Longitudinal monitoring of Torque Teno virus DNAemia in kidney transplant recipients correlates with long-term complications of inadequate immunosuppression.

Optimization of individual immunosuppression, which reduces the risks of both graft loss and patients' death, is considered the best approach to improve long-term outcomes of renal transplantation. Torque Teno Virus (TTV) DNAemia has emerged as a potential biomarker reflecting the depth of therapeutic immunosuppression during the initial year post-transplantation. However, its efficacy in long-term monitoring remains uncertain. In a cohort study involving 34 stable kidney transplant recipients and 124 healthy volunteers, we established lower and upper TTV DNAemia thresholds (3.75-5.1 log10 cp/mL) correlating with T-cell activatability, antibody response against flu vaccine, and risk for subsequent serious infections or cancer over 50 months. Validation in an independent cohort of 92 recipients confirmed that maintaining TTV DNAemia within this range in >50% of follow-up time points was associated with reduced risks of complications due to inadequate immunosuppression, including de novo DSA, biopsy-proven antibody-mediated rejection, graft loss, infections, or cancer. Multivariate analysis highlighted "in-target" TTV DNAemia as the sole independent variable significantly linked to decreased risk for long-term complications due to inadequate immunosuppression (odds ratio [OR]: 0.27 [0.09-0.77]; p = 0.019). Our data suggest that the longitudinal monitoring of TTV DNAemia in kidney transplant recipients could help preventing the long-term complications due to inadequate immunosuppression.

A prospective observational study for justification, safety, and efficacy of a third dose of mRNA vaccine in patients receiving maintenance hemodialysis.

The level of protection achieved by the standard two doses of COVID-19 mRNA vaccines in patients receiving maintenance hemodialysis (MHD) remains unclear. To study this we used the French Renal Epidemiology and Information Network (REIN) Registry to compare the incidence and severity of 1474 cases of COVID-19 diagnosed in patients receiving MHD after none, one or two doses of vaccine. Vaccination significantly reduce COVID-19 incidence and severity, but 11% of patients infected after two doses still died. Lack of vaccinal protection in patients naïve for SARS-CoV-2 could be due to defective Tfh response [38% of patients with negative spike-specific CD4+ T-cell interferon gamma release assay] and failure to generate viral neutralizing titers of anti-spike receptor binding domain (RBD) IgGs (63% of patients with titer at or under 997 BAU/ml, defining low/no responders) after two doses of vaccine. To improve protection, a third dose of vaccine was administered to 75 patients [57 low/no responders, 18 high responders after two doses] from the ROMANOV cohort that prospectively enrolled patients receiving MHD vaccinated with BNT162b2 (Pfizer). Tolerance to the third dose was excellent. High responders to two doses did not generate more anti-RBD IgGs after three doses but had more side effects. Importantly, 31 (54%) of low/no responders to two doses reached neutralizing titers of anti-RBD IgGs after three doses. A positive interferon gamma release assay and/or suboptimal titer of anti-RBD IgGs after two doses were the only predictive variables for response to three doses in multivariate analysis. Thus, the standard scheme of vaccination insufficiently protects patients receiving MHD. Anti-RBD IgG and specific CD4+ T-cell response after two doses can guide personalized administration of the third dose, which improves the humoral response of SARS-CoV-2-naïve patients receiving MHD.

Predictive factors of a viral neutralizing humoral response after a third dose of COVID-19 mRNA vaccine.

Kidney transplant recipients (KTRs) have reduced ability to mount adequate antibody response after two doses of the COVID-19 mRNA vaccine. French health authorities have allowed a third booster dose (D3) for KTRs, but their response is heterogeneous and tools able to discriminate the responders are lacking. Anti-RBD IgG titers (chemiluminescence immunoassay), spike-specific cellular responses (IFN-γ-releasing assay, IGRA), and in vitro serum neutralization of the virus (the best available correlate of protection), were evaluated 7-14 days after the second dose (D2) of BNT162b2 vaccine in 93 KTRs. Among the 73 KTRs, whose serum did not neutralize SARS-CoV-2 in vitro after D2, 14 (19%) acquired this capacity after D3, and were considered as "responders." Exploratory univariate analysis identified short time from transplantation and high maintenance immunosuppression as detrimental factors for the response to D3. In addition, any of the presence of anti-RBD IgGs and/or positive IGRA after D2 was predictive of response to D3. By contrast, none of the KTRs with both a negative serology and IGRA responded to D3. In summary, routinely available bioassays performed after D2 allow identifying KTRs that will respond to a booster D3. These results pave the way for the personalization of vaccination strategy in KTRs.

Evolution of humoral lesions on follow-up biopsy stratifies the risk for renal graft loss after antibody-mediated rejection treatment.

