Diagnostic Value of the Aminopeptidase N, N-Acetyl-β-D-Glucosaminidase and Dipeptidylpeptidase IV in Evaluating Tubular Dysfunction in Patients with Glomerulopathies

Figures & data

Table 1 Baseline anthropometric and biochemical characteristics

	Membranous nephropathy	IgA nephropathy	Lupus nephropathy	Diabetic nephropathy	Control group
N (M:F)	10 (6:4)	38 (24:14)	29 (4:25)	51 (28:23)	50 (25:25)
Age (years)	59.6 ± 7.4^†	51.6 ± 12.2	43.0 ± 10.5	56.4 ± 12.5^†	47.7 ± 11.6
Hgb (g/dl)	12.33 ± 2.07^†	12.81 ± 2.20^‡	11.13 ± 1.65	11.16 ± 1.95^‡	13.99 ± 1.06
WBC (×10^9/mL)	6.81 ± 2.11	6.81 ± 2.02	5.15 ± 1.66^‡	7.39 ± 2.08^‡	5.97 ± 1.34
Creatinine (μmol/L)	122.93 ± 92.57^‡	202.63 ± 184.21	107.45 ± 64.51^†	319.37 ± 295.36	74.04 ± 11.47
CCr (mL/min)	70.33 ± 31.27^†	66.25 ± 37.39	75.30 ± 21.58	33.86 ± 16.72	109.90 ± 16.41
TP (g/L)	59.28±10.32	70.17 ± 8.80	68.95 ± 6.53^†	67.36 ± 7.91^†	74.43 ± 4.88
Albumin (g/L)	34.70 ± 8.30^†	41.56 ± 5.02	40.55 ± 3.82	39.80 ± 5.38^‡	41.85 ± 3.87
TC (mmol/L)	8.23 ± 3.07	6.72 ± 1.96	5.45 ± 1.27	5.62 ± 1.39	5.87 ± 0.96
TG (mmol/L)	2.61 ± 1.09^‡	2.85 ± 1.88^†	1.97 ± 1.19	2.25 ± 1.02^†	1.67 ± 1.12
Glycemia (mmol/L)	5.09 ± 0.57^‡	4.93 ± 0.58	4.33 ± 0.69	10.48 ± 4.32	5.48 ± 0.45
CRP (mg/dL)	5.43 ± 1.07	3.18 ± 2.03	4.27 ± 3.35	5.16 ± 3.68	1.43 ± 1.01
Fibrinogen (g/L)	4.77 ± 2.61	4.24 ± 1.09	5.13 ± 1.89^‡	5.15 ± 2.51^‡	3.91 ± 1.22

Results are given as means ± SD.

*p < 0.001 vs. control group.

^†p < 0.01 vs. control group.

^‡p < 0.05 vs. control group.

Abbreviations: N (M:F) = number (male:female), Hgb = hemoglobin, WBC = white blood cells, CCr = creatinine clearence, TP = total proteins, TC = total cholesterol, TG = triglycerides, CRP = C reactive protein.

Table 2 Serum and urinary enzyme activities

	Membranous nephropathy	IgA nephropathy	Lupus nephropathy	Diabetic nephropathy	Control group
PC-1
Serum (U/L)	4.75 ± 1.09^†	4.60 ± 1.06^†	3.86 ± 0.78	3.61 ± 1.05	3.94 ± 0.68
Urine (U/mmol creatinine)	0.02 (0.002–0.212)	0.04^B (0.003–0.154)	0.01 (0.002–0.217)	0.018 (0.001–0.007)	0.01 (0.001–0.084)
APN
Serum (U/L)	25.58 ± 4.38^†	22.09 ± 5.72	20.55 ± 3.83	20.23 ± 8.21	21.73 ± 4.14
Urine (U/mmol creatinine)	0.14 (0.05–0.71)	0.07 (0.04–0.28)	0.09 (0.05–0.41)	0.20 (0.05–1.40)	0.09 (0.04–0.33)
NAGA
Serum (U/L)	NA	NA	NA	NA	NA
Urine (U/mmol creatinine)	1.14 (0.31–3.80)	0.58 (0.02–2.14)	0.40 (0.10–1.83)	0.47 (0.03–2.29)	0.34 (0.18–1.10)
DPP IV
Serum (U/L)	17.26 ± 6.15	18.97 ± 4.60^†	NA	14.29 ± 4.00	16.17 ± 2.25
Urine (U/mmol creatinine)	0.20 (0.05–0.32)	0.17 (0.05–0.65)	NA	0.31 (0.05–1.64)	0.18 (0.05–0.63)

