Changes made in the 8th edition of the Guide for the Care and Use of Laboratory Animals included new recommendations for the amount of space for breeding female mice. Adopting the new recommendations required, in essence, the elimination of trio breeding practices for all institutions. Both public opinion and published data did not readily support the new recommendations. In response, the National Jewish Health Institutional Animal Care and Use Committee established a program to directly compare the effects of breeding format on mouse pup survival and growth. Our study showed an overall parity between trio and pairwise breeding formats on the survival and growth of the litters, suggesting that the housing recommendations for breeding female mice as stated in the current Guide for the Care and Use of Laboratory Animals should be reconsidered.
An elusive goal of cellular immune vaccines is the generation of large numbers of antigen-specific T cells in response to subunit immunization. A broad spectrum of cytokines and cell-surface costimulatory molecules are known to shape the programming, magnitude, and repertoire of T cells responding to vaccination. We show here that the majority of innate immune receptor agonist-based vaccine adjuvants unexpectedly depend on IL-27 for eliciting CD4(+) and CD8(+) T-cell responses. This is in sharp contrast to infectious challenge, which generates T-cell responses that are IL-27-independent. Mixed bone marrow chimera experiments demonstrate that IL-27 dependency is T cell-intrinsic, requiring T-cell expression of IL-27R?. Further, we show that IL-27 dependency not only dictates the magnitude of vaccine-elicited T-cell responses but also is critical for the programming and persistence of high-affinity T cells to subunit immunization. Collectively, our data highlight the unexpected central importance of IL-27 in the generation of robust, high-affinity cellular immune responses to subunit immunization.
Dendritic cells (DCs) are required for the induction of cytotoxic T cells (CTL). In most tissues, including the lung, the resident DCs fall into two types expressing the integrin markers CD103 and CD11b. The current supposition is that DC function is predetermined by lineage, designating the CD103(+) DC as the major cross-presenting DC able to induce CTL. Here we show that Poly I:C (TLR3 agonist) or R848 (TLR7 agonist) do not activate all endogenous DCs. CD11b(+) DCs can orchestrate a CTL response in vivo in the presence of a TLR7 agonist but not a TLR3 agonist, whereas CD103(+) DCs require ligation of TLR3 for this purpose. This selectivity does not extend to antigen cross-presentation for T-cell proliferation but is required for induction of cytotoxicity. Thus, we demonstrate that the ability of DCs to induce functional CTLs is specific to the nature of the pathogen-associated molecular pattern (PAMP) encountered by endogenous DC.
Evaluation and mitigation of the risk of immunogenicity to protein aggregates and particles in therapeutic protein products remains a primary concern for drug developers and regulatory agencies. To investigate how the presence of protein particles and the route of administration influence the immunogenicity of a model therapeutic protein, we measured the immune response in mice to injections of formulations of recombinant murine growth hormone (rmGH) that contained controlled levels of protein particles. Mice were injected twice over 6 weeks with rmGH formulations via the subcutaneous, intraperitoneal, or intravenous (i.v.) routes. In addition to soluble, monomeric rmGH, the samples prepared contained either nanoparticles of rmGH or both nano- and microparticles of rmGH.The appearance of anti-rmGH IgG1, IgG2a, IgG2b, IgG2c, and IgG3 titers following the second injection of both preparations implies that multiple mechanisms contributed to the immune response. No dependence of the immune response on particle size and distribution was observed. The immune response measured after the second injection was most pronounced when i.v. administration was used. Despite producing high anti-rmGH titers mice appeared to retain the ability to properly regulate and use endogenous growth hormone.
Antigen derived from viral infections with influenza and vesicular stomatitis virus can persist after resolution of infection. Here we show that antigen can similarly persist for weeks following viral challenge and vaccination. Antigen is captured by lymphatic endothelial cells (LECs) under conditions that induce LEC proliferation. Consistent with published data showing that viral antigen persistence impacts the function of circulating memory T cells, we find that vaccine-elicited antigen persistence, found on LECs, positively influences the degree of protective immunity provided by circulating memory CD8(+) T cells. The coupling of LEC proliferation and antigen capture identifies a mechanism by which the LECs store, or 'archive', antigens for extended periods of time after antigen challenge, thereby increasing IFN?/IL-2 production and enhancing protection against infection. These findings therefore have the potential to have an impact on future vaccination strategies and our understanding of the role for persisting antigen in both vaccine and infectious settings.
