[Physiopathology of severe sepsis]

Therapeutic Approaches in Modulating the Inflammatory and Immunological Response in Patients With Sepsis, Acute Respiratory Distress Syndrome, and Pancreatitis: An Expert Opinion Review

Immunomodulation has long been an adjunct approach in treating critically ill patients with sepsis, acute respiratory distress syndrome (ARDS), and acute pancreatitis (AP). Hyperactive immune response with immunopathogenesis leads to organ dysfunction and alters the clinical outcomes in critically ill. Though the immune response in the critically ill might have been overlooked, it has gathered greater attention during this novel coronavirus disease 2019 (COVID-19) pandemic. Modulating hyperactive immune response, the cytokine storm, especially with steroids, has shown to improve the outcomes in COVID-19 patients. In this review, we find that immune response pathogenesis in critically ill patients with sepsis, ARDS, and AP is nearly similar. The use of immunomodulators such as steroids, broad-spectrum serine protease inhibitors such as ulinastatin, thymosin alpha, intravenous immunoglobulins, and therapies such as CytoSorb and therapeutic plasma exchange may help in improving the clinical outcomes in these conditions. As the experience of the majority of physicians in using such therapeutics may be limited, we provide our expert comments regarding immunomodulation to optimize outcomes in patients with sepsis/septic shock, ARDS, and AP.

Role of Nutrition Support in Inflammatory Conditions

This review intends to summarize recent development on the potential nutrition implications of acute inflammation encountered during critical illness. Different aspects of the inflammatory response and their impact on nutrition management during critical illness will be discussed: the timing of the postinjury metabolic response, the integration of regulatory mechanisms involved in the metabolic response to stress, the oxidative stress, the metabolic and clinical consequences in terms of energy expenditure, use of energy, changes in body composition, and behavior.

Antenatal exposure to chorioamnionitis affects lipid metabolism in 7-week-old sheep

Antenatal exposure of the fetus to inflammation may alter postnatal organ development. In our previous work, we demonstrated that the fetal liver is involved in the systemic inflammation associated with chorioamnionitis, leading to metabolic changes. On the basis of these findings, we hypothesized that chorioamnionitis can lead to postnatal inflammation-related liver injury and disturbed lipid metabolism. Chorioamnionitis was induced in sheep by intra-amniotic injection of lipopolysaccharide (LPS) or saline at 90, 100 and 110 days of gestation. Liver homeostasis and lipid metabolism were analyzed at term and at 7 weeks of age. At term, hepatic T-lymphocytes and apoptotic hepatocytes were increased. In addition, hepatic cholesterol and triglyceride levels were decreased in LPS-exposed animals compared with controls. At 7 weeks of age, no hepatic inflammation could be detected. However, liver triglycerides and plasma cholesterol levels were increased in LPS-exposed animals relative to controls. The changes in lipid levels at 7 weeks of age were associated with increased leptin receptor mRNA levels, increased lipid peroxidation, increased expression of cytochrome c oxidase subunit 4 as a marker for mitochondrial function and increased circulating ceramide levels. These findings demonstrate that chorioamnionitis-mediated antenatal inflammation-related liver disturbances have long-lasting postnatal effects on lipid metabolism.

Positive effect of septimeb™ on mortality rate in severe sepsis: a novel non antibiotic strategy

Background

Septimeb is a new herbal-derived remedy, recently approved for its potential immunomodulatory effects. Regarding the key role of immune system in the pathogenesis of severe sepsis and lack of any standard treatment for improving survival of these patients; we evaluated the effect of Septimeb -as an adjutant to standard treatment-on inflammatory biomarkers and mortality rates in patients with severe sepsis.

Methods

In this multicenter, randomized, single-blind trial, we assigned patients with severe sepsis and Acute Physiology and Chronic Health Evaluation (APACHE II) score of more than 20 to receive standard treatment of severe sepsis (control group) or standard treatment plus Septimeb. This group was treated with Septimeb for 14 days then followed up for another14 days. APACHE score, Sequential Organ Failure Assessment (SOFA) and Simplified Acute Physiology Score (SAPS) were calculated daily. Blood samples were analyzed for interleukin 2 tumor necrosis factor-α, total antioxidant power, platelet growth factor and matrix metalloproteinase 2.

Results

A total of 29 patients underwent randomization (13 in control group and 16 in Septimeb group). There was significant difference between the Septimeb and control group in the 14 days mortality rate (18.8% vs. 53.85 respectively, P=0.048). Compared to control group, Septimeb was significantly effective in improving SAPS (P= 0.029), SOFA (P=0.003) and APACHE II (P=0.008) scores. Inflammatory biomarkers didn’t change significantly between the two groups (P>0.05).

Conclusion

Septimeb reduces mortality rates among patients with severe sepsis and it could be added as a safe adjutant to standard treatment of sepsis.

