PBMC Responses Research Articles

Immunoglobulin and T cell receptor repertoire changes induced by a prototype vaccine against Chagas disease in naïve rhesus macaques

BackgroundA vaccine against Trypanosoma cruzi, the agent of Chagas disease, would be an excellent additional tool for disease control. A recombinant vaccine based on Tc24 and TSA1 parasite antigens was found to be safe and immunogenic in naïve macaques.MethodsWe used RNA-sequencing and performed a transcriptomic analysis of PBMC responses to vaccination of naïve macaques after each vaccine dose, to shed light on the immunogenicity of this vaccine and guide the optimization of doses and formulation. We identified differentially expressed genes and pathways and characterized immunoglobulin and T cell receptor repertoires.ResultsRNA-sequencing analysis indicated a clear transcriptomic response of PBMCs after three vaccine doses, with the up-regulation of several immune cell activation pathways and a broad non-polarized immune profile. Analysis of the IgG repertoire showed that it had a rapid turnover with novel IgGs produced following each vaccine dose, while the TCR repertoire presented several persisting clones that were expanded after each vaccine dose.ConclusionsThese data suggest that three vaccine doses may be needed for optimum immunogenicity and support the further evaluation of the protective efficacy of this vaccine.

Atopic dermatitis phenotype affects expression of atopic diseases despite similar mononuclear cell cytokine response

BackgroundThe atopic march refers to the co-expression and progression of atopic diseases in childhood, often beginning with atopic dermatitis, although children may not “progress” through each atopic disease. ObjectiveWe hypothesized that future atopic disease expression is modified by atopic dermatitis phenotype, and that these differences result from underlying dysregulation of cytokine signaling. MethodsChildren (n=285) were enrolled into the Childhood Origins of ASThma birth cohort and followed prospectively. Rates of atopic dermatitis, food allergy, allergic rhinitis, and asthma were assessed longitudinally from birth to 18 years of age. Associations between atopic dermatitis phenotype and food allergy, allergic rhinitis, asthma, allergic sensitization, exhaled nitric oxide, and lung function were determined. Peripheral blood mononuclear cell responses (IL-5, IL-10, IL-13, IFN-γ) to dust mite, phytohemagglutinin, Staphylococcus aureus Cowan I, and tetanus toxoid were compared among atopic dermatitis phenotypes. ResultsAtopic dermatitis at year 1 was associated with an increased risk of food allergy (p=0.004). Both persistent and late-onset atopic dermatitis were associated with an increased risk of asthma (p=<0.001), rhinitis (p<0.001), elevated total IgE (p=<0.001), percentage of aeroallergens with detectable IgE (p<0.001), and elevated exhaled nitric oxide (p=0.002). Longitudinal analyses did not reveal consistent differences in PBMC responses among dermatitis phenotypes. ConclusionAtopic dermatitis phenotype is associated with differential expression of other atopic diseases. Our findings suggest peripheral blood cytokine dysregulation is not a mechanism underlying this process, and immune dysregulation may be mediated at mucosal surfaces or in secondary lymphoid organs.

Cytokine responses in Chlamydia pneumoniae-stimulated PBMC in asthmatic and non-asthmatic subjects.

Cytokine responses in Chlamydia pneumoniae-stimulated PBMC in asthmatic and non-asthmatic subjects.

