Angiotensin II Type 1 Receptor Antibodies among Renal Transplant in UAE
Hypertension is one of the most important risk factors for acute rejection and graft loss in renal transplantation. In the study of hypertension, the genes of the renin-angiotensin system (RAS): renin, angiotensin-converting enzyme (ACE), angiotensinogen, and angiotensin II receptor type 1 (AT1R) are of the greatest interest. The results of numerous studies in this area have shown that the raising RAS activity determines the development of hypertension in many respects. Hyperactivity of the RAS tissue causes the distortion of the structure and function of organs and tissues. In addition, it is the RAS tissue activation that is responsible for the remodeling of the heart and blood vessels, the development of heart failure, type II diabetes, retinopathy, and nephropathy as well (Cheungpasitporn et al., 2016).
Compatibility of HLA antibodies is an important factor in determining the long-term survival of a renal transplant patient. There are two categories of non-HLA antibodies: alloantibodies and auto-antibodies (Zhang & Reed, 2016). Even a complete match on the main HLA I and II does not guarantee the absence of acute rejection episodes in the postoperative period (Pabon, Navarro, & Martin, 2011). Humoral mechanisms also play their role in renal rejection. They are mediated by the antibodies, which may be present in the serum of the recipient prior to transplantation or develop after the transplantation of the foreign tissue. Preoperative identification of already present antibodies against the transplanted cells is accomplished by directly determining tissue compatibility, which is performed in a vitro formulation of the reaction between the donor cells and the serum of the recipient. Interaction of antibodies with the antigen on the surface of the transplanted cells leads to the cell death. In addition, the accumulation of immune complexes in blood vessels activates complement, which leads to the development of acute or chronic necrotizing vasculitis or chronic fibrosis with a narrowing of blood vessels (Mauiyyedi & Colvin, 2002).
Methodology
A total of 599 adult patients who received a kidney transplant between 1998 and 2007 were enrolled in the study. 521 of them received a first kidney transplant, 59 - a second kidney transplant, and 3% of the participants had already more than two transplants. For the research, the donors were analyzed by such parameters as gender, age, and deceased/living status. The parameters of the recipients included gender, age, time of any acute rejection episodes, and a number of previous transplants, pretransplantation anti-HLA immunization, delayed graft function, HLA-A-B-DR incompatibilities, and induction therapy with antithymocyte globulin or anti-IL2 receptor antibodies. 94.2% of the participants were recipients of a deceased-donor kidney. 34% of patients were treated with antithymocyte globulin, and 49.6% of patients received anti-interleukin-2-receptor-antibodies. In addition, 95% of patients received steroids for maintenance therapy and calcineurin inhibitors associated with mycophenolate mofetil (Giral et al., 2013).
Since 1998, for each consecutive patient receiving a renal transplant, the serum samples were stored in the DIVAT-biocollection. For the research, anti-AT1R antibodies were measured with a sandwich ELISA. Pre- and posttransplant …
