Characterization of crAss-like phage isolates highlights Crassvirales genetic heterogeneity and worldwide distribution.

Crassvirales (crAss-like phages) are an abundant group of human gut-specific bacteriophages discovered in silico. The use of crAss-like phages as human fecal indicators is proposed but the isolation of only seven cultured strains of crAss-like phages to date has greatly hindered their study. Here, we report the isolation and genetic characterization of 25 new crAss-like phages (termed crAssBcn) infecting Bacteroides intestinalis, belonging to the order Crassvirales, genus Kehishuvirus and, based on their genomic variability, classified into six species. CrAssBcn phage genomes are similar to ΦCrAss001 but show genomic and aminoacidic differences when compared to other crAss-like phages of the same family. CrAssBcn phages are detected in fecal metagenomes around the world at a higher frequency than ΦCrAss001. This study increases the known crAss-like phage isolates and their abundance and heterogeneity open the question of what member of the Crassvirales group should be selected as human fecal marker.

Dominance of phage particles carrying antibiotic resistance genes in the viromes of retail food sources.

The growth of antibiotic resistance has stimulated interest in understanding the mechanisms by which antibiotic resistance genes (ARG) are mobilized. Among them, studies analyzing the presence of ARGs in the viral fraction of environmental, food and human samples, and reporting bacteriophages as vehicles of ARG transmission, have been the focus of increasing research. However, it has been argued that in these studies the abundance of phages carrying ARGs has been overestimated due to experimental contamination with non-packaged bacterial DNA or other elements such as outer membrane vesicles (OMVs). This study aims to shed light on the extent to which phages, OMVs or contaminating non-packaged DNA contribute as carriers of ARGs in the viromes. The viral fractions of three types of food (chicken, fish, and mussels) were selected as sources of ARG-carrying phage particles, whose ability to infect and propagate in an Escherichia coli host was confirmed after isolation. The ARG-containing fraction was further purified by CsCl density gradient centrifugation and, after removal of DNA outside the capsids, ARGs inside the particles were confirmed. The purified fraction was stained with SYBR Gold, which allowed the visualization of phage capsids attached to and infecting E. coli cells. Phages with Myoviridae and Siphoviridae morphology were observed by electron microscopy. The proteins in the purified fraction belonged predominantly to phages (71.8% in fish, 52.9% in mussels, 78.7% in chicken sample 1, and 64.1% in chicken sample 2), mainly corresponding to tail, capsid, and other structural proteins, whereas membrane proteins, expected to be abundant if OMVs were present, accounted for only 3.8-21.4% of the protein content. The predominance of phage particles in the viromes supports the reliability of the protocols used in this study and in recent findings on the abundance of ARG-carrying phage particles.

Antibiotic resistance in the viral fraction of dairy products and a nut-based milk.

Phages, the most abundant biological entities in the biosphere, can carry different bacterial genes, including those conferring antibiotic resistance. In this study, dairy products were analyzed by qPCR for the presence of phages and phage particles containing antibiotic resistance genes (ARGs). Eleven ARGs were identified in 50 samples of kefir, yogurt, milk, fresh cheese and nut-based milk (horchata), purchased from local retailers in Barcelona. Propagation experiments showed that at least some of the phages isolated from these samples infected Escherichia coli WG5, which was selected as the host strain because it does not contain prophages or ARGs in its genome. Electron microscopy revealed that the phage particles showed morphologies compatible with the Myoviridae and Siphoviridae families. Our results show that dairy products contain ARGs within infectious phage particles and may therefore serve as a reservoir of ARGs that can be mobilized to susceptible hosts, both in the food matrix and in the intestinal tract after ingestion.

Highly absorbent hydrogels comprised from interpenetrated networks of alginate-polyurethane for biomedical applications.

