Azam Mohsin

All Publications

• The immune microenvironment of transplant glomerulitis Kidney International Reports Bracey, N., Maltzman, J., Long, A., Dhanasekaran, R., Shankar, V., Mohsin, A., Kambham, N., Wernig, G., Gentles, A., Davis, M., Charu, V. 2025: 3113-3127

  Abstract

  Transplant glomerulitis is a morphological lesion seen in kidney allograft rejection that is associated with poor outcomes; however, little is known about how immune cells infiltrate and organize specifically within glomeruli.We used Co-Detection by Indexing (CODEX) multifluorescent imaging to measure 52 protein markers in a retrospective cohort of 41 human allograft nephrectomies (ANs) and evaluated the immunological landscape of transplant glomerulitis.Characterization of 18 cell types identified diverse immune cells within inflamed glomeruli, with unique phenotypes and compositions compared with the extraglomerular microenvironment. Immunological phenotypes were conserved across glomeruli within individuals and associated with the general state of injury, with M1 macrophages and effector CD8 T cells associated with mild inflammation. Distance-based spatial analysis further revealed a profibrotic community composed of M2 macrophages, memory CD8 T cells and exhausted CD8 T cells surrounding endothelial cell hubs. These interaction networks were associated with regions of adverse glomerular remodeling, expression of profibrotic proteins, and were more prevalent in individuals with C4d-positive rejection.These results implicate distinct cell-cell interactions as hallmarks of alloimmune injury and chronic remodeling during transplant glomerulitis and may give rise to new tools for histological risk assessment of clinical rejection syndromes.

  View details for DOI 10.1016/j.ekir.2025.06.015

  View details for PubMedCentralID PMC12446868

• Age-dependent cytokine surge in blood precedes cancer diagnosis. Proceedings of the National Academy of Sciences of the United States of America Chen, G., Mohsin, A., Zheng, H., Rosenberg-Hasson, Y., Padilla, C., Sarin, K. Y., Dekker, C. L., Grant, P., Maecker, H. T., Lu, Y., Furman, D., Shen-Orr, S., Khatri, P., Davis, M. M. 2025; 122 (12): e2420502122

  Abstract

  Aging is associated with increased variability and dysregulation of the immune system. We performed a system-level analysis of serum cytokines in a longitudinal cohort of 133 healthy individuals over 9 y. We found that cancer incidence is a major contributor to increased cytokine abundance variability. Circulating cytokines increase up to 4 y before a cancer diagnosis in subjects with age over 80 y. We also analyzed cytokine expression in 10 types of early-stage cancers from The Cancer Genome Atlas. We found that a similar set of cytokines is upregulated in tumor tissues, specifically after the age of 80 y. Similarly, cellular senescence activity and CDKN1A/p21 expression increase with age in cancer tissues. Finally, we demonstrated that the cytokine levels in serum can be used to predict cancers among subjects age at 80+ y. Our results suggest that latent senescent cancers contribute to age-related chronic inflammation.

  View details for DOI 10.1073/pnas.2420502122

  View details for PubMedID 40117305

• BRWD1 orchestrates small pre-B cell chromatin topology by converting static to dynamic cohesin. Nature immunology Mandal, M., Maienschein-Cline, M., Hu, Y., Mohsin, A., Veselits, M. L., Wright, N. E., Okoreeh, M. K., Yoon, Y. M., Veselits, J., Georgopoulos, K., Clark, M. R. 2023

  Abstract

  Lymphocyte development consists of sequential and mutually exclusive cell states of proliferative selection and antigen receptor gene recombination. Transitions between each state require large, coordinated changes in epigenetic landscapes and transcriptional programs. How this occurs remains unclear. Here we demonstrate that in small pre-B cells, the lineage and stage-specific epigenetic reader bromodomain and WD repeat-containing protein 1 (BRWD1) reorders three-dimensional chromatin topology to affect the transition between proliferative and gene recombination molecular programs. BRWD1 regulated the switch between poised and active enhancers interacting with promoters, and coordinated this switch with Igk locus contraction. BRWD1 did so by converting chromatin-bound static to dynamic cohesin competent to mediate long-range looping. ATP-depletion revealed cohesin conversion to be the main energetic mechanism dictating dynamic chromatin looping. Our findings provide a new mechanism of cohesin regulation and reveal how cohesin function can be dictated by lineage contextual mechanisms to facilitate specific cell fate transitions.

