Molecular Mechanisms of Vascular Damage During Lung Injury

Bae²,

et al. 2023

J Inflamm

Background Acute lung injury (ALI) is a life-threatening condition that fundamentally results from inflammation and edema in the lung. There are no effective treatments available for clinical use. Previously, we found that as a leakage blocker CU06-1004 prevents endothelial barrier disruption and enhances endothelial cell survival under inflammatory conditions. In this study, we aimed to elucidate the effect of CU06-1004 in terms of prevention of inflammation and endothelial dysfunction in an ALI mouse model. Methods An ALI model was established that included intraperitoneal administration of LPS. Following LPS administration, survival rates and lung wet/dry ratios were assessed. Histological analysis was performed using hematoxylin and eosin staining. Scanning electron microscopy was used to examine alveolar and capillary morphology. Cytokines such as IL-1β, IL-6, and TNF-α were analyzed using an ELISA assay of bronchoalveolar lavage fluid (BALF) and serum. Neutrophil infiltration was observed in BALF using Wright-Giemsa staining, and myeloperoxidase (MPO) activity was assessed. Pulmonary vascular leakage was confirmed using Evans-blue dye, and the expression of junctional proteins was evaluated using immunofluorescent staining. Expression of adhesion molecules was observed using immunofluorescence staining. NF-κB activation was determined using immunohistochemistry and western blot analysis. Results Survival rates and pulmonary edema were ameliorated with CU06-1004 treatment. Administration of CU06-1004 normalized histopathological changes induced by LPS, and alveolar-capillary wall thickening was reduced. Compared with the LPS-challenged group, after CU06-1004 treatment, the infiltration of immune cells was decreased in the BALF, and MPO activity in lung tissue was reduced. Similarly, in the CU06-1004 treatment group, pro-inflammatory cytokines were significantly inhibited in both BALF and serum. Evans-blue leakage was reduced, and the expression of junctional proteins was recovered in the CU06-1004 group. Adhesion molecules were downregulated and NF-κB activation was inhibited after CU06-1004 treatment. Conclusions These results suggested that CU06-1004 had a therapeutic effect against LPS-induced ALI via alleviation of the inflammatory response and protection of vascular integrity.

Section: Discussionmentioning

confidence: 99%

Efficacy of CU06-1004 via regulation of inflammation and endothelial permeability in LPS-induced acute lung injury

Bae²,

et al. 2023

J Inflamm

“…To repress transcription of certain genes, previous work has indicated that NF-κB subunits act in concert with several other proteins including the class I HDACs ( Ashburner et al, 2001 ). A number of studies in the last two decades have revealed a complex multileveled modulation of ALI/ARDS pathological mechanism including global epigenetic regulation of the gene expression (reviewed in ( Bossardi Ramos and Adam, 2021 )). Previously, the barrier-disruptive effect of cytoplasmic class II HDAC6 has been studied in detail ( Joshi et al, 2015 ; Yu et al, 2016a ; Borgas et al, 2016 ; Yu et al, 2016b ) demonstrating the involvement of this enzyme in a number of critical events such as the deacetylation (destabilizing) of microtubules ( Borgas et al, 2016 ; Karki et al, 2019 ), the induction of TNF-α along with caspase-3 activation ( Yu et al, 2016a ; Yu et al, 2016b ), and the regulation of Hsp90 function ( Joshi et al, 2015 ).…”

Section: Discussionmentioning

confidence: 99%

NF-κB-dependent repression of Sox18 transcription factor requires the epigenetic regulators histone deacetylases 1 and 2 in acute lung injury

et al. 2022

In acute lung injury (ALI), the NF-κB-mediated downregulation of Sox18 gene expression leads to the disruption of the pulmonary endothelial barrier. Previous studies have suggested that the action of NF-κB as a transcriptional repressor also requires the action of class I histone deacetylases (HDACs). Thus, the purpose of this study was to investigate and further delineate the mechanism of Sox18 repression during lipopolysaccharide (LPS) induced ALI. Using selective inhibitors and specific siRNA-driven depletion of HDACs 1-3 in human lung microvascular endothelial cells (HLMVEC) we were able to demonstrate a critical role for HDACs 1 and 2 in the LPS-mediated repression of Sox18 gene expression and the loss of endothelial monolayer integrity. Moreover, our data demonstrate that HDAC1 associates with a transcription-repressive complex within the NF-κB-binding site of Sox18 promoter. Further, we were able to show that the selective inhibitor of HDAC1, tacedinaline, significantly reduced the endothelial permeability and injury associated with LPS challenge in the mouse lung. Taken together, our data demonstrate, for the first time, that transcription repressors HDACs 1 and 2 are involved in pathological mechanism of ALI and can be considered as therapeutic targets.

“…Because the endothelium is a major mediator of organ dysfunction in response to shock 3,[60][61][62][63][64] , we hypothesized that epigenetic alterations in the endothelium may lead to sustained organ damage (e.g., lungs, kidneys) via prolonged vascular dysfunction, including systemic vascular leak, thrombosis, and increased leukocyte adhesion 65 . However, the specific role of the epigenetic changes within the endothelium in failing organs is not well understood.…”

Section: Discussionmentioning

confidence: 99%

Shock drives a highly coordinated transcriptional and DNA methylation response in the endothelium

Ramos

Martino

Chuy

et al. 2022

Preprint

Interleukin 6 (IL-6) is a major mediator of the cytokine storm during shock. Its actions on the endothelium lead to pathological vascular leakage, leukocyte adhesion, and coagulopathy, which may result in multiorgan dysfunction and potentially death. Many shock survivors suffer long-term sequelae. We hypothesize that shock-induced endothelial epigenetic changes are involved in orchestrating these chronic pathological changes. Here, we interrogated the DNA methylation changes in the kidney endothelium after a challenge with lipopolysaccharides (LPS) in wilt type (WT) mice and in mice lacking endothelial SOCS3 (SOCS3iEKO). We identified 2596 differentially methylated positions (DMP) after an LPS challenge in WT mice. Notably, lack of endothelial SOCS3 leads to a highly divergent response, with 3564 DMP in response to LPS in SOCS3iEKO vs WT mice. Consistent with the hyper-inflammatory response in SOCS3iEKO mice, gene ontology analysis shows an enrichment in genes associated with an inflammatory response. To assess whether endothelial cells respond to IL-6 signaling directly by inducing DNA methylation changes, we challenged human umbilical vein endothelial cells in culture with IL-6 for 72 hours prior to methylomics assays. DNA methylation modifications were observed in sites associated with pathways regulating the regulation of cell adhesion, proliferation, and cytokine signaling. To determine the stability of these changes, we treated cells with IL-6 for 72h, followed by 96h in the absence of IL-6. We found that 40% of the DMP remained modified after the cytokine wash with a mean difference of less than 2% when comparing washed (72+96h) vs. non-washed cells (72h alone), suggesting that many changes in the endothelial methylome may remain in place for prolonged periods. In summary, persistent activation of endothelial IL-6 signaling leads to endothelial DNA methylation changes. Together, our data demonstrate that in response to pro-inflammatory stimuli, the endothelium elicits epigenetic changes that are at least in part due to IL-6/STAT3/SOCS3 signaling. These changes may regulate pathways associated with reduced long-term survival and chronic organ damage after shock.