Increased soluble programed cell death-ligand 1 is associated with acute coronary syndrome

Costimulatory and Coinhibitory Immune Checkpoints in Atherosclerosis: Therapeutic Targets in Atherosclerosis?

The benefits of current state-of-the-art treatments to combat atherosclerotic cardiovascular disease (ASCVD) have stagnated. Treatments are mostly based on controlling cardiovascular risk factors, especially hyperlipidemia. Although the most recent advances with PCSK-9 inhibitors support the hyperlipidemia aspect of ASCVD, several lines of experimental evidence have outlined that atherosclerosis is also driven by inflammation. In the past years, phase 1, 2, and 3 clinical trials targeting inflammation to combat ASCVD have revealed that patients do tolerate such immune therapies, show decreases in inflammatory markers, and/or have reductions in cardiovascular endpoints. However, the search for the optimal anti-inflammatory or immune-modulating strategy and the stratification of patients who would benefit from such treatments and appropriate treatment regimens to combat ASCVD is only just beginning. In this review, we focus on immune checkpoint-based therapeutics (costimulation and coinhibition), many of which are already approved by the U.S. Food and Drug Administration for the treatment of cancer or autoimmune diseases, and discuss their use as a novel immunotherapeutic strategy to treat ASCVD.

Prognostic Significance of Soluble PD-L1 on Cardiovascular Outcomes in Patients with Coronary Artery Disease

AIMS

Programmed cell death-1 (PD-1) and its ligand (PD-L1) regulate T cells, leading to immunotolerance. We previously demonstrated that patients with coronary artery disease (CAD) had increased circulating levels of soluble PD-L1 (sPD-L1). However, the prognostic significance of sPD-L1 on cardiovascular outcomes is unknown. In the present study, we evaluated the association between sPD-L1 and cardiovascular events in patients with CAD.

METHODS

We prospectively measured sPD-L1 in patients with CAD admitted to Kumamoto University Hospital between December 2017 and January 2020 and observed their cardiovascular event rate. The primary outcome was a composite of death from non-cardiovascular causes, death from cardiovascular causes, non-fatal myocardial infarction, unstable angina pectoris, revascularization, hospitalization for heart failure, and ischemic stroke.

RESULTS

Finally, 627 patients were enrolled, and 35 patients were lost to follow-up. The median follow-up duration was 522 days. In total, 124 events were recorded. The Kaplan-Meier curve showed that the event rate was higher in the higher sPD-L1 group (median ≥ 136 pg/dL) than in the lower sPD-L1 group (25.0% vs. 16.9%; p=0.028, log-rank test). Univariate Cox proportional hazards analysis showed that high-sensitivity C-reactive protein, an estimated glomerular filtration rate of ＜60 mL/min/1.73m2, B-type natriuretic peptide, left ventricular ejection fraction, and sPD-L1 were significantly associated with cardiovascular events. Multivariable Cox proportional hazards analysis of factors that were significant in univariate analysis identified that sPD-L1 was significantly and independently associated with cardiovascular events (hazard ratio: 1.364, 95% confidence interval: 1.018-1.828, p=0.038).

CONCLUSIONS

Higher sPD-L1 levels were significantly associated with future cardiovascular events in patients with CAD.

Association of immunologic findings of atheromatous plaques with subsequent cardiovascular events in patients with peripheral artery disease

Patients with peripheral artery disease (PAD) have a higher risk of cardiovascular events. We examined the histology of atheromatous plaques in the femoral artery and investigated their association with subsequent cardiovascular events in patients with PAD. Patients who underwent femoral artery endarterectomy between March 2010 and January 2021 were included. We analyzed the expression of myeloperoxidase (MPO), citrullinated histone, and programmed cell death ligand 1 (PD-L1) in femoral artery plaques by immunohistochemistry. Data on the subsequent occurrence of major adverse cardiovascular events (MACEs), major adverse limb events (MALEs), and all-cause mortality were retrospectively collected. A total of 37 patients were included. The median age was 71 (range, 42-90) years, and 25 patients (67.6%) were male. During the median follow-up of 24 months, 10 patients experienced MACEs and 16 patients had MALEs. Patients with MACEs had a higher number of MPO-stained cells (p = 0.044) and lower PD-L1 staining intensity (p = 0.021) in atheromatous plaques compared with those of patients with a stable prognosis. When the patients were grouped according to the immunologic score based on the MPO-stained cell number and PD-L1 staining intensity, those with a higher score had a significantly higher cumulative risk of MACEs (p = 0.014). The immunologic profile of excised peripheral artery plaques may be associated with future cardiovascular events in patients with PAD.

