Dorota Bartoszek

The influence of non‐HLA antibodies directed against angiotensin II type 1 receptor (AT1R) on early renal transplant outcomes

Non‐HLA antibodies (Abs) targeting vascular receptors are thought to have an impact on renal transplant injury. Anti‐angiotensin II type 1‐receptor‐activating antibodies (anti‐AT1R) have been mentioned to stimulate a severe vascular rejection, but the pretransplant screening has not been introduced yet. The aim of our study was to assess the incidence and importance of anti‐AT1R antibodies and their influence on renal transplant in the 1st year of observation. We prospectively evaluated the presence of anti‐AT1R antibodies in 117 consecutive renal transplant recipients in pre‐ and post‐transplant screening. Anti‐AT1R antibodies were observed in 27/117 (23%) of the analyzed recipients already before transplantation. The function of renal transplant was considerably worse in anti‐AT1R(+) group. The patients with anti‐AT1R Abs >9 U/ml lost their graft more often. Biopsy‐proven AR was described in 4/27 (15%) pts in the anti‐AT1R(+) group and 13/90 (14.4%) in the anti‐AT1R(−) group, but more severe cases of Banff IIB or antibody‐mediated rejection (AMR) were more often observed in anti‐AT1R (+) 4/27 (15%) vs. 1/90 (1.1%) in anti‐AT1R(+) (P = 0.009). Patients with anti‐AT1R Abs level >9 U/ml run a higher risk of graft failure independently of classical immunological risk factors. The recipients with anti‐AT1R Abs developed more severe acute rejections described as IIB or AMR in Banff classification. More recipients among the anti‐AT1R‐positive ones lost the graft. Our study suggests monitoring of anti‐AT1R Abs before renal transplantation for assessment of immunologic risk profiles and the identification of patients highly susceptible to immunologic events, graft failure, and graft loss.

The Complement Cascade and Renal Disease

Serum complement cascade, a part of innate immunity required for host protection against invading pathogens, is also a mediator of various forms of disease and injury. It is activated by classical, lectin, and alternative pathways that lead to activation of C3 component by C3 convertases, release of C3b opsonin, C5 conversion and eventually membrane attack complex formation. The tightly regulated activation process yields also C3a and C5a anaphylatoxins, which target a broad spectrum of immune and non-immune cells. The review discusses the involvement of the complement cascade in kidney disease pathogenesis and injury. The role of the complement pathways in autoantibody-mediated forms of glomerulonephritis (lupus nephritis, anti-glomerular basement membrane disease, anti-neutrophil cytoplasmic autoantibody-induced or membranoproliferative glomerulonephritis, membranous nephropathy), C3 glomerulopathy, atypical forms of hemolytic uremic syndrome, ischemic-reperfusion injury of transplanted kidney, and antibody-mediated renal allograft rejection are discussed. The disturbances in complement activation and regulation with underlying genetics are presented and related to observed pathology. Also promising strategies targeting the complement system in complement-related disorders are mentioned.

The impact of non-HLA antibodies directed against endothelin-1 type A receptors (ETAR) on early renal transplant outcomes.

BACKGROUND Non-HLA antibodies (Abs) targeting vascular receptors are considered to have an influence on renal transplant injury. Anti-endothelin-1 type A receptor (anti-ETAR) antibodies were associated with cellular and antibody-mediated rejection and early onset of vasculopathy in heart transplant patients but their role in renal transplantation remains unclear. The aim of our study was to assess the incidence and importance of anti-ETAR antibodies and their impact on renal transplant during the first year observation. METHODS We evaluated the presence of anti-ETAR antibodies in 116 consecutive renal transplant recipients in pre- and post-transplant screening (before and in 1st, 3rd, 6th, 12th month after transplantation). Additionally, we assessed the presence of anti-HLA antibodies. Anti-ETAR antibodies were assayed by ELISA. The diagnosis of acute rejection was based on the Banff criteria. RESULTS Anti-ETAR antibodies were observed in 55 (47.4%) of the analyzed recipients before transplantation. The function of renal transplant was significantly worse in the anti-ETAR(+) group compared to the anti-ETAR(-) group during the first post-transplant year. One month after transplantation the serum creatinine in anti-ETAR (+) patients (pts) was 1.86±0.8mg/dl and 1.51±0.5 in anti-ETAR(-) pts (p=0.009). Twelve months after transplantation the difference between the groups was still observed 1.70±0.7 vs. 1.40±0.4 (p=0.04). Biopsy proven acute rejection was recognized in 8/55 (14.5%) in ETAR(+) and 9/61 (14.8%) in ETAR(-) patients but cases with mild to severe intimal arteritis (v1-v3) were more often observed in patients with the presence of anti-ETAR Abs 4/55 (7.2%) comparing with 1/61 (1.6%) in anti-ETAR(-) patients. The anti-ETAR antibody levels varied at different measurement intervals during the one-year follow-up. CONCLUSIONS The presence of anti-ETAR antibodies is associated with a worse renal transplant function during the first 12months after transplantation. Including anti-ETAR antibodies in the diagnostics of renal transplant recipient immune status should be considered to provide comprehensive assessment of humoral alloimmunity.

