Biology subjects

Fandrich, M.

Publications and source records attributed to Fandrich, M..

4 recordsLinked to original sources

bioRxiv2025

Lymphoid-tissue-on-chip recapitulates human antibody responses in vitro

In the past decades, vaccine development has made great strides. Nevertheless, more often than not, vaccine candidates fail in advanced stages of development and clinical trials. A key reason is the poor predictive value of non-clinical in vivo and in vitro models, due to either species-specific differences in the immune response or insufficient reflection of physiological vaccine mechanisms. Reliable modeling of human adaptive immune responses is a prerequisite to understand processes leading to vaccine-induced protective immunization and to drive informed decisions in vaccine development pipelines. Here, we present a centrifugal microfluidics based organ-on-chip approach to generate an organotypic high density lymphoid tissue on-chip. The model enables long-term culture of lymphoid tissue and raised antigen-specific antibody responses against influenza vaccines even after four weeks on-chip. Antibody response of different magnitude and quality could be induced both by direct antigen exposure as well as by recruitment of antigen-presenting cells from the periphery. The model represents an attractive approach to evaluate the impact of the mode of antigen delivery on adaptive immune responses. Beyond applications in vaccine development, the lymphoid-tissue-on-chip provides a platform to study cellular interactions during homeostasis, immune responses and long-term impact of immunomodulators over several weeks.

bioengineering↗

bioRxiv2024

Making the effect visible - OX40 targeting nanobodies for in vivo imaging of activated T cells

PurposeHuman OX40 (hOX40/CD134), a member of the TNF receptor superfamily, is mainly expressed on activated T lymphocytes. Triggered by its ligand OX40L (CD252), it provides costimulatory signals that support the differentiation, proliferation and long-term survival of T cells. Besides being a relevant therapeutic target, hOX40 is also an important biomarker for monitoring the presence or infiltration of activated T cells within the tumor microenvironment (TME), the inflammatory microenvironment (IME) in immune-mediated diseases (IMIDs) and the lymphatic organs. Here, we developed novel single domain antibodies (nanobodies, Nbs) targeting hOX40 to monitor the activation status of T cells by in vivo molecular imaging. MethodsNbs against hOX40 (hOX40-Nbs) were selected from an immunized Nb-library by phage display. The identified hOX40-Nbs were characterized in vitro, including determination of their specificity, affinity, stability, epitope recognition and their impact on OX40 signaling and T cell function. A lead candidate was site-specifically conjugated with a fluorophore via sortagging and applied for noninvasive in vivo optical imaging (OI) of hOX40-expressing cells in a xenograft mouse model. ResultsOur selection campaign revealed four unique Nbs that exhibit strong binding affinities and high stabilities under physiological conditions. Epitope binning and domain mapping indicated the targeting of at least two different epitopes on hOX40. When analyzing their impact on OX40 signaling, an agonistic effect was excluded for all validated Nbs. Incubation of activated T cells with hOX40-Nbs did not affect cell viability or proliferation patterns, whereas differences in cytokine release were observed. In vivo OI with a fluorophore-conjugated lead candidate in experimental mice with hOX40-expressing xenografts demonstrated its specificity and functionality as an imaging probe. ConclusionConsidering the need for advanced probes for noninvasive in vivo monitoring of T cell activation dynamics, we propose, that our hOX40-Nbs have a great potential as imaging probes for noninvasive and longitudinal in vivo diagnostics. Quantification of OX40+ T cells in TME or IME will provide crucial insights into the activation state of infiltrating T cells, offering a valuable biomarker for assessing immune responses, predicting treatment efficacy, and guiding personalized immunotherapy strategies in patients with cancer or IMIDs.

immunology↗

bioRxiv2023

Development and validation of a respiratory syncytial virus multiplex immunoassay

Respiratory syncytial virus (RSV) is one of the leading causes of severe respiratory disease in infants and adults. RSV exists as two subtypes A and B, which co-circulate throughout the season, although one will usually become dominant. While vaccines and monoclonal therapeutic antibodies either are or will shortly become available, correlates of protection remain unclear. For this purpose, we developed an RSV multiplex immunoassay that analyses antibody titers towards the post-F, Nucleoprotein, and a diverse mix of G proteins. Technical and clinical validation showed outstanding performance, while methodological developments enabled identification of the subtype of previous infections through use of the diverse G proteins for approximately 50% of samples. As a proof of concept to show the suitability of the assay in serosurveillance studies, we then evaluated titer decay and age- dependent antibody responses within population cohorts. Overall, the developed assay shows robust performance, is scalable, provides additional information on infection subtype, and is therefore ideally suited to be used in future population cohort studies. ImportanceAlthough respiratory syncytial virus (RSV) is endemic and re-infections are common and harmless to the majority of the population, it is a leading cause of hospitalization in young children, the elderly, or immunocompromised individuals. A better characterization of RSV immunology and spreading dynamics is thus critical for preparedness, especially when interventions aiming to mitigate other diseases (e.g., COVID-19) disturb its endemic cycles. This requires high-throughput information-dense assays. We therefore developed a bead-based multiplex immunoassay that allows measurements of antibodies against multiple RSV antigens simultaneously. We identified antibodies which were strong indicators of previous infection, while others allowed identification of the subtype of the previous infection. The assay itself was shown to be robust and scalable, making it ideal for to keep track of the temporal variation RSV immunity profiles within the population.

immunology↗

bioRxiv2018

Cryo-EM structure of an amyloid fibril from systemic amyloidosis

Systemic AA amyloidosis is a worldwide occurring disease of humans and animals that arises from the misfolding of serum amyloid A protein. To provide insights into the molecular basis of this disease we used electron cryo-microscopy and determined the structure of an ex vivo amyloid fibril purified from AA amyloidotic mice at 3.0 [A] resolution. The fibril consists of C-terminally truncated serum amyloid A protein arranged into a compactly folded all-{beta} conformation. The structure identifies the protein N-terminus as central for the assembly of this fibril and provides a mechanism for its prion-like replication. Our data further explain how amino acid substitutions within the tightly packed fibril core can lead to amyloid resistance in vivo.

biophysics↗