Biology subjects

Bromberg, J. S.

Publications and source records attributed to Bromberg, J. S..

6 recordsLinked to original sources

bioRxiv2025

Cellular and Molecular Resolution of Focal Segmental Glomerulosclerosis Recurrence in Human Allografts

Primary Focal Segmental Glomerulosclerosis (FSGS) is an important cause of end-stage renal disease (ESRD). Primary FSGS recurrence rates in transplanted kidneys are high, with 25-50% in first transplants and up to 80% in second transplants, often leading to graft loss. To investigate the molecular and cellular events underlying recurrent primary FSGS (reFSGS), we performed single-nucleus RNA sequencing (snRNA-seq) on kidney transplant biopsies from patients with reFSGS and controls with normal allograft function. Our analysis revealed that podocyte loss in reFSGS is driven by metabolic and structural dysregulation rather than apoptosis. Overexpression of vascular endothelial growth factor (VEGF)-A by podocytes was observed, potentially disrupting glomerular endothelial cell growth and permeability. Parietal epithelial cells (PECs) exhibited dedifferentiation towards a podocyte-like state, potentially compensating for podocyte loss, but this was associated with increased collagen deposition and glomerular sclerosis. Ligand-receptor interactions between glomerular cells and B cells further promoted extracellular matrix deposition and fibrosis. Additionally, tubular cells demonstrated evidence of tubular sclerosis and impaired regenerative potential, accompanied by increased interactions with T cells. These findings provide novel insights into the pathogenesis of reFSGS and identify potential therapeutic targets. This study establishes a foundation for future research to further investigate cell-type-specific interventions in recurrent FSGS.

molecular biology↗

bioRxiv2025

Transplant immunosuppressant therapies induce unique functional changes in lymph node and re-shape gut immune homeostasis

BackgroundLifelong immunosuppressive therapy is required to prevent allograft rejection in organ transplantation. Current immunosuppressants effectively suppress adaptive and innate immune responses, but their broad, antigen-non-specific effects often result in severe off-target complications. It remains a significant unmet medical need in transplant medicine. ResultsIn this study we investigated immunosuppressant effects of four major immunosuppressant classes, including tacrolimus, prednisone, mycophenolate mofetil (MMF), and fingolimod (FTY), on the gut microbiome, metabolic pathways, lymphoid architecture and lymphocyte trafficking after up to 30-day chronic exposure. Despite their distinct mechanisms of action and not designed to target the gut, all immunosuppressive drugs induced profound and time-dependent alterations in both intestine gene expression and gut microbiome composition. Progressive alterations from moderate early, drug-specific changes to a strikingly convergent microbial dysbiosis, marked by significant expansion of pathobionts of Muribaculaceae, occurred across all drug classes. Concurrently, all drugs uniformly induced significant suppression of mucosal immunity including B cell, immunoglobulin, and antigen recognition. Time-dependent changes in lymph node (LN) reorganization and cellular composition were also observed, marked by a progressive shift toward pro-inflammatory phenotypes in gut-draining mesenteric LNs and a gradual loss of tolerogenic architecture in peripheral LNs. Drug-specific metabolic alterations and distinct phases of intestinal transcriptional responses were also characterized. Notably, MMF and FTY demonstrated the most robust immunomodulatory properties, and were able to suppress alloantigen-induced inflammation through mediating regulatory T cell distribution and LN remodeling. ConclusionsTogether, these findings highlight the underappreciated complexity and temporal dynamics immunosuppressants effects, particularly their impact on the gut and compartmentalized regulation of alloimmune in lymphoid tissues. Understanding these relationships offers new opportunities for refining immunosuppressive strategies to reduce treatment-related off-target complications and improve long-term organ transplant outcomes.

immunology↗

bioRxiv2024

Regulatory T cells crosstalk with tumor and endothelium through lymphotoxin signaling

Regulatory T cells (Tregs) are suppressors of anti-tumor immunity that exert multifaceted functions by signaling surrounding cells. We revealed Tregs use their high-level surface lymphotoxin (LT)1{beta}2 to preferentially stimulate LT{beta} receptor (LT{beta}R) nonclassical NF{kappa}B signaling on both tumor and lymphatic endothelial cells (LECs) to accelerate tumor growth and metastasis. Selectively targeting LT{beta}R nonclassical NF{kappa}B pathways on both tumors and LECs cocultured with Tregs, inhibited tumor growth and migration in vitro. Further, we identified protumorigenic chemokines and interferon-stimulated response genes selectively driven by LT{beta}R nonclassical NF{kappa}B in melanoma cells. Endothelial specific genes related to oncogenic process such as SOX18 and FLRT2 were identified to be driven under LT{beta}R nonclassical NF{kappa}B in LECs. Leveraging in vivo Treg LT1{beta}2 interactions with LT{beta}R on tumor and LECs, transfer of WT but not LT-deficient Tregs promoted transplanted WT B16F10 growth and tumor cell-derived CXCL1 and CXCL10 secretion in LT{beta}R-deficient host mice, and increased endothelial specific genes related to tumor angiogenesis and lymphangiogenesis, in WT mice bearing LT{beta}R-depleted melanoma. Selectively blocking LT{beta}R nonclassical NF{kappa}B pathways remarkably suppressed tumor growth and lymphatic metastasis by reducing tumor cell and LEC-derived CXCL1 and CXCL10 production, restricting Treg and myeloid-derived suppressor cell (MDSC) recruitment to tumor. It also retained intratumoral effector T cells, especially IFN{gamma}+ CD8 T cells by restraining Treg facilitated lymphatic vessel permeability. Our data revealed that Treg LT1{beta}2 promotes LT{beta}R nonclassical NF{kappa}B signaling in tumor cells and LECs providing a rational strategy to modulate Treg-mediated protumorigenic molecules to prevent tumor growth and metastasis.

