The impact of nutritional status during fetal life on the overall health of adults has been recognized; however, dietary effects on the developing immune system are largely unknown. Development of ...secondary lymphoid organs occurs during embryogenesis and is considered to be developmentally programmed. Secondary lymphoid organ formation depends on a subset of type 3 innate lymphoid cells (ILC3) named lymphoid tissue inducer (LTi) cells. Here we show that mouse fetal ILC3s are controlled by cell-autonomous retinoic acid (RA) signalling in utero, which pre-sets the immune fitness in adulthood. We found that embryonic lymphoid organs contain ILC progenitors that differentiate locally into mature LTi cells. Local LTi cell differentiation was controlled by maternal retinoid intake and fetal RA signalling acting in a haematopoietic cell-autonomous manner. RA controlled LTi cell maturation upstream of the transcription factor RORγt. Accordingly, enforced expression of Rorgt restored maturation of LTi cells with impaired RA signalling, whereas RA receptors directly regulated the Rorgt locus. Finally, we established that maternal levels of dietary retinoids control the size of secondary lymphoid organs and the efficiency of immune responses in the adult offspring. Our results reveal a molecular link between maternal nutrients and the formation of immune structures required for resistance to infection in the offspring.
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DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary
The mucosa‐associated lymphoid tissue (MALT) International Prognostic Index (IPI) was recently proposed as a prognostic index for patients with MALT lymphoma. We aimed to investigate the ...prognostic value of the serum β2‐microglobulin level in the context of MALT‐IPI, and we proposed a new prognostic index. Survival outcomes were analysed with regard to β2‐microglobulin level, MALT‐IPI, and the new prognostic index in MALT lymphoma patients (n = 571). The validity of the new prognostic index was assessed using an independent cohort (n = 216). Patients with high β2‐microglobulin levels had significantly worse progression‐free survival (PFS) and overall survival (OS) outcomes. A high β2‐microglobulin level was independently associated with poor PFS and OS. β2‐microglobulin levels further stratified patients in the MALT‐IPI intermediate‐risk group in terms of PFS and OS. A new prognostic index based on the MALT‐IPI and the β2‐microglobulin level, MALT‐IPI‐B, was proposed. The MALT‐IPI‐B was able to stratify patients into subgroups having distinct PFS and OS outcomes in both the training and validation cohorts. MALT‐IPI‐B enabled the identification of patients with poor survival outcomes who were classified into the intermediate‐risk group by the MALT‐IPI. In conclusion, this new β2‐microglobulin‐based prognostic index may have the specific advantage of identifying high‐risk patients who may require systemic treatment.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Stromal cells (SCs) establish the compartmentalization of lymphoid tissues critical to the immune response. However, the full diversity of lymph node (LN) SCs remains undefined. Using droplet-based ...single-cell RNA sequencing, we identified nine peripheral LN non-endothelial SC clusters. Included are the established subsets, Ccl19hi T-zone reticular cells (TRCs), marginal reticular cells, follicular dendritic cells (FDCs), and perivascular cells. We also identified Ccl19lo TRCs, likely including cholesterol-25-hydroxylase+ cells located at the T-zone perimeter, Cxcl9+ TRCs in the T-zone and interfollicular region, CD34+ SCs in the capsule and medullary vessel adventitia, indolethylamine N-methyltransferase+ SCs in the medullary cords, and Nr4a1+ SCs in several niches. These data help define how transcriptionally distinct LN SCs support niche-restricted immune functions and provide evidence that many SCs are in an activated state.