How T cell receptor (TCR) avidity influences CD8(+) T cell development and repertoire selection is not yet fully understood. To fill this gap, we utilized Src-like adaptor protein (SLAP)-deficient mice as a tool to increase TCR avidity on double positive (DP) thymocytes. We generated SLAP(-/-) mice with the transgenic MHC class I-restricted TCR (OT-1) and SLAP(-/-) V?5 mice, expressing only the ?-chain of the TCR OT-1 transgene, to examine the effects of increased TCR surface levels on CD8(+) T cell development and repertoire selection. In comparing SLAP(-/-) OT-1 and V?5 mice with wild-type controls, we performed compositional analysis and assessed thymocyte signaling by measuring CD5 levels. In addition, we performed tetramer and compositional staining to measure affinity for the cognate antigen, ovalbumin (OVA) peptide, presented by MHC. Furthermore, we quantified differences in ?-chain repertoire in SLAP(-/-) V?5 mice. We have found that SLAP(-/-) OT-1 mice have fewer CD8(+) thymocytes but have increased CD5 expression. SLAP(-/-) OT-1 mice have fewer DP thymocytes expressing V?2, signifying increased endogenous ?-chain rearrangement, and more non-OVA-specific CD8(+) splenocytes upon tetramer staining. Our data demonstrate that SLAP(-/-) V?5 mice also have fewer OVA-specific cells and increased V?2 usage in the peripheral V?5 CD8(+) T cells that were non-OVA-specific, demonstrating differences in ?-chain repertoire. These studies provide direct evidence that increased TCR avidity in DP thymocytes enhances CD8(+) T cell negative selection deleting thymocytes with specificity for cognate antigen, an antigen the mature T cells may never encounter. Collectively, these studies provide new insights into how TCR avidity during CD8(+) T cell development influences repertoire selection.
While the need for CD4 T cells in the generation of CD8 T cell memory has been well documented, the mechanism underlying their requirement remains unknown. Here, we detail an immunization method capable of generating CD8 memory T cells that are indifferent to CD4 T cell help. Using a subunit vaccination that combines polyIC and an agonistic CD40 antibody, we program protective CD4-independent CD8 T cell memory. When cells generated by combined polyIC/CD40 immunization are compared to cells produced following a CD4-dependent vaccination, Listeria monocytogenes, they display dramatic differences, both phenotypically and functionally. The memory cells generated in a CD4-deficient host by polyIC/CD40 immunization provide protection against secondary infectious challenge, whereas cells generated by LM immunization in the same environment do not. Interestingly, combined polyIC/CD40 immunization generates long-term memory cells with low Blimp-1 and elevated Eomes expression despite high expression of Blimp-1 during the primary response. The potency of combined polyIC/CD40 to elicit CD8+ T cell memory in the absence of CD4 T cells suggests that it could be considered as a vaccine adjuvant in clinical situations where CD4 responses/numbers are compromised.
Although most cases of chronic obstructive pulmonary disease (COPD) occur in smokers, only a fraction of smokers develop the disease. We hypothesized distinct molecular signatures for COPD and emphysema in the peripheral blood mononuclear cells (PBMCs) of current and former smokers. To test this hypothesis, we identified and validated PBMC gene expression profiles in smokers with and without COPD. We generated expression data on 136 subjects from the COPDGene study, using Affymetrix U133 2.0 microarrays (Affymetrix, Santa Clara, CA). Multiple linear regression with adjustment for covariates (gender, age, body mass index, family history, smoking status, and pack-years) was used to identify candidate genes, and ingenuity pathway analysis was used to identify candidate pathways. Candidate genes were validated in 149 subjects according to multiplex quantitative real-time polymerase chain reaction, which included 75 subjects not previously profiled. Pathways that were differentially expressed in subjects with COPD and emphysema included those that play a role in the immune system, inflammatory responses, and sphingolipid (ceramide) metabolism. Twenty-six of the 46 candidate genes (e.g., FOXP1, TCF7, and ASAH1) were validated in the independent cohort. Plasma metabolomics was used to identify a novel glycoceramide (galabiosylceramide) as a biomarker of emphysema, supporting the genomic association between acid ceramidase (ASAH1) and emphysema. COPD is a systemic disease whose gene expression signatures in PBMCs could serve as novel diagnostic or therapeutic targets.
