Blood MMP-9 measured at 2 years after lung transplantation as a prognostic biomarker of chronic lung allograft dysfunction

BACKGROUND

Long-term outcomes of lung transplantation (LTx) remain hampered by chronic lung allograft dysfunction (CLAD). Matrix metalloproteinase 9 (MMP-9) is a secretory endopeptidase identified as a key mediator in fibrosis processes associated with CLAD. The objective of this study was to investigate whether plasma MMP9 levels may be prognostic of CLAD development.

METHODS

Participants were selected from the Cohort in Lung Transplantation (COLT) for which a biocollection was associated. We considered two time points, year 1 (Y1) and year 2 (Y2) post-transplantation, for plasma MMP-9 measurements. We analysed stable recipients at those time points, comparing those who would develop a CLAD within the 2 years following the measurement to those who would remain stable 2 years after.

RESULTS

MMP-9 levels at Y1 were not significantly different between the CLAD and stable groups (230 ng/ml vs. 160 ng/ml, p = 0.4). For the Y2 analysis, 129 recipients were included, of whom 50 developed CLAD within 2 years and 79 remained stable within 2 years. MMP-9 plasma median concentrations were higher in recipients who then developed CLAD than in the stable group (230 ng/ml vs. 118 ng/ml, p = 0.003). In the multivariate analysis, the Y2 MMP-9 level was independently associated with CLAD, with an average increase of 150 ng/ml (95% CI [0-253], p = 0.05) compared to that in the stable group. The Y2 ROC curve revealed a discriminating capacity of blood MMP-9 with an area under the curve of 66%.

CONCLUSION

Plasmatic MMP-9 levels measured 2 years after lung transplantation have prognostic value for CLAD.

Aortic valve replacement for aortic stenosis in France – influence of centers' volumes on TAVR adoption rate and outcomes

Aims

Over the last decade, transcatheter aortic valve replacement (TAVR) became extensively used, now being the recommended as first line procedure for aortic valve replacement (AVR) in selected patients' populations. It is unknown whether TAVR adoption rate and variability in outcomes is influenced by centers' volume.

Methods

From a French administrative hospital-discharge database, we collected all AVR performed in France between 2007 and 2019. Centers were stratified to terciles based on their annual SAVR per year per center during 2007–2009 (“pre TAVR era”).

Results

There was 218,489 AVRs (153,747 SAVR and 74,732 TAVR) performed in 46 centers between 2007–2019. Number of total AVR and even more so number of number of TAVR significantly and linearly increased from 2007 to 2019 in all terciles but faster in the high volume tercile (+17, +17 and +31 AVR/center/year in the low, middle and high terciles respectively, P [ANCOVA]<0.001; +11, + 19 and +33 TAVR/center/year in the low, medium and high tercile respectively, P [ANCOVA] <0.00, Figure 1). The age of patients underwent TAVR remained grossly unchanged in all three terciles, however, the Charlson index declined from 2010 to 2019 (from 1.35±1.42 to 0.65±1.04, from 1.21±1.40 to 0.65±1.05 and from 1.53±1.58 to 0.81±1.21, in the low, middle and high terciles, P for trend <0.001, 0.021, and <0.001, respectively). Charlson score in the years 2017–2019, was higher in the high than middle and low terciles (0.87±1.22, 0.76±1.11 and 0.65±1.04, respectively, P<0.0001). The in-hospital mortality rate for TAVR significantly declined from 2010 to 2019 for TAVR in all terciles (from 8.3% to 2.1%, from 7.5% to 2.5% and from 8.2% to 2.1% for low, middle and high TAVR terciles, respectively; p for trend = 0.002, 0.001 and <0.001, respectively, Figure 2). Average mortality in 2017–2019 was similar in all terciles (2.3%, 2.5% and 2.2% for low, middle and high terciles, respectively, P=0.47). After adjusting for age, sex and Charlson score, mortality was higher in the low tercile compared with middle and high terciles (OR 1.15, P<0.001, confidence interval [CI] 1.0–1.2, and OR 1.18, P<0.001, CI 1.1–1.2, respectively).

Conclusions

From 2007 to 2019 total AVR linearly increased, mostly due to increase in TAVR, irrespective of centers' volume, but increase rate was higher in high volume centers. A constant decline in patients risk profile, with a striking decrease in mortality rate, was observed in all volume terciles. High-volume centers patients' have higher risk profile, with adjusted mortality slightly lower than medium and low volume centers.

