Biology subjects

Kutzler, M. A.

Publications and source records attributed to Kutzler, M. A..

3 recordsLinked to original sources

bioRxiv2026

Adenosine deaminase co-immunization reverses age-associated immunosenescence by restoring germinal center T follicular helper cell function

Older adults experience disproportionate morbidity and mortality from Clostridioides difficile infection (CDI); however, existing toxoid- and receptor binding domain (RBD)-based vaccines elicit suboptimal protection in aged hosts due to the age-associated defects in CD4+ T cell function, T follicular helper (TFH) cell activation, and antibody quality. We evaluated whether adenosine deaminase (ADA), an enzymatic immune modulator that degrades immunosuppressive adenosine, and improves GC TFH differentiation and survival, could reverse these age-related impairments when co-delivered with DNA vaccine plasmids targeting toxin A and B RBDs (pRBD). In aged mice, pRBD vaccination alone produced markedly reduced toxin-specific effector/memory CD4+ T cells, diminished TFH activation, and poor toxin A neutralization compared to vaccinated young mice. Co-immunization with plasmid-encoded adenosine deaminase-1 (pADA) restored toxin-specific CD4+ T cell generation and cytokine production, activation-induced marker (AIM) TFH responses, and antibody-mediate toxin neutralization to levels comparable to young adults. Mechanistically, pADA co-immunization was associated with the reduction of CXCR4 on germinal center (GC) TFH cells--an age-related defect linked to impaired GC positioning and diminished B cell help--suggesting that ADA improves humoral quality by correcting GC TFH mislocalization. These immune enhancements corresponded with improved clinical outcomes in morbidity, mortality, and weight-loss following C. difficile spore challenge of aged mice. Finally, pADA significantly reduced adenosine levels in aged lymph nodes, implicating a potential enzymatic-based regulation of GC immunosenescence. Together, these findings identify ADA as a metabolic adjuvant capable of reversing key features of vaccine immunosenescence and highlight adenosine dependent CXCR4 regulation as a tractable axis for improving vaccine efficacy in older populations.

immunology↗

bioRxiv2026

Generation and characterization of a novel MHC-II tetramer for tracking and characterization of toxin B-specific CD4+ T cell responses

The gastrointestinal pathogen Clostridioides difficile, is a major burden for health systems due to high rates of recurrence. C. difficile pathogenesis is mediated by two virulence factors, toxin A (TcdA) and Toxin B (TcdB). Antibodies specific for TcdA and TcdB are correlated with protection from symptomatic recurrence, however, the role for CD4+ T cells is poorly understood in part due to the lack of tools to study the toxin-specific CD4+ T cell response. Our group recently demonstrated the antibody and CD4+ T cell response to C. difficile toxins is impaired via the glucosyltransferase activity of the toxins; however, tools do not exist to study the protective capacity and the phenotype of toxin-specific CD4+ T cells. Therefore, we developed an MHC-II tetramer to identify TcdB-specific CD4+ T cells via flow cytometry. Herein, we identified an immunodominant epitope (TcdB1961-1975) in the CROPs region of TcdB and optimized an MHC-II tetramer for use in tracking and phenotyping TcdB-specific CD4+ T cell responses following multiple different immunization strategies in mice. Utilizing the tetramer, TcdB-specific T follicular helper (Tfh) cells were detected following TcdB-CROPs mRNA-LNP vaccination validating the advantage of the tetramer. Furthermore, using a modular mRNA vector expressing the TcdB1961 peptide covalently bound to the beta chain of MHC-II (MHC-II{beta}) we were able to generate a robust population of TcdB-specific CD4+ T cells. These data outline the generation of new tools for the C. difficile field and lay the groundwork for future studies of toxin-specific CD4+ T cell responses.

immunology↗

bioRxiv2021

Pre-vaccination Frequency of Circulatory Tfh is associated with Robust Immune Response to TV003 Dengue Vaccine

It has been estimated that more than 390 million people are infected with Dengue virus every year; around 96 millions of these infections result in clinical pathologies. To date, there is only one licensed viral vector-based Dengue virus vaccine CYD-TDV approved for use in dengue endemic areas. While initially approved for administration independent of serostatus, the current guidance only recommends the use of this vaccine for seropositive individuals. Therefore, there is a critical need for investigating the influence of Dengue virus serostatus and immunological mechanisms that influence vaccine outcome. Here, we provide comprehensive evaluation of sero-status and host immune factors that correlate with robust immune responses to a Dengue virus vector based tetravalent vaccine (TV003) in a Phase II clinical cohort of human participants. We observed that sero-positive individuals demonstrate a much stronger immune response to the TV003 vaccine. Our multi-layered immune profiling revealed that sero-positive subjects have increased baseline/pre-vaccination frequencies of circulating T follicular helper (cTfh) cells and the Tfh related chemokine CXCL13/BLC. Importantly, this baseline/pre-vaccination cTfh profile correlated with the vaccinees ability to launch neutralizing antibody response against all four sero-types of Dengue virus, an important endpoint for Dengue vaccine clinical trials. Overall, we provide novel insights into the favorable cTfh related immune status that persists in Dengue virus sero-positive individuals that correlate with their ability to mount robust vaccine specific immune responses. Such detailed interrogation of cTfh cell biology in the context of clinical vaccinology will help uncover mechanisms and targets for favorable immuno-modulatory agents. Author summaryDengue virus (DENV) is a worldwide threat that causes significant health and economic burden. Currently, there are several challenges in the development of a DENV vaccine including the existence of four different serotypes all; capable of causing disease and antibody dependent enhancement (ADE). For complete protection, a vaccine must be able to generate neutralizing antibodies against all 4 serotypes to avoid ADE. Currently, there is one licensed DENV vaccine, CYD-TDV (DENGVAXIATM). However, this vaccine is only efficacious in protecting against severe disease in DENV seropositive individuals therefore serostatus effect must be further studied for optimal vaccine design. A subset of CD4+ T cells called T-follicular helper (Tfh) cells have been well known to play a major role in aiding high affinity antibody production. Therefore, we chose to look at subsets of Tfh and the cytokines they produce in human blood that can serve as biomarkers for effective vaccine design. We found that DENV sero-positive participants had increased pre-vaccination frequencies of Tfh cells and higher levels of the Tfh related chemokine CXCL13/BLC that plays a role in directing antigen-specific responses. This pre-vaccination Tfh profile and CXCL13/BLC are then correlated positively with the vaccinees ability to produce neutralizing antibody against all four sero-types (breadth of the Response) of DENV, an important goal for all DENV vaccine trials.

immunology↗