Differentiation of fetal hematopoietic stem cells requires ARID4B to restrict autocrine KITLG/KIT-Src signaling.

Balance between the hematopoietic stem cell (HSC) duality to either possess self-renewal capacity or differentiate into multipotency progenitors (MPPs) is crucial for maintaining homeostasis of the hematopoietic stem/progenitor cell (HSPC) compartment. To retain the HSC self-renewal activity, KIT, a receptor tyrosine kinase, in HSCs is activated by its cognate ligand KITLG originating from niche cells. Here, we show that AT-rich interaction domain 4B (ARID4B) interferes with KITLG/KIT signaling, consequently allowing HSC differentiation. Conditional Arid4b knockout in mouse hematopoietic cells blocks fetal HSC differentiation, preventing hematopoiesis. Mechanistically, ARID4B-deficient HSCs self-express KITLG and overexpress KIT. As to downstream pathways of KITLG/KIT signaling, inhibition of Src family kinases rescues the HSC differentiation defect elicited by ARID4B loss. In summary, the intrinsic ARID4B-KITLG/KIT-Src axis is an HSPC regulatory program that enables the differentiation state, while KIT stimulation by KITLG from niche cells preserves the HSPC undifferentiated pool

Adipocyte PD-L1 Modulates Checkpoint Blockade Cancer Immunotherapy Efficacy

PD-L1 expression in both tumor and host cells correlates with antitumor therapeutic efficacy, but the specific contribution of PD-L1 in various cell compartments to antitumor immunity remains to be fully elucidated. Here we show that PD-L1 expression is significantly elevated in human and mouse mature adipocytes versus preadipocytes. When co-cultured with mouse splenocytes, adipocytes reduce αPD-L1 antibody-mediated CD8+ T cell activation. Genetic ablation of adipose PD-L1 obliterates, while enforced PD-L1 expression in preadipocytes confers, the immune-inhibitory effect of adipocytes. Pharmacologic inhibition of adipogenesis by the PPAR gamma antagonist GW9662 reduces adipose PD-L1 expression and enhances the antitumor efficacy of αPD-L1 and αPD-1 immunotherapies in female mice bearing syngeneic melanoma or mammary tumors. Combo treatment with GW9662 and αPD-L1 increased antitumor lymphocytes infiltration versus control or single agent treatment. In diet-induced obese female mice, combo treatment elicited suppressed melanoma growth, although less effectively versus lean females. In contrast to females, melanomas in either lean or obese male mice exhibited no applicable response to combo treatment. More strikingly, obese males lost αPD-L1 single treatment response versus lean males, with lower CD45+ and CD3+ T cell infiltration in tumors. However, castration in lean males rescued efficacy of combo treatment. These data suggest an antagonistic effect of male hormones in this combination. Our findings provide a previously unappreciated approach to bolster anticancer immunotherapy efficacy. The potential impact of sex and obesity warrants consideration in future development of immunotherapy-related combination therapy

CRYSTAL VIBRATION OF BETA BARIUM METABORATE AND ITS PHASE TRANSITION BY RAMAN SCATTERING

Author Institution: Laboratory of Vibrational Spectroscopy, Institute of Chemistry, Academia Sinica(A) The Raman and i.r. spectra of the newly synthesized second harmonic generating crystal $\beta$-barium metaborate in the low temperature phase are presented with a complete assignment of the external and internal vibrational modes. Emphasis is put on the discussion of the site group effect, the isotope effect and the dynamic coupling between the external and the internal motion of the metaborate ring and the barium ion. Force constants are also calculated with the prediction that there is one internal vibrational mode of the metaborate ring at a frequency of $177 cm^{-1}$ which is of the order of the frequencies of the lattice modes. (B) The Raman spectra of beta barium metaborate crystal are presented in the temperature range from $25^{\circ}C$ to $400^{\circ}C$. The spectra reveal that, as the temperature rises, the frequencies of the internal modes are unaffected. However, those of the lattice modes decrease slightly by about $3 cm^{-1}$. Results also show that the phase transition between the low and high temperature phases which are known in the literature occurs over a wide temperature range with no significant changes spectroscopically except the enhancement of the intensity of the translational mode of barium ions at $86 cm^{-1}$ as the temperature rises. Most intensity enhanced is of E symmetry. The enhancement is most drastic around $217^{\circ}C$ and $317^{\circ}C$. It is interpreted that the phase transition is mainly due to the rearrangement of the barium ions in the crystal. As the temperature rises, more barium ions are shifted to the sites of $C_{3}$ and $D_{3}$ symmetries. The role of the barium ion is also discussed along with its relationship with the second harmonic generating property of the bete barium metaborate crystal

Mechanisms of Resistance to Antibody–Drug Conjugates

Antibody–drug conjugates (ADCs), with antibodies targeted against specific antigens linked to cytotoxic payloads, offer the opportunity for a more specific delivery of chemotherapy and other bioactive payloads to minimize side effects. First approved in the setting of HER2+ breast cancer, more recent ADCs have been developed for triple-negative breast cancer (TNBC) and, most recently, hormone receptor-positive (HR+) breast cancer. While antibody–drug conjugates have compared favorably against traditional chemotherapy in some settings, patients eventually progress on these therapies and require a change in treatment. Mechanisms to explain the resistance to ADCs are highly sought after, in hopes of developing next-line treatment options and expanding the therapeutic windows of existing therapies. These resistance mechanisms are categorized as follows: change in antigen expression, change in ADC processing and resistance, and efflux of the ADC payload. This paper reviews the recently published literature on these mechanisms as well as potential options to overcome these barriers

Genetic ablation of adipocyte PD-L1 reduces tumor growth but accentuates obesity-associated inflammation.

