Human IL-2 Research Articles

Abstract 2837: Conservation of JAK-STAT signaling in canine lymphocytes responding to human IL-6, IL-7, and IL-1 alpha

Abstract Dogs share physiological similarities with humans, positioning them as valuable models for studying the efficacy and safety of drugs and their underlying mechanisms of action. The JAK-STAT pathway, a highly conserved signaling pathway across species, including humans and dogs, presents an opportunity to investigate the therapeutic potential of cytokines that utilize this pathway. In this study, we aimed to evaluate the functional activity of three canine cytokines on canine cells. To assess stimulation of the JAK/STAT pathway, we used a flow cytometry assay that measures phospho-STAT in activated canine or human lymphocytes in whole blood specimens. Testing of commercially available human and canine IL-6 proteins revealed that canine lymphocytes respond poorly to most canine IL-6 products, whereas all recombinant human IL-6 products stimulated STAT phosphorylation in canine lymphocytes, despite sharing low sequence similarity with canine IL-6. In human T cells, both canine IL-6 and human IL-6 stimulated STAT phosphorylation, demonstrating biological activity from the canine IL-6 products. Several JAK inhibitors inhibited cytokine-induced STAT phosphorylation in both canine and human CD4 T-cells, consistent with JAK inhibition, but targeting the IL-6 receptor with tocilizumab only blocked IL-6-induced STAT phosphorylation in human but not canine CD4 T-cells in whole blood. These findings demonstrate the potential of our assay system to assess cross-species cytokine reactivity, determine if JAK/STAT inhibitors used clinically might be useful in treating inflammatory conditions in dogs, and identify novel canine-specific inhibitors. Additionally, we explored the induction of IL-8 by human and canine IL-1 alpha in IL-1 alpha sensitive human cells. Human IL-1 alpha failed to stimulate a canine IL-1 alpha sensitive cell line, suggesting species-specific differences in IL-1 alpha activity. Furthermore, we discovered that canine IL-7 and human IL-7 are species-specific. In summary, this proof-of-concept study highlights the capability to assess the activation of STATs and pathway inhibition by JAK inhibitors in canine whole blood using flow cytometry. We confirmed that human IL-6 stimulates JAK/STAT signaling in canine CD4 T-cells. Our results also revealed significant differences in species cross-reactivity of human IL-6, IL-7, and IL-1 alpha, underscoring the importance of species-specific investigations. Leveraging the similarities and differences between canine and human cytokines targeting the JAK-STAT pathway can enhance drug development efforts and contribute to the advancement of safer and more effective therapies for both humans and pet dogs with similar diseases. This study was funded by NCI Contract No. 75N91019D00024. Citation Format: King Leung Fung, Melissa L. Breiner, James B. Mitchell, Ralph E. Parchment. Conservation of JAK-STAT signaling in canine lymphocytes responding to human IL-6, IL-7, and IL-1 alpha [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 2837.

Abstract 5339: Establishment of a humanized IL5/IL5RA mouse model to evaluate modulators of eosinophilic inflammation in vivo

Abstract IL-5/IL-5R signaling plays a key role in the maturation, activation, survival, and recruitment of eosinophils to sites of inflammation. Targeting this pathway is an attractive therapeutic strategy for certain inflammatory diseases, such as asthma. Here, we generated a novel humanized IL5/IL5RA model (B-hIL5/hIL5RA) to examine the utility of human IL-5/IL5R-targeting therapeutic candidates. Specifically, the entire murine Il5 coding region was replaced by the corresponding human IL5 sequence, and the human IL5RA sequence coding the extracellular domain was inserted to replace the corresponding murine sequence. Successful generation of the model was confirmed by expression of human IL-5 by ELISA and IL5RA by flow cytometry. Furthermore, the proportion of eosinophils in the blood of B-hIL5/hIL5RA mice increased after stimulation with human IL5 recombinant protein, indicating that the humanized IL5RA protein is functional. Next, the ability of the humanized mice to establish asthma-like disease was tested using ovalbumin: following a 14 day sensitization period, mice were challenged with nebulized OVA daily from day 21 until the endpoint; treatment with mepolizumab or benralizumab analog was performed. Flow cytometric analysis of the bronchioalveolar fluid indicates that treatment with mepolizumab or benralizumab analog significantly lowered the number of eosinophils when compared to the isotype control in homozygous B-hIL5/hIL5RA mice. Blood counts and quantification of lung H&E sections also confirm that the treatments lowered the number of eosinophils in circulation and lung tissue, respectively. Taken together, these data indicate that B-hIL5/hIL5RA mice are a suitable preclinical model to test novel modulators of human IL-5/IL-5RA signaling. Citation Format: Suman Zhao, Shujin Zhang, Zhen Chen, Liya Yang, Mari Kuraguchi, Jiangfeng Yuan, Heiling Shen. Establishment of a humanized IL5/IL5RA mouse model to evaluate modulators of eosinophilic inflammation in vivo [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 5339.

Abstract 4189: BALB/c-hIL12RB1/hIL12RB2: A robust model for preclinical research in human IL-12 therapy

Abstract Interleukin-12 (IL-12) is a multifaceted cytokine primarily produced by antigen-activated dendritic cells, macrophages, and neutrophils. Its receptor is a composite of IL12RB1 and IL12RB2, and the union of these two subunits forms a high-affinity receptor complex proficient in mediating IL-12 signaling. As a pivotal regulator of innate and adaptive immunity, IL-12 plays a crucial role in steering the differentiation of naïve T cells into Th1 cells. It is renowned as a T cell stimulatory factor, fostering T cell proliferation. Furthermore, IL-12 has the capacity to augment the activation of cytotoxic lymphocytes and natural killer cells (NK), thereby enhancing interferon (IFN-γ) production. Empirical evidence consistently demonstrates that IL-12 synergistically exerts anti-tumor effects in conjunction with various immune cells, such as T cells and NK cells. Its effectiveness in preclinical studies has solidified IL-12 as an appealing drug target, leading to the development of activating antibodies, therapeutic IL-12 proteins, and tumor vaccines as potential treatments. To delve deeper into the functionality and therapeutic potential of IL-12, we have engineered a humanized mouse model, known as BALB/c-hIL12RB1/hIL12RB2. Notably, this model fully preserves the intracellular domains of mouse IL12RB1 and IL12RB2 proteins, ensuring the normal propagation of intracellular signaling. It also effectively expresses human IL12RB1 and IL12RB2. In vitro functional validation experiments have verified that BALB/c-hIL12RB1/hIL12RB2 mice can proficiently generate IFN-γ when induced by human IL-12. Furthermore, in vivo efficacy experiments have yielded compelling results. Intratumoral administration of human IL-12 mRNA in BALB/c-hIL12RB1/hIL12RB2 mice led to a significant suppression in the growth of CT26 tumors, culminating in complete tumor regression. Subsequent rechallenge experiments conducted after the discontinuation of treatment revealed no tumor recurrence, signifying the enduring inhibitory effect of hIL12 mRNA on mouse tumors. In conclusion, the development of BALB/c-hIL12RB1/hIL12RB2 mice stands as a robust model for advancing preclinical research in the realm of human IL-12 therapy. Citation Format: Yuan Fang, Huiyi Wang, Jun Xing, Lu Yang, Jing Zhao, Xiang Gao, Cunxiang Ju. BALB/c-hIL12RB1/hIL12RB2: A robust model for preclinical research in human IL-12 therapy [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 4189.

