Evaluation of Endothelial Dysfunction and Inflammatory Vasculopathy After SARS-CoV-2 Infection-A Cross-Sectional Study

Background: Rising data suggest that COVID-19 affects vascular endothelium while the underlying mechanisms promoting COVID-19-associated endothelial dysfunction and inflammatory vasculopathy are largely unknown. The aim was to evaluate the contribution of COVID-19 to persisting vascular injury and to identify parameters linked to COVID-19-associated endothelial dysfunction and inflammatory vasculopathy. Methods: In a cross-sectional design, flow-mediated dilation (FMD), nitroglycerine-related dilation (NMD), pulse-wave velocity (PWV), augmentation index, intima-media thickness (IMT), compounds of the arginine and kynurenine metabolism, homocysteine, von Willebrand factor (vWF), endothelial microparticles (EMP), antiendothelial cell antibodies, inflammatory, and immunological parameters, as well as nailfold capillary morphology were measured in post-COVID-19 patients, patients with atherosclerotic cardiovascular diseases (ASCVD) and healthy controls without prior or recent SARS-CoV-2 infection. Results: Post-COVID-19 patients had higher values of PWV, augmentation index, IMT, asymmetric and symmetric dimethylarginine, vWF, homocysteine, CD31+/CD42b- EMP, C-reactive protein, erythrocyte sedimentation rate, interleukin-6, and β-2-glycoprotein antibodies as well as lower levels of homoarginine and tryptophan compared to healthy controls (all with p < 0.05). A higher total number of pathologically altered inflammatory conditions and higher rates of capillary ramifications, loss, caliber variability, elongations and bushy capillaries with an overall higher microangiopathy evolution score were also observed in post-COVID-19 patients (all with p < 0.05). Most parameters of endothelial dysfunction and inflammation were comparably altered in post-COVID-19 patients and patients with ASCVD, including FMD and NMD. Conclusion: COVID-19 may affect arterial stiffness, capillary morphology, EMP and selected parameters of arginine, kynurenine and homocysteine metabolism as well as of inflammation contributing to COVID-19-associated endothelial dysfunction and inflammatory vasculopathy.

Association between panel reactive antibody and antiendothelial cell antibody positivity in kidney transplant patients

OBJECTIVES

Endothelium is the major tissue for hyperacute and acute rejection. Binding of antibody to endothelium activates several immunologic mechanisms. Antiendothelial cell antibodies are a group of nonhuman leukocyte antigen antibodies that may play a role in the induction of an immunologic reaction that triggers inflammation. The aim of this study was to investigate whether there was an association between antiendothelial cell antibody positivity and panel reactive antibody positivity in renal transplant patients.

MATERIALS AND METHODS

In this study, we investigated the association between antiendothelial cell antibodies and panel reactive antibody Class I class II crossmatch positivity in patients, and compared these results with results from 100 healthy volunteers. All serum samples were analyzed by bead-based technology for calculated panel reactive antibody positivity; in addition, slides were used, each containing human umbilical vein endothelial cells and capillary-rich tissue for antiendothelial cell antibody positivity.

RESULTS

Antiendothelial cell antibodies was positive in 48 of 89 patients (panel reactive antibody Class I class II negative), 22 of 35 patients (class I-positive), 25 of 39 patients (class II-positive), 26 of 40 (class I class II positive), and 37 of 57 serologic and flow cytometry crossmatch-positive patients (P ≤ .016), and ultimately, in 122 of 205 patients and 25 of 100 volunteers (P ≤ .001). Antiendothelial cell antibody positivity was more frequent in panel reactive antibody-positive than negative patients and the control group.

CONCLUSIONS

Binding of antiendothelial cell antibodies to endothelial cells may activate complement by the classical pathway and cause upregulation of adhesion molecules. This study questioned the antigenic specificity of antiendothelial cell antibodies. Our study results showed that antiendothelial cell antibodies may play an important role for graft destruction, independent of panel reactive antibody and crossmatch positivity.

Circulating anti-β2-glycoprotein I antibodies of peripheral arterial disease patients trigger a genomic overexpression of Toll-like receptor 4 in endothelial cells

OBJECTIVE

Circulating anti-β2-glycoprotein I (ABGPI) antibodies are associated with peripheral arterial disease (PAD) and induce the expression of leukocyte adhesion molecules and proinflammatory cytokines by endothelial cells. Our aim is to study a transcriptional activation pathway of the innate immune system through the cellular signalling cascade triggered by receptors Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) of endothelial cells after the exposure of these cells to seropositive ABGPI human serum obtained from PAD patients.

METHODS

We obtained serum samples from PAD patients and controls without PAD. ABGPI serum titer was detected using indirect immunofluorescence. Our sample was stratified into three groups: group I (PAD and ABGPI titer ≥1:100; n = 15), group II (PAD and ABGPI titer <1:100; n = 15), and control participants (no PAD; n = 15). All serum samples were incubated with human aortic endothelial cell (HAEC) culture. Genomic expression of TLR2 and TLR4 receptors and their shared intracellular signalling molecules, myeloid differentiation primary response gene 88 (MyD88), and interleukin (IL)-1 receptor-associated kinase (1IRAK1), were measured after the exposure of HAECs to each serum.

RESULTS

HAEC genomic expression of TLR4 was higher after the exposure to group I serum than after the exposure to group II serum (log10×10-relative quantification [RQ]: 1.80 ± 0.42 vs 1.37 ± 0.39; P = .01) or control serum (log10×10-RQ: 1.80 ± 0.42 vs 1.09 ± 0.26; P < .01). TLR4 expression was higher in group II than in the control group (log10×10-RQ: 1.37 ± 0.39 vs 1.09 ± 0.26; P = .04). TLR4 expression correlated with MyD88 (r = 0.54; P < .01) and IRAK1 (r = 0.55; P < .01) expression. We recorded a positive correlation between MyD88 and IRAK1 genomic expression (r = 0.58; P < .01).

CONCLUSIONS

Our results suggest that serum from PAD patients with elevated ABGPI antibodies induces a genomic overexpression of TLR4 and its cellular signalling molecules in endothelial cells.

Circulating anti-beta2-glycoprotein I antibodies are associated with endothelial dysfunction, inflammation, and high nitrite plasma levels in patients with intermittent claudication

Our aim is to investigate a possible association of circulating anti-beta2-glycoprotein I antibodies (ABGPI) with the endothelial dysfunction, nitric oxide bioactivity dysregulation, and the inflammatory status that surrounds peripheral arterial disease. We carried out an observational translational study, including 50 male patients with intermittent claudication and a healthy control group of 10 male subjects, age and sex matched with the cases. Flow-mediated arterial dilatation (FMAD) was assessed as a surrogate of endothelial dysfunction, and C-reactive protein (hsCRP) was determined as a marker of inflammation. Nitrite plasma levels were measured by colorimetric analysis. Circulating ABGPI titer was detected with indirect immunofluorescence. Titers <1 : 10 represented the reference range and the lower detection limit of the test. Circulating ABGPI titer ≥1 : 10 was detected in 21 (42%) patients and in none of the control subjects (P < 0.01). Patients with ABGPI titer ≥1 : 10 had a lower FMAD (P = 0.01). The CRP levels were higher in patients with ABGPI titer ≥1 : 10 (P = 0.04). The nitrite plasma levels were higher in patients with ABGPI titer ≥1 : 10 (P < 0.01). These data suggest that these circulating ABGPI may collaborate in the development of atherosclerosis; however, further prospective studies are required to establish a causal relationship.