Proteasome Inhibitor Carfilzomib‐Based Therapy for Antibody‐Mediated Rejection of the Pulmonary Allograft: Use and Short‐Term Findings

We present this observational study of lung transplant recipients (LTR) treated with carfilzomib (CFZ)‐based therapy for antibody‐mediated rejection (AMR) of the lung. Patients were considered responders to CFZ if complement‐1q (C1q)‐fixing ability of their immunodominant (ID) donor‐specific anti‐human leukocyte antibody (DSA) was suppressed after treatment. Treatment consisted of CFZ plus plasma exchange and immunoglobulins. Fourteen LTRs underwent CFZ for 20 ID DSA AMR. Ten (71.4%) of LTRs responded to CFZ. DSA IgG mean fluorescence intensity (MFI) fell from 7664 (IQR 3230–11 874) to 1878 (653–7791) after therapy (p = 0.001) and to 1400 (850–8287) 2 weeks later (p = 0.001). DSA C1q MFI fell from 3596 (IQR 714–14 405) to <30 after therapy (p = 0.01) and <30 2 weeks later (p = 0.02). Forced expiratory volume in 1s ( FEV₁) fell from mean 2.11 L pre‐AMR to 1.92 L at AMR (p = 0.04). FEV₁ was unchanged after CFZ (1.91 L) and subsequently rose to a maximum of 2.13 L (p = 0.01). Mean forced expiratory flow during mid forced vital capacity (25–75) (FEF_25–75) fell from mean 2.5 L pre‐AMR to 1.95 L at AMR (p = 0.01). FEF_25–75 rose after CFZ to 2.54 L and reached a maximum of 2.91 L (p = 0.01). Responders had less chronic lung allograft dysfunction or progression versus nonresponders (25% vs. 83%, p = 0.04). No deaths occurred within 120 days and 7 patients died post CFZ therapy of allograft failure. Larger prospective interventional studies are needed to further describe the benefit of CFZ‐based therapy for pulmonary AMR.     

Postoperative outcomes of lung transplant recipients with preformed donor-specific antibodies

OBJECTIVESFew studies have evaluated the outcomes of lung transplantation (LTx) in recipients with preformed donor-specific antibodies (DSAs). This study investigated the postoperative changes in preformed DSAs based on prospectively collected data of DSAs, and the influences of preformed DSAs on postoperative outcomes among LTx recipients. Open in a separate windowMETHODSBetween July 2010 and December 2019, 216 recipients underwent LTx (81 living-donor lobar lung transplants and 135 deceased-donor lung transplants). We reviewed 8 cases with preformed DSAs to determine postoperative changes in DSAs and compared postoperative outcomes between recipients with and without DSAs.RESULTSThe preoperative mean fluorescence intensity of preformed DSAs ranged from 1141 to 14 695. Two recipients experienced antibody-mediated rejection within 2 weeks after LTx. DSAs disappeared in 7 recipients; however, 1 recipient experienced the relapse of DSAs and died from chronic lung allograft syndrome (CLAD), whereas 1 recipient had persisting DSAs within the study period and died from CLAD. Neither overall survival (OS) nor CLAD-free survival was significantly different between recipients with and without DSAs (P = 0.26 and P = 0.17, respectively). However, both OS and CLAD-free survival were significantly lower in recipients with DSAs against HLA class II than in those without these antibodies {5-year OS: 25.0% [95% confidence interval (CI): 0.9–66.5%] vs 72.1% (95% CI: 63.8–78.9%), P = 0.030 and 5-year CLAD-free survival: 26.7% (95% CI: 1.0–68.6%) vs 73.7% (95% CI: 66.5–79.5%), P = 0.002}.CONCLUSIONSPrognosis in recipients experiencing the relapse of preformed DSAs and those with persisting DSAs may be poor. The recipients with anti-HLA class II preformed DSAs had a significantly worse prognosis.     

