Regulatory Phenotype Research Articles

Immune Complex-Driven Generation of Human Macrophages with Anti-Inflammatory and Growth-Promoting Activity.

To maintain homeostasis, macrophages must be capable of assuming either an inflammatory or an anti-inflammatory phenotype. To better understand the latter, we stimulated human macrophages in vitro with TLR ligands in the presence of high-density immune complexes (IC). This combination of stimuli resulted in a broad suppression of inflammatory mediators and an upregulation of molecules involved in tissue remodeling and angiogenesis. Transcriptomic analysis of TLR stimulation in the presence of IC predicted the downstream activation of AKT and the inhibition of GSK3. Consequently, we pretreated LPS-stimulated human macrophages with small molecule inhibitors of GSK3 to partially phenocopy the regulatory effects of stimulation in the presence of IC. The upregulation of DC-STAMP and matrix metalloproteases was observed on these cells and may represent potential biomarkers for this regulatory activation state. To demonstrate the presence of these anti-inflammatory, growth-promoting macrophages in a human infectious disease, biopsies from patients with leprosy (Hanseniasis) were analyzed. The lepromatous form of this disease is characterized by hypergammaglobulinemia and defective cell-mediated immunity. Lesions in lepromatous leprosy contained macrophages with a regulatory phenotype expressing higher levels of DC-STAMP and lower levels of IL-12, relative to macrophages in tuberculoid leprosy lesions. Therefore, we propose that increased signaling by FcγR cross-linking on TLR-stimulated macrophages can paradoxically promote the resolution of inflammation and initiate processes critical to tissue growth and repair. It can also contribute to infectious disease progression.

Preoperative oral immunonutrition in gastrointestinal surgical patients: How the tumour microenvironment can be modified.

This study is focused on the impact of enteral immunonutrition on the cell-mediated immune response in the microenvironment of gastric and colorectal cancers. This is a prospective pilot study approved by the local Ethics Committee. The immunophenotypic structure of the immune cells before (on the biopsy) and after (on the surgical sample) the administration of the immunonutrition in 16 patients is compared with 8 patients receiving regular diet. The samples of non-tumour tissue from sleeve-gastrectomy are used as non-neoplastic control. Antibodies were tested: CD4, CD8, PD-1, FOX-P3, CD68, CD163, CD80, CD21, CD56, PD-L1. We applied already well-known scoring systems for the evaluation of the immunohistochemistry and compared our data in the different groups by statistical analysis. In treated patients, we detected a modulation of the immune response with higher number of cytotoxic and helper T-lymphocytes in the tumour microenvironment of the surgical specimens compared to the pre-operative biopsy, and a lower number of lymphocytes presenting an exhausted (i.e. double positive CD8 and PD-1 lymphocytes) and regulatory (i.e. double positive CD4 and FOX-P3 lymphocytes) phenotype. Moreover we observed the M1 polarization with a lower number of CD163 positive macrophages and the inhibition of the PD-1/PD-L1 pathway in treated patients. The immunonutrition impacts on the tumoral microenvironment of gastric and colorectal cancer activating the inflammatory pathway, in terms of humoral and cellular response.

FTY720 Regulates Mitochondria Biogenesis in Dendritic Cells to Prevent Kidney Ischemic Reperfusion Injury.

