Adenosine Deaminase Activity in Chronic Lymphocytic Leukemia and Healthy Subjects

Identification of ADA as a Biomarker for Atypical Epstein Barr Virus Infection in Children

OBJECTIVE

This study aims to explore the ability of adenosine deaminase (ADA) to discriminate atypical Epstein Barr virus (EBV) infection in children from acute febrile illness.

METHODS

All children admitted to the Children's Hospital of Soochow University between 2018 and 2019, who were acute febrile patients and subjected to the plasma EBV-DNA polymerase chain reaction (PCR) and indirect immunofluorescence (IIF) assay for EBV-specific antibodies assays. The diagnostic value of each detection index was compared by the area under the ROC curve.

RESULTS

In children with atypical Epstein Barr virus infection, the sensitivity, specificity, positive predictive value, negative predictive value and Youden index were 62.87%, 100.00%,100.00%, 61.73% and 0.63 for EBV-DNA PCR assay, 80.84%, 100.00%, 100.00%, 75.76% and 0.81 for VCA-IgG avidity and 89.22%, 87.00%, 91.98%, 82.86% and 0.76 for ADA. VCA-IgG avidity (AUC=0.904, P<0.01) and ADA (AUC=0.881, P<0.01) assays had the great diagnostic efficiency. In addition, the sensitivity, specificity and AUC were 92.75%,91.43% and 0.921(95%CI: 0.856-0.985) for ADA in the course≤3 days group, respectively.

CONCLUSIONS

ADA has a good diagnostic value in the early stage of atypical EBV infection, and is not affected by primary EBV infection and reactivation. SCHLüSSELWöRTER: Adenosine deaminase, Epstein -Barr virus, Biomarker, children.

Adenosine, Schizophrenia and Cancer: Does the Purinergic System Offer a Pathway to Treatment?

For over a century, a complex relationship between schizophrenia diagnosis and development of many cancers has been observed. Findings from epidemiological studies are mixed, with reports of increased, reduced, or no difference in cancer incidence in schizophrenia patients. However, as risk factors for cancer, including elevated smoking rates and substance abuse, are commonly associated with this patient population, it is surprising that cancer incidence is not higher. Various factors may account for the proposed reduction in cancer incidence rates including pathophysiological changes associated with disease. Perturbations of the adenosine system are hypothesized to contribute to the neurobiology of schizophrenia. Conversely, hyperfunction of the adenosine system is found in the tumor microenvironment in cancer and targeting the adenosine system therapeutically is a promising area of research in this disease. We outline the current biochemical and pharmacological evidence for hypofunction of the adenosine system in schizophrenia, and the role of increased adenosine metabolism in the tumor microenvironment. In the context of the relatively limited literature on this patient population, we discuss whether hypofunction of this system in schizophrenia, may counteract the immunosuppressive role of adenosine in the tumor microenvironment. We also highlight the importance of studies examining the adenosine system in this subset of patients for the potential insight they may offer into these complex disorders.

Diversity of adenosine deaminase in children with EBV-related diseases

Background

Adenosine deaminase (ADA) is an enzyme involved in purine metabolism with an important role in cellular immunity. Thus, this study investigated the association between ADA and Epstein–Barr virus (EBV)-related diseases.

Methods

We retrospectively collected data from all children admitted to the Children’s Hospital of Soochow University, Suzhou, China, between May 1, 2018, and March 31, 2019, who underwent plasma EBV-DNA polymerase chain reaction, alanine aminotransferase (ALT), and ADA testing.

Results

Of 6868 children, 1877 had an elevated level of ADA, and 4991 had a level within the normal range. Multivariate logistic regression analysis indicated that ALT (adjusted odds radio [aOR] = 1.001, 95% confidence interval [CI]: 1.001–1.002), EBV infection (aOR = 8.486, 95% CI: 6.753–10.663), inflammatory disease (aOR = 3.915, 95% CI: 3.198–4.794), autoimmune disease (aOR = 2.307, 95% CI: 1.823–2.920), and malignant disease (aOR = 1.381; 95% CI: 1.101–1.734) were risk factors for an elevated ADA level. Furthermore, the ADA levels among EBV-related diseases significantly differed, including infectious mononucleosis, atypical EBV infection, respiratory infection, malignant disease, and other diseases (P < 0.05). In addition, the ADA level positively correlated with the Epstein–Barr viral load (r = 0.501, P < 0.05).

Conclusions

This large, retrospective study identified a correlation between ADA and EBV-related diseases, which may help clinicians detect these diseases earlier based on the plasma ADA concentration.