Various populations of memory phenotype CD8(+) T cells have been described over the last 15-20 y, all of which possess elevated effector functions relative to naive phenotype cells. Using a technique for isolating Ag-specific cells from unprimed hosts, we recently identified a new subset of cells, specific for nominal Ag, but phenotypically and functionally similar to memory cells arising as a result of homeostatic proliferation. We show in this study that these virtual memory (VM) cells are independent of previously identified innate memory cells, arising as a result of their response to IL-15 trans presentation by lymphoid tissue-resident CD8?(+) dendritic cells in the periphery. The absence of IL-15, CD8(+) T cell expression of either CD122 or eomesodermin or of CD8a(+) dendritic cells all lead to the loss of VM cells in the host. Our results show that CD8(+) T cell homeostatic expansion is an active process within the nonlymphopenic environment, is mediated by IL-15, and produces Ag-inexperienced memory cells that retain the capacity to respond to nominal Ag with memory-like function. Preferential engagement of these VM T cells into a vaccine response could dramatically enhance the rate by which immune protection develops.
The hematopoietic humanized mouse (hu-mouse) model is a powerful resource to study and manipulate the human immune system. However, a major and recurrent issue with this model has been the poor maturation of B cells that fail to progress beyond the transitional B cell stage. Of interest, a similar problem has been reported in transplant patients who receive cord blood stem cells. In this study, we characterize the development of human B and T cells in the lymph nodes (LNs) and spleen of BALB/c-Rag2(null)Il2r?(null) hu-mice. We find a dominant population of immature B cells in the blood and spleen early, followed by a population of human T cells, coincident with the detection of LNs. Notably, in older mice we observe a major population of mature B cells in LNs and in the spleens of mice with higher T cell frequencies. Moreover, we demonstrate that T cells are necessary for B cell maturation, as introduction of autologous human T cells expedites the appearance of mature B cells, whereas in vivo depletion of T cells retards B cell maturation. The presence of the mature B cell population correlates with enhanced IgG and Ag-specific responses to both T cell-dependent and T cell-independent challenges, indicating their functionality. These findings enhance our understanding of human B cell development, provide increased details of the reconstitution dynamics of hu-mice, and validate the use of this animal model to study mechanisms and treatments for the similar delay of functional B cells associated with cord blood transplantations.
Type I IFNs are important for direct control of viral infection and generation of adaptive immune responses. Recently, direct stimulation of CD4(+) T cells via type I IFNR has been shown to be necessary for the formation of functional CD4(+) T cell responses. In contrast, we find that CD4(+) T cells do not require intrinsic type I IFN signals in response to combined TLR/anti-CD40 vaccination. Rather, the CD4 response is dependent on the expression of type I IFNR (IFN?R) on innate cells. Further, we find that dendritic cell (DC) expression of the TNF superfamily member OX40 ligand was dependent on type I IFN signaling in the DC, resulting in a reduced CD4(+) T cell response that could be substantially rescued by an agonistic Ab to the receptor OX40. Taken together, we show that the IFN?R dependence of the CD4(+) T cell response is accounted for exclusively by defects in DC activation.
Variant peptide vaccines are used clinically to expand T cells that cross-react with tumor-associated Ags (TAA). To investigate the effects of elevated endogenous TAA expression on variant peptide-induced responses, we used the GP70 TAA model. Although young BALB/c mice display T cell tolerance to the TAA GP70(423-431) (AH1), expression of GP70 and suppression of AH1-specific responses increases with age. We hypothesized that as TAA expression increases, the AH1 cross-reactivity of variant peptide-elicited T cell responses diminishes. Controlling for immunosenescence, we showed that elevated GP70 expression suppressed AH1 cross-reactive responses elicited by two AH1 peptide variants. A variant that elicited almost exclusively AH1 cross-reactive T cells in young mice elicited few or no T cells in aging mice with Ab-detectable GP70 expression. In contrast, a variant that elicited a less AH1 cross-reactive T cell response in young mice successfully expanded AH1 cross-reactive T cells in all aging mice tested. However, these T cells bound the AH1/MHC complex with a relatively short half-life and responded poorly to ex vivo stimulation with the AH1 peptide. Variant peptide vaccine responses were also suppressed when AH1 peptide is administered tolerogenically to young mice before vaccination. Analyses of variant-specific precursor T cells from naive mice with Ab-detectable GP70 expression determined that these T cells expressed PD-1 and had downregulated IL-7R? expression, suggesting they were anergic or undergoing deletion. Although variant peptide vaccines were less effective as TAA expression increases, data presented in this article also suggest that complementary immunotherapies may induce the expansion of T cells with functional TAA recognition.
