Long-lasting Immunological Memory Research Articles

Abstract 454: microRNAs role in innate immunosenescence during anti-PD1 immunotherapy

Abstract Checkpoint inhibitors have achieved durable responses and long-lasting immunologic memory in cancer patients. However, the initial and acquired resistance remains an unsolved problem. It’s urgent to learn the molecular mechanisms causing resistance. microRNAs (miRNAs) are short transcripts that regulate many pathophysiological processes. Here, we investigated the miRNAs expression changes after GVAX combined with monoclonal PD-1 antibody treatment in the murine melanoma B16F10 tumors and identified microRNAs down-regulated in responsive tumors. Deletion of this family member in three different syngeneic mouse tumors did not affect their in vitro nor in vivo proliferation but sensitized anti-PD1 immunotherapy. The miRNA deletion with anti-PD1 therapy increased total CD45+ leukocyte infiltration with all types of hematopoietic cells except macrophages. Both tumor bulk RNA sequencing and single-cell RNA sequencing revealed activated innate sensing genes especially for pathogen recognition and phagosome formation. Importantly, we found specific miRNA-deletion effects rely on tumor resident macrophage, IFN-γ release in the tumor microenvironment (TME) and the miRNA regulating machinery protein Argonaut2 (Ago2). Notably, the miRNA expression status of melanoma patients correlates with the survival and innate immune sensing gene expression. Our results suggest that this family of miRNAs participate in initial resistance by escaping innate immunosurveillance. Deletion of the miRNA may turn immune “cold” tumors to “hot” tumors, providing potential therapeutic targets to overcome resistance in melanoma, colorectal, triple-negative breast cancer and possibly other cancers. Citation Format: Zhouting Zhu, Tariq M. Rana. microRNAs role in innate immunosenescence during anti-PD1 immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 454.

Redox-responsive polymer micelles co-encapsulating immune checkpoint inhibitors and chemotherapeutic agents for glioblastoma therapy

Immunotherapy with immune checkpoint blockade (ICB) for glioblastoma (GBM) is promising but its clinical efficacy is seriously challenged by the blood-tumor barrier (BTB) and immunosuppressive tumor microenvironment. Here, anti-programmed death-ligand 1 antibodies (aPD-L1) are loaded into a redox-responsive micelle and the ICB efficacy is further amplified by paclitaxel (PTX)-induced immunogenic cell death (ICD) via a co-encapsulation approach for the reinvigoration of local anti-GBM immune responses. Consequently, the micelles cross the BTB and are retained in the reductive tumor microenvironment without altering the bioactivity of aPD-L1. The ICB efficacy is enhanced by the aPD-L1 and PTX combination with suppression of primary and recurrent GBM, accumulation of cytotoxic T lymphocytes, and induction of long-lasting immunological memory in the orthotopic GBM-bearing mice. The co-encapsulation approach facilitating efficient antibody delivery and combining with chemotherapeutic agent-induced ICD demonstrate that the chemo-immunotherapy might reprogram local immunity to empower immunotherapy against GBM.

Gold standard assessment of immunogenic cell death induced by photodynamic therapy: From in vitro to tumor mouse models and anti-cancer vaccination strategies.

