Expert Statements on the Standard of Care in Critically Ill Adult Patients With Atypical Hemolytic Uremic Syndrome.

A typical hemolytic uremic syndrome (aHUS) presents similarly to thrombotic thrombocytopenic purpura (TTP) and other causes or conditions with thrombotic microangiopathy (TMA), such as disseminated intravascular coagulation or sepsis. Similarity in clinical presentation may hinder diagnosis and optimal treatment selection in the urgent setting in the ICU. However, there is currently no consensus on the diagnosis or treatment of aHUS for ICU specialists. This review aims to summarize available data on the diagnosis and treatment strategies of aHUS in the ICU to enhance the understanding of aHUS diagnosis and outcomes in patients managed in the ICU. To this end, a review of the recent literature (January 2009-March 2016) was performed to select the most relevant articles for ICU physicians. Based on the paucity of adult aHUS cases overall and within the ICU, no specific recommendations could be formally graded for the critical care setting. However, we recognize a core set of skills required by intensivists for diagnosing and managing patients with aHUS: recognizing thrombotic microangiopathies, differentiating aHUS from related conditions, recognizing involvement of other organ systems, understanding the pathophysiology of aHUS, knowing the diagnostic workup and relevant outcomes in critically ill patients with aHUS, and knowing the standard of care for patients with aHUS based on available data and guidelines. In conclusion, managing critically ill patients with aHUS requires basic skills that, in the absence of sufficient data from patients treated within the ICU, can be gleaned from an increasingly relevant literature outside the ICU. More data on critically ill patients with aHUS are needed to validate these conclusions within the ICU setting

Nomenclature for renal replacement therapy and blood purification techniques in critically ill patients: practical applications

This article reports the conclusions of the second part of a consensus expert conference on the nomenclature of renal replacement therapy (RRT) techniques currently utilized to manage acute kidney injury and other organ dysfunction syndromes in critically ill patients. A multidisciplinary approach was taken to achieve harmonization of definitions, components, techniques, and operations of the extracorporeal therapies. The article describes the RRT techniques in detail with the relevant technology, procedures, and phases of treatment and key aspects of volume management/fluid balance in critically ill patients. In addition, the article describes recent developments in other extracorporeal therapies, including therapeutic plasma exchange, multiple organ support therapy, liver support, lung support, and blood purification in sepsis. This is a consensus report on nomenclature harmonization in extracorporeal blood purification therapies, such as hemofiltration, plasma exchange, multiple organ support therapies, and blood purification in sepsis

Expression of AXL receptor tyrosine kinase relates to monocyte dysfunction and severity of cirrhosis

Infectious complications in patients with cirrhosis frequently initiate episodes of decompensation and substantially contribute to the high mortality. Mechanisms of the underlying immuneparesis remain underexplored. TAM receptors (TYRO3/AXL/MERTK) are important inhibitors of innate immune responses. To understand the pathophysiology of immuneparesis in cirrhosis, we detailed TAM receptor expression in relation to monocyte function and disease severity prior to the onset of acute decompensation. TNF-α/IL-6 responses to lipopolysaccharide were attenuated in monocytes from patients with cirrhosis (n = 96) compared with controls (n = 27) and decreased in parallel with disease severity. Concurrently, an AXL-expressing (AXL+) monocyte population expanded. AXL+ cells (CD14+CD16highHLA-DRhigh) were characterised by attenuated TNF-α/IL-6 responses and T cell activation but enhanced efferocytosis and preserved phagocytosis of Escherichia coli. Their expansion correlated with disease severity, complications, infection, and 1-yr mortality. AXL+ monocytes were generated in response to microbial products and efferocytosis in vitro. AXL kinase inhibition and down-regulation reversed attenuated monocyte inflammatory responses in cirrhosis ex vivo. AXL may thus serve as prognostic marker and deserves evaluation as immunotherapeutic target in cirrhosis

Mucosa-associated invariant T cells link intestinal immunity with antibacterial immune defects in alcoholic liver disease

