Integrated Multiomics Reveals Key Drivers and Immune Cell Phenotypes of Infrapopliteal Atherosclerosis and Calcification.

BACKGROUND

Infrapopliteal atherosclerosis and calcification are major causes of chronic limb ischemia. This study aimed to identify causative genes and immune cell phenotypes driving this pathology to develop targeted therapeutic strategies.

METHODS

Bulk RNA transcriptomics (bulk RNA-seq) and summary data-based Mendelian randomization (SMR) were integrated to identify key genes associated with infrapopliteal atherosclerosis. Subsequently, single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST) were employed to characterize the target gene's specific expression and spatial distribution in calcified vessels. Mendelian randomization (MR) combined with scRNA-seq was utilized to identify immune cell phenotypes causally associated with the disease. Molecular mechanisms were investigated via in silico knockout and protein-protein interaction analyses, followed by therapeutic drug prediction via enrichment analysis.

RESULTS

Integrated analysis identified HLA-B as the robust causative gene for infrapopliteal atherosclerosis (PSMR = 0.002, β = 0.274). scRNA-seq analysis showed that HLA-B was significantly upregulated in B cells in calcified vascular tissue. Additionally, MR analysis combined with scRNA-seq identified IgD- CD27- B cell %B cell and IgD+ CD24- B cell %lymphocyte as immune cell phenotypes causally associated with the disease. In silico knockout combined with protein docking revealed a strong interaction between HLA-B and MRPL18, and ST analysis demonstrated higher overall expression of HLA-B in calcified vessels, particularly in plaques and calcified regions. Drug enrichment analysis suggested that allopurinol, abacavir, and lamotrigine could be potential therapeutics targeting HLA-B.

CONCLUSION

Integrated multiomics revealed HLA-B upregulation drives infrapopliteal atherosclerosis and calcification, identifying IgD- CD27- B cell %B cell and IgD+ CD24- B cell %lymphocyte as causal immune phenotypes.