Developing new approaches to improve the swelling, degradation rate, and mechanical properties of alginate hydrogels without compromising their biocompatibility for biomedical applications represents a potential area of research. In this work, the generation of interpenetrated networks (IPN) comprised from alginate-polyurethane in an aqueous medium is proposed to design hydrogels with tailored properties for biomedical applications. Aqueous polyurethane (PU) dispersions can crosslink and interpenetrate alginate chains, forming amide bonds that allow the structure and water absorption capacity of these novel hydrogels to be regulated. In this sense, this work focuses on studying the relation of the PU concentration on the properties of these hydrogels. The results indicate that the crosslinking of the alginate with PU generates IPN hydrogels with a crystalline structure characterized by a homogeneous smooth surface with high capacity to absorb water, tailoring the degradation rate, thermal decomposition, and storage module, not altering the native biocompatibility of alginate, providing character to inhibit the growth of E. coli and increasing also its hemocompatibility. The IPN hydrogels that include 20 wt.% of PU exhibit a reticulation index of 46 ± 4%, swelling capacity of 545 ± 13% at 7 days of incubation at physiological pH, resistance to both acidic and neutral hydrolytic degradation, mechanical improvement of 91 ± 1%, and no cytotoxicity for monocytes and fibroblasts growing for up to 72 h of incubation. These results indicate that these novel hydrogels can be used for successful biomedical applications in the design of wound healing dressings.

Rapid viscoelastic changes are a hallmark of early leukocyte activation.

To accomplish their critical task of removing infected cells and fighting pathogens, leukocytes activate by forming specialized interfaces with other cells. The physics of this key immunological process are poorly understood, but it is important to understand them because leukocytes have been shown to react to their mechanical environment. Using an innovative micropipette rheometer, we show in three different types of leukocytes that, when stimulated by microbeads mimicking target cells, leukocytes become up to 10 times stiffer and more viscous. These mechanical changes start within seconds after contact and evolve rapidly over minutes. Remarkably, leukocyte elastic and viscous properties evolve in parallel, preserving a well-defined ratio that constitutes a mechanical signature specific to each cell type. Our results indicate that simultaneously tracking both elastic and viscous properties during an active cell process provides a new, to our knowledge, way to investigate cell mechanical processes. Our findings also suggest that dynamic immunomechanical measurements can help discriminate between leukocyte subtypes during activation.

Inhaled corticosteroids may have a protective effect against coronavirus infection.

BACKGROUND: Spain has been severely affected by the COVID-19 epidemic, with 195,944 persons infected and 20,453 deaths at the time of writing. Older people with respiratory or cardiac conditions are most at risk. OBJECTIVE: The aim was to compare respiratory symptoms in nursing home residents and patients with uncontrolled asthma, who are considered vulnerable to COVID-19. METHODS: We studied 134 nursing home residents and 139 patients with uncontrolled asthma, groups vulnerable to COVID-19. Demographic characteristics, clinical manifestations, outcomes, key laboratory results, and radiological images were collected from medical records. COVID-19 infection was detected by polymerase chain reaction (PCR). RESULTS: Thirteen (9.3%) patients with uncontrolled asthma, all receiving inhaled corticosteroids were infected by COVID-19. Eighty (60%) nursing home residents were infected; only 28, all of whom had received inhaled corticosteroids, had a good prognosis. CONCLUSIONS: Early treatment with inhaled corticosteroids may be helpful in COVID-19 infection. Persons with an allergy might have some protective mechanisms against coronavirus.

Inhaled corticosteroids may have a protective effect against coronavirus infection

BACKGROUND: Spain has been severely affected by the COVID-19 epidemic, with 195,944 persons infected and 20,453 deaths at the time of writing. Older people with respiratory or cardiac conditions are most at risk. OBJECTIVE: The aim was to compare respiratory symptoms in nursing home residents and patients with uncontrolled asthma, who are considered vulnerable to COVID-19.METHODS: We studied 134 nursing home residents and 139 patients with uncontrolled asthma, groups vulnerable to COVID-19. Demographic characteristics, clinical manifestations, out-comes, key laboratory results, and radiological images were collected from medical records. COVID-19 infection was detected by polymerase chain reaction (PCR).RESULTS: Thirteen (9.3%) patients with uncontrolled asthma, all receiving inhaled corticoste-roids were infected by COVID-19. Eighty (60%) nursing home residents were infected; only 28, all of whom had received inhaled corticosteroids, had a good prognosis CONCLUSIONS: Early treatment with inhaled corticosteroids may be helpful in COVID-19 infection. Persons with an allergy might have some protective mechanisms against coronavirus

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Diacylglycerol kinase ζ promotes actin cytoskeleton remodeling and mechanical forces at the B cell immune synapse.

