Serum vascular adhesion protein-1 level predicts risk of incident cancers in subjects with type II diabetes

The role of vascular adhesion protein-1 in diabetes and diabetic complications

Vascular adhesion protein-1 (VAP-1) plays a dual role with its adhesive and enzymatic properties, facilitating leukocyte migration to sites of inflammation and catalyzing the breakdown of primary amines into harmful by-products, which are linked to diabetic complications. Present in various tissues, VAP-1 also circulates in a soluble form in the bloodstream. Diabetes is associated with several complications such as cardiovascular disease, retinopathy, nephropathy, and neuropathy, significantly contributing to disability and mortality. These complications arise from hyperglycemia-induced oxidative stress, inflammation, and the formation of advanced glycation end-products (AGEs). Earlier research, including our own from the 1990s and early 2000s, has underscored the critical role of VAP-1 in these pathological processes, prompting extensive investigation into its contribution to diabetic complications. In this review, we examine the involvement of VAP-1 in diabetes and its complications, alongside its link to other conditions related to diabetes, such as cancer and metabolic dysfunction-associated fatty liver disease. We also explore the utility of soluble VAP-1 as a biomarker for diabetes, its complications, and other related conditions. Since the inhibition of VAP-1 to treat diabetic complications is a novel and promising treatment option, further studies are needed to translate the beneficial effect of VAP-1 inhibitors observed in animal studies to clinical trials recruiting human subjects. Besides, future studies should focus on using serum sVAP-1 levels for risk assessment in diabetic patients, identifying those who need intensive glycemic control, and determining the patient population that would benefit most from VAP-1 inhibitor therapies.

Serum vascular adhesion protein-1 is associated with twelve-year risk of incident cancer, cancer mortality, and all-cause mortality: a community-based cohort study

Background

Vascular adhesion protein-1 (VAP-1), a dual-function glycoprotein, has been reported to play a crucial role in inflammation and tumor progression. We conducted a community-based cohort study to investigate whether serum VAP-1 could be a potential biomarker for predicting incident cancers and mortality.

Method

From 2006 to 2018, we enrolled 889 cancer-free subjects at baseline. Serum VAP-1 levels were measured using a time-resolved immunofluorometric assay. Cancer and vital status of the participants were obtained by linking records with the computerized cancer registry and death certificates in Taiwan.

Results

During a median follow-up of 11.94 years, 69 subjects developed incident cancers and 66 subjects died, including 29 subjects who died from malignancy. Subjects in the highest tertile of serum VAP-1 had a significantly higher risk of cancer incidence (p=0.0006), cancer mortality (p=0.0001), and all-cause mortality (p=0.0002) than subjects in the other tertiles. The adjusted hazard ratios per one standard deviation increase in serum VAP-1 concentrations were 1.28 for cancer incidence (95% CI=1.01-1.62), 1.60 for cancer mortality (95% CI=1.14-2.23), and 1.38 for all-cause mortality (95% CI=1.09-1.75). The predictive performance of serum VAP-1 was better than that of gender, smoking, body mass index, hypertension, diabetes, and estimated glomerular filtration rate but lower than that of age for cancer incidence, cancer mortality, and all-cause mortality, as evidenced by higher increments in concordance statistics and area under the receiver operating characteristic curve.

Conclusion

Serum VAP-1 levels are associated with a 12-year risk of incident cancer, cancer mortality, and all-cause mortality in a general population.

Vascular adhesion protein-1 (VAP-1) in vascular inflammatory diseases

Summary: Vascular adhesion protein-1 (VAP-1) also known as amino oxidase copper containing 3 (AOC3) is a pro-inflammatory and versatile molecule with adhesive and enzymatic properties. VAP-1 is a primary amine oxidase belonging to the semicarbazide-sensitive amine oxidase (SSAO) family, which catalyzes the oxidation of primary amines leading to the production of ammonium, formaldehyde, methylglyoxal, and hydrogen peroxide. VAP-1 is mainly expressed by endothelial cells, smooth muscle cells, adipocytes and pericytes. It is involved in a repertoire of biological functions, e.g., immune cell extravasation, angiogenesis, and vascularization. Research into VAP-1 has intensified within the last decade on its role as a novel clinical biomarker and as a potential therapeutic target of vascular inflammatory disorders such as atherosclerosis, stroke, diabetes, neurovascular disorders (e.g., Alzheimer’s Disease), hepatic disease (e.g., non-alcoholic steatohepatitis), and skin conditions (e.g., psoriasis). This is the most up-to-date and comprehensive review on VAP-1 focusing on the translational aspects of VAP-1. Compared to recent reviews, our review provides novel insights on VAP-1 and heart failure, stroke and frailty, diabetes, endometriosis, osteoarthritis, COVID-19, conjunctivitis associated systemic lupus erythematosus, hematopoietic stem cells, gliomas, treatment of colorectal cancer with a novel VAP-1 inhibitor (U-V269), promoting recovery of motor functions and habit learning with a novel VAP-1 inhibitor (PXS-4681A), and 68Ga-DOTA-Siglec-9, a labelled peptide of Siglec-9 (a VAP-1 ligand), which appears to be a safe PET tracer for inflammation in rheumatoid arthritis. Finally, we present the emerging role of VAP-1 in pregnancy as a gatekeeper of immune cells, which are critical for spiral arterial remodeling, the deficiency of which could lead to vascular disorders of pregnancy such as preeclampsia. Future research should prioritize clinical trials on VAP-1 small-molecule inhibitors and monoclonal antibodies, thus, maximizing the potential of VAP-1 targeted therapy as well as research into sVAP-1 as a clinical biomarker of diseases and its prognosis.