Cells undergoing programmed cell death (apoptosis) are removed in situ by macrophages and dendritic cells (DCs) through a specialized form of phagocytosis (efferocytosis). In the lung, there are two primary DC subsets with the potential to migrate to the local lymph nodes (LNs) and initiate adaptive immune responses. In this study, we show that only CD103(+) DCs were able to acquire and transport apoptotic cells to the draining LNs and cross present apoptotic cell-associated antigen to CD8 T cells. In contrast, both the CD11b(hi) and the CD103(+) DCs were able to ingest and traffic latex beads or soluble antigen. CD103(+) DCs selectively exhibited high expression of TLR3, and ligation of this receptor led to enhanced in vivo cytotoxic T cell responses to apoptotic cell-associated antigen. The selective role for CD103(+) DCs was confirmed in Batf3(-/-) mice, which lack this DC subtype. Our findings suggest that CD103(+) DCs are the DC subset in the lung that captures and presents apoptotic cell-associated antigen under homeostatic and inflammatory conditions and raise the possibility for more focused immunological targeting to CD8 T cell responses.
Type I IFN and IL-12 are well documented to serve as so called "signal 3" cytokines, capable of facilitating CD8(+) T cell proliferation, effector function and memory formation. While their ability to serve in this capacity is well established, to date, no non-cytokine signal 3 mediators have been clearly identified. We have established a vaccine model system in which the primary CD8(+) T cell response is independent of either IL-12 or type I IFN receptors, but dependent on CD27/CD70 interactions. We show here that primary and secondary CD8(+) T cell responses are generated in the combined deficiency of IFN and IL-12 signaling. In contrast, antigen specific CD8(+) T cell responses are compromised in the absence of the TNF receptors CD27 and OX40. These data indicate that CD27/OX40 can serve the central function as signal 3 mediators, independent of IFN or IL-12, for the generation of CD8(+) T cell immune memory.
Conjugation of TLR agonists to protein or peptide antigens has been demonstrated in many studies to be an effective vaccine formula in inducing cellular immunity. However, the molecular and cellular mediators involved in TLR-induced immune responses have not been carefully examined. In this study, we identify Type I IFN and IL-12 as critical mediators of cross-priming induced by a TLR7 agonist-antigen conjugate. We demonstrate that TLR7-driven cross-priming requires both Type I IFN and IL-12. Signaling through the IFN-??R was required for the timely recruitment and accumulation of activated dendritic cells in the draining lymph nodes. Although IL-12 was indispensable during cross-priming, it did not regulate DC function. Therefore, the codependency for these 2 cytokines during TLR7-induced cross-priming is the result of their divergent effects on different cell-types. Furthermore, although dermal and CD8?(+) DCs were able to cross-prime CD8(+) T cells, Langerhans cells were unexpectedly found to potently cross-present antigen and support CD8(+) T-cell expansion, both in vitro and in vivo. Collectively, the data show that a TLR7 agonist-antigen conjugate elicits CD8(+) T-cell responses by the coordinated recruitment and activation of both tissue-derived and lymphoid organ-resident DC subsets through a Type I IFN and IL-12 codependent mechanism.
Development of effective new mucosal vaccine adjuvants has become a priority with the increase in emerging viral and bacterial pathogens. We previously reported that cationic liposomes complexed with non-coding plasmid DNA (CLDC) were effective parenteral vaccine adjuvants. However, little is known regarding the ability of liposome-nucleic acid complexes to function as mucosal vaccine adjuvants, or the nature of the mucosal immune responses elicited by mucosal liposome-nucleic acid adjuvants. To address these questions, antibody and T cell responses were assessed in mice following intranasal immunization with CLDC-adjuvanted vaccines. The effects of CLDC adjuvant on antigen uptake, trafficking, and cytokine responses in the airways and draining lymph nodes were also assessed. We found that mucosal immunization with CLDC-adjuvanted vaccines effectively generated potent mucosal IgA antibody responses, as well as systemic IgG responses. Notably, mucosal immunization with CLDC adjuvant was very effective in generating strong and sustained antigen-specific CD8(+) T cell responses in the airways of mice. Mucosal administration of CLDC vaccines also induced efficient uptake of antigen by DCs within the mediastinal lymph nodes. Finally, a killed bacterial vaccine adjuvanted with CLDC induced significant protection from lethal pulmonary challenge with Burkholderia pseudomallei. These findings suggest that liposome-nucleic acid adjuvants represent a promising new class of mucosal adjuvants for non-replicating vaccines, with notable efficiency at eliciting both humoral and cellular immune responses following intranasal administration.
