Biology subjects

Yadava, K.

Publications and source records attributed to Yadava, K..

3 recordsLinked to original sources

bioRxiv2021

Hematopoietic stem cell requirement for macrophage regeneration is tissue-specific

Tissue-resident macrophages (TRM{Phi}) are important immune sentinels responsible for maintaining tissue and immune homeostasis within their specific niche. Recently, the origins of TRM{Phi} have undergone intense scrutiny where now most TRM{Phi} are thought to originate early during embryonic development independent of hematopoietic stem cells (HSCs). We previously characterized two distinct subsets of mouse peritoneal cavity macrophages (Large and Small Peritoneal Macrophages; LPM and SPM, respectively) whose origins and relationship to both fetal and adult long-term (LT)-HSCs have not been fully investigated. Here we employ highly purified LT-HSC transplantation and in vivo lineage tracing to show a dual ontogeny for LPM and SPM, where the initial wave of peritoneal macrophages is seeded from yolk sac-derived precursors, which later require LT-HSCs for regeneration. In contrast, transplanted fetal and adult LT-HSCs are not able to regenerate brain-resident microglia. Thus, we demonstrate that LT-HSCs retain the potential to develop into TRM{Phi}, but their requirement is tissue-specific.

immunology↗

bioRxiv2020

Hyaluronan Synthesis Inhibition Impairs Antigen Presentation and Delays Transplantation Rejection

A coat of pericellular hyaluronan surrounds mature dendritic cells (DC) and contributes to cell-cell interactions. We asked whether 4-methylumbelliferone (4MU), an oral inhibitor of HA synthesis, could inhibit antigen presentation. We find that 4MU treatment reduces pericellular hyaluronan, destabilizes interactions between DC and T-cells, and prevents T-cell proliferation in vitro and in vivo. These effects were observed only when 4MU was added prior to initial antigen presentation but not later, consistent with 4MU-mediated inhibition of de novo antigenic responses. Building on these findings, we find that 4MU delays rejection of allogeneic pancreatic islet transplant and allogeneic cardiac transplants in mice and suppresses allogeneic T-cell activation in human mixed lymphocyte reactions. We conclude that 4MU, an approved drug, may have benefit as an adjunctive agent to delay transplantation rejection.

immunology↗

bioRxiv2020

Sustained Release of IL-2 Using an Injectable Hydrogel Prevents Autoimmune Diabetes

Interleukin 2 (IL-2) is a promising therapy for autoimmune type 1 diabetes (T1D), but the short half-life in vivo (less than 6 minutes) limits effective tissue exposure to IL-2. Tissue exposure is required for the tolerogenic effects of IL-2. We have developed an injectable hydrogel that incorporates heparin polymers to enable the sustained release of IL-2. This platform uses clinical grade and commercially available materials, including collagen, hyaluronan, and heparin, to deliver IL-2 by slowly degrading and releasing IL-2 over a two-week period in vivo. We find that heparin potentiates the activity of IL-2 and IL-2-mediated expansion of Foxp3+ regulatory T cell (Treg). Hydrogel-mediated IL-2 release showed a reduction of CD4+ and CD8+ T cells and an increase of FoxP3+ Treg in the lymph nodes of injected mice. Moreover, in the Non-Obese Diabetic (NOD) mouse model of T1D once-weekly administration of IL-2 hydrogels prevented diabetes onset as efficiently as 3x weekly repeated injections of soluble IL-2. Together these data suggest that heparin-containing hydrogels may have benefit in delivering low-dose IL-2 and promoting immune tolerance in autoimmune diabetes.

immunology↗