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Intro: Understanding infectious disease transmission dynamics is key to optimising infection prevention and control (IPC) strategies. Yet, standard epidemiological modelling tools do not fully utilise large datasets of time- evolving spatial interactions, which could lead to improved descriptions of complex transmission dynamics, as exhibited by multi-drug resistant organisms (MDRO). Here, we showcase an approach accounting for spatial-temporal dynamics using machine learning and graph theory to characterize nosocomial MDRO transmission. Methods: We performed a retrospective cohort study using all inpatient admissions to a 1200-bed Singaporean hospital from 2018-01-01 to 2021-12-31. We employ a graph-based machine learning methodology to learn transmission dynamics using spatial-temporal patient interactions. Taking Methicillin-resistant Staphylococcus aureus (MRSA) as a proof-of-principle, we examine the real-world efficacy using routine surveillance and clinical cultures obtained during acute care. Findings: There were 149,352 inpatient admissions and 3.21 million contact-interactions during the study period; 7,753 (5.2%) of these patients tested positive for MRSA, with 1,585 (1.1%;) being likely hospital acquisitions. The probability of onward transmission was largest on the day a culture-positive result was reported (11.2% of all transmissions). However, high onward-transmission persisted beyond (weighted-mean 7.8 days). Through spatial-temporal analsysis, we found hospital rooms with comparatively high acquisition-rates (36/665 wards accounting for 50.2% of hospital-acquisitions); these hotspots were found to be central in network of patient transfers, and interconnected with each other. Conclusion: With extensive and detailed datasets becoming available, new methodologies that leverage their size and detail can provide insights into transmission processes. Here, we demonstrated their use to learn the transmission dynamics of an MDRO and showed their ability to make inferences on spatial-temporal profiles of transmission. Furthering this research, we will engineer spatial-temporal features to predict pathogen transmission dynamics and expand to additional MDROs.

Intro: Controlling the spread of infectious diseases requires correctly targeting preventative resources. When poorly deployed, these resources are misspent and have an inefficient impact. In a dynamic environment where sources of outbreaks are ever-changing, how to optimally deploy these resources is difficult to identify and can moreover change over time. In addressment, we outline and test network-driven framework that accounts for underlying patient mobility, and outbreak dynamics in hospitals to predict the temporal and spatial arrival of carbapenemase-producing Enterobacteriaceae (CPE) outbreaks. Methods: We reconstructed CPE-outbreaks using a novel formulation based on transmission-dynamics, contact-interactions, and microbiology data. For each outbreak, we then examine their spatial evolution and, using background hospital population movement (entire patient population from Imperial College Healthcare NHS Trust between 2018-08-17 and 2022-02-03), we predict the arrival times of new CPE cases across wards. Findings: The background mobility-network contained ward-transitions from 181,512 patients (178 wards). Based on the construction, the network comprises a single giant component and acts as a medium for disease transmission. For the results of a fitted regression predicting outbreak arrival, we included locational attributes, in addition to network distances. Overall, we found that effective distance (a graphbased path measure shown previously epidemiologically predictive) contained unique predictive power compared to edge weight. However, the effective distance could be complemented by information regarding patient demographics (Age and Sex) of patient transfers; their predictive power is suggestive of specific sub-population mobility as more important drivers of CPE. Conclusion: We investigated a network-driven framework showing the potential to anticipate arrival-times of hospital CPE outbreaks. In including additional information, we also showed how specific hospital population movements were key drivers of CPE. In furthering our results, we next plan to investigate additional diseases, validate our findings beyond our current dataset, and explore further locational attributes.

Purpose: Contact tracing is a crucial tool in infection prevention and control (IPC), which aims to identify outbreaks and prevent onward transmission. What constitutes a contact is typically based on strict binary criteria (i.e., being at a location at the same time). Missing data, indirect contacts and background sources can however substantially alter contact-tracing investigations. Here, we present StEP, a Spatial-temporal Epidemiological Proximity model that accounts for imperfect data by introducing a network-based notion of contact based on spatial-temporal proximity derived from background flows of patient movement. Methods & Materials: We showcase StEP by analysing outbreaks of multidrug-resistant bacteria and COVID-19 within a large hospital Trust in London (UK).StEP utilises spatial-temporal patient trajectories and the background hospital movement flows to recover enhanced contact networks. Firstly, we study a well-characterised outbreak of carbapenemase-producing Enterobacteriaceae (CPE) involving 116 hospitalised patients where genetic sequencing is used to learn model parameters. Secondly, our trained model is deployed in an unsupervised manner on three unseen outbreaks involving 867 patients of related CPE-types. Thirdly, we test application to an altogether novel pathogen by analysing a hospital outbreak of COVID-19 among 90 hospital patients, and demonstrate the power of StEP when characterising newly emerging diseases, even when there is a lack of sequencing data. Results: In addition to recovering core contact structures, StEP identifies missing contacts that link seemingly unconnected infection clusters, revealing a larger extent of transmission than conventional methods. Via genomic analyses we confirm that the additional contacts detected through StEP lead to improved alignment to the plasmid phylogeny (the major outbreak driving force). Hence the StEP contact network is most aligned to the transmission structure. Conclusion: By considering spatial-temporal information in a continuous manner, StEP tackles several challenges associated with traditional contact-tracing. StEP allows both direct and indirect contacts as possible routes of disease transmission and is tuneable to a pathogen's epidemiological characteristics. Such flexible use of heterogeneous data in uncertain situations can significantly enhance IPC.

Purpose: Predicting healthcare-acquired infections (HAIs) has the potential to revolutionise the prevention and control of transmissible infections. Existing prediction models for HAIs, however, fail to capture fully the contact-driven nature of infectious diseases. Here, we investigate the epidemiological predictivity of patient contact patterns through a forecasting model for hospital-onset COVID-19 infection (HOCI). Methods & Materials: Our cohort comprises all patient admissions at a large London NHS Trust between 1/04/2020 and 1/04/2021. For patients, we consider (i) their hospital pathway, (ii) patient contacts, and (iii) date of COVID-19 infection. We consider rolling 14-day windows and forecast patient infection over the subsequent 7 days. Over each window, we construct a patient contact network and compute network features that capture contact centrality. We then combine network features, hospital environmental variables and patient clinical data to predict subsequent infections. Results: A total of 51,157 patient admissions/episodes were observed during the study. Across all models, we find that contact-network features showed the highest performance (0.91 AUC-ROC). A reduced model with the six most predictive variables was almost as predictive and contained five features from patient contact (including direct contact with and network proximity to infectious cases) and only one environmental variable (length of stay). Conclusion: Our results reveal that the number of direct contacts and network proximity to infectious patient(s) are highly predictive of HOCI. Such contact-based risk factors are easily extracted from routinely collected electronic health records providing a highly accessible route to improve personalised disease prognostics in future models.

