Serum Soluble Semaphorin 4D is Associated with Left Atrial Diameter in Patients with Atrial Fibrillation

The value of serum Sema4D level in reflecting the inflammatory state of acute ST-segment elevation myocardial infarction

Background

This study sought to investigate the expression of soluble semaphorin 4D (sSema4D) in acute ST-segment elevation myocardial infarction (STEMI) and to explore its value in evaluating the inflammatory status of acute myocardial infarction (AMI).

Methods

From October 2020 to June 2021, 100 patients with STEMI diagnosed at the Department of Cardiology of our hospital were selected as the STEMI group, 83 patients with unstable angina (UA) were selected as the UA group, and 78 patients with negative coronary angiography (CAG) were selected as the control group. The baseline data of the 3 groups of patients were recorded, the sSema4D levels were determined, the expression of sSema4D levels in AMI was analyzed, and the value of sSema4D levels in reflecting inflammatory state of AMI was explored.

Results

Compared with UA group and control group, the expression of sSema4D in peripheral blood of STEMI group was significantly increased (P<0.001), which could better reflect the inflammatory status of patients with STEMI than traditional inflammatory indicators [hypersensitive c-reactive protein (hs-CRP)] (P<0.05). The receiver operating characteristic (ROC) curve showed that sSema4D (AUC =0.780, cut-off =19.62, 95% CI: 0.629, 0.837, P<0.001) was more specific than hs-CRP (AUC =0.697, cut-off =3.39, 95% CI: 0.629, 0.765, P<0.001) in reflecting the inflammatory status of STEMI patients.

Conclusions

sSema4D levels have certain value in reflecting the inflammatory state of STEMI.

The role of semaphorins in cardiovascular diseases: Potential therapeutic targets and novel biomarkers

Semaphorins (Semas), which belongs to the axonal guidance molecules, include 8 classes and could affect axon growth in the nervous system. Recently, semaphorins were found to regulate other pathophysiological processes, such as immune response, oncogenesis, tumor angiogenesis, and bone homeostasis, through binding with their plexin and neuropilin receptors. In this review, we summarized the detailed role of semaphorins and their receptors in the pathological progression of various cardiovascular diseases (CVDs), highlighting that semaphorins may be potential therapeutic targets and novel biomarkers for CVDs.

Assessment of the relationship between semaphorin4D level and recurrence after catheter ablation in paroxysmal atrial fibrillation

OBJECTIVE

Semaphorin4D (Sema4D), a novel integral membrane glycoprotein, plays a role in atherosclerosis, angiogenesis and chronic inflammation. Elevated levels of sema4D were presented in myocardial infarction, heart failure and atrial fibrillation. Aim of the study was to investigate the relation between sema4D and recurrence after catheter ablation (CA) in paroxysmal AF.

METHODS

The present study included 161 paroxysmal AF patients (PAF) (101 patients undergone CA) and 60 healthy subjects. Serum levels of sema4D were measured and study participants were followed-up for 3 months and 1 year since CA in terms of recurrence respectively.

RESULTS

Sema4D levels were significantly elevated in the recurrent group compared to the non-recurrent PAF patients (p < 0.001). Sema4D was importantly positively correlated with both left atrial volume index (r = 0.51, p < 0.013) and high sensitive C-reactive protein (r = 0.38), p < 0.011). In multivariate analysis, sema4D [odds ratio (OR) = 1.23, 95% CI 1.11-1.42; p < 0.001] and left atrial diameter (OR = 1.13, 95% CI 1.02-1.23; p = 0.012) were found to be significant independent risk parameters for recurrence.

CONCLUSIONS

Sema4D is a novel biomarker that may help to identify individuals with recurrence after CA procedure in long term period in PAF.

CD100 modulates cytotoxicity of CD8+ T cells in patients with acute myocardial infarction

BACKGROUND

CD100 is an immune semaphorin family member that highly expressed on T cells, which take part in the development of acute myocardial infarction (AMI). Matrix metalloproteinases (MMPs) are important mediators for membrane-bound CD100 (mCD100) shedding from T cells to generate soluble CD100 (sCD100), which has immunoregulatory effect on T cells. The aim of this study was to investigate modulatory role of CD100 on CD8⁺ T cell activity in AMI patients.

METHODS

Peripheral sCD100 and MMP-2 level, as well as mCD100 level on T cells was assessed in patients with stable angina pectoris (SAP), unstable angina pectoris (UAP), and AMI. The regulatory function of MMP-2 on mCD100 shedding, sCD100 formation, and cytotoxicity of CD8⁺ T cells was analyzed in direct and indirect contact co-culture system.

RESULTS

AMI patients had higher peripheral sCD100 and lower mCD100 expression on CD8⁺ T cells in comparison with SAP, UAP, and controls. CD8⁺ T cells in AMI patients showed elevated direct cytotoxicity, enhanced cytokine production, and increased perforin/granzyme B secretion. Recombinant sCD100 stimulation promoted cytolytic function of CD8⁺ T cells in controls and AMI patients. Furthermore, AMI patients also had elevated circulating MMP-2 level. Recombinant MMP-2 stimulation induced mCD100 shedding from CD8⁺ T cells and sCD100 generation, resulting in enhancement of CD8⁺ T cell cytotoxicity in AMI patients.

