Sustained Immune Response Research Articles

Ultra-miniature ultra-compliant neural probes with dissolvable delivery needles: design, fabrication and characterization.

Stable chronic functionality of intracortical probes is of utmost importance toward realizing clinical application of brain-machine interfaces. Sustained immune response from the brain tissue to the neural probes is one of the major challenges that hinder stable chronic functionality. There is a growing body of evidence in the literature that highly compliant neural probes with sub-cellular dimensions may significantly reduce the foreign-body response, thereby enhancing long term stability of intracortical recordings. Since the prevailing commercial probes are considerably larger than neurons and of high stiffness, new approaches are needed for developing miniature probes with high compliance. In this paper, we present design, fabrication, and in vitro evaluation of ultra-miniature (2.7μm x 10μm cross section), ultra-compliant (1.4 × 10-2 μN/μm in the axial direction, and 2.6 × 10-5 μN/μm and 1.8 × 10-6 μN/μm in the lateral directions) neural probes and associated probe-encasing biodissolvable delivery needles toward addressing the aforementioned challenges. The high compliance of the probes is obtained by micron-scale cross-section and meandered shape of the parylene-C insulated platinum wiring. Finite-element analysis is performed to compare the strains within the tissue during micromotion when using the ultra-compliant meandered probes with that when using stiff silicon probes. The standard batch microfabrication techniques are used for creating the probes. A dissolvable delivery needle that encases the probe facilitates failure-free insertion and precise placement of the ultra-compliant probes. Upon completion of implantation, the needle gradually dissolves, leaving behind the ultra-compliant neural probe. A spin-casting based micromolding approach is used for the fabrication of the needle. To demonstrate the versatility of the process, needles from different biodissolvable materials, as well as two-dimensional needle arrays with different geometries and dimensions, are fabricated. Further, needles incorporating anti-inflammatory drugs are created to show the co-delivery potential of the needles. An automated insertion device is developed for repeatable and precise implantation of needle-encased probes into brain tissue. Insertion of the needles without mechanical failure, and their subsequent dissolution are demonstrated. It is concluded that ultra-miniature, ultra-compliant probes and associated biodissolvable delivery needles can be successfully fabricated, and the use of the ultra-compliant meandered probes results in drastic reduction in strains imposed in the tissue as compared to stiff probes, thereby showing promise toward chronic applications.

Targeting cells of the immune system: mannosylated HPMA-LMA block-copolymer micelles for targeting of dendritic cells.

Successful tumor immunotherapy depends on the induction of strong and sustained tumor antigen-specific immune responses by activated antigen-presenting cells (APCs) such as dendritic cells (DCs). Since nanoparticles have the potential to codeliver tumor-specific antigen and DC-stimulating adjuvant in a DC-targeting manner, we wanted to assess the suitability of mannosylated HPMA-LMA block polymers for immunotherapy. Fluorescence-labeled block copolymer micelles derived from P(HPMA)-block-P(LMA) copolymers and according statistical copolymers were synthesized via RAFT polymerization, and loaded with the APC activator L18-MDP. Both types of copolymers were conjugated with D-mannose to target the mannose receptor as expressed by DCs and macrophages. The extent and specificity of micelle binding and activation of APCs was monitored using mouse spleen cells and bone marrow-derived DC (BMDC). Nontargeting HPMA-LMA statistical copolymers showed strong unspecific cell binding. HPMA-LMA block copolymers bound DC only when conjugated with mannose, and in a mannose receptor-specific manner. Mannosylated HPMA-LMA block copolymers were internalized by DC. DC-targeting HPMA-LMA block copolymers mediated DC activation when loaded with L18-MDP. Mannosylated HPMA-LMA block copolymers are a promising candidate for the delvopment of DC-targeting nanovaccines.

Molecular and Cellular Responses to Interleukin-4 Treatment in a Rat Model of Transient Ischemia.

