Abstract 6026: A novel humanized mouse model based on NOG-FcgR-/-mice recapitulates anti-tumor immune reactions by human immune systems in response to anti-PD-1 antibody (Nivolumab)

Humanized mice with human hematopoietic and immune systems have been frequently used for examining in vivo anti-cancer effects of various drugs, including immune checkpoint inhibitors (ICIs) like anti-PD-1 or anti-CTLA-4 antibodies, yet the reliability of the mouse models to be improved. We have recently developed NOD-scid, IL-2Rγ KO (NOG) mice deficient for the mouse FcεRI and FcγIIb genes, thus lacking the expression of functional mouse FcγRs, (NOG-FcγR-/-) and the activity of endogenous antibody-dependent cellular cytotoxicity (ADCC). Reconstitution experiments with human hematopoietic stem cells (HSC) showed that NOG-FcγR-/- mice had higher engraftment capacity for human leucocytes than NOG mice, namely the numbers of HSC-derived human CD19+ B cells and CD33+ myeloid cells, but not CD3+ T cells, were higher in the various tissues in NOG-FcγR-/- mice than those in NOG mice. In tumor-bearing experiments using those reconstituted mice, it was of interest that humanized NOG-FcγR-/- mice (huNOG-FcγR-/-) could invoke strong tumor growth suppression or rejection in response to anti-PD-1 antibody (Nivolumab) treatment in several cancer cell lines, which was absent in conventional huNOG mice. Accordingly, Nivolumab treatment in huNOG-FcγR-/- mice induced a significant increase of human T cells in number in the spleen and infiltration of human T cells with Granzyme B and Perforin-expression into tumor. Furthermore, the composition of activated T cells was different between huNOG-FcγR-/- and huNOG mice. HuNOG-FcγR-/- mice had elevated numbers of activated T cells, both T central memory cells (TCM) and T effector memory cells (TEM), whereas huNOG mice showed an opposite trend, reduced TCM and TEM and increase of naïve T cells. Our results suggest that the novel NOG-FcγR-/- mice become a good model for elucidating the cellular and molecular mechanisms of human tumor rejection by human T cells, and that they will provide a superior in vivo platform for evaluation of anti-cancer drugs, especially, in combination with ICIs like Nivolumab.

Citation Format: Ikumi Katano, Asami Hanazawa, Iyo Otsuka, Takuya Yamaguchi, Misa Mochiduki, Kenji Kawai, Ryoji Ito, Motohito Goto, Takahiro Kagawa, Takeshi Takahashi. A novel humanized mouse model based on NOG-FcgR-/-mice recapitulates anti-tumor immune reactions by human immune systems in response to anti-PD-1 antibody (Nivolumab) [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 6026.

A humanized mouse model to study asthmatic airway inflammation via the human IL-33/IL-13 axis

Asthma is one of the most common immunological diseases and is characterized by airway hyperresponsiveness (AHR), mucus overproduction, and airway eosinophilia. Although mouse models have provided insight into the mechanisms by which type-2 cytokines induce asthmatic airway inflammation, differences between the rodent and human immune systems hamper efforts to improve understanding of human allergic diseases. In this study, we aim to establish a preclinical animal model of asthmatic airway inflammation using humanized IL-3/GM-CSF or IL-3/GM-CSF/IL-5 Tg NOD/Shi-scid-IL2rγnull (NOG) mice and investigate the roles of human type-2 immune responses in the asthmatic mice. Several important characteristics of asthma - such as AHR, goblet cell hyperplasia, T cell infiltration, IL-13 production, and periostin secretion - were induced in IL-3/GM-CSF Tg mice by intratracheally administered human IL-33. In addition to these characteristics, human eosinophilic inflammation was observed in IL-3/GM-CSF/IL-5 Tg mice. The asthmatic mechanisms of the humanized mice were driven by activation of human Th2 and mast cells by IL-33 stimulation. Furthermore, treatment of the humanized mice with an anti-human IL-13 antibody significantly suppressed these characteristics. Therefore, the humanized mice may enhance our understanding of the pathophysiology of allergic disorders and facilitate the preclinical development of new therapeutics for IL-33-mediated type-2 inflammation in asthma.

