Biology subjects

Chong, A. S.

Publications and source records attributed to Chong, A. S..

7 recordsLinked to original sources

bioRxiv2026

Autoreactive antibody production by intrarenal B cells in mouse kidney allograft rejection

Antibody-mediated rejection (AMR) is a major cause of kidney allograft failure, with donor HLA-specific antibodies (DSA) recognized as primary drivers of AMR pathology. However, a significant proportion of AMR diagnoses lack detectable DSA, thus implicating DSA-independent mechanisms. In support, we previously reported on the accumulation of autoreactive B cells in rejecting renal biopsies, which raised the possibility that autoreactive IgG produced within the allograft contributes to graft pathology. In this study, we used mouse models to show that rejecting kidney allografts preferentially promoted a breach in autoreactive B cell tolerance, leading to the local production of autoreactive antibodies. Notably, autoreactive IgG responses were uncoupled from DSA production, indicative of distinct regulation. Organoid cultures confirmed that autoantibody production was observed in the rejecting kidney, whereas DSAs were produced in both the lymph node and graft. Intrarenal B cells expressing Nur77 were enriched for autoreactivity, consistent with in situ antigen recognition. Finally, autoreactive antibodies are pathogenic, since inhibiting autoantibody production with transient anti-IL-15 and CTLA-4Ig led to preserved kidney allografts. These unique features of in situ autoantibody responses may be relevant to diverse diseases with chronic tissue inflammation beyond transplantation.

immunology↗

bioRxiv2026

High-dimensional spatial proteomics and novel machine learning pipeline identifies disease specific renal damage states

Lupus nephritis (LuN) and renal allograft rejection (RAR) manifest inflammation and fibrosis that ultimately lead to kidney failure. To quantitatively assess spatial injury patterns, we collected high dimensional spatial proteomics data from 23 LuN, 33 RAR, and 8 kidney control (KC) biopsies. We developed a computational pipeline to segment and classify tubules, capillaries, and glomeruli in whole-slide images using three trained neural networks (Renal Damage diagnosis, RDDx). RDDx achieved high accuracy and generalizability, reliably identifying small capillaries and differentiating tubular and vascular inflammation in kidney tissues. Both LuN and RAR showed reduced tubular and capillary areas with expanded interstitial space. LuN displayed patchy clusters of stressed and inflamed tubules, whereas RAR exhibited diffuse injury. Within RAR, T cell-mediated rejection (TCMR) showed intense tubulitis while antibody-mediated rejection (ABMR) featured proliferating and inflamed capillaries near atrophic tubules. RDDx quantitative metric outputs correlated with histopathological scores, highlighting their reproducibility and clinical relevance. Stressed tubules in mildly inflamed LuN biopsies suggested they were a sensitive injury marker, while proliferating capillaries revealed microvascular remodeling in ABMR. These findings indicated RDDx can identify and quantify damage mechanisms specific to each renal disease thus facilitating future mechanistic studies and therapeutic target discovery.

immunology↗

bioRxiv2025

Comparative ScRNA-Seq Profiling of Antigen-Specific CD4+ T cells in Semi-Allogeneic Transplantation and Pregnancy Reveals Intersecting Signatures of Rejection and Tolerance

Transplantation of allogeneic organs requires lifelong immunosuppression to prevent rejection. Prior sensitization and resultant memory T cells are barriers to achieving successful transplant tolerance. In reproductive immunology by contrast, pregnancy represents a spontaneous model of tolerance where the semi-allogeneic fetus evades rejection even in multiparous or rejection-sensitized mothers. CD8+ T cell phenotypes of tolerance and rejection have been previously reported in transplant and pregnancy, but the transcriptional states of donor and fetus-specific CD4+ T cells remain poorly defined. Here, we performed Single-cell RNA-sequencing on endogenous, antigen-specific CD4+ T cells across models of allogeneic heart transplants and naive or paternal skin-sensitized pregnancy. We identified expanded T follicular helper (Tfh) and non-follicular effectors in transplant rejection absent in tolerance. Naive pregnancy resulted in a modest expansion of effector clusters with transcriptional quiescence that mirrored virgin mice. Successful sensitized pregnancy resulted in expanded Tfh clusters consistent with increased fetal-specific antibodies and limited non-Tfh effector responses. Most striking were the extensive changes imposed on donor-specific Foxp3pos regulatory T cells (Tregs) resulting in the co-clustering together with Foxp3neg T conventional cells (Tconvs) in transplant tolerance and the emergence of a Foxp3neg Type I Regulatory cluster observed in pregnancy of sensitized dams. Finally, we showed that these transcriptomes were relevant and enriched in human datasets of health and disease respectively. Thus, the context-dependent signatures of antigen-specific CD4+ T cells provide new insights into their divergent responses to allogeneic conflict at the intersection of transplant and reproductive immunology. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=178 HEIGHT=200 SRC="FIGDIR/small/663404v2_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@1b30a86org.highwire.dtl.DTLVardef@17820cforg.highwire.dtl.DTLVardef@1b1fbeaorg.highwire.dtl.DTLVardef@11ff17_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

Resolution of in situ inflammation in human lupus nephritis into principal immune cell trajectories

