All Publications

  • CD52 Is Elevated on B cells of SLE Patients and Regulates B Cell Function. Frontiers in immunology Bhamidipati, K. n., Silberstein, J. L., Chaichian, Y. n., Baker, M. C., Lanz, T. V., Zia, A. n., Rasheed, Y. S., Cochran, J. R., Robinson, W. H. 2020; 11: 626820


    Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by B cell dysregulation and breaks in tolerance that lead to the production of pathogenic autoantibodies. We performed single-cell RNA sequencing of B cells from healthy donors and individuals with SLE which revealed upregulated CD52 expression in SLE patients. We further demonstrate that SLE patients exhibit significantly increased levels of B cell surface CD52 expression and plasma soluble CD52, and levels of soluble CD52 positively correlate with measures of lupus disease activity. Using CD52-deficient JeKo-1 cells, we show that cells lacking surface CD52 expression are hyperresponsive to B cell receptor (BCR) signaling, suggesting an inhibitory role for the surface-bound protein. In healthy donor B cells, antigen-specific BCR-activation initiated CD52 cleavage in a phospholipase C dependent manner, significantly reducing cell surface levels. Experiments with recombinant CD52-Fc showed that soluble CD52 inhibits BCR signaling in a manner partially-dependent on Siglec-10. Moreover, incubation of unstimulated B cells with CD52-Fc resulted in the reduction of surface immunoglobulin and CXCR5. Prolonged incubation of B cells with CD52 resulted in the expansion of IgD+IgMlo anergic B cells. In summary, our findings suggest that CD52 functions as a homeostatic protein on B cells, by inhibiting responses to BCR signaling. Further, our data demonstrate that CD52 is cleaved from the B cell surface upon antigen engagement, and can suppress B cell function in an autocrine and paracrine manner. We propose that increased expression of CD52 by B cells in SLE represents a homeostatic mechanism to suppress B cell hyperactivity.

    View details for DOI 10.3389/fimmu.2020.626820

    View details for PubMedID 33658999

    View details for PubMedCentralID PMC7917337

  • Immunomodulatory receptors are differentially expressed in B and T cell subsets relevant to autoimmune disease. Clinical immunology (Orlando, Fla.) Murphy, K. A., Bhamidiphati, K. n., Rubin, S. J., Kipp, L. n., Robinson, W. H., Lanz, T. V. 2019: 108276


    Inhibitory cell-surface receptors on lymphocytes, often called immune checkpoints, are powerful targets for cancer therapy. Despite their direct involvement in autoimmune pathology, they are currently not exploited therapeutically for autoimmune diseases. Understanding the receptors' expression patterns in health and disease is essential for targeted drug design. Here, we designed three 23-colour flow cytometry panels for peripheral-blood T cells, including 15 lineage-defining markers and 21 immunomodulatory cell-surface receptors, and a 22-marker panel for B cells. Blood samples from healthy individuals, multiple sclerosis (MS), and lupus (SLE) patients were included in the study. Several receptors show differential expression on regulatory T cells (Treg) compared to T helper (Th) 1 and Th17 cells, and functional relevance of this difference could be shown for BTLA and CD5. Unbiased multiparametric analysis revealed a subset of activated CD8+ T cells and a subset of unswitched memory B cells that are diminished in MS and SLE, respectively.

    View details for DOI 10.1016/j.clim.2019.108276

    View details for PubMedID 31669582

  • Mechanisms that determine nanocarrier targeting to healthy versus inflamed lung regions. Nanomedicine : nanotechnology, biology, and medicine Brenner, J. S., Bhamidipati, K., Glassman, P. M., RAMAKRISHNAN, N., Jiang, D., Paris, A. J., Myerson, J. W., Pan, D. C., Shuvaev, V. V., Villa, C. H., Hood, E. D., Kiseleva, R., Greineder, C. F., Radhakrishnan, R., Muzykantov, V. R. 2017; 13 (4): 1495-1506


    Inflamed organs display marked spatial heterogeneity of inflammation, with patches of inflamed tissue adjacent to healthy tissue. To investigate how nanocarriers (NCs) distribute between such patches, we created a mouse model that recapitulates the spatial heterogeneity of the inflammatory lung disease ARDS. NCs targeting the epitope PECAM strongly accumulated in the lungs, but were shunted away from inflamed lung regions due to hypoxic vasoconstriction (HVC). In contrast, ICAM-targeted NCs, which had lower whole-lung uptake than PECAM/NCs in inflamed lungs, displayed markedly higher NC levels in inflamed regions than PECAM/NCs, due to increased regional ICAM. Regional HVC, epitope expression, and capillary leak were sufficient to predict intra-organ of distribution of NCs, antibodies, and drugs. Importantly, these effects were not observable with traditional spatially-uniform models of ARDS, nor when examining only whole-organ uptake. This study underscores how examining NCs' intra-organ distribution in spatially heterogeneous animal models can guide rational NC design.