Dendritic cells (DCs) are central in regulating immune responses of kidney ischemia-reperfusion injury (IRI), and strategies to alter DC function may provide new therapeutic opportunities. Sphingosine 1-phosphate (S1P) modulates immunity through binding to its receptors (S1P1-5), and protection from kidney IRI occurs in mice treated with S1PR agonist, FTY720 (FTY). We tested if ex vivo propagation of DCs with FTY could be used as cellular therapy to limit the off-target effects associated with systemic FTY administration in kidney IRI. DCs have the ability of regulate innate and adaptive responses and we posited that treatment of DC with FTY may underlie improvements in kidney IRI. Herein, it was observed that treatment of bone marrow derived dendritic cells (BMDCs) with FTY induced mitochondrial biogenesis, FTY-treated BMDCs (FTY-DCs) showed significantly higher oxygen consumption rate and ATP production compared to vehicle treated BMDCs (Veh-DCs). Adoptive transfer of FTY-DCs to mice 24 h before or 4 h after IRI significantly protected the kidneys from injury compared to mice treated with Veh-DCs. Additionally, allogeneic adoptive transfer of C57BL/6J FTY-DCs into BALB/c mice equally protected the kidneys from IRI. FTY-DCs propagated from S1pr1-deficient DCs derived from CD11cCreS1pr1fl/fl mice as well as blunting mitochondrial oxidation in wildtype (WT) FTY-DCs prior to transfer abrogated the protection observed by FTY-DCs. We queried if DC mitochondrial content alters kidney responses after IRI, a novel but little studied phenomenon shown to be integral to regulation of the immune response. Transfer of mitochondria rich FTY-DCs protects kidneys from IRI as transferred FTY-DCs donated their mitochondria to recipient splenocytes (i.e., macrophages) and prior splenectomy abrogated this protection. Adoptive transfer of FTY-DCs either prior to or after ischemic injury protects kidneys from IRI demonstrating a potent role for donor DC-mitochondria in FTY's efficacy. This is the first evidence, to our knowledge, that DCs have the potential to protect against kidney injury by donating mitochondria to splenic macrophages to alter their bioenergetics thus making them anti-inflammatory. In conclusion, the results support that ex vivo FTY720-induction of the regulatory DC phenotype could have therapeutic relevance that can be preventively infused to reduce acute kidney injury.

Co-treatments to Boost IDO Activity and Inhibit Production of Downstream Catabolites Induce Durable Suppression of Experimental Autoimmune Encephalomyelitis.

Reinforcing defective tolerogenic processes slows progression of autoimmune (AI) diseases and has potential to promote drug-free disease remission. Previously, we reported that DNA nanoparticles (DNPs) and cyclic dinucleotides (CDNs) slow progression of experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis, by activating the Stimulator of Interferon Genes (STING) signaling adaptor to stimulate interferon type 1 (IFN-I) production, which induced dendritic cells to express indoleamine 2,3 dioxygenase (IDO) and acquire immune regulatory phenotypes. Here, we show that therapeutic responses to DNPs depend on DNA sensing via cyclic GAMP synthase (cGAS) and interactions between Programmed Death-1 (PD-1) and PD-1 ligands. To investigate how increased tryptophan (Trp) metabolism by IDO promotes therapeutic responses mice were co-treated at EAE onset with DNPs and drugs that inhibit kynurenine aminotransferase-II (KatII) or 3-hydroxyanthranilic acid dioxygenase (HAAO) activity downstream of IDO in the kynurenine (Kyn) pathway. DNP and KatII or HAAO inhibitor co-treatments suppressed EAE progression more effectively than DNPs, while KatII inhibition had no significant therapeutic benefit and HAAO inhibition attenuated but did not prevent EAE progression. Moreover, therapeutic responses to co-treatments were durable as EAE progression did not resume after co-treatment. Thus, using STING agonists to boost IDO activity and manipulating the Kyn pathway downstream of IDO is an effective strategy to enhance tolerogenic responses that overcome autoimmunity to suppress EAE progression.