Results for serum enzyme activities are given as means ± SD, while results for urinary enzyme activities are given as medians with range in parentheses.

*p < 0.01 vs. control group.

^†p < 0.05 vs. control group.

Abbreviations: PC-1 = plasma cell glycoprotein 1, APN = aminopeptidase N, NAGA = N-acetyl-β-D-glucosaminidase, DPP IV = dipeptidylpeptidase IV, NA = not applicable.

Table 3 Lymphocyte ectoenzyme activities

	Membranous nephropathy	IgA nephropathy	Lupus nephropathy	Controlgroup
PC-1 (nmol/min/10^6 ly)
Unstimulated	12.70 (10.30–20.30)	11.95 (9.85–28.00)	11.45 (8.44–19.30)	11.60 (9.38–18.00)
ConA-stimulated	12.30 (10.20–20.10)	11.95 (9.65–17.90)	12.60 (7.57–18.30)	12.70 (9.12–17.50)
PWM-stimulated	12.10 (9.98–18.30)	12.20 (8.64–18.70)	10.95 (8.50–16.50)	12.00 (8.98–18.20)
APN (nmol/min/10^6 ly)
Unstimulated	72.15 (42.30–93.30)	66.20 (39.50–117.70)	71.30 (45.80–160.00)	70.40 (42.60–105.30)
ConA-stimulated	49.75 (34.10–62.30)	50.70 (37.70–65.80)	57.90 (30.50–114.20)	54.80 (39.30–82.80)
PWM-stimulated	40.15 (27.30–51.50)	37.45 (28.90–46.80)	40.40 (27.30–60.00)	39.80 (26.50–55.60)

Results are given as medians with range in parentheses.

Abbreviations: PC-1 = plasma cell glycoprotein 1, APN = aminopeptidase N, ConA = concanavalin A, PWM = pokeweed mitogen.

Table 4 Correlation of serum and urine enzyme activities with proteinuria and creatinine clearance

	P	R
Membranous nephropathy
Prot. 24h, PC-1 serum	< 0.01	0.77
Prot. 24h, NAGA urine	< 0.01	0.82
CCr – DPP IV urine	< 0.05	0.71
IgA nephropathy
Prot. 24h, NAGA urine	< 0.01	0.41
CCr, APN urine	< 0.01	0.75
CCr, DPP IV urine	< 0.01	0.71
Lupus nephritis
Prot. 24h, NAGA urine	< 0.001	0.67
Prot. 24h, PC-1 urine	< 0.01	0.55
CCr, APN serum	< 0.05	0.65
CCr, NAGA urine	< 0.05	0.43
CCr, APN (ConA-stimulated Ly)	< 0.05	0.64
CCr, APN ((PWM-stimulated Ly)	< 0.05	0.54
C3, APN (ConA-stimulated Ly)	< 0.05	0.55
C3, APN (PWM-stimulated Ly)	< 0.05	0.59
C3, APN serum	< 0.05	0.63
Diabetic nephropathy
CCr, PC-1 urine	< 0.01	0.39

Abbreviations: PC-1 = plasma cell glycoprotein 1, APN = aminopeptidase N, NAGA = N-acetyl-β-D-glucosaminidase, DPP IV = dipeptidylpeptidase IV, ConA = concanavalin A, PWM = pokeweed mitogen, Prot. 24h = 24h proteinuria, CCr = creatinine clearance.

