Undiagnosed and untreated non-alcoholic fatty liver disease (NAFLD) can lead to the development of many complications, such as cirrhosis, hepatocellular carcinoma, or cardiovascular diseases. Obese people are at increased risk of developing NAFLD. Due to the current lack of routine diagnostics, it is extremely important to look for new diagnostic methods and markers for this disease. The aim of this study was to assess the concentration of selected pro-inflammatory adipokines and cytokines in the unstimulated saliva of obese people with fatty liver disease in various stages (with or without slight fibrosis) and to analyze them for possible use as early markers of NAFLD diagnosis. The study involved 96 people who were divided into 5 groups based on the criterion of body mass index (BMI) and the degree of fatty liver (liver elastography). There were statistically significant differences between the groups in the concentrations of MMP-9 (matrix metalloproteinase 9), resistin, and IL-1β (interleukin 1β) in saliva. Statistically significant, positive correlations between hepatic steatosis and the concentration of MMP-2 (matrix metalloproteinase 2), resistin, and IL-1β in saliva were also found. Statistically significant positive correlations were also found between the concentration of resistin in saliva and the concentration of ALT (alanine aminotransferase) and GGTP (gamma-glutamyl transpeptidase) in serum. MMP-2, IL-1β, and resistin may be potential markers of NAFLD development, assessed in saliva. However, further research is needed because this is the first study to evaluate the concentrations of the selected pro-inflammatory parameters in the saliva of patients with NAFLD.
Keywords: NAFLD biomarkers; NAFLD diagnosis; interleukin 1 β (IL-1β); matrix metalloproteinase 2 (MMP-2); matrix metalloproteinase 9 (MMP-9); non-alcoholic fatty liver disease (NAFLD); obesity; pro-inflammatory cytokines; resistin; saliva.