[CAR-T therapy for autoimmune diseases]. / Thérapie cellulaire CAR-T dans le traitement des maladies auto-immunes.

Cellular therapy using genetically modified T lymphocytes expressing synthetic receptors, known as CAR (Chimeric Antigen Receptor), has revolutionized the treatment of certain hematologic malignancies. This success has led to exploring the same approach in the treatment of severe autoimmune diseases refractory to conventional therapies. Initial results in systemic lupus erythematosus have shown complete remissions that appear to persist over time. Consequently, there is a growing number of ongoing clinical trials. In this review, we discuss the rationale behind the use of CAR-T therapies, the targeted autoimmune diseases, and the associated risks.

La thérapie cellulaire à base de lymphocytes T génétiquement modifiés exprimant des récepteurs synthétiques ou CAR (récepteur antigénique chimérique) a révolutionné le traitement de certaines maladies hémato-oncologiques. Ce succès a conduit à l'exploration de la même approche dans le traitement de maladies auto-immunes sévères et réfractaires aux thérapies conventionnelles. Les premiers résultats obtenus dans le lupus érythémateux systémique ont montré des rémissions complètes semblant persister dans le temps. Nous assistons donc actuellement à une prolifération importante d'essais cliniques. Dans cet article, nous abordons le rationnel derrière l'utilisation des thérapies CAR-T, les maladies auto-immunes ciblées, mais aussi les risques associés.

Deregulated cellular circuits driving immunoglobulins and complement consumption associate with the severity of COVID-19 patients.

SARS-CoV-2 infection causes an abrupt response by the host immune system, which is largely responsible for the outcome of COVID-19. We investigated whether the specific immune responses in the peripheral blood of 276 patients were associated with the severity and progression of COVID-19. At admission, dramatic lymphopenia of T, B, and NK cells is associated with severity. Conversely, the proportion of B cells, plasmablasts, circulating follicular helper T cells (cTfh) and CD56- CD16+ NK-cells increased. Regarding humoral immunity, levels of IgM, IgA, and IgG were unaffected, but when degrees of severity were considered, IgG was lower in severe patients. Compared to healthy donors, complement C3 and C4 protein levels were higher in mild and moderate, but not in severe patients, while the activation peptide of C5 (C5a) increased from the admission in every patient, regardless of their severity. Moreover, total IgG, the IgG1 and IgG3 isotypes, and C4 decreased from day 0 to day 10 in patients who were hospitalized for more than two weeks, but not in patients who were discharged earlier. Our study provides important clues to understand the immune response observed in COVID-19 patients, associating severity with an imbalanced humoral response, and identifying new targets for therapeutic intervention.

Effectiveness of a polyphenolic extract (Lippia citriodora and Hibiscus sabdariffa) on appetite regulation in overweight and obese grade I population: an 8-week randomized, double-blind, cross-over, placebo-controlled trial.

INTRODUCTION: Polyphenols have shown capacity to improve appetite sensation, leading to enhanced control of body weight. However, despite being related with hunger-related hormones, metabolic and mechanism are not well known. METHODS: The effectiveness of a nutraceutical composed of extract to Lippia citriodora and Hibiscus sabdarrifa (Lc-Hs) for controlling satiety and hunger was analyzed in a cross-over, placebo-controlled (Pla) clinical intervention. The study was divided in two 60-day periods separated by 30-day length wash-out period. At the end of each period, overweight and obese subjects (n = 33; age = 33.76 ± 12.23; BMI = 28.20 kg/m2 ± 2.47; fat mass 30.65 ± 8.39%; both sexes were proposed to eat an ad-libitum meal. Meanwhile, appetite sensation was determined by visual analog scales at different times. Moreover, blood extraction was performed to determine biochemical parameters (lipid and glucidic profile and safety parameters) and to evaluate hunger-related hormones (insulin, leptin, ghrelin, adiponectin, GLP-1 and peptide YY). RESULTS: A decrease in appetite sensation was observed in Lc-Hs treatment, showing higher satiety quotient (Pla = 3.36 ± 2.33%mm/kcal; Lc-Hs = 5.53 ± 2.91%mm/kcal; p < 0.0001). Area under the curve was higher in Pla compared to Lc-Hs during the test, from baseline to minute 240 (240 (Pla 9136.65 ± 2261.46% x min-1; Lc-Hs 8279.73 ± 2745.71% x min-1; p < 0.014). Energy consumption was lower for subjects treated with Lc-Hs (774.44 ± 247.77 kcal) compared to those treated with Pla (849.52 ± 246.54 kcal) (p < 0.004). Leptin values varied from baseline (Pla 12.36 ± 1.98 ng/mL; Lc-Hs 13.13 ± 1.99 ng/mL) to the end of the study (Pla 12.60 ± 2.02 ng/mL; Lc-Hs 12.06 ± 2.05 ng/mL; p < 0.047). GLP-1 values varied (p < 0.001) in Lc-Hs treatment from baseline (4.34 ± 0.49 ng/mL) to the end of the study (3.23 ± 0.52 ng/mL). CONCLUSION: The supplementation with the Lc-Hs extract decreases appetite sensation in overweight and obese population, reducing calorie intake after an ad-libitum meal. Due to variation on hunger-related hormones and the relationship between satiety feeling, it would be interesting to develop future research focused on the variation of the hormones themselves.