The discovery of the concept of immunogenic cell death (ICD) is a cornerstone in the development of novel anti-cancer immunotherapeutic approaches. Induction of the ICD pathway by specific anti-cancer therapeutic regimens can eliminate cancer cells by directly killing them during therapy and by activation of strong and specific anti-cancer immunity, leading to a long-lasting immunological memory that prevents cancer recurrence. ICD encompasses different forms of regulated cell death and can be triggered by many anti-cancer treatment modalities, including photodynamic therapy (PDT). PDT is a multistep procedure involving the accumulation of a light-sensitive dye known as a photosensitizer (PS) in tumor cells, followed by its activation by irradiation with a light of an appropriate wavelength. In the presence of molecular oxygen, the irradiated PS leads to the generation of cytotoxic reactive oxygen species, which can lead to ICD induction in the cancer cells. Here, we first describe in vitro methods to help optimize the PDT procedure for a specific PS. We also provide a collection of protocols and techniques for assessing ICD in vitro, including analysis of the emission of damage associated molecular patterns (DAMPs), efferocytosis, and the maturation and activation state of antigen presenting cells. Next, we describe in detail protocols for diverse tumor mouse models for assessing and characterizing ICD in vivo, such as murine tumor vaccination models. Finally, as an immunotherapeutic vaccine, we suggest using either PDT-induced dead cancer cells, preferably undergoing ICD, or dendritic cells loaded with lysates of PDT-induced cancer cells in a syngeneic orthotopic glioma model. Overall, this methodological article provides a quantitative, comprehensive set of validated tools that can be successfully used, with some adaptations, to identify, optimize and validate novel PSs in vitro and in vivo for the efficient induction of ICD during photodynamic treatment.

SIRPα blockade improves the antitumor immunity of radiotherapy in colorectal cancer

High-dose hypofractionated radiotherapy (HRT) is an important anticancer treatment modality that activates antitumor host immune responses. However, HRT for oligometastases of colorectal cancer (CRC) has shown frustrating results in the clinic. As part of immune evasion, myeloid cells express signal regulatory protein α (SIRPα) to inhibit phagocytosis by phagocytes in the tumor microenvironment (TME). We postulated that SIRPα blockade enhances HRT by alleviating the inhibitory action of SIRPα on phagocytes. We demonstrated that SIRPα on myeloid cells was upregulated in the TME after HRT. When SIRPα blockade was administered with HRT, we observed superior antitumor responses compared with anti-SIRPα or HRT alone. When anti-SIRPα was administered to local HRT, the TME could become a tumoricidal niche that was heavily infiltrated by activated CD8+ T cells, but with limited myeloid-derived suppressor cells and tumor-associated macrophages. While CD8+ T cells were required for the effectiveness of the anti-SIRPα + HRT combination. The triple therapy with anti-SIRPα + HRT + anti-PD-1 had superior antitumor responses compared with the combination of any two therapies and established a strong and long-lasting adaptive immunological memory. Collectively, SIRPα blockade provides a novel way to overcome HRT resistance in oligometastatic CRC patients. Our results herein provide a valuable cancer treatment strategy that has the potential to be translated into clinical practice.

CD8 + T cell memory is sustained in mice by hepatic stellate cells.

Long-lasting immunological memory is the ultimate goal of vaccination. Homeostatic maintenance of memory CD8 + cytotoxic T cells (MemCD8TCs) is thought to be mediated by IL-15/IL-15R heterodimer (15HD)-expressing myeloid cells. Nonmyeloid hepatic stellate cells (HSCs) also express 15HD, but their role in maintaining MemCD8TC homeostasis is unknown. We engineered a genetically engineered mouse in which IL-15R complementary DNA (cDNA) had been inserted in-frame with lecithin-retinol acyltransferase gene and bred onto an IL-15R-KO (15R-KO) genetic background (L15R) that expressed IL-15R in HSCs at normal levels, but not in other liver cells. Outside of the liver of L15R mice, IL-15R expression was found in a number of organs, but not in dendritic cells and macrophages. The low IL-15R expression in the bone marrow (BM) of L15R mice was eliminated by the reconstitution of lethally-irradiated L15R mice with 15R-KO BM to generate L15RC mice. Because MemCD8TC maintenance is mediated by 15HD, not empty IL-15R, 15HD content in L15R mice was determined and found for liver, lung, kidney, and heart. L15R and L15RC mice developed and maintained long-lasting, systemic antigen-specific MemCD8TCs that were efficacious against tumor growth and Listeria monocytogenes infection in an antigen-specific manner. Among the four organs with 15HD content, liver-associated MemCD8TCs were different from those found in the lung, kidney, and heart in two ways: (1) they were quantitatively the most numerous, and (2) they appeared uniquely in the form of clusters in a specialized structure, sinusoidal niches of the liver. The liver, the largest organ of the body, is endowed with the capability of effectuating long-lasting functional cytotoxic T cell memory.

