Peripheral Lymphoid Organs Research Articles

Ubiquitin Ligases CBL and CBL-B Maintain the Homeostasis and Immune Quiescence of Dendritic Cells.

Dendritic cells (DCs) are composed of multiple lineages of hematopoietic cells and orchestrate immune responses upon detecting the danger and inflammatory signals associated with pathogen and damaged tissues. Under steady-state, DCs are maintained at limited numbers and the functionally quiescent status. While it is known that a fine balance in the DC homeostasis and activation status is also important to prevent autoimmune diseases and hyperinflammation, mechanisms that control DC development and activation under stead-state remain not fully understood. Here we show that DC-specific ablation of CBL and CBL-B (CBL-/-CBL-B-/-) leads to spontaneous liver inflammation and fibrosis and early death of the mice. The mutant mice have a marked expansion of classic CD8α+/CD103+ DCs (cDC1s) in peripheral lymphoid organs and the liver. These DCs exhibit atypical activation phenotypes characterized by an increased production of inflammatory cytokines and chemokines but not the cell surface MHC-II and costimulatory ligands. While the mutant mice also have massive T cell activation, lymphocytes are not required for the disease development. The CBL-/-CBL-B-/- mutation enhances FLT3-mTOR signaling, due to defective FLT3 ubiquitination and degradation. Blockade of FLT3-mTOR signaling normalizes the homeostasis of cDC1s and attenuates liver inflammation. Our result thus reveals a critical role of CBLs in the maintenance of DC homeostasis and immune quiescence. This regulation could be relevant to liver inflammatory diseases and fibrosis in humans.

ГІСТОЛОГІЧНИЙ АНАЛІЗ ЛІМФОЇДНИХ УТВОРЕНЬ ШЛУНКА І ТОНКОЇ КИШКИ У КЛІНІКО-ПАТОГЕНЕТИЧНОМУ ПРОФІЛІ БАБЕЗІОЗУ

Peripheral lymphoid organs respond immediately to a decrease in the body's defence responses, and their localisation and morphological specificity account for their active involvement in immunogenesis (especially in animals). This fact accentuates the morpho-functional estimation of the lymphoid tissue condition with the purpose of timely diagnostics of starting deviations and preventing the development of decompensated changes. Thus, the analysis of histological changes of the latter in natural and experimental prototypes of babesiosis is relevant. The aim of the research is to define the role of histological changes of lymphoid masses in the stomach and small intestine in the formation of the clinical and pathogenetic profile of babesiosis. We studied the structural changes of lymphoid masses of the stomach and small intestine in animals with babesiosis postmortem by histological methods. Fixation was traditionally carried out in 12% aqueous formalin solution, dehydration in alcohol (30º to absolute), and pouring (paraffin/ celloidin). Staining was conducted with eosin and haematoxylin, Van Gizon, Brasche. Analysis was performed using an Olympus BX-41 microscope, Japan (x 100; x 200; x 1350). Verification was carried out by cytological, ultramicroscopic, molecular genetic methods (polymerase chain reaction) and in a biological experiment on animals. Analysis of specimens of the lamina propria in the gastric mucosa of the animals in the experimental group and clinical observation group established that the latter contained diffuse accumulations of the lymphoid tissue. Their dispersal involved different parts of the organ, including quite large areas. Haematoxylin and eosin staining gave a clear histological pattern with a marked contrast of fragments, which contributed to diagnostic resources. Lymphoid follicles were observed occasionally, their marginal, mantle zones were blurred. The germinative centres were not detected and did not show any lucency. Neutrophilic granulocytes, monocytes and plasma cells predominated among the cellular leucocyte populations. Examination of the lymphoid apparatus of the small intestine showed predominantly diffuse nodular hyperplasia, which was widespread. A focal version of the nosological prototype was observed in individual specimens occasionally, presented as single cells (most often in the terminal parts of the organ). Histological changes of lymphoid masses of the stomach and small intestine in animals with babesiosis consisted in the development of expressive diffuse nodular hyperplasia with disorganization of the structure of lymphoid follicles, destruction of zonality of the latter, making it impossible to detect germinative centres.

A Central Role for Atg5 in Microbiota-Dependent Foxp3+ RORγt+ Treg Cell Preservation to Maintain Intestinal Immune Homeostasis.

Autophagy is an evolutionary conserved catabolic pathway that ensures the degradation of intracellular components. The autophagic pathway is regulated by autophagy-related (Atg) proteins that govern formation of double-membraned vesicles called autophagosomes. Autophagy deficiency in regulatory T (Treg) cells leads to increased apoptosis of these cells and to the development of autoimmune disorders, predominantly characterized by intestinal inflammation. Recently, RORγt-expressing Treg cells have been identified as key regulators of gut homeostasis, preventing intestinal immunopathology. To study the role of autophagy in RORγt+ Foxp3+ Treg cells, we generated mice lacking the essential component of the core autophagy machinery Atg5 in Foxp3+ cells. Atg5 deficiency in Treg cells led to a predominant intestinal inflammation. While Atg5-deficient Treg cells were reduced in peripheral lymphoid organs, the intestinal RORγt+ Foxp3+ subpopulation of Treg cells was most severely affected. Our data indicated that autophagy is essential to maintain the intestinal RORγt+ Foxp3+ Treg population, thereby protecting the mice from gut inflammatory disorders.