IL-6 serum levels predict severity and response to tocilizumab in COVID-19: An observational study.

BACKGROUND: Patients with coronavirus disaese 2019 (COVID-19) can develop a cytokine release syndrome that eventually leads to acute respiratory distress syndrome requiring invasive mechanical ventilation (IMV). Because IL-6 is a relevant cytokine in acute respiratory distress syndrome, the blockade of its receptor with tocilizumab (TCZ) could reduce mortality and/or morbidity in severe COVID-19. OBJECTIVE: We sought to determine whether baseline IL-6 serum levels can predict the need for IMV and the response to TCZ. METHODS: A retrospective observational study was performed in hospitalized patients diagnosed with COVID-19. Clinical information and laboratory findings, including IL-6 levels, were collected approximately 3 and 9 days after admission to be matched with preadministration and postadministration of TCZ. Multivariable logistic and linear regressions and survival analysis were performed depending on outcomes: need for IMV, evolution of arterial oxygen tension/fraction of inspired oxygen ratio, or mortality. RESULTS: One hundred forty-six patients were studied, predominantly males (66%); median age was 63 years. Forty-four patients (30%) required IMV, and 58 patients (40%) received treatment with TCZ. IL-6 levels greater than 30 pg/mL was the best predictor for IMV (odds ratio, 7.1; P < .001). Early administration of TCZ was associated with improvement in oxygenation (arterial oxygen tension/fraction of inspired oxygen ratio) in patients with high IL-6 (P = .048). Patients with high IL-6 not treated with TCZ showed high mortality (hazard ratio, 4.6; P = .003), as well as those with low IL-6 treated with TCZ (hazard ratio, 3.6; P = .016). No relevant serious adverse events were observed in TCZ-treated patients. CONCLUSIONS: Baseline IL-6 greater than 30 pg/mL predicts IMV requirement in patients with COVID-19 and contributes to establish an adequate indication for TCZ administration.

Synthesis of (±)-Setigerumine†I: Biosynthetic Origins of the Elusive Racemic Papaveraceae Isoxazolidine Alkaloids*.

The biosynthetic origins of the structurally related racemic isoxazolidine Papaveraceae alkaloids Setigerumine I, Dactylicapnosinine and Dactylicapnosine have remained elusive since their original isolation over two decades ago. Herein we report the first biosynthetic hypothesis for their formation and, inspired by it, the first synthesis of (±)-Setigerumine I with accompanying computational rationale. Based on the results, these isoxazolidine alkaloids arise from racemizing oxidative rearrangements of prominent isoquinoline alkaloids Noscapine and Hydrastine. The key steps featured in this synthesis are a room temperature Cope elimination and a domino oxidation/inverse-electron demand 1,3-dipolar cycloaddition of an axially chiral, yet configurationally unstable, intermediate. The work opens this previously inaccessible family of natural products for biological studies.

Smokeless Tobacco and the Rural Teen: How Culture and Masculinity Contribute to Adolescent Use.

