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T cells are present in early stages of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and play a major role in disease outcome and long-lasting immunity. Nasal administration of a fully human anti-CD3 monoclonal antibody (Foralumab) reduced lung inflammation as well as serum IL-6 and C-reactive protein in moderate cases of COVID-19. Using serum proteomics and RNA-sequencing, we investigated the immune changes in patients treated with nasal Foralumab. In a randomized trial, mild to moderate COVID-19 outpatients received nasal Foralumab (100 μg/d) given for 10 consecutive days and were compared to patients that did not receive Foralumab. We found that naïve-like T cells were increased in Foralumab-treated subjects and NGK7 + effector T cells were reduced. CCL5, IL32, CST7, GZMH, GZMB, GZMA, PRF1 , and CCL4 gene expression were downregulated in T cells and CASP1 was downregulated in T cells, monocytes, and B cells in subjects treated with Foralumab. In addition to the downregulation of effector features, an increase in TGFB1 gene expression in cell types with known effector function was observed in Foralumab-treated subjects. We also found increased expression of GTP-binding gene GIMAP7 in subjects treated with Foralumab. Rho/ROCK1, a downstream pathway of GTPases signaling was downregulated in Foralumab-treated individuals. TGFB1, GIMAP7 , and NKG7 transcriptomic changes observed in Foralumab-treated COVID-19 subjects were also observed in healthy volunteers, MS subjects, and mice treated with nasal anti-CD3. Our findings demonstrate that nasal Foralumab modulates the inflammatory response in COVID-19 and provides a novel avenue to treat the disease.

Background Gamma-delta (γδ) T cells are a major cell population in the intestinal mucosa and are key mediators of mucosal tolerance and microbiota composition. Little is known about the mechanisms by which intestinal γδ T cells interact with the gut microbiota to maintain tolerance. Results We found that antibiotic treatment impaired oral tolerance and depleted intestinal γδ T cells, suggesting that the gut microbiota is necessary to maintain γδ T cells. We also found that mice deficient for γδ T cells (γδ−/−) had an altered microbiota composition that led to small intestine (SI) immune dysregulation and impaired tolerance. Accordingly, colonizing WT mice with γδ−/− microbiota resulted in SI immune dysregulation and loss of tolerance whereas colonizing γδ−/− mice with WT microbiota normalized mucosal immune responses and restored mucosal tolerance. Moreover, we found that SI γδ T cells shaped the gut microbiota and regulated intestinal homeostasis by secreting the fecal micro-RNA let-7f. Importantly, oral administration of let-7f to γδ−/− mice rescued mucosal tolerance by promoting the growth of the γδ−/−-microbiota-depleted microbe Ruminococcus gnavus. Conclusions Taken together, we demonstrate that γδ T cell-selected microbiota is necessary and sufficient to promote mucosal tolerance, is mediated in part by γδ T cell secretion of fecal micro-RNAs, and is mechanistically linked to restoration of mucosal immune responses.

Multiple sclerosis is an autoimmune disease that affects the central nervous system. Because of its complexity and the difficulty to treat, searching for immunoregulatory responses that reduce the clinical signs of disease by non-aggressive mechanisms and without adverse effects is a scientific challenge. Herein we propose a protocol of oral tolerance induction that prevented and controlled MOG-induced experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. The genetically modified strain HSP65-producing Lactococcus lactis was orally administered for 5 consecutive days either before or during disease development in mice. Both protocols of feeding HSP65 resulted in significant reduction in the clinical score of EAE. Frequencies of LAP+CD4+Foxp3- regulatory T cells were higher in spleens and inguinal lymph nodes of fed mice. In addition, intravital microscopy showed that adherence of leukocytes to venules in the spinal cord was reduced in orally treated mice. Oral treatment with HSP65-producing L.lactis prevented leukocytes to leave the secondary lymphoid organs, therefore they could not reach the central nervous system. Despite the inhibition of pathological immune response that drive EAE development, activated T cells were at normal frequencies suggesting that oral tolerance did not induce general immunosuppression, but it led to specific control of pathogenic T cells. Our results indicate a novel therapeutic strategy to prevent and control autoimmune diseases such as multiple sclerosis.

Oral tolerance (OT) has classically been defined as the specific suppression of cellular and/or humoral immune responses to an antigen by prior administration of the antigen through the oral route. Multiple mechanisms have been proposed to explain the induction of OT including T cell clonal depletion and anergy when high doses of antigens are fed, and regulatory T (Treg) cell generation following oral administration of low and repeated doses of antigens. Oral antigen administration suppresses the immune response in several animal models of autoimmune disease, including experimental autoimmune encephalomyelitis, uveitis, thyroiditis, myasthenia, arthritis and diabetes, but also non-autoimmune inflammatory conditions such as asthma, atherosclerosis, graft rejection, allergy and stroke. However, human trials have given mixed results and a great deal remains to be learned about the mechanisms of OT before it can be successfully applied to people. One of the possible mechanisms relates to the gut microbiota and in this review, we will explore the cellular components involved in the induction of OT and the role of the gut microbiota in contributing to OT development.

Neutrophils were classically described as powerful effectors of acute inflammation, and their main purpose was assumed to be restricted to pathogen killing through production of oxidants. As consequence, neutrophils also may lead to significant collateral damage to the healthy tissues, and after performing these tasks, these leukocytes are supposed to die within tissues. However, there is a growing body of evidence showing that neutrophils also play a pivotal role in the resolution phases of inflammation, because they can modulate tissue environment due to secretion of different kind of cytokines. Drug-induced liver injury (DILI) is a worldwide concern being one of the most prevalent causes of liver transplantation, and is well established that there is an intense neutrophil recruitment into necrotic liver during DILI. However, information if such abundant granulocyte infiltration is also linked to the tissue repairing phase of hepatic injury is still largely elusive. Here, we investigated the dynamics of neutrophil trafficking within blood, bone marrow, and liver during hepatic inflammation, and how changes in their gene expression profile could drive the resolution events during acetaminophen (APAP)-induced liver injury. We found that neutrophils remained viable during longer periods following liver damage, because they avidly patrolled necrotic areas and up-regulated pro-resolutive genes, including Tgfb, Il1r2, and Fpr2. Adoptive transference of “resolutive neutrophils” harvested from livers at 72 h after injury to mice at the initial phases of injury (6 h after APAP) significantly rescued organ injury. Thus, we provide novel insights on the role of neutrophils not only in the injury amplification, but also in the resolution phases of inflammation.

Oral tolerance is defined as the specific suppression of cellular and/or humoral immune responses to an Ag by prior administration of the Ag through the oral route. Although the investigation of oral tolerance has classically involved Ag feeding, we have found that oral administration of anti-CD3 mAb induced tolerance through regulatory T (Treg) cell generation. However, the mechanisms underlying this effect remain unknown. In this study, we show that conventional but not plasmacytoid dendritic cells (DCs) are required for anti-CD3–induced oral tolerance. Moreover, oral anti-CD3 promotes XCL1 secretion by small intestine lamina propria γδ T cells that, in turn, induces tolerogenic XCR1+ DC migration to the mesenteric lymph node, where Treg cells are induced and oral tolerance is established. Consistent with this, TCRδ−/− mice did not develop oral tolerance upon oral administration of anti-CD3. However, XCL1 was not required for oral tolerance induced by fed Ags, indicating that a different mechanism underlies this effect. Accordingly, oral administration of anti-CD3 enhanced oral tolerance induced by fed MOG35–55 peptide, resulting in less severe experimental autoimmune encephalomyelitis, which was associated with decreased inflammatory immune cell infiltration in the CNS and increased Treg cells in the spleen. Thus, Treg cell induction by oral anti-CD3 is a consequence of the cross-talk between γδ T cells and tolerogenic DCs in the gut. Furthermore, anti-CD3 may serve as an adjuvant to enhance oral tolerance to fed Ags.

