Iron dysregulation combined with aging prevents sepsis-induced apoptosis

Comparison of the National Early Warning Scores and Rapid Emergency Medicine Scores with the APACHE II Scores as a Prediction of Mortality in Patients with Medical Emergency Team Activation: a Single-centre Retrospective Cohort Study

Introduction

The medical emergency team enables the limitation of patients’ progression to critical illness in the general ward. The early warning scoring system (EWS) is one of the criteria for medical emergency team activation; however, it is not a valid criterion to predict the prognosis of patients with MET activation.

Aim

In this study, the National Early Warning Score (NEWS) and Rapid Emergency Medicine Score (REMS) was compared with that of the Acute Physiology and Chronic Health Evaluation II (APACHE II) score in predicting the prognosis of patients who had been treated a medical emergency team.

Material and Methods

In this single-centre retrospective cohort study, patients treated by a medical emergency team between April 2013 and March 2019 and the 28-day prognosis of MET-activated patients were assessed using APACHE II, NEWS, and REMS.

Results

Of the 196 patients enrolled, 152 (77.5%) were men, and 44 (22.5%) were women. Their median age was 68 years (interquartile range: 57-76 years). The most common cause of medical emergency team activation was respiratory failure (43.4%). Univariate analysis showed that APACHE II score, NEWS, and REMS were associated with 28-day prognostic mortality. There was no significant difference in the area under the receiver operating characteristic curve of APACHE II (0.76), NEWS (0.67), and REMS (0.70); however, the sensitivity of NEWS (0.70) was superior to that of REMS (0.47).

Conclusion

NEWS is a more sensitive screening tool like APACHE II than REMS for predicting the prognosis of patients with medical emergency team activation. However, because the accuracy of NEWS was not sufficient compared with that of APACHE II score, it is necessary to develop a screening tool with higher sensitivity and accuracy that can be easily calculated at the bedside in the general ward.

Post-intensive care syndrome: its pathophysiology, prevention, and future directions

Expanding elderly populations are a major social challenge in advanced countries worldwide and have led to a rapid increase in the number of elderly patients in intensive care units (ICUs). Innovative advances in medical technology have enabled lifesaving of patients in ICUs, but there remain various problems to improve their long-term prognoses. Post-intensive care syndrome (PICS) refers to physical, cognition, and mental impairments that occur during ICU stay, after ICU discharge or hospital discharge, as well as the long-term prognosis of ICU patients. Its concept also applies to pediatric patients (PICS-p) and the mental status of their family (PICS-F). Intensive care unit-acquired weakness, a syndrome characterized by acute symmetrical limb muscle weakness after ICU admission, belongs to physical impairments in three domains of PICS. Prevention of PICS requires performance of the ABCDEFGH bundle, which incorporates the prevention of delirium, early rehabilitation, family intervention, and follow-up from the time of ICU admission to the time of discharge. Diary, nutrition, nursing care, and environmental management for healing are also important in the prevention of PICS. This review outlines the pathophysiology, prevention, and future directions of PICS.

Immunosenescence in neurocritical care

BACKGROUND

Several advanced and developing countries are now entering a superaged society, in which the percentage of elderly people exceeds 20% of the total population. In such an aging society, the number of age-related diseases such as malignant tumors, diabetes, and severe infections including sepsis is increasing, and patients with such disorders often find themselves in the ICU.

MAIN BODY

Age-related diseases are closely related to age-induced immune dysfunction, by which reductions in the efficiency and specificity of the immune system are collectively termed "immunosenescence." The most noticeable is a decline in the antigen-specific acquired immune response. The exhaustion of T cells in elderly sepsis is related to an increase in nosocomial infections after septicemia, and even death over subacute periods. Another characteristic is that senescent cells that accumulate in body tissues over time cause chronic inflammation through the secretion of proinflammatory cytokines, termed senescence-associated secretory phenotype. Chronic inflammation associated with aging has been called "inflammaging," and similar age-related diseases are becoming an urgent social problem.

CONCLUSION

In neuro ICUs, several neuro-related diseases including stroke and sepsis-associated encephalopathy are related to immunosenescence and neuroinflammation in the elderly. Several advanced countries with superaged societies face the new challenge of improving the long-term prognosis of neurocritical patients.

