In genetically predisposed individuals, many pathogenic pathways are initiated by environmental variables, such as infectious agents, and the presentation of BD is linked to the interaction between the immune system and genetic background [18]. It is crucial to look for a biomarker for illness diagnosis or prognosis due to the implications and complications of BD, which can cause some patients to become disabled or die, as well as the lack of sensitive diagnostic laboratory tests. As far as our awareness, this is the initial investigation looking into how miR-146a and LXRβ are expressed in Egyptian cases with BD as well as evaluating any potential associations with disease activity and clinical presentation .

The crucial role that miRNAs play as important regulators of biological processes connected to the pathogenesis of several autoimmune illnesses has been established by numerous research [19]. According to this research, the expression of the miR-146a gene was lower in Behçet’s disease than in healthy controls (Fig. 4). EL Khateeb et al. [2] demonstrated that BD Egyptian patients showed a significantly lower miR-146a gene expression than control subjects which corresponds to the findings of our study. Moreover, Emara et al. [11] reported that with BD, miR-146a exhibited a protective relationship. In contrast, Kolahi et al. [20] indicated that the expression of miR-146a did not significantly differ between controls and BD cases. This can be explained by, miR-146a diminishes the level of TNF receptor-associated factors (TRAF6), NF-κB, and interleukin (IL)-1 receptor-associated kinase 1. This affects the immune response in BD. Therefore, it is rational that miR-146a decrease enhances the immune response (increases TRAF6 and NF-κB) and causes BD [9]. A past study by Pockar et al. [21] found an association of miR-146a with Behçet’s disease and reduced expression of miR-146a and IL17, TNFα and IL1β in individuals with Behçet’s disease. They found that miR-146 and erythroblast transformation specific 1 (ETS-1) were associated with childhood uveitis. An association was found between miR-146 and microvascular leakage .

Expression level of miR-146a among the studied groups

MiR-146a serum expression levels and disease activity in our study differed significantly, as measured by the BDCAF Patients Index Score: the greater the biomarker level, the lower the disease activity, and vice versa. Between miR-146a and the BDCAF Patient's Index, a strong negative correlation was discovered. In line with the study's results, Abdelaleem et al. [8] and Chen et al. [22] demonstrated that miR-146a relates to mouth ulcers and eye disease. According to Shaker et al. [9], concerning miR-146a, there was evidence of a strong correlation between patients and degree of BDCAI activity. Opposed to our study, El Khateeba et al. [2] demonstrated that neither BDCAF nor the different clinical symptoms of BD cases exhibited a strong relationship with miR-146a expression. The elevation of NF-κB, tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6), and interleukin-1 receptor-associated kinase 1 (IRAK1) is linked to inflammatory symptoms when human miR-146a is downregulated, which can activate the transcription of many inflammatory reaction-related genes  [23].

In our study, LXRβ gene expression was markedly diminished in Behçet’s disease than in healthy controls. Similarly, Wu et al. [24] showed that LXRβ mRNA expression in peripheral blood mononuclear cells (PBMC) and LXRβ protein expression in purified CD4 + T cells both considerably reduced in active BD cases as contrasted to healthy controls. Wu et al. [25] demonstrated that after LXRβ activation, the frequency of Th17 and Th1 cells as well as the related cytokines, IL-17 and IFN-γ, were all reduced. LXRβ regulated the phosphorylation of NF-κB to regulate inflammation-causing cytokine generation.

In this research, there was a significant relationship between LXRβ serum expression levels and disease activity, as determined by the BDCAF Patients Index Score: the greater the biomarker level, the lower the disease activity and vice versa. A negative significant correlation was found between LXRβ and BDCAF Patient's Index. Consistent with the study's findings, Wu et al. [24] showed an association between reduced LXRβ gene expression and disease activity in BD as lower LXRβ activation could lead to elevated immunological response of Th1 and Th17. A function for LXRβ in the development of these disorders is supported by the fact that LXR expression did not decrease during quiescence, but rather only in cases with active ocular inflammation suffering from uveitis.

Among individuals with Behçet’s disease, there was a strong positive correlation between miR-146a and LXRβ in the current research. Through decreasing the expression of IRAK1, miR-146a decreases NF-κB [25]. For comparing the diagnostic value of miR-146a and LXRβ, we utilized ROC curve analysis (Table 5). Diagnostically, both miR-146a and LXRβ are significant predictors of BD, but miR-146a functions better as a potential biomarker for diagnosing BD.

In our study, where BCDAF score is the dependent variable for univariate regression; the results indicated that a  negative correlation between BCDAF score and miR-146a, LXRβ. Thus, by univariate regression, we reported that miR-146a and LXRβ were found as risk factors for the severity of Behçet’s disease by BDCAF score. Aligning with our study, Hou et al. [26] showed that the length of the disease, white blood cells, hemoglobin, platelets, CRP, ESR, and red blood cells were the variables at risk for illness activity. In disagreement with our study, the neutrophil-to-lymphocyte ratio (NLR) was also a risk factor.

The reason for discrepancies between the results of the current study and some prior research could be attributed to various factors such as patient environmental factors, clinical manifestations, disease severity and activity, immunosuppressive treatment duration and effect, and ethnicity.

Regarding the study's shortcomings, only a small number of patients were included, and it took place in just one location. The subjects who satisfied the qualifying requirements were added, enabling the comparison of groups that were well matched. Notwithstanding these drawbacks, this is among the first research to assess the miR-146a and LXRβ biomarkers in Behçet’s disease patients simultaneously. It is advised that these results be verified in additional research with a bigger sample size.