Multiple sclerosis is a complex autoimmune disease characterized by chronic inflammation, demyelination, and neurodegeneration within the central nervous system (CNS). It affects over 2.8 million people worldwide and poses significant challenges to patients, healthcare providers, and researchers alike (31, 32).
The clinical course of MS can be classified into different subtypes, including RRMS, SPMS, PPMS, and PRMS, each with its own distinct features (7, 33).
The pathophysiology of MS involves a dysregulated immune response, leading to the infiltration of autoreactive T-cells and B-cells into the CNS. These immune cells initiate an inflammatory cascade that damages the myelin sheath surrounding nerve fibers, resulting in impaired nerve conduction and neurodegeneration(34, 35). The etiology of MS is multifactorial, involving a combination of genetic susceptibility and environmental triggers (36). Various genetic variants have been associated with an increased risk of developing MS, and several environmental factors, such as infections, vitamin D deficiency, and smoking, have been implicated in its pathogenesis (37, 38).
It is anticipated that this study will uncover novel insights into the factors that contribute to the progression and severity of MS. By identifying these factors, we hope to enhance our understanding of the disease's underlying mechanisms and potentially identify targets for intervention and management. Ultimately, this research has the potential to improve patient care and contribute to the development of personalized treatment approaches for individuals with MS. In our study, we have shown that although there is a vast amount of difference between SPMS and PPMS in many aspects, we have found 14 common PPI in both diseases, which shows that there are many similarities between them in the lethality of the disease. Eight of these PPI have been introduced as key factors in MS in the previous studies (Table 1 provides the DOI of related papers). In addition, we have introduced six novel entities and discussed their relation to MS.
Table 1
Common PPI related to SPMS and PPMS
PPI | Full name | Function | Literature evidence |
MSN | Moesin | cell adhesion and signaling | 10.3389/fimmu.2021.640778 |
ROS1 | ROS proto-oncogene 1, receptor tyrosine kinase | protein kinase | 10.1039/c6md00643d |
CD4 | Cluster of Differentiation 4 | T-cell activation and immunity | 10.1016/j.it.2004.01.007 |
NR4A1 | Nuclear receptor subfamily 4 group A member 1 | Transcriptional regulator, cell differentiation | 10.4103/1673-5374.339492 |
LCP1 | Lymphocyte cytosolic protein 1 | Actin cytoskeleton regulation | 10.1002/pmic.201800355 |
S100A9 | S100 calcium-binding protein A9 | Inflammatory protein regulation | 10.1111/jcmm.15928 |
AIF1 | Allograft inflammatory factor 1 | Inflammatory response regulation | 10.1016/j.nbd.2009.11.014 |
CD44 | Cluster of Differentiation 44 | Cell adhesion molecule and hyaluronan receptor | 10.4049/jimmunol.1004043 |
GNL3 | G protein nucleolar 3 | Ribosome biogenesis regulation | This study |
PLEC | Plectin | Cytoskeletal protein organization | This study |
C1R | Complement C1r subcomponent | Initiates complement activation | This study |
C1S | Complement C1s subcomponent | Initiates complement activation | This study |
SERPING1 | Serpin family G member 1 | Regulates complement system activity | This study |
ITGB4 | Integrin subunit beta 4 | Cell adhesion, signaling | This study |
MSN (Table 1), an actin-binding protein, has emerged as a key player in MS pathogenesis. It contributes to the migration and activation of immune cells, particularly T cells, facilitating their infiltration into the CNS. This infiltration is a pivotal step in initiating the inflammatory response observed in MS (39). ROS1 (Table 1), a receptor tyrosine kinase, holds promise as a potential target in MS. Its signaling pathways are implicated in the activation and proliferation of immune cells, exacerbating the inflammatory cascade within the CNS(40). CD4+ T cells have long been recognized as key drivers of autoimmune responses in MS. These cells, expressing the CD4 surface glycoprotein, release pro-inflammatory cytokines and chemokines, promoting the recruitment and activation of other immune cells (41). NR4A1(Table 1), also known as Nur77, acts as an orchestrator of immune responses. In MS, NR4A1 regulates the activation and survival of autoreactive T cells, contributing to disease progression. Exploring the intricate balance of NR4A1-mediated signaling pathways may uncover novel therapeutic avenues for MS treatment (42). S100A9 (Table 1), a calcium-binding protein expressed in myeloid cells, plays a prominent role in MS pathology. Its contribution lies in the recruitment and activation of immune cells, further fueling inflammation and tissue damage in the CNS. S100A9 is implicated in the recruitment and activation of immune cells, particularly myeloid cells, in MS. This protein contributes to the perpetuation of inflammation within the CNS, leading to tissue damage and neurodegeneration observed in MS (43). LCP1 (Table 1), through its role in cytoskeletal rearrangement and cell motility, influences the migration and infiltration of T cells into the CNS in MS. The infiltration of immune cells, facilitated by LCP1, contributes to the formation of inflammatory lesions and the destruction of myelin, resulting in neurological dysfunction (44). AIF1 (Table 1) is expressed in activated microglia, the resident immune cells of the CNS. In MS, AIF1 expression is upregulated within demyelinated lesions. Activated microglia expressing AIF1 contribute to the inflammatory response and neurodegenerative processes, further exacerbating the progression of MS (45). CD44 (Table 1) is involved in immune cell adhesion and migration. In MS, upregulated CD44 expression facilitates the transmigration of immune cells across the blood-brain barrier and their infiltration into the CNS. This immune cell infiltration contributes to the inflammatory response and subsequent tissue damage in MS (46).