cancer biology↗

bioRxiv2024

Macrophage microRNA-146a is a central regulator of the foreign body response to biomaterial implants

Host recognition and immune-mediated foreign body response (FBR) to biomaterials can adversely affect the functionality of implanted materials. To identify key targets underlying the generation of FBR, here we perform analysis of microRNAs (miR) and mRNAs responses to implanted biomaterials. We found that (a) miR-146a levels inversely affect macrophage accumulation, foreign body giant cell (FBGC) formation, and fibrosis in a murine implant model; (b) macrophage-derived miR-146a is a crucial regulator of the FBR and FBGC formation, as confirmed by global and cell-specific knockout of miR-146a; (c) miR-146a modulates genes related to inflammation, fibrosis, and mechanosensing; (d) miR-146a modulates tissue stiffness near the implant during FBR; and (e) miR-146a is linked to F-actin production and cellular traction force induction, which are vital for FBGC formation. These novel findings suggest that targeting macrophage miR-146a could be a selective strategy to inhibit FBR, potentially improving the biocompatibility of biomaterials.

cell biology↗

bioRxiv2022

Early immunomodulatory program triggered by pro-tolerogenic Bifidobacterium pseudolongum drives cardiac transplant outcomes

BackgroundDespite ongoing improvements in regimens to prevent allograft rejection, most cardiac and other organ grafts eventually succumb to chronic vasculopathy, interstitial fibrosis, or endothelial changes, and eventually graft failure. The events leading to chronic rejection are still poorly understood and the gut microbiota is a known driving force in immune dysfunction. We previously showed that gut microbiota dysbiosis profoundly influences the outcome of vascularized cardiac allografts and subsequently identified biomarker species associated with these differential graft outcomes. MethodsIn this study, we further detailed the multifaceted immunomodulatory properties of pro-tolerogenic and pro-inflammatory bacterial species over time, using our clinically relevant model of allogenic heart transplantation. ResultsIn addition to tracing longitudinal changes in the recipient gut microbiome over time, we observed that Bifidobacterium pseudolongum (Bifido) induced an early anti-inflammatory phenotype within 7 days, while Desulfovibrio desulfuricans (Desulfo) resulted in a pro-inflammatory phenotype, defined by alterations in leukocyte distribution and lymph node (LN) structure. Indeed, in vitro results showed that Bifido and Desulfo acted directly on primary innate immune cells. However, by 40 days after treatment, these two bacterial strains were associated with mixed effects in their impact on LN architecture and immune cell composition and loss of colonization within gut microbiota, despite protection of allografts from inflammation with Bifido treatment. ConclusionsThese dynamic effects suggest a critical role for early microbiota-triggered immunological events such as innate immune cell engagement, T cell differentiation, and LN architectural changes in the subsequent modulation of pro-tolerant versus pro-inflammatory immune responses in organ transplant recipients.

immunology↗

bioRxiv2022

Strain-specific alterations in gut microbiome and host immune responses elicited by Bifidobacterium pseudolongum

The beneficial effects attributed to Bifidobacterium are thought to arise from their host immunomodulatory capabilities, which are likely to be species- and even strain-specific. However, their strain-specificity in direct and indirect immune modulation remain largely uncharacterized. We have shown that B. pseudolongum UMB-MBP-01, a murine isolate, is capable of suppressing inflammation and reducing fibrosis in vivo. To ascertain the mechanism driving this activity and to determine if it is specific to UMB-MBP-01, we compared it to B. pseudolongum type strain ATCC25526 of porcine origin using a combination of in vitro and in vivo experimentation and comparative genomics approaches. Despite many shared features, we demonstrate that these two strains possess distinct genetic repertoires in carbohydrate assimilation, differential activation signatures and cytokine responses in innate immune cells, and differential effects on lymph node morphology with unique local and systemic leukocyte distribution. Importantly, the administration of each B. pseudolongum strain resulted in major divergence in the structure, composition, and function of gut microbiota. This was accompanied by markedly different changes in intestinal transcriptional activities, suggesting strain-specific modulation of the endogenous gut microbiota as a key to host responses of immune modulation and changes in intestinal B. pseudolongum strains. These observations highlight the importance of strain-specificity characteristics of Bifidobacterium for prophylactic supplementation for immune modulation and advance our understanding of the mechanisms which drive the association between Bifidobacterium and health benefit.

microbiology↗