Age-associated chemokine receptor expression profiles in human peripheral blood monocyte subsets predict cardiovascular disease risk.

Aging was associated with remodeling of monocyte populations, including a reduction in anti-inflammatory classical monocytes and an expansion of immature monocytes.

• High-dimensional single-cell antibody sequencing (Ab-Seq) was performed on peripheral blood mononuclear cells from 61 participants aged 42-78 years enrolled in the Coronary Assessment of Virginia (CAVA) cohort.
• Anti-inflammatory classical monocytes were reduced with age.
• Immature monocytes expanded with age.
• These changes were identified across participants spanning a 36-year age range.

Among younger individuals with severe CAD, the intermediate monocyte subcluster iMo_HLA-DRintCCR2low was increased.

• This finding was identified using Ab-Seq profiling in the CAVA cohort.
• The iMo_HLA-DRintCCR2low subcluster was specifically elevated in younger individuals with severe coronary artery disease.
• This association was age-dependent, distinguishing younger from older participants with CAD.

Among younger individuals with severe CAD, the anti-inflammatory classical monocyte subcluster cMo_CD33hiCD163hiCXCR4+ was reduced.

• The cMo_CD33hiCD163hiCXCR4+ subcluster is characterized as anti-inflammatory.
• Reduction of this subcluster was observed specifically in younger individuals with severe CAD.
• This finding was identified through high-dimensional Ab-Seq profiling.

In older individuals with progressive CAD, further reductions in CCR6+ and CXCR3+ classical monocytes were observed.

• Both CCR6-expressing and CXCR3-expressing classical monocytes declined with advancing CAD in older participants.
• Flow cytometry validation confirmed decreased CCR6-expressing classical monocytes in older individuals with high CAD burden.
• These reductions were identified as age-dependent features of CAD progression.

Independent of age, CXCR3-expressing intermediate monocytes were significantly increased in individuals with severe CAD.

• The association between CXCR3+ intermediate monocytes and severe CAD was observed regardless of participant age.
• This finding was identified through Ab-Seq profiling and validated by flow cytometry.
• CXCR3+ intermediate monocytes represent a disease-associated monocyte feature not confounded by aging.

Transcriptomic analysis revealed that CXCR3+ intermediate monocytes demonstrated increased expression of C1Q genes compared with CXCR3low cells.

• C1Q gene expression was elevated in CXCR3+ intermediate monocytes relative to CXCR3low intermediate monocytes.
• C1Q genes are associated with complement pathway activity and inflammation.
• This transcriptomic finding provides mechanistic insight into the potential pro-inflammatory role of CXCR3+ intermediate monocytes in CAD.

In older individuals, CCR6 expression on intermediate monocytes positively associated with HDL cholesterol and increased with CAD severity.

• Chemokine receptor expression correlated with lipid parameters specifically in older individuals.
• CCR6 expression on intermediate monocytes showed a positive correlation with HDL cholesterol levels.
• CCR6 expression on intermediate monocytes increased with CAD severity in older participants.
• This represents an age-dependent relationship between monocyte chemokine receptor expression and lipid metabolism.

CXCR3 expression on classical monocytes declined with advancing CAD in older individuals.

• This decline was observed in older participants and represents an age-associated pattern.
• CXCR3 expression on classical monocytes decreased progressively with greater CAD severity.
• This finding contrasts with the age-independent increase of CXCR3+ intermediate monocytes in severe CAD.

Flow cytometry validation confirmed decreased CCR6-expressing classical monocytes in older individuals with high CAD burden.

• Independent flow cytometry experiments validated the Ab-Seq finding regarding CCR6+ classical monocytes.
• The decrease in CCR6-expressing classical monocytes was specific to older individuals with high CAD burden.
• This validation supports the robustness of the Ab-Seq-derived findings.