Anle138b prevents PrP plaque accumulation in Tg(PrP-A116V) mice but does not mitigate clinical disease.

Anle138b is an anti-aggregating compound previously shown to delay the onset of scrapie, a transmissible prion disease, although its in vivo efficacy against other prion disease subtypes has not been fully assessed. TgGSS mice that model Gerstmann-Sträussler-Scheinker disease (GSS) via expression of mouse PrPA116V accumulate PrP amyloid plaques in their brains and develop progressive ataxia leading to death in ~160 days. When allowed to feed on food pellets containing anle138b from weaning until death, the brains of TgGSS mice displayed significant reductions in PrP plaque burden, insoluble PrP, and proteinase K-resistant PrPSc at end stage, compared with TgGSS mice allowed to feed on placebo food pellets. Despite these effects on biological markers of disease, there was no difference in the onset of symptoms or the age at death between the two treatment groups. In contrast, scrapie-inoculated wild-type mice treated with anle138b survived nearly twice as long (254 days) as scrapie-inoculated mice fed placebo (~136 days). They also displayed greater reductions in insoluble and PK-resistant PrPSc than TgGSS mice. Although these results support an anti-aggregating effect of anle138b, the discordance in clinical efficacy noted between the two prion disease models tested underscores the pathophysiological differences between them and highlights the need to consider differences in susceptibilities among prion subtypes when assessing potential therapies for prion diseases.

The integrated stress response in hypoxia-induced diffuse white matter injury.

Currently no treatments exist for preterm infants with diffuse white matter injury (DWMI) caused by hypoxia. Due to improved care of preterm neonates and increased recognition by advanced imaging techniques, the prevalence of DWMI is increasing. A better understanding of the pathophysiology of DWMI is therefore of critical importance. The integrated stress response (ISR), a conserved eukaryotic response to myriad stressors including hypoxia, may play a role in hypoxia-induced DWMI and may represent a novel target for much needed therapies. In this study we utilize in vitro and in vivo hypoxic models of DWMI to investigate whether the ISR is involved in DWMI. We demonstrate that hypoxia activates the ISR in primary mouse oligodendrocyte precursor cells (OPCs) in vitro and that genetically inhibiting the ISR in differentiating OPCs increases their susceptibility to in vitro hypoxia. We also show that a well-established in vivo mild chronic hypoxia (MCH) mouse model and a new severe acute hypoxia (SAH) mouse model of DWMI activates the initial step of the ISR. Nonetheless, genetic inhibition of the ISR has no detectable effect on either MCH or SAH-induced DWMI. In addition, we demonstrate that genetic enhancement of the ISR does not ameliorate MCH or SAH-induced DWMI. These studies suggest that while the ISR protects OPCs from hypoxia in vitro, it does not appear to play a major role in either MCH or SAH-induced DWMI and is therefore not a likely target for therapies aimed at improving neurological outcome in preterm neonates with hypoxia-induced DWMI.SIGNIFICANCE STATEMENTDiffuse white matter injury (DWMI) caused by hypoxia is a leading cause of neurological deficits following premature birth. An increased understanding of the pathogenesis of this disease is critical. The integrated stress response (ISR) is activated by hypoxia and protects oligodendrocyte lineage cells in other disease models. This has led to an interest in the potential role of the ISR in DWMI. Here we examine the ISR in hypoxia-induced DWMI and show that while the ISR protects oligodendrocyte lineage cells from hypoxia in vitro, genetic inhibition or enhancement of the ISR has no effect on hypoxia-induced DWMI in vivo suggesting that the ISR does not play a major role in, and is not a likely therapeutic target for, DWMI.

Injectable butyrate-prodrug micelles induce long-acting immune modulation and prevent autoimmune arthritis in mice.

Short chain fatty acid (SCFAs), such as butyrate, have shown promising therapeutic potential due to their immunomodulatory effects, particularly in maintaining immune homeostasis. However, the clinical application of SCFAs is limited by the need for frequent and high oral dosages. Rheumatoid arthritis (RA) is characterized by aberrant activation of peripheral T cells and myeloid cells. In this study, we aimed to deliver butyrate directly to the lymphatics using a polymeric micelle-based butyrate prodrug to induce long-lasting immunomodulatory effects. Notably, negatively charged micelles (Neg-ButM) demonstrated superior efficacy in targeting the lymphatics following subcutaneous (s.c.) administration and were retained in the draining lymph nodes, spleen, and liver for over one month. In the collagen antibody-induced arthritis (CAIA) mouse model of RA, only two s.c. injections of Neg-ButM successfully prevented disease onset and promoted tolerogenic phenotypes in T cells and myeloid cells, both locally and systemically. These results underscore the potential of this strategy in managing inflammatory autoimmune diseases by directly modulating immune responses via lymphatic delivery.