Funding Acknowledgement

Type of funding sources: None.

[stent thrombosis : A won battle ? (data from the France PCI registry)]

GOAL

The aim of the study is to assess the incidence, risk factors and prognosis of definite stent thrombosis (ST) at 1 year in the France PCI multicenter prospective registry.

PATIENTS AND METHODS

Only patients who underwent coronary angioplasty with at least one stent implantation between 1^st January 2014 and 31 December 2019 were included. The population was separated into 2 groups: the "ST" group with stent thrombosis and the "control" group without stent thrombosis.

RESULTS

35,435 patients were included. 256 patients (0.72%) presented a ST at 1 year. The rate of ST decreased significantly in acute coronary syndrome (1.5% in 2014 vs. 0.73% in 2019; p = 0.05) but not in chronic coronary syndrome (0.46% in 2014 vs 0.40%; p = 0.98). The risk factors are young age (65.8 years vs 68.2; p = 0.002), clinical context (35.27% vs 16.68%; p = 0.0001), diabetes (35.2 % vs 26.4%; p = 0.002), renal failure (11.7% vs 8%; p = 0.009) and history of coronary angioplasty (28.63% vs 21.86%; p = 0.009) and peripheral arterial disease (14.5% vs 10.1%; p = 0.021), LV dysfunction (37% vs 27.5%; p = 0.003), mean length (39.6 mm vs 31, 7mm; p <0.0001) and the mean number of stents per procedure (1.9 vs 1.6; p <0.0001), a TIMI flow ≤1 pre procedure (21.5% vs 12.4%; p <0.0001) and an intrastent restenosis (11% vs 6%; p <0.0001). The 1-year mortality of the ST group was significantly higher than that of the control group (19.14% vs 5.82%; p <0.0001).

CONCLUSION

Since 2014, the incidence of ST at 1 year has been decreasing but remains stuck at a floor level of 0.54% in 2019. The battle for ST seems to have been partly won and its risk factors well identified, but its mortality is still high.

Right ventricular dysfunction before transcatheter aortic valve implantation: incidence, predictive factors and prognostic impact

Background

Right ventricular dysfunction (RVD) is considered to be a late marker of advanced aortic stenosis (AS) and is associated with poor prognosis. Currently. there are conflicting data on the impact of RVD on clinical outcomes in patients with severe AS treated with TAVI. Moreover, few studies have studied the evolution (recovery or persistence) of RVD and its prognostic impact.

Objectives

To assess the incidence and predictive factors of RVD before TAVI, its prognostic impact and its evolution after TAVI.

Methods

All patients treated with TAVI for severe AS were included in a prospective single center database. Only patients who had a quantitative assessment of RV including Tricuspid Annular Plane Systolic Excursion (TAPSE) and/or doppler tissue imaging-derived tricuspid lateral annular systolic velocity (S') measurements, were eligible to this study. RVD was defined by a TAPSE &lt;17 mm or S' &lt;9.5 cm/s if TAPSE was not available.

Results

Between May 2014 and April 2019, 503 patients with RV function evaluation were included. Incidence of RVD before TAVI was 18.7%. Predictors of RVD were diabetes (P=0.03), atrial fibrillation (P=0.001), altered left ventricular ejection fraction (P&lt;0.0001), left ventricular dilatation (P=0.007), and previous cardiac surgery (P=0.002). Long-term survival was altered in patients with RVD before TAVI as compared to those without RVD (HR 1.97, 95% CI: 1.1–3.4, P=0.01). One year after TAVI, 58.7% of patients with baseline RVD had a normal RV function and had similar outcome as compared to those without RVD at baseline. In contrast, patients with persistent RVD had the worst prognosis.

Conclusions

RVD is not rare and has a deleterious prognostic impact in patients treated by TAVI. Recovery of normal RV function is frequent after TAVI whereas persistence of RVD is associated with poor outcomes.

Funding Acknowledgement

Type of funding sources: None.

Overexpression of the MSK1 Kinase in Patients With Chronic Lung Allograft Dysfunction and Its Confirmed Role in a Murine Model

BACKGROUND

Chronic lung allograft dysfunction (CLAD) and its obstructive form, the obliterative bronchiolitis (OB), are the main long-term complications related to high mortality rate postlung transplantation. CLAD treatment lacks a significant success in survival. Here, we investigated a new strategy through inhibition of the proinflammatory mitogen- and stress-activated kinase 1 (MSK1) kinase.