THREE MONTHS OF STRENGTH TRAINING ALTERS LPS-INDUCED IMMUNE RESPONSES IN CIRCULATING PBMC OF OLDER PERSONS

Abstract BACKGROUND Recently, we showed that 3 months strength training affect 18 canonical pathways related to chronic inflammation in peripheral mononuclear blood cells (PBMC) of older adults. Here we investigate if resistance training improves the stress response of PBMC by mimicking in-vitro an acute infection by lipopolysaccharide (LPS)-challenge. METHODS 14 women aged ≥65 years were randomized into 3 months of either 3×/week intensive strength training (IST: 3×10 rep at 80% 1RM), strength endurance training (SET: 2×30 reps at 40% 1RM) or control (CON: 3×30 sec stretching). Before and after 3 months training, PBMC were isolated and cultured with and without LPS. Prior culture and after 24 hours of culture, RNA was collected from pre-cultured, post-cultured and LPS challenged PBMC’s, respectively. Targeted RNA sequencing including 407 inflammation-related genes was performed. Pathway analysis was performed with Ingenuity Pathway Analyses using all 407 genes, a Benjamini-Hochberg p-value &amp;lt; 0.05 and a z-score of ≤-2 or ≥2 were considered as significant. RESULTS Strength training altered 23 pathways in LPS-stimulated PBMC; (IST: 7 upregulated and 2 down-regulated, SET: 5 upregulated and 10 downregulated). None of the altered pathways overlapped between IST and SET. The Cytotoxic T Lymphocyte-mediated Apoptosis of Target Cells pathway was enriched oppositely in both training groups (downregulated in IST versus upregulated in SET). CONCLUSIONS Three months IST and SET can induce changes in the inflammatory stress response of PBMC, but by affecting different genes and related pathways. A balanced exercise program altering both training regimes might therefore provide optimal immune adaptations in older persons.

Abstract A029: Treatment-Specific Immune Phenotypes Identified by nELISA High-Throughput Proteomics Reveal Actionable Insights for Drug Discovery

Abstract Understanding tumor immunology requires high content tools that can capture the complex microenvironment, as well as high-throughput cell-based assays to rapidly screen compounds, antibodies, or cell therapies. Unfortunately, proteomics tools to investigate interactions between cancer and immune cells compromise either content or cost, limiting access to phenotypic data. To overcome this issue, we developed the nELISA: a high-throughput miniaturized ELISA quantifying 191 cytokines, chemokines, proteases and growth factors, at 10x-reduced cost compared to previous tools, and applied it to cell based models to demonstrate its ability to characterize immune phenotypes in co-culture systems. We ran the largest PBMC secretome screen to date, in which ~10,000 PBMC samples were treated with various inflammatory stimuli, and were further perturbed with a selected library of 80 recombinant protein “perturbagens”. 191 secreted proteins were profiled in all samples, resulting in ~2M datapoints. The nELISA profiles were able to capture phenotypes associated with specific stimulation conditions, individual donors, and potent cytokine perturbagens. By compensating for stimulation and donor differences, we clustered perturbagens according to their effects on PBMC secretomes. As expected, perturbagens such as IFN gamma and IL-4 led to well-established Th1 or Th2 responses, respectively, and clustered with perturbagens involved in these phenotypes. Novel phenotypic effects were also identified, such as distinct responses to the near identical CXCL12 alpha and beta isoforms. Interestingly, we observed important similarities between PBMC responses to the cytokine drugs IFN beta and IL-1 Receptor antagonist, supporting the use of the latter as a replacement for the former in certain indications. These findings highlight the ability of the nELISA to capture actionable insights from high-throughput screens, and demonstrate its applicability to SAR studies and drug repurposing screens. Thus, the nELISA is a powerful tool for immunotherapy drug discovery, and we will expand upon its use for target identification, in vitro pharmacology, predicting patient response to therapy, as well as characterizing the potential of iPSC- or donor-derived material for cell therapy. Citation Format: Nathaniel Robichaud, Grant Ongo, Ivan Teahulos, Woojong Rho, Milad Dagher. Treatment-Specific Immune Phenotypes Identified by nELISA High-Throughput Proteomics Reveal Actionable Insights for Drug Discovery [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A029.

