NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ Research Articles

Examining Intercage Transmission of Chlamydia muridarum: Impact of Barrier Husbandry and Cage Sanitization.

Chlamydia muridarum (Cm) has reemerged as a prevalent bacterial contaminant of academic research mouse colonies. A study was conducted to assess the effectiveness of husbandry and cage sanitization methods in preventing intercage transmission of Cm. To assess intercage transmission during cage change, a cage housing 2 Cm-free Swiss Webster (SW; Tac:SW) sentinel mice was placed randomly on each of 12 individually ventilated cage racks, housing cages with Cm-shedding mice, located in one of 2 animal holding rooms. Husbandry staff blinded to the study cages changed all cages in the animal holding rooms weekly using a microisolation cage technique. PCR testing performed at 180 d postplacement confirmed all mice remained negative for Cm. To assess the effectiveness of cage sanitization to eliminate Cm, we investigated transmission of Cm to a naive Cm-free SW and NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mouse cohoused for 7 d (repeated weekly for 4 wk) in cages assigned to one of 3 groups (n = 10 pairs of mice/group). Cages that previously housed 2 Cm-shedding BALB/c mice were either washed in a tunnel washer (82.2 °C [180 °F] final rinse for an average of 16 s per run; n = 10) with and without postwashing autoclaving (121 °C for 20 min; n = 10), or were untreated (bedding change only; n = 10). Pre- and postsanitization swabs of each cage were assayed for Cm by PCR. All pretreatment swabs tested positive, while posttreatment swabs from all cages (excluding bedding change) tested negative. All SW and NSG mice, irrespective of group, remained negative for Cm as determined by PCR. These findings suggest that infectious Cm does not persist in untreated cages or after mechanical washing with and without autoclaving. Collectively, these findings suggest that neither our husbandry protocols nor inadequate cage sanitization methods likely contributed to the observed prevalence of Cm in contemporary research mouse colonies.

Novel Antimitotic Agent SP-1-39 Inhibits Head and Neck Squamous Cell Carcinoma

Effective management of head and neck cancer (HNC) poses a significant challenge in the field of oncology, due to its intricate pathophysiology and limited treatment options. The most common HNC malignancy is head and neck squamous cell carcinoma (HNSCC). HNSCC treatment includes a combination of surgery, radiation, and chemotherapy. While HNSCC is treatable if diagnosed early, this is often not the case and is considered incurable once in its late stages and metastatic disease has developed. Therapies are also limited once resistant disease has occurred. SP-1-39, a novel colchicine-binding site inhibitor (CBSI), has been recently reported for its potential efficacy in a variety of cancer cell lines including breast, melanoma, pancreatic, and prostate. SP-1-39 also shows abilities to overcome paclitaxel resistance in a paclitaxel-resistant prostate cancer xenograft model. To evaluate the potential of SP-1-39 as a new HNSCC treatment option, herein we systematically performed preclinical studies in HNSCC models using SP-1-39 and demonstrated that, in vitro, SP-1-39 inhibits the proliferation of 2 HNSCC cell lines with low nanomolar IC50 values (1.4 to 2.1 nM), induces HNSCC cell apoptosis in a dose-dependent manner, interferes with migration of HNSCC cells, and leads to HNSCC cell cycle arrest in the G2/M phase. In vivo, SP-1-39 suppresses the primary tumor growth of a Detroit 562 subcutaneous xenograft mouse model in 6- to 8-wk-old, male NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) mice, with no detectable cytotoxic effects at a low dose of 2.5 mg/kg. This efficacy of SP-1-39 is better when compared with the treatment using a reference chemotherapy drug, paclitaxel at 10 mg/kg. Collectively, these data demonstrate that SP-1-39 is a promising candidate for further development for more efficacious HNSCC treatment.

Abstract 4571: Combination of FOLFIRI (5-FU, Leucovorin, and Irinotecan) and ProAgio on colon cancer growth and metastasis

Abstract Background/Objective: One of the common mechanisms of resistance of solid tumors, including colon cancers, is activation of integrins on endothelial cells (ECs) and cancer-associated fibroblasts (CAFs). ProAgio is a small molecule developed to target integrin alpha V beta 3 (αvβ3), located on surface of abnormal ECs and CAFs. ProAgio enhances apoptosis and inhibits angiogenesis via targeting αvβ3. The aim of the current study is to evaluate the ProAgio combination with FOLFIRI on the immune profile and tumor growth of colon cancer. Material and Methods: Female BALB/CJ and male NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) mice were acquired from the Jackson Laboratory, and experiments were performed under the approval of The University of Alabama at Birmingham-Institutional Animal Care and Use Committee. For orthotropic tumor efficacy studies, BALB/CJ mice were injected with 2×105 CT-26 wild type and CT26.CL25 cells in 30ul 1:1 Matrigel Matrix and PBS into the Cecum. PDX (10mg) was orthotopically implanted into the NSG mice cecum. At Day five, mice were divided into four treatment groups: including 1) sterile water (vehicle), 2) ProAgio (15mg/kg; IP; once daily for nine days), 3) FOLFIRI (5-FU: 30mg/kg; Leucovorin 50mg/kg; Irinotecan; 20mg/kg - once every three days intraperitoneal) or 4) combination of ProAgio and FOLFIRI. The study completed on day 15, tumor weight was noted, and tumors were processed for histology and flow cytometry. Results: ProAgio plus FOLFIRI significantly (p<0.001) reduced tumor weight in both models compared to individual treatments and vehicles. Combination-treated mice showed a significant (p<0.001) reduction in T-cell exhaustion (CD8+ T cells that are positive for PD-1, TIM-3, and CTLA-4). Analysis of the myeloid compartment showed a significant (p<0.001) increase in the M1 macrophages that express F4/80 as well as CD86, MHC-II and a decrease in the M2 macrophage in the mice treated with ProAgio plus FOLFIRI. The combination therapy exhibited a significant (p<0.001) increase in the dendritic cell infiltration into the tumor microenvironment. Histology analysis showed that ProAgio treatment reduced the incidence of organ site metastasis (disseminated and locoregional spread) such as liver, pancreas, and diaphragm. Conclusion: Our study offers encouraging observations that ProAgio plus FOLFIRI can suppress colon cancer growth and metastasis by inhibiting αvβ3 preclinically and may provide a novel therapeutic combination for the management of colon cancers. Citation Format: Purnachandra Nagaraju Ganji, Jeremy B. Foote, Madhu Sudhana Saddala, Falguni Mishra, Sujith Sarvesh, Midhun Malla, Ashiq Masood, Zhi-Ren Liu, Bassel F. El-Rayes. Combination of FOLFIRI (5-FU, Leucovorin, and Irinotecan) and ProAgio on colon cancer growth and metastasis [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 4571.

