Appendicitis is one of the most common abdominal emergencies globally, yet little is understood about the inflammatory mechanisms or potential drivers of disease. Neutrophil inflammation and increased cytokine expression such as IL-6 and IL-8 are hallmarks of appendicitis inflammation. However, early histological studies identified increased T and B cell infiltration during appendicitis, providing support for adaptive immune activation as well, although this has never been investigated in depth. We hypothesized that antigen-dependent activation of the adaptive immune response contributes to appendicitis pathology, in addition to the known innate-mediated processes. Via a series of transcriptomic approaches and lymphocyte repertoire analysis in human appendiceal tissue, we identified evidence of antigen-dependent B cell activation. Increased somatic hypermutation in the germinal center and plasma cell compartment was comprised of presumed high-affinity IgG and IgA B cells. We propose that the appendiceal microbiome acts as a source of antigen, as significant microbial dysbiosis was observed during appendicitis. This dysbiosis was characterized by outgrowth of pathobionts such as Parvimonas and oral biofilm-formers such as Fretibacterium and Fusobacterium , in line with previous reports. We also identified potential loss of epithelial barrier integrity via spatial transcriptomic analysis of the appendiceal epithelium, supporting the possibility of microbial invasion into the tissue during appendicitis. This study provides insight into the inflammatory mechanisms of a common disease and helps to define the immune and microbial compartment of an often-ignored organ, the appendix.### Competing Interest StatementThe authors have declared no competing interest.

The movement of carbon in subduction zones plays a crucial role in regulating the global carbon cycle, controlling Earth's climate, and maintaining its habitability. Recent work suggests that only a fraction of the carbon released from subducting slabs at sub-arc depths is ultimately released from volcanic arcs, necessitating the existence of hidden carbon reservoirs within the slab-to-arc pathways. However, the precise location of these reservoirs remains enigmatic. Slab fluid serves as the primary medium for carbon transport in subduction zones; thus, a comprehensive understanding of fluid-rock interaction during slab fluid migration is essential for reconciling the carbon flux imbalance between the slab and the arc. In this study, we explore rock carbonation along a fluid conduit in the Southwestern Tianshan HP metamorphic belt in northwest China. Field evidence and petrologic observation reveal significant carbonation of a siliciclastic metasediment at its contact with a high-pressure garnet-bearing calcite (formerly aragonite) vein. We find that rock carbonation (by progressive Febearing magnesite, dolomite, then aragonite precipitation) occurred when slab-derived carbonic fluids migrated through the metasedimentary sequence at approximately 80 km depth. Furthermore, modeling demonstrates that the metasedimentary layer atop the slab has the capacity to sequester 20%-50% of the fluid carbon from the ascending slab devolatilization flux. We propose that the metasedimentary veneer at the plate interface functions as a "carbon filter", hindering the transfer of carbon from the slab to the arc and helping to reconcile the carbon flux imbalance between the amount released by the slab and that emitted by the arc. This study also provides insights into decarbonation efficiency and mechanisms, carbon-transfer pathways, and temporal aspects of the subduction zone carbon cycle.

Abstract Solid organ transplantation is the preferred treatment for end-stage organ failure. Achieving stable donor-specific transplantation tolerance holds the potential to vastly improve the quality of life for transplant recipients by eliminating lifelong exposure to drug toxicity, a higher risk of malignancy and infection, and the development of chronic rejection associated with conventional immunosuppression. In mice, treatment with anti-CD154 (aCD154) prolongs graft survival, but the addition of donor splenocyte transfusion (DST) to aCD154 produces a robust state of graft-specific tolerance to fully MHC-mismatched cardiac allografts. In this study, we investigated parameters that dictate the efficacy of DST treatment. Our results support an antigen dispersal hypothesis whereby DST enables alloantigen to circulate to all secondary lymphoid organs where it can prime alloreactive T cells under cover of aCD154, and induce widespread tolerance in a larger repertoire of T cells than enabled by an allograft alone.