METHODS

MSK1 expression was assessed in a mouse OB model after heterotopic tracheal allotransplantation. Pharmacological inhibition of MSK1 (H89, fasudil, PHA767491) was evaluated in the murine model and in a translational model using human lung primary fibroblasts in proinflammatory conditions. MSK1 expression was graded over time in biopsies from a cohort of CLAD patients.

RESULTS

MSK1 mRNA progressively increased during OB (6.4-fold at D21 posttransplantation). Inhibition of MSK1 allowed to counteract the damage to the epithelium (56% restoration for H89), and abolished the recruitment of MHCII+ (94%) and T cells (100%) at the early inflammatory phase of OB. In addition, it markedly decreased the late fibroproliferative obstruction in allografts (48%). MSK1 inhibitors decreased production of IL-6 (whose transcription is under the control of MSK1) released from human lung fibroblasts (96%). Finally, we confirmed occurrence of a 2.9-fold increased MSK1 mRNA expression in lung biopsies in patients at 6 months before CLAD diagnosis as compared to recipients with stable lung function.

CONCLUSIONS

These findings suggest the overall interest of the MSK1 kinase either as a marker or as a potential therapeutic target in lung dysfunction posttransplantation.

Assessment of long-term structural deterioration of transcatheter aortic bioprosthetic valves

Background

The durability of transcatheter aortic bioprosthetic valves is a crucial issue in the context of extension of indications in younger and lower-risk patients, but data are scarce, especially beyond 5 years of follow-up. This study sought to evaluate the incidence of structural valve degeneration (SVD) 5 to 10 years post-procedure.

Methods

Demographic, procedural, and in-hospital outcome data on patients who underwent transcatheter aortic valve implantation (TAVI) from 2002 to 2014 were obtained from our prospective institutional database. Patients in whom echocardiographic data were available both at baseline and 5 years post-TAVI were included. Clinical and echocardiographic follow-up were performed on site annually. Hemodynamic SVD was determined according to European task force committee guidelines.

Results

A total of 208 patients (82.5±7.6 years of age; 53% female) with paired post-procedure and late echocardiographic follow-up (median 5.3 years, range 5 to 11.4 years) were included. Eleven (5.3%) patients were treated with a self-expandable valve and 197 (94.7%) patients with a balloon-expandable valve. Mean aortic valve gradient and effective aortic valve area remained unchanged during follow-up. There were 2 cases (1.0%) of severe SVD 6 and 7 years after implantation requiring redo-TAVI. There were 4 cases (1.9%) of moderate SVD (mean 6.0 years post-implantation; range 5 to 7 years).

Conclusions

Our data do not demonstrate any alarm on transcatheter aortic valve durability. Careful prospective assessment in younger and lower risk patients and comparison with surgical bioprosthetic valves are required to further assess long-term durability of transcatheter valves.

Funding Acknowledgement

Type of funding source: None

Dry heat and microwave-generated steam protocols for the rapid decontamination of respiratory personal protective equipment in response to COVID-19-related shortages

BACKGROUND

In the wake of the SARS-CoV-2 pandemic and unprecedented global demand, clinicians are struggling to source adequate access to personal protective equipment. Respirators can be in short supply, though are necessary to protect workers from SARS-CoV-2 exposure. Rapid decontamination and reuse of respirators may provide relief for the strained procurement situation.

METHOD

In this study, we investigated the suitability of 70°C dry heat and microwave-generated steam (MGS) for reprocessing of FFP2/N95-type respirators, and Type-II surgical face masks. Staphylococcus aureus was used as a surrogate as it is less susceptible than enveloped viruses to chemical and physical processes.

RESULTS

We observed >4 log10 reductions in the viability of dry S. aureus treated by dry heat for 90 min at 70°C and >6 log10 reductions by MGS for 90 s. After 3 reprocessing cycles, neither process was found to negatively impact the bacterial or NaCl filtration efficiency of the respirators that were tested. However, MGS was incompatible with Type-II surgical masks tested, as we confirmed that bacterial filtration capacity was completely lost following reprocessing. MGS was observed to be incompatible with some respirator types due to arcing observed around some types of metal nose clips and by loss of adhesion of clips to the mask.

CONCLUSION

Considering the advantages and disadvantages of each approach, we propose a reprocessing personal protective equipment/face mask workflow for use in medical areas.