Background/aims: Intestinal permeability with systemic distribution of bacterial products are central in the immunopathogenesis of alcoholic liver disease (ALD), yet links with intestinal immunity remain elusive. Mucosa-associated invariant T cells (MAIT) are found in liver, blood and intestinal mucosa and are a key component of antibacterial host defences. Their role in ALD is unknown. Methods/design: We analysed frequency, phenotype, transcriptional regulation and function of blood MAIT cells in severe alcoholic hepatitis (SAH), alcohol-related cirrhosis (ARC) and healthy controls (HC). We also examined direct impact of ethanol, bacterial products from faecal extracts and antigenic hyperstimulation on MAIT cell functionality. Presence of MAIT cells in colon and liver was assessed by quantitative PCR and immunohistochemistry/gene expression respectively. Results: In ARC and SAH, blood MAIT cells were dramatically depleted, hyperactivated and displayed defective antibacterial cytokine/cytotoxic responses. These correlated with suppression of lineage-specific transcription factors and hyperexpression of homing receptors in the liver with intrahepatic preservation of MAIT cells in ALD. These alterations were stronger in SAH, where surrogate markers of bacterial infection and microbial translocation were higher than ARC. Ethanol exposure in vitro, in vivo alcohol withdrawal and treatment with Escherichia coli had no effect on MAIT cell frequencies, whereas exposure to faecal bacteria/antigens induced functional impairments comparable with blood MAIT cells from ALD and significant MAIT cell depletion, which was not observed in other T cell compartments. Conclusions: In ALD, the antibacterial potency of MAIT cells is compromised as a consequence of contact with microbial products and microbiota, suggesting that the ‘leaky’ gut observed in ALD drives MAIT cell dysfunction and susceptibility to infection in these patients

Lysophosphatidylcholines modulate immunoregulatory checkpoints in peripheral monocytes and are associated with mortality in people with acute liver failure.

BACKGROUND AND AIMS: Acute liver failure (ALF) is a life-threatening disease characterised by high-grade inflammation and immunoparesis with a high incidence of death from sepsis. Here, we aimed to describe the metabolic dysregulation in ALF and determine whether systemic immune responses are modulated via the lysophosphatidylcholine(LPC)-autotaxin(ATX)-lysophosphatidylcholinic acid (LPA) pathway. METHODS: 96 ALF patients, 71 healthy controls (HC), 104 patients with cirrhosis and 31 septic patients were recruited. The pathways of interest were identified based on multivariate statistical analysis of proton nuclear magnetic resonance (1HNMR) spectroscopy, untargeted ultraperformance liquid chromatography-mass spectrometry (UPLC-MS)-based lipidomics and validated with a targeted metabolomics panel. Peripheral blood mononuclear cells were cultured with LPA 16:0, 18:0, 18:1, and their immune checkpoint surface expression was assessed by flow cytometry. LPA receptor (LPAR) transcript-level expression of monocytes was investigated and the effect of LPAR antagonism was also examined in vitro. RESULTS: LPC 16:0 was found highly discriminant between ALF and HC. There was an increase in ATX and LPA in ALF compared to HC and sepsis. LPCs 16:0, 18:0 and 18:1 were reduced in ALF patients with poor prognosis. Treatment of monocytes with LPA 16:0 increased their PD-L1 expression and reduced CD155, CD163, MerTK levels, without effect on T and NK/CD56+T cells immune checkpoints. LPAR1 and 3 antagonism in culture reversed the LPA effect on monocyte expression of MerTK and CD163. MerTK and CD163, but not LPARs genes, were differently expressed and upregulated in monocytes from ALF patients compared to controls. CONCLUSION: Reduced amounts of LPCs are biomarkers of poor prognosis in patients with ALF. The LPC-ATX-LPA axis appears to modulate innate immune response in ALF via LPAR1 and LPAR3. Further investigations are required to identify novel therapeutic agents targeting these receptors. IMPACT AND IMPLICATIONS: Liver disease is the 5th leading cause of death in the UK and rising in incidence. Acute liver failure occurs on the background of normal liver function and mostly in young adults. Acute admissions to hospital and intensive care units are rising in the UK and worldwide. We identified a metabolic signature of acute liver failure and investigated the immunometabolic role of the Lysophosphatdylcholine(LPC)-Autotaxin (ATX)-Lysophosphatidylcholinic acid (LPA) pathway in order to find a mechanistic explanation for monocyte behaviour and find possible therapeutic target(s) to modulate the systemic immune response in ALF. At present, no selective immune based therapies exist. We were able to modulate monocyte phenotype and function in vitro and aim to extend findings to murine models of ALF before could apply this treatment to patients. Future therapies may be based on the enhancement of resolution through metabolic modulation and therefore the role of specific lipids in this pathway require elucidation and the relative merits of ATX inhibition, LPAR blockade or lipid-based therapies answered. This application aims to make a step change in meeting this knowledge gap and definitively elucidate these immune-metabolic pathways using an experimental medicine approach, thus finding the most effective therapeutic targets

The CLIF Consortium Acute Decompensation score (CLIF-C ADs) for prognosis of hospitalised cirrhotic patients without acute-on-chronic liver failure