Establishing anion exchange membrane water electrolysis (AEMWE) as a new technology for efficient hydrogen production requires cost-effective and high-performance catalyst materials. Here, we report the synthesis and comprehensive characterization of carbon supported NiRu alloy nanoparticles as a cost-effective hydrogen evolution reaction catalyst for AEMWEs. Different NiRu catalysts were synthesized using a facile and scalable impregnation method. Half-cell results showed the ‘NiRu’ catalyst with ca. 10 wt.% Ru to exhibit an increased noble metal mass activity and slightly decreased Tafel slope compared to a commercial Pt/C catalyst with 60 wt.% Pt. Further, we report the application of NiRu/C as a cathodic catalyst in AEMWE full cell for the first time. In full cell tests, the synthesized catalysts exhibit 2 A cm ^−2 at 1.95 V with a low loading of 0.1 mg _PGM cm ^−2 at the cathode.

Deep brain stimulation (DBS) has emerged as a revolutionary technique for accessing and modulating brain circuits. DBS is used to treat dysfunctional neuronal circuits in neurological and psychiatric disorders. Despite over two decades of clinical application, the fundamental mechanisms underlying DBS are still not well understood. One reason is the complexity of in vivo electrical manipulation of the central nervous system, particularly in rodent models. DBS-devices for freely moving rodents are typically custom-designed and not commercially available, thus making it difficult to perform experimental DBS according to common standards. Addressing these challenges, we have developed a novel wireless microstimulation system for deep brain stimulation (wDBS) tailored for rodents. We demonstrate the efficacy of this device for the restoration of behavioral impairments in hemiparkinsonian mice through unilateral wDBS of the subthalamic nucleus. Moreover, we introduce a standardized and innovative pipeline, integrating machine learning techniques to analyze Parkinson's disease-like and DBS-induced gait changes., (© 2024. The Author(s).)

A signal mixer facilitates rich computation, which has been the building block of modern telecommunication. This frequency mixing produces new signals at the sum and difference frequencies of input signals, enabling powerful operations such as heterodyning and multiplexing. Here, we report that a neuron is a signal mixer. We found through ex vivo and in vivo whole-cell measurements that neurons mix exogenous (controlled) and endogenous (spontaneous) subthreshold membrane potential oscillations, producing new oscillation frequencies, and that neural mixing originates in voltage-gated ion channels. Furthermore, we demonstrate that mixing is evident in human brain activity and is associated with cognitive functions. We found that the human electroencephalogram displays distinct clusters of local and inter-region mixing and that conversion of the salient posterior alpha-beta oscillations into gamma-band oscillations regulates visual attention. Signal mixing may enable individual neurons to sculpt the spectrum of neural circuit oscillations and utilize them for computational operations., Competing Interests: Declaration of interests N.G. and E.S.B. are inventors of a patent on neuromodulation using temporal interference (TI) of kHz electric fields, assigned to MIT. N.G. and E.S.B. are co-founders of TI Solutions AG, a company committed to producing hardware and software solutions to support TI research., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Tremor is one of the most common neurological symptoms. Its clinical and neurobiological complexity necessitates novel approaches for granular phenotyping. Instrumented neurophysiological analyses have proven useful, but are highly resource-intensive and lack broad accessibility. In contrast, bedside scores are simple to administer, but lack the granularity to capture subtle but relevant tremor features. We utilise the open-source computer vision pose tracking algorithm Mediapipe to track hands in clinical video recordings and use the resulting time series to compute canonical tremor features. This approach is compared to marker-based 3D motion capture, wrist-worn accelerometry, clinical scoring and a second, specifically trained tremor-specific algorithm in two independent clinical cohorts. These cohorts consisted of 66 patients diagnosed with essential tremor, assessed in different task conditions and states of deep brain stimulation therapy. We find that Mediapipe-derived tremor metrics exhibit high convergent clinical validity to scores (Spearman's ρ = 0.55-0.86, p≤ .01) as well as an accuracy of up to 2.60 mm (95% CI [-3.13, 8.23]) and ≤0.21 Hz (95% CI [-0.05, 0.46]) for tremor amplitude and frequency measurements, matching gold-standard equipment. Mediapipe, but not the disease-specific algorithm, was capable of analysing videos involving complex configurational changes of the hands. Moreover, it enabled the extraction of tremor features with diagnostic and prognostic relevance, a dimension which conventional tremor scores were unable to provide. Collectively, this demonstrates that current computer vision algorithms can be transformed into an accurate and highly accessible tool for video-based tremor analysis, yielding comparable results to gold standard tremor recordings., (© 2024. The Author(s).)

Dystonia is a neurological movement disorder characterised by abnormal involuntary movements and postures, particularly affecting the head and neck. However, current clinical assessment methods for dystonia rely on simplified rating scales which lack the ability to capture the intricate spatiotemporal features of dystonic phenomena, hindering clinical management and limiting understanding of the underlying neurobiology. To address this, we developed a visual perceptive deep learning framework that utilizes standard clinical videos to comprehensively evaluate and quantify disease states and the impact of therapeutic interventions, specifically deep brain stimulation. This framework overcomes the limitations of traditional rating scales and offers an efficient and accurate method that is rater-independent for evaluating and monitoring dystonia patients. To evaluate the framework, we leveraged semi-standardized clinical video data collected in three retrospective, longitudinal cohort studies across seven academic centres. We extracted static head angle excursions for clinical validation and derived kinematic variables reflecting naturalistic head dynamics to predict dystonia severity, subtype, and neuromodulation effects. The framework was also applied to a fully independent cohort of generalised dystonia patients for comparison between dystonia sub-types. Computer vision-derived measurements of head angle excursions showed a strong correlation with clinically assigned scores. Across comparisons, we identified consistent kinematic features from full video assessments encoding information critical to disease severity, subtype, and effects of neural circuit interventions, independent of static head angle deviations used in scoring. Our visual perceptive machine learning framework reveals kinematic pathosignatures of dystonia, potentially augmenting clinical management, facilitating scientific translation, and informing personalized precision neurology approaches., (© 2024. The Author(s).)

The unprecedented increase in life expectancy presents a unique opportunity and the necessity to explore both healthy and pathological aspects of ageing. Electroencephalography (EEG) has been widely used to identify neuromarkers of cognitive ageing due to its affordability and richness in information. However, despite the growing volume of data and methodological advancements, the abundance of contradictory and non-reproducible findings has hindered clinical translation. To address these challenges, our study introduces a comprehensive workflow expanding on previous EEG studies and investigates various static and dynamic power and connectivity estimates as potential neuromarkers of cognitive ageing in a large dataset. We also assess the robustness of our findings by testing their susceptibility to band specification. Finally, we characterise our findings using functionally annotated brain networks to improve their interpretability and multi-modal integration. Our analysis demonstrates the effect of methodological choices on findings and that dynamic rather than static neuromarkers are not only more sensitive but also more robust. Consequently, they emerge as strong candidates for cognitive ageing neuromarkers. Moreover, we were able to replicate the most established EEG findings in cognitive ageing, such as alpha oscillation slowing, increased beta power, reduced reactivity across multiple bands, and decreased delta connectivity. Additionally, when considering individual variations in the alpha band, we clarified that alpha power is characteristic of memory performance rather than ageing, highlighting its potential as a neuromarker for cognitive ageing. Finally, our approach using functionally annotated source reconstruction allowed us to provide insights into domain-specific electrophysiological mechanisms underlying memory performance and ageing. HIGHLIGHTS: We provide an open and reproducible pipeline with a comprehensive workflow to investigate static and dynamic EEG neuromarkers. Neuromarkers related to neural dynamics are sensitive and robust. Individualised alpha power characterises cognitive performance rather than ageing. Functional annotation allows cross-modal interpretation of EEG findings., (© 2024 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.)

