New Molecular Insights into Immune Cell Development.

During development innate lymphoid cells and specialized lymphocyte subsets colonize peripheral tissues, where they contribute to organogenesis and later constitute the first line of protection while maintaining tissue homeostasis. A few of these subsets are produced only during embryonic development and remain in the tissues throughout life. They are generated through a unique developmental program initiated in lympho-myeloid-primed progenitors, which lose myeloid and B cell potential. They either differentiate into innate lymphoid cells or migrate to the thymus to give rise to embryonic T cell receptor-invariant T cells. At later developmental stages, adaptive T lymphocytes are derived from lympho-myeloid progenitors that colonize the thymus, while lymphoid progenitors become specialized in the production of B cells. This sequence of events highlights the requirement for stratification in the establishment of immune functions that determine efficient seeding of peripheral tissues by a limited number of cells.

Epithelia Use Butyrophilin-like Molecules to Shape Organ-Specific γδ T Cell Compartments.

Many body surfaces harbor organ-specific γδ T cell compartments that contribute to tissue integrity. Thus, murine dendritic epidermal T cells (DETCs) uniquely expressing T cell receptor (TCR)-Vγ5 chains protect from cutaneous carcinogens. The DETC repertoire is shaped by Skint1, a butyrophilin-like (Btnl) gene expressed specifically by thymic epithelial cells and suprabasal keratinocytes. However, the generality of this mechanism has remained opaque, since neither Skint1 nor DETCs are evolutionarily conserved. Here, Btnl1 expressed by murine enterocytes is shown to shape the local TCR-Vγ7(+) γδ compartment. Uninfluenced by microbial or food antigens, this activity evokes the developmental selection of TCRαß(+) repertoires. Indeed, Btnl1 and Btnl6 jointly induce TCR-dependent responses specifically in intestinal Vγ7(+) cells. Likewise, human gut epithelial cells express BTNL3 and BTNL8 that jointly induce selective TCR-dependent responses of human colonic Vγ4(+) cells. Hence, a conserved mechanism emerges whereby epithelia use organ-specific BTNL/Btnl genes to shape local T cell compartments.

Asynchronous lineage priming determines commitment to T cell and B cell lineages in fetal liver.

The molecular events that initiate lymphoid-lineage specification remain unidentified because the stages of differentiation during which lineage commitment occurs are difficult to characterize. We isolated fetal liver progenitor cells undergoing restriction of their differentiation potential toward the T cell-innate lymphoid cell lineage or the B cell lineage. Transcripts that defined the molecular signatures of these two subsets were sequentially upregulated in lympho-myeloid precursor cells and in common lymphoid progenitor cells, respectively, and this preceded lineage restriction; this indicates that T cell-versus-B cell commitment is not a binary fate 'decision'. The T cell-bias and B cell-bias transcriptional programs were frequently co-expressed in common lymphoid progenitor cells and were segregated in subsets biased toward T cell differentiation or B cell differentiation, after interleukin 7 (IL-7) signaling that controlled the number of progenitor cells engaging in T cell differentiation versus B cell differentiation.

Assembling the layers of the hematopoietic system: A window of opportunity for thymopoiesis in the embryo.

During embryonic development, several independent generations of hematopoietic cells were identified. They occur in the yolk sac and the intra-embryonic major arteries, in a narrow window of development. They arise sequentially, starting with primitive erythrocytes in the yolk sac blood islands, progressing to less differentiated erythromyeloid progenitors still in the yolk sac, and culminating with multipotent progenitors, some of which will generate the adult hematopoietic stem cell compartment. All these cells contribute to the formation of a layered hematopoietic system that reflects adaptative strategies to the fetal environment and the embryo's needs. It is mostly composed, at these stages, of erythrocytes and tissue-resident macrophages both of yolk sac origin, the latter persisting throughout life. We propose that subsets of lymphocytes of embryonic origin derive from a different intra-embryonic generation of multipotent cells occurring before the emergence of hematopoietic stem cell progenitors. These multipotent cells have a limited lifespan and generate cells that provide basic protection against pathogens before the adaptive immune system is functional, contribute to tissue development and homeostasis, and shape the establishment of a functional thymus. Understanding the properties of these cells will impact the understanding of childhood leukemia and of adult autoimmune pathology and thymic involution.