Amine oxidase copper-containing 3 (AOC3) inhibition: a potential novel target for the management of diabetic retinopathy

Background

Diabetic retinopathy (DR), a microvascular complication of diabetes, is the leading cause of visual impairment in people aged 20–65 years and can go undetected until vision is irreversibly lost. There is a need for treatments for non-proliferative diabetic retinopathy (NPDR) which, in comparison with current intravitreal (IVT) injections, offer an improved risk–benefit ratio and are suitable for the treatment of early stages of disease, during which there is no major visual impairment. Efficacious systemic therapy for NPDR, including oral treatment, would be an important and convenient therapeutic approach for patients and physicians and would reduce treatment burden. In this article, we review the rationale for the investigation of amine oxidase copper-containing 3 (AOC3), also known as semicarbazide-sensitive amine oxidase and vascular adhesion protein 1 (VAP1), as a novel target for the early treatment of moderate to severe NPDR. AOC3 is a membrane-bound adhesion protein that facilitates the binding of leukocytes to the retinal endothelium. Adherent leukocytes reduce blood flow and in turn rupture blood vessels, leading to ischemia and edema. AOC3 inhibition reduces leukocyte recruitment and is predicted to decrease the production of reactive oxygen species, thereby correcting the underlying hypoxia, ischemia, and edema seen in DR, as well as improving vascular function.

Conclusion

There is substantial unmet need for convenient, non-invasive treatments targeting moderately severe and severe NPDR to reduce progression and preserve vision. The existing pharmacotherapies (IVT corticosteroids and IVT anti-vascular endothelial growth factor-A) target inflammation and angiogenesis, respectively. Unlike these treatments, AOC3 inhibition is predicted to address the underlying hypoxia and ischemia seen in DR. AOC3 inhibitors represent a promising therapeutic strategy for treating patients with DR and could offer greater choice and reduce treatment burden, with the potential to improve patient compliance.

Vascular Adhesion Protein-1: A Cell Surface Amine Oxidase in Translation

Significance: Vascular adhesion protein-1 (VAP-1) is an ectoenzyme that oxidates primary amines in a reaction producing also hydrogen peroxide. VAP-1 on the blood vessel endothelium regulates leukocyte extravasation from the blood into tissues under physiological and pathological conditions. Recent Advances: Inhibition of VAP-1 by neutralizing antibodies and by several novel small-molecule enzyme inhibitors interferes with leukocyte trafficking and alleviates inflammation in many experimental models. Targeting of VAP-1 also shows beneficial effects in several other diseases, such as ischemia/reperfusion, fibrosis, and cancer. Moreover, soluble VAP-1 levels may serve as a new prognostic biomarker in selected diseases. Critical Issues: Understanding the contribution of the enzyme activity-independent and enzyme activity-dependent functions, which often appear to be mediated by the hydrogen peroxide production, in the VAP-1 biology will be crucial. Similarly, there is a pressing need to understand which of the VAP-1 functions are regulated through the modulation of leukocyte trafficking, and what is the role of VAP-1 synthesized in adipose and smooth muscle cells. Future Directions: The specificity and selectivity of new VAP-1 inhibitors, and their value in animal models under therapeutic settings need to be addressed. Results from several programs studying the therapeutic potential of VAP-1 inhibition, which now are in clinical trials, will reveal the relevance of this amine oxidase in humans.

Standard and competing risk analysis of the effect of albuminuria on cardiovascular and cancer mortality in patients with type 2 diabetes mellitus

BACKGROUND

Competing risks occur when populations may experience outcomes that either preclude or alter the probability of experiencing the main study outcome(s). Many standard survival analysis methods do not account for competing risks. We used mortality risk in people with diabetes with and without albuminuria as a case study to investigate the impact of competing risks on measures of absolute and relative risk.

METHODS

A population with type 2 diabetes was identified in Clinical Practice Research Datalink as part of a historical cohort study. Patients were followed for up to 9 years. To quantify differences in absolute risk estimates of cardiovascular and cancer, mortality standard (Kaplan-Meier) estimates were compared to competing-risks-adjusted (cumulative incidence competing risk) estimates. To quantify differences in measures of association, regression coefficients for the effect of albuminuria on the relative hazard of each outcome were compared between standard cause-specific hazard (CSH) models (Cox proportional hazards regression) and two competing risk models: the unstratified Lunn-McNeil model, which estimates CSH, and the Fine-Gray model, which estimates subdistribution hazard (SDH).

