Publications

The 2018 and 2019 American Heart Association and American College of Cardiology (AHA/ACC) guidelines for primary prevention of atherosclerotic cardiovascular disease (ASCVD) recommend consideration of so-called "risk-enhancing factors" in borderline to intermediate risk individuals. These include high-risk race/ethnicity (e.g. South Asian origin), chronic kidney disease, a family history of premature ASCVD, the metabolic syndrome, chronic inflammatory disorders (e.g. rheumatoid arthritis [RA], psoriasis, or chronic human immunodeficiency virus [HIV]), and conditions specific to women, among others. Studies suggest, however, that risk may be highly heterogeneous within these subgroups. The AHA/ACC guidelines also recommend consideration of coronary artery calcium (CAC) scoring for further risk assessment in borderline to intermediate risk individuals in whom management is uncertain. Although the combination of risk enhancing factors and CAC burden (together with Pooled Cohort estimates) may lead to more accurate ASCVD risk assessment, few publications have closely examined the interplay between risk enhancing factors and CAC scoring for personalized risk estimation. Our aim is to review the relevant literature in this area. Although further research is clearly needed, CAC assessment seems a highly valuable option to inform individualized ASCVD risk management in these important, often highly heterogeneous patient subgroups.

AIMS

TGF-β signaling is required for chronic hypoxia-induced pulmonary hypertension (PH). The activation of TGF-β by thrombospondin-1 (TSP-1) contributes to the pathogenesis of hypoxia-induced PH. However, neither the cellular source of pathologic TSP-1 nor the downstream signaling pathway that link activated TGF-β to PH have been determined. In this study, we hypothesized that circulating monocytes, which are recruited to become interstitial macrophages, are the major source of TSP-1 in hypoxia-exposed mice, and TSP-1 activates TGF-β with increased Rho kinase signaling, causing vasoconstriction.

METHODS AND RESULTS

Flow cytometry revealed that a specific subset of interstitial macrophages is the major source of pathologic TSP-1 in hypoxia. Intravenous depletion and parabiosis experiments demonstrated that these cells are circulating prior to recruitment into the interstitium. Rho kinase mediated vasoconstriction was a major downstream target of active TGF-β. Thbs1 deficient bone marrow protected against hypoxic-PH by blocking TGF-β activation and Rho kinase-mediated vasoconstriction.

CONCLUSIONS

In hypoxia-challenged mice, bone marrow derived and circulating monocytes are recruited to become interstitial macrophages which express TSP-1, resulting in TGF-β activation and Rho kinase-mediated vasoconstriction.

TRANSLATIONAL PERSPECTIVES

Inflammation contributes to the pathogenesis of many forms of pulmonary hypertension, but blocking inflammation has not been a successful therapeutic strategy to date. Here we found that mice with experimental hypoxia-induced pulmonary hypertension have recruitment of circulating, classical monocytes into the lungs, and that these cells express the protein thrombospondin-1 that causes activation of TGF-β and results in Rho-kinase mediated vasoconstriction. These data suggest that more precise targeting of inflammation, such as blocking specific cells like monocytes or cytokines like TGF-β, would be a more effective future therapeutic approach for pulmonary hypertension etiologies where these pathways underlie disease pathogenesis.