Abstract 4002: Investigating CAR-T cell efficacy and activation in the disseminated NALM6-luc human B-cell acute lymphoblastic leukemia model

Abstract Introduction: Chimeric Antigen Receptor T (CAR-T) cell therapy has emerged as a promising approach for treating hematological malignancies, particularly B-cell acute lymphoblastic leukemia (B-ALL). This study aimed to delve into the activation dynamics and therapeutic efficacy of CD19 CAR-T cells in a disseminated NALM6-luc human B-ALL murine model. Experimental design: NALM6-Luc-mCh-Puro cells were implanted intravenously in female NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) mice. Animals were treated with CD19 CAR-T cells alone and in combination with ibrutinib. The anti-tumor activity was assessed, and the persistence and activation of CAR-T cells in the blood were evaluated using flow cytometry. Additionally, ddPCR analysis was employed to quantify CAR copy numbers, providing insights into the T-cell persistence over time. Results: Treatment with CD19 CAR-T cells exhibited notable anti-cancer activity and that activity was enhanced in combination with ibrutinib, in line with other reports. The increased time to progression was noted as 69.2% for the CAR-T group and 138.4% for the combination of CAR-T and ibrutinib compared to control. Flow cytometry analysis showed that CAR-T cells persisted in the blood throughout the study. The mean CAR-T absolute cell count for both CAR-T and CAR-T plus ibrutinib treated groups increased from 2 cell/µL blood on Day 0 to 11 and 51 cells/µL of blood, respectively, by Day 39. The progressive increase of PD-1+ and LAG-3+ percentage cells correlates positively with tumor burden, indicating a dynamic link between biomarker upregulation and the presence of tumor cells in mice. ddPCR analysis revealed an initial CAR copy decrease in all groups, followed by gradual increase in tumor-bearing mice treated with CD19 CAR-T cells, with a dramatic increase observed by Day 39. Results from CAR-T treated and CAR-T plus ibrutinib treated groups were comparable, showing mean copy numbers per ng of DNA increasing from less than 1 on day 4 to 17.9 and 23.3, respectively, on day 39. Importantly, no changes were noted in non-tumor implanted mice, emphasizing the tumor dependency for CAR-T cell expansion. Conclusion: This study emphasizes the marked anti-cancer activity of CD19 CAR-T cells in the NALM6-Luc-mCh-Puro B-ALL murine model. Comprehensive analysis of CAR-T cell persistence and activation, including insights from ddPCR, provides a robust understanding of therapeutic response dynamics. The observed in vivo anti-cancer efficacy aligns with the persistence of CAR-T cells revealed by flow cytometry and the dynamic expansion captured through ddPCR analysis. Our results indicate ddPCR and flow cytometry as complementary and independent methods for assessing the systemic CAR-T cell persistence, contributing to optimizing therapy for B-cell acute lymphoblastic leukemia. Citation Format: Prashant Pandey, David Draper, Sheri Barnes, Yewei Xing, Derrik Germain, Lauren Kucharczyk, Roys Stacey. Investigating CAR-T cell efficacy and activation in the disseminated NALM6-luc human B-cell acute lymphoblastic leukemia 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 4002.

Epizootic of enterocolitis and clostridial overgrowth in NSG and NSG-related mouse strains.

While the immunodeficient status of NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) and NSG-related mice provides utility for numerous research models, it also results in increased susceptibility to opportunistic pathogens. Over a 9-week period, a high rate of mortality was reported in a housing room of NSG and NSG-related mice. Diagnostics were performed to determine the underlying etiopathogenesis. Mice submitted for evaluation included those found deceased (n = 2), cage mates of deceased mice with or without diarrhea (n = 17), and moribund mice (n = 8). Grossly, mice exhibited small intestinal and cecal dilation with abundant gas and/or digesta (n = 18), serosal hemorrhage and congestion (n = 6), or were grossly normal (n = 3). Histologically, there was erosive to ulcerative enterocolitis (n = 7) of the distal small and large intestine or widespread individual epithelial cell death with luminal sloughing (n = 13) and varying degrees of submucosal edema and mucosal hyperplasia. Cecal dysbiosis, a reduction in typical filamentous bacteria coupled with overgrowth of bacterial rods, was identified in 18 of 24 (75%) mice. Clostridium spp. and Paeniclostridium sordellii were identified in 13 of 23 (57%) and 7 of 23 (30%) mice, respectively. Clostridium perfringens (7 of 23, 30%) was isolated most frequently. Toxinotyping of C. perfringens positive mice (n = 2) identified C. perfringens type A. Luminal immunoreactivity to several clostridial species was identified within lesioned small intestine by immunohistochemistry. Clinicopathologic findings were thus associated with overgrowth of various clostridial species, though direct causality could not be ascribed. A diet shift preceding the mortality event may have contributed to loss of intestinal homeostasis.

Antibiotic Treatment of Corynebacterium bovis-associated Clinical Disease in NSG Mice.

