A novel engineered CCL20 locked dimer (CCL20LD) is nearly identical to the naturally occurring chemokine CCL20 but blocks CCR6-mediated chemotaxis and offers a new approach to treat the diseases of psoriasis and psoriatic arthritis. Methods for quantifying CCL20LD serum levels are needed to assess pharmacokinetics parameters and evaluate drug delivery, metabolism, and toxicity. Existing ELISA kits fail to discriminate between CCL20LD and the natural chemokine, CCL20WT (the wild type monomer). Herein, we tested several available CCL20 monoclonal antibodies to be able to identify one clone that can be used both as a capture and a detection antibody (with biotin-labeling) to specifically detect CCL20LD with high specificity. After validation using recombinant proteins, the CCL20LD-selective ELISA was used to analyze blood samples from CCL20LD treated mice, demonstrating the utility of this novel assay for preclinical development of a biopharmaceutical lead compound for psoriatic disease.

With its new lab in West Allis, a local startup can now produce larger quantities of its patented molecule that shows early potential for treating autoimmune conditions like psoriasis and other inflammatory diseases. 
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The milestone is a step on the years-long path to commercialization for preclinical biopharma startup XLock Biosciences LLC, which began with a discovery in Medical College of Wisconsin biochemistry professor Brian Volkman's lab. 

Volkman and a group of founders including other MCW researchers provided seed funding and officially co-founded the company in 2020.

The new XLock Biosciences lab is at 662 S. 94th Place in West Allis. Volkman and a partner purchased the roughly 3,000-square-foot building last year for $249,900 and moved in a few weeks ago, according to Volkman and state records.

Along with a partnership with a contract manufacturing organization that produces an initial key ingredient, the dedicated lab gives XLock the capacity to increase production of its protein 100-fold, Volkman said.

"What that allows us to do is move our studies from testing in mice going up to larger animals like rats and even chimpanzees," said Volkman, who now also serves as the startup's chief scientific officer. "We're trying to de-risk the technology by establishing safety in animal models."

Previously, XLock Biosciences was operating semi-virtually and utilizing MCW research space. MCW has an equity share in the company.
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The lead compound XLock Biosciences is working on is a biologic drug, as distinguished from a small molecule drug, according to the company. It mimics a naturally occurring protein and has a therapeutic effect that could be administered via an injection, XLock Biosciences vice president Chad Koplinski said.

Although the startup's original research studied psoriasis, XLock Biosciences is now focused on commercializing its molecule as therapeutic for other diseases that have few or no FDA-approved treatments, such as graft versus host disease — a common complication for bone marrow transplant patients, Volkman said. 

XLock Biosciences has raised more than $2 million in government grant funding through programs like Small Business Innovation Research. 

The startup is looking to raise around $10 million in venture capital next year to finance its operations to the point of submitting an Investigational New Drug (IND) application with the U.S. Food and Drug Administration, Volkman said.

"IND is basically the starting line for phase-one clinical trials," he said.

G protein–coupled receptors (GPCRs) recruit b-arrestins to coordinate diverse cellular processes, but the structural dynamics driving this process are poorly understood. Atypical chemokine receptors (ACKRs) are intrinsically biased GPCRs that engage b-arrestins but not G proteins, making them a model system for investigating the structural basis of b-arrestin recruitment. Here, we performed nuclear magnetic resonance (NMR) experiments on 13CH3-e–methionine–labeled ACKR3, revealing that b-arrestin recruitment is associated with conformational exchange at key regions of the extracellular ligand-binding pocket and intracellular b-arrestin–coupling region. NMR studies of ACKR3 mutants defective in b-arrestin recruitment identified an allosteric hub in the receptor core that coordinates transitions among heterogeneously populated and selected conformational states. Our data suggest that conformational selection guides b-arrestin recruitment by tuning receptor dynamics at intracellular and extracellular regions.

Dynamic control of GPCRs
​Arrestins are a group of proteins that regulate signaling through G protein–coupled receptors (GPCRs). They are best known as an off switch in signaling through G proteins, but they also coordinate G protein–independent signaling. Kleist et al. took advantage of an intrinsically β-arrestin–biased GPCR, atypical chemokine receptor 3 (ACKR3), to study β-arrestin recruitment. Nuclear magnetic resonance spectroscopy experiments support a role for conformational selection. The inactive state shows conformational heterogeneity at the ligand-binding pocket. Ligand binding can cause stabilization of an active state that in turn tunes the dynamics at the intracellular region to allow β-arrestin recruitment. —VV