The Hypothalamus-pituitary-adrenocortical Response to Critical Illness: A Concept in Need of Revision

Altered muscle transcriptome as molecular basis of long-term muscle weakness in survivors from critical illness

PURPOSE

Critically ill patients requiring intensive care unit (ICU) admission suffer from muscle weakness that persists for years, compromising quality-of-life. The pathophysiology of this long-term weakness remains unclear. We hypothesized that former ICU-patients show a long-term abnormal RNA-expression profile, which may contribute to lower long-term strength and for which modifiable risk factors can be identified.

METHODS

This pre-planned secondary analysis of the EPaNIC-trial compared muscle transcriptomes of 115 former ICU-patients 5 years after critical illness and 30 matched controls with RNA-sequencing, followed by pathway over-representation and differential co-expression analyses of the differentially expressed RNAs. We used multivariable linear regression analyses to identify which of the abnormal RNA-expressions associated with the long-term muscle strength of the patients and to identify potential risk factors for the abnormal RNA-expressions.

RESULTS

In former patients, 234 down-regulated and 116 up-regulated RNAs were identified after adjustment for age, sex, and BMI. Pathway over-representation and further molecular and histological analyses indicated impaired mitochondrial energy metabolism, disturbed lipid metabolism, and increased collagen formation/fibrosis in former patients. Abnormal muscle RNA-expression in former patients correlated with lower long-term muscle strength. Several treatments given in-ICU and at 5-year follow-up associated with abnormal RNA-expression, most notably in-ICU early parenteral nutrition (early PN) and glucocorticoid use.

CONCLUSION

Abnormal RNA-expression profiles 5 years after critical illness suggest disrupted mitochondrial function, disturbed lipid metabolism, and fibrosis, associated with lower long-term muscle strength and partly attributable to possibly avoidable risk factors. These findings open perspectives for prevention and possibly treatment of long-term muscle weakness after critical illness.

TRIAL REGISTRATION NUMBER AND DATE

ClinicalTrials.gov-NCT00512122, July 31, 2007.

Critical illness-based chronic disease: a new framework for intensive metabolic support

PURPOSE OF REVIEW

This review addresses the novel concept of critical illness as a potential chronic disease. The high clinical and economic burdens of chronic critical illness and post-ICU syndromes are mainly due to refractoriness to therapy and consequently lead to significant complications. Interventions need to be preventive in nature and therefore a robust disease model is warranted.

RECENT FINDINGS

There are three paradigms that are leveraged to create a new critical illness-based chronic disease (CIBCD) model: metabolic model of critical illness, intensive metabolic support (IMS; insulinization and nutrition support), and driver-based chronic disease modeling. The CIBCD model consists of four stages: risk, predisease, (chronic) disease, and complications. The principal goal of the CIBCD model is to expose early opportunities to prevent disease progression, particularly further morbidity, complications, and mortality. IMS is used to target seminal pathophysiological events such as immune-neuroendocrine axis (INA) activation and failure to downregulate INA activation because of preexisting chronic diseases and recurrent pathological insults.

SUMMARY

The CIBCD model complements our understanding of critical illness and provides needed structure to preventive actions that can improve clinical outcomes. Many research, knowledge, and practice gaps exist, which will need to be addressed to optimize and validate this model.

Effect of methylprednisolone vs hydrocortisone on 30-day mortality in critically ill adults with septic shock: an analysis of the MIMIC-IV database

BACKGROUND

Methylprednisolone is still used to treat adults with septic shock in real-world clinical settings, despite current international guidelines recommending hydrocortisone. The aim of this study was to assess the effect of methylprednisolone vs hydrocortisone on 30-day mortality among critically ill patients with septic shock.

METHODS

We conducted a retrospective cohort study on adults with septic shock using the MIMIC-IV v3.0 database. Patients who received methylprednisolone after diagnosis were matched using propensity score matching (PSM) with those received hydrocortisone, to balance confounding factors between groups. The primary outcome was the 30-day mortality rate. Subgroup and sensitivity analyses were performed to assess the robustness of the conclusions.

