Browsing by Subject "TLRs"

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Open Access
Immunomodulatory effects of exosomes: promising candidates in immunotherapy
(2018-08) Kılgöz, Havva Özgen
Exosomes are type of extracellular vesicles secreted from almost all cell types and carry numerous biological molecules such as nucleic acids, protein and lipids. They mediate many cellular processes including cellular communication and immune responses. Accumulating evidence suggests that these vesicles play a key role in the pathogenesis of inflammatory diseases, infectious diseases and many malignancies. The significant role of exosomes in cellular level also describe their intriguing potential in cancer therapeutics. The primary aim of this thesis is to identify the immunomodulatory roles of distinct exosome species and extend the knowledge of exosome utilization in immunotherapy. The exosomes purified from i) RAW264.7 (murine macrophage-like), ii) EG7 (murine T cell lymphoma), and iii) HUH7 (human hepatocellular carcinoma) had distinct characteristics as well as immunomodulatory features upon murine splenocyte stimulation either alone or in combination with poly(I:C) (a TLR3 ligand), R848(a TLR7/8 ligand), and CpG ODN(a TLR9 ligand). Strikingly, these cell line-derived exosomes displayed changing internalization kinetics by immune cells. Furthermore, the involvement of exosomes in the liver disease progression in the course of Hepatitis B virus (HBV) infection, cirrhosis and hepatocellular carcinoma (HCC) was investigated. As a result of patients’ exosome stimulation assays with healthy peripheral blood mononuclear cells (PBMCs) and murine splenocytes, patient plasma-derived exosomes had inflammatory effects correlated with the severity of liver damage suggesting that these exosomes might have a pathological role in liver disease progression and/or pathogenesis. In the final part, we used a dehydration-rehydration technique enabling external loading of desired Toll-like receptors (TLR) ligand within exosome and liposome. We developed a robust therapeutic vaccine delivery system in which injection of therapeutic vaccine to tumor burden animals enhanced anti-tumor activity and prolonged survival of HCC xenografts. In summary, this approach could broaden the immunotherapeutic utility of exosomes in the clinic.
Open Access
Therapeutic approaches to the prevention of liver fibrosis and cancer progression
(2015-08) Aydın, Muammer Merve
In our previous studies on liver regeneration, we demonstrated that following partial hepatectomy (PH) FLT3 contributes cellular proliferation that provides a basis for liver regeneration. Moreover, we were able to suggest a potential role for FLT3 in hepatocarcinogenesis for the first time. Therefore, we further investigated the effect of FLT3 inhibition on the invasiveness and aggressiveness of hepatocarcinogenesis. Our findings were parallel to our previous results supporting the contribution of FLT3 in hepatocarcinogenesis. Thus, we are presenting FLT3 as a novel candidate for the diagnosis and treatment of HCC. We also focused on liver fibrosis since it is the initial wound healing response generated by the liver against damaging insults. Liver fibrosis is a reversible process, but if its progression is not prevented it might turn into cirrhosis and end up with HCC. Toll-like receptors (TLRs) have been reported to contribute to this fibrotic response generated in the liver resulting from the activating effects of various danger ligands. We show that using suppressive oligodeoxynucleotide (ODN) A151 might control TLR dependent immune activation that takes place after the induction of liver fibrosis. Our results show that suppressive ODN A151 administration has a negative effect on αSMA expression and collagen accumulation, which are the major events taking place during liver fibrogenesis. Additionally, this suppressive effect of suppressive ODN A151 was revealed to be systemic. Splenocytes of suppressive ODN A151 administered mice showed different cytokine secretion patterns and antigen presenting cell (APC) function after being stimulated with various TLR ligands. These findings suggested us that using suppressive ODN might be a rational and novel approach to control the liver fibrogenesis and even prevent its progression into cirrhosis reducing the number of liver transplantations needed by the patients. Finally, we focused on HSPs, some of which are also known to activate TLR signaling. Additionally, HSP27 has a role in actin cytoskeleton organization and controlling cellular motility, which are among the events that take place in liver fibrogenesis. Therefore, for the first time we present preliminary data on the potential role of HSP27 in liver fibrosis and quercetin treatment as a therapeutic approach due to its HSP27 and αSMA expression changing effects.