Depending on the strain of immunodeficient mice, Corynebacterium bovis infection can be asymptomatic or cause transient or prolonged skin disease. C. bovis infection of NOD. Cg- Prkdcscid Il2rgtm1Wjl /SzJ (NSG) mice results in clinical skin disease that progresses in severity. Amoxicillin metaphylaxic and prophylaxic therapy prevents transmission and infection of mice after exposure to C. bovis and inhibits the growth of C. bovis isolates at therapeutic doses that are clinically achievable in mice. Amoxicillin is not efficacious for treatment of transient clinical skin disease in athymic nude mice, but the efficacy of amoxicillin treatment has not previously been characterized in C. bovis -infected NSG mice. In the current study, NSG mice were treated with amoxicillin beginning at 5 wk after exposure to C. bovis, at which time they had well-established clinical signs of disease. Clinical signs were scored to assess disease progression, regression, and reappearance. Our results showed that amoxicillin treatment for 3 or 6 wk reduced the clinical scores of NSG mice with C. bovis -associated clinical disease. In addition, withdrawal of treatment led to the recurrence of clinical signs. Collectively, our data suggest that amoxicillin treatment is effective in alleviating the clinical signs associated with C. bovis infection for the duration of treatment in NSG mice. Clinical intervention with antibiotics for C. bovis -infected NSG mice can be an option for management of C. bovis -related clinical disease either before or during facility-wide remediation efforts.

A Novel Fc-Optimized Antibody Drug Conjugate Targeting CD7 As a Therapeutic Strategy in T-Cell Acute Lymphoblastic Leukemia

Despite progress in improving treatment regimens for patients with T-cell acute lymphoblastic leukemia (T-ALL), the therapeutic options are still limited, and especially antibody-based immunotherapy is not established. The CD7 antigen represents a promising target structure in T-ALL since it is strongly expressed in different T-ALL subtypes including early T-cell precursor (ETP)-ALL. Therefore, different approaches are currently pursued for targeting CD7, including CAR-T cell therapy. Due to its high internalization capacity CD7 also represents an ideal target structure for antibody drug conjugates (ADC). Here, a novel antibody engineering approach for CD7-targeting was evaluated in vitro and in xenograft mouse models of T-ALL. A CD7 antibody was optimized for its ability to trigger antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) by introducing two amino acid substitutions (S239D/I332E; DE-variant) in the Fc-domain. In addition, the Fc-engineered antibody was conjugated to the microtubule-disrupting agent monomethyl auristatin E (MMAE) via an enzymatic-cleavable linker (mc-vc-PABC). The Fc-optimized ADC, CD7-DE-vcMMAE, as well as the unconjugated antibody, CD7-DE, showed improved binding to activating Fcγ receptors (FcγRIIa, FcγRIIIa) compared to a CD7 antibody lacking the DE-modification. This resulted in potent ADCC- and ADCP-activity against different T-ALL cell lines mediated by NK-cells or macrophages as effector cells (EC 50 ADCC, 1-7 pM). In contrast to the CD7-DE antibody, CD7-DE-vcMMAE showed strong cytotoxic effects independently of immune effector cell engagement by releasing its cytotoxic compound into T-ALL cells in an antigen-restricted manner, thereby inducing G2/M cell cycle arrest and apoptosis. CD7-DE-vcMMAE was active at subnanomolar concentrations demonstrating dose-dependent cytotoxic effects in six T-ALL cell lines (IC 50 0.2 - 1 nM). The extent of maximum growth inhibition ranged between 54-98 % and correlated with CD7 antigen density. Yet, although CD7-DE-vcMMAE did not kill CD7-negative cells directly, the linker design facilitated bystander killing activity. Thus, in co-culture experiments using CEM cells and CEM-CD7-knockout cells mimicking CD7-antigen escape, the ADC demonstrated significant killing of neighbouring CD7-negative cells, thereby extending its mode of action. The antitumor activity of the CD7-ADC was further investigated in xenograft mouse models of T-ALL. In a first model, CEM cells were injected subcutaneously into NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice and CD7-DE-vcMMAE treatment was evaluated in comparison to the unconjugated antibody CD7-DE. Treatment with CD7-DE-vcMMAE led to a significantly reduced tumor growth in comparison to CD7-DE or untreated animals (p<0.05; see panel A). A preclinical phase II-like patient-derived xenograft (PDX) study employing eight randomly selected T-ALL-PDX samples from pediatric and adult patients was conducted. PDX-cells were injected intravenously into NSG mice and treatment was started when the leukemia load reached 1 % human blasts in the peripheral blood, reflecting an overt leukemia situation. Animals receiving therapy with CD7-DE-vcMMAE showed significant prolongation of median survival in comparison to animals treated with a similarly designed control ADC targeting an irrelevant antigen (control-DE-vcMMAE) or which were left untreated (median survival time; CD7-DE-vc-MMAE: 82 days; untreated/control-DE-vcMMAE: 60 days; p<0.05; see panel B). Importantly, no leukemic blasts were found in the peripheral blood, spleen or bone marrow in animals treated with CD7-DE-vcMMAE and surviving the experimental period of 150 days. Together, the novel ADC CD7-DE-vcMMAE showed a unique set of Fc effector functions, potent direct growth inhibitory effects, bystander killing activity and efficacy in xenograft models of T-ALL. These results exhibit CD7-DE-vcMMAE as a promising therapeutic strategy and form the basis for new approaches in the treatment of T-ALL.

Human circulating CD24hi marginal zone B cells produce IgM targeting atherogenic antigens and confer protection from vascular disease.