Predictive Value for Outcome and Evolution of Geriatric Parameters after Transcatheter Aortic Valve Implantation

OBJECTIVES

To identify parameters of comprehensive geriatric assessment (CGA) CGA including ABCDEF score, a multidomain frailty assessment, associated with poor outcome after TAVI and to assess the evolution of CGA parameters at 6-months follow-up.

DESIGN

one-year monocentric prospective cohort study.

SETTING

Departments of geriatric medicine and cardiology in Rouen University Hospital, Normandy, France.

PARTICIPANTS

all patients over 70, selected for TAVI by a multidisciplinary "heart team".

MEASUREMENTS

8-areas CGA was performed before TAVI and at 6-months follow-up. Poor outcome was defined as decrease in 1 BADL or unplanned readmission at 6 months or death within the first year after TAVI. Geriatric characteristics associated with poor outcome were assessed by logistic regression with surgical scores as bivariable. Geriatric characteristics were compared between baseline and 6-months follow-up.

RESULTS

114 patients (mean age 85.8±5.3 years) were included. Mean EuroSCORE was 19.1±10.6%. Poor outcome occurred in 57(50.0%) patients. Loss of one BADL (OR:1.66, 95CI[1.11-2.48]), decrease in IADL (OR:1.41, 95CI[1.14-1.74]), in plasmatic albumin (OR:1.10, 95CI[1.01-1.20]), in MMSe (OR:1.13, 95CI[1.02-1.26]), low walking speed (OR:1.53, 95CI[1.01-2.33]) and ABCDEF score ≥2 (OR:1.63, 95CI[1.09-2.42]) were independently associated with poor outcome. In survivors with complete follow-up (n=80), most geriatric parameters were maintained 6 months after TAVI, but IADL decreased (5.6±1.9 to 4.9±2.2, p<0.001). MMSe increased in patients with previous cognitive impairments whereas it decreased in those without (p<0.001).

CONCLUSION

CGA parameters are independently associated with poor outcome after TAVI. These parameters, but IADL, are maintained at 6 months and course of the MMSe depends on previous cognitive status.

Blood CD9+ B cell, a biomarker of bronchiolitis obliterans syndrome after lung transplantation

Bronchiolitis obliterans syndrome is the main limitation for long-term survival after lung transplantation. Some specific B cell populations are associated with long-term graft acceptance. We aimed to monitor the B cell profile during early development of bronchiolitis obliterans syndrome after lung transplantation. The B cell longitudinal profile was analyzed in peripheral blood mononuclear cells from patients with bronchiolitis obliterans syndrome and patients who remained stable over 3 years of follow-up. CD24^hi CD38^hi transitional B cells were increased in stable patients only, and reached a peak 24 months after transplantation, whereas they remained unchanged in patients who developed a bronchiolitis obliterans syndrome. These CD24^hi CD38^hi transitional B cells specifically secrete IL-10 and express CD9. Thus, patients with a total CD9⁺ B cell frequency below 6.6% displayed significantly higher incidence of bronchiolitis obliterans syndrome (AUC = 0.836, PPV = 0.75, NPV = 1). These data are the first to associate IL-10-secreting CD24^hi CD38^hi transitional B cells expressing CD9 with better allograft outcome in lung transplant recipients. CD9-expressing B cells appear as a contributor to a favorable environment essential for the maintenance of long-term stable graft function and as a new predictive biomarker of bronchiolitis obliterans syndrome-free survival.

P3664Infective endocarditis after transcatheter aortic valve implantation, a comparison with endocarditis occurring in surgical aortic prosthesis and native aortic valve patients

Background

Infective endocarditis is rare but serious. Epidemiology is well known in standard population and surgical valve patients (Pts). The recent development of Transcatheter Aortic Valve Implantation (TAVI) raises new questions about endocarditis in this population.

Purpose

The aim of this study was to assess outcomes of endocarditis in TAVI Pts and to compare the results to surgical aortic valve (SV) owners and native aortic valve (NV) patients.

Methods

We included all patients hospitalized in our institution and presenting with endocarditis after TAVI between 2012 and 2018. We compared these patients to those discussed within the “endocarditis team” and presenting with endocarditis located on SV or on NV.