BACKGROUND:MUPPITS-2 was a randomized, placebo-controlled clinical trial that demonstrated mepolizumab (anti-IL-5) reduced exacerbations and blood and airway eosinophils in urban children with severe eosinophilic asthma. Despite this reduction in eosinophilia, exacerbation risk persisted in certain patients treated with mepolizumab. This raises the possibility that subpopulations of airway eosinophils exist that contribute to breakthrough exacerbations. OBJECTIVE:We aimed to determine the effect of mepolizumab on airway eosinophils in childhood asthma. METHODS:Sputum samples were obtained from 53 MUPPITS-2 participants. Airway eosinophils were characterized using mass cytometry and grouped into subpopulations using unsupervised clustering analyses of 38 surface and intracellular markers. Differences in frequency and immunophenotype of sputum eosinophil subpopulations were assessed based on treatment arm and frequency of exacerbations. RESULTS:Median sputum eosinophils were significantly lower among participants treated with mepolizumab compared with placebo (58% lower, 0.35% difference [95% CI 0.01, 0.74], P = .04). Clustering analysis identified 3 subpopulations of sputum eosinophils with varied expression of CD62L. CD62Lint and CD62Lhi eosinophils exhibited significantly elevated activation marker and eosinophil peroxidase expression, respectively. In mepolizumab-treated participants, CD62Lint and CD62Lhi eosinophils were more abundant in participants who experienced exacerbations than in those who did not (100% higher for CD62Lint, 0.04% difference [95% CI 0.0, 0.13], P = .04; 93% higher for CD62Lhi, 0.21% difference [95% CI 0.0, 0.77], P = .04). CONCLUSIONS:Children with eosinophilic asthma treated with mepolizumab had significantly lower sputum eosinophils. However, CD62Lint and CD62Lhi eosinophils were significantly elevated in children on mepolizumab who had exacerbations, suggesting that eosinophil subpopulations exist that contribute to exacerbations despite anti-IL-5 treatment.

Rock metamorphism releases substantial CO 2 over geologic timescales (>1 My), potentially driving long-term planetary climate trends. The nature of carbonate sediments and crustal thermal regimes exert a strong control on the efficiency of metamorphic CO 2 release; thus, it is likely that metamorphic CO 2 degassing has not been constant throughout time. The Proterozoic Earth was characterized by a high proportion of dolomite-bearing mixed carbonate-silicate rocks and hotter crustal regimes, both of which would be expected to enhance metamorphic decarbonation. Thermodynamic phase equilibria modeling predicts that the metamorphic carbon flux was likely ~1.7 times greater in the Mesoproterozoic Era compared to the modern Earth. Analytical and numerical approaches (the carbon cycle model PreCOSCIOUS) are used to estimate the impact this would have on Proterozoic carbon cycling and global atmospheric compositions. This enhanced metamorphic CO 2 release alone could increase pCO 2 by a factor of four or more when compared to modern degassing rates, contributing to a stronger greenhouse effect and warmer global temperatures during the expansion of life on the early Earth.

Contact metamorphism of carbonate rocks is a complex process, often characterized by chemical and isotopic disequilibrium and dominated by open-system fluid flow. As such, a handful of recent studies have applied the relatively new tool of carbonate clumped isotope thermometry across km-scale contact aureoles to track conditions from low to high grade. Results have been particularly intriguing among low grade carbonates at the extreme outer edge of the metamorphic aureole. We therefore present results of carbonate clumped isotope analysis combined with detailed petrography and sample characterization to explore the onset of metamorphism in the Alta stock contact aureole, Utah. In addition to focusing on a few densely sampled field profiles near the lowest-grade talc isograd, we perform mm-scale microsampling to assess the relationship between heterogeneous reaction features and carbonate clumped isotopes. We find that elevated metamorphic temperatures (~ 275–300 °C) are recorded by matrix dolomite only in samples which underwent corresponding recrystallization and grain size reduction, and that the boundary between recrystallized and un-recrystallized samples is consistently expressed in the field across a ~ 33 m wide zone. At the microscale, clumped isotopes reveal very local equilibration and recrystallization, recording differing prograde and retrograde reaction temperatures within a few millimeters. Carbonate clumped isotope thermometry and traditional stable isotopes are further used to explore heterogeneous fluid compositions and channelized flow in the outer aureole.

The fate of subducted CO2 remains the subject of widespread disagreement, with different models predicting either wholesale (up to 99%) decarbonation of the subducting slab or extremely limited carbon loss and, consequently, massive deep subduction of CO2. The fluid history of subducted rocks lies at the heart of this debate: rocks that experience significant infiltration by a water-bearing fluid may release orders of magnitude more CO2 than rocks that are metamorphosed in a closed chemical system. Numerical models make a wide range of predictions regarding water mobility, and further progress has been limited by a lack of direct observations. Here we present a comprehensive field-based study of decarbonation efficiency in a subducting slab (Cyclades, Greece), and show that ~40% to ~65% of the CO2 in subducting crust is released via metamorphic decarbonation reactions at forearc depths. This result precludes extensive deep subduction of most CO2 and suggests that the mantle has become more depleted in carbon over geologic time.

