Endothelial cell metabolism in sepsis

PTP1B inhibitor alleviates deleterious septic lung injury through Src signaling

Septic lung injury is an unmet clinical challenge due to its high mortality, and there is a lack of effective treatment. Accumulating evidence suggests that an uncontrolled pulmonary inflammatory response is important in the pathogenesis of lung injury in sepsis. Therefore, limiting excessive early inflammatory responses may be an effective strategy. We established a septic lung injury model using cecal ligation and puncture. Western blotting and immunofluorescence analyses were performed to assess the expression of PTP1B and endoplasmic reticulum (ER) stress and pyroptosis. Co-immunoprecipitation was used to analyze the binding of PTP1B and Src molecules. PTP1B is upregulated in both in vivo and in vitro models of septic lung injury. PTP1B directly binds to Src and aggravates inflammation by regulating the ER stress-pyroptosis axis. The inhibition of PTP1B alleviates inflammation and improves the prognosis of septic mice. Our study suggesting that PT1B inhibitors have clinical application value in the treatment of septic lung injury. This may provide a new strategy for the treatment of septic lung injury.

Control of inflammatory lung injury and repair by metabolic signaling in endothelial cells

PURPOSE OF REVIEW

Sepsis-induced inflammatory lung injury includes acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). There are currently no effective treatments for ALI/ARDS, but clinical outcomes could be improved by inhibiting lung injury and/or promoting post-sepsis vascular repair. In this review, we describe studies of endothelial cell metabolic pathways in sepsis-induced ALI/ARDS and vascular repair and identify areas of research that deserve attention in future studies. We also describe studies of metabolic interventions that aim to inhibit ALI/ARDS and/or promote post-sepsis vascular repair, including those that target endothelial cell metabolites, endothelial cell metabolic signaling pathways, and endothelial cell metabolism.

RECENT FINDINGS

Endothelial cells are integral to both the injury and repair phases of ALI/ARDS. During the injury phase of ALI/ARDS, lung endothelial cell survival decreases, and lung endothelial cell-to-endothelial cell (EC-EC) junctions are weakened. During the repair phase after sepsis-induced lung injury, lung endothelial cell proliferation and lung EC-EC junction reannealing occur. These crucial aspects of ALI/ARDS and post-sepsis vascular repair, that is, endothelial cell viability, growth, and junction integrity, are controlled by a myriad of metabolites and metabolic signaling pathways in endothelial cells.

SUMMARY

Metabolic signaling pathways in endothelial cells represent a novel class of putative targets for the prevention and treatment of sepsis-induced inflammatory lung injury. Therapies that target metabolic signaling in endothelial cells are currently being explored as potential treatments for sepsis-induced inflammatory lung injury.

Tumor necrosis factor receptor 2 promotes endothelial cell-mediated suppression of CD8+ T cells through tuning glycolysis in chemoresistance of breast cancer

BACKGROUND

T cells play a pivotal role in chemotherapy-triggered anti-tumor effects. Emerging evidence underscores the link between impaired anti-tumor immune responses and resistance to paclitaxel therapy in triple-negative breast cancer (TNBC). Tumor-related endothelial cells (ECs) have potential immunoregulatory activity. However, how ECs regulate T cell activity during TNBC chemotherapy remains poorly understood.

METHODS

Single-cell analysis of ECs in patients with TNBC receiving paclitaxel therapy was performed using an accessible single-cell RNA sequencing (scRNA-seq) dataset to identify key EC subtypes and their immune characteristics. An integrated analysis of a tumor-bearing mouse model, immunofluorescence, and a spatial transcriptome dataset revealed the spatial relationship between ECs, especially Tumor necrosis factor receptor (TNFR) 2+ ECs, and CD8+ T cells. RNA sequencing, CD8+ T cell proliferation assays, flow cytometry, and bioinformatic analyses were performed to explore the immunosuppressive function of TNFR2 in ECs. The downstream metabolic mechanism of TNFR2 was further investigated using RNA sequencing, cellular glycolysis assays, and western blotting.