RESULTS

A total of 1,607 septic shock patents were enrolled in this study, with an overall 30-day mortality rate of 42.1%. After 1:1 PSM, 376 pairs were successfully matched. The primary outcome occurred in 141 patients (37.5%) and in 131 patients (34.8%) in the methylprednisolone and hydrocortisone groups, respectively (HR = 1.105, 95% CI: 0.871-1.402, P = 0.410). In subgroup analyses based on age, sex, blood culture positivity, pneumonia, and invasive mechanical ventilation (IMV), along with sensitivity analyses for deletion of missing values, findings remained consistent. However, the methylprednisolone group exhibited a longer ICU stay, elevated blood glucose levels, and a shorter maintenance duration for vasopressin compared to the hydrocortisone group.

CONCLUSIONS

Among adults with septic shock, there was no significant difference in 30-day mortality between those administered methylprednisolone and hydrocortisone. It needs to be further verified in prospective, randomized controlled trials.

Unraveling the immunological landscape and gut microbiome in sepsis: a comprehensive approach to diagnosis and prognosis

BACKGROUND

Comprehensive and in-depth research on the immunophenotype of septic patients remains limited, and effective biomarkers for the diagnosis and treatment of sepsis are urgently needed in clinical practice.

METHODS

Blood samples from 31 septic patients in the Intensive Care Unit (ICU), 25 non-septic ICU patients, and 18 healthy controls were analyzed using flow cytometry for deep immunophenotyping. Metagenomic sequencing was performed in 41 fecal samples, including 13 septic patients, 10 non-septic ICU patients, and 18 healthy controls. Immunophenotype shifts were evaluated using differential expression sliding window analysis, and random forest models were developed for sepsis diagnosis or prognosis prediction.

FINDINGS

Septic patients exhibited decreased proportions of natural killer (NK) cells and plasmacytoid dendritic cells (pDCs) in CD45+ leukocytes compared with non-septic ICU patients and healthy controls. These changes statistically mediated the association of Bacteroides salyersiae with sepsis, suggesting a potential underlying mechanism. A combined diagnostic model incorporating B.salyersia, NK cells in CD45+ leukocytes, and C-reactive protein (CRP) demonstrated high accuracy in distinguishing sepsis from non-sepsis (area under the receiver operating characteristic curve, AUC = 0.950, 95% CI: 0.811-1.000). Immunophenotyping and disease severity analysis identified an Acute Physiology and Chronic Health Evaluation (APACHE) II score threshold of 21, effectively distinguishing mild (n = 19) from severe (n = 12) sepsis. A prognostic model based on the proportion of total lymphocytes, Helper T (Th) 17 cells, CD4+ effector memory T (TEM) cells, and Th1 cells in CD45+ leukocytes achieved robust outcome prediction (AUC = 0.906, 95% CI: 0.732-1.000), with further accuracy improvement when combined with clinical scores (AUC = 0.938, 95% CI: 0.796-1.000).

INTERPRETATION

NK cell subsets within innate immunity exhibit significant diagnostic value for sepsis, particularly when combined with B. salyersiae and CRP. In addition, T cell phenotypes within adaptive immunity are correlated with sepsis severity and may serve as reliable prognostic markers.

FUNDING

This project was supported by the National Key R&D Program of China (2023YFC2307600, 2021YFA1301000), Shanghai Municipal Science and Technology Major Project (2023SHZDZX02, 2017SHZDZX01), Shanghai Municipal Technology Standards Project (23DZ2202600).

Association of childhood maltreatment and adverse lifetime experiences with post-injury psychopathology: evidence from the China Severe Trauma Cohort

BACKGROUND

Adverse life experiences have been associated with increased susceptibilities to psychopathology in later life. However, their impact on psychological responses following physical trauma remains largely unexplored.

