Chronic Inflammation via suPAR: Liên kết thiếu hụt giữa Bệnh tiểu đường và Tử vong Tim mạch

Highlights

• Soluble urokinase plasminogen activator receptor (suPAR) levels are significantly higher in patients with Type 2 Diabetes (T2D) compared to those without.
• In patients with Coronary Artery Disease (CAD), suPAR mediates more than 50% of the association between T2D and adverse outcomes, including cardiovascular death and myocardial infarction.
• Unlike high-sensitivity C-reactive protein (hs-CRP), suPAR acts as a critical independent mediator of the diabetic cardiovascular risk profile.
• These findings suggest that chronic immune activation, rather than just acute-phase inflammation, drives the poor prognosis seen in diabetic patients with heart disease.

Introduction: The Intersection of Metabolic and Vascular Disease

The pathophysiological nexus between Type 2 Diabetes (T2D) and Coronary Artery Disease (CAD) has long been recognized as a primary driver of global mortality. While hyperglycemia, dyslipidemia, and hypertension are established contributors to vascular damage, they do not fully account for the disproportionately high risk of cardiovascular death in the diabetic population. Clinical research is increasingly shifting toward the role of chronic, low-grade inflammation—often termed ‘inflammaging’—and immune dysregulation as the hidden architects of this risk.

Traditionally, high-sensitivity C-reactive protein (hs-CRP) has served as the clinical standard for measuring systemic inflammation. However, hs-CRP is a non-specific acute-phase reactant that reflects downstream inflammatory processes. Recently, attention has turned to the soluble urokinase plasminogen activator receptor (suPAR). As a marker of chronic immune activation, suPAR is primarily produced by bone marrow-derived cells and reflects the activity of the innate immune system. The study by Sakr et al., published in Diabetes Care, provides a critical investigation into whether suPAR acts as the primary mediator through which diabetes exerts its deleterious effects on the cardiovascular system.

Study Design and Methodology

The researchers utilized data from the Emory Cardiovascular Biobank, a large-scale prospective study of patients undergoing cardiac catheterization. The analysis included 4,324 participants with a mean age of 64 years. Approximately 31.8% of the cohort had a diagnosis of T2D. The primary objective was to determine the extent to which suPAR and hs-CRP mediated the risk of adverse outcomes.

The study endpoints were robust and clinically relevant: 1) cardiovascular death, 2) a composite of incident myocardial infarction (MI) and cardiovascular death, and 3) all-cause mortality. Patients were followed for a median of 6.9 years, providing substantial longitudinal data. To ensure the validity of the results, the team employed Fine and Gray competing risk models and Cox proportional hazards models, adjusting for a wide array of confounders, including age, sex, BMI, smoking status, renal function (eGFR), and medication use (statins, ACE inhibitors, and glucose-lowering therapies). Regression-based causal mediation analysis was the cornerstone of the statistical approach, allowing the authors to quantify the proportion of the T2D effect explained by these inflammatory biomarkers.

Detailed Results: suPAR as a Key Mediator

The initial findings confirmed that participants with T2D had significantly higher baseline suPAR levels (median 3,260 pg/mL) compared to those without T2D (2,792 pg/mL). This elevation persisted regardless of other clinical variables, suggesting that diabetes itself is a potent stimulus for chronic immune activation.

The Primacy of suPAR over hs-CRP

The study revealed that T2D was associated with a 38% increased risk of cardiovascular death (Hazard Ratio [HR] 1.38; 95% CI 1.16–1.63). However, the most striking discovery occurred during the mediation analysis. When the models were adjusted for suPAR levels, the hazard ratio for T2D was dramatically attenuated to 1.18 (95% CI 0.99–1.40), losing its statistical significance (P = 0.1). In contrast, adjustment for hs-CRP had negligible impact on the risk associated with T2D.

Quantitatively, suPAR was found to mediate more than 50% of the effect of T2D on cardiovascular death and the composite endpoint of MI and death. This suggests that a substantial portion of the cardiovascular risk traditionally attributed to diabetes is actually driven by the biological pathways represented by suPAR. Similar patterns were observed for all-cause mortality, reinforcing suPAR’s role as a pervasive marker of systemic vulnerability in diabetic patients.

Expert Commentary: Mechanistic Insights and Clinical Implications

The findings by Sakr et al. have profound implications for how clinicians view the ‘diabetic heart.’ It appears that suPAR is not merely a marker of disease but a reflection of a specific type of immune dysregulation that is highly prevalent in diabetes. Unlike hs-CRP, which fluctuates with acute infections or minor injuries, suPAR levels are remarkably stable over time, making it a superior indicator of a patient’s chronic inflammatory ‘set point.’

Biological Plausibility

Why is suPAR so closely linked to diabetic outcomes? Mechanistically, suPAR is the cleaved form of uPAR, which is expressed on various immune cells, including monocytes and neutrophils, as well as endothelial cells. High levels of suPAR have been linked to several pathological processes:

• Endothelial Dysfunction: suPAR promotes the recruitment of inflammatory cells to the vascular wall, accelerating atherosclerosis.
• Renal Injury: suPAR is a known driver of proteinuric kidney disease; given the close link between renal health and cardiovascular outcomes (the cardiorenal syndrome), this may be a primary pathway of mediation.
• Bone Marrow Activity: suPAR levels reflect increased myelopoiesis, which provides a continuous supply of pro-inflammatory monocytes that destabilize atherosclerotic plaques.

Study Limitations and Future Directions

While the study is robust, certain limitations must be acknowledged. The cohort consisted of patients already undergoing cardiac evaluation, which may limit generalizability to the broader, asymptomatic diabetic population. Furthermore, while the mediation analysis suggests a causal link, observational data cannot definitively prove causation. Future research must determine whether specifically lowering suPAR levels—perhaps through novel anti-inflammatory agents or more aggressive metabolic control—can directly reduce cardiovascular events.

Conclusion: Moving Toward Inflammation-Targeted Therapies

The identification of suPAR as a major mediator of diabetic cardiovascular risk represents a significant step forward in personalized medicine. It suggests that managing T2D in the context of CAD requires more than just glucose and lipid control; it requires a targeted approach to quenching chronic immune activation. For clinicians, suPAR may soon serve as a vital tool for risk stratification, identifying those diabetic patients who are at the highest risk despite ‘well-controlled’ traditional risk factors. As we move into an era of anti-inflammatory cardiovascular therapies, suPAR stands out as a promising target for intervention and a sentinel for patient prognosis.

References

1. Sakr SM, Desai S, Medina-Inojosa J, et al. Soluble Urokinase Plasminogen Activator Receptor (suPAR) Mediates the Impact of Diabetes on Adverse Outcomes in Coronary Artery Disease. Diabetes Care. 2026;49(3):450-459. PMID: 41533335.
2. Hayek SS, Sever S, Ko YA, et al. Soluble Urokinase Plasminogen Activator Receptor and Cognitive Function, Brain Volume, and White Matter Hyperintensities. Circulation. 2020;142(3):218-228.
3. Eapen DJ, Manocha P, Lakkad N, et al. Soluble Urokinase Plasminogen Activator Receptor Level Is an Independent Predictor of the Presence and Severity of Coronary Artery Disease and of Future Adverse Events. J Am Heart Assoc. 2014;3(5):e001118.