    View details for DOI 10.1016/j.nano.2016.12.019

    View details for PubMedID 28065731

  • The Other Function: Class II-Restricted Antigen Presentation by B Cells FRONTIERS IN IMMUNOLOGY Adler, L. N., Jiang, W., Bhamidipati, K., Millican, M., Macaubas, C., Hung, S., Mellins, E. D. 2017; 8


    Mature B lymphocytes (B cells) recognize antigens using their B cell receptor (BCR) and are activated to become antibody-producing cells. In addition, and integral to the development of a high-affinity antibodies, B cells utilize the specialized major histocompatibility complex class II (MHCII) antigen presentation pathway to process BCR-bound and internalized protein antigens and present selected peptides in complex with MHCII to CD4+ T cells. This interaction influences the fate of both types of lymphocytes and shapes immune outcomes. Specific, effective, and optimally timed antigen presentation by B cells requires well-controlled intracellular machinery, often regulated by the combined effects of several molecular events. Here, we delineate and summarize these events in four steps along the antigen presentation pathway: (1) antigen capture and uptake by B cells; (2) intersection of internalized antigen/BCRs complexes with MHCII in peptide-loading compartments; (3) generation and regulation of MHCII/peptide complexes; and (4) exocytic transport for presentation of MHCII/peptide complexes at the surface of B cells. Finally, we discuss modulation of the MHCII presentation pathway across B cell development and maturation to effector cells, with an emphasis on the shaping of the MHCII/peptide repertoire by two key antigen presentation regulators in B cells: HLA-DM and HLA-DO.

    View details for DOI 10.3389/fimmu.2017.00319

    View details for Web of Science ID 000397144900001

    View details for PubMedID 28386257

  • Neutrophils promote alveolar epithelial regeneration by enhancing type II pneumocyte proliferation in a model of acid-induced acute lung injury AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY Paris, A. J., Liu, Y., Mei, J., Dai, N., Guo, L., Spruce, L. A., Hudock, K. M., Brenner, J. S., Zacharias, W. J., Mei, H. D., Slamowitz, A. R., Bhamidipati, K., Beers, M. F., Seeholzer, S. H., Morrisey, E. E., Worthen, G. S. 2016; 311 (6): L1062-L1075


    Alveolar epithelial regeneration is essential for resolution of the acute respiratory distress syndrome (ARDS). Although neutrophils have traditionally been considered mediators of epithelial damage, recent studies suggest they promote type II pneumocyte (AT2) proliferation, which is essential for regenerating alveolar epithelium. These studies did not, however, evaluate this relationship in an in vivo model of alveolar epithelial repair following injury. To determine whether neutrophils influence alveolar epithelial repair in vivo, we developed a unilateral acid injury model that creates a severe yet survivable injury with features similar to ARDS. Mice that received injections of the neutrophil-depleting Ly6G antibody had impaired AT2 proliferation 24 and 72 h after acid instillation, which was associated with decreased reepithelialization and increased alveolar protein concentration 72 h after injury. As neutrophil depletion itself may alter the cytokine response, we questioned the contribution of neutrophils to alveolar epithelial repair in neutropenic granulocyte-colony stimulating factor (G-CSF)-/- mice. We found that the loss of G-CSF recapitulated the neutrophil response of Ly6G-treated mice and was associated with defective alveolar epithelial repair, similar to neutrophil-depleted mice, and was reversed by administration of exogenous G-CSF. To approach the mechanisms, we employed an unbiased protein analysis of bronchoalveolar lavage fluid from neutrophil-depleted and neutrophil-replete mice 12 h after inducing lung injury. Pathway analysis identified significant differences in multiple signaling pathways that may explain the differences in epithelial repair. These data emphasize an important link between the innate immune response and tissue repair in which neutrophils promote alveolar epithelial regeneration.

    View details for DOI 10.1152/ajplung.00327.2016

    View details for Web of Science ID 000389642700004

    View details for PubMedID 27694472

    View details for PubMedCentralID PMC5206401