Comparative analysis of calcified soft tissues revealed shared deregulated pathways

Area of Science:

• Biomedical Science
• Pathology
• Genomics

Background:

• Soft tissue calcification is a common age-related pathology, predominantly affecting vascular tissue.
• The precise mechanisms and tissue-specific nature of pathological calcification remain poorly understood.
• Previous research has analyzed calcified tissues individually, hindering cross-tissue pathway comparisons.

Purpose of the Study:

• To identify common and tissue-specific molecular changes associated with calcification.
• To analyze calcification in the aorta, tibial artery, coronary artery, and pituitary gland.
• To utilize RNA sequencing and histological data from the Genotype-Tissue Expression (GTEx) dataset.

Main Methods:

• Analysis of publicly available GTEx data, including RNA sequencing and histological information.
• Manual grading of Hematoxylin and eosin (H&E) stained arterial samples for calcification severity (0-4).
• Association of transcript levels with calcification grade, controlling for sex, age, and cause of death, followed by gene set enrichment analysis.

Main Results:

• Calcification was identified in 28% of aortas, 20% of tibial arteries, 43% of coronary arteries, and 8% of pituitary glands.
• An age-dependent increase in calcification incidence was observed in all vascular tissues but not the pituitary.
• While differentially expressed genes showed poor overlap across tissues, down-regulation of intracellular transport and up-regulation of inflammatory pathways were common findings in calcified arteries.

Conclusions:

• Pathological calcification, despite limited shared gene expression changes across tissues, presents potential therapeutic targets.
• Alleviating local inflammation in soft tissues may represent a universal strategy for managing pathological calcification.
• Upregulation of PD-1 and PD-L1 in calcified tissues suggests a role for localized inflammation in the disease process.