RESULTS

In this study, we identified an immunoregulatory EC subtype, characterized by enhanced TNFR2 expression in non-responders. By a mouse model of TNBC, we revealed a dynamic reduction in the proportion of the CD8+ T cell-contacting tumor vessels that could co-localize spatially with CD8+ T cells during chemotherapy and an increased expression of TNFR2 by ECs. TNFR2 suppresses glycolytic activity in ECs by activating NF-κB signaling in vitro. Tuning endothelial glycolysis enhances programmed death-ligand (PD-L) 1-dependent inhibitory capacity, thereby inducing CD8+ T cell suppression. In addition, TNFR2+ ECs showed a greater spatial affinity for exhausted CD8+ T cells than for non-exhausted CD8+ T cells. TNFR2 blockade restores impaired anti-tumor immunity in vivo, leading to the loss of PD-L1 expression by ECs and enhancement of CD8+ T cell infiltration into the tumors.

CONCLUSIONS

These findings reveal the suppression of CD8+ T cells by ECs in chemoresistance and indicate the critical role of TNFR2 in driving the immunosuppressive capacity of ECs via tuning glycolysis. Targeting endothelial TNFR2 may serve as a potent strategy for treating TNBC with paclitaxel.

Physiologic disruption and metabolic reprogramming in infection and sepsis

Effective responses against severe systemic infection require coordination between two complementary defense strategies that minimize the negative impact of infection on the host: resistance, aimed at pathogen elimination, and disease tolerance, which limits tissue damage and preserves organ function. Resistance and disease tolerance mostly rely on divergent metabolic programs that may not operate simultaneously in time and space. Due to evolutionary reasons, the host initially prioritizes the elimination of the pathogen, leading to dominant resistance mechanisms at the potential expense of disease tolerance, which can contribute to organ failure. Here, we summarize our current understanding of the role of physiological perturbations resulting from infection in immune response dynamics and the metabolic program requirements associated with resistance and disease tolerance mechanisms. We then discuss how insight into the interplay of these mechanisms could inform future research aimed at improving sepsis outcomes and the potential for therapeutic interventions.

Molecular mechanism of Xuebijing in treating pyogenic liver abscess complicated with sepsis

BACKGROUND

Xuebijing (XBJ) can alleviate the inflammatory response, improve organ function, and shorten the intensive care unit (ICU) stay in patients with pyogenic liver abscess (PLA) complicated with sepsis, but the molecular mechanisms have not been elucidated. This study aimed to explore the molecular mechanism of XBJ in treating PLA complicated with sepsis using a network pharmacology approach.

METHODS

The active ingredients and targets of XBJ were retrieved from the ETCM database. Potential targets related to PLA and sepsis were retrieved from the GeneCards, PharmGKB, DisGeNet, Online Mendelian Inheritance in Man (OMIM), Therapeutic Targets Database (TTD), and DrugBank databases. The targets of PLA complicated with sepsis were mapped to the targets of XBJ to identify potential treatment targets. Protein-protein interaction networks were analyzed using the STRING database. Potential treatment targets were imported into the Metascape platform for Gene Ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Molecular docking was performed to validate the interactions between active ingredients and core targets.

RESULTS

XBJ was found to have 54 potential treatment targets for PLA complicated with sepsis. Interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor (TNF) were identified as core targets. KEGG enrichment analysis revealed important pathways, including the interleukin-17 (IL-17) signaling pathway, the TNF signaling pathway, the nuclear factor-kappa B (NF-κB) signaling pathway, and the Toll-like receptor (TLR) signaling pathway. Molecular docking experiments indicated stable binding between XBJ active ingredients and core targets.

CONCLUSION

XBJ may exert therapeutic effects on PLA complicated with sepsis by modulating signaling pathways, such as the IL-17, TNF, NF-κB, and TLR pathways, and targeting IL-1β, IL-6, and TNF.

Xuebijing improves intestinal microcirculation dysfunction in septic rats by regulating the VEGF-A/PI3K/Akt signaling pathway

BACKGROUND

This study aims to explore whether Xuebijing (XBJ) can improve intestinal microcirculation dysfunction in sepsis and its mechanism.

