Despite a great deal of research in the past, there is still no proper treatment for patients with MS, but researchers suggest a genetic effect on the etiology of the disease (19). Previous Studies have also discriminated that autoimmune diseases are more common in first-degree relatives of patients with MS, which is also observed in our familial MS cases, Genetically predisposed along with environmental factors are also effective factors in causing autoimmune diseases (20). In 2006, the coexistence of AIDS in patients with familial MS was reported in 64% of first-degree relatives (21). Despite previous researches, a study conducted in the Netherlands examined 115 families with familial MS, however, AIDS was not common in MS patients or their first-degree relatives (22). Therefore, further studies are needed to investigate the association of familial MS and the frequency of AIDs. The pathogenesis of multiple sclerosis consists of an inflammatory and neurodegenerative phase (23).
A member of the type Ι cytokine receptor family is IL7R. As mentioned before, the IL7R-IL7Rα ligand-receptor pair play an important role in the survival and proliferation of B and T lymphocytes, and their genetic variations could lead to the immunodeficiency syndromes (24). IL7R is located on chromosome 5pl3, and a region occasionally suggested to be linked to MS disease (25). Previous studies have shown that IL7R can interact with Thymic Stromal Lymphopoietin (TSLP), and activate CD11e + dendritic cells that lead to the production of type 2 helper T cell (Th2) cytokines. Th2 cells are believed to confer an anti-inflammatory response, and have been associated with decreasing inflammation and amelioration of MS patients clinical signs (26). Therefore, IL7R plays a significant role in the differentiation of helper T cells, and a decrease in this gene decreases anti-inflammatory cytokines and increases inflammatory cytokines (27). In 2013, the association between IL7R and the genetic cause of MS was first discovered. No validated genes have been reported since the publication of HLA associations in the early 1970s. In fact, previous studies have shown that IL7R is the first non-HLA gene to be identified in MS. The identification of IL7R has made great strides in understanding the MS genetic risk factors (28). Increasing evidence has shown that this gene also promotes oligodendrocyte survival and myelination (29). Lei et al, have used metronidazole-induced demyelination in a transgenic zebrafish line in which oligodendrocytes expressed green fluorescent protein (GFP). Their results demonstrated a decrease in IL7R expression that induced JAK/STAT signaling pathway leading to oligodendrocytes apoptosis. These findings highlight the role of IL7R in the demyelination that is important in the pathogenesis of MS (30), and increase the need to investigate the expression of IL7R in patients with MS.
The results of comparing the gene expression in our four study groups showed that the IL7R was significantly decreased in the sporadic patients versus FDR, control, and also familial groups. Since there is a significant differential expression between the sporadic and familial group, it is expected that familial patients do not have a significant difference in expression with FDR and control groups, and the results could directly confirm this. Thus, it could be said that this decrease in the IL7R expression might be significantly associated with sporadic MS patients. Also the results showed that the expression level of IL7R in all patients was significantly decreased compared with all healthy individuals. This expected decrease in expression appears to lead to a decrease in anti-inflammatory cytokines, followed by the onset or exacerbation of MS symptoms. Investigation of the IL7R gene expression in MS patients in Australia, in 2005, showed a down-regulation in PPMS, and an up-regulation in SPMS compared to the controls (31). In 2018, a Bioinformatics study has identified miR-199a and miR-142-3-P as crucial biomarkers in MS due to targeting the pivotal susceptibility genes, in particular KRAS and IL7R. They also examined IL7R expression in a small population of MS and control patients (15 MS, 14 controls) and reported an increased expression of this gene, which contradicts our study (32).
Wnt signaling pathway plays a key role in activating the myelination process as well as the differentiation and formation of oligodendrocytes. Therefore, it can be said that it is one of the key pathways in the MS disease. This pathway is also necessary for the maturation of the brain cells and is effective in reducing the penetration of immune cells. Besides, activation of Wnt/ca2+ pathway regulates cytokine production in T cells (33). Previous studies have also suggested the role of the Wnt pathway in the development and oligodendrocytes re-myelination. Therefore, this pathway can be targeted as a potential and effective treatment for MS patients (34). The Wnt/ca2+ pathway is activated through the Nuclear Factor of Activating T-cell (NFAT). NFATc2 is a member of the nuclear transcription factor activating a family of T cells, and is one of the Wnt/ca2+ pathway genes, which transmits to the nucleus via dephosphorylation by calcineurin. As a result, it activates the Wnt/ca2+ pathway target genes (35). An experiment in NFATc2 knockout mice indicated an increase in immune responses, as well as the production of cytokines in T cells (17). In contrast, in Mast cells, a significant decrease in production of cytokines and delayed inflammatory responses is a consequence of NFATc2 deficiency. The induction of EAE in NFATc2 knockout mice causes a markedly reduced clinical score, compared to wild-type animals (36). According to these studies, it seems that NFATc2-suppression can be considered as a potential disease-modifying treatment for MS patients. Thus, it would be expected that the expression level of NFATc2 is increased in MS patients compared with controls. In the present study, the relative expression level of NFATc2 is up-regulated significantly between sporadic and also familial groups, compared with FDR and control groups. The results of our study indicated that the expression of NFATc2 is not significantly different between sporadic and familial patients, and therefore the NFATc2 cannot act as a marker in distinguishing familial and sporadic forms. However, since NFATc2 expression in familial patients has changed significantly compared to their first-degree relatives, this gene can be considered as a possible prognostic marker in affected families. As expected, NFATC2 mRNA level was also up-regulated in all MS patients versus all controls.
RNF213 is located on chromosome 17 and is one of the genes involved in the inflammatory pathways, such as Wnt/ca2. This gene is expressed in most tissues of the body, but its physiological function is still much unknown. RNF213 encodes a unique, 591-KDa protein with both a ring finger domain and walker motifs (37). Ring-based E3 ligases have been linked to the control of many cellular processes, including proteasome-dependent proteolysis, immunological processes and transcription (38). Therefore, RNF213 is an ATPase and E3 ubiquitin ligase protein, which targets NFATc2 proteasomal degradation, attenuating the non-canonical Wnt/ca2+ pathway. As a result, RNF213 deficiency has been shown to trigger an increased expression of NFAT target genes (39). Thus, because the expression of the NFATC2 increased in the pathways leading to MS, the expression of the RNF213 gene is expected to decrease. In the present study, RNF213 expression was significantly increased in familial MS compared with the control group, which is in contrast to the expected result. However, since no studies have been found to investigate the expression of the RNF213 in MS versus healthy controls so far, the results of the study do not seem very unpredictable, and by examining this gene in different populations and in a larger statistical community, we will achieve more reliable results. We could only find one study that investigated the association of RNF213 with MS pathogenesis, which was conducted in 2021. In this study, multiple variants in several genes, including RNF213, were introduced as an effective factor in the development of MS (40).
This work is the first study that has examined the expression of NFATc2 and RNF213 among MS patients versus controls, and also the first study to investigate the expression of IL7R, NFATc2 and RNF213 among MS groups with genetic classification. However, this research also has some limitations, which can be pointed out by the small statistical population of the participants. Further studies in a larger group are necessary to determine whether IL7R, NFATc2 and RNF213 can be used as biomarkers for the prognosis of MS.