Diacylglycerol kinases (DGKs) limit antigen receptor signaling in immune cells by consuming the second messenger diacylglycerol (DAG) to generate phosphatidic acid (PA). Here, we showed that DGKζ promotes lymphocyte function-associated antigen 1 (LFA-1)-mediated adhesion and F-actin generation at the immune synapse of B cells with antigen-presenting cells (APCs), mostly in a PA-dependent manner. Measurement of single-cell mechanical force generation indicated that DGKζ-deficient B cells exerted lower forces at the immune synapse than did wild-type B cells. Nonmuscle myosin activation and translocation of the microtubule-organizing center (MTOC) to the immune synapse were also impaired in DGKζ-deficient B cells. These functional defects correlated with the decreased ability of B cells to present antigen and activate T cells in vitro. The in vivo germinal center response of DGKζ-deficient B cells was also reduced compared with that of wild-type B cells, indicating that loss of DGKζ in B cells impaired T cell help. Together, our data suggest that DGKζ shapes B cell responses by regulating actin remodeling, force generation, and antigen uptake-related events at the immune synapse. Hence, an appropriate balance in the amounts of DAG and PA is required for optimal B cell function.

Mastocytosis and the Fig Wasp (Blastophaga psenes).

BACKGROUND: Mastocytosis involves the abnormal proliferation of mast cells and clinical variability. In the case of anaphylaxis, the triggering antigen, often associated with Hymenoptera allergens, must be identified. The common fig (Ficus carica) requires the fig wasp (Blastophaga psenes) for pollination. OBJECTIVE: We evaluated the ingestion of B. psenes as a trigger of anaphylaxis in patients with mastocytosis. MATERIAL AND METHODS: Skin prick tests (SPTs) and specific immunoglobulin E to the possible involved allergens were carried out in the patient and in 4 controls allergic to Hymenoptera and fig. Given the possibility of hidden allergens, we studied the source (figs of various origins) and possible hypersensitivity to Hymenoptera allergens, including the fig wasp (B. psenes). RESULTS: In all subjects, the SPT resulted in a wheal (larger than with histamine) with the extract of the inferior part of the female fig but not with the male extract (lower pole and stem). Immune detection was made with the stem and inferior part of figs and venom of Polistes and Vespula. Recognition bands were observed at 25 kDa with female fig extracts that were also recognized by the patient with anaphylaxis to Hymenoptera venom. CONCLUSIONS: We cannot exclude the possibility that the ingestion of fig with Blastophaga antigens may have triggered anaphylaxis in our patient.

Distinct Roles for Bruton's Tyrosine Kinase in B Cell Immune Synapse Formation.

Bruton's tyrosine kinase (Btk) has a key role in the signaling pathways of receptors essential for the B lymphocyte response. Given its implication in B cell-related immunodeficiencies, leukemias/lymphomas and autoimmunity, Btk is studied intensely and is a target for therapy. Here, using primary B cells from distinct mouse models and the pharmacological inhibitors ibrutinib and acalabrutinib, we report distinct roles for Btk in antigen-triggered immune synapse (IS) formation. Btk recruitment to the plasma membrane regulates the B cell ability to trigger IS formation as well as its appropriate molecular assembly; Btk shuttling/scaffold activities seem more relevant than the kinase function on that. Btk-kinase activity controls antigen accumulation at the IS through the PLCγ2/Ca2+ axis. Impaired Btk membrane-recruitment or kinase function likewise alters antigen-triggered microtubule-organizing center (MTOC) polarization to the IS, B cell activation and proliferation. Data also show that, for B cell function, IS architecture is as important as the quantity of antigen that accumulates at the synapse.

