Histone H4 induces heparan sulfate degradation by activating heparanase in chlorine gas-induced acute respiratory distress syndrome

Abstract

Background Heparan sulfate (HS) degradation mediates pulmonary endothelial hyper-permeability and acute pulmonary edema during acute respiratory distress syndrome (ARDS). The aim of this study was to examine whether histone H4 induced HS degradation by activating heparanase (HPSE) in chlorine gas (Cl2)-induced ARDS. Methods Acute lung injury was induced by Cl2 exposure or histone H4 injection in C57BL/6 mice. Histone H4 in bronchoalveolar lavage fluid (BALF) and plasma was measured by ELISA. HS degradation was measured by immunostaining, ELISA, and flow cytometry. HPSE mRNA and protein were measured by real-time qPCR and western blot analysis, respectively, at preset timepoints. The HPSE inhibitor OGT2115 and specific siRNAs were used to study the role of HPSE during HS degradation caused by Cl2 exposure or histone H4 challenge. Blocking antibodies against TLR1, TLR2, TLR4, or TLR6 were used in vitro to investigate which signaling pathway was involved. The transcriptional regulation of HPSE was studied vis-à-vis NF-κB, which was assessed by nuclear translocation of NF-κB p65 and phosphorylation of I-κBα protein. Results Histone H4 in BALF and plasma increased evidently after Cl2 inhalation. Cl2 exposure or histone H4 challenge caused obvious acute lung injury in mice, and the pulmonary glycocalyx was degraded evidently as observed from endothelial HS staining and measurement of plasma HS fragments. Pretreatment with OGT2115, an HPSE inhibitor, relieved the acute lung injury and HS degradation caused by Cl2 exposure or histone H4 challenge. Targeted knockdown of HPSE by RNA interference (RNAi) significantly inhibited histone H4 induced HS degradation in HPMECs, as measured by immunofluorescence and flow cytometry. By inducing phosphorylation of I-κB α and nuclear translocation of NF-κB p65, histone H4 directly promoted mRNA transcription and protein expression of HPSE in a dose-dependent manner. Additionally, a blocking antibody against TLR4 markedly inhibited both activation of NF-κB and expression of HPSE induced by histone H4. Conclusions Histone H4 is a major pro-inflammatory mediator in Cl2-induced ARDS in mice, and induces HS degradation by activating HPSE via TLRs- and NF-κB-signaling pathways.

Targeting circulating high mobility group box-1 and histones by extracorporeal blood purification as an immunomodulation strategy against critical illnesses

“…Histones also exert potent cytotoxicity to vascular endothelial cells in a dose-dependent manner by binding to phospholipid–phosphodiester bonds in cell membranes and thus altering membrane permeability and initiating calcium ion influx [ 16 , 52 ]. Meanwhile, histones mediate the disruption of endothelial barrier function and vascular permeability by inducing oxidative stress and pyroptosis in endothelial cells [ 53 , 54 ], disrupting cell–cell adherens junctions [ 55 , 56 ], upregulating the expression of adhesion molecules ICAM1, VCAM1, and E-selectin [ 55 , 57 , 58 ], and impairing the endothelial glycocalyx [ 59 , 60 ]. Furthermore, histone-induced proinflammatory cytokine release and vascular endothelial injury will unfortunately disrupt the fine balance and cross talk between coagulant, anticoagulant and inflammatory pathways to trigger, amplify and propagate disseminated intravascular coagulation (DIC) [ 61 ].…”

M6229 Protects against Extracellular-Histone-Induced Liver Injury, Kidney Dysfunction, and Mortality in a Rat Model of Acute Hyperinflammation

“…Endothelial cells are covered at their luminal side with an extracellular layer, the glycocalyx, of which glycosaminoglycans constitute the major part [33]. glycocalyx forms a protective barrier to extracellular histones [34] and is likely disrupted as a consequence of histone challenge [35]. Hence, in the histone-challenged rats, the M6229 may provide protection by shielding endothelial cells and replenishing the disturbed glycocalyx barrier.…”

Heparanase in cancer progression: Structure, substrate recognition and therapeutic potential

“…For example, extracellular histone H4 induces HS degradation by activating HPSE in chlorine (Cl2)-induced acute respiratory distress syndrome (ARDS). Knockdown of HPSE by RNAi demonstrated that histone h4-induced HS degradation requires HPSE and is dependent on the enzymatic activity of HPSE (Zhang et al, 2022). In cells expressing high levels of HPSE, reduction of nuclear syndecan-1 results in increased histone acetyltransferase (HAT) activity, which stimulates protein transcription and transcriptional upregulation of multiple genes that drive aggressive tumor phenotypes (Purushothaman et al, 2011).…”