GENETIC DELETION OF TRANSLOCATOR PROTEIN EXACERBATES POST-SEPSIS SYNDROME WITH ACTIVATION OF THE C1Q PATHWAY IN SEPTIC MOUSE MODEL

Diagnostic utility of plasma translocator protein 18 kDa (TSPO) in sepsis: A case-control study

Translocator protein 18 kDa (TSPO) is a mitochondrial membrane protein that is involved in inflammation, oxidative stress, and steroidogenesis. TSPO may be a marker of inflammatory responses in the brain and other organs, but there have been few studies of the potential clinical significance of measuring the circulating TSPO concentration, especially in patients with sepsis. In this study, we compared the circulating TSPO concentrations of patients with sepsis and healthy controls to investigate the utility of plasma TSPO for the diagnosis of sepsis. Patients with sepsis admitted to the intensive care unit of Hiroshima University Hospital between January 2020 and April 2024 were enrolled. Plasma samples were collected from patients within 24 hours of admission and also from healthy volunteers, and their plasma TSPO concentrations were compared. Receiver operating characteristic analysis was used to evaluate the usefulness of plasma TSPO concentration for the diagnosis of sepsis. We also investigated the relationships of TSPO concentration with the severity of sepsis, complications, and prognosis of the patients. Eighty subjects (52 patients and 28 controls) were included in this study. The plasma TSPO concentrations of the patients with sepsis were significantly lower than those of the healthy controls (0.094 vs 0.25 ng/mL, P < .001), and receiver operating characteristic analysis generated an area under the curve of 0.81 (95% confidence interval: 0.72-0.91). In patients with sepsis, the TSPO concentration was not associated with the severity of sepsis, complications, or prognosis. Plasma TSPO may be a useful biomarker for the diagnosis of sepsis.

GENETIC ABLATION OF THE C-TYPE LECTIN RECEPTOR CLEC2D INCREASES PERITONITIS MORTALITY, INFLAMMATION, AND PHYSIOLOGY WITHOUT DIMINISHING ORGAN INJURY

ABSTRACT

Background: Sepsis accounts for substantial morbidity and mortality motivating investigators to continue the search for pathways and molecules driving the pathogenesis of the disease. The current study examined if the novel C-type lectin receptor (CLR), Clec2d, plays a significant role in the pathogenesis of sepsis. Methods: Clec2d knockout (KO) mice were fully backcrossed onto the C57/BL6 background. Acute endotoxemia was induced with an intraperitoneal injection of lipopolysaccharide (LPS). Sepsis was induced in two different models, cecal ligation and puncture (CLP) and Pseudomonas aeruginosa pneumonia. Both models were treated with antibiotics and fluid resuscitation. In the sepsis models, physiologic and hematologic measurements were measured at 24 h by collecting a small sample of peripheral blood. Mortality was followed for 14 days. Results : A total of 197 mice were studied, 58 wild type (WT) and 54 knock-out (KO) in the LPS model; 27 wild type and 21 KO mice in the CLP model; and 22 WT and 15 KO mice in the pneumonia model. Clec2d KO mice had greater mortality in the LPS and CLP studies but not the pneumonia model. There were significant differences in multiple parameters determined 24 h post sepsis between mice who subsequently died and those lived. Consistent with previous reports in the CLP model, higher concentrations of IL-6, increased numbers of peripheral blood lymphocytes and greater renal injury were found in the dying mice. In contrast, in the pneumonia model, IL-6 was higher in the surviving mice; however, the IL-6 levels in the pneumonia model (0.6 ± 0.3 ng/mL mean ± SEM) were less than 2% of the IL-6 levels of mice that died in the CLP model (41 ± 9 ng/mL, mean ± SEM). There were no differences in the lymphocyte count or renal injury between living and dying mice in the pneumonia model. In both sepsis models, dying mice had lower heart rates, respiratory rates, and body temperatures. These values were also lower in the KO mice compared to the WT in CLP, but the breath rate and body temperature were increased in the KO pneumonia mice. Conclusion: The C-type lectin receptor Clec2d plays a complicated role in the pathogenesis of sepsis, which varies with source of infection as demonstrated in the models used to study the disease. These data highlight the heterogeneity of the responses to sepsis and provide further evidence that a single common pathway driving sepsis organ injury and death likely does not exist.

Post-sepsis psychiatric disorder: Pathophysiology, prevention, and treatment

Post-sepsis psychiatric disorder, encompassing anxiety, depression, post-traumatic stress disorder and delirium, is a highly prevalent complication secondary to sepsis, resulting in a marked increase in long-term mortality among affected patients. Regrettably, psychiatric impairment associated with sepsis is frequently disregarded by clinicians. This review aims to summarize recent advancements in the understanding of the pathophysiology, prevention, and treatment of post-sepsis mental disorder, including coronavirus disease 2019-related psychiatric impairment. The pathophysiology of post-sepsis psychiatric disorder is complex and is known to involve blood-brain barrier disruption, overactivation of the hypothalamic-pituitary-adrenal axis, neuroinflammation, oxidative stress, neurotransmitter dysfunction, programmed cell death, and impaired neuroplasticity. No unified diagnostic criteria for this disorder are currently available; however, screening scales are often applied in its assessment. Modifiable risk factors for psychiatric impairment post-sepsis include the number of experienced traumatic memories, the length of ICU stay, level of albumin, the use of vasopressors or inotropes, daily activity function after sepsis, and the cumulative dose of dobutamine. To contribute to the prevention of post-sepsis psychiatric disorder, it may be beneficial to implement targeted interventions for these modifiable risk factors. Specific therapies for this condition remain scarce. Nevertheless, non-pharmacological approaches, such as comprehensive nursing care, may provide a promising avenue for treating psychiatric disorder following sepsis. In addition, although several therapeutic drugs have shown preliminary efficacy in animal models, further confirmation of their potential is required through follow-up clinical studies.