INNATE IMMUNITY AND ORGAN TRANSPLANTATION: THE POTENCIAL ROLE OF TOLL-LIKE RECEPTORS

ANDRADE C. F.(1), WADDELL T. K.(1), KESHAVJEE S.(1), LIU M.(1)

(1)Thoracic Surgery Research Laboratory, Toronto General Hospital, University Health Network, Department of Surgery, University of Toronto, Ontario, Canada

Traditionally, the recognition and tolerance of transplanted grafts has been considered to be within the realm of the adaptive immune system. Innate immunity, on the other hand, as the first line of host defense, plays a role in fighting against invading microorganisms. Recently, with the discovery of the Toll-like receptors (TLRs), the role of innate immune responses in the control of adaptive immunity has become a new area of interest. Emerging evidence suggests that in addition to responding to pathogen-associated molecular patterns of microorganisms, TLRs can be activated by endogenous ligands, expressed by mammalian cells. These ‘danger signals’ may participate in ischemia-reperfusion related organ damage and subsequently influence function and survival of transplanted grafts. Furthermore, it has been suggested that adaptive immune responses can enhance the acute inflammatory responses controlled by innate immunity in organ transplantation. This review addresses the potential involvement of TLRs in different stages of organ transplantation. Intriguing and controversial findings are presented and discussed in order to stimulate more attention to this emerging and potentially important area of research in organ transplantation.

KEY WORDS: adaptive immunity, danger signals, ischemia-reperfusion, rejection

FINANCIAL SUPPORT: Ontario Thoracic Society, the Canadian Cystic Fibrosis Foundation, the Canadian Institutes of Health Research (MT-13270, MOP-42465), CAPES (Brazil).

CORRESPONDENCE TO:

Cristiano Feijó Andrade, Irmandade Santa Casa de Misericórdia de Porto Alegre. Avenida Prof. Annes Dias, 285, Centro, CEP 90020-090 - Porto Alegre, RS, Brasil. Fone: (51) 32273909. Email: cristiandrade@bol.com.br