Furthermore, by comparing the two types of MS, we predicted 15 TFs that might be the essential component in MS. Seven of these TFs had been explained in previous investigations, while eight of them have never been examined (Table 2).
Table 2
Common TF related to SPMS and PPMS
TF | Full name | Function | Literature evidence |
TCF21 | Transcription factor 21 | Cardiac development regulator | This study |
TRIM28 | Tripartite motif-containing 28 | transcriptional repressor | This study |
DROSHA | Drosha ribonuclease III | mediates primary microRNA processing | This study |
ZNF217 | Zinc finger protein 217 | Transcriptional regulator of oncogenesis | This study |
SR1 | Serine/arginine-rich splicing factor 1 | Hormone-responsive gene regulation | This study |
ESR2 | Estrogen receptor 2 | Hormone-responsive gene regulation | This study |
BCAT | Branched-chain amino acid transaminase | Catalyzes amino acid metabolism | This study |
RACK7 | Receptor for activated C kinase 7 | Regulation of protein translation | This study |
NR1H3 | Nuclear receptor subfamily 1 group H member 3 | Cholesterol metabolism regulation and homeostasis | 10.1016/j.neuron.2016.04.039 |
RELA | V-rel avian reticuloendotheliosis viral oncogene | Regulates NF-κB signaling pathway | 10.1016/j.jneuroim.2018.04.002 |
BP1 | Homeobox protein DLX6BP1 | Neural development and differentiation | 10.1016/j.neucli.2022.02.002 |
SPI1 | Spi-1 proto-oncogene | Regulates myeloid cell differentiation | 10.1093/brain/awu408 |
BACH1 | BTB domain and CNC homolog 1 | Regulates gene expression and stress response | 10.1016/j.neuron.2021.12.034 |
TP53 | Tumor protein p53 | Tumor suppressor | 10.3390/ijms19113652 |
ERG | ERG, ETS transcription factor | Endothelial Cell Differentiation and Angiogenesis | 10.1080/08820139.2018.1433203 |
In the following section we discuss the possible role of the MS related TFs in details. NR1H3 (Table 2), also known as LXRA (Liver X Receptor Alpha), is a transcription factor that plays a significant role in regulating lipid metabolism and immune responses. It has been implicated in the pathogenesis of MS due to its involvement in modulation of inflammatory processes and lipid homeostasis within the CNS. Dysregulation of NR1H3 signaling has been associated with altered immune cell function and inflammation, contributing to MS pathology (47). RELA (Table 2) is a subunit of the NF-κB transcription factor complex that regulates numerous cellular processes, including inflammation, immune responses, and cell survival. In the context of MS, RELA plays a crucial role in orchestrating the immune response and promoting inflammation within the CNS. Dysregulated RELA signaling can contribute to the chronic inflammatory state observed in MS and the subsequent damage to myelin (48). BP1 (Table 2), also known as DLX4 (Distal-less Homeobox 4), is a transcription factor belonging to the homeobox gene family. While the direct involvement of BP1 in MS is not well-established, studies have shown its dysregulation in other autoimmune diseases. BP1 may influence immune cell development and function, potentially impacting the immune response in MS. Further research is needed to elucidate the specific role of BP1 in MS pathogenesis (49). SPI1 (Table 2), also known as PU.1, is a transcription factor essential for the development and function of hematopoietic cells, including immune cells. SPI1 plays a critical role in regulating immune cell differentiation, activation, and inflammatory responses. Dysregulated SPI1 activity has been associated with autoimmune and inflammatory diseases, including MS. Altered SPI1 expression may impact immune cell function and contribute to the immune dysregulation observed in MS (50). BACH1 (Table 2) is a transcription factor involved in cellular stress responses and oxidative stress regulation. While its direct involvement in MS is not well-elucidated, oxidative stress is known to play a role in MS pathogenesis. BACH1 may modulate oxidative stress levels and influence immune cell function in MS. Further investigation is necessary to determine the precise role of BACH1 in MS (51). TP53 (Table 2), commonly referred to as p53, is a well-known tumor suppressor protein involved in cell cycle regulation, DNA repair, and apoptosis. In the context of MS, TP53 may have a dual role. On the one hand, TP53 activation can trigger apoptosis of autoreactive immune cells, helping to control the autoimmune response. On the other hand, TP53 activation may promote neuroinflammation and tissue damage. The precise involvement of TP53 in MS is complex and requires further investigation (52). ERG (Table 2) is a transcription factor involved in hematopoiesis and endothelial cell development. While its direct role in MS is not yet fully understood, ERG has been implicated in endothelial cell dysfunction and angiogenesis, processes that can contribute to immune cell infiltration and inflammation within the CNS in MS. Further research is needed to uncover the specific involvement of ERG in MS pathogenesis (53). By investigating the factors associated with early mortality in MS, we aim to provide valuable information to clinicians, researchers, and healthcare providers. Identifying these factors will not only deepen our understanding of the disease but also pave the way for further research and the development of targeted therapies. Through collaborative efforts, we can strive towards better outcomes and improved quality of life for individuals living with MS.