Adenosine deaminase as a marker for the severity of infectious mononucleosis secondary to EBV in children

Background

Infectious mononucleosis, a common disease in children and young adults, is often accompanied by elevated transaminase levels and rarely, liver failure. This study aimed to determine whether adenosine deaminase is a marker of severity in children with infectious mononucleosis, especially those with elevated alanine transaminase levels.

Methods

This case-control study was conducted at the Children’s Hospital of Soochow University. A total of 104 children with infectious mononucleosis and 50 controls with other acute infections and fever, tonsillitis, or lymphadenitis, were enrolled in the study. Among the 104 children with infectious mononucleosis, 54 had normal alanine transaminase levels and 50 had elevated alanine transaminase levels. The children’s clinical and laboratory data were analyzed to assess the diagnostic value of adenosine deaminase in the three groups.

Results

The adenosine deaminase level in the infectious mononucleosis group was significantly higher than that in the control group (P < 0.001). The adenosine deaminase levels were highly correlated with lymphocyte count, CD3⁺CD8⁺ T cells (%), CD4⁺/CD8⁺ ratio, and CD3⁻CD19⁺ (%) (r > 0.7, P < 0.01). The sensitivity and specificity of adenosine deaminase in predicting children with infectious mononucleosis were 97.1% and 94.0%, respectively. Furthermore, multivariate regression analysis revealed that adenosine deaminase level was a risk factor for elevated alanine transaminase in children with infectious mononucleosis.

Conclusions

Adenosine deaminase may be a marker of the severity of infectious mononucleosis in children, and a predictor of elevated alanine transaminase in children with infectious mononucleosis.

Prognostic and Therapeutic Value of Apolipoprotein A and a New Risk Scoring System Based on Apolipoprotein A and Adenosine Deaminase in Chronic Lymphocytic Leukemia

Lipid metabolism is related to lymphomagenesis, and is a novel therapeutic target in some hematologic tumors. Apolipoprotein A (ApoA), the major protein of high-density lipoprotein (HDL), plays a crucial role in lipid transportation and protecting against cardiovascular disease, and takes effect on anti-inflammation and anti-oxidation. It is correlated with the prognosis of some solid tumors. Yet, there is no investigation involving the role of ApoA plays in chronic lymphocytic leukemia (CLL). Our retrospective study focuses on the prognostic value of ApoA in CLL and its therapeutic potential for CLL patients. Herein, ApoA is a favorable independent prognostic factor for both overall survival (OS) and progression-free survival (PFS) of CLL patients. ApoA is negatively associated with β2-microglobulin (β2-MG) and advanced stage, which are poor prognostic factors in CLL. Age, Rai stage, ApoA, and adenosine deaminase (ADA) are included in a new risk scoring system named ARAA-score. It is capable of assessing OS and PFS of CLL patients. Furthermore, cell proliferation assays show that the ApoA-I mimetic L-4F can inhibit the proliferation of CLL cell lines and primary cells. In conclusion, ApoA is of prognostic value in CLL, and is a potential therapy for CLL patients. The ARAA-score may optimize the risk stratification of CLL patients.

Biochemical characterization of adenosine deaminase (CD26; EC 3.5.4.4) activity in human lymphocyte-rich peripheral blood mononuclear cells

The conversion of adenosine to inosine is catalyzed by adenosine deaminase (ADA) (EC 3.5.4.4), which has two isoforms in humans (ADA1 and ADA2) and belongs to the zinc-dependent hydrolase family. ADA modulates lymphocyte function and differentiation, and regulates inflammatory and immune responses. This study investigated ADA activity in lymphocyte-rich peripheral blood mononuclear cells (PBMCs) in the absence of disease. The viability of lymphocyte-rich PBMCs isolated from humans and kept in 0.9% saline solution at 4-8°C was analyzed over 20 h. The incubation time and biochemical properties of the enzyme, such as its Michaelis-Menten constant (Km) and maximum velocity (Vmax), were characterized through the liberation of ammonia from the adenosine substrate. Additionally, the presence of ADA protein on the lymphocyte surface was determined by flow cytometry using an anti-CD26 monoclonal human antibody, and the PBMCs showed long-term viability after 20 h. The ADA enzymatic activity was linear from 15 to 120 min of incubation, from 2.5 to 12.5 µg of protein, and pH 6.0 to 7.4. The Km and Vmax values were 0.103±0.051 mM and 0.025±0.001 nmol NH3·mg-1·s-1, respectively. Zinc and erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) inhibited enzymatic activity, and substrate preference was given to adenosine over 2'-deoxyadenosine and guanosine. The present study provides the biochemical characterization of ADA in human lymphocyte-rich PBMCs, and indicates the appropriate conditions for enzyme activity quantification.