Emerging roles for IL-6 family cytokines as positive and negative regulators of ectopic lymphoid structures

IL-6 family cytokines display broad effects in haematopoietic and non-haematopoietic cells that regulate immune homeostasis, host defence, haematopoiesis, development, reproduction and wound healing. Dysregulation of these activities places this cytokine family as important mediators of autoimmunity, chronic inflammation and cancer. In this regard, ectopic lymphoid structures (ELS) are a pathological hallmark of many tissues affected by chronic disease. These inducible lymphoid aggregates form compartmentalised T cell and B cell zones, germinal centres, follicular dendritic cell networks and high endothelial venules, which are defining qualities of peripheral lymphoid organs. Accordingly, ELS can support local antigen-specific responses to self-antigens, alloantigens, pathogens and tumours. ELS often correlate with severe disease progression in autoimmune conditions, while tumour-associated ELS are associated with enhanced anti-tumour immunity and a favourable prognosis in cancer. Here, we discuss emerging roles for IL-6 family cytokines as regulators of ELS development, maintenance and activity and consider how modulation of these activities has the potential to aid the successful treatment of autoimmune conditions and cancers where ELS feature.

Generation of a Half-Life Extended Anti-CD19 BiTE® Antibody Construct Compatible with Once-Weekly Dosing for Treatment of CD19-Positive Malignancies

CD19 is an immunoglobulin family member expressed ubiquitously on B cell lineage cells, from the pre-B cell to the mature B cell stage, until downregulation during terminal differentiation into plasma cells. CD19 is important for B cell activation, maturation and proliferation, and is widely expressed on the majority of B cell neoplasms.The T cell engaging bispecific antibody construct (BiTE®) blinatumomab, which targets CD19, is approved for the treatment of relapsed or refractory B cell precursor acute lymphoblastic leukemia in adults and children in the US and has shown great promise for treating other CD19-positive hematological malignancies. The short serum half-life of blinatumomab necessitates administration by continuous IV infusion to maintain therapeutic serum concentrations. To extend the half-life and allow for a more convenient administration, a next generation BiTE® antibody construct designated CD19 HLE BiTE® has been generated. The CD19 HLE BiTE® comprises a new CD19- and CD3-targeting tandem single-chain Fv antibody fused to an Fc domain.The biological properties of CD19 HLE BiTE® were evaluated in vitro and in vivo . CD19 HLE BiTE® binds with high affinity to both human and non-human primate (NHP) CD19 as well as CD3. In vitro experiments demonstrated that CD19 HLE BiTE® can recruit and activate human and NHP T cells, mediating redirected lysis of CD19-expressing cells at half-maximal effective concentrations in the low picomolar range. The fusion to an Fc domain resulted in a serum half-life of 210 hours following a single intravenous administration of a 5 µg/kg dose in NHP. In a repeat-dose study CD19 HLE BiTE® caused robust depletion of circulating B cells, B lineage bone marrow cells, and peripheral lymphoid organ B cells in NHPs, whilst no overt signs of toxicity were observed in clinical and laboratory examinations of the animals.These results demonstrate that CD19 HLE BiTE® effectively eliminated CD19-positive cells in vitro and in vivo, and may be suitable for once weekly dosing in patients with CD19-positive malignancies. DisclosuresLorenczewski:Amgen: Employment, Equity Ownership. Friedrich:Amgen Research (Munich) GmbH: Employment, Equity Ownership. Kischel:AMGEN: Employment. Dahlhoff:Amgen Research (Munich): Employment, Equity Ownership. Anlahr:Amgen: Employment, Equity Ownership. Balazs:Amgen Inc.: Employment, Equity Ownership. Rock:Amgen, Inc.: Employment, Equity Ownership. Boyle:Amgen: Employment. Goldstein:Amgen: Employment. Coxon:Amgen, Inc.: Employment. Chapman-Arvedson:Amgen, Inc.: Employment, Equity Ownership.

