Deep learning-based phenotyping reclassifies combined hepatocellular-cholangiocarcinoma.

Primary liver cancer arises either from hepatocytic or biliary lineage cells, giving rise to hepatocellular carcinoma (HCC) or intrahepatic cholangiocarcinoma (ICCA). Combined hepatocellular- cholangiocarcinomas (cHCC-CCA) exhibit equivocal or mixed features of both, causing diagnostic uncertainty and difficulty in determining proper management. Here, we perform a comprehensive deep learning-based phenotyping of multiple cohorts of patients. We show that deep learning can reproduce the diagnosis of HCC vs. CCA with a high performance. We analyze a series of 405 cHCC-CCA patients and demonstrate that the model can reclassify the tumors as HCC or ICCA, and that the predictions are consistent with clinical outcomes, genetic alterations and in situ spatial gene expression profiling. This type of approach could improve treatment decisions and ultimately clinical outcome for patients with rare and biphenotypic cancers such as cHCC-CCA.

Interactions between free-living amoebae and Cryptosporidium parvum: an experimental study.

Free-Living Amebae (FLA) and Cryptosporidium oocysts occasionally share the same environment. From 2004 to 2016, Cryptosporidium was responsible for 60% of 905 worldwide waterborne outbreaks caused by protozoan parasites. The aim of this study was to evaluate interactions between C. parvum oocysts and two common FLAs (Acanthamoeba castellanii and Vermamoeba vermiformis) in a water environment. Encystment and survival of FLAs were evaluated by microscopy using trypan blue vital coloration. Oocysts were numerated on microscopy. Interactions were studied over time in conditions both unfavorable and favorable to phagocytosis. Potential phagocytosis was directly evaluated by several microscopic approaches and indirectly by numeration of microorganisms and oocyst infectivity evaluation. Occasional phagocytosis of C. parvum by FLAs was documented. However, oocyst concentrations did not decrease significantly, suggesting resistance of oocysts to phagocytosis. A temporary decrease of oocyst infectivity was observed in the presence of A. castellanii. The effect of these interactions on C. parvum infectivity is particularly interesting. The biofilm condition could favor the persistence or even the proliferation of oocysts over time. This study demonstrated interactions between C. parvum and FLAs. Further knowledge of the mechanisms involved in the decrease of oocyst infectivity in the presence of A. castellanii could facilitate the development of new therapeutic approaches.

Title: Interactions entre amibes libres et Cryptosporidium parvum : étude expérimentale. Abstract: Les amibes libres et les oocystes de Cryptosporidium partagent parfois le même environnement. Entre 2004 et 2016, Cryptosporidium a été responsable de 60 % des 905 épidémies d'origine hydrique dans le monde causées par des parasites protozoaires. Le but de cette étude était d'évaluer les interactions entre les oocystes de C. parvum et deux espèces d'amibes libres communes (Acanthamoeba castellanii et Vermamoeba vermiformis) en environnement aquatique. L'enkystement et la survie des amibes libres ont été évalués par microscopie en utilisant une coloration vitale au bleu trypan. Les oocystes ont été comptés au microscope. Les interactions ont été étudiées au cours du temps dans des conditions à la fois défavorables et favorables à la phagocytose. La phagocytose potentielle a été évaluée directement par plusieurs approches microscopiques et indirectement par la numération des micro-organismes et l'évaluation de l'infectiosité des oocystes. Une phagocytose occasionnelle de C. parvum par amibes libre a été documentée. Cependant, les concentrations d'oocystes n'ont pas diminué de manière significative, ce qui suggère une résistance des oocystes à la phagocytose. Une diminution temporaire de l'infectivité des oocystes a été observée en présence d'A. castellanii. L'effet de ces interactions sur l'infectiosité de C. parvum est particulièrement intéressant. La condition biofilm pourrait favoriser la persistance ou même la prolifération des oocystes de C. parvum au fil du temps. Cette étude a démontré des interactions entre C. parvum et amibes libres. Une meilleure connaissance des mécanismes impliqués dans la diminution de l'infectiosité des oocystes en présence d'A. castellanii pourrait faciliter le développement de nouvelles approches thérapeutiques.

Daratumumab for antibody-mediated rejection: Is it time to target the real culprit?