Tobacco use is the leading preventable cause of disease, disability, and death in the United States. Smokeless tobacco (SLT) is primarily used by younger, rural males and often in the presence of other males. This formative study examined how hegemonic masculinity and male norms can lead to initiation and continued use of SLT by rural adolescent males and females. Survey data collected from high school sophomores in 4 rural high schools (n = 293) explores perceptions of masculinity and male norms' contribution to SLT uptake and use. About 22.5% of total sample reported lifetime use (34.4% male, 13.7% female), 10.9% reported past-month use (20.0% male, 4.2% female). Logistic regressions show a one-unit increase in adherence to traditional perceptions of masculinity more than doubled the odds of ever using SLT and significantly increased odds of 30-day use. Having male household family members who uses SLT significantly increased the odds of lifetime and 30-day SLT use for both genders, while having male family members who smoke cigarettes was not a significant correlate. Recognition of health warnings on SLT packaging was negatively associated with SLT use for both genders. Implications for inclusion of masculinity and male role models in SLT prevention intervention strategies are discussed.

Chlorpyrifos interacts with other agricultural stressors to alter stream communities in laboratory microcosms.

Chlorpyrifos is one of the most widely used agricultural insecticides in the world, but to date there is limited empirical information about its potential to interact with other common agricultural stressors. We conducted a 15-d, community-level, microcosm experiment evaluating individual and combined effects of chlorpyrifos, nutrient enrichment, and sedimentation on stream invertebrate communities (abundance, biomass, richness, size structure, composition) and ecosystem processes (primary productivity and leaf decomposition). We found that sedimentation was the most detrimental stressor, with significant negative impacts on most invertebrate community and ecosystem function variables. Even though chlorpyrifos did not cause significant invertebrate mortality in the microcosms, it still altered ecosystem function by lowering leaf decomposition rates, probably through sublethal inhibition of invertebrate shredders. Furthermore, we observed a significant reversal interaction between chlorpyrifos and sediment for small-sized invertebrates collected in gravel (abundance in sediment × insecticide microcosms was 2.4 times lower than predicted by additivity), as well as an antagonistic interaction with nutrients on invertebrate richness in the same microhabitat (richness in nutrient × insecticide microcosms was 1.6 times higher than predicted by additivity). Our results suggest that chlorpyrifos has the potential to alter freshwater ecosystem function and interact non-additively with other common agricultural stressors. These findings are in keeping with a growing body of research highlighting that multiple stressor interactions and ecosystem processes should be considered when evaluating the impacts of organic toxicants on freshwater ecosystems.

Effects of Game Location, Quality of Opposition, and Starting Quarter Score in the Outcome of Elite Water Polo Quarters.

The notational analysis is used to investigate teams' performance in water polo, especially focused on the determinants of success. Recently, a new topic has emerged "the situational variables," which includes the game conditions that may influence the performance at a behavioral level. The aim of this study was to identify the interactive effects of starting quarter score (SQS) (i.e., score difference at the beginning of each quarter and at the final score) and game location (GL) (i.e., home and away teams) in relation to quality of opposition (i.e., positions of difference between opposing teams at the end-of-season rankings) in elite men's water polo games. Data comprised 528 games (n = 2,112 quarters) from the first Spanish water polo division. A linear regression analysis was applied to show the impact of SQS and GL in relation to quality of opposition (unbalanced and balanced) for quarter (all quarters, and second, third, and fourth quarters). Results showed that SQS has an important effect for all quarters (0.16) and for the second (0.14) and third (0.14) quarters in balanced games (whereas the fourth quarter has an unpredictable outcome), and for each quarter (all quarters: 0.33; second quarter: 0.55; third quarter: 0.44; fourth quarter: 0.26) in unbalanced games. In addition, GL effects emerged for balanced (0.31) and unbalanced (0.45) games for all quarters and specifically for the second quarter of the unbalanced games. Therefore, this study showed that the elite water polo game dynamics, indirectly providing a reference for coaches (i.e., effective tactical approach) and physical trainers (i.e., high performance intensities), plans to improve their players' performance.

Functional inhibition of aquaporin-3 with a gold-based compound induces blockage of cell proliferation.

