IDENTIFICATION AND CLINICAL VALIDATION OF HYPOXIA-INDUCIBLE FACTOR 1α PROTEIN AS THE POTENTIAL BIOMARKER IN PATIENTS WITH SEPSIS

Early hyperbaric oxygen therapy through regulating the HIF-1α signaling pathway attenuates Neuroinflammation and behavioral deficits in a mouse model of Sepsis-associated encephalopathy

BACKGROUND

Sepsis-associated encephalopathy (SAE) presents a significant clinical challenge, associated with increased mortality and healthcare expenses. Hyperbaric oxygen therapy (HBOT), involving inhaling pure or highly concentrated oxygen under pressures exceeding one atmosphere, has demonstrated neuroprotective effects in various conditions. However, the precise mechanisms underlying its protective actions against sepsis-associated brain injury remain unclear. This study aimed to determine whether HBOT protects against SAE and to elucidate the impact of the hypoxia-inducible factor-1α (HIF-1α) signaling pathway on SAE.

METHODS

The experiment consisted of two parts. In the first part, C57BL/6 J male mice were divided into five groups using a random number table method: control group, sham surgery group, sepsis group, HBOT + sepsis group, and HBOT + sham surgery group. In the subsequent part, C57BL/6 J male mice were divided into four groups: sepsis group, HBOT + sepsis group, HIF-1α + HBOT + sepsis group, and HIF-1α + sepsis group. Sepsis was induced via cecal ligation and puncture (CLP). Hyperbaric oxygen therapy was administered at 1 h and 4 h post-CLP. After 24 h, blood and hippocampal tissue were collected for cytokine measurements. HIF-1α, TNF-α, IL-1β, and IL-6 expression were assessed via ELISA and western blotting. Microglial expression was determined by immunofluorescence. Blood-brain barrier permeability was quantified using Evans Blue. Barnes maze and fear conditioning were conducted 14 days post-CLP to evaluate learning and memory.

RESULTS

Our findings reveal that CLP-induced hippocampus-dependent cognitive deficits coincided with elevated HIF-1α and increased TNF-α, IL-1β, and IL-6 levels in both blood and hippocampus. Observable activation of microglial cells in the hippocampus and increased blood-brain barrier (BBB) permeability were also evident. HBOT mitigated HIF-1α, TNF-α, IL-1β, and IL-6 levels, attenuated microglial activation in the hippocampus, and significantly improved learning and memory deficits in CLP-exposed mice. Additionally, these outcomes were corroborated by injecting a lentivirus that overexpressed HIF-1α into the hippocampal region of the mice.

CONCLUSION

HIF-1α escalation induced peripheral and central inflammatory factors, promoting microglial activation, BBB impairment, and cognitive dysfunction. However, HBOT ameliorated these effects by reducing HIF-1α levels in Sepsis-Associated Encephalopathy.

SIMULATED AEROMEDICAL EVACUATION EXACERBATES ACUTE LUNG INJURY VIA HYPOXIA-INDUCIBLE FACTOR 1Α-MEDIATED BNIP3/NIX-DEPENDENT MITOPHAGY

ABSTRACT

Background: With the advancement of medicine and the development of technology, the limiting factors of aeromedical evacuation are gradually decreasing, and the scope of indications is expanding. However, the hypobaric and hypoxic environments experienced by critically ill patients in flight can cause lung injury, leading to inflammation and hypoxemia, which remains one of the few limiting factors for air medical evacuation. This study aimed to examine the mechanism of secondary lung injury in rat models of acute lung injury that simulate aeromedical evacuation. Methods: An acute lung injury model was induced in SD rats by the administration of lipopolysaccharide (LPS) followed by exposure to a simulated aeromedical evacuation environment (equivalent to 8,000 feet above sea level) or a normobaric normoxic environment for 4 h. The expression of hypoxia-inducible factor 1α (HIF-1α) was stabilized by pretreatment with dimethyloxalylglycine. The reactive oxygen species levels and the protein expression levels of HIF-1α, Bcl-2-interacting protein 3 (BNIP3), and NIX in lung tissue were measured. Results: Simulated aeromedical evacuation exacerbated pathological damage to lung tissue and increased the release of inflammatory cytokines in serum as well as the reactive oxygen species levels and the protein levels of HIF-1α, BNIP3, and NIX in lung tissue. Pretreatment with dimethyloxalylglycine resulted in increases in the protein expression of HIF-1α, BNIP3, and NIX. Conclusion: Simulated aeromedical evacuation leads to secondary lung injury through mitophagy.

Unraveling the role of HIF-1α in sepsis: from pathophysiology to potential therapeutics-a narrative review

Sepsis is characterized by organ dysfunction resulting from a dysregulated inflammatory response triggered by infection, involving multifactorial and intricate molecular mechanisms. Hypoxia-inducible factor-1α (HIF-1α), a notable transcription factor, assumes a pivotal role in the onset and progression of sepsis. This review aims to furnish a comprehensive overview of HIF-1α's mechanism of action in sepsis, scrutinizing its involvement in inflammatory regulation, hypoxia adaptation, immune response, and organ dysfunction. The review encompasses an analysis of the structural features, regulatory activation, and downstream signaling pathways of HIF-1α, alongside its mechanism of action in the pathophysiological processes of sepsis. Furthermore, it will delve into the roles of HIF-1α in modulating the inflammatory response, including its association with inflammatory mediators, immune cell activation, and vasodilation. Additionally, attention will be directed toward the regulatory function of HIF-1α in hypoxic environments and its linkage with intracellular signaling, oxidative stress, and mitochondrial damage. Finally, the potential therapeutic value of HIF-1α as a targeted therapy and its significance in the clinical management of sepsis will be discussed, aiming to serve as a significant reference for an in-depth understanding of sepsis pathogenesis and potential therapeutic targets, as well as to establish a theoretical foundation for clinical applications.