We report the case of a sensitized woman who underwent successful transplantation after a desensitization protocol, with an optically normal 8-day biopsy. At 3 months, she developed active antibody-mediated rejection (AMR) due to preformed donor-specific antibodies. It was decided to treat the patient with daratumumab, an anti-CD38 monoclonal antibody. The mean fluorescence intensity of donor-specific antibodies decreased, pathologic signs of AMR regressed, and kidney function returned to normal. A molecular assessment of biopsies was retrospectively performed. By doing so, regression of the molecular signature of AMR was evidenced between the second and third biopsies. Interestingly, the first biopsy revealed a gene expression profile of AMR, which helped retrospectively classify this biopsy as AMR, illustrating the relevance of molecular phenotyping of biopsy in high-risk situations such as desensitization.

Postsynaptic Protein Shank3a Deficiency Synergizes with Alzheimer's Disease Neuropathology to Impair Cognitive Performance in the 3xTg-AD Murine Model.

Synaptic loss is intrinsically linked to Alzheimer's disease (AD) neuropathology and symptoms, but its direct impact on clinical symptoms remains elusive. The postsynaptic protein Shank3 (SH3 and multiple ankyrin repeat domains) is of particular interest, as the loss of a single allele of the SHANK3 gene is sufficient to cause profound cognitive symptoms in children. We thus sought to determine whether a SHANK3 deficiency could contribute to the emergence or worsening of AD symptoms and neuropathology. We first found a 30%-50% postmortem loss of SHANK3a associated with cognitive decline in the parietal cortex of individuals with AD. To further probe the role of SHANK3 in AD, we crossed male and female 3xTg-AD mice modelling Aß and tau pathologies with Shank3a-deficient mice (Shank3Δex4-9). We observed synergistic deleterious effects of Shank3a deficiency and AD neuropathology on object recognition memory at 9, 12, and 18 months of age and on anxious behavior at 9 and 12 months of age in hemizygous Shank3Δex4-9-3xTg-AD mice. In addition to the expected 50% loss of Shank3a, levels of other synaptic proteins, such as PSD-95, drebrin, and homer1, remained unchanged in the parietotemporal cortex of hemizygous Shank3Δex4-9 animals. However, Shank3a deficiency increased the levels of soluble Aß42 and human tau at 18 months of age compared with 3xTg-AD mice with normal Shank3 expression. The results of this study in human brain samples and in transgenic mice are consistent with the hypothesis that Shank3 deficiency makes a key contribution to cognitive impairment in AD.SIGNIFICANCE STATEMENT Although the loss of several synaptic proteins has been described in Alzheimer's disease (AD), it remains unclear whether their reduction contributes to clinical symptoms. The results of this study in human samples show lower levels of SHANK3a in AD brain, correlating with cognitive decline. Data gathered in a novel transgenic mouse suggest that Shank3a deficiency synergizes with AD neuropathology to induce cognitive impairment, consistent with a causal role in AD. Therefore, treatment aiming at preserving Shank3 in the aging brain may be beneficial to prevent AD.

A seeding-based neuronal model of tau aggregation for use in drug discovery.

Intracellular accumulation of tau protein is a hallmark of Alzheimer's Disease and Progressive Supranuclear Palsy, as well as other neurodegenerative disorders collectively known as tauopathies. Despite our increasing understanding of the mechanisms leading to the initiation and progression of tau pathology, the field still lacks appropriate disease models to facilitate drug discovery. Here, we established a novel and modulatable seeding-based neuronal model of full-length 4R tau accumulation using humanized mouse cortical neurons and seeds from P301S human tau transgenic animals. The model shows specific and consistent formation of intraneuronal insoluble full-length 4R tau inclusions, which are positive for known markers of tau pathology (AT8, PHF-1, MC-1), and creates seeding competent tau. The formation of new inclusions can be prevented by treatment with tau siRNA, providing a robust internal control for use in qualifying the assessment of potential therapeutic candidates aimed at reducing the intracellular pool of tau. In addition, the experimental set up and data analysis techniques used provide consistent results in larger-scale designs that required multiple rounds of independent experiments, making this is a versatile and valuable cellular model for fundamental and early pre-clinical research of tau-targeted therapies.

Novel repertoire of tau biosensors to monitor pathological tau transformation and seeding activity in living cells.