A novel Toll-like receptor 7/8–specific antagonist E6742 ameliorates clinically relevant disease parameters in murine models of lupus

The sensing of self RNA by the endosomal Toll-like receptors (TLRs) 7 and 8 initiates pathogenic mechanisms underlying the autoimmune disease lupus. A blockade of the TLR7/8 signals may, therefore, be a novel therapeutic intervention for lupus. To test the hypothesis, a novel compound E6742 that blocks TLR7/8 activation was identified. The mode of action of E6742 was investigated by analysis of the tertiary structure of TLR7 and 8 in complex with E6742. The in vitro activities of the compound were examined in cellular systems and its therapeutic potential was evaluated in murine lupus models. Tertiary structures of the extracellular domain of TLR7 and 8 in complex with E6742 showed that E6742 binds specifically and non-covalently to the hydrophobic pocket located at the interface of TLR7 or TLR8 homodimers. E6742 potently and selectively inhibited several TLR7/8-mediated cytokine responses in human PBMC. In two mouse models of lupus, oral dosing of E6742 after the onset of disease suppressed increase in autoantibodies and blocked the advance of organ damage. Collectively, the data show that TLR7/8 activation contributes to disease progression and its blocking by E6742 has potential as a therapeutic intervention for lupus.

CD4+ and CD8+ T effector memory responses in Chlamydia pneumoniae-stimulated PBMC in non-asthmatic subjects

Chlamydia pneumoniae (C. pneumoniae) is a gram-negative intracellular bacterium that causes respiratory infection. C. pneumoniae infection can trigger asthma symptoms, but may be underdiagnosed. Immunological differences exist between subjects with or without asthma, with regard to host responses to C. pneumoniae. The heterogeneity of asthma can be better understood by analyzing the repertoire of T-cell subpopulations. The aim of this study was to expand existing knowledge of T effector memory (TEM) lymphocytes through identification of C.

Neuropsychological decrements in midlife type-2 diabetes are not associated with peripheral NLRP3 inflammasome responsiveness.

Midlife Type 2 Diabetes Mellitus (T2DM) is associated with an increased risk of Alzheimer Disease (AD) in later life, with altered inflammatory responses postulated as key pathological drivers. Previous studies have demonstrated increased responsiveness to NLR family pyrin domain containing 3 (NLRP3) inflammasome agonists, both in individuals with untreated T2DM in addition to those with established AD. We hypothesised that peripheral NLRP3 inflammasome responses may be altered during the early stages of T2DM-related cognitive dysfunction. Here, we assessed the relationship between NLPR3 responses in peripheral blood mononuclear cells (including to Aβ-42, the putative pathogenic protein in AD) and neuropsychological performance in uncomplicated midlife T2DM to identify early signatures of immune dysregulation which may predispose to later cognitive decline. We recruited a cross-sectional cohort of middle-aged adults with uncomplicated T2DM and matched Healthy Controls (HCs) for comprehensive neuropsychological assessment and in vitro PBMC responses to a range of NLRP3 agonists were assessed. T2DM was associated with subtle decrements on neuropsychological tests of delayed memory and executive function (both p<0.05). Overall, there were no differences between T2DM and HCs in immune responses induced by NLRP3 agonists. Further, we observed no relationship between the subtle neuropsychological decrements observed in T2DM and PBMC responsiveness to NLRP3 agonists. Our data suggests that peripheral NLRP3 inflammasome response dysregulation may not play a role in the early stages of cognitive dysfunction in midlife T2DM. Further longitudinal studies are warranted to examine the contribution of peripheral NLRP3 responses towards disease pathology and as cognitive decline accelerates in T2DM.

A Path-Based Analysis of Infected Cell Line and COVID-19 Patient Transcriptome Reveals Novel Potential Targets and Drugs Against SARS-CoV-2.

Most transcriptomic studies of SARS-CoV-2 infection have focused on differentially expressed genes, which do not necessarily reveal the genes mediating the transcriptomic changes. In contrast, exploiting curated biological network, our PathExt tool identifies central genes from the differentially active paths mediating global transcriptomic response. Here we apply PathExt to multiple cell line infection models of SARS-CoV-2 and other viruses, as well as to COVID-19 patient-derived PBMCs. The central genes mediating SARS-CoV-2 response in cell lines were uniquely enriched for ATP metabolic process, G1/S transition, leukocyte activation and migration. In contrast, PBMC response reveals dysregulated cell-cycle processes. In PBMC, the most frequently central genes are associated with COVID-19 severity. Importantly, relative to differential genes, PathExt-identified genes show greater concordance with several benchmark anti-COVID-19 target gene sets. We propose six novel anti-SARS-CoV-2 targets ADCY2, ADSL, OCRL, TIAM1, PBK, and BUB1, and potential drugs targeting these genes, such as Bemcentinib, Phthalocyanine, and Conivaptan.