Asthma is a chronic inflammatory disease of the airways that afflicts over 30 million individuals in the United States and over 300 million individuals worldwide. The inflammatory response in the airways is often characterized by the analysis of sputum, which contains multiple types of cells including neutrophils, macrophages, lymphocytes, and rare bronchial epithelial cells. Subtyping patients using microscopy of the sputum has identified both neutrophilic and eosinophilic infiltrates in airway inflammation. However, with the extensive heterogeneity among these cell types, a higher resolution understanding of the inflammatory cell types present in the sputum is needed to dissect the heterogeneity of disease. Improved recognition of the distinct phenotypes and sources of inflammation in asthmatic granulocytes may identify relevant pathways for clinical management or investigation of novel therapeutic mediators. Here, we employed mass cytometry or cytometry by time-of-flight to quantify frequency and define functional status of sputum derived airway cells in asthmatic patients and healthy controls. This in-depth single cell analysis method identified multiple distinct subtypes of airway immune cells, especially in neutrophils. Significance was discovered by statistical analysis as well as a data-driven unbiased clustering approach. Our multidimensional assessment method identifies differences in cellular function and supports identification of cellular status that may contribute to diverse clinical responses. This technical advance is relevant for studies of pathogenesis and may provide meaningful insights to advance our knowledge of asthmatic inflammation.

The existence of stabilizing feedbacks within Earth's climate system is generally thought to be necessary for the persistence of liquid water and life. Over the course of Earth's history, Earth's atmospheric composition appears to have adjusted to the gradual increase in solar luminosity, resulting in persistently habitable surface temperatures. With limited exceptions, the Earth system has been observed to recover rapidly from pulsed climatic perturbations. Carbon dioxide (CO2) regulation via negative feedbacks within the coupled global carbon-silica cycles are classically viewed as the main processes giving rise to climate stability on Earth. Here we review the long-term global carbon cycle budget, and how the processes modulating Earth's climate system have evolved over time. Specifically, we focus on the relative roles that shifts in carbon sources and sinks have played in driving long-term changes in atmospheric pCO(2). We make the case that marine processes are an important component of the canonical silicate weathering feedback, and have played a much more important role in pCO(2) regulation than traditionally imagined. Notably, geochemical evidence indicate that the weathering of marine sediments and off-axis basalt alteration act as major carbon sinks. However, this sink was potentially dampened during Earth's early history when oceans had higher levels of dissolved silicon (Si), iron (Fe), and magnesium (Mg), and instead likely fostered more extensive carbon recycling within the ocean-atmosphere system via reverse weathering-that in turn acted to elevate ocean-atmosphere CO2 levels.

Rationale: MicroRNAs are potent regulators of biologic systems that are critical to tissue homeostasis. Individual microRNAs have been identified in airway samples. However, a systems analysis of the microRNA-mRNA networks present in the sputum that contribute to airway inflammation in asthma has not been published. Objectives: Identify microRNA and mRNA networks in the sputum of patients with asthma. Methods: We conducted a genome-wide analysis of microRNA and mRNA in the sputum from patients with asthma and correlated expression with clinical phenotypes. Weighted gene correlation network analysis was implemented to identify microRNA networks (modules) that significantly correlate with clinical features of asthma and mRNA expression networks. MicroRNA expression in peripheral blood neutrophils and lymphocytes and in situ hybridization of the sputum were used to identify the cellular sources of microRNAs. MicroRNA expression obtained before and after ozone exposure was also used to identify changes associated with neutrophil counts in the airway. Measurements and Main Results: Six microRNA modules were associated with clinical features of asthma. A single module (nely) was associated with a history of hospitalizations, lung function impairment, and numbers of neutrophils and lymphocytes in the sputum. Of the 12 microRNAs in the nely module, hsa-miR-223-3p was the highest expressed microRNA in neutrophils and was associated with increased neutrophil counts in the sputum in response to ozone exposure. Multiple microRNAs in the nely module correlated with two mRNA modules enriched for TLR (Toll-like receptor) and T-helper cell type 17 (Th17) signaling and endoplasmic reticulum stress. hsa-miR-223-3p was a key regulator of the TLR and Th17 pathways in the sputum of subjects with asthma. Conclusions: This study of sputummicro RNA and mRNA expression from patients with asthma demonstrates the existence of microRNA networks and genes that are associated with features of asthma severity. Among these, hsa-miR-223-3p, a neutrophil-derived microRNA, regulates TLR/Th17 signaling and endoplasmic reticulum stress.