AQP3 has been correlated with higher transport of glycerol, increment of ATP content, and larger proliferation capacity. Recently, we described the gold(III) complex Auphen as a very selective and potent inhibitor of AQP3's glycerol permeability (Pgly ). Here we evaluated Auphen effect on the proliferation of various mammalian cell lines differing in AQP3 expression level: no expression (PC12), moderate (NIH/3T3) or high (A431) endogenous expression, cells stably expressing AQP3 (PC12-AQP3), and human HEK293T cells transiently transfected (HEK-AQP3) for AQP3 expression. Proliferation was evaluated in the absence or presence of Auphen (5 µM) by counting number of viable cells and analyzing 5-bromo-2'-deoxyuridine (BrdU) incorporation. Auphen reduced ≈50% the proliferation in A431 and PC12-AQP3, ≈15% in HEK-AQP3 and had no effect in PC12-wt and NIH/3T3. Strong arrest in the S-G2/M phases of the cell cycle, supported by analysis of cyclins (A, B1, D1, E) levels, was observed in AQP3-expressing cells treated with Auphen. Flow-cytometry of propidium iodide incorporation and measurements of mitochondrial dehydrogenases activity confirmed absence of cytotoxic effect of the drug. Functional studies evidenced ≈50% inhibition of A431 Pgly by Auphen, showing that the compound's antiproliferative effect correlates with its ability to inhibit AQP3 Pgly . Role of Cys-40 on AQP3 permeability blockage by Auphen was confirmed by analyzing the mutated protein (AQP3-Ser-40). Accordingly, cells transfected with mutated AQP3 gained resistance to the antiproliferative effect of Auphen. These results highlight an Auphen inhibitory effect on proliferation of cells expressing AQP3 and suggest a targeted therapeutic effect on carcinomas with large AQP3 expression.

An immunoassay that distinguishes real neuromyelitis optica signals from a labeling detected in patients receiving natalizumab.

BACKGROUND: Cell-based assays for neuromyelitis optica (NMO) diagnosis are the most sensitive and specific methods to detect anti-aquaporin 4 (AQP4) antibodies in serum, but some improvements in their quantitative and specificity capacities would be desirable. Thus the aim of the present work was to develop a sensitive quantitative method for detection of anti-AQP4 antibodies that allows clear diagnosis of NMO and distinction of false labeling produced by natalizumab treatment. METHODS: Sera from 167 individuals, patients diagnosed with NMO (16), multiple sclerosis (85), optic neuritis (24), idiopathic myelitis (21), or other neurological disorders (13) and healthy controls (8), were used as the primary antibody in an immunofluorescence assay on HEK cells transfected with the M23 isoform of human AQP4 fused with enhanced green fluorescent protein. Cells used were freshly transfected or stored frozen and then thawed just before adding the serum. RESULTS: Microscopic observation and fluorescence quantification produced similar results in fresh and frozen samples. Serum samples from patients diagnosed with NMO were 100% positive for anti-AQP4 antibodies, while all the other sera were negative. Using serum from patients treated with natalizumab, a small and unspecific fluorescent signal was produced from all HEK cells, regardless of AQP4 expression. CONCLUSIONS: Our cell-based double-label fluorescence immunoassay protocol significantly increases the signal specificity and reduces false diagnosis of NMO patients, especially in those receiving natalizumab treatment. Frozen pretreated cells allow faster detection of anti-AQP4 antibodies.

[Agricultural land use impacts on aquatic macroinvertebrates in small streams from La Vieja river (Valle del Cauca, Colombia]. / Impacto del uso del suelo agropecuario sobre macroinvertebrados acuáticos en pequeñas quebradas de la cuenca del río La Vieja (Valle del Cauca, Colombia).

The expansion of the agricultural frontier in Colombia has exerted significant pressure on its aquatic ecosystems during the last few decades. In order to determine the impacts of different agricultural land uses on the biotic and abiotic characteristics of first and second order streams of La Vieja river watershed, we evaluated 21 streams located between 1,060 and 1,534 m asl in the municipalities of Alcalá, Ulloa, and Cartago (Valle del Cauca, Colombia). Seven streams were protected by native vegetation buffers, eight had influence of coffee and plantain crops, and six were influenced by cattle ranching. Habitat conditions, channel dimensions, water quality, and aquatic macroinvertebrates were studied in each stream. Streams draining cattle ranching areas had significantly higher dissolved solids, higher phosphorus, higher alkalinity, higher conductivity, and lower dissolved oxygen than those covered by cropland and forests. Coarse substrates and diversity of flow regimes were significantly higher in cropland and protected streams when compared to streams affected by cattle ranching, whereas the percent of silt and slow currents was significantly higher in the latter. A total of 26,777 macroinvertebrates belonging to 17 orders, 72 families and 95 genera were collected. The most abundant groups were Diptera 62.8%, (Chironomidae 49.6%, Ceratopogonidae 6.7%), Mollusca 18.8% (Hydrobiidae 7.2%, Sphaeriidae 9.6%) and Trichoptera 5.7% (Hydropsychidae 3.7%). The Ephemeroptera, Trichoptera, and Plecoptera orders, known for their low tolerance to habitat perturbation, had high abundance in cropland and forested streams, whereas Diptera and Mollusca were more abundant in those impacted by cattle ranching. Results indicate that streams draining forests and croplands have better physical and biological conditions than those draining pastures, and highlight the need to implement protective measures to restore the latter.