IgMs that inactivate oxidation-specific epitopes (IgMOSE), which are secondary products of lipid peroxidization, protect against inflammatory diseases, including diet-induced atherosclerosis. However, the human B cell subtype that produces IgMOSE remains unknown. In this study, we used single-cell mass cytometry and adoptive transfer of B cell subtypes to NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice to identify B27+IgM+CD24hi cells as the major producers of IgMOSE in humans. Notably, these cells have characteristics of human circulatory marginal zone B (MZB) cells, which are known to be atheoroprotective IgM producers in mice. CD24 antibody treatment to reduce MZB cells and IgM in a hyperlipidemic humanized mouse model provides the evidence that MZB cells protect against vascular inflammation. Consistent with these findings, the frequency of B27+IgM+CD24hi cells (MZB) in patients inversely correlates with coronary artery disease severity.

A Microwell Device for the Efficient Generation of Arrays of Microtissues and Humanized Bone Marrow Micro-Ossicles

(1) Background: There are no high-throughput microtissue platforms for generating bone marrow micro-ossicles. Herein, we describe a method for the assembly of arrays of microtissues from bone marrow stromal cells (BMSC) in vitro and their maturation into bone marrow micro-ossicles in vivo. (2) Methods: Discs with arrays of 50 microwells were used to assemble microtissues from 3 × 105 BMSCs each on a nylon mesh carrier. Microtissues were cultured in chondrogenic induction medium followed by hypertrophic medium in an attempt to drive endochondral ossification, and then they were implanted in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice, where they were remodeled into bone marrow micro-ossicles. Mice were transplanted with 105 human umbilical cord blood CD34+ cells. (3) Results: Micro-ossicles contained more human CD45+ cells, but fewer human CD34+ progenitor cells than mouse marrow. Human hematopoietic progenitor cells cycle rapidly at non-physiological rates in mouse marrow, and reduced CD34+ cell content in micro-ossicles is consistent with the notion that the humanized niche better controls progenitor cell cycling. (4) Conclusions: Assembling microtissues in microwells, linked by a nylon membrane carrier, provides an elegant method to manufacture and handle arrays of microtissues with bone organ-like properties. More generally, this approach and platform could aid bridging the gap between in vitro microtissue manipulation and in vivo microtissue implantation.

Abstract 41: Subcutaneous growth and immune cell profiling of BT-474 human breast carcinoma in four strains of triple immunodeficient mice

Abstract Triple immunodeficient mouse models, that lack functional T cells, B cells, and natural killer cells, are necessary when evaluating human cancer cell growth and cell-based therapy activity, allowing for assessment without innate mouse immune system involvement. Due to limited colony sizes at any given vendor, study timelines can sometimes become compromised unless a sufficient alternative is validated. Site location can also be a factor, as licensing restrictions may be an issue for international corporations. In an effort to prove overall similarities across four strains of triple immunodeficient mice, the growth characteristics of BT-474 were compared in female NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice, NOD.CB17-Prkdcscid IL2rgtm1/BcgenHsd (B-NDG) mice, NOD-Prkdcem26Cd52Il2rgem26Cd22/NjuCrl (NCG) mice, and NOD.Cg-Prkdcscid Il2rgtm1Sug/JicTac (CIEA NOG) mice. An immune cell profile was also performed across these four mouse strains and evaluated via flow cytometry to observe any immune cell subset differences in blood, spleen, and tumor samples. Samples analyzed post implant were collected when subcutaneous tumors were ~500 mm3. Model development studies were completed previously to optimize tumor growth kinetics. Historic growth conditions were BT-474 cells implanted at 1.0E+07 cells/implant in the presence of an extracellular matrix into the high right axilla of female NSG mice. Using the same optimized growth conditions, NSG, B-NDG, NCG, and CIEA NOG mice were implanted with BT-474 cells. BT-474 grew well in all the tested mouse strains, producing 100% take rate. Compared to NSG mice, median tumor volume doubling times differed by 1-5 days, median times to an evaluation size of 150 mm3 (typical study enrollment tumor volume) differed by +/- ~4 days and median time to an evaluation size of 1250 mm3 (tumor volume at the end of life) differed by +/- ~10 days. BT-474 did not induce body weight loss in any of the tested mouse strains and all clinical observations were similar. Flow cytometry was performed to quantify lymphocyte and myeloid immune subsets in blood, spleen, and tumor. Overall, compared to NSG mice, the absolute counts were similar for all immune subsets measured except for regulatory T cells (Tregs). B-NDG, NCG, and CIEA NOG mice had reduced Treg numbers in the spleen of tumor-bearing mice. In the tumor, Treg numbers were lower in the B-NDG and CIEA NOG mice. No differences were observed for any immune subset in the blood. Overall, the tumor growth kinetics of BT-474 in B-NDG mice was most similar to historical data using NSG mice. The flow data also confirmed that each strain’s immune cell population generally looked very similar, with limited differences between the four strains of triple immunodeficient mice. Citation Format: Justin Snider, Derrik Germain, Lauren Kucharczyk, Anita Zaitouna, Erin Trachet, Scott Wise. Subcutaneous growth and immune cell profiling of BT-474 human breast carcinoma in four strains of triple immunodeficient mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 41.

Human Hematopoietic Stem Cell Engrafted IL-15 Transgenic NSG Mice Support Robust NK Cell Responses and Sustained HIV-1 Infection.

Mice reconstituted with human immune systems are instrumental in the investigation of HIV-1 pathogenesis and therapeutics. Natural killer (NK) cells have long been recognized as a key mediator of innate anti-HIV responses. However, established humanized mouse models do not support robust human NK cell development from engrafted human hematopoietic stem cells (HSCs). A major obstacle to human NK cell reconstitution is the lack of human interleukin-15 (IL-15) signaling, as murine IL-15 is a poor stimulator of the human IL-15 receptor. Here, we demonstrate that immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice expressing a transgene encoding human IL-15 (NSG-Tg(IL-15)) have physiological levels of human IL-15 and support long-term engraftment of human NK cells when transplanted with human umbilical-cord-blood-derived HSCs. These Hu-NSG-Tg(IL-15) mice demonstrate robust and long-term reconstitution with human immune cells, but do not develop graft-versus-host disease (GVHD), allowing for long-term studies of human NK cells. Finally, we show that these HSC engrafted mice can sustain HIV-1 infection, resulting in human NK cell responses in HIV-infected mice. We conclude that Hu-NSG-Tg(IL-15) mice are a robust novel model to study NK cell responses to HIV-1.

