Plasma miR-150-5p in Renal Transplant Recipients with Acute Antibody-Mediated Rejection.

Background: Rejection continues to be the main cause of renal graft loss. Currently, the gold standard for diagnosis is an allograft biopsy; however, because it is time-consuming, costly, and invasive, the pursuit of novel biomarkers has gained interest. Variation in the expressions of miRNAs is currently considered a probable biomarker for the diagnosis of acute rejection. This study aimed to determine whether miR-150-5p in serum is related to microvascular damage in patients with acute antibody-mediated rejection (ABMR). Methods: A total of 27 patients who underwent renal transplantation (RT) with and without ABMR were included in the study. We performed the quantification of hsa-miR-150-5p, hsa-miR-155, hsa-miR-21, hsa-miR-126, and hsa-miR-1 in plasma by RT-qPCR. The expressions between the groups and their correlations with the histological characteristics of the patients with ABMR were also investigated. Results: miR-150-5p significantly increased in the plasma of patients with rejection (p < 0.05), and the changes in miR-150-5p were directly correlated with microvascular inflammation in the allograft biopsies. Clinical utility was determined by ROC analysis with an area under the curve of 0.873. Conclusions: Our results show that the patients with RT with ABMR exhibited increased expression of miR-150-5p compared to patients without rejection, which could have clinical consequences, as well as probable utility in the diagnosis of ABMR, and bioinformatics may help in unraveling the molecular mechanisms underlying ABMR conditions.

Rechazo crónico mediado por anticuerpos

Contexto el rechazo crónico mediado por anticuerpos (cABMR, chronic antibody-mediated rejection) se considera una de las principales causas de disfunción crónica del injerto. Objetivo profundizar en la comprensión de los mecanismos que la ocasionan para diseñar tratamientos efectivos, dado que es muy poco lo que se ha avanzado en el tratamiento de esta patología. Metodología en esta revisión narrativa de la literatura, presentamos los factores de riesgo relacionados con la disfunción crónica del injerto, haciendo énfasis en la fisiopatología, el diagnóstico y el tratamiento del cABMR. Resultados el factor de riesgo más relevante para el desarrollo de disfunción crónica del injerto es el desarrollo de anticuerpos donante específicos (DSA) y ABMR. Para el diagnóstico de cABMR activo, se requieren los criterios de Banff 2017 (los tres deben estar presentes: Evidencia histológica de lesión tisular crónica, evidencia de inflamación actual en el endotelio vascular ocasionada por anticuerpos y evidencia serológica de DSA. El cABMR no tiene un tratamiento efectivo. Conclusiones dado que cABMR no tiene un tratamiento efectivo, es importante disminuir la exposición a los factores de riesgo y hacer un diagnóstico y un tratamiento oportuno de los eventos agudos de lesión renal que contribuyen a la progresión de disfunción crónica del injerto.

Context Chronic antibody-mediated rejection (cABMR) is considered one of the main causes of chronic graft. Objective To review the mechanisms that cause cABMR to design effective treatments, since it is very little what has been advanced in it treatment of this pathology. Methodology In this narrative review of the literature, we present the risk factors related to the chronic dysfunction of the injection, emphasizing the pathophysiology the diagnosis and treatment of cABMR. Results The most relevant risk factor for the development of chronic graft dysfunction is the development of specific donor antibodies (DSA) and ABMR. For the diagnosis of active cABMR, the criteria of Banff 2017 are required (three must be present: histological evidence of chronic tissue injury, evidence of current inflammation in the vascular endothelium caused by antibodies and serological evidence of DSA. The cABMR does not have an effective treatment. Conclusions Since cABMR does not have an effective treatment, it is important reduce exposure to risk factors and carry out a diagnosis and treatment of the acute events of kidney injury that contribute to the progression of chronic injection dysfunction.

Retrasplante pulmonar con cross-match positivo en trasplante pulmonar primario complicado con rechazo mediado por anticuerpos / Lung Retransplantation with Positive Crossmatch in Primary Lung Transplantation Complicated by Antibody-Mediated Rejection