Intradermal skin test with mRNA vaccines as a surrogate marker of T cell immunity in immunocompromised patients.

OBJECTIVES: Intradermal skin test (IDT) with mRNA vaccines may represent a simple, reliable, and affordable tool to measure T cell response in immunocompromised patients who failed to mount serological responses following vaccination with mRNA covid-19 vaccines. METHODS: We compared anti-SARS-CoV-2 antibodies and cellular responses in vaccinated immunocompromised patients (n = 58), healthy seronegative naive controls (NC, n = 8), and healthy seropositive vaccinated controls (VC, n = 32) by Luminex, spike-induced IFN-γ Elispot and an IDT. A skin biopsy 24 h after IDT and single-cell RNAseq was performed in three vaccinated volunteers. RESULTS: Twenty-five percent of seronegative NC had a positive Elispot (2/8) and IDT (1/4), compared to 95% (20/21) and 93% (28/30) in seropositive VC, respectively. Single-cell RNAseq data in the skin of VC showed a predominant mixed population of effector helper and cytotoxic T cells. The TCR repertoire revealed 18/1064 clonotypes with known specificities against SARS-CoV-2, among which six were spike-specific. Seronegative immunocompromised patients with positive Elispot and IDT were in 83% (5/6) treated with B cell-depleting reagents, while those with negative IDT were all transplant recipients. CONCLUSIONS: Our results indicate that delayed local reaction to IDT reflects vaccine-induced T-cell immunity opening new perspectives to monitor seronegative patients and elderly populations with waning immunity.

A cluster-randomised clinical trial comparing two cardiovascular health education strategies in a child population: the Savinghearts project.

BACKGROUND: This paper describes a methodology for comparing the effects of an eduentertainment strategy involving a music concert, and a participatory class experience involving the description and making of a healthy breakfast, as educational vehicles for delivering obesity-preventing/cardiovascular health messages to children aged 7-8 years. METHODS/DESIGN: This study will involve a cluster-randomised trial with blinded assessment. The study subjects will be children aged 7-8 years of both sexes attending public primary schools in the Madrid Region. The participating schools (n=30) will be randomly assigned to one of two groups: 1) Group MC, in which the children will attend a music concert that delivers obesity-preventing/cardiovascular health messages, or 2) Group HB, in which the children will attend a participatory class providing the same information but involving the description and making of a healthy breakfast. The main outcome measured will be the increase in the number of correct answers scored on a knowledge questionnaire and in an attitudes test administered before and after the above interventions. The secondary outcome recorded will be the reduction in BMI percentile among children deemed overweight/obese prior to the interventions. The required sample size (number of children) was calculated for a comparison of proportions with an α of 0.05 and a ß of 0.20, assuming that the Group MC subjects would show values for the measured variables at least 10% higher than those recorded for the subjects of Group HB. Corrections were made for the design effect and assuming a loss to follow-up of 10%. The maximum sample size required will be 2107 children. Data will be analysed using summary measurements for each cluster, both for making estimates and for hypothesis testing. All analyses will be made on an intention-to-treat basis. DISCUSSION: The intervention providing the best results could be recommended as part of health education for young schoolchildren. TRIAL REGISTRATION: Clinicaltrials.gov: NCT01418872.

Procalcitonin concentration in the emergency department predicts 30-day mortality in COVID-19 better than the lymphocyte count, the neutrophil-tolymphocyte ratio, or the C-reactive protein level. / Procalcitonina es superior a recuento linfocitario, índice neutrófilo/linfocito y proteína C reactiva para la predicción de mortalidad a 30 días de pacientes con COVID-19 en el servicio de urgencias.