Protein Kinase C Theta Modulates PCMT1 through hnRNPL to Regulate FOXP3 Stability in Regulatory T Cells

T cell receptor signaling, together with cytokine-induced signals, can differentially regulate RNA processing to influence T helper versus regulatory Tcell fate. Protein kinase C family members have been shown to function in alternative splicing and RNA processing in various cell types. Tcell-specific protein kinase C theta, a molecular regulator of Tcell receptor downstream signaling, has been shown to phosphorylate splicing factors and affect post-transcriptional control of Tcell gene expression. In this study, we explored how using a synthetic cell-penetrating peptide mimic for intracellular anti-protein kinase C theta delivery fine-tunes differentiation of induced regulatory Tcells through its differential effects on RNA processing. We identified protein kinase C theta signaling as a critical modulator of two key RNA regulatory factors, heterogeneous nuclear ribonucleoprotein L (hnRNPL) and protein-l-isoaspartate O-methyltransferase-1 (PCMT1), and loss of protein kinase C theta function initiated a "switch" in post-transcriptional organization in induced regulatory Tcells. More interestingly, we discovered that protein-l-isoaspartate O- methyltransferase-1 acts as an instability factor in induced regulatory Tcells, by methylating the forkhead box P3 (FOXP3) promoter. Targeting protein-l-isoaspartate O-methyltransferase-1 using a cell-penetrating antibody revealed an efficient means of modulating RNA processing to confer a stable regulatory Tcell phenotype.

Gene editing to induce FOXP3 expression in human CD4 + T cells leads to a stable regulatory phenotype and function

Thymic regulatory T cells (tTregs) are potent inhibitors of autoreactive immune responses, and loss of tTreg function results in fatal autoimmune disease. Defects in tTreg number or function are also implicated in multiple autoimmune diseases, leading to growing interest in use of Treg as cell therapies to establish immune tolerance. Because tTregs are present at low numbers in circulating blood and may be challenging to purify and expand and also inherently defective in some subjects, we designed an alternative strategy to create autologous Treg-like cells from bulk CD4+ T cells. We used homology-directed repair (HDR)-based gene editing to enforce expression of FOXP3, the master transcription factor for tTreg Targeted insertion of a robust enhancer/promoter proximal to the first coding exon bypassed epigenetic silencing, permitting stable and robust expression of endogenous FOXP3. HDR-edited T cells, edTregs, manifested a transcriptional program leading to sustained expression of canonical markers and suppressive activity of tTreg Both human and murine edTregs mediated immunosuppression in vivo in models of inflammatory disease. Further, this engineering strategy permitted generation of antigen-specific edTreg with robust in vitro and in vivo functional activity. Last, edTreg could be enriched and expanded at scale using clinically relevant methods. Together, these findings suggest that edTreg production may permit broad future clinical application.

247-OR: ADA Presidents’ Select Abstract: Detection of T-Cells Reactive to Hybrid Insulin Peptides in Subjects at Risk for Type 1 Diabetes

Our lab recently established that Hybrid Insulin Peptides (HIPs) are antigenic ligands for diabetogenic T cell clones in the NOD mouse model of autoimmune diabetes. Importantly, we have found that the phenotype of HIP-reactive T cells present in the peripheral blood of NOD mice is indicative of ongoing autoimmunity in the pancreas. In the human setting, we demonstrated that T cells reactive to HIPs are present in the residual islets of type 1 diabetic (T1D) organ donors and more recently, in PBMC from T1D patients. Using an IFN-gamma ELISPOT assay to test T cell reactivity in the peripheral blood of T1D patients or control subjects to a panel of 16 HIPs, we demonstrated that 70% of the responding patients showed reactivity to multiple HIPs. To determine whether the presence of HIP-reactive T cells might serve as a biomarker of disease activity in humans, we are following longitudinally a cohort of subjects positive for multiple islet autoantibodies (Ab+), individuals that are at high risk for developing T1D. Using IFN-gamma ELISPOT and CFSE dilution assays, our data indicate that HIP-reactive T cells with an inflammatory phenotype can be detected before disease onset. In one Ab+ individual that showed HIP reactivity, we used single-cell RNA sequencing to study the phenotype and TCR usage of HIP-responding T cells in 3 longitudinal samples collected 6 months apart. We observed that T cells with a regulatory phenotype (FoxP3+, CTLA-4+, LAG3+) can be observed when a proliferative response - but not inflammatory - is detected. In this ongoing study, we are reporting for the first time that HIP-reactive T cells can be observed in the peripheral blood of subjects at risk for T1D, and our data may indicate that the balance of inflammatory vs. regulatory signals of HIP-reactive T cells could be potential indicators of disease activity. Disclosure R.L. Baker: None. T. Delong: None. M. Rewers: None. P. Gottlieb: Advisory Panel; Self; Janssen Scientific Affairs, LLC., Tolerion, Inc., Viacyte, Inc. Research Support; Self; Caladrius Biosciences, Inc., Immune Tolerance Network, Janssen Pharmaceuticals, Inc., JDRF, Leona M. and Harry B. Helmsley Charitable Trust, Mercia/Nova Laboratories, National Institute of Diabetes and Digestive and Kidney Diseases, Novo Nordisk Inc. Stock/Shareholder; Self; IM Therapeutics. K.M. Haskins: None. Funding American Diabetes Association (1-15-ACE-14 to T.D.); JDRF (2-SRA-2017-511-S-B); National Institutes of Health (R21AI133059-01A1)