Within hours after stroke, potentially cytotoxic pro-inflammatory mediators are elevated within the brain; thus, one potential therapeutic strategy is to reduce them and skew the brain toward an anti-inflammatory state. Because interleukin-4 (IL-4) treatment induces an anti-inflammatory, “alternative-activation” state in microglia and macrophages in vitro, we tested the hypothesis that early supplementation of the brain with IL-4 can shift it toward an anti-inflammatory state and reduce damage after transient focal ischemia. Adult male rat striata were injected with endothelin-1, with or without co-injection of IL-4. Inflammation, glial responses and damage to neurons and white matter were quantified from 1 to 7 days later. At 1 day, IL-4 treatment increased striatal expression of several anti-inflammatory markers (ARG1, CCL22, CD163, PPARγ), increased phagocytic (Iba1-positive, CD68-positive) microglia/macrophages, and increased VEGF-A-positive infiltrating neutrophils in the infarcts. At 7 days, there was evidence of sustained, propagating responses. IL-4 increased CD206, CD200R1, IL-4Rα, STAT6, PPARγ, CD11b, and TLR2 expression and increased microglia/macrophages in the infarct and astrogliosis outside the infarct. Neurodegeneration and myelin damage were not reduced, however. The sustained immune and glial responses when resolution and repair processes have begun warrant further studies of IL-4 treatment regimens and long-term outcomes.

3D models and omics approaches to study developmental neurotoxicity

Amyotrophic lateral sclerosis (ALS) is a rare neurodegenerative disease that primarily affects motor neurons and is accompanied by sustained unregulated immune responses, but without clear indications of the ultimate causative mechanisms. The identification of a diverse array of ALS phenotypes, a series of recently discovered mutations, and the links between ALS and frontotemporal degeneration have significantly increased our knowledge of the disease. In this review we discuss the main features involved in ALS pathophysiology in the context of recent advances in ‘omics’ approaches, including genomics, proteomics, and others. We emphasize the pressing need to combine clinical imaging with various different parameters taken from omics fields to facilitate early, accurate diagnosis and rational drug design in the treatment of ALS.

Abstract SY28-01: Immunotherapy in combination with neoadjuvant therapy and immune-related adverse events

Abstract Immunotherapy has recently entered a renaissance phase with the approval of multiple agents for the treatment of cancer. Immunotherapy stands ready to join traditional modalities, including surgery, chemotherapy, radiation, and hormone therapy, as a pillar of cancer treatment. Although immunotherapy has begun to have success in advanced cancer treatment, its scheduling and efficacy with conventional therapies, such as surgery, has not been systematically examined. Here, we have used two models of spontaneously metastatic breast cancers in mice to compare the therapeutic power of neoadjuvant versus adjuvant immunotherapies in the context of primary tumor resection. Therapies, including Treg depletion, anti-PD-1 or anti-PD1/anti-CD137 combinations were evaluated. Elevated and sustained peripheral tumor-specific immune responses underpinned the outcome, and blood sampling of tumor-specific CD8+ T cells immediately prior to and post surgery may provide a predictor of outcome. New combination immunotherapies are displaying both efficacy and immune-related adverse events (irAEs) in humans. Prolonged T regulatory cell (Treg) depletion in tumor bearing Foxp3-DTR mice using diphtheria toxin (DT) mirrored the spectrum of antitumor responses and severity of irAEs that can occur in ipilimumab/nivolumab treated patients, while transient Treg depletion and anti-CTLA-4/PD-1 therapy had equivalent effects in mice, lowering the immune tolerance threshold and allowing irAEs to be more easily provoked following treatment with additional immunomodulatory antibodies. This platform has been used to compare a number of promising immunotherapies. Citation Format: Mark J. Smyth, Jing Liu, Stephen J. Blake, Michele WL Teng. Immunotherapy in combination with neoadjuvant therapy and immune-related adverse events. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr SY28-01.

Early injury of the neonatal lung contributes to premature lung aging: a hypothesis.

Chronic lung disease of the newborn, also known as bronchopulmonary dysplasia (BPD), is the most common chronic lung disease in early infancy and results in an increased risk for long-lasting pulmonary impairment in the adult. BPD develops upon injury of the immature lung by oxygen toxicity, mechanical ventilation, and infections which trigger sustained inflammatory immune responses and extensive remodeling of the extracellular matrix together with dysregulated growth factor signaling. Histopathologically, BPD is characterized by impaired alveolarization, disrupted vascular development, and saccular wall fibrosis. Here, we explore the hypothesis that development of BPD involves disturbance of conserved pathways of molecular aging that may contribute to premature aging of the lung and an increased susceptibility to chronic lung diseases in adulthood.

