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.

Detailed analysis of Japanese patients with adenosine deaminase 2 deficiency reveals characteristic elevation of type II interferon signature and STAT1 hyperactivation

BACKGROUND

Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive inflammatory disease caused by loss-of-function mutations in both alleles of the ADA2 gene. Most patients with DADA2 exhibit systemic vasculopathy consistent with polyarteritis nodosa, but large phenotypic variability has been reported, and the pathogenesis of DADA2 remains unclear.

OBJECTIVES

This study sought to assess the clinical and genetic characteristics of Japanese patients with DADA2 and to gain insight into the pathogenesis of DADA2 by multi-omics analysis.

METHODS

Clinical and genetic data were collected from 8 Japanese patients with DADA2 diagnosed between 2016 and 2019. ADA2 variants in this cohort were functionally analyzed by in vitro overexpression analysis. PBMCs from 4 patients with DADA2 were subjected to transcriptome and proteome analyses. Patient samples were collected before and after introduction of anti- TNF-α therapies. Transcriptome data were compared with those of normal controls and patients with other autoinflammatory diseases.

RESULTS

Five novel ADA2 variants were identified in these 8 patients and were confirmed pathogenic by in vitro analysis. Anti-TNF-α therapy controlled inflammation in all 8 patients. Transcriptome and proteome analyses showed that upregulation of type II interferon signaling was characteristic of DADA2. Network analysis identified STAT1 as a key regulator and a hub molecule in DADA2 pathogenesis, a finding supported by the hyperactivation of STAT1 in patients' monocytes and B cells after IFN-γ stimulation.

CONCLUSIONS

Type II interferon signaling and STAT1 are associated with the pathogenesis of DADA2.

Aging-associated latent herpes viral infection in normal Japanese individuals and patients with Werner syndrome

A series of our "inflammageing" study examining serum samples from a maximum of 217 healthy Japanese individuals aged between 1 and 100 years and mutation-proven 40 patients with Werner syndrome (WS) indicated normal aging-associated elevations of highly sensitive CRP (hsCRP) and matrix metalloproteinase-9 (MMP-9). To further study the contribution of environmental factors such as persistent herpes viral infection to inflammageing, IgG antibodies against varicella/zoster virus (VZV) and cytomegalovirus (CMV) were examined in the same serum samples as has been done for hsCRP and MMP-9 analyses. The mean levels of serum IgG viral antibodies were comparable between normal (mean ± SE: 31.0 ± 4.3 unit) and WS (38.6 ± 7.6) for CMV, and between normal (42.0 ± 12.2) and WS (29.8 ± 3.8) for VZV, respectively. Significant associations of aging with IgG anti-CMV antibody were in normal aging (p = 0.023) and WS (p = 0.037), but not with IgG VZV in both conditions. Aging-associated change of IgG anti-CMV antibody titer in WS increased significantly (1.32 times higher) compared with normal aging (p = 0.037). IgG anti-CMV level was significantly elevated in the male gender than female in both conditions (p = 0.006). Elevated hsCRP level was significantly associated with IgG anti-CMV (p = 0.016) and IgG anti-VZV (p = 0.008) antibodies in normal aging, but not in WS. Serum MMP-9 was significantly associated with IgG anti-CMV level (p = 0.0002) in normal aging, but not in WS. Persistent herpes viral infection may constitute a part of "inflammageing" in normal aging and WS.

MMP-9/ANC score as a predictive biomarker for efficacy of bevacizumab plus platinum doublet chemotherapy in patients with advanced or recurrent non-squamous non-small cell lung cancer

BACKGROUND

Bevacizumab is a recombinant humanized monoclonal antibody against vascular endothelial growth factor (VEGF), which is a key regulator of tumor angiogenesis.

OBJECTIVE

To evaluate biomarkers to predict the benefit of paclitaxel and carboplatin plus bevacizumab (PCB) therapy in patients with advanced or recurrent non-squamous non-small cell lung cancer.