Covalent conjugation of TLR agonists to protein Ags often facilitates the generation of a CD8(+) T cell response. However, mechanisms underlying the efficacy of the conjugate over its unconjugated counterpart have been largely uninvestigated. In this study, we show that conjugation of a TLR7 agonist enhances CD8(+) T cell responses without affecting Ag persistence and with minimal impact on cellular uptake of the Ag in vivo. Instead, the conjugated form induced a robust accumulation of dendritic cells (DCs) in regional lymph nodes. Perhaps more importantly, cross-presentation in DCs was detected only when the Ag was delivered in the conjugated form with the TLR7 agonist. Collectively, these data represent the first demonstration that a TLR agonist-Ag conjugate elicits CD8(+) T cell responses based not on its capacity to induce DC maturation or Ag persistence and uptake, but on the engagement of DC cross-presentation pathways.
The TNF superfamily members CD70 and OX40 ligand (OX40L) were reported to be important for CD4(+) T cell expansion and differentiation. However, the relative contribution of these costimulatory signals in driving CD4(+) T cell responses has not been addressed. In this study, we found that OX40L is a more important determinant than CD70 of the primary CD4(+) T cell response to multiple immunization regimens. Despite the ability of a combined TLR and CD40 agonist (TLR/CD40) stimulus to provoke appreciable expression of CD70 and OX40L on CD8(+) dendritic cells, resulting CD4(+) T cell responses were substantially reduced by Ab blockade of OX40L and, to a lesser degree, CD70. In contrast, the CD8(+) T cell responses to combined TLR/CD40 immunization were exclusively dependent on CD70. These requirements for CD4(+) and CD8(+) T cell activation were not limited to the use of combined TLR/CD40 immunization, because vaccinia virus challenge elicited primarily OX40L-dependent CD4 responses and exclusively CD70-dependent CD8(+) T cell responses. Attenuation of CD4(+) T cell priming induced by OX40L blockade was independent of signaling through the IL-12R, but it was reduced further by coblockade of CD70. Thus, costimulation by CD70 or OX40L seems to be necessary for primary CD4(+) T cell responses to multiple forms of immunization, and each may make independent contributions to CD4(+) T cell priming.
We have previously shown that Toll-like receptor (TLR) agonists cooperate with CD40 to generate CD8 T cell responses exponentially larger than the responses generated with traditional vaccine formulations. We have also shown that combined TLR agonist/anti-CD40 immunization uniquely induces the upregulation of CD70 on antigen bearing dendritic cells (DCs). In contrast, immunization with either a TLR agonist or a CD40 stimulus alone does not significantly increase CD70 expression on DCs. Furthermore, the CD8(+) T cell response generated by combined TLR agonist/anti-CD40 immunization is dependent on the expression of CD70 by DCs, as CD70 blockade following immunization dramatically decreases the CD8 T cell response. Here we show that other innate pathways, independent of the TLRs, can also cooperate with CD40 to induce potent, CD70 dependent, CD8 T cell responses. These innate stimuli include Type I IFN (IFN) and alpha-galactosylceramide (alphaGalCer) or aC-GalCer, glycolipids that are presented by a nonclassical class I MHC molecule, CD1d, and are able to activate NKT cells. Furthermore, this combined IFN/anti-CD40 immunization generates protective memory against bacterial challenge with Listeria monocytogenes. Together these data indicate the importance of assessing CD70 expression on DCs as a marker for the capacity of a given vaccine formulation to potently activate cellular immunity. Our data indicate that optimal induction of CD70 expression requires a coordinated stimulation of both innate (TLR, IFN, alphaGalCer) and adaptive (CD40) signaling pathways.