Generation and Characterization of a Humanized Lung Xenograft Mouse Model for Studying Henipavirus Pathogenesis.

The development of humanized mouse models has recently opened new avenues in the field of infectious diseases. These models allow research on many human viruses that were once difficult to study, because finding suitable animal models of infection can be challenging, cost prohibitive, and often do not entirely recapitulate all parameters of the disease. Here, we describe the procedure of human immune system reconstitution (humanization) of NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice by the bone marrow, liver, and thymus (BLT) reconstitution method as well as the process of human lung engraftment. We then describe how to infect these human lung grafts with the paramyxovirus Nipah virus (NiV) that can cause lethal respiratory disease in humans, and for which there is only limited understanding of pathogenesis to acute lung injury.

A Novel Human OX40L-CAR-Treg Specifically Targets Activated Antigen-Presenting Cells and Effectively Controls T Cell Alloreactivity and Xeno-GvHD

Background: Graft-versus-host disease (GvHD) remains the leading cause of non-relapse mortality after allogeneic hematopoietic stem cell transplantation (HCT). Adoptive transfer of regulatory T cells (Tregs) has demonstrated promising results in controlling GvHD in both animal models and phase I/II clinical trials. However, strategies to increase the stability of ex-vivo expanded Tregs, and to optimize their potency, are needed. Recent efforts to accomplish these goals have focused on engineering Chimeric Antigen Receptor (CAR) Tregs, with the first attempts using CARs targeted against disparate HLA antigens. However, Tregs targeting HLA have several limitations, including the downregulation of these antigens that accompanies some diseases, as well as the lack of utility of this approach in the HLA-matched setting. In this study, we tested a novel GvHD prophylaxis approach consisting of infusing donor Tregs engineered to express an anti-OX40L CAR that, upon engagement with activated OX40L+ host antigen-presenting cells (APCs), increases their suppressor potency to dampen APC-mediated activation of alloreactive T cells. Methods and Results: We designed a CAR construct containing an scFv targeting OX40L, a CD28 costimulatory domain, along with CD3ζ, as well as the fluorescent reporter NeonGreen, all under the control of a synthetic FOXP3 promoter. This design enabled the selective and sustained expression of the anti-OX40L CAR on CD25+CD127- FoxP3+ Treg cells. We also created Tregs transduced with a non-targeting NeonGreen-only control construct (Neon-Tregs). Engineered OX40L CAR-Tregs maintained expression of the canonical Treg markers FOXP3, CD25, and CTLA-4, and demonstrated robust activation in the presence of OX40L-expressing cells. In co-culture assays of OX40L CAR-Tregs with OX40L-expressing K562 target cells, we demonstrate upregulation of Treg suppressive proteins CTLA-4, LAP, CD71, GARP and LAG3 without inducing expression of pro-inflammatory cytokines (no upregulation of IFNγ, TNFα, IL17a) (Figure 1A). Activation of Tregs via CAR recognition of OX40L+ cells resulted in 2.5-fold enhancement in their potency to suppress anti-CD3/CD28-driven T cell proliferation in vitro compared to Neon-Tregs at a 1:4 Treg-to-Teff ratio (p<0.05). Furthermore, OX40L-CAR-Tregs demonstrated a greater capacity to inhibit monocyte-derived dendritic cell activation, highlighting the superior suppressive activity of these OX40L-CAR-Tregs compared to non-targeting Neon-Tregs. Importantly, in a human xenograft model of GvHD, induced by transplantation of human PBMC into sublethally irradiated NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice, OX40L CAR-Treg demonstrated superior GvHD disease control compared to both PBMC alone and Neon-Tregs. Clinical scores were assessed by a combinatorial system including five parameters: weight loss, posture, mobility, skin, and fur conditions, and curves were compared using a 2-way ANOVA mixed-effects analysis, which demonstrated improvement in clinical xeno-GvHD with the OX40L CAR-Treg > Neon-Treg > PBMC alone over the entire length of analysis (p <0.001). An example of the substantial improvement in the clinical score on Day +14 is as follows: combined GvHD clinical score = 6.5 for PBMC vs 2.5 for Neon-Treg vs 0.15 for OX40L CAR-Treg, p <0.0001 for all comparisons. This control of clinical GvHD resulted in prolonged recipient survival when compared to both PBMC alone and to control Neon-Tregs (MST = 34 days for OX40L-CAR-Treg, 20 days for Neon-Treg, 14 days for PBMC alone, p<0.001, Figure 1B). Conclusions: Collectively, these results demonstrate a novel and efficacious approach using OX40L-CAR Tregs to enhance Treg suppressive function and to control GvHD. Because OX40L is upregulated on APCs in inflammatory environments, and its expression is limited to APCs and activated endothelial cells, this approach provides a unique strategy for the control of allo-immunity after HCT. Moreover, these OX40L-CAR Treg may be broadly applicable beyond HCT, to control allo-immunity after solid organ transplant and to suppress T cell activation in autoimmune diseases. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Brain Organoids to Evaluate Cellular Therapies.

