Human toll - like receptor 9 (hTLR9) expression and function in haematological and non-haematological malignancies
thesisposted on 15.12.2014, 10:39 by Areej Mashhour Tawfiq Assaf
This thesis addresses the expression and function of human TLR9 in haematological and non-haematological tumour cells. I have shown that most B linage tumour cell lines expressed TLR9, with the exception of myeloma cell lines U266, Karpas 707H and the EBV-lymphoblastoid HMy2 cell line, whereas all non-haematological cell lines tested were negative or very weakly positive. TLR9 positive B-cells/B-cell lines, responded to CpG-ODN activation by activating intracellular signalling pathways, cytokine release, surface marker upregulation and cellular proliferation, whereas TLR9 negative cells did not.;Data on the ability of pre-treatment with low doses of CpG-ODN to induce a refractory state (tolerance) on Burkitt's lymphoma BJAB cells indicates that low doses of CpG-ODN tolerised NF-kappaB activation and, to some extent, cellular proliferation and surface marker upregulation. Moreover, reactivating NF-kappaB on BJAB cells after being tolerised with low dose of CpG-ODN is time dependent with the tolerising effect lasting up to two weeks after a single dose of CpG-ODN.;Finally, inhibiting the signalling pathways (ERK, p38MAPK, PI3K/AKTand NF-kappaB) with selective inhibitors U0126, SB203580, LY294002 and Curcumin respectively, has shown different effects on basal and CpG-ODN activated surface marker expression, cellular proliferation and cytokine release. Furthermore, different signalling pathways mediate different functional effects of CpG-ODN/TLR9 activation, and suggest that ERK and p38 MAPK pathways are involved in CpG-ODN mediated NF-kappaB activation. This work should shed a new light on the mechanisms of action of CpG activation on TLR5 signalling in immune and non-immune cells and on its immunotherapeutic use in the treatment of cancer.