Ebola virus (EBOV) is a member of the Filoviridae family of highly pathogenic viruses that cause severe hemorrhagic fever and is the causative agent of the 2014 West Africa outbreak. Currently, there are no approved filovirus vaccines or treatments to combat these sporadic and deadly epidemics. One target for EBOV antiviral therapy is to block viral entry into host cells. Recently, phosphatidylserine (PtdSer) receptors, primarily known for their involvement in the clearance of dying cells, were shown to mediate entry of enveloped viruses including filoviruses. The PtdSer receptors, T-cell immunoglobulin mucin domain-1 (TIM-1) and family member TIM-4, serve as filovirus receptors, significantly enhancing EBOV entry. TIM-dependent virus uptake occurs via apoptotic mimicry by binding to PtdSer on the surface of virions through a conserved PtdSer binding pocket within the amino terminal IgV domain. TIM-4 is expressed on antigen presenting cells (APCs), including macrophages and dendritic cells (DCs), which are critical in early EBOV infection. My studies are the first to define the molecular details of virion/TIM-4 interactions and establish the importance of TIM-4 for EBOV infection of murine resident peritoneal macrophages. In addition, previous work has utilized only in vitro models to establish the importance of the TIM proteins in EBOV entry. My studies are the first to demonstrate the importance of TIM-1 and TIM-4 for in vivo EBOV pathogenesis and to confirm them as relevant targets of future filovirus therapeutics. Macrophage phenotypes can vary greatly depending upon chemokine and cytokine signals from their microenvironment. Historically, macrophages have been classified into two major subgroups: classically activated macrophages (M1) and alternatively activated macrophages (M2). Macrophages are a critical early target of EBOV infection and my work primarily focused on interferon gamma-stimulated (M1) macrophages since this treatment profoundly inhibited EBOV infection of human and murine macrophages. Interferon gamma treatment blocked EBOV replication in macrophages, reducing viral RNA levels in a manner similar to that observed when cultures were treated with the protein synthesis inhibitor, cycloheximide. Microarray studies with interferon gamma-treated human macrophages identified more than 160 interferon-stimulated genes. Ectopic expression of a select group of these genes inhibited EBOV infection. These studies provide new potential avenues for antiviral targeting as these genes that have not previously appreciated to inhibit infection of negative strand RNA viruses including EBOV. In addition and most exciting, using MA-EBOV, we found that murine interferon gamma, when administered either 24 hours before or after infection, protects lethally challenged mice and significantly reduces morbidity. Our findings suggest that interferon gamma, an FDA-approved drug, may serve as a novel and effective prophylactic or treatment option.

<p>Inflammatory Bowel Disease (IBD) is a chronic intestinal inflammation that has caused many challenges for healthcare providers in treating the disease and also altered the quality of life of the patients. The cure for IBD is still symptomatic-based; the causes mechanism and pathogenesis of IBD are to be further investigated. Currently, IBD has been considered as an excessive immune response to commensal flora that in normal condition is tolerable to the host. Antigen presenting cells (APCs) play an important role in the pathogenesis of IBD. Macrophage is one of the professional APCs that present antigen information to T cells and induce the T cell subtype proliferation. Aside from this role, macrophages also phagocytose pathogens and clean cell debris in thebody.</p> <p>T cell immunoglobulin and mucin domain (TIM)-4 is a glycoprotein expressed on the surface of macrophage, which recognizes phosphatidylserine (PS) that is expressed mainly on the surface of the early apoptotic cell phospholipid membrane; the latter is a negatively charged molecule that can bind to the TIM-4 to enhance the phagocytosing activity. In IBD, the loss of intestinal epithelial cells (IECs) due to apoptosis is prominent in the site of inflammation especially in ulcerative colitis (UC).</p> <p>The aim of this study is to elucidate whether there is an increase of TIM-4 expression in colitis mice model after exposure to excessive number of apoptotic IECs and whether TIM-4 plays a role in the development of colitis in mice.</p> <p>The expression of TIM-4 is measured with several tests; including flow cytometry, immunohistochemistry, western blotting and real time RT-PCR. In the first step, we tried to see if there is a difference in the TIM-4 expression in colitis mice and ethanol control mice. After the association was established, we further observed the role of TIM-4 in the pathogenesis of IBD by injecting TIM-4+ macrophages into the mice prior to inducing a mild colitis in the mice and finally injected neutralizing anti TIM-4 antibodies to block the available TIM-4 receptors.</p> <p>We found that TIM-4 expression was higher in a colitis mouse model compared to the control. Also by injecting TIM-4+ macrophages into the mice, the frequency of intestinal T regulatory (Treg) cells was decreased significantly. Finally in the group treated with anti-TIM-4 neutralizing antibodies prior to colitis induction, the frequency of intestinal Treg cells increased significantly and the inflammation response was less severe than the colitis control group. This study revealed, for the first time in the world, that TIM-4 expression in the colon of colitis mice was significantly increased, which suppressed Tregs and promoted T effector cells.</p> / Master of Science in Medical Sciences (MSMS)