Synthetic intrinsically disordered protein fusion tags that enhance protein solubility.

We report the de novo design of small (<20 kDa) and highly soluble synthetic intrinsically disordered proteins (SynIDPs) that confer solubility to a fusion partner with minimal effect on the activity of the fused protein. To identify highly soluble SynIDPs, we create a pooled gene-library utilizing a one-pot gene synthesis technology to create a large library of repetitive genes that encode SynIDPs. We identify three small (<20 kDa) and highly soluble SynIDPs from this gene library that lack secondary structure and have high solvation. Recombinant fusion of these SynIDPs to three known inclusion body forming proteins rescue their soluble expression and do not impede the activity of the fusion partner, thereby eliminating the need for removal of the SynIDP tag. These findings highlight the utility of SynIDPs as solubility tags, as they promote the soluble expression of proteins in E. coli and are small, unstructured proteins that minimally interfere with the biological activity of the fused protein.

Brachytherapy via a depot of biopolymer-bound 131I synergizes with nanoparticle paclitaxel in therapy-resistant pancreatic tumours.

Locally advanced pancreatic tumours are highly resistant to conventional radiochemotherapy. Here we show that such resistance can be surmounted by an injectable depot of thermally responsive elastin-like polypeptide (ELP) conjugated with iodine-131 radionuclides (131I-ELP) when combined with systemically delivered nanoparticle albumin-bound paclitaxel. This combination therapy induced complete tumour regressions in diverse subcutaneous and orthotopic mouse models of locoregional pancreatic tumours. 131I-ELP brachytherapy was effective independently of the paclitaxel formulation and dose, but external beam radiotherapy (EBRT) only achieved tumour-growth inhibition when co-administered with nanoparticle paclitaxel. Histological analyses revealed that 131I-ELP brachytherapy led to changes in the expression of intercellular collagen and junctional proteins within the tumour microenvironment. These changes, which differed from those of EBRT-treated tumours, correlated with the improved delivery and accumulation of paclitaxel nanoparticles within the tumour. Our findings support the further translational development of 131I-ELP depots for the synergistic treatment of localized pancreatic cancer.

Polyethylene Glycol-Like Brush Polymer Conjugate of a Protein Drug Does Not Induce an Antipolymer Immune Response and Has Enhanced Pharmacokinetics than Its Polyethylene Glycol Counterpart.

Protein therapeutics, except for antibodies, have a short plasma half-life and poor stability in circulation. Covalent coupling of polyethylene glycol (PEG) to protein drugs addresses this limitation. However, unlike previously thought, PEG is immunogenic. In addition to induced PEG antibodies, ≈70% of the US population has pre-existing anti-PEG antibodies. Both induced and preexisting anti-PEG antibodies result in accelerated drug clearance, reduced clinical efficacy, and severe hypersensitivity reactions that have limited the clinical utility of uricase, an enzyme drug for treatment for refractory gout that is decorated with a PEG corona. Here, the authors synthesize a poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) conjugate of uricase that decorates the protein with multiple polymer chains to create a corona to solve these problems. The resulting uricase-POEGMA is well-defined, has high bioactivity, and outperforms its PEG counterparts in its pharmacokinetics (PK). Furthermore, the conjugate does not induce anti-POEGMA antibodies and is not recognized by anti-PEG antibodies. These findings suggest that POEGMA conjugation may provide a solution to the immunogenicity and antigenicity limitations of PEG while improving upon its PK benefits. These results transcend uricase and can be applied to other PEGylated therapeutics and the broader class of biologics with suboptimal PK.

Intratumoral delivery of brachytherapy and immunotherapy by a thermally triggered polypeptide depot.

Biomaterial-based approaches for a combination of radiotherapy and immunotherapy can improve outcomes in metastatic cancer through local delivery of both therapeutic modalities to the primary tumor to control local tumor growth and distant metastases. This study describes an injectable depot for sustained intratumoral (i.t.) delivery of an iodine-131 (131I) radionuclide and a CpG oligodeoxynucleotide immunostimulant, driven by the thermally sensitive phase transition behavior of elastin-like polypeptides (ELPs). We synthesized and characterized an ELP with an oligolysine tail (ELP-K12) that forms an electrostatic complex with CpG for delivery from an ELP depot and evaluated the ability of the complex to enhance local and systemic tumor control as a monotherapy and in combination with 131I-ELP brachytherapy. I.t delivery of CpG from an ELP-K12 depot dramatically prolongs i.t. retention to more than 21 days as compared to soluble CpG that is only retained within the tumor for <24 h. ELP-K12 also enhances CpG delivery by increasing cellular uptake of CpG to generate greater toll-like receptor 9 (TLR9) activation than CpG alone. I.t. treatment with an ELP-K12/CpG depot slows primary tumor growth and reduces lung metastases in a poorly immunogenic 4 T1 syngeneic breast cancer model whereas i.t treatment of CpG alone has no significant effect on primary tumor growth or metastases. Notably, a combination of 131I-ELP brachytherapy and ELP-K12/CpG delivered i.t. inhibited 4 T1 tumor growth and strongly decreased the development of lung metastases, leading to a synergistic improvement in mouse survival. These preclinical results demonstrate that injectable ELP depots may provide a useful approach for the delivery of combination radio- and immuno-therapy to treat metastatic disease.