Aggregates of the tau protein are a well-known hallmark of several neurodegenerative diseases, collectively referred to as tauopathies, including frontal temporal dementia and Alzheimer's disease (AD). Monitoring the transformation process of tau from physiological monomers into pathological oligomers or aggregates in a high-throughput, quantitative manner and in a cellular context is still a major challenge in the field. Identifying molecules able to interfere with those processes is of high therapeutic interest. Here, we developed a series of inter- and intramolecular tau biosensors based on the highly sensitive Nanoluciferase (Nluc) binary technology (NanoBiT) able to monitor the pathological conformational change and self-interaction of tau in living cells. Our repertoire of tau biosensors reliably reports i. molecular proximity of physiological full-length tau at microtubules; ii. changes in tau conformation and self-interaction associated with tau phosphorylation, as well as iii. tau interaction induced by seeds of recombinant tau or from mouse brain lysates of a mouse model of tau pathology. By comparing biosensors comprising different tau forms (i.e. full-length or short fragments, wild-type, or the disease-associated tau(P301L) variant) further insights into the tau transformation process are obtained. Proof-of-concept data for the high-throughput suitability and identification of molecules interfering with the pathological tau transformation processes are presented. This novel repertoire of tau biosensors is aimed to boost the disclosure of molecular mechanisms underlying pathological tau transformation in living cells and to discover new drug candidates for tau-related neurodegenerative diseases.

A Simple Molecular Tool for the Assessment of Kidney Transplant Biopsies.

BACKGROUND: The Banff Classification for Allograft Pathology recommendations for the diagnosis of kidney transplant rejection includes molecular assessment of the transplant biopsy. However, implementation of molecular tools in clinical practice is still limited, partly due to the required expertise and financial investment. The reverse transcriptase multiplex ligation-dependent probe amplification (RT-MLPA) assay is a simple, rapid, and inexpensive assay that permits simultaneous evaluation of a restricted gene panel using paraffin-embedded tissue blocks. The aim of this study was to develop and validate a RT-MLPA assay for diagnosis and classification of rejection. METHODS: A retrospective cohort of 220 kidney transplant biopsies from two centers, which included 52 antibody-mediated rejection, 51 T-cell-mediated rejection, and 117 no-rejection controls, was assessed. A 17-gene panel was identified on the basis of relevant pathophysiological pathways. A support vector machine classifier was developed. A subset of 109 biopsies was also assessed using the Nanostring Banff Human Organ Transplant panel to compare the two assays. RESULTS: The support vector machine classifier train and test accuracy scores were 0.84 and 0.83, respectively. In the test cohort, the F1 score for antibody-mediated rejection, T-cell-mediated rejection, and control were 0.88, 0.86, and 0.69, respectively. Using receiver-operating characteristic curves, the area under the curve for class predictions was 0.96, 0.89, and 0.91, respectively, with a weighted average at 0.94. Classifiers' performances were highest for antibody-mediated rejection diagnosis with 94% correct predictions, compared with 88% correct predictions for control biopsies and 60% for T-cell-mediated rejection biopsies. Gene expression levels assessed by RT-MLPA and Nanostring were correlated: r = 0.68, P < 0.001. Equivalent gene expression profiles were obtained with both assays in 81% of the samples. CONCLUSIONS: The 17-gene panel RT-MLPA assay, developed here for formalin-fixed paraffin-embedded kidney transplant biopsies, classified kidney transplant rejection with an overall accurate prediction ratio of 0.83. PODCAST: This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_04_10_CJN10100822.mp3.

Belatacept rescue conversion in kidney transplant recipients with vascular lesions (Banff cv score >2): a retrospective cohort study.

BACKGROUND: Immunosuppression in kidney transplant recipients with decreased graft function and histological vascular changes can be particularly challenging. The impact of a late rescue conversion to belatacept on kidney graft survival in this context has never been studied. METHODS: We report a bicentric retrospective cohort study comparing a calcineurin inhibitor (CNI) to belatacept switch versus CNI continuation in 139 kidney transplant recipients with histological kidney vascular damage (cv ≥2, g + cpt ≤1, i + t ≤1) and low estimated glomerular filtration rate (≤40 mL/min/1.73 m²). Primary outcome was death-censored graft survival. RESULTS: During the study follow-up, 10 graft losses (14.5%) occurred in the belatacept group (n = 69) versus 26 (37.1%) in the matched CNI group (n = 70) (P = .005). Death-censored graft survival was significantly higher in the belatacept group (P = .001). At 3 years, graft survival was 84.0% in the belatacept group compared with 65.1% in the control group. Continuing CNI was an independent risk factor for graft loss [hazard ratio (HR) 3.46; P < .005]. The incidence of cellular rejection after the conversion was low (4.3% in both groups) and not significantly different between groups (P = .84). Patients switched to belatacept developed significantly less donor-specific antibodies de novo. Belatacept was an independent risk factor for the occurrence of opportunistic infections (HR 4.84; P < .005). CONCLUSION: The replacement of CNI with belatacept in patients with decreased allograft function and vascular lesions is associated with an improvement in graft survival and represents a valuable option in a context of organ shortage. Caution should be exercised regarding the increased risk of opportunistic infection.

