The potential role of perivascular lymphatic vessels in preservation of kidney allograft function

Background: Lymphangiogenesis occurs in diseased native kidneys and kidney allografts, and correlates with histological injury; however, the clinical significance of lymphatic vessels in kidney allografts is unclear. Methods: This study retrospectively reviewed 63 kidney transplant patients who underwent protocol biopsies. Lymphatic vessels were identified by immunohistochemical staining for podoplanin, and were classified according to their location as perivascular or interstitial lymphatic vessels. The associations between perivascular lymphatic density and kidney allograft function and pathological findings were analyzed. Results: There were no significant differences in perivascular lymphatic densities in kidney allograft biopsy specimens obtained at 0 h, 3 months and 12 months. The groups with higher perivascular lymphatic density showed a lower proportion of progression of interstitial fibrosis/tubular atrophy grade from 3 to 12 months (P for trend = 0.039). Perivascular lymphatic density was significantly associated with annual decline of estimated glomerular filtration rate after 12 months (r = −0.31, P = 0.017), even after adjusting for multiple confounders (standardized β = −0.30, P = 0.019). Conclusions: High perivascular lymphatic density is associated with favourable kidney allograft function. The perivascular lymphatic network may be involved in inhibition of allograft fibrosis and stabilization of graft function.