Results

A total of 34 TAVI Pts were included and compared to a population of 45 SV and 68 NV Pts. TAVI Pts were older (83.1±1.1 yrs, vs 73.3±1.7 and 66.0±1.7, respectively; p<0.001) and had a higher Charlson score (6.2±0.4, vs 5.6±0.4 and 4.1±0.3; p<0.001). TAVI Pts underwent more frequently invasive procedures during the 6 months prior to the diagnosis of endocarditis (38.2%, vs 11.4 and 8.8%; p<0.001). They had less incidence of a new valvular murmur (0%, vs 28.9 and 33.8%; p=0.001) and less heart failure symptoms (26.5%, vs 28.9 and 33.8%; p=0.007). Clinical complications were similar between the 3 groups and mortality was high and comparable at 1 year (29.2%, vs 36.4 and 29.7% p=0.730). However, TAVI Pts were more frequently re-hospitalized (41.2% vs 26.7% and 16.2%, p=0.02) and were treated less invasively (surgery or pacemaker extraction in 14.7% vs 35.6% and 42.6%, p=0.019). Only one TAVI Pt needed surgical aortic valve replacement.

Conclusion

Despite more frequent comorbidities, TAVI patients affected by infective endocarditis have the same mortality during the first year after diagnosis compared to SV and NV patients but are more often rehospitalized.

P907Respective pronostic value of the valvular aortic calcifications and the thoracic aorta calcifications in patients with and without low gradient aortic stenosis after TAVI

Background

Both the valvular aortic calcifications (VAC) and the thoracic aorta calcifications (TAC) have a prognostic impact in patients with aortic stenosis. Their respective prognostic values in patients with and without low gradient aortic stenosis (LGAS) remain unknown after TAVI.

Objectives

To assess the prognostic significance of VAC and TAC in patients with and without LGAS regarding cardiovascular mortality after 3 years follow-up.

Methods

The CAPRI-LGAS is an ancillary study of the C4CAPRI trial (NCT02935491) including 1282 consecutive TAVI patients. Calcifications were measured on pre-TAVI CT. The primary outcome was defined as cardiovascular mortality 3 years after TAVI.

Results

Among the 1282 patients, 397 (31%) had a LGAS. Compared to the other patients, LGAS patients were more prone to be men, younger, with atrial fibrillation, and lower left ventricular ejection fraction (LVEF), p<0.05 for all. No statistically significant difference was noticed for pulmonary systolic pressures, history of diabetes, chronic respiratory disease, renal insufficiency or peripheral vascular disease. VAC was lower in LGAS compared to non-LGAS patients (1.05 cm3±0.7 vs 0.75 cm3±0.5), p<0.001, the contrary was noticed for TAC, (3.1 cm3±3 vs 3.7 cm3±3.7), p=0.011. After 3 years follow-up, 227 (17.7%) patients died from cardiovascular causes; respectively 85 (21.4%) and 142 (16.1%) patients with and without LGAS, p=0.02. In univariate analysis, in LGAS patients each increase of 1cm3 TAC was associated with cardiovascular mortality while VAC was not, respectively Hazard Ratio (HR) 1.07 and confidence interval (CI) (1.023–1.119) p=0.003, and HR 0.822 CI (0.523–1.292), p=0.39. In patients without LGAS both TAC and VAC were associated with mortality, respectively HR 1.054 CI (1.006–1.104), p=0.028 and HR 1.363 CI (1.092–1.701), p=0.006. Multivariate analysis was adjusted for TAC, VAC, age, gender, atrial fibrillation, and LVEF. In LGAS patients TAC but not VAC was still a predictor of cardiovascular mortality, respectively HR 1.092 CI (1.031–1.158), p=0.003, and HR 0.743 CI (0.464–1.191), p=0.21. In patients without LGAS TAC was no more associated with cardiovascular mortality while VAC was, respectively HR 1.306 CI (1.024–1.666), p=0.031, and HR 1.038 CI (0.985–1.094), p=0.161. When further adjusting on pulmonary systolic pressures, history of diabetes, chronic respiratory disease, renal insufficiency and peripheral vascular disease, the results remained similar ie in LGAS patients, TAC HR 1.090 CI (1.022–1.162), p=0.009 while in patients without LGAS VAC HR 1.377 CI (1.049–1.809), p=0.021.

Conclusions

The present study shows that VAC and TAC involve different prognostic information in patients with and without LGAS after TAVI. While VAC may be a marker of early and periprocedural mortality and aortic regurgitation in non-LGAS patients, TAC may continue to be harmful and increase afterload in patients with LGAS whom LVEF is often impaired.