METHODS

A rat model of sepsis was established by cecal ligation and puncture (CLP). A total of 30 male SD rats were divided into four groups: sham group, CLP group, XBJ + axitinib group, and XBJ group. XBJ was intraperitoneally injected 2 h before CLP. Hemodynamic data (blood pressure and heart rate) were recorded. The intestinal microcirculation data of the rats were analyzed via microcirculation imaging. Enzyme-linked immunosorbent assay (ELISA) kits were used to detect the serum levels of interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor-α (TNF-α) in the rats. Histological analysis and transmission electron microscopy were used to analyze the injury of small intestinal microvascular endothelial cells and small intestinal mucosa in rats. The expression of vascular endothelial growth factor A (VEGF-A), phosphoinositide 3-kinase (PI3K), phosphorylated PI3K (p-PI3K), protein kinase B (Akt), and phosphorylated Akt (p-Akt) in the small intestine was analyzed via Western blotting.

RESULTS

XBJ improved intestinal microcirculation dysfunction in septic rats, alleviated the injury of small intestinal microvascular endothelial cells and small intestinal mucosa, and reduced the systemic inflammatory response. Moreover, XBJ upregulated the expression of VEGF-A, p-PI3K/total PI3K, and p-Akt/total Akt in the rat small intestine.

CONCLUSION

XBJ may improve intestinal microcirculation dysfunction in septic rats possibly through the VEGF-A/PI3K/Akt signaling pathway.

Organotypic heterogeneity in microvascular endothelial cell responses in sepsis-a molecular treasure trove and pharmacological Gordian knot

In the last decades, it has become evident that endothelial cells (ECs) in the microvasculature play an important role in the pathophysiology of sepsis-associated multiple organ dysfunction syndrome (MODS). Studies on how ECs orchestrate leukocyte recruitment, control microvascular integrity and permeability, and regulate the haemostatic balance have provided a wealth of knowledge and potential molecular targets that could be considered for pharmacological intervention in sepsis. Yet, this information has not been translated into effective treatments. As MODS affects specific vascular beds, (organotypic) endothelial heterogeneity may be an important contributing factor to this lack of success. On the other hand, given the involvement of ECs in sepsis, this heterogeneity could also be leveraged for therapeutic gain to target specific sites of the vasculature given its full accessibility to drugs. In this review, we describe current knowledge that defines heterogeneity of organ-specific microvascular ECs at the molecular level and elaborate on studies that have reported EC responses across organ systems in sepsis patients and animal models of sepsis. We discuss hypothesis-driven, single-molecule studies that have formed the basis of our understanding of endothelial cell engagement in sepsis pathophysiology, and include recent studies employing high-throughput technologies. The latter deliver comprehensive data sets to describe molecular signatures for organotypic ECs that could lead to new hypotheses and form the foundation for rational pharmacological intervention and biomarker panel development. Particularly results from single cell RNA sequencing and spatial transcriptomics studies are eagerly awaited as they are expected to unveil the full spatiotemporal signature of EC responses to sepsis. With increasing awareness of the existence of distinct sepsis subphenotypes, and the need to develop new drug regimen and companion diagnostics, a better understanding of the molecular pathways exploited by ECs in sepsis pathophysiology will be a cornerstone to halt the detrimental processes that lead to MODS.

Multi-Omics Endotypes in ICU Sepsis-Induced Immunosuppression

It is evident that the admission of some patients with sepsis and septic shock to hospitals is occurring late in their illness, which has contributed to the increase in poor outcomes and high fatalities worldwide across age groups. The current diagnostic and monitoring procedure relies on an inaccurate and often delayed identification by the clinician, who then decides the treatment upon interaction with the patient. Initiation of sepsis is accompanied by immune system paralysis following "cytokine storm". The unique immunological response of each patient is important to define in terms of subtyping for therapy. The immune system becomes activated in sepsis to produce interleukins, and endothelial cells express higher levels of adhesion molecules. The proportions of circulating immune cells change, reducing regulatory cells and increasing memory cells and killer cells, having long-term effects on the phenotype of CD8 T cells, HLA-DR, and dysregulation of microRNA. The current narrative review seeks to highlight the potential application of multi-omics data integration and immunological profiling at the single-cell level to define endotypes in sepsis and septic shock. The review will consider the parallels and immunoregulatory axis between cancer and immunosuppression, sepsis-induced cardiomyopathy, and endothelial damage. Second, the added value of transcriptomic-driven endotypes will be assessed through inferring regulatory interactions in recent clinical trials and studies reporting gene modular features that inform continuous metrics measuring clinical response in ICU, which can support the use of immunomodulating agents.