The intestinal mucosa constitutes an environment of closely regulated immune cells. Dendritic cells (DC) interact with the gut microbiome and antigens and are important in maintaining gut homeostasis. Here, we investigate DC transcriptome, phenotype and function in five anatomical locations of the gut lamina propria (LP) which constitute different antigenic environments. We show that DC from distinct gut LP compartments induce distinct T cell differentiation and cytokine secretion. We also find that PD-L1+ DC in the duodenal LP and XCR1+ DC in the colonic LP comprise distinct tolerogenic DC subsets that are crucial for gut homeostasis. Mice lacking PD-L1+ and XCR1+ DC have a proinflammatory gut milieu associated with an increase in Th1/Th17 cells and a decrease in Treg cells and have exacerbated disease in the models of 5-FU-induced mucositis and DSS-induced colitis. Our findings identify PD-L1+ and XCR1+ DC as region-specific physiologic regulators of intestinal homeostasis. Dendritic cells initiate and regulate adaptive immunity and differ according to gut anatomical location. Here the authors show that DC residing in the upper and lower intestines show differential PD-L1 and XCR1 expression and drive specific T cell responses to prevent gut inflammation.

Conjugated linoleic acid (CLA) has been shown to activate the nuclear receptor PPAR-γ and modulate metabolic and immune functions. Despite the worldwide use of CLA dietary supplementation, strong scientific evidence for its proposed beneficial actions are missing. We found that CLA-supplemented diet reduced mucosal damage and inflammatory infiltrate in the dextran sodium sulfate (DSS)-induced colitis model. Conditional deletion of PPAR-γ in macrophages from mice supplemented with CLA diet resulted in loss of this protective effect of CLA, suggesting a PPAR-γ-dependent mechanism mediated by macrophages. However, CLA supplementation significantly worsened colorectal tumor formation induced by azoxymethane and DSS by inducing macrophage and T-cell-producing TGF-β via PPAR-γ activation. Accordingly, either macrophage-specific deletion of PPAR-γ or in vivo neutralization of latency-associated peptide (LAP, a membrane-bound TGF-β)-expressing cells abrogated the protumorigenic effect of CLA. Thus, the anti-inflammatory properties of CLA are associated with prevention of colitis but also with development of colorectal cancer.

The Spike protein (S protein) is a critical component in the infection of the new coronavirus (SARS-CoV-2). The objective of this work was to evaluate whether peptides from S protein could cause negative impact in the aquatic animals. The aquatic toxicity of SARS-CoV-2 spike protein peptides derivatives has been evaluated in tadpoles (n = 50 tadpoles/5 replicates of 10 animals) from species Physalaemus cuvieri (Leptodactylidae). After synthesis, purification, and characterization of peptides (PSDP2001, PSDP2002, PSDP2003) an aquatic contamination has been simulated with these peptides during 24 hours of exposure in two concentrations (100 and 500 ng/mL). The control group (“C”) was composed of tadpoles kept in polyethylene containers containing de-chlorinated water. Oxidative stress, antioxidant biomarkers and AChE activity were assessed. In both concentrations, PSPD2002 and PSPD2003 increased catalase and superoxide dismutase antioxidants enzymes activities, as well as oxidative stress (nitrite levels, hydrogen peroxide and reactive oxygen species). All three peptides also increased acetylcholinesterase activity in the highest concentration. These peptides showed molecular interactions in silico with acetylcholinesterase and antioxidant enzymes. Aquatic particle contamination of SARS-CoV-2 has cholinesterasic effect in P. cuvieri tadpoles. These findings indicate that the COVID-19 can constitute environmental impact or biological damage potential., Graphical abstract

The Spike protein (S protein) is a critical component in the infection of the new coronavirus (SARS-CoV-2). The objective of this work was to evaluate whether peptides from S protein could cause negative impact in the aquatic animals. The aquatic toxicity of SARS-CoV-2 spike protein peptides derivatives has been evaluated in tadpoles (n = 50 tadpoles / 5 replicates of 10 animals) from species Physalaemus cuvieri (Leptodactylidae). After synthesis, purification, and characterization of peptides (PSDP2001, PSDP2002, PSDP2003) an aquatic contamination has been simulatedwith these peptides during 24 hours of exposure in two concentrations (100 and 500 ng/mL). The control group (“C”) was composed of tadpoles kept in polyethylene containers containing de-chlorinated water. Oxidative stress, antioxidant biomarkers and neurotoxicity activity were assessed. In both concentrations, PSPD2002 and PSPD2003 increased catalase and superoxide dismutase antioxidants enzymes activities, as well as oxidative stress (nitrite levels, hydrogen peroxide and reactive oxygen species). All three peptides also increased acetylcholinesterase activity in the highest concentration. These peptides showed molecular interactions in silico with acetylcholinesterase and antioxidant enzymes. Aquatic particle contamination of SARS-CoV-2 has neurotoxics effects in P. cuvieri tadpoles. These findings indicate that the COVID-19 can constitute environmental impact or biological damage potential.HIGHLIGHTSSARS-CoV-2 spike protein peptides (PSDP) were synthesized, purified, and characterized by solid phase peptide synthesis.PSDP peptides promoted REDOX imbalance and acute neurotoxicity in tadpoles (Physalaemus cuvieri)In silico studies have shown interactionsbetween peptides and acetylcholinesterase and antioxidant enzymesAquatic particle contamination of SARS-CoV-2 can constitute additional environmental damageGRAPHICAL ABSTRACT

Oral tolerance (OT) plays a critical role in maintaining the gut homeostatic environment. OT is defective in mice lacking microbiota or gamma-delta T cells (γδ-/-). We found that γδ-/- mice have an altered microbiota, including a decrease in Rumincoccus gnavus. Transfer of microbiota from γδ-/- mice to WT mice impaired OT, whereas transfer of WT microbiota or R. gnavus to γδ-/- mice restored OT. Restoration of OT was associated with increased IL-10 production by CX3CR1+ mononuclear phagocytes and Treg cells, and decreased Th17 cells. Fecal micro-RNAs can regulate the microbiota and we found that intestinal γδ T cells produced the miRNA let-7f and that oral administration of let-7f to γδ-/- mice increased R. gnavus and restored OT. Taken together, we demonstrate that the γδ T cell-selected microbiota is necessary and sufficient to promote OT, which is mechanistically linked to γδ T cell secretion of a microbiota-modulating miRNA.