La hipertensión arterial pulmonar (HAP) representa el 2,6% de los trasplantes pulmonares (TP), con una mediana de supervivencia condi cional (desde los 30 días del TP) de 9,8 años. Son frecuentes, el rechazo celular agudo (ACR) y la disfunción crónica del injerto (CLAD), mientras que es infrecuente el rechazo mediado por anticuerpos (AMR). El retrasplante pulmonar (RTP) constituye el 4% del TP mundial, debido a complicaciones en la vía aérea, disfunción primaria del injerto, ACR y CLAD. Mujer de 22 años, portadora de HAP idiopática (HAPI) desde el año 2013, trasplantada bipulmonar (TBP) en enero de 2018. A los 16 meses presentó neumonía adquirida en la comuni dad. En una internación posterior, presentó ACR y a pesar de pulsos de metilprednisolona, progresó a requerimientos de cánula de alto flujo y ventilación mecánica no invasiva hospitalaria, caída del VEF1, y tomografía de tórax con vidrio esmerilado difuso y engrosamiento irregular reticular del intersticio subpleural; interpretándose como CLAD a predominio de síndrome de bronquiolitis obliterante (BOS), con presencia de anticuerpos específicos contra el donante (DSA). En enero de 2020 se realizó nuevo TP y ante cross-match positivo, se realizó plasmaféresis y reposición de IgG. Al mes del egreso, no se observaron signos de rechazo en control de biopsias transbronquiales. Entre 2 y 10% de los pacientes con indicación primaria de TP por HAPI son sometidos a retrasplante pulmonar (RTP). La presencia de DSA y el miss-match de HLA, no son contraindicaciones para el RTP.

Pulmonary arterial hypertension (PAH) represents 2.6% of lung transplantations (LT), with a conditional median survival (from 30 days after LT) of 9.8 years. Acute cellular rejection (ACR) and chronic lung allograft dysfunction (CLAD) are common; whereas the antibody-mediated rejection (AMR) is not. Lung retransplantation (LR) accounts for 4% of global LTs for complications in the airways, primary allograft dys function, ACR and CLAD. 22-year-old woman with idiopathic PAH (IPAH) since 2013, who underwent a double-lung transplantation (DLT) in January 2018. 16 months after transplantation she presented community-acquired pneumonia. During a subsequent hospitalization, she presented ACR. Despite the fact that she received pulse methylprednisolone, she required high-flow cannula therapy and hospital non-invasive mechanical ventilation; the FEV1 was reduced and she underwent a chest tomography with diffuse ground glass opacities and irregular reticular thickening of the subpleural interstitium; interpreting the predominance of BOS (bronchiolitis obliterans syndrome) as CLAD, with presence of donor-specific antibodies (DSA). In January 2020, she received a new DLT and due to a positive crossmatch, she was treated with plasmapheresis and IgG replacement. One month after hospital discharge, no signs of rejection were observed at the BTB (bone-patellar tendon-bone) control. Between 2 to 10% of patients with primary indication of LT for IPAH are subjected to lung retransplantation (LR). The presence of DSA and HLA (human leucocyte antigen) mismatch aren't contraindications to LR.

The immunohistochemical expression of von Willebrand factor, T-cadherin, and Caveolin-1 is increased in kidney allograft biopsies with antibody-mediated injury.

BACKGROUND: There are only a few reports evaluating the applicability of endothelial-damage markers analysis by immunohistochemistry (IHC) in kidney allograft samples. This study analyzed the expression of Caveolin-1 (Cav), von Willebrand factor (Vwf), and T-cadherin (Cad) in kidney biopsies and their association with antibody-mediated injury. METHODS: In this retrospective study, 114 cases with antibody-mediated changes (Banff, 2020) and 72 with interstitial fibrosis/tubular atrophy were selected. IHC for Cav, Vwf and Cad was performed and evaluated according to their qualitative expression in peritubular capillaries. The cases were grouped according to the presence of microvascular inflammation (MVI), donor-specific antibodies (DSA), C4d positivity and antibody-mediated rejection (AMR). A level of significance < 0.05 was adopted. RESULTS: Vwf expression was associated with MVI (p < 0.001), DSA (p = 0.016), C4d (p < 0.001) and AMR (p < 0.001), and was higher in DSA+/C4d+ cases despite MVI (p < 0.001). The expression of Cad correlated with MVI (p = 0.015), C4d (p = 0.005) and AMR (p = < 0.001). Cad was more expressed in chronic AMR compared with acute/active cases (p = 0.001). Cav expression was associated with MVI (p = 0.029) and AMR (p = 0.016) and was also higher in chronic AMR (p = 0.049). A combined score of Vwf and Cad was higher in AMR when compared with C4d without rejection and IF/TA cases (p < 0.001). CONCLUSION: Vwf, Cad and Cav expression shows association with antibody-mediated injury and may be helpful to support AMR diagnosis.

Capillary leak syndrome as a complication of antibody-mediated rejection treatment: a case report.