Effects of re-augmenting maintenance immunosuppression on post-transplant donor-specific HLA antibodies in liver transplantation

BackgroundDonor-specific antibodies (DSAs) have various negative short- and long-term effects after organ transplantation. DSAs are prevalent in patients with insufficient immunosuppression; thus, even patients with stable conditions after liver transplantation should be under optimized immunosuppression. However, the effect of re-augmenting immunosuppression therapy for patients with insufficient immunosuppression remains unclear. In this study, we investigated the long-term changes and the effects of immunosuppression (IS) re-augmentation on the DSA status.MethodsTwo DSA screenings were performed in 67 patients during long-term follow-up after liver transplantation. After the first screening, IS re-augmentation was performed in patients with consent. The effects of IS re-augmentation on the DSA status were analyzed using data of the serial DSA screenings. Negative conversion was defined as DSA positivity with MFI > 1000 converted to MFI < 1000. Improvement of DSA status was defined as either a 50% reduction of MFI or negative conversion.ResultsThe median interval between the first and second DSA screening was 50 months. Among 67 patients, 43 were positive for DSAs on the first screening. Among these 43 patients, 30 had minimal to no IS therapy at the time of the first screening. Among the 30 patients, IS re-augmentation was conducted in 19. A comparison between the patients with a re-augmented IS and those with a sustained minimized IS showed that the DSA levels significantly decreased in the former (63% (12/19) vs. 18% (2/11), p = 0.02).ConclusionsThe results of this study indicate that post-liver transplant IS re-augmentation had suppressive effects on the DSA status. However, the clinical significance of DSA-negative conversion and/or mean fluorescence intensity reduction needs to be further investigated through histological evaluation and/or graft survival during longer follow-up periods.     

Safety and Efficacy of a Steroid Avoidance Immunosuppression Regimen in Renal Transplant Patients With De Novo or Preformed Donor-Specific Antibodies: A Single-Center Study

Although interest in the role of donor-specific antibodies (DSAs) in kidney transplant rejection, graft survival, and histopathological outcomes is increasing, their impact on steroid avoidance or minimization in renal transplant populations is poorly understood. Primary outcomes of graft survival, rejection, and histopathological findings were assessed in 188 patients who received transplants between 2012 and 2015 at the Scripps Center for Organ Transplantation, which follows a steroid avoidance protocol. Analyses were performed using data from the United Network for Organ Sharing. Cohorts included kidney transplant recipients with de novo DSAs (dnDSAs; n = 27), preformed DSAs (pfDSAs; n = 15), and no DSAs (nDSAs; n = 146). Median time to dnDSA development (classes I and II) was shorter (102 days) than in previous studies. Rejection of any type was associated with DSAs to class I HLA (P < .05) and class II HLA (P < .01) but not with graft loss. Although mean fluorescence intensity (MFI) independently showed no association with rejection, an MFI >5000 showed a trend toward more antibody-mediated rejection (P < .06), though graft loss was not independently associated. Banff chronic allograft nephropathy scores and a modified chronic injury score were increased in the dnDSA cohort at 6 months, but not at 2 years (P < .001 and P < .08, respectively). Our data suggest that dnDSAs and pfDSAs impact short-term rejection rates but do not negatively impact graft survival or histopathological outcomes at 2 years. Periodic protocol post-transplant DSA monitoring may preemptively identify patients who develop dnDSAs who are at a higher risk for rejection.     

Clinical significance of low pre-transplant donor specific antibodies (DSA) in living donor kidney recipients with negative complement-dependent cytotoxicity crossmatches (CDCXM), and negative flow cytometry crossmatches (FLXM) – A single-center experience