The intestinal mucosa constitutes an environment of closely regulated immune cells. Dendritic cells (DC) interact with the gut microbiome and antigens and are important in maintaining gut homeostasis. Here, we investigate DC transcriptome, phenotype and function in five anatomical locations of the gut lamina propria (LP) which constitute different antigenic environments. We show that DC from distinct gut LP compartments induce distinct T cell differentiation and cytokine secretion. We also find that PD-L1+ DC in the duodenal LP and XCR1+ DC in the colonic LP comprise distinct tolerogenic DC subsets that are crucial for gut homeostasis. Mice lacking PD-L1+ and XCR1+ DC have a proinflammatory gut milieu associated with an increase in Th1/Th17 cells and a decrease in Treg cells and have exacerbated disease in the models of 5-FU-induced mucositis and DSS-induced colitis. Our findings identify PD-L1+ and XCR1+ DC as region-specific physiologic regulators of intestinal homeostasis., Dendritic cells initiate and regulate adaptive immunity and differ according to gut anatomical location. Here the authors show that DC residing in the upper and lower intestines show differential PD-L1 and XCR1 expression and drive specific T cell responses to prevent gut inflammation.

Objectives To investigate putative different outcomes on non-alcoholic fatty liver disease development in mice using fat options regularly used in human nutrition. Methods Male C57BL/6 mice were fed control diet, and four different high fat diets (HFD - 40% calories from fat, Research Diets, USA) for 16 and 30 weeks. High fat diets had different common fat sources, including trans fat, non-trans fat palm oil (Primex-Z®), palm oil alone and corn oil alone. Mice were euthanized and samples were collected for analysis. Results Using an unprecedented combination of in vivo imaging with immunometabolic phenotyping, we revealed that HFD induced a major increase in hepatic lipid droplet deposition in comparison to controls, being significantly higher in Primex-Z® fed mice. All HFDs had similar or less weight gain compared with control mice; however, Primex-Z® ingestion led to a higher increasing in adiposity index (∼90% increase) in comparison to other fat sources. Gene expression of isolated liver immune cells revealed large changes expression of several inflammatory pathways, which were also more elevated in Primex-Z fed mice, including Tnf (∼20-fold), Il1b (∼60-fold) and Tgfb (2.5-fold). Immunophenotyping and in vivo analysis showed that the frequency of hepatic immune cells was also disturbed during different HFD contents, rendering not only Kupffer cell depletion, but also reduced bacterial arresting ability. Conclusion Different fat dietary sources imprint different immune and metabolic impacts in the liver during high fat diet consumption. Our data highlight that Primex-Z® – a novel non-trans fat – is not only able to damage hepatocytes, but also impair liver ability to clear blood-borne infections.

Mammals and microorganisms have evolved a complex and tightly controlled mutual relationship. This interaction grants protection and energy source for the microorganisms, and on the other hand, provides several immunologic, metabolic and physiological advantages for the host. The gastrointestinal tract (GI) harbors the largest bacteria diversity within the body and complex mechanisms control microbiota community under homeostasis. However, once disrupted, microbiota imbalance can lead to overt growth of resident and invasive populations, with potential risk for lethal diseases. In these cases, bacteria might also escape from the intestines and reach different organs through the blood and lymphatic circulation. To control these unwanted conditions, all body tissues are populated with resident macrophages that have the ability to capture and eliminate pathogens, avoiding their dissemination. Here we discuss the different routes for bacterial translocation from the intestinal tract, and how macrophages act in the removal of these microorganisms to prevent systemic infections and restore the homeostasis.

Summary Myeloid suppressor cells promote tumor growth by a variety of mechanisms which are not fully characterized. We identified myeloid cells (MCs) expressing the latency-associated peptide (LAP) of TGF-β on their surface and LAPHi MCs that stimulate Foxp3+ Tregs while inhibiting effector T cell proliferation and function. Blocking TGF-β inhibits the tolerogenic ability of LAPHi MCs. Furthermore, adoptive transfer of LAPHi MCs promotes Treg accumulation and tumor growth in vivo. Conversely, anti-LAP antibody, which reduces LAPHi MCs, slows cancer progression. Single-cell RNA-Seq analysis on tumor-derived immune cells revealed LAPHi dominated cell subsets with distinct immunosuppressive signatures, including those with high levels of MHCII and PD-L1 genes. Analogous to mice, LAP is expressed on myeloid suppressor cells in humans, and these cells are increased in glioma patients. Thus, our results identify a previously unknown function by which LAPHi MCs promote tumor growth and offer therapeutic intervention to target these cells in cancer., Graphical abstract, Highlights • Several myeloid cell subsets express surface LAP • Myeloid cells that express surface LAP possess immunosuppressive properties • LAP expressing myeloid cells induce Tregs and inhibit effector T cell function • LAP expressing myeloid cells promote tumor growth, Immunology; Cancer

International audience; The aim of this study was to investigate the contribution of IL-33/ST2 axis in the onset and progression of acute liver injury using a mice model of drug-induced liver injury (DILI). DILI was induced by overdose administration of acetaminophen (APAP) by oral gavage in wild-type BALB/c, ST2-deficient mice and in different bone marrow chimeras. Neutrophils were depleted by anti-Ly6G and macrophages with clodronate liposomes (CLL). Blood and liver were collected for biochemical, immunologic and genetic analyses. Mice were imaged by confocal intravital microscopy and liver non-parenchymal cells and hepatocytes were isolated for flow cytometry, genetic and immunofluorescence studies. Acetaminophen overdose caused a massive necrosis and accumulation of immune cells within the liver, concomitantly with IL-33 and chemokine release. Liver non-parenchymal cells were the major sensors for IL-33, and amongst them, neutrophils were the major players in amplification of the inflammatory response triggered by IL-33/ST2 signalling pathway. Blockage of IL-33/ST2 axis reduces APAP-mediated organ injury by dampening liver chemokine release and activation of resident and infiltrating liver non-parenchymal cells.

Seizures are due to excessive, synchronous neuronal firing in the brain and are characteristic of epilepsy, the fourth most prevalent neurological disease. We report handling-induced and spontaneous seizures in mice deficient for CD39, a cell-surface ATPase highly expressed on microglial cells. CD39-/- mice with handling-induced seizures had normal input-output curves and paired-pulse ratio measured from hippocampal slices and lacked microgliosis, astrogliosis or overt cell loss in the hippocampus and cortex. As expected, however, the cerebrospinal fluid of CD39-/- mice contained increased levels of ATP and decreased levels of adenosine. To determine if immune activation was involved in seizure progression, we challenged mice with lipopolysaccharide (LPS) and measured the effect on microglia activation and seizure severity. Systemic LPS challenge resulted in increased cortical staining of Iba1/CD68 and gene array data from purified microglia predicted increased expression of interleukin-8, triggering receptor expressed on myeloid cells 1, p38, pattern recognition receptors, death receptor, nuclear factor-κB , complement, acute phase, and interleukin-6 signalling pathways in CD39-/- versus CD39+/+ mice. However, LPS treatment did not affect handling-induced seizures. In addition, microglia-specific CD39 deletion in adult mice was not sufficient to cause seizures, suggesting instead that altered expression of CD39 during development or on non-microglial cells such as vascular endothelial cells may promote the seizure phenotype. In summary, we show a correlation between altered extracellular ATP/adenosine ratio and a previously unreported seizure phenotype in CD39-/- mice. This work provides groundwork for further elucidation of the underlying mechanisms of epilepsy.