Inflammation, immune activation, and cardiovascular disease in HIV.

Cardiovascular disease is one of the leading causes of morbidity and mortality in people living with HIV. Several epidemiological studies have shown an increased risk of myocardial infarction and stroke compared to uninfected controls. Although traditional risk factors contribute to this increased risk of cardiovascular disease, HIV-specific mechanisms likely also play a role. Systemic inflammation has been linked to cardiovascular disease in several populations suffering from chronic inflammation, including people living with HIV. Although antiretroviral therapy reduces immune activation, levels of inflammatory markers remain elevated compared to uninfected controls. The causes of this sustained immune response are likely multifactorial and incompletely understood. In this review, we summarize the evidence describing the relationship between inflammation and cardiovascular disease and discuss potential anti-inflammatory treatment options for cardiometabolic disease in people living with HIV.

Gene expression profiling in melanised sites of Atlantic salmon fillets.

Black spots, which deteriorate quality of Atlantic salmon fillets represent a significant problem for commercial aquaculture. These areas are characterized with accumulation of melanomacrophages, occasional formation of granulomas and substitution of skeletal muscle with connective tissue. A number of possible causative agents have been suggested including vaccination and infection with piscine reovirus (PRV). We report transcriptome profiling of melanised foci with oligonucleotide DNA microarrays. Analyses revealed a multitude of differentially expressed genes associated with melanogenesis, metabolic changes and formation of scar. The immune profile was characterized with inflammation, preferential activation of classical complement pathway, MHCII and helper T cells combined with strong B cells responses and massive induction of immunoglobulins; innate antiviral responses were relatively weak in sharp contrast to PRV-caused heart and skeletal muscle inflammation and other viral infections. A panel of immune genes with specific activation in dark spots was found, most up-regulated were CD209-like lectin (44-fold) and prostaglandin reductase (11-fold). Further, RNA sequencing was performed on the same material to search for the presence of putative pathogens. Transcripts of prokaryotic rRNA with exclusive or preferential location in black spots were found. Results suggest mild chronic inflammation initiated with trauma, bacterial or viral infection followed by sustained immune responses to opportunistic microorganisms as a realistic scenario of dark spots formation.

Pulmonary immunity and durable protection induced by the ID93/GLA-SE vaccine candidate against the hyper-virulent Korean Beijing Mycobacterium tuberculosis strain K

The majority of tuberculosis (TB) vaccine candidates advanced to clinical trials have been evaluated preclinically using laboratory-adapted strains. However, it has been proposed that challenge with clinical isolates in preclinical vaccine testing could provide further and more practical validation. Here, we tested the ID93/GLA-SE TB vaccine candidate against the clinical Mycobacterium tuberculosis (Mtb) strain K (Mtb K) belonging to the Beijing family, the most prevalent Mtb strain in South Korea. Mice immunized with ID93/GLA-SE exhibited a significant reduction in bacteria and reduced lung inflammation against Mtb K when compared to non-immunized controls. In addition, we analyzed the immune responses in the lungs of ID93/GLA-SE-immunized mice, and showed that ID93/GLA-SE was able to elicit sustained Th1-biased immune responses including antigen-specific multifunctional CD4+ T cell co-producing IFN-γ, TNF-α, and IL-2 as well as a high magnitude of IFN-γ response for up to 10 weeks post-challenge. Notably, further investigation of T cell subsets in the lung following challenge showed remarkable generation of CD8+ central memory T cells by ID93/GLA-SE-immunization. Our findings showed that ID93/GLA-SE vaccine confers a high level of robust protection against the hypervirulent Mtb Beijing infection which was characterized by pulmonary Th1-polarized T-cell immune responses. These findings may also provide relevant information for potential utility of this vaccine candidate in East-Asian countries where the Beijing genotype is highly prevalent.