Studies have shown that beta band activity is not tonically elevated but comprises exaggerated phasic bursts of varying durations and magnitudes, for Parkinson's disease (PD) patients. Current methods for detecting beta bursts target a single frequency peak in beta band, potentially ignoring bursts in the wider beta band. In this study, we propose a new robust framework for beta burst identification across wide frequency ranges. Chronic local field potential at-rest recordings were obtained from seven PD patients implanted with Medtronic SenSight™ deep brain stimulation (DBS) electrodes. The proposed method uses wavelet decomposition to compute the time-frequency spectrum and identifies bursts spanning multiple frequency bins by thresholding, offering an additional burst measure, ∆f, that captures the width of a burst in the frequency domain. Analysis included calculating burst duration, magnitude, and ∆f and evaluating the distribution and likelihood of bursts between the low beta (13-20 Hz) and high beta (21-35 Hz). Finally, the results of the analysis were correlated to motor impairment (MDS-UPDRS III) med off scores. We found that low beta bursts with longer durations and larger width in the frequency domain (∆f) were positively correlated, while high beta bursts with longer durations and larger ∆f were negatively correlated with motor impairment. The proposed method, finding clear differences between bursting behavior in high and low beta bands, has clearly demonstrated the importance of considering wide frequency bands for beta burst behavior with implications for closed-loop DBS paradigms., (© 2023. The Author(s).)

Background: Deep brain stimulation of the internal globus pallidus effectively alleviates dystonia motor symptoms. However, delayed symptom control and a lack of therapeutic biomarkers and a single pallidal sweetspot region complicates optimal programming. Postoperative management is complex, typically requiring multiple, lengthy follow-ups with an experienced physician - an important barrier to widespread adoption in medication-refractory dystonia patients., Objective: Here we prospectively tested the best machine-predicted programming settings in a dystonia cohort treated with GPi-DBS against the settings derived from clinical long-term care in a specialised DBS centre., Methods: Previously, we reconstructed an anatomical map of motor improvement probability across the pallidal region using individual stimulation volumes and clinical outcomes in dystonia patients. We used this to develop an algorithm that tests in silico thousands of putative stimulation settings in de novo patients after reconstructing an individual, image-based anatomical model of electrode positions, and suggests stimulation parameters with the highest likelihood of optimal symptom control. To test real-life application, our prospective study compared results in 10 patients against programming settings derived from long-term care., Results: In this cohort, dystonia symptom reduction was observed at 74.9 ± 15.3% with C-SURF programming as compared to 66.3 ± 16.3% with clinical programming (p < 0.012). The average total electrical energy delivered (TEED) was similar for both the clinical and C-SURF programming (262.0 μJ/s vs. 306.1 μJ/s respectively)., Conclusion: Our findings highlight the clinical potential of machine-based programming in dystonia, which could markedly reduce the programming burden in postoperative management., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: FL reports grants from Boston Scientific not relevant to the submitted manuscript. MMR reports grants and personal fees from Boston Scientific and Medtronic, not relevant to the submitted work. MJR reports grants and personal fees from Boston Scientific, Medtronic and Zambon, not relevant to the submitted work. JV reports grants and personal fees from Medtronic, personal fees from St. Jude, grants and personal fees from Boston Scientific, personal fees from UCB, personal fees from Merz, personal fees from Allergan, personal fees from TEVA, personal fees from Novartis, personal fees from AbbVie and personal fees from Grünenthal, all outside the submitted work. All other authors report no competing interests., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Tremor is the most frequent human movement disorder, and its diagnosis is based on clinical assessment. Yet finding the accurate clinical diagnosis is not always straightforward. Fine-tuning of clinical diagnostic criteria over the past few decades, as well as device-based qualitative analysis, has resulted in incremental improvements to diagnostic accuracy. Accelerometric assessments are commonplace, enabling clinicians to capture high-resolution oscillatory properties of tremor, which recently have been the focus of various machine-learning (ML) studies. In this context, the application of ML models to accelerometric recordings provides the potential for less-biased classification and quantification of tremor disorders. However, if implemented incorrectly, ML can result in spurious or nongeneralizable results and misguided conclusions. This work summarizes and highlights recent developments in ML tools for tremor research, with a focus on supervised ML. We aim to highlight the opportunities and limitations of such approaches and provide future directions while simultaneously guiding the reader through the process of applying ML to analyze tremor data. We identify the need for the movement disorder community to take a more proactive role in the application of these novel analytical technologies, which so far have been predominantly pursued by the engineering and data analysis field. Ultimately, big-data approaches offer the possibility to identify generalizable patterns but warrant meaningful translation into clinical practice. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society., (© 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.)

Background: Eye movement abnormalities are commonplace in neurological disorders. However, unaided eye movement assessments lack granularity. Although videooculography (VOG) improves diagnostic accuracy, resource intensiveness precludes its broad use. To bridge this care gap, we here validate a framework for smartphone video-based nystagmography capitalizing on recent computer vision advances., Methods: A convolutional neural network was fine-tuned for pupil tracking using > 550 annotated frames: ConVNG. In a cross-sectional approach, slow-phase velocity of optokinetic nystagmus was calculated in 10 subjects using ConVNG and VOG. Equivalence of accuracy and precision was assessed using the "two one-sample t-test" (TOST) and Bayesian interval-null approaches. ConVNG was systematically compared to OpenFace and MediaPipe as computer vision (CV) benchmarks for gaze estimation., Results: ConVNG tracking accuracy reached 9-15% of an average pupil diameter. In a fully independent clinical video dataset, ConVNG robustly detected pupil keypoints (median prediction confidence 0.85). SPV measurement accuracy was equivalent to VOG (TOST p < 0.017; Bayes factors (BF) > 24). ConVNG, but not MediaPipe, achieved equivalence to VOG in all SPV calculations. Median precision was 0.30°/s for ConVNG, 0.7°/s for MediaPipe and 0.12°/s for VOG. ConVNG precision was significantly higher than MediaPipe in vertical planes, but both algorithms' precision was inferior to VOG., Conclusions: ConVNG enables offline smartphone video nystagmography with an accuracy comparable to VOG and significantly higher precision than MediaPipe, a benchmark computer vision application for gaze estimation. This serves as a blueprint for highly accessible tools with potential to accelerate progress toward precise and personalized Medicine., (© 2022. The Author(s).)