Kidney Transplant T Cell-Mediated Rejection Occurring After Anti-CD19 CAR T-Cell Therapy for Refractory Aggressive Burkitt-like Lymphoma With 11q Aberration: A Case Report.

Post-transplant lymphoproliferative disorder is a growing complication of kidney transplantation and is associated with a poor prognosis. Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy is an important new treatment option modifying the outcome of refractory hematological cancers. Here, we report the case of a 40-year-old kidney transplant recipient who developed a Burkitt-like lymphoma with 11q aberration 5 years after transplantation. After 3 unsuccessful lines of chemotherapy, it was decided to treat the patient with anti-CD19 CAR T cells as a salvage therapy. Three months after CAR T-cell infusion, she experienced a grade IIB T cell-mediated rejection with severe tubulitis (T3), slight interstitial inflammation (I1), and severe intimal arteritis (V2) with blood suffusion. Among T cells infiltrating the graft, some of them expressed the anti-CD19 CAR. CAR T cells within the graft and in blood samples were also detected by droplet digital polymerase chain reaction. Function of the kidney transplant improved after corticosteroid treatment and remained stable. However, lymphoma progressed, with a massive pulmonary mass leading to the patient's death 10 months after CAR T-cell infusion.

Correlation Between Microvascular Inflammation in Endomyocardial Biopsies and Rejection Transcripts, Donor-specific Antibodies, and Graft Dysfunction in Antibody-mediated Rejection.

BACKGROUND: The pathology-based diagnosis of cardiac antibody-mediated rejection (AMR) relies on the 2013 International Society for Heart and Lung Transplantation Working Formulation, in which microvascular inflammation (MVI) is considered as present or absent regardless of its extent. This work assessed the biological and clinical value of a semiquantitative evaluation of the extent of MVI in endomyocardial biopsies (EMBs). METHODS: We retrospectively graded the extent of MVI in 291 EMB from 291 patients according to a 4-point scale in which MVI scores of 0, 1, 2, and 3 represented 0%, 1%-10%, 11%-50%, and >50% of the myocardial area, respectively. We analyzed the association between the MVI score and tissue rejection molecular activity assessed by microarrays or reverse transcriptase multiplex ligation-dependent probe amplification, current pathology classification (pathologic AMR [pAMR]), anti-HLA donor-specific antibodies, and graft dysfunction. RESULTS: Overall, 172 (59.1%), 33 (11.4%), 42 (14.4%), and 44 (15.1%) EMB were given MVI scores of 0, 1, 2, and 3, respectively. pAMR1(H+) and pAMR2/3 categories were found to be heterogeneous in terms of MVI score. Acute cellular rejection grades did not influence the MVI score. In both molecular approaches, we observed a stepwise increase in the expression of AMR-related transcripts with increasing MVI scores, independent of the C4d or CD68 status (P < 0.001). Both the frequency and mean fluorescence intensity of donor-specific antibodies gradually increased with the MVI score (P < 0.001). Acute graft dysfunction was more frequent in MVI score 3 (P < 0.001). CONCLUSIONS: The intensity of MVI in EMB, based on a semiquantitative evaluation of its extent, has biological and clinical importance.

Prognostic Value of C4d Immunolabelling in Adult Patients With IgA Vasculitis.