Original Research: Parvovirus B19 infection in children with sickle cell disease in the hydroxyurea era.

Parvovirus B19 infection causes transient aplastic crisis in sickle cell disease (SCD) due to a temporary interruption in the red blood cell production. Toxicity from hydroxyurea includes anemia and reticulocytopenia, both of which also occur during a transient aplastic crisis event. Hydroxyurea inhibits proliferation of hematopoietic cells and may be immunosuppressive. We postulated that hydroxyurea could exacerbate parvovirus B19-induced aplastic crisis and inhibit the development of specific immune responses in children with SCD. We conducted a retrospective review of parvovirus B19 infection in 330 children with SCD. Altogether there were 120 known cases of aplastic crisis attributed to parvovirus B19 infection, and 12% of children were on hydroxyurea treatment during the episode. We evaluated hematological and immune responses. Children with HbSS or HbSβ(0)-thalassemia treated with hydroxyurea, when compared with untreated children, required fewer transfusions and had higher Hb concentration nadir during transient aplastic crisis. Duration of hospital stays was no different between hydroxyurea-treated and untreated groups. Children tested within a week following aplastic crisis were positive for parvovirus-specific IgG. Immune responses lasted for the duration of the observation period, up to 13 years after transient aplastic crisis, and there were no repeat aplastic crisis episodes. The frequencies of parvovirus-specific antibodies in all children with SCD increased with age, as expected due to the increased likelihood of a parvovirus exposure, and were comparable to frequencies reported for healthy children. Approximately one-third of children had a positive parvovirus B19-specific IgG test without a documented history of transient aplastic crisis, and 64% of them were treated with hydroxyurea. Hydroxyurea may reduce requirements for blood transfusions and may attenuate symptoms during transient aplastic crisis episodes caused by parvovirus B19 infections. Children with SCD, whether treated or untreated with hydroxyurea, generate sustained and protective parvovirus B19-specific immune responses.

Immune activation in the central nervous system throughout the course of HIV infection.

Robust and dynamic innate and adaptive responses characterize the acute central nervous system (CNS) response to HIV and other viral infections. In a state of chronic infection or viral latency, persistent immune activation associates with abnormality in the CNS. Understanding this process is critical, as immune-mediated abnormality in nonrenewable CNS cells may result in long-term neurologic sequelae for HIV-infected individuals. In humans, immune activation is reduced by suppressive combination antiretroviral therapy, but persists at abnormally elevated levels on treatment. CNS immune activation is initiated in acute infection and progressively increases until combination antiretroviral therapy is started. Newly identified characteristics of the CNS immune surveillance network include features of homeostasis and function of brain microglial cells, lymphatic drainage from CNS to cervical lymph nodes, and cells in cerebrospinal fluid associated with neurocognitive impairment. More research is required to determine whether early intervention to reduce infection limits the immunopathology established by sustained immune responses that ultimately fail to resolve infection, and to unravel mechanisms of persistent immune activation during treated HIV so that strategies can be developed to therapeutically protect the brain.

A Single Dose TMV-HA Vaccine Protects Mice from H5N1 Influenza Challeng

Recombinant subunit vaccines are an efficient strategy to meet the demands of a possible influenza pandemic, because of rapid and scalable production. However, vaccines made from recombinant Hemagglutinin (HA) subunit protein are often of low potency, requiring repeated boosting to generate a sustained immune response. Previously, we demonstrated improved immunogenicity of a plant-made H1 Hemagglutinin (HA) vaccine by chemical conjugation to the surface of the Tobacco Mosaic Virus (TMV) which is non infectious in mammals. Antigen coated TMV is taken up by mammalian dendritic cells and is a highly effective antigen carrier for subunit protein vaccines. In this work, we tested the effectiveness of a TMV-H5 HA conjugate vaccine. We compared the TMV-H5 immunogenicity in mice, with and without an oil-in water squalene adjuvant, to H5N1 virus or HA protein alone, as measured by anti-H5 IgG titers and Hemagglutination Inhibition (HAI). We then evaluated the efficacy of the TMV-H5 vaccine by lethal H5N1 virus challenge in mice. Our results show that a single dose of the TMV-H5 conjugate vaccine is sufficient to generate 40% survival, similar to H5 protein given with adjuvant, or 100% survival after vaccination with adjuvant, similar to H5N1 virus vaccination.