The Deubiquitinase Activity of CYLD Is Required for Maturation of B Cells

B cell development is a tightly controlled process leading to the generation of mature B cells. A number of genes and pathways, as well as stimuli from the microenvironment play an important role in the maturation process, which in the adult begins in the bone marrow, where progenitor cells reside, and is completed in the peripheral lymphoid organs. Perturbation of this process can have severe effects on the homeostasis of B cells, leading to lymphoproliferative or lymphocytopenic conditions.CYLD is a functional deubiquitinase, hydrolysing K63-linked ubiquitin chains from a variety of substrates. CYLD regulates many cellular pathways, important to cell survival and apoptosis, including NF- κ B, through deubiquitination of key molecules and has been implicated in several solid and haematological tumours. Previous studies on the effect of CYLD ablation on B cells using conventional knock-out animal models lead to varying results, ranging from B cell hyperplasia and enlargement of the lymphoid organs (J Biol Chem. 2007 May 25;282(21):15884-93) to no effect (J Clin Invest. 2006 Nov;116(11):3042-9). On the other hand, targeted expression of a shorter splice variant of CYLD, which retains its catalytic domain, but lacks binding sites for interacting proteins, in place of the full-length protein, led to a marked expansion of the mature B lymphocytes compartment (J Exp Med. 2007 Oct 29;204(11):2615-27) and promoted the development of a human B-Chronic Lymphocytic Leukemia-like syndrome in mice (Leukemia. 2017 Jun 1. doi: 10.1038/leu.2017.168).To better understand the role of CYLD in B cell development, we generated transgenic mice with targeted disruption of the catalytically active form of CYLD in B cells. To this end we crossed mice harbouring the floxed CYLD gene (CYLDflx), to mice expressing the Cre recombinase under the control of the Mb1(CD79a) or the CD19 promoter. Mb1CreCYLDflx/flx and CD19CreCYLDflx/flx mice, ranging between 4 and 12 weeks of age were compared to age and sex matched CYLDflx/flx control animals.Mb1CreCYLDflx/flx mice displayed a marked reduction in spleen size and cellularity, compared to their control (CYLDflx/flx) littermates and histopathology findings indicate differences in the architecture and organization of secondary follicles. Cytometric analysis of peripheral blood showed a pronounced decrease of CD19+ cells in the peripheral blood (on average 33.19% of total lymphocytes vs 0.97%, n=3, t-test, P< 0.001) and the spleen (on average 43.88% of total lymphocytes vs 16.0%, n=3 animals, t-test, P<0.01) of Mb1CreCYLDflx/flx compared to control (CYLDflx/flx) mice. In the bone marrow, the percentage of immature (CD19+/CD25+/IgM+/c-kit-) B cells was elevated in Mb1CreCYLDflx/flx mice, compared to CYLDflx/flx mice (on average 11.52% of lymphocytes vs 22.57%, n=3, t-test, P<0.01), whereas the percentage of mature (CD19+/CD25-/IgM+/c-kit-) B cells was reduced (on average 28.67% of lymphocytes, vs 8.28%, n=3, t-test, P<0.01). Similar results were obtained with CD19CreCYLDflx/flx mice.Our data imply a crucial role for the deubiquitinase activity of CYLD in the maturation of B cells, since its cell-specific ablation in B cells leads to a severe impairment of their maturation. Further studies to elucidate the mechanism governing CYLD function in B cell maturation and its potential use as a target for therapeutic intervention in Chronic Lymphocytic Leukemia are underway.The research leading to these results has received funding from the Marie Skłodowska-Curie actions - IF 2015 of the European Union's Horizon 2020 Programme (Project ID: 708041). DisclosuresGhia:Roche: Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen Pharmaceuticals: Honoraria, Research Funding.

Early Nutrition with Different Diets Composition versus Fasting on Immunity-Related Gene Expression and Histomorphology of Digestive and Lymphoid Organs of Layer-Type Chicks.