Abstract 112: The NSG-Flt3KO; Tg(hFLT3LG); hIL15 mouse strain improves engraftment of innate immune cells post-CD34+ humanization

Abstract Human immune system mouse models play critical roles in numerous preclinical drug development pipelines, including immunology, infectious diseases, and immuno-oncology. These models are constantly evolving, with addition of human cytokines to sustain engraftment of human immune cells. To date, most humanized models have primarily focused on T lymphocyte cell biology, leaving room for improvement in developing models that effectively represent NK cells and the myeloid lineage. Previously, we demonstrated that the introduction of human IL-15 (NSG-IL-15) or FLT3L (NSG-FLT3L) to NOD-scid IL2rγnull (NSG) mice enhanced engraftment of innate immune cells, including human CD56+ NK cells, CD141+ and CD1c+ DC subsets, CD123+ pDCs, and CD14+ monocytes. In this study, we describe a new NSG mouse variant (NSG-Flt3KO; Tg(hFLT3LG); hIL15) that expresses physiological levels of both human IL-15 and FLT3L and detail the immune cell diversity following HSC engraftment. NSG-Flt3KO; Tg(hFLT3LG); hIL15 mice, along with control strains NSG, NSG-IL15, and NSG-FLT3L, were engrafted with human umbilical cord blood derived CD34+ hematopoietic stem cells from three different donors, and blood samples were collected until Week 20 post-transplantation. Blood samples were analyzed via flow cytometry to assess the engraftment of innate and adaptive immune cells. Spleen and bone marrow samples were collected at Week 12 post-transplantation and analyzed for lymphoid and myeloid immune cell populations via flow cytometry. To compare the differences among the strains in terms of immune cell sub-populations across weeks, a Two-Way ANOVA (mixed-model) was conducted, with p<0.05 considered statistically significant. Overall, the results demonstrate that NSG-Flt3KO; Tg(hFLT3LG); hIL15 mice have enhanced CD56+/dim CD16+ NK cells compared to NSG-FTL3L strain (20.5±12.8% vs 7.0±3.5% at Week 12), but comparable to NSG-IL15. Furthermore, myeloid sub-lineage cells in NSG-IL15-FLT3L mice, such as monocytes, macrophages (M1), granulocytes, dendritic cells, and neutrophils, were greater than in NSG or NSG-IL15 strains, but comparable to NSG-FLT3L mice. Overall levels of hCD45+ and T cell sub-populations (CD3+ or CD4+ or CD8+) were comparable across all strains tested. In sum, our NSG-Flt3KO; Tg(hFLT3LG); hIL15 engraftment data suggest an improved model that supports drug development targeting human myeloid and NK cell populations. Citation Format: Srinivas Reddy Boreddy, Shuang Hu, Brian Soper. The NSG-Flt3KO; Tg(hFLT3LG); hIL15 mouse strain improves engraftment of innate immune cells post-CD34+ humanization [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 112.

Abstract 1405: Development of a humanized anti-IL-22 antibody for cancer and inflammation therapy

Abstract Interleukin-22 (IL-22) is an inflammatory cytokine involved in the pathology of autoimmune diseases such as psoriasis, atopic dermatitis, and ulcerative colitis. IL-22 has also been shown to promote epithelial cell proliferation, stemness and tumorigenesis in cancer, and is associated with a more aggressive phenotype in a variety of cancers including inflammatory colon cancer models. IL-22 plays a central role in this pathogenic process by driving activation of STAT3 and other signaling cascades. Recent studies demonstrated that neutralization of IL-22 reduced dysplasia and tumor development in preclinical models. However, there has not been a clear application for anti-IL-22 therapy for cancer and autoimmune diseases, likely due to identifying the right disease indication and their low potency and efficacy. Thus, there remains an opportunity to explore the potential of more potent anti-IL-22 therapeutics. We have developed humanized anti-IL-22 antibodies with high affinities to human, cynomolgus and mouse IL-22 using BioAtla’s proprietary antibody discovery and engineering platforms. In vitro data demonstrated that our anti-IL-22 antibodies inhibited IL-22-induced p-STAT3 activities. In addition, our antibodies showed a 10-fold increased binding activity to human IL-22 compared to Fezakinumab, which was previously developed by Pfizer for the treatment of autoimmune diseases. To test the functions of our antibodies in vivo, we established an inflammation-driven sporadic colitis-associated colorectal (CAC) cancer mouse model. Our humanized anti-IL-22 antibody, a potent, species cross-reactive anti-IL-22 blocking antibody, significantly reduced tumor progression in CAC model. These data suggest that targeting IL-22 reduces tumor occurrence by reducing inflammation-induced tumorigenesis. In addition, we evaluated our anti-IL22 antibodies in an imiquimod-induced psoriasiform skin inflammation mouse model. The mice treated with anti-IL22 antibodies had significantly reduced skin lesions compared to isotype antibody-treated mice. Q-PCR analysis of the mouse skin demonstrated that treatment with our anti-IL-22 antibody led to significantly decreased RNA levels of the imiquimod-induced inflammatory marker CXCL3. In conclusion, the development of a potent, species cross-reactive anti-IL-22 antibody using BioAtla’s antibody discovery and engineering platforms addresses the past challenges of anti-IL-22 therapeutics and allows for translational studies in relevant animal efficacy and safety models. Citation Format: Jian Chen, Cathy Chang, Gerhard Frey, Haizhen Liu, Jing Wang, William J. Boyle, Jay M. Short. Development of a humanized anti-IL-22 antibody for cancer and inflammation therapy [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 1405.