LDL-Binding IL-10 Reduces Vascular Inflammation in Atherosclerotic Mice.

Atherosclerosis is a chronic inflammatory disease associated with the accumulation of low-density lipoprotein (LDL) in arterial walls. Higher levels of the anti-inflammatory cytokine IL-10 in serum are correlated with reduced plaque burden. However, cytokine therapies have not translated well to the clinic, partially due to their rapid clearance and pleiotropic nature. Here, we engineered IL-10 to overcome these challenges by hitchhiking on LDL to atherosclerotic plaques. Specifically, we constructed fusion proteins in which one domain is IL-10 and the other is an antibody fragment (Fab) that binds to protein epitopes of LDL. In murine models of atherosclerosis, we show that systemically administered Fab-IL-10 constructs bind circulating LDL and traffic to atherosclerotic plaques. One such construct, 2D03-IL-10, significantly reduces aortic immune cell infiltration to levels comparable to healthy mice, whereas non-targeted IL-10 has no therapeutic effect. Mechanistically, we demonstrate that 2D03-IL-10 preferentially associates with foamy macrophages and reduces pro-inflammatory activation markers. This platform technology can be applied to a variety of therapeutics and shows promise as a potential targeted anti-inflammatory therapy in atherosclerosis.

Immune Potentiation of PLGA Controlled-Release Vaccines for Improved Immunological Outcomes.

With the emergence of SARS-CoV-2 and the continued emergence of new infectious diseases, there is a need to improve and expand current vaccine technology. Controlled-release subunit vaccines provide several benefits over current vaccines on the market, including the use of less antigen and fewer boost doses. Previously, our group reported molecules that alter NF-κB signaling improved the vaccine's performance and improved adjuvant-related tolerability. In this report, we test how these immune potentiators will influence responses when included as part of a controlled-release poly(lactic-co-glycolic) vaccine formulation. Murine in vivo studies revealed that SN50 and honokiol improved antibody levels at early vaccine time points. Microparticles with SN50 produced strong antibody levels over a longer period compared to microparticles without SN50. The same particles also increased T-cell activity. All of the immune potentiators tested further promoted Th2 humoral responses already exhibited by the control CpG OVA microparticle formulation. Overall, under controlled-release conditions, immune potentiators enhance the existing effects of controlled-release formulations, making it a potentially beneficial additive for controlled-release vaccine formulations.

Cysteine-binding adjuvant enhances survival and promotes immune function in a murine model of acute myeloid leukemia.

ABSTRACT: Therapeutic vaccination has long been a promising avenue for cancer immunotherapy but is often limited by tumor heterogeneity. The genetic and molecular diversity between patients often results in variation in the antigens present on cancer cell surfaces. As a result, recent research has focused on personalized cancer vaccines. Although promising, this strategy suffers from time-consuming production, high cost, inaccessibility, and targeting of a limited number of tumor antigens. Instead, we explore an antigen-agnostic polymeric in situ cancer vaccination platform for treating blood malignancies, in our model here with acute myeloid leukemia (AML). Rather than immunizing against specific antigens or targeting adjuvant to specific cell-surface markers, this platform leverages a characteristic metabolic and enzymatic dysregulation in cancer cells that produces an excess of free cysteine thiols on their surfaces. These thiols increase in abundance after treatment with cytotoxic agents such as cytarabine, the current standard of care in AML. The resulting free thiols can undergo efficient disulfide exchange with pyridyl disulfide (PDS) moieties on our construct and allow for in situ covalent attachment to cancer cell surfaces and debris. PDS-functionalized monomers are incorporated into a statistical copolymer with pendant mannose groups and TLR7 agonists to target covalently linked antigen and adjuvant to antigen-presenting cells in the liver and spleen after IV administration. There, the compound initiates an anticancer immune response, including T-cell activation and antibody generation, ultimately prolonging survival in cancer-bearing mice.

