Examining the clinical significance of microvascular inflammation after kidney transplantation

Investigators recently uncovered key insights into newly defined rejection entities in kidney transplantation that may offer improved patient risk categorization post-transplant. The research will be presented at ASN Kidney Week 2024, from October 23–27.

Kidney transplant rejection continues to threaten the long-term success of kidney transplants, with microvascular inflammation (inflammation within capillaries) playing a pivotal role in graft failure. Due to its complex nature, this inflammation poses a major challenge in clinical practice.

In response, the international Banff classification—the global standard for diagnosing transplant rejection—has redefined antibody-mediated rejection diagnostics by introducing two new categories of microvascular inflammation: mild microvascular inflammation with probable antibody-mediated rejection and microvascular inflammation in the absence of antibody-mediated responses.

In a landmark study analyzing more than 16,000 biopsies from almost 7,000 kidney transplant recipients, researchers found that many cases initially considered as non-rejection were reclassified into the newly defined categories of microvascular inflammation. Importantly, reclassified patients with microvascular inflammation in the absence of antibody-mediated responses displayed an increased risk of graft failure compared with those without signs of rejection, underscoring the importance of this new classification.

“Recognizing these phenotypes could improve risk stratification and support more personalized management for kidney transplant patients,” explains first author, Aurélie Sannier, pathologist and researcher at the Paris Institute for Transplantation and Organ Regeneration. “We encourage large studies in other organ transplants where microvascular inflammation is also a critical feature of antibody-mediated rejection.”