RESULTS

In patients with normoalbuminuria, standard and competing-risks-adjusted estimates for cardiovascular mortality were 11.1% (95% confidence interval (CI) 10.8-11.5%) and 10.2% (95% CI 9.9-10.5%), respectively. For cancer mortality, these figures were 8.0% (95% CI 7.7-8.3%) and 7.2% (95% CI 6.9-7.5%). In patients with albuminuria, standard and competing-risks-adjusted estimates for cardiovascular mortality were 21.8% (95% CI 20.9-22.7%) and 18.5% (95% CI 17.8-19.3%), respectively. For cancer mortality, these figures were 10.7% (95% CI 10.0-11.5%) and 8.6% (8.1-9.2%). For the effect of albuminuria on cardiovascular mortality, regression coefficient values from multivariable standard CSH, competing risks CSH, and competing risks SDH models were 0.557 (95% CI 0.491-0.623), 0.561 (95% CI 0.494-0.628), and 0.456 (95% CI 0.389-0.523), respectively. For the effect of albuminuria on cancer mortality, these values were 0.237 (95% CI 0.148-0.326), 0.244 (95% CI 0.154-0.333), and 0.102 (95% CI 0.012-0.192), respectively.

CONCLUSIONS

Studies of absolute risk should use methods that adjust for competing risks to avoid over-stating risk, such as the CICR estimator. Studies of relative risk should consider carefully which measure of association is most appropriate for the research question.

Serum vascular adhesion protein-1 is up-regulated in hyperglycemia and is associated with incident diabetes negatively

BACKGROUND/OBJECTIVES

Vascular adhesion protein-1 (VAP-1) can enhance tissue glucose uptake in cell studies and normalize hyperglycemia in animal studies. However, serum VAP-1 concentration (sVAP-1) is higher in subjects with diabetes in cross-sectional studies. In this cohort study, we test our hypothesis that sVAP-1 is increased in prediabetes to counteract hyperglycemia and is associated with incident diabetes negatively.

SUBJECTS/METHODS

From 2006 to 2012, 600 subjects without diabetes from Taiwan Lifestyle Study were included and followed regularly. Diabetes was diagnosed if FPG ≥ 126 mg/dL (7 mmol/L), 2-h plasma glucose (2hPG) during an oral glucose tolerance test (OGTT) ≥ 200 mg/dL (11.1 mmol/L), or hemoglobin A1c (HbA1c) ≥ 6.5%, or if the subject received anti-diabetic medications. Abdominal fat areas were measured by abdominal computed tomography and sVAP-1 was analyzed by ELISA.

RESULTS

sVAP-1 was higher in subjects with prediabetes (p < 0.05) and increased during an OGTT (p < 0.001). Fasting sVAP-1 was associated with the response of sVAP-1 during an OGTT (p < 0.001). Besides, sVAP-1 was associated negatively with body mass index (BMI, r = -0.1449, p = 0.003), waist circumference (r = -0.1425, p = 0.004), abdominal visceral (r = -0.1457, p = 0.003), and subcutaneous (r = -0.1025, p = 0.035) fat areas, and serum high-sensitivity C-reactive protein (hsCRP) concentration (r = -0.2035, p < 0.0001), and positively with plasma adiponectin concentration (r = 0.2086, p < 0.0001), adjusted for age and gender. After 4.7 ± 2.6 years, 73 subjects (12.2%) developed incident diabetes. High sVAP-1 predicted a lower incidence of diabetes, adjusted for age, gender, BMI, family history of diabetes, HbA1c, HOMA2-%B and HOMA2-IR (HR = 0.66, 95% CI = 0.50-0.88, p < 0.01).

CONCLUSIONS

sVAP-1 is increased in response to hyperglycemia. It is associated with obesity and serum hsCRP concentration negatively, and plasma adiponectin concentration positively. Besides, a high sVAP-1 is associated with a lower incidence of diabetes in human.

Vascular adhesion protein-1: Role in human pathology and application as a biomarker

Vascular adhesion protein-1 (VAP-1) is a member of the copper-containing amine oxidase/semicarbazide-sensitive amine oxidase (AOC/SSAO) enzyme family. SSAO enzymes catalyze oxidative deamination of primary amines, which results in the production of the corresponding aldehyde, hydrogen peroxide and ammonium. VAP-1 is continuously expressed as a transmembrane glycoprotein in the vascular wall during development and facilitates the accumulation of inflammatory cells into the inflamed environment in concert with other leukocyte adhesion molecules. The soluble form of VAP-1 is released into the circulation mainly from vascular endothelial cells. Over- and under-expression of sVAP-1 result in alterations of the reported reaction product levels, which are involved in the pathogenesis of multiple human diseases. The combination of enzymatic and adhesion capacities as well as its strong association with inflammatory pathologies makes VAP-1 an interesting therapeutic target for drug discovery. In this article, we will review the general characteristics and biological functions of VAP-1, focusing on its important role as a prognostic biomarker in human pathologies. In addition, the potential therapeutic application of VAP-1 inhibitors will be discussed.