Adenovirus-Vectored African Swine Fever Virus pp220 Induces Robust Antibody, IFN-γ, and CTL Responses in Pigs.

African Swine Fever Virus (ASFV) poses a serious threat to the pork industry worldwide; however, there is no safe vaccine or treatment available. The development of an efficacious subunit vaccine will require the identification of protective antigens. The ASFV pp220 polyprotein is essential for virus structural integrity. This polyprotein is processed to generate p5, p34, p14, p37, and p150 individual proteins. Immunization of pigs with a cocktail of adenoviruses expressing the proteins induced significant IgG, IFN-γ-secreting cells, and cytotoxic T lymphocyte responses. Four predicted SLA-I binding nonamer peptides, namely p34161−169, p37859−867, p1501363−1371, and p1501463−1471, recalled strong IFN-γ+ PBMC and splenocyte responses. Notably, peptide p34161−169 was recognized by PBMCs isolated from 7/10 pigs and by splenocytes isolated from 8/10 pigs. Peptides p37859−867 and p1501363−1371 stimulated recall IFN-γ+ responses in PBMCs and splenocytes isolated from 8/10 pigs, whereas peptide p1501463−1471 recalled responses in PBMCs and splenocytes isolated from 7/10 to 9/10 pigs, respectively. The results demonstrate that the pp220 polyprotein contains multiple epitopes that induce robust immune responses in pigs. Importantly, these epitopes are 100% conserved among different ASFV genotypes and were predicted to bind multiple SLA-I alleles. The outcomes suggest that pp220 is a promising candidate for inclusion in a prototype subunit vaccine.

AMP5A modulates Toll-like receptors 7 and 8 single-stranded RNA immune responses in PMA-differentiated THP-1 and PBMC

BackgroundDysregulation of antiviral immunity has been implicated in the progression of acute respiratory syndrome coronavirus 2 infection into severe cases of coronavirus disease of 2019 (COVID-19). Imbalances in the inflammatory response drive the overabundant production of pro-inflammatory cytokines and chemokines. The low molecular weight fraction of 5% human serum albumin commercial preparation (AMP5A) is a novel biologic drug currently under clinical investigation for the treatment of osteoarthritis and the hyperinflammatory response associated with COVID-19. This study aims to elucidate AMP5A effects following the activation of immune cells with agonists of Toll-like receptor (TLR) 7 and/or 8, which detect ssRNA viral sequences.MethodsCXCL10 ELISAs were used to evaluate the dynamics of myeloid cells activated with CL075 and CL307, agonists of TLR7/8 and TLR7, respectively. In addition, enrichment analysis of gene sets generated by ELISA arrays was utilized to gain insight into the biologic processes underlying the identified differentially expressed cytokine profiles. Finally, relative potency (REP) was employed to confirm the involvement of mechanisms of action paramount to AMP5A activity.ResultsAMP5A inhibits the release of CXCL10 from both CL075- and CL307-activated PMA-differentiated THP-1 and peripheral blood mononuclear cells. Furthermore, AMP5A suppresses a distinct set of pro-inflammatory cytokines (including IL-1β, IL-6, IL-12, and CXCL10) associated with COVID-19 and pro-inflammatory NF-κB activation. REP experiments using antagonists specific for the immunomodulatory transcription factors, peroxisome proliferator-activated receptor γ, and aryl hydrocarbon receptor, also indicate that these pathways are involved in the ability of AMP5A to inhibit CXCL10 release.ConclusionDue to the biphasic course of COVID-19, therapeutic approaches that augment antiviral immunity may be more beneficial early in infection, whereas later interventions should focus on inflammation suppression. In this study, we show that AMP5A inhibits TLR 7/8 signaling in myeloid cells, resulting in a decrease in inflammatory mediators associated with hyperinflammation and autoimmunity. Furthermore, data demonstrating that AMP5A activates immunomodulatory transcription factors found to be protective in lung disease is provided. These findings suggest that the modes and mechanisms of action of AMP5A are well suited to treat conditions involving dysregulated TLR 7/8 activation.Graphical