BACKGROUND: The standard-of-care protocol, based on plasma exchanges, high-dose intravenous immunoglobulin and optimization of maintenance immunosuppression, can slow down the evolution of antibody-mediated rejection (AMR), but with high interindividual variability. Identification of a reliable predictive tool of the response to AMR treatment is a mandatory step for personalization of the follow-up strategy and to guide second-line therapies. METHODS: Interrogation of the electronic databases of 2 French university hospitals (Lyon and Strasbourg) retrospectively identified 81 renal transplant recipients diagnosed with AMR without chronic lesions (cg score ≤1) at diagnosis and for whom a follow-up biopsy had been performed 3-6 months after initiation of therapy. RESULTS: The evolution of humoral lesions on follow-up biopsy (disappearance versus persistence versus progression) correlated with the risk for allograft loss (logrank test, P = .001). Patients with disappearance of humoral lesions had ∼80% graft survival at 10 years. The hazard ratio for graft loss in multivariate analysis was 3.91 (P = .04) and 5.15 (P = .02) for patients with persistence and progression of lesions, respectively. The non-invasive parameters classically used to follow the intensity of humoral alloimmune response (evolution of immunodominant DSA mean fluorescence intensity) and the decline of renal graft function (estimated glomerular filtration rate decrease and persistent proteinuria) showed little clinical value to predict the histological response to AMR therapy. CONCLUSION: We conclude that invasive monitoring of the evolution of humoral lesions by the mean of follow-up biopsy performed 3-6 months after the initiation of therapy is an interesting tool to predict long-term outcome after AMR treatment.

Missing Self-Induced Activation of NK Cells Combines with Non-Complement-Fixing Donor-Specific Antibodies to Accelerate Kidney Transplant Loss in Chronic Antibody-Mediated Rejection.

BACKGROUND: Binding of donor-specific antibodies (DSAs) to kidney allograft endothelial cells that does not activate the classic complement cascade can trigger the recruitment of innate immune effectors, including NK cells. Activated NK cells contribute to microvascular inflammation leading to chronic antibody-mediated rejection (AMR). Recipient NK cells can also trigger antibody-independent microvascular inflammation by sensing the absence of self HLA class I molecules ("missing self") on allograft endothelial cells. This translational study investigated whether the condition of missing self amplifies DSA-dependent NK cell activation to worsen chronic AMR. METHODS AND RESULTS: Among 1682 kidney transplant recipients who underwent an allograft biopsy at Lyon University Hospital between 2004 and 2017, 135 fulfilled the diagnostic criteria for AMR and were enrolled in the study. Patients with complement-fixing DSAs identified by a positive C3d binding assay (n=73, 54%) had a higher risk of transplant failure (P=0.002). Among the remaining patients with complement-independent chronic AMR (n=62, 46%), those in whom missing self was identified through donor and recipient genotyping exhibited worse allograft survival (P=0.02). In multivariable analysis, only proteinuria (HR: 7.24; P=0.01) and the presence of missing self (HR: 3.57; P=0.04) were independent predictors for transplant failure following diagnosis of chronic AMR. Cocultures of human NK cells and endothelial cells confirmed that addition of missing self to DSA-induced NK cell activation increased endothelial damage. CONCLUSIONS: The assessment of missing self at the time of diagnosis of chronic AMR identifies patients at higher risk for kidney transplant failure.

The ROMANOV study found impaired humoral and cellular immune responses to SARS-CoV-2 mRNA vaccine in virus-unexposed patients receiving maintenance hemodialysis.

Patients on maintenance hemodialysis (MHD), which are at high risk of infection by SARS-CoV-2 virus and death due to COVID-19, have been prioritized for vaccination. However, because they were excluded from pivotal studies and have weakened immune responses, it is not known whether these patients are protected after the "standard" two doses of mRNA vaccines. To answer this, anti-spike receptor binding domain (RBD) IgG and interferon gamma-producing CD4+ and CD8+ specific-T cells were measured in the circulation 10-14 days after the second injection of BNT162b2 vaccine in 106 patients receiving MHD (14 with history of COVID-19) and compared to 30 healthy volunteers (four with history of COVID-19). After vaccination, most (72/80, 90%) patients receiving MHD naïve for the virus generated at least one type of immune effector, but their response was weaker and less complete than that of healthy volunteers. In multivariate analysis, hemodialysis and immunosuppressive therapy were significantly associated with absence of both anti-RBD IgGs and anti-spike CD8+ T cells. In contrast, previous history of COVID-19 in patients receiving MHD correlated with the generation of both types of immune effectors anti-RBD IgG and anti-spike CD8+ T cells at levels similar to healthy volunteers. Patients receiving MHD naïve for SARS-Cov-2 generate mitigated immune responses after two doses of mRNA vaccine. Thus, the good response to vaccine of patients receiving MHD with a history of COVID-19 suggest that these patients may benefit from a third vaccine injection.