Simple SummaryWith the continuous improvement in the progress of poultry industry, a better understanding of the avian immune system is necessary. A prolonged holding period (36–72 h), along with a delay in access to feed and/or water post-hatching, has a negative influence on performance, intestinal histomorphology, and the immune system development of chicks. Therefore, the present study aimed to investigate the effect of early feeding with different diet composition or delayed feeding during the first 72 h of chick’s life on the expression of immunity-related genes and histomorphology of digestive and lymphoid organs of layer-type chicks. Early nutrition post-hatching had no negative effect on the development of the lymphoid and digestive organs in chicks. Histomorphological examination revealed an increase in cortex and cortex:medulla of thymus and bursa in the early fed groups compared to the fasted ones, with resultant impacts on the primary lymphoid organs. Higher germinal center areas and white pulp of the spleen were recorded in the early fed chicks, implying augmented proliferation and maturation of B cells in the secondary lymphoid organs. In the liver, a strong positive reaction to Best’s carmine stain in the early fed groups, indicating that the liver of these chicks had numerous glycogen granules in the cytoplasm of hepatocytes. The expression levels of splenic-immunity related genes were up-regulated in most of the early fed chicks at 14 day of age. Our findings suggested that early feeding post-hatch can modify the splenic-immunity related genes and modulate the histomorphology of the digestive (liver and proventriculus) and lymphoid organ in layer-type chicks during the early life post-hatching.Early feeding post-hatching (EFPH) can impact the immune response and modify the immunity-related gene expression. Therefore, we aimed to examine the effects of EFPH with different diets composition versus fasting during the first 72 h of chick’s life on the histomorphological structures of the liver, proventriculus, central and peripheral lymphoid organs, and immunity-related genes in layer-type chicks during the brooding period. A total of 400 chicks were randomly allotted into 4 groups with 4 replicates each. The experimental groups during the first 72 h of life were: feed and water deprivation (control, T1), feeding a starter layer diet (20% CP and 11.84 MJ/kg ME, T2), feeding a starter layer diet contained 3% molasses in its composition (20% CP and 11.81 MJ/kg ME; T3), and feeding a starter broiler diet (23% CP and 12.68 MJ/kg ME, T4). After the first 72 h of chick’s life, all chicks were fed ad libitum the T2 diet. EFPH had no negative effect on the development of the lymphoid or digestive organs in chicks. Greater relative weights of the spleen and bursa of Fabricius (p < 0.05) were observed in the early fed chicks compared to control at day 14 of age. Histomorphological examination revealed an increase (p < 0.05) in thymus cortex and cortex:medulla in the T3 and T4 groups compared to the fasted ones at day 28 of age. Pelicae height, follicular width, cortex, and cortex:medulla of bursa were improved (p < 0.01) in the fed groups compared to fasted chicks, with resultant influences on the primary lymphoid organs. Compared to control, higher germinal center areas and white pulp of the spleen (p < 0.05) were recorded in the early fed chicks, implying augmented proliferation and maturation of B cells in the secondary lymphoid organs. In the liver, a strong positive reaction to Best’s carmine stain in the early fed groups, indicating that the liver of these chicks had numerous glycogen granules or greater glycogen density in the cytoplasm of hepatocytes. There was a significant enhancement in the proventriculus mucosal and gland thickness, as well as fold height (p < 0.05) in the early fed chicks. The expression levels of splenic Toll-like receptor 2, interleukin 4, tumor necrosis factor α, and interferon gamma were up-regulated (p < 0.01) in most of the early fed chicks (T2, T3, and T4) compared to fasted ones at 14 day of age. In conclusion, EFPH could modify the splenic-immunity related genes and modulate the histomorphology of the digestive (liver and proventriculus) and lymphoid organs in layer-type chicks during the brooding period.

Stroke affects intestinal immune cell trafficking to the central nervous system

Stroke is an acute neurological disease with a strong inflammatory component that can be regulated by the intestinal microbiota and intestinal immune cells. Although stroke has been shown to alter immune cell populations in the gut, the dynamics of cell trafficking have not been elucidated. To study the trafficking of gut-derived immune cells after stroke, we used mice expressing the photoconvertible protein Kikume Green-Red, which turns form green to red when exposed to violet light. Mice underwent laparotomy and the small intestine was exposed to violet laser light. Immune cells were isolated from the small intestine immediately after photoconversion and 2 days later. Percentage of immune cells (CD45+KikR+) that expressed the red variant of the protein (KikR) was higher immediately after photoconversion than 2 days later, indicating cell egress from the small intestine. To investigate whether intestinal immune cells traffic to the periphery and/or the central nervous system (CNS) after stroke, we analyzed KikR+ immune cells (2 days after photoconversion) in peripheral lymphoid organs, meninges and brain, 3 and 14 days after transient occlusion of the middle cerebral artery (tMCAo) or sham-surgery. Although migration was observed in naïve and sham animals, stroke induced a higher mobilization of gut KikR+ immune cells, especially at 3 days after stroke, to all the organs analyzed. Notably, we detected a significant migration of CD45hi immune cells from the gut to the brain and meninges at 3 days after stroke. Comparison of cell trafficking between organs revealed a significant preference of intestinal CD11c+ cells to migrate from the small intestine to brain and meninges after stroke. We conclude that stroke increases immune cell trafficking from the small intestine to peripheral lymphoid organs and the CNS where they might contribute to post-stroke inflammation.

Visualization of leukemic B cell clonal dynamics during therapy using tSNE.

Abstract Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of CD19+ CD5+ clonal B lymphocytes in the blood, bone marrow, and peripheral lymphoid organs. Many patients with CLL never receive treatment for the leukemia and therapy is typically only initiated upon progression of disease-related clinical complications. Treatment options for progressing patients range from chemoimmunotherapy (CIT) to small molecule inhibitors that target pro-survival signaling pathways in leukemic B cells, such as the BTK inhibitor ibrutinib. Although therapy regimens have improved, there is still no cure for CLL, in part due to clonal evolution of the leukemic B cell. The goal of this study is to document the clonal dynamics of CLL B cells at baseline and at response evaluation(s) for alterations in clonal architecture and expression of cell surface markers associated with therapy resistance using the single cell flow cytometry analysis tool, t-distributed stochastic neighbor embedding (t-SNE). Biobanked peripheral blood mononuclear cells were obtained from patients that underwent frontline CIT or ibrutinib, or secondary ibrutinib therapy. Fourteen parameter flow cytometry was performed and subjected to tSNE analysis to document CLL B cell clonal architecture and evolution in patients undergoing the various therapies. Profound differences in treatment responses and leukemic cell clonal dynamics were observed which may inform the discovery of novel biomarkers associated with therapy resistance.