Glycosylation-modified antigens as a tolerance-inducing vaccine platform prevent anaphylaxis in a pre-clinical model of food allergy.

The only FDA-approved oral immunotherapy for a food allergy provides protection against accidental exposure to peanuts. However, this therapy often causes discomfort or side effects and requires long-term commitment. Better preventive and therapeutic solutions are urgently needed. We develop a tolerance-inducing vaccine technology that utilizes glycosylation-modified antigens to induce antigen-specific non-responsiveness. The glycosylation-modified antigens are administered intravenously (i.v.) or subcutaneously (s.c.) and traffic to the liver or lymph nodes, respectively, leading to preferential internalization by antigen-presenting cells, educating the immune system to respond in an innocuous way. In a mouse model of cow's milk allergy, treatment with glycosylation-modified ß-lactoglobulin (BLG) is effective in preventing the onset of allergy. In addition, s.c. administration of glycosylation-modified BLG shows superior safety and potential in treating existing allergies in combination with anti-CD20 co-therapy. This platform provides an antigen-specific immunomodulatory strategy to prevent and treat food allergies.

A serine-conjugated butyrate prodrug with high oral bioavailability suppresses autoimmune arthritis and neuroinflammation in mice.

Butyrate-a metabolite produced by commensal bacteria-has been extensively studied for its immunomodulatory effects on immune cells, including regulatory T cells, macrophages and dendritic cells. However, the development of butyrate as a drug has been hindered by butyrate's poor oral bioavailability, owing to its rapid metabolism in the gut, its low potency (hence, necessitating high dosing), and its foul smell and taste. Here we report that the oral bioavailability of butyrate can be increased by esterifying it to serine, an amino acid transporter that aids the escape of the resulting odourless and tasteless prodrug (O-butyryl-L-serine, which we named SerBut) from the gut, enhancing its systemic uptake. In mice with collagen-antibody-induced arthritis (a model of rheumatoid arthritis) and with experimental autoimmune encephalomyelitis (a model of multiple sclerosis), we show that SerBut substantially ameliorated disease severity, modulated key immune cell populations systemically and in disease-associated tissues, and reduced inflammatory responses without compromising the global immune response to vaccination. SerBut may become a promising therapeutic for autoimmune and inflammatory diseases.

Synthetically mannosylated antigens induce antigen-specific humoral tolerance and reduce anti-drug antibody responses to immunogenic biologics.

Immunogenic biologics trigger an anti-drug antibody (ADA) response in patients that reduces efficacy and increases adverse reactions. Our laboratory has shown that targeting protein antigen to the liver microenvironment can reduce antigen-specific T cell responses; herein, we present a strategy to increase delivery of otherwise immunogenic biologics to the liver via conjugation to a synthetic mannose polymer, p(Man). This delivery leads to reduced antigen-specific T follicular helper cell and B cell responses resulting in diminished ADA production, which is maintained throughout subsequent administrations of the native biologic. We find that p(Man)-antigen treatment impairs the ADA response against recombinant uricase, a highly immunogenic biologic, without a dependence on hapten immunodominance or control by T regulatory cells. We identify increased T cell receptor signaling and increased apoptosis and exhaustion in T cells as effects of p(Man)-antigen treatment via transcriptomic analyses. This modular platform may enhance tolerance to biologics, enabling long-term solutions for an ever-increasing healthcare problem.

Rapamycin delays disease onset and prevents PrP plaque deposition in a mouse model of Gerstmann-Sträussler-Scheinker disease.

Autophagy is a cell survival response to nutrient deprivation that delivers cellular components to lysosomes for digestion. In recent years, autophagy has also been shown to assist in the degradation of misfolded proteins linked to neurodegenerative disease (Ross and Poirier, 2004). In support of this, rapamycin, an autophagy inducer, improves the phenotype of several animal models of neurodegenerative disease. Our Tg(PrP-A116V) mice model Gerstmann-Sträussler-Scheinker disease (GSS), a genetic prion disease characterized by prominent ataxia and extracellular PrP amyloid plaque deposits in brain (Yang et al., 2009). To determine whether autophagy induction can mitigate the development of GSS, Tg(PrP-A116V) mice were chronically treated with 10 or 20 mg/kg rapamycin intraperitoneally thrice weekly, beginning at 6 weeks of age. We observed a dose-related delay in disease onset, a reduction in symptom severity, and an extension of survival in rapamycin-treated Tg(PrP-A116V) mice. Coincident with this response was an increase in the autophagy-specific marker LC3II, a reduction in insoluble PrP-A116V, and a near-complete absence of PrP amyloid plaques in the brain. An increase in glial cell apoptosis of unclear significance was also detected. These findings suggest autophagy induction enhances elimination of misfolded PrP before its accumulation in plaques. Because ataxia persisted in these mice despite the absence of plaque deposits, our findings also suggest that PrP plaque pathology, a histopathological marker for the diagnosis of GSS, is not essential for the GSS phenotype.

