Peptide-scFv antigen recognition domains effectively confer CAR T cell multiantigen specificity

The emergence of immune escape is a significant roadblock to developing effective chimeric antigen receptor (CAR) T cell therapies against hematological malignancies, including acute myeloid leukemia (AML). Here, we demonstrate feasibility of targeting two antigens simultaneously by combining a GRP78-specific peptide antigen recognition domain with a CD123-specific scFv to generate a peptide-scFv bispecific antigen recognition domain (78.123). To achieve this, we test linkers with varying length and flexibility and perform immunophenotypic and functional characterization. We demonstrate that bispecific CAR T cells successfully recognize and kill tumor cells that express GRP78, CD123, or both antigens and have improved antitumor activity compared to their monospecific counterparts when both antigens are expressed. Protein structure prediction suggests that linker length and compactness influence the functionality of the generated bispecific CARs. Thus, we present a bispecific CAR design strategy to prevent immune escape in AML that can be extended to other peptide-scFv combinations.

GRP78-CAR T cell effector function against solid and brain tumors is controlled by GRP78 expression on T cells

Lack of targetable antigens is a key limitation for developing successful T cell-based immunotherapies. Members of the unfolded protein response (UPR) represent ideal immunotherapy targets because the UPR regulates the ability of cancer cells to resist cell death, sustain proliferation, and metastasize. Glucose-regulated protein 78 (GRP78) is a key UPR regulator that is overexpressed and translocated to the cell surface of a wide variety of cancers in response to elevated endoplasmic reticulum (ER) stress. We show that GRP78 is highly expressed on the cell surface of multiple solid and brain tumors, making cell surface GRP78 a promising chimeric antigen receptor (CAR) T cell target. We demonstrate that GRP78-CAR T cells can recognize and kill GRP78+ brain and solid tumors in vitro and in vivo. Additionally, our findings demonstrate that GRP78 is upregulated on CAR T cells upon T cell activation; however, this expression is tumor-cell-line specific and results in heterogeneous GRP78-CAR T cell therapeutic response.

Murine foetal liver supports limited detectable expansion of life-long haematopoietic progenitors

Current dogma asserts that the foetal liver (FL) is an expansion niche for recently specified haematopoietic stem cells (HSCs) during ontogeny. Indeed, between embryonic day of development (E)12.5 and E14.5, the number of transplantable HSCs in the murine FL expands from 50 to about 1,000. Here we used a non-invasive, multi-colour lineage tracing strategy to interrogate the embryonic expansion of murine haematopoietic progenitors destined to contribute to the adult HSC pool. Our data show that this pool of fated progenitors expands only two-fold during FL ontogeny. Although Histone2B-GFP retention in vivo experiments confirmed substantial proliferation of phenotypic FL-HSC between E12.5 and E14.5, paired-daughter cell assays revealed that many mid-gestation phenotypic FL-HSCs are biased to differentiate, rather than self-renew, relative to phenotypic neonatal and adult bone marrow HSCs. In total, these data support a model in which the FL-HSC pool fated to contribute to adult blood expands only modestly during ontogeny.

Physiological levels of thrombospondin-1 decrease NO-dependent vasodilation in coronary microvessels from aged rats

Aging and cardiovascular disease are associated with the loss of nitric oxide (NO) signaling and a decline in the ability to increase coronary blood flow reserve (CFR). Thrombospondin-1 (Thbs-1), through binding of CD47, has been shown to limit NO-dependent vasodilation in peripheral vascular beds via formation of superoxide (O2 (-)). The present study tests the hypothesis that, similar to the peripheral vasculature, blocking CD47 will improve NO-mediated vasoreactivity in coronary arterioles from aged individuals, resulting in improved CFR. Isolated coronary arterioles from young (4 mo) or old (24 mo) female Fischer 344 rats were challenged with the NO donor, DEA-NONO-ate (1 × 10(-7) to 1 × 10(-4) M), and vessel relaxation and O2 (-) production was measured before and after Thbs-1, αCD47, and/or Tempol and catalase exposure. In vivo CFR was determined in anesthetized rats (1-3% isoflurane-balance O2) via injected microspheres following control IgG or αCD47 treatment (45 min). Isolated coronary arterioles from young and old rats relax similarly to exogenous NO, but addition of 2.2 nM Thbs-1 inhibited NO-mediated vasodilation by 24% in old rats, whereas young vessels were unaffected. Thbs-1 increased O2 (-) production in coronary arterioles from rats of both ages, but this was exaggerated in old rats. The addition of CD47 blocking antibody completely restored NO-dependent vasodilation in isolated arterioles from aged rats and attenuated O2 (-) production. Furthermore, αCD47 treatment increased CFR from 9.6 ± 9.3 (IgG) to 84.0 ± 23% in the left ventricle in intact, aged animals. These findings suggest that the influence of Thbs-1 and CD47 on coronary perfusion increases with aging and may be therapeutically targeted to reverse coronary microvascular dysfunction.

Regulation of integrin endocytic recycling and chemotactic cell migration by syntaxin 6 and VAMP3 interaction

Integrins are the primary receptors of cells adhering to the extracellular matrix, and play key roles in various cellular processes including migration, proliferation and survival. The expression and distribution of integrins at the cell surface is controlled by endocytosis and recycling. The present study examines the function of syntaxin 6 (STX6), a t-SNARE located in the trans-Golgi network, in integrin trafficking. STX6 is overexpressed in many types of human cancer. We show that depletion of STX6 inhibits chemotactic cell migration and the delivery of the laminin receptor α3β1 integrin to the cell surface, whereas STX6 overexpression stimulates chemotactic cell migration, integrin delivery, and integrin-initiated activation of focal adhesion kinase. These data indicate that STX6 plays a rate-limiting role in cell migration and integrin trafficking. In STX6-depleted cells, α3β1 integrin is accumulated in recycling endosomes that contain the v-SNARE VAMP3. Importantly, we show that STX6 and VAMP3 form a v-/t-SNARE complex, VAMP3 is required in α3β1 integrin delivery to the cell surface, and endocytosed α3β1 integrin traffics to both VAMP3 and STX6 compartments. Collectively, our data suggest a new integrin trafficking pathway in which endocytosed integrins are transported from VAMP3-containing recycling endosomes to STX6-containing trans-Golgi network before being recycled to the plasma membrane.

Workers' compensation for nonmalignant asbestos-related lung disease

Workers' compensation claims filed for occupational illness are generally more complicated to resolve than are injury claims, and they may therefore face higher likelihood of rejection. This study analyzed outcomes and predictive factors for claims filed from one clinic in Washington State between 1982 and 1986 by 157 male patients for nonmalignant asbestos-related lung disease. Among 50 federal Longshore claims, 46 (92%) were unresolved or could not be located by claims administrators. In contrast, 118 (89%) of State Fund claims had been resolved, with 48% accepted without consistent relationship to disease severity. Claims filed under both jurisdictions showed a twofold greater risk of rejection by the State Fund (relative risk, RR = 2.0; 95% confidence interval, 95% CI = 1.3-3.2). State Fund claims filed for nonwhite patients were rejected more often than those of white patients, although the association was explained at least partially by jurisdictional overlap (adjusted RR = 1.5; 95% CI = 1.05-2.1). This study indicates a need to scrutinize the handling of occupational disease claims by the federal Longshore system and to consider the adverse influences of jurisdictional conflicts and possible race-associated factors on compensation of occupational illness.