Abstract 6312: Orthogonal IL-2/IL-2Rβ signaling selectively enhances and sustains a synthetic effector state via a novel mechanism and outperforms constitutive armoring approaches

Abstract CAR T cell therapy has demonstrated remarkable clinical efficacy against blood malignancies. However, prominent barriers, including limited proliferation, CAR T cell persistence, and poor T cell effector function, hinder its potential, especially in solid tumors. Various engineering approaches attempt to address these issues by armoring CAR T cells with factors that enhance the function and maintenance of T cells in the anti-tumor response. We previously described a human orthogonal IL-2/IL-2R system consisting of a pegylated, IL-2 mutein (STK- 009) that does not significantly activate the wild type receptor and a mutated IL-2 Receptor Beta (oRβ) that does not significantly respond to its native ligand, wild type IL-2. This system provides a “private IL-2 signal” in engineered oRβ-expressing cells while avoiding signaling in bystander immune cells, reducing toxicities. We have demonstrated STK-009/oRβ’s ability to selectively expand oRβ-expressing CAR T cells (SYNCAR T cells) targeting heme (SYNCAR-001, CD19) and solid tumor (SYNCAR-002, GPC3) targets at will. Importantly, the system enhanced anti-tumor control driving deep and durable responses in both bulky lymphoma and hepatocellular carcinoma (HCC) tumor models. Additionally, in a non-human primate model, STK-009 did not potentiate wild type T or NK cells and exhibited no evidence of toxicity. Currently, the combination of STK-009 + SYNCAR-001 is undergoing Phase I clinical trials (NCT05665062). Here, we conducted a direct comparison of several armoring approaches including the SYNCAR platform, the overexpression of c-Jun, an IL-15/IL-15Rα fusion, and IL-18 in human CAR T cells targeting GPC3. To assess their effects in overcoming CAR T cell dysfunction, cells were subjected to continuous antigen exposure in vitro. STK-009 treated SYNCAR-002 T cells displayed an enhanced proliferative capacity, sustained effector cytokine secretion, and an increased activation state when compared to other armoring technologies and PBS treatment. In a HCC tumor model, treatment with STK-009/SYNCAR-002 demonstrated superior tumor control with minimal toxicities. Interestingly, IL-18 overexpression also controlled tumors, but was accompanied by uncontrolled CAR T cell expansion and toxicity resembling severe GVHD. scRNAseq analyses revealed STK-009-treated SYNCAR-002 T cells simultaneously activated effector genes and repressed an exhaustion gene signature. This analysis also identified a novel mechanism by which STK-009/oRβ signaling induces a superior synthetic effector state via transcriptional repression of the stress response/proteosome. These findings support the advantages of an orthogonal platform that selectively drives and sustains potent T cell effector function without safety concerns associated with constitutively expressed armored approaches. Citation Format: Ethan Jung, Helena Silva, Marie Semana, Ivan Cheng, Somya Singh, Michele Bauer, Mohammed Ali, Henry Rosas, Ryan Burgess, George Zeng, Woei Chang, Navneet Ratti, Deepti Rokkam, Patrick J. Lupardus, Martin Oft, Paul-Joseph Aspuria. Orthogonal IL-2/IL-2Rβ signaling selectively enhances and sustains a synthetic effector state via a novel mechanism and outperforms constitutive armoring approaches [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 6312.

Abstract 4074: Discovery of WTX-518, an IL-18 pro-drug that is conditionally activated within the tumor microenvironment and induces regressions in mouse tumor models

Abstract Systemic administration of proinflammatory cytokines is a promising approach to treat cancer. IL-18 has been shown to promote activation of both innate and adaptive anti-tumor responses in pre-clinical models. Specifically, IL-18 has been shown to impact macrophage suppressive function as well as drive CD4+ T cells towards a TH1 phenotype. However, IL-18 therapies have been hampered by a lack of efficacy due to the suppressive activity of IL-18 binding protein (IL-18BP), which binds to IL-18 and prevents its interaction with its receptor. Several groups have taken the approach of modifying IL-18 to render it resistant to IL-18BP as a potential strategy to enhance anti-tumor activity. To explore the therapeutic benefit of delivering a conditionally-activated IL-18 to the tumor microenvironment, we have developed inducible polypeptides (INDUKINE™ molecules) consisting of mouse IL-18 or IL-18BP resistant IL-18 (BPR IL-18) tethered via protease-sensitive linkers to a high affinity antibody blockade domain, and a half-life extension (HLE) domain which improves exposure in the tumor. IL-18 INDUKINE™ molecules are inactive until reaching the tumor microenvironment, where the linkers are cleaved by intra-tumoral proteases, releasing active IL-18. Intraperitoneal (i.p.) administration of an IL-18BP resistant IL-18 (BPR IL-18) INDUKINE™ molecule led to complete tumor regression in the MC38 tumor model. In contrast, equimolar doses of wild-type IL-18 INDUKINE™ protein were not as efficacious. Moreover, BPR IL-18 INDUKINE treatment led to increased activation and frequencies of NK cells and tumor specific CD8 T cells in MC38 tumors. WTX-518 is a novel INDUKINE™ molecule that is designed to selectively deliver active human BPR IL-18 to the tumor microenvironment. WTX-518 is inducible in vitro, either when tested using a reporter assay or primary immune cells. Importantly, the active BPR IL-18 payload is resistant to IL-18BP in reporter or primary immune cell assays. WTX-518 is also selectively inducible, as incubation ex vivo with various primary human tumors led to the release of active BPR IL-18, while WTX-518 was stable in human serum and after exposure to primary cells from healthy tissues. Pharmacological and efficacy data support continued preclinical development of this innovative and differentiated engineered IL-18 therapy. Citation Format: Kristin R. Morris, Heather Brodkin, Kyriakos Economides, Daniel J. Hicklin, Julie LePrevost, Celesztina Nagy-Domonkos, Christopher Nirschl, Andres Salmeron, Cynthia Seidel-Dugan, Cierra Spencer, Zoe Steuert, William M. Winston. Discovery of WTX-518, an IL-18 pro-drug that is conditionally activated within the tumor microenvironment and induces regressions in mouse tumor models [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 4074.

