Selective PP2A Enhancement through Biased Heterotrimer Stabilization.

Impairment of protein phosphatases, including the family of serine/threonine phosphatases designated PP2A, is essential for the pathogenesis of many diseases, including cancer. The ability of PP2A to dephosphorylate hundreds of proteins is regulated by over 40 specificity-determining regulatory "B" subunits that compete for assembly and activation of heterogeneous PP2A heterotrimers. Here, we reveal how a small molecule, DT-061, specifically stabilizes the B56α-PP2A holoenzyme in a fully assembled, active state to dephosphorylate selective substrates, such as its well-known oncogenic target, c-Myc. Our 3.6 Å structure identifies molecular interactions between DT-061 and all three PP2A subunits that prevent dissociation of the active enzyme and highlight inherent mechanisms of PP2A complex assembly. Thus, our findings provide fundamental insights into PP2A complex assembly and regulation, identify a unique interfacial stabilizing mode of action for therapeutic targeting, and aid in the development of phosphatase-based therapeutics tailored against disease specific phospho-protein targets.

Caspase-1 Engages Full-Length Gasdermin D through Two Distinct Interfaces That Mediate Caspase Recruitment and Substrate Cleavage.

The recognition and cleavage of gasdermin D (GSDMD) by inflammatory caspases-1, 4, 5, and 11 are essential steps in initiating pyroptosis after inflammasome activation. Previous work has identified cleavage site signatures in substrates such as GSDMD, but it is unclear whether these are the sole determinants for caspase engagement. Here we report the crystal structure of a complex between human caspase-1 and the full-length murine GSDMD. In addition to engagement of the GSDMD N- and C-domain linker by the caspase-1 active site, an anti-parallel ß sheet at the caspase-1 L2 and L2' loops bound a hydrophobic pocket within the GSDMD C-terminal domain distal to its N-terminal domain. This "exosite" interface endows an additional function for the GSDMD C-terminal domain as a caspase-recruitment module besides its role in autoinhibition. Our study thus reveals dual-interface engagement of GSDMD by caspase-1, which may be applicable to other physiological substrates of caspases.

RANBP2 and USP9x regulate nuclear import of adenovirus minor coat protein IIIa.

As intracellular parasites, viruses exploit cellular proteins at every stage of infection. Adenovirus outbreaks are associated with severe acute respiratory illnesses and conjunctivitis, with no specific antiviral therapy available. An adenoviral vaccine based on human adenovirus species D (HAdV-D) is currently in use for COVID-19. Herein, we investigate host interactions of HAdV-D type 37 (HAdV-D37) protein IIIa (pIIIa), identified by affinity purification and mass spectrometry (AP-MS) screens. We demonstrate that viral pIIIa interacts with ubiquitin-specific protease 9x (USP9x) and Ran-binding protein 2 (RANBP2). USP9x binding did not invoke its signature deubiquitination function but rather deregulated pIIIa-RANBP2 interactions. In USP9x-knockout cells, viral genome replication and viral protein expression increased compared to wild type cells, supporting a host-favored mechanism for USP9x. Conversely, RANBP2-knock down reduced pIIIa transport to the nucleus, viral genome replication, and viral protein expression. Also, RANBP2-siRNA pretreated cells appeared to contain fewer mature viral particles. Transmission electron microscopy of USP9x-siRNA pretreated, virus-infected cells revealed larger than typical paracrystalline viral arrays. RANBP2-siRNA pretreatment led to the accumulation of defective assembly products at an early maturation stage. CRM1 nuclear export blockade by leptomycin B led to the retention of pIIIa within cell nuclei and hindered pIIIa-RANBP2 interactions. In-vitro binding analyses indicated that USP9x and RANBP2 bind to C-terminus of pIIIa amino acids 386-563 and 386-510, respectively. Surface plasmon resonance testing showed direct pIIIa interaction with recombinant USP9x and RANBP2 proteins, without competition. Using an alternative and genetically disparate adenovirus type (HAdV-C5), we show that the demonstrated pIIIa interaction is also important for a severe respiratory pathogen. Together, our results suggest that pIIIa hijacks RANBP2 for nuclear import and subsequent virion assembly. USP9x counteracts this interaction and negatively regulates virion synthesis. This analysis extends the scope of known adenovirus-host interactions and has potential implications in designing new antiviral therapeutics.

