MicroRNAs (miRNAs) are small noncoding conserved RNAs containing 19 to 24 nucleotides that are regulators of post-translational modifications and are involved in the majority of biological processes such as immune homeostasis, T helper cell differentiation, central and peripheral tolerance, and immune cell development. Autoimmune diseases are characterized by immune system dysregulation, which ultimately leads to destructive responses to self-antigens. A large body of literature suggests that autoimmune diseases and immune dysregulation are associated with different miRNA expression changes in the target cells and tissues of adaptive or innate immunity. miR-155 is identified as a critical modulator of immune responses. Recently conducted studies on the expression profile of miR-155 suggest that the altered expression and function of miR-155 can mediate vulnerability to autoimmune diseases and cause significant dysfunction of the immune system.
Systemic sclerosis is a fibrotic autoimmune disease in which aberrant remodeling of the extracellular matrix in organs disturbs their functionalities. The aim of this study was to investigate the expression of gelatinases on systemic sclerosis. Consequently, a mouse model of systemic sclerosis was employed and the gelatinolytic activity of gelatinases was evaluated on the fibrotic tissues of this model. Two groups of ten mice were considered in this work: a group of systemic sclerosis model and control group. For the generation of systemic sclerosis model, mice received bleomycin, while the control group was subjected to phosphate buffered saline (PBS) reception. Mice were tested for fibrosis by using trichrome staining, hydroxyproline measurement and α-SMA detection in tissue sections. Additionally, the gelatinolytic activity of matrix metalloproteinase 2 and matrix metalloproteinase 9 were measured using gelatin zymography in lungs and skin tissue homogenates. The obtained results indicated that subcutaneous injection of bleomycin-induced fibrosis in skin and lung tissues of mice. Pro and active forms of matrix methaloproteinase 9 were increased in fibrotic lung tissues (p<0.05 and p<0.01, respectively), while, the gelatinolytic activity of MMP2 was unaffected in these tissues. Additionally, in skin tissues of bleomycin-treated animals, both pro and active forms of MMP9 and MMP2 were increased (p<0.05). Pro and active forms of gelatinases increase differently in skin and lung tissues of bleomycin-induced scleroderma.
Systemic sclerosis is a female predominant, a fibrotic autoimmune disease in which disturbance in tissue homeostasis and cell turnover including cell apoptosis are central events in pathogenesis. Sex hormones are known as the important players in sexual dimorphism of autoimmune diseases and in tissue homeostasis. Progesterone influences autoimmune disease via its immunomodulatory effect or by its direct action on parenchymal cell function. On the other hand, this hormone impacts tissue homeostasis by acting on cell apoptosis in a different situation. The objective of this study was to examine the effect of progesterone on cellular apoptosis of skin and lung tissues in a mouse model of scleroderma. Four group of mice were involved in this study with 10 mice in each. The fibrotic model was induced by daily subcutaneous injection of bleomycin for 28 days. One week after initiation of fibrosis induction, mice received subcutaneous progesterone alone or with bleomycin for 21 days. Control group received only Phosphate buffered saline PBS. After 28 days, under lethal anesthesia skin and lung tissues were harvested for histological assessment and hydroxyproline measurement. Apoptosis in tissue sections was detected by TUNEL assay technique. Bleomycin administration induced fibrosis in skin and lung tissues. Severe apoptosis was seen in skin and lung tissues of the bleomycin-treated group (p<0.001 in the skin and p<0.05 in the lung). Progesterone injection either in the skin (p>0.05) or in the lung (p>0.05) did not alter apoptosis in bleomycin-treated animals. Our data confirm the role of apoptosis in the pathogenesis of fibrosis in this model; however, progesterone does not affect cellular apoptosis in skin and lung tissues of bleomycin-injured animals.
Systemic sclerosis (SSc) is the fibrotic autoimmune disease with a higher incidence in women. Lung fibrosis is the most common cause of death in SSc patients. Sex steroids have crucial role in the induction of autoimmune diseases. Progesterone impacts autoimmunity by direct action on parenchymal cells or through its immunomodulatory effect. This study aimed to investigate the effect of progesterone on the cellularity of airways in an animal model of systemic sclerosis. 6 groups of mice were considered in this study. Systemic sclerosis (SSc) was induced in female BALB/c mice by subcutaneous injection of bleomycin for 28 days. For evaluating the effect of Progesterone in SSc model, Progesterone was administered subcutaneously parallel with bleomycin for 28 days or one week after the first administration of bleomycin for 21 days. Further, three control groups were included in this study. On day 29, under lethal anesthesia bronchoalveolar lavage (BAL) was collected and evaluated for cellularity. Our results indicate the increment of cells in BAL of SSc (P<0.0001) mice. Administration of Progesterone for 28 days significantly reduced the infiltrating cells in BALs (P<0.01) of SSc mice. The differential count of BALs indicates that Progesterone reduced the number of lymphocytes (P˂0.05) in SSc mice but did not affect the number of macrophages. Therefore, we conclude that progesterone reduced the inflammatory cells in airways by decreasing the number of lymphocytes.
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