The magnitude of the germinal center B cell and T follicular helper cell response predicts long-lasting antibody titers to plague vaccination.

The development of a safe and effective vaccine against Yersinia pestis, the causative organism for plague disease, remains an important global health priority. Studies have demonstrated effective immune-based protection against plague challenge that is induced by plague antigen subunit vaccination in an aqueous alhydrogel formulation; however, whether these candidate vaccines in this formulation and presentation, induce long-lasting immunological memory in the form of durable cellular and antibody recall responses has not been fully demonstrated. In this study, we analyzed germinal center T follicular helper and germinal center B cell responses following F1V and F1 + V plague subunit immunization of mice with vaccines formulated in various adjuvants. Our data demonstrate that recombinant plague protein immunization formulated with IL-2/GM-CSF cytokines bound to alhydrogel adjuvant drive an increase in the magnitude of the germinal center T follicular helper and germinal center B cell responses following primary immunization, compared to vaccines formulated with Alhydrogel adjuvant alone. In contrast, plague protein subunit immunization combined with CpG ODN bound to alhydrogel increased the magnitude and duration of the germinal center Tfh and B cell responses following booster immunization. Importantly, enhanced germinal center Tfh and B cell responses correlated with long-lasting and high F1V-specific antibody titers and more robust antibody recall responses to F1V re-exposure. These findings indicate that vaccine formulations that drive enhancement of the germinal center Tfh and B cell responses are critical for inducing durable plague-specific humoral immunity.

Temperature effects on teleost immunity in the light of climate change.

Temperature is an important environmental modulator of teleost immune activity. Susceptibility of teleosts to temperature variation depends on the species-specific adaptive temperature range, and the activity of the teleost immune system is generally temperature-dependent. Similar to many physiological and metabolic traits of ectotherms, temperature modulates the activity of immune traits. At low temperatures, acquired immunity of many teleost species is down-modulated, and their immuno-competence mainly depends on innate immunity. At intermediate temperatures, both innate and acquired immunity are fully active and provide optimal protection, including long-lasting immunological memory. When temperatures increase and reach the upper permissive range, teleost immunity is compromised. Moreover, temperature shifts may have negative effects on teleost immune functions, in particular if shifts occur rapidly with high amplitudes. On the contrary, short-term temperature increase may help teleost immunity to fight against pathogens transiently. A major challenge to teleosts therefore is to maintain immuno-competence throughout the temperature range they are exposed to. Climate change coincides with rising temperatures, and more frequent and more extreme temperature shifts. Both are likely to influence the immuno-competence of teleosts. Nonetheless, teleosts exist in habitats that differ substantially in temperature, ranging from below zero in the Arctic's to above 40°C in warm springs, illustrating their enormous potential to adapt to different temperature regimes. The present review seeks to discuss how changes in temperature variation, induced by climate change, might influence teleost immunity.

A century of BCG vaccination: Immune mechanisms, animal models, non-traditional routes and implications for COVID-19

Bacillus Calmette-Guerin (BCG) has been used as a vaccine against tuberculosis since 1921 and remains the only currently approved vaccine for this infection. The recent discovery that BCG protects against initial infection, and not just against progression from latent to active disease, has significant implications for ongoing research into the immune mechanisms that are relevant to generate a solid host defense against Mycobacterium tuberculosis (Mtb). In this review, we first explore the different components of immunity that are augmented after BCG vaccination. Next, we summarize current efforts to improve the efficacy of BCG through the development of recombinant strains, heterologous prime-boost approaches and the deployment of non-traditional routes. These efforts have included the development of new recombinant BCG strains, and various strategies for expression of important antigens such as those deleted during the M. bovis attenuation process or antigens that are present only in Mtb. BCG is typically administered via the intradermal route, raising questions about whether this could account for its apparent failure to generate long-lasting immunological memory in the lungs and the inconsistent level of protection against pulmonary tuberculosis in adults. Recent years have seen a resurgence of interest in the mucosal and intravenous delivery routes as they have been shown to induce a better immune response both in the systemic and mucosal compartments. Finally, we discuss the potential benefits of the ability of BCG to confer trained immunity in a non-specific manner by broadly stimulating a host immunity resulting in a generalized survival benefit in neonates and the elderly, while potentially offering benefits for the control of new and emerging infectious diseases such as COVID-19. Given that BCG will likely continue to be widely used well into the future, it remains of critical importance to better understand the immune responses driven by it and how to leverage these for the design of improved vaccination strategies against tuberculosis.

