Antigen-presenting Cells For Priming Research Articles

Combination of Metal-Phenolic Network-Based Immunoactive Nanoparticles and Bipolar Irreversible Electroporation for Effective Cancer Immunotherapy.

To circumvent the limitations of conventional cancer immunotherapy, it is critical to prime antigen-presenting cells (APCs) to initiate the cancer-immune cycle. Here, the authors develop a metal-phenolic network (MPN)-based immunoactive nanoparticle in combination with irreversible electroporation (IRE) for an effective cancer immunotherapy. The MPN nanoparticles are synthesized by coordinating tannic acid with manganese (Mn) ions, and subsequent coating with CpG-oligodeoxynucleotides (CpG-ODNs) via hydrogen bonding. The CpG-ODN-coated Mn-phenolic network (CMP) nanoparticles are effectively internalized into macrophages, a type of APCs, and successfully trigger M1 polarization to promote release of proinflammatory cytokines. Notably, the CMP nanoparticles demonstrate an extended retention time period than the free CpG-ODN in the tumor. The tumor microenvironment tailored bipolar IRE, enhances the therapeutic efficacy by significantly broadening the ablation zone, which further increases immunogenic cell death (ICD). Ultimately, the simultaneous CMP nanoparticles and IRE treatment successfully inhibit tumor growth and prolong survival in a mouse tumor model. Thus, CMP nanoparticles are empowered with Mn and CpG-ODN immunomodulators and the tumor microenvironment tailored bipolar IRE will be a new tool for effective cancer immunotherapy to treat intractable malignancies.

The immuno-reactivity of polypseudorotaxane functionalized magnetic CDMNP-PEG-CD nanoparticles.

pH‐magnetic dual‐responsive nanocomposites have been widely used in drug delivery and gene therapy. Recently, a polypseudorotaxane functionalized magnetic nanoparticle (MNP) was developed by synthesizing the magnetic nanoparticles with cyclodextrin (CD) molecules (CDMNP) via polyethylene glycol (PEG) (CDMNP‐PEG‐CD). The purpose of this study was to explore the antigenicity and immunogenicity of the nanoparticles in vivo prior to their further application explorations. Here, nanoparticles were assessed in vivo for retention, bio‐distribution and immuno‐reactivity. The results showed that, once administered intravenously, CDMNP‐PEG‐CD induced a temporary blood monocyte response and was cleared effectively from the body through the urine system in mice. The introduction of β‐CD and PEG/β‐CD polypseudorotaxane on SiO2 magnetic nanoparticles (SOMNP) limited particle intramuscular dispersion after being injected into mouse gastrocnemius muscle (GN), which led to the prolonged local inflammation and muscle toxicity by CDMNP and CDMNP‐PEG‐CD. In addition, T cells were found to be more susceptible for β‐CD–modified CDMNP; however, polypseudorotaxane modification partially attenuated β‐CD–induced T cell response in the implanted muscle. Our results suggested that CDMNP‐PEG‐CD nanoparticles or the decomposition components have potential to prime antigen‐presenting cells and to break the muscle autoimmune tolerance.

Role of B cells in TH cell responses in a mouse model of asthma

The importance of B lymphocytes to present antigens for antibody production is well documented. In contrast, very little is known about their capacity to influence CD4+ T-cell activation during a primary or secondary response to allergens. Using mouse models of asthma, we investigated the role of B cells as antigen-presenting cells in priming and maintenance of TH cell responses. Mice were immunized through the intranasal route with house dust mite (HDM) extract derived from Dermatophagoides pteronyssinus. B cells were depleted in HDM-sensitized animals to investigate the importance of B cells in maintenance of the allergic response. B cells were depleted before HDM sensitization to investigate the role of B cells in T-cell priming; furthermore, HDM sensitization was performed in mice with MHC class II expression restricted to the B-cell lineage. We found that B cells serve as potent antigen-presenting cells exvivo and restimulate invivo-primed HDM-specific TH cells. HDM antigens were taken up by B cells independently of B-cell receptor specificity, indicating that HDM uptake and antigen presentation to CD4+ T cells is not restricted to rare B cells carrying HDM-specific B cell receptors. B-cell depletion before HDM challenge in HDM-sensitized mice resulted in a dramatic reduction of allergic response, indicating the role of B cells in amplification of TH2 responses. In contrast, HDM sensitization of mice in which MHC class II expression was restricted to B cells revealed the inability of these cells to prime TH2 responses but highlighted their unexpected role in priming TH1 and TH17 responses. Collectively, these data reveal new mechanisms leading to initiation and exacerbation of the allergic response that might have implications for designing new therapeutic strategies to combat HDM allergy.

