Toll-like receptors (TLRs): An old family of immune receptors with a new face in cancer pathogenesis.

In the dark path of tumorigenesis, the more carefully the cancer biology is studied, the more brilliant answers could be given to the countless questions about its orchestrating derivers. The identification of the correlation between Toll-like receptors (TLRs) and different processes involved in carcinogenesis was one of the single points of blinding light highlighting the interconnection between the immune system and cancer. TLRs are a wide family of single-pass membrane-spanning receptors that have developed through the evolution to recognize the structurally conserved molecules derived from microorganisms or damaged cells. But this is not everything about these receptors as they could orchestrate several downstream signalling pathways leading to the formation or suppression of cancer cells. The present review is tempted to provide a concise schematic about the biology and the characters of TLRs and also summarize the major findings of the regulatory role of TLRs and their associated signalling in the pathogenesis of human cancers.

Tuberculosis comorbidity with rheumatoid arthritis: Gene signatures, associated biomarkers, and screening.

Rheumatoid arthritis (RA) is known to be related to an elevated risk of infections because of its pathobiology and the use of immunosuppressive therapies. Reactivation of latent tuberculosis (TB) infection is a serious issue in patients with RA, especially after receiving anti-TNFs therapy. TNF blocking reinforces the TB granuloma formation and maintenance and the growth of Mycobacterium tuberculosis (Mtb). After intercurrent of TB infection, the standard recommendation is that the treatment with TNF inhibitors to be withheld despite its impressive effect on suppression of inflammation until the infection has resolved. Knowing pathways and mechanisms that are common between two diseases might help to find the mechanistic basis of this comorbidity, as well as provide us a new approach to apply them as therapeutic targets or diagnostic biomarkers. Also, screening for latent TB before initiation of an anti-TNF therapy can minimize complications. This review summarizes the shared gene signature between TB and RA and discusses the biomarkers for early detection of this infection, and screening procedures as well.

Toll-like receptors (TLRs) in cancer; with an extensive focus on TLR agonists and antagonists.

At the forefront of the battle against pathogens or any endogenously released molecules, toll-like receptors (TLRs) play an important role as the most noble pattern recognition receptors. The ability of these receptors in distinguishing "self" and "non-self" antigens is a cornerstone in the innate immunity system; however, misregulation links inflammatory responses to the development of human cancers. It has been known for some time that aberrant expression and regulation of TLRs not only endows cancer cells an opportunity to escape from the immune system but also supports them through enhancing proliferation and angiogenesis. Over the past decades, cancer research studies have witnessed a number of preclinical and clinical breakthroughs in the field of TLR modulators and some of the agents have exceptionally performed well in advanced clinical trials. In the present review, we have provided a comprehensive review of different TLR agonists and antagonists and discuss their limitations, toxicities, and challenges to outline their future incorporation in cancer treatment strategies.

The Association between the Plasma Sugar and Lipid Profile with the Gene Expression of the Regulatory Protein of mTOR (Raptor) in Patients with Rheumatoid Arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is an autoinflammatory and self-perpetuating disease with both articular and extra-articular manifestations, such as cardiovascular complications, which are the leading cause of mortality and morbidity in RA patients. Impaired sugar and lipid metabolism are considered as the critical risk factors for cardiovascular disease (CVD). Regarding the regulatory function of Raptor in the immunometabolism, in this study, we evaluated the association between plasma sugar and lipid profiles with the gene expression of Raptor and the cytokine tumor necrosis factor-α (TNF-α), as an inflammatory mediator, in peripheral blood leukocyte of RA patients. MATERIAL AND METHODS: Thirty-five RA patients who received combinational disease modified anti-rheumatoid drugs (DMARD) regimen and thirty healthy subjects enrolled in this study. The gene expression of Raptor was assessed by the real-time PCR method, and the Plasma levels of glucose and lipids, as well as TNF-α, were obtained using Hitachi device and enzyme-linked immunosorbent assay (ELISA) technique, respectively. RESULTS: The gene expression of Raptor was reduced significantly in RA patients compared to the healthy subjects (p = .001). The plasma level of HDL was significantly higher in RA patients than the control group (p = .001), while the plasma level of LDL was reduced significantly in these patients (p = .001). CONCLUSION: In our study, the reduced gene expression of Raptor may contribute to the impaired immunometabolism in RA patients, which is independent of plasma sugar and lipid profile.

