Abstract. Low molecular weight hyaluronate (LMW-HA) blocks interactions between T lymphocyte CD44 and hyaluronate (HA), a heteropolysaccharide that is expressed on the surface of endothelial cells and ubiquitously in the extracellular matrix. This study was undertaken to assess the ability of LMW-HA to modify the course of experimental acute renal allograft rejection. Lewis (LEW) rats were bilaterally nephrectomized and received an orthotopic, fully MHC-mismatched, Wistar-Furth (WF) kidney transplant. Animals received either no treatment, low doses of cyclosporin A (CsA) on days 0 to 5, LMW-HA on days 0 to 5, or CsA plus LMW-HA on days 0 to 5 after transplantation. With no treatment, CsA monotherapy, or HA monotherapy, animals rejected their allografts at a median of 15, 13, and 7.5 d, respectively (P = NS). In contrast, combined CsA plus LMW-HA therapy prevented acute rejection and significantly prolonged graft survival (P = 0.008) to a median of 49.0 d. CsA/LMW-HA-treated grafts also demonstrated better preservation of renal function at day 30 (serum creatinine level, 1.38 ± 0.8 mg/dl), compared with surviving animals treated with CsA alone (2.9 ± 0.55 mg/dl, P < 0.05). Histologic graft analysis of CsA/LMW-HA-treated animals at day 7 after transplantation showed minimal rejection and leukocyte infiltration, compared with all other groups. Intragraft gene expression analysis, using semiquantitative reverse transcription-PCR, at the same time point showed reductions of CD4, CD8, and interferon-γ transcript levels in the combined-treatment group. This is the first study demonstrating the immunomodulatory functions of LMW-HA in vivo in the setting of organ transplantation. Defining the exact mechanisms that underlie this immunomodulation may provide the rationale to develop novel strategies for use in clinical transplantation.
GlucoCEST magnetic resonance imaging in vivo may be diagnostic of acute renal allograft rejection