Oral administration of Ag induces regulatory T cells that express latent membrane-bound TGF-β (latency-associated peptide [LAP]) and have been shown to play an important role in the induction of oral tolerance. We developed an in vitro model to study modulation of LAP+ on CD4+ T cells. The combination of anti-CD3 mAb, anti-CD28 mAb, and recombinant IL-2 induced expression of LAP on naive CD4+ T cells, independent of Foxp3 or exogenous TGF-β. In vitro generated CD4+LAP+Foxp3− T cells were suppressive in vitro, inhibiting proliferation of naive CD4+ T cells and IL-17A secretion by Th17 cells. Assessing the impact of different cytokines and neutralizing Abs against cytokines, we found that LAP induction was decreased in the presence of IL-6 and IL-21, and to a lesser extent by IL-4 and TNF-α. IL-6 abrogated the in vitro induction of CD4+LAP+ T cells by STAT3-dependent inhibition of Lrrc32 (glycoprotein A repetitions predominant [GARP]), the adapter protein that tethers TGF-β to the membrane. Oral tolerance induction was enhanced in mice lacking expression of IL-6R by CD4+ T cells and by treatment of wild-type mice with neutralizing anti-IL-6 mAb. These results suggest that proinflammatory cytokines interfere with oral tolerance induction and that blocking the IL-6 pathway is a potential strategy for enhancing oral tolerance in the setting of autoimmune and inflammatory diseases.

CD3-specific monoclonal antibody (mAb) treats autoimmune disease in animal models and has shown promise in clinical trials of type 1 diabetes. Whereas intravenous administration of CD3-specific mAb acts primarily by transient depletion of activated effector T cells, oral CD3-specific mAb acts primarily by the induction Tregs. We investigated whether oral CD3-specific mAb inhibits disease in non obese diabetic (NOD) mice that spontaneously develop autoimmune diabetes, closely resembling human type 1 diabetes. We found that oral CD3-specific mAb treatment delayed onset and reduced incidence of diabetes in NOD mice, inducing changes in both effector and regulatory T cell compartments. The therapeutic effect was associated with decreased T cell proliferation, decreased IFNγ and IL-17 production, and increased TGF-β and IL-10 production in vitro. In vivo transfer experiments demonstrated that oral CD3-specific mAb decreased diabetogenicity of effector T cells and increased the function of regulatory T cells. Oral OKT3, a monoclonal antibody specific for human CD3 had equivalent effects in transgenic NOD mice expressing the human CD3 epsilon chain which serves as a preclinical model for testing human CD3-specific mAb. These results suggest that oral CD3-specific mAb has the potential for treating autoimmune diabetes in humans.

Background & Aims Resident macrophages are derived from yolk sac precursors and seed the liver during embryogenesis. Native cells may be replaced by bone marrow precursors during extensive injuries, irradiation, and infections. We investigated the liver populations of myeloid immune cells and their location, as well as the dynamics of phagocyte repopulation after full depletion. The effects on liver function due to the substitution of original phagocytes by bone marrow–derived surrogates were also examined. Methods We collected and analyzed liver tissues from C57BL/6 (control), LysM-EGFP, B6 ACTb-EGFP, CCR2 −/− , CD11c-EYFP, CD11c-EYFP-DTR, germ-free mice, CX3CR1 gfp/gfp , CX3CR1 gpf/wt , and CX3CR1-DTR-EYFP . Liver nonparenchymal cells were immunophenotyped using mass cytometry and gene expression analyses. Kupffer and dendritic cells were depleted from mice by administration of clodronate, and their location and phenotype were examined using intravital microscopy and time-of-flight mass cytometry. Mice were given acetaminophen gavage or intravenous injections of fluorescently labeled Escherichia coli , blood samples were collected and analyzed, and liver function was evaluated. We assessed cytokine profiles of liver tissues using a multiplexed array. Results Using mass cytometry and gene expression analyses, we identified 2 populations of hepatic macrophages and 2 populations of monocytes. We also identified 4 populations of dendritic cells and 1 population of basophils. After selective depletion of liver phagocytes, intravascular myeloid precursors began to differentiate into macrophages and dendritic cells; dendritic cells migrated out of sinusoids, after a delay, via the chemokine CX3CL1. The cell distribution returned to normal in 2 weeks, but the repopulated livers were unable to fully respond to drug-induced injury or clear bacteria for at least 1 month. This defect was associated with increased levels of inflammatory cytokines, and dexamethasone accelerated the repopulation of liver phagocytes. Conclusions In studies of hepatic phagocyte depletion in mice, we found that myeloid precursors can differentiate into liver macrophages and dendritic cells, which each localize to distinct tissue compartments. During replenishment, macrophages acquire the ability to respond appropriately to hepatic injury and to remove bacteria from the blood stream.

Lymph nodes (LNs) are organs spread within the body, where the innate immune responses can connect with the adaptive immunity. In fact, LNs are strategically interposed in the path of the lymphatic vessels, allowing intimate contact of tissue antigens with all resident immune cells in the LN. Thus, understanding the cellular composition, distribution, location and interaction using ex vivo whole LN imaging will add to the knowledge on how the body coordinates local and systemic immune responses. This protocol shows an ex vivo imaging strategy following an in vivo administration of fluorescent-labeled antibodies that allows a very reproducible and easy-to-perform methodology by using conventional confocal microscopes and stock reagents. Through subcutaneous injection of antibodies, it is possible to label different cell populations in draining LNs without affecting tissue structures that can be potentially damaged by a conventional immunofluorescence microscopy technique.

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS). Experimental Autoimmune Encephalomyelitis (EAE) is the most widely used animal model for the study of MS. The Suppressor of Cytokine Signaling (SOCS) 2 protein plays a critical role in regulating the immune responses. The role of SOCS2 during EAE has not been explored. EAE was induced in WT and SOCS2-/- mice using myelin oligodendrocyte glycoprotein (MOG35-55) peptide. Brain and spinal cord were examined during the peak (day 14) and recovery phase (day 28) of the disease. SOCS2 was upregulated in the brain of WT mice at the peak and recovery phase of EAE. The development of the acute phase was slower in onset in SOCS2-/- mice and was associated with reduced number of Th1 (CD3+CD4+IFN-γ+) cells in the spinal cord and brain. However, while in WT mice, maximal clinical EAE score was followed by a progressive recovery; the SOCS2-/- mice were unable to recover from locomotor impairment that occurred during the acute phase. There was a prolonged inflammatory response (increased Th1 and decreased Th2 and T regulatory cells) in the late phase of EAE in the CNS of SOCS2-/- mice. Transplantation of bone marrow cells from SOCS2-/- into irradiated WT mice resulted in higher lethality at the early phase of EAE. Altogether, these results suggest that SOCS2 plays a dual role in the immune response during EAE. It is necessary for damage during the acute phase damage but plays a beneficial role in the recovery stage of the disease.

Leukocytes are a large population of cells spread within most tissues in the body. These cells may be either sessile (called as resident cells) or circulating leukocytes, which travel long journeys inside the vessels during their lifespan. Although production and maturation of these leukocytes in adults primarily occur in the bone marrow, it is well known that this process—called hematopoiesis—started in the embryonic life in different sites, including the yolk sac, placenta, and the liver. In this review, we will discuss how the liver acts as a pivotal site for leukocyte maturation during the embryo phase, and also how the most frequent liver-resident immune cell populations—namely Kupffer cells, dendritic cells, and lymphocytes—play a vital role in both tolerance and inflammatory responses to antigens from food, microbiota, and pathogens.