Abstract 6744: Activating anti-MDS immunity with polarized dendritic cell vaccines

Abstract Less than 50% of patients with higher-risk myelodysplastic syndromes (MDS) show clinical response to standard-of-care hypomethylating (HMA) therapy. Significant enthusiasm existed for immunotherapy/HMA combinations for these patients, but studies have failed to deliver on the initial promise. We have demonstrated that patients with MDS have a deficiency in antigen-presenting cells, called CD141Hi dendritic cells (DC). DC-deficient MDS patients have reduced response to HMAs, worse overall survival, and show less response to cancer vaccination. We hypothesized that restoration of this population using a novel DC vaccination approach - alpha-type-1 polarized dendritic cells (αDC1) - might compensate for this deficiency and restore immunity. To generate αDC1s, we collected monocytes from MDS patients and healthy donors (HD) and cultured them for 6 days in vitro in the presence of recombinant human GM-CSF and IL-4 followed by an additional 18-24 hours in the presence of αDC1 maturation factors (poly-I:C/IFNα/IFNγ/TNFα/IL-1β). Overall, we attempted to generate αDC1s from 15 MDS samples; 13/15 exhibited intermediate to very high-risk disease and 10/15 are currently receiving HMA therapy. We successfully cultured cells from 8/15 samples (53%). Of the 8 MDS samples, 5 were collected from patients receiving HMA therapy (62.5%). We were unable to successfully culture αDC1s from the other 5 patients receiving HMA therapy, and thus the effect of HMA therapy on aDC1 generation remains unclear. To test the function of MDS αDC1s, we focused on two signals necessary to activate immune responses: 1) the expression of co-stimulatory molecules and 2) the production of IL-12p70. Flow cytometric analysis on αDC1s and immature DCs from MDS samples revealed intra-patient variation in the fold-change surface expression of CD40/80/83/86 and HLA-DR proteins. Additionally, there was a trend towards decreased up-regulation of CD80 and CD86 in MDS specimens compared to HD. To assess production of IL-12p70, we stimulated immature DCs and αDC1s with CD40L and performed ELISA analysis on the media supernatant. We found that 3 out of 4 samples could produce IL-12p70 (range 27 - 5,480 pg/ml). To date, our results suggest that generation of MDS patient-derived αDC1 cells is feasible and additional work is being performed to fully characterize their ability to activate anti-MDS immune responses. Since αDC1s have an established safety profile in patients with solid tumors, we anticipate that we will be able to rapidly translate our results to the clinic. Citation Format: Daniel Alvarado, Jennifer Peresie, Adam Brinkman, Cheryl Allen, Weijian Jiang, Pawel Kalinski, Tiffany Tanaka, Elizabeth Griffiths, Michael Nemeth. Activating anti-MDS immunity with polarized dendritic cell vaccines [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 6744.

Abstract 37: IL-4 drives CART cell exhaustion in a CD4 independent manner

Abstract While chimeric antigen receptor T (CART) cell therapy has shown remarkable success, the development of exhaustion limits durable response. We identified a role for interleukin (IL)-4 in the development of CART cell exhaustion through three independent approaches including: 1) a genome-wide CRISPR knockout screen using healthy donor CART cells in an in vitro model for exhaustion, 2) RNA and ATAC sequencing on freshly produced and chronically stimulated healthy donor CART cells, and 3) RNA and ATAC sequencing on pre-infusion CART cell products from responders and non-responders in the Zuma-1 clinical trial that led to the FDA approval of axi-cel. Further, in vitro validation studies revealed that CD19 directed CART (CART19) cells chronically stimulated in the presence of human recombinant IL-4 (hrIL-4) displayed signs of exhaustion such as 1) decreased proliferation (p = 0.01), 2) increased coexpression of inhibitory receptors (p = 0.01), and 3) decreased production of IL-2 and interferon (IFN)-γ (p= 0.02, p = 0.002). Encouragingly, CART19 cells combined with an IL-4 monoclonal antibody improved antitumor activity (p = 0.045) and expansion (p = 0.01) while also decreasing the co-expression of inhibitory receptors (p = 0.02) in a mantle cell lymphoma xenograft mouse model. Building on these results, we asked if IL-4 driven exhaustion results from a direct impact of IL-4 on CART cells. To test this, we used a tumor-free assay where CART19 cells were chronically stimulated with CD19 beads in the presence of hrIL-4 or diluent. CART cells treated with hrIL-4 displayed an exhausted phenotype characterized by increased co-expression of inhibitory receptors (p = 0.04) and decreased production of IL-2 (p = 0.01). Next, we asked if IL-4 driven CART cell exhaustion is dependent on the costimulatory domain. We tested the impact of IL-4 on both CD28ζ and 41BBζ costimulated CART19 cells. Similar to our previous studies with CART19-28ζ cells, chronic stimulation of CART19-BBζ cells in the presence of hrIL-4 enhanced the exhausted phenotype as seen by increased co-expression of inhibitory receptors (p = 0.04) and decreased production of IL-2 and IFN-γ (p = 0.08 and p = 0.007). Finally, we asked if IL-4 induces exhaustion independently of its classic role in Th2 polarization of CD4 CART cells. Following CART production, we isolated CD8 cells and chronically stimulated them in the presence of hrIL-4 or diluent. CD8 CART cells treated with hrIL-4 displayed an enhanced exhausted profile as seen by 1) decreased proliferative ability (p < 0.0001), 2) increased co-expression of inhibitory receptors (p = 0.01), and 3) decreased production of IL-2 and IFN-γ (p < 0.0001, p = 0.004). Together, our data indicates a novel role for IL-4 in the development of CART cell exhaustion that is independent of tumor cells, costimulatory domain, and CD4 cells. As such, we believe IL-4 neutralization may be a widely applicable and actionable approach to improve the durable response to CART cell therapy. Citation Format: Carli M. Stewart, Elizabeth L. Siegler, Truc N. Huynh, R. Leo Sakemura, Brooke Kimball, Long Mai, Kun Yun, James H. Girsch, Jennifer Feigin, Omar Gutierrez Ruiz, Makena Rodriguez, Ekene Ogbodo, Ismail Can, Claudia Manriquez Roman, Olivia Sirpilla, Hong Xia, Jenny Kim, Justin Budka, Mike Mattie, Nathalie Scholler, Simone Filosto, Saad S. Kenderian. IL-4 drives CART cell exhaustion in a CD4 independent manner [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 37.