Casein Kinase II exacerbates rheumatoid arthritis via promoting Th1 and Th17 cell inflammatory responses

Objectives : Studies have demonstrated that CK2 is engaged in CD4+ T cell proliferation and activation. We investigated the potential involvement of CK2 in the pathogenesis of rheumatoid arthritis (RA). Methods Peripheral blood and synovial fluid mononuclear cells (PBMC and SFMC) of RA patients, as well as splenocytes of collagen-induced arthritis (CIA) mice were treated with different doses of CK2 inhibitor CX4945 in vitro. Then, the Th1, Th2, Th17, and Treg cell responses were analyzed. In addition, CIA mice were administrated with CX4945 via oral gavage. Accordingly, the arthritis scores, bone destruction, tissue damage, and the CD4+ T cell subsets were assessed. Results The expression of CK2 was upregulated in CD4+ T cells under RA circumstance. In vitro CX4945 treatment significantly inhibited the Th1 and Th17 cell responses, while promoted the Th2 cell responses in RA patient PBMC, SFMC and CIA mouse splenocytes, dampening IFN-γ and IL-17A production. Moreover, administration of CX4945 ameliorated the severity of arthritis in CIA mice, along with decreased Th1 and Th17 cells. However, CX4945 seemed to have minimal effect on RA Treg cells. Conclusion CK2 serves as an important regulator of the Th1 and Th17 cell axes in RA, thus contributing to the disease aggravation.

Banana Lectin from Musa paradisiaca Is Mitogenic for Cow and Pig PBMC via IL-2 Pathway and ELF1

The aim of the study was to gain deeper insights in the potential of polyclonal stimulation of PBMC with banana lectin (BanLec) from Musa paradisiaca. BanLec induced a marked proliferative response in cow and pig PBMC, but was strongest in pigs, where it induced an even higher proliferation rate than Concanavalin A. Molecular processes associated with respective responses in porcine PBMC were examined with differential proteome analyses. Discovery proteomic experiments was applied to BanLec stimulated PBMC and cellular and secretome responses were analyzed with label free LC-MS/MS. In PBMC, 3955 proteins were identified. After polyclonal stimulation with BanLec, 459 proteins showed significantly changed abundance in PBMC. In respective PBMC secretomes, 2867 proteins were identified with 231 differentially expressed candidates as reaction to BanLec stimulation. The transcription factor “E74 like ETS transcription factor 1 (ELF1)” was solely enriched in BanLec stimulated PBMC. BanLec induced secretion of several immune regulators, amongst them positive regulators of activated T cell proliferation and Jak-STAT signaling pathway. Top changed immune proteins were CD226, CD27, IFNG, IL18, IL2, CXCL10, LAT, ICOS, IL2RA, LAG3, and CD300C. BanLec stimulates PBMC of cows and pigs polyclonally and induces IL2 pathway and further proinflammatory cytokines. Proteomics data are available via ProteomeXchange with identifier PXD027505.

Impairment of effector molecules response in diabetes induces susceptibility to Leishmania amazonensis infection