Dynamic changes to tissue-resident immunity after MHC-matched and MHC-mismatched solid organ transplantation.

The heterogeneous pool of tissue-resident lymphocytes in solid organs mediates infection responses and supports tissue integrity and repair. Their vital functions in normal physiology suggest an important role in solid organ transplantation; however, their detailed examination in this context has not been performed. Here, we report the fate of multiple lymphocyte subsets, including T, B, and innate lymphoid cells, after murine liver and heart transplantation. In major histocompatibility complex (MHC)-matched transplantation, donor lymphocytes are retained in liver grafts and peripheral lymphoid organs of heart and liver transplant recipients. In MHC-mismatched transplantation, increased infiltration of the graft by recipient cells and depletion of donor lymphocytes occur, which can be prevented by removal of recipient T and B cells. Recipient lymphocytes fail to recreate the native organs' phenotypically diverse tissue-resident lymphocyte composition, even in MHC-matched models. These post-transplant changes may leave grafts vulnerable to infection and impair long-term graft function.

Microglial Nox2 Plays a Key Role in the Pathogenesis of Experimental Autoimmune Encephalomyelitis.

While oxidative stress has been linked to multiple sclerosis (MS), the role of superoxide-producing phagocyte NADPH oxidase (Nox2) in central nervous system (CNS) pathogenesis remains unclear. This study investigates the impact of Nox2 gene ablation on pro- and anti-inflammatory cytokine and chemokine production in a mouse experimental autoimmune encephalomyelitis (EAE) model. Nox2 deficiency attenuates EAE-induced neural damage and reduces disease severity, pathogenic immune cells infiltration, demyelination, and oxidative stress in the CNS. The number of autoreactive T cells, myeloid cells, and activated microglia, as well as the production of cytokines and chemokines, including GM-CSF, IFNγ, TNFα, IL-6, IL-10, IL-17A, CCL2, CCL5, and CXCL10, were much lower in the Nox2−/− CNS tissues but remained unaltered in the peripheral lymphoid organs. RNA-seq profiling of microglial transcriptome identified a panel of Nox2 dependent proinflammatory genes: Pf4, Tnfrsf9, Tnfsf12, Tnfsf13, Ccl7, Cxcl3, and Cxcl9. Furthermore, gene ontology and pathway enrichment analyses revealed that microglial Nox2 plays a regulatory role in multiple pathways known to be important for MS/EAE pathogenesis, including STAT3, glutathione, leukotriene biosynthesis, IL-8, HMGB1, NRF2, systemic lupus erythematosus in B cells, and T cell exhaustion signaling. Taken together, our results provide new insights into the critical functions performed by microglial Nox2 during the EAE pathogenesis, suggesting that Nox2 inhibition may represent an important therapeutic target for MS.

Nanoemulsions Target to Ectopic Lymphoids in Inflamed Joints to Restore Immune Tolerance in Rheumatoid Arthritis.

Inducing immune tolerance through repeated administration of self-antigens is a promising strategy for treating rheumatoid arthritis (RA), and current research indicates that coadministration of immunomodulators can further orchestrate the tolerogenic response. However, most of the clinical trials based on tolerance induction have negligible therapeutic effects. Peripheral lymphoid organs play critical roles in immunotherapy. Here, we design an engineered nanoemulsion for targeted codelivery of self-antigens and an immunomodulator to ectopic lymphoid structures (ELSs) in inflamed joints of RA. Namely, a citrullinated multiepitope self-antigen (CitP) and rapamycin are incorporated into the nanoemulsions (NEs@CitP/Rapa), which are fabricated by a facial method using commercialized pharmaceutical excipients. After intravenous administration, the nanoemulsion shows satisfactory accumulation in the inflamed paws and provides enhanced anti-inflammatory effect in various experimental murine models of RA. Our study provides a promising targeting strategy to induce immune tolerance for the treatment of RA.

CD5 levels reveal distinct basal T-cell receptor signals in T cells from non-obese diabetic mice.