Abstract 2836: Assessment of therapeutic antibody efficacy without the interference of murine Fc receptors allows for investigation of human antibody-dependent cellular cytotoxicity mediated by NK cells in the FcResolv™ hIL-15 NOG mouse model

Abstract Targeted antibody therapy is applied to treat various cancer types. In addition to the primary mode of action (MOA), which involves direct binding to the tumor antigen, indirect MOA acting through the constant region (Fc) of the antibody can enhance anti-tumor efficacy. Indirect mechanisms engage the innate immune system, mediated by both the complement system (complement-dependent cytotoxicity (CDC)) and immune cells (antibody-dependent cellular phagocytosis (ADCP) and antibody-dependent cellular cytotoxicity (ADCC)). These indirect mechanisms can complicate the evaluation and accurate assessment of antibody-induced ADCC by human NK cells in current mouse models. In immune-deficient mouse strains (e.g. NOG), false positives and/or negatives may occur due to interactions with murine Fc receptors. These can either result in anti-tumor responses via activation of the murine innate immune system or can interfere with the human-targeted therapy's primary MOA. To study the response to anti-cancer antibodies without the interference of these murine Fc receptor interactions and to investigate ADCC mediated by human NK cells, a novel mouse model deficient in Fc receptors and expressing human IL-15 (FcResolv™ hIL-15 NOG) was employed for testing antibody therapies. Methods: Patient-derived xenograft (PDX) tumor models were transplanted into hIL-15 NOG and FcResolv™ hIL-15 NOG mice. A human head and neck squamous cell carcinoma and a lung adenocarcinoma PDX model were both treated with cetuximab. Treatment with pertuzumab and trastuzumab was applied in a breast ductal carcinoma PDX model. Rituximab treatment was tested in two diffuse large B cell lymphoma PDX models. Based on growth kinetics, the lung cancer PDX model was chosen for further testing of ADCC in the NK cell-humanized FcResolv™ hIL-15 NOG mouse. Results and Conclusion: There was no difference in percent tumor growth inhibition between the FcResolv™ hIL-15 NOG and hIL-15 NOG mice with regards to cetuximab treatment in the lung and head and neck cancer or for trastuzumab treatment of breast ductal carcinoma. However, pertuzumab treatment revealed a false positive efficacy, with the false positive effect more pronounced in hIL-15 NOG mice than in FcResolv™ hIL-15 NOG mice. In one of the lymphoma models, a false negative result was observed. Here, rituximab did not show notable tumor inhibition in the hIL-15 NOG mice but did in the FcResolv™ hIL-15 NOG mice. These results demonstrate that FcResolv™ hIL-15 NOG mice serve as a suitable mouse model for a more accurate assessment of the therapeutic efficacy of anti-tumor antibodies. Additionally, evaluation of human-mediated ADCC of therapeutic antibodies in NK cell-humanized FcResolv™ hIL-15 NOG allows detection of effects specifically mediated by human NK cells. Citation Format: Simone Rhein, Maria Stecklum, Monika Buczek, Janell Richardson, Jens Hoffmann. Assessment of therapeutic antibody efficacy without the interference of murine Fc receptors allows for investigation of human antibody-dependent cellular cytotoxicity mediated by NK cells in the FcResolv™ hIL-15 NOG mouse model [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 2836.

Abstract 117: Improved PBMC humanized mouse models for immuno-oncology drugs evaluation

Abstract It has been demonstrated that anti-PD(L)1 therapy could significantly improve survival outcomes for patients with metastatic solid cancers, such as melanoma, non-small cell lung cancer and MSI-H colorectal cancer. However, more than half of these patients (NCT02563002, NCT02142738, NCT02563002) do not respond to immune checkpoint blockade (ICB) therapy, and 90% of colorectal cancer patients have MSS/pMMR characteristics and almost no response at all, which drives scientists to design novel drug candidates urgently and integrate tumor and tumor microenvironment (TME) signals systemically to rejuvenate exhausted immune system and overcome ICB resistance. LIDE has developed both traditional PBMC humanized mice model, and human immune cells and cancer co-inoculated model for IO drugs functional evaluation in the last 5-years by using unique PBMC donor selection and standard cancer biobank (PDX patient-derived xenografts, CDX cell derived xenograft) establishment. Cancer biopsies with MDM2 amplification or DNMT3A alternation have been shown resistant to PD1-Ab therapy but sensitive to chemical combo-therapy, and pMMR cancer PDX models seem responsible well to EGFR targeted, CD39-CD73-Adenosine targeted therapy. Human IL15 transgenic mice are used as one useful tool to investigate in vivo function of NK cells, NK engagers/modulators as well as drugs with ADCC (Antibody dependent cell-mediated cytotoxicity) effect. The activated immune cells and cancer co-transfer model, can significantly delay the graft-versus-host-reaction for another month compared with traditional PBMC humanized model, and archives maximal therapeutic effect of the testing drugs by pre-activating T cells with specific tumor antigens. Dendritic cells or macrophages could be successfully introduced into this co-inoculated system to work together with T cells, mimic human tumor tissue complexity, to help determine the overall effect induced by integrated signals. It seems CD40 agonist or CD47 antagonist could well synergies with anti-PD(L)1 to control melanoma and triple negative breast cancer development, respectively. This optimized PBMC humanized cancer-bearing mice models have been tested for various cancer targets, e.g. PD(L)1, Tim3, Lag3, Tigit, PVRIG, TGFβ1, CD73/CD39, CD47/Sirpa, DLL3/CD3, Claudin18.2/4-1BB, B7-H3, GITR, to better understand the interaction between cancer cells and immune cells. Citation Format: Bin Xie, Xin Hou, Pengfei Yang, Yanbing Zhou, Danyi Wen. Improved PBMC humanized mouse models for immuno-oncology drugs evaluation [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 117.

Abstract 1322: A cryopreserved allogeneic anti-BCMA CAR-NK cellular therapy exhibits both innate and CAR-mediated MM cell killing in vitro and in vivo