Suppression of tumor cell lactate-generating signaling pathways eradicates murine PTEN/p53-deficient aggressive-variant prostate cancer via macrophage phagocytosis.

Purpose: PTEN loss-of-function/PI3K pathway hyperactivation occurs in ∼50% of metastatic, castrate-resistant prostate cancer patients, resulting in poor therapeutic outcomes and resistance to immune checkpoint inhibitors across multiple malignancies. Our prior studies in prostate-specific PTEN/p53-deleted genetically engineered mice (Pb-Cre;PTEN fl/fl Trp53 fl/fl GEM) with aggressive-variant prostate cancer (AVPC) demonstrated feedback Wnt/ß-catenin signaling activation in 40% mice resistant to androgen deprivation therapy (ADT)/PI3K inhibitor (PI3Ki)/PD-1 antibody (aPD-1) combination, resulting in restoration of lactate cross-talk between tumor-cells and tumor-associated macrophages (TAM), histone lactylation (H3K18lac) and phagocytic suppression within TAM. Here, we targeted immunometabolic mechanism(s) of resistance to ADT/PI3Ki/aPD-1 combination, with the goal of durable tumor control in PTEN/p53-deficient PC. Experimental design: Pb-Cre;PTEN fl/fl Trp53 fl/fl GEM were treated with either ADT (degarelix), PI3Ki (copanlisib), aPD-1, MEK inhibitor (trametinib) or Porcupine inhibitor (LGK 974) as single agents or their combinations. MRI was used to monitor tumor kinetics and immune/proteomic profiling/ ex vivo co-culture mechanistic studies were performed on prostate tumors or established GEM-derived cell lines. Results: We tested whether Wnt/ß-catenin pathway inhibition with LGK 974 addition to degarelix/copanlisib/aPD-1 therapy enhances tumor control in GEM, and observed de novo resistance due to feedback activation of MEK signaling. Based on our observation that degarelix/aPD-1 treatment resulted in partial inhibition of MEK signaling, we substituted trametinib for degarelix/aPD-1 treatment, and observed a durable tumor growth control of PI3Ki/MEKi/PORCNi in 100% mice via H3K18lac suppression and complete TAM activation within TME. Conclusions: Abrogation of lactate-mediated cross-talk between cancer cells and TAM results in durable ADT-independent tumor control in PTEN/p53-deficient AVPC, and warrants further investigation in clinical trials. STATEMENT OF TRANSLATIONAL RELEVANCE: PTEN loss-of-function occurs in ∼50% of mCRPC patients, and associated with poor prognosis, and immune checkpoint inhibitor resistance across multiple malignancies. Our prior studies have demonstrated that ADT/PI3Ki/PD-1 triplet combination therapy controls PTEN/p53-deficient PC in 60% of mice via enhancement of TAM phagocytosis. Here, we discovered that resistance to ADT/PI3K/PD-1 therapy occurred via restoration of lactate production via feedback Wnt/MEK signaling following treatment with PI3Ki, resulting in inhibition of TAM phagocytosis. Critically, co-targeting of PI3K/MEK/Wnt signaling pathways using an intermittent dosing schedule of corresponding targeted agents resulted in complete tumor control and significantly prolonged survival without significant long-term toxicity. Collectively, our findings provide "proof-of-concept" that targeting lactate as a macrophage phagocytic checkpoint controls growth of murine PTEN/p53-deficient PC and warrant further investigation in AVPC clinical trials.

Suppression of Tumor Cell Lactate-generating Signaling Pathways Eradicates Murine PTEN/p53-deficient Aggressive-variant Prostate Cancer via Macrophage Phagocytosis.