The New Old CD8+ T Cells in the Immune Paradox of Pregnancy.

CD8+ T cells are the most frequent T cell population in the immune cell compartment at the feto-maternal interface. Due to their cytotoxic potential, the presence of CD8+ T cells in the immune privileged pregnant uterus has raised considerable interest. Here, we review our current understanding of CD8+ T cell biology in the uterus of pregnant women and discuss this knowledge in relation to a recently published immune cell Atlas of human decidua. We describe how the expansion of CD8+ T cells with an effector memory phenotype often presenting markers of exhaustion is critical for a successful pregnancy, and host defense towards pathogens. Moreover, we review new evidence on the presence of long-lasting immunological memory to former pregnancies and discuss its impact on prospective pregnancy outcomes. The formation of fetal-specific memory CD8+ T cell subests in the uterus, in particular of tissue resident, and stem cell memory cells requires further investigation, but promises interesting results to come. Advancing the knowledge of CD8+ T cell biology in the pregnant uterus will be pivotal for understanding not only tissue-specific immune tolerance but also the etiology of complications during pregnancy, thus enabling preventive or therapeutic interventions in the future.

Divergent Immune Responses to SARS-CoV-2 Vaccines in Immunocompromised Patients.

To The Editor: Understanding the composition and duration of immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is critical for prevention of infection. The most critical elements of immunity to SARS-CoV-2 are neutralizing antibody and T-cell immunity. Current assessments of immunity and risk for infections largely depended on detection of antibodies to SARS-CoV-2. However, taken alone, this represents an often-unreliable tool due to the evanescent nature of spike immunoglobulin G (IgG) responses.1-3 Here, an important and more durable response involves cytotoxic T-cells that can eliminate virally infected cells and T helper cells, which are critical to coordinating adaptive immunity toward the virus and generating long-lasting immunologic memory. However, T-cell responses are more difficult to assess. These issues become more prescient in determining immunity to SARS-CoV-2 in immunocompromised individuals where a majority show no IgG responses to vaccines and the recent emergence of the Delta variant with reports of >74% vaccine breakthrough cases.4,5 Here, we report on patients demonstrating divergent immune responses to SARS-CoV-2 vaccination. Institutional Review Board approval and informed consent was obtained before performance of assays (Appendix 1, SDC, https://links.lww.com/TP/C290). Seven patients were identified from a cohort of 70 immunocompromised patients, with all demonstrating spike-specific IgG unresponsiveness 2–4 mo postvaccination. All had received treatment with B-cell modifying agents. We subsequently examined CD4+/CD8+ T-cell–spike-specific immune responses in all patients and repeat examination after revaccination in 2 patients (see Appendix 1, SDC, https://links.lww.com/TP/C290, for Methods and Data). CD4+/CD8+ T-cell responses are shown in Figure 1 and demonstrate robust CD4+T-cell (0.94 ± 1.2%, Normal > 0.05%) and CD8+ T-cell (0.89 ± 1.2%, Normal > 0.05%) immune responses to spike peptides. Two patients receiving Johnson & Johnson booster vaccines demonstrated increased T-cell responses but remained spike IgG negative. This suggests that T-cell immune responses to SARS-CoV-2 vaccines are primal and retentive and that B-cell depletion before vaccine exposure prevents the cascade of progression of B-cell activation necessary for SARS-CoV-2 spike IgG production.FIGURE 1.: A, Detectable CD4+/CD8+ T-cell immune responses in vaccinated patients against SARS-CoV-2 spike peptides. Flow cytometry diagrams from 7 patients (P1–P7) assessed after 2 doses of Pfizer or Moderna vaccines. Cells were stimulated by SARS-CoV-2 spike peptides pool (PepMix SARS-CoV-2 [spike glycoprotein, JPT) for 9 h in vitro in the presence of Brefeldin A and anti-CD28/CD49d (BD Bioscience, San Jose, CA). Cells were stained for T-cell surface markers followed by fixation, permeabilization, and