Abstract Introduction Multiple myeloma (MM) is the second most prevalent hematopoietic malignancy with an overall 5-year survival rate of 58%. B cell maturation antigen (BCMA) is selectively expressed on normal and malignant plasma cells, making it an attractive MM target. Anti-BCMA chimeric antigen receptor (CAR) T cell therapy and T cell engagers have shown promise as treatment options for certain MM patients; however, potential toxicities associated with these anti-BCMA therapies, such as cytokine release syndrome (CRS), have limited broader utilization. Much like T cells, natural killer (NK) cells are cytolytic and have demonstrated an innate capacity to reduce tumor burden while exhibiting a more favorable safety profile in clinical testing. To that end, we developed a cryopreserved allogeneic cell therapy comprised of genetically modified human umbilical cord blood-derived (CB) NK cells transduced with a gammaretroviral vector, which incorporates genes for an anti-BCMA CAR and soluble human interleukin-15 (sIL-15). Referred to hereafter as anti-BCMA CAR-NK, it exhibits both innate NK- and CAR-mediated killing in vitro and robust in vivo activity against established MM tumors. Methods CBNK cells were isolated from donor cord blood units, propagated using feeder cells, transduced with a gammaretroviral vector to express an anti-BCMA CAR and soluble human IL-15, and propagated further before harvest and cryopreservation. Donor-equivalent untransduced (UTD) NK cells were generated via the same process but without the transduction step. Cryopreserved anti-BCMA CAR-NK and UTD NK cells were used for in vitro studies, including short-term killing, as well as for evaluation of activity against established MM tumors in vivo using the MM.1S-Luc4 model. Results The anti-BCMA CAR was successfully expressed across all batches of anti-BCMA CAR-NK generated. Results from an in vitro cytotoxicity assay indicated that anti-BCMA CAR-NK kills BCMA expressing MM.1S-Luc4 tumor cells and secretes IFNγ, TNFα, and granzyme B at greater amounts compared to donor-equivalent UTD NK. Anti-BCMA CAR-NK and UTD NK cells also demonstrated equivalent cytotoxicity towards BCMA non-expressing cell lines, JJN3-Luc BCMA KO and NCI-H520, in an effector:target cancer cell dependent manner, highlighting the potential for treatment with anti-BCMA CAR-NK post-prior BCMA therapy. In in vivo studies, anti-BCMA CAR-NK exhibited robust anti-tumor activity in an MM.1S-Luc4 NSG mouse xenograft model, with no signs of anti-BCMA CAR-NK related body weight loss. Conclusion A cryopreserved allogeneic anti-BCMA CAR-NK cellular therapy exhibits both innate and CAR-mediated killing in vitro and robust in vivo activity in MM tumor models. Preclinical data supports future clinical evaluation in relapsed/refractory MM patients who have received prior BCMA therapy and IND enabling studies are ongoing. Citation Format: LeeAnn Talarico, Christina Wong, Chunyan Pang, Taylor Hickman, Chenqi Hu, Amy Shaw, Emily Wisniewski, Shao-Chiang (Michael) Lai, Pranjal Sharma, Shaun Moore, Luan Nguyen, Kayla Rhuda, Saurin Patel, Paul Lin, Rafet Basar, Shawn Cogan, Kat Sofjan, Arun Ramamurthy, Aaron Handler, Kathryn Fraser, Yana Wang, Katayoun Rezvani, Michael D. Curley. A cryopreserved allogeneic anti-BCMA CAR-NK cellular therapy exhibits both innate and CAR-mediated MM cell killing in vitro and in vivo [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 1322.

Abstract 6328: Preclinical development of CAR T cells with antigen-inducible IL-18 enforcement to treat GD2-positive solid cancers

Abstract Cytokine-engineering is a promising strategy to overcome limitations of CAR T cell therapy in solid tumors. We have developed a novel investigational medicinal product, consisting of CAR T cells directed against ganglioside GD2 along with CAR-inducible secretion of IL-18, to enforce their activation response and effector functions in the microenvironment of solid cancers. Our lentiviral all-in-one vector combines constitutive expression of a 14.G2a antibody-derived GD2-specific, 4-1BB-costimulated CAR with inducible nuclear factor of activated T cells (NFAT)-driven expression of the human IL-18 transgene. A control construct contains EGFP in the place of IL-18 (GD2EGFPCART). Lentiviral transduction of T cells from various individual donors with both preclinical and clinical batches of virus resulted in CAR surface expression in >40% of T cells. GD2IL18CART contained effector memory and central memory T cell phenotypes at similar frequencies as the control. CAR engagement by immobilized anti-idiotype antibody or by GD2-positive tumor cells selectively induced IL-18 release, with production of IL-18 strictly depending on GD2 antigen engagement. GD2IL18CART responded to interaction with GD2-positive tumor cells with superior IFN-γ, TNF-α and IL-2 cytokine release and superior target cytolysis compared to the control CAR T cells without inducible IL-18, whereas IL-6 was secreted at similar concentrations. In an NSG xenograft model of disseminated GD2-positive tumors, GD2IL18CART had superior in vivo anti-tumor activity than GD2EGFPCART, with eradication of GD2-positive tumor xenografts as detected by bioluminescence imaging while the control achieved only limited extension of progression-free survival. Finally, we established GMP-compliant manufacturing of GD2IL18CART that is feasible and efficient at clinical scale, using an automated protocol and device. Three validation runs confirmed robust expansion of CAR+ T cells to final cell numbers of 3.5x109 CAR+ cells (median; range 3.4 to 3.7x109), with consistent transduction efficiencies of >54% at the in-process control time-point and at harvest. GD2IL18CART from clinical-scale manufacturing runs responded to interaction with GD2 with strictly antigen-dependent secretion of both IL-18 and IFN-γ and efficiently lysed various GD2-positive tumor targets. In conclusion, we assembled all prerequisites for clinical evaluation of an IL-18 cytokine enhanced, GD2-specific CAR T cell product for the treatment of patients with a variety of solid tumors, recruited on the basis of GD2 immunofluorescence pre-screening (EU CT 2022-501725-21-00). Besides addressing the safety of GD2IL18CART therapy in pediatric and adult patients as the primary endpoint, the study will allow to gain substantial knowledge on the biological effects of IL-18 in the TME of the individual solid tumors. Citation Format: Lena Fischer-Riepe, Sareetha Kailayangiri, Katharina Zimmermann, Rita Pfeifer, Michael Aigner, Bianca Altvater, Sascha Kretschmann, Simon Voelkl, Jordan Hartley, Celine Dreger, Katja Petry, Andreas Bosio, Angelika von Doellen, Wolfgang Hartmann, Holger Lode, Dennis Goerlich, Andreas Mackensen, Melanie Jungblut, Axel Schambach, Hinrich Abken, Claudia Rossig. Preclinical development of CAR T cells with antigen-inducible IL-18 enforcement to treat GD2-positive solid cancers [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 6328.

Abstract 7260: An HSV-1-based vector for local delivery of IL-12 and IL-2 reshapes the immune landscape leading to tumor clearance and systemic immune surveillance