Previous studies have reported that microglia depletion leads to impairment of synapse formation and these cells rapidly repopulate from CNS progenitors. However, the impact of microglia depletion and repopulation in the long-term state of the CNS environment has not been characterized. Here, we report that acute and synchronous microglia depletion and subsequent repopulation induces gray matter microgliosis, neuronal death in the somatosensory cortex and ataxia-like behavior. We find a type 1 interferon inflammatory signature in degenerating somatosensory cortex from microglia-depleted mice. Transcriptomic and mass cytometry analysis of repopulated microglia demonstrates an interferon regulatory factor 7-driven activation state. Minocycline and anti-IFNAR1 antibody treatment attenuate the CNS type 1 interferon-driven inflammation, restore microglia homeostasis and reduce ataxic behavior. Neither microglia depletion nor repopulation impact neuropathology or T-cell responses during experimental autoimmune encephalomyelitis. Together, we found that acute microglia ablation induces a type 1 interferon activation state of gray matter microglia associated with acute neurodegeneration.

Since their discovery in the early 90s, microRNAs (miRNAs), small non-coding RNAs, have mainly been associated with posttranscriptional regulation of gene expression on a cell-autonomous level. Recent evidence has extended this role by adding inter-species communication to the manifold functional range. In our latest study [Liu S, et al., 2016, Cell Host & Microbe], we identified miRNAs in gut lumen and feces of both mice and humans. We found that intestinal epithelial cells (IEC) and Hopx+ cells were the two main sources of fecal miRNA. Deficiency of IEC-miRNA resulted in gut dysbiosis and WT fecal miRNA transplantation restored the gut microbiota. We investigated potential mechanisms for this effect and found that miRNAs were able to regulate the gut microbiome. By culturing bacteria with miRNAs, we found that host miRNAs were able to enter bacteria, specifically regulate bacterial gene transcripts and affect bacterial growth. Oral administration of synthetic miRNA mimics affected specific bacteria in the gut. Our findings describe a previously unknown pathway by which the gut microbiome is regulated by the host and raises the possibility that miRNAs may be used therapeutically to manipulate the microbiome for the treatment of disease.

Background & Aims The precise determination of non-alcoholic fatty liver disease (NAFLD) onset is challenging. Thus, the initial hepatic responses to fat accumulation, which may be fundamental to our understanding of NAFLD evolution and clinical outcomes, are largely unknown. Herein, we chronologically mapped the immunologic and metabolic changes in the liver during the early stages of fatty liver disease in mice and compared this with human NAFLD samples. Methods Liver biopsies from patients with NAFLD (NAFLD activity score [NAS] 2–3) were collected for gene expression profiling. Mice received a high-fat diet for short periods to mimic initial steatosis and the hepatic immune response was investigated using a combination of confocal intravital imaging, gene expression, cell isolation, flow cytometry and bone marrow transplantation assays. Results We observed major immunologic changes in patients with NAS 2–3 and in mice in the initial stages of NAFLD. In mice, these changes significantly increased mortality rates upon drug-induced liver injury, as well as predisposing mice to bacterial infections. Moreover, deletion of Toll-like receptor 4 in liver cells dampened tolerogenesis, particularly in Kupffer cells, in the initial stages of dietary insult. Conclusion The hepatic immune system acts as a sentinel for early and minor changes in hepatic lipid content, mounting a biphasic response upon dietary insult. Priming of liver immune cells by gut-derived Toll-like receptor 4 ligands plays an important role in liver tolerance in initial phases, but continuous exposure to insults may lead to damage and reduced ability to control infections. Lay summary Fatty liver is a very common form of hepatic disease, leading to millions of cases of cirrhosis every year. Patients are often asymptomatic until becoming very sick. Therefore, it is important that we expand our knowledge of the early stages of disease pathogenesis, to enable early diagnosis. Herein, we show that even in the early stages of fatty liver disease, there are significant alterations in genes involved in the inflammatory response, suggesting that the hepatic immune system is disturbed even following minor and undetectable changes in liver fat content. This could have implications for the diagnosis and clinical management of fatty liver disease., Graphical abstract, Highlights • Hepatic immune response is already altered in liver biopsies from patients with mild NAFLD. • We designed a novel mouse model to mimic mild NAFLD, enabling the chronological mapping of liver changes. • This revealed an increased mortality rate upon secondary liver damage and a window of increased susceptibility to infection. • NAFLD diagnosis may be significantly improved by a more profound investigation of changes in hepatic immunology. • These data could guide customized nutritional and therapeutic interventions at different stages of NAFLD.

Immunotherapy that acts by counteracting the suppressive environment established by the tumor became a very promising approach for the treatment of cancer. Regulatory immune cells promote cancer by suppressing antitumor immune responses, but there are few cell surface molecules that can specifically be targeted to neutralize their function. We characterized a regulatory T-cell population that expresses surface latency-associated peptide (LAP). LAP is an adaptor and regulator of TGF-beta, a potent immunosuppressive cytokine. An increase in LAP+ CD4 T cells has been reported in human cancer, including head and neck and colorectal cancer. To study the regulatory role of LAP+ cells in cancer, we developed a murine monoclonal anti-LAP antibody. We found that treatment with anti-LAP antibody reduces tumor growth and increases survival in various cancer models, including colon carcinoma, glioblastoma and melanoma. Anti-LAP antibody is able to block TGF-beta release from cells expressing LAP and also reduces both the number and suppressive abilities of tumor-associated LAP+ regulatory cells. Anti-LAP antibody treatment triggers a profound peripheral immune response by acting on both innate and adaptive arms of the immune system. A synergistic antitumor effect was observed by combining anti-LAP antibody with dendritic cell vaccination. To study different LAP+ immune cells on a single-cell level, we developed a 19-panel flow cytometry approach. Based on the TCGA data analysis, the expression of LAP-associated genes correlates inversely with patient survival in a number of cancers. In summary, LAP+ immune cells contribute to cancer progression, and targeting these cells for cancer treatment represents a promising immunotherapeutic approach against cancer. Citation Format: Galina Gabriely, Andre da Cunha, Rafael Rezende, Nathaniel Skillin, Brendan Kenyon, Lena Walton, Murugaiyan Gopal, Howard Weiner. The role of LAP positive immune cells in cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A85.

Oral tolerance can be defined as an inhibition of specific immune responsiveness to subsequent parenteral injections of proteins to which an individual or animal has been previously exposed via the oral route. Multiple mechanisms of tolerance are induced by oral-fed antigens, but induction of regulatory CD4 T-cells expressing the transcription factor Foxp3 and the membrane-bound TGF-β stands out as the major players in oral tolerance. Oral antigen administration suppresses several animal models of autoimmune disease, including experimental autoimmune encephalomyelitis, uveitis, thyroiditis, myasthenia, arthritis, and diabetes, but also nonautoimmune inflammatory conditions such as asthma, atherosclerosis, graft rejection, allergy, and stroke. However, human trials have produced mixed results, and a great deal remains to be learned about the mechanisms of oral tolerance before it can be successfully applied to people. In this review, we highlight the cellular components involved in oral tolerance induction. A deep knowledge of these intricate cell interactions will pave the way for a successful application of antigen tolerance to treat autoimmune and nonautoimmune inflammatory diseases.