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•Single-cell RNA sequencing of lymph node stromal cells reveals nine clusters•Known subsets TRCs, MRCs, FDCs, and perivascular cells identified•Five additional stromal cell clusters identified and anatomical locations determined•Two clusters, Cxcl9+ TRCs and Nr4a1+ SCs, are defined by activation signatures
Lymph node stromal cells support diverse processes, but bulk assessments obscure their niche-specific functions. Rodda et al. identify transcriptional profiles for nine lymph node stromal cell clusters using single-cell RNA sequencing, validate subset markers in situ, and suggest niche-restricted functions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The intestine contains some of the most diverse and complex immune compartments in the body. Here we describe a method for isolating human gut-associated lymphoid tissues (GALTs) that allows ...unprecedented profiling of the adaptive immune system in submucosal and mucosal isolated lymphoid follicles (SM-ILFs and M-ILFs, respectively) as well as in GALT-free intestinal lamina propria (LP). SM-ILF and M-ILF showed distinct patterns of distribution along the length of the intestine, were linked to the systemic circulation through MAdCAM-1+ high endothelial venules and efferent lymphatics, and had immune profiles consistent with immune-inductive sites. IgA sequencing analysis indicated that human ILFs are sites where intestinal adaptive immune responses are initiated in an anatomically restricted manner. Our findings position ILFs as key inductive hubs for regional immunity in the human intestine, and the methods presented will allow future assessment of these compartments in health and disease.
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•Novel methods for isolating human M-ILFs, SM-ILFs, and GALT-free intestinal LP•Human M-ILFs and SM-ILFs are highly organized sites of adaptive immune induction•An adaptive immune roadmap of human GALT and GALT-free LP•Human ILFs contribute to regionalized adaptive immune responses
Our understanding of the function of lymphoid follicles in the human intestine remains limited. Fenton et al. describe a method for identifying and isolating lymphoid follicles along the length of the human intestine and use it to show a role of these structures in regionalized adaptive immune responses.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
HIV-1-infected cells persist indefinitely despite the use of combination antiretroviral therapy (ART), and novel therapeutic strategies to target and purge residual infected cells in individuals on ...ART are urgently needed. Here, we demonstrate that CD4+ T cell-associated HIV-1 RNA is often highly enriched in cells expressing CD30, and that cells expressing this marker considerably contribute to the total pool of transcriptionally active CD4+ lymphocytes in individuals on suppressive ART. Using in situ RNA hybridization studies, we show co-localization of CD30 with HIV-1 transcriptional activity in gut-associated lymphoid tissues. We also demonstrate that ex vivo treatment with brentuximab vedotin, an antibody-drug conjugate (ADC) that targets CD30, significantly reduces the total amount of HIV-1 DNA in peripheral blood mononuclear cells obtained from infected, ART-suppressed individuals. Finally, we observed that an HIV-1-infected individual, who received repeated brentuximab vedotin infusions for lymphoma, had no detectable virus in peripheral blood mononuclear cells. Overall, CD30 may be a marker of residual, transcriptionally active HIV-1 infected cells in the setting of suppressive ART. Given that CD30 is only expressed on a small number of total mononuclear cells, it is a potential therapeutic target of persistent HIV-1 infection.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In modern bony fishes, or teleost fish, the general lack of leucocyte markers has greatly hampered investigations of the anatomy of the immune system and its reactions involved in inflammatory ...responses. We have previously reported the cloning and sequencing of the salmon CD3 complex, molecules that are specifically expressed in T cells. Here, we generate and validate sera recognizing a peptide sequence of the CD3ε chain. Flow cytometry analysis revealed high numbers of CD3ε+ or T cells in the thymus, gill and intestine, whereas lower numbers were detected in the head kidney, spleen and peripheral blood leucocytes. Subsequent morphological analysis showed accumulations of T cells in the thymus and spleen and in the newly discovered gill‐located interbranchial lymphoid tissue. In the latter, the T cells are embedded in a meshwork of epithelial cells and in the spleen, they cluster in the white pulp surrounding ellipsoids. The anatomical organization of the salmonid thymic cortex and medulla seems to be composed of three layers consisting of a sub‐epithelial medulla‐like zone, an intermediate cortex‐like zone and finally another cortex‐like basal zone. Our study in the salmonid thymus reports a previously non‐described tissue organization. In the intestinal tract, abundant T cells were found embedded in the epithelium. In non‐lymphoid organs, the presence of T cells was limited. The results show that the interbranchial lymphoid tissue is quantitatively a very important site of T cell aggregation, strategically located to facilitate antigen encounter. The interbranchial lymphoid tissue has no resemblance to previously described lymphoid tissues.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Tissue-specific autoimmunity occurs when selected antigens presented by susceptible alleles of the major histocompatibility complex are recognized by T cells. However, the reason why certain specific ...self-antigens dominate the response and are indispensable for triggering autoreactivity is unclear. Spontaneous presentation of insulin is essential for initiating autoimmune type 1 diabetes in non-obese diabetic mice