METHODS

Based on the China Severe Trauma Cohort, we conducted a cohort study of 2937 patients who were admitted to the Trauma Medical Center of West China Hospital between June 2020 and August 2023. Adverse life experiences, including childhood maltreatment (5 subtypes, measured by Childhood Trauma Questionnaire-Short Form) and adverse lifetime experiences (17 subtypes, by Life Events Checklist) were assessed. Generalized linear mixed models were used to examine the associations of childhood maltreatment and adverse lifetime experiences with symptoms of psychopathology measured at multiple time-points after the index injury (i.e., at recruitment, 1-, 3-, 6-, and 12-month follow-ups), adjusted for important confounders. We further stratified the analyses by level of genetic predisposition to a given psychological symptom quantified by polygenic risk score (PRS) based on publicly available GWAS summary statistics. Mediation analyses were performed to assess the role of adverse lifetime experiences in connecting childhood maltreatment and post-injury psychopathology.

RESULTS

The mean age of participants was 47.95 years with a predominance of males (61.39%). During the whole follow-up period, the incidence of symptoms of stress-related disorders, anxiety, and depression was 13.86%, 29.89%, and 36.57%, respectively. We observed associations between the cumulative number of those studied adversities and increased risk of post-injury psychopathology, particularly stress-related disorder (odds ratio [OR] = 2.78, 95% confidence interval [CI] 1.87-4.12 for ≥ 2 vs no childhood maltreatment; 2.65 [1.67-4.20] for ≥ 4 vs 0-1 adverse lifetime experiences). By subtype, positive associations were observed for most studied life adversities, with the most pronounced estimates for childhood emotional abuse (ORs = 1.71-2.52) and lifetime life-threatening illness/injury (ORs = 1.87-2.89). We found basically comparable estimates among traumatized individuals with different PRSs for studied psychopathology. Moreover, adverse lifetime experiences may partially (mediation proportion: 22.52-27.48%) explain the associations between various childhood maltreatment and post-injury psychopathology.

CONCLUSIONS

Both childhood maltreatment and adverse lifetime experiences were associated with post-injury psychopathology, irrespective of genetic susceptibility. Such findings highlight the importance of close surveillance and timely psychological interventions for injury patients with adverse life experiences.

A murine model of acute and prolonged abdominal sepsis, supported by intensive care, reveals time-dependent metabolic alterations in the heart

BACKGROUND

Sepsis-induced cardiomyopathy (SICM) often occurs in the acute phase of sepsis and is associated with increased mortality due to cardiac dysfunction. The pathogenesis remains poorly understood, and no specific treatments are available. Although SICM is considered reversible, emerging evidence suggests potential long-term sequelae. We hypothesized that metabolic and inflammatory cardiac changes, previously observed in acute sepsis as potential drivers of SICM, partially persist in prolonged sepsis.

METHODS

In 24-week-old C57BL/6J mice, sepsis was induced by cecal ligation and puncture, followed by intravenous fluid resuscitation, subcutaneous analgesics and antibiotics, and, in the prolonged phase, by parenteral nutrition. Mice were killed after 5 days of sepsis (prolonged sepsis, n = 15). For comparison, we included acutely septic mice killed at 30 h (acute sepsis, n = 15) and healthy controls animals (HC, n = 15). Cardiac tissue was collected for assessment of inflammatory and metabolic markers through gene expression, metabolomic analysis and histological assessment.

RESULTS

In prolonged sepsis, cardiac expression of IL-1β and IL-6 and macrophage infiltration remained upregulated (p ≤ 0.05). In contrast, tissue levels of Krebs cycle intermediates and adenosine phosphates were normal, whereas NADPH levels were low in prolonged sepsis (p ≤ 0.05). Gene expression of fatty acid transporters and of the glucose transporter Slc2a1 was upregulated in prolonged sepsis (p ≤ 0.01). Lipid staining and glycogen content were elevated in prolonged sepsis together with increased gene expression of enzymes responsible for lipogenesis and glycogen synthesis (p ≤ 0.05). Intermediate glycolytic metabolites (hexose-phosphates, GADP, DHAP) were elevated (p ≤ 0.05), but gene expression of several enzymes for glycolysis and mitochondrial oxidation of pyruvate, fatty-acyl-CoA and ketone bodies to acetyl-CoA were suppressed in prolonged sepsis (p ≤ 0.05). Key metabolic transcription factors PPARα and PGC-1α were downregulated in acute, but upregulated in prolonged, sepsis (p ≤ 0.05 for both). Ketone body concentrations were normal but ketolytic enzymes remained suppressed (p ≤ 0.05). Amino acid metabolism showed mild, mixed changes.

