Lang, M. L. | Search bioRxiv

bioRxiv2025

Human C. difficile-specific memory B cells encode protective IgG1 despite predominance of non-neutralizing antibodies.

Clostridioides difficile remains a common source of nosocomial infection resulting in a wide range of clinical outcomes and for which there is no vaccine and limited therapeutic options. C. difficile Toxin B (TcdB)-specific IgG is the best correlate of protection against severe and recurrent disease. However, there are very few therapeutic IgG fully human monoclonal antibodies (hmAbs) that have shown efficacy thus far. We therefore hypothesized that the memory B cell (Bmem) compartment of individuals who have recovered from infection may be dominated by non-protective IgG molecules but encode some antibodies that are protective. We therefore produced hmAbs from a library of Bmem-encoded IgG1 sequences. Most TcdB-specific hmAbs displayed low affinity binding and poor neutralization of TcdB in vitro while a few hmAbs had high affinity binding and good TcdB neutralization. The results correlated with in vivo studies in which high affinity, TcdB-neutralizing hmAbs provided moderate protection of C57Bl/6 mice against C. difficile disease. Similar protection was observed in Tg32 mice expressing the human FcRn transgene, indicating that gut delivery of hmAb did not account for limited efficacy. Although non-protective antibody sequences dominate the repertoire, human Bmem cells may be a good source of therapeutic hmAbs for C. difficile treatment.

immunology↗

bioRxiv2021

Peptide Aggregation Induced Immunogenic Rupture (PAIIR)

Under the influence of stress and membrane damage, cells undergo immunogenic cell death (ICD), which involves the release of damage associated molecular patterns (DAMPs), natural adjuvants for enhancing an immune response. In the presence of an antigen, released DAMPs can determine the type and magnitude of the immune response, and therefore the longevity and efficacy of an antigen-specific immunity. In the last decade, the immune response effect of ICD has been shown, yet there is no tool that can induce controlled ICD with predictable results, regardless of the cell type. We designed a peptide-based tool, called [II], for controlled damage to cell membrane to induce ICD and DAMPs release. Herein we describe a series of experiments that determine that the mechanism of action of [II] includes a caspase-dependent ICD and subsequent release of immune stimulating DAMPs, on various cell types. Moreover, we tested the hypothesis that controlled DAMP release via [II] in vivo was associated with enhancement of antigen-specific adaptive immunity with influenza hemagglutinin (HA) subunit vaccine. HA and [II] showed significantly higher HA specific IgG1 and IgG2a antibodies, compared to HA-only immunized mice, while the peptide itself did not elicit antibodies. In this paper, we demonstrate the first peptide-aggregation induced immunogenic rupture (PAIIR) approach as vaccine adjuvants for increasing both humoral and cellular immunity. In consideration of its ability to enhance IgG2a responses that are associated with heterosubtypic influenza virus protection, PAIIR is a promising adjuvant to promote universal protection upon influenza HA vaccination.

bioengineering↗