Enzyme activity in dried blood spot as a diagnostic tool for adenosine deaminase 2 deficiency

BACKGROUND

Deficiency of adenosine deaminase 2 (DADA2) is an autoinflammatory disease caused by mutations in the adenosine deaminase 2 (ADA2) gene. Loss of functional ADA2 activity results in vasculitis syndrome, immunodeficiency, and hematopoietic disorders. Early diagnosis is required for effective treatment.

METHODS

We developed a dried blood spot (DBS)-based ADA2 activity colorimetric assay. Heparin-affinity purification was used during sample preparation to improve the assay more efficiently. The stability of ADA2 during DBS storage and ADA2 activity of DADA2 patients and healthy controls were examined.

RESULTS

Active ADA2 was extracted from the DBS of healthy controls. ADA2 activity in DBS, stored either frozen or refrigerated, remained stable for at least 90 days. A significant difference in ADA2 activity was observed between healthy controls and patients. No ADA2 activity was detected in DBS from patients.

CONCLUSIONS

Our new DBS ADA2 activity assay is experimentally simple, highly adaptable, and requires no special equipment except for a microplate reader. A low background was achieved with heparin-affinity purification. The method differentiates clearly between healthy controls and patients. ADA2 activity can be reliably measured in DBS, providing an opportunity to diagnose DADA2 at an early stage.

Maternal circulating levels of some metabolic syndrome biomarkers in gestational diabetes mellitus

The aims of the present study were to explore serum levels of lipid profile, atherogenic indexes LDL-C/HDL-C, TG/HDL-C, and TC/HDL-C, bilirubin, adiponectin, pseudocholinesterase, activities of gamma-glutamyltransferase (GGT), adenosine deaminase (ADA), and α-amylase, insulin resistance using homeostasis model assessment of insulin resistance (HOMA-IR) formula, and assessment of correlations between them in gestational diabetes mellitus (GDM) compared with normal pregnancy. A cross-sectional study was designed. The patients consisted of 30 women with GDM. The normal group consisted of 30 healthy pregnant women. The Mann-Whitney U test and Spearman's correlation analysis were used for statistical analysis. A p value less than 0.05 was considered significant. Serum activities of enzymes GGT (p = 0.001) and ADA (p = 0.02) were significantly higher in GDM compared with normal pregnancy, while pseudocholinesterase were significantly decreased (p = 0.02). However, activity of enzyme α-amylase did not show significant difference between two groups (p = 0.75). Serum levels of both HDL-C and adiponectin were significantly decreased in GDM group (p = 0.001). The atherogenic indexes and the HOMA-IR index were significantly higher in GDM (p = 0.001). Serum activity of ADA showed positive correlation with total cholesterol (TC) (r = 0.46, p = 0.01) and CRP (r = 0.66, p = 0.001) in GDM group. Serum levels of total bilirubin correlated negatively with both ADA (r = -0.38, p = 0.04) and triglyceride (r = -0.45, p = 0.01) in women with GDM. Serum activity of GGT correlated positively with LDL-C (r = 0.48, p = 0.01) and TC (r = 0.52, p = 0.003) in GDM group. Increased atherogenic indexes, ADA, GGT, and decreased pseudocholinesterase might be risk factors for GDM.

Protective effect of gallic acid and Syzygium cumini extract against oxidative stress-induced cellular injury in human lymphocytes

CONTEXT

Syzygium cumini (Myrtaceae) presents antioxidant, anti-inflammatory, hypoglycemic and antibacterial effects; however, the cellular and molecular mechanisms of action in the immune system are not yet completely elucidated.

OBJECTIVE

This study evaluates the in vitro effect of gallic acid and aqueous S. cumini leaf extract (ASc) on adenosine deaminase (ADA) and dipeptidyl peptidase IV (DPP-IV) activities, cell viability and oxidative stress parameters in lymphocytes exposed to 2, 2'-azobis-2-amidinopropane dihydrochloride (AAPH).

MATERIALS AND METHODS

Lymphocytes were incubated with ASc (100 and 500 µg/ml) and gallic acid (50 and 200 µM) at 37 °C for 30 min followed by incubation with AAPH (1 mM) at 37 °C for 2 h. After the incubation time, the lymphocytes were used for determinations of ADA, DPP-IV and lactate dehydrogenase (LDH) activities, lipid peroxidation, protein thiol (P-SH) group levels and cellular viability by colorimetric methods.

RESULTS

(i) HPLC fingerprinting of ASc revealed the presence of catechin, epicatechin, rutin, quercitrin, isoquercitrin, quercetin, kaempferol and chlorogenic, caffeic, gallic and ellagic acids; (ii) for the first time, ASc reduced the AAPH-induced increase in ADA activity, but no effect was observed on DPP-IV activity; (iii) ASc increased P-SH groups and cellular viability and decreased LDH activity, but was not able to reduce the AAPH-induced lipid peroxidation; (iv) gallic acid showed less protective effects than ASc.

DISCUSSION AND CONCLUSION

ASc affects the purinergic system and may modulate adenosine levels, indicating that the extract of this plant exhibits immunomodulatory properties. ASc also may potentially prevent the cellular injury induced by oxidative stress, highlighting its cytoprotective effects.

Inhibition of adenosine deaminase (ADA)-mediated metabolism of cordycepin by natural substances

Cordycepin, which is an analogue of a nucleoside adenosine, exhibits a wide variety of pharmacological activities including anticancer effects. In this study, ADA1- and ADA2-expressing HEK293 cells were established to determine the major ADA isoform responsible for the deamination of cordycepin. While the metabolic rate of cordycepin deamination was similar between ADA2-expressing and Mock cells, extensive metabolism of cordycepin was observed in the ADA1-expressing cells with K_m and V_max values of 54.9 μmol/L and 45.8 nmole/min/mg protein. Among five natural substances tested in this study (kaempferol, quercetin, myricetin, naringenin, and naringin), naringin strongly inhibited the deamination of cordycepin with K_i values of 58.8 μmol/L in mouse erythrocytes and 168.3 μmol/L in human erythrocytes. A treatment of Jurkat cells with a combination of cordycepin and naringin showed significant cytotoxicity. Our in silico study suggests that not only small molecules such as adenosine derivatives but also bulky molecules like naringin can be a potent ADA1 inhibitor for the clinical usage.