IL-35, a double-edged sword in cancer.

Interleukin 35 (IL-35), a cytokine mainly produced by regulatory T cells (Treg cells), is composed of an Epstein-Barr virus-induced gene 3 ß-chain and an IL-12 p35 α-chain. IL-35 causes tumorigenicity in cancer, protects cancer cells against apoptosis, and facilitates cancer progression. However, a few reports have referred to its contradictory roles in cancer prevention. Therefore, the exact purpose of this cytokine in cancer development has become a fundamental question that needs to be answered. In this review, we explain the structure of IL-35 and its receptors and their different signaling pathways. Finally, the function of IL-35 in some cancers and the possible application of this cytokine in approaches for cancer therapy have been discussed.

Neopterin serum level does not reflect the disease activity in rheumatoid arthritis: A systematic review and meta-analysis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease caused by established chronic inflammation. Neopterin levels have extensively been considered as a marker of immune activation during inflammation. In this study, we performed a systematic evaluation and meta-analysis to elucidate the overall relationship between neopterin concentration and RA disease activity. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, a systematic review was conducted using PubMed, Google Scholar, Web of Science, and Scopus from 2000 to August 2020. The Newcastle-Ottawa scale was used to assess the quality of eligible studies. The effect size (ES) and corresponding 95% confidence intervals (CIs) were calculated to evaluate this association. A total of 15 studies out of 98 met our inclusion criteria. The pooled analysis found that patients with RA had high level of neopterin; however, no statistically significant association was found between neopterin levels with high, intermediate, and low diseases activity score (DAS)-28 (ES =11.18, 95% CI: 6.02 to 16.34, and I2 = 91.8%; and ES = 8.57, 95% CI: 6.41 to 10.37, and I2 = 99.5%; and ES =12.45, 95% CI: -1.68 to 26.58, and I2 = 99.0%, respectively). Our results indicated that the neopterin concentration does not seem to have any substantial impact on the RA disease activity.

The immunomodulatory effects of mesenchymal stromal cell-based therapy in human and animal models of systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune inflammatory disease with no absolute cure. Although the exact etiopathogenesis of SLE is still enigmatic, it has been well demonstrated that a combination of genetic predisposition and environmental factors trigger a disturbance in immune responses and thereby participate in the development of this condition. Almost all available therapeutic strategies in SLE are primarily based on the administration of immunosuppressive drugs and are not curative. Mesenchymal stromal cells (MSCs) are a subset of non-hematopoietic adult stem cells that can be isolated from many adult tissues and are increasingly recognized as immune response modulating agents. MSC-mediated inhibition of immune responses is a complex mechanism that involves almost every aspect of the immune response. MSCs suppress the maturation of antigen-presenting cells (DC and MQ), proliferation of T cells (Th1, T17, and Th2), proliferation and immunoglobulin production of B cells, the cytotoxic activity of CTL and NK cells in addition to increasing regulatory cytokines (TGF-ß and IL10), and decreasing inflammatory cytokines (IL17, INF-ϒ, TNF-α, and IL12) levels. MSCs have shown encouraging results in the treatment of several autoimmune diseases, in particular SLE. This report aims to review the beneficial and therapeutic properties of MSCs; it also focuses on the results of animal model studies, preclinical studies, and clinical trials of MSC therapy in SLE from the immunoregulatory aspect.

Association between polymorphisms of cytokine genes and brucellosis: A comprehensive systematic review and meta-analysis.

