Biology subjects

Gehring, A. J.

Publications and source records attributed to Gehring, A. J..

3 recordsLinked to original sources

bioRxiv2023

B Cells Promote T Cell Immunosenescence and Mammalian Aging Parameters

A dysregulated adaptive immune system is a key feature of aging, and is associated with age-related chronic diseases and mortality. Most notably, aging is linked to a loss in the diversity of the T cell repertoire and expansion of activated inflammatory age-related T cell subsets, though the main drivers of these processes are largely unknown. Here, we find that T cell aging is directly influenced by B cells. Using multiple models of B cell manipulation and single-cell omics, we find B cells to be a major cell type that is largely responsible for the age-related reduction of naive T cells, their associated differentiation towards pathogenic immunosenescent T cell subsets, and for the clonal restriction of their T cell receptor (TCR). Accordingly, we find that these pathogenic shifts can be therapeutically targeted via CD20 monoclonal antibody treatment. Mechanistically, we uncover a new role for insulin receptor signaling in influencing age-related B cell pathogenicity that in turn induces T cell dysfunction and a decline in healthspan parameters. These results establish B cells as a pivotal force contributing to age-associated adaptive immune dysfunction and healthspan outcomes, and suggest new modalities to manage aging and related multi-morbidity. One Sentence SummaryInsulin receptor signaling facilitates the induction of age associated B cell inflammatory changes, which drive phenotypic aging of the T cell compartment and adverse outcomes to mammalian healthspan parameters.

immunology↗

bioRxiv2023

Macrophages heterogeneity and significance during human fetal pancreatic development

Organogenesis is a complex process that relies on a dynamic interplay between extrinsic factors originating from the microenvironment and intrinsic factors specific to the tissue. For the endocrine cells of the islet of Langerhans, the local microenvironment consists of various cell types including pancreatic acinar and ductal cells as well as neuronal, immune, endothelial, and stromal cells. Interestingly, hematopoietic cells have been detected in human pancreas as early as 6 post-conception weeks (PCW)1,2, but whether they play a role during islet formation in humans remains largely unknown. To shed light on this question, we performed single nuclei RNA sequencing of the human fetal pancreas during the early weeks of the second trimester, specifically focusing on the molecular interaction between the hematopoietic niche and the pancreatic epithelium. Our analysis identified a wide range of hematopoietic cells as well as two distinct subsets of macrophages that are unique to the fetal pancreas and absent in neonatal or adult pancreatic tissues. Leveraging this discovery, we developed a co-culture system of hESC-derived endocrine-macrophage organoids to model their interaction in vitro. Remarkably, we found that macrophages promoted the differentiation and viability of developing endocrine cells in vitro and enhanced tissue engraftment in immunocompromised mice, supporting a role for these cells in future tissue engineering strategies for diabetes.

developmental biology↗

bioRxiv2023

Liver-specific Inflammatory Signatures Predict Clinically Significant Liver Damage.

Background and AimsInflammation drives progression of chronic liver disease. However, the triggers of inflammation remain undefined during chronic hepatitis B (CHB) because hepatic flares are spontaneous and difficult to capture. We used nucleoside analogue (NA) withdrawal to investigate early inflammatory events because liver damage after stopping therapy occurs in a predictable time frame. 11 CHB patients underwent 192 weeks of NA therapy before a protocol defined stop. Liver fine-needle aspirates (FNAs) were collected at baseline and 4-weeks post-withdrawal and analyzed using flow cytometry and single-cell RNA sequencing (scRNA-seq). Intrahepatic mononuclear cells (IHMCs) from uninfected livers were used to validate transcriptomic findings. At 4 weeks post NA-withdrawal, HBV DNA rebounded but alanine aminotransferase (ALT) levels remained normal, 7/11 patients developed ALT elevations (>2xULN) at later timepoints. There were no changes in cell frequencies between baseline and viral rebound. ScRNA-seq revealed upregulation of IFN stimulated genes (ISGs) and pro-inflammatory cytokine MIF upon viral rebound. In vitro experiments confirmed the type I IFN-dependent ISG profile whereas MIF was induced primarily by IL-12. MIF exposure further amplified inflammatory cytokine production by myeloid cells. Our data show that innate immune activation is detectable in the liver before clinically-significant liver damage is detectable in the serum.

immunology↗