Urinary Monocyte Chemoattractant Protein-1 Levels and Interstitial Changes in the Renal Cortex and Their Relationship with Loss of Renal Function in Renal Transplant Patients with Delayed Graft Function

Abstract

Background: Inflammatory cell infiltration and residual areas of fibrosis in kidneys after renal transplantation can lead to functional abnormalities with long-term implications. Objectives: The aim of this study was to determine urinary monocyte chemoattractant protein-1 (uMCP-1) levels, relative cortical interstitial area (RCIA), and cortical tubulointerstitial macrophage infiltration in renal transplant patients with delayed graft function (DGF) and their possible correlation with graft outcome. Design: Patients were followed after biopsies for one year, and their renal function and structure were evaluated, as well as parameters of inflammatory process. Setting: Clinical Hospital of the School of Medicine of Ribeirão Preto. Patients: Twenty-two cadaveric kidney transplant recipients with DGF were followed for one year. Measurements: Renal function, RCIA, macrophages infiltration and uMCP-1 levels were evaluated. Methods: Renal function was evaluated by plasma creatinine levels. RCIA was determined by morphometry. Immunohistochemical staining of macrophages was performed using an anti-CD68 monoclonal antibody. uMCP-1 levels were determined using a human MCP-1/CCL2 immunoassay kit. Results: There was a significant increase in uMCP-1 levels in transplant patients compared with controls ( p < 0.001). RCIA was 7.1% (6.4 to 9.2; median and 25th to 75th percentiles) in controls and 37.1% (28.1 to 43.7) in patients with kidney transplants ( p < 0.001). The patients who presented with a higher RCIA in the first biopsy showed higher levels of plasma creatinine one year after transplantation (r = 0.44; p < 0.05). The number of tubulointerstitial macrophages per 0.10 mm 2 grid field was higher in the renal cortex of transplant patients compared with the controls (19.4 (9.0 to 47.1) vs. 2.5 (1.8 to 3.4), p < 0.001). There was also a positive correlation between the RCIA and the number of tubulointerstitial macrophages in the renal cortex of these patients (r = 0.49; p < 0.001). Limitations: The number of patients studied was relatively small and may not be reflecting outcomes over a larger spectrum of kidney cadaveric transplants. Conclusions: Our results demonstrate increased levels of uMCP-1 in transplant patients with DGF, in addition to increased tubulointerstitial macrophage infiltration and RCIA, which could predict the outcome of renal function in these patients.