Antigen processing and presentation by macrophages

Human anti-PSCA CAR macrophages possess potent antitumor activity against pancreatic cancer

Due to the limitations of autologous chimeric antigen receptor (CAR)-T cells, alternative sources of cellular immunotherapy, including CAR macrophages, are emerging for solid tumors. Human induced pluripotent stem cells (iPSCs) offer an unlimited source for immune cell generation. Here, we develop human iPSC-derived CAR macrophages targeting prostate stem cell antigen (PSCA) (CAR-iMacs), which express membrane-bound interleukin (IL)-15 and truncated epidermal growth factor receptor (EGFR) for immune cell activation and a suicide switch, respectively. These allogeneic CAR-iMacs exhibit strong antitumor activity against human pancreatic solid tumors in vitro and in vivo, leading to reduced tumor burden and improved survival in a pancreatic cancer mouse model. CAR-iMacs appear safe and do not exhibit signs of cytokine release syndrome or other in vivo toxicities. We optimized the cryopreservation of CAR-iMac progenitors that remain functional upon thawing, providing an off-the-shelf, allogeneic cell product that can be developed into CAR-iMacs. Overall, our preclinical data strongly support the potential clinical translation of this human iPSC-derived platform for solid tumors, including pancreatic cancer.

Interferon therapy and its association with depressive disorders - A review

Interferons (IFNs) are important in controlling the innate immune response to viral infections. Besides that, studies have found that IFNs also have antimicrobial, antiproliferative/antitumor and immunomodulatory effects. IFNs are divided into Type I, II and III. Type I IFNs, in particular IFN-α, is an approved treatment for hepatitis C. However, patients developed neuropsychological disorders during treatment. IFN-α induces proinflammatory cytokines, indoleamine 2,3-dioxygenase (IDO), oxidative and nitrative stress that intensifies the body's inflammatory response in the treatment of chronic inflammatory disease. The severity of the immune response is related to behavioral changes in both animal models and humans. Reactive oxygen species (ROS) is important for synaptic plasticity and long-term potentiation (LTP) in the hippocampus. However, excess ROS will generate highly reactive free radicals which may lead to neuronal damage and neurodegeneration. The limbic system regulates memory and emotional response, damage of neurons in this region is correlated with mood disorders. Due to the drawbacks of the treatment, often patients will not complete the treatment sessions, and this affects their recovery process. However, with proper management, this could be avoided. This review briefly describes the different types of IFNs and its pharmacological and clinical usages and a focus on IFN-α and its implications on depression.

From peripherally unsubstituted subphthalocyanines with anti-inflammatory activity on macrophages to tri-iodo derivatives with adjuvant and immunostimulatory functions

In this study we evaluated the impact of iodine substitution on the ability of subphthalocyanines (SubPc) to stimulate or regulate the function of macrophages. Previous studies have focused on the usage of phthalocyanines and their derivatives as treatment options against different types of cancer. In order to obtain better prognosis rates, their possible effects on the immune system cells should be delineated. Unique subphthalocyanines were designed and synthesized by our group and a derivative was generated via iodine substitution. In our study we further tested the effects of the new Subpcs on macrophage cell lines. Macrophages play an important role in the immune system through cytokine production and antigen presentation to other types of the immune system cells. They can define the type and the strength of the immune responses against a particular danger signal. Based on pro-inflammatory cytokine (TNF[Formula: see text], IL1[Formula: see text] and IL6) production levels by macrophages, unsubstituted SubPc had anti-inflammatory properties. However, iodine substitution on the same SubPc created a completely opposite effect since these iodo-substituted SubPc exerted an immunostimulatory effect on macrophages based on significant increases in the pro-inflammatory cytokine production levels compared to the untreated controls. While SubPcs can be used to suppress the pro-inflammatory activities of the macrophages, iodine-substituted SubPcs have potentials to be used as adjuvants and immunostimulatory molecules.

Macrophages as stimulators of MART-1 27-35 epitope-specific human cytolytic T lymphocytes in vitro

BACKGROUND

Activation and expansion of antigen-specific cytolytic T lymphocytes (CTL) require epitope presented by antigen-presenting cells (APC). Presently, dendritic cells (DC) are viewed as the most efficient APC. Since the recognition of DCs as the professional APC, the paradigm has emerged that macrophage (MPhi) are scavengers and are incapable of activating T cells.