CONCLUSION

Up-regulation of MMP-2 might contribute to elevation of mCD100 shedding and sCD100 formation, leading to increased cytotoxicity CD8⁺ T cells in AMI patients.

CD100 Effects in Macrophages and Its Roles in Atherosclerosis

CD100 or Sema4D is a protein from the semaphorin family with important roles in the vascular, nervous and immune systems. It may be found as a membrane bound dimer or as a soluble molecule originated by proteolytic cleavage. Produced by the majority of hematopoietic cells including B and T lymphocytes, natural killer and myeloid cells, as well as endothelial cells, CD100 exerts its actions by binding to different receptors depending on the cell type and on the organism. Cell-to-cell adhesion, angiogenesis, phagocytosis, T cell priming, and antibody production are examples of the many functions of this molecule. Of note, high CD100 serum levels has been found in inflammatory as well as in infectious diseases, but the roles of the protein in the pathogenesis of these diseases has still to be clarified. Macrophages are highly heterogeneous cells present in almost all tissues, which may change their functions in response to microenvironmental conditions. They are key players in the innate and adaptive immune responses and have decisive roles in sterile conditions but also in several diseases such as atherosclerosis, autoimmunity, tumorigenesis, and antitumor responses, among others. Although it is known that macrophages express CD100 and its receptors, few studies have focused on the role of this semaphorin in this cell type or in macrophage-associated diseases. The aim of this review is to critically revise the available data about CD100 and atherosclerosis, with special emphasis on its roles in macrophages and monocytes. We will also describe the few available data on treatments with anti-CD100 antibodies in different diseases. We hope that this review stimulates future studies on the effects of such an important molecule in a cell type with decisive roles in inflammatory diseases such as atherosclerosis.

Semaphorin 4D levels in heart failure patients: a potential novel biomarker of acute heart failure?

AIMS

Semaphorin 4D (Sema4D) is expressed on platelets and T-cells and known to be involved in inflammation. The aims of this study include comparing Sema4D and N terminal pro brain natriuretic peptide (NT-proBNP) serum levels in heart failure (HF) patients to a control group, evaluating the correlation between Sema4D and NT-proBNP levels, and assessing Sema4D serum levels in HF patients during acute exacerbation and remission.

METHODS AND RESULTS

Forty-five patients diagnosed with HF (based on echocardiographic findings, positive NT-proBNP levels, and normal C-reactive protein) and 11 healthy controls (declaring no chronic diseases or medications) comprised the study population. Demographic, clinical, laboratory, and echocardiographic data were used to create the study database. NT-proBNP and Sema4D serum samples were taken on admission and discharge. NT-proBNP levels were significantly higher in the HF group than in controls (P < 0.001). Sema4D levels were significantly higher in HF patients than in healthy controls (2143.04 ± 1253 vs. 762.18 ± 581.6 ng/mL, P < 0.001, respectively). Using linear regression, a higher creatinine level was found to predict both higher levels of NT-proBNP and Sema4D (P = 0.05 and P < 0.014, respectively), while a reduced ejection fraction was found to predict higher NT-proBNP levels only (P < 0.001 and P = 0.87, respectively). Average Sema4D levels reduced significantly at remission (3534.94 ± 1650.55 vs. 2455.67 ± 1424, P = 0.03), while mean NT-proBNP levels did not change significantly.

CONCLUSIONS

Sema4D levels in HF patients' serum are significantly higher than in healthy controls. Clinical improvement caused rapid reduction in Sema4D levels, possibly reflecting the inflammatory aspect of HF. These findings might suggest that Sema4D can be used as a diagnostic biomarker of acute HF. Further studies of Sema4D and HF are warranted.

Endogenous Regulators of the Immune System (sCD100, Malonic Dialdehyde, and Arginase)

Tissue damage in various diseases, hypoxic conditions, and some pathologies are associated with production of endogenous factors such as the soluble form of the surface receptor CD100, malonic dialdehyde, and arginase and their release into circulation. These factors modulate functional state of lymphocytes in the immune system: potentiate activation of B lymphocytes, activate synthesis and secretion of IL-25 and IL-17 cytokines, and suppress proliferative activity of T lymphocytes, thus modulating immunological reactivity of the organism. Reactions of innate and adaptive immunity develop against the background of changed immunological reactivity, which should be taken into account in the development of pathogenetically substantiated therapy.

The Role of Semaphorin 4D in Bone Remodeling and Cancer Metastasis

Semaphorin 4D (Sema4D; CD100) is a transmembrane homodimer 150-kDa glycoprotein member of the Semaphorin family. Semaphorins were first identified as chemorepellants that guide neural axon growth. Sema4D also possesses immune regulatory activity. Recent data suggest other Sema4D functions: inactivation of platelets, stimulation of angiogenesis, and regulation of bone formation. Sema4D is a coupling factor expressed on osteoclasts that inhibits osteoblast differentiation. Blocking Sema4D may, therefore, be anabolic for bone. Sema4D and its receptor Plexin-B1 are commonly dysregulated in cancers, suggesting roles in cancer progression, invasion, tumor angiogenesis, and skeletal metastasis. This review focuses on Sema4D in bone and cancer biology and the molecular pathways involved, particularly Sema4D-Plexin-B1 signaling crosstalk between cancer cells and the bone marrow microenvironment-pertinent areas since a humanized Sema4D-neutralizing antibody is now in early phase clinical trials in cancers and neurological disorders.