OBJECTIVES: Although many demographic and clinical predictors of mortality have been studied in relation to COVID-19, little has been reported about the prognostic utility of inflammatory biomarkers. MATERIAL AND METHODS: Retrospective cohort study. All patients with laboratory-confirmed COVID-19 treated in a hospital emergency department were included consecutively if baseline measurements of the following biomarkers were on record: lymphocyte counts, neutrophil-to-lymphocyte ratio NRL, and C-reactive protein (CRP) and procalcitonin (PCT) levels. We analyzed associations between the biomarkers and all-cause 30-day mortality using Cox regression models and dose-response curves. RESULTS: We included 896 patients, 151 (17%) of whom died within 30 days. The median (interquartile range) age was 63 (51-78) years, and 494 (55%) were men. NLR, CRP and PCT levels at ED presentation were higher, while lymphocyte counts were lower, in patients who died compared to those who survived (P .001). The areas under the receiver operating characteristic curves revealed the PCT concentration (0.79; 95% CI, 0.75-0.83) to be a better predictor of 30-day mortality than the lymphocyte count (0.70; 95% CI, 0.65-0.74; P .001), the NLR (0.74; 95% CI, 0.69-0.78; P = .03), or the CRP level (0.72; 95% CI, 0.68-0.76; P .001). The proposed PCT concentration decision points for use in emergency department case management were 0.06 ng/L (negative) and 0.72 ng/L (positive). These cutoffs helped classify risk in 357 patients (40%). Multivariable analysis demonstrated that the PCT concentration had the strongest association with mortality. CONCLUSION: PCT concentration in the emergency department predicts all-cause 30-day mortality in patients with COVID-19 better than other inflammatory biomarkers.

OBJETIVO: Existen múltiples variables demográficas y clínicas predictivas de mortalidad en pacientes con COVID-19. Sin embargo, hay menos información sobre el valor pronóstico de los biomarcadores inflamatorios. METODO: Estudio de cohorte retrospectivo. Se incluyeron de forma consecutiva todos los pacientes con COVID-19, confirmado por laboratorio, atendidos en un servicio de urgencias hospitalario (SUH) y con valor basal de los siguientes biomarcadores: recuento linfocitario, índice neutrófilo/linfocito (INL), proteína C reactiva (PCR) y procalcitonina (PCT). La relación entre los biomarcadores y la mortalidad total a 30 días se analizó mediante una regresión de Cox y gráficos de dosis-respuesta. RESULTADOS: Se incluyeron 896 pacientes, 151 (17%) fallecieron en los primeros 30 días. La mediana de edad fue de 63 años (51-78) y 494 (55%) eran hombres. El valor de INL, PCR y PCT fue mayor, mientras que el recuento linfocitario fue menor, en los pacientes que fallecieron respecto a los que sobrevivieron (p 0,001). La PCT fue superior al recuento linfocitario, INL y PCR en la predicción de mortalidad a 30 días (ABC 0,79 [IC 95%: 0,75-0,83] vs 0,70 [IC 95%: 0,65-0,74], p 0,001; 0,74 [IC 95%: 0,69-0,78], p = 0,03; y 0,72 [IC 95%: 0,68-0,76], p 0,001). Los puntos de decisión de PCT propuestos, 0,06 ng/l para exclusión y 0,72 ng/l para inclusión de muerte a 30 días, podrían facilitar la toma de decisiones en urgencias. Hubo 357 pacientes (40%) con valores de PCT en estas categorías. El análisis multivariable mostró una mayor asociación con la mortalidad para PCT que en los otros biomarcadores estudiados. CONCLUSIONES: PCT es el biomarcador con mejor capacidad para predecir mortalidad a 30 días por cualquier causa en pacientes con COVID-19 valorados en un SUH.

Global distribution of a key trophic guild contrasts with common latitudinal diversity patterns.

Most hypotheses explaining the general gradient of higher diversity toward the equator are implicit or explicit about greater species packing in the tropics. However, global patterns of diversity within guilds, including trophic guilds (i.e., groups of organisms that use similar food resources), are poorly known. We explored global diversity patterns of a key trophic guild in stream ecosystems, the detritivore shredders. This was motivated by the fundamental ecological role of shredders as decomposers of leaf litter and by some records pointing to low shredder diversity and abundance in the tropics, which contrasts with diversity patterns of most major taxa for which broad-scale latitudinal patterns haven been examined. Given this evidence, we hypothesized that shredders are more abundant and diverse in temperate than in tropical streams, and that this pattern is related to the higher temperatures and lower availability of high-quality leaf litter in the tropics. Our comprehensive global survey (129 stream sites from 14 regions on six continents) corroborated the expected latitudinal pattern and showed that shredder distribution (abundance, diversity and assemblage composition) was explained by a combination of factors, including water temperature (some taxa were restricted to cool waters) and biogeography (some taxa were more diverse in particular biogeographic realms). In contrast to our hypothesis, shredder diversity was unrelated to leaf toughness, but it was inversely related to litter diversity. Our findings markedly contrast with global trends of diversity for most taxa, and with the general rule of higher consumer diversity at higher levels of resource diversity. Moreover, they highlight the emerging role of temperature in understanding global patterns of diversity, which is of great relevance in the face of projected global warming.