Long-term Follow-up of Non-HLA and Anti-HLA Antibodies: Incidence and Importance in Renal Transplantation

BACKGROUND Detection of antibody-mediated injury is becoming increasingly important in post-transplant patient care. The role of donor-specific anti-human leukocyte antigen (HLA) antibodies in kidney transplant damage is known, whereas the significance of non-HLA antibodies remains an unresolved concern. The aim of the study was to determine the presence and influence on renal function of non-HLA and anti-HLA antibodies in stable patients at 5 years after kidney transplantation. METHODS We evaluated the antibodies in 35 consecutive patients with stable renal function at 5 years after transplantation. RESULTS Pretransplant screening for donor-specific antibodies by CDC cross-matches was negative in all patients. Anti-endothelial cell antibodies (AECA), anti-angiotensin II type 1 receptor antibodies (anti-AT1R), and anti-endothelin receptor antibodies (anti-ETAR) were assayed as non-HLA antibodies. Non-HLA antibodies were observed in 12 (34%) patients, including AECA (n = 5; 14%), anti- AT1R (n = 6; 17%), anti-ETAR (n = 4; 11%), and both anti-AT1R and anti-ETAR (n = 3). Among 13 (37%) patients with anti-HLA antibodies, 7 also had both non-HLA antibodies: AECA (n = 1), anti-AT1R (n = 3), and anti-ETAR (n = 3). The antibody-negative group (n = 13) showed significantly better renal function than the antibody-positive group (non-HLA and/or anti-HLA; n = 22). Biopsy-proven acute rejection had occurred in 2 of 13 (15%) antibody-negative versus 8 of 22 (36%) antibody-positive patients. These preliminary data revealed an high prevalence of autoantibody and alloantibody production among stable patients at 5 years after kidney transplantation. CONCLUSION Simultaneous production of these antibodies and their association with reduced renal function suggests that active humoral immune responses are poorly controlled by immunosuppression.

The Impact of De Novo Donor-specific Anti-Human Leukocyte Antigen Antibodies on 5-Year Renal Transplant Outcome

Numerous studies have shown that circulating donor-specific antibodies targeting human leukocyte antigen (HLA) are associated with accelerated renal transplant failure, but many patients with these antibodies have good graft function. The aim of our study was to investigate the long-term graft function and survival in patients with de novo post-transplant donor-specific anti-HLA antibodies (DSA). Our prospective study included 78 consecutive recipients with a negative crossmatch before transplantation. Recipient serum samples were assayed for DSA in week 2 and 1, 3, 6, 9, 12 months after transplantation using a complement-dependent lymphocytotoxic technique with donor lymphocytes. Additionally, patients with DSA and stable renal function in the first year were tested with a more sensitive flow-panel-reactive antibody. DSA were present in 34 (44%) of our patients during the first 12 months after transplantation. Biopsy-proved acute rejection occurred in 11 DSA-positive and 10 DSA-negative patients. Seven DSA-positive patients had antibody-mediated rejection and no DSA-negative ones developed humoral rejection. The serum creatinine level in DSA-positive patients was significantly higher (2.48 vs 1.43 mg/dL) in year 5. The 13 (38%) DSA-positive patients with good graft function in month 12 were stable during a 5-year follow-up: their serum creatinine was 1.46 ± 0.4 in year 1 and 1.56 ± 0.4 mg/dL in year 5 and nobody lost their allograft. One- and 5- year graft survivals were appropriately 85% and 59% in DSA-positive patients compared to 93% and 93% in DSA-negative patients. To sum up, post-transplant DSA had a significant influence on kidney function and graft survival but in 38% of patients the presence of DSA did not decrease a 5-year renal function. A good renal allograft function in the presence of DSA in the first year after transplantation and cessation of their production in the subsequent years may be a good prognostic marker for a long-term allograft function and survival.

Non-HLA antibodies: angiotensin II type 1 receptor (anti-AT1R) and endothelin-1 type A receptor (anti-ETAR) are associated with renal allograft injury and graft loss.