METHOD

The melanoma-associated MART-1(27-35) peptide-loaded MPhi from HLA-A2-positive donors were used to activate MART-1(27-35) epitope-specific CTL in vitro.

RESULTS

We show that peptide-pulsed MPhi stimulate MART-1(27-35) epitope-specific precursors to proliferate and to express effector functions. We also show that upon restimulation with the peptide pulsed MPhi, a fraction of the epitope-specific CTLs undergoes activation-induced cell death. The activation-induced cell death is induced in an epitope-specific manner and through apoptosis.

CONCLUSION

MPhi can function as APC and are also capable of modulating expansion and contraction of CTL response in vitro.

Spatial separation of HLA-DM/HLA-DR interactions within MIIC and phagosome-induced immune escape

Major Histocompatibility Complex (MHC) class II molecules, including Human Leukocyte Antigen (HLA)-DR, present peptide fragments from proteins degraded in the endocytic pathway. HLA-DR is targeted to late-endocytic structures named MHC class II-containing Compartments (MIIC), where it interacts with HLA-DM. This chaperone stabilizes HLA-DR during peptide exchange and is critical for successful peptide loading. To follow this process in living cells, we have generated cells containing HLA-DR3/Cyan Fluorescent Protein (CFP), HLA-DM/Yellow Fluorescent Protein (YFP), and invariant chain. HLA-DR/DM interactions were observed by Fluorescence Resonance Energy Transfer (FRET). These interactions were pH insensitive, yet occurred only in internal structures and not at the limiting membrane of MIIC. In a cellular model of infection, phagosomes formed a limiting membrane surrounding internalized Salmonella. HLA-DR and HLA-DM did not interact in Salmonella-induced vacuoles, and HLA-DR was not loaded with antigens. The absence of HLA-DR/DM interactions at the limiting membrane prevents local loading of MHC class II molecules in phagosomes. This may allow these bacteria to successfully evade the immune system.

Antigen Stability Controls Antigen Presentation

We investigated whether protein stability controls antigen presentation using a four disulfide-containing snake toxin and three derivatives carrying one or two mutations (L1A, L1A/H4Y, and H4Y). These mutations were anticipated to increase (H4Y) or decrease (L1A) the antigen non-covalent stabilizing interactions, H4Y being naturally and frequently observed in neurotoxins. The chemically synthesized derivatives shared similar three-dimensional structure, biological activity, and T epitope pattern. However, they displayed differential thermal unfolding capacities, ranging from 65 to 98 degrees C. Using these differentially stable derivatives, we demonstrated that antigen stability controls antigen proteolysis, antigen processing in antigen-presenting cells, T cell stimulation, and kinetics of expression of T cell determinants. Therefore, non-covalent interactions that control the unfolding capacity of an antigen are key parameters in the efficacy of antigen presentation. By affecting the stabilizing interaction network of proteins, some natural mutations may modulate the subsequent T-cell stimulation and might help microorganisms to escape the immune response.

Mathematical modeling of T-cell proliferation

A mathematical model of the T-lymphocyte proliferation process (in vivo and in vitro) is presented. This model takes into account cell-cycle progression and the regulation by lymphokines (lymphocyte activating factor interleukin 1 and T-cell growth factor interleukin 2). Using data on the generalized picture of the short-term course of viral hepatitis B, the parameter estimation procedure is carried out. The possibility of immunocorrection (by means of injection of a pharmacologic dose of IL-2) during the immune response to viral hepatitis B with T-lymphocyte deficiency is shown.

Mathematical model of antiviral immune response. I. Data analysis, generalized picture construction and parameters evaluation for hepatitis B

The present approach to the mathematical modelling of infectious diseases is based upon the idea that specific immune mechanisms play a leading role in development, course, and outcome of infectious disease. The model describing the reaction of the immune system to infectious agent invasion is constructed on the bases of Burnet's clonal selection theory and the co-recognition principle. The mathematical model of antiviral immune response is formulated by a system of ten non-linear delay-differential equations. The delayed argument terms in the right-hand part are used for the description of lymphocyte division, multiplication and differentiation processes into effector cells. The analysis of clinical and experimental data allows one to construct the generalized picture of the acute form of viral hepatitis B. The concept of the generalized picture includes a quantitative description of dynamics of the principal immunological, virological and clinical characteristics of the disease. Data of immunological experiments in vitro and experiments on animals are used to obtain estimates of permissible values of model parameters. This analysis forms the bases for the solution of the parameter identification problem for the mathematical model of antiviral immune response which will be the topic of the following paper (Marchuk et al., 1991, J. theor. Biol. 15).