Animal models currently used to test the efficacy and safety of cell therapies, mainly murine models, have limitations as molecular, cellular, and physiological mechanisms are often inherently different between species, especially in the brain. Therefore, for clinical translation of cell-based medicinal products, the development of alternative models based on human neural cells may be crucial. We have developed an in vitro model of transplantation into human brain organoids to study the potential of neural stem cells as cell therapeutics and compared these data with standard xenograft studies in the brain of immunodeficient NOD.Cg-Prkdcscid&amp;nbsp;Il2rgtm1Wjl/SzJ (NSG) mice. Neural stem cells showed similar differentiation and proliferation potentials in both human brain organoids and mouse brains. Our results suggest that brain organoids can be informative in the evaluation of cell therapies, helping to reduce the number of animals used for regulatory studies.

Single Cell Analysis Identifies Immune Marker IL4I1 As Critical for Leukemogenesis and Immunity

The treatment landscape of acute myeloid leukemia (AML) is evolving with new targets entering clinical translation. However, patients’ responses are still heterogeneous. Bone marrow (BM) is considered an immune privilege organ, but recent evidence suggests that inflammatory insults can increase cell cycling in hematopoietic stem cells (HSCs) gradually accumulating DNA damage. Thus, discovering immune targets on leukemia cells is an urgent unmet need. Here, we used scRNA seq to compare BM aspirates from 12 complete response (CR) and 10 refractory patients. We found 24 cell clusters expressing established markers of hematopoietic population. Differentially expressed genes between CR and refractory patients were determined using EdgeR and illustrated by volcano plots (Log2FC>|0.58|, x-axis, and Log10Adjusted P, y-axis) followed by enrichment for immune markers. Interleukin 4-induced gene 1 (IL4I1), in cluster 5 (promonocyte-like AML) was the most significant immune marker overexpressed in refractory patients (Fig. 1A). IL4I1 encodes a secreted oxidase protein (Molinier-Frenkel et al. FEBS 2017) that induces cancer immune escape by limiting proliferation of cytotoxic T cells (Lasoudris et al. Eur J Immunol. 2011). IL4I1 also activates the aryl hydrocarbon receptor and correlates with lower survival in glioma patients (Sadik et al. Cell. 2020). Its role in AML is unknown. To determine its clinical relevance in AML, we generated Kaplan-Meier curves using TCGA (n=132) and TARGET AML (n=187) databases and showed that patients with high IL4I1 had decreased survival (Fig. 1B&C). IL4I1 expression is increased in AML patients’ samples as compared to normal blood samples (Fig. 1D) and found in patients with mixed lineage leukemia (MLL) or complex cytogenetics (Fig. 1E). We next interrogated IL4I1 expression on leukemia stem cells (LSCs) defined as CD34+CD38- in the Princess Margaret Leukemia database (n=75) and noted IL4I1 expression was higher on LSCs vs normal HSCs (Fig. 1F). We then knocked out the IL4I1 gene in MOLM14 leukemic cells using CRISPR/Cas9 technology. IL4I1 silencing inhibited leukemia proliferation measured by Ki67 (Fig. 1G) and increased leukemia apoptosis measured by Annexin-V (Fig. 1H) compared to wild type (WT) leukemic cells. IL4I1 deficiency in leukemic cells arrested G2/S/M cell cycle progression which accelerated cell differentiation as compared to WT leukemic cells (Fig. 1I). We also performed Pearson correlations of IL4I1 with leukemic oncogenic drivers such as homeobox A cluster (HOXA) genes which strongly associate with the MLL translocation (Ernst et al. Curr. Biol. 2004) in TCGA- and TARGET-AML databases. Radar plots showed that IL4I1 was significantly correlated with these HOXA family genes (Fig. 1J, TCGA shown). We next interrogated immune regulatory functions of IL4I1 in AML patients and showed that enrichment of IL4I1 high genes vs low were in 4 signaling pathways: (i) cytokines/inflammation, (ii) innate immunity, (iii) antigen presentation and (iv) adaptive immunity (Fig. 1K). Representative genes signatures in these 4 pathways are summarized in Fig. 1L. We further tested whether IL4I1 expressing leukemia cells (WT) suppress T cells expansion in vitro. We used CFSE dilution to measure CD8+ T cells proliferation. WT MOLM14egfp cells inhibited CD8+ T cell proliferation while IL4I1 blockade in MOLM14egfp cells restored their proliferation (Fig. 1M). To test the role of IL4I1 in AML progression in vivo, we injected NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice with IL4I1-CRISPR/Cas9 KO or WT MOLM14egfp cells (Fig. 2A). Mice injected with WT MOLM14egfp cells had higher leukemia burden (Fig. 2B), higher Ki67 proliferation rate (Fig. 2C), and lower apoptosis rate (Fig. 2D) than IL4I1-KO MOLM14egfp recipients at Day 14 post-challenge. Self-renewal ability of leukemia cells is correlated to reactive oxygen species (ROS) (Testa U. et al. Exp Hematol. 2016). We found that ROS levels in IL4I1 KO leukemic cells are diminished compared to WT leukemic cells (Fig. 2E). Finally, we tested IL4I1 expression in response to Fedratinib, a JAK2 inhibitor, and showed that IL4I1 expression was decreased in responders (R) vs nonresponders (NR) (Fig. 2F). We conclude that IL4I1 is a rational immune therapeutic target for AML and testing of IL4I1 Inhibitor CB-668 through a collaboration with Calithera is underway. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Preclinical Development of [211At]meta- astatobenzylguanidine ([211At]MABG) as an Alpha Particle Radiopharmaceutical Therapy for Neuroblastoma.

