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The mechanisms of graft acceptance (tolerance) have been a major area of investigation in the transplant group at Massachusetts General Hospital, with mouse, pigs, non-human primates and clinical trials. Robert Colvin, MD, is currently seeking the mechanisms of graft acceptance and the role of Foxp3+ Treg cells in mouse kidney allografts. These studies have revealed a novel Treg-rich organized lymphoid structure (TOLS) in accepted allografts that surround small arteries. Depletion of Treg causes dissolution of the TOLS and precipitates acute graft rejection. Dr. Colvin’s group showed that kidney allografts induce systemic tolerance within two weeks that allows subsequent acceptance of heart allograft. Systemic tolerance is dependent on Foxp3 cells. Current work addresses the molecular mechanisms by which kidneys induce tolerance.

In studies in human kidney allografts, Dr. Colvin’s group was the first to describe chronic antibody-mediated rejection, now recognized as the most common cause of late graft dysfunction. He has shown that deposition of the classical complement component, C4d, in peritubular capillaries is a useful marker of acute and chronic antibody-mediated rejection. C4d is the most specific marker of these conditions. Through the efforts of Dr. Colvin and others, new categories of acute and chronic antibody-mediated rejection have been incorporated into the Banff criteria and have become the standard of care. Non-human primate studies have demonstrated sequential stages of chronic humoral rejection and tolerance with distinctive mRNA signatures as detected by Nanostring analysis of protocol biopsies. This approach is now being applied to human renal transplant biopsies in a protocol to induce tolerance.

The major focus of the laboratory currently is the transcript analysis of human renal biopsies, both transplanted and native kidneys. The technique employs the NanoString nCounter to assess ~800 genes in routine formalin fixed paraffin embedded tissues. Among the advantages of NanoString are that a separate core, processed at the time of biopsy, is not required. Transcripts are assessed in the same sample analyzed by light microscopy and large retrospective and longitudinal analyses of archived samples can be readily performed in the setting of multicenter studies, which will enable retrospective randomization with long-term survival endpoints available. Dr. Colvin is one of the leaders of an international consortium that has developed a novel Human Organ Transplant (HOT) panel to accelerate translational research and will be applying this approach to >1000 clinical samples. Recent publications have shown that transcripts can detect subpathologic evidence of rejection that correlates with outcome, including later development of antibody mediated rejection. Capillaritis and DSA but not C4d deposition correlated with transcript elevation.

Newly acquired technology has given us the opportunity to focus on spatial genomics, using the GeoMx and CosMx platforms to identity cell and site-specific gene expression in routine clinical kidney biopsy sections, led by Ivy Rosales. Her studies showed that glomerular endothelial cells develop a distinctive transcript response in transplant glomerulopathy, with ectopic production of COL4A1 and diminished expression of the glomerular endothelial specific gene EHD3, providing new insights into the pathogenesis of this defining feature of chronic antibody mediated rejection.

Selected Publications

  • Mengel, M, Loupy A, Haas C, C. R, Naesens M, Akalin E, Clahsen-van Groningen MC, Dagobert J, Demetris AJ, Duong van Huyen JP, Gueguen J, Issa F, Robin b, Rosales I, Von der Thüsen JH, Sanchez-Fueyo A, Smith RN, Wood K, Adam B and Colvin RB. Banff 2019 Meeting Report: Molecular Diagnostics in Solid Organ Transplantation—Consensus for the Banff Human Organ Transplant (B-HOT) Gene Panel and Open Source Multicenter Validation. Am J Transplant, 2020
  • Ma D, Hirose T, Lassiter G, Sasaki H, Rosales I, Coe TM, Rickert CG, Matheson R, Colvin RB, Qin W, Kan Y, Layer JV, Paragas VB, Stiede K, Hall KC, Youd ME, Queiroz LM, Westlin WF, Curtis M, Yang L, Markmann JF and Kawai T. Kidney Transplantation from Triple-Knockout Pigs Expressing Multiple Human Proteins in Cynomolgus Macaques. Am J Transplant, 2022. 22: 46-57
  • Rosales, I. A., Yang, C., Farkash, E. A., Ashry, T., Ge, J., Aljabban, I., Ayyar, A., Ndishabandi, D., White, R., Gildner, E., Gong, J., Liang, Y., Lakkis, F. G., Nickeleit, V., Russell, P. S., Madsen, J. C., Alessandrini, A. and Colvin, R. B. Novel Intragraft Regulatory Lymphoid Structures in Kidney Allograft Tolerance. Am J Transplant, 2022, 22: 705-716
  • Smith, RN, Rosales, IA, Tomaszewski, K, Mahowald, GK , Araujo-Medina, M, Acheampong, E, Bruce, A, Rios, A, Otsuka, T, Tsuji, T, Hotta, K and Colvin, RB.  Validation and Utility of Banff Human Organ Transplant Gene Panel in Human Kidney Transplant Biopsies. Transplantation, in press 2022
  • Rosales, IA, Mahowald, GK, Tomaszewski, K, Hotta, K, Iwahara, I, Otsuka, T, Tsuji, T, Takada, Y, Acheampong, E, Araujo-Medina, M, Bruce, A, Rios, A, Cosimi, AB, Elias, N, Kawai, T, Gilligan, H, Safa, K, Riella, LV, Tolkoff-Rubin, NE, Williams, Jr., WW, Smith, RN and Colvin, RB. Banff. “Human Organ Transplant Transcripts Correlate with Renal Allograft Pathology and Outcome: Importance of Capillaritis and Subpathologic Rejection.” J Am Soc Nephrol, in press, 2022