Role of monocytes in anti-CD3-induced T-cell DNA synthesis: effect of chloroquine and monensin on anti-CD3-induced human T-cell activation

Anti-CD3 monoclonal antibody (MoAb) induces proliferation of freshly isolated peripheral blood T cells only in the presence of monocytes/macrophages and requires binding of the Fc portion of antibody to monocytes/macrophages. In this investigation, we examined whether monocytes process anti-CD3 similar to any soluble antigen and present to T cells in context with HLA-DR to induce maximal DNA synthesis. Adherent monocytes were pulsed with anti-CD3 MoAb in the presence or absence of the lysozomotropic agents chloroquine and monensin, which are known to inhibit processing of soluble antigens, washed extensively, and then incubated with autologous T cells in the absence of soluble anti-CD3, and 3H-thymidine incorporation and CD25 expression were measured. Both monensin and chloroquine inhibited anti-CD3-pulsed monocyte-induced T-cell DNA synthesis and CD25 expression in a dose-dependent manner. This inhibitory effect was not due to any loss in cell viability or the effect on the expression of HLA-DR on monocytes. Paraformaldehyde-fixed monocytes pulsed with anti-CD3 MoAb induced significantly less DNA synthesis, HLA-DR expression, and CD25 antigen expression on autologous T cells as compared to responses induced by unfixed anti-CD3-pulsed monocytes. The treatment of anti-CD3-pulsed monocytes with framework-specific anti-HLA-DR MoAb inhibited their capacity to induce T-cell DNA synthesis. These data suggest that monocytes, in addition to serving as the matrix for cross-linking, also process anti-CD3 MoAb and present to the T cells in the context of HLA-DR antigens to induce optimal DNA synthesis.

Biodegradable microspheres. III: some immunological properties of polyacryl starch microparticles

The antibody responses against empty polyacryl starch microparticles and the corresponding human serum albumin (HSA)-containing microparticles were followed in mice for 30 weeks. Empty polyacryl starch microparticles were nonimmunogenic as determined by a direct, enzyme-linked immunosorbent assay (ELISA). However, when the previously nonimmunogenic particle matrix was presented to the immune system together with entrapped HSA, an antibody response was detected not only against the protein antigen, but also against the microparticles matrix as detected in an inhibition ELISA. The spheres were good adjuvants for the foreign protein (HSA) and gave nearly the same response as that obtained with Freund's complete adjuvant (FCA), while the corresponding free antigen showed no or poor immunogenicity. The effects of the microparticles on lymphocytes and macrophages were also investigated. Empty microspheres were weakly stimulatory to lymphocytes. Moreover, they stimulated macrophages to release interleukin 1 in vitro.

The biology of human cytomegalovirus infection after bone marrow transplantation

Human cytomegalovirus (HCMV) infection remains the most common infectious cause of morbidity after bone marrow transplantation (BMT). In a prospective study of 127 BMT recipients who received blood cultures for HCMV between days 28 to 105 after marrow grafting, HCMV viremia occurred in 68 patients (53.4%). Twenty patients (15.7%) had one or two positive cultures, and 48 (37.7%) had greater than or equal to three positive cultures. Fifty-nine patients (46.4%) had no viremia. HCMV-associated interstitial pneumonia (HCMV-IP) occurred in one-third of the viremic patients. Quantitative measurements of infectious HCMV or of HCMV DNA in lung tissue were made to determine whether HCMV replication correlated with clinical disease. Using DNA probes, viral DNA was measured by dot-blot hybridization, and this correlated with infectious HCMV. However, neither HCMV DNA nor HCMV viral titer correlated with time from the onset of pneumonia to death. The hypothesis is presented that HCMV-IP is caused by immunologic events induced after HCMV infection. In this model HCMV alterations in recipient cell surfaces induce donor alloreactivity to minor histocompatibility differences and lead to the subsequent pneumonitis which we term HCMV-IP. This model suggests that prevention of HCMV-IP will require early use of antiviral therapy or late use of immune response modification.