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Adoption of high-content omic technologies in clinical studies, coupled with computational methods, has yielded an abundance of candidate biomarkers. However, translating such findings into bona fide clinical biomarkers remains challenging. To facilitate this process, we introduce Stabl, a general machine learning method that identifies a sparse, reliable set of biomarkers by integrating noise injection and a data-driven signal-to-noise threshold into multivariable predictive modeling. Evaluation of Stabl on synthetic datasets and five independent clinical studies demonstrates improved biomarker sparsity and reliability compared to commonly used sparsity-promoting regularization methods while maintaining predictive performance; it distills datasets containing 1,400-35,000 features down to 4-34 candidate biomarkers. Stabl extends to multi-omic integration tasks, enabling biological interpretation of complex predictive models, as it hones in on a shortlist of proteomic, metabolomic and cytometric events predicting labor onset, microbial biomarkers of pre-term birth and a pre-operative immune signature of post-surgical infections. Stabl is available at https://github.com/gregbellan/Stabl .

Ischemic stroke (IS) is the leading cause of acquired disability and the second leading cause of dementia and mortality. Current treatments for IS are primarily focused on revascularization of the occluded artery. However, only 10% of patients are eligible for revascularization and 50% of revascularized patients remain disabled at 3 months. Accumulating evidence highlight the prognostic significance of the neuro- and thrombo-inflammatory response after IS. However, several randomized trials of promising immunosuppressive or immunomodulatory drugs failed to show positive results. Insufficient understanding of inter-patient variability in the cellular, functional, and spatial organization of the inflammatory response to IS likely contributed to the failure to translate preclinical findings into successful clinical trials. The inflammatory response to IS involves complex interactions between neuronal, glial, and immune cell subsets across multiple immunological compartments, including the blood-brain barrier, the meningeal lymphatic vessels, the choroid plexus, and the skull bone marrow. Here, we review the neuro- and thrombo-inflammatory responses to IS. We discuss how clinical imaging and single-cell omic technologies have refined our understanding of the spatial organization of pathobiological processes driving clinical outcomes in patients with an IS. We also introduce recent developments in machine learning statistical methods for the integration of multi-omic data (biological and radiological) to identify patient-specific inflammatory states predictive of IS clinical outcomes.

Surgical Site Complications (SSCs) may occur in up to 25% of patients undergoing bowel resection, resulting in significant morbidity and economic burden. However, the accurate prediction of SSCs remains clinically challenging. Leveraging high-content proteomic technologies to comprehensively profile patients’ immune response to surgery is a promising approach to identify predictive biological factors of SSCs.

Estimating the time of delivery is of high clinical importance because pre- and postterm deviations are associated with complications for the mother and her offspring. However, current estimations are inaccurate. As pregnancy progresses toward labor, major transitions occur in fetomaternal immune, metabolic, and endocrine systems that culminate in birth. The comprehensive characterization of maternal biology that precedes labor is key to understanding these physiological transitions and identifying predictive biomarkers of delivery. Here, a longitudinal study was conducted in 63 women who went into labor spontaneously. More than 7000 plasma analytes and peripheral immune cell responses were analyzed using untargeted mass spectrometry, aptamer-based proteomic technology, and single-cell mass cytometry in serial blood samples collected during the last 100 days of pregnancy. The high-dimensional dataset was integrated into a multiomic model that predicted the time to spontaneous labor [R = 0.85, 95% confidence interval (CI) [0.79 to 0.89], P = 1.2 × 10-40, N = 53, training set; R = 0.81, 95% CI [0.61 to 0.91], P = 3.9 × 10-7, N = 10, independent test set]. Coordinated alterations in maternal metabolome, proteome, and immunome marked a molecular shift from pregnancy maintenance to prelabor biology 2 to 4 weeks before delivery. A surge in steroid hormone metabolites and interleukin-1 receptor type 4 that preceded labor coincided with a switch from immune activation to regulation of inflammatory responses. Our study lays the groundwork for developing blood-based methods for predicting the day of labor, anchored in mechanisms shared in preterm and term pregnancies.