Type 1 diabetes in non-obese diabetic (NOD) mice occurs when autoreactive T cells eliminate insulin producing pancreatic β cells. While extensively studied in T-cell receptor (TCR) transgenic mice, the contribution of alterations in thymic selection to the polyclonal T-cell pool in NOD mice is not yet resolved. The magnitude of signals downstream of TCR engagement with self-peptide directs the development of a functional T-cell pool, in part by ensuring tolerance to self. TCR interactions with self-peptide are also necessary for T-cell homeostasis in the peripheral lymphoid organs. To identify differences in TCR signal strength that accompany thymic selection and peripheral T-cell maintenance, we compared CD5 levels, a marker of basal TCR signal strength, on immature and mature T cells from autoimmune diabetes-prone NOD and -resistant B6 mice. The data suggest that there is no preferential selection of NOD thymocytes that perceive stronger TCR signals from self-peptide engagement. Instead, NOD mice have an MHC-dependent increase in CD4+ thymocytes and mature T cells that express lower levels of CD5. In contrast, T cell-intrinsic mechanisms lead to higher levels of CD5 on peripheral CD8+ T cells from NOD relative to B6 mice, suggesting that peripheral CD8+ T cells with higher basal TCR signals may have survival advantages in NOD mice. These differences in the T-cell pool in NOD mice may contribute to the development or progression of autoimmune diabetes.

Epinephrine Production in Th17 Cells and Experimental Autoimmune Encephalitis.

Epinephrine is a hormone secreted primarily by medullary cells of the adrenal glands which regulates permeability of blood–brain barrier (BBB). Recent studies showed signaling by epinephrine/epinephrine receptor in T cells is involved in autoimmune diseases. Nevertheless, the production of epinephrine by T cells and its pathogenic function in T cells are not well investigated. Our results show that phenylethanol N-methyltransferase (PNMT), a rate-limiting enzyme of epinephrine synthesis, is specifically expressed in vitro in differentiated TH17 cells and in tissue-resident TH17 cells. Indeed, expression levels of enzymes involved in epinephrine production are higher in TH17 cells from animals after EAE induction. The induction of PNMT was not observed in other effector T cell subsets or regulatory T cells. Epinephrine producing TH17 cells exhibit co-expression of GM-CSF, suggesting they are pathogenic TH17 cells. To delineate the function of epinephrine-production in TH17 cells, we generated a TH17-specific knockout of tyrosine hydroxylase (Th) by breeding a Th-flox and a ROR-gt-CRE mouse (Th-CKO). Th-CKO mice are developmentally normal with an equivalent T lymphocyte number in peripheral lymphoid organs. Th-CKO mice also show an equivalent number of TH17 cells in vivo and following in vitro differentiation. To test whether epinephrine-producing TH17 cells are key for breaching the BBB, migration of T cells through mouse brain endothelial cells was investigated in vitro. Both epi+ wild-type and epi- TH17 cells migrate through an endothelial cell barrier. Mice were immunized with MOG peptide to induce experimental autoimmune encephalitis (EAE) and disease progression was monitored. Although there is a reduced infiltration of CD4+ T cells in Th-CKO mice, no difference in clinical score was observed between Th-CKO and wild-type control mice. Increased neutrophils were observed in the central nervous system of Th-CKO mice, suggesting an alternative pathway to EAE progression in the absence of TH17 derived epinephrine.

MiRNA-467b inhibits Th17 differentiation by targeting eIF4E in experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE) are neuroinflammatory autoimmune diseases characterized by the axonal loss, demyelination, and neurodegeneration of the central nervous system. Overactivation of CD4+ T cells, especially the migration of the Th1 and Th17 subsets into the central nervous system (CNS), leads to the secretion of inflammatory mediators and destruction of the contact between neurons and activated macrophages, which can then result in a series of neurocognitive and motor deficits. In this study, we intended to explore the role of miRNA-467b in regulating Th cell development in EAE. We found that the level of miRNA-467b was decreased and eukaryotic initiation factor 4 F (eIF4E) was increased in lymph nodes and the CNS at EAE peak. eIF4E was confirmed as the direct target of miRNA467b. Overexpression of miRNA-467b could suppress a percentage of CD4+ IL-17+ cells in EAE CD4 + T cells in vitro. In addition, we also identified miRNA-467b, which could suppress Th17 cell differentiation by targeting eIF4E in vitro. Furthermore, injecting miRNA-467b mimics into the caudal vein of EAE mice contributed to less inflammation in the peripheral lymphoid organs and CNS and alleviated disease severity. Taken together, our findings imply that miRNA-467b inhibits the differentiation and function of Th17 cells by targeting eIF4E, thereby alleviating EAE.

Eomes Impedes Durable Response to Tumor Immunotherapy by Inhibiting Stemness, Tissue Residency, and Promoting the Dysfunctional State of Intratumoral CD8+ T Cells.