Table 5 Anthropometric and biochemical characteristics in patients with type 1 DM and type 2 DM with microalbuminuria and macroalbuminuria

	DM type 1 with microalbuminuria (n = 9)	DM type 2 with microalbuminuria (n = 11)	DM type 2 with macroalbuminuria (n = 31)
N (M:F)	4:5	10:1	14:17
Age (years)	40.1 ± 13.8^‡	57.6 ± 10.3	60.6 ± 8.6
Hgb (g/dL)	13.53 ± 2.34^§	14.49 ± 1.02^‡	11.72 ± 1.99
WBC (×10^9/mL)	5.66 ± 1.76	6.65 ± 1.50	7.19 ± 2.09
Creatinine (μmol/L)	81.56 ± 17.11^‡	92.82 ± 19.09^‡	214.1 ± 174.1
CCr (mL/min)	93.56 ± 23.04^‡	111.11 ± 40.09^‡	43.50 ± 24.01
TP (g/L)	72.87 ± 12.11	74.92 ± 3.99	70.74 ± 8.22
Albumin (g/L)	39.20 ± 8.13	41.04 ± 2.92	39.54 ± 5.19
TC (mmol/L)	4.95 ± 1.01^†	5.88 ± 0.82	5.73 ± 1.59
TG (mmol/L)	1.69 ± 0.82	2.89 ± 0.85^││	2.19 ± 1.03
Glycemia (mmol/L)	15.16 ± 6.15^§	10.11 ± 1.73	9.25 ± 3.44
CRP (mg/dL)	4.77 ± 0.97	4.66 ± 1.69	5.47 ± 4.66
Fibrinogen (g/L)	3.72 ± 0.77	4.59 ± 1.22	5.76 ± 2.96

Results are given as means ± SD.

*p < 0.01 vs. DM type 2 with microalbuminuria.

^†p < 0.05 vs. DM type 2 with microalbuminuria.

^‡p < 0.001 vs. DM type 2 with macroalbuminuria.

^§p < 0.01 vs. DM type 2 with macroalbuminuria.

^││p < 0.05 vs. DM type 2 with macroalbuminuria.

Abbreviations: N (M:F) = number (male:female), Hgb = hemoglobin, WBC = white blood cells, CCr = creatinine clearance; TP = total protein, TC = total cholesterol, TG = triglycerides, CRP = C reactive protein.

Table 6 Serum and urinary enzyme activities in patients with type 1 DM and type 2 DM with microalbuminuria and macroalbuminuria

	DM type 1 (n = 9)	DM type 2 with microalbuminuria (n = 11)	DM type 2 with macroalbuminuria (n = 31)	Control group (n = 50)
PC-1
Serum (U/L)	3.38 ± 0.80	3.65 ± 1.18	3.37 ± 1.04	3.94 ± 0.68
Urine (U/mmol Cr)	0.018 (0.012–0.050)	0.03 (0.001–0.080)	0.01 (0.001–0.039)	0.01 (0.001–0.084)
APN
Serum (U/L)	21.00 ± 5.98	18.91 ± 11.84	18.18 ± 6.99^†	22.27 ± 4.14
Urine (U/mmol Cr)	0.30 (0.09–0.51)	0.35 (0.07–1.40)	0.16 (0.05–0.66)	0.09 (0.04–0.33)
NAGA
Serum (U/L)	NA	NA	NA	NA
Urine (U/mmol Cr)	0.42 (0.13–0.92)	0.72 (0.06–2.29)	0.42 (0.03–0.71)	0.34 (0.18–1.10)
DPP IV
Serum (U/L)	12.78 ± 4.12^†	12.18 ± 6.22^†	15.16 ± 2.96	16.39 ± 2.25
Urine (U/mmol Cr)	0.42 (0.13–0.75)	0.50 (0.07–1.64)^†	0.21 (0.05–0.66)	0.18 (0.05–0.63)

Results for serum enzyme activities are given as means ± SD, while results for urinary enzyme activities are given as medians with range in parentheses.

*p < 0.01 vs. control group.

^†p < 0.05 vs. control group.