Endothelial CXCR2 deficiency attenuates renal inflammation and glycocalyx shedding through NF-κB signaling in diabetic kidney disease

BACKGROUND

The incidence of diabetic kidney disease (DKD) continues to rapidly increase, with limited available treatment options. One of the hallmarks of DKD is persistent inflammation, but the underlying molecular mechanisms of early diabetic kidney injury remain poorly understood. C-X-C chemokine receptor 2 (CXCR2), plays an important role in the progression of inflammation-related vascular diseases and may bridge between glomerular endothelium and persistent inflammation in DKD.

METHODS

Multiple methods were employed to assess the expression levels of CXCR2 and its ligands, as well as renal inflammatory response and endothelial glycocalyx shedding in patients with DKD. The effects of CXCR2 on glycocalyx shedding, and persistent renal inflammation was examined in a type 2 diabetic mouse model with Cxcr2 knockout specifically in endothelial cells (DKD-Cxcr2 eCKO mice), as well as in glomerular endothelial cells (GECs), cultured in high glucose conditions.

RESULTS

CXCR2 was associated with early renal decline in DKD patients, and endothelial-specific knockout of CXCR2 significantly improved renal function in DKD mice, reduced inflammatory cell infiltration, and simultaneously decreased the expression of proinflammatory factors and chemokines in renal tissue. In DKD conditions, glycocalyx shedding was suppressed in endothelial Cxcr2 knockout mice compared to Cxcr2 L/L mice. Modulating CXCR2 expression also affected high glucose-induced inflammation and glycocalyx shedding in GECs. Mechanistically, CXCR2 deficiency inhibited the activation of NF-κB signaling, thereby regulating inflammation, restoring the endothelial glycocalyx, and alleviating DKD.

CONCLUSIONS

Taken together, under DKD conditions, activation of CXCR2 exacerbates inflammation through regulation of the NF-κB pathway, leading to endothelial glycocalyx shedding and deteriorating renal function. Endothelial CXCR2 deficiency has a protective role in inflammation and glycocalyx dysfunction, suggesting its potential as a promising therapeutic target for DKD treatment.

Influence of burn severity on endothelial glycocalyx shedding following thermal trauma: A prospective observational study

OBJECTIVE

Severe burns cause hypermetabolic and inflammatory responses are treated with significant volume resuscitation. This study aimed to evaluate correlations between glycocalyx metabolites and the burn size as well as certain clinical parameters such as administered fluid volumes.

STUDY DESIGN

Severely burned patients with a total body surface area (TBSA) burned smaller and larger than 20% were included. Clinical parameters including length of stay, mortality, fluid administration and Sequential Organ Failure Assessment (SOFA) score as well as syndecan and heparansulfate, as laboratory parameters for endothelial damage, were obtained.

RESULTS

A total of 39 patients (32 males, 7 females) with a mean age at burn of 45 ± 21 years were included. Syndecan levels decreased and heparansulfate levels increased over time. In both heparansulfate and syndecan, there was no significant difference between burns smaller and larger than 20% TBSA at any time point. Syndecan levels at 24 h after burn correlated significantly with IL-10 levels at admission (R = 0.58 and p < 0.05). There were significant linear correlations of %TBSA and cumulative administration of fluids after 24 h on syndecan levels after 48 h. Correlations between clinical parameters and syndecan or heparansulfate levels over time were not found.

CONCLUSIONS

This study shows that even though there are moderate correlations with burn size and administered fluid volume, levels of syndecan and heparansulfate are not predictive for clinical outcomes of burned patients in our cohort. Further studies with higher numbers evaluating the effect of large burns on glycocalyx shedding over a longer period of time are needed. Showing significant glycocalyx shedding in large burn including potentially correlations with clinical outcomes may yield new therapeutic targets.

RECCAS - REmoval of Cytokines during CArdiac Surgery: study protocol for a randomised controlled trial

Background

On-pump cardiac surgery triggers a significant postoperative systemic inflammatory response, sometimes resulting in multiple-organ dysfunction associated with poor clinical outcome. Extracorporeal cytokine elimination with a novel haemoadsorption (HA) device (CytoSorb®) promises to attenuate inflammatory response. This study primarily assesses the efficacy of intraoperative HA during cardiopulmonary bypass (CPB) to reduce the proinflammatory cytokine burden during and after on-pump cardiac surgery, and secondarily, we aim to evaluate effects on postoperative organ dysfunction and outcomes in patients at high risk.

Methods/design

This will be a single-centre randomised, two-arm, patient-blinded trial of intraoperative HA in patients undergoing on-pump cardiac surgery. Subjects will be allocated to receive either CPB with intraoperative HA or standard CPB without HA. The primary outcome is the difference in mean interleukin 6 (IL-6) serum levels between the two study groups on admission to the intensive care unit. A total number of 40 subjects was calculated as necessary to detect a clinically relevant 30 % reduction in postoperative IL-6 levels. Secondary objectives evaluate effects of HA on markers of inflammation up to 48 hours postoperatively, damage to the endothelial glycocalyx and effects on clinical scores and parameters of postoperative organ dysfunction and outcomes.

Discussion

In this pilot trial we try to assess whether intraoperative HA with CytoSorb® can relevantly reduce postoperative IL-6 levels in patients undergoing on-pump cardiac surgery. Differences in secondary outcome variables between the study groups may give rise to further studies and may lead to a better understanding of the mechanisms of haemoadsorption.

Trial registration

German Clinical Trials Register number DRKS00007928 (Date of registration 3 Aug 2015)