Background and Objectives: Glomerular C4d deposits are associated the severity and outcomes of IgA nephropathy. Whether this holds true in immunoglobulin A vasculitis (IgAV) is not known. The main objective of the study was to analyze the prognostic value of glomerular C4d immunolabelling on kidney impairment in adults with IgAV. Design, Setting, Participants, Measurements: This retrospective cohort study included 120 adults with IgAV and a kidney biopsy performed between 1995 and 2018 in two French university hospital centers. All paraffin-embedded biopsies were reassessed according to Oxford classification. Immunofluorescence for C4d was performed in all cases. For analysis, patients were grouped according to positivity for C4d in the glomerular area. The main outcome was a composite endpoint of 50% increase in 24 h-proteinuria, or eGFR decrease by 50%, or kidney replacement therapy. Results: The median follow-up was 28.3 months. Twenty-three patients met the composite endpoint, 12 for kidney replacement therapy, 6 for an eGFR decrease >50% and 5 for a >50% increase in proteinuria. At time of biopsy, the median proteinuria was 1.9 g/24 h and the median eGFR 73.5 mL/min/1.73 m2. Among the 102 patients evaluable for C4d, 24 were positive on >30% glomeruli, mainly with a parieto-mesangial pattern. In this group, the initial proteinuria was more frequently nephrotic than in the C4d- group (60% vs. 33%, P = 0.039). Mesangial hypercellularity was more frequent in the C4d+ group (42% vs. 13%; P = 0.006) whereas macroscopic hematuria was more frequent in the C4d- group (18% vs. 0%; P = 0.03). After a median follow-up of 28 months, kidney survival did not differ according to C4d status. Conclusion: In a population of adult IgAV patients, glomerular positivity for C4d was associated with the severity of the kidney disease at presentation, but not with subsequent renal function deterioration.

Eculizumab in gemcitabine-induced thrombotic microangiopathy: experience of the French thrombotic microangiopathies reference centre.

BACKGROUND: Gemcitabine is a broadly prescribed chemotherapy, the use of which can be limited by renal adverse events, including thrombotic microangiopathy (TMA). METHODS: This study evaluated the efficacy of eculizumab, a monoclonal antibody targeting the terminal complement pathway, in patients with gemcitabine-induced TMA (G-TMA). We conducted an observational, retrospective, multicenter study in 5 French centres, between 2011 and 2016. RESULTS: Twelve patients with a G-TMA treated by eculizumab were included. The main characteristics were acute renal failure (100%), including stage 3 acute kidney injury (AKI, 58%) and renal replacement therapy (17%), hypertension (92%) and diffuse oedema (83%). Eculizumab was started after a median of 15 days (range 4-44) following TMA diagnosis. A median of 4 injections of eculizumab was performed (range 2-22). Complete hematological remission was achieved in 10 patients (83%) and blood transfusion significantly decreased after only one injection of eculizumab (median of 3 packed red blood cells (range 0-10) before treatment vs 0 (range 0-1) after one injection, P < 0.001). Two patients recovered completely renal function (17%), and 8 achieved a partial remission (67%). Compared to a control group of G-TMA without use of eculizumab, renal outcome was more favourable. At the end of the follow up, median eGFR was 45 vs 33 ml/min/1.73m2 respectively in the eculizumab group and in the control group. CONCLUSIONS: These results suggest that eculizumab is efficient on haemolysis and reduces transfusion requirement in G-TMA. Moreover, eculizumab may improve renal function recovery.

Intensity of de novo DSA detected by Immucor Lifecodes assay and C3d fixing antibodies are not predictive of subclinical ABMR after Kidney Transplantation.

De novo donor-specific antibodies (dnDSA) are associated with antibody-mediated rejection (ABMR) and allograft loss. We tested Immucor* (IM) Luminex Single-antigen beads (LSAB) assay and C3d-fixing antibodies in the setting of dnDSA and subclinical (s) ABMR. This retrospective multicentric study included 123 patients biopsied because of the presence of subclinical de novo DSA detected by One Lamda* Labscreen (MFI > 1000). In 112 patients, sera of the day of the biopsy were available and tested in a central lab with IM Lifecodes LSAB and C3d fixing antibodies assays. In 16 patients (14.3%), no DSA was detected using Immucor test. In 96 patients, at least one DSA was determined with IM. Systematic biopsies showed active sABMR in 30 patients (31.2%), chronic active sABMR in 17 patients (17.7%) and no lesions of sABMR in 49 KT recipients (51%). Intensitity criteria (BCM, BCR and AD-BCR) of DSA were not statistically different between these 3 histological groups. The proportion of patients with C3d-fixing DSA was not statistically different between the 3 groups and did not offer any prognostic value regarding graft survival. Performing biopsy for dnDSA could not be guided by the intensity criteria of IM LSAB assay. C3d-fixing DSA do not offer added value.

Pan-TRK Immunohistochemistry Is Highly Correlated With NTRK3 Gene Rearrangements in Salivary Gland Tumors.