Background & Aims The liver is the main hematopoietic site in embryos, becoming a crucial organ in both immunity and metabolism in adults. However, how the liver adapts both the immune system and enzymatic profile to challenges in the postnatal period remains elusive. We aimed to identify the mechanisms underlying this adaptation. Methods We analyzed liver samples from mice on day 0 after birth until adulthood. Human biopsies from newborns and adults were also examined. Liver immune cells were phenotyped using mass cytometry (CyTOF) and expression of several genes belonging to immune and metabolic pathways were measured. Mortality rate, bacteremia and hepatic bacterial retention after E. coli challenge were analyzed using intravital and in vitro approaches. In a set of experiments, mice were prematurely weaned and the impact on gene expression of metabolic pathways was evaluated. Results Human and mouse newborns have a sharply different hepatic cellular composition and arrangement compared to adults. We also found that myeloid cells and immature B cells primarily compose the neonatal hepatic immune system. Although neonatal mice were more susceptible to infections, a rapid evolution to an efficient immune response was observed. Concomitantly, newborns displayed a reduction of several macronutrient metabolic functions and the normal expression level of enzymes belonging to lipid and carbohydrate metabolism was reached around the weaning period. Interestingly, early weaning profoundly disturbed the expression of several hepatic metabolic pathways, providing novel insights into how dietary schemes affect the metabolic maturation of the liver. Conclusion In newborns, the immune and metabolic profiles of the liver are dramatically different to those of the adult liver, which can be explained by the differences in the liver cell repertoire and phenotype. Also, dietary and antigen cues may be crucial to guide liver development during the postnatal phase. Lay summary Newborns face major challenges in the extra-uterine life. In fact, organs need to modify their cellular composition and gene expression profile in order to adapt to changes in both microbiota and diet throughout life. The liver is interposed between the gastrointestinal system and the systemic circulation, being the destination of all macronutrients and microbial products from the gut. Therefore, it is expected that delicately balanced mechanisms govern the transformation of a neonatal liver to a key organ in adults.

Autoimmune diseases are reversed in mice using nanoparticles that display disease-associated antigens bound to MHC class II molecules.

Seizures are due to excessive, synchronous neuronal firing in the brain and are characteristic of epilepsy, the fourth most prevalent neurological disease. We report handling‐induced and spontaneous seizures in mice deficient for CD39, a cell‐surface ATPase highly expressed on microglial cells. CD39−/− mice with handling‐induced seizures had normal input–output curves and paired‐pulse ratio measured from hippocampal slices and lacked microgliosis, astrogliosis or overt cell loss in the hippocampus and cortex. As expected, however, the cerebrospinal fluid of CD39−/− mice contained increased levels of ATP and decreased levels of adenosine. To determine if immune activation was involved in seizure progression, we challenged mice with lipopolysaccharide (LPS) and measured the effect on microglia activation and seizure severity. Systemic LPS challenge resulted in increased cortical staining of Iba1/CD68 and gene array data from purified microglia predicted increased expression of interleukin‐8, triggering receptor expressed on myeloid cells 1, p38, pattern recognition receptors, death receptor, nuclear factor‐κB , complement, acute phase, and interleukin‐6 signalling pathways in CD39−/− versus CD39+/+ mice. However, LPS treatment did not affect handling‐induced seizures. In addition, microglia‐specific CD39 deletion in adult mice was not sufficient to cause seizures, suggesting instead that altered expression of CD39 during development or on non‐microglial cells such as vascular endothelial cells may promote the seizure phenotype. In summary, we show a correlation between altered extracellular ATP/adenosine ratio and a previously unreported seizure phenotype in CD39−/− mice. This work provides groundwork for further elucidation of the underlying mechanisms of epilepsy.

Regulatory T cells (Tregs) promote cancer by suppressing antitumor immune responses. We found that anti-LAP antibody, which targets the latency-associated peptide (LAP)/transforming growth factor-β (TGF-β) complex on Tregs and other cells, enhances antitumor immune responses and reduces tumor growth in models of melanoma, colorectal carcinoma, and glioblastoma. Anti-LAP decreases LAP+ Tregs, tolerogenic dendritic cells, and TGF-β secretion and is associated with CD8+ T cell activation. Anti-LAP increases infiltration of tumors by cytotoxic CD8+ T cells and reduces CD103+ CD8 T cells in draining lymph nodes and the spleen. We identified a role for CD103+ CD8 T cells in cancer. Tumor-associated CD103+ CD8 T cells have a tolerogenic phenotype with increased expression of CTLA-4 and interleukin-10 and decreased expression of interferon-γ, tumor necrosis factor-α, and granzymes. Adoptive transfer of CD103+ CD8 T cells promotes tumor growth, whereas CD103 blockade limits tumorigenesis. Thus, anti-LAP targets multiple immunoregulatory pathways and represents a potential approach for cancer immunotherapy.

This study investigates the influence of gallium-arsenide (GaAs) laser photobiostimulation applied with different energy densities on skin wound healing by secondary intention in rats. Three circular wounds, 10 mm in diameter, were made on the dorsolateral region of 21 Wistar rats weighting 282.12 ± 36.08 g. The animals were equally randomized into three groups: Group SAL, saline solution 0.9%; Group L3, laser GaAs 3 J/cm(2); Group L30, laser GaAs 30 J/cm(2). Analyses of cells, blood vessels, collagen and elastic fibres, glycosaminoglycans and wound contraction were performed on the scar tissue from different wounds every 7 days for 21 days. On day 7, 14 and 21, L3 and L30 showed higher collagen and glycosaminoglycan levels compared to SAL (P < 0.05). At day 21, elastic fibres were predominant in L3 and L30 compared to SAL (P < 0.05). Type-III collagen fibres were predominant at day 7 in both groups. There was gradual reduction in these fibres and accumulation of type-I collagen over time, especially in L3 and L30 compared with SAL. Elevated density of blood vessels was seen in L30 on days 7 and 14 compared to the other groups (P < 0.05). On these same days, there was higher tissue cellularity in L3 compared with SAL (P < 0.05). The progression of wound closure during all time points investigated was higher in the L30 group (P < 0.05). Both energy densities investigated increased the tissue cellularity, vascular density, collagen and elastic fibres, and glycosaminoglycan synthesis, with the greater benefits for wound closure being found at the density of 30 J/cm(2).

Heat shock proteins (Hsps) participate in the cellular response to stress and they are hiperexpressed in inflammatory conditions. They are also known to play a major role in immune modulation, controlling, for instance, autoimmune responses. In this study, we showed that oral administration of a recombinant Lactococcus lactis strain that produces and releases LPS-free Hsp65 prevented the development of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. This was confirmed by the reduced inflammatory cell infiltrate and absence of injury signs in the spinal cord. The effect was associated with reduced IL-17 and increased IL-10 production in mesenteric lymph node and spleen cell cultures. Hsp65-producing-L. lactis-fed mice had a remarkable increase in the number of natural and inducible CD4+Foxp3+ regulatory T (Treg) cells and CD4+LAP+ (Latency-associated peptide) Tregs - which express the membrane-bound TGF-β - in spleen, inguinal and mesenteric lymph nodes as well as in spinal cord. Moreover, many Tregs co-expressed Foxp3 and LAP. In vivo depletion of LAP+ cells abrogated the effect of Hsp65-producing L. lactis in EAE prevention and worsened disease in medium-fed mice. Thus, Hsp65-L.lactis seems to boost this critical regulatory circuit involved in controlling EAE development in mice.