Suppressing the abnormalities associated with asthma has been difficult to accomplish using immunotherapy or vaccination once the disease is established. The effector cells necessary for effective immunization/vaccination and immunotherapy of asthma are also not well understood. Therefore, we vaccinated allergen (OVA)-sensitized mice to determine whether therapeutic immunization could suppress airway hyperresponsiveness (AHR) and inflammation and to identify key immune effector cells and cytokines. Mice were immunized with a vaccine comprised of Ag and cationic liposome-DNA complexes (CLDC), a vaccine which has previously been shown to elicit strong CD4(+) and CD8(+) T cell responses and activation of Th1 immunity. We showed that immunization with the OVA-CLDC vaccine significantly suppressed AHR, eosinophilia, goblet cell metaplasia, and Th2 cytokine production. In contrast, immunization with CLDC alone suppressed eosinophilia and Th2 cytokine production, but failed to suppress AHR and goblet cell changes. Using adoptive transfer experiments, we found that suppression of AHR was mediated by Ag-specific CD8(+) T cells and was dependent on IFN-gamma production by the transferred T cells. Thus, we conclude that generation of strong, allergen-specific CD8(+) T cell responses by immunization may be capable of suppressing AHR and allergic airway inflammation, even in previously sensitized and challenged mice.
The success of clinically relevant immunotherapies requires reversing tumor-induced immunosuppression. Here we demonstrated that linear polyethylenimine-based (PEI-based) nanoparticles encapsulating siRNA were preferentially and avidly engulfed by regulatory DCs expressing CD11c and programmed cell death 1-ligand 1 (PD-L1) at ovarian cancer locations in mice. PEI-siRNA uptake transformed these DCs from immunosuppressive cells to efficient antigen-presenting cells that activated tumor-reactive lymphocytes and exerted direct tumoricidal activity, both in vivo and in situ. PEI triggered robust and selective TLR5 activation in vitro and elicited the production of hallmark TLR5-inducible cytokines in WT mice, but not in Tlr5-/- littermates. Thus, PEI is a TLR5 agonist that, to our knowledge, was not previously recognized. In addition, PEI-complexed nontargeting siRNA oligonucleotides stimulated TLR3 and TLR7. The nonspecific activation of multiple TLRs (specifically, TLR5 and TLR7) reversed the tolerogenic phenotype of human and mouse ovarian tumor-associated DCs. In ovarian carcinoma-bearing mice, this induced T cell-mediated tumor regression and prolonged survival in a manner dependent upon myeloid differentiation primary response gene 88 (MyD88; i.e., independent of TLR3). Furthermore, gene-specific siRNA-PEI nanocomplexes that silenced immunosuppressive molecules on mouse tumor-associated DCs elicited discernibly superior antitumor immunity and enhanced therapeutic effects compared with nontargeting siRNA-PEI nanocomplexes. Our results demonstrate that the intrinsic TLR5 and TLR7 stimulation of siRNA-PEI nanoparticles synergizes with the gene-specific silencing activity of siRNA to transform tumor-infiltrating regulatory DCs into DCs capable of promoting therapeutic antitumor immunity.
Memory T cells exhibit superior responses to pathogens and tumors compared with their naive counterparts. Memory is typically generated via an immune response to a foreign antigen, but functional memory T cells can also be produced from naive cells by homeostatic mechanisms. Using a recently developed method, we studied CD8 T cells, which are specific for model (ovalbumin) and viral (HSV, vaccinia) antigens, in unimmunized mice and found a subpopulation bearing markers of memory cells. Based on their phenotypic markers and by their presence in germ-free mice, these preexisting memory-like CD44(hi) CD8 T cells are likely to arise via physiological homeostatic proliferation rather than a response to environmental microbes. These antigen-inexperienced memory phenotype CD8 T cells display several functions that distinguish them from their CD44(lo) counterparts, including a rapid initiation of proliferation after T cell stimulation and rapid IFN-gamma production after exposure to proinflammatory cytokines. Collectively, these data indicate that the unprimed antigen-specific CD8 T cell repertoire contains antigen-inexperienced cells that display phenotypic and functional traits of memory cells.