BackgroundIt is controversial whether all donor-specific antibodies (DSA) detected by the solid-phase single antigen bead (SAB) assay negatively affect kidney transplantation outcomes. The study aimed to evaluate the possible clinical significance of low pre-transplant DSA in living donor kidney recipients. We analyzed a group of patients with HLA-A, B, and -DR DSA reactivities below a virtual crossmatch (VXM) value of 5000 MFI but with all VXM DSA reactivities at HLA-DQ, -DP, and -Cw, which were not typed routinely for donors prior to transplantation. We also investigated the incidence of persistent and de novo DSAs in available posttransplant SAB assays.MethodsFrom the historical cohort of living donor recipients transplanted between 2014 and 2018 at our center (n = 82), 55 patients met the inclusion criteria, namely: these patients were > 18 years old with non-HLA identical sibling donors, who were not desensitized, who had available pre-transplant SAB results, and who had negative both complement-dependent cytotoxicity crossmatch (CDCXM) and flow cytometry crossmatch (FLXM) results. An additional donor HLA typing, performed for all 55 recipients, identified donor additional HLA-DQ, -DP, and -Cw DSA reactivities. These patients were then divided by SAB reactivity into three groups: 1) those with DSA-positive reactivities; 2) those with non-donor-specific anti-HLA reactivities (NDSA); and, 3) those who were anti-HLA-negative. All these recipients were followed for three years and checked for their de novo or persistent DSA.ResultsIn the studied cohort, DSA-positive, NDSA reactive, and anti-HLA negative recipients constituted 33%, 36%, and 31% of 55 patients, respectively. Non-routinely considered pre-transplant HLA-DQ, -DP, and -Cw DSA-positive reactivities were shown in as many as 78% of DSA-positive cases (group 1) with the lowest MFI value of 319 to DP4 and the highest MFI of 5767 to DQ2. Of the pre-transplant HLA-A, B, and -DR DSA reactivities, only -DR52 DSA reactivity reached the highest MFI value of 2191. These detected DSAs did not reduce the mean estimated glomerular filtration rate (eGFR) values and did not increase the incidence of proteinuria in recipients. While the 3-year graft survival was lower in the DSA-positive group (94.4%) with one recipient who lost kidney transplant, the difference was not significantly different (p = 0.7) from the NDSA (100%) and negative (100%) groups. In terms of the incidence of de novo acute antibody-mediated rejection (AMR) at three years after transplantation, no case has been reported in the cohort. This may suggest that low DSA-positive recipients do not experience higher rejection rate. However, DSA-positive recipients had a tendency for a higher frequency of C4d deposits in peritubular capillaries (PTC) and de novo DSA.ConclusionOur 3-year follow-up of patients with low pre-transplant DSA found no association with a deterioration in graft function and worse graft survival. Furthermore, we did not observe an increase in AMR in our patients with low DSA. A larger cohort and a longer follow-up period may be needed to evaluate the tendency of low DSA-positive recipients towards the higher incidence of C4d deposits in PTC and/or de novo DSA.     

Sputum trypsin-like protease activity relates to clinical outcome in cystic fibrosis

BackgroundIn cystic fibrosis (CF) airways excessive levels of serine trypsin-like proteases (TLPs) activate the epithelial sodium channel (ENaC) resulting in airways dehydration and promotion of mucus secretion. Despite this the relationship of TLP activity and clinical outcome has not been studied.MethodsWe analysed supernatant (sol) prepared from CF sputum from adult CF patients in two study cohorts (29 and 33 samples, respectively). Protease activities were determined by measuring the hydrolysis of peptide-based substrates or by ELISA. Lung function was assessed by spirometry (FEV₁). Mortality data was retrospectively obtained and time in months until death or transplantation used for subsequent survival analysis.ResultsTLP activity inversely correlated with percent predicted FEV₁ (r = −0.4, p = 0.03) and was greater in individuals who did not survive beyond 5-years from the time of sample collection. A Kaplan-Meier analysis demonstrated significantly reduced survival (p = 0.04) for individuals with high TLP activity [hazard ratio (HR) of 7.21 per log unit TLP activity (p = 0.03)]. In contrast, neutrophil elastase displayed no significant associations with lung function or patient survival. Similar findings were evident in the second study cohort.ConclusionsSputum TLP activity may represent a novel non-invasive biomarker and/or therapeutic target for CF lung disease.     

Preformed C1q-binding Donor-specific Anti-HLA Antibodies and Graft Function After Kidney Transplantation

Background

De novo complement-binding donor-specific anti-human leukocyte antigen antibodies (DSAs) are reportedly associated with an increased risk of kidney graft failure, but there is little information on preformed complement-binding DSAs. This study investigated the correlation between preformed C1q-binding DSAs and medium-term outcomes in kidney transplantation (KT).