Clinical Implications of a New DDX58 Pathogenic Variant That Causes Lupus Nephritis due to RIG-I Hyperactivation.

BACKGROUND: Lupus nephritis (LN) is one of the most severe complications of systemic lupus erythematosus, with heterogeneous phenotypes and different responses to therapy. Identifying genetic causes of LN can facilitate more individual treatment strategies. METHODS: We performed whole-exome sequencing in a cohort of Chinese patients with LN and identified variants of a disease-causing gene. Extensive biochemical, immunologic, and functional analyses assessed the effect of the variant on type I IFN signaling. We further investigated the effectiveness of targeted therapy using single-cell RNA sequencing. RESULTS: We identified a novel DDX58 pathogenic variant, R109C, in five unrelated families with LN. The DDX58 R109C variant is a gain-of-function mutation, elevating type I IFN signaling due to reduced autoinhibition, which leads to RIG-I hyperactivation, increased RIG-I K63 ubiquitination, and MAVS aggregation. Transcriptome analysis revealed an increased IFN signature in patient monocytes. Initiation of JAK inhibitor therapy (baricitinib 2 mg/d) effectively suppressed the IFN signal in one patient. CONCLUSIONS: A novel DDX58 R109C variant that can cause LN connects IFNopathy and LN, suggesting targeted therapy on the basis of pathogenicity. PODCAST: This article contains a podcast at.

Harmonizing florbetapir and PiB PET measurements of cortical Aß plaque burden using multiple regions-of-interest and machine learning techniques: An alternative to the Centiloid approach.

INTRODUCTION: Machine learning (ML) can optimize amyloid (Aß) comparability among positron emission tomography (PET) radiotracers. Using multi-regional florbetapir (FBP) measures and ML, we report better Pittsburgh compound-B (PiB)/FBP harmonization of mean-cortical Aß (mcAß) than Centiloid. METHODS: PiB-FBP pairs from 92 subjects in www.oasis-brains.org and 46 in www.gaain.org/centiloid-project were used as the training/testing sets. FreeSurfer-extracted FBP multi-regional Aß and actual PiB mcAß in the training set were used to train ML models generating synthetic PiB mcAß. The correlation coefficient (R) between the synthetic/actual PiB mcAß in the testing set was assessed. RESULTS: In the testing set, the synthetic/actual PiB mcAß correlation R = 0.985 (R2  = 0.970) using artificial neural network was significantly higher (p ≤ 6.6e-4) than the FBP/PiB correlation R = 0.927 (R2  = 0.860), improving total variance percentage (R2 ) from 86% to 97%. Other ML models such as partial least square, ensemble, and relevance vector regressions also improved R (p = 9.677e-05 /0.045/0.0017). DISCUSSION: ML improved mcAß comparability. Additional studies are needed for the generalizability to other amyloid tracers, and to tau PET. Highlights Centiloid is a calibration of the amyloid scale, not harmonization. Centiloid unifies the amyloid scale without improving inter-tracer association (R2 ). Machine learning (ML) can harmonize the amyloid scale by improving R2 . ML harmonization maps multi-regional florbetapir SUVRs to PiB mean-cortical SUVR. Artificial neural network ML increases Centiloid R2 from 86% to 97%.

Integrin mediates cell entry of the SARS-CoV-2 virus independent of cellular receptor ACE2.