4069From first in man transcatheter aortic valve implantation, a 15-year experience

Background

Since the first-in-man transcatheter aortic valve implantation (TAVI) performed in 2002, the number of procedures has dramatically increased. However, long-term data regarding outcome and valve durability remain poor.

Purpose

We aimed to evaluate the evolution of 30-day outcomes over years and long-term mortality and valve durability after TAVI.

Methods

All consecutive patients presenting with severe symptomatic aortic stenosis treated by TAVI in our center were included prospectively. Clinical and echocardiographic follow-up was performed at 30 days and annually thereafter. Survival curves were constructed using Kaplan-Meier analysis. We also evaluated valve durability according to the European standardized definition of structural valve deterioration.

Results

Between 2002 and 2018, 1530 consecutive patients underwent TAVI including 1285 (84.0%) patients via a femoral approach. A balloon-expandable transcatheter heart valve was predominantly used (1421 patients; 92.9%). The annual transfemoral approach rate increased progressively to reach 93.3%. Age of patients remained stable over time with a global mean age of 83.7±6.5 years old. Logistic EuroSCORE decreased from 49.2±8.2% to 14.3±8.6% (p<0.0001). Thirty-day mortality dramatically decreased below 3% since 2015 and was 0% in 2018. Similarly, major vascular complications decreased from 50.0% in the first year to less than 1% since 2017 (p=0.001). The length of hospital-stay progressively shortened up to a median of 2 days in 2018. The Kaplan-Meier survival estimation was 82.3%, 60.3%, 33.0%; 11.7% and 8.9% respectively at 1, 3, 5, 8 and 10 years. On long-term follow-up the mean aortic gradient remained unchanged (Figure), and only five patients presented a severe prosthetic valve deterioration. Among them, four patients successfully benefited from a valve in valve TAVI procedure. The competing risk analysis at 10 years estimates risk for severe and moderate-or-severe valve deterioration of 1.9±0.9% and 4.3±1.3% respectively.

TEE mean transaortic gradient

Conclusions

Long-term (up to 10 years) follow-up of our large pioneer series of patients treated by TAVI shows a dramatic improvement of outcomes and no warning signs of valve deterioration suggesting very encouraging valve durability, using predominantly, a balloon expandable prosthesis. Further studies are warranted to study valve durability after TAVI before extension to lower risk patients.

CD9+ Regulatory B Cells Induce T Cell Apoptosis via IL-10 and Are Reduced in Severe Asthmatic Patients

CD9 was recently identified as a marker of murine IL-10-competent regulatory B cells. Functional impairments or defects in CD9⁺ IL-10-secreting regulatory B cells are associated with enhanced asthma-like inflammation and airway hyperresponsiveness. In mouse models, all asthma-related features can be abrogated by CD9⁺ B cell adoptive transfer. We aimed herein to decipher the profiles, features, and molecular mechanisms of the regulatory properties of CD9⁺ B cells in human and mouse. The profile of CD9⁺ B cells was analyzed using blood from severe asthmatic patients and normal and asthmatic mice by flow cytometry. The regulatory effects of mouse CD9⁺ B cells on effector T cell death, cell cycle arrest, apoptosis, and mitochondrial depolarization were determined using yellow dye, propidium iodide, Annexin V, and JC-1 staining. MAPK phosphorylation was analyzed by western blotting. Patients with severe asthma and asthmatic mice both harbored less CD19⁺CD9⁺ B cells, although these cells displayed no defect in their capacity to induce T cell apoptosis. Molecular mechanisms of regulation of CD9⁺ B cells characterized in mouse showed that they induced effector T cell cycle arrest in sub G0/G1, leading to apoptosis in an IL-10-dependent manner. This process occurred through MAPK phosphorylation and activation of both the intrinsic and extrinsic pathways. This study characterizes the molecular mechanisms underlying the regulation of CD9⁺ B cells to induce effector T cell apoptosis in mice and humans via IL-10 secretion. Defects in CD9⁺ B cells in blood from patients with severe asthma reveal new insights into the lack of regulation of inflammation in these patients.

High circulating CD4+CD25hiFOXP3+ T-cell sub-population early after lung transplantation is associated with development of bronchiolitis obliterans syndrome

BACKGROUND

Chronic bronchiolitis obliterans syndrome (BOS) remains a major limitation for long-term survival after lung transplantation. The immune mechanisms involved and predictive biomarkers have yet to be identified. The purpose of this study was to determine whether peripheral blood T-lymphocyte profile could predict BOS in lung transplant recipients.