Factors in childhood associated with lung function decline to adolescence in cystic fibrosis

BackgroundDespite improvements in general health and life expectancy in people with cystic fibrosis (CF), lung function decline continues unabated during adolescence and early adult life.MethodsWe examined factors present at age 5-years that predicted lung function decline from childhood to adolescence in a longitudinal study of Australasian children with CF followed from 1999 to 2017.ResultsLung function trajectories were calculated for 119 children with CF from childhood (median 5.0 [25%-75%=5.0–5.1]) years) to early adolescence (median 12.5 [25%-75%=11.4–13.8] years). Lung function fell progressively, with mean (standard deviation) annual change -0.105 (0.049) for forced vital capacity (FVC) Z-score (p<0.001), -0.135 (0.048) for forced expiratory volume in 1-second (FEV₁) Z-score (p<0.001), -1.277 (0.221) for FEV₁/FVC% (p<0.001), and -0.136 (0.052) for forced expiratory flow between 25% and 75% of FVC Z-score (p<0.001). Factors present in childhood predicting lung function decline to adolescence, in multivariable analyses, were hospitalisation for respiratory exacerbations in the first 5-years of life (FEV₁/FVC p = 0.001, FEF_25–75 p = 0.01) and bronchoalveolar lavage neutrophil elastase activity (FEV₁/FVC% p = 0.001, FEV₁ p = 0.05, FEF_25–75 p = 0.02). No examined factor predicted a decline in the FVC Z-score.ConclusionsAction in the first 5-years of life to prevent and/or treat respiratory exacerbations and counteract neutrophilic inflammation in the lower airways may reduce lung function decline in children with CF, and these should be targets of future research.     

Impact of the Presence and Duration of Donor-Specific Antibodies on Renal Function

Background

Although anti-human leukocyte antigen (HLA) antibodies (DSA) is associated with graft loss, 3 things remain unclear: whether the duration and strength of DSA affect renal function; what mean fluorescence intensity (MFI) cut-off should be used; and whether the DSA effect is additive in case of multiple DSAs.

Methods

A study was made of 63 patients who received living donor kidney transplants with clonal deletion protocol and were followed up for 18 months with reduced doses of immunosuppressants. DSA was tested for monthly, using Luminex Mixed and Single Antigen beads (One Lambda, Inc., Canoga Park, CA, USA). Decrease of estimated glomerular filtration rate (eGFR) was obtained at baseline and 18 months after transplantation. Association of renal damage and DSAs was compared using several DSA models with several MFI cut-offs.

Results

Additive DSA models always showed better association with renal damage than comprehensive models. When calculating the DSA effect in additive models, “proxy-area under the curve” (AUC)—a triangular approximation of the actual AUC—showed better association with renal damage than did DSA duration (R² = 0.105 vs 0.087). Adjusting for other factors, 27% of the variation of GFR change was explained by proxy-AUC. No significant change of association occurred if the MFI cut-off level changed from 1000 to 3000.

Conclusion

Our results support the association of DSA with development of longitudinal renal damage. The clinical interpretation may be similar at MFI cut-offs of 1000, 2000, and 3000. An additive DSA effect may be expected in patients with multiple DSAs. Our study suggests the importance of frequently checking for DSA and reducing their MFI value to minimize renal damage by the antibodies.     

Long-term outcomes of sensitized lung transplant recipients after peri-operative desensitization

The Toronto Lung Transplant Program has been using a peri-operative desensitization regimen of plasma exchange, intravenous immune globulin, and antithymocyte globulin in order to accept donor-specific antibody (DSA)-positive lung transplants safely since 2008. There are no long-term data on the impact of this practice on allograft survival or the development of chronic lung allograft dysfunction (CLAD). We extended our prior study to include long-term follow-up of 340 patients who received lung transplants between January 1, 2008 and December 31, 2011. We compared allograft survival and CLAD-free survival among patients in three cohorts: DSA-positive, panel reactive antibody (PRA)-positive/DSA-negative, and unsensitized at the time of transplant. The median follow-up time in this extension study was 6.7 years. Among DSA-positive, PRA-positive/DSA-negative, and unsensitized patients, the median allograft survival was 8.4, 7.9, and 5.8 years, respectively (p = .5908), and the median CLAD-free survival was 6.8, 7.3, and 5.7 years, respectively (p = .5448). This follow-up study confirms that long-term allograft survival and CLAD-free survival of patients who undergo DSA-positive lung transplants with the use of our protocol do not differ from other lung transplant recipients. Use of protocols such as ours, therefore, may improve access to transplant for sensitized candidates.     