Coronavirus disease 2019 (COVID-19) is a highly contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is broadly accepted that SARS-CoV-2 utilizes its spike protein to recognize the extracellular domain of angiotensin-converting enzyme 2 (ACE2) to enter cells for viral infection. However, other mechanisms of SARS-CoV-2 cell entry may occur. We show quantitatively that the SARS-CoV-2 spike protein also binds to the extracellular domain of broadly expressed integrin α5ß1 with an affinity comparable to that of SARS-CoV-2 binding to ACE2. More importantly, we provide direct evidence that such binding promotes the internalization of SARS-CoV-2 into non-ACE2 cells in a manner critically dependent upon the activation of the integrin. Our data demonstrate an alternative pathway for the cell entry of SARS-CoV-2, suggesting that upon initial ACE2-mediated invasion of the virus in the respiratory system, which is known to trigger an immune response and secretion of cytokines to activate integrin, the integrin-mediated cell invasion of SARS-CoV-2 into the respiratory system and other organs becomes effective, thereby promoting further infection and progression of COVID-19.

A randomized-controlled trial of ischemia-free liver transplantation for end-stage liver disease.

BACKGROUND & AIMS: Ischemia-reperfusion injury (IRI) has thus far been considered as an inevitable component of organ transplantation, compromising outcomes, and limiting organ availability. Ischemia-free organ transplantation is a novel approach designed to avoid IRI, with the potential to improve outcomes. METHODS: In this randomized-controlled clinical trial, recipients of livers from donors after brain death were randomly assigned to receive either an ischemia-free or a 'conventional' transplant. The primary endpoint was the incidence of early allograft dysfunction. Secondary endpoints included complications related to graft IRI. RESULTS: Out of 68 randomized patients, 65 underwent transplants and were included in the analysis. 32 patients received ischemia-free liver transplantation (IFLT), and 33 received conventional liver transplantation (CLT). Early allograft dysfunction occurred in two recipients (6%) randomized to IFLT and in eight (24%) randomized to CLT (difference -18%; 95% CI -35% to -1%; p = 0.044). Post-reperfusion syndrome occurred in three recipients (9%) randomized to IFLT and in 21 (64%) randomized to CLT (difference -54%; 95% CI -74% to -35%; p <0.001). Non-anastomotic biliary strictures diagnosed with protocol magnetic resonance cholangiopancreatography at 12 months were observed in two recipients (8%) randomized to IFLT and in nine (36%) randomized to CLT (difference, -28%; 95% CI -50% to -7%; p = 0.014). The comprehensive complication index at 1 year after transplantation was 30.48 (95% CI 23.25-37.71) in the IFLT group vs. 42.14 (95% CI 35.01-49.26) in the CLT group (difference -11.66; 95% CI -21.81 to -1.51; p = 0.025). CONCLUSIONS: Among patients with end-stage liver disease, IFLT significantly reduced complications related to IRI compared to a conventional approach. CLINICAL TRIAL REGISTRATION: chictr.org. ChiCTR1900021158. IMPACT AND IMPLICATIONS: Ischemia-reperfusion injury has thus far been considered as an inevitable event in organ transplantation, compromising outcomes and limiting organ availability. Ischemia-free liver transplantation is a novel approach of transplanting donor livers without interruption of blood supply. We showed that in patients with end-stage liver disease, ischemia-free liver transplantation, compared with a conventional approach, led to reduced complications related to ischemia-reperfusion injury in this randomized trial. This new approach is expected to change the current practice in organ transplantation, improving transplant outcomes, increasing organ utilization, while providing a clinical model to delineate the impact of organ injury on alloimmunity.

A nanobody-based complement inhibitor targeting complement component 2 reduces hemolysis in a complement humanized mouse model of autoimmune hemolytic anemia.