Two waves of distinct hematopoietic progenitor cells colonize the fetal thymus.

The generation of T cells depends on the migration of hematopoietic progenitor cells to the thymus throughout life. The identity of the thymus-settling progenitor cells has been a matter of considerable debate. Here we found that thymopoiesis was initiated by a first wave of T cell lineage-restricted progenitor cells with limited capacity for population expansion but accelerated differentiation into mature T cells. They gave rise to αß and γδ T cells that constituted Vγ3(+) dendritic epithelial T cells. Thymopoiesis was subsequently maintained by less-differentiated progenitor cells that retained the potential to develop into B cells and myeloid cells. In that second wave, which started before birth, progenitor cells had high proliferative capacity but delayed differentiation capacity and no longer gave rise to embryonic γδ T cells. Our work reconciles conflicting hypotheses on the nature of thymus-settling progenitor cells.

A wave of bipotent T/ILC-restricted progenitors shapes the embryonic thymus microenvironment in a time-dependent manner.

During embryonic development, multiple waves of hematopoietic progenitors with distinct lineage potential are differentially regulated in time and space. Two different waves of thymic progenitors colonize the fetal thymus where they contribute to thymic organogenesis and homeostasis. The origin, the lineage differentiation potential of the first wave, and their relative contribution in shaping the thymus architecture, remained, however, unclear. Here, we show that the first wave of thymic progenitors comprises a unique population of bipotent T and innatel lymphoid cells (T/ILC), generating a lymphoid tissue inducer cells (LTi's), in addition to invariant Vγ5+ T cells. Transcriptional analysis revealed that innate lymphoid gene signatures and, more precisely, the LTi-associated transcripts were expressed in the first, but not in the second, wave of thymic progenitors. Depletion of early thymic progenitors in a temporally controlled manner showed that the progeny of the first wave is indispensable for the differentiation of autoimmune regulator-expressing medullary thymic epithelial cells (mTECs). We further show that these progenitors are of strict hematopoietic stem cell origin, despite the overlap between lymphopoiesis initiation and the transient expression of lymphoid-associated transcripts in yolk sac (YS) erythromyeloid-restricted precursors. Our work highlights the relevance of the developmental timing on the emergence of different lymphoid subsets, required for the establishment of a functionally diverse immune system.

An Alternative Study about the Geometry and the First Law of Thermodynamics for AdS Lovelock Gravity, Using the Definition of Conserved Charges.

In this work, we introduce an extension of the study of the first law of thermodynamics of black holes based on the geometry of the extended phase space for AdS Lovelock gravities, which includes changes in scales. As expected, the result obtained coincides with the previously known four-dimensional case. For higher dimensions, the result is the rise of two new contributions to the first law of thermodynamics. The first term corresponds to corrections of the usual definition of thermodynamic volumes at the horizon due to the presence of the higher curvature terms. The second term arises in odd dimensions, comes from the asymptotic region, and corresponds to a scale transformation of the form ∝δ^ln(l/ℓ), with l the AdS radius and ℓ a parameter. A particularly interesting case corresponds to the Chern Simons gravity where the change scale does not generate a contribution at the asymptotic region, likely due to the Chern Simons AdS local symmetry.

Factors underlying compliance with a healthy snacking initiative in the school environment: accounts of school principals in Montevideo (Uruguay).