Abstract Clinical use of recombinant interleukin (IL)-12 and -2 therapy has been hindered due to unfavorable kinetics and toxicity associated with systemic exposure. Durable targeted delivery to the tumor microenvironment (TME) is a promising therapeutic strategy to overcome these clinical limitations, prompting the development of KB707, a replication-defective herpes simplex virus type 1 (HSV-1)-based vector encoding human IL-12 and -2, for the treatment of solid tumors. Prior studies in mice demonstrated that local vector-encoded cytokine administration enhanced murine IL-12/IL-2 expression while limiting systemic exposure compared to conventional protein therapy. In a syngeneic, B16-F10 melanoma mouse model, intratumoral murine KB707-equivalent treatment led to improved survival in a unilateral tumor model and an abscopal effect in a bilateral tumor model. Additionally, the majority of previously treated animals survived rechallenge with B16-F10 in the absence of further therapy, indicative of systemic anti-tumor immune memory. Together, these results suggested that vector-mediated delivery of IL-12 and -2 could elicit both local and systemic anti-tumor immune responses. To elucidate the underlying changes to the immune landscape, B16-F10 tumor-bearing animals were treated intratumorally with vector or vehicle control on day 0 and were sacrificed on day 7; a second cohort of tumor-bearing animals received two vector doses (days 0 and 7) and were sacrificed on days 8, 10, 12, or 14. Immune cell profiling of samples taken from the tumor, tumor draining lymph node (dLN), spleen, and whole blood were analyzed by flow cytometry, and serum cytokine analysis was conducted by multiplex ELISA. Flow cytometric analysis of tumors revealed that vector treatment resulted in increased frequencies of proliferating and activated effector CD8+ and CD4+ T cells, peaking 24 hours post-second dose. These results correlated with high levels of the proinflammatory cytokines IFNγ and TNFα in the serum of vector recipient animals. The blood, spleens, and dLNs also showed increased frequencies of activated effector CD8+ and CD4+ T cells, peaking 24-72 hours post-second dose. Interestingly, although IL-2 alone has been shown to promote immune suppression and tumor outgrowth by mediating regulatory T cell (Treg) expansion and infiltration in certain contexts, the frequency of Tregs in treated vs. control tumors was substantially reduced after first and repeat dosing. Together, these results support a mechanism by which vector-driven local expression of IL-12 and IL-2 can expand and activate effector T cells both in the TME and systemically while simultaneously repressing Tregs, consistent with the previously described inhibition of primary tumor outgrowth, abscopal effects on secondary tumors, and prevention of recurrence observed with this therapeutic approach. Citation Format: Dana M. Previte, Trevor J. Parry, Suma M. Krishnan. An HSV-1-based vector for local delivery of IL-12 and IL-2 reshapes the immune landscape leading to tumor clearance and systemic immune surveillance [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 7260.

Abstract 7181: Low dose interleukin-6 (SON-080) for neuropathies: Toxicology and clinical plans

Abstract Neuropathies are conditions in which peripheral nerves degenerate, resulting in sensory and motor symptoms that can profoundly affect the patients’ quality of life. Chemotherapy-induced peripheral neuropathy (CIPN) is induced by most antineoplastic agents, affecting cancer patients during or following completion of treatment. Neuropathy-specific pain medication is most often inefficient against pain, can cause major side effects that limit their use, do not address non-pain related symptoms, and do not stop CIPN progression. Most evidence suggests that physical exercise is the most efficient approach to reduce neuropathy symptoms and potentially, progression. Other publications have causally linked exercise, through the ability of contracting muscles to release low levels of interleukin-6 into the bloodstream thereby activating several metabolic and physiological pathways that help regenerate muscle and nerve tissue, affect glucose homeostasis, increase lipolysis, improve microvascular blood flow and reduce inflammation. Preclinical disease models of CIPN and diabetic peripheral neuropathy (DPN) have confirmed that IL-6 administered at low doses is capable of stimulating peripheral nerve growth, thereby ameliorating motor and sensory functions and normalizing the associated pain or sensation disturbance of neuropathy. The maximum tolerated (MTD) dose of recombinant human IL-6 (rhIL-6) has been established as a treatment for thrombocytopenia in hundreds of cancer patients using the drug product that was produced in the 1990’s (Process A) dosed intravenously (IV) or subcutaneously (SC). We have developed a cGMP compliant version of rhIL-6 (SON-080) using a state-of-the-art process (Process B) that meets current regulatory guidelines for cell lines and processes. An analytical comparison of SON-080 with Process A rhIL-6 concluded that both drugs are highly comparable for at least 14 different key physicochemical characteristics. Therefore, we expect similar in vivo behavior with Process B material as compared with the Process A molecule. In order to support clinical plans for the safety and toxicity of rhIL-6, a dose range and schedule of administration that matches the current clinical protocol was performed in a cynomolgus monkey primate toxicology model. Under these conditions, SON-080 was found safe and well tolerated with a No Adverse Effect Levels (NOAEL) of 30µg/kg, the highest dose tested. On this basis, a fully controlled Phase 1b/2a clinical study, SB211, is ongoing to evaluate safety, tolerability, and efficacy of subcutaneous SON-080 dosage and administration schedule that targets an exposure mirroring the endogenous release levels elicited by moderate to heavy exercise. Confirmation of safety in the first portion of the trial will pave the way for efficacy evaluation with the objective to provide CIPN patients with a novel, safe, and effective treatment for painful neuropathies. Citation Format: Susan Dexter, Gael Hedou, Richard T. Kenney, Darrel J. Rezac, Pankaj Mohan. Low dose interleukin-6 (SON-080) for neuropathies: Toxicology and clinical plans [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 7181.

Multiply restimulated human cord blood-derived Tregs maintain stabilized phenotype and suppressive function and predict their therapeutic effects on autoimmune diabetes

BackgroundRegulatory T cells (Tregs) are involved in the maintenance of immune homeostasis and immune regulation. Clinical trials on the adoptive transfer of Tregs have been ongoing for > 10 years. However, many unresolved issues remain in the production of readymade Treg products and selection of patients. Hence, this study aimed to develop a method to expand off-the-shelf Tregs derived from umbilical cord blood (UCB-Tregs) in vitro without changing their phenotype and inhibitory function. In addition, the study intended to design an approach to precisely select patients who are more likely to benefit from the adoptive Treg transfer therapy.MethodsUCB-Tregs were isolated and cultured in a medium containing human recombinant IL-2 and rapamycin and then multiply restimulated with human T-activator CD3/CD28 dynabeads. The phenotype and suppressive capacity of Tregs were assessed on days 18 and 42. The relationship between the suppressive function of UCB-Tregs in vitro and clinical indicators was analyzed, and the ability of the in vitro suppressive capacity to predict the in vivo therapeutic effects was evaluated.ResultsUCB-Tregs expanded 123-fold and 5,981-fold at 18 and 42 days, respectively. The suppressive function of UCB-Tregs on the proliferation of immune cells at 42 days was not significantly different compared with that of UCB-Tregs obtained at 18 days. The suppression rate of UCB-Tregs to PBMCs was negatively correlated with the course of diabetes. Moreover, the high-suppression group exhibited a better treatment response than the low-suppression group during the 12-month follow-up period.ConclusionsMultiply restimulated UCB-Tregs expanded at a large scale without any alterations in their classical phenotypic features and inhibitory functions. The suppressive function of Tregs in vitro was negatively correlated with the disease duration. The present study revealed the possibility of predicting the in vivo therapeutic effects via the in vitro inhibition assay. Thus, these findings provided a method to obtain off-the-shelf Treg products and facilitated the selection of patients who are likely to respond to the treatment, thereby moving toward the goal of precision treatment.

