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Antibody inhibitors pose an ongoing challenge to the treatment of subjects with inherited protein deficiency disorders, limiting the efficacy of both protein replacement therapy and corrective gene therapy. Beyond their central role as producers of serum antibody, B cells also exhibit many unique properties that could be exploited in cell therapy applications, notably including antigen-specific recognition and the linked capacity for antigen presentation. Here we employed CRISPR-Cas9 to demonstrate that ex vivo antigen-primed Blimp1-knockout "decoy" B cells, incapable of differentiation into plasma cells, participated in and downregulated host antigen-specific humoral responses after adoptive transfer. Following ex vivo antigen pulse, adoptively transferred high-affinity antigen-specific decoy B cells were diverted into germinal centers en masse, thereby reducing participation by endogenous antigen-specific B cells in T-dependent humoral responses and suppressing both cognate and linked antigen-specific immunoglobulin (Ig)G following immunization with conjugated antigen. This effect was dose-dependent and, importantly, did not impact concurrent unrelated antibody responses. We demonstrated the therapeutic potential of this approach by treating factor VIII (FVIII)-knockout mice with antigen-pulsed decoy B cells prior to immunization with an FVIII conjugate protein, thereby blunting the production of serum FVIII-specific IgG by an order of magnitude as well as reducing the proportion of animals exhibiting functional FVIII inhibition by 6-fold.

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Syphilis continues to be a significant public health concern worldwide. The disease is endemic in many low- and middle-income countries, and rates have risen sharply in high-income countries over the last decade. The continued prevalence of infectious and congenital syphilis worldwide highlights the need for the development of an effective syphilis vaccine to complement public health measures for syphilis control. The complex, multi-stage course of syphilis infection necessitates a holistic approach to the development of an effective vaccine, in which immunization prevents both the localized stage of infection (typified by the highly infectious chancre) and the disseminated stages of infection (typified by the secondary rash, neurosyphilis, and destructive tertiary lesions, as well as congenital syphilis). Inhibiting development of the infectious chancre would reduce transmission thus providing community- level protection, while preventing dissemination would provide individual-level protection by reducing serious sequelae and may also provide community level protection by reducing shedding during secondary syphilis. In the current study we build upon prior investigations which demonstrated that immunizations with individual, well characterized T. pallidum TprK, TprC, and Tp0751 peptides elicits partial protection against infection in the animal model. Specifically, we show here that immunization with a TprC/TprK/Tp0751 tri-antigen cocktail protects animals from progressive syphilis lesions and substantially inhibits dissemination of the infection.

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Tuberculosis (TB) remains the single most serious infectious disease attributable to a single-causative organism. A variety of drugs have been evaluated for pulmonary delivery as dry powders: capreomycin sulfate has shown efficacy and was safely delivered by inhalation at high doses to human volunteers, whereas CPZEN-45 is a new drug that has also been shown to kill resistant TB. The studies here combine these drugs-acting by different mechanisms-as components of single particles by spray-drying, yielding a new combination drug therapy. The spray-dried combination powder was prepared in an aerodynamic particle size range suitable for pulmonary delivery. Physicochemical storage stability was demonstrated for a period of 6 months. The spray-dried combination powders of capreomycin and CPZEN-45 have only moderate affinity for mucin, indicating that delivered drug will not be bound by these mucins in the lung and available for microbicidal effects. The pharmacokinetics of disposition in guinea pigs demonstrated high local concentrations of drug following direct administration to the lungs and subsequent systemic bioavailability. Further studies are required to demonstrate the in vivo efficacy of the combination to confirm the therapeutic potential of this novel combination.

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In natural microbial systems, conditional spatial sequestration of transcription factors enables cells to respond rapidly to changes in their environment or intracellular state by releasing presynthesized regulatory proteins. Although such a mechanism may be useful for engineering synthetic biology technologies ranging from cell-based biosensors to biosynthetic platforms, to date it remains unknown how or whether such conditional spatial sequestration may be engineered. In particular, based upon seemingly contradictory reports in the literature, it is not clear whether subcellular spatial localization of a transcription factor within the cytoplasm is sufficient to preclude regulation of cognate promoters on plasmid-borne or chromosomal loci. Here, we describe a modular, orthogonal platform for investigating and implementing this mechanism using protease-alleviated spatial sequestration (PASS). In this system, expression of an exogenous protease mediates the proteolytic release of engineered transcriptional regulators from the inner face of the Escherichia coli cytoplasmic membrane. We demonstrate that PASS mediates robust, conditional regulation of either transcriptional repression, via tetR, or transcriptional activation, by the λ phage CI protein. This work provides new insights into a biologically important facet of microbial gene expression and establishes a new strategy for engineering conditional transcriptional regulation for the microbial synthetic biology toolbox.

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