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

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.

Correction to: The elevated levels of urinary angiotensinogen are correlated with the severity of idiopathic membranous nephropathy.

Following publication of the original article [1], it was reported that, due to a typesetting mistake, the three tables and two figures for this article were included as an Additional file instead of in the body of the article. The original publication of this article has been updated to correct this.

Extracellular Histones Promote Pulmonary Fibrosis in Patients With Coal Workers' Pneumoconiosis.

OBJECTIVE: This investigation assessed the profibrotic role that extracellular histones play in the pathogenesis of coal workers' pneumoconiosis (CWP). METHODS: The correlation of extracellular histones with small opacity profusion (SOP) and transforming growth factor-ß (TGF-ß) was analyzed. The stimulating effect of extracellular histones on pulmonary fibroblast was assessed in vitro. RESULTS: The levels of extracellular histones in plasma were positively correlated with SOP and TGF-ß in the coal miners investigated. Plasma collected from patients with CWP caused apparent lung fibroblast proliferation, while anti-H4 antibody antagonized the stimulating effect of the patient plasma by blocking histone H4. In vitro experiments showed that extracellular histones directly stimulated fibroblast proliferation. CONCLUSION: Consistent with our hypothesis, the concentrations of extracellular histones were indices of the severity of pulmonary fibrosis in simple CWP, and extracellular histones-targeted intervention could inhibit the proliferation of lung fibroblast.

The elevated levels of urinary angiotensinogen are correlated with the severity of idiopathic membranous nephropathy.

BACKGROUND: Immunosuppressive treatment will predispose an idiopathic membranous nephropathy (iMN) patient to opportunistic infections. Disease severity is one of the main concerns for making the treatment decision. Urinary angiotensinogen (UAGT) level has been shown highly correlated with intrarenal renin-angiotensin system (RAS) activity and severity of chronic kidney diseases (CKD). We aimed to test the relationship between the UAGT level and the severity of iMN. METHODS: This cross-sectional study included a total of 48 biopsy-proven iMN patients, 46 minimal change disease (MCD) patients, and 44 healthy volunteers. The clinical and laboratory data and urine samples were collected from all subjects before the use of RAS inhibitors. We determined the UAGT levels with a method of enzyme-linked immunosorbent assay. RESULTS: The UAGT levels were not different between the iMN (277.05 ± 61.25, µg/g.Cr) and MCD patients (244.19 ± 40.24, µg/g.Cr), but both of them were significantly higher than those of healthy controls (6.85 ± 1.10, µg/g.Cr). UAGT levels were correlated negatively with serum albumin (r = - 0.393, p = 0.006) and estimated glomerular filtration rate (eGFR) (r = - 0.352, p = 0.014) and positively with 24-h proteinuria (r = 0.614, p < 0.001) in iMN patients but not in MCD patients. Multivariate linear regression analysis revealed that only proteinuria independently determinate the levels of UAGT (ß = 0.649, p < 0.001) in iMN patients. CONCLUSIONS: UAGT levels were correlated negatively with serum albumin and glomerular filtration rate and positively with proteinuria in iMN patients at the onset. This suggests that elevated levels of UAGT are associated with the severity of iMN. The UAGT level may be used as a cofactor for deciding immunosuppressive therapy in iMN patient.

Up-regulation of intrarenal renin-agiotensin system contributes to renal damage in high-salt induced hypertension rats.

BACKGROUND/AIMS: To investigate the change of intrarenal renin-agiotensin system (RAS) and its role in high-salt induced hypertension. METHODS: Wistar rats were divided into normal-salt (NS), high-salt diet (HS) and high-salt diet with Losartan group (HS+L), for 6 weeks. Systolic blood pressure (SBP) was monitored. Blood and urine samples were collected every 2 weeks. Angiotensinogen (AGT) was measured by ELISA. AGT mRNA and protein were measured by real-time PCR and immunohistochemistry. Renin activity and angiotensin II (Ang II) were measured by radioimmunoassay. RESULTS: HS versus NS group, SBP increased from 2(nd) week (P<0.05), urinary protein increased at 6(th) week (P<0.05). Although plasma renin, AGT and Ang II had no significant changes (P>0.05), renal cortex renin, AGT, and Ang II increased significantly in HS (P<0.05). In HS+L, Losartan failed to reduce SBP (P>0.05) but abolished the increase of proteinuria (P<0.01), renal cortex renin, AGT, Ang II and urinary AGT reduced (P<0.05) while plasma renin, AGT and Ang II enhanced (P<0.05) when compared with HS. Urinary AGT was positively correlated with renal AGT (r=0.592, P <0.01) and Ang II (r=0.726, P <0.01). CONCLUSION: Inappropriate response of the renal RAS to a high salt diet may contribute to hypertension and renal damage, and urinary AGT could reflect intrarenal RAS activity.