Chronic Periodontitis (ChP) is a prevalent inflammatory disease affecting 46% of the US population. ChP produces a profound local inflammatory response to dysbiotic oral microbiota that leads to destruction of alveolar bone and tooth loss. ChP is also associated with systemic illnesses including cardiovascular diseases, malignancies, and adverse pregnancy outcomes. However, the mechanisms underlying these adverse health outcomes are poorly understood. We used a highly multiplex mass cytometry immunoassay to perform an in-depth analysis of the systemic consequences of ChP in patients, before and after periodontal treatment in this prospective cohort study. A high-dimensional analysis of intracellular signaling networks revealed immune system-wide dysfunctions differentiating patients with ChP from healthy controls. Notably, we observed exaggerated pro-inflammatory responses to P. gingivalis-derived lipopolysaccharide in circulating neutrophils and monocytes from patients with ChP. Simultaneously, natural killer cell responses to inflammatory cytokines were attenuated. Importantly, the immune alterations associated with ChP were no longer detectable three weeks after periodontal treatment. Our findings demarcate systemic and cell-specific immune dysfunctions in patients with ChP which can be temporarily reversed by the local treatment of ChP.

BACKGROUND:Nitrosation of a conserved cysteine residue at position 93 in the hemoglobin β chain (β93C) to form S-nitroso (SNO) hemoglobin (Hb) is claimed to be essential for export of nitric oxide (NO) bioactivity by the red blood cell (RBC) to mediate hypoxic vasodilation and cardioprotection. METHODS:To test this hypothesis, we used RBCs from mice in which the β93 cysteine had been replaced with alanine (β93A) in a number of ex vivo and in vivo models suitable for studying export of NO bioactivity. RESULTS:In an ex vivo model of cardiac ischemia/reperfusion injury, perfusion of a mouse heart with control RBCs (β93C) pretreated with an arginase inhibitor to facilitate export of RBC NO bioactivity improved cardiac recovery after ischemia/reperfusion injury, and the response was similar with β93A RBCs. Next, when human platelets were coincubated with RBCs and then deoxygenated in the presence of nitrite, export of NO bioactivity was detected as inhibition of ADP-induced platelet activation. This effect was the same in β93C and β93A RBCs. Moreover, vascular reactivity was tested in rodent aortas in the presence of RBCs pretreated with S-nitrosocysteine or with hemolysates or purified Hb treated with authentic NO to form nitrosyl(FeII)-Hb, the proposed precursor of SNO-Hb. SNO-RBCs or NO-treated Hb induced vasorelaxation, with no differences between β93C and β93A RBCs. Finally, hypoxic microvascular vasodilation was studied in vivo with a murine dorsal skin-fold window model. Exposure to acute systemic hypoxia caused vasodilatation, and the response was similar in β93C and β93A mice. CONCLUSIONS:RBCs clearly have the fascinating ability to export NO bioactivity, but this occurs independently of SNO formation at the β93 cysteine of Hb.

MotivationMultiple biological clocks govern a healthy pregnancy. These biological mechanisms produce immunologic, metabolomic, proteomic, genomic and microbiomic adaptations during the course of pregnancy. Modeling the chronology of these adaptations during full-term pregnancy provides the frameworks for future studies examining deviations implicated in pregnancy-related pathologies including preterm birth and preeclampsia.ResultsWe performed a multiomics analysis of 51 samples from 17 pregnant women, delivering at term. The datasets included measurements from the immunome, transcriptome, microbiome, proteome and metabolome of samples obtained simultaneously from the same patients. Multivariate predictive modeling using the Elastic Net (EN) algorithm was used to measure the ability of each dataset to predict gestational age. Using stacked generalization, these datasets were combined into a single model. This model not only significantly increased predictive power by combining all datasets, but also revealed novel interactions between different biological modalities. Future work includes expansion of the cohort to preterm-enriched populations and in vivo analysis of immune-modulating interventions based on the mechanisms identified.Availability and implementationDatasets and scripts for reproduction of results are available through: https://nalab.stanford.edu/multiomics-pregnancy/.Supplementary informationSupplementary data are available at Bioinformatics online.