Pulmonary artery pressure in cystic fibrosis adults: Characteristics,clinical correlates and long-term follow-up

BackgroundWe examined pulmonary artery pressure (PAP) characteristics of CF adults, studied clinical correlates and long-term survival.MethodsComprehensive clinical data were collected and Doppler echocardiography was used to estimate PAP in 109 stable CF adults and 50 healthy controls.ResultsCF patients had lower day and night-time oxygen status, elevated CRP and BNP, and elevated PAP (27.7(13.2, 62.8) mmHg patients v 17.9(11.3, 30.9) mmHg controls, p < 0.001). Even patients with mild pulmonary disease had raised PAP. PAP measurements strongly correlated with arterial partial pressure of oxygen (PaO₂, r = − 0.673, p < 0.001), and FEV₁ percentage predicted (FEV₁%, r = − 0.642, p < 0.001) which were both independent predictors of PAP. At 10 year follow up PAP measurements were related to survival but FEV₁% and PaO₂ were both stronger predictors of death.ConclusionsPAP is raised in CF adults and correlates with pulmonary disease severity. Unlike PaO₂ and FEV₁%, it does not appear to be an independent prognostic marker.     

Effect of C1q-binding donor-specific anti-HLA antibodies on the clinical outcomes of patients after renal transplantation: A systematic review and meta-analysis

BackgroundComplement-binding donor-specific human leukocyte antigen (HLA) antibodies in kidney recipients have been associated with a higher risk of allograft rejection and loss. The objective of this meta-analysis was to investigate the correlation between C1q-binding donor-specific antibodies (DSAs) and clinical outcomes in kidney transplantation (KT) recipients.MethodsWe conducted systematic searches in the PubMed, EMBASE, and the Cochrane Library databases to identify all studies since inception to August 2021 that compared clinical outcomes between C1q + DSA and C1q-DSA patients who underwent KT. Data were independently extracted by two reviewers who assessed the risk of bias. Data were summarized with fixed effects or random effects models according to heterogeneity. We assessed clinical outcomes including graft loss, rejection, delayed graft function (DGF), and all-cause patient death.ResultsTwenty-six studies with a total of 1337 patients were included: 485 with C1q-binding DSAs, and 850 without C1q-binding DSAs. Compared with the C1q-DSA group, the C1q + DSA group had significant increases in antibody-mediated rejection (AMR) (relative risk [RR] = 2.09, 95% confidence interval [CI], 1.53–2.86; P < 0.00001), graft loss (RR = 2.40, 95% CI, 1.66–3.47; P < 0.00001), and death (RR = 3.13, 95% CI, 1.06–9.23; P = 0.04). The C1q + DSA and C1q-DSA groups did not show significant differences in T-cell-mediated rejection, acute rejection, acute cellular rejection, mixed rejection, or DGF.ConclusionThe findings of this systematic review suggest that C1q + DSA KT have a higher risk of AMR, graft loss, and death compared with C1q-DSA patients. Monitoring C1q-binding DSAs allows risk stratification of recipients and guides physician management.     

Flow cytometry crossmatching to investigate kidney-biopsy-proven,antibody-mediated rejection in patients who develop de novo donor-specific antibodies

IntroductionThe appearance of de novo donor-specific anti-human leukocyte antigen antibodies (dnDSAs) after kidney transplantation is independently associated with poor long-term allograft outcomes. The objective of the present study was to evaluate the predictive value of a flow cytometry crossmatching (FC-XM) assay after the appearance of dnDSAs related to antibody-mediated allograft rejection (ABMR) after kidney transplantation.Materials and methodsA total of 89 recipients with dnDSAs after transplantation were included. The crossmatching results were compared with the dnDSA profile (the mean fluorescence intensity (MFI), the complement-binding activity, and the IgG subclass profile) and the biopsy's morphological features.ResultsOf the 89 patients, 59 (66%) were positive in an FC-XM assay, 17 (19%) had complement-binding DSAs, 55 (62%) were positive for IgG1 and/or IgG3 in a solid phase assay, and 45 (51%) had morphological biopsy features linked to ABMR.ConclusionAn FC-XM assay was unable to discriminate between cases with or without ABMR on biopsy findings; it had a low positive predictive value (<70%) and a low negative positive predictive value (<42.9%), taking into account the sensitivity of our assay (limit of detection: DSAs with an MFI >3000). In this context, the height of the MFI of the dnDSAs might be enough for a high positive predictive value for ABMR and additional testing for complement binding activity can remain optional.     