We report a case of capillary leak that developed during treatment of antibody-mediated rejection in a kidney transplant recipient. A 53-year-old female transplant recipient experienced an increase in serum creatinine from 1.1 to 1.8 mg/dL. Antibody-mediated rejection was diagnosed by graft biopsy. She was treated with five plasmapheresis sessions (on alternate days with albumin replacement), five doses of immunoglobulin (5 g/dose at 100 mg/kg), a single dose of rituximab (500 mg), and four doses of bortezomib on days 1, 4, 7, and 10 (1.72 mg/dose at 1.3 mg/m2 body surface area). During treatment, edema, slight diarrhea, pancytopenia, hypoalbuminemia, peripheral neuropathy, and postural hypotension were noted. Despite control of liquids, she presented with edema progressing to an increase of more than 10 kg body weight. Prerenal acute graft dysfunction associated with hypotension was diagnosed on day 12, heart failure or other infectious complications being discounted. On day 13, daily hemodialysis was prescribed, and a stable volume status was reached after five hemodialysis sessions. On day 20, the patient recovered diuresis and the edema and diarrhea abated, but she remained on chronic hemodialysis. After excluding other causes of distributive shock, the diagnosis of capillary leak syndrome was based on the presence of hypotension, generalized edema, and hypoalbuminemia in the absence of significant proteinuria. The concomitant presence of diarrhea, peripheral neuropathy, and pancytopenia, suggest a possible causal role for bortezomib. Awareness by clinicians of capillary leak syndrome associated with bortezomib-based treatment of AMR is paramount, despite its rarity.

Bortezomib in Kidney Transplant: Current Use and Perspectives.

BACKGROUND: Despite major advances in transplant medicine, antibody-mediated rejection (AMR) continues to have severe clinical implications and adversely affect graft survival. Therefore, the search for alternative drugs to treat AMR is widely pursued. The first-in-class proteasome inhibitor bortezomib (BZ) is a selective inhibitor of the 26S proteasome, which was initially approved for the treatment of malignant plasma cell disorders. METHODS: This review encompasses how our understanding of inhibiting proteasome pathway created the basis of BZ research and important milestones accomplished in AMR treatment in the transplant setting. It further discusses at length the results of clinical studies, the tolerability profile, drug-drug interactions and the perspectives of BZ use in desensitization protocols. RESULTS: Proteasome inhibition can downregulate NF-κB activity; decrease cell proliferation/differentiation; induce apoptosis via cell cycle arrest, endoplasmic reticulum stress and caspase induction due the accumulation of unfolded or misfolded proteins; and downregulate antigen presentation, cell-cell interaction, and cell migration. Proteasome inhibition is more evident in cells with high rate of protein synthesis and secretion, like plasma cells. These cells play a critical role in the production of antibodies during AMR. CONCLUSIONS: There is accumulating evidence that the proteasome inhibitor BZ may substantially affect the function and integrity of alloantibody-secreting plasma cells in AMR after organ solid transplant, as well as the activation, proliferation and differentiation of T- and B-lymphocytes. Recent clinical studies have provided evidence that BZ has the capability to downregulate circulating antibodies and treat AMR episodes. Additional randomized-controlled studies are required to assess the impact of BZ during short and long follow-ups.

Compartment-specific expression of natural killer cell markers in renal transplantation: immune profile in acute rejection.

Natural killer (NK) cells have been implicated in graft dysfunction. Here, we formulated hypothesis that distinct patterns of expression NK cells markers correlated with acute rejection in kidney transplantation. Therefore, we studied the pattern of NK cell markers CD56, CD57, and CD16 in different compartments of biopsies obtained from recipients diagnosed with acute graft rejection, with or without donor-specific antibodies (DSA). DSA-negative biopsies-from patients with acute T-cell mediated rejection (aTCMR) had an increased expression of CD56+ and CD57+ cells (P = 0.004 and P = 0.001) in the interstitial compartment in comparison with DSA-positive biopsies from patients acute antibody-mediated rejection (aABMR) with (aABMR C4d+) and without C4d deposition (aABMR C4d-). CD16+ cells was increased (P = 0.03) in the glomerular compartment in DSA-positive biopsies. We assume that CD16+ expression and antibody-dependent cellular cytotoxicity (ADCC) in microvascular injury can be associated with aABMR. IFN-γ release from cytoplasmic granules of NK cell could be associated with aTCMR. Our findings suggest that NK cells need to be carefully evaluated because variations in NK cell marker expression might imply the involvement of different immune system pathways in graft rejection.

Dynamics of anti-human leukocyte antigen antibodies after renal transplantation and their impact on graft outcome.