intracellular staining of cytokines (BD Bioscience, San Jose, CA). Activated CD4+ T cells (IL-2+TNFα+) and CD8+ T cells (IFNγ+TNFα+) are shown in the upper right-hand corner of each flow box. B, This figure shows immune responses to SARS-CoV-2 spike peptides in 2 patients who obtained external revaccination with the Johnson & Johnson vaccine. As in (A), percentages of activated CD4+ T cells (IL-2+TNFα+) and CD8+ T cells (IFNγ+TNFα+) in blood are shown after first vaccination (2 doses) and after third vaccination (booster). Activated CD4+ T cells (IL-2+TNFα+) and CD8+ T cells (IFNγ+TNFα+) are shown in the upper right-hand corner of each flow box. IFNγ, interferon γ; IL, interleukin; P, patient; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; TNFα, tumor necrosis factor α.Absence of IgG responses to SARS-CoV-2 suggests patients be considered “unvaccinated.” However, we show that patients treated with B-cell–modifying agents develop robust T-cell immune responses to SARS-CoV-2 without generating IgG responses. These observations should be considered in light of data presented by Peng et al showing robust CD4+/CD8+ T-cell responses to SARS-CoV-2 after infection. A critical observation was the diversity of T-cell responses that likely extend beyond the persistence of spike antibody. IgG is necessary for sterilizing immunity and T-cells cannot prevent infection as antigen presentation is required, but T-cell immunity can be at the ready for viral elimination. This may provide an inside track for rapid deployment of SARS-CoV-2 immunity, and although not preventing infection, could alter the severity and duration of SARS-CoV-2 disease.6 This is supported by data from Oberhardt et al7 who recently showed that vaccine-induced CD8+ T cells were the main mediators of protection after vaccination since they emerged before detection of neutralizing antibody and expanded after booster vaccination. Thus, detection of T-cell immune responses in patients failing to generate spike-specific IgG may aid in a more comprehensive assessment of immunity to SARS-CoV-2, identifying patients who would no longer be considered “unvaccinated” based on negative spike-specific IgG. This likely has relevance to patients receiving B-cell directed therapies for autoimmune and hematologic diseases. ACKNOWLEDGMENTS The authors would like to express our gratitude to the members of the Transplant Immunotherapy Program and the Transplant Immunology Laboratory at Cedars-Sinai Medical Center for their dedication to improving patient outcomes and safety during the coronavirus disease 2019 pandemic. We would also like to thank the patients who participated in this study by donating their blood for analysis of SARS-CoV-2 reactive T-cells.

One Year after Mild COVID-19: The Majority of Patients Maintain Specific Immunity, But One in Four Still Suffer from Long-Term Symptoms.

After COVID-19, some patients develop long-term symptoms. Whether such symptoms correlate with immune responses, and how long immunity persists, is not yet clear. This study focused on mild COVID-19 and investigated correlations of immunity with persistent symptoms and immune longevity. Persistent complications, including headache, concentration difficulties and loss of smell/taste, were reported by 51 of 83 (61%) participants and decreased over time to 28% one year after COVID-19. Specific IgA and IgG antibodies were detectable in 78% and 66% of participants, respectively, at a 12-month follow-up. Median antibody levels decreased by approximately 50% within the first 6 months but remained stable up to 12 months. Neutralizing antibodies could be found in 50% of participants; specific INFgamma-producing T-cells were present in two thirds one year after COVID-19. Activation-induced marker assays identified specific T-helper cells and central memory T-cells in 80% of participants at a 12-month follow-up. In correlative analyses, older age and a longer duration of the acute phase of COVID-19 were associated with higher humoral and T-cell responses. A weak correlation between long-term loss of taste/smell and low IgA levels was found at early time points. These data indicate a long-lasting immunological memory against SARS-CoV-2 after mild COVID-19.