Predicting Evolutionary Constraints by Identifying Conflicting Demands in Regulatory Networks.

Gene regulation networks allow organisms to adapt to diverse environmental niches. However, the constraints underlying the evolution of gene regulation remain ill defined. Here, we show that partial order-a concept that ranks network output levels as a function of different input signals-identifies such constraints. We tested our predictions by experimentally evolving an engineered signal-integrating network in multiple environments. We find that populations: (1) expand in fitness space along the Pareto-optimal front associated with conflicts in regulatory demands, by fine-tuning binding affinities within the network, and (2) expand beyond the Pareto-optimal front through changes in the network structure. Our constraint predictions are based only on partial order and do not require information on the network architecture or underlying genetics. Overall, our findings show that limited knowledge of current regulatory phenotypes can provide predictions on future evolutionary constraints.

Controlled Delivery of Immunomodulators from a Biomaterial Scaffold Niche to Induce a Tolerogenic Phenotype in Human Dendritic Cells.

Engineering a regulatory phenotype in dendritic cells (DCs) is a potential approach to circumvent an immune response against self-antigens in autoimmunity or alloantigens in allograft rejection. Cell microenvironments influence the differentiation of DC precursors into either proinflammatory/immunostimulatory or tolerogenic/regulatory DCs. Biomaterial-based vehicles can be used to re-engineer cell microenvironments and re-educate the DC phenotype. This study presents the development and validation of a biomaterial-based multicomponent immunomodulatory (MI) scaffold for the purpose of promoting a tolerogenic/regulatory DC phenotype. Glutaraldehyde-crosslinked gelatin microparticles, loaded with specific immunomodulators, were embedded into a porous agarose scaffold. Using the Weibull equation and the Bayesian approach, an empirical mathematical model was derived from the release profile data of "model" molecules. The scaffold design was generated from the model to achieve distinct temporal release profiles of the loaded immunomodulator(s): granulocyte monocyte colony-stimulating factor (GM-CSF), dexamethasone (DEX), and/or peptidoglycan (PGN). The MI scaffold-treated DCs (MI DCs) showed an increase in the expression of tolerogenic markers such as surface immunoglobulin-like transcript 3 (ILT-3) and secreted interleukin-10 (IL-10), with a simultaneous decrease in maturation markers such as CD86 and secreted interferon-γ (IFN-γ). In cell culture studies, these MI DCs were able to suppress T-cell proliferation. This approach is expected to enhance the generation of endogenous regulatory DCs when applied in vivo. This technology serves as a basis for future immunotherapeutic applications in the autoimmunity and allogeneic therapies. It also shows that empirical mathematical modeling can be used to engineer scaffold designs for distinct temporal release of one or more immunomodulators.