Chronic Stenotrophomonas maltophilia infection and exacerbation outcomes in cystic fibrosis

BackgroundChronic Stenotrophomonas maltophilia infection is a risk factor for pulmonary exacerbation in cystic fibrosis (CF) but its impact on subsequent clinical outcomes is unknown. The aim of this study was to determine the effect of chronic S. maltophilia infection and associated antimicrobial therapy on the recovery of forced expiratory lung volume in 1 s (FEV₁) following pulmonary exacerbation.MethodsThis was a retrospective cohort study of patients with CF followed at The Hospital for Sick Children and St. Michael's Hospital from 1997 to 2008. The primary outcome was the difference in FEV₁ percent predicted from baseline to follow up after a pulmonary exacerbation. Secondary outcomes for the effect of antimicrobial therapy included time to subsequent exacerbation.ResultsThere were 1667 pulmonary exacerbations in 440 CF patients. Patients with chronic S. maltophilia infection did not recover their baseline FEV₁ following 31% of exacerbations and had an overall mean FEV₁ decline of 1.84% predicted after exacerbation. Older (p = 0.02), female (p = 0.02) patients with lower BMI z score (p = 0.002) and Burkholderia cepacia complex infection (p = 0.005), but not chronic S. maltophilia infection (p = 0.86), had a greater decrease in follow up FEV₁% pred compared to baseline. The number of days of antibiotic therapy against S. maltophilia during a pulmonary exacerbation was not associated with a significant difference in the FEV₁ recovery (p = 0.69) or with a longer time to subsequent pulmonary exacerbation (p = 0.56).ConclusionsAlthough CF patients experience a significant decline in lung function following exacerbation, chronic S. maltophilia infection and associated antimicrobial therapy do not affect subsequent lung function recovery.     

Correlation of Luminex-Based Single Antigen Based Results With Complement-Dependent Cytotoxicity Crossmatch and Flow Cytometry Crossmatch Results: A Single-Center Experience From Istanbul

BackgroundThis study aimed to retrospectively investigate the correlation of mean Class I donor-specific antibody (DSA) intensity values detected in Luminex-based techniques with the results of complement-dependent cytotoxicity crossmatch (CDC-XM) and flow cytometry crossmatch (FC-XM) results.MethodsA total of 335 patients with kidney failure and their living donors whose CDC-XM, FC-XM, and single antigen based (SAB) tests were studied between 2018 and 2020 for transplant preparation from living donor candidates were included in the study. Patients were divided into 4 groups according to their mean fluorescence intensity (MFI) values of SAB assay.ResultsAnti-HLA antibodies (class I and/or class II) were detected using SAB in 91.6% patients included in the study (MFI >1000). Class I DSA was positive in 34.8% of patients with anti-HLA antibodies. When CDC-XM and FC-XM results were evaluated in the 4 groups separated according to MFI values, 3 patients with DSA MFI <1000 had negative CDC-XM and T-B-FC-XM results. Of 32 patients with DSA-MFI between 1000 and 3000, 93.75% (n = 30) had T-B-FC-XM or CDC-XM-negative results, and 6.25% (n = 2) had B-FC-XM-positive results. The CDC-XM, T, and B-FC-XM were negative in all 17 patients with DSA-MFI between 3000 and 5000. Our results showed that MFI >5834 DSA values were significantly correlated with positive T-FC-XM (P < .001), and MFI >6016 values were significantly correlated with positive CDC-XM (P = .002). In addition, MFI values >5000 were associated with both CDC-XM and FC-XM in our study.ConclusionsThe MFI values >5000 correlated with both CDC-XM and FC-XM.     

Clinical Significance of C3d Assay in Kidney Transplant Recipients With Donor-Specific Anti–Human Leukocyte Antigen Antibodies