Combining Cancer Vaccines with Immunotherapy: Establishing a New Immunological Approach.

Therapeutic cancer vaccines have become increasingly qualified for use in personalized cancer immunotherapy. A deeper understanding of tumor immunology and novel antigen delivery technologies has assisted in optimizing vaccine design. Therapeutic cancer vaccines aim to establish long-lasting immunological memory against tumor cells, thereby leading to effective tumor regression and minimizing non-specific or adverse events. However, due to several resistance mechanisms, significant challenges remain to be solved in order to achieve these goals. In this review, we describe our current understanding with respect to the use of the antigen repertoire in vaccine platform development. We also summarize various intrinsic and extrinsic resistance mechanisms behind the failure of cancer vaccine development in the past. Finally, we suggest a strategy that combines immune checkpoint inhibitors to enhance the efficacy of cancer vaccines.

The Bone Marrow as Sanctuary for Plasma Cells and Memory T-Cells: Implications for Adaptive Immunity and Vaccinology

The bone marrow (BM) is key to protective immunological memory because it harbors a major fraction of the body’s plasma cells, memory CD4+ and memory CD8+ T-cells. Despite its paramount significance for the human immune system, many aspects of how the BM enables decade-long immunity against pathogens are still poorly understood. In this review, we discuss the relationship between BM survival niches and long-lasting humoral immunity, how intrinsic and extrinsic factors define memory cell longevity and show that the BM is also capable of adopting many responsibilities of a secondary lymphoid organ. Additionally, with more and more data on the differentiation and maintenance of memory T-cells and plasma cells upon vaccination in humans being reported, we discuss what factors determine the establishment of long-lasting immunological memory in the BM and what we can learn for vaccination technologies and antigen design. Finally, using these insights, we touch on how this holistic understanding of the BM is necessary for the development of modern and efficient vaccines against the pandemic SARS-CoV-2.

Hyperbaric Oxygen Boosts PD-1 Antibody Delivery and T Cell Infiltration for Augmented Immune Responses Against Solid Tumors.

Aberrant mechanical properties and immunosuppression are the two key factors that limit the antitumor efficacy of T cell immune checkpoint blockade inhibitors, e.g., programmed cell death‐1 antibody (PD‐1 Ab), against solid tumors in the clinic. This study leverages hyperbaric oxygen (HBO) for the first time to address these two issues and reports the PD‐1‐Ab‐mediated immune responses against various stroma‐rich solid malignancies. The results demonstrate that HBO promoted PD‐1 Ab delivery and T cells infiltration into tumor parenchyma by depleting the extracellular matrix's main components, such as collagen and fibronectin. Furthermore, HBO disrupts hypoxia‐mediated immunosuppression and helps PD‐1 Ab trigger robust cytotoxic T lymphocytes and long‐lasting immunological memory to inhibit tumor relapses. Such enhanced immune responses are effective in solid tumors from rodents and the cancer cells from hepatocellular carcinoma patients. The results illustrate that HBO bolsters antitumor efficacy of PD‐1 Ab, and the HBO–PD‐1 Ab combination is a promising stroma‐rich solid tumors’ treatment in the clinic.

Long-term Memory Response After a Single Intramuscular Rabies Booster Vaccination 10-24 Years After Primary Immunization.