Interplay between Cytokine Circuitry and Transcriptional Regulation Shaping Helper T Cell Pathogenicity and Plasticity in Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a chronic disorder manifested as Crohn’s disease (CD) and ulcerative colitis (UC) characterized by intestinal inflammation and involves a dysregulated immune response against commensal microbiota through the activation of CD4 T helper cells. T helper cell differentiation to effector or regulatory phenotypes is controlled by cytokine networks and transcriptional regulators. Distinct polarized T helper cells are able to alter their phenotypes to adapt to diverse and fluctuating physiological environments. T helper cells exhibit intrinsic instability and flexibility to express cytokines of other lineages or transdifferentiate from one T helper cell type to another in response to various perturbations from physiological cytokine milieu as a means of promoting local immunity in response to injury or ensure tissue homeostasis. Furthermore, functional plasticity and diversity of T helper cells are associated with pathogenicity and are critical for immune homeostasis and prevention of autoimmunity. In this review, we provide deeper insights into the combinatorial extrinsic and intrinsic signals that control plasticity and transdifferentiation of T helper cells and also highlight the potential of exploiting the genetic reprogramming plasticity of T helper cells in the treatment of IBD.

Regulating T-cell differentiation through the polyamine spermidine

The cross-talk between the host and its microbiota plays a key role in the promotion of health. The production of metabolites such as polyamines by intestinal-resident bacteria is part of this symbiosis shaping host immunity. The polyamines putrescine, spermine, and spermidine are abundant within the gastrointestinal tract and might substantially contribute to gut immunity. We aimed to characterize the polyamine spermidine as a modulator of T-cell differentiation and function. Naive T cells were isolated from wild-type mice or cord blood from healthy donors and submitted to polarizing cytokines, with and without spermidine treatment, to evaluate CD4+ T-cell differentiation invitro. Moreover, mice were subjected to oral supplementation of spermidine, or its precursor l-arginine, to assess the frequency and total numbers of regulatory T (Treg) cells invivo. Spermidine modulates CD4+ T-cell differentiation invitro, preferentially committing naive T cells to a regulatory phenotype. After spermidine treatment, activated T cells lacking the autophagy gene Atg5 fail to upregulate Foxp3 to the same extent as wild-type cells. These results indicate that spermidine's polarizing effect requires an intact autophagic machinery. Furthermore, dietary supplementation with spermidine promotes homeostatic differentiation of Treg cells within the gut and reduces pathology in a model of T-cell transfer-induced colitis. Altogether, our results highlight the beneficial effects of spermidine, or l-arginine, on gut immunity by promoting Treg cell development.

Anti-TNF therapy in IBD exerts its therapeutic effect through macrophage IL-10 signalling

ObjectiveMacrophage interleukin (IL)-10 signalling plays a critical role in the maintenance of a regulatory phenotype that prevents the development of IBD. We have previously found that anti-tumour necrosis factor (TNF)...

Detection of T cells Reactive to Hybrid Insulin Peptides in Subjects at Risk for Type 1 Diabetes

Abstract Our lab recently established that Hybrid Insulin Peptides (HIPs) are antigenic ligands for diabetogenic T cell clones in the NOD mouse model of autoimmune diabetes. Importantly, we have found that the phenotype of HIP-reactive T cells present in the peripheral blood of NOD mice is indicative of ongoing autoimmunity in the pancreas. In the human setting, we demonstrated that T cells reactive to HIPs are present in the residual islets of type 1 diabetic (T1D) organ donors and more recently, in PBMC from T1D patients. Using an IFN-g ELISPOT assay to test T cell reactivity in the peripheral blood of T1D patients or control subjects to a panel of 16 HIPs, we demonstrated that 70% of the responding patients showed reactivity to multiple HIPs. To determine whether the presence of HIP-reactive T cells might serve as a biomarker of disease activity in humans, we are following longitudinally a cohort of subjects positive for multiple islet autoantibodies (Ab+), individuals that are at high risk for developing T1D. Using IFN-g ELISPOT and CFSE dilution assays, our data indicate that HIP-reactive T cells with an inflammatory phenotype can be detected before disease onset. In one Ab+ individual that showed HIP reactivity, we used single-cell RNA sequencing to study the phenotype and TCR usage of HIP-responding T cells. We observed that T cells with a regulatory phenotype (FoxP3+, CTLA-4+, LAG3+) can be observed when a proliferative (but not inflammatory) response is detected. In this ongoing study, we are reporting for the first time that HIP-reactive T cells can be observed in the peripheral blood of subjects at risk for T1D, suggesting that the balance of inflammatory vs. regulatory signals of HIP-reactive T cells could be potential indicators of disease activity.