The purpose of this study was to sequentially monitor anti-HLA antibodies and correlate the results with antibody-mediated rejection (AMR), graft survival (GS), and graft function (GF). We collected sera from 111 kidney transplant recipients on transplant days 0, 7, 14, 30, 60, 90, 180, and 360 and analyzed PRA levels by ELISA. DSAs were analyzed by single-antigen beads in rejecting kidneys. At pre-transplant, 79.3% of the patients were non-sensitized (PRA = 0%) and 20.7% were sensitized (PRA > 1%). After transplant, patients were grouped by PRA profile: no anti-HLA antibodies pre- or post-transplant (group HLApre-/post-; n = 80); de novo anti-HLA antibodies post-transplant (group HLApre-/post+; n = 8); sensitized pre-transplant/increased PRA post-transplant (group HLApre+/post↑; n = 9); and sensitized pre-transplant/decreased PRA post-transplant (group HLApre+/post↓; n = 14). De novo anti-HLA antibodies were detected at 7-180 d. In sensitized patients, PRA levels changed within the first 30 d post-transplant. Incidence of AMR was higher in HLApre-/post+ and HLApre+/post↑ than in HLApre-/post-, and HLApre+/post↓ (p < 0.001) groups. One-yr death-censored GS was 36% in group HLApre+/post↑, compared with 98%, 88% and 100% in groups HLApre-/post-, HLApre-/post+, and HLApre+/post↓, respectively (p < 0.001). Excluding first-year graft losses, GF and GS were similar among the groups. In conclusion, post-transplant antibody monitoring can identify recipients at higher risk of AMR.

Anticuerpos anti-HLA y rechazo agudo del injerto renal en los niños / Anti-HLA antibodies and acute renal graft rejection in children

Introducción. A pesar de que las nuevas terapias inmunosupresoras han mejorado notablemente la evolución clínica de los trasplantes renales, los rechazos agudo y crónico siguen limitando la sobrevida a largo plazo del injerto. En base a lo anterior, el objetivo de este estudio fue determinar la presencia de anticuerpos séricos contra antígenos de histocompatibilidad (HLA) clase I y clase II en niños con rechazo agudo del injerto renal. Métodos. Se realizó un estudio clínico prospectivo en pacientes con trasplante renal que presentaron rechazo agudo del injerto. Se les tomó muestra de suero al momento de la biopsia renal, misma que fue utilizada para la detección de anticuerpos contra antígenos HLA de clase I y II por ensayo basado en equipo fuoroanalizador (Luminex) y microperlas cubiertas con antígenos clase I y clase II de One Lambda. Resultados. De 21 pacientes estudiados, 17 pacientes (81%), fueron diagnosticados con rechazo celular y cuatro (19%) con rechazo agudo mediado por anticuerpos. El tiempo post-trasplante promedio de presentación del rechazo humoral agudo fue de 18.7 meses y para el rechazo celular de 36.7 meses. Once pacientes (52.3%) presentaron anticuerpos específicos contra el donador. Los anticuerpos contra antígenos HLA clase I donador específicos se encontraron en seis pacientes, siendo más frecuente el rechazo agudo mediado por anticuerpos (humoral), donde todos los pacientes tuvieron anti HLA clase I con Chi cuadrada (P =0.004). En cuanto a los anticuerpos inespecíficos, el 95.2% de los pacientes desarrollaron este tipo de anticuerpos. Conclusiones. El 95% de los niños con rechazo del injerto renal presentan anticuerpos anti HLA, específicos y/o no específicos contra el donador. Los anticuerpos anti HLA donador específicos clase I se presentan con mayor frecuencia en el rechazo humoral.

Background. Although new immunosuppressive therapies have signifcantly improved the clinical progression of kidney transplants, acute and chronic rejection continue to limit long-term graft survival. Despite this, the aim of the study was to determine the presence of human leukocyte antigen (HLA) antibodies class I and class II in children with acute renal graft rejection. Methods. Patients with graft rejection were included in the study. A serum sample for anti-HLA antibody measurement class I and II by Luminex was taken at the time of renal biopsy. Results. Seventeen patients (81%) had cellular rejection and four (19%) antibody-mediated rejection. Mean post-transplant time of rejection was 18.7 months and 36.7 months for humoral rejection and cellular rejection, respectively. Eleven patients (52.3%) had donor specific (DS) antibodies. Anti-HLA class I DS was found in six patients including the four patients with humoral rejection (Fisher exact test p =0.004); 95.2% had non-DS antibodies. Conclusions. Of the children with acute renal graft rejection, 95% have anti HLA antibodies (DS and/or non-DS). Anti-HLA DS class I are more frequent in humoral rejection.