Background: Deep brain stimulation of the subthalamic nucleus is an effective treatment of Parkinson's disease, yet it is often associated with a general deterioration of speech intelligibility. Clustering the phenotypes of dysarthria has been proposed as a strategy to tackle these stimulation-induced speech problems., Methods: In this study, we examine a cohort of 24 patients to test the real-life application of the proposed clustering and attempt to attribute the clusters to specific brain networks with two different approaches of connectivity analysis., Results: Both our data-driven and hypothesis-driven approaches revealed strong connections of variants of stimulation-induced dysarthria to brain regions that are known actors of motor speech control. We showed a strong connection between the spastic dysarthria type and the precentral gyrus and supplementary motor area, prompting a possible disruption of corticobulbar fibers. The connection between the strained voice dysarthria and more frontal areas hints toward a deeper disruption of the motor programming of speech production., Conclusions: These results provide insights into the mechanism of stimulation-induced dysarthria in deep brain stimulation of the subthalamic nucleus and may guide reprogramming attempts for individual Parkinson's patients based on pathophysiological understanding of the affected networks., Competing Interests: Declaration of competing interest FL reports grants from Boston Scientific not relevant to the submitted work. MMR reports grants and personal fees from Boston Scientific and Medtronic, not relevant to the submitted work. JV reports grants and personal fees from Medtronic, personal fees from St. Jude, grants and personal fees from Boston Scientific, personal fees from UCB, personal fees from Merz, personal fees from Allergan, personal fees from TEVA, personal fees from Novartis, personal fees from AbbVie and personal fees from Grünenthal, all outside the submitted work., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This Review provides an overview of the emerging concepts of catalysts, membranes, and membrane electrode assemblies (MEAs) for water electrolyzers with anion-exchange membranes (AEMs), also known as zero-gap alkaline water electrolyzers. Much of the recent progress is due to improvements in materials chemistry, MEA designs, and optimized operation conditions. Research on anion-exchange polymers (AEPs) has focused on the cationic head/backbone/side-chain structures and key properties such as ionic conductivity and alkaline stability. Several approaches, such as cross-linking, microphase, and organic/inorganic composites, have been proposed to improve the anion-exchange performance and the chemical and mechanical stability of AEMs. Numerous AEMs now exceed values of 0.1 S/cm (at 60-80 °C), although the stability specifically at temperatures exceeding 60 °C needs further enhancement. The oxygen evolution reaction (OER) is still a limiting factor. An analysis of thin-layer OER data suggests that NiFe-type catalysts have the highest activity. There is debate on the active-site mechanism of the NiFe catalysts, and their long-term stability needs to be understood. Addition of Co to NiFe increases the conductivity of these catalysts. The same analysis for the hydrogen evolution reaction (HER) shows carbon-supported Pt to be dominating, although PtNi alloys and clusters of Ni(OH) 2 on Pt show competitive activities. Recent advances in forming and embedding well-dispersed Ru nanoparticles on functionalized high-surface-area carbon supports show promising HER activities. However, the stability of these catalysts under actual AEMWE operating conditions needs to be proven. The field is advancing rapidly but could benefit through the adaptation of new in situ techniques, standardized evaluation protocols for AEMWE conditions, and innovative catalyst-structure designs. Nevertheless, single AEM water electrolyzer cells have been operated for several thousand hours at temperatures and current densities as high as 60 °C and 1 A/cm 2 , respectively.

Dimension is a fundamental property of objects and the space in which they are embedded. Yet ideal notions of dimension, as in Euclidean spaces, do not always translate to physical spaces, which can be constrained by boundaries and distorted by inhomogeneities, or to intrinsically discrete systems such as networks. To take into account locality, finiteness and discreteness, dynamical processes can be used to probe the space geometry and define its dimension. Here we show that each point in space can be assigned a relative dimension with respect to the source of a diffusive process, a concept that provides a scale-dependent definition for local and global dimension also applicable to networks. To showcase its application to physical systems, we demonstrate that the local dimension of structural protein graphs correlates with structural flexibility, and the relative dimension with respect to the active site uncovers regions involved in allosteric communication. In simple models of epidemics on networks, the relative dimension is predictive of the spreading capability of nodes, and identifies scales at which the graph structure is predictive of infectivity. We further apply our dimension measures to neuronal networks, economic trade, social networks, ocean flows, and to the comparison of random graphs., (© 2022. The Author(s).)

Lung and bladder cancers are mostly incurable because of the early development of drug resistance and metastatic dissemination. Hence, improved therapies that tackle these two processes are urgently needed to improve clinical outcome. We have identified RSK4 as a promoter of drug resistance and metastasis in lung and bladder cancer cells. Silencing this kinase, through either RNA interference or CRISPR, sensitized tumor cells to chemotherapy and hindered metastasis in vitro and in vivo in a tail vein injection model. Drug screening revealed several floxacin antibiotics as potent RSK4 activation inhibitors, and trovafloxacin reproduced all effects of RSK4 silencing in vitro and in/ex vivo using lung cancer xenograft and genetically engineered mouse models and bladder tumor explants. Through x-ray structure determination and Markov transient and Deuterium exchange analyses, we identified the allosteric binding site and revealed how this compound blocks RSK4 kinase activation through binding to an allosteric site and mimicking a kinase autoinhibitory mechanism involving the RSK4's hydrophobic motif. Last, we show that patients undergoing chemotherapy and adhering to prophylactic levofloxacin in the large placebo-controlled randomized phase 3 SIGNIFICANT trial had significantly increased ( P = 0.048) long-term overall survival times. Hence, we suggest that RSK4 inhibition may represent an effective therapeutic strategy for treating lung and bladder cancer., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

We demonstrate that electron-vibration-vibration two-dimensional infrared spectroscopy (EVV 2DIR) can be used to detect the binding of a drug to a target protein-active site. The EVV 2DIR spectrum of the FGFR1 kinase target protein is found to have ∼200 detectable cross-peaks in the spectral region 1250-1750 cm -1 /2600-3400 cm -1 , with additional 63 peaks caused by the addition of a drug, SU5402. Of these 63 new peaks, it is shown that only six are due to protein-drug interactions, with the other 57 being due to vibrational coupling within the drug itself. Quantum mechanical calculations employing density functional theory are used to support assignment of the six binding-dependent peaks, with one being assigned to a known interaction between the drug and a backbone carbonyl group which forms part of the binding site. None of the 57 intramolecular coupling peaks associated with the drug molecule change substantially in either intensity or frequency when the drug binds to the target protein. This strongly suggests that the structure of the drug in the target binding site is essentially identical to that when it is not bound.