BackgroundPublished data regarding long-lasting immunological rabies memory after pre-exposure prophylaxis (PrEP) are scarce. We tested the hypothesis that rabies booster immunization elicits rapid anamnestic responses.MethodsFor this observational study, we included participants who had received PrEP 10–24 years before inclusion. We measured rabies antibody titers before, and on days 3, 7, and 14 after a single intramuscular booster.ResultsAll 28 participants responded adequately regardless of route of administration or 2-dose vs 3-dose PrEP regimen.ConclusionRabies immunological memory is reactivated within 7 days after a single intramuscular booster immunization, even when administered 10–24 years after PrEP.

Specific IgG and IgA Antibody Reactivities in Sera of Children by Enzyme-Linked Immunoassay and Comparison With Giardia duodenalis Diagnosis in Feces.

BackgroundGiardia duodenalis is conventionally diagnosed in fecal samples using parasitological methods. However, sensitivity is poor when only a single sample is analyzed, due to intermittent excretion of cysts in feces. Alternatively, the serum antibodies to G. duodenalis can be used for parasite diagnosis and epidemiological studies to determine previous exposure. We compared the rate of G. duodenalis infection between serum anti-Giardia IgG and IgA antibodies and fecal examination in Brazilian children.MethodsFecal and serum samples were tested from 287 children at a clinical laboratory and from 187 children at daycare centers. Fecal samples were processed using conventional parasitological methods and coproantigen detection for Giardia diagnosis. Serum samples were tested using an in-house ELISA for detection of anti-Giardia IgG and IgA.ResultsG. duodenalis was found in 8.2% (N=39) of the 474 children analyzed. The sensitivity and specificity of ELISA were 80.0% and 90.0% for IgG and 80.0% and 83.3% for IgA, respectively. The total positivity rate of anti-Giardia IgG and IgA in the sera was 13.9% (N=66) and 23.6% (N=112). The agreement between the positivity of specific antibodies and the detection of G. duodenalis in feces was moderate for ELISA-IgG, kappa index (95% CI)=0.543 (0.422–0.664), and mild for ELISA-IgA, kappa index (95% CI)=0.283 (0.162–0.404). Among the children infected with other enteroparasites, 11.6% (N=10) and 24.4% (N=21) showed reactivity to anti-Giardia IgG and to IgA, respectively. This cross-reactivity was more frequent in samples from children infected with Endolimax nana and Entamoeba coli.ConclusionsThe higher frequency of specific antibody reactivity compared with G. duodenalis diagnosis in feces could reflect continuous exposure of children to G. duodenalis infection, resulting in long-lasting immunological memory and/or cross-reactivity with other intestinal amoebas.

Modulation of tumor microenvironment using a TLR-7/8 agonist-loaded nanoparticle system that exerts low-temperature hyperthermia and immunotherapy for in situ cancer vaccination

Most cancer vaccines under development are associated with defined tumor antigens rather than with all antigens of whole tumor cells, limiting the anti-tumor immune responses that they elicit. This work proposes an immunomodulator (R848)-loaded nanoparticle system (R848@NPs) that can absorb near-infrared light (+NIR) to cause low-temperature hyperthermia that interacts synergistically with its loaded R848 to relieve the tumor-mediated immunosuppressive microenvironment, generating robust anti-tumor memory immunity. In vitro results reveal that the R848@NPs could be effectively internalized by dendritic cells, causing their maturation and the subsequent regulation of their anti-tumor immune responses. Post-treatment observations in mice in which tumors were heat-treated at high temperatures reveal that tumor growth was significantly inhibited initially but not in the longer term, while low-temperature hyperthermia or immunotherapy alone simply delayed tumor growth. In contrast, a combined therapy that involved low-temperature hyperthermia and immunotherapy using R848@NPs/+NIR induced a long-lasting immunologic memory and consequently inhibited tumor growth and prevented cancer recurrence and metastasis. These results suggest that the method that is proposed herein is promising for generating cancer vaccines in situ, by using the tumor itself as the antigen source and the introduced R848@NPs/+NIR to generate a long-term anti-tumor immunity, for personalized immunotherapy.