Sustaining efficacious T cell-mediated antitumor immune responses in the tumor tissues is the key to the success of cancer immunotherapy. Current strategies leverage altering the signals T cells sense in the tumor microenvironment (TME). Checkpoint inhibitor-based approaches block inhibitory signals such as PD-1 whereas cytokine-based therapies increase the level of immune-stimulatory cytokines such as IL-2. Besides extrinsic signals, the genetic circuit within T cells also participates in determining the nature and trajectory of antitumor immune responses. Here, we showed that efficacy of the IL33-based tumor immunotherapy was greatly enhanced in mice with T cell-specific Eomes deficiency. Mechanistically, we demonstrated that Eomes deficient mice had diminished proportions of exhausted/dysfunctional CD8+ T cells but increased percentages of tissue resident and stem-like CD8+ T cells in the TME. In addition, the IFNγ+TCF1+ CD8+ T cell subset was markedly increased in the Eomes deficient mice. We further demonstrated that Eomes bound directly to the transcription regulatory regions of exhaustion and tissue residency genes. In contrast to its role in inhibiting T cell immune responses at the tumor site, Eomes promoted generation of central memory T cells in the peripheral lymphoid system and memory recall responses against tumor growth at a distal tissue site. Finally, we showed that Eomes deficiency in T cells also resulted in increased efficacy of PD-1-blockade tumor immunotherapy. In all, our study indicates that Eomes plays a critical role in restricting prolonged T cell-mediated antitumor immune responses in the TME whereas promoting adaptive immunity in peripheral lymphoid organs.

Activation of epigenetic regulator KDM6B by Salmonella Typhimurium enables chronic infections

ABSTRACT Non-typhoidal Salmonella (NTS) infections result in self limiting gastroenteritis except in rare cases wherein manifestations of chronic infections can occur. Strategies employed by Salmonella to thrive in hostile environments of host during chronic infections are complex and multifaceted. In chronic state, a coordinated action of bacterial effectors allows reprogramming of macrophages to M2 subtype and thereby creating a permissible replicative niche. The mechanistic details of these processes are not fully known. In the current study we identified, histone H3-lysine 27 trimethylation (H3K27me3)-specific demethylase, KDM6B to be upregulated in both cell culture and in murine model of Salmonella infection. KDM6B recruitment upon infection exhibited an associated loss of overall H3K27me3 in host cells and was Salmonella SPI1 effectors coordinated. ChIP-qRT-PCR array analysis revealed several new gene promoter targets of KDM6B demethylase activity including PPARδ, a crucial regulator of fatty acid oxidation pathway and Salmonella-persistent infections. Furthermore, pharmacological inhibition of KDM6B demethylase activity with GSKJ4 in chronic Salmonella infection mice model led to a significant reduction in pathogen load and M2 macrophage polarization in peripheral lymphoid organs. The following work thus reveals Salmonella effector-mediated epigenetic reprogramming of macrophages responsible for its long-term survival and chronic carriage.

Cytomorphological study of lymph node lesions

Lymph nodes are important components of peripheral or secondary lymphoid organs which play a huge role in immune response. To study cytomorphological features and incidence of various lymph node lesions in patients ≤18 years. The data has taken from 100 patients of ≤18 years having lymph node lesion presented at central clinical laboratory for Fine Needle Aspiration cytology examination. FNAC was done in all cases &amp; correlated with their clinical data. Interpretation of their cytology examination is showing that in our tertiary care centre most common lymph node lesion in patient ≤18 year is granulomatous lymphadenitis(44%) followed by reactive lymphadenitis (37%), Acute inflammation(06%), Abscess formation (05%), Cystic lesion (03%), and Leukemic infiltration (02%). Most affected age is 6 to 10 years. Granulomatous &amp; Reactive lymphadenitis are common causes of lymphadenitisin ≤18 years age group. Among this study 6-10 years are more affected age group. These result can be obtain by Fine Needle Aspiration cytology examination.

Platelet-Targeted Gene Therapy Induces Robust Immune Tolerance Even in a Primed Model Via Peripheral Clonal Deletion of CD4 and CD8 T Cells and Expansion of Treg Cells

