Quantitative urinary proteome analysis reveals potential biomarkers for disease activity of Behcet's disease uveitis.

PURPOSE: Behçet's disease-associated uveitis (BDU) is a severe, recurrent inflammatory condition affecting the eye and is part of a systemic vasculitis with unknown etiology, making biomarker discovery essential for disease management. In this study, we intend to investigate potential urinary biomarkers to monitor the disease activity of BDU. METHODS: Firstly, label-free data-dependent acquisition (DDA) and tandem mass tag (TMT)-labeled quantitative proteomics methods were used to profile the proteomes of urine from active and quiescent BDU patients, respectively. For further exploration, the remaining fifty urine samples were analyzed by a data-independent acquisition (DIA) quantitative proteomics method. RESULTS: Twenty-nine and 21 differential proteins were identified in the same urine from BDU patients by label-free DDA and TMT-labeled analyses, respectively. Seventy-nine differentially expressed proteins (DEPs) were significantly changed in other active BDU urine samples compared to those in quiescent BDU urine samples by IDA analysis. Gene Ontology (GO) and protein-protein interaction (PPI) analyses revealed that the DEPs were associated with multiple functions, including the immune and neutrophil activation responses. Finally, seven proteins were identified as candidate biomarkers for BDU monitoring and recurrence prediction, namely, CD38, KCRB, DPP4, FUCA2, MTPN, S100A8 and S100A9. CONCLUSIONS: Our results showed that urine can be a good source of biomarkers for BDU. These dysregulated proteins provide potential urinary biomarkers for BDU activity monitoring and provide valuable clues for the analysis of the pathogenic mechanisms of BDU.

Urinary Metabolomic Profiling to Identify Potential Biomarkers for the Diagnosis of Behcet's Disease by Gas Chromatography/Time-of-Flight-Mass Spectrometry.

Diagnosing Behcet's disease (BD) is challenging because of the lack of a diagnostic biomarker. The purposes of this study were to investigate distinctive metabolic changes in urine samples of BD patients and to identify urinary metabolic biomarkers for diagnosis of BD using gas chromatography/time-of-flight-mass spectrometry (GC/TOF-MS). Metabolomic profiling of urine samples from 44 BD patients and 41 healthy controls (HC) were assessed using GC/TOF-MS, in conjunction with multivariate statistical analysis. A total of 110 urinary metabolites were identified. The urine metabolite profiles obtained from GC/TOF-MS analysis could distinguish BD patients from the HC group in the discovery set. The parameter values of the orthogonal partial least squared-discrimination analysis (OPLS-DA) model were R²X of 0.231, R²Y of 0.804, and Q² of 0.598. A biomarker panel composed of guanine, pyrrole-2-carboxylate, 3-hydroxypyridine, mannose, l-citrulline, galactonate, isothreonate, sedoheptuloses, hypoxanthine, and gluconic acid lactone were selected and adequately validated as putative biomarkers of BD (sensitivity 96.7%, specificity 93.3%, area under the curve 0.974). OPLS-DA showed clear discrimination of BD and HC groups by a biomarker panel of ten metabolites in the independent set (accuracy 88%). We demonstrated characteristic urinary metabolic profiles and potential urinary metabolite biomarkers that have clinical value in the diagnosis of BD using GC/TOF-MS.

Microalbuminuria as an early marker of renal involvement in Behcet's disease: it is associated with neurological involvement and duration of the disease.

BACKGROUND: Despite its nature as a systemic vasculitis, renal involvement is known to occur infrequently in Behçet's Disease (BD). OBJECTIVES: Our aim was to investigate proteinuria, microhematuria and microalbuminuria in 24-h urine and evaluate subclinical or symptomatic renal involvement in BD patients. METHODS: Two hundred and eleven patients who fulfilled the International Behçet's Disease criteria were included in the study. After urine analysis, five of 12 patients who were found to have proteinuria underwent renal biopsy, while 199 patients without proteinuria were investigated for microalbuminuria (MA). RESULTS: A total of 34 (16.1%) patients were found to have renal involvement including 22 (11.1%) with MA and 12 with proteinuria (5.6%). Renal biopsies resulted as focal glomerulosclerosis in three, membranous glomerulosclerosis in one and secondary amyloidosis in two patients. Neurological involvement was found to be significantly more prevalent in patients with MA (P < 0.01). Neurological involvement and duration of disease (> or = 10 years) was found to increase the risk for MA by 21.75-fold and 5.03-fold, respectively. Though age over 40 years, thrombophlebitis, HLA B51 haplotype and ophthalmological involvement were not found to be significantly associated with MA; these parameters increased the risk for MA. CONCLUSIONS: Renal involvement may be more prevalent in BD than it has been recognized; it usually presents with asymptomatic microhematuria, proteinuria and/or microalbuminuria; therefore clinicians must check 24-h urine for the presence of proteinuria, microhematuria and microalbuminuria; especially in patients who are aged over 40 years, have a longer duration of the disease and multisystem involvement.