CONCLUSIONS

Our results suggest myocardial lipid and glycogen accumulation and suppressed mitochondrial oxidation, with a functionally intact Krebs cycle, in the prolonged phase of sepsis, together with ongoing myocardial inflammation. Whether these alterations have functional consequences and predispose to long-term sequelae of SICM needs further research.

Critical illness-related corticosteroid insufficiency (CIRCI) - an overview of pathogenesis, clinical presentation and management

According to the Society of Critical Care Medicine, critical illness-related corticosteroid insufficiency (CIRCI) characterizes hypothalamic-adrenal axis insufficiency following acute medical conditions of various causes, i.e., sepsis, septic shock, acute respiratory distress syndrome, community-acquired pneumonia, and status after major surgical procedures. Due to highly variable etiology, understanding the pathomechanism and management of CIRCI assumes relevance for all centers providing intensive care. During CIRCI, multiple peripheral adaptations develop, and cortisol distribution volume increases due to hypothalamic-adrenal axis dysregulation, alterations in cortisol metabolism, and tissue resistance to corticosteroids. The proper diagnosis and treatment of CIRCI may be challenging in many cases. Although we have been acquainted with CIRCI since 2008, it remains a difficult condition with widely variable approaches among clinicians due to inconsistent high-quality study results determining the effect of corticosteroids on mortality. Corticosteroids are widely used in acutely ill patients, highlighting the necessity for reliable knowledge to support crucial clinicians' decisions in daily medical practice. In this review, we provide an overview of the clinical management of patients with CIRCI based on current recommendations and selected studies.

Mechanisms underlying delirium in patients with critical illness

Delirium is an acute, global cognitive disorder syndrome, also known as acute brain syndrome, characterized by disturbance of attention and awareness and fluctuation of symptoms. Its incidence is high among critically ill patients. Once patients develop delirium, it increases the risk of unplanned extubation, prolongs hospital stay, increases the risk of nosocomial infection, post-intensive care syndrome-cognitive impairment, and even death. Therefore, it is of great importance to understand how delirium occurs and to reduce the incidence of delirium in critically ill patients. This paper reviews the potential pathophysiological mechanisms of delirium in critically ill patients, with the aim of better understanding its pathophysiological processes, guiding the formulation of effective prevention and treatment strategies, providing a basis for clinical medication.

Diagnosing and treating the elderly individual with hypopituitarism

Hypopituitarism in the elderly is an underestimated condition mainly due to the non-specific presentation that can be attributed to the effects of aging and the presence of comorbidities. Diagnosis and treatment of hypopituitarism often represent a challenging task and this is even more significant in the elderly. Diagnosis can be insidious due to the physiological changes occurring with aging that complicate the interpretation of hormonal investigations, and the need to avoid some provocative tests that carry higher risks of side effects in this population. Treatment of hypopituitarism has generally the goal to replace the hormonal deficiencies to restore a physiological balance as close as possible to that of healthy individuals but in the elderly this must be balanced with the risks of over-replacement and worsening of comorbidities. Moreover, the benefit of some hormonal replacement therapies in the elderly, including sex hormones and growth hormone, remains controversial.

Body mass index, smoking behavior, and depression mediated the effects of schizophrenia on chronic obstructive pulmonary disease: trans-ethnic Mendelian-randomization analysis

Background

Previous studies have highlighted the association between schizophrenia (SCZ) and chronic obstructive pulmonary disease (COPD), yet the causal relationship remains unestablished.

