Effect of in vitro embryo culture and embryo transfer on the expression of toll-like receptor (tlr)-5 in adult mouse lung tissue

Assisted reproductive technologies (ART) are widely used all over the world in the treatment of infertility. In vitro fertilization and embryo transfer are commonly used among ART methods. However, there is evidence suggesting that, compared with spontaneous pregnancies, children born through various ART methods are more susceptible to various health problems including respiratory diseases such as asthma. The innate immune system has created the first line of defense in the host body against pathogens and foreign antigens. Toll- like receptors (TLR) constitute one of the most important components of the innate immune system. Among TLRs, TLR 5 plays an important role in the development of the immune response by recognizing bacterial flagellin. The aim of the present thesis was to investigate whether or not there is any effect of in vitro embryo culture and embryo transfer on the expression of TLR 5 in the adult lung tissue. The present study consists of one Control and one Experimental group. The Experimental group consisted of adults generated by transfer of in vitro-developed blastocysts obtained through in vitro culture of zygotes. The control group was obtained from mating natural cycling females with F1 hybrid males of the same age. To examine the general histological structure of the adult lung tissues isolated from Control and Experimental groups, Crossman's trichrome method was used. Immunohistochemistry and immunofluorescence methods were performed to show expression of TLR 5 in the cells of lung tissue. Real-time PCR and western blott techniques were used to to quantify the espression of TLR 5 at the mRNA and protein levels, respectively. Immunohistochemical analyses demonstrated that TLR 5 is expressed by cells located in the airways, alveol's wall, blood with a similar pattern of expression between the two groups. It was further demonstrated that macrophages, Type 2 pneumocytes and Clara cells are among the cells expressing TLR 5. qRT-PCR results indicated that the level of TLR 5 mRNA is increased 1.03-fold (p> 0.05) in the Experimental group compared with the Control group. Results obtained from western blot analysis showed that expression level of TLR 5 protein was decreased in Experimental group by 1.30-fold (p> 0,05) compared with the Control group. Taken together, results obtained from the present study indicate that TLR 5 is expresed by certain cells in the adult mouse lung tissue including Type II pneumocytes, macrophages and Clara cells and in vitro embryo culture and embryo transfer procedures may alter the immune response in adult lung tissue by changing the expression of TLR 5.