OBJECTIVE: To evaluate the implementation of the Uruguayan healthy snacking initiative in primary and secondary schools in the capital, and to explore the factors underlying compliance from the perspective of school principals. DESIGN: A mixed-method approach was used, which included semi-structured interviews with school principals and a survey of the foods and beverages sold and advertised in the schools. SETTING: Primary and secondary schools in Montevideo (the capital city of Uruguay). PARTICIPANTS: School principals. RESULTS: The great majority of the schools did not comply with the initiative. Exhibition of non-recommended products was the main cause for non-compliance, followed by advertising of non-recommended products through promotional activities of food and beverage companies. Although school principals were aware of the healthy snack initiative and showed a positive attitude towards it, the majority lacked knowledge about its specific content. Factors underlying compliance with the healthy snacking initiative were related to its characteristics, characteristics of the schools, and external factors such as family habits and advertising. CONCLUSIONS: Results showed that the rationale underlying the selling of products at schools favours the availability of ultra-processed products and constitutes the main barrier for the promotion of healthy dietary habits among children and adolescents. Strategies aimed at facilitating the identification of unhealthy foods and beverages and provision of incentives to canteen managers to modify their offer are recommended.

Metalaxyl Degradation by Mucorales Strains Gongronella sp. and Rhizopus oryzae.

In this study, the degradation of metalaxyl was investigated in the presence of two Mucorales strains, previously isolated from soil subjected to repeated treatments with this fungicide and selected after enrichment technique. Fungal strains were characterised by a polyphasic approach using phylogenetic analysis of the Internal Transcribed Spacer (ITS) gene region, phenotypic characterisation by Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) spectral analysis, and growth kinetics experiments. The strains were identified as Gongronella sp. and Rhizopus oryzae. The fungal growth kinetics in liquid cultures containing metalaxyl fits with Haldane model. Under laboratory conditions, the ability of Gongronella sp. and R. oryzae cultures to degrade metalaxyl was evaluated in liquid cultures and soil experiments. Both species were able to: (a) use metalaxyl as the main carbon and energy source; and (b) degrade metalaxyl in polluted soils, with rates around 1.0 mg kg-¹ d-¹. This suggests these strains could degrade metalaxyl in soils contaminated with this fungicide.

Critical role of TCR specificity in the development of Vγ1Vδ6.3+ innate NKTγδ cells.

A large fraction of innate NKTγδ T cells uses TCRs composed of a semi-invariant Vδ6.3/6.4-Dδ2-Jδ1 chain together with more diverse Vγ1-Jγ4 chains. To address the role of γδTCR specificity in their generation, we analyzed their development in mice transgenic (Tg) for a Vγ1-Jγ4 chain frequently expressed by NKTγδ cells (Tg-γ) and in mice Tg for the same Vγ1-Jγ4 chain together with a Vδ6BDδ2Jδ1 chain not usually found among NKTγδ cells (Tg-γδ). Surprisingly, both promyelocytic leukemia zinc finger (PLZF)(+) and NK1.1(+) NKTγδ cells were found in the thymus of Tg-γδ albeit at lower numbers than in Tg-γ mice, and virtually all of them expressed the Tg TCR. However, the PLZF(+) subset, but not the NK1.1(+) subset, also expressed an endogenous Vδ6.3/6.4 chain, and its size was severely reduced in TCRδ(-/-) Tg-γδ mice. These results could suggest that the PLZF(+) and the NK1.1(+) subsets are developmentally unrelated. However, PLZF(+) and NK1.1(+) NKTγδ cells express identical Vδ6.3/6.4 chains, and NK1.1(+) cells can be obtained upon intrathymic injection of sorted PLZF(+) cells, thus indicating their developmental relationship. In fact, the NK1.1(+) γδ thymocytes present in Tg-γδ mice correspond to a small subset of NK1.1(+) γδ thymocytes in wild-type animals, which express a more diverse repertoire of TCRs and can be recognized by the expression of the CD62L Ag. Collectively, our data demonstrated that TCR specificity is essential for the development of most NKTγδ T cells and revealed a developmental heterogeneity in γδ T cells expressing the NK1.1 marker.

Temporal predisposition to αß and γδ T cell fates in the thymus.