Background & Aims: Eosinophilic esophagitis (EoE) is a chronic, esophageal, type 2 inflammatory response associated with increased serum levels of interleukin 13 (IL13), which might contribute to its pathogenesis. RPC4046, a recombinant humanized monoclonal antibody against IL13, prevents its binding to the receptor subunits IL13RA1 and IL13RA2. We performed a phase 2 trial to evaluate the efficacy and safety of RPC4046 in patients with EoE., Methods: We performed a multicenter, double-blind trial of 99 adults with active EoE randomly assigned (1:1:1) to groups given RPC4046 (180 or 360 mg) or placebo once weekly for 16 weeks, from September 2014 through December 2015. Patients were seen at day 1 (baseline) and weeks 2, 4, 8, 12, and 16. They underwent esophagogastroduodenoscopy and biopsies were collected at baseline and week 16. Patients completed a daily dysphagia symptom diary through week 16 and patient-reported outcome data were collected. The primary outcome was change in mean esophageal eosinophil count in the 5 high-power fields (hpfs) with the highest level of inflammation., Results: At week 16, mean changes in esophageal eosinophil count per hpf were a reduction of 94.8 ± 67.3 in patients who received 180 mg RPC4046 (P < .0001) and a reduction of 99.9 ± 79.5 in patients who received 360 mg RPC4046 (P < .0001) compared with a reduction of 4.4 ± 59.9 in patients who received placebo. The 360-mg RPC4046 group, compared with the placebo group, showed significant reductions in validated endoscopic severity score at all esophageal locations (P < .0001), validated histologic grade and stage scores (both P < .0001), and clinician's global assessment of disease severity (P = .0352); they had a numerical reduction in scores from the dysphagia symptom diary (P = .0733). Significant reductions in esophageal eosinophil counts and histologic and endoscopic features were observed in patients with steroid-refractory EoE who received RPC4046. The most common adverse events were headache and upper respiratory tract infection., Conclusions: In a phase 2 trial of patients with EoE, we found RPC4046 (a monoclonal antibody against IL13) to reduce histologic and endoscopic features compared with placebo. RPC4046 was well tolerated. ClinicalTrials.gov no: NCT02098473., (Copyright © 2019 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Ozanimod (RPC1063) is a specific and potent small molecule modulator of the sphingosine 1-phosphate receptor 1 (S1PR1) and receptor 5 (S1PR5), which has shown therapeutic benefit in clinical trials of relapsing multiple sclerosis and ulcerative colitis. Ozanimod and its active metabolite, RP-101075, exhibit a similar specificity profile at the S1P receptor family in vitro and pharmacodynamic profile in vivo. The NZBWF1 mouse model was used in therapeutic dosing mode to assess the potential benefit of ozanimod and RP-101075 in an established animal model of systemic lupus erythematosus. Compared with vehicle-treated animals, ozanimod and RP-101075 reduced proteinuria over the duration of the study and serum blood urea nitrogen at termination. Additionally, ozanimod and RP-101075 reduced kidney disease in a dose-dependent manner, as measured by histological assessment of mesangial expansion, endo- and exo-capillary proliferation, interstitial infiltrates and fibrosis, glomerular deposits, and tubular atrophy. Further exploration into gene expression changes in the kidney demonstrate that RP-101075 also significantly reduced expression of fibrotic and immune-related genes in the kidneys. Of note, RP-101075 lowered the number of plasmacytoid dendritic cells, a major source of interferon alpha in lupus patients, and reduced all B and T cell subsets in the spleen. Given the efficacy demonstrated by ozanimod and its metabolite RP-101075 in the NZBWF1 preclinical animal model, ozanimod may warrant clinical evaluation as a potential treatment for systemic lupus erythematosus.

Cadmium (Cd) is a nephrotoxic environmental pollutant that causes a generalized dysfunction of the proximal tubule characterized by polyuria and proteinuria. Even though the effects of Cd on the kidney have been well-characterized, the molecular mechanisms underlying these effects have not been fully elucidated. MicroRNAs (miRNAs) are small non-coding RNAs that regulate cellular and physiologic function by modulating gene expression at the post-transcriptional level. The goal of the present study was to determine if Cd affects renal cortex miRNA expression in a well-established animal model of Cd-induced kidney injury. Male Sprague-Dawley rats were treated with subcutaneous injections of either isotonic saline or CdCl₂ (0.6 mg/kg) 5 days a week for 12 weeks. The 12-week Cd-treatment protocol resulted in kidney injury as determined by the development of polyuria and proteinuria, and a significant increase in the urinary biomarkers Kim-1, β₂ microglobulin and cystatin C. Total RNA was isolated from the renal cortex of the saline control and Cd treated animals, and differentially expressed miRNAs were identified using µParaflo TM microRNA microarray analysis. The microarray results demonstrated that the expression of 44 miRNAs were significantly increased and 54 miRNAs were significantly decreased in the Cd treatment group versus the saline control ( t -test, p ≤ 0.05, N = 6 per group). miR-21-5p, miR-34a-5p, miR-146b-5p, miR-149-3p, miR-224-5p, miR-451-5p, miR-1949, miR-3084a-3p, and miR-3084c-3p demonstrated more abundant expression and a significant two-fold or greater increased expression in the Cd-treatment group versus the saline control group. miR-193b-3p, miR-455-3p, and miR-342-3p demonstrated more abundant expression and a significant two-fold or greater decreased expression in the Cd-treatment group versus the saline control group. Real-time PCR validation demonstrated (1) a significant ( t -test, p ≤ 0.05, N = 6 per group) increase in expression in the Cd-treated group for miR-21-5p (2.7-fold), miR-34a-5p (10.8-fold), miR-146b-5p (2-fold), miR-224-5p (10.2-fold), miR-3084a-3p (2.4-fold), and miR-3084c-3p (3.3-fold) and (2) a significant ( t -test, p ≤ 0.05, N = 6 per group) 52% decrease in miR-455-3p expression in the Cd-treatment group. These findings demonstrate that Cd significantly alters the miRNA expression profile in the renal cortex and raises the possibility that dysregulated miRNA expression may play a role in the pathophysiology of Cd-induced kidney injury. In addition, these findings raise the possibility that Cd-dysregulated miRNAs might be used as urinary biomarkers of Cd exposure or Cd-induced kidney injury., Competing Interests: The authors have no conflicts of interest to declare.

The sphingosine-1-phosphate receptor-1 (S1P 1 ) agonist ozanimod ameliorates ulcerative colitis, yet its mechanism of action is unknown. Here, we examine the cell subsets that express S1P 1 in intestine using S1P 1 -eGFP mice, the regulation of S1P 1 expression in lymphocytes after administration of dextran sulfate sodium (DSS), after colitis induced by transfer of CD4 + CD45RB hi cells, and by crossing a mouse with TNF-driven ileitis with S1P 1 -eGFP mice. We then assayed the expression of enzymes that regulate intestinal S1P levels, and the effect of FTY720 on lymphocyte behavior and S1P 1 expression. We found that not only T and B cells express S1P 1 , but also dendritic (DC) and endothelial cells. Furthermore, chronic but not acute inflammatory signals increased S1P 1 expression, while the enzymes that control tissue S1P levels in mice and humans with inflammatory bowel disease (IBD) were uniformly dysregulated, favoring synthesis over degradation. Finally, we observed that FTY720 reduced T-cell velocity and induced S1P 1 degradation and retention of Naïve but not effector T cells. Our data demonstrate that chronic inflammation modulates S1P 1 expression and tissue S1P levels and suggests that the anti-inflammatory properties of S1PR agonists might not be solely due to their lymphopenic effects, but also due to potential effects on DC migration and vascular barrier function.

