l or gamma-glutamyl-transferase of more than 50 IU/l, plus aspartate aminotransferase of more than 40 IU/l or alanine aminotransferase of more than 42 IU/l.

RESULTS

Seven hundred and twenty-five of 3,409 patients received artificial nutrition: 303 received total parenteral nutrition (TPN) and 422 received enteral nutrition (EN). Twenty-three percent of patients developed liver dysfunction: 30% in the TPN group and 18% in the EN group. The univariate analysis showed an association between liver dysfunction and TPN (p < 0.001), Multiple Organ Dysfunction Score on admission (p < 0.001), sepsis (p < 0.001), early use of artificial nutrition (p < 0.03), and malnutrition (p < 0.01). In the multivariate analysis, liver dysfunction was associated with TPN (p < 0.001), sepsis (p < 0.02), early use of artificial nutrition (p < 0.03), and calculated energy requirements of more than 25 kcal/kg per day (p < 0.05).

CONCLUSION

TPN, sepsis, and excessive calculated energy requirements appear as risk factors for developing liver dysfunction. Septic critically ill patients should not be fed with excessive caloric amounts, particularly when TPN is employed. Administering artificial nutrition in the first 24 hours after admission seems to have a protective effect.

Mechanisms of Disease: mechanisms and clinical implications of cholestasis in sepsis

Cholestasis is a common complication in patients with extrahepatic bacterial infection and sepsis. This article gives a comprehensive overview of the molecular and cellular mechanisms of sepsis-associated cholestasis. Recent advances in the understanding of intrahepatic cholestasis have allowed us to delineate the molecular mechanisms that underlie sepsis-associated cholestasis and to describe their potential clinical and therapeutic applications. The mechanisms and clinical presentation of sepsis-associated liver injury vary according to the severity of the bacterial infection. Proinflammatory cytokines and nitric oxide cause cholestasis by impairing hepatocellular and ductal bile formation. Ischemic liver injury and, rarely, progressive sclerosing cholangitis can also be found in patients with septic shock, or major trauma with systemic inflammatory response syndrome. Treatment is mainly focused on eradication of the underlying infection and managing the sepsis. The use of ursodeoxycholic acid or extracorporeal liver support as treatments for sepsis-associated cholestasis is under investigation, but neither can be recommended in routine clinical practice at present. Patients with progressive sclerosing cholangitis should be considered for orthotopic liver transplantation.

Hyperbaric oxygen stimulates cell proliferation and normalizes multidrug resistance protein-2 protein localization in primary rat hepatocytes

Hyperbaric oxygen therapy (HBO) has been used for many clinical treatments, including primary liver non-function. However, the cellular mechanism by which HBO treatment ameliorates liver function is not understood. Therefore, the purpose of this study was to elucidate this cellular mechanism using primary cultured rat hepatocytes in in vitro studies. Hepatocytes were treated with HBO at 1 day after plating, and the morphological and functional characteristics of bile canaliculi formed in cultured hepatocytes were observed by time-lapse microscopy. Multidrug resistance protein-2 localization was observed by confocal laser microscopy. In cultured hepatocytes, the labeling index in the HBO group at 2 days after treatment was significantly higher than that in the control group. In addition, the proliferating cellular nuclear antigen level in the HBO group was significantly higher than that in the control group. The contraction of the bile canaliculi in the HBO group was slower than in the control group and the dilatation of bile canaliculi in the HBO group was much larger than in the control group. Multidrug resistance protein-2 in the HBO group was localized at the apical membrane. These results show that HBO stimulates hepatocytes to proliferate and HBO normalizes multidrug resistance protein-2 localization to the apical membrane, which could dilate bile canaliculi.

[Relation of pathoanatomic substrate and incidence of bacterial infection in the acute biliary tract disease]

Acute biliary diseases have become the most common indication for major abdominal surgery. We investigated 60 patients who underwent surgery for the acute biliary diseases, within 48 hours from the onset of the illness (group I), and over longer preoperative interval (48 h up to 5 days) (group II). Surgical specimen (gallbladder) was histologically examined. Samples for microbiological exams were obtained from gallbladder, common bile duct, Lund's node, gallbladder bed and peritoneal cavity. Positive bile cultures were found in 43% of group I, and in 70% of group II (p<0.05). Microbiological analysis revealed 13 different species, mostly Gram negative aerobic rods (69%). The incidence of bacteriobilia was in correlation with HP of lesions (79% in the acute and 18% in chronic lesions; p<0.01), what testified the importance of time interval and role of bacterial factor in the acute biliary pathology. Septic complications strictly occurred in patients with positive biliary findings. Early surgical treatment eliminates focus, and stops further development of intraabdominal and systemic septic complications. Correlation between bacteriobilia and septic sequelae calls for prophylactic use of antibiotics.

The beneficial effect of trolox on sepsis-induced hepatic drug metabolizing dysfunction

Trolox is a hydrophilic analogue of vitamin E. The aim of this study was to investigate its effects on hepatic injury, especially alteration in cytochrome P450 (CYP)-dependent drug metabolism during polymicrobial sepsis. Rats were subjected to polymicrobial sepsis by cecal ligation and puncture (CLP). The rats were treated intravenously with Trolox (2.5 mg/kg) or vehicle, immediately after CLP. Serum aminotransferases and lipid peroxidation levels were markedly increased 24 h after CLP. This increase was attenuated by Trolox. Total CYP content and NADPH-P450 reductase activity decreased significantly 24 h after CLP. This decrease in CYP content was attenuated by Trolox. At 24 h after CLP, there was a significant decrease in the activity of these CYP isozymes: CYP1A1, 1A2, 2B1, and 2E1. However, Trolox differentially inhibited the decrease in CYP isozyme activity. Trolox had little effect on the decrease in CYP1A1 activity but Trolox significantly attenuated decreases in CYP1A2 and 2E1 activities. In fact, Trolox restored CYP2B1 activity to the level of activity found in control rats. Our findings suggest that Trolox reduces hepatocellular damage as indicated by abnormalities in hepatic drug-metabolizing function during sepsis. Our data also indicates that this protection is, in part, caused by decreased lipid peroxidation.

Surgical sepsis: dysregulation of immune function and therapeutic implications

Sepsis is defined clinically as the systemic inflammatory response of the host to the documented systemic infection. The pathophysiological disturbance involves both the innate and adaptive immune systems encompassing cellular immunity, humoral components and the complement system. Dendritic cells (antigen-presenting cells) are key cells involved in the regulation of the immune response in sepsis, in particular in activating T cells and especially inducing the production and secretion of specific cytokines. These are the main mediators in establishing prominent disturbances of inflammation in patients with sepsis. The clinical features of the sepsis syndrome may vary from minor clinical disturbances to severe multiple organ failure and death of the host. Appropriate therapeutic strategies for patients with sepsis utilise conventional therapy and new novel forms of treatment, which are showing promise for the future.