There is a 0.138% incidence of adverse reactions related to blood transfusion. Transfusion-related acute lung injury, immunosuppression, fever, pathogen transmission, and hemolytic transfusion reactions are the most common ones. Synthetic oxygen carriers have been developed to deal with blood shortages and for use in the field where stored blood was not available. They were also designed to be pathogen free, including unknown viruses. In this study, we used Male Golden Syrian Hamsters implemented with a dorsal window chamber to determine how infusion of three different, genetically crosslinked recombinant acellular hemoglobin (rHb) solutions with different oxygen affinities and nitric oxide kinetics affect mean arterial pressure (MAP), heart rate (HR), kidney function, and kidney structure. We found that the administration of all three rHb solutions caused mild hypertension and bradycardia 30 minutes after infusion. However, acute changes in glomerular filtration rate (GFR) were not detected, even though histological analysis was performed 72 hours after treatment revealed some structural changes. All the rHb solutions resulted in hypertension 30 minutes after a 10% topload administration. Regardless of their properties, the presence of acellular Hb causes significant alterations to kidney tissue.

At least a third of the blood supply in the world is used to transfuse 1-2 units of packed red blood cells for each intervention and most clinical trials of blood substitutes have been carried out at this level of oxygen carrying capacity (OCC) restoration. However, the increase of oxygenation achieved is marginal or none at all for molecular hemoglobin (Hb) products, due to their lingering vasoactivity. This has provided the impetus for the development of "oxygen therapeutics" using Hb-based molecules that have high oxygen affinity and target delivery of oxygen to anoxic areas. However it is still unclear how these oxygen carriers counteract or mitigate the functional effects of anemia due to obstruction, vasoconstriction and under-perfusion. Indeed, they are administered as a low dosage/low volume therapeutic Hb (subsequently further diluted in the circulatory pool) and hence induce extremely small OCC changes. Hyperviscous plasma expanders provide an alternative to oxygen therapeutics by increasing the oxygen delivery capacity (ODC); in anemia they induce supra-perfusion and increase tissue perfusion (flow) by as much as 50%. Polyethylene glycol conjugate albumin (PEG-Alb) accomplishes this by enhancing the shear thinning behavior of diluted blood, which increases microvascular endothelial shear stress, causes vasodilation and lowering peripheral vascular resistance thus facilitating cardiac function. Induction of supra-perfusion takes advantage of the fact that ODC is the product of OCC and blood flow and hence can be maintained by increasing either or both. Animal studies suggest that this approach may save a considerable fraction of the blood supply. It has an additional benefit of enhancing tissue clearance of toxic metabolites.

