Immunology
Abstract
Despite the rare appearance of potent HIV-neutralizing mAbs in infected individuals requiring prolonged affinity maturation, little is known regarding this process in the majority of viremic individuals. HIV-infected individuals with chronic HIV viremia have elevated numbers of nonconventional tissue-like memory (TLM) B cells that predominate in blood over conventional resting memory (RM) B cells. Accordingly, we investigated affinity maturation in these 2 memory B cell populations. Analysis of IgG-expressing TLM B cells revealed a higher number of cell divisions compared with RM B cells; however, TLM B cells paradoxically displayed significantly lower frequencies of somatic hypermutation (SHM). To assess Ab reactivity in TLM and RM B cells, single-cell cloning was performed on HIV envelope CD4–binding site–sorted (CD4bs-sorted) B cells from 3 individuals with chronic HIV viremia. Several clonal families were present among the 127 cloned recombinant mAbs, with evidence of crosstalk between TLM and RM B cell populations that was largely restricted to non-VH4 families. Despite evidence of common origins, SHM frequencies were significantly decreased in TLM-derived mAbs compared with SHM frequencies in RM-derived mAbs. However, both cell populations had lower frequencies of SHMs than did broadly neutralizing CD4bs–specific mAbs. There was a significant correlation between SHM frequencies and the HIV-neutralizing capacities of the mAbs. Furthermore, HIV neutralization was significantly higher in the RM-derived mAbs compared with that seen in the TLM-derived mAbs, and both SHM frequencies and neutralizing capacity were lowest in TLM-derived mAbs with high polyreactivity. Thus, deficiencies in memory B cells that arise during chronic HIV viremia provide insight into the inadequacy of the Ab response in viremic individuals.
Authors
Eric Meffre, Aaron Louie, Jason Bannock, Leo J.Y. Kim, Jason Ho, Cody C. Frear, Lela Kardava, Wei Wang, Clarisa M. Buckner, Yimeng Wang, Olivia R. Fankuchen, Kathleen R. Gittens, Tae-Wook Chun, Yuxing Li, Anthony S. Fauci, Susan Moir
Abstract
Glioblastomas are highly infiltrated by diverse immune cells, including microglia, macrophages, and myeloid-derived suppressor cells (MDSCs). Understanding the mechanisms by which glioblastoma-associated myeloid cells (GAMs) undergo metamorphosis into tumor-supportive cells, characterizing the heterogeneity of immune cell phenotypes within glioblastoma subtypes, and discovering new targets can help the design of new efficient immunotherapies. In this study, we performed a comprehensive battery of immune phenotyping, whole-genome microarray analysis, and microRNA expression profiling of GAMs with matched blood monocytes, healthy donor monocytes, normal brain microglia, nonpolarized M0 macrophages, and polarized M1, M2a, M2c macrophages. Glioblastoma patients had an elevated number of monocytes relative to healthy donors. Among CD11b+ cells, microglia and MDSCs constituted a higher percentage of GAMs than did macrophages. GAM profiling using flow cytometry studies revealed a continuum between the M1- and M2-like phenotype. Contrary to current dogma, GAMs exhibited distinct immunological functions, with the former aligned close to nonpolarized M0 macrophages.
Authors
Konrad Gabrusiewicz, Benjamin Rodriguez, Jun Wei, Yuuri Hashimoto, Luke M. Healy, Sourindra N. Maiti, Ginu Thomas, Shouhao Zhou, Qianghu Wang, Ahmed Elakkad, Brandon D. Liebelt, Nasser K. Yaghi, Ravesanker Ezhilarasan, Neal Huang, Jeffrey S. Weinberg, Sujit S. Prabhu, Ganesh Rao, Raymond Sawaya, Lauren A. Langford, Janet M. Bruner, Gregory N. Fuller, Amit Bar-Or, Wei Li, Rivka R. Colen, Michael A. Curran, Krishna P. Bhat, Jack P. Antel, Laurence J. Cooper, Erik P. Sulman, Amy B. Heimberger
Abstract
Acute allograft rejection is mediated by host CD8+ cytotoxic T lymphocytes (CTL) targeting graft class I major histocompatibility complex (MHC) molecules. In experimental rodent models, rejection requires differentiation of naive CD8+ T cells into alloreactive CTL within secondary lymphoid organs, whereas in humans, CTL may alternatively develop within the graft from circulating CD8+ effector memory T cells (TEM) that recognize class I MHC molecules on graft endothelial cells (EC). This latter pathway is poorly understood. Here, we show that host CD4+ TEM, activated by EC class II MHC molecules, provide critical help for this process. First, blocking HLA-DR on EC lining human artery grafts in immunodeficient mice reduces CD8+ CTL development within and acute rejection of the artery by adoptively transferred allogeneic human lymphocytes. Second, siRNA knockdown or CRISPR/Cas9 ablation of class II MHC molecules on EC prevents CD4+ TEM from helping CD8+ TEM to develop into CTL in vitro. Finally, implanted synthetic microvessels, formed from CRISPR/Cas9-modified EC lacking class II MHC molecules, are significantly protected from CD8+ T cell–mediated destruction in vivo. We conclude that human CD8+ TEM–mediated rejection targeting graft EC class I MHC molecules requires help from CD4+ TEM cells activated by recognition of class II MHC molecules.
Authors
Parwiz Abrahimi, Lingfeng Qin, William G. Chang, Alfred L.M. Bothwell, George Tellides, W. Mark Saltzman, Jordan S. Pober
Abstract
Renal tubular atrophy and interstitial fibrosis are common hallmarks of etiologically different progressive chronic kidney diseases (CKD) that eventually result in organ failure. Even though these pathological manifestations constitute a major public health problem, diagnostic tests, as well as therapeutic options, are currently limited. Members of the dickkopf (DKK) family, DKK1 and -2, have been associated with inhibition of Wnt signaling and organ fibrosis. Here, we identify DKK3 as a stress-induced, tubular epithelia–derived, secreted glycoprotein that mediates kidney fibrosis. Genetic as well as antibody-mediated abrogation of DKK3 led to reduced tubular atrophy and decreased interstitial matrix accumulation in two mouse models of renal fibrosis. This was facilitated by an amplified, antifibrogenic, inflammatory T cell response and diminished canonical Wnt/β-catenin signaling in stressed tubular epithelial cells. Moreover, in humans, urinary DKK3 levels specifically correlated with the extent of tubular atrophy and interstitial fibrosis in different glomerular and tubulointerstitial diseases. In summary, our data suggest that DKK3 constitutes an immunosuppressive and a profibrotic epithelial protein that might serve as a potential therapeutic target and diagnostic marker in renal fibrosis.
Authors
Giuseppina Federico, Michael Meister, Daniel Mathow, Gunnar H. Heine, Gerhard Moldenhauer, Zoran V. Popovic, Viola Nordström, Annette Kopp-Schneider, Thomas Hielscher, Peter J. Nelson, Franz Schaefer, Stefan Porubsky, Danilo Fliser, Bernd Arnold, Hermann-Josef Gröne
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