METHODS

Among 21 patients treated with PCB, 10 were included in the good responder group and 11 in the non-responder group. Serum VEGF, MMP-2 and MMP-9 were measured using ELISA.

RESULTS

There were no significant differences in these markers levels between groups. However, the good responder group showed a significantly higher pre-treatment MMP-9/ absolute neutrophil count (ANC) score than the non-responder group before the treatment (p= 0.014), and there was a positive correlation between the score and the tumor reduction rate (r= 0.57, p= 0.016). Furthermore, by dividing patients into a high scoring group (MMP-9/ANC ≥ median, n= 11) and a low scoring group (MMP-9/ANC < median, n= 10), former group showed a significant improvement in the median progression-free survival compared with latter group (636 vs. 196 days, p = 0.032).

CONCLUSIONS

MMP-9/ANC score before PCB treatment may be a suitable biomarker to assess the anti-tumor effects of PCB therapy.

Inflammageing assessed by MMP9 in normal Japanese individuals and the patients with Werner syndrome

Age-associated minor inflammation: inflammageing may explain human ageing mechanism(s). Our previous study reported a significant increase in the serum level of highly sensitive C-reactive protein (hsCRP) with normal ageing and the patients with Werner syndrome (WS). To further study the minor inflammatory condition associated with ageing, another possible ageing biomarker: matrix metalloproteinase-9 (MMP9) was examined in the sera from 217 normal Japanese individuals aged between 1 and 100 years and 41 mutation-proven Japanese WS aged between 32 and 70 years. MMP9 was assayed by ELISA. The serum level of MMP9 was elevated significantly (p < 0.001) with normal ageing from both sexes as hsCRP. In contrast to normal ageing, the serum MMP9 level in WS decreased significantly with calendar age (p < 0.05). The MMP9 level (ng/mL) in WS (147.2 ± 28.5) was not significantly different in comparison with those from age-matched normal adult population aged between 25 and 70 years (109.1 ± 9.4), nor normal elderly population aged between 71 and 100 years (179.9 ± 16.1). Although both normal ageing and WS were associated with minor inflammation, the inflammatory parameters such as serum MMP9 and hsCRP changed differently between normal ageing and WS. The WS-specific chronic inflammation including skin ulcer and diabetes mellitus may contribute the different behavior of both ageing biomarkers from normal ageing.

Multiplex cytokine analysis of Werner syndrome

We reported a minor inflammation-driven ageing (inflammageing) assessed by highly sensitive CRP (hsCRP) in normal individuals and patients with Werner syndrome (WS), followed by an ageing associated Th2-biased cytokine change in normal ageing in the previous papers. To further study the association of hsCRP and 26 cytokines/chemokines in 35 WS patients, a multiple cytokine array system was used in the same serum samples as were examined for hsCRP. The serum levels of Th2 cytokines (IL-4, IL-6, IL-10, and GM-CSF), Th1 products (IL-2, TNFα, IL-12, and IFNγ) and monocyte/macrophage products (MCP-1, basic FGF and G-CSF) in WS were significantly elevated compared with normal ageing. Elevated hsCRP level in WS was significantly correlated with IL-6, IL-12 and VEGF levels, if age and sex were taken into account. A pro-inflammatory cytokine/chemokine circuit-stimulated immunological shift to Th2 in WS was similar to normal ageing. These cytokine/chemokine changes may induce a systemic chronic inflammation monitored by hsCRP, though these immunological changes in WS were more complicated than normal ageing, possibly due to the WS-specific chronic inflammation such as skin ulcer, diabetes mellitus and central obesity with visceral fat deposition. Further study may warrant the pathophysiology of Th2 shift and Th2-biased inflammageing in normal ageing and WS.

