Intranasal SARS-CoV-2 RBD decorated nanoparticle vaccine enhances viral clearance in the Syrian hamster model.

Multiple vaccines have been developed and licensed for SARS-CoV-2. While these vaccines reduce disease severity, they do not prevent infection, and SARS-CoV-2 continues to spread and evolve. To prevent infection and limit transmission, vaccines must be developed that induce immunity in the respiratory tract. Therefore, we performed proof-of-principle vaccination studies with an intranasal nanoparticle vaccine against SARS-CoV-2. The vaccine candidate consisted of the self-assembling 60-subunit I3-01 protein scaffold covalently decorated with the SARS-CoV-2 receptor binding domain (RBD) using the SpyCatcher-SpyTag system. We verified the intended antigen display features by reconstructing the I3-01 scaffold to 3.4A using cryo-EM, and then demonstrated that the scaffold was highly saturated when grafted with RBD. Using this RBD-grafted SpyCage scaffold (RBD+SpyCage), we performed two unadjuvanted intranasal vaccination studies in the "gold-standard" preclinical Syrian hamster model. Hamsters received two vaccinations 28 days apart, and were then challenged 28 days post-boost with SARS-CoV-2. The initial study focused on assessing the immunogenicity of RBD+SpyCage, which indicated that vaccination of hamsters induced a non-neutralizing antibody response that enhanced viral clearance but did not prevent infection. In an expanded study, we demonstrated that covalent bonding of RBD to the scaffold was required to induce an antibody response. Consistent with the initial study, animals vaccinated with RBD+SpyCage more rapidly cleared SARS-CoV-2 from both the upper and lower respiratory tract. These findings demonstrate the intranasal SpyCage vaccine platform can induce protection against SARS-CoV-2 and, with additional modifications to improve immunogenicity, is a versatile platform for the development of intranasal vaccines targeting respiratory pathogens.

Chimeric antigen receptor signaling: Functional consequences and design implications.

Chimeric antigen receptor (CAR) T cell therapy has transformed the care of refractory B cell malignancies and holds tremendous promise for many aggressive tumors. Despite overwhelming scientific, clinical, and public interest in this rapidly expanding field, fundamental inquiries into CAR T cell mechanistic functioning are still in their infancy. Because CAR T cells are manufactured from donor T lymphocytes, and because CARs incorporate well-characterized T cell signaling components, it has largely been assumed that CARs signal analogously to canonical T cell receptors (TCRs). However, recent studies demonstrate that many aspects of CAR signaling are unique, distinct from endogenous TCR signaling, and potentially even distinct among various CAR constructs. Thus, rigorous and comprehensive proteomic investigations are required for rational engineering of improved CARs. Here, we review what is known about proximal CAR signaling in T cells, compare it to conventional TCR signaling, and outline unmet challenges to improving CAR T cell therapy.

MAP3K11 is a tumor suppressor targeted by the oncomiR miR-125b in early B cells.

MicroRNAs (miRNAs) are a class of small, non-coding RNAs that posttranscriptionally regulate gene expression and thereby control most, if not all, biological processes. Aberrant miRNA expression has been linked to a variety of human diseases including cancer, but the underlying molecular mechanism often remains unclear. Here we have screened a miRNA expression library in a growth factor-dependent mouse pre-B-cell system to identify miRNAs with oncogenic activity. We show that miR-125b is sufficient to render pre-B cells growth factor independent and demonstrate that continuous expression of miR-125b is necessary to keep these cells in a transformed state. Mechanistically, we find that the expression of miR-125b protects against apoptosis induced by growth factor withdrawal, and that it blocks the differentiation of pre-B to immature B cells. In consequence, miR-125b-transformed cells maintain expression of their pre-B-cell receptor that provides signals for continuous proliferation and survival even in the absence of growth factor. Employing microarray analysis, we identified numerous targets of miR-125b, but only reconstitution of MAP3K11, a critical regulator of mitogen- and stress-activated kinase signaling, interferes with the cellular fitness of the transformed cells. Together, this indicates that MAP3K11 might function as an important tumor suppressor neutralized by oncomiR-125b in B-cell leukemia.

Increased leukocyte survival and accelerated onset of lymphoma in the absence of MCL-1 S159-phosphorylation.

The antiapoptotic BCL-2 protein MCL-1, which opposes mitochondrial outer membrane permeabilization, was shown to have a crucial role in the survival of hematopoietic cells. We have previously shown that, upon loss of phosphatidylinositol 3-kinase signaling, S159 of MCL-1 is phosphorylated by glycogen synthase kinase-3 (GSK-3), earmarking MCL-1 for enhanced ubiquitylation and degradation. In this study, we introduced MCL-1(wt) or the phosphorylation-deficient mutant MCL-1(S159A) in mouse BM cells, followed by adoptive transfer to recipient mice. Mice expressing MCL-1(S159A) exhibited significantly elevated white blood cell and lymphocyte counts, whereas no effect was observed on the distribution of T and B lymphocyte subsets or the numbers of monocytes, red blood cells or platelets. Expression of MCL-1(S159A) in Eµ-Myc transgenic bone marrow significantly accelerated the onset of disease, and these mice displayed increased spleen weights compared with Eµ-Myc/MCL-1(wt) mice. Our data demonstrate that the absence of MCL-1 S159 phosphorylation provides a survival advantage for hematopoietic cells in vivo and facilitates oncogenesis.