The sphingosine 1 phosphate receptor family has been studied widely since the initial discovery of its first member, endothelium differentiation gene 1. Since this initial discovery, the family has been renamed and the primary member of the family, the S1P1 receptor, has been targeted for a variety of disease indications and successfully drugged for the treatment of patients with relapsing multiple sclerosis. Recently, the three-dimensional structure of the S1P1 receptor has been determined by X-ray crystallography and the specifics of the sphingosine 1 phosphate ligand binding pocket mapped. Key structural features for the S1P1 receptor will be reviewed and the potential binding modes of additional pharmacologically active agents against the receptor will be analyzed in an effort to better understand the structural basis of important receptor-ligand interactions.

We report our experimental results for linear analog optical links that use phase or frequency modulation and optical discrimination. The discriminators are based on two architectures: a cascaded MZI FIR lattice filter and a ring assisted MZI (RAMZI) IIR filter. For both types of discriminators, we demonstrate > 6 dB improvement in the link's third-order output intercept point (OIP3) over a MZM link. We show that the links have low second-order distortion when using balanced detection. Using high optical power, we demonstrate an OIP3 of 39.2 dBm. We also demonstrate 4.3dB improvement in signal compression.

Cytokine storm during viral infection is a prospective predictor of morbidity and mortality, yet the cellular sources remain undefined. Here, using genetic and chemical tools to probe functions of the S1P(1) receptor, we elucidate cellular and signaling mechanisms that are important in initiating cytokine storm. Whereas S1P(1) receptor is expressed on endothelial cells and lymphocytes within lung tissue, S1P(1) agonism suppresses cytokines and innate immune cell recruitment in wild-type and lymphocyte-deficient mice, identifying endothelial cells as central regulators of cytokine storm. Furthermore, our data reveal immune cell infiltration and cytokine production as distinct events that are both orchestrated by endothelial cells. Moreover, we demonstrate that suppression of early innate immune responses through S1P(1) signaling results in reduced mortality during infection with a human pathogenic strain of influenza virus. Modulation of endothelium with a specific agonist suggests that diseases in which amplification of cytokine storm is a significant pathological component could be chemically tractable., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Background: The X-linked Inhibitor of Apoptosis (XIAP) has attracted much attention as a cancer drug target. It is the only member of the IAP family that can directly inhibit caspase activity in vitro, and it can regulate apoptosis and other biological processes through its C-terminal E3 ubiquitin ligase RING domain. However, there is controversy regarding XIAP's role in regulating tumor cell proliferation and survival under normal growth conditions in vitro., Methods: We utilized siRNA to systematically knock down XIAP in ten human tumor cell lines and then monitored both XIAP protein levels and cell viability over time. To examine the role of XIAP in the intrinsic versus extrinsic cell death pathways, we compared the viability of XIAP depleted cells treated either with a variety of mechanistically distinct, intrinsic pathway inducing agents, or the canonical inducer of the extrinsic pathway, TNF-related apoptosis-inducing ligand (TRAIL)., Results: XIAP knockdown had no effect on the viability of six cell lines, whereas the effect in the other four was modest and transient. XIAP knockdown only sensitized tumor cells to TRAIL and not the mitochondrial pathway inducing agents., Conclusions: These data indicate that XIAP has a more central role in regulating death receptor mediated apoptosis than it does the intrinsic pathway mediated cell death.

The ability of interleukin-10 (IL-10) to suppress accessory cell functions required for optimal T-cell activation makes it an important inhibitor of cell-mediated immunity. Thus, after infection with the protozoan parasite Toxoplasma gondii, IL-10 knockout (KO) mice develop a CD4(+)-T-cell-dependent shock-like reaction with high levels of IL-12 and gamma interferon (IFN-gamma) in serum, leading to death of mice during the acute phase of infection. Previous studies from this laboratory have shown that simultaneous blockade of CD28 and CD40 can prevent this lethal reaction by inhibiting the production of IFN-gamma. However, the blockade of costimulation did not affect systemic levels of IL-12. To better understand the relationship between IL-12 and the CD28 and CD40 pathways in mediating immune hyperactivity, antagonists of these factors were used to determine their effects on the development of a pathological T-cell response in IL-10 KO mice. Blockade of IL-12 or the CD28/B7 interaction alone did not affect survival; however, the combined blockade of both pathways resulted in decreased production of IFN-gamma and the survival of IL-10 KO mice. To assess the role of the two ligands for CD28, B7.1 and B7.2, IL-10 KO mice were treated with alphaIL-12 plus alphaB7.1 or alphaB7.2 or the combination of all three antibodies. These studies revealed that blockade of both B7 molecules is required for decreased production of IFN-gamma and survival of infected IL-10 KO mice, suggesting that B7.1 and B7.2 can contribute to the lethal shock-like reaction in IL-10 KO mice. In contrast, neutralization of IL-12 and blockade of the CD40/CD40 ligand (CD40L) interaction in vivo did not alter the production of IFN-gamma and only resulted in a small delay in time to death of mice. Together, these data suggest that the CD28/B7 interaction has a central role in the development of a pathological T-cell response in IL-10 KO mice, which is distinct from the role of the CD40/CD40L and IL-12 pathways.

Long-term resistance to Toxoplasma gondii is dependent on the development of parasite-specific T cells that produce IFN-gamma. CD28 is a costimulatory molecule important for optimal activation of T cells, but CD28(-/-) mice are resistant to T. gondii, demonstrating that CD28-independent mechanisms regulate T cell responses during toxoplasmosis. The identification of the B7-related protein 1/inducible costimulator protein (ICOS) pathway and its ability to regulate the production of IFN-gamma suggested that this pathway may be involved in the CD28-independent activation of T cells required for resistance to T. gondii. In support of this hypothesis, infection of wild-type or CD28(-/-) mice with T. gondii resulted in the increased expression of ICOS by activated CD4(+) and CD8(+) T cells. In addition, both costimulatory pathways contributed to the in vitro production of IFN-gamma by parasite-specific T cells and when both pathways were blocked, there was an additive effect that resulted in almost complete inhibition of IFN-gamma production. Although in vivo blockade of the ICOS costimulatory pathway did not result in the early mortality of wild-type mice infected with T. gondii, it did lead to increased susceptibility of CD28(-/-) mice to T. gondi associated with reduced serum levels of IFN-gamma, increased parasite burden, and increased mortality compared with the control group. Together, these results identify a critical role for ICOS in the protective Th1-type response required for resistance to T. gondii and suggest that ICOS and CD28 are parallel costimulatory pathways, either of which is sufficient to mediate resistance to this intracellular pathogen.