Proinflammatory cytokines in heart failure: double-edged swords

Increased circulating and intracardiac levels of proinflammatory cytokines have been associated with chronic heart failure. Following an initial insult, the increased production of proinflammatory cytokines, including TNF-α, IL-6, IL-1, and IL-18, jeopardizes the surrounding tissue through propagation of the inflammatory response and direct effects on the cardiac myocyte structure and function. Cardiac myocyte hypertrophy, contractile dysfunction, cardiac myocyte apoptosis, and extracellular matrix remodeling contribute enormously to the development and progression of chronic heart failure. Despite the identification of efficacious pharmacological regimens and introduction of mechanical interventions, chronic heart failure remains among the leading causes of mortality worldwide. To introduce novel therapeutic strategies that modulate the inflammatory response in the context of the failing heart, it is of prime importance to determine the contributions of TNF-α, IL-6, IL-1, and IL-18 in mediating cardiac adaptive and maladaptive responses, as well as delineating their downstream intracellular signaling pathways and their potential therapeutic implications.

Chorioamnionitis induced hepatic inflammation and disturbed lipid metabolism in fetal sheep

Chorioamnionitis frequently induces a fetal inflammatory response syndrome (FIRS), characterized by an elevation of proinflammatory mediators and systemic inflammation. Although there is increasing evidence that inflammation and lipid metabolism influence each other, the effects of chorioamnionitis-induced FIRS on fetal lipid homeostasis are currently not known. Accordingly, we hypothesize that chorioamnionitis induces an inflammatory response in the fetal liver, consequently leading to metabolic disturbances. Chorioamnionitis was induced by intra-amniotic injection of 10 mg endotoxin (control) for 2 d or 2 wk before delivery. Saline injections were given to controls. The effect of chorioamnionitis on hepatic inflammation and metabolic parameters was analyzed in ovine fetuses at the GA of 125 d (normal GA = 150 d). We found that 2 d after the endotoxin injections, inflammatory markers were significantly higher compared with controls. In addition, lipid and glucose metabolism were disturbed in response to endotoxin. Moreover, the antioxidant state capacity was reduced, and hepatic damage was apparent. Two weeks after the endotoxin injections, the fetal livers were still inflamed and had higher glucose concentrations in the blood. In addition, the levels of markers for hepatic damage (alanine aminotransferase and aspartate aminotransferase) were increased. In conclusion, chorioamnionitis induces liver inflammation leading to metabolic disturbances in the fetus.

Vasoactive hormone adrenomedullin and its binding protein: anti-inflammatory effects by up-regulating peroxisome proliferator-activated receptor-gamma

Sepsis is a critical inflammatory condition from which numerous patients die due to multiple organ failure and septic shock. The vasoactive hormone adrenomedullin (AM) and its binding protein (AMBP-1) are beneficial in sepsis by abrogating the progression to irreversible shock and decreasing proinflammatory cytokine release. To investigate the anti-inflammatory mechanism, we studied to determine the effect of the AM/AMBP-1 complex on peroxisome proliferator-activated receptor-gamma (PPAR-gamma) expression and activation by using RAW264.7 cells and a rat endotoxemia model. LPS treatment significantly decreased PPAR-gamma expression in vivo and in vitro and was associated with increased TNF-alpha production. Treatment with AM/AMBP-1 for 4 h completely restored PPAR-gamma levels in both models, resulting in TNF-alpha suppression. In a knockdown model using small interfering RNA in RAW264.7 macrophages, AM/AMBP-1 failed to suppress TNF-alpha production in the absence of PPAR-gamma. LPS caused the suppression of intracellular cyclic AMP (cAMP), which was prevented by simultaneous AM/AMBP-1 treatment. Although incubation with dibutyryl cAMP significantly decreased LPS-induced TauNuF-alpha release, it did not alter PPAR-gamma expression. Through inhibition studies using genistein and PD98059 we found that the Pyk-2 tyrosine kinase-ERK1/2 pathway is in part responsible for the AM/AMBP-1-mediated induction of PPAR-gamma and the anti-inflammatory effect. We conclude that AM/AMBP-1 is protective in sepsis due to its vasoactive properties and direct anti-inflammatory effects mediated through both the cAMP-dependent pathway and Pyk-2-ERK1/2-dependent induction of PPAR-gamma.

Hyperbaric oxygen therapy prevents coagulation disorders in an experimental model of multiple organ failure syndrome

OBJECTIVE

To evaluate the effects of hyperbaric oxygen (HBO) therapy on the coagulation cascade using an experimental model of multiple organ failure syndrome (MOFS).

DESIGN

MOFS was induced by zymosan (500mg/kg i.p.) in rats. HBO therapy (2ATA) was administered in a cylindrical steel chamber 4 and 11h after zymosan administration. In a separate set of experiments animals were monitored for 72h, and systemic toxicity was scored.

INTERVENTION

Eighteen hours after zymosan administration, rats were killed and blood samples were used for analysis of hemocoagulative parameters, hemodynamics, and arterial blood gas.