OBJECTIVE: Owing to involvement of host genetic factors in susceptibility to brucellosis infection and its outcome, this study aimed to carry out a comprehensive systematic review and meta-analysis to derive a precise evaluation of the association between the risk of brucellosis and its focal complication and all cytokines examined in case-control studies, including Interferon gamma (IFN-γ), Tumor Necrosis Factor (TNF)-α, TNF-ß, Transforming Growth Factor(TGF)-ß, IL-2, IL-4, IL-6, IL-10, IL-12B, IL-15, and IL-18 polymorphisms. METHODS: A systematic literature search in PubMed, Web of Science, Google Scholar, and Scopus was performed to identify the relevant studies, and related information was extracted. The effect size (ES) and corresponding 95% confidence intervals (CIs) were calculated to estimate the association. RESULTS: From 158 initial results, twenty-five eligible studies were included in the meta-analysis. Overall, the pooled results showed that the dominant models of IFN-γ UTR5644, TGF-ß rs1800470 and rs1800471, TNF-α rs1800629, and IL-10 rs1800872 were significantly less frequent in brucellosis patients than the controls. Also, the pooled analysis of the mutant allele vs. wild allele of TGF-ß rs1800471 and IL-10 rs1800872 showed negative association with brucellosis risk. On the other hand, our pooled analysis demonstrated that the mutant allele of IL-4 rs2243250 and IL-18 rs1946519 were associated with increased susceptibility to brucellosis. In addition, the IFN-γ UTR5644 and TGF-ß rs1800470 were more frequent in the patients without focal forms. CONCLUSIONS: IL-4 rs2243250 and IL-18 rs1946519 have a positive correlation with brucellosis whereas the IFN-γ UTR5644, TGF-ß rs1800470 and rs1800471, TNF-α rs1800629, and IL-10 rs1800872 showed a negative association with this disease. The association between the other single nucleotide polymorphisms (SNP) and brucellosis risk was not confirmed in the current meta-analysis. PROSPERO Registration: CRD42018117203.

Innate immune response in systemic autoimmune diseases: a potential target of therapy.

Innate immunity refers to defense mechanisms that are always present, ready to combat microbes and other offending agents. Innate immunity acts as a first-line defense and activates the conventional immune responses; however, it has been speculated that the importance of innate immunity in initiation and development of some disorders is more than just the "first line of defense". Autoimmune diseases, caused by immune system overactivation, are among the most challenging scientific and clinical problems, and there is still much to be learned about their pathogenesis. We aimed to provide a comprehensive overview of available documents about the role of innate immunity in systemic autoimmune diseases including rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, polymyositis, and systemic sclerosis. This study highlights the innate immunity pathways or molecules that are under investigation for therapy of these diseases.

Survivin a pivotal antiapoptotic protein in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease, pathologically characterized by lymphocyte infiltration of the synovial membrane that leads to chronic inflammation and progressive joint damage. RA develops as a result of increased cell infiltration and cell proliferation as well as impaired cell death. Activated cells in joints including lymphocytes and fibroblast-like synoviocytes (FLS) survive for a long time as a consequence of compromised apoptosis, but the mechanism underlying cell survival in synovium remains to be firmly established. Inhibition of apoptosis by survivin, as a critical antiapoptotic protein, contributes to both the persistence of autoreactive T lymphocytes and tumor-like phenotype of FLS in RA. In addition to the antiapoptotic role, survivin also has prognostic relevance in RA prodromal phase. Hence, this review provides an overview of the current knowledge regarding the involvement of survivin protein in the pathogenesis of RA.

Decreased Gene Expression of Epstein-Barr Virus-Induced Gene 3 (EBI-3) may Contribute to the Pathogenesis of Rheumatoid Arthritis.

BACKGROUND: Interleukin-35 (IL-35) is a member of the IL-12 family of heterodimeric cytokines produced by regulatory T (Treg) cells. This immunosuppressive cytokine can prevent exaggerated inflammatory responses like those responsible for the development of rheumatoid arthritis (RA). This study aims to determine the correlation between the gene expression of Epstein-Barr virus-induced gene 3 (EBI-3) and IL-12A (p35) subunits of IL-35 in peripheral blood leukocytes with immunological and clinical parameters in RA patients. METHODS: We recruited 47 patients with RA and 44 healthy subjects. The disease activity score-28 (DAS-28) was assessed by an expert rheumatologist and the plasma levels of neopterin and anti-cyclic citrullinated peptide (anti-CCP) was measured using ELISA method also Serum rheumatoid factor (RF) was assessed by the agglutination test. For the evaluation of IL-12A and EBI-3 gene expression, we used qPCR. RESULTS: We did not find any significant correlation between the gene expression of IL-35 subunits and DAS-28. There was a negative correlation between the plasma levels of neopterin and the gene expression of EBI-3 (p = 0.004). Inversely, we found a positive correlation between plasma level of anti-CCP and neopterin (p < 0.001) also between RF and DAS-28 (p = 0.001). CONCLUSION: Regarding the significant negative correlation between EBI-3 gene expression and plasma levels of neopterin, it can be concluded that the altered gene expression of EBI-3 may play a role in the pathogenesis of RA.

