Calprotectin is a contributor to and potential therapeutic target for vascular calcification in chronic kidney disease

A Prospective Study of the Association Between Plasma Calprotectin Levels and New-Onset CKD in the General Population

Introduction

Systemic inflammation has been associated with chronic kidney disease (CKD). In this study, we aimed to investigate a potential association between the plasma biomarker of inflammation calprotectin and new-onset CKD in a population-based cohort study.

Methods

Individuals without CKD at baseline (n = 4662) who participated in the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) prospective population-based cohort study in the Netherlands were included. Baseline plasma calprotectin levels were assessed in samples that had been stored at -80 °C. Occurrence of new-onset CKD was defined as a composite outcome of an estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m2, urinary albumin excretion (UAE) >30 mg/24h, or both.

Results

Baseline median (interquartile range) plasma calprotectin levels were 0.49 (0.35-0.68) mg/l and baseline median eGFR was 95.9 (interquartile range: 85.0-105.7) ml/min per 1.73 m2. After median follow-up of 8.3 (7.8-8.9) years, 467 participants developed new-onset CKD. Baseline plasma calprotectin levels were significantly associated with an increased risk of new-onset CKD (hazard ratio [HR] per doubling 1.28 [95% confidence interval, CI: 1.14-1.44], P < 0.001), independent of potentially confounding factors (HR 1.14 [95% CI: 1.01-1.29], P = 0.034), except for baseline high-sensitive C-reactive protein (hs-CRP) (HR 1.05 [0.91-1.21], P = 0.494). In secondary analyses, the association between plasma calprotectin and occurrence of UAE >30 mg/24h remained significant (HR 1.17 [1.02-1.34], P = 0.027), but not significantly so for the incidence of eGFR <60 ml/min per 1.73 m2 as individual outcome (HR 1.15 [0.92-1.43], P = 0.218).

Conclusion

Higher plasma calprotectin levels are associated with an increased risk of developing CKD in the general population. This association is mitigated after adjustment for hs-CRP, and more pronounced with new-onset CKD defined by UAE.

Identification of S100A8/A9 involved in thromboangiitis obliterans development using tandem mass tags-labeled quantitative proteomics analysis

Thromboangiitis obliterans (TAO) is characterized by inflammation and obstruction of small-and medium-sized distal arteries, with limited pharmacotherapies and surgical interventions. The precise pathogenesis of TAO remains elusive. By utilizing the technology of tandem mass tags (TMT) for quantitative proteomics and leveraging bioinformatics tools, a comparative analysis of protein profiles was conducted between normal and TAO rats to identify key proteins driving TAO development. The results unveiled 1385 differentially expressed proteins (DEPs) in the TAO compared with the normal group-comprising 365 proteins with upregulated expression and 1020 proteins with downregulated expression. Function annotation through gene ontology indicated these DEPs mainly involved in cell adhesion, positive regulation of cell migration, and cytosol. The principal signaling pathways involved regulation of the actin cytoskeleton, vascular smooth contraction, and focal adhesion. The roles of these DEPs and associated signaling pathways serve as a fundamental framework for comprehending the mechanisms underpinning the onset and progression of TAO. Furthermore, we conducted a comprehensive evaluation of the effects of S100A8/A9 and its inhibitor, paquinimod, on smooth muscle cells (SMCs) and in TAO rats. We observed that paquinimod reduces SMCs proliferation and migration, promotes phenotype switching and alleviates vascular stenosis in TAO rats. In conclusion, our study revealed that the early activation of S100A8/A9 in the femoral artery is implicated in TAO development, targeting S100A8/A9 signaling may provide a novel approach for TAO prevention and treatment.

Common mouse models of chronic kidney disease are not associated with cachexia

The 5/6 nephrectomy and adenine-induced nephropathy mouse models have been extensively used to study Chronic Kidney Disease (CKD)-related cachexia. One common caveat of these CKD models is the cross-sectional nature of comparisons made versus controls. We here performed a comprehensive longitudinal assessment of body composition and energy metabolism in both models. The most striking finding is that weight loss is largely driven by reduced food intake which promotes rapid loss of lean and fat mass. However, in both models, mice catch up weight and lean mass a few days after the surgery or when they are switched back to standard chow diet. Muscle force and mass are fully recovered and no sign of cachexia is observed. Our data demonstrate that the time-course of kidney failure and weight loss are unrelated in these common CKD models. These data highlight the need to reconsider the relative contribution of direct and indirect mechanisms to muscle wasting observed in CKD.