Costimulatory pathways have a pivotal role in the T-cell response to alloantigen. The role of costimulatory blockade with anti-CD154 in orthotopic liver transplantation (OLT) has not been examined previously. This study aims to investigate effects of anti-CD154 and CTLA4-immunoglobulin (Ig) in the early post-OLT period using a major histocompatibility complex-disparate fully arterialized OLT model in the rat. Lewis rats underwent OLT with Dark Agouti liver allografts. Recipients were randomized to receive (1) isotype control, (2) anti-CD154, (3) CTLA4-Ig, or (4) cyclosporine A (CyA). Rats were killed day 8, and specimens were obtained for histological examination, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling, immunohistochemistry, and quantitative reverse-transcriptase polymerase chain reaction. An additional five transplant recipients were treated with anti-CD154 for 14 days postoperatively to assess long-term allograft survival. All isotype control animals died on or before day 6 of acute rejection. Apart from four deaths caused by nonimmunologic causes, all treated recipients survived to day 8. The median survival of rats treated for 14 days with anti-CD154 was greater than 150 days. Serum aspartate aminotransferase and bilirubin levels normalized by day 3 in the CyA group and day 5 in transplant recipients treated with costimulatory blockade. Histologically, there was no difference between isotype controls and CTLA4-Ig-treated animals, whereas anti-CD154-treated transplant recipients had a lower Banff score. CD4+ and CD8+ T-cell infiltrates were prominent in transplant recipients treated with costimulatory blockade. Intragraft analysis showed an increase in lymphocyte apoptosis, Fas ligand messenger RNA expression, and reduction in interleukin-6 gene expression in transplant recipients treated with costimulatory blockade. Costimulatory blockade did not alter intragraft gene expression of other mediators of T-cell priming, differentiation, and effector function compared with isotype control animals. In conclusion, costimulatory blockade prevented acute rejection, enabled long-term survival, and increased intragraft lymphocyte apoptosis in a high-responding rat OLT model.

To address whether a functional dichotomy exists between CD80 and CD86 in naive T cell activation in vivo, we administered anti-CD80 or CD86 blocking mAb alone or in combination to mice with parent-into-F(1) graft-vs-host disease (GVHD). In this model, the injection of naive parental T cells into unirradiated F(1) mice results in either a Th1 cytokine-driven, cell-mediated immune response (acute GVHD) or a Th2 cytokine-driven, Ab-mediated response (chronic GVHD) in the same F(1) recipient. Combined CD80/CD86 blockade beginning at the time of donor cell transfer mimicked previous results seen with CTLA4Ig and completely abrogated either acute or chronic GVHD by preventing the activation and maturation of donor CD4(+) T cells as measured by a block in acquisition of memory marker phenotype and cytokine production. Similar results were seen with selective CD86 blockade; however, the degree of CD4 inhibition was always less than that seen with combined CD80/CD86 blockade. A more striking effect was seen with selective CD80 blockade in that chronic GVHD was converted to acute GVHD. This effect was associated with the induction of Th1 cytokine production, donor CD8(+) T cell activation, and development of antihost CTL. The similarity of this effect to that reported for selective CTLA4 blockade suggests that CD80 is a critical ligand for CTLA4 in mediating the down-regulation of Th1 responses and CD8(+) T cell activation. In contrast, CD86 is critical for the activation of naive CD4(+) T cells in either a Th1 or a Th2 cytokine-mediated response.

Previous work has demonstrated that short-term systemic administration of cytotoxic T lymphocyte antigen-4 (CTLA-4) Ig blocks human pancreatic islet xenograft rejection in mice and induces long-term, donor-specific tolerance, whereas studies on pig pancreatic islet rejection in mice have failed to demonstrate a role for CTLA4Ig in preventing rejection. Treatment with anti-CD40 ligand (L) monoclonal antibodies alone is somewhat effective in prolonging the survival of islet xenografts, but ineffective when applied to skin xenografts. However, simultaneous blockade of the CD28 and CD40 co-stimulatory pathways prolongs the survival of pig skin on recipient mice. To evaluate the role of CD28 and CD40 co-stimulatory pathways in pig islet-like cell cluster (ICC) xenograft rejection in mice, CD40L-deficient mice transplanted with fetal porcine ICCs were given posttransplant treatment with human (h) CTLA4Ig or a human IgG1 chimeric mAb (hL6). Xenografts were evaluated 6 or 12 days after transplantation. Fetal porcine ICC xenografts were protected from rejection in hCTLA4Ig-treated CD40L-deficient mice, whereas xenograft rejection persisted in untreated CD40L-deficient mice. Simultaneous blockade of the CD28 and CD40 co-stimulatory pathways is mandatory to inhibit ICC xenograft rejection in the pig-to-mouse model, because the CD28 and CD40 co-stimulatory pathways seem capable of efficiently substituting for one another.

The existence of surface waves on anisotropic materials was proven under fairly general conditions by Lothe and Barnett in 1976 [1]. But, until now, the status of surface waves on piezoelectric materials has remained unresolved. This paper presents general existence theorems for surface waves on piezoelectric substrates. It is demonstrated that for short circuit boundary conditions a surface wave solution must exist under virtually any circumstances. However, for a free surface, comparatively stringent existence conditions are required. Numerical examples are given for both free and shorted surfaces, and it is demonstrated that, in some situations, a surface wave solution may not exist for free surface propagation. The existence proofs were developed as a result of theoretical work on Green function modeling, which is now the preferred technique for rigorous SAW and pseudo-SAW device analysis. The mechanisms of the existence proofs and the associated mathematical results give great insight into the structure and properties of the Green functions and include many results that are directly relevant to device analysis.

Provision of adequate T cell costimulation is critical for the development of acute and chronic allograft rejection. We have previously reported that early blockade of CD28-B7 T cell costimulation prevents the development of graft arteriosclerosis, in the LEW into F344 rat cardiac transplant model. In this study, we used the same model to examine the requirement for CD28-B7-mediated T cell costimulation in the progression of established chronic rejection and examined the individual roles of B7-1 (CD80) and B7-2 (CD86) costimulatory molecules. Late blockade of CD28-B7 T cell costimulation by the fusion protein CTLA4Ig, which binds both CD80 and CD86, attenuated the development of transplant arteriosclerosis, mononuclear cell infiltration, and parenchymal fibrosis in this model. Selective blockade of CD80 using the mutant fusion protein Y100F was as effective as CTLA4Ig in this regard. In contrast to CTLA4Ig, blockade of CD80 alone by Y100F was ineffective at preventing early graft loss and prolonging graft survival when given early after transplantation. This study is the first to demonstrate that late blockade of CD28-B7 T cell costimulation interrupts chronic cardiac allograft rejection, and it indicates the importance of continued T cell activation in this process. This study further defines functional differences between CD80 and CD86 costimulatory molecules in vivo.