ObjectivesDilutional coagulopathy after resuscitation with crystalloids/colloids clinically often appears as diffuse microvascular bleeding. Administration of fibrinogen reduces bleeding and increases maximum clot firmness, measured by thromboelastometry. Study objective was to implement a model where microvascular bleeding can be directly assessed by visualizing clot formation in microvessels, and correlations can be made to thromboelastometry.DesignRandomized animal study.SettingUniversity research laboratory.SubjectsMale Syrian Golden hamsters.InterventionsMicrovessels of Syrian Golden hamsters fitted with a dorsal window chamber were studied using videomicroscopy. After 50% hemorrhage followed by 1 hour of hypovolemia resuscitation with 35% of blood volume using a high-molecular-weight hydroxyethyl starch solution (Hextend, Hospira, MW 670 kD) occurred. Animals were then treated with 250 mg/kg fibrinogen IV (Laboratoire français du Fractionnement et des Biotechnologies, Paris, France) or an equal volume of saline before venular vessel wall injuries was made by directed laser irradiation, and the ability of microthrombus formation was assessed.Measurements and main resultsThromboelastometric measurements of maximum clot firmness were performed at the beginning and at the end of the experiment. Resuscitation with hydroxyethyl starch and sham treatment significantly decreased FIBTEM maximum clot firmness from 32 ± 9 mm at baseline versus 13 ± 5 mm after sham treatment (p < 0.001). Infusion of fibrinogen concentrate significantly increased maximum clot firmness, restoring baseline levels (baseline 32 ± 9 mm; after fibrinogen administration 29 ± 2 mm). In vivo microthrombus formation in laser-injured vessels significantly increased in fibrinogen-treated animals compared with sham (77% vs 18%).ConclusionsFibrinogen treatment leads to increased clot firmness in dilutional coagulopathy as measured with thromboelastometry. At the microvascular level, this increased clot strength corresponds to an increased prevalence of thrombus formation in vessels injured by focused laser irradiation.

Objective: The longitudinal assessment of physical function with high temporal resolution at a scalable and objective level in patients recovering from surgery is highly desirable to understand the biological and clinical factors that drive the clinical outcome. However, physical recovery from surgery itself remains poorly defined and the utility of wearable technologies to study recovery after surgery has not been established. Background: Prolonged postoperative recovery is often associated with long-lasting impairment of physical, mental, and social functions. Although phenotypical and clinical patient characteristics account for some variation of individual recovery trajectories, biological differences likely play a major role. Specifically, patient-specific immune states have been linked to prolonged physical impairment after surgery. However, current methods of quantifying physical recovery lack patient specificity and objectivity. Methods: Here, a combined high-fidelity accelerometry and state-of-the-art deep immune profiling approach was studied in patients undergoing major joint replacement surgery. The aim was to determine whether objective physical parameters derived from accelerometry data can accurately track patient-specific physical recovery profiles (suggestive of a 'clock of postoperative recovery'), compare the performance of derived parameters with benchmark metrics including step count, and link individual recovery profiles with patients' preoperative immune state. Results: The results of our models indicate that patient-specific temporal patterns of physical function can be derived with a precision superior to benchmark metrics. Notably, 6 distinct domains of physical function and sleep are identified to represent the objective temporal patterns: "activity capacity" and "moderate and overall activity (declined immediately after surgery); "sleep disruption and sedentary activity (increased after surgery); "overall sleep", "sleep onset", and "light activity" (no clear changes were observed after surgery). These patterns can be linked to individual patients preopera-tive immune state using cross-validated canonical-correlation analysis. Importantly, the pSTAT3 signal activity in monocytic myeloid-derived suppressor cells predicted a slower recovery. Conclusions: Accelerometry-based recovery trajectories are scalable and objective outcomes to study patient-specific factors that drive physical recovery. [ABSTRACT FROM AUTHOR]

The hematocrit (Hct) of awake hamsters was lowered to 90% of baseline by isovolemic hemodilution using hamster plasma to determine the acute effect of small changes in Hct and blood viscosity on systemic hemodynamics. Mean arterial blood pressure increased, reaching a maximum of about 10% above baseline (8.6 [+ or -] 5.5 mmHg) when Hct decreased 8.4 [+ or -] 1.9% (P < 0.005). Cardiac output increased continuously with hemodilution. These conditions were reached at ~60 min after exchange transfusion and remained stationary for 1 h. Peripheral vascular resistance was approximately constant up to a decrease of Hct of about 10% and then fell continuously with lowering Hct. Vascular hindrance or vascular resistance independent of blood viscosity increased by about 20% and remained at this level up to an Hct decrease of 20%, indicating that the vasculature constricted with the lowered Hct. The results for the initial 2-h period are opposite but continuous with previous findings with small increases in Hct. In conclusion, limited acute anemic conditions increase mean arterial blood pressure during the initial period of 2 h, an effect that is quantitatively similar but opposite to the acute increase of Hct during the same period. hemodilution; acute anemia; blood viscosity; nitric oxide doi: 10.1152/ajpheart.00496.2010.