Generation of Human Immunosuppressive Myeloid Cell Populations in Human Interleukin-6 Transgenic NOG Mice

The tumor microenvironment contains unique immune cells, termed myeloid-derived suppressor cells (MDSCs), and tumor-associated macrophages (TAMs) that suppress host anti-tumor immunity and promote tumor angiogenesis and metastasis. Although these cells are considered a key target of cancer immune therapy, in vivo animal models allowing differentiation of human immunosuppressive myeloid cells have yet to be established, hampering the development of novel cancer therapies. In this study, we established a novel humanized transgenic (Tg) mouse strain, human interleukin (hIL)-6-expressing NOG mice (NOG-hIL-6 transgenic mice). After transplantation of human hematopoietic stem cells (HSCs), the HSC-transplanted NOG-hIL-6 Tg mice (HSC-NOG-hIL-6 Tg mice) showed enhanced human monocyte/macrophage differentiation. A significant number of human monocytes were negative for HLA-DR expression and resembled immature myeloid cells in the spleen and peripheral blood from HSC-NOG-hIL-6 Tg mice, but not from HSC-NOG non-Tg mice. Engraftment of HSC4 cells, a human head and neck squamous cell carcinoma-derived cell line producing various factors including IL-6, IL-1β, macrophage colony-stimulating factor (M-CSF), and vascular endothelial growth factor (VEGF), into HSC-NOG-hIL-6 Tg mice induced a significant number of TAM-like cells, but few were induced in HSC-NOG non-Tg mice. The tumor-infiltrating macrophages in HSC-NOG-hIL-6 Tg mice expressed a high level of CD163, a marker of immunoregulatory myeloid cells, and produced immunosuppressive molecules such as arginase-1 (Arg-1), IL-10, and VEGF. Such cells from HSC-NOG-hIL-6 Tg mice, but not HSC-NOG non-Tg mice, suppressed human T cell proliferation in response to antigen stimulation in in vitro cultures. These results suggest that functional human TAMs can be developed in NOG-hIL-6 Tg mice. This mouse model will contribute to the development of novel cancer immune therapies targeting immunoregulatory/immunosuppressive myeloid cells.

Myosin light chains 9 and 12 are functional ligands for CD69 that regulate airway inflammation

Recent decades have witnessed a rapid worldwide increase in chronic inflammatory disorders such as asthma. CD4⁺ T helper 2 cells play critical roles in the pathogenesis of allergic airway inflammation, and CD69 expression on activated CD4 T cells is required to induce allergic inflammation in tissues. However, how CD69 mechanistically controls allergic inflammation remains poorly defined. In lymphoid tissues, CD69 regulates cellular retention through inhibition of S1P1 expression and requires no specific ligands to function. In contrast, we show herein that myosin light chain (Myl) 9 and Myl12 are new functional ligands for CD69. Blockade of CD69-Myl9/12 interaction ameliorates allergic airway inflammation in ovalbumin-induced and house dust mite-induced mouse models of asthma. Within the inflamed mouse airways, we found that the expression of Myl9/12 was increased and that platelet-derived Myl9/12 localized to the luminal surface of blood vessels and formed intravascular net-like structures. Analysis of nasal polyps of eosinophilic chronic rhinosinusitis patients revealed that Myl9/12 expression was increased in inflammatory lesions and was distributed within net-like structures in the intravascular space. In addition, we detected Myl9/12 in perivascular spaces where many CD69⁺ cells were positioned within Myl9/12 structures. Thus, CD69-Myl9/12 interaction is a key event in the recruitment of activated CD69⁺ T cells to inflamed tissues and could be a therapeutic target for intractable airway inflammatory diseases.

