Mast cells participate in smooth muscle cell reprogramming and atherosclerotic plaque calcification

BACKGROUND

Calcification, a key feature of advanced human atherosclerosis, is positively associated with vascular disease burden and adverse events. We showed that macrocalcification can be a stabilizing factor for carotid plaque molecular biology, due to inverse association with immune processes. Mast cells (MCs) are important contributors to plaque instability, but their relationship with macrocalcification is unexplored. With a hypothesis that MC activation negatively associates with carotid plaque macrocalcification, we aimed to investigate the link between MCs and carotid plaque vulnerability, and study MC role in plaque calcification via smooth muscle cells (SMCs).

METHODS

Pre-operative computed tomography angiographies of patients (n = 40) undergoing surgery for carotid stenosis were used to characterize plaque morphology. Plaque microarrays (n = 40 and n = 126) were used for bioinformatic deconvolution of immune cell populations. Tissue microarrays (n = 103) were used to histologically validate the contribution of activated and resting MCs in plaques.

RESULTS

Activated MCs and their typical markers were negatively correlated with macrocalcification. The ratio of activated vs. resting MCs was increased in low-calcified plaques from symptomatic patients. There was no modulating effect of medication on MC ratios. In vitro experiments showed that SMC calcification attenuated MC activation, while both active and resting MCs stimulated SMC calcification and induced dedifferentiation towards a pro-inflammatory-, osteochondrocyte-like phenotype, without modulating their migro-proliferative function.

CONCLUSIONS

Integrative analyses from human plaques showed that MC activation is inversely associated with macrocalcification and positively with parameters of plaque vulnerability. Mechanistically, MCs induce SMC osteogenic reprograming, while matrix calcification in turn attenuates MC activation, offering new therapeutic avenues for exploration.

The association of renal impairment with different patterns of intracranial arterial calcification: Intimal and medial calcification

BACKGROUND AND AIMS

Increasing knowledge about calcification together with improved imaging techniques provided evidence that intracranial arterial calcification (IAC) can be divided into two distinct entities: intimal and medial calcification. The purpose of this study was to investigate the association between kidney function and the two patterns of IAC, which could clarify the underlying mechanisms of intimal or medial calcification and its clinical consequence.

METHODS

A total of 516 participants were enrolled in this study. Kidney function was assessed using the estimated glomerular filtration rate (eGFR) based on modified glomerular filtration rate estimating equation. The degree of IAC measured by IAC scores was evaluated on non-contrast head computed tomography (CT) images and IAC was classified as intimal or medial calcification. Associations of kidney function with IAC scores and patterns were assessed sing multivariate logistic regression analysis.

RESULTS

In 440 patients (85.27%) with IAC, 189 (42.95%) had predominant intimal calcifications and 251 (57.05%) had predominant medial calcifications. Multivariate analysis revealed that lower eGFR level (eGFR <60 ml/min/1.73 m²) was associated with higher IAC scores (odds ratio [OR] 2.01; 95% confidence interval [CI], 1.50-2.71; p < 0.001). Medial calcification was more frequent in the lower eGFR group (eGFR <60 ml/min/1.73 m²) compared to the other two groups with eGFR 60 to 89 and eGFR >90 ml/min/1.73 m² (78.72% vs. 53.65%, p < 0.001; 78.72% vs. 47.78%, p < 0.001). In multivariable analysis, impaired kidney function was associated with an increased odds of medial calcification presence in patients with eGFR <60 ml/min/1.73 m² (OR, 1.47; 95% CI, 1.05 to 2.06).

CONCLUSIONS

Our findings demonstrated that impaired renal function was independently associated with a higher degree of calcification in intracranial arteries, especially medial calcification, which reflects a distinction between two types of arterial calcification and raise the possibility for specific prevention of lesion formation.