[O.sub.2]-carrying fluids based on hemoglobin (Hb) are in various stages of clinical trials to determine their suitability as [O.sub.2]-carrying plasma expanders. Polymerized Hb solutions are characterized by their vasoactivity, low [O.sub.2] affinity, oncotic effect, prolonged shelf life, and stability. Physiological responses to facilitated [O.sub.2] transport after exchange transfusion with polymerized bovine Hb (PBH) were studied in the hamster window chamber model during acute moderate anemia to determine how PBH affects microvascular perfusion and tissue oxygenation. The anemic state [29% hematocrit (Hct)] was induced by hemodilution with a plasma expander (70 kDa dextran). After hemodilution, animals were randomly assigned to different exchange transfusion groups. Study groups were based on the concentration of PBH used, namely: PBH at 13 g Hb/dl [PBH13], PBH diluted to 8 (PBH8) or 4 (PBH4) g Hb/dl in albumin solution at matching colloidal osmotic pressure (COP), and no PBH (only albumin solution) at matching COP (PBH0). Measurement of systemic parameters, microvascular hemodynamics, capillary perfusion, and intravascular and tissue 02 levels was performed at 18% Hct. Restitution of [O.sub.2]-carrying capacity with PBH13 increased arterial pressure and triggered vasoconstriction, low perfusion, and high peripheral resistance. PBH4 and PBH0 exhibited lower arterial pressures compared with PBH 13. Exchange transfused animals with PBH8 and PBH4 better maintained perfusion and functional capillary density than PBH13. Blood gas parameters and acid-base balance were recovered proportional to microvascular perfusion. Arterial [O.sub.2] tensions were improved with PBH4 and PBH8 by preventing [O.sub.2] precapillary release and increasing 02 reserve. Further studies to establish PBH optimal dosage, efficacy, safety, and its effect on outcome are indicated before Hb-based [O.sub.2]-carrying blood substitutes are implemented in routine practice. microcirculation; red blood cells; hemodilution; functional capillary density; hemoglobin oxygen affinity; tissue oxygen.

The hamster window chamber model was used to study systemic and microvascular hemodynamic responses to extreme hemodilution with low- and high-viscosity plasma expanders (LVPE and HVPE, respectively) to determine whether plasma viscosity is a factor in homeostasis during extreme anemic conditions. Moderated hemodilution was induced by two isovolemic steps performed with 6% 70-kDa dextran until systemic hematocrit (Hct) was reduced to 18% (level 2). In a third isovolemic step, hemodilution with LVPE (6% 70-kDa dextran, 2.8 cP) or HVPE (6% 500-kDa dextran, 5.9 cP) reduced Hct to 11%. Systemic parameters, cardiac output (CO), organ flow distribution, microhemodynamics, and functional capillary density, were measured after each exchange dilution. Fluorescent-labeled microspheres were used to measure organ (brain, heart, kidney, liver, lung, and spleen) and window chamber blood flow. Final blood and plasma viscosities after the entire protocol were 2.1 and 1.4 cP, respectively, for LVPE and 2.8 and 2.2 cP, respectively, for HVPE (baseline = 4.2 and 1.2 cP, respectively). HVPE significantly elevated mean arterial pressure and CO compared with LVPE but did not increase vascular resistance. Functional capillary density was significantly higher for HVPE [87% (SD 7) of baseline] than for LVPE [42% (SD 11) of baseline]. Increases in mean arterial blood pressure, CO, and shear stressmediated factors could be responsible for maintaining organ and microvascular perfusion after exchange with HVPE compared with LVPE. Microhemodynamic data corresponded to microsphere-measured perfusion data in vital organs. microcirculation; extreme hemodilution; plasma expander; organ flow distribution; intravascular oxygen; functional capillary density