Type 2 Diabetes is a chronic disease resulting from insulin dysfunction that triggers a low-grade inflammatory state and immune impairment. Leishmaniasis is an infectious disease characterized by chronic inflammation resulted from the parasite's immunomodulation ability. Thus, due to the delicate immune balance required in the combat and resistance to Leishmania infection and the chronic deregulation of the inflammatory response observed in type 2 diabetes, we evaluated the response of PBMC from diabetic patients to in vitro Leishmania amazonensis infection. For that, peripheral blood was collected from 25 diabetic patients and 25 healthy controls matched for age for cells extraction and subsequent experimental infection for 2 or 24 h and analyzed for phagocytic and leishmanicidal capacity by optical microscopy, oxidative stress by GSSG generation, labeling of intracellular mediators by enzyme-Linked immunosorbent assay, and cytokines measurement with cytometric beads array technique. We found that the diabetic group had a higher percentage of infected cells and a greater number of amastigotes per cell. Also, even inducing NF-kB phosphorylation and increasing TNF production after infection, cells from diabetic patients were unable to downregulate NRF2 and generate oxidative stress, which may be associated with the exacerbated levels of IL-6 observed. PBMC of diabetic individuals are more susceptible to infection by L. amazonensis and fail to control the infection over time due to the inability to generate effector microbicidal molecules.

Oral Vaccination Approaches for Anti-SHIV Immunity.

We modified a Sabin Oral Poliovirus Vaccine (OPV) vector to permit secretion of the antigens of interest with the goal of improving anti-HIV Env humoral responses in a SHIV mucosal immunization composed of DNA and recombinant OPVs. We evaluated stimulation of systemic and mucosal cell-mediated and humoral immunity in Rhesus macaques by two regimens, both involving a prime with a SHIVBG505 DNA construct producing non-infectious particles formulated in lipid nanoparticles, administered in the oral cavity, and two different viral vector boostings, administered in the oral cavity and intestinally. Group 1 was boosted with rMVA-SHIVBG505, expressing SIV Gag/Pol and HIVBG505 Env. Group 2 was boosted with a SHIVBG505-OPV vaccine including a non-secreting SIVmac239CA-p6-OPV, expressing Gag CA, NC and p6 proteins, and a HIVBG505C1-V2-OPV, secreting the C1-V2 fragment of HIV EnvBG505, recognized by the broadly neutralizing antibody PG16. A time course analysis of anti-SHIV Gag and Env CD4+ and CD8+ T-cell responses in PBMC and in lymph node, rectal, and vaginal MNC was carried out. Both regimens stimulated significant cell-mediated responses in all compartments, with SHIVBG505-OPV immunization stimulating more significant levels of responses than rMVA- SHIVBG505. Boolean analysis of these responses revealed predominantly monofunctional responses with multifunctional responses also present in all tissues. Stimulation of antibody responses was disappointing in both groups with negative anti-SHIV IgG in plasma, and IgA in salivary, rectal and vaginal secretions being restricted to a few animals. After repeated rectal challenge with SHIVBG505, two Group 1 animals remained uninfected at challenge termination. No significant differences were observed in post-infection viral loads between groups. After the acute phase decline, CD4+ T cell percentages returned to normal levels in vaccinated as well as control animals. However, when compared to controls, vaccinate groups had more significant preservation of PBMC and rectal MNC Th17/Treg ratios, considered the strongest surrogate marker of progression to AIDS. We conclude that the vaccine platforms used in this study are insufficient to stimulate significant humoral immunity at the tested doses and schedule but sufficient to stimulate significant mucosal and systemic cell-mediated immunity, impacting the preservation of key Th17 CD4+ T cells in blood and rectal mucosa.

Intravenous BCG protects SIV+ macaques from tuberculosis.