  View details for DOI 10.1038/s41590-023-01666-z

  View details for PubMedID 37985858

  View details for PubMedCentralID 6155124

• Tcf-1 promotes genomic instability and T cell transformation in response to aberrant β-catenin activation. Proceedings of the National Academy of Sciences of the United States of America Arnovitz, S., Mathur, P., Tracy, M., Mohsin, A., Mondal, S., Quandt, J., Hernandez, K. M., Khazaie, K., Dose, M., Emmanuel, A. O., Gounari, F. 2022; 119 (32): e2201493119

  Abstract

  Understanding the mechanisms promoting chromosomal translocations of the rearranging receptor loci in leukemia and lymphoma remains incomplete. Here we show that leukemias induced by aberrant activation of β-catenin in thymocytes, which bear recurrent Tcra/Myc-Pvt1 translocations, depend on Tcf-1. The DNA double strand breaks (DSBs) in the Tcra site of the translocation are Rag-generated, whereas the Myc-Pvt1 DSBs are not. Aberrantly activated β-catenin redirects Tcf-1 binding to novel DNA sites to alter chromatin accessibility and down-regulate genome-stability pathways. Impaired homologous recombination (HR) DNA repair and replication checkpoints lead to retention of DSBs that promote translocations and transformation of double-positive (DP) thymocytes. The resulting lymphomas, which resemble human T cell acute lymphoblastic leukemia (T-ALL), are sensitive to PARP inhibitors (PARPis). Our findings indicate that aberrant β-catenin signaling contributes to translocations in thymocytes by guiding Tcf-1 to promote the generation and retention of replication-induced DSBs allowing their coexistence with Rag-generated DSBs. Thus, PARPis could offer therapeutic options in hematologic malignancies with active Wnt/β-catenin signaling.

  View details for DOI 10.1073/pnas.2201493119

  View details for PubMedID 35921443

  View details for PubMedCentralID PMC9371646

• Asymmetrical forward and reverse developmental trajectories determine molecular programs of B cell antigen receptor editing. Science immunology Okoreeh, M. K., Kennedy, D. E., Emmanuel, A. O., Veselits, M., Moshin, A., Ladd, R. H., Erickson, S., McLean, K. C., Madrigal, B., Nemazee, D., Maienschein-Cline, M., Mandal, M., Clark, M. R. 2022; 7 (74): eabm1664

  Abstract

  During B lymphopoiesis, B cell progenitors progress through alternating and mutually exclusive stages of clonal expansion and immunoglobulin (Ig) gene rearrangements. Great diversity is generated through the stochastic recombination of Ig gene segments encoding heavy and light chain variable domains. However, this commonly generates autoreactivity. Receptor editing is the predominant tolerance mechanism for self-reactive B cells in the bone marrow (BM). B cell receptor editing rescues autoreactive B cells from negative selection through renewed light chain recombination first at Igκ then Igλ loci. Receptor editing depends on BM microenvironment cues and key transcription factors such as NF-κB, FOXO, and E2A. The specific BM factor required for receptor editing is unknown. Furthermore, how transcription factors coordinate these developmental programs to promote usage of the λ chain remains poorly defined. Therefore, we used two mouse models that recapitulate pathways by which Igλ light chain-positive B cells develop. The first has deleted J kappa (Jκ) genes and hence models Igλ expression resulting from failed Igκ recombination (Igκdel). The second models autoreactivity by ubiquitous expression of a single-chain chimeric anti-Igκ antibody (κ-mac). Here, we demonstrated that autoreactive B cells transit asymmetric forward and reverse developmental trajectories. This imparted a unique epigenetic landscape on small pre-B cells, which opened chromatin to transcription factors essential for Igλ recombination. The consequences of this asymmetric developmental path were both amplified and complemented by CXCR4 signaling. These findings reveal how intrinsic molecular programs integrate with extrinsic signals to drive receptor editing.

  View details for DOI 10.1126/sciimmunol.abm1664

  View details for PubMedID 35930652

  View details for PubMedCentralID PMC9636592

• Wnt-β-catenin activation epigenetically reprograms Treg cells in inflammatory bowel disease and dysplastic progression. Nature immunology Quandt, J., Arnovitz, S., Haghi, L., Woehlk, J., Mohsin, A., Okoreeh, M., Mathur, P. S., Emmanuel, A. O., Osman, A., Krishnan, M., Morin, S. B., Pearson, A. T., Sweis, R. F., Pekow, J., Weber, C. R., Khazaie, K., Gounari, F. 2021; 22 (4): 471-484

  Abstract

  The diversity of regulatory T (Treg) cells in health and in disease remains unclear. Individuals with colorectal cancer harbor a subpopulation of RORγt+ Treg cells with elevated expression of β-catenin and pro-inflammatory properties. Here we show progressive expansion of RORγt+ Treg cells in individuals with inflammatory bowel disease during inflammation and early dysplasia. Activating Wnt-β-catenin signaling in human and murine Treg cells was sufficient to recapitulate the disease-associated increase in the frequency of RORγt+ Treg cells coexpressing multiple pro-inflammatory cytokines. Binding of the β-catenin interacting partner, TCF-1, to DNA overlapped with Foxp3 binding at enhancer sites of pro-inflammatory pathway genes. Sustained Wnt-β-catenin activation induced newly accessible chromatin sites in these genes and upregulated their expression. These findings indicate that TCF-1 and Foxp3 together limit the expression of pro-inflammatory genes in Treg cells. Activation of β-catenin signaling interferes with this function and promotes the disease-associated RORγt+ Treg phenotype.