MAIN RESULTS

Zymosan administration caused MOFS by affecting the coagulation cascade, as shown by a significant increase in plasma levels of fibrinogen, tissue plasminogen activator, inhibitor of tissue plasminogen activator of type 1, and plasma levels of fibrin degradation products vs. control rats. Zymosan-induced MOFS was also characterized by a significant increase in von Willebrand antigen plasma levels vs. controls. Moreover, zymosan administration induced a significant fall in mean arterial blood pressure and alteration in blood gas values. HBO therapy significantly reduced the derangements of coagulation cascade, the fall in mean blood pressure and alteration in blood gas induced by zymosan administration.

CONCLUSIONS

The hypercoagulability induced by zymosan could be responsible for organ failure and death. Our data demonstrate that HBO therapy significantly prevents the alteration in the coagulation cascade and arterial blood gas in an experimental model of MOFS.

Decreased circulating elastin peptide levels in humans with sepsis

OBJECTIVE

Sepsis is a potentially life-threatening medical condition induced by viral, bacterial or fungal infection, which is characterized by systemic inflammation, hypotension and vasodilation that can lead to cardiovascular collapse. Increased activity of elastases, enzymes which degrade the extracellular matrix components including elastin, has been demonstrated in plasma of septic patients. Since elastin peptides (EP), by binding to an elastin-laminin receptor on vascular endothelial and smooth muscle cells, induce dose-dependent vasodilation, we hypothesized that elevated circulating EP could contribute to the vasodilation that occurs in septic patients.

MATERIALS AND METHODS

Blood for measurement of EP was collected from not-septic and septic patients admitted to the intensive care unit (ICU), as well as from healthy subjects. Plasma EP concentrations were measured using a competitive ELISA technique.

RESULTS

The plasma EP level in the septic patients was approximately half that of the not-septic patients and the healthy controls, with similar EP levels in the latter two groups. There was no apparent association between EP levels and age or gender in any of the groups.

CONCLUSIONS

Plasma EP levels were actually decreased in septic patients, possibly indicating that the balance between EP production vs. elimination favors elimination. This result further suggests that circulating EP may not be important in the development of the vasodilation and hypotension that occurs in septic shock. Alternatively, however, increased degradation of EP by elastase or other enzymes could lead to the appearance of biologically active EP, which may not be recognized by the ELISA assay.

Nitrous oxide and risk of surgical wound infection: a randomised trial

BACKGROUND

Nitrous oxide inactivates vitamin B12 and methionine synthase, thereby impairing DNA formation and, consequently, new cell formation. The gas also inhibits methionine production, which can reduce scar formation and depresses chemotactic migration by monocytes. Therefore, we assessed whether nitrous oxide increases the incidence of surgical wound infection.

METHODS

We recruited 418 patients aged 18-80 years, scheduled for colon resection that was expected to last more than 2 h, at three hospitals in Austria and Hungary. Patients were randomly assigned 65% intraoperative nitrous oxide (n=208) or nitrogen (n=206), with remifentanil and isoflurane. The primary outcome was the incidence of clinical postoperative wound infection, analysed by intention to treat.

FINDINGS

206 patients in the nitrous oxide group and 202 in the nitrogen group were included in the final analysis. Duration of surgery was longer in the nitrogen group (3.4 h [1.5]) than in the nitrous oxide group (3.0 h [SD 1.3]) and arterial pressure (84 mm Hg [10] vs 81 mm Hg [9]), bispectral index values (53 [9] vs 44 [8]), and end-tidal isoflurane concentration (0.64% [0.14] vs 0.56% [0.13]) were greater in patients given nitrogen than in those given nitrous oxide. Infection rate was 15% (31/206) in patients given nitrous oxide and 20% (40/202) in those given nitrogen (p=0.205). Additionally, the ASEPSIS wound healing score, wound collagen deposition, number of patients admitted to critical care unit, time to first food ingestion, duration of hospital stay, and mortality did not differ between treatment groups.

INTERPRETATION

Nitrous oxide does not increase the incidence of surgical wound infection.

Molecular mechanisms involved in the pathogenesis of septic shock

Pathogenesis of the development of sepsis is highly complex and has been the object of study for many years. The inflammatory phenomena underlying septic shock are described in this review, as well as the enzymes and genes involved in the cellular activation that precedes this condition. The most important molecular aspects are discussed, ranging from the cytokines involved and their respective transduction pathways to the cellular mechanisms related to accelerated catabolism and multi-organic failure.

Mecanismos de resposta imune às infecções

O conhecimento dos principais mecanismos de defesa imune contra os diversos agentes infecciosos permite a compreensão da patogênese das doenças infectoparasitárias e das várias estratégias do hospedeiro e do parasita. O sistema imunológico atua numa rede de cooperação, envolvendo a participação de muitos componentes estruturais, moleculares e celulares. Nesse cenário encontra-se o delicado equilíbrio entre a saúde e a doença, em que tanto a deficiência quanto o exagero resultam em dano tecidual. Este artigo explora esses aspectos e algumas abordagens terapêuticas que surgem desse entendimento.