[131I]meta-iodobenzylguanidine ([131I]MIBG) is a targeted radiotherapeutic administered systemically to deliver beta particle radiation in neuroblastoma. However, relapses in the bone marrow are common. [211At]meta-astatobenzylguanidine ([211At] MABG) is an alpha particle emitter with higher biological effectiveness and short path length which effectively sterilizes microscopic residual disease. Here we investigated the safety and antitumor activity [211At]MABG in preclinical models of neuroblastoma. We defined the maximum tolerated dose (MTD), biodistribution, and toxicity of [211At]MABG in immunodeficient mice in comparison with [131I]MIBG. We compared the antitumor efficacy of [211At]MABG with [131I]MIBG in three murine xenograft models. Finally, we explored the efficacy of [211At]MABG after tail vein xenografting designed to model disseminated neuroblastoma. The MTD of [211At]MABG was 66.7 MBq/kg (1.8 mCi/kg) in CB17SC scid-/- mice and 51.8 MBq/kg (1.4 mCi/kg) in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. Biodistribution of [211At]MABG was similar to [131I]MIBG. Long-term toxicity studies on mice administered with doses up to 41.5 MBq/kg (1.12 mCi/kg) showed the radiotherapeutic to be well tolerated. Both 66.7 MBq/kg (1.8 mCi/kg) single dose and fractionated dosing 16.6 MBq/kg/fraction (0.45 mCi/kg) × 4 over 11 days induced marked tumor regression in two of the three models studied. Survival was significantly prolonged for mice treated with 12.9 MBq/kg/fraction (0.35 mCi/kg) × 4 doses over 11 days [211At]MABG in the disseminated disease (IMR-05NET/GFP/LUC) model (P = 0.003) suggesting eradication of microscopic disease. [211At]MABG has significant survival advantage in disseminated models of neuroblastoma. An alpha particle emitting radiopharmaceutical may be effective against microscopic disseminated disease, warranting clinical development.

Abstract 1338: Humanized mouse model for in vivo evaluation of bispecific antibody efficacy

Abstract Bispecific antibodies have shown several promising advantages over monoclonal antibodies and are emerging as one of growing cancer immunotherapies. Preclinical in vivo models to assess efficacy associated with immune cell engagement are needed. Here we evaluated an EGFR bispecific T cell engager (EGFRXCD3 BiTE) using xenograft models in humanized NSG™ (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) mice that have been engrafted with human CD34+ HSC and have human T cells in circulation. Three EGFR+ tumor models were used in this report including LG1202 lung PDX and two triple negative breast cancer cell lines MDA-MB-231 with a high EGFR expression level and MDA-MB-453 with a low EGFR expression. Interestingly we found that all three models were resistant to EGFR monoclonal antibody drug cetuximab despite the expression of EGFR but responded to EGFRXCD3 BiTE. BiTE-induced T cell activation was evident through the analysis of tumor infiltrated lymphocytes by flow cytometry at the end of the study. BiTE treatment for 3 weeks effectively reduced the LG1202 tumor growth whereas the effect of cetuximab on the tumor growth was minimal. In the BiTE-treated group, CD3+ T cell percentage increased as compared to the vehicle group, and both CD4+ and CD8+ T cell subsets showed an increased frequency of CD69+ cells. We also observed elevated levels of human cytokines IFN-γ, IL-6, IL-2, and IL-10 in circulation 4 h after animals received the first BiTE dose. We evaluated the dose response of BiTE treatments on MDA-MB-231 model with a high EGFR expression. Low dose BiTE reduced tumor growth whereas high dose BiTE effectively prevented or even regressed some tumor growth. Flow analysis showed that tumor CD3+ T cell frequency remained similar to the vehicle group but CD8+ T frequency increased after high dose BiTE. High CD69+CD8+ T cell frequency was found in the vehicle group and the percentage further increased after high dose BiTE. For the low EGFR-expressing MDA-MB-453 model, BiTE treatment for 4 weeks also effectively reduced the tumor growth. In comparison, while cetuximab treatment decreased EGFR expression on tumor cells, it did not reduce the tumor growth. Flow analysis showed that BiTE-treated group had increased T cell infiltration into the tumors when compared to the PBS and cetuximab groups. The frequency and cell number of CD25+ and CD69+ CD4+ T and CD8+ T cells in the tumor increased after BiTE treatment. Together, these data support our humanized mouse model to be used to validate T-cell dependent bispecific antibody efficacy. Citation Format: Li-Chin Yao, James G. Keck, Danying cai. Humanized mouse model for in vivo evaluation of bispecific antibody efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1338.

The P2X7 Receptor Antagonist AZ10606120 Does Not Alter Graft-Versus-Host Disease Development and Increases Serum Human Interferon-γ in a Humanized Mouse Model

Allogeneic hematopoietic stem cell transplantation is a curative therapy for hematological malignancies, but its efficacy is limited by graft-versus-host disease (GVHD). This life-threatening disorder develops when donor (graft) immune cells cause inflammatory damage to recipient (host) tissues. The immune cell receptor channel P2X7 and its ligand adenosine 5’-triphosphate (ATP) have been implicated in GVHD pathogenesis. Therefore, this signaling axis represents a potential therapeutic target. This study aimed to investigate if the specific P2X7 antagonist AZ10606120 (AZ10) could prevent GVHD development in a preclinical, humanized mouse model, in which NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice are injected with human peripheral blood mononuclear cells (hPBMCs). Flow cytometric measurements of ATP-induced cation dye uptake revealed that AZ10 blocked P2X7 activity in human RPMI 8226 multiple myeloma cells (IC50 of 1 ± 1 nM) and murine RAW 264.7 macrophages (IC50 of 3 ± 1 nM), as well as primary donor CD4+ and CD8+ T cells. However, AZ10 (2 mg/kg), injected intraperitonealy (i.p.) daily for the first 10 days post-hPBMC injection, did not reduce clinical or histological GVHD development in mice. AZ10 did not impact engraftment of human leukocytes, predominantly CD4+ and CD8+ T cells. However, AZ10 increased serum human interferon gamma (hIFN-γ) concentrations, with CD8+ T cells being the main hIFN-γ producing T cell subset. In conclusion, this study suggests a role for P2X7 activation in impairing hIFN-γ production during GVHD pathogenesis, with the use of P2X7 blockade as a therapeutic strategy warranting further investigation.