The impaired gene expression of adenosine monophosphate-activated kinase (AMPK), a key metabolic enzyme in leukocytes of newly diagnosed rheumatoid arthritis patients.

The disturbed immune homeostasis is involved in the pathogenesis of an array of autoimmune diseases like rheumatoid arthritis (RA). The adenosine monophosphate-activated protein kinase (AMPK) with a pivotal role in immunometabolism process, also plays a regulatory function in the immune system. This study aims to evaluate the alteration of AMPK gene expression in peripheral blood leukocytes of RA patients and its effects on disease severity as well as plasma levels of anti-inflammatory cytokines. 60 RA patients, including 30 newly diagnosed and 30 patients whose disease were under controlled with the combinational disease-modifying anti-rheumatic drug (DMARD), as well as 30 healthy subjects, were enrolled in our study. The gene expression of AMPK was evaluated using real-time PCR method. The plasma concentrations of IL-10 and TGF-ß1 were measured using sandwich ELISA. The gene expression of AMPK was significantly lower in the newly diagnosed RA patients in comparison with the control group (P = 0.049). Inversely, in RA patients who received DMARD therapy, the gene expression of AMPK was significantly higher than the control group (P = 0.003). There was no significant correlation between AMPK gene expression and plasma levels of IL-10 and TGF-ß1. The plasma levels of TGF-ß1 was significantly higher in both newly diagnosed and under-treatment patients compared with healthy subjects (P < 0.001). The impaired gene expression of AMPK in peripheral blood leukocytes and elevated levels of plasma TGF-ß1 can be contributed in RA pathogenesis.

Analysis of Helios gene expression and Foxp3 TSDR methylation in the newly diagnosed Rheumatoid Arthritis patients.

BACKGROUND: The control of auto-reactive cells is defective in rheumatoid arthritis (RA). Regulatory T (Treg) cells which play a key role in the modulation of immune responses have an impaired function in RA. Foxp3 is a master regulator of Treg cells which its expression is under the tight control of epigenetic mechanisms. In the current study, we analyzed the epigenetic modulation of the Foxp3 Treg-specific demethylated region (TSDR) and Helios gene expression to determine Treg cells alteration in RA patients. METHODS: We have recruited 20 newly diagnosed patients with RA and 41 healthy controls in our study. The measurement of Foxp3 and Helios gene expression was performed by the real-time PCR technique and the methylation level of TSDR was analyzed by bisulfite treatment and quantitative methylation-specific PCR (Q-MSP). RESULTS: We found that RA patients had significantly lower level of Foxp3 gene expression and TSDR demethylation compared to healthy subjects (P < 0.001 and P = 0.006, respectively). Inversely, the Helios gene expression was elevated significantly in RA patients group (P = 0.048). We also observed a significant correlation between Foxp3 and Helios gene expression (P = 0.016) as well as a significant correlation between FoxP3 expression and demethylation rate of TSDR (P = 0.010). CONCLUSION: Our results suggested that both epigenetic modifications and Helios gene expression may have important roles in the pathogenesis of RA through their effects on Foxp3 gene expression.

Dimethyl Fumarate Inhibits Fibroblast Like Synoviocytes-mediated Inflammation and Joint Destruction in Rheumatoid Arthritis.