BackgroundAntibody-mediated rejection (AMR) is a major cause of allograft loss in kidney transplant. Although donor-specific anti–human leukocyte antigen antibody (DSA) is a key cause of AMR, not all patients with DSA are diagnosed as having AMR and show poor allograft outcomes. This study aimed to evaluate clinical significance of C3d-binding activity in patients with DSA identified by single-antigen bead (SAB) assay.MethodsA total of 168 recipients screened for DSA from 2015 to 2018 were enrolled. Among them, 52 patients had DSA confirmed by SAB assay. Sera were tested using the C3d assay on Luminex platform. AMR was defined by kidney allograft biopsy results using Banff 2015 criteria.ResultsOf 52 patients, C3d-binding DSAs were detected in 22 patients (42.3%). Indication allograft biopsy was performed in 35 patients, with 31 (88.6%) diagnosed as having AMR. Patients with C3d-binding DSA had more class II SAB-DSA (73.3% vs 100%, P = .015) and showed significantly higher mean (SD) fluorescence intensity of class II SAB-DSA than the C3d-binding DSA(?) group (9606.7 [6096.6] vs 1921.0 [1483.8], P < .001). There was a positive correlation in the highest mean fluorescence intensity between class II SAB-DSA and class II C3d-binding DSA (r = 0.70, P < .001). Patients with C3d-binding DSA showed worse death-censored graft survival than those with non-C3d-binding DSA (P = .023).ConclusionsThis study showed that presence of C3d-binding DSA was significantly associated with allograft loss in SAB-DSA–positive patients. Further trials are warranted.     

Ibrutinib suppresses alloantibody responses in a mouse model of allosensitization

BackgroundIbrutinib is a Bruton's tyrosine Kinase (BTK) antagonist that inhibits B cell receptor (BCR) signaling. Complete BTK deficiency is associated with absence of B-cells. Ibrutinb is currently approved by FDA for treatment of B-cell malignancies, including Waldenström macroglobulinaemia. We recently carried out studies to determine if ibrutinib could modify alloantibody responses.Materials and methodsA mouse model of allogenic sensitization using a C57BL/6 mouse as the recipient of a skin allograft from an HLA-A2 transgenic mouse was utilized to examine the effects of ibrutinib on alloantibody responses and B cell effector functions. Donor-specific antibody (DSA) levels were measured in a flow-cytometric antibody binding assay. Splenic T and B cell subsets and plasma cells were analyzed in flow cytometry.ResultsControl mice developed peak levels of DSA IgM at day 14 PTx while the ibrutinib treated mice had significantly lower levels of DSA IgM (p = 0.0047). Control mice developed HLA.A2-specific IgG antibodies at day 14 (230 ± 60 MFI) and reached peak levels at day 21 (426 ± 61 MFI). In contrast, mice in the treatment group had low levels of HLA.A2-specific IgG at day 14 (109 ± 59 MFI, p = 0.004) and day 21 (241 ± 86 MFI, p = 0.003). FACS analysis found a reduction of B220⁺ or CD19⁺ B cell population (p < 0.05). In addition, ibrutinib attenuated recall DSA IgG responses to re-sensitization (p < 0.05) and reduced CD38⁺ CD138⁺ plasma cells (p < 0.05) in the spleens.ConclusionsIbrutinib is effective in suppressing alloantibody responses through blocking BTK-mediated BCR signaling, leading to reduction of B cells and short-lived plasma cells in the spleens. Use of ibrutinib may provide benefits to HLA-sensitized transplant patients for alloantibody suppression.     

Detection of donor-specific HLA antibodies: A retrospective observation in 350 renal transplant cases

BackgroundThe main objective of this study was to determine the results of the cell-based assay (CDC-XM and FC-XM), and correlate with the results of solid phase assay (L-SAB).MethodsIn this retrospective study, 350 prospective renal transplant recipients were tested for the presence of HLA antibodies by CDC-XM, FC-XM and L-SAB screening with their corresponding donor.ResultsT-cell-FC-XM showed a sensitivity of 71.43% and a specificity of 91.50% for detecting class I L-SAB (+), while B-cell-FCXM showed a sensitivity of 94.94% and a specificity of 61.99% for detecting class II L-SAB (+). On the other hand, T-CDC-XM showed a sensitivity of 32.14% and a specificity of 98.64% for detecting class I L-SAB (+), while B-CDC-XM showed a sensitivity of 44.30% and a specificity of 94.83% for detecting class II L-SAB (+). In this study, the results indicated that DSA class I MFI value of 2845 and above significantly (p ≤0.001) correlated with T-cell-FC-XM positivity, while MFI value of 4585 and above (p ≤0.001) showed strong predictive accuracy of a positive T-cell-CDC-XM. However, DSA class II MFI cut-off of 1988 and above significantly (p ≤0.001) correlated with B-cell-FC-XM positivity, while MFI value of 5986 and above (p ≤0.001) showed strong predictive accuracy of a positive B-cell-CDC-XM.ConclusionsOur study showed that CDC-XM has poor sensitivity, while FC-XM has poor specificity to detect DSA. L-SAB has good correlation with T-cell-FC-XM (p < 0.0001) but not with B-cell-FC-XM (P = 0.31). DSA strength >2845 and > 1988 significantly correlated with T-cell-FC-XM positivity and B-cell-FC-XM positivity, respectively. While, a MFI value of >4585 and > 5986 significantly correlated with T-cell-CDC-XM positivity and B-cell-CDC-XM positivity, respectively. These MFI cut-off values could serve as a surrogate marker for CDC-XM and FC-XM tests and may help in resolving the limitations of cell-based techniques. In conclusion, we found that L-SAB is more sensitive and specific than CDC-XM and FC-XM and therefore may be used as a test of choice.     