  View details for DOI 10.1038/s41590-021-00889-2

  View details for PubMedID 33664518

  View details for PubMedCentralID PMC8262575

• Machine Learning to Quantify In Situ Humoral Selection in Human Lupus Tubulointerstitial Inflammation. Frontiers in immunology Kinloch, A. J., Asano, Y., Mohsin, A., Henry, C., Abraham, R., Chang, A., Labno, C., Wilson, P. C., Clark, M. R. 2020; 11: 593177

  Abstract

  In human lupus nephritis, tubulointerstitial inflammation (TII) is associated with in situ expansion of B cells expressing anti-vimentin antibodies (AVAs). The mechanism by which AVAs are selected is unclear. Herein, we demonstrate that AVA somatic hypermutation (SHM) and selection increase affinity for vimentin. Indeed, germline reversion of several antibodies demonstrated that higher affinity AVAs can be selected from both low affinity B cell germline clones and even those that are strongly reactive with other autoantigens. While we demonstrated affinity maturation, enzyme-linked immunosorbent assays (ELISAs) suggested that affinity maturation might be a consequence of increasing polyreactivity or even non-specific binding. Therefore, it was unclear if there was also selection for increased specificity. Subsequent multi-color confocal microscopy studies indicated that while TII AVAs often appeared polyreactive by ELISA, they bound selectively to vimentin fibrils in whole cells or inflamed renal tissue. Using a novel machine learning pipeline (CytoSkaler) to quantify the cellular distribution of antibody staining, we demonstrated that TII AVAs were selected for both enhanced binding and specificity in situ. Furthermore, reversion of single predicted amino acids in antibody variable regions indicated that we could use CytoSkaler to capture both negative and positive selection events. More broadly, our data suggest a new approach to assess and define antibody polyreactivity based on quantifying the distribution of binding to native and contextually relevant antigens.

  View details for DOI 10.3389/fimmu.2020.593177

  View details for PubMedID 33329582

  View details for PubMedCentralID PMC7731665

• Antibodies in cerebral cavernous malformations react with cytoskeleton autoantigens in the lesional milieu. Journal of autoimmunity Zhang, D., Kinloch, A. J., Srinath, A., Shenkar, R., Girard, R., Lightle, R., Moore, T., Koskimäki, J., Mohsin, A., Carrión-Penagos, J., Romanos, S., Shen, L., Clark, M. R., Shi, C., Awad, I. A. 2020; 113: 102469

  Abstract

  Previous studies have reported robust inflammatory cell infiltration, synthesis of IgG, B-cell clonal expansion, deposition of immune complexes and complement within cerebral cavernous malformation (CCM) lesions. B-cell depletion has also been shown to reduce the maturation of CCM in murine models. We hypothesize that antigen(s) within the lesional milieu perpetuate the pathogenetic immune responses in CCMs. This study aims to identify those putative antigen(s) using monoclonal antibodies (mAbs) derived from plasma cells found in surgically removed human CCM lesions. We produced human mAbs from laser capture micro-dissected plasma cells from four CCM patients, and also germline-reverted versions. CCM mAbs were assayed using immunofluorescence on central nervous system (CNS) tissues and immunocytochemistry on human primary cell lines. Antigen characterization was performed using a combination of confocal microscopy, immunoprecipitation and mass spectrometry. Affinity was determined by enzyme-linked immunosorbent assay, and specificity by multi-color confocal microscopy and quantitative co-localization. CCM mAbs bound CNS tissue, especially endothelial cells and astrocytes. Non-muscle myosin heavy chain IIA (NMMHCIIA), vimentin and tubulin are three cytoskeleton proteins that were commonly targeted. Selection of cytoskeleton proteins by plasma cells was supported by a high frequency of immunoglobulin variable region somatic hypermutations, high affinity and selectivity of mAbs in their affinity matured forms, and profoundly reduced affinity and selectivity in the germline reverted forms. Antibodies produced by plasma cells in CCM lesions commonly target cytoplasmic and cytoskeletal autoantigens including NMMHCIIA, vimentin and tubulin that are abundant in endothelial cells and astrocytes. Binding to, and selection on autoantigen(s) in the lesional milieu likely perpetuates the pathogenetic immune response in CCMs. Blocking this in situ autoimmune response may yield a novel treatment for CCM.

  View details for DOI 10.1016/j.jaut.2020.102469

  View details for PubMedID 32362501

  View details for PubMedCentralID PMC7483292