B Cells Negatively Regulate the Establishment of CD49b(+)T-bet(+) Resting Memory T Helper Cells in the Bone Marrow

During an immune reaction, some antigen-experienced CD4 T cells relocate from secondary lymphoid organs (SLOs) to the bone marrow (BM) in a CD49b-dependent manner and reside and rest there as professional memory CD4 T cells. However, it remains unclear how the precursors of BM memory CD4 T cells are generated in the SLOs. While several studies have so far shown that B cell depletion reduces the persistence of memory CD4 T cells in the spleen, we here show that B cell depletion enhances the establishment of memory CD4 T cells in the BM and that B cell transfer conversely suppresses it. Interestingly, the number of antigen-experienced CD4 T cells in the BM synchronizes the number of CD49b⁺T-bet⁺ antigen-experienced CD4 T cells in the spleen. CD49b⁺T-bet⁺ antigen-experienced CD4 T cells preferentially localize in the red pulp area of the spleen and the BM in a T-bet-independent manner. We suggest that B cells negatively control the generation of CD49b⁺T-bet⁺ precursors of resting memory CD4 T cells in the spleen and may play a role in bifurcation of activated effector and resting memory CD4 T cell lineages.

CD49b/CD69-Dependent Generation of Resting T Helper Cell Memory

In the absence of antigen, memory T helper (Th) cells are maintained in a resting state. Recently it has been shown that bone marrow (BM) is a major reservoir of resting memory Th cells. In a given immune response, less than 10% of the activated CD4 T cells are recruited to the pool of resting BM memory Th cells. Here we review recent evidence that CD69 and CD49b control homing of memory Th cell precursors to the BM. During the effector phase of an immune response, about 10% of activated CD4 T cells in the spleen express both CD69 and CD49b, and thus qualify as precursors of resting memory Th cells of BM. Loss or blockade of CD69 and CD49b expression on CD4 T cells impairs the generation of resting memory Th cells in the BM. Moreover, in the absence of BM memory Th cells in CD69-deficient mice, T-cell help for B cells is impaired, confirming the central role of BM memory Th cells in the maintenance of immunological memory.

Murine Schnurri-2 controls natural killer cell function and lymphoma development

Schnurri (Shn)-2 is a large zinc finger-containing protein implicated in cell growth, signal transduction and lymphocyte development. Here, we report that Shn-2-deficient (Shn-2(-/-)) mice develop CD3-positive lymphoma spontaneously. In Shn-2(-/-) mice, we observed decreased cytotoxicity of natural killer (NK) cells accompanied by decreased expression of perforin and granzyme-B. In addition, phosphorylation of signal transducer and activator of transcription (STAT) 5 was reduced in Shn-2(-/-) NK cells, while phosphorylation of STAT3 and protein expression of nuclear factor-κB p65 subunit were enhanced in Shn-2(-/-) NK cells. Moreover, cell-surface expression of activation molecules such as CD27, CD69 and CD122 were decreased on Shn-2(-/-) NK cells. Thus, Shn-2 is considered to play an important role in the activation and function of NK cells and the development of T cell lymphoma in vivo.

T-helper (Th)1/Th2 imbalance in the peripheral blood of dogs with malignant tumor

T helper type 1 cell (Th1)/Th2 imbalance has been observed in a variety of pathological conditions, including malignant diseases. We evaluated the Th1/Th2 in peripheral blood Th cells by means of intracytoplasmic cytokine analysis in 11 dogs with advanced malignant tumor; four of them showed metastatic tumor. The percentage of Th1 was significantly lower and the percentage of Th2 was significantly higher in diseased dogs compared to healthy dogs. The percentage of Th1 in three patients with metastatic tumor was significantly lower than that in the patients with non-metastatic tumor. We conclude that the Th1/Th2 balance was polarized to Th2 in dogs with cancer.

Electroretinogram analysis of relative spectral sensitivity in genetically identified dichromatic macaques

The retinas of macaque monkeys usually contain three types of photopigment, providing them with trichromatic color vision homologous to that of humans. However, we recently used molecular genetic analysis to identify several macaques with a dichromatic genotype. The affected X chromosome of these animals contains a hybrid gene of long-wavelength-sensitive (L) and middle-wavelength-sensitive (M) photopigments instead of separate genes encoding L and M photopigments. The product of the hybrid gene exhibits a spectral sensitivity close to that of M photopigment; consequently, male monkeys carrying the hybrid gene are genetic protanopes, effectively lacking L photopigment. In the present study, we assessed retinal expression of L photopigment in monkeys carrying the hybrid gene. The relative sensitivities to middle-wavelength (green) and long-wavelength (red) light were measured by electroretinogram flicker photometry. We found the sensitivity to red light to be extremely low in protanopic male monkeys compared with monkeys with the normal genotype. In female heterozygotes, sensitivity to red light was intermediate between the genetic protanopes and normal monkeys. Decreased sensitivity to long wavelengths was thus consistent with genetic loss of L photopigment.