C2 is an attractive therapeutic target for many complement-mediated diseases. We developed Nab1B10, a new anti-C2 nanobody that potently and selectively inhibits both the classical and lectin pathways of complement activation. Mechanistically, Nab1B10 binds to the C2a portion of C2 and inhibits the assembly of C3 convertase C4b2a. Nab1B10 cross-reacts with monkey but not rodent C2 and inhibits classical pathway-mediated hemolysis. Using a new complement humanized mouse model of autoimmune hemolytic anemia (AIHA), we demonstrated that Nab1B10 abolished classical pathway complement activation-mediated hemolysis in vivo. We also developed C2-neutralizing bi- and tetra-valent antibodies based on Nab1B10 and found these antibodies significantly more potent than the other anti-C2 monoclonal antibody that is already in clinical trials. These data suggest that these novel C2-neutralizing nanobodies could be further developed as new therapeutics for many complement-mediated diseases, in which pathogenesis is dependent on the classical and/or lectin pathway of complement activation.

Association of regulatory T cells with renal outcomes in patients with proliferative lupus nephritis.

BACKGROUND: Despite progress in the diagnosis and treatment of proliferative lupus nephritis (PLN), the prognosis remains unfavorable. Previous investigations have suggested that the deficiency of regulatory T cells (Tregs) is involved in the pathogenesis of systemic lupus erythematosus (SLE) and lupus nephritis (LN). But the prognostic value of Tregs in PLN remains controversial. This study aimed to investigate the association of Tregs with renal outcomes in patients with PLN. METHODS: The baseline and follow-up data of patients with biopsy-proven PLN were collected in this study. All patients were divided into two groups according to whether the renal endpoint event occurred. Clinicopathologic features and therapeutic responses were compared between the two groups. Cox regression analyses curve fitting and threshold effect analysis were implemented to investigate the relationship between Tregs level and the long-term renal outcomes. The renal endpoint was defined as end-stage kidney disease (ESKD) or doubling the SCr value. RESULTS: A total of 405 PLN patients were included. After a follow-up of 71.53 (53.13-97.47) months, 42 (10.4%) patients reached the renal endpoint. The Treg cell counts (16/µL) in the renal endpoint group were significantly decreased than that in the non-renal endpoint group (p < 0.001). Univariate and multivariate Cox regression analyses showed that the high level of Tregs was an independent protective factor for the long-term renal prognosis of PLN. Smooth curve fitting of the generalized additive mixed model analysis indicated that the risk of renal endpoint first decreased with Tregs and then slightly increased along with Treg cell levels. The segmented linear model revealed that when Treg cell counts <46/µL, the risk of renal endpoint decreased by 6.8% for every 1 µL increase in Treg levels (p = 0.0029). CONCLUSION: Treg cell counts are closely related to the long-term renal outcomes of patients with PLN, and increasing Treg cell levels may play an important role in improving the prognosis of the kidney, but there may be a turning point (i.e., threshold effect) at the Treg cell counts that leads to directional changes in the renal outcomes.

A public resource of baseline data from the Alzheimer's Prevention Initiative Autosomal-Dominant Alzheimer's Disease Trial.

INTRODUCTION: The Alzheimer's Prevention Initiative Autosomal-Dominant Alzheimer's Disease (API ADAD) Trial evaluated the anti-oligomeric amyloid beta (Aß) antibody therapy crenezumab in cognitively unimpaired members of the Colombian presenilin 1 (PSEN1) E280A kindred. We report availability, methods employed to protect confidentiality and anonymity of participants, and process for requesting and accessing baseline data. METHODS: We developed mechanisms to share baseline data from the API ADAD Trial in consultation with experts and other groups sharing data from Alzheimer's disease (AD) prevention trials, balancing the need to protect anonymity and trial integrity with making data broadly available to accelerate progress in the field. We pressure-tested deliberate and inadvertent potential threats under specific assumptions, employed a system to suppress or mask both direct and indirect identifying variables, limited and firewalled data managers, and put forth specific principles requisite to receive data. RESULTS: Baseline demographic, PSEN1 E280A and apolipoprotein E genotypes, florbetapir and fluorodeoxyglucose positron emission tomography, magnetic resonance imaging, clinical, and cognitive data can now be requested by interested researchers. DISCUSSION: Baseline data are publicly available; treatment data and biological samples, including baseline and treatment-related blood-based biomarker data will become available in accordance with our original trial agreement and subsequently developed Collaboration for Alzheimer's Prevention principles. Sharing of these data will allow exploration of important questions including the differential effects of initiating an investigational AD prevention therapy both before as well as after measurable Aß plaque deposition.