How T cell progenitors engage into the γδ or αß T cell lineages is a matter of intense debate. In this study, we analyzed the differentiation potential of single thymocytes from wild-type and TCRγδ-transgenic mice at two sequential early developmental stages. Double-negative (DN) 3 progenitors from both wild-type and transgenic mice retain the capacity to engage into both pathways, indicating that full commitment is only completed after this stage. More importantly, DN2 and DN3 progenitors from TCRγδ transgenic mice have strong biases for opposite fates, indicating that developmentally regulated changes, other than the production of a functional TCR, altered their likelihood to become a γδ or an αß T cell. Thus, unlike the differentiation in other hematopoietic lineages, T cell progenitors did not restrict, but rather switch their differentiation potential as they developed.

Differential requirement of RasGRP1 for γδ T cell development and activation.

γδ T (γδT) cells belong to a distinct T cell lineage that performs immune functions different from αß T (αßT) cells. Previous studies established that Erk1/2 MAPKs are critical for positive selection of αßT cells. Additional evidence suggests that increased Erk1/2 activity promotes γδT cell generation. RasGRP1, a guanine nucleotide-releasing factor for Ras, plays an important role in positive selection of αßT cells by activating the Ras-Erk1/2 pathway. In this article, we demonstrate that RasGRP1 is critical for TCR-induced Erk1/2 activation in γδT cells, but it exerts different roles for γδT cell generation and activation. Deficiency of RasGRP1 does not obviously affect γδT cell numbers in the thymus, but it leads to increased γδT cells, particularly CD4(-)CD8(+) γδT cells, in the peripheral lymphoid organs. The virtually unhindered γδT cell development in the RasGRP1(-/-) thymus proved to be cell intrinsic, whereas the increase in CD8(+) γδT cells is caused by non-cell-intrinsic mechanisms. Our data provide genetic evidence that decreased Erk1/2 activation in the absence of RasGRP1 is compatible with γδT cell generation. Although RasGRP1 is dispensable for γδT cell generation, RasGRP1-deficient γδT cells are defective in proliferation following TCR stimulation. Additionally, RasGRP1-deficient γδT cells are impaired to produce IL-17 but not IFNγ. Together, these observations revealed that RasGRP1 plays differential roles for γδ and αß T cell development but is critical for γδT cell proliferation and production of IL-17.

Innate NKTγδ and NKTαß cells exert similar functions and compete for a thymic niche.

The transcriptional regulator promyelocytic leukemia zinc finger (PLZF) is highly expressed during the differentiation of natural killer T (NKT) cells and is essential for the acquisition of their effector/memory innate-like phenotype. Staining with anti-PLZF and anti-NK1.1 Abs allows the definition of two subsets of NKTαß and NKTγδ thymocytes that differ phenotypically and functionally: a PLZF(+) NK1.1(-) subset composed of mostly quiescent cells that secrete more IL-4 than IFN-γ upon activation and a PLZF(+/-) NK1.1(+) subset that expresses CD127, NK1.1, and other NK-cell markers, secrete more IFN-γ than IL-4 upon activation and contains a sizable fraction of dividing cells. The size of the NK1.1(+) population is very tightly regulated and NK1.1(+) αß and γδ thymocytes compete for a thymic niche. Furthermore, the relative representation of the PLZF(+) and NK1.1(+) subsets varies in a strain-specific manner with C57BL/6 (B6) mice containing more NK1.1(+) cells and (B6 × DBA/2)F1 (B6D2F1) mice more PLZF(+) cells. Consequently, activation of NKT cells in vivo is expected to result in higher levels of IL-4 secreted in B6D2F1 mice than in B6 mice. Consistent with this possibility, B6D2F1 mice, when compared with B6 mice, contain more "innate" CD8(+) thymocytes, the generation of which depends on IL-4 secreted by NKT cells.

Degradation of metalaxyl and folpet by filamentous fungi isolated from Portuguese (Alentejo) vineyard soils.