Is there any relationship between serum and urine neopterin and serum interferon-gamma levels in the activity of Behcet's disease?

BACKGROUND: Behcet's disease (BD) is a chronic, inflammatory, multisystem vasculitic disorder. There is no reliable laboratory marker that indicates disease activity. Neopterin is an immunological marker of cellular immune activation, which is secreted by monocytes/macrophages as a result of interferon-gamma (IFN-gamma) secretion by activated T lymphocytes. OBJECTIVE: We aimed to investigate serum and urine neopterin levels in BD patients. METHODS: Forty-five patients who were diagnosed according to the criteria of the International Study Group for BD and 45 age- and sex-matched healthy controls were enrolled in the study. Disease activity was considered by clinical findings. Serum and urine neopterin levels and serum IFN-gamma levels were measured. RESULTS: The mean values of serum and urine neopterin levels were 12.68 +/- 4.87 nmol/L and 167.53 +/- 148.73 micromol/mol creatinine, respectively, in BD patients (P = 0.000 and P = 0.008, respectively), which were statistically significantly different from the control group. However, there was no significant statistical difference between serum and urine neopterin levels of the clinically active and inactive patients. It was also found that the mean value of serum IFN-gamma levels was higher in healthy controls than in BD patients (P = 0.000). CONCLUSIONS: We conclude that serum and urinary neopterin measurement can not be used as a reliable laboratory marker as the BD patients' serum and urinary neopterin levels do not increase in the active stage even though these levels increase when compared to healthy controls.

Urinary 8-isoprostaglandin F(2alpha) level in Behçet's disease.

Although its etiology remains unknown, the increased production of reactive oxygen species in Behçet's disease (BD) have been reported. Furthermore, it has been suggested that vascular and endothelial tissue damage seen in BD is related to elevated reactive oxygen species generated by activated neutrophils from BD patients. To investigate the formation of lipid peroxidation in BD patients in vivo, urinary level of 8-isoprostaglandin F(2alpha) was quantitated by enzyme immunoassay after solid phase extraction in different clinical forms of BD patients. There was no difference in urinary level of 8-isoprostaglandin F(2alpha) between BD patient and healthy control group. There was also no difference in urinary levels of 8-isoprostaglandin F(2alpha) in subgroup analyses of BD patients, i.e. in mucocutaneous and vascular type BD patients; active and inactive BD patients. Contrary to the findings in literature, we found no difference in urinary level of 8-isoprostaglandin F(2alpha) between patients with systemic lupus erythematosus and healthy control group. These findings show no increase in lipid peroxidation despite the augmented formation of reactive oxygen species in BD patients. It may be interesting to assess formation of urinary level of 8-isoprostaglandin F(2alpha) in BD patients who do not take any medication.

Mild renal injury in Behçet's disease.

AIM: The aim of this study is to investigate the frequency of microalbuminuria and abnormal urinary beta2-microglobulin excretion in patients with Behçet's disease (BD). MATERIALS AND METHODS: Twenty-eight patients and 27 healthy controls were included in this study. Urine albumin/creatinine and beta2-microglobulin/creatinine ratios were calculated. RESULTS: The frequency of microalbuminuria and abnormal urinary beta2-microglobulin excretion was higher among patients with BD than in control group, but this was not statistically significant (p > 0.05). CONCLUSION: Microalbuminuria and abnormal beta2-microglobulin excretion are markers of renal injury, which have not been investigated in BD previously. Renal injury in BD is more frequent than has been recognized and it is most often in mild nature.

Urinary nitric oxide levels are increased and correlated with plasma concentrations in patients with Behçet's disease: is it a new urinary activity marker?