AIMS: Secretory carcinoma (SC) is characterized by ETV6 rearrangements, most often ETV6-NTRK3 fusion. Given its histologic overlap with other salivary gland tumors (SGTs), SCs can be difficult to diagnose without genetic confirmation. A recently developed pan-TRK (tropomyosin receptor kinase) antibody shows promise for identifying tumors with NTRK (neurotrophic tyrosine kinase receptor 3) fusions. The aim of this study was to evaluate the utility of pan-TRK immunohistochemistry in distinguishing SCs from mimics and selecting patients eligible for TRK inhibitor clinical trials. We examined whole-tissue sections from 111 SGTs with molecular characterization, including 26 SCs (23 with ETV6-NTRK3 fusion and 3 with ETV6-RET fusion detected by ligation-dependent reverse transcription-polymerase chain reaction, next-generation sequencing and 85 non-SC SGTs (no ETV6-NTRK3 fusion). Immunohistochemistry was performed with a pan-TRK rabbit monoclonal antibody. When any pan-TRK staining (nuclear or cytoplasmic with any staining intensity) was considered to indicate positivity, 22 of 23 SCs with ETV6-NTRK3 fusion (95.7%) and 33 of 85 non-SC (38.8%) salivary neoplasms were positive, mainly basal cell adenoma, pleomorphic adenomas, adenoid cystic carcinomas, and epithelial-myoepithelial carcinomas. All SCs with ETV6-RET fusion were entirely negative. When only nuclear pan-TRK staining with any staining intensity was considered positive, 18 of 23 SCs with ETV6-NTRK3 fusion (78.3%) were positive, 11 among them with diffuse staining (>30% of cells). All non-SCs and SCs with ETV6-RET fusion were entirely negative. In comparison to molecular analysis (ligation-dependent reverse transcription-polymerase chain reaction, next-generation sequencing), nuclear pan-TRK IHC has a sensitivity of 78.3% and a specificity of 100% for diagnosing SCs with ETV6-NTRK3 fusion, 69% and 100% for SCs (all fusions). Pan-TRK is a reasonable screening test for diagnosing SCs among SGTs when taking only nuclear staining into account. Although pan-TRK expression is not entirely sensitive for SCs, nuclear staining is highly specific for SCs with ETV6-NTRK3 fusion. The lack of pan-TRK immunoreactivity in a subset of SCs is suggestive of atypical exons 4 to 14 or exons 5 to 14 ETV6-NTRK3 fusion or non-NTRK alternative fusion partners such as ETV6-RET. Pan-TRK staining can serve as a strong diagnostic marker to distinguish SC from it mimics and to select patients eligible for TRK inhibitor clinical trials.

Evolution of Non-alcoholic Fatty Liver Disease (NAFLD) Biomarkers in Response to Weight Loss 1 Year After Bariatric Surgery-a Post Hoc Analysis of the FibroTest Prospective Study.

BACKGROUND: Bariatric surgery is among the therapeutic options for non-alcoholic fatty liver disease (NAFLD), affecting 90% of patients with obesity. The aim of this study was to evaluate the evolution of NAFLD lesions 1 year after surgery using noninvasive markers. METHODS: From November 2011 to November 2012, 253 patients with obesity undergoing bariatric surgery in three French University Hospitals were included. Histological data regarding intraoperative liver biopsy were collected at baseline, clinical, and biological data, including FibroTest®, SteatoTest®, and NASHTest®, before and after surgery. RESULTS: Fibrosis' prevalence was 74.2% with a positive predictive value (PPV) for FibroTest® of 78.6% and 43.4% for significant fibrosis (Kleiner ≥ F2) with a negative predictive value (NPV) of 56.1%. NAFLD's prevalence was 84% with a PPV for SteatoTest® of 85.9% and 7.7% for NASH with an NPV for NASHTest® of 93.8%. One year after bariatric surgery, mean BMI had significantly decreased from 46.5 to 31.7 kg/m2 (p < 0.001). Fibrosis assessed by the FibroTest® showed that 82.5% of patients were F0 after surgery compared to 90.9% before. Using SteatoTest®, the percent of patient without steatosis (S0) increased from 1.6 to 49.6% after surgery, and rate of severe steatosis (S3) improved from 43.3 to 3.9%. NASHTest® revealed that the percent of patients without NASH increased from 12.8 to 73.6% and rates of NASH improved from 12 to 0.8%. CONCLUSIONS: Validated noninvasive biomarkers SteatoTest® and NASHTest® suggested NAFLD and steatohepatitis improvement after bariatric surgery and might be useful tools for patient follow-up. Regarding fibrosis, FibroTest® was not accurate in patients with extreme obesity.