Meloidogyne species are destructive phytonematodes that result in reduced yields of coffee. The classic test for resistance to Meloidogyne exigua in coffee progenies is both expensive and time-consuming. The use of molecular marker techniques can assist the selection process when it is difficult to measure the phenotype, such as in cases of resistance to nematode infestation. The objective of this study was to identify microsatellite markers associated with resistance to M. exigua in F5 progenies of coffee derived from a cross between Hibrido de Timor 440-10 and Catuai Amarelo IAC 86. Of the 44 simple sequence repeat (SSR) markers evaluated, 11 showed a polymorphic pattern with a mean number of 4.5 alleles per marker. Clustering analysis classified 82 progenies into three groups related to the response to nematodes and parental genotypes allocated to different groups (resistant and susceptible). SSRCafe 40 allele 2, SSRCafe 15 allele 3, SSRCafe 20 allele 3, and SSRCafe 13 allele 1 were negatively correlated with reproduction factor. In addition, SSRCafe 13 allele 2, SSRCafe 19 allele 3, SSRCafe 40 allele 2, SSRCafe 15 allele 3, and SSRCafe 20 allele 3 were correlated with the root gall index of M. exigua. These SSR markers, which have been validated in this population, represent a potential method to select progenies resistant to nematodes in coffee-breeding programs.

Celecoxib is a selective inhibitor of cyclooxygenase-2 (COX-2) and blocks prostaglandin (PG) biosynthesis associated with inflammatory conditions. In a model of peripherally induced inflammatory pain in rats, celecoxib, given systemically, induced a state of hypoalgesia where the nociceptive threshold was raised above basal values, an effect not observed after treatment with non-selective inhibitors of COX (indomethacin, piroxicam). Here, we have assessed the possibility that these atypical effects of celecoxib could be mediated by action at a site in the CNS. Inflammation and hyperalgesia were induced in one hind paw of rats by intraplantar injection of carrageenan (250microg). Nociceptive thresholds to mechanical stimulation were measured in the inflammed and contralateral paws for 6h after carrageenan injection. Celecoxib, SC236 (selective COX-2 inhibitors), indomethacin (non-selective COX inhibitor), SC560 (selective COX-1 inhibitor) or morphine were given by i.c.v. injection, 30 min before carrageenan. Celecoxib, SC236 or morphine-induced hypoalgesia whereas, after indomethacin or SC 560, the nociceptive threshold only returned to basal values. Naltrexone, also given i.c.v., reversed the hypoalgesia after celecoxib or morphine. Bestatin, an inhibitor of metabolism of endogenous opioid peptides, given i.c.v., potentiated the analgesic effects of a low dose of celecoxib. Taken together, these data indicate that celecoxib could act centrally after systemic administration to produce its characteristic profile of analgesia in this model of peripheral inflammatory pain. Moreover, this atypical analgesia appeared to be mediated by endogenous opioids rather than by inhibition of PG biosynthesis.

Pretreatment using celecoxib, a cyclooxygenase (COX) 2 inhibitor, or indomethacin, a nonselective COX inhibitor, reduced lypopolyssaccharide (LPS)-induced leukocyte migration to the rat peritoneal cavity. The effect of celecoxib (12 mg/kg) or indomethacin (2 mg/kg) on neutrophil chemotaxis induced by formyl-methionyl-leucyl-phenylalanine (FMLP) in an in vitro chemotactic assay (Boyden chamber) was investigated. Celecoxib and indomethacin inhibited chemotaxis induced by FMLP (Control=26.6+/-1.45, Celecoxib=12.8+/-3.04, Indomethacin=6.26+/-2.19 cells/field). When observed under intravital microscopy, a mouse cremaster preparation was used to assess the microvasculature to further investigate which step of cell recruitment was affected by these drugs. Celecoxib and indomethacin inhibited leukocyte migration induced by 0.05 microg/kg LPS injected into the cremaster muscle. However, the effect of celecoxib was associated with reduced cell rolling and adhesion, whereas indomethacin was only effective at inhibiting cell adhesion. Furthermore, SC560 pretreatment (a COX-1 selective inhibitor) of normal or LPS-challenged tissues did not alter leukocyte migration or cell adhesion, but it did enhance leukocyte rolling activity in both cases. Taken together, these results indicate that: 1) COX-1 activity is mainly related to leukocyte traffic under physiological conditions, and 2) COX-2 activity is mainly related to cell traffic under inflammatory conditions in vascular beds, suggesting a possible effect of selective COX-2 inhibitors on the expression of adhesion molecules.

Background and purpose: The analgesics, paracetamol and dipyrone are weak inhibitors of the cyclooxygenase isoforms 1 or 2 (COX-1, COX-2) but more potent on COX-3. Both are also weak anti-inflammatory agents, relative to their analgesic and antipyretic activities. In a model of inflammatory pain mediated by prostaglandins, both compounds were analgesic. We have analysed this shared effect further in order to elucidate the underlying mechanisms. Experimental approach: Inflammation was induced in one hind paw of rats by intraplantar injection of 250 μg λ-carrageenan (CG) and the contralateral paw injected with saline. Nociceptive thresholds to mechanical stimulation were measured immediately before and for 6 h after, injection of CG. The analgesics were s.c. or locally (intraplantar) injected either 30 min before or 2 h after CG. In some groups, naltrexone was injected (s.c. or intraplantar), 1 h before CG. Key results: Pretreatment with paracetamol or dipyrone (60–360 mg kg−1) reversed hyperalgesia induced by CG and increased nociceptive threshold in the inflamed paw above the basal level (hypoalgesia). Paracetamol, but not dipyrone, also raised nociceptive thresholds in the non-inflamed paw. Subcutaneous, but not local, administration of naltrexone, a specific opioid antagonist, reversed the hypoalgesia induced by paracetamol, but similar naltrexone treatment had no effect on dipyrone-induced analgesia. Conclusions and implications: Although both paracetamol and dipyrone are inhibitors of COX isoforms and thus of prostaglandin biosynthesis and were analgesic in our model, their analgesic actions were functionally and mechanistically different. Satisfactory mechanisms of action for these analgesics still remain to be established. British Journal of Pharmacology (2008) 153, 760–768; doi:10.1038/sj.bjp.0707630; published online 24 December 2007

γδ T cells are a subset of lymphocytes specialized in protecting the host against pathogens and tumours. Here we describe a subset of regulatory γδ T cells that express the latency-associated peptide (LAP), a membrane-bound TGF-β1. Thymic CD27+IFN-γ+CCR9+α4β7+TCRγδ+ cells migrate to the periphery, particularly to Peyer's patches and small intestine lamina propria, where they upregulate LAP, downregulate IFN-γ via ATF-3 expression and acquire a regulatory phenotype. TCRγδ+LAP+ cells express antigen presentation molecules and function as antigen presenting cells that induce CD4+Foxp3+ regulatory T cells, although TCRγδ+LAP+ cells do not themselves express Foxp3. Identification of TCRγδ+LAP+ regulatory cells provides an avenue for understanding immune regulation and biologic processes linked to intestinal function and disease., Latency-associated peptide (LAP) is a membrane-bound form of TGF-β1. Here the authors show that LAP marks a subset of regulatory γδ T cells with innate gut-homing properties, which present antigen and induce CD4+ Foxp3+ in Peyer's patches and lamina propria.