Multiplexed, quantitative serological profiling of COVID-19 from blood by a point-of-care test.

Highly sensitive, specific, and point-of-care (POC) serological assays are an essential tool to manage coronavirus disease 2019 (COVID-19). Here, we report on a microfluidic POC test that can profile the antibody response against multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens-spike S1 (S1), nucleocapsid (N), and the receptor binding domain (RBD)-simultaneously from 60 µl of blood, plasma, or serum. We assessed the levels of antibodies in plasma samples from 31 individuals (with longitudinal sampling) with severe COVID-19, 41 healthy individuals, and 18 individuals with seasonal coronavirus infections. This POC assay achieved high sensitivity and specificity, tracked seroconversion, and showed good concordance with a live virus microneutralization assay. We can also detect a prognostic biomarker of severity, IP-10 (interferon-γ-induced protein 10), on the same chip. Because our test requires minimal user intervention and is read by a handheld detector, it can be globally deployed to combat COVID-19.

Ultrasensitive point-of-care immunoassay for secreted glycoprotein detects Ebola infection earlier than PCR.

Ebola virus (EBOV) hemorrhagic fever outbreaks have been challenging to deter due to the lack of health care infrastructure in disease-endemic countries and a corresponding inability to diagnose and contain the disease at an early stage. EBOV vaccines and therapies have improved disease outcomes, but the advent of an affordable, easily accessed, mass-produced rapid diagnostic test (RDT) that matches the performance of more resource-intensive polymerase chain reaction (PCR) assays would be invaluable in containing future outbreaks. Here, we developed and demonstrated the performance of a new ultrasensitive point-of-care immunoassay, the EBOV D4 assay, which targets the secreted glycoprotein of EBOV. The EBOV D4 assay is 1000-fold more sensitive than the U.S. Food and Drug Administration-approved RDTs and detected EBOV infection earlier than PCR in a standard nonhuman primate model. The EBOV D4 assay is suitable for low-resource settings and may facilitate earlier detection, containment, and treatment during outbreaks of the disease.

Multiplexed, quantitative serological profiling of COVID-19 from a drop of blood by a point-of-care test.

Highly sensitive, specific, and point-of-care (POC) serological assays are an essential tool to manage the COVID-19 pandemic. Here, we report on a microfluidic, multiplexed POC test that can profile the antibody response against multiple SARS-CoV-2 antigens - Spike S1 (S1), Nucleocapsid (N), and the receptor binding domain (RBD) - simultaneously from a 60 microliter drop of blood, plasma, or serum. We assessed the levels of anti-SARS-CoV-2 antibodies in plasma samples from 19 individuals (at multiple time points) with COVID-19 that required admission to the intensive care unit and from 10 healthy individuals. This POC assay shows good concordance with a live virus microneutralization assay, achieved high sensitivity (100%) and specificity (100%), and successfully tracked the longitudinal evolution of the antibody response in infected individuals. We also demonstrated that we can detect a chemokine, IP-10, on the same chip, which may provide prognostic insight into patient outcomes. Because our test requires minimal user intervention and is read by a handheld detector, it can be globally deployed in the fight against COVID-19 by democratizing access to laboratory quality tests.

Complex microparticle architectures from stimuli-responsive intrinsically disordered proteins.

The controllable production of microparticles with complex geometries is useful for a variety of applications in materials science and bioengineering. The formation of intricate microarchitectures typically requires sophisticated fabrication techniques such as flow lithography or multiple-emulsion microfluidics. By harnessing the molecular interactions of a set of artificial intrinsically disordered proteins (IDPs), we have created complex microparticle geometries, including porous particles, core-shell and hollow shell structures, and a unique 'fruits-on-a-vine' arrangement, by exploiting the metastable region of the phase diagram of thermally responsive IDPs within microdroplets. Through multi-site unnatural amino acid (UAA) incorporation, these protein microparticles can also be photo-crosslinked and stably extracted to an all-aqueous environment. This work expands the functional utility of artificial IDPs as well as the available microarchitectures of this class of biocompatible IDPs, with potential applications in drug delivery and tissue engineering.