In human lupus nephritis (LuN), tubulointerstitial inflammation (TII) is prognostically more important than glomerular inflammation. However, a comprehensive understanding of both TII complexity and heterogeneity is lacking. Herein, we used high-dimensional confocal microscopy and specialized computer vision techniques to quantify immune cell populations and localize these within normal and diseased renal cortex structures. With these tools, we compared LuN to renal allograft rejection (RAR) and normal kidney. In both LuN and RAR, the 33 characterized immune cell populations formed discrete subgroups whose constituents co-varied in prevalence across biopsies. In both diseases, these co-variant immune cell subgroups organized into the same unique niches. Therefore, inflammation could be resolved into trajectories representing the relative prevalence and density of cardinal immune cell members of each co-variant subgroup. Indeed, in any one biopsy, the inflammatory state could be characterized by quantifying constituent immune cell trajectories. Remarkably, LuN heterogeneity could be captured by quantifying a few myeloid immune cell trajectories while RAR was more complex with additional T cell trajectories. Our studies identify rules governing renal inflammation and thus provide an approach for resolving LuN into discrete mechanistic categories. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/638655v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@109dd33org.highwire.dtl.DTLVardef@995037org.highwire.dtl.DTLVardef@161525dorg.highwire.dtl.DTLVardef@6692d8_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO C_FIG

immunology↗

bioRxiv2024

Donor HLA DQ reactive B cells clonally expand under chronic immunosuppression and include atypical CD21lowCD27- B cells with high avidity germline B cell receptors.

Long-term allograft survival is limited by humoral-associated chronic allograft rejection, suggesting inadequate constraint of humoral alloimmunity by contemporary immunosuppression. Heterogeneity in alloreactive B cells and the incomplete definition of which B cells participate in chronic rejection in immunosuppressed transplant recipients limits our ability to develop effective therapies. Using a double-fluorochrome single-HLA tetramer approach combined with single-cell in vitro culture, we investigated the B-cell receptor (BCR) repertoire characteristics, avidity, and phenotype of donor HLA-DQ reactive B cells in a transplant recipient with end-stage donor specific antibody (DSA)-associated cardiac allograft vasculopathy while receiving maintenance immunosuppression (tacrolimus, mycophenolate mofetil, prednisone). Donor DQB1*03:02/DQA1*03:01 (DQ8)-reactive IgG+ B cells were enriched for minimally mutated and germline encoded high avidity BCRs (median KD 4.26x10-09) with an atypical, antigen-experienced and proliferative phenotype (CD27-CD21lowCD71+CD11c+/-). These B cells coexisted with a smaller subset of more highly mutated, affinity matured IgG+CD27+ B cells. Circulating donor-reactive B cells and DSA remained detectable after rituximab, contrasting with the marked reduction in DSA after allograft explant and retransplant. Together, these findings define the persistence of germline high-avidity HLA-DQ alloreactive B cells and their co-existence with affinity matured clones that were both driven by the allograft despite conventional immunosuppression.

immunology↗

bioRxiv2024

Efficacy and limitations of combined A2.CAR Treg and anti-CD154 therapy in a mouse model of haplo-mismatched heart transplantation

Successful allograft specific tolerance induction would eliminate the need for daily immunosuppression and improve post-transplant quality of life. Adoptive cell therapy with regulatory T cells expressing donor-specific Chimeric Antigen Receptors (CAR-Tregs) is a promising strategy, but as monotherapy, cannot prolong the survival with allografts with multiple MHC mismatches. Using an HLA-A2-transgenic haplo-mismatched heart transplantation model in immunocompetent C57Bl/6 recipients, we show that HLA-A2-specific (A2) CAR Tregs was able to synergize with low dose of anti-CD154 to enhance graft survival. Using haplo-mismatched grafts expressing the 2W-OVA transgene and tetramer-based tracking of 2W- and OVA-specific T cells, we showed that in mice with accepted grafts, A2.CAR Tregs inhibited endogenous non-A2 donor- specific T cell, B cell and antibody responses, and promoted a significant increase in endogenous FoxP3+Tregs with indirect donor-specificity. By contrast, in mice where A2.CAR Tregs failed to prolong graft survival, FoxP3neg A2.CAR T cells preferentially accumulated in rejecting allografts and endogenous donor-specific responses were not controlled. This study therefore provides the first evidence for synergy between A2.CAR Tregs and CD154 blockade to promote infectious tolerance in immunocompetent recipients of haplo-mismatched heart grafts and defines features of A2.CAR Tregs when they fail to reshape host immunity towards allograft tolerance.

immunology↗

bioRxiv2020

Intrarenal B cells integrate in situ innate and adaptive immunity in human renal allograft rejection

In human allograft rejection, intrarenal B cell infiltrates identify those with a poor prognosis. However, how intrarenal B cells contribute to rejection is not known. Single cell RNA-sequencing of intrarenal class-switched B cells revealed a unique innate cell transcriptional state resembling murine peritoneal B1 cells (Bin cells). Comparison to the transcriptome of whole renal allograft rejecting tissue revealed that Bin cells existed within a complex autocrine and paracrine network of signaling axes. The immunoglobulins expressed by Bin cells did not bind donor specific antigens nor were they enriched for reactivity to ubiquitously expressed self-antigens. Rather, Bin cells frequently expressed antibodies reactive with renal expressed antigens. Furthermore, local antigens could drive Bin cell proliferation and differentiation into plasma cells expressing self-reactive antibodies. By contributing to local innate immune networks, and expressing antibodies reactive with renal expressed antigens, Bin cells are predicted to amplify local inflammation and tissue destruction.

immunology↗