One-prime multi-boost strategy immunization with recombinant DNA, adenovirus, and MVA vector vaccines expressing HPV16 L1 induces potent, sustained, and specific immune response in mice

Human papillomavirus (HPV) is associated with various human diseases, including cancer, and developing vaccines is a cost-efficient strategy to prevent HPV-related disease. The major capsid protein L1, which an increasing number of studies have confirmed is typically expressed early in infection, is a promising antigen for such a vaccine, although the E6 and E7 proteins have been characterized more extensively. Thus, the L1 gene from HPV16 was inserted into a recombinant vector, AdHu5, and MVA viral vectors, and administered by prime-boost immunization. Virus-like particles were used as control antigens. Our results indicate that prime-boost immunization with heterologous vaccines induced robust and sustained cellular and humoral response specific to HPV16 L1. In particular, sera obtained from mice immunized with DNA + DNA + Ad + MVA had excellent antitumor activity in vivo. However, the data also confirm that virus-like particles can only elicit low levels cellular immunity and not be long-lasting, and are therefore unsuitable for treatment of existing HPV infections.

Effect of HSV-IL12 Loaded Tumor Cell-Based Vaccination in a Mouse Model of High-Grade Neuroblastoma.

We designed multimodal tumor vaccine that consists of irradiated tumor cells infected with the oncolytic IL-12-expressing HSV-1 virus, M002. This vaccine was tested against the syngeneic neuroblastoma mouse model Neuro 2a injected into the right caudate nucleus of the immunocompetent A/J mice. Mice were vaccinated via intramuscular injection of multimodal vaccine or uninfected irradiated tumor cells at seven and 14 days after tumor establishment. While there was no survival difference between groups vaccinated with cell-based vaccine applied following tumor injection, a premunition prime/boost vaccination strategy produced a significant survival advantage in both groups and sustained immune response to an intracranial rechallenge of the same tumor. The syngeneic but unrelated H6 hepatocellular tumor cell line grew unrestricted in vaccinated mice, indicative of vaccine-mediated specific immunity to Neuro 2a tumors. Longitudinal analyses of tumor-infiltrating lymphocytes revealed a primary adaptive T cell response involving both CD4+ and CD8+ T cell subsets. Spleen cell mononuclear preparations from vaccinated mice were significantly more cytotoxic to Neuro 2a tumor cells than spleen cells from control mice as demonstrated in a four-hour in vitro cytotoxicity assay. These results strongly suggest that an irradiated whole cell tumor vaccine incorporating IL-12-expressing M002 HSV can produce a durable, specific immunization in a murine model of intracranial tumor.

Efficacy and long-term durability of intradermal recombinant hepatitis B virus vaccine among intramuscular vaccine nonresponders: A prospective study in healthcare personnel.

Data on efficacy, safety, and durability of intradermal vaccine administration in persons who have not responded appropriately to intramuscular administration of hepatitis B virus (HBV) vaccine are relatively scarce. We designed a prospective case series in an urban tertiary care hospital in Israel. The medical records of 4007 healthcare personnel who had worked in the hospital between 1996 and 2006 were examined and those with an unsatisfactory level (<10 mIU/ml) of hepatitis B surface antibody (HBsAb) following two courses of a three-dose intramuscular HBV vaccine ("nonresponders") were identified. Nonresponders were vaccinated with three doses of 5 µg of intradermal recombinant hepatitis B surface antigen-based vaccine at weeks 0, 2, and 4. Level of HBsAb was determined 4 weeks after the last dose, and an additional dose was administered as needed. HBsAb level was again determined 24 weeks after the final vaccine dose to assess late immune reactivity and long-term durability of the vaccine. Vaccine safety was assessed at each vaccination and testing session. Twenty-seven subjects were included in the study, and 21 completed the study. The proportion of subjects with satisfactory HBsAb level at 4 weeks after the last administered dose was 70.3% (19/27). The proportion of subjects with sustained immune response at 24 weeks was 62.9% (17/27) according to intention-to-treat analysis and 80.9% (17/21) according to per protocol analysis. There were no reports of adverse events in response to the administration of the vaccine. Intradermal administration of HBV vaccine offers an efficient, safe, and durable option for intramuscular vaccine nonresponders and represents a means to optimize utilization of the widespread HBs antigen-based vaccine formulation.