Comparative Molecular and Biological Characteristic of the Systemic Inflammatory Response in Adult and Old Male Wistar Rats with Different Resistance to Hypoxia

Morphological, molecular, and biological features of the systemic inflammatory response induced by LPS administration were assessed in adult and old male Wistar rats with high and low resistance to hypoxia. In 6 h after LPS administration, mRNA expression levels of Hif1a, Vegf, Nfkb, and level of IL-1β protein in old rats were higher than in adult rats regardless of hypoxia tolerance. The morphometric study showed that the number of neutrophils in the interalveolar septa of the lungs was significantly higher in low-resistant adult and old rats 6 h after LPS administration. Thus, in old male Wistar rats, systemic inflammatory response is more pronounced than in adult rats and depends on the initial tolerance to hypoxia, which should be considered when developing new approaches to the therapy of systemic inflammatory response in individuals of different ages.

SECRETED TRYPTOPHANYL-tRNA SYNTHETASE 1 IS A PROGNOSTIC MARKER IN SEPSIS PATIENTS WITHOUT MONOCYTOPENIA

ABSTRACT

Objective: This study aimed to test whether the prognostic value of tryptophanyl-tRNA synthetase 1 (WARS1) for 28-day mortality in patients with sepsis was affected by monocytopenia. Methods: A prospective analysis of retrospectively collected samples from 74 sepsis patients was performed. WARS1, C-reactive protein (CRP), and procalcitonin were measured at admission and 24 and 72 h after admission. The prognostic value of WARS1, CRP, and procalcitonin for 28-day mortality was compared using repeated measures analysis of variance and the area under the receiver operating characteristic curve (AUROC). All analyses were performed in patients with or without monocytopenia, defined as an absolute monocyte count less than 0.1 × 10 9 cells/L. Results: WARS1 levels differed significantly between survivors and nonsurvivors when all patients and patients without monocytopenia were assessed ( P = 0.008, P < 0.001, respectively). In contrast, the WARS1 level did not differ between survivors and nonsurvivors with monocytopenia. C-reactive protein and procalcitonin levels were not different between survivors and nonsurvivors regardless of whether they had monocytopenia. The AUROCs of WARS1 at admission and 24 h for mortality were significantly higher in patients without monocytopenia (0.830, 0.818) than in patients with monocytopenia (0.232, 0.196; P < 0.001, both). When patients without monocytopenia were analyzed, the AUROCs of WARS1 for mortality were 0.830 and 0.818 at admission and 24 h, respectively, which were significantly higher than those of CRP (0.586, 0.653) and procalcitonin (0.456, 0.453) at the same time points ( P = 0.024 and 0.034, respectively). Conclusion: WARS1 is a useful biomarker for prognosis in sepsis patients without monocytopenia.

Hypoxia-inducible factor-1α is a biomarker for predicting patients with sepsis

OBJECTIVE

This study aimed to investigate the potential value of serum hypoxia-inducible factor-1α (HIF-1α) concentrations as a biomarker in patients with sepsis.

METHODS

The enrolled patients were divided into the following four groups: the intensive care unit (ICU) control group (n = 33), infection group (n = 29), septic nonshock group (n = 40), and septic shock group (n = 94). An enzyme-linked immunosorbent assay was used to measure serum HIF-1α concentrations on ICU admission. Clinical parameters and laboratory test results were also collected.

RESULTS

Serum HIF-1α concentrations were significantly higher in the infection group, septic nonshock group, and septic shock group than in the ICU control group. Moreover, HIF-1α concentrations were associated with a better predictive ability for diagnosing sepsis than the Acute Physiology and Chronic Health Evaluation II score, procalcitonin concentrations, and lactate concentrations. Patients with sepsis and HIF-1α concentrations >161.14 pg/mL had a poor prognosis.

CONCLUSIONS

Serum HIF-1α concentrations are a useful biomarker for the diagnosis of sepsis and predicting the prognosis of patients.

Elevated MMP-8 levels, inversely associated with BMI, predict mortality in mechanically ventilated patients: an observational multicenter study

BACKGROUND

The present study aimed to investigate the correlation between weight status and mortality in mechanically ventilated patients and explore the potential mediators.

METHODS

Three medical centers encompassing 3301 critically ill patients receiving mechanical ventilation were assembled for retrospective analysis to compare mortality across various weight categories of patients using machine learning algorithms. Bioinformatics analysis identified genes exhibiting differential expression among distinct weight categories. A prospective study was then conducted on a distinct cohort of 50 healthy individuals and 193 other mechanically ventilated patients. The expression levels of the genes identified through bioinformatics analysis were quantified through enzyme-linked immunosorbent assay (ELISA).

RESULTS

The retrospective analysis revealed that overweight individuals had a lower mortality rate than underweight individuals, and body mass index (BMI) was an independent protective factor. Bioinformatics analysis identified matrix metalloproteinase 8 (MMP-8) as a differentially expressed gene between overweight and underweight populations. The results of further prospective studies showed that overweight patients had significantly lower MMP-8 levels than underweight patients ((3.717 (2.628, 4.191) vs. 2.763 (1.923, 3.753), ng/ml, P = 0.002). High MMP-8 levels were associated with increased mortality risk (OR = 4.249, P = 0.005), indicating that elevated level of MMP-8 predicts the mortality risk of underweight patients receiving mechanical ventilation.

CONCLUSIONS

This study provides evidence for a protective effect of obesity in mechanically ventilated patients and highlights the potential role of MMP-8 level as a biomarker for predicting mortality risk in this population.