Plasma p-tau217 predicts in vivo brain pathology and cognition in autosomal dominant Alzheimer's disease.

INTRODUCTION: Plasma-measured tau phosphorylated at threonine 217 (p-tau217) is a potential non-invasive biomarker of Alzheimer's disease (AD). We investigated whether plasma p-tau217 predicts subsequent cognition and positron emission tomography (PET) markers of pathology in autosomal dominant AD. METHODS: We analyzed baseline levels of plasma p-tau217 and its associations with amyloid PET, tau PET, and word list delayed recall measured 7.61 years later in non-demented age- and education-matched presenilin-1 E280A carriers (n = 24) and non-carrier (n = 20) family members. RESULTS: Carriers had higher plasma p-tau217 levels than non-carriers. Baseline plasma p-tau217 was associated with subsequent amyloid and tau PET pathology levels and cognitive function. DISCUSSION: Our findings suggest that plasma p-tau217 predicts subsequent brain pathological burden and memory performance in presenilin-1 E280A carriers. These results provide support for plasma p-tau217 as a minimally invasive diagnostic and prognostic biomarker for AD, with potential utility in clinical practice and trials. HIGHLIGHTS: Non-demented presenilin-1 E280A carriers have higher plasma tau phosphorylated at threonine 217 (p-tau217) than do age-matched non-carriers. Higher baseline p-tau217 is associated with greater future amyloid positron emission tomography (PET) pathology burden. Higher baseline p-tau217 is associated with greater future tau PET pathology burden. Higher baseline p-tau217 is associated with worse future memory performance.

Sex differences in blood biomarkers and cognitive performance in individuals with autosomal dominant Alzheimer's disease.

INTRODUCTION: Plasma tau phosphorylated at threonine 217 (P-tau217) and neurofilament light (NfL) have emerged as markers of Alzheimer's disease (AD) pathology. Few studies have examined the role of sex in plasma biomarkers in sporadic AD, yielding mixed findings, and none in autosomal dominant AD. METHODS: We examined the effects of sex and age on plasma P-tau217 and NfL, and their association with cognitive performance in a cross-sectional study of 621 Presenilin-1 E280A mutation carriers (PSEN1) and non-carriers. RESULTS: As plasma P-tau217 levels increase, cognitively unimpaired female carriers showed better cognitive performance than cognitively unimpaired male carriers. Yet, as disease progresses, female carriers had a greater plasma NfL increase than male carriers. There were no sex differences in the association between age and plasma biomarkers among non-carriers. DISCUSSION: Our findings suggest that, among PSEN1 mutation carriers, females had a greater rate of neurodegeneration than males, yet it did not predict cognitive performance. HIGHLIGHTS: We examined sex differences in plasma P-tau217 and NfL in Presenilin-1 E280A (PSEN1) mutation carriers and non-carriers. Female carriers had a greater plasma NfL increase, but not P-tau217, than male carriers. As plasma P-tau217 levels increase, cognitively unimpaired female carriers showed better cognitive performance than cognitively unimpaired male carriers. The interaction effect of sex by plasma NfL levels did not predict cognition among carriers.

Molecular characterization of linker and loop-mediated structural modulation and hinge motion in the C4-C5 domains of cMyBPC.

