Mileto, S. | Search bioRxiv

bioRxiv2024

MLL1 directs gut-associated antibody responses to helminth and bacterial infections

Soil-transmitted helminths are one of the most common infections globally, yet how to promote effective gut-associated humoral responses is not well understood. We identify the histone methyltransferase MLL1 as a key target to promote IgA-driven responses. Mll1 was increased in germinal center B cells in gut-associated lymphoid tissues, and Mll1-deficiency led to changes in the histone modification H3K4me3 on key B cell and immune-regulatory genes. Correspondingly, MLL1-deficient B cells had defective germinal centers and IgG1 in response to the helminth Trichuris muris. Yet, Mll1f/fCd23cre/+ mice expelled worms more rapidly compared to control mice. Accelerated worm clearance correlated with elevated IgA+ plasma cells, as well as both serum and fecal IgA. RNA-sequencing identified CCR9 as a key MLL1-regulated molecule. As such, Mll1f/fCd23cre/+ mice infected with T. muris had increased IgA+CCR9+ PC localized in the large intestine. Regulation of IgA by MLL1 was confirmed beyond T. muris infection. In vitro cultures confirmed Mll1-deficiency increased IgA+ plasma cells in a B cell-intrinsic manner, and IgA production was also increased in Mll1f/fCd23cre/+ mice infected with the bacterium C. rodentium. This study reveals MLL1 as a key target to promote IgA responses to gut-associated infections.

immunology↗

bioRxiv2021

Using antibody synergy to engineer a high potency biologic cocktail against C. difficile

Here we show that transgenic spirulina may solve key challenges of developing effective monoclonal protein therapeutics for diseases afflicting gastrointestinal (GI) tissues. We describe, as a paradigm for this novel approach, LMN-201: an investigational four-component treatment for Clostridioides difficile (C. difficile) infection comprising four monoclonal protein therapeutics produced and delivered within spirulina biomass. Three antibody-like moieties within LMN-201 were rationally designed using a multiplicative potency framework, termed synthetic avidity, that increased in vitro toxin neutralization potency by >200-fold relative to the individual components. The fourth moiety, a lysin enzyme protein, adds direct, toxinotype-agnostic antibacterial activity. In rodent challenge models, species-relevant LMN-201-like cocktails reduced disease burden and mortality. In a human GI pharmacokinetic study, LMN-201 was present at concentrations 100- to 1,000-fold above the estimated minimally effective therapeutic threshold at the distal intestine. In a Phase 2 study in participants suffering from C. difficile infection (CDI), seven days of treatment with LMN-201 plus standard-of-care antibiotics achieved initial clinical cure in 21/21 (100%) participants, sustained clinical cure through four weeks in 19/21 (90.5%) participants, and had a favorable safety profile. These findings support LMN-201 with standard-of-care antibiotics as a viable treatment option for CDI, validate spirulina as a scalable platform for oral biologics, and establish a generalizable strategy for engineering high-potency combination protein therapeutics for diseases with a GI tissue nexus.

bioengineering↗