Our previous studies have demonstrated that platelet-specific gene transfer under control of the αIIb promoter (2b) results in effective immune tolerance induction to FVIII and FIX as well as the non-coagulant protein ovalbumin (OVA) in the unprimed model. Here we explored how the reactivity of immune responses affects the efficacy of transgene expression and the potential immune tolerance mechanisms in platelet-specific gene transfer in the primed model. We used OVA as a surrogate protein for this study. Recipient wild-type (WT) CD45.1 mice were primed with OVA protein. Platelet-OVA expression was introduced by 2bOVA lentivirus transduction of Sca-1+ cells from either WT/CD45.2 or OTII/CD45.2 donors followed by transplantation into OVA-primed WT/CD45.1 recipients preconditioned with 6.6Gy irradiation. We found that pre-existing high-reactive immune responses devastate platelet-OVA expression in recipients in both the WT/WT and OTII/WT models. Using the WT/WT mouse model, 6 of 7 2bOVA-transduced recipients had sustained platelet-OVA expression with levels ranging from 4.53-8.84 ng/108 platelets. Anti-OVA total IgG titers declined with time in 2bOVA-transduced OVA-primed recipients even when rechallenged with OVA. In contrast, recall memory immune responses were elicited in 2bGFP and untransduced transplanted controls. Furthermore, full-thickness tail skin grafts from CAG-OVATg mice were successfully engrafted onto 2bOVA-transduced recipients and survived throughout the remaining lifetimes of the animals. In contrast, skin grafts were completely rejected in control 2bGFP-transduced and untransduced transplanted recipients. To ensure that the immune system was not inactive in 2bOVA-transduced recipients, animals were immunized with unrelated antigen recombinant human FVIII (rhF8) using a protocol known to induce anti-F8 immune responses even in WT mice. All 2bOVA-transduced recipients developed anti-F8 inhibitory antibodies after rhF8 immunization with no differences between the 2bOVA group and the 2bGFP and untransduced control groups. Using the OVA-specific CD4 TCR transgenic model (OTII/WT), we showed that sustained platelet-OVA expression was achieved in 90% of 2bOVA-transduced recipients. OVA-specific CD4 T cells were deleted and Treg cells were expanded in peripheral lymphoid organs in 2bOVA-transduced OVA-primed recipients. The levels of platelet-OVA expression negatively correlates with the percentages of OVA-specific CD4 T cells, but positively correlates with Treg cells. Immune tolerance was also achieved in the OTII/WT model even though all donor-derived CD4 T cells are OVA-specific. However, our studies showed that high-reactive immune responses could influence the neoprotein expression in platelet-targeted gene therapy. Using the OVA-specific CD8 TCR transgenic model (OTI/WT), in which all donor-derived CD8 T cells are OVA-specific, we found that low levels of platelet-OVA expression were obtained at week 5 after transplantation (0.72±0.65 ng/108 platelets) and then dropped to barely detectable at subsequent time points. Flow cytometry analysis showed that there were 33.9±12.9% platelets positive with GFP in 2bGFP LV-transduced recipients, demonstrating that high transduction efficiency and successful transplantation were achieved. Of note, OVA-specific CD8 T cells in the 2bOVA group were 48% lower than in the 2bGFP control group, demonstrating that antigen-specific CD8 T cells were partially deleted in the OTI/WT model after platelet-targeted OVA gene transfer. Interestingly, we found that the percentage of the antigen-specific CD8+Foxp3+ cells in the 2bOVA group was significantly higher than in the 2bGFP group (0.19±0.14% vs. 0.05±0.01%, respectively). These results suggest that there is a counterpace process between immune reaction and immune tolerance after platelet-targeted gene therapy. In conclusion, our studies demonstrate that platelet-targeted gene therapy can induce antigen-specific immune tolerance even when the immune response has been mounted via peripheral clonal deletion of antigen-specific CD4 and CD8 T cells and expansion of Tregs, suggesting that platelet-targeted gene therapy is a promising approach to induce immune tolerance for treatment of diseases with undesired immune responses or even with pre-existing immune responses, such as hemophilia A with inhibitors or autoimmune diseases. Disclosures No relevant conflicts of interest to declare.

Differential Use of Rap1 Effectors for Integrin Activation in Platelets and Lymphocytes

Rap1 is a major convergence point of the platelet and lymphocyte signaling pathways that result in talin1 binding to the integrin β-cytoplasmic domain and consequent integrin activation, effective hemostasis and immune functions. The nature of the connection between Rap1 and talin1 in integrin activation is an important remaining gap in our understanding of this process. Deletion of RIAM in T cells partially suppressed αLβ2 and α4β7 integrin activation but did not block activation of α4β1. In sharp contrast, deletion of both Rap1a and Rap1b isoforms or deletion of talin1 profoundly suppressed activation of α4β1 in addition to the other two integrins. The loss of homing of T cells to peripheral lymphoid organs was correlated with the loss of integrin activation in these mutant T cells. We recently identified two Rap1 binding sites in talin1 F0 and F1 domains and generated mice bearing point mutations, which block Rap1 binding to both talin1 F0 and F1 domains (R35E,R118E). In platelets, which lack endogenous RIAM, a talin1 (R35E,R118E) mutation suppresses activation of integrin αIIbβ3 and platelet aggregation to a similar extent to that observed in Rap1a,b null platelets. In contrast, talin1 (R35E,R118E)-expressing T cells manifest only partial loss of integrin activation, whereas RIAM null T cells expressing talin1 (R35E,R118E) exhibit a much more profound defect. Importantly, overexpression of RIAM can completely rescue the integrin activation defect in talin1 (R35E,R118E)-expressing T cells indicating that Rap1 binding to RIAM and talin1 are partially redundant in T cells. These findings reveal that although both Rap1 and talin1 are essential for integrin action in blood cells, the connections between them vary in different blood cells and that the final steps in integrin activation and blood cell function can be manipulated in a cell-type specific manner. Disclosures No relevant conflicts of interest to declare.