NAFLD is a liver disease that can cause a variety of diseases. It is necessary to diagnose NAFLD early and explore hub genes. From the perspective of computational biology, this paper explored the molecular mechanism of NAFLD related to pyroptosis and the relationship between three hub genes associated with NAFLD/ healthy obesity and diagnosis and immune infiltration. 25 DEGs related to pyroptosis were obtained by differential expression analysis of the training set and their involved pathways were analyzed in detail.
To the results of BP enrichment, Yang et al. explored the hepatoprotective effect of quercetin in T2DM-induced NAFLD and its mechanism, establishing in vivo and in vitro quercetin treatment models. Their results showed that quercetin significantly attenuated the production of interleukin-1β, interleukin-6 and TNF-α induced by T2DM [8]. Marina et al. identified innate immune cells, including neutrophils, as central regulators of NASH-related inflammation [9]. Regarding the CC enrichment results, Muhammad et al. demonstrated that membrane remodeling is a key factor in the hepatotoxicity of obese zebrafish larvae induced by the co-exposure of benzo [a] pyrene and ethanol [10]. Minxuan et al. found that E3 ubiquitin-protein ligase Trim31 could alleviate non-alcoholic fatty liver disease by targeting Rhbdf2 in mouse hepatocytes [11]. David et al. demonstrated that activation of NOD-like receptor protein 3 causes spontaneous inflammation and fibrosis in the liver [12].
Furthermore, the RF algorithm was used to obtain the 25 DEGs weights. We selected the Top 3 weighted genes for subsequent analysis. The literature review showed that all three hub genes are closely related to NALFD. Nassim et al. found that IL32NAFLD was associated with body mass index, waist circumference, NAFLD activity score, transaminase, and patient homeostasis model assessment index for insulin resistance. Moreover, treatment of control human hepatocytes with recombinant IL32 resulted in insulin resistance, the hallmark metabolic dysregulation in NAFLD hepatocytes. This finding confirmed that IL32 has a crucial role in the pathogenesis of NAFLD [13]. By weighted co-expression network analysis, Xu et al. identified IL32 as a common potential therapeutic target for NAFLD and periodontitis [14]. The review by Cristiana et al. summarized IL32 as a possible mediator linking lipotoxicity to inflammation and liver disease [15]. Guido et al. sequenced the liver transcriptome of 125 obese individuals and found that IL32 was overexpressed in NAFLD patients. IL32 is not only related to liver fat and liver injury but also has a significant independent correlation with NAFLD [16]. Nonalcoholic steatohepatitis (NASH) results from further disease progression in patients with NAFLD. For TREM2, Erica et al. showed TREM2 in mice with SB3 overexpression in hepatocytes with NASH [17]. In addition, the role of PANX1 in the progression of NAFLD needs to be further confirmed.
Finally, we used the three hub genes to construct diagnostic models of NFLD separately and jointly. We explored the correlation between hub genes and 22 immune cell levels in the immune microenvironment. We found that multiple immune cells were significantly different between the two groups of healthy obesity and NALFD, and the three Hub genes strongly correlated with multiple immune cells. For example, Yuzo et al. showed that CD8 tissue-resident memory T cells promote liver fibrosis regression by inducing apoptosis of hepatic stellate cells [18]. Zhou et al. found that the relationship between neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) and NAFLD was nonlinear. In addition, PLR ≥ 42.29 may be a protective factor for NAFLD, while NLR < 1.23 may be a risk factor for NAFLD [19]. The study by Song et al. found a significant reduction in activated neutrophils, macrophages M2, M0, and dendritic cells after bariatric surgery (BS). This study revealed the underlying immune mechanism of BS and is a promising biomarker to distinguish the severity of NAFLD [20].