Analytical validation of an automated assay for the measurement of adenosine deaminase (ADA) and its isoenzymes in saliva and a pilot evaluation of their changes in patients with SARS-CoV-2 infection

OBJECTIVES

The aim of the present study was to validate a commercially available automated assay for the measurement of total adenosine deaminase (tADA) and its isoenzymes (ADA1 and ADA2) in saliva in a fast and accurate way, and evaluate the possible changes of these analytes in individuals with SARS-CoV-2 infection.

METHODS

The validation, in addition to the evaluation of precision and accuracy, included the analysis of the effects of the main procedures that are currently being used for SARS-CoV-2 inactivation in saliva and a pilot study to evaluate the possible changes in salivary tADA and isoenzymes in individuals infected with SARS-CoV-2.

RESULTS

The automated assay proved to be accurate and precise, with intra- and inter-assay coefficients of variation below 8.2%, linearity under dilution linear regression with R² close to 1, and recovery percentage between 80 and 120% in all cases. This assay was affected when the sample is treated with heat or SDS for virus inactivation but tolerated Triton X-100 and NP-40. Individuals with SARS-CoV-2 infection (n=71) and who recovered from infection (n=11) had higher mean values of activity of tADA and its isoenzymes than healthy individuals (n=35).

CONCLUSIONS

tADA and its isoenzymes ADA1 and ADA2 can be measured accurately and precisely in saliva samples in a rapid, economical, and reproducible way and can be analyzed after chemical inactivation with Triton X-100 and NP-40. Besides, the changes observed in tADA and isoenzymes in individuals with COVID-19 open the possibility of their potential use as non-invasive biomarkers in this disease.

Characterization of total adenosine deaminase activity (ADA) and its isoenzymes in saliva and serum in health and inflammatory conditions in four different species: an analytical and clinical validation pilot study

Background

Measurement of adenosine deaminase (ADA) can provide information about cell-mediated immunity. This report’s objective was to study the enzymatic activity of total ADA (tADA) and its isoenzymes ADA1 and ADA2 in canine, equine, porcine, and bovine serum and saliva and their changes in different inflammatory situations in each species. Besides, an automated method for ADA2 measurement was developed and validated.

Results

tADA was present in serum and saliva of healthy animals of the four species. Erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) concentration of 0.47 mM was needed for ADA1 inhibition in canine and porcine samples (serum and saliva) and bovine saliva, whereas for equine saliva 0.94 mM was needed. ADA2 activity was not detected in bovine serum and was very low or absent in equine serum and bovine saliva. An automated procedure to measure ADA2 consisting of adding EHNA to a commercial reagent for tADA measurement provided repetitive (coefficients of variation < 8.8% in serum and < 10% in saliva) and accurate (linearity of serial sample dilutions with R² > 0.90) results, being equivalent to a manual incubation of the sample with EHNA at a similar concentration. Salivary tADA, as well as ADA1 and ADA2, were higher in dogs with leishmaniosis, horses with acute abdominal disease and pigs with lameness than in healthy animals. tADA and isoenzymes in saliva showed a positive significant correlation with serum ferritin in dogs (r = 0.602, P < 0.01; r = 0.555, P < 0.05; and r = 0.632, P < 0.01; respectively for tADA, ADA1 and ADA2) and serum C-reactive protein in pigs (r = 0.700, P < 0.01, for both tADA and ADA1; r = 0.770, P < 0.001, for ADA2), whereas salivary ADA2 significantly correlated with serum amyloid A in horses (r = 0.649, P < 0.01). In cows, salivary tADA and ADA1 significantly increased after calving, correlating with total white blood cell count (r = 0.487, P < 0.05, for both tADA and ADA1).

Conclusions

The activity of total ADA and its different isoenzymes, can be measured in serum and saliva of dogs, horses, pigs and cows by a simple and fast procedure described in this report. When measured in saliva, these analytes correlated with other biomarkers of inflammation and it could potentially be used as a biomarkers of inflammation and immune activation in the species of this study.