Club cell secretory protein and lung function in children with cystic fibrosis

BackgroundClub cell secretory protein (CC16) exerts anti-inflammatory functions in lung disease. We sought to determine the relation of serum CC16 deficits and genetic variants that control serum CC16 to lung function among children with cystic fibrosis (CF).MethodsWe used longitudinal data from CF children (EPIC Study) with no positive cultures for Pseudomonas aeruginosa prior to enrollment. Circulating levels of CC16 and an inflammatory score (generated from CRP, SAA, calprotectin, G-CSF) were compared between participants with the lowest and highest FEV₁ levels in adolescence (LLF and HLF groups, respectively; N = 130-per-group). Single nucleotide variants (SNVs) in the SCGB1A1, EHF-APIP loci were tested for association with circulating CC16 and with decline of FEV₁ and FEV₁/FVC% predicted levels between ages 7–16 using mixed models.ResultsCompared with the HLF group, the LLF group had lower levels of CC16 (geometric means: 8.2 vs 6.5 ng/ml, respectively; p = 0.0002) and higher levels of the normalized inflammatory score (-0.21 vs 0.21, p = 0.0007). Participants in the lowest CC16 and highest inflammation tertile had the highest odds for having LLF (p<0.0001 for comparison with participants in the highest CC16 and lowest inflammation tertile). Among seven SNVs associated with circulating CC16, the top SNV rs3741240 was associated with decline of FEV₁/FVC and, marginally, FEV₁ (p = 0.003 and 0.025, respectively; N = 611 participants, 20,801 lung function observations).ConclusionsSerum CC16 deficits are strongly associated with severity of CF lung disease and their effects are additive with systemic inflammation. The rs3741240 A allele is associated with low circulating CC16 and, possibly, accelerated lung function decline in CF.     

Clinical effect of lumacaftor/ivacaftor in F508del homozygous CF patients with FEV1 ≥ 90% predicted at baseline

ObjectiveThe first available CFTR modulator combination for homozygous F508del patients, lumacaftor/ivacaftor, has not been tested in patients with percentage predicted (pp)FEV₁ > 90 in the phase III trials. The objective of this study is to share real life experience about treatment results in this group.MethodsIn this retrospective observational study, patients aged 6 years or older starting on lumacaftor/ivacaftor in standard care were in strict follow up. For these patients, data were obtained about FEV₁, BMI, CFQ-R and sweat chloride before start and after 6 months of treatment, and data about FEV₁ and BMI were recorded every 3 months. Exacerbations were recorded continuously.ResultsWe identified 40 patients with a ppFEV₁ ≥ 90 at the start of lumacaftor/ivacaftor who had been in follow up for at least 12 months. After 12 months, ppFEV₁ was unchanged, whereas mean absolute change in BMI was +0.88 (p = 0.001) with a mean change in SDS for BMI of +0.26 (p = 0.014). Mean CFQ-R overall score at 6 months improved by 2.6% (p = 0.004) and mean decrease in sweat chloride was -27.3 mEq/L (p = 0.000). Exacerbation rate declined from 1.03 to 0.53/person/year (p = 0.003). One patient discontinued treatment in the first 12 months because of progression of CFRLD, two paused treatment but resumed later.ConclusionHomozygous F508del patients starting lumacaftor/ivacaftor at ppFEV₁ ≥ 90 improved significantly in nutritional status, sweat chloride levels and exacerbation rate, but did not respond in ppFEV₁. Treatment is well tolerated in this patient group. These effects make it worth considering to treat this group of patients with lumacaftor/ivacaftor.