Kathy Mu

Bio: Kathy Mu is an academic researcher from Rockefeller University. The author has contributed to research in topics: Hepatitis C virus & Haematopoiesis. The author has an hindex of 4, co-authored 4 publications receiving 841 citations. Previous affiliations of Kathy Mu include National Institutes of Health.

A genetically humanized mouse model for hepatitis C virus infection

Abstract: Hepatitis C virus (HCV) remains a major medical problem. Antiviral treatment is only partially effective and a vaccine does not exist. Development of more effective therapies has been hampered by the lack of a suitable small animal model. Although xenotransplantation of immunodeficient mice with human hepatocytes has shown promise, these models are subject to important challenges. Building on the previous observation that CD81 and occludin comprise the minimal human factors required to render mouse cells permissive to HCV entry in vitro, we attempted murine humanization via a genetic approach. Here we show that expression of two human genes is sufficient to allow HCV infection of fully immunocompetent inbred mice. We establish a precedent for applying mouse genetics to dissect viral entry and validate the role of scavenger receptor type B class I for HCV uptake. We demonstrate that HCV can be blocked by passive immunization, as well as showing that a recombinant vaccinia virus vector induces humoral immunity and confers partial protection against heterologous challenge. This system recapitulates a portion of the HCV life cycle in an immunocompetent rodent for the first time, opening opportunities for studying viral pathogenesis and immunity and comprising an effective platform for testing HCV entry inhibitors in vivo.

Persistent hepatitis C virus infection in microscale primary human hepatocyte cultures

Abstract: Hepatitis C virus (HCV) remains a major public health problem, affecting approximately 130 million people worldwide. HCV infection can lead to cirrhosis, hepatocellular carcinoma, and end-stage liver disease, as well as extrahepatic complications such as cryoglobulinemia and lymphoma. Preventative and therapeutic options are severely limited; there is no HCV vaccine available, and nonspecific, IFN-based treatments are frequently ineffective. Development of targeted antivirals has been hampered by the lack of robust HCV cell culture systems that reliably predict human responses. Here, we show the entire HCV life cycle recapitulated in micropatterned cocultures (MPCCs) of primary human hepatocytes and supportive stroma in a multiwell format. MPCCs form polarized cell layers expressing all known HCV entry factors and sustain viral replication for several weeks. When coupled with highly sensitive fluorescence- and luminescence-based reporter systems, MPCCs have potential as a high-throughput platform for simultaneous assessment of in vitro efficacy and toxicity profiles of anti-HCV therapeutics.

Splicing Diversity of the Human OCLN Gene and Its Biological Significance for Hepatitis C Virus Entry

Abstract: Persistent hepatitis C virus (HCV) infection is a primary etiological factor for the development of chronic liver disease, including cirrhosis and cancer. A recent study identified occludin (OCLN), an integral tight junction protein, as one of the key factors for HCV entry into cells. We explored the splicing diversity of OCLN in normal human liver and observed variable expression of alternative splice variants, including two known forms (WT-OCLN and OCLN-ex4del) and six novel forms (OCLN-ex7ext, OCLN-ex3pdel, OCLN-ex3del, OCLN-ex3-4del, OCLN-ex3p-9pdel, and OCLN-ex3p-7pdel). Recombinant protein isoforms WT-OCLN and OCLN-ex7ext, which retained the HCV-interacting MARVEL domain, were expressed on the cell membrane and were permissive for HCV infection in in vitro infectivity assays. All other forms lacked the MARVEL domain, were expressed in the cytoplasm, and were nonpermissive for HCV infection. Additionally, we observed variable expression of OCLN splicing forms across human tissues and cell lines. Our study suggests that the remarkable natural splicing diversity of OCLN might contribute to HCV tissue tropism and possibly modify the outcome of HCV infection in humans. Genetic factors crucial for regulation of OCLN expression and susceptibility to HCV infection remain to be elucidated.

Microfluidic organs-on-chips

Abstract: Organ-level physiology is recapitulated in vitro by culturing cells in perfused, microfluidic devices.

Monocyte-derived IL-1 and IL-6 are differentially required for cytokine-release syndrome and neurotoxicity due to CAR T cells

Abstract: In the clinic, chimeric antigen receptor-modified T (CAR T) cell therapy is frequently associated with life-threatening cytokine-release syndrome (CRS) and neurotoxicity. Understanding the nature of these pathologies and developing treatments for them are hampered by the lack of appropriate animal models. Herein, we describe a mouse model recapitulating key features of CRS and neurotoxicity. In humanized mice with high leukemia burden, CAR T cell-mediated clearance of cancer triggered high fever and elevated IL-6 levels, which are hallmarks of CRS. Human monocytes were the major source of IL-1 and IL-6 during CRS. Accordingly, the syndrome was prevented by monocyte depletion or by blocking IL-6 receptor with tocilizumab. Nonetheless, tocilizumab failed to protect mice from delayed lethal neurotoxicity, characterized by meningeal inflammation. Instead, the IL-1 receptor antagonist anakinra abolished both CRS and neurotoxicity, resulting in substantially extended leukemia-free survival. These findings offer a therapeutic strategy to tackle neurotoxicity and open new avenues to safer CAR T cell therapies.

Human CD141(+) (BDCA-3)(+) dendritic cells (DCs) represent a unique myeloid DC subset that cross-presents necrotic cell antigens

Abstract: The characterization of human dendritic cell (DC) subsets is essential for the design of new vaccines. We report the first detailed functional analysis of the human CD141(+) DC subset. CD141(+) DCs are found in human lymph nodes, bone marrow, tonsil, and blood, and the latter proved to be the best source of highly purified cells for functional analysis. They are characterized by high expression of toll-like receptor 3, production of IL-12p70 and IFN-beta, and superior capacity to induce T helper 1 cell responses, when compared with the more commonly studied CD1c(+) DC subset. Polyinosine-polycytidylic acid (poly I:C)-activated CD141(+) DCs have a superior capacity to cross-present soluble protein antigen (Ag) to CD8(+) cytotoxic T lymphocytes than poly I:C-activated CD1c(+) DCs. Importantly, CD141(+) DCs, but not CD1c(+) DCs, were endowed with the capacity to cross-present viral Ag after their uptake of necrotic virus-infected cells. These findings establish the CD141(+) DC subset as an important functionally distinct human DC subtype with characteristics similar to those of the mouse CD8 alpha(+) DC subset. The data demonstrate a role for CD141(+) DCs in the induction of cytotoxic T lymphocyte responses and suggest that they may be the most relevant targets for vaccination against cancers, viruses, and other pathogens.

Humanized mice for immune system investigation: progress, promise and challenges.

Abstract: Significant advances in our understanding of the in vivo functions of human cells and tissues and the human immune system have resulted from the development of 'humanized' mouse strains that are based on severely immunodeficient mice with mutations in the interleukin-2 receptor common γ-chain locus. These mouse strains support the engraftment of a functional human immune system and permit detailed analyses of human immune biology, development and functions. In this Review, we discuss recent advances in the development and utilization of humanized mice, the lessons learnt, the remaining challenges and the promise of using humanized mice for the in vivo study of human immunology.