Influence of the direction of elemental luminance gradients on the responses of V4 cells to textured surfaces

The texture of an object provides important cues for its recognition; however, little is known about the neural representation of texture. To investigate the representation of texture in the visual cortex, we recorded single-cell activities in area V4 of macaque monkeys. To distinguish the sensitivity of the cells to texture parameters such as density and element size from that to spatial frequency, we used texture stimuli mimicking shaded granular surfaces. We varied the size and density of the texture elements and the direction of elemental luminance gradients (apparent shadings) as stimulus parameters. Most macaque V4 cells (151 of 170; 89%) exhibited sensitivity to the texture parameters. Interestingly, 21 of these cells were tuned to single shading directions (unidirectional tuning). This unidirectional tuning cannot be explained by complex-cell-like tuning for spectral power of spatial frequency, because texture stimuli with a shading direction and its opposite have almost the same spectral power. Unidirectional tunings of these cells were invariant for the position of the texture elements. Thus, this tuning cannot be explained by simple-cell-like phase-dependent spatial frequency tuning or selectivity to a particular arrangement of the elements. Moreover, the unidirectional tuning had a bias toward vertical directions, consistent with an anisotropy in the perception of three-dimensional shape from shading. This novel spatial property suggests that V4 cells are involved in extracting texture features from objects, including their three-dimensionality.

Neural selectivity for hue and saturation of colour in the primary visual cortex of the monkey

In the inferior temporal (IT) cortex of monkeys, which has been shown to play a critical role in colour discrimination, there are neurons sensitive to a narrow range of hues and saturation. By contrast, neurons in the retina and the parvocellular layer of the lateral geniculate nucleus (pLGN) encode colours in a way that does not provide explicit representation of hue or saturation, and the process by which hue- and saturation-selectivity is elaborated remains unknown. We therefore tested the colour-selectivity of neurons in the primary visual cortex (V1) and compared it with those of pLGN and IT neurons. Quantitative analysis was performed using a standard set of colours, systematically distributed within the CIE (Commission Internationale de l'Eclairage)-xy chromaticity diagram. Selectivity for hue and saturation was characterized by analysing response contours reflecting the overall distribution of responses across the chromaticity diagram. We found that the response contours of almost all pLGN neurons were linear and broadly tuned for hue. Many V1 neurons behaved similarly; nonetheless, a considerable number of V1 neurons had clearly curved response contours and were selective for a narrow range of hues or saturation. The relative frequencies of neurons exhibiting various selectivities for hue and saturation were remarkably similar in the V1 and IT cortex, but were clearly different in the pLGN. Thus, V1 apparently plays a very important role in the conversion of colour signals necessary for generating the elaborate colour selectivity observed in the IT cortex.

Enhancement of glutaminase-like immunoreactivity in rat brain by an irreversible inhibitor of the enzyme

Changes of glutaminase immunoreactivity in rat brain were examined after intracranial injection of 6-diazo-5-oxo-L-norleucine (DON), an irreversible inhibitor of glutaminase. When 1 M DON was injected into the lateral ventricle, a half-lethal dose was 7.5-10 mumol. After intraventricular injection of 2-7.5 mumol DON, glutaminase immunoreactivity was dose dependently enhanced with the maximum enhancement 3-5 days after the injection. The enhanced glutaminase immunoreactivity was recognized by enlarged granular immunodeposits in both perikarya and neuropil in many regions, such as the hippocampus, thalamus, hypothalamus, periaqueductal gray, and some brain stem, cerebellar, and spinal cord regions. Intrathalamic injection of 0.2 mumol DON enhanced glutaminase immunoreactivity in many neuronal perikarya in the thalamus and in some perikarya in layer VI of the cerebral cortex. Intrastriatal injection of the same dose of DON enhanced glutaminase immunoreactivity in neuropil of the caudoputamen and in many neuronal perikarya of the intralaminar thalamic nuclei. These results suggested that DON induced a new massive synthesis of glutaminase in the affected neurons.