Faculty Bibliography

One of the greatest obstacles to achieving implantable electronics with long-term functionality and minimized inflammatory reactions is the immune-mediated foreign-body response (FBR). Recently, semiconducting polymers with mixed electron-ion conductivity have been demonstrated as promising candidates to achieve direct electrical interfacing on bio-tissues. However, there is limited understanding of their immune compatibility in vivo, and strategies for minimizing the FBR through molecular design remain underexplored. Here we introduce a set of molecular design strategies for enhancing the immune compatibility of semiconducting polymers. Specifically, we show that selenophene, when incorporated in the backbone, can mitigate the FBR by suppressing macrophage activation. In addition, side-chain functionalization with immunomodulatory groups decreases the FBR further by downregulating the expression of inflammatory biomarkers. Together, our synthesized polymers achieve suppression of the FBR by as much as 68% (as indicated by the collagen density). In the meantime, these immune-compatible designs still provide a high charge-carrier mobility of around 1 cm² V^-1 s^-1. We anticipate that such immune-compatible design principles can be translated to a variety of conjugated polymers to suppress the FBR for implantable applications.

Butyrate, a microbiome-derived short-chain fatty acid with pleiotropic effects on inflammation and metabolism, has been shown to significantly reduce atherosclerotic lesions, rectify routine metabolic parameters such as low-density lipoprotein cholesterol (LDL-C), and reduce systemic inflammation in murine models of atherosclerosis. However, its foul odor, rapid metabolism in the gut and thus low systemic bioavailability limit its therapeutic effectiveness. Our laboratory has engineered an ester-linked L-serine conjugate to butyrate (SerBut) to mask its taste and odor and to coopt amino acid transporters in the gut to increase its systemic bioavailability, as determined by tissue measurements of free butyrate, produced by hydrolysis of SerBut. In an apolipoprotein E-knockout (ApoE)-/- mouse model of atherosclerosis, SerBut reduced systemic LDL-C, proinflammatory cytokines, and circulating neutrophils. SerBut enhanced inhibition of plaque progression and reduced monocyte accumulation in the aorta compared with sodium butyrate. SerBut suppressed liver injury biomarkers alanine transaminase and aspartate aminotransferase and suppressed steatosis in the liver. SerBut overcomes several barriers to the translation of butyrate and shows superior promise in slowing atherosclerosis and liver injury compared with equidosed sodium butyrate.

Versatile technologies that can deliver both RNA and protein payloads could streamline development, simplify manufacturing and expand the capabilities of combination therapies. Here we demonstrate an efficient approach to forming ca. 100 nm polymer vesicles (polymersomes) capable of rapid self-assembly without organic solvents, avoiding the need for post-encapsulation purification. Block copolymers are designed with a lower critical solution temperature that renders them soluble in aqueous medium under standard refrigeration, but they spontaneously assemble at room temperature into large batches of nanoparticles with predictable size and morphology. The nanomaterials are designed with charged and biofunctional moieties to drive payload affinity and in vivo targeting, while both siRNA and proteins can be encapsulated during warming at >75% loading efficiencies. Formulations can be stored in a dry state for greater hydrolytic stability under standard refrigeration and can be diluted directly from the vial, bypassing the need for purification required for high scalability. We use our system for in vivo delivery in protein subunit vaccination, immune tolerance induction and siRNA interference therapy in cancer.

Interleukin-33 (IL-33) is an immunoregulatory cytokine that moderately suppresses experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS). However, poor pharmacokinetics and toxicity hinder its clinical translation. To address these limitations, we develop an activity-attenuated IL-33 by recombinant fusion to serum albumin (SA). SA-IL-33 exhibits reduced toxicity and prolonged residence in the secondary lymphoid organs (SLOs), sites of T cell priming in autoimmunity, compared to wild-type (WT) IL-33. Prophylactic SA-IL-33 administration prevents EAE with superior efficacy to WT IL-33 and comparable efficacy to fingolimod (FTY720), a Food and Drug Administration (FDA)-approved MS drug. Therapeutic SA-IL-33 treatment also reduces disease severity in both chronic and relapsing-remitting EAE. SA-IL-33 modulates immunity in EAE by suppressing CD45⁺ cell infiltration (including myelin-reactive T helper 17 [T_H17] cells) in the spinal cord, while expanding type 2 immune cells (including type 2 innate lymphoid cells [ILC2s], ST2⁺ regulatory T cells [Tregs], T helper 2 [T_H2] cells, and M2-polarized macrophages) in the SLOs. These findings suggest that SA-IL-33 is a promising therapeutic for neuroinflammatory diseases.

Fibrosis is involved in 45% of deaths in the United States, and no treatment exists to reverse progression of the disease. To find novel targets for fibrosis therapeutics, we developed a model for the differentiation of monocytes to myofibroblasts that allowed us to screen for proteins involved in myofibroblast differentiation. Inhibition of a novel protein target generated by our model, talin2, reduces myofibroblast-specific morphology, α-smooth muscle actin content, and collagen I content and lowers the pro-fibrotic secretome of myofibroblasts. We find that knockdown of talin2 de-differentiates myofibroblasts and reverses bleomycin-induced lung fibrosis in mice, and further that Tln2^-/- mice are resistant to bleomycin-induced lung fibrosis and resistant to unilateral ureteral obstruction-induced kidney fibrosis. Talin2 inhibition is thus a potential treatment for reversing lung and kidney fibroses.

Current asthma treatments manage disease symptoms but fail to address the underlying cause of allergic disease. Allergen immunotherapy holds the promise for durable disease control by establishing allergen-specific tolerance through repeated introduction of native allergens; however, its efficacy can be limited by long interventions, reactions upon administration, and poor patient compliance. Here, we developed a rapid, safe, and effective liver-targeted allergen immunotherapy (LIT) to provide long-term disease control. We developed LIT tolerogens from native respiratory allergens, which induced antigen-specific regulatory T (T_reg) cells in vivo with only two interventions. Synthetic mannosylation of native allergens prevented antibody-mediated recognition and subsequent life-threatening anaphylaxis upon administration. Protein engineering prevented sensitization events that occurred because of the proteolytic activity of native respiratory allergens, which limit the effectiveness of allergen immunotherapy. In preclinical models of allergic asthma, LIT ameliorated clinical, pathological, and serological features, and protection was dependent on antigen-specific T_reg cells. In sensitized mice, LIT provided a year-long control of allergic asthma symptoms in the absence of additional intervention. Last, LIT induced antigen-specific T_reg cells against Der p 1, a major protein in the clinically relevant house dust mite (HDM) respiratory allergen. In mice with established HDM allergy, LIT was well tolerated and provided allergic symptom relief. Together, our data provide a proof of concept that LIT with synthetically mannosylated tolerogens provides a rapid, safe, and effective approach to allergen immunotherapy and holds promise for durable control of allergic asthma.

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.

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.

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.