Novel Injectable Pentablock Copolymer Based Thermoresponsive Hydrogels for Sustained Release Vaccines.

The need for multiple vaccinations to enhance the immunogenicity of subunit vaccines may be reduced by delivering the vaccine over an extended period of time. Here, we report two novel injectable pentablock copolymer based thermoresponsive hydrogels made of polyethyleneglycol-polycaprolactone-polylactide-polycaprolactone-polyethyleneglycol (PEG-PCL-PLA-PCL-PEG) with varying ratios of polycaprolactone (PCL) and polylactide (PLA), as single shot sustained release vaccines. Pentablock copolymer hydrogels were loaded with vaccine-encapsulated poly lactic-co-glycolic acid nanoparticles (PLGA-NP) or with the soluble vaccine components. Incorporation of PLGA-NP into the thermoresponsive hydrogels increased the complex viscosity of the gels, lowered the gelation temperature, and minimized the burst release of antigen and adjuvants. The two pentablock hydrogels stimulated both cellular and humoral responses. The addition of PLGA-NP to the hydrogels sustained immune responses for up to 49days. The polymer with a higher ratio of PCL to PLA formed a more rigid gel, induced stronger immune responses, and stimulated effective anti-tumor responses in a prophylactic melanoma tumor model.

Abstract 1329: Identification of neoantigens recognized by autoantibodies in chemotherapy-treated pancreatic cancer patients

Abstract Pancreatic ductal adenocarcinoma (PDA) is one of the most difficult cancer to treat, both for lack of effective screening method and for resistance phenomenon. At present surgical resection is the only potentially curative option, but the absence of early symptoms or clinical-pathological markers results in diagnosis at a late, inoperable stage in mostly of cases. Once diagnosed, a number of chemotherapy, radiation and combination therapy regimens are usually used to treat patients, but responses remain poor. However, chemotherapy is able to enhance tumor immunogenicity. Thus more immunogenic neo-antigens can be induced by chemotherapy and targeted by passive or active immunotherapy. We have previously identified a number of Tumor Associated Antigens (TAA) that are recognized by autoantibodies in PDAC patients. One of these, alpha-enolase, was found to have good antigen capability and immunization with DNA coding for alpha-enolase effectively enhanced the survival of genetically engineered mice that develop spontaneously PDAC. To discover neo-antigens that might be selected for immunotherapy, we have analysed antibody response in PDAC patients’ sera before and after chemotherapy. The reactivity of PDAC patients’ sera obtained before and after two rounds of chemotherapy was analysed on 2-dimensional gel electrophoresis proteome map of CF-PAC pancreatic cancer cell line and the antigens recognized by autoantibodies were identified by mass spectrometry. A number of antigens, mainly metabolic enzymes, proteins involved in transcription and structural proteins, were recognized by autoantibody only after one or two rounds of chemotherapy. The identification of common and individual antigens from chemotherapy treated-patients formed the platform for ongoing immunological studies aimed to assess the ability of these neo-antigens, compared to that identified before chemotherapy treatment, to induce specific helper and cytotoxic response to PDAC. A stronger and sustained immune response correlated to survival is expected to be induced by neo-antigens. Validation of these neo-antigens will allow to develop specific immunotherapy combined with chemotherapy. Citation Format: Giorgia Mandili, Emanuela Mazza, Michela Capello, Daniele Giordano, Paola Cappello, Francesco Novelli. Identification of neoantigens recognized by autoantibodies in chemotherapy-treated pancreatic cancer patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1329. doi:10.1158/1538-7445.AM2015-1329

