Identification of inflammatory markers suitable for non-invasive, repeated measurement studies in biobehavioral research: A feasibility study.

INTRODUCTION: Studying the role of the immune system in the interaction between mental and physical health is challenging. To study individuals with an intensive, longitudinal study design that requires repetitive sampling in their daily life, non-invasive sampling techniques are a necessity. Urine can be collected in a non-invasive way, but this may be demanding for participants and little is known about fluctuation of inflammatory markers in urine over time. The aim of this study was to investigate the feasibility of non-invasive sampling, and to explore intra-individual differences in inflammatory markers in urine. MATERIALS & METHODS: Ten healthy individuals collected 24-hour urine for 63 consecutive days. In a pilot analysis, 39 inflammatory markers were examined for detectability in urine, stability over time and under storage conditions, and daily fluctuations. Multiplex analyses were used to quantify levels of eight selected markers: C-reactive protein (CRP), Fractalkine, Interleukin-1 receptor-antagonist (IL-1RA), interferon-α (IFNα), interferon-γ (IFNγ), Interferon gamma-induced protein 10 (IP10), Macrophage inflammatory protein-1ß (MIP-1ß), and Vascular Endothelial Growth Factor (VEGF). Cross-correlations were calculated between the overnight and 24-hour samples were calculated, to examine whether 24-hour urine could be replaced by the overnight portion for better feasibility. We examined intra- and interindividual differences in the levels of inflammatory markers in urine and the fluctuations thereof. RESULTS: This study showed that levels of selected inflammatory markers can be detected in urine. Cross-correlation analyses showed that correlations between levels of inflammatory markers in the night portion and the 24-hour urine sample varied widely between individuals. In addition, analyses of time series revealed striking inter- and intra-individual variation in levels of inflammatory markers and their fluctuations. CONCLUSION: We show that the assessment of urinary inflammatory markers is feasible in an intensive day-to-day study in healthy individuals. However, 24-hour urine cannot be replaced by an overnight portion to alleviate the protocol burden. Levels of inflammatory markers show substantial variation between and within persons.

Monocyte Chemotactic Protein-1, Fractalkine, and Receptor for Advanced Glycation End Products in Different Pathological Types of Lupus Nephritis and Their Value in Different Treatment Prognoses.

BACKGROUND: Early diagnosis is important for the outcome of lupus nephritis (LN). However, the pathological type of lupus nephritis closely related to the clinical manifestations; therefore, the treatment of lupus nephritis depends on the different pathological types. OBJECTIVE: To assess the level of monocyte chemotactic protein (MCP-1), fractalkine (Fkn), and receptor for advanced glycation end product (RAGE) in different pathological types of lupus nephritis and to explore the value of these biomarkers for predicting the prognosis of lupus nephritis. METHODS: Patients included in this study were assessed using renal biopsy. Class III and class IV were defined as the proliferative group, class V as non-proliferative group, and class V+III and class V+IV as the mixed group. During the follow-up, 40 of 178 enrolled patients had a poor response to the standard immunosuppressant therapy. The level of markers in the different response groups was tested. RESULTS: The levels of urine and serum MCP-1, urine and serum fractalkine, and serum RAGE were higher in the proliferative group, and lower in the non-proliferative group, and this difference was significant. The levels of urine and serum MCP-1 and serum RAGE were lower in the poor response group, and these differences were also significant. The relationship between urine MCP-1 and urine and serum fractalkine with the systemic lupus erythematosus disease activity index was evaluated. CONCLUSION: The concentration of cytokines MCP-1, fractalkine, and RAGE may be correlated with different pathology type of lupus nephtitis. Urine and serum MCP-1 and serum RAGE may help in predicting the prognosis prior to standard immunosuppressant therapy.

Expressions of mRNA for innate immunity-associated functional molecules in urinary sediment in immunoglobulin A nephropathy.

AIM: It has been reported that the innate immune system plays a pivotal role in the pathogenesis of immunoglobulin A nephropathy (IgAN). To explore non-invasive monitoring of disease activity in children with IgAN, we examined whether expressions of mRNA for innate immunity-associated functional molecules: CC ligand chemokine 5 (CCL5), fractalkine/CX3CL1, interferon-γ-induced protein 10 (IP-10), monocyte chemoattractant protein 1 (MCP-1), retinoic acid-inducible gene-I (RIG-I), and toll-like receptor 3 (TLR3) in urinary sediment from patients with IgAN correlate with histologic parameters. METHODS: Twenty consecutive children with IgAN and four children with thin basement membrane disease (serving as a non-inflammatory control) were enrolled in this pilot study. Urinary mRNA expressions of target genes were examined real-time quantitative polymerase chain reaction. RESULTS: The expressions of CCL5, fractalkine and RIG-I were significantly increased in IgAN (all P < 0.05). Although no significant correlation was observed between mRNA expressions of these three molecules and clinical parameters, such as levels of urinary protein excretion, degrees of occult blood in urine and serum albumin, the expression of fractalkine was significantly correlated with the histological activity index (P = 0.022) and the chronicity index (P = 0.005). Furthermore, intense glomerular immune activity of fractalkine was observed in biopsy specimens in patients with moderately to severe proliferative IgAN. CONCLUSION: Regional expression of fractalkine may be involved in the pathogenesis of childhood IgAN. Although our present findings remain preliminary, measurement of mRNA expression of fractalkine in urinary sediment could be used as a non-invasive method for predicting histologic severity in IgAN in children. Further studies of this issue are needed.

Urinary fractalkine and monocyte chemoattractant protein-1 as possible predictors of disease activity of childhood glomerulonephritis.

Renal biopsy is the gold standard for confirmation of disease severity and diagnosis of glomerulonephritis (GN), but its procedure is invasive with a risk of complications. Thus, a non-invasive monitoring method is desirable especially in pediatric patients. Fractalkine and monocyte chemoattractant protein-1 (MCP-1) are proinflammatory chemokines, and both have been reported to be involved in the pathogenesis of immunocomplex-mediated GN. Recently, it has been reported that urinary fractalkine and MCP-1 may serve as possible predictors of disease activity of adult patients with GN. We, therefore, examined whether urinary levels of fractalkine and MCP-1 correlate with clinical and histologic parameters. Twenty-six consecutive children with various types of GN were enrolled in this study, including lupus nephritis, IgA nephropathy, membranous nephropathy, acute GN, and thin basement membrane disease (served as a non-inflammatory control). Urinary fractalkine and MCP-1 concentrations in the first morning urine samples obtained at the time of renal biopsy were measured by enzyme-linked immunosorbent assay, and standardized for urinary creatinine concentrations. Urinary fractalkine concentration differed significantly among the disease categories. Urinary concentrations of fractalkine and MCP-1 showed a significant positive correlation with the degree of occult blood in urine and a significant inverse correlation with the estimated glomerular filtration rate. Furthermore, the urinary MCP-1 concentration was significantly correlated with histological chronicity indices in patients with lupus nephritis and IgA nephropathy. Measurement of urinary fractalkine and MCP-1 concentrations may be useful as a non-invasive method for predicting the disease activity of GN in children.