The programmed death-ligand 1 (PD-L1)-dependent immune checkpoint attenuates host immunity and maintains self-tolerance. Imbalance between protective immunity and immunopathology due to altered PD-L1 signaling can lead to autoimmunity or tumor immunosuppression. The role of the PD-L1-dependent checkpoint in non-immune system is less reported. We previously found that white adipocytes highly express PD-L1. Here we show that adipocyte-specific PD-L1 knockout mice exhibit enhanced host anti-tumor immunity against mammary tumors and melanoma with low or no tumor PD-L1. However, adipocyte PD-L1 ablation in tumor-free mice also exacerbates diet-induced body weight gain, pro-inflammatory macrophage infiltration into adipose tissue, and insulin resistance. Low PD-L1 mRNA levels in human adipose tissue correlate with high body mass index and presence of type 2 diabetes. Therefore, our mouse genetic approach unequivocally demonstrates a cell-autonomous function of adipocyte PD-L1 in promoting tumor growth and inhibiting antitumor immunity. In addition, our work uncovers a previously unrecognized role of adipocyte PD-L1 in mitigating obesity-related inflammation and metabolic dysfunction

PPARγ inhibition boosts efficacy of PD-L1 Checkpoint Blockade Immunotherapy against Murine Melanoma in a sexually dimorphic manner.

Immune checkpoint blockade-based immunotherapy has become standard of care for multiple cancer types. However, the overall response rates among various cancer types still remain unsatisfactory. There is a pressing clinical need to identify combination therapies to improve efficacy of anticancer immunotherapy. We previously showed that pharmacologic inhibition of PPARγ by GW9662 boosts αPD-L1 and αPD-1 antibody efficacy in treating murine mammary tumors. In addition, we defined sexually dimorphic αPD-L1 efficacy in B16 melanoma. Here, we show a sexually dimorphic response to the combination of GW9662 and αPD-L1 immunotherapy in B16 melanoma. Combination effects were observed in female, but not male hosts. Neither female oöphorectomy impairs, nor does male castration rescue the combination effects, suggesting a sex hormone-independent response to this combination therapy. In diet-induced obese females, melanoma growth remained responsive to the combination treatment, albeit less robustly than lean females. These findings are informative for future design and application of immunotherapy-related combination therapy for treating human melanoma patients by taking gender and obesity status into consideration

Estrogen receptor beta signaling in CD8 + T cells boosts T cell receptor activation and antitumor immunity through a phosphotyrosine switch

BackgroundThe non-overlapping functions of the two estrogen receptor subtypes, ERα (Estrogen Receptor α)and ERβ (Estrogen Receptor β), in tumor cells have been studied extensively. However, their counterparts in host cells is vastly underinterrogated. Even less is known about how ERα and ERβ activities are regulated in a subtype-specific manner. We previously identified a phosphotyrosine residue (pY36) of human ERβ that is important for tumor ERβ to inhibit growth of breast cancer cells in vitro and in vivo. A role of this ERβ phosphotyrosine switch in regulating host ERβ remains unclear.Conventional gene editing was used to mutate the corresponding tyrosine residue of endogenous mouse ERβ (Y55F) in mouse embryonic stem cells. The derived homozygous mutant Esr2Y55F/Y55F mouse strain and its wild-type (WT) counterpart were compared in various transplant tumor models for their ability to support tumor growth. In addition, flow cytometry-based immunophenotyping was carried out to assess antitumor immunity of WT and mutant hosts. Adoptive transfer of bone marrow and purified CD8+ T cells were performed to identify the host cell type that harbors ERβ-dependent antitumor function. Furthermore, cell signaling assays were conducted to compare T cell receptor (TCR)-initiated signaling cascade in CD8+ T cells of WT and mutant mice. Lastly, the ERβ-selective agonist S-equol was evaluated for its efficacy to boost immune checkpoint blockade (ICB)-based anticancer immunotherapy.Disabling the ERβ-specific phosphotyrosine switch in tumor-bearing hosts exacerbates tumor growth. Further, a cell-autonomous ERβ function was defined in CD8+ effector T cells. Mechanistically, TCR activation triggers ERβ phosphorylation, which in turn augments the downstream TCR signaling cascade via a non-genomic action of ERβ. S-equol facilitates TCR activation that stimulates the ERβ phosphotyrosine switch and boosts anti-PD-1 (Programmed cell death protein 1) ICB immunotherapy.Our mouse genetic study clearly demonstrates a role of the ERβ phosphotyrosine switch in regulating ERβ-dependent antitumor immunity in CD8+ T cells. Our findings support the development of ERβ agonists including S-equol in combination with ICB immunotherapy for cancer treatment