[Diagnosis and therapy of sepsis]

MicroLet-7b Regulates Neutrophil Function and Dampens Neutrophilic Inflammation by Suppressing the Canonical TLR4/NF-κB Pathway

Sepsis is a heterogeneous syndrome caused by a dysregulated host response during the process of infection. Neutrophils are involved in the development of sepsis due to their essential role in host defense. COVID-19 is a viral sepsis. Disfunction of neutrophils in sepsis has been described in previous studies, however, little is known about the role of microRNA-let-7b (miR-let-7b), toll-like receptor 4 (TLR4), and nuclear factor kappa B (NF-κB) activity in neutrophils and how they participate in the development of sepsis. In this study, we investigated the regulatory pathway of miR-let-7b/TLR4/NF-κB in neutrophils. We also explored the downstream cytokines released by neutrophils following miR-let-7b treatment and its therapeutic effects in cecal ligation and puncture (CLP)-induced septic mice. Six-to-eight-week-old male C57BL/6 mice underwent CLP following treatment with miR-let-7b agomir. Survival (n=10), changes in liver and lungs histopathology (n=4), circulating neutrophil counts (n=4), the liver-body weight ratio (n=4–7), and the lung wet-to-dry ratio (n=5–6) were recorded. We found that overexpression of miR-let-7b could significantly down-regulate the expression of human-derived neutrophilic TLR4 at a post-transcriptional level, a decreased level of proinflammatory factors including interleukin-6 (IL-6), IL-8, tumor necrosis factor α (TNF-α), and an upregulation of anti-inflammatory factor IL-10 in vitro. After miR-let-7b agomir treatment in vivo, neutrophil recruitment was inhibited and thus the injuries of liver and lungs in CLP-induced septic mice were alleviated (p=0.01 and p=0.04, respectively), less weight loss was reduced, and survival in septic mice was also significantly improved (p=0.013). Our study suggested that miR-let-7b could be a potential target of sepsis.

[Indocyanine green elimination for the evaluation of liver function: prognostic value in patients with community-acquired sepsis]

BACKGROUND

The aim of our clinical study was to correlate liver function measured by indocyanine green (ICG) elimination and clinical outcomes in patients with an early stage of community-acquired sepsis (CAS).

MATERIALS AND METHODS

A total of 341 patients (≥ 18 years) presenting with suspicion of CAS or evidence of an infection and fulfillment of ≥ 2 systemic inflammatory response syndrome (SIRS) criteria were included in the observational study"Prognosis of early sepsis 2" (Prognose der frühen Sepsis 2, ProFS 2). Patients who had been hospitalized within the last 7 days were excluded. In a subgroup of these patients (n = 72) who were transferred to an intensive or intermediate care unit according to the clinical judgment of the treating physicians, ICG elimination (plasma disappearance rate, ICG-PDR; 15 min retention rate, ICG-R15) was assessed by using a noninvasive monitoring system (LiMON, PULSION Medical Systems, Germany). ICG-PDR and -R15 were determined on the day of admission (n = 72) and after 96 h (n = 34). The primary end point of the study was defined as death within 30 days. Secondary endpoints were need for renal replacement therapy, requirement for invasive mechanical ventilation, and length of stay in an intermediate or intensive care unit.

RESULTS AND CONCLUSION

In contrast to patients with sepsis or severe sepsis, ICG elimination was found to be significantly impaired in patients with septic shock. Furthermore, a significant predictive value of ICG-PDR and -R15 on the day of admission for the need for subsequent renal replacement therapy (n = 12) was observed. In addition, reduced ICG elimination was associated with a longer stay in an intermediate or intensive care unit. However, ICG elimination on admission could not predict 30-day mortality (n = 14) or requirement of mechanical ventilation (n = 20).