Despite accumulating evidence indicating that neurotransmitters released by the sympathetic nervous system can modulate the activity of innate immune cells, we still know very little about how norepinephrine impacts signaling pathways in dendritic cells (DC) and the consequence of that in DC-driven T cell differentiation. In this article, we demonstrate that β2-adrenergic receptor (β2AR) activation in LPS-stimulated DC does not impair their ability to promote T cell proliferation; however, it diminishes IL-12p70 secretion, leading to a shift in the IL-12p70/IL-23 ratio. Although β2AR stimulation in DC induces protein kinase A–dependent cAMP-responsive element–binding protein phosphorylation, the effect of changing the profile of cytokines produced upon LPS challenge occurs in a protein kinase A–independent manner and, rather, is associated with inhibition of the NF-κB and AP-1 signaling pathways. Moreover, as a consequence of the inverted IL-12p70/IL-23 ratio following β2AR stimulation, LPS-stimulated DC promoted the generation of CD4+ T cells that, upon TCR engagement, produced lower amounts of IFN-γ and higher levels of IL-17. These findings provide new insights into molecular and cellular mechanisms by which β2AR stimulation in murine DC can influence the generation of adaptive immune responses and may explain some aspects of how sympathetic nervous system activity can modulate immune function.

Regulatory T cells (Tregs) play a critical role in the maintenance of immunological tolerance. The best-characterized Tregs are those expressing the transcription factor Foxp3 and in vivo modulation of Foxp3 Tregs has been employed to study their role in immune homeostasis. Latency-associated peptide (LAP) is a membrane-bound TGF-β complex that has also been shown to play a role in Treg function and oral tolerance. We developed a novel anti-mouse LAP mAb that allowed us to investigate the effect of targeting LAP in vivo on immune function and on anti-CD3-induced oral tolerance. We found that in vivo anti-LAP mAb administration led to a decrease in the number of CD4+LAP+ Tregs in spleen and lymph nodes without affecting CD4+Foxp3+ Tregs. Spleen cells from anti-LAP-injected mice proliferated more in vitro and produced increased amounts of IL-2, IL-17 and IFN-γ. Moreover, injection of anti-LAP antibody abrogated the protective effect of oral anti-CD3 on experimental autoimmune encephalomyelitis (EAE). Finally, in vivo anti-LAP administration prior to myelin oligodendrocyte glycoprotein immunization resulted in severe EAE in the absence of pertussis toxin, which is used for EAE induction. Our findings demonstrate the importance of CD4+LAP+ T cells in the control of immune homeostasis and autoimmunity and provides a new tool for the in vivo investigation of murine LAP+ Tregs on immune function.

Background/Aims: In this study we analyzed the mechanisms underlying celecoxib-induced analgesia in a model of inflammatory pain in rats, using the intracerebroventricular (i.c.v.) administration of selective opioid and cannabinoid antagonists. Methods and Results: Analgesic effects of celecoxib were prevented by selective µ-(β-funaltrexamine) and δ-(naltrindole), but not ĸ-(nor-binaltorphimine) opioid antagonists, given i.c.v. 30 min before celecoxib. Similar pretreatment with AM 251, but not SR 144528, cannabinoid CB1 and CB2 receptor antagonists, respectively, prevented celecoxib-induced analgesia. The fatty acid amide hydrolase inhibitor, URB 597, also prevented celecoxib-induced analgesia. Conclusions: Our data provided further evidence for the involvement of endogenous opioids and revealed a new cannabinoid component of the mechanism(s) underlying celecoxib-induced analgesia.

In a model of peripherally induced inflammatory pain in rats, selective inhibitors of cyclooxygenase (COX)-2 raised nociceptive thresholds above basal values, an effect referred to as "hypoalgesia". However other, non-selective, inhibitors of COX (indomethacin, piroxicam) or a selective inhibitor of COX-1 did not induce hypoalgesia in this model, implying that COX inhibition was not causally related to the hypoalgesic effect. Here, we have assessed whether other COX-2 inhibitors or other sulphonamides, apart from celecoxib could exhibit hypoalgesia in our model of inflammatory pain. Inflammation was induced in one hind paw of rats by intraplantar injection of carrageenan (250 μg). Nociceptive thresholds to mechanical stimulation were measured in the inflamed and contralateral paws for 6 h after carrageenan. Three sulphonamides, celecoxib itself, furosemide (a loop diuretic), acetazolamide (a carbonic anhydrase inhibitor), or a selective COX-2 inhibitor lacking the sulphonamide group, lumiracoxib, were injected s.c., 30 min before the pro-inflammatory stimulus. Naltrexone, a non-selective opioid antagonist was also administered s.c., 30 min before test drugs. Furosemide and acetazolamide dose-dependently induced hypoalgesia in the inflamed paw, as did celecoxib. However, lumiracoxib only produced anti-hyperalgesia. Pre-treatment with naltrexone completely prevented the hypoalgesia induced by the sulphonamides, but only partially prevented the anti-hyperalgesic effect of lumiracoxib. Taken together, our results suggest that the sulphonamide group in the structure of celecoxib is more critical for the development of hypoalgesia in our model than its ability to inhibit COX-2. Further, other sulphonamides lacking significant COX inhibition were also able to exhibit hypoalgesic effects, mediated by the endogenous opioid system.

Aims The endogenous opioids mediate the analgesic effects of celecoxib in a model of mechanical hyperalgesia in rats. As responses to thermal stimuli may differ from those to mechanical stimuli, we have here assessed celecoxib in a rat model of thermal hyperalgesia and the possible involvement of endogenous opioids and their corresponding receptors in these effects. Main methods Injection of carrageenan (CG) into one hind paw induced a dose-related hyperalgesia (decreased time for paw withdrawal) to thermal stimuli (infra-red light beam), over 6 h. Key findings Celecoxib (sc) 30 min before CG (250 μg per paw) induced a dose-dependent reversal of hyperalgesia, with withdrawal times well above basal levels, characterizing development of hypoalgesia. Indomethacin (sc) reversed CG-induced hyperalgesia only to basal levels (an anti-hyperalgesic effect). Naltrexone (sc) prevented hypoalgesia after celecoxib but did not change the response to indomethacin. Local (intraplantar) injection of either a selective antagonist of μ-(beta-funaltrexamine), κ-(nor-binaltorphimine) or of δ-(naltrindole) opioid receptors also reversed the hypoalgesic effects of celecoxib, without modifying the hyperalgesia due to CG or affecting the nociceptive thresholds in the non-injected paw. Significance Our data show that celecoxib, unlike indomethacin, was hypoalgesic in this model of thermal hyperalgesia, and that this effect was mediated by peripheral μ-, κ- and δ-opioid receptors.

Mechanical hyperalgesia induced in rat paws by carrageenan (250 μg) was modified by pre-treatment with three selective inhibitors of cyclo-oxygenase-2 (COX-2); celecoxib, rofecoxib and SC236. These inhibitors raised the nociceptive threshold above the normal, non-inflamed, level, inducing a state of hypoalgesia. Such hypoalgesia was observed in different strains of rat (Holtzman, Wistar and Sprague–Dawley) and after different modes of administration of the COX-2 inhibitor (locally, in the paw, or systemically). A selective inhibitor of COX-1 (SC 560; 1–10 mg kg −1 ) decreased hyperalgesia but did not induce hypoalgesia. Pre-treatment with naltrexone (3 mg kg −1 ), an opioid receptor antagonist, did not affect carrageenan-induced hyperalgesia but abolished the hypoalgesic effects of COX-2 inhibitors, without diminishing the anti-hyperalgesic effect of indomethacin. In rats made tolerant to the anti-nociceptive effects of morphine, all anti-nociceptive effects of SC236 were abolished but the anti-hyperalgesic effects of indomethacin or SC 560 were unaffected. We conclude that, in our model of inflammatory hyperalgesia, the anti-nociceptive effect of selective COX-2 inhibitors involved the participation of endogenous opioids.