PURPOSE: Phosphatase and tensin homolog (PTEN) loss-of-function/PI3K pathway hyperactivation is associated with poor therapeutic outcomes and immune checkpoint inhibitor resistance across multiple malignancies. Our prior studies in Pb-Cre;PTENfl/flTrp53fl/fl genetically engineered mice (GEM) with aggressive-variant prostate cancer (AVPC) demonstrated tumor growth control in 60% mice following androgen deprivation therapy/PI3K inhibitor (PI3Ki)/programmed cell death protein 1 (PD-1) antibody combination, via abrogating lactate cross-talk between cancer cells and tumor-associated macrophages (TAM), and suppression of histone lactylation (H3K18lac)/phagocytic activation within TAM. Here, we targeted immunometabolic mechanism(s) of PI3Ki resistance, with the goal of durable tumor control in AVPC. EXPERIMENTAL DESIGN: Pb-Cre;PTENfl/flTrp53fl/fl GEM were treated with PI3Ki (copanlisib), MEK inhibitor (trametinib) or Porcupine inhibitor (LGK'974) singly or their combinations. MRI was used to monitor tumor kinetics and immune/proteomic profiling/ex vivo coculture mechanistic studies were performed on GEM tumors or corresponding tumor-derived cell lines. RESULTS: Given our proteomic profiling showing persistent MEK signaling within tumors of PI3Ki-resistant GEM, we tested whether addition of trametinib to copanlisib enhances tumor control in GEM, and we observed 80% overall response rate via additive suppression of lactate within TME and H3K18lac within TAM, relative to copanlisib (37.5%) monotherapy. The 20% resistant mice demonstrated feedback Wnt/ß-catenin activation, resulting in restoration of lactate secretion by tumor cells and H3K18lac within TAM. Cotargeting Wnt/ß-catenin signaling with LGK'974 in combination with PI3Ki/MEKi, demonstrated durable tumor control in 100% mice via H3K18lac suppression and complete TAM activation. CONCLUSIONS: Abrogation of lactate-mediated cross-talk between cancer cells and TAM results in durable ADT-independent tumor control in PTEN/p53-deficient AVPC, and warrants further investigation in clinical trials.

Synthetically mannosylated antigens induce antigen-specific humoral tolerance and reduce anti-drug antibody responses to immunogenic biologics.

Immunogenic biologics trigger an anti-drug antibody (ADA) response in patients, which reduces efficacy and increases adverse reactions. Our laboratory has previously shown that targeting protein antigen to the liver microenvironment can reduce antigen-specific T cell responses; herein, we present a strategy to increase delivery of otherwise immunogenic biologics to the liver via conjugation to a synthetic mannose polymer (p(Man)). This delivery leads to reduced antigen-specific T follicular helper cell and B cell responses resulting in diminished ADA production, which is maintained throughout subsequent administrations of the native biologic. We found that p(Man)-antigen treatment impairs the ADA response against recombinant uricase, a highly immunogenic biologic, without a dependence on hapten immunodominance or control by Tregs. We identify increased TCR signaling and increased apoptosis and exhaustion in T cells as effects of p(Man)-antigen treatment via transcriptomic analyses. This modular platform may enhance tolerance to biologics, enabling long-term solutions for an ever-increasing healthcare problem.

Engineered IL-7 synergizes with IL-12 immunotherapy to prevent T cell exhaustion and promote memory without exacerbating toxicity.

Cancer immunotherapy is moving toward combination regimens with agents of complementary mechanisms of action to achieve more frequent and robust efficacy. However, compared with single-agent therapies, combination immunotherapies are associated with increased overall toxicity because the very same mechanisms also work in concert to enhance systemic inflammation and promote off-tumor toxicity. Therefore, rational design of combination regimens that achieve improved antitumor control without exacerbated toxicity is a main objective in combination immunotherapy. Here, we show that the combination of engineered, tumor matrix-binding interleukin-7 (IL-7) and IL-12 achieves remarkable anticancer effects by activating complementary pathways without inducing any additive immunotoxicity. Mechanistically, engineered IL-12 provided effector properties to T cells, while IL-7 prevented their exhaustion and boosted memory formation as assessed by tumor rechallenge experiments. The dual combination also rendered checkpoint inhibitor (CPI)-resistant genetically engineered melanoma model responsive to CPI. Thus, our approach provides a framework of evaluation of rationally designed combinations in immuno-oncology and yields a promising therapy.

Reversal of Lactate and PD-1-mediated Macrophage Immunosuppression Controls Growth of PTEN/p53-deficient Prostate Cancer.