Rheumatoid arthritis (RA) as a chronic inflammatory disorder affects around 1% of the world population. Fibroblast-like synoviocyte (FLS), one of the main cells in RA pathogenesis is characterized by hyperproliferation and resistance to apoptosis resulting to synovial hyperplasia. Dimethyl fumarate (DMF) has been licensed for the treatment of multiple sclerosis (MS) and psoriasis; however, its role in RA is unknown. DMF has immunomodulatory properties and may be considered as therapeutic approach in RA treatment. In this study, we aimed to investigate the effect of DMF on controlling FLS-mediated synovial inflammation and joint destruction in RA. FLSs were isolated from synovial tissues of 8 patients with RA and treated with DMF. Apoptosis rate was analyzed by Annexin V-FITC. Cell proliferation was measured by carboxyfluorescein succinimidyl ester (CFSE) dye. The matrix metalloproteinase 3 (MMP3) and NF-кB pathway protein (p65) mRNA expression were evaluated by RT-PCR. Also, the IL-6 production and lactate release were measured in FLS supernatant. DMF treatment decreased the cell proliferation and increased apoptosis in a dose dependent manner. DMF-treated FLS showed a reduction in IL-6 and lactate release. Moreover, it was revealed that DMF inhibited the expression of p65 and MMP3. Our data demonstrate that DMF treatment suppresses the aggressive and inflammatory features of RA FLSs. Our Results suggest that DMF might be expected to be evaluated as a therapy for RA.

The effect of tranexamic acid on synovium of patients undergoing arthroplasty and anterior cruciate ligament reconstruction surgery.

Preoperative hemorrhage can be reduced using anti-fibrinolytic medicine tranexamic acid (TXA). During surgical procedures, local administration is being used more and more frequently, either as an intra-articular infusion or as a perioperative rinse. Serious harm to adult soft tissues can be detrimental to the individual since they possess a weak ability for regeneration. Synovial tissues and primary fibroblast-like synoviocytes (FLS) isolated from patients were examined using TXA treatment in this investigation. FLS is obtained from rheumatoid arthritis (RA), osteoarthritis (OA), and anterior cruciate ligament (ACL)-ruptured patients. The in vitro effect of TXA on primary FLS was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assays for cell death, annexin V/propidium iodide (PI) staining for apoptotic rate, real-time PCR for p65 and MMP-3 expression, and enzyme-linked immunosorbent assay (ELISA) for IL-6 measurement. MTT assays revealed a significant decrease in cell viability in FLS of all groups of patients following treatment with 0.8-60 mg/ml of TXA within 24 h. There was a significant increase in cell apoptosis after 24 h of exposure to TXA (15 mg/ml) in all groups, especially in RA-FLS. TXA increases the expression of MMP-3 and p65 expression. There was no significant change in IL-6 production after TXA treatment. An increase in receptor activator of nuclear factor kappa-Β ligand (RANK-L) production was seen only in RA-FLS. This study demonstrates that TXA caused significant synovial tissue toxicity via the increase in cell death and elevation of inflammatory and invasive gene expression in FLS cells.

The epigenetics orchestra of Notch signaling: a symphony for cancer therapy.

The aberrant regulation of the Notch signaling pathway, which is a fundamental developmental pathway, has been implicated in a wide range of human cancers. The Notch pathway can be activated by both canonical and noncanonical Notch ligands, and its role can switch between acting as an oncogene or a tumor suppressor depending on the context. Epigenetic modifications have the potential to modulate Notch and its ligands, thereby influencing Notch signal transduction. Consequently, the utilization of epigenetic regulatory mechanisms may present novel therapeutic opportunities for both single and combined therapeutics targeted at the Notch signaling pathway. This review offers insights into the mechanisms governing the regulation of Notch signaling and explores their therapeutic potential.

Role of Frizzled receptor expression on patients' survival with gastrointestinal cancers: A systematic review with meta-analysis.

BACKGROUND: Frizzled receptors (FZD) play a pivotal role in the initiation and progression of a wide array of cancers. Dysregulated expression of FZD receptors is correlated with higher metastasis and invasive potential, as well as short survival in many malignancies. In this meta-analysis, we aimed to verify the prognostic value of FZD receptor expression on patients' survival with different types of gastrointestinal (GI) cancers, including gastric, colorectal, and esophageal cancers. METHODS: A systematic search was performed using PubMed, Scopus, and Web of Science from 2000 to November 2020. Fourteen studies, including 2997 patients met our inclusion criteria, in which nine articles were considered FZD7 while the rest were about other FZD members. The fixed-effect model was used to estimate the pooled hazard ratio (HR) and the 5-year overall survival (OS) rate. We used the Newcastle-Ottawa scale of cohort articles to determine the quality of included studies. RESULTS: The results showed that high expression of FZD receptors is associated with the poor survival in patients with GI cancers (HR= 1.83, 95% CI: 1.5-2.17). Moreover, multivariate analysis indicated that FZD receptors could be considered as an independent prognostic factor (HR = 1.76, 95% CI: 1.37-2.16). CONCLUSION: According to our results, overexpression of FZD receptors predicts a poor prognosis in patients with GI cancers and could be used as a useful therapeutic target.

