Structural and functional characterization of a monoclonal antibody blocking TIGIT.

TIGIT is an immune checkpoint receptor that is expressed on subsets of activated T cells and natural killer (NK) cells. Several ligands for TIGIT, including poliovirus receptor (PVR), are expressed on cancer cells and mediate inhibitory signaling to suppress antitumor activities of the immune cells. Many studies support that the TIGIT signaling is a potential target for cancer immunotherapy. We developed an IgG4-type monoclonal antibody against human TIGIT, designated as MG1131, using a phage display library of single-chain variable fragments (scFvs). MG1131 interacts with TIGIT much more tightly than PVR does. The crystal structure of a scFv version of MG1131 bound to TIGIT was determined, showing that MG1131 could block the PVR-TIGIT interaction and thus the immunosuppressive signaling of TIGIT. Consistently, MG1131 is bound to TIGIT-expressing cells and interferes with PVR binding to these cells. Moreover, MG1131 increased NK cell-mediated tumor killing activities, inhibited immunosuppressive activity of regulatory T (Treg) cells from healthy donors, and restored interferon-γ secretion from peripheral blood mononuclear cells derived from multiple myeloma patients. MG1131 also increased T cell infiltration to the tumor site and inhibited tumor growth in mice. Collectively, these data indicate that MG1131 modulates the effector functions of T cells and NK cells positively and Treg cells negatively.

MG1141A as a Highly Potent Monoclonal Neutralizing Antibody Against SARS-CoV-2 Variants.

Since the coronavirus disease outbreak in 2019, several antibody therapeutics have been developed to treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Antibody therapeutics are effective in neutralizing the virus and reducing hospitalization in patients with mild and moderate infections. These therapeutics target the spike protein of SARS-CoV-2; however, emerging mutations in this protein reduce their efficiency. In this study, we developed a universal SARS-CoV-2 neutralizing antibody. We generated a humanized monoclonal antibody, MG1141A, against the receptor-binding domain of the spike protein through traditional mouse immunization. We confirmed that MG1141A could effectively neutralize live viruses, with an EC50 of 92 pM, and that it exhibited effective Fc-mediated functions. Additionally, it retained its neutralizing activity against the alpha (UK), beta (South Africa), and gamma (Brazil) variants of SARS-CoV-2. Taken together, our study contributes to the development of a novel antibody therapeutic approach, which can effectively combat emerging SARS-CoV-2 mutations.

Ssu72 is a T-cell receptor-responsive modifier that is indispensable for regulatory T cells.

The homeostatic balance between effector T cells and regulatory T cells (Tregs) is crucial for adaptive immunity; however, epigenetic programs that inhibit phosphorylation to regulate Treg development, peripheral expression, and suppressive activity are elusive. Here, we found that the Ssu72 phosphatase is activated by various T-cell receptor signaling pathways, including the T-cell receptor and IL-2R pathways, and localizes at the cell membrane. Deletion of Ssu72 in T cells disrupts CD4+ T-cell differentiation into Tregs in the periphery via the production of high levels of the effector cytokines IL-2 and IFNγ, which induce CD4+ T-cell activation and differentiation into effector cell lineages. We also found a close correlation between downregulation of Ssu72 and severe defects in mucosal tolerance in patients. Interestingly, Ssu72 forms a complex with PLCγ1, which is an essential effector molecule for T-cell receptor signaling as well as Treg development and function. Ssu72 deficiency impairs PLCγ1 downstream signaling and results in failure of Foxp3 induction. Thus, our studies show that the Ssu72-mediated cytokine response coordinates the differentiation and function of Treg cells in the periphery.

Topically administered Risedronate shows powerful anti-osteoporosis effect in ovariectomized mouse model.

We investigated the therapeutic effect of topical Risedronate (RIS) on a mouse model of estrogen-deficient osteoporosis. Fourteen-week-old female mice were ovariectomized and assigned to 4 groups: SHAM-operated (SHAM), OVX mice treated with vehicle (OVX-V), OVX mice treated with 0.2% RIS (OVX-0.2% RIS), and OVX-mice treated with 0.02% RIS (OVX-0.02% RIS). Topical samples containing RIS were prepared in 10% (w/w) polyethylene glycol (PEG, MW 400) and 80 µg of sample was spread on the mice's mid-backs every 3 days for 5 weeks. Micro-CT analysis of femora demonstrated that OVX-0.2% RIS exhibited a 29% greater bone mineral density and 24% greater bone volume fraction than that of OVX-V group. Investigation of the trabecular bone in OVX-0.2% RIS revealed a 24% higher bone volume (BV/TV), 51% higher trabecular number (Tb.N), and 40% lower trabecular separation (Tb.Sp) compared to OVX-V mice. Additionally, bone phenotypes of tibiae were further confirmed by histological analysis. OVX-0.2% RIS group exhibited a 494% greater BV/TV, 464% less Tb.Sp, 81% greater active osteoclast surface (Oc.S/BS) and 26% less osteoclast number (N.Oc/BS) than that of OVX-V group. Collectively, these results indicated that topical delivery of RIS has powerful pharmaceutical effects on the prevention of osteoporosis and bone turnover.

Ion pairs of risedronate for transdermal delivery and enhanced permeation rate on hairless mouse skin.

Ion-paired solutions of risedronate (RIS) with L-arginine (ARG), L-lysine (LYS), and diethylenetriamine (DETA) were tested in vitro for their potential to enhance the penetration of RIS across the skin of hairless mouse. The xylene solubilities of RIS paired with ARG, LYS, and DETA in molar ratios of 1:2, 1:2, and 1:1 were 8.9%, 12.0%, and 2.1%, respectively, in comparison with the solubility in deionized water, but non-ion-paired RIS was not detected in xylene. In vitro permeation tests were performed on the skin of hairless mice, and the results indicated that ion-paired RIS could penetrate mice skin about 36 times more effectively than RIS alone. The cumulative amount of ion paired RIS after 24 h resulted in 475.18±94.19 µg/cm(2) and 511.21±106.52 µg/cm(2) at molar ratio of 1:2 and 1:1. The cumulative amount of RIS alone was as low as 14.13±5.49 µg/cm(2) in 24h. The hairless mice showed no skin irritation after a single administration of RIS alone and ion-paired RIS (1:2 molar ratio with ARG, and 1:1 molar ratio with DETA). In this study, we found that RIS can be delivered transdermally, and the ion-paired system in an aqueous solution showed an enhanced flux through the skin barrier.