Immune synapse instructs epigenomic and transcriptomic functional reprogramming in dendritic cells.

Understanding the fate of dendritic cells (DCs) after productive immune synapses (postsynaptic DCs) with T cells during antigen presentation has been largely neglected in favor of deciphering the nuances of T cell activation and memory generation. Here, we describe that postsynaptic DCs switch their transcriptomic signature, correlating with epigenomic changes including DNA accessibility and histone methylation. We focus on the chemokine receptor Ccr7 as a proof-of-concept gene that is increased in postsynaptic DCs. Consistent with our epigenomic observations, postsynaptic DCs migrate more efficiently toward CCL19 in vitro and display enhanced homing to draining lymph nodes in vivo. This work describes a previously unknown DC population whose transcriptomics, epigenomics, and migratory capacity change in response to their cognate contact with T cells.

Latitude dictates plant diversity effects on instream decomposition.

Running waters contribute substantially to global carbon fluxes through decomposition of terrestrial plant litter by aquatic microorganisms and detritivores. Diversity of this litter may influence instream decomposition globally in ways that are not yet understood. We investigated latitudinal differences in decomposition of litter mixtures of low and high functional diversity in 40 streams on 6 continents and spanning 113° of latitude. Despite important variability in our dataset, we found latitudinal differences in the effect of litter functional diversity on decomposition, which we explained as evolutionary adaptations of litter-consuming detritivores to resource availability. Specifically, a balanced diet effect appears to operate at lower latitudes versus a resource concentration effect at higher latitudes. The latitudinal pattern indicates that loss of plant functional diversity will have different consequences on carbon fluxes across the globe, with greater repercussions likely at low latitudes.

Impacts of detritivore diversity loss on instream decomposition are greatest in the tropics.

The relationship between detritivore diversity and decomposition can provide information on how biogeochemical cycles are affected by ongoing rates of extinction, but such evidence has come mostly from local studies and microcosm experiments. We conducted a globally distributed experiment (38 streams across 23 countries in 6 continents) using standardised methods to test the hypothesis that detritivore diversity enhances litter decomposition in streams, to establish the role of other characteristics of detritivore assemblages (abundance, biomass and body size), and to determine how patterns vary across realms, biomes and climates. We observed a positive relationship between diversity and decomposition, strongest in tropical areas, and a key role of abundance and biomass at higher latitudes. Our results suggest that litter decomposition might be altered by detritivore extinctions, particularly in tropical areas, where detritivore diversity is already relatively low and some environmental stressors particularly prevalent.

COVID-19 severity associates with pulmonary redistribution of CD1c+ DCs and inflammatory transitional and nonclassical monocytes.

SARS-CoV-2 is responsible for the development of coronavirus disease 2019 (COVID-19) in infected individuals, who can either exhibit mild symptoms or progress toward a life-threatening acute respiratory distress syndrome (ARDS). Exacerbated inflammation and dysregulated immune responses involving T and myeloid cells occur in COVID-19 patients with severe clinical progression. However, the differential contribution of specific subsets of dendritic cells and monocytes to ARDS is still poorly understood. In addition, the role of CD8+ T cells present in the lung of COVID-19 patients and relevant for viral control has not been characterized. Here, we have studied the frequencies and activation profiles of dendritic cells and monocytes present in the blood and lung of COVID-19 patients with different clinical severity in comparison with healthy individuals. Furthermore, these subpopulations and their association with antiviral effector CD8+ T cell subsets were also characterized in lung infiltrates from critical COVID-19 patients. Our results indicate that inflammatory transitional and nonclassical monocytes and CD1c+ conventional dendritic cells preferentially migrate from blood to lungs in patients with severe COVID-19. Thus, this study increases the knowledge of specific myeloid subsets involved in the pathogenesis of COVID-19 disease and could be useful for the design of therapeutic strategies for fighting SARS-CoV-2 infection.