Ageing in Werner syndrome

Oxidative stress markers including pentosidine and homocysteine were examined comparing them with inflammation markers including highly sensitive C-reactive protein (hsCRP) and matrix metalloproteinase-9 (MMP-9) in serum from patients with Werner syndrome (WS) and healthy individuals. Elevation of serum pentosidine correlated significantly with normal aging in healthy individuals (p < 0.0004). Serum pentosidine in WS increased significantly compared with age-matched healthy individuals (p < 0.05). Serum homocysteine levels increased insignificantly with normal aging in healthy individuals and in WS compared with age-matched healthy individuals. As both pentosidine and homocysteine levels did not correlate with hsCRP or MMP-9, both oxidative stress markers may be differentially regulated by inflammation.

Aging-associated inflammation in healthy Japanese individuals and patients with Werner syndrome

Minor inflammation-driven aging (inflammaging) has been proposed to explain human aging mechanism. To study the inflammatory condition associated with normal human aging, highly sensitive CRP (hsCRP) was examined in the sera collected from 217 healthy Japanese individuals aged between 1 and 100years and 41 mutation-proven Japanese Werner syndrome (WS) patients. The serum hsCRP was assayed by ELISA. The serum hsCRP level increased significantly (p<0.001) with normal aging from both sexes. The serum hsCRP was significantly elevated in WS (mean±SE: 11.0±1.6μg/ml) compared with age-matched normal population (1.3±0.3μg/ml, p<0.001) and normal elderly population ages between 71 and 100years (4.2±0.7μg/ml, p<0.001). Both normal aging and WS were associated with minor inflammation that can be evaluated by serum hsCRP. WS may be a good candidate to study inflammaging.

Human plasma adenosine deaminase 2 is secreted by activated monocytes

Adenosine deaminase (ADA) plays an important role in the immune system, and its activity is composed of two kinetically distinct isozymes, ADA1 and ADA2. ADA2 is a major component of human plasma total ADA activity and ADA2 activity is significantly elevated in patients with various diseases such as HIV infection and chronic hepatitis. However, relatively little is known about ADA2 because of difficulties in purifying this enzyme. In this study we succeeded in purifying human plasma ADA2 and demonstrate the extracellular secretion of ADA2 from human peripheral blood monocytes stimulated with phorbol 12-myristate 13-acetate and calcium ionophore.

The Examination of Rheumatoid Factor and Other Serum Markers in Rheumatoid Arthritis

Rheumatoid factor (IgM-RF) has been widely used to diagnose rheumatoid arthritis (RA) in clinical practice. We investigated the RA diagnostic performances of anti-cyclic citrullinated peptide antibody (anti-CCP), matrix metalloproteinase-3 (MMP-3), anti-agalactosyl IgG antibody (CA*RF), and anti-calpastatin antibody (ACA) in comparison with IgM-RF. Among 68 RA patients, IgM-RF was positive in 31 (45.6%) and negative in 37 (54.4%). In the IgM-RF-positive group, positivity in anti-CCP, CA*RF, and ACA was 97%, 100%, and 97%, respectively, although that in MMP-3 (74%) was inferior to the others. On the other hand, in the IgM-RF-negative group, positivity in anti-CCP, MMP-3, and ACA was 73%, 81%, and 86%, respectively, although that in CA*RF was only 59%. We conclude that the combination of IgM-RF and anti-CCP/ACA will provide an accurate diagnosis of RA in clinical practice.

Adenosine deaminase 2 from chicken liver: purification, characterization, and N-terminal amino acid sequence

Adenosine deaminase (ADA) is involved in purine metabolism and plays an important role in the mechanism of the immune system. ADA activity is composed of two kinetically distinct isozymes, which are referred to as ADA1 and ADA2. ADA1 is widely distributed in many animals and well characterized. On the contrary, relatively little is known about ADA2. In this study, we first purified ADA2 to homogeneity from chicken liver. The purified enzyme had a molecular mass of approximately 110 kDa on gel filtration. Also, the enzyme was shown to be a homodimer with an estimated molecular mass of 61 kDa on SDS-PAGE. Following treatment with N-glycosidase, the molecular mass of ADA2 changed to 55 kDa. Several properties of the highly purified ADA2 were also investigated in this study. Furthermore, the N-terminal amino acid sequence of ADA2 was determined.