The geologic carbon cycle plays a fundamental role in controlling Earth's climate and habitability. For billions of years, stabilizing feedbacks inherent in the cycle have maintained a surface environment that could sustain life. Carbonation/decarbonation reactions are the primary mechanisms for transferring carbon between the solid Earth and the ocean-atmosphere system. These processes can be broadly represented by the reaction: CaSiO3(wollastonite) + CO2 (gas) <-> CaCO3(calcite) + SiO2(quartz). This class of reactions is therefore critical to Earth's past and future habitability. Here, we summarize their significance as part of the Deep Carbon Obsevatory's "Earth in Five Reactions" project. In the forward direction, carbonation reactions like the one above describe silicate weathering and carbonate formation on Earth's surface. Recent work aims to resolve the balance between silicate weathering in terrestrial and marine settings both in the modern Earth system and through Earth's history. Rocks may also undergo carbonation reactions at high temperatures in the ultramafic mantle wedge of a subduction zone or during retrograde regional metamorphism. In the reverse direction, the reaction above represents various prograde metamorphic decarbonation processes that can occur in continental collisions, rift zones, subduction zones, and in aureoles around magmatic systems. We summarize the fluxes and uncertainties of major carbonation/decarbonation reactions and review the key feedback mechanisms that are likely to have stabilized atmospheric CO2 levels. Future work on planetary habitability and Earth's past and future climate will rely on an enhanced understanding of the long-term carbon cycle.

We undertake thermodynamic pseudosection modeling of metacarbonate rocks in the Wepawaug Schist, Connecticut, USA, and examine the implications for CO2 outgassing from collisional orogenic belts. Two broad types of pseudosections are calculated: (1) a fully closed-system model with no fluid infiltration and (2) a fluid-buffered model including an H2O-CO2 fluid of a fixed composition. This fluid-buffered model is used to approximate a system open to infiltration by a water-bearing fluid. In all cases the fully closed-system model fails to reproduce the observed major mineral zones, mineral compositions, reaction temperatures, and fluid compositions. The fluid-infiltrated models, on the other hand, successfully reproduce these observations when the Xco, of the fluid is in the range similar to 0.05 to similar to 0.15. Fluid-infiltrated models predict significant progressive CO2 loss, peaking at 50% decarbonation at amphibolite facies. The closed-system models dramatically underestimate the degree of decarbonation, predicting only 15% CO2 loss at peak conditions, and, remarkably, <1% CO2 loss below similar to 600 degrees C. We propagate the results of fluid-infiltrated pseudosections to determine an areal CO2 flux for the Wepawaug Schist. This yields 10(12) mol CO2 km-(2) Myr(-1), consistent with multiple independent estimates of the metamorphic CO2 flux, and comparable in magnitude to fluxes from mid-ocean ridges and volcanic arcs. Extrapolating to the area of the Acadian orogenic belt, we suggest that metamorphic CO2 degassing is a plausible driver of global warming, sea level rise, and, perhaps, extinction in the mid-to late-Devonian. (C) 2018 Elsevier B.V. All rights reserved.

We report the results of Sm–Nd garnet geochronology on a mafic granulite from the metamorphic sole of the Ballantrae Ophiolite, Scotland. The resultant age of 477.6 ± 1.9 Ma (2σ) is interpreted to represent the obduction of the Ballantrae Ophiolite and the onset of the Grampian phase of the Caledonian Orogeny in Scotland. Thermodynamic modelling indicates peak conditions of c . 825°C and at least 10 kbar for the unit. In conjunction with a biostratigraphic constraint on metamorphic garnet deposition in sediments at 465 ± 2.5 Ma, this new age more precisely constrains the duration of Grampian metamorphism in Scotland to 12.6 ± 3.1 myr (2σ). In combination with this new age, previous geochronological work on sillimanite-zone garnet indicates a time-averaged initial heating rate of 106 ± 78°C myr −1 (2σ), a rapid rate that may be inconsistent with orogenic self-heating via crustal overthickening alone. The calculated heating rate for the associated garnet zone is also rapid and more precisely constrained at 47 ± 14°C myr −1 (2σ). These results together with the short overall duration of the event support the idea that the Grampian phase of the Caledonian Orogeny in Scotland included both rapid heating and correspondingly fast exhumation.