Epitel Hücre Kökenli Serpınb1'in Nötrofil Elastaz İlişkili Anti-Apoptotik ve Pro- Apoptotik Yolaklar Üzerine Etkisi
Özet
Asthma is a chronic inflammatory lung disease that significantly impacts the quality of life of people of all ages. Shortness of breath, coughing, and chest tightness in the airway are common symptoms in sensitive people. While hereditary factors may play a role in airway obstruction in asthma, other stimuli such as particular allergens, cigarette smoke, and air pollution may also be effective. Although airway obstruction occurs in different phases, inflammatory cells such as neutrophils, eosinophils, and mast cells contribute to the disease's pathophysiology.
As the asthma response has heterogenic nature, it is also possible to divide them into eosinophilic and neutrophilic (non-eosinophilic). It is known that neutrophils occupy an essential place in the course of the disease in the pathology of neutrophilic asthma. By transmigrating from the vascular area to the inflamed tissues, neutrophils attempt to eliminate the response caused by the effects of biological or chemical substances. Proteases and reactive oxygen species with cytotoxic effects that neutrophils store in their specialized granules are critical molecules for neutrophils to perform this function. Although the interaction of airway epithelial cells and neutrophils affects the existing pathogen or chemical, the progressive increase in neutrophil numbers harms the host by disrupting the balance of proteases and anti-proteases. Proteolytic enzymes, including NE and MMP-9, play essential roles in airway remodeling and repair.
The uncontrolled release of antimicrobial proteins with strong cytotoxic effects such as neutrophil elastase, cathepsin G, proteinase 3 stored in the azurophilic granules of neutrophil causes cellular destruction. Studies have shown that neutrophil elastase activates intracellular signaling pathways and causes tissue damage. Against the effects of uncontrolled release of proteases in specialized compartments of neutrophils, there are various proteins with anti-proteolytic activity in the cytoplasm. The leukocyte elastase inhibitor SERPINB1, which has anti-protease properties in the cytoplasm and is responsible for the inhibition of these proteases, protects against the effects of uncontrolled protease release in specific parts of neutrophils. Furthermore, SERPINB1 has been shown to have pro-apoptotic and anti-apoptotic effects by regulating molecules involved in various death pathways, such as caspases, via the activation or inhibition of intracellular signaling pathways as well as anti-protease activities. It is also seen that SERPINB1 may have a direct or indirect decisive role in determining the fate of the cell. The fact that SERPINs are metastable molecules and contain many regions open to conformational change can encourage the emergence of different activities by interacting with other molecules. It has been shown that during cellular stress, SERPINB1 loses its anti-protease activity by undergoing conformational changes as a result of protease attacks on the P1-P1 region and translocates to the nucleus by gaining endonuclease activity. This new molecule is called L-DNase II (DNase II derived from leukocyte elastase inhibitor) with the change in its activity. L-DNase II, translocated to the nucleus, cleaves DNA into oligonucleosomes and leads the cell to apoptosis (programmed cell death). DNases have an essential place in apoptosis studies. Therefore, the function of L-Dnase II molecule in NE-related apoptotic pathways needs to be clarified. However, information on the relationship between neutrophil inflammation and epithelial cells of this pathway, which starts with proteases, is limited in the literature.
Within the scope of this thesis, the pro-and anti-apoptotic effects of SERPINB1 in relation to neutrophil elastase were investigated at the RNA and protein level by differentiation of bronchial epithelial cells (BEAS-2B) by the ALI-culture method. It was shown that the stimulation of BEAS-2B cells with increasing concentrations of neutrophil elastase-induced apoptosis. The dose(s) to specifically activate the LEI/L-DNase II pathway was decided. Consistent with the literature, it was revealed that there was no significant change in Caspase-3, Caspase-8, and Caspase-9 molecules at protein and gene levels. As a result of analyzes at the protein level, it was determined that neutrophil elastase revealed forms of SERPINB1 with different molecular weights. In addition, it was found that the amount of SERPINB1 in the cytosolic and nuclear sections of epithelial cells changes with neutrophil elastase stimulation.