Immunization of children with secondary immunodeficiency

ABSTRACTThe main causes of secondary immunodeficiency at a pediatric age include infectious diseases (mainly HIV infection), malignancies, haematopoietic stem cell or solid organ transplantation and autoimmune diseases. Children with secondary immunodeficiency have an increased risk of severe infectious diseases that could be prevented by adequate vaccination coverage, but vaccines administration can be associated with reduced immune response and an increased risk of adverse reactions. The immunogenicity of inactivated and recombinant vaccines is comparable to that of healthy children at the moment of vaccination, but it undergoes a progressive decline over time, and in the absence of a booster, the patients remain at risk of developing vaccine-preventable infections. However, the administration of live attenuated viral vaccines is controversial because of the risk of the activation of vaccine viruses. A specific immunization program should be administered according to the clinical and immunological status of each of these conditions to ensure a sustained immune response without any risks to the patients' health.

Regulation of CTL trafficking into tumors and anti-tumor immunity by chemoattractant receptors BLT1 and CXCR3 (TUM7P.1015)

Abstract A major hurdle limiting the success of tumor immunotherapies in the clinic is poor recruitment of CD8+ T cells (Cytotoxic T Lymphocytes-CTL) into tumors despite efficient CTL responses in the periphery. However, little is known about the mechanisms that regulate their infiltration into tumors. We investigated the role of leukotriene B4 receptor, BLT1 and CXCR3, the receptor for CXCL9 and CXCL10 in anti-tumor immunity using a syngeneic B16 melanoma mice model. Significant acceleration in tumor growth and reduced survival was observed in both BLT1-/- and CXCR3-/- mice as compared to WT mice. Tumor immune infiltration studies revealed significant reduction of CTLs in BLT1-/- and CXCR3-/- tumors as compared to WT tumors, their frequencies being similar in the periphery. Adoptive transfer of WT but not BLT1-/- or CXCR3-/- CTLs reduced tumor growth in Rag2-/- animals due to enhanced WT CTL infiltration to tumors. Furthermore, adoptive transfer of BLT1-/-, CXCR3-/- or BLT1-/-CXCR3-/- CTLs together with WT CTLs showed that initial migration of BLT1+/+ CTLs to tumors facilitates additional CTL recruitment in a CXCR3 dependent manner. An anti-PD-1 antibody based vaccine completely lost its efficacy in both BLT1-/- and CXCR3-/- mice suggesting a requirement for these receptors in generating sustained anti-tumor immune response. These results demonstrate a critical role for BLT1 and CXCR3 in CTL migration to tumors and thus can be targeted to elicit effective anti-tumor responses.

Persistence of pathological distribution of NK cells in HIV-infected patients with prolonged use of HAART and a sustained immune response.

ObjectiveA prospective analysis of the distribution of NK subsets and natural cytotoxicity receptors (NKp30/NKp46) in HIV patients with long-term HAART use and sustained virological and immunological response.MethodsThe main inclusion criteria were: at least 3 years’ receipt of HAART; current CD4+ count ≥ 500 cells/mm3; undetectable viral load for at least 24 months; no hepatotropic virus co-infection. Percentages of CD56dim, CD56bright NK cells and CD56neg CD16+ cells were obtained. Expression of the NCRs, NKp30 and NKp46 was analysed in CD56+ cells. Thirty-nine infected patients and sixteen healthy donors were included in the study.ResultsThe percentages of total CD56+ and CD56dim NK cells were significantly lower in HIV-infected patients than in healthy donors (70.4 vs. 50.3 and 80.9 vs. 66.1 respectively). The percentage of total CD56+ NK cells expressing NCR receptors was lower in HIV patients than in healthy donors (NKp30: 25.20 vs. 58.63; NKp46: 24.8 vs. 50.59). This was also observed for CD56dim and CD56bright NK cells. Length of time with undetectable HIV viral load was identified as an independent factor associated with higher expression of NKp30 and NKp46.ConclusionDespite the prolonged and effective use of HAART, HIV-infected patients do not fully reconstitute the distribution of NK cells. Length of time with an undetectable viral load was related to greater recovery of NKp30/NKp46 receptors.