Abstract Tuberculosis is the most common cause of death due to infection in people living with HIV (PLHIV). BCG, a live attenuated Mycobacterium bovis strain given intradermally to infants, is the only licensed vaccine to prevent TB. However, intradermal BCG offers little protection from pulmonary TB in adults and safety concerns limit its use in PLHIV. Recently, intravenous (IV) BCG has been shown to provide striking protection from TB in rhesus macaques. Given this dramatic success, we tested whether IV BCG could protect macaques with a pre-existing SIV infection using our established model of SIV/Mtb coinfection in Mauritian cynomolgus macaques (MCM). MCM were intrarectally infected with SIVmac239 and 5 months later were vaccinated with BCG at 8 ×107 CFU delivered IV. To prevent disseminated BCG disease in immunocompromised animals, four weeks after IV vaccination animals were treated with an 8-week regimen of isoniazid/rifampin/ethambutol (HRE). Four weeks after HRE cessation, animals were challenged with low-dose Mtb Erdman. SIV+ MCM exhibited no signs of BCG disease before or after HRE treatment. Following BCG vaccination, a rapid and sustained increase in airway T cells was observed in both SIV+ and SIV-naïve animals. Increased antibody titers to Mtb lysate were observed in plasma and airways following IV BCG. PBMC responses to Mtb-specific stimuli by IFNγ ELISpot indicated rapid and early clearance of Mtb in vaccinated animals regardless of SIV infection. All SIV-naïve (n=7) and 7 out of 10 SIV+, vaccinated animals were free of TB and without culturable bacilli in their tissues at 12 weeks post challenge. Flow cytometric analysis of PBMCs and tissues obtained at necropsy are underway to further define immune correlates of protection.

Anti-LYPD1/CD3 T-Cell-Dependent Bispecific Antibody for the Treatment of Ovarian Cancer.

Ovarian cancer is a diverse class of tumors with very few effective treatment options and suboptimal response rates in early clinical studies using immunotherapies. Here we describe LY6/PLAUR domain containing 1 (LYPD1) as a novel target for therapeutic antibodies for the treatment of ovarian cancer. LYPD1 is broadly expressed in both primary and metastatic ovarian cancer with ∼70% prevalence in the serous cancer subset. Bispecific antibodies targeting CD3 on T cells and a tumor antigen on cancer cells have demonstrated significant clinical activity in hematologic cancers. We have developed an anti-LYPD1/CD3 T-cell-dependent bispecific antibody (TDB) to redirect T-cell responses to LYPD1 expressing ovarian cancer. Here we characterize the nonclinical pharmacology of anti-LYPD1/CD3 TDB and show induction of a robust polyclonal T-cell activation and target dependent killing of LYPD1 expressing ovarian cancer cells resulting in efficient in vivo antitumor responses in PBMC reconstituted immune-deficient mice and human CD3 transgenic mouse models. Anti-LYPD1/CD3 TDB is generally well tolerated at high-dose levels in mice, a pharmacologically relevant species, and showed no evidence of toxicity or damage to LYPD1 expressing tissues.

An observational study of innate immune responses in patients with acute appendicitis

Acute appendicitis is a common surgical emergency worldwide. Exaggerated immune responses could be associated with appendicitis. This study aimed at characterizing immune responses towards a large variety of gut commensals and pathogens, and pattern recognition receptor (PRR) ligands, and investigating the course of systemic inflammation in a prospective cohort of acute appendicitis patients. PBMC responses of 23 patients of the cohort and 23 healthy controls were characterized more than 8 months post-surgery. Serum cytokine levels were measured in 23 patients at the time of appendicitis and after one month. CRP, WBC and percentage of neutrophils were analyzed in the total cohort of 325 patients. No differences in PBMC responses were found between patients and controls. Stronger IL-10 responses were found following complicated appendicitis. A trend towards lower IL-8 responses was shown following gangrenous appendicitis. Serum IL-10 and IL-6 were significantly elevated at presentation, and IL-6, IL-8 and TNF-α levels were higher in complicated appendicitis. Routine biomarkers could predict severity of appendicitis with high specificities, but low sensitivities. Cytokine responses in patients following acute appendicitis did not differ from healthy controls. Higher serum cytokine levels were found in acute complicated and gangrenous cases. Further research into discriminative biomarkers is warranted.

