Browsing by Subject "immunomodulation"

Now showing 1 - 3 of 3

Open Access
Chitosan polysaccharide suppress toll like receptor dependent immune response
(Turkish Society of Immunology, 2015) Tincer G.; Bayyurt, B.; Arıca, Y.M.; Gürsel İ.
Objectives: Chitosan is a widely used vaccine or anti-cancer delivery vehicle. In this study, we investigated the immunomodulatory effect of chitosan/pIC nanocomplexes on mouse immune cells. Materials and methods: Proliferative and cytotoxic features of chitosan were tested via CCK-8 assay on RAW 264. 7. IL-1β production was assessed via ELISA from PEC supernatants. TNF-α, and NO induction from chitosan treated RAW cells detected by ELISA and Griess assay, respectively. mRNA message levels of TLRs and cytokines on macrophages in response to chitosan/pIC nanocomplex treatments were evaluated by RT-PCR. Results: Results revealed that chitosan is non-toxic to cells, however, proliferative capacities of macrophages were reduced by chitosan administration. Mouse PECs treated with chitosan, led to NLRP3 dependent inflammasome activation as evidenced by dose-dependent IL-1β secretion. Chitosan/pIC nanocomplexes did not improve immunostimulatory action of pIC on RAW cells, since TNF-α and NO productions remained unaltered. Expression levels of several TLRs, CXCL-16 and IFN-α messages from mouse splenocytes were down regulated in response to chitosan/pIC nanocomplex treatment. Conclusion: Our results revealed that chitosan is an anti-proliferative and inflammasome triggering macromolecule on immune cells. Utilization of chitosan as a carrier system is of concern for immunotherapeutic applications. © 2015 Turkish Journal of Immunology.
Open Access
In vitro and in vivo immunomodulatory effects of extracellular vesicles
(2013) Şahin, Mehmet
The major theme of this thesis was to characterize and understand the immunomodulatory potential of extracellular vesicles (EVs) isolated from different mouse and human cell lines on immune cells. To this end, we first purified and characterized the particle nature of exosomes and microparticles (MPs) and exosomes by AFM and DLS analyses. Next, we documented their in vitro or in vivo differential uptake/internalization kinetics by immune cells. Finally, we tested the potential application of EVs as a drug delivery system. The physicochemical characterization studies confirmed that EVs were in vesicular form and upon reconstitution followed by lyophilization they retained their original sizes (i.e. size ranges were 100-150 nm for exosomes, and 250-500 nm for MPs, respectively). MPs derived from mouse cell lines (macrophage, T-cell and fibroblast) were stained and administered in vitro and in vivo to track their internalization by immune cells. When incubated in culture, origins of MPs greatly affected uptake rate and ratio by different immune cells. This differential internalization pattern of distinct MPs was reproduced when they were injected i.p. to mice. When incubated in culture B-cells took up the most MPs from fibroblast origin cells. Macrophages of peritoneal exudate cells took up RAW264.7 derived MPs at the highest level upon 24h post-ip injection. We tested whether MPs have a role in transportation or presentation of bacterial products during an ongoing infection by adhering circulating pathogenic by-products and carrying them to distant immune cells. Our data suggest that MPs could contribute to the severity of ongoing infection in vivo, since MPs from different cells can adhere distinct ligands such as LPS or DNA or even RNA and transmit these ligands to naive innate immune cells augmenting the immunostimulatory response raised against these ligands. Lastly, the immunotherapeutic potential of EVs harboring immunosuppressive synthetic oligodeoxynucleotide sequence namely, A151 was tested following dehydrationrehydration method on mouse splenocytes. EV-associated A151 displayed improved inhibition of immune activation triggered by TLR7/8 and TLR9 ligands on spleen cells. When taken together, this study established that various types of EVs derived from different cells induces plethora of activities on immune cells. Furthermore, EVs are potential drug carrier systems when loaded externally with suitable agents and can be harnessed in immunotherapy of diseases.
Open Access
Peptide nanofibers for engineering tissues and immune system
(2014) Mammadov, Rashad
Interdisciplinary work at the interface of biology and materials science is important for finding cures to complex diseases. Achievements in materials science allow us to control materials at nanoscale and design them according to specific therapeutic purposes. This includes incorporating biophysical and biochemical signals into materials to make them biologically functional. These signals are sensed by cells in normal or pathological cases and influence their decision-making process, which eventually alters cellular behavior. However, cellular environment is so complex in terms of these signals that recapitulating it with synthetic materials is unattainable considering our limited resources. Therefore, we need to distinguish those signals that are structurally simple, but at the same time biologically critical, that would drive cellular behavior to desired outcome. In this thesis, I will describe peptide nanofiber systems for tissue engineering and vaccinology applications. First system is inspired from heparan sulfate (HS) – a natural polymer in extracellular matrix – that bind to growth factors and regulate their functioning, therefore central for induction of various physiological processes. Peptide nanofibers with right composition of bioactive chemical functional groups from HS showed specific interaction with growth factors and induced endothelial cells to form blood vessels similar to natural matrices carrying HS. Considering mentioned features, these peptide nanofibers could be useful for effective regeneration of tissues. Secondly, the peptide nanofiber system carrying pathogenic DNA motives, which is an infection signal, was developed. While non-immunogenic by itself, these nanofibers shifted immune response against pathogenic DNA towards a context that is useful for fighting intracellular pathogens and cancer. Overall, this thesis demonstrates that structurally simple but appropriate biophysical and biochemical signals could be synergistic for inducing desired biological processes at the nanoscale.