Sex-dependent PD-L1/sPD-L1 trafficking in human endothelial cells in response to inflammatory cytokines and VEGF

Programmed cell death 1 ligand 1 (PD-L1) expressed in non-immune cells is involved in immune-mediated tissue damage in the context of inflammatory conditions and tumor immune escape. Emerging evidence suggests soluble (s)PD-L1 as a marker of inflammation. Based on well-established sex-specific differences in immunity, we tested the novel hypotheses that (i) endothelial cell PD-L1 is modulated by inflammatory cytokines and vascular endothelial growth factor (VEGF) in a sex-specific fashion, and (ii) the endothelium is a source of sPD-L1. After exposure of human umbilical vein endothelial cells (HUVECs) to lipopolysaccharide, interleukin (IL)1β or VEGF for 24 h, total PD-L1 levels were upregulated solely in cells from female donors, while being unchanged in those from male donors. Accordingly, exposure to synovial fluids from patients with inflammatory arthritis upregulated PD-L1 levels in HUVECs from female donors only. Membrane PD-L1 expression as measured by flow cytometry was unchanged in response to inflammatory stimuli. However, exposure to 2 ng/mL IL-1β or 50 ng/mL VEGF time-dependently increased sPD-L1 release by HUVECs from female donors. Treatment with the metalloproteinase (MMP) inhibitor GM6001 (10 μM) prevented IL-1β-induced sPD-L1 release and enhanced membrane PD-L1 levels. The anti-VEGF agents bevacizumab and sunitinib reduced both VEGF-induced PD-L1 accumulation and sPD-L1 secretion. Thus, inflammatory agents and VEGF rapidly increased endothelial PD-L1 levels in a sex-specific fashion. Furthermore, the vascular endothelium may be a sPD-L1 source, whose production is MMP-dependent and modulated by anti-VEGF agents. These findings may have implications for sex-specific immunity, vascular inflammation and response to anti-angiogenic therapy.

Soluble programmed cell death-ligand 1 as a new potential biomarker associated with acute coronary syndrome

Background

Soluble programmed cell death-ligand 1 (sPD-L1) has been well documented to activate immunosuppression and is considered an essential predictor of negative clinical outcomes for several malignances and inflammatory conditions. However, the clinical significance of sPD-L1 in the peripheral blood of patients with coronary artery disease (CAD) remains unclear. The aim of this study was to assess the correlations of sPD-L1 with clinical features in CAD patients and evaluate the diagnostic value of this protein in CAD.

Methods

A total of 111 CAD patients and 97 healthy volunteers who served as healthy controls (HCs) were consecutively enrolled. Plasma levels of sPD-L1 were measured with an amplified enzyme-linked immunosorbent assay (ELISA), and hs-CRP was measured with a C-reactive protein assay kit. The levels of other inflammatory cytokines were assessed in 88 CAD patients and 47 HCs by a multiparameter immunoluminescence flow cytometry detection technique. A logistic regression model was used to assess the independent association of sPD-L1 with acute coronary syndrome (ACS). The correlation between sPD-L1 and inflammatory cytokines in ACS was also assessed.

Results

Plasma levels of sPD-L1 were significantly increased in CAD patients, especially those with ACS. Univariate logistic regression analysis revealed that sPD-L1 (OR: 3.382, 95% CI: 2.249–5.084, p < 0.001), BMI, hypertension, diabetes, dyslipidemia, previous MI, and the levels of HDL-C, LDL-C and hs-CRP were significantly associated with ACS. sPD-L1 (OR: 3.336, 95% CI: 1.084–6.167, p = 0.001) was found to be independently and significantly associated with ACS in the subsequent multivariable logistic regression analysis. Additionally, elevated plasma sPD-L1 levels were associated with increased interleukin-6 and interleukin-8 levels in ACS patients. Receiver operating characteristic (ROC) analysis showed that the AUC of sPD-L1 for diagnosing ACS was 0.778, with a sensitivity of 73.9% and a specificity of 73.4%, which was comparable with that of the inflammatory biomarker hs-CRP.

Conclusion

The plasma sPD-L1 level reflects the severity of CAD, is associated with inflammatory responses and is a potential new biomarker for the diagnosis of ACS.