The requirements for B7 costimulation during an in vivo humoral response to an intact extracellular bacteria have not been reported. In this study we immunized mice with Streptococcus pneumoniae (R36A) to determine the B7 requirements for induction of Ig, specific for two determinants on R36A, the phosphorylcholine (PC) determinant of C-polysaccharide and pneumococcal surface protein A (PspA). We show that the primary anti-PspA response, the development of PspA-specific memory, and the induction of the secondary anti-PspA response in primed mice were completely dependent upon B7 costimulation. Of note, costimulation was required only briefly after the secondary immunization compared with after the primary immunization for optimal induction of Ig. Blockade of B7 costimulation at the time of secondary immunization also completely abrogated the established state of memory, but did not induce tolerance. In contrast to the anti-PspA response, the primary anti-PC response involved only a very short period of B7 costimulation. Whereas B7-2 alone was required for induction of the primary anti-PspA and anti-PC responses, a redundant role for B7-1 and B7-2 was noted for the PspA-specific secondary response. CTLA4Ig blocked both the anti-PC and anti-PspA responses equally well over a wide range of bacterial doses. These studies demonstrate a critical, but variable, role for B7-dependent costimulation during an Ig response to an extracellular bacteria.

Abscesses are a classic host response to infection by many pathogenic bacteria. The immunopathogenesis of this tissue response to infection has not been fully elucidated. Previous studies have suggested that T cells are involved in the pathologic process, but the role of these cells remains unclear. To delineate the mechanism by which T cells mediate abscess formation associated with intra-abdominal sepsis, the role of T-cell activation and the contribution of antigen-presenting cells via CD28-B7 costimulation were investigated. T cells activated in vitro by zwitterionic bacterial polysaccharides (Zps) known to induce abscess formation required CD28-B7 costimulation and, when adoptively transferred to the peritoneal cavity of naïve rats, promoted abscess formation. Blockade of T-cell activation via the CD28-B7 pathway in animals with CTLA4Ig prevented abscess formation following challenge with different bacterial pathogens, including Staphylococcus aureus, Bacteroides fragilis, and a combination of Enterococcus faecium and Bacteroides distasonis. In contrast, these animals had an increased abscess rate following in vivo T-cell activation via CD28 signaling. Abscess formation in vivo and T-cell activation in vitro required costimulation by B7-2 but not B7-1. These results demonstrate that abscess formation by pathogenic bacteria is under the control of a common effector mechanism that requires T-cell activation via the CD28-B7-2 pathway.

Interleukin-10 (IL-10) is associated with inhibition of cell-mediated immunity and downregulation of the expression of costimulatory molecules required for T-cell activation. When IL-10-deficient (IL-10KO) mice are infected with Toxoplasma gondii, they succumb to a T-cell-mediated shock-like reaction characterized by the overproduction of IL-12 and gamma interferon (IFN-gamma) associated with widespread necrosis of the liver. Since costimulation is critical for T-cell activation, we investigated the role of the CD28-B7 and CD40-CD40 ligand (CD40L) interactions in this infection-induced immunopathology. Our studies show that infection of mice with T. gondii resulted in increased expression of B7 and CD40 that was similar in wild-type and IL-10KO mice. In vivo blockade of the CD28-B7 or CD40-CD40L interactions following infection of IL-10KO mice with T. gondii did not affect serum levels of IFN-gamma or IL-12, nor did it prevent death in these mice. However, when both pathways were blocked, the IL-10KO mice survived the acute phase of infection and had reduced serum levels of IFN-gamma and alanine transaminase as well as decreased expression of inducible nitric oxide synthase in the liver and spleen. Analysis of parasite-specific recall responses from infected IL-10KO mice revealed that blockade of the CD40-CD40L interaction had minimal effects on cytokine production, whereas blockade of the CD28-B7 interaction resulted in decreased production of IFN-gamma but not IL-12. Further reduction of IFN-gamma production was observed when both costimulatory pathways were blocked. Together, these results demonstrate that the CD28-B7 and CD40-CD40L interactions are involved in the development of infection-induced immunopathology in the absence of IL-10.

B7 costimulation is a required component of many type 2 immune responses, including allergy and protective immunity to many nematode parasites. This response includes elevations in Th2 cytokines and associated effector functions including elevations in serum IgG1 and IgE and parasite expulsion. In studies of mice infected with Trichuris muris, blocking B7 ligand interactions inhibited protective immunity, suppressed IL-4 production, and enhanced IFN-gamma production, but unexpectedly did not inhibit production of the Th2 cytokine, IL-13. Blocking both IFN-gamma and B7 restored protective immunity, which was IL-13 dependent, but did not restore IL-4 or associated IgE responses. Although IL-13 was required for worm expulsion in mice in which both IFN-gamma and B7 were blocked, IL-4 could mediate expulsion in the absence of both IL-13 and IFN-gamma. These studies demonstrate that 1) B7 costimulation is required to induce IL-4, but not IL-13 responses; 2) IL-13 is elevated in association with the IFN-gamma response that occurs following inhibition of B7 interactions, but can only mediate IL-4-independent protection when IFN-gamma is also inhibited; and 3) increased IL-13 production, in the absence of increased IL-4 production, is not associated with an IgE response, even in the absence of IFN-gamma.

Experimental autoimmune glomerulonephritis (EAG), an animal model of Goodpasture's disease, can be induced in Wistar Kyoto (WKY) rats by a single injection of rat glomerular basement membrane (GBM) in adjuvant. EAG is characterized by circulating and deposited anti-GBM antibodies, accompanied by focal necrotizing glomerulonephritis with crescent formation. The role of T cells in the pathogenesis of EAG remains unclear. T-cell costimulation is provided by ligation of CD28 with either B7.1 (CD80) or B7.2 (CD86) on antigen-presenting cells, and can be inhibited by a soluble form of CTLA4 (CTLA4-Ig) that binds to both B7.1 and B7.2. We examined the effect of CD28-B7 blockade on the development of EAG using native CTLA4-Ig or mutant CTLA4-Ig (Y100F-Ig), which selectively blocks B7.1. Native CTLA4-Ig treatment ameliorated EAG by several measures, including the levels of circulating anti-GBM antibodies, albuminuria, the deposition of IgG and fibrin in the glomeruli, the severity of glomerular abnormalities, and the numbers of infiltrating T cells and macrophages. Y100F-Ig resulted in a similar reduction in the severity of nephritis, but produced no overall reduction in circulating anti-GBM antibodies, although there was a reduction in IgG2a antibodies. We concluded that CD28-B7 blockade reduced autoantibody production and cellular infiltration of glomeruli, and prevented target organ injury. Our results suggest a key role for B7. 1 in costimulation of Th1-like autoimmune responses in the rat, and show that glomerular injury in EAG is largely dependent on cell-mediated mechanisms.