A proteome-wide screen identifies the calcium binding proteins, S100A8/S100A9, as clinically relevant therapeutic targets in aortic dissection

Aortic dissection (AD) is a fatal cardiovascular disease with limited pharmacotherapies. To discover novel therapeutic targets for AD, the present study was conducted on ascending aorta samples from AD patients versus those from control subjects using proteomic analysis. Integrated proteomic data analysis identified S100 calcium-binding proteins A8 and A9 (S100A8/A9) as new therapeutic targets for AD. As assessed by ELISA, the circulating levels of S100A8/A9 were elevated in AD patients. In addition, we validated the upregulation of S100A8/A9 in a mouse model of AD. In vitro and in vivo studies substantiated that S100A8/A9, as danger-associated molecular pattern molecules, promotes the smooth muscle cells phenotypic switch by inhibiting serum response factor (SRF) activity but elevating NF-κB dependent inflammatory response. Depletion of S100A8/A9 attenuates the occurrence and development of AD. As a proof of concept, we tested the safety and efficacy of pharmacological inhibition of S100A8/A9 by ABR-25757 (paquinimod) in a mouse model of AD. We observed that ABR-25757 ameliorated the incidence of rupture and improved elastin morphology associated with AD. Further single-cell RNA sequencing disclosed that the phenotypic switch of vascular smooth muscle cells (VSMCs) and inflammatory response pathways were responsible for ABR-25757-mediated protection against AD. Thus, this study reveals the regulatory mechanism of S100A8/A9 in AD and offers a potential therapeutic avenue to treat AD by targeting S100A8/A9.

Calprotectin blockade inhibits long-term vascular pathology following peritoneal dialysis-associated bacterial infection

Bacterial infections and the concurrent inflammation have been associated with increased long-term cardiovascular (CV) risk. In patients receiving peritoneal dialysis (PD), bacterial peritonitis is a common occurrence, and each episode further increases late CV mortality risk. However, the underlying mechanism(s) remains to be elucidated before safe and efficient anti-inflammatory interventions can be developed. Damage-Associated Molecular Patterns (DAMPs) have been shown to contribute to the acute inflammatory response to infections, but a potential role for DAMPs in mediating long-term vascular inflammation and CV risk following infection resolution in PD, has not been investigated. We found that bacterial peritonitis in mice that resolved within 24h led to CV disease-promoting systemic and vascular immune-mediated inflammatory responses that were maintained up to 28 days. These included higher blood proportions of inflammatory leukocytes displaying increased adhesion molecule expression, higher plasma cytokines levels, and increased aortic inflammatory and atherosclerosis-associated gene expression. These effects were also observed in infected nephropathic mice and amplified in mice routinely exposed to PD fluids. A peritonitis episode resulted in elevated plasma levels of the DAMP Calprotectin, both in PD patients and mice, here the increase was maintained up to 28 days. In vitro, the ability of culture supernatants from infected cells to promote key inflammatory and atherosclerosis-associated cellular responses, such as monocyte chemotaxis, and foam cell formation, was Calprotectin-dependent. In vivo, Calprotectin blockade robustly inhibited the short and long-term peripheral and vascular consequences of peritonitis, thereby demonstrating that targeting of the DAMP Calprotectin is a promising therapeutic strategy to reduce the long-lasting vascular inflammatory aftermath of an infection, notably PD-associated peritonitis, ultimately lowering CV risk.

Leucine-Rich Alpha-2 Glycoprotein 1 Accumulates in Complicated Atherosclerosis and Promotes Calcification

Atherosclerosis is the primary cause of cardiovascular disease. The development of plaque complications, such as calcification and neo-angiogenesis, strongly impacts plaque stability and is a good predictor of mortality in patients with atherosclerosis. Despite well-known risk factors of plaque complications, such as diabetes mellitus and chronic kidney disease, the mechanisms involved are not fully understood. We and others have identified that the concentration of circulating leucine-rich α-2 glycoprotein 1 (LRG1) was increased in diabetic and chronic kidney disease patients. Using apolipoprotein E knockout mice (ApoE-/-) (fed with Western diet) that developed advanced atherosclerosis and using human carotid endarterectomy, we showed that LRG1 accumulated into an atherosclerotic plaque, preferentially in calcified areas. We then investigated the possible origin of LRG1 and its functions on vascular cells and found that LRG1 expression was specifically enhanced in endothelial cells via inflammatory mediators and not in vascular smooth muscle cells (VSMC). Moreover, we identified that LRG1 was able to induce calcification and SMAD1/5-signaling pathways in VSMC. In conclusion, our results identified for the first time that LRG1 is a direct contributor to vascular calcification and suggest a role of this molecule in the development of plaque complications in patients with atherosclerosis.