Abstract 3266: BND-22, a first-in-class, anti-ILT2 monoclonal antibody inhibits the immunosuppressive effects of HLA-G and enhances anti-tumor activity of immune cells in preclinical in vitro, ex vivo, and in vivo models

Abstract Background: Ig-like transcripts (ILTs) are a family of immuno-modulating receptors expressed on immune cells. ILT2 is an inhibitory receptor expressed on both innate and adaptive immune cells. It has been shown to bind to MHC class I molecules and binds with the highest affinity to HLA-G, an immunosuppressive MHC molecule expressed by multiple tumor types. ILT2-mediated inhibition can lead to impairment of immune cell proliferation, differentiation, phagocytosis, cytotoxicity and cytokine secretion, identifying the ILT2 signaling axis as a potential novel target for anti-cancer immunotherapy. Here we describe preclinical characterization of BND-22, a humanized IgG4, ILT2 antagonist antibody developed for the treatment of solid tumors. Methods: BND-22 binding to ILT2 was evaluated by flow cytometry, ELISA and surface plasmon resonance. We investigated the ability of BND-22 to reverse ILT2-mediated immune suppression of macrophages and lymphocytes. Macrophage and NK cell effector functions were studied in vitro and ex vivo in the presence of several cancer cell lines and patient tumor tissues using flow cytometry, time-lapse live-cell-microscopy, and functional cell-based assays. Xenograft subcutaneous melanoma and colorectal carcinoma and melanoma lung metastases models were used to evaluate the in vivo anti-tumor effect of BND-22. Results: BND-22 binds ILT2, but not other ILT-family receptors, with low nanomolar affinity and blocks its interaction with HLA-G in a concentration-dependent manner. ILT2 blockade with BND-22 increased macrophage-mediated phagocytosis of tumor cell lines and patient-excised tumors, enhanced the cytotoxicity of NK cells against multiple types of cancer cells, and increased NK cell production of Granzyme B and IFNγ. ILT2 and PD-1 were found to be expressed by different sub-populations of CD45+ cells. Co-blockade of ILT2 and PD-1 showed a synergistic effect in increasing pro-inflammatory cytokine production by patient-derived PBMC in response to autologous tumor cells. In subcutaneous melanoma and colorectal carcinoma xenograft mouse models, BND-22 enhanced the anti-tumor activity of macrophages, inhibited tumor growth and prolonged survival. BND-22 also potently increased the anti-tumor activity of lymphocytes and inhibited metastases spread in an in vivo melanoma lung lesion model. Conclusions: BND-22, a first-in-class, anti-ILT2 antagonist antibody induces a potent macrophage and lymphocyte-driven anti-tumor immune response in multiple in vitro, ex vivo and in vivo models. BND-22 offers a differentiated, multi immune cell-based mechanism of action. Safety, tolerability, and anti-tumor activity of BND-22 will be explored in a first-in-human clinical trial in cancer patients with tumor types known to express HLA-G. Citation Format: Ilana Mandel, Dana Haves, Ilana Goldshtein, Tsuri Peretz, Dror Alishekevitz, Yair Sapir, Sharon Hashmueli, Itay Friedman, Tehila Ben Moshe. BND-22, a first-in-class, anti-ILT2 monoclonal antibody inhibits the immunosuppressive effects of HLA-G and enhances anti-tumor activity of immune cells in preclinical in vitro, ex vivo, and in vivo models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3266.

A helminth-derived suppressor of ST2 blocks allergic responses.

The IL-33-ST2 pathway is an important initiator of type 2 immune responses. We previously characterised the HpARI protein secreted by the model intestinal nematode Heligmosomoides polygyrus, which binds and blocks IL-33. Here, we identify H. polygyrus Binds Alarmin Receptor and Inhibits (HpBARI) and HpBARI_Hom2, both of which consist of complement control protein (CCP) domains, similarly to the immunomodulatory HpARI and Hp-TGM proteins. HpBARI binds murine ST2, inhibiting cell surface detection of ST2, preventing IL-33-ST2 interactions, and inhibiting IL-33 responses in vitro and in an in vivo mouse model of asthma. In H. polygyrus infection, ST2 detection is abrogated in the peritoneal cavity and lung, consistent with systemic effects of HpBARI. HpBARI_Hom2 also binds human ST2 with high affinity, and effectively blocks human PBMC responses to IL-33. Thus, we show that H. polygyrus blocks the IL-33 pathway via both HpARI which blocks the cytokine, and also HpBARI which blocks the receptor.