Murine alveolar macrophages rapidly accumulate intranasally administered SARS-CoV-2 Spike protein leading to neutrophil recruitment and damage

The trimeric SARS-CoV-2 Spike protein mediates viral attachment facilitating cell entry. Most COVID-19 vaccines direct mammalian cells to express the Spike protein or deliver it directly via inoculation to engender a protective immune response. The trafficking and cellular tropism of the Spike protein in vivo and its impact on immune cells remains incompletely elucidated. In this study, we inoculated mice intranasally, intravenously, and subcutaneously with fluorescently labeled recombinant SARS-CoV-2 Spike protein. Using flow cytometry and imaging techniques, we analyzed its localization, immune cell tropism, and acute functional impact. Intranasal administration led to rapid lung alveolar macrophage uptake, pulmonary vascular leakage, and neutrophil recruitment and damage. When injected near the inguinal lymph node medullary, but not subcapsular macrophages, captured the protein, while scrotal injection recruited and fragmented neutrophils. Widespread endothelial and liver Kupffer cell uptake followed intravenous administration. Human peripheral blood cells B cells, neutrophils, monocytes, and myeloid dendritic cells all efficiently bound Spike protein. Exposure to the Spike protein enhanced neutrophil NETosis and augmented human macrophage TNF-α (tumor necrosis factor-α) and IL-6 production. Human and murine immune cells employed C-type lectin receptors and Siglecs to help capture the Spike protein. This study highlights the potential toxicity of the SARS-CoV-2 Spike protein for mammalian cells and illustrates the central role for alveolar macrophage in pathogenic protein uptake.

Murine alveolar macrophages rapidly accumulate intranasally administered SARS-CoV-2 Spike protein leading to neutrophil recruitment and damage.

The trimeric SARS-CoV-2 Spike protein mediates viral attachment facilitating cell entry. Most COVID-19 vaccines direct mammalian cells to express the Spike protein or deliver it directly via inoculation to engender a protective immune response. The trafficking and cellular tropism of the Spike protein in vivo and its impact on immune cells remains incompletely elucidated. In this study, we inoculated mice intranasally, intravenously, and subcutaneously with fluorescently labeled recombinant SARS-CoV-2 Spike protein. Using flow cytometry and imaging techniques, we analyzed its localization, immune cell tropism, and acute functional impact. Intranasal administration led to rapid lung alveolar macrophage uptake, pulmonary vascular leakage, and neutrophil recruitment and damage. When injected near the inguinal lymph node medullary, but not subcapsular macrophages, captured the protein, while scrotal injection recruited and fragmented neutrophils. Widespread endothelial and liver Kupffer cell uptake followed intravenous administration. Human peripheral blood cells B cells, neutrophils, monocytes, and myeloid dendritic cells all efficiently bound Spike protein. Exposure to the Spike protein enhanced neutrophil NETosis and augmented human macrophage TNF-α (tumor necrosis factor-α) and IL-6 production. Human and murine immune cells employed C-type lectin receptors and Siglecs to help capture the Spike protein. This study highlights the potential toxicity of the SARS-CoV-2 Spike protein for mammalian cells and illustrates the central role for alveolar macrophage in pathogenic protein uptake.

Determination of in vitro immunotoxic potencies of a series of perfluoralkylsubstances (PFASs) in human Namalwa B lymphocyte and human Jurkat T lymphocyte cells.

Exposure to PFASs is associated to several adverse health effects, such as immunotoxicity. Immunotoxic effects of PFOA and PFOS, including a reduced antibody response in both experimental animals and humans, have been reported. However, there is limited understanding of the underlying mechanisms involved. Moreover, there is only a restricted amount of immunotoxicity data available for a limited number of PFASs. In the current study the effects of 15 PFASs, including short- and long-chain perfluorinated carboxylic and sulfonic acids, fluorotelomer alcohols, and perfluoralkyl ether carboxylic acids were studied on the expression of recombinant activating gene 1 (RAG1) and RAG2 in the Namalwa human B lymphoma cell line, and on the human IL-2 promotor activity in Jurkat T-cells. Concentration-response data were subsequently used to derive in vitro relative potencies through benchmark dose analysis. In vitro relative potency factors (RPFs) were obtained for 6 and 9 PFASs based on their effect on RAG1 and RAG2 gene expression in Namalwa B-cells, respectively, and for 10 PFASs based on their inhibitory effect on IL-2 promotor activity in Jurkat T-cells. The most potent substances were HFPO-TA for the reduction of RAG1 and RAG2 gene expression in Namalwa cells (RPFs of 2.1 and 2.3 respectively), and PFDA on IL-2 promoter activity (RPF of 9.1). RAG1 and RAG2 play a crucial role in V (D)J gene recombination, a process for acquiring a varied array of antibodies crucial for antigen recognition. Hence, the effects observed in Namalwa cells might indicate a PFAS-induced impairment of generating a diverse range of B-cells essential for antigen recognition. The observed outcomes in the Jurkat T-cells suggest a possible PFAS-induced reduction of T-cell activation, which may contribute to a decline in the T-cell dependent antibody response. Altogether, the present study provides potential mechanistic insights into the reported PFAS-induced decreased antibody response. Additionally, the presented in vitro models may represent useful tools for assessing the immunotoxic potential of PFASs and prioritization for further risk assessment.

Carvacrol prophylaxis improves clinical outcome and dampens apoptotic and pro-inflammatory immune responses upon Campylobacter jejuni infection of human microbiota-associated IL-10-/- mice.

Incidence rates of human Campylobacter jejuni infections are progressively increasing globally. Since the risk for the development of post-infectious autoimmune diseases correlates with the severity of the preceding enteritis and campylobacteriosis treatment usually involves symptomatic measures, it is desirable to apply antibiotic-independent compounds to treat or even prevent disease. Given its health-promoting including anti-inflammatory properties carvacrol constitutes a promising candidate. Thisprompted us to test the disease-alleviating including immune-modulatory effects of carvacrolprophylaxis in acute murine campylobacteriosis. Therefore, human gut microbiota-associated IL-10-/- mice were orally challenged with synthetic carvacrol starting a week before C. jejuni infection and followed up until day 6 post-infection. Whereas carvacrol prophylaxis did neither affect gastrointestinal pathogen loads, nor the human commensal gut microbiota composition, it improved the clinical outcome of mice, attenuated colonic epithelial cell apoptosis, and dampened pro-inflammatory immune responses not only in the intestinal tract but also in extra-intestinal organs including the liver and the spleen. In conclusion, our preclinical placebo-controlled intervention study provides convincing evidence that oral carvacrol pretreatment constitutes a promising option to mitigate acute campylobacteriosis and in turn, to reduce the risk for post-infectious complications.