Degenerative Myelopathy and Neuropathy in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) Mice Caused by Lactate Dehydrogenase-Elevating Virus (LDV).

Following implantation of patient-derived xenograft (PDX) breast carcinomas from three separate individuals, 33/51 female NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice presented with progressive, unilateral to bilateral, ascending hindlimb paresis to paralysis. Mice were mildly dehydrated, in thin to poor body condition, with reduced to absent hindlimb withdrawal reflex and deep pain sensation. Microscopically, there was variable axonal swelling, vacuolation, and dilation of myelin sheaths within the ventral spinal cord and spinal nerve roots of the thoracolumbar and sacral spinal cord, as well as within corresponding sciatic nerves. Results of PCR screening of PDX samples obtained at necropsy and pooled environmental swabs from the racks housing affected animals were positive for lactate dehydrogenase-elevating virus (LDV). LDV is transmitted through animal-animal contact or commonly as a contaminant of biologic materials of mouse origin. Infection is associated with progressive degenerative myelopathy and neuropathy in strains of mice harboring endogenous retrovirus (AKR, C58), or in immunosuppressed strains (NOD-SCID, Foxn1nu), and can interfere with normal immune responses and alter engraftment and growth of xenograft tumors in immunosuppressed mice. This is the first reported series of LDV-induced poliomyelitis in NSG mice and should be recognized as a potentially significant confounder to biomedical studies utilizing immunodeficient xenograft models.

Targeting USP7 Suppresses Tumor Development By Promoting Ubiquitination of PHF8 and Suppressing SNAI1/Wnt Signaling in T-Cell Acute Lymphoblastic Leukemia

IntroductionT-cell acute lymphoblastic leukemia (T-ALL) is a common hematological malignancy with a high unfavorable prognosis. Ubiquitin-specific-processing protease 7 (USP7) is one of the deubiquitinating enzymes attracting concentrated attention in current studies for cancers; it is also involved in regulation of oncogenic transcriptional program in T-ALL, and serves as a potential target to treat T-ALL. USP7 is interacted with PHD Finger protein 8 (PHF8), a histone lysine demethylase in T-ALL. However, the impact of the interaction in T-ALL development is undetermined. In this study, we explored the anti-tumor effect of targeting USP7 and its downstream substrate in T-ALL and underlying mechanism.MethodsIn vitro GST pull-down assay, co-immunoprecipitation assay, protein deubiquitination and stability assays were used to detect the interaction of USP7 with its direct substrate and the ubiquitination level. Gain-of-function(overexpression) and loss-of-function (lentiviral shRNA knockdown) approaches for USP7 were conducted for gene expression, CCK-8 cell proliferation assay, and apoptosis assay with annexin V + PI staining. ChIP-qPCR assay was used to explore the enrichment of histone markers in promoter region of target gene. In vivo human T-ALL xenograft mouse model was developed in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mouse by tail vein injection of 2.5 × 10 6 /mouse and the leukemia engraftment was evaluated with human CD45+ cells by flow cytometry. The qPCR and western blot were carried out for detection mRNA level and protein level of related genes. The mRNA level of USP7 and its substrate PHF8 was examined by qPCR in 43 newly-diagnosed T-ALL patients with an approval of the Ethics Committee. Microarray datasets of T-ALL patients from GEO database were used to determine the USP7 and its substrate -related genes with web-based platform MEM and Limma.ResultsResults showed that USP7 directly interacted with PHF8; and overexpressed USP7 deubiquitinated and stabilized PHF8, and enhanced cell proliferation of JURKAT T-ALL cells. These data indicates targeting USP7 promotes cell proliferation of T-ALL cells through its substrate PHF8. Moreover, SNAI1 was identified as one of key co-expressed genes with PHF8 in microarray datasets from T-ALL patients, and knock-down of PHF8 suppressed the SNAL1 expression and increased the recruitment of repressive histone marker, H3K9me2 but decreased the enrichment of H3K4me3 in SNAI1 promoter. SNAI1 knockdown significantly induced the cell proliferation arrest and apoptosis of T-ALL cells (Fig.1A & 1B). With in vivo human leukemia xenograft mouse model, we further demonstrated that SNAI1 knockdown significantly reduce the spleen size and weight, the ratio of human CD45(+) cells, bone marrow cellularity and also the inflammatory cell infiltration compared to the scramble shRNA control (Fig.1C-1F). Moreover, Wnt signaling was identified as SNAI1 interaction partners by the pathway analysis in the SNAI1 interaction genes in the microarray data from T-ALL patients. SNAI1 knockdown significantly suppressed the expression of the Axin2 and Survivn, the key components of Wnt signaling. These data suggested oncogenic role of USP7/PHF8/SNAI1/Wnt signaling in T-ALL. Next, we explored the effect of SNAI1 on USP7 knockdown-induced anti-tumor effect. We found that USP7 knockdown induced cell proliferation arrest and apoptosis, and overexpression of SNAI1 could block the effect in vitro. Furthermore, the in vivo data showed that USP7 knockdown significantly suppressed spleen size and weight, the ratio of human CD45(+) cells, bone marrow cellularity, inflammatory cell infiltration, and the protein expression of PHF8, SNAI1, Axin2 and Survivin; and SNAI1 overexpression completely rescue the USP7 knockdown-mediated antitumor effect and restored the expression of Axin2 and Survivin in vivo (Fig.2).Conclusion:Our results demonstrated that targeting USP7 by shRNA induces the cell proliferation arrest and apoptosis by promoting ubiquitination of PHF8 and suppressing SNAI1/Wnt signaling in T-ALL. Our data also revealed the oncogenic roles of USP7/PHF8/SNAI1/Wnt signaling in T-ALL and suggested targeting the signaling pathway as potential therapy in T-ALL. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.