Towards a unifying, systems biology understanding of large-scale cellular death and destruction caused by poorly liganded iron: Parkinson's, Huntington's, Alzheimer's, prions, bactericides, chemical toxicology and others as examples

Exposure to a variety of toxins and/or infectious agents leads to disease, degeneration and death, often characterised by circumstances in which cells or tissues do not merely die and cease to function but may be more or less entirely obliterated. It is then legitimate to ask the question as to whether, despite the many kinds of agent involved, there may be at least some unifying mechanisms of such cell death and destruction. I summarise the evidence that in a great many cases, one underlying mechanism, providing major stresses of this type, entails continuing and autocatalytic production (based on positive feedback mechanisms) of hydroxyl radicals via Fenton chemistry involving poorly liganded iron, leading to cell death via apoptosis (probably including via pathways induced by changes in the NF-κB system). While every pathway is in some sense connected to every other one, I highlight the literature evidence suggesting that the degenerative effects of many diseases and toxicological insults converge on iron dysregulation. This highlights specifically the role of iron metabolism, and the detailed speciation of iron, in chemical and other toxicology, and has significant implications for the use of iron chelating substances (probably in partnership with appropriate anti-oxidants) as nutritional or therapeutic agents in inhibiting both the progression of these mainly degenerative diseases and the sequelae of both chronic and acute toxin exposure. The complexity of biochemical networks, especially those involving autocatalytic behaviour and positive feedbacks, means that multiple interventions (e.g. of iron chelators plus antioxidants) are likely to prove most effective. A variety of systems biology approaches, that I summarise, can predict both the mechanisms involved in these cell death pathways and the optimal sites of action for nutritional or pharmacological interventions.

Effects of aging on the immunopathologic response to sepsis

OBJECTIVE

Aging is associated with increased inflammation following sepsis. The purpose of this study was to determine whether this represents a fundamental age-based difference in the host response or is secondary to the increased mortality seen in aged hosts.

DESIGN

Prospective, randomized controlled study.

SETTING

Animal laboratory in a university medical center.

SUBJECTS

Young (6-12 weeks) and aged (20-24 months) FVB/N mice.

INTERVENTIONS

Mice were subjected to 2 x 25 or 1 x 30 cecal ligation and puncture (CLP).

MEASUREMENTS AND MAIN RESULTS

Survival was similar in young mice subjected to 2 x 25 CLP and aged mice subjected to 1 x 30 CLP (p = 0.15). Young mice subjected to 1 x 30 CLP had improved survival compared with the other groups (p < 0.05). When injury was held constant but mortality was greater, both systemic and peritoneal levels of tumor necrosis factor-alpha, interleukin (IL)-6, IL-10, and monocyte chemotactic protein-1 were elevated 24 hours after CLP in aged animals compared with young animals (p < 0.05). When mortality was similar but injury severity was different, there were no significant differences in systemic cytokines between aged mice and young mice. In contrast, peritoneal levels of tumor necrosis factor-alpha, IL-6, and IL-10 were higher in aged mice subjected to 1 x 30 CLP than young mice subjected to 2 x 25 CLP despite their similar mortalities (p < 0.05). There were no significant differences in either bacteremia or peritoneal cultures when animals of different ages sustained similar injuries or had different injuries with similar mortalities.

CONCLUSIONS

Aged mice are more likely to die of sepsis than young mice when subjected to an equivalent insult, and this is associated with increases in both systemic and local inflammation. There is an exaggerated local but not systemic inflammatory response in aged mice compared with young mice when mortality is similar. This suggests that systemic processes that culminate in death may be age independent, but the local inflammatory response may be greater with aging.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

Epithelial apoptosis in mechanistically distinct methods of injury in the murine small intestine

Gut epithelial apoptosis is involved in the pathophysiology of multiple diseases. This study characterized intestinal apoptosis in three mechanistically distinct injuries with different kinetics of cell death. FVB/N mice were subjected to gamma radiation, Pseudomonas aeruginosa pneumonia or injection of monoclonal anti-CD3 antibody and sacrificed 4, 12, or 24 hours post-injury (n=10/time point). Apoptosis was quantified in the jejunum by hematoxylin and eosin (H&E), active caspase-3, terminal deoxynucleotidyl transferase dUTP-mediated nick end labeling (TUNEL), in situ oligoligation reaction (ISOL,) cytokeratin 18, and annexin V staining. Reproducible results were obtained only for H&E, active caspase-3, TUNEL and ISOL, which were quantified and compared against each other for each injury at each time point. Kinetics of injury were different with early apoptosis highest following radiation, late apoptosis highest following anti CD3, and more consistent levels following pneumonia. ISOL was the most consistent stain and was always statistically indistinguishable from at least 2 stains. In contrast, active caspase-3 demonstrated lower levels of apoptosis, while the TUNEL assay had higher levels of apoptosis in the most severely injured intestine regardless of mechanism of injury. H&E was a statistical outlier more commonly than any other stain. This suggests that regardless of mechanism or kinetics of injury, ISOL correlates to other quantification methods of detecting gut epithelial apoptosis more than any other method studied and compares favorably to other commonly accepted techniques of quantifying apoptosis in a large intestinal cross sectional by balancing sensitivity and specificity across a range of times and levels of death.