Diacylglycerol kinase ζ limits the polarized recruitment of diacylglycerol-enriched organelles to the immune synapse in T cells.

The antigen-induced formation of an immune synapse (IS) between T cells and antigen-presenting cells results in the rapid generation of the lipid second messenger diacylglycerol (DAG) in T cells. Diacylglycerol kinase ζ (DGKζ) converts DAG into phosphatidic acid (PA). Cytotoxic T lymphocytes (CTLs) from mice deficient in DGKζ have enhanced antiviral and antitumor activities, indicating that the amount of DAG controls the effectiveness of the T cell response. We characterized the second C1 domain of protein kinase Cθ (PKCθ), a DAG-binding protein that is specifically recruited to the IS, as a biological sensor to observe the generation of a DAG gradient during IS formation. In experiments with transgenic mouse CTLs expressing the OT-I T cell receptor (TCR), we showed that both strong and weak interactions between antigen and the TCR led to the rapid generation of DAG, whereas only strong interactions induced the movement of DAG-enriched organelles toward the IS. In DGKζ-deficient CTLs, antigen stimulation led to the enhanced accumulation of DAG-containing organelles at the IS; however, impaired activation of the PA effector PKCζ resulted in lack of reorientation of the microtubule-organizing center toward the IS, a process needed for effective T cell activation. Together, these data suggest that the activation of DGKζ downstream of antigen recognition provides a mechanism that ensures the activation of PA-dependent signaling as a direct result of the strength of TCR-dependent DAG mobilization.

Homeobox NKX2-3 promotes marginal-zone lymphomagenesis by activating B-cell receptor signalling and shaping lymphocyte dynamics.

NKX2 homeobox family proteins have a role in cancer development. Here we show that NKX2-3 is overexpressed in tumour cells from a subset of patients with marginal-zone lymphomas, but not with other B-cell malignancies. While Nkx2-3-deficient mice exhibit the absence of marginal-zone B cells, transgenic mice with expression of NKX2-3 in B cells show marginal-zone expansion that leads to the development of tumours, faithfully recapitulating the principal clinical and biological features of human marginal-zone lymphomas. NKX2-3 induces B-cell receptor signalling by phosphorylating Lyn/Syk kinases, which in turn activate multiple integrins (LFA-1, VLA-4), adhesion molecules (ICAM-1, MadCAM-1) and the chemokine receptor CXCR4. These molecules enhance migration, polarization and homing of B cells to splenic and extranodal tissues, eventually driving malignant transformation through triggering NF-κB and PI3K-AKT pathways. This study implicates oncogenic NKX2-3 in lymphomagenesis, and provides a valid experimental mouse model for studying the biology and therapy of human marginal-zone B-cell lymphomas.

[Practical guide for the use of biological agents in rheumatoid arthritis - December 2011 update]. / Guia prático de utilização de terapêuticas biotecnológicas na artrite reumatóide - actualização de Dezembro 2011.

The authors review the practical aspects of biological therapy use for rheumatoid arthritis patients, commenting safety issues before and after treatment initiation and the best treatment strategies to optimize efficacy.

Portuguese guidelines for the use of biological agents in rheumatoid arthritis - March 2010 update.