Improved cell signaling analysis by biofunctionalized nanospheres and imaging flow cytometry.

The analysis of immune cell signaling is critical for the understanding of the biology and pathology of the immune system, and thus a mandatory step for the development of efficient biomarkers and targeted therapies. Phosflow, which has progressively replaced the traditional western blot approach, relies on flow cytometry to analyze various signaling pathways at a single-cell level. This technique however suffers a lack of sensitivity largely due to the low signal/noise ratio that characterizes cell signaling analysis. In this study, we describe a new technique, which combines the use of biofunctionalized nanospheres (i.e., synthetic particulate antigens, SPAg) to stimulate the immune cells in suspension and imaging flow cytometry to identify homogenously-stimulated cells and quantify the activity of the chosen signaling pathway in selected subcellular regions of interest. Using BCR signaling as model, we demonstrate that SIBERIAN (SPAg-assIsted suB-cEllulaR sIgnaling ANalysis) allows assessing immune cell signaling with unprecedented sensitivity and specificity.

Significance of PR3-ANCA positivity in eosinophilic granulomatosis with polyangiitis (Churg-Strauss).

OBJECTIVES: Only a third of patients with eosinophilic granulomatosis with polyangiitis (EGPA) are ANCA-positive, mainly directed against MPO. ANCA directed against PR3 are rarely found in EGPA. We aimed to examine the significance of PR3-ANCA in EGPA. METHODS: We set up a retrospective European multicentre cohort including 845 patients. Baseline characteristics and outcomes were analysed and compared according to ANCA status. RESULTS: ANCA status was available for 734 patients: 508 (69.2%) ANCA-negative, 210 (28.6%) MPO-ANCA and 16 (2.2%) PR3-ANCA. At baseline, PR3-ANCA patients, compared with those with MPO-ANCA and ANCA-negative, less frequently had active asthma (69% vs 91% and 93%, P = 0.003, respectively) and peripheral neuropathy (31% vs 71% and 47%, P < 0.0001), more frequently had cutaneous manifestations (63% vs 38% and 34%, P = 0.03) and pulmonary nodules (25% vs 10% and 8%, P = 0.046), and lower median eosinophil count (1450 vs 5400 and 3224/mm3, P < 0.0001). Vasculitis relapse-free survival was shorter for PR3-ANCA (hazard ratio 6.05, P = 0.005) and MPO-ANCA patients (hazard ratio 1.88, P = 0.0002) compared with ANCA-negative patients. CONCLUSION: PR3-ANCA EGPA patients differ from those with MPO-ANCA and negative ANCA, and share clinical features with granulomatosis with polyangiitis. This suggests that PR3-ANCA EGPA could be a particular form of PR3-ANCA-associated vasculitis.

Lung Diseases in Inflammatory Myopathies.

Lung involvement is the leading cause of mortality in inflammatory myopathy. A careful assessment of clinical and serologic manifestations especially myositis-associated autoantibodies allows precise classification of the different phenotypes of inflammatory myopathy and stratification of the risk of lung involvement. About three out of four patients with inflammatory myopathy develop interstitial lung disease (ILD), which represents the main cause of morbidity and mortality. In patients with a confirmed diagnosis of inflammatory myopathy, the approach to the diagnosis of ILD includes assessment of clinical and functional severity, evaluation of the high-resolution computed tomography pattern of disease, which often suggests nonspecific interstitial pneumonia or organizing pneumonia. Bronchoalveolar lavage to rule out infection is often performed; however, video-assisted thoracoscopic lung biopsy is now generally discouraged, unless malignancy is suspected. The so-called antisynthetase syndrome characterized by the combination of mechanics' hands, Raynaud' phenomenon, myositis often mild or absent, and presence of one of the anti-tRNA synthetase antibodies is associated with a 70% risk of ILD, especially in subjects with antibodies other than anti-Jo1 antibodies (i.e., anti-PL7 or -PL12 antibodies). Treatment depends on both severity and progression of ILD, often including a combination of corticosteroids and immunosuppressive therapy. Rituximab-based regimen has showed promising results in retrospective studies for the management of refractory or rapidly progressive forms of ILD. Clinical trials are ongoing to evaluate the actual efficacy of this strategy on mortality related to lung disease. Secondary pulmonary complications of inflammatory myopathy include opportunistic infections, aspiration pneumonia, pneumomediastinum, ventilatory failure due to diaphragmatic muscular weakness, drug-induced pneumonitis, and rarely pulmonary hypertension.