Repeated febrile malaria exposure remodels monocytes/macrophages toward a regulatory/tolerogenic phenotype

Abstract In malaria-naïve individuals, P. falciparum (Pf) infection results in numerous Pf-infected red blood cells (iRBCs) that trigger systemic inflammation and fever. Conversely, repeatedly infected individuals in endemic areas are often asymptomatic and have low levels of iRBCs, even children who have yet to acquire reliably protective antibodies. The molecular mechanisms underlying these clinical observations are unclear. PBMCs collected from Malian children before the malaria season responded to iRBCs by producing pyrogenic, pro-inflammatory mediators such as IL-1β, IL-6 and TNF. However, following febrile malaria there was a marked shift in the response to iRBCs with the same children’s PBMCs producing lower levels of those cytokines. These data suggest that malaria-induced epigenetic reprogramming of innate immune cells may play a role in immunity to malaria. Accordingly, age-stratified analysis of monocytes collected before the malaria season showed an inverse relationship between age and pro-inflammatory cytokine production capacity. Monocytes of Malian adults expressed higher levels of CD163, CD206, Arginase-1, TGM2, molecules which are known to be associated with regulatory phenotype. These observations were recapitulated with an in vitro system of monocyte-macrophage differentiation whereby re-exposure to iRBCs was associated with diminished expression of pro-inflammatory mediators and a corresponding decrease in epigenetic markers of active gene transcription (i.e. H3K4me3) at the TSS of the same pro-inflammatory mediators. Together these data support the hypothesis that epigenetic reprogramming of monocytes/macrophages toward a regulatory phenotype contributes to clinical immunity to malaria.

Human Chorionic Gonadotropin acts as a central regulator of adaptive immune responses during early pregnancy safeguarding fetal survival

Abstract A perfect interplay between the endocrine system and the maternal immune system is pivotal for early fetal tolerance induction. Particularly, the placenta-derived hormone human chorionic gonadotropin (hCG) that is secreted during early pregnancy stages and is suggested to regulate pro- and anti-inflammatory maternal immune responses. However, the precise mechanisms underlying hCG-driven immunoregulation are far from being understood. Thus, we performed several studies to illuminate the participation of hCG in immunomodulation with a specific focus on T and B cell responses. We included human and mouse material in our studies to analyze the influence of hCG on the generation, plasticity and functionality of regulatory T (Treg) cells, Th17 cells and B cells using different in vitro assays. In vivo, we applied hCG during the peri-implantation period into abortion-prone mice and analyzed Treg proportions and activity. Our in vitro results revealed that hCG attracts human Treg, promotes formation of human and mouse Treg and increases T cell suppressive activity in both species. Moreover, hCG inhibits mouse Th17 differentiation and induces Th17 cells with anti-inflammatory phenotypes in the mouse system. Human B cells adopt a regulatory phenotype and start to secrete fetal-protective asymmetric antibodies upon hCG stimulation in vitro. In vivo, hCG application into abortion-prone mice restored Treg levels, augmented Treg suppressive activity and rescued fetuses from rejection. In summary, our findings suggest that hCG contributes to early fetal tolerance induction by shifting maternal adaptive immune responses towards an anti-inflammatory profile.