The authors present the revised version of the Portuguese Society of Rheumatology (SPR) guidelines for the treatment of rheumatoid arthritis (RA) with biological therapies. In these guidelines the criteria for introduction and maintenance of biological agents are discussed as well as the contraindications and procedures in the case of non-responders. Biological treatment should be considered in RA patients with a disease activity score 28 (DAS 28) superior to 3.2 despite treatment with 20mg/week of methotrexate (MTX) for at least 3 months or, if such treatment is not possible, after 6 months of other conventional disease modifying drug or combination therapy. A DAS 28 score between 2.6 and 3.2 with a significant functional or radiological deterioration under treatment with conventional regimens could also constitute an indication for biological treatment. The treatment goal should be remission or, if that is not achievable, at least a low disease activity, characterized by a DAS28 lower than 3.2, without significative functional or radiological worsening. The response criteria, at the end of the first 3 months of treatment, are a decrease of 0.6 in the DAS28 score. After 6 months of treatment response criteria is defined as a decrease of more than 1.2 in the DAS28 score. Non-responders, in accordance to the Rheumatologist's clinical opinion, should try a switch to another biological agent (tumour necrosis factor antagonist, abatacept, rituximab or tocilizumab).

[Nailfold capillaroscopy in the evaluation of Raynaud's phenomenon and undifferentiated connective tissue disease]. / A Capilaroscopia do Leito Ungueal na Avaliação Prognóstica do Fenómeno de Raynaud e da Doença Indiferenciada do Tecido Conjuntivo.

BACKGROUND: Microvascular abnormalities involved in the pathogenic mechanism of several connective tissue disorders can be detected by nailfold capillaroscopy. OBJECTIVES: Evaluation of the interest of nailfold capillaroscopy results in patients with Raynaud s phenomenon or undifferentiated connective tissue disease and their correlation with diagnostic and therapeutical evolution. METHODS: Selection of capillaroscopic and laboratory results of patients with the diagnosis of Raynaud s phenomenon (without defined connective tissue disease) or undifferentiated connective tissue disease. Evaluation of the present diagnosis and treatment comparing with the ones existed at the time of capillaroscopy performance. RESULTS: 80 patients were enrolled with an age of 51.4+/-14.3 years (mean+/-SD) 78 females (97.5%) with Raynaud s phenomenon and undifferentiated connective tissue disease 27 patients (33.8%); Raynaud s Phenomenon 46 patients (57.5%); undifferentiated connective tissue disease 7 patients (8.7%). The capillaroscopic results were normal 30 patients (37.5%); minor changes tortuosity enlargement 16 patients (20.0%) major changes 34 patients (42.5%) hemorrhages 25 patients (31.3%) megacapillaries 26 patients (32.5%) avascular areas 3 patients (3.8%). The introduction of new treatments after the capillaroscopy occurred in 32 patients (40.0%) and a new diagnosis was done in 39 patients (48.8%). Major changes in capillaroscopy correlated with the change of diagnosis and the introduction of a new treatment (p<0.0001). CONCLUSION: Nailfold capillaroscopy performed in patients with isolated Raynaud s phenomenon or undifferentiated connective tissue disease has a role in the prognostic evaluation related to the possibility of an evolution of the diagnosis or to the need of the introduction of new treatments.

Capillarosecopic patterns in rheumatic diseases.

Nailfold capillaroscopy (NVC) is a simple, non-invasive, inexpensive and useful method for the analysis of microvascular abnormalities found in several rheumatic disorders. The well-known Raynaud's phenomenon is a clinical condition that should promptly lead to a microvascular analysis, in order to distinguish its primary form (functional, not disease associated) from the secondary Raynaud's phenomenon (disease associated). NVC has an exceptional predictive value in this early distinction, and this may be the best advantage this technique can offer. Microvascular damage is a typical feature of Systemic Sclerosis (SSc) and more than 95% of the patients present architectural disorganization, giant capillaries, haemorrhages, loss of capillaries, avascular areas and neovascularization, as main microvascular abnormalities. These sequential capillaroscopic changes characterize the "scleroderma pattern" and reflect the SSc microangiopathy. In dermatomyositis and undifferentiated connective tissue disease the capillaroscopic aspects are generally named as "scleroderma-like pattern". Capillaroscopy changes have also been found in other systemic rheumatic diseases such as Systemic Lupus Erythematosus, Antiphospholipid Syndrome and Sjögren's Syndrome, further epidemiological and clinical studies are needed to better characterize and standardize nailfold capillaroscopy patterns in these disorders.