Degradation of xenobiotics by microbial populations is a potential method to enhance the effectiveness of ex situ or in situ bioremediation. The purpose of this study was to evaluate the impact of repeated metalaxyl and folpet treatments on soil microbial communities and to select soil fungal strains able to degrade these fungicides. Results showed enhanced degradation of metalaxyl and folpet in vineyards soils submitted to repeated treatments with these fungicides. Indeed, the greatest degradation ability was observed in vineyard soil samples submitted to greater numbers of treatments. Respiration activities, as determined in the presence of selective antibiotics in soil suspensions amended with metalaxyl and folpet, showed that the fungal population was the microbiota community most active in the degradation process. Batch cultures performed with a progressive increase of fungicide concentrations allowed the selection of five tolerant fungal strains: Penicillium sp. 1 and Penicillium sp. 2, mycelia sterila 1 and 3, and Rhizopus stolonifer. Among these strains, mycelium sterila 3 and R. stolonifer presented only in vineyard soils treated with repeated application of these fungicides and showed tolerance >1,000 mg l(-1) against commercial formulations of metalaxyl (10 %) plus folpet (40 %). Using specific methods for inducing sporulation, mycelium sterila 3 was identified as Gongronella sp. Because this fungus is rare, it was compared using csM13-polymerase chain reaction (PCR) with the two known species, Gongronella butleri and G. lacrispora. The high tolerance to metalaxyl and folpet shown by Gongronella sp. and R. stolonifer might be correlated with their degradation ability. Our results point out that selected strains have potential for the bioremediation of metalaxyl and folpet in polluted soil sites.

Cutting edge: Thymic NK cells develop independently from T cell precursors.

Although NK cells in the mouse are thought to develop in the bone marrow, a small population of NK cells in the thymus has been shown to derive from a GATA3-dependent pathway. Characteristically, thymic NK cells express CD127 and few Ly49 molecules and lack CD11b. Because these NK cells develop in the thymus, the question of their relationship to the T cell lineage has been raised. Using several different mouse models, we find that unlike T cells, thymic NK cells are not the progeny of Rorc-expressing progenitors and do not express Rag2 or rearrange the TCRγ locus. We further demonstrate that thymic NK cells develop independently of the Notch signaling pathway, supporting the idea that thymic NK cells represent bona fide NK cells that can develop independently of all T cell precursors.

Development of promyelocytic zinc finger and ThPOK-expressing innate gamma delta T cells is controlled by strength of TCR signaling and Id3.

The broad-complex tramtrack and bric a brac-zinc finger transcriptional regulator (BTB-ZF), promyelocytic leukemia zinc finger (PLZF), was recently shown to control the development of the characteristic innate T cell phenotype and effector functions of NK T cells. Interestingly, the ectopic expression of PLZF was shown to push conventional T cells into an activated state that seems to be proinflammatory. The factors that control the normal expression of PLZF in lymphocytes are unknown. In this study, we show that PLZF expression is not restricted to NK T cells but is also expressed by a subset of gammadelta T cells, functionally defining distinct subsets of this innate T cell population. A second BTB-ZF gene, ThPOK, is important for the phenotype of the PLZF-expressing gammadelta T cells. Most importantly, TCR signal strength and expression of inhibitor of differentiation gene 3 control the frequency of PLZF-expressing gammadelta T cells. This study defines the factors that control the propensity of the immune system to produce potentially disease-causing T cell subsets.

TCR-inducible PLZF transcription factor required for innate phenotype of a subset of gammadelta T cells with restricted TCR diversity.

Some gammadelta and alphabeta T lymphocytes exhibit an "innate" phenotype associated with rapid cytokine responses. The PLZF transcription factor is essential for the innate phenotype of NKT cells. This report shows that PLZF is likewise responsible for the innate, NKT-like phenotype of Vgamma1+Vdelta6.3/Vdelta6.4+ cells. TCR cross-linking induced PLZF expression in all polyclonal immature gammadelta thymocytes, suggesting that agonist selection might be required for PLZF induction. Transgenic expression of Vgamma1Vdelta6.4 TCR was sufficient to support the development of large numbers of PLZF+ T cells, further supporting the importance of the TCR for PLZF induction. Interestingly, expression of this TCR transgene led to the development of spontaneous dermatitis.

Patellofemoral Pain Syndrome Risk Associated with Squats: A Systematic Review.