Methods

Under the genome-wide significance threshold (P<5×10-8), data from individuals of European (EUR) and East Asian (EAS) ancestries with SCZ were selected for analysis. Univariable Mendelian randomization (MR) explored the causal relationship between SCZ and COPD. Linkage disequilibrium score (LDSC) regression was used to calculate genetic correlation, while multivariable and mediation MR further investigated the roles of six confounding factors and their mediating effects. The primary method utilized was inverse-variance weighted (IVW), complemented by a series of sensitivity analyses and false discovery rate (FDR) correction.

Results

LDSC analysis revealed a significant genetic correlation between SCZ and COPD within EUR ancestry (rg = 0.141, P = 6.16×10-7), with no such correlation found in EAS ancestry. IVW indicated a significant causal relationship between SCZ and COPD in EUR ancestry (OR = 1.042, 95% CI 1.013-1.071, P = 0.003, PFDR = 0.015). Additionally, replication datasets provide evidence of consistent causal associations(P < 0.05 & PFDR < 0.05). Multivariable and mediation MR analyses identified body mass index (BMI)(Mediation effect: 50.57%, P = 0.02), age of smoking initiation (Mediation effect: 27.42%, P = 0.02), and major depressive disorder (MDD) (Mediation effect: 60.45%, P = 6.98×10-5) as partial mediators of this causal relationship. No causal associations were observed in EAS (OR = 0.971, 95% CI 0.875-1.073, P = 0.571, PFDR = 0.761) ancestry. No causal associations were found in the reverse analysis across the four ancestries (P > 0.05 & PFDR > 0.05).

Conclusions

This study confirmed a causal relationship between SCZ and the risk of COPD in EUR ancestry, with BMI, smoking, and MDD serving as key mediators. Future research on a larger scale is necessary to validate the generalizability of these findings across other ancestries.

Abnormal DNA methylation within HPA-axis genes years after paediatric critical illness

BACKGROUND

Critically ill children suffer from impaired physical/neurocognitive development 2 years later. Glucocorticoid treatment alters DNA methylation within the hypothalamus-pituitary-adrenal (HPA) axis which may impair normal brain development, cognition and behaviour. We tested the hypothesis that paediatric-intensive-care-unit (PICU) patients, sex- and age-dependently, show long-term abnormal DNA methylation within the HPA-axis layers, possibly aggravated by glucocorticoid treatment in the PICU, which may contribute to the long-term developmental impairments.

RESULTS

In a pre-planned secondary analysis of the multicentre PEPaNIC-RCT and its 2-year follow-up, we identified differentially methylated positions and differentially methylated regions within HPA-axis genes in buccal mucosa DNA from 818 former PICU patients 2 years after PICU admission (n = 608 no glucocorticoid treatment; n = 210 glucocorticoid treatment) versus 392 healthy children and assessed interaction with sex and age, role of glucocorticoid treatment in the PICU and associations with long-term developmental impairments. Adjusting for technical variation and baseline risk factors and correcting for multiple testing (false discovery rate < 0.05), former PICU patients showed abnormal DNA methylation of 26 CpG sites (within CRHR1, POMC, MC2R, NR3C1, FKBP5, HSD11B1, SRD5A1, AKR1D1, DUSP1, TSC22D3 and TNF) and three DNA regions (within AVP, TSC22D3 and TNF) that were mostly hypomethylated. These abnormalities were sex-independent and only partially age-dependent. Abnormal methylation of three CpG sites within FKBP5 and one CpG site within SRD5A1 and AKR1D1 was partly attributable to glucocorticoid treatment during PICU stay. Finally, abnormal methylation within FKBP5 and AKR1D1 was most robustly associated with long-term impaired development.

CONCLUSIONS

Two years after critical illness in children, abnormal methylation within HPA-axis genes was present, predominantly within FKBP5 and AKR1D1, partly attributable to glucocorticoid treatment in the PICU, and explaining part of the long-term developmental impairments. These data call for caution regarding liberal glucocorticoid use in the PICU.