Sepsis, leukocytes, and nitric oxide (NO): an intricate affair

Sepsis is exceedingly burdensome for hospital intensive care unit caregivers, and its incidence, as well as sepsis-related deaths, is increasing steadily. Sepsis is characterized by a robust increase in NO production throughout the organism that is driven by iNOS. Moreover, NO is an important factor in the development of septic shock and is synthesized by NOS, an enzyme expressed by a variety of cells, including vascular endothelium, macrophages, and neutrophils. However, the effects of NO on leukocyte functions, and the underlying mechanisms, are relatively unknown. Thus, the present review focuses on the effects of NO and its derivatives on cells of the immune system. Experimental evidences discussed herein show that NO induces posttranslational modifications of key proteins in targeted processes with the potential of deterring cellular physiology. Consequently, the manipulation of NO distribution in septic patients, used in conjunction with conventional treatments aimed at restoring normal immune functions, may represent a valuable therapeutic strategy.

Effects of mild hypothermia on hemodynamics in cardiac arrest survivors and isolated failing human myocardium

Post-cardiac arrest myocardial dysfunction is a common phenomenon after return of spontaneous circulation (ROSC) and contributes to hemodynamic instability and low survival rates after cardiac arrest. Mild hypothermia for 24 h after ROSC has been shown to significantly improve neurologic recovery and survival rates. In the present study we investigate the influence of therapeutic hypothermia on hemodynamic parameters in resuscitated patients and on contractility in failing human myocardium. We analyzed hemodynamic data from 200 cardiac arrest survivors during the hypothermia period. The initial LVEF was 32.6 +/- 1.2% indicating a significantly impaired LV function. During hypothermia induction, the infusion rate of epinephrine could be significantly reduced from 9.1 +/- 1.3 microg/min [arrival intensive care unit (ICU) 35.4 degrees C] to 4.6 +/- 1.0 microg/min (34 degrees C) and 2.8 +/- 0.5 microg/min (33 degrees C). The dobutamine and norepinephrine application rates were not changed significantly. The mean arterial blood pressure remained stable. The mean heart rate significantly decreased from 91.8 +/- 1.7 bpm (arrival ICU) to 77.3 +/- 1.5 bpm (34 degrees C) and 70.3 +/- 1.4 bpm (33 degrees C). In vitro we investigated the effect of hypothermia on isolated ventricular muscle strips from explanted failing human hearts. With decreasing temperature, the contractility increased to a maximum of 168 +/- 23% at 27 degrees C (n = 16, P < 0.05). Positive inotropic response to hypothermia was accompanied by moderately increased rapid cooling contractures as a measure of sarcoplasmic reticulum (SR) Ca(2+) content, but can be elicited even when the SR Ca(2+) release is blocked in the presence of ryanodine. Contraction and relaxation kinetics are prolonged with hypothermia, indicating increased Ca(2+) sensitivity as the main mechanism responsible for inotropy. In conclusion, mild hypothermia stabilizes hemodynamics in cardiac arrest survivors which might contribute to improved survival rates in these patients. Mechanistically, we demonstrate that hypothermia improves contractility in failing human myocardium most likely by increasing Ca(2+)-sensitivity.

Alterations of neuropeptides in the human gut during peritonitis

BACKGROUND AND AIMS

Gastrointestinal motility is reduced during sepsis but the pathomechanism involved is poorly understood. We investigated the expression of substance P (SP) and vasoactive intestinal peptide (VIP) in the myenteric plexus during peritonitis in human small bowel.

MATERIALS AND METHODS

Tissue samples of the small bowel were gathered from healthy patients and from patients with peritonitis. Immunohistochemistry for myeloperoxidase (MPO), SP, and VIP was performed in whole mount sections. To determine the level of inflammation, MPO-positive cells were counted in the circular muscle layer. SP and VIP immunoreactivity was analyzed in myenteric plexus neurons. The area of positive immunoreactivity for either neuropeptide within the plexus was analyzed and set in relation to the total area of the plexus and consecutively expressed as percentage.

RESULTS

During peritonitis, MPO-positive cells significantly increased by approximately fourfold as compared to healthy tissue. The immunoreactivity for SP was significantly reduced by approximately 80% in myenteric plexus neurons during peritonitis. In contrast, the immunoreactivity for VIP significantly increased by nearly twofold during peritonitis.

CONCLUSIONS

During peritonitis, the inflammatory reaction within the gut is increased. The neuropeptide expression in myenteric plexus neurons was observed as shifting towards increased expression of VIP, known to inhibit intestinal motility, and towards decreased expression of the prokinetic neuropeptide SP.