BACKGROUND & AIMS: Cirrhotic patients with acute decompensation frequently develop acute-on-chronic liver failure (ACLF), which is associated with high mortality rates. Recently, a specific score for these patients has been developed using the CANONIC study database. The aims of this study were to develop and validate the CLIF-C AD score, a specific prognostic score for hospitalised cirrhotic patients with acute decompensation (AD), but without ACLF, and to compare this with the Child-Pugh, MELD, and MELD-Na scores. METHODS: The derivation set included 1016 CANONIC study patients without ACLF. Proportional hazards models considering liver transplantation as a competing risk were used to identify score parameters. Estimated coefficients were used as relative weights to compute the CLIF-C ADs. External validation was performed in 225 cirrhotic AD patients. CLIF-C ADs was also tested for sequential use. RESULTS: Age, serum sodium, white-cell count, creatinine and INR were selected as the best predictors of mortality. The C-index for prediction of mortality was better for CLIF-C ADs compared with Child-Pugh, MELD, and MELD-Nas at predicting 3- and 12-month mortality in the derivation, internal validation and the external dataset. CLIF-C ADs improved in its ability to predict 3-month mortality using data from days 2, 3-7, and 8-15 (C-index: 0.72, 0.75, and 0.77 respectively). CONCLUSIONS: The new CLIF-C ADs is more accurate than other liver scores in predicting prognosis in hospitalised cirrhotic patients without ACLF. CLIF-C ADs therefore may be used to identify a high-risk cohort for intensive management and a low-risk group that may be discharged early

MerTK expressing hepatic macrophages promote the resolution of inflammation in acute liver failure.

OBJECTIVE: Acute liver failure (ALF) is characterised by overwhelming hepatocyte death and liver inflammation with massive infiltration of myeloid cells in necrotic areas. The mechanisms underlying resolution of acute hepatic inflammation are largely unknown. Here, we aimed to investigate the impact of Mer tyrosine kinase (MerTK) during ALF and also examine how the microenvironmental mediator, secretory leucocyte protease inhibitor (SLPI), governs this response. DESIGN: Flow cytometry, immunohistochemistry, confocal imaging and gene expression analyses determined the phenotype, functional/transcriptomic profile and tissue topography of MerTK+ monocytes/macrophages in ALF, healthy and disease controls. The temporal evolution of macrophage MerTK expression and its impact on resolution was examined in APAP-induced acute liver injury using wild-type (WT) and Mer-deficient (Mer-/-) mice. SLPI effects on hepatic myeloid cells were determined in vitro and in vivo using APAP-treated WT mice. RESULTS: We demonstrate a significant expansion of resolution-like MerTK+HLA-DRhigh cells in circulatory and tissue compartments of patients with ALF. Compared with WT mice which show an increase of MerTK+MHCIIhigh macrophages during the resolution phase in ALF, APAP-treated Mer-/- mice exhibit persistent liver injury and inflammation, characterised by a decreased proportion of resident Kupffer cells and increased number of neutrophils. Both in vitro and in APAP-treated mice, SLPI reprogrammes myeloid cells towards resolution responses through induction of a MerTK+HLA-DRhigh phenotype which promotes neutrophil apoptosis and their subsequent clearance. CONCLUSIONS: We identify a hepatoprotective, MerTK+, macrophage phenotype that evolves during the resolution phase following ALF and represents a novel immunotherapeutic target to promote resolution responses following acute liver injury

Early enteral nutrition in critically ill patients: ESICM clinical practice guidelines.

To provide evidence-based guidelines for early enteral nutrition (EEN) during critical illness. We aimed to compare EEN vs. early parenteral nutrition (PN) and vs. delayed EN. We defined "early" EN as EN started within 48 h independent of type or amount. We listed, a priori, conditions in which EN is often delayed, and performed systematic reviews in 24 such subtopics. If sufficient evidence was available, we performed meta-analyses; if not, we qualitatively summarized the evidence and based our recommendations on expert opinion. We used the GRADE approach for guideline development. The final recommendations were compiled via Delphi rounds. We formulated 17 recommendations favouring initiation of EEN and seven recommendations favouring delaying EN. We performed five meta-analyses: in unselected critically ill patients, and specifically in traumatic brain injury, severe acute pancreatitis, gastrointestinal (GI) surgery and abdominal trauma. EEN reduced infectious complications in unselected critically ill patients, in patients with severe acute pancreatitis, and after GI surgery. We did not detect any evidence of superiority for early PN or delayed EN over EEN. All recommendations are weak because of the low quality of evidence, with several based only on expert opinion. We suggest using EEN in the majority of critically ill under certain precautions. In the absence of evidence, we suggest delaying EN in critically ill patients with uncontrolled shock, uncontrolled hypoxaemia and acidosis, uncontrolled upper GI bleeding, gastric aspirate >500 ml/6 h, bowel ischaemia, bowel obstruction, abdominal compartment syndrome, and high-output fistula without distal feeding access