Ghodsinia, A. | bioRxiv Science

bioRxiv2025

Probabilistic migration events drive transient tissue residency of lymphocytes during homeostasis

Tissue-resident lymphocytes form a phenotypically and functionally distinct analog to the corresponding circulatory lymphocyte populations. Residential CD8 T cells, in particular, are identified as having prolonged residence in the tissues and key functions in recall responses at tissue-environmental interfaces, although the dwell time in individual tissues has yet to be resolved. Residential CD4 T cells, regulatory T cells, B cells, and NK cells have been demonstrated to share phenotypic properties with residential CD8 T cells, but the migratory kinetics are even more poorly defined. Here we used probabilistic modelling on a large parabiosis dataset, covering multiple time-points and tissues, to calculate migration kinetics and dwell times of multiple lymphocyte subsets across a diverse set of tissues. Markov chain modelling identified distinct cell type-specific and tissue-specific residency patterns. The liver and gut were prone to prolonged residency compared to other tissue types, and a hierarchy of residency was observed with CD8 T cells and NK cells demonstrating longer residency than CD4 conventional T cells and regulatory T cells, which in turn resided in tissues longer than B cells. With few exceptions, however, average residency was at least an order of magnitude shorter than the life-span of the mouse, indicating a more dynamic form of steady-state tissue residency than usually assumed. Together these data provide a comprehensive model of a pan-tissue shared program in lymphocyte tissue residence, as well as identifying cell type- and organ-specific modification of the migratory kinetics.

immunology↗

bioRxiv2024

Directed disruption of IL2 aggregation sites produces designer biologics with enhanced specificity coupled to improved production capacity

The pleotropic nature of interleukin-2 (IL2) has allowed it to be used as both a pro-inflammatory and anti-inflammatory therapeutic agent, through promotion of regulatory T cell (Treg) responses via the IL2RA receptor or promotion of CD8 T cell responses via the IL2RB receptor, respectively. However, the utility of IL2 as a treatment is limited by this same pleiotropy, and protein engineering to bias specificity towards either the regulatory T cell (Treg) or CD8 T cell lineage often requires a trade-off in protein production or total bioactivity. Here we use SolubiS, a computational algorithm-based method, to predict mutations within the IL2 structure to improve protein production yield while altering cellular selectivity, to generate a mutein with elevated therapeutic potential. The design and testing process identified the V126R (murine) / V111R (human) mutation as a Treg-enhancing mutein, creating a cation repulsion to inhibit primary binding to IL2RB, with a post-IL2RA confirmational shift enabling secondary IL2RB binding, and hence allowing the trimeric receptor complex to form. In human IL2, additional N110R T151R aggregation-protecting mutations could improve protein yield of the V111R mutation. The approach also generated novel CD8 T cell-promoting mutations. Y79K created a cation-cation repulsion with IL2RA, while Q50W enhanced CD8 T cell activity through potential {pi}-stacking enhancing binding to IL2RB, with the combination highly stimulatory for CD8 T cells. For human IL2, Y65K (homolog to murine Y79K) coupled with E82K prevented IL2RA binding, however it required the aggregation-protecting mutations of N110R T151R to rescue production. These muteins, designed with both cellular specificity and protein production features, have potential as both biological tools and therapeutics.

immunology↗