PURPOSE: Phosphatase and tensin homolog (PTEN) loss of function occurs in approximately 50% of patients with metastatic castrate-resistant prostate cancer (mCRPC), and is associated with poor prognosis and responsiveness to standard-of-care therapies and immune checkpoint inhibitors. While PTEN loss of function hyperactivates PI3K signaling, combinatorial PI3K/AKT pathway and androgen deprivation therapy (ADT) has demonstrated limited anticancer efficacy in clinical trials. Here, we aimed to elucidate mechanism(s) of resistance to ADT/PI3K-AKT axis blockade, and to develop rational combinatorial strategies to effectively treat this molecular subset of mCRPC. EXPERIMENTAL DESIGN: Prostate-specific PTEN/p53-deficient genetically engineered mice (GEM) with established 150-200 mm3 tumors, as assessed by ultrasound, were treated with either ADT (degarelix), PI3K inhibitor (copanlisib), or anti-PD-1 antibody (aPD-1), as single agents or their combinations, and tumors were monitored by MRI and harvested for immune, transcriptomic, and proteomic profiling, or ex vivo co-culture studies. Single-cell RNA sequencing on human mCRPC samples was performed using 10X Genomics platform. RESULTS: Coclinical trials in PTEN/p53-deficient GEM revealed that recruitment of PD-1-expressing tumor-associated macrophages (TAM) thwarts ADT/PI3Ki combination-induced tumor control. The addition of aPD-1 to ADT/PI3Ki combination led to TAM-dependent approximately 3-fold increase in anticancer responses. Mechanistically, decreased lactate production from PI3Ki-treated tumor cells suppressed histone lactylation within TAM, resulting in their anticancer phagocytic activation, which was augmented by ADT/aPD-1 treatment and abrogated by feedback activation of Wnt/ß-catenin pathway. Single-cell RNA-sequencing analysis in mCRPC patient biopsy samples revealed a direct correlation between high glycolytic activity and TAM phagocytosis suppression. CONCLUSIONS: Immunometabolic strategies that reverse lactate and PD-1-mediated TAM immunosuppression, in combination with ADT, warrant further investigation in patients with PTEN-deficient mCRPC.

Synthetically glycosylated antigens for the antigen-specific suppression of established immune responses.

Inducing antigen-specific tolerance during an established immune response typically requires non-specific immunosuppressive signalling molecules. Hence, standard treatments for autoimmunity trigger global immunosuppression. Here we show that established antigen-specific responses in effector T cells and memory T cells can be suppressed by a polymer glycosylated with N-acetylgalactosamine (pGal) and conjugated to the antigen via a self-immolative linker that allows for the dissociation of the antigen on endocytosis and its presentation in the immunoregulatory environment. We show that pGal-antigen therapy induces antigen-specific tolerance in a mouse model of experimental autoimmune encephalomyelitis (with programmed cell-death-1 and the co-inhibitory ligand CD276 driving the tolerogenic responses), as well as the suppression of antigen-specific responses to vaccination against a DNA-based simian immunodeficiency virus in non-human primates. Our findings show that pGal-antigen therapy invokes mechanisms of immune tolerance to resolve antigen-specific inflammatory T-cell responses and suggest that the therapy may be applicable across autoimmune diseases.

Therapeutic use of α2-antiplasmin as an antifibrinolytic and hemostatic agent in surgery and regenerative medicine.

The biomaterial fibrin is widely used as a clinical tissue sealant in surgery. In preclinical research, fibrin is also extensively studied as a carrier material for growth factor delivery. In these applications, premature fibrin degradation leads to recurrent bleeding, tissue dehiscence and limited regenerative efficacy. Therefore, fibrinolysis inhibitors have been added to clinical fibrin formulations, for example the bovine-derived serine protease inhibitor aprotinin. Aprotinin is additionally used as a hemostatic agent to prevent excessive bleeding during surgery, in this case protecting endogenous fibrin clots. Nevertheless, aprotinin use has been associated with serious safety issues. Here, we explore the use the human physiological fibrinolysis inhibitor α2-antiplasmin (α2PI) as a substitute for aprotinin. We evaluate the efficacy of α2PI in the three main applications of aprotinin. We first showed that recombinant α2PI can successfully prolong the durability of fibrin biomaterials as compared to aprotinin in a model of subcutaneous implantation in mice mimicking application as a tissue sealant. We then used α2PI to enhance the delivery of engineered vascular endothelial growth factor (VEGF)-A and platelet-derived growth factor (PDGF)-BB in fibrin in promoting diabetic wound healing, which lead to improved wound closure, granulation tissue formation and angiogenesis. Lastly, we demonstrated that α2PI can be as effective as aprotinin as an intravenous hemostatic agent to prevent blood loss, using a tail-vein bleeding model in mice. Therefore, we believe that engineering fibrin biomaterials or endogenous fibrin with α2PI can have a strong impact in surgery and regenerative medicine by providing a competitive substitute to aprotinin that is of human origin.