Patellofemoral pain syndrome (PFPS) is highly prevalent; it can cause severe pain and evolve into progressive functional loss, leading to difficulties performing daily tasks such as climbing and descending stairs and squatting. This systematic review aimed to find evidence, in the literature, of squat movements that can cause or worsen PFPS. This work was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, and its protocol was registered in PROSPERO (CRD42019128711). From the 6570 collected records, 37 were included. From these 37 articles, 27 present a causal relationship between knee flexion and PFPS, 8 describe a relationship, considering the greater existence of muscle contractions, and one article did not describe this relationship in its results. The main limitations stem from the fact that different studies used different evaluation parameters to compare the force exerted on the patellofemoral joint. Furthermore, most studies are focused on sports populations. After analysing the included works, it was concluded that all squat exercises can cause tension overload in the knee, especially with a knee flexion between 60° and 90° degrees. The main causal/worsening factors of PFPS symptoms are the knee translocation forward the toes (on the same body side) when flexing the knee, and the muscle imbalance between the thigh muscles.

Epidemiology of COVID-19 Among Indigenous Populations in Brazil.

BACKGROUND: Due to social and geographical isolation, indigenous people are more vulnerable to adverse conditions; however, there is a lack of data on the epidemics' impact on these populations. Thus, this article's objective was to describe the epidemiological situation of COVID-19 in indigenous communities in Brazil. METHODS: This descriptive observational study was carried out in indigenous communities in the municipality of Amaturá (Amazonas, Brazil). Individuals from the Alto Rio Solimões Special Indigenous Sanitary District (DSEI) who met the Sars-Cov-2 infection case definitions during the period between January and August 2020 were included. For case notification, the definitions adopted by the Ministry of Health of Brazil and by the Special Secretariat for Indigenous Health were considered. RESULTS: Out of the entire population served by the Alto Rio Solimões DSEI (n = 2890), 109 indigenous people were suspected of having been infected with Sars-Cov-R during the study period; a total of 89 cases were actually confirmed (rate: 3.08 cases/100,000 inhabitants). Most patients diagnosed with COVID-19 were female (56.2%), with a mean age of 32.4 (± 23.6) years. Predominant symptoms were fever (76.4%), dry cough (64%), and headache (60.7%). Complications occurred in 7.9% of the patients; no deaths were reported. CONCLUSION: These results enhance the observation that indigenous populations, even if relatively isolated, are exposed to COVID-19. The disease cases assessed showed a favorable evolution, which does not mean reducing the need for caring of this population.

Isolated open tibial shaft fracture: a seven-hospital, prospective observational study in two Latin America countries.

INTRODUCTION: open tibial fractures are challenging due to the frequent severe bone injury associated with poor soft tissue conditions. This is relevant in low- and middle-income countries, mainly related to delayed definitive fixation and lack of adequate training in soft tissue coverage procedures. Due to these factors, open tibial fracture is an important source of disability for Latin American countries. Herein we sought to provide an epidemiological overview of isolated open tibial shaft fracture across seven hospitals in southern cone of Latin America. The secondary goal was to assess the impact on quality of life based on return-to-work rate (RWR). METHODS: patients with an isolated open tibial shaft fracture treated in seven different hospitals from Brazil and Argentina from November 2017 to March 2020 were included in the study. Clinical and radiographic results were evaluated throughout the 120-day follow-up period. Final evaluation compared RWR with the SF-12 questionnaire, bone healing, and gait status. RESULTS: Seventy-two patients were treated, 57 followed for 120 days and 48 completed the SF-12 questionnaire. After 120 days, 70.6% had returned to work, 61.4% had experienced bone healing. Age, antibiotic therapy, type of definitive treatment, and infection significantly influenced the RWR. Gait status exhibited strong correlations with RWR and SF-12 physical component score. CONCLUSIONS: Isolated open tibial shaft fractures are potentially harmful to the patient's quality of life after 120 days of the initial management. RWR is significantly higher for younger patients, no history of infection, and those who could run in the gait status assessment.