. A major set of pathogenic CD4 T cells specifically recognizes the 12-20 segment of the insulin B-chain (B:12-20), an epitope that is generated from direct presentation of insulin peptides by antigen-presenting cells
. These T cells do not respond to antigen-presenting cells that have taken up insulin that, after processing, leads to presentation of a different segment representing a one-residue shift, B:13-21
. CD4 T cells that recognize B:12-20 escape negative selection in the thymus and cause diabetes, whereas those that recognize B:13-21 have only a minor role in autoimmunity
. Although presentation of B:12-20 is evident in the islets
, insulin-specific germinal centres can be formed in various lymphoid tissues, suggesting that insulin presentation is widespread
. Here we use live imaging to document the distribution of insulin recognition by CD4 T cells throughout various lymph nodes. Furthermore, we identify catabolized insulin peptide fragments containing defined pathogenic epitopes in β-cell granules from mice and humans. Upon glucose challenge, these fragments are released into the circulation and are recognized by CD4 T cells, leading to an activation state that results in transcriptional reprogramming and enhanced diabetogenicity. Therefore, a tissue such as pancreatic islets, by releasing catabolized products, imposes a constant threat to self-tolerance. These findings reveal a self-recognition pathway underlying a primary autoantigen and provide a foundation for assessing antigenic targets that precipitate pathogenic outcomes by systemically sensitizing lymphoid tissues.
Much has been learned about how cells enter lymphoid tissues. But how do they leave? Sphingosine-1-phosphate (S1P) has emerged over the past decade as a central mediator of lymphocyte egress. In this ...review, we summarize the current understanding of how S1P promotes exit from the secondary lymphoid organs and thymus. We review what is known about additional requirements for emigration and summarize the mostly distinct requirements for exit from the bone marrow. Egress from lymphoid organs is limited during immune responses, and we examine how this regulation works. There is accumulating evidence for roles of S1P in directing immune cell behavior within lymphoid tissues. How such actions can fit together with the egress-promoting role of S1P is discussed. Finally, we examine current understanding of how FTY720, a drug that targets S1P receptors and is approved for the treatment of multiple sclerosis, causes immune suppression.
Secondary lymphoid organs are important locations for the initiation of adaptive immune responses. They develop before birth, and their formation requires interaction between ...lymphotoxin-α₁ß₂-expressing lymphoid-tissue inducer cells and lymphotoxin-ß receptor-expressing stromal organizer cells. Here, we discuss new insights into the earliest phases of peripheral lymph node and Peyer's patch formation that occur before lymphotoxin-ß receptor signalling and suggest a role for the developing nervous system. In addition, we discuss the differing requirements for the postnatal formation of mucosa-associated lymphoid tissues and tertiary lymphoid structures that develop at sites of chronic inflammation.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Summary
Systemic chronic immune activation is considered today as the driving force of CD4+ T‐cell depletion and acquired immunodeficiency syndrome (AIDS). A residual chronic immune activation ...persists even in HIV‐infected patients in which viral replication is successfully inhibited by anti‐retroviral therapy, with the extent of this residual immune activation being associated with CD4+ T‐cell loss. Unfortunately, the causal link between chronic immune activation and CD4+ T‐cell loss has not been formally established. This article provides first a brief historical overview on how the perception of the causative role of immune activation has changed over the years and lists the different kinds of immune activation characteristic of human immunodeficiency virus (HIV) infection. The mechanisms proposed to explain the chronic immune activation are multiple and are enumerated here, as well as the mechanisms proposed on how chronic immune activation could lead to AIDS. In addition, we summarize the lessons learned from natural hosts that know how to ‘show AIDS the door’, and discuss how these studies informed the design of novel immune modulatory interventions that are currently being tested. Finally, we review the current approaches aimed at targeting chronic immune activation and evoke future perspectives.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
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