Baby's First Macrophage: Temporal Regulation of Hofbauer Cell Phenotype Influences Ligand-Mediated Innate Immune Responses across Gestation.

The importance of fetal placental macrophages (Hofbauer cell [HCs]) is underscored by their appearance 18 d postconception and maintenance through term; however, how human HCs evolve during healthy pregnancy and how microenvironment and ontogeny impact phenotype and function remain unknown. In this study, we comprehensively classify human HCs ex vivo, interrogate phenotypic plasticity, and characterize antiviral immune responses through gestation. Activated HCs were abundant in early pregnancy and decreased by term; molecular signatures emphasize inflammatory phenotypes early in gestation. Frequency of HCs with regulatory phenotypes remained high through term. Furthermore, term HCs exhibited blunted responses to stimulation, indicating reduced plasticity. IFN-λ1 is a key placental IFN that appeared less protective than IFN-α, suggesting a potential weakness in antiviral immunity. Ligand-specific responses were temporally regulated: we noted an absence of inflammatory mediators and reduced antiviral gene transcription following RIG-I activation at term despite all HCs producing inflammatory mediators following IFN-γ plus LPS stimulation. Collectively, we demonstrate sequential, evolving immunity as part of the natural history of HCs through gestation.

Cell Therapy With Mesenchymal Stem Cells Induces an Innate Immune Memory Response That Attenuates Experimental Colitis in the Long Term.

Background and AimsMesenchymal stem cells [MSCs] are used in preclinical and clinical studies for treatment of immune-mediated disorders, thanks to their immunomodulatory properties. Cell therapy with MSCs induces multiple effects in the immune system which ultimately lead to increase in the number of immune cells with regulatory phenotype. In this study, we investigated whether the beneficial effects of MSC therapy are maintained in the long term in a clinically relevant mouse model of colitis.MethodsA single dose of adipose-derived MSCs [aMSCs] was infused into dextran sulphate sodium [DSS]-induced colitic mice during the induction phase of the disease. Following a latency period of 12 weeks, mice were re-challenged with a second 7-day cycle of DSS.ResultsDSS-induced colitic mice treated with aMSCs showed significant reduction in their colitic disease activity index during the second DSS challenge when compared with non-aMSC treated DSS-induced colitic mice. Strikingly, the long-term protection induced by aMSC therapy was also observed in Rag-1-/- mice where no adaptive immune memory cell responses take place. Increased percentages of Ly6G+CD11b+ myeloid cells were observed 12 weeks after the first inflammatory challenge in the peritoneal cavity, spleen, and bone marrow of DSS-induced colitic mice that were infused with aMSCs. Interestingly, upon re-challenge with DSS, these animals showed a concomitant increase in the regulatory/inflammatory macrophage ratio in the colon lamina propria.ConclusionsOur findings demonstrate for the first time that MSC therapy can imprint an innate immune memory-like response in mice which confers sustained protection against acute inflammation in the long term.

The lymph node stromal laminin α5 shapes alloimmunity.

Lymph node stromal cells (LNSCs) regulate immunity through constructing lymphocyte niches. LNSC-produced laminin α5 (Lama5) regulates CD4+ T cells but the underlying mechanisms of its functions are poorly understood. Here we show that depleting Lama5 in LNSCs resulted in decreased Lama5 protein in the LN cortical ridge (CR) and around high endothelial venules (HEVs). Lama5 depletion affected LN structure with increased HEVs, upregulated chemokines, and cell adhesion molecules, and led to greater numbers of Tregs in the T cell zone. Mouse and human T cell transendothelial migration and T cell entry into LNs were suppressed by Lama5 through the receptors α6 integrin and α-dystroglycan. During immune responses and allograft transplantation, depleting Lama5 promoted antigen-specific CD4+ T cell entry into the CR through HEVs, suppressed T cell activation, and altered T cell differentiation to suppressive regulatory phenotypes. Enhanced allograft acceptance resulted from depleting Lama5 or blockade of T cell Lama5 receptors. Lama5 and Lama4/Lama5 ratios in allografts were associated with the rejection severity. Overall, our results demonstrated that stromal Lama5 regulated immune responses through altering LN structures and T cell behaviors. This study delineated a stromal Lama5-T cell receptor axis that can be targeted for immune tolerance modulation.