The absence of invariant chain in MHC II cancer vaccines enhances the activation of tumor-reactive type 1 CD4+ T lymphocytes

Activation of tumor-reactive T lymphocytes is a promising approach for the prevention and treatment of patients with metastatic cancers. Strategies that activate CD8(+) T cells are particularly promising because of the cytotoxicity and specificity of CD8(+) T cells for tumor cells. Optimal CD8(+) T cell activity requires the co-activation of CD4(+) T cells, which are critical for immune memory and protection against latent metastatic disease. Therefore, we are developing "MHC II" vaccines that activate tumor-reactive CD4(+) T cells. MHC II vaccines are MHC class I(+) tumor cells that are transduced with costimulatory molecules and MHC II alleles syngeneic to the prospective recipient. Because the vaccine cells do not express the MHC II-associated invariant chain (Ii), we hypothesized that they will present endogenously synthesized tumor peptides that are not presented by professional Ii(+) antigen presenting cells (APC) and will therefore overcome tolerance to activate CD4(+) T cells. We now report that MHC II vaccines prepared from human MCF10 mammary carcinoma cells are more efficient than Ii(+) APC for priming and boosting Type 1 CD4(+) T cells. MHC II vaccines consistently induce greater expansion of CD4(+) T cells which secrete more IFNgamma and they activate an overlapping, but distinct repertoire of CD4(+) T cells as measured by T cell receptor Vbeta usage, compared to Ii(+) APC. Therefore, the absence of Ii facilitates a robust CD4(+) T cell response that includes the presentation of peptides that are presented by traditional APC, as well as peptides that are uniquely presented by the Ii(-) vaccine cells.

Memory B Cells Specific for the NC16A Domain of the 180 kDa Bullous Pemphigoid Autoantigen Can Be Detected in Peripheral Blood of Bullous Pemphigoid Patients and Induced In Vitro to Synthesize Autoantibodies

Bullous pemphigoid is a subepidermal blistering disease characterized by the synthesis of autoantibodies against the 180 kDa and the 230 kDa bullous pemphigoid antigens. Whether autoimmunity is also reflected by the presence of circulating autoantigen-specific memory B cells is still a matter of debate. We used a new assay combining two-step immunomagnetic enrichment with multiparameter flow cytometry to detect and characterize bullous pemphigoid 180 kDa-specific IgG+ B cells in blood of bullous pemphigoid patients. In a first magnetic separation, B cells were isolated from peripheral blood mononuclear cells using releasable microbeads conjugated to a CD19 antibody. From pre-enriched B cells, bullous pemphigoid 180 kDa-specific cells were then positively selected using microbeads directly conjugated with a recombinant N-terminal fragment of the bullous pemphigoid 180 kDa ectodomain, containing the noncollagenous 16A domain, which was recently shown to harbor major epitopes of autoantibodies in bullous pemphigoid sera. Noncollagenous 16A domain-specific IgG+ B cells were detectable in blood of most, if not all patients with serum autoantibodies against the noncollagenous 16A domain. The specificity of the cells was confirmed by in vitro differentiation into antibody-forming cells and analysis of the culture supernatant for the presence of noncollagenous 16A domain-specific IgG antibodies. All noncollagenous 16A domain-specific IgG+ B cells showed a clear memory immunophenotype. Noncollagenous 16A domain-specific IgG+ memory B cells may be crucial for continuous noncollagenous 16A domain-specific autoantibody production and/or play a part as antigen-presenting cells for priming and restimulation of bullous pemphigoid 180 kDa-specific T helper cells.

Critical role for activation of antigen-presenting cells in priming of cytotoxic T cell responses after vaccination with virus-like particles.

Virus-like particles (VLPs) are known to induce strong Ab responses in the absence of adjuvants. In addition, VLPs are able to prime CTL responses in vivo. To study the efficiency of this latter process, we fused peptide p33 derived from lymphocytic choriomeningitis virus to the hepatitis B core Ag, which spontaneously assembles into VLPs (p33-VLPs). These p33-VLPs were efficiently processed in vitro and in vivo for MHC class I presentation. Nevertheless, p33-VLPs induced weak CTL responses that failed to mediate effective protection from viral challenge. However, if APCs were activated concomitantly in vivo using either anti-CD40 Abs or CpG oligonucleotides, the CTL responses induced were fully protective against infection with lymphocytic choriomeningitis virus or recombinant vaccinia virus. Moreover, these CTL responses were comparable to responses generally induced by live vaccines, because they could be measured in primary ex vivo (51)Cr release assays. Thus, while VLPs alone are inefficient at inducing CTL responses, they become very powerful vaccines if applied together with substances that activate APCs.

Role of donor and recipient antigen-presenting cells in priming and maintaining T cells with indirect allospecificity.

It has been suggested that the sensitization of recipient T lymphocytes against peptides derived from allogeneic major histocompatibility complex (MHC) antigens in the context of self-MHC molecules may contribute to the pathogenesis of chronic allograft rejection. The purpose of this study was to quantitate and characterize the indirect alloresponse in renal transplantation. An HLA-A2-negative patient whose A2-positive kidney transplant failed as a result of chronic rejection was selected for this study. T-cell clones were raised using a cocktail of peptides corresponding to polymorphic regions of the A2 sequence and studied by measuring their proliferation using [3H]thymidine incorporation. The presence in vivo of HLA-A2-specific T cells was assessed using limiting dilution analysis. T-cell clones were specific for a single peptide of HLA-A2, residues 92-120, and restricted by HLA-DRB1*1502. The frequency of interleukin-2-secreting T cells specific for this A2 peptide was 1:86,000, only 2-fold lower than that measured against the recall antigen tetanus toxoid. Capitalizing on the similarity of the donor and recipient DR15 alleles (DRB1*1501 and 1502), the question was addressed as to how these T cells had been primed in vivo. Although the large majority of clones responded to A2 synthetic peptide presented by both DR15 alleles, only 3 of 10 clones responded to cells co-expressing DRB1*1501 and A2. These data suggest that antigen presentation by recipient APCs is responsible for maintaining T cells with indirect allospecificity in vivo and that, in the context of partial DR matching, indirect presentation by the parenchymal cells of the graft may serve to induce tolerance in T cells with indirect allospecificity.