Tick-borne encephalitis virus (TBEV) antibodies in animal sera \u2013 occurrence in goat flocks in Germany, longevity and ability to recall immunological information after more than six years

BackgroundTBE is an important tick-borne viral zoonosis in Europe and some parts of Asia. Humans can become infected by tick bite and in some cases also by consumption of nonpasteurized raw milk and raw milk products from ruminants. Serological investigations of milking flocks can help to assess the risk of TBEV infection for humans. 735 blood samples from 50 goat flocks from four federal states of Germany were tested by TBEV-VNT to assess a potential risk for TBEV infection.There are some gaps in the knowledge about immunity in animals, for example with regard to the longevity of TBEV immunity. Two goats and two sheep were immunized and TBEV antibody titers could be detected for up to 7 years.Furthermore, nothing is known about a possible long-lasting immunological memory that could quickly be reactivated by an additional contact to TBEV. Seven years after the first immunization two goats and two sheep as well as two naïve goats and two sheep were boostered and TBEV antibody titers followed.ResultsOnly one sample in each of the three states was TBEV-antibody positive (VNT), albeit with low titers. However, in Baden-Württemberg seven samples were positive, among them four goats of the same flock.TBEV-antibody positive titers were detected in goats for up to 6 years and 10 months, in sheep for up to 4 years and 7 months.Seven years after immunization a clear immunological recall occurred in response to administration of one dose of vaccine in two goats and two sheep.ConclusionIt can be concluded that in the tested flocks the risk of an alimentary TBEV infection was low. However, in one single flock a considerably higher risk must be assumed.Antibody titers in goats and sheep can last very long after contact to TBEV, albeit at a low level. This should be taken into consideration in cases where the risk of an alimentary infection is assessed in a flock by serological investigations.The immunological recall gives rise to the suspicion that the immunological memory after a first contact to TBEV lasts for many years, probably lifelong.

Pathogenic CD8+ Epidermis-Resident Memory T Cells Displace Dendritic Epidermal T Cells in Allergic Dermatitis

The skin is our interface with the outside world, and consequently it is exposed to a wide range of microbes and allergens. Recent studies have indicated that allergen-specific skin-resident memory T (TRM) cells play a role in allergic contact dermatitis (ACD). However, the composition and dynamics of the epidermal T-cell subsets during ACD are not known. Here we show that exposure of the skin to the experimental contact allergen DNFB results in a displacement of the normally occurring dendritic epidermal T cells (DETC) concomitant with an accumulation of epidermal CD8+CD69+CD103+ TRM cells in mice. By studying knockout mice, we provide evidence that CD8+ T cells are required for the displacement of the DETC and that DETC are not required for recruitment of CD8+ TRM cells to the epidermis following allergen exposure. We demonstrate that the magnitude of the allergic reaction correlates with the number of CD8+ epidermal TRM cells, which again correlates with allergen dose and number of allergen exposures. Finally, in an attempt to elucidate why CD8+ epidermal TRM cells persist in the epidermis, we show that CD8+ epidermal TRM cells have a higher proliferative capability and are bioenergetically more stable, displaying a higher spare respiratory capacity than DETC.

CXCR1- or CXCR2-modified CAR T cells co-opt IL-8 for maximal antitumor efficacy in solid tumors

Chimeric antigen receptor (CAR) T-cell therapy targeting solid tumors has stagnated as a result of tumor heterogeneity, immunosuppressive microenvironments, and inadequate intratumoral T cell trafficking and persistence. Early (≤3 days) intratumoral presentation of CAR T cells post-treatment is a superior predictor of survival than peripheral persistence. Therefore, we have co-opted IL-8 release from tumors to enhance intratumoral T-cell trafficking through a CAR design for maximal antitumor activity in solid tumors. Here, we demonstrate that IL-8 receptor, CXCR1 or CXCR2, modified CARs markedly enhance migration and persistence of T cells in the tumor, which induce complete tumor regression and long-lasting immunologic memory in pre-clinical models of aggressive tumors such as glioblastoma, ovarian and pancreatic cancer.