Purine-Metabolising Enzymes and Apoptosis in Cancer

The enzymes of both de novo and salvage pathways for purine nucleotide synthesis are regulated to meet the demand of nucleic acid precursors during proliferation. Among them, the salvage pathway enzymes seem to play the key role in replenishing the purine pool in dividing and tumour cells that require a greater amount of nucleotides. An imbalance in the purine pools is fundamental not only for preventing cell proliferation, but also, in many cases, to promote apoptosis. It is known that tumour cells harbour several mutations that might lead to defective apoptosis-inducing pathways, and this is probably at the basis of the initial expansion of the population of neoplastic cells. Therefore, knowledge of the molecular mechanisms that lead to apoptosis of tumoural cells is key to predicting the possible success of a drug treatment and planning more effective and focused therapies. In this review, we describe how the modulation of enzymes involved in purine metabolism in tumour cells may affect the apoptotic programme. The enzymes discussed are: ectosolic and cytosolic 5'-nucleotidases, purine nucleoside phosphorylase, adenosine deaminase, hypoxanthine-guanine phosphoribosyltransferase, and inosine-5'-monophosphate dehydrogenase, as well as recently described enzymes particularly expressed in tumour cells, such as deoxynucleoside triphosphate triphosphohydrolase and 7,8-dihydro-8-oxoguanine triphosphatase.

Rapid, reliable, and sensitive detection of adenosine deaminase activity by UHPLC-Q-Orbitrap HRMS and its application to inhibitory activity evaluation of traditional Chinese medicines

Adenosine deaminase (ADA), which is a key enzyme in the metabolism of purine nucleosides, plays important roles in diverse disorders, such as tuberculosis, diabetes, liver disorders, and cancer. Determination of the activities of ADA and its isoenzymes in body fluids has received considerable attention in the diagnosis and treatment of relative diseases. Ultraviolet spectroscopy with adenosine (AD) as a substrate is a classical approach for screening potential ADA inhibitors by measuring the decrease in substrate (AD) at 265 nm or increase in the product (inosine) at 248 nm. However, AD and inosine share a very close maximum absorption wavelength, and the reaction is uncertain and is frequently interfered by the background color of matrix compounds or plant extracts. Thus, the method usually yields false positive or negative results. In this study, a novel, rapid, sensitive, and accurate ultra-high-performance liquid chromatography-Q exactive hybrid quadrupole orbitrap high-resolution accurate mass spectrometric (UHPLC-Q-Orbitrap HRMS) method was developed for determining and screening ADA inhibitors by directly determining the deamination product of AD, inosine. A proper separation was achieved for inosine and chlormequat (internal standard) within 2 min via isocratic elution (0.1% formic acid:methanol = 85:15, v/v) at a flow rate of 0.3 mL min^-1 on a Waters ACQUITY HSS T3 column (2.1 mm × 100 mm, 1.8 μm) following a simple precipitation of proteins. The intra- and inter-day precisions of the developed method were below 7.17% and 8.99%, respectively. The method exhibited advantages of small total reaction volume (60 μL), short running time (2 min), high sensitivity (lowest limit of quantification of 0.02 μM for inosine), and low cost (small enzyme consumption of 0.007 unit mL^-1 for ADA and substrate of 3.74 μM for AD in individual inhibition), and no matrix effects (101.64%-107.12%). Stability results showed that all analytes were stable under the investigated conditions. The developed method was successfully applied to the detection of the inhibitory activity of ADA from traditional Chinese medicines.

Influence of Adalimumab on the Expression Profile of Genes Associated with the Histaminergic System in the Skin Fibroblasts In Vitro

Objective

The aim of this study was to evaluate the influence of adalimumab on expression profile of genes associated with the histaminergic system in Normal Human Dermal Fibroblast (NHDF) cells stimulated with 8.00 μg/ml of adalimumab and the identification of miRNAs regulating these genes' expression.

Methods

NHDFs were cultured with or without the presence of adalimumab for 2, 8, and 24 hours. The expression profile of genes and miRNA were determined with the use of microarray technology.

Results

Among 22283 ID mRNA, 65 are associated with the histaminergic system. It can be observed that 15 mRNAs differentiate NHDFs cultures with adalimumab form control. The analysis of miRNAs showed that, among 1105 ID miRNA, 20 miRNAs are differentiating in cells treated with adalimumab for 2 hours, 9 miRNA after 8 hours, and only 3 miRNAs after 24 hours.

Conclusion

It was also determined that miRNAs play certain role in the regulation of the expression of genes associated with the histaminergic system. The results of this study confirmed the possibility of using both genes associated with this system as well as miRNAs regulating their expression, as complementary molecular markers of sensitivity to the adalimumab treatment.