High diagnostic value of anticalpastatin autoantibodies in rheumatoid arthritis detected by ELISA using human erythrocyte calpastatin as antigen

OBJECTIVE

To develop a quantitative method of measuring autoantibodies against human calpastatin in rheumatoid arthritis (RA) and to determine their diagnostic value compared with other autoimmune and articular diseases.

METHODS

We performed a highly sensitive ELISA for IgG and IgM anticalpastatin autoantibodies in human sera using human erythrocyte calpastatin as an antigen. Samples were diluted 1:2000 for the measurement of IgG and 1:400 for IgM.

RESULTS

IgG anticalpastatin antibodies were found in the sera of 48 of 58 patients (82.8%) with RA. In contrast, IgG anticalpastatin antibodies were found in the sera of only 2 of 11 (8.3%) patients with osteoarthritis (OA). Compared to sera from patients with other autoimmune diseases, anticalpastatin antibody sensitivity for RA was better than that of systemic lupus erythematosus (5.6%), systemic sclerosis (0%), mixed connective tissue disease (0%), and Sjögren's syndrome (20%). IgG anticalpastatin antibodies also showed high specificity (96.1%) for RA. Almost 90% of patients with RA were positive for IgG or IgM anticalpastatin antibodies.

CONCLUSION

We have developed a simple, sensitive, specific, and quantitative ELISA for anticalpastatin antibodies that may have a high diagnostic value for RA.

Characterization and purification of adenosine deaminase 1 from human and chicken liver

Adenosine deaminase 1 (ADA1) was purified from human and chicken liver. The purified enzyme had a molecular weight of approximately 42,000 Da on SDS-PAGE. In humans, ADA1 was mainly purified concomitant with ADA-binding protein, dipeptidyl peptidase IV (DPP IV)/CD26; however, in chickens, only ADA1 without DPP IV was purified. Both human and chicken ADA1s showed similar properties on substrate specificities, sensitivities on inhibitors, and pH profile. However, they had different affinities with adenosine-Sepharose and IgG anti-ADA1-Sepharose. Human ADA1 was not adsorbed in adenosine-Sepharose column, but chicken ADA1 was adsorbed. As for IgG anti-ADA1-Sepharose column, the results were converse. Furthermore, human ADA1 could bind to DPP IV whereas chicken ADA1 could not.

Induction of a novel gelatinolytic activity in synovial tissue of patients with rheumatoid arthritis

Gelatinolytic activity induced by longtime incubation at 37 degrees C was found in extracts of rheumatoid synovial tissues. The enzyme activity was assessed by gelatin zymography and 3H-gelatin degradation assay. The observed enzyme had different characteristics from matrix metalloproteinases; it did not require metal ions for activity. However, metallocheltors blocked activation and addition of some metal ions restored the activation. The molecular size of the enzyme was changed time-dependently. The approximate molecular weight of the first enzyme produced by incubation was 65 kDa and it was converted to a broad size molecule with a molecular weight of 50 kDa after further incubation. Substrate specificity was detected for denatured collagen types I, II, III and IV.

Correlations between matrix metalloproteinase-9 and adenosine deaminase isozymes in synovial fluid from patients with rheumatoid arthritis

OBJECTIVE

To clarify the significance of increased adenosine deaminase (ADA) isozyme activities in synovial fluid (SF) from patients with rheumatoid arthritis (RA).

METHODS

ADA isozyme activities were measured using colorimetric assays. Concentrations of matrix metalloproteinase-9 (MMP-9) were measured by ELISA.

RESULTS

Levels of ADA isozyme activities in RA SF were significantly higher than those from patients with osteoarthritis and patients with traumatic injuries. Significant positive correlations between MMP-9 concentration and ADA activities were observed in RA SF (MMP-9 vs total ADA: r = 0.880; vs ADA1: r = 0.829; vs ADA2: r = 0.823; p < 0.001).