Temporal Control of Trained Immunity via Encapsulated Release of ß-Glucan Improves Therapeutic Applications.

Emerging diseases require generating new vaccines, which can often be time consuming. An alternate method to boost host defense is by inducing nonspecific innate immune memory, called trained immunity, to develop novel prophylactics. Many molecules, most notably ß-glucan, induce trained immunity, but their effects are often short-lived and uncontrolled. This lack of temporal control limits both the therapeutic ability of training and provides fundamental questions about its nature. To achieve temporal control of trained immunity, controlled release nanoparticles encapsulating only 3.5% of the standard dose of ß-glucan to attain sustained release over a month are engineered. Nanoparticle-trained mice exhibit prolonged training effects and improve resistance to a B16F10 tumor challenge compared to mice that receive an equivalent amount of free ß-glucan. The duration of trained immunity is further fine tuned by synthesizing nanoparticles composed of different molecular weights to modulate the release kinetics. These results demonstrate that dosing and temporal control can substantially alter the trained response to unanticipated levels. As such, this approach using sustained release platforms might lead to a novel prophylactic strategy for improved disease resistance against a wide variety of diseases.

Masking the immunotoxicity of interleukin-12 by fusing it with a domain of its receptor via a tumour-protease-cleavable linker.

Immune-checkpoint inhibitors have shown modest efficacy against immunologically 'cold' tumours. Interleukin-12 (IL-12)-a cytokine that promotes the recruitment of immune cells into tumours as well as immune cell activation, also in cold tumours-can cause severe immune-related adverse events in patients. Here, by exploiting the preferential overexpression of proteases in tumours, we show that fusing a domain of the IL-12 receptor to IL-12 via a linker cleavable by tumour-associated proteases largely restricts the pro-inflammatory effects of IL-12 to tumour sites. In mouse models of subcutaneous adenocarcinoma and orthotopic melanoma, masked IL-12 delivered intravenously did not cause systemic IL-12 signalling and eliminated systemic immune-related adverse events, led to potent therapeutic effects via the remodelling of the immune-suppressive microenvironment, and rendered cold tumours responsive to immune-checkpoint inhibition. We also show that masked IL-12 is activated in tumour lysates from patients. Protease-sensitive masking of potent yet toxic cytokines may facilitate their clinical translation.

Lymph Node-Targeted Synthetically Glycosylated Antigen Leads to Antigen-Specific Immunological Tolerance.

Inverse vaccines that tolerogenically target antigens to antigen-presenting cells (APCs) offer promise in prevention of immunity to allergens and protein drugs and treatment of autoimmunity. We have previously shown that targeting hepatic APCs through intravenous injection of synthetically glycosylated antigen leads to effective induction of antigen-specific immunological tolerance. Here, we demonstrate that targeting these glycoconjugates to lymph node (LN) APCs under homeostatic conditions leads to local and increased accumulation in the LNs compared to unmodified antigen and induces a tolerogenic state both locally and systemically. Subcutaneous administration directs the polymeric glycoconjugate to the draining LN, where the glycoconjugated antigen generates robust antigen-specific CD4+ and CD8+ T cell tolerance and hypo-responsiveness to antigenic challenge via a number of mechanisms, including clonal deletion, anergy of activated T cells, and expansion of regulatory T cells. Lag-3 up-regulation on CD4+ and CD8+ T cells represents an essential mechanism of suppression. Additionally, presentation of antigen released from the glycoconjugate to naïve T cells is mediated mainly by LN-resident CD8+ and CD11b+ dendritic cells. Thus, here we demonstrate that antigen targeting via synthetic glycosylation to impart affinity for APC scavenger receptors generates tolerance when LN dendritic cells are the cellular target.