METHODS

An in-depth profiling of CD4⁺ and CD8⁺ T cells was prospectively performed on blood cells from stable (STA) and BOS patients with a longitudinal follow-up. Samples were analyzed at 1 and 6 months after transplantation, at the time of BOS diagnosis, and at an intermediate time-point at 6 to 12 months before BOS diagnosis.

RESULTS

Although no significant difference was found for T-cell compartments at BOS diagnosis or several months beforehand, we identified an increase in the CD4⁺CD25^hiFoxP3⁺ T-cell sub-population in BOS patients at 1 and 6 months after transplantation (3.39 ± 0.40% vs 1.67 ± 0.22% in STA, p < 0.001). A CD4⁺CD25^hiFoxP3⁺ T-cell threshold of 2.4% discriminated BOS and stable patients at 1 month post-transplantation. This was validated on a second set of patients at 6 months post-transplantation. Patients with a proportion of CD4⁺CD25^hiFoxP3⁺ T cells up to 2.4% in the 6 months after transplantation had a 2-fold higher risk of developing BOS.

CONCLUSIONS

This study is the first to report an increased proportion of circulating CD4⁺CD25^hiFoxP3⁺ T cells early post-transplantation in lung recipients who proceed to develop BOS within 3 years, which supports its use as a BOS predictive biomarker.

Increased degradation of ATP is driven by memory regulatory T cells in kidney transplantation tolerance

Regulatory T cells were recently proposed as the central actor in operational tolerance after renal transplantation. Tolerant patients harbor increased FoxP3hi memory Treg frequency and increased demethylation in the Foxp3 Treg-specific demethylated region when compared to stable kidney recipients and exhibit greater memory Treg suppressive capacities and higher expression of the ectonucleotidase CD39. However, in this particular and unique situation the mechanisms of action of Tregs were not identified. Thus, we analyzed the ability of memory Tregs to degrade extracellular ATP in tolerant patients, healthy volunteers, and patients with stable graft function under immunosuppression and determined the role of immunosuppressive drugs on this process. The conserved proportion of memory Tregs leads to the establishment of a pro-tolerogenic balance in operationally tolerant patients. Memory Tregs in tolerant patients display normal capacity to degrade extracellular ATP/ADP. In contrast, memory Tregs from patients with stable graft function do not have this ability. Finally, in vitro, immunosuppressive drugs may favor the lower proportion of memory Tregs in stable patients, but they have no effect on CD39-dependent ATP degradation and do not explain memory Treg lack of extracellular ATP/ADP degradation ability. Thus, intrinsic active regulatory mechanisms may act long after immunosuppressive drug arrest in operationally tolerant patients and may contribute to kidney allograft tolerance via the maintenance of CD39 Treg function.

Blood Gene Expression Predicts Bronchiolitis Obliterans Syndrome

Bronchiolitis obliterans syndrome (BOS), the main manifestation of chronic lung allograft dysfunction, leads to poor long-term survival after lung transplantation. Identifying predictors of BOS is essential to prevent the progression of dysfunction before irreversible damage occurs. By using a large set of 107 samples from lung recipients, we performed microarray gene expression profiling of whole blood to identify early biomarkers of BOS, including samples from 49 patients with stable function for at least 3 years, 32 samples collected at least 6 months before BOS diagnosis (prediction group), and 26 samples at or after BOS diagnosis (diagnosis group). An independent set from 25 lung recipients was used for validation by quantitative PCR (13 stables, 11 in the prediction group, and 8 in the diagnosis group). We identified 50 transcripts differentially expressed between stable and BOS recipients. Three genes, namely POU class 2 associating factor 1 (POU2AF1), T-cell leukemia/lymphoma protein 1A (TCL1A), and B cell lymphocyte kinase, were validated as predictive biomarkers of BOS more than 6 months before diagnosis, with areas under the curve of 0.83, 0.77, and 0.78 respectively. These genes allow stratification based on BOS risk (log-rank test p < 0.01) and are not associated with time posttransplantation. This is the first published large-scale gene expression analysis of blood after lung transplantation. The three-gene blood signature could provide clinicians with new tools to improve follow-up and adapt treatment of patients likely to develop BOS.