Organoid Polymer Functionality and Mode of Klebsiella pneumoniae Membrane Antigen Presentation Regulates Ex Vivo Germinal Center Epigenetics in Young and Aged B Cells

Abstract

Antibiotic-resistant bacteria are a major global health threat that continues to rise due to a lack of effective vaccines. Of concern are Klebsiella pneumoniae (K. pneumoniae) that fail to induce in vivo germinal center B cell responses, which facilitate antibody production to fight infection. Immunotherapies using antibodies targeting antibiotic-resistant bacteria are emerging as promising alternatives, however, they cannot be efficiently derived ex vivo, necessitating the need for immune technologies to develop therapeutics. Here, polyethylene glycol (PEG)-based immune organoids are developed to elucidate the effects of polymer end-point chemistry, integrin ligands, and mode of K. pneumoniae antigen presentation on germinal center-like B cell phenotype and epigenetics, to better define the lymph node microenvironment factors regulating ex vivo germinal center dynamics. Notably, PEG vinyl sulfone or acrylate fail to sustain primary immune cells, but functionalization with maleimide (PEG-4MAL) leads to B cell expansion and germinal center-like induction. RNA sequencing analysis of lymph node stromal and germinal center B cells shows niche associated heterogeneity of integrin-related genes. Incorporation of niche-mimicking peptides reveals that collagen-1 promotes germinal center-like dynamics and epigenetics. PEG-4MAL organoids elucidate the impact of K. pneumoniae outer membrane-embedded protein antigen versus soluble antigen presentation on germinal centers and preserve the response across young and aged mice.

Thymus Extracellular Matrix‐Derived Scaffolds Support Graft‐Resident Thymopoiesis and Long‐Term In Vitro Culture of Adult Thymic Epithelial Cells

“…Tunable microenvironments in combination with proper immune cell types or organoids will provide unprecedented opportunities to investigate organ physiology and immune response ex vivo, and to test and implement novel therapeutic strategies. [ 47,48 ]…”

Eliciting B cell immunity against infectious diseases using nanovaccines

“…antigen-specific bnAb development, whether they have an impact on B-cell somatic hypermutation and T FH cell functions, and whether they can break through clonality bottlenecks that restrict the engagement of the large diversity of B-cell repertoire and memory responses. Emerging ex vivo cellular and acellular technologies (for example, organoids 28,[64][65][66] and acellular antibody discovery pipeline 67 ) that could be integrated with nanovaccine research in both in vivo and ex vivo settings can reduce the nanovaccine discovery timeline, impact on the dynamics of germinal centres and memory B-cell re-activation, and elucidate mechanisms to overcome poor immunity in the elderly population 68 .…”

Recent advances in chemically defined and tunable hydrogel platforms for organoid culture

“…The immune system is highly intricate and is still one of the most challenging systems to study. In order to recapitulate such complex microenvironment, lymph node organoids were developed in MMP-sensitive, defined PEG hydrogels using Naïve B cells and 40LB stromal cells (genetically modified to express CD40 ligand and produce B cell-activating factor) [118]. The study revealed that maleimide group, but not vinyl sulfone and acrylate, when used as end-group functionality in PEG hydrogels, sustained B cells' survival and germinal center-like induction.…”