B cells induced by Schistosoma japonicum infection display diverse regulatory phenotypes and modulate CD4+ T cell response

BackgroundThe increased activity of regulatory B cells (Breg) is known to be involved in immunosuppression during helminth infection, which is characterized by inducing IL-10-producing Breg cells. However, the current knowledge of B cell subsets differentiation and IL-10-independent immunoregulatory mechanisms of B cells in schistosomiasis is insufficient.MethodsBALB/c mice were percutaneously infected with cercariae for investigating the profile of B cell subsets during Schistosoma japonicum infection. B cells isolated from the spleen or peritoneal cavity were analyzed for the regulatory phenotype after stimulation with soluble egg antigens (SEA) in vitro. CD4+ T cells were then cocultured with B cells pretreated with or without anti-PD-L1 antibody for investigating the role of B cells from infected mice on regulating CD4+ T cells. Furthermore, the in vivo administration of anti-PD-L1 antibody was conducted to investigate the role of PD-L1 in regulating host immunity during infection.ResultsThe percentages of peritoneal and splenic B-1a cells, as well as marginal zone B (MZB) cells were decreased at eight and twelve weeks after infection compared to those from uninfected mice. In splenic B cells, TGF-β expression was increased at eight weeks but declined at twelve weeks of infection, and PD-L1 expression was elevated at both eight and twelve weeks of infection. In addition, SEA stimulation in vitro significantly promoted the expression of IL-10 in peritoneal B cells and CD5 in splenic B cells, and the SEA-stimulated splenic and peritoneal B cells preferentially expressed PD-L1 and TGF-β. The splenic B cells from infected mice were able to suppress the function of Th1 and Th2 cells in vitro but to expand the expression of Tfh transcription factor Bcl6, which was further enhanced by blocking PD-L1 of B cells before co-cultivation. Moreover, Th2 response and Bcl6 expression in CD4+ T cells were also increased in vivo by blocking PD-L1 after infection, although the hepatic pathology was slightly influenced.ConclusionsOur findings revealed that S. japonicum infection modulates the differentiation of B cell subsets that have the capability to affect the CD4+ T cell response. This study contributes to a better understanding of B cells immune response during schistosomiasis.

The immunologic Warburg effect: Evidence and therapeutic opportunities in autoimmunity.

Pro‐inflammatory signals induce metabolic reprogramming in innate and adaptive immune cells of both myeloid and lymphoid lineage, characterized by a shift to aerobic glycolysis akin to the Warburg effect first described in cancer. Blocking the switch to aerobic glycolysis impairs the survival, differentiation, and effector functions of pro‐inflammatory cell types while favoring anti‐inflammatory and regulatory phenotypes. Glycolytic reprogramming may therefore represent a selective vulnerability of inflammatory immune cells, providing an opportunity to modulate immune responses in autoimmune disease without broad toxicity in other tissues of the body. The mechanisms by which aerobic glycolysis and the balance between glycolysis and oxidative phosphorylation regulate immune responses have only begun to be understood, with many additional insights expected in the years to come. Immunometabolic therapies targeting aerobic glycolysis include both pharmacologic inhibitors of key enzymes and glucose‐restricted diets, such as the ketogenic diet. Animal studies support a role for these pharmacologic and dietary therapies for the treatment of autoimmune diseases, and in a few cases proof of concept has been demonstrated in human disease. Nonetheless, much more work is needed to establish the clinical safety and efficacy of these treatments.This article is categorized under:Biological Mechanisms > MetabolismTranslational, Genomic, and Systems Medicine > Translational MedicineBiological Mechanisms > Cell Signaling