Inhibitory Effects of Cold Atmospheric Plasma on Inflammation and Tumor-Like Feature of Fibroblast-Like Synoviocytes from Patients with Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a chronic, debilitating systemic disease characterized by chronic inflammation and progressive joint destruction. Fibroblast-like synoviocytes (FLSs) are one of the most important players in the pathophysiology of RA, acting like tumor cells and secreting inflammatory cytokines. Previous research has shown that cold atmospheric plasma (CAP) inhibits cancer cells and may have anti-inflammatory properties. This study examined the effects of argon plasma jet-produced CAP on the suppression of invasion and inflammation caused by cultured RA-FLS. The findings revealed that CAP reduced cell viability and elevated the percentage of apoptotic RA-FLS by producing reactive oxygen species. Carboxyfluorescein diacetate succinimidyl ester (CFSE) staining confirmed that CAP could decrease the proliferation of RA-FLS. Furthermore, CAP effectively reduced the production of inflammatory factors (e.g., NF-κB and IL-6) as well as destructive factors like receptor activator of nuclear factor kappa-B ligand (RANKL) and matrix metalloproteinases-3 (MMP-3). These data suggest that CAP could be a promising treatment for slowing the progression of RA by reducing tumor-like features and inflammation in RA-FLS.

Advanced glycation end products (AGEs) and its receptor, RAGE, modulate age-dependent COVID-19 morbidity and mortality. A review and hypothesis.

Coronavirus Disease 2019 (COVID-19), caused by the novel virus SARS-CoV-2, is often more severe in older adults. Besides age, other underlying conditions such as obesity, diabetes, high blood pressure, and malignancies, which are also associated with aging, have been considered risk factors for COVID-19 mortality. A rapidly expanding body of evidence has brought up various scenarios for these observations and hyperinflammatory reactions associated with COVID-19 pathogenesis. Advanced glycation end products (AGEs) generated upon glycation of proteins, DNA, or lipids play a crucial role in the pathogenesis of age-related diseases and all of the above-mentioned COVID-19 risk factors. Interestingly, the receptor for AGEs (RAGE) is mainly expressed by type 2 epithelial cells in the alveolar sac, which has a critical role in SARS-CoV-2-associated hyper inflammation and lung injury. Here we discuss our hypothesis that AGEs, through their interaction with RAGE amongst other molecules, modulates COVID-19 pathogenesis and related comorbidities, especially in the elderly.

Mesenchymal stromal/stem cells (MSCs) and MSC-derived extracellular vesicles in COVID-19-induced ARDS: Mechanisms of action, research progress, challenges, and opportunities.

In late 2019, a novel coronavirus (SARS-CoV-2) emerged in Wuhan city, Hubei province, China. Rapidly escalated into a worldwide pandemic, it has caused an unprecedented and devastating situation on the global public health and society economy. The severity of recent coronavirus disease, abbreviated to COVID-19, seems to be mostly associated with the patients' immune response. In this vein, mesenchymal stromal/stem cells (MSCs) have been suggested as a worth-considering option against COVID-19 as their therapeutic properties are mainly displayed in immunomodulation and anti-inflammatory effects. Indeed, administration of MSCs can attenuate cytokine storm and enhance alveolar fluid clearance, endothelial recovery, and anti-fibrotic regeneration. Despite advantages attributed to MSCs application in lung injuries, there are still several issues __foremost probability of malignant transformation and incidence of MSCs-related coagulopathy__ which should be resolved for the successful application of MSC therapy in COVID-19. In the present study, we review the historical evidence of successful use of MSCs and MSC-derived extracellular vesicles (EVs) in the treatment of acute respiratory distress syndrome (ARDS). We also take a look at MSCs mechanisms of action in the treatment of viral infections, and then through studying both the dark and bright sides of this approach, we provide a thorough discussion if MSC therapy might be a promising therapeutic approach in COVID-19 patients.