CONCLUSION

Elevated levels of ADA activities were found in SF from patients with RA. There were significant positive correlations between MMP-9 and ADA isozymes. These results may reflect the inflammatory condition of patients with RA.

Dipeptidyl peptidase IV from human serum: purification, characterization, and N-terminal amino acid sequence

Dipeptidyl peptidase IV (DPP IV) in normal human serum was purified 14,400-fold with a 25% yield to homogeneity. The molecular weight of the purified enzyme was approximately 110,000 on SDS-PAGE, almost the same as that of human kidney membrane-bound DPP IV. No difference was found between the two enzymes enzymologically and immunologically, either in substrate specificity, susceptibility to inhibitors, or cross-reactivity with an anti-rat kidney DPP IV antibody, or in their ability to bind adenosine deaminase. However, the N-terminal amino acid sequence of serum DPP IV lacked the transmembrane domain of the membrane-bound enzyme and started at the 39th position, serine, from the N-terminus predicted from the cDNA nucleotide sequence. These results suggest that membrane-bound DPP IV loses its transmembrane domain upon release into the serum, and that its structure on the plasma membrane is not required for its binding to adenosine deaminase.

Aminopeptidase N in sera of healthy subjects is a different N-terminal processed derivative from the one obtained from maternal serum

A major aminopeptidase present in normal human serum was purified to homogeneity as a 150-kDa molecular species. Western blotting confirmed the binding of an anti-aminopeptidase N antibody to the protein. The N-terminal amino acid sequence of the enzyme was determined. The first 13 amino acids of the enzyme completely matched amino acids 59-71 of the sequence predicted from the human intestinal aminopeptidase N cDNA nucleotide sequence. As reported previously, aminopeptidase N from maternal serum had 68 fewer amino acid residues at the N-terminus than the enzyme obtained from detergent-solubilized membranes. The results indicate that aminopeptidase N in normal serum is a different N-terminal processed derivative from that obtained from maternal serum.

Comparison of the abilities of proteins from Bartonella bacilliformis and Bartonella henselae to deform red cell membranes and to bind to red cell ghost proteins

Infections in humans by Bartonella bacilliformis, but not Bartonella henselae, are characterized by invasion of red cells. Supernatants of culture medium from B. bacilliformis and B. henselae each contain a protein which causes invagination of membranes of human red cells and formation of intracellular vacuoles. These two proteins are very similar in molecular mass, heat stability and mechanism of action. B. henselae does not bind to human red cells, but human red cell ghost membrane proteins were recognized by both bacteria, five by B. bacilliformis and the same five, and one additional protein by B. henselae. Two of these proteins had molecular masses consistent with actin and spectrin. Actin binds to five electroblotted outer membrane proteins from B. henselae and four of these proteins are retained on an actin-Sepharose column.

CD26/dipeptidyl peptidase IV does not work as an adenosine deaminase-binding protein in rat cells

In this paper, we describe further characterization of the membrane-associated molecule CD26/dipeptidyl peptidase IV (DPP IV), which is said to be adenosine deaminase-binding protein (ADA-bp) in humans, to clarify its association with ADA in rat immune cells. For this purpose, we used three types of rats: DPP IV+ rats; DPP IV- rats, which lack enzyme activity and immunological reactivity of DPP IV; and ADA- rats, which have reduced ADA activity due to continuous peritoneal injection of 2'-DCF, a potent inhibitor of ADA. ADA existed in the cells of DPP IV+ and DPP IV- rats, but it did not exist on the cell surface in either rat. ADA- rats showed a decrease in ADA activity and in the number of immune cells, but no effect on DPP IV was observed. These data suggest that in rats, in contrast to humans, DPP IV does not exist as ADA-bp.