CD40L, the ligand for CD40 on dendritic cells (DCs), plays an important role in maturation and activation of DCs leading to induction of immune responses. Our previous studies showed that the mouse splenic CD4(-)8(-) DCs are tolerogenic and capable of stimulating suppressive type 1 CD4(+) regulatory T (Tr1) cell responses via TGF-beta secretion. In this study, we investigated whether CD40 ligation is able to convert tolerogenic CD4(-)8(-) DCs into immunogenic ones by in vitro treatment of DCs with anti-CD40 antibody. Our data showed that in vitro CD40 ligation with anti-CD40 antibody converted TGF-beta-secreting tolerogenic CD4(-)8(-) DCs into IL-12-secreting immunogenic ones capable of stimulating type 1 CD4(+) helper T (Th1) and CD8(+) cytotoxic T lymphocyte (CTL) responses leading to induction of antitumor immunity. In addition, in vivo CD40 ligation by intratumoral injection of adenoviral vector AdVCD40L expressing CD40 ligand also induced tumor growth inhibition and regression of established P815 tumors with infiltration of tolerogenic CD4(-)8(-) DCs. Therefore, our data provide new information for and may thus have useful impacts in CD40 ligation-based immunotherapy of cancer.
We re-examined the observation that ?? T cells, when transferred from mice tolerized to an inhaled conventional Ag, suppress the allergic IgE response to this Ag specifically. Using OVA and hen egg lysozyme in crisscross fashion, we confirmed the Ag-specific IgE-regulatory effect of the ?? T cells. Although only V?4(+) ?? T cells are regulators, the Ag specificity does not stem from specificity of their ?? TCRs. Instead, the V?4(+) ?? T cells failed to respond to either Ag, but rapidly acquired Ag-specific regulatory function in vivo following i.v. injection of non-T cells derived from the spleen of Ag-tolerized mice. This correlated with their in vivo Ag acquisition from i.v. injected Ag-loaded splenic non-T cells, and in vivo transfer of membrane label provided evidence for direct contact between the injected splenic non-T cells and the V?4(+) ?? T cells. Together, our data suggest that Ag itself, when acquired by ?? T cells, directs the specificity of their IgE suppression.
The objective of modern vaccine development is the safe generation of protective long-term immune memory, both prophylactic and therapeutic. Live attenuated vaccines generate potent cellular and humoral immunity [1-3], but numerous problems exist with these vaccines, ranging from production and storage issues to adverse reactions and reversion to virulence. Subunit vaccines are safer, more stable, and more amenable to mass production. However the protection they produce is frequently inferior to live attenuated vaccines and is typically confined to humoral, and not cellular immunity. Unfortunately, there are presently no subunit vaccines available clinically that are effective at eliciting cellular responses let alone cellular memory . This article will provide and overview of areas of investigation that we see as important for the development of vaccines with the capacity to induce robust and enduring cellular immune responses.
Myocarditis is commonly associated with cardiotropic infections and has been linked to development of autoimmunity. N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a naturally occurring tetrapeptide that prevents inflammation and fibrosis in hypertension and other cardiovascular diseases; however, its effect on autoimmune-mediated cardiac diseases remains unknown. We studied the effects of Ac-SDKP in experimental autoimmune myocarditis (EAM), a model of T cell-mediated autoimmune disease. This study was conducted to test the hypothesis that Ac-SDKP prevents autoimmune myocardial injury by modulating the immune responses. Lewis rats were immunized with porcine cardiac myosin and treated with Ac-SDKP or vehicle. In EAM, Ac-SDKP prevented both systolic and diastolic cardiac dysfunction, remodeling as shown by hypertrophy and fibrosis, and cell-mediated immune responses without affecting myosin-specific autoantibodies or antigen-specific T cell responses. In addition, Ac-SDKP reduced cardiac infiltration by macrophages, dendritic cells, and T cells, pro-inflammatory cytokines [interleukin (IL)-1?, tumor necrosis factor-?, IL-2, IL-17] and chemokines (cytokine-induced neutrophil chemoattractant-1, interferon-?-induced protein 10), cell adhesion molecules (intercellular adhesion molecule-1, L-selectin), and matrix metalloproteinases (MMP). Ac-SDKP prevents autoimmune cardiac dysfunction and remodeling without reducing the production of autoantibodies or T cell responses to cardiac myosin. The protective effects of Ac-SDKP in autoimmune myocardial injury are most likely mediated by inhibition of 1) innate and adaptive immune cell infiltration and 2) expression of proinflammatory mediators such as cytokines, chemokines, adhesion molecules, and MMPs.
Inflammation is thought to play a role in ischemic acute kidney injury (AKI). We have demonstrated that macrophage and dendritic cell depletion, using liposome-encapsulated clodronate (LEC), is protective against ischemic AKI.
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