INTRODUCTION Non-HLA antibodies specific for angiotensin II type 1 receptor (anti-AT1R) and endothelin-1 type A receptor (anti-ETAR) of vascular cells activate signaling pathways leading to cell proliferation and vascular injury. The aim of this study was to evaluate the impact of non-HLA antibodies on kidney allograft morphology and function in patients who underwent a kidney biopsy due to renal function impairment. PATIENTS AND METHODS The study included 65 consecutive renal transplant patients who were evaluated for the presence of non-HLA and anti-HLA antibodies at the time of transplant biopsy. Results of pre-transplant CDC cross-match were negative. A kidney allograft biopsy was performed between 6 days and 13 years (42 ± 49 months) after transplantation, and the diagnosis was made on the basis of the Banff criteria. The level >9 U/L of anti-AT1R and anti-ETAR antibodies was considered high. RESULTS A high level of non-HLA antibodies (anti-AT1R and/or anti-ETAR) was found in 7 (10.7%) of 65 patients at the time of biopsy. Graft loss in the non-HLA-positive patients was significantly higher (71% in non-HLA-positive cases after 7.8 ± 2.6 months vs 11% after 6 months in non-HLA-negative cases [P = .00099]). In these non-HLA-positive patients, the mean anti-AT1R level was 15.3 ± 9.4 U/L and the mean anti-ETAR level was 13.8 ± 8.6 U/L. In only 2 of these patients were anti-HLA antibodies additionally detected: anti-class I in 1 and anti-class II in both patients. The mean serum creatinine level was 2.34 ± 0.6 mg/dL at the time of biopsy. Results of an early biopsy revealed acute vascular rejection (Banff grade IIB). Chronic allograft injury was found (grading cg1-3, cv1-2, ci1-2, ct1-2) in the remaining 6 patients. C4d was present in 3 of 7 patients. CONCLUSIONS High levels of anti-AT1R and/or anti-ETAR antibodies were associated with morphological and functional allograft injury and graft loss in these study patients. Non-HLA antibodies can be helpful in assessing the risk of graft failure.

Humoral immunity in hand transplantation: Anti-HLA and non-HLA response

UNLABELLED Antibodies against donors HLA antigens and B cell activity are recognized modulators of immune response to allograft. The role of both anti-HLA and non-HLA antibodies is understood in solid organ transplantation, but has not been addressed in composite tissue allografts. AIM We decided to evaluate the presence and role of anti-HLA and non-HLA antibodies after hand transplantation. METHODS We assayed anti-HLA and non-HLA antibodies in 5 consecutive hand transplant patients. The presence of anti-HLA antibodies was tested by flow-PRA method (One Lambda). Non-HLA antibodies were defined as anti-endothelial cell (AECA), anti-angiotensin II type 1 receptor (anti-AT1R), anti-endothelin receptor antibodies (anti-ETAR). RESULTS Anti-HLA antibodies were present in 1 patient in class I and in another one in class II. Both patients developed one episode of acute rejection. AECA were present in only one recipient with borderline activity. Both anti-AT1R and Anti-ETAR were found strongly positive in one patient who repeatedly developed acute rejection episodes. CONCLUSION The presence of non-HLA antibodies (anti-AT1R and anti-ETAR) and the occurrence of multiple rejection episodes found in one patient here require further investigation into a possible association and role of humoral immunity in composite tissue rejection.

Issues of Immunological and Hemodynamic Monitoring Before and During Kidney Transplantation in Sensitized Heart Transplant Recipient

Previously transplanted highly sensitized patients experience problems with subsequent transplantation. It is also difficult to provide optimal hemodynamic conditions during successive kidney transplantation in heart transplant recipients. PATIENT AND METHODS We present a case of a 56-year old patient with end-stage renal failure after heart transplantation performed 21 years ago and hemodialyzed using arteriovenous fistula. The patient had 69% panel-reactive antibodies, had been on the active waiting list since 2013, and presented 335 positive crossmatches with deceased donors. He also positively crossmatched with a potential living donor. Detailed examination of anti-HLA antibodies revealed the absence of IgG donor-specific antibodies and negative crossmatch with dithiothreitol-treated serum. The transplantation from his wife was performed with positive crossmatch after 4 plasma exchanges and thymoglobulin induction. Because sympathetic and parasympathetic denervation of the transplanted heart and the presence of arteriovenous fistula induced volume overload of the right heart, we used central venous pressure (CVP) and the PiCCO2 for postsurgical assessment of cardiac output. RESULTS Monitoring, like CVP and other static exponents of preload obtained by PICCO (extravascular lung water, global end-diastolic volume index) as well as the dynamic parameters obtained by PiCCO2 (pulse pressure variation, stroke volume variation), was not sensitive enough to describe recipient volume status. The immediate graft function was observed, and after 11 months satisfactory estimated glomerular filtration rate is noted with the absence of donor-specific antibodies. CONCLUSION The history of heart transplantation with existing arteriovenous fistula makes clinical tools such as continuous cardiac output monitoring and CVP parameter inadequate for describing the hemodynamic situation. The high level of panel-reactive antibodies and positive crossmatch possibly caused by IgM antibodies do not have to withdraw the recipient from kidney transplantation.