An antibody specific to N-terminal amino acid sequence of human maternal serum cystine aminopeptidase and its applications

An antibody directed against a synthetic peptide corresponding to the N-terminal sequence of human cystine aminopeptidase (CAP) present in maternal serum was prepared. Although the antibody did not immunoprecipitate the activity of CAP, it was useful for purification and immunoblot analysis of CAP protein. An antipeptide antibody-conjugated Sepharose 4B column was very effective in purifying a single CAP protein from partially purified enzyme preparation, and Western blotting confirmed the binding of the antibody to CAP protein.

Is CD26/dipeptidyl peptidase IV a really important molecule in T cell activation of a certain rat strain?

A new monoclonal antibody (MS-7 mAb) was raised to investigate the real role of the membrane-associated molecule CD26/dipeptidyl peptidase IV (DPP IV; EC 3.4.14.5), which transduces activation signals in T cells. A strain of rats which is deficient in DPP IV was used. MS-7 mAb recognized DPP IV (110 kDa) and its 60 kDa fragment, starting at the 281st residue corresponding to the extracellular one comprising the active-site sequence Gly-X-Ser631-X-Gly of DPP IV. MS-7 mAb recognized CD26 on T cells of DPP IV+ rats both before and after mitogen activation. CD26 expression and DPP IV enzyme activity are increased on T cells following their activation; nevertheless, no CD26 was expressed on T cells of DPP IV- rats, and no DPP IV enzyme activity was detected either before or after mitogen activation. In addition, MS-7 mAb inhibited the mitogen-stimulated proliferation of DPP IV+ rats, but did not affect that of DPP IV- rats. These results suggest that CD26/DPP IV is not a necessary molecule in T cell activation, and that there is some other bypass in T cell activation of DPP IV- rats.

Identification of an alanine aminopeptidase in human maternal serum as a membrane-bound aminopeptidase N

In addition to cystine aminopeptidase (oxytocinase) alanine aminopeptidase is present at high levels in the serum of pregnant women. In this study we compared the enzyme with membrane-bound aminopeptidase N purified from human placenta. Comparison of catalytic and immunological properties and N-terminal sequence analyses revealed that the enzymes were differentially processed derivatives of the same protein, and that the N-terminal 68 residues of aminopeptidase N were deleted in the alanine aminopeptidase. The deleted sequence contains a small cytoplasmic region, a hydrophobic transmembrane domain and a junctional domain. These results suggest that the enzyme may be released into the maternal circulation as a result of lacking these three domains.

N-terminal amino acid sequence of the 60-kDa protein of rat kidney dipeptidyl peptidase IV

The N-terminal amino acid sequence of the 60-kDa protein of purified dipeptidyl peptidase IV (DPP IV) was determined. The protein was isolated from rat kidney by detergent solubilization. The first 22 amino acids were sequenced; these matched the predicted sequence between residues 281 and 302 of the amino-terminal region of rat liver DPP IV.

Increased excretion of proline-containing peptides in dipeptidyl peptidase IV-deficient rats

We have reported that a substrain of Fischer 344 rat exhibits a deficiency of dipeptidyl peptidase IV (Watanabe et al. Experientia 43: 400-401, 1987). In this study, this rat model was found to excrete large amounts of proline-containing peptides in the urine. The peptide fraction also contained other amino acids, such as hydroxyproline and glycine. The results indicate that the enzyme might be involved in the metabolism of collagens and related peptides.

Identification of a rat liver dipeptidyl aminopeptidase IV with a liver plasma membrane glycoprotein (gp110). A study using dipeptidyl aminopeptidase IV-deficient rats

A rat liver plasma membrane glycoprotein, gp110, was compared with dipeptidyl aminopeptidase IV (DAP IV) by using Wistar rats (DAP IV-positive rats) and Fischer 344 rats (DAP IV-negative rats). Fischer rats also lacked gp110 and gp110 of Wistar rats had DAP IV activity. Furthermore, we showed that the C-terminal sequence of gp110 was Ser-Leu-Arg, which was the same as the C-terminal amino acid sequence deduced from the nucleotide sequence of the cDNA of DAP IV. According to these results, we concluded that gp110 was identical with DAP IV.