Strong evidence indicates that chronic inflammation triggers fibrosis, which, once established, may progress independently. Furthermore, recent studies suggest that the epithelial to mesenchymal transition (EMT) process is involved in fibrosis onset as a result of chronic inflammation. Thus, a strict relationship seems to be established between fibrosis, chronic inflammation and EMT.
ZNF281 has been characterized as an EMT-inducing transcription factor (EMT-TF), suggesting its involvement in regulating pluripotency, stemness, and cancer. Several authors report that ZNF281 is a direct SNAIL target required for SNAIL-induced EMT and that it is phosphorylates by glycogen synthase kinase 3ß (GSK-3ß) to be then selectively ubiquitinated and degraded.
In a preliminary study, we demonstrated for the first time a role of ZNF281 in intestinal chronic inflammation. The aim of present study is to investigate the role of ZNF281 in the onset and progression of intestinal and liver fibrosis through in vitro, in vivo and ex vivo analyses. More specifically, we will assess the expression levels of ZNF281 pathway in gut and liver cell lines (human colorectal fibroblast adherent cell line (CCD-18Co), hepatic stellate cells (HSC) LX2 and murine embryonic fibroblast (MEF)) as well as the effect of ZNF silencing on fibrotic genes. Moreover, we will use two animal models of Cronh¿s disease (CD) and non-alcoholic steatohepatitis (NASH) to induce fibrosis and analyze the expression levels of ZNF281 pathway and fibrotic genes. Finally, the same analyses will be performed in intestinal and hepatic biopsy specimens of pediatric patients affected by structuring CD and NASH.
The identification of transcription factor ZNF281 as a novel player of fibrogenesis in the intestinal and hepatic tissue affected by chronic inflammation will allow a deeper comprehension of the pathogenetic mechanisms involved in fibrogenesis and will provide a new tool for the treatment of fibrosis in NASH and CD.
Fibrosis is known to follow chronic tissue inflammation and ultimately lead to organ scarring and subsequent loss of function. Fibroproliferative disease may affect almost all tissues and organs, including the skin, kidneys, lungs, cardiac and vascular systems, eyes, liver, pancreas and intestine. Tissue fibrosis is a leading cause of morbidity and mortality. It has been estimated that 45% of deaths in Western Countries can be attributed to fibrotic disorders (J Pathol. 2008;214:199¿210).
Currently, the molecular mechanisms regulating tissue fibrosis remain incompletely understood and established targeted therapeutic strategies are still unsettled, particularly in the pediatric disease. In general, the fibrotic process in early-onset inflammatory chronic disease, including IBD and NASH, remains under-studied, under-recognized and, potentially, undermanaged. Therefore, there is a broad consensus about the central need to explore the peculiarities of the pediatric/adolescent disease that deserve specific consideration and management.
Intestinal fibrosis is a highly complex process involving the dynamic actions of numerous molecules which are able to regulate activation of ECM-producing cells during tissue damage and repair. It appears to be widely accepted that chronic intestinal inflammation invariably leads to fibrosis. However, this process does not occur in all patients, indicating that distinct mechanisms of inflammation and restitution/fibrosis exist. It is crucial to explore this area since various pathways could be targeted separately, which would thus allow tailored treatment for wound healing abnormalities, especially in IBD.
Similarly, hepatic fibrosis is an integral part in the progression of chronic liver disease, ultimately leading to cirrhosis and hepatocellular carcinoma. Recently, the increasing prevalence of obesity and the metabolic syndrome has resulted in increasing incidence of cirrhosis secondary to nonalcoholic fatty liver disease (NAFLD), especially in developed countries. A central issue in this field relates to the identification of those factors that trigger inflammation, thus fuelling the transition from nonalcoholic fatty liver to NASH, that is featured by progressive fibrosis. Thus, considerable efforts are currently devoted to liver fibrosis research, not only with the goal of further elucidating the molecular mechanisms that drive this disease, but equally in view of establishing effective diagnostic and therapeutic strategies. Indeed, it is clear that there is an urgent need for new therapies for the treatment of liver fibrosis as well as for novel strategies to monitor the severity of the disease. This has been, and still is, a major driver for many fundamental and translational researchers in the hepatology field to devote their work to liver fibrosis.
In summary, strong evidence indicates that chronic inflammation triggers fibrosis, which, once established, may progress independently. Available anti-inflammatory drugs have been shown to be ineffective in the prevention and treatment of the fibrosis. It is critical to elucidate the cellular signals promoting fibrogenesis that act independently of inflammatory pathways and immuno-inflammatory response. Definition of the cellular and molecular mechanisms involved in intestinal and liver fibrosis may provide the key to developing new therapeutic approaches.
In a preliminary study, we found that a member of the ZNFs family, the transcription factor ZNF281, is strongly implicated in the onset and development of intestinal inflammation. Moreover, our data gave rise the possibility of a further function of this protein in the activation of the fibrotic process, also considering its well-known role as an EMT-transcription factor. Indeed, recent evidences support the view of a strict relationship between EMT and inflammation-induced fibrosis. The present study will allow to explore the potential of ZNF281 as a new player in intestinal and liver fibrosis through a wide experimental set. Indeed we will use in vitro, in vivo and ex vivo experimental models. About that, we will use, other that established cell lines, two mouse models, the DSS-colitis mouse model and the high fat diet mouse model, that are considered very helpful for the study of fibrogenesis in IBD and NASH, respectively. But more importantly, we will have biopsy samples from gut and liver fibrotic tissues of children with CD and NASH, that provide a unique tool to analyze the alterations of genes/proteins potentially implicated in this aspect of the disease.
In conclusion, the identification of the transcription factor ZNF281 as a novel player of fibrogenesis in the intestinal and hepatic tissue affected by chronic inflammation will allow a deeper comprehension of the pathogenetic mechanisms involved in fibrogenesis and will provide a new target for the treatment of fibrosis in NASH and CD.