Nitric oxide (NO) is a free radical and serves many functions within the kidney. Excess NO causes glomerular injury. Behçet's disease (BD) is a systemic immunoinflammatory vasculitis, affecting every organ in the body including the kidneys (subclinic glomerulonephritis). We investigated the role of urinary total nitrite levels (end product of NO) in BD and evaluated whether urinary concentrations were correlated with its plasma levels or disease activity. Thirty-six consecutive Behçet's patients (19 men, 17 women; 35.9 years), and 20 age- and sex-matched healthy control volunteers (12 men, eight women; 33.2 years) were divided into an active (n = 16) and inactive (n = 20) period. Urinary and serum NO levels ( micromol/mg urinary creatinine) were higher in BD patients (4.1 +/- 0.3) than control subjects (1.7 +/- 0.2; P < 0.001). Serum NO levels in Behçet's patients and control subjects were 51.3 +/- 9.8 and 21.7 +/- 7.3 micromol/L, respectively (P < 0.001). Active patients had higher urinary NO excretion (4.9 +/- 0.3) than inactive patients (3.3 +/- 0.3; P < 0.01). Urinary NO levels were correlated with its serum levels (r2 = 0.69, P < 0.001). Higher urinary NO levels found in BD may be produced by the kidney as a result of an inflammatory stimulation. As excess NO is toxic to the tissues, increased NO levels may play a role in mediating subclinic glomerular injury of such patients. However, we could not determine the exact site(s) of NO synthesis by the kidney, such as the glomeruli, blood vessels and/or the tubular cells. Whatever the source, urinary NO levels may be used as a new activity marker in the diagnosis and follow up of BD by serial measurements.

Urinary adrenomedullin levels are increased and correlated with plasma concentrations in patients with Behçet's syndrome.

BACKGROUND: The objective was to measure urinary adrenomedullin (AM) levels in patients with active or inactive Behçet's syndrome and compare them to levels in healthy control subjects. METHODS: Forty-five consecutive patients with Behçet's syndrome (20 men and 25 women with a mean age of 37.7 +/- 10.8 years) and 20 age- and sex-matched healthy hospital staff volunteers as control subjects (nine men and 11 women with a mean age of 36.2 +/- 10.4 years) were studied. Urinary and plasma AM concentrations were measured by high-performance liquid chromatography. We also investigated whether disease activity correlates with urinary and plasma AM levels. The Mann-Whitney U-test was used in statistical analysis and the values were expressed as mean +/- SD. RESULTS: Urinary excretion of AM (pmol per mg urinary creatinine) in patients with Behçet's syndrome (81.3 +/- 35.1) was significantly higher (P < 0.001) than in control subjects (31.2 +/- 16.1). Plasma AM levels (pmol/L) in patients with Behçet's syndrome and controls were 69.1 +/- 19.2 and 20.7 +/- 11.8, respectively; the difference was significant (P < 0.001). Although active Behçet's syndrome patients (n = 22) had higher urinary AM levels (92.1 +/- 41.1) compared to inactive (n = 23; 70.8 +/- 32.2), the difference was not significant (P > 0.05). Plasma AM levels in active Behçet's syndrome patients (77.5 +/- 21.2) were also higher than in inactive (61.6 +/- 17.3), but the difference was not significant (P > 0.05). CONCLUSION: Urinary AM levels were higher in Behçet's patients than in control subjects. Urinary AM levels were correlated with plasma AM levels. The results suggest that the higher AM levels found in the urine may be produced by the kidney as a result of the stimulation of inflammation during the course of Behçet's syndrome, or may come from plasma, as plasma AM levels were increased. However, the exact sites of AM synthesis by the kidney (e.g. glomeruli, blood vessels and/or tubular cells) could not be determined in this study. Further studies in this respect are necessary.

Glomerulonephritis in Behçet's disease: report of seven cases and review of the literature.

Despite being recognised much more frequently than in the past, renal involvement has not previously been regarded as a feature of Behcet's disease (BD). In this study we aimed to assess the frequency of renal involvement in BD by performing urinalyses of 674 consecutive BD patients; we also retrospectively evaluated the charts of 4212 BD patients for the incidence of glomerulonephritis (GN). Urinary abnormalities (proteinuria and/or haematuria) were present in 10.8%; and during a period of 23 years GN was detected by renal biopsy in seven (0.16%) BD patients. Two patients with GN were lost to follow-up; end-stage renal failure developed in only one patient, and she underwent renal transplantation. We were unable to determine any pathognomonic feature that was predictive of renal involvement. Although males tend to have a more serious clinical course of BD the incidences of urinary abnormalities and GN were similar in both sexes in our series. According to our results, we can conclude that urinary abnormalities are more frequent in BD; however, serious renal lesions develop in only very few of these patients.