INTRODUCTION: The central C4 and C5 domains (C4C5) of cardiac myosin binding protein C (cMyBPC) contain a flexible interdomain linker and a cardiac-isoform specific loop. However, their importance in the functional regulation of cMyBPC has not been extensively studied. METHODS AND RESULTS: We expressed recombinant C4C5 proteins with deleted linker and loop regions and performed biophysical experiments to determine each of their structural and dynamic roles. We show that the linker and C5 loop regions modulate the secondary structure and thermal stability of C4C5. Furthermore, we provide evidence through extended molecular dynamics simulations and principle component analyses that C4C5 can adopt a completely bent or latched conformation. The simulation trajectory and interaction network analyses reveal that the completely bent conformation of C4C5 exhibits a specific pattern of residue-level interactions. Therefore, we propose a "hinge-and-latch" mechanism where the linker allows a great degree of flexibility and bending, while the loop aids in achieving a completely bent and latched conformation. Although this may be one of many bent positions that C4C5 can adopt, we illustrate for the first time in molecular detail that this type of large scale conformational change can occur in the central domains of cMyBPC. CONCLUSIONS: Our hinge-and-latch mechanism demonstrates that the linker and loop regions participate in dynamic modulation of cMyBPC's motion and global conformation. These structural and dynamic features may contribute to muscle isoform-specific regulation of actomyosin activity, and have potential implications regarding its ability to propagate or retract cMyBPC's regulatory N-terminal domains.

Hepatocyte glutathione S-transferase mu 2 prevents non-alcoholic steatohepatitis by suppressing ASK1 signaling.

BACKGROUND & AIMS: Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide. The advanced stage of NAFLD, non-alcoholic steatohepatitis (NASH), has been recognized as a leading cause of end-stage liver injury for which there are no FDA-approved therapeutic options. Glutathione S-transferase Mu 2 (GSTM2) is a phase II detoxification enzyme. However, the roles of GSTM2 in NASH have not been elucidated. METHODS: Multiple RNA-seq analyses were used to identify hepatic GSTM2 expression in NASH. In vitro and in vivo gain- or loss-of-function approaches were used to investigate the role and molecular mechanism of GSTM2 in NASH. RESULTS: We identified GSTM2 as a sensitive responder and effective suppressor of NASH progression. GSTM2 was significantly downregulated during NASH progression. Hepatocyte GSTM2 deficiency markedly aggravated insulin resistance, hepatic steatosis, inflammation and fibrosis induced by a high-fat diet and a high-fat/high-cholesterol diet. Mechanistically, GSTM2 sustained MAPK pathway signaling by directly interacting with apoptosis signal-regulating kinase 1 (ASK1). GSTM2 directly bound to the N-terminal region of ASK1 and inhibited ASK1 N-terminal dimerization to subsequently repress ASK1 phosphorylation and the activation of its downstream JNK/p38 signaling pathway under conditions of metabolic dysfunction. CONCLUSIONS: These data demonstrated that hepatocyte GSTM2 is an endogenous suppressor that protects against NASH progression by blocking ASK1 N-terminal dimerization and phosphorylation. Activating GSTM2 holds promise as a therapeutic strategy for NASH. CLINICAL TRIAL NUMBER: IIT-2021-277. LAY SUMMARY: New therapeutic strategies for non-alcoholic steatohepatitis are urgently needed. We identified that the protein GSTM2 exerts a protective effect in response to metabolic stress. Therapies that aim to increase the activity of GSTM2 could hold promise for the treatment of non-alcoholic steatohepatitis.

Good pregnancy outcomes in lupus nephritis patients with complete renal remission.

BACKGROUND: The aim of this study was to investigate pregnancy outcomes and risk factors in patients with lupus nephritis (LN). METHODS: A total of 158 pregnancies in 155 women with LN were divided into a remission group and a control group according to whether they achieved complete renal remission (CRR) prior to pregnancy. The adverse pregnancy outcomes and risk factors were retrospectively analyzed. RESULTS: In the remission group, 130 LN patients with 133 pregnancies (two twin pregnancies) delivered 127 live births; 25 LN patients with 25 pregnancies delivered 19 live births in the control group. Compared with the control group, the remission group had significantly lower incidence of LN relapse, fetal loss and premature birth. For LN patients in the remission group, a CRR duration <18 months [odds ratio (OR) 11.24, 95% confidence interval (CI) 2.95-42.80, P < 0.001] and anti-C1q antibody positivity before pregnancy (OR 7.2, 95% CI 1.38-37.41, P = 0.019) were independent risk factors for LN relapse; anti-phospholipid antibody positivity (OR 9.32, 95% CI 1.27-68.27, P = 0.028) and prednisone dosage during pregnancy ≥12.5 mg/day (OR 3.88, 95% CI 1.37-10.99, P = 0.011) were independent risk factors for fetal loss and premature birth, respectively; and age >30 years was an independent risk factor for preeclampsia and premature birth. CONCLUSION: LN patients with a CRR duration greater than 18 months were associated with good pregnancy outcomes and lower LN relapse. Age, anti-C1q and anti-phospholipid antibodies, and prednisone dosage during pregnancy were risk factors for adverse pregnancy outcomes.

Limitations of clinical trial sample size estimate by subtraction of two measurements.

In planning randomized clinical trials (RCTs) for diseases such as Alzheimer's disease (AD), researchers frequently rely on the use of existing data obtained from only two time points to estimate sample size via the subtraction of baseline from follow-up measurements in each subject. However, the inadequacy of this method has not been reported. The aim of this study is to discuss the limitation of sample size estimation based on the subtraction of available data from only two time points for RCTs. Mathematical equations are derived to demonstrate the condition under which the obtained data pairs with variable time intervals could be used to adequately estimate sample size. The MRI-based hippocampal volume measurements from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and Monte Carlo simulations (MCS) were used to illustrate the existing bias and variability of estimates. MCS results support the theoretically derived condition under which the subtraction approach may work. MCS also show the systematically under- or over-estimated sample sizes by up to 32.27 % bias. Not used properly, such subtraction approach outputs the same sample size regardless of trial durations partly due to the way measurement errors are handled. Estimating sample size by subtracting two measurements should be treated with caution. Such estimates can be biased, the magnitude of which depends on the planned RCT duration. To estimate sample sizes, we recommend using more than two measurements and more comprehensive approaches such as linear mixed effect models.

Continuous ZnO nanoparticle exposure induces melanoma-like skin lesions in epidermal barrier dysfunction model mice through anti-apoptotic effects mediated by the oxidative stress-activated NF-κB pathway.

BACKGROUND: Increasing interest in the hazardous properties of zinc oxide nanoparticles (ZnO NPs), commonly used as ultraviolet filters in sunscreen, has driven efforts to study the percutaneous application of ZnO NPs to diseased skin; however, in-depth studies of toxic effects on melanocytes under conditions of epidermal barrier dysfunction remain lacking. METHODS: Epidermal barrier dysfunction model mice were continuously exposed to a ZnO NP-containing suspension for 14 and 49 consecutive days in vivo. Melanoma-like change and molecular mechanisms were also verified in human epidermal melanocytes treated with 5.0 µg/ml ZnO NPs for 72 h in vitro. RESULTS: ZnO NP application for 14 and 49 consecutive days induced melanoma-like skin lesions, supported by pigmented appearance, markedly increased number of melanocytes in the epidermis and dermis, increased cells with irregular nuclei in the epidermis, recruited dendritic cells in the dermis and dysregulated expression of melanoma-associated gene Fkbp51, Trim63 and Tsp 1. ZnO NPs increased oxidative injury, inhibited apoptosis, and increased nuclear factor kappa B (NF-κB) p65 and Bcl-2 expression in melanocytes of skin with epidermal barrier dysfunction after continuously treated for 14 and 49 days. Exposure to 5.0 µg/ml ZnO NPs for 72 h increased cell viability, decreased apoptosis, and increased Fkbp51 expression in melanocytes, consistent with histological observations in vivo. The oxidative stress-mediated mechanism underlying the induction of anti-apoptotic effects was verified using the reactive oxygen species scavenger N-acetylcysteine. CONCLUSIONS: The entry of ZnO NPs into the stratum basale of skin with epidermal barrier dysfunction resulted in melanoma-like skin lesions and an anti-apoptotic effect induced by oxidative stress, activating the NF-κB pathway in melanocytes.

Deep residual inception encoder-decoder network for amyloid PET harmonization.

INTRODUCTION: Multiple positron emission tomography (PET) tracers are available for amyloid imaging, posing a significant challenge to consensus interpretation and quantitative analysis. We accordingly developed and validated a deep learning model as a harmonization strategy. METHOD: A Residual Inception Encoder-Decoder Neural Network was developed to harmonize images between amyloid PET image pairs made with Pittsburgh Compound-B and florbetapir tracers. The model was trained using a dataset with 92 subjects with 10-fold cross validation and its generalizability was further examined using an independent external dataset of 46 subjects. RESULTS: Significantly stronger between-tracer correlations (P < .001) were observed after harmonization for both global amyloid burden indices and voxel-wise measurements in the training cohort and the external testing cohort. DISCUSSION: We proposed and validated a novel encoder-decoder based deep model to harmonize amyloid PET imaging data from different tracers. Further investigation is ongoing to improve the model and apply to additional tracers.

Sex differences in cognitive resilience in preclinical autosomal-dominant Alzheimer's disease carriers and non-carriers: Baseline findings from the API ADAD Colombia Trial.

INTRODUCTION: Females may have greater susceptibility to Alzheimer's disease (AD)-pathology. We examined the effect of sex on pathology, neurodegeneration, and memory in cognitively-unimpaired Presenilin-1 (PSEN1) E280A mutation carriers and non-carriers. METHODS: We analyzed baseline data from 167 mutation carriers and 75 non-carriers (ages 30 to 53) from the Alzheimer's Prevention Initiative Autosomal Dominant AD Trial, including florbetapir- and fludeoxyglucose-PET, MRI based hippocampal volume and cognitive testing. RESULTS: Females exhibited better delayed recall than males, controlling for age, precuneus glucose metabolism, and mutation status, although the effect was not significant among PSEN1 mutation carriers only. APOE ε4 did not modify the effect of sex on AD biomarkers and memory. DISCUSSION: Our findings suggest that, among cognitively-unimpaired individuals at genetic risk for autosomal-dominant AD, females may have greater cognitive resilience to AD pathology and neurodegeneration than males. Further investigation of sex-specific differences in autosomal-dominant AD is key to elucidating mechanisms of AD risk and resilience.

Machine Learning for Prediction and Risk Stratification of Lupus Nephritis Renal Flare.

BACKGROUND: Renal flare of lupus nephritis (LN) is strongly associated with poor kidney outcomes, and predicting renal flare and stratifying its risk are important for clinical decision-making and individualized management to reduce LN flare. METHODS: We randomly divided 1,694 patients with biopsy-proven LN, who had achieved remission after treatment, into a derivation cohort (n = 1,186) and an internal validation cohort (n = 508), at a ratio of 7:3. The risk of renal flare 5 years after remission was predicted using an eXtreme Gradient Boosting (XGBoost) method model, developed from 59 variables, including demographic, clinical, immunological, pathological, and therapeutic characteristics. A simplified risk score prediction model (SRSPM) was developed from important variables selected by XGBoost model using stepwise Cox regression for practical convenience. RESULTS: The 5-year relapse rates were 39.5% and 38.2% in the derivation and internal validation cohorts, respectively. Both the XGBoost model and the SRSPM had good predictive performance, with a C-index of 0.819 (95% confidence interval [CI]: 0.774-0.857) and 0.746 (95% CI: 0.697-0.795), respectively, in the validation cohort. The SRSPM comprised 6 variables, including partial remission and endocapillary hypercellularity at baseline, age, serum Alb, anti-dsDNA, and serum complement C3 at the point of remission. Using Kaplan-Meier analysis, the SRSPM identified significant risk stratification for renal flares (p < 0.001). CONCLUSIONS: Renal